Gtua_2001_report.pdf

2001 Report Gas Turbine Users’ Association

GTUA Annual Meeting 14 May 2001 Banff, Alberta, Canada

The information contained in this report is both proprietary and confidential to Solar Turbines Incorporated. It is intended solely for the use of GTUA attendees and is not intended for further dissemination.

Solar Turbines Incorporated 9330 Sky Park Court San Diego, CA 92123-5398 U.S.A. Caterpillar is a registered trademark of Caterpillar Inc. Solar, Titan, Mars, Taurus, Mercury, Centaur, Saturn, Turbotronic and SoLoNOx are trademarks of Solar Turbines Incorporated. Specifications subject to change without notice. Printed in U.S.A. ã2001 Solar Turbines Incorporated. All rights reserved. GTUA2001HO/0501/5C

Solar Turbines Incorporated

GTUA 2001

Preface The following is an explanation of the system Solar Turbines adopted for identifying the models within â â our product families of Saturn , Centaur , â Mercury™, Taurus™, Mars , and Titan™ gas turbines. For each model, the product family name is followed by a model number that indicates the current configuration, such as Saturn 20. A suffix following the family name and model number designation, such as Centaur 50S, denotes whether the product is a low speed power turbine (L), marine (M), or SoLoNOx™ (S) configuration. To further identify a particular model’s build configuration, the family name, model number and suffix are followed

by a version designation, such as Centaur 40S 4700. The last digit of this number will typically be a 1 or 2, denoting single- or two-shaft gas turbine. New models that are uniquely different from Solar’s current product families will be given a new family name and model number. Uprates or modifications to existing product families will maintain their family name and model number. The current product family names and ratings are given in Tables 1 and 2. The uprate options available for Solar's twoshaft and single-shaft gas turbines are listed in Tables 3 and 4 respectively.

Table 1. Current Production Models for Compressor Set, Mechanical-Drive and Marine Applications

Product

Mechanical Rating

Thermal Efficiency, %

SoLoNOx

kW

hp

Saturn 20

1185

1590

24.5

N/A

Centaur 40

3500

4700

27.9

Yes

Centaur 50

4570

6130

30.0

Yes

Centaur 50L*

4680

6275

31.0

Yes

Taurus 60

5740

7700

32.0

Yes

Taurus 60M

5170

6935

32.0

N/A

Taurus 70

7690

10,310

34.8

Yes

Mars 90

9860

13,220

33.3

Yes

Mars 100

11 190

15,000

34.0

Yes

Titan 130

14 540

19,500

35.7

Yes

* Centaur 50 with two-stage power turbine

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Table 2. Current Production Models for Generator Set Applications Electrical Rating, kWe*

SoLoNOx

Saturn 20

1210

N/A

Centaur 40

3515

Yes

Centaur 50

4600

Yes

Mercury 50

4200

Yes

Taurus 60

5500

Yes

Taurus 70

7520

Yes

Mars 90**

9450

Yes

Mars 100**

10 690

Yes

Titan 130

14 000

Yes

Product

* **

Output at generator terminals Two-shaft gas turbines

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Table 3. Uprate Options for Compressor Set and Mechanical-Drive Applications Model

Configuration Incoming

Nominal Power, hp

Uprated

Incoming

Uprated

Mars 100

90-13000 100-14000

10-1302 10-1402 20-1602 10-1402 20-1602 20-1602 40-4502 40-4702 40L-5302 40-4702 40L-5302 40L-5302 50-5702 50-6102 50L-5902 50-5802 50L-5902 50L-5902 60-6502 60-7002 60-7302 60-7002 60-7302 60-7302 60-7802 70-9702 70-10302 70-9702 70-10302 70-10302 90-13202 100-15000 90-13202 100-15000 100-15000 100-15000

1200 1340 1450 1340 1450 1450 3950 4390 4700 4390 4700 4700 5450 5680 5680 5680 5680 5815 6200 6500 6960 6500 6960 6960 7150 8900 8900 9500 9500 9700 10,000 10,000 12,600 12,600 13,220 14,100

1340 1450 1590 1450 1590 1590 4500 4680 5240 4500 5240 5105 5680 6130 6150 5815 6150 6275 6500 6960 7150 6960 7150 7150 7700 9700 10,310 9700 10,310 10,310 13,220 15,000 13,220 15,000 15,000 15,000

Titan 130

130-18002

130-19502

18,000

19,500

Saturn 10

10-1202

10-1302

Centaur 40

10-1402 40-4002

40-4502

Centaur 50

40-4702 50-5502

50-5702

Taurus 60

50-5802 60-6202

60-6502

Taurus 70

60-7002 60-7302 70-8900 70-9500

Mars 90

70-9700 90-10000 90-12000

* Two-shaft gas turbines

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Table 4. Uprate Options for Generator Set Applications Model

Configuration

Nominal Power, kWe**

Incoming

Uprated

10-1201

10-1301

800

950

Saturn 20

20-1501

10-1401 20-1601

950 1140

1040 1210

Centaur 40

40-4001

40-4501

2880

3130

Centaur 50

40-4501 50-5501

40-4701 40-4701 50-5701

3130 3130 3880

3515 3515 4140

Taurus 60

50-5701 50-5901 60-6201

50-5901 50-5901 50-6201 60-6501

4140 4140 4345 4370

4345 4345 4600 4550

Taurus 70

60-7001 70-9701

60-7001 60-7801 60-7001 60-7801 60-7801 70-10301

4550 4950 4550 4950 4950 7150

4950 5500 4950 5500 5500 7520

Mars 90*

90-10000

90-13202

10,000

13,220

Mars 100*

90-13000 100-14000

100-15000 90-13202 100-15000 100-15000 100-15000

10,000 12,600 12,600 13,220 14,100

15,000 13,220 15,000 15,000 15,000

Titan 130

130-18001

130-19501

12,832

13,505

Saturn 10

60-6501

90-12000

* **

Incoming

Two-shaft gas turbines Output at generator terminals

FOR MORE INFORMATION Please contact: Solar’s Office nearest you or: Solar Turbines Incorporated Customer Services 9330 Sky Park Court San Diego, California 92123-5398 U.S.A. Telephone: [+1] 858-694-1661 Facsimile: [+1] 858-694-6996 Internet: www.solarturbines.com (Please refer to the list of Solar’s Customer Services offices.)

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Contents Section

Page

Preface .......................................................................................................................................................... i Message to the GTUA .............................................................................................................................. ix General Questions to Solar G-1 G-2 G-3 G-4 G-5 G-6 G-7 G-8 G-9 G-10

Experience and Training of FSRs........................................................................................1 Compression and Surge System Controls ..........................................................................6 Software Quality and Change Control ...............................................................................10 New Software Developments ............................................................................................13 Improvements in TBO .......................................................................................................18 Removal of Backup Post Lube ..........................................................................................23 Retrofit / Upgrade Configuration Control ...........................................................................25 Pancake Valve Experience................................................................................................27 Titan and Mercury Experience...........................................................................................30 New Developments ...........................................................................................................35

Mars Question M-1

Current Mars Experience...................................................................................................39

Saturn Questions S-1 S-2 S-3

Current Saturn Experience ................................................................................................42 Carbon Seal Developments...............................................................................................43 Plans for Saturn Product Line............................................................................................44

General Question to All Manufacturers GA-1

Plans for Internet Technology............................................................................................45

Appendix Reference Material .......................................................................................................... A-1 Acronyms......................................................................................................................... A-3 Solar’s Customer Services Offices.................................................................................. A-5

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Illustrations Figure

Page

General Questions to Solar 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Field Operations Organization.......................................................................................................2 Asset Management Services.........................................................................................................3 Response Center ..........................................................................................................................4 Customer Support Activity Form ...................................................................................................5 Customer Satisfaction Survey ......................................................................................................5 Anti-Surge Control Screen ............................................................................................................7 Anti-Surge Control Lines ...............................................................................................................8 Typical Anti-Surge Control Recycle Loop......................................................................................8 Recommended Valve Arrangement ..............................................................................................9 Solar's Family of Scalable Products ............................................................................................14 TT4000 Lite Touch Screen..........................................................................................................14 Connectivity of Solar's Products..................................................................................................15 Rack-Mounted Logix 5550 ..........................................................................................................15 DIN Rail-Mounted Logix 5434 .....................................................................................................16 Combination Generator Control Module......................................................................................16 Ladder and Function Block Programming...................................................................................17 Typical Risk Profile......................................................................................................................19 Goodman Diagram for First-Stage Disk ......................................................................................22 Valve Assembly...........................................................................................................................27 Valve Components ......................................................................................................................27 Cross Section of Two Valve Assembly........................................................................................28 Two Drain Valve Assembly .........................................................................................................28 Titan 130 Two-Shaft Gas Turbine ...............................................................................................31 Cutaway of the Mercury 50 Engine .............................................................................................32 Engine Cross Section Showing Airflow .......................................................................................33 Test Hours through 2000.............................................................................................................33 Mercury 50 Development Test Cell and Harbor Drive Facility ....................................................34 Taurus 70 Two-Shaft Gas Turbine..............................................................................................35 Taurus 70 Single-Shaft Gas Turbine...........................................................................................35 Taurus 60 Two-Shaft Gas Turbine..............................................................................................36 Taurus 60 Single-Shaft Gas Turbine...........................................................................................36 Taurus 60 Mobile Power Unit ......................................................................................................37

Mars Question 33

Typical Mars Gas Turbine Cutaway ............................................................................................40

Saturn Questions 34 35

Saturn Two-Shaft Engine ............................................................................................................42 Saturn Single-Shaft Engine .........................................................................................................42

General Question to All Manufacturers 36

Solar's Updated Web Site ...........................................................................................................45

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Tables Table

Page

Preface 1 2 3 4

Current Production Models for Compressor Set, Mechanical-Drive and Marine Applications ....... i Current Production Models for Generator Set Applications .......................................................... ii Uprate Options for Compressor Set and Mechanical-Drive Applications..................................... iii Uprate Options for Generator Set Applications ............................................................................ iv

General Questions to Solar 5 6 7 8 9 10 11

Disk Life Extension......................................................................................................................20 Bearing Lining Characteristics.....................................................................................................23 Pancake Valve Part Numbers .....................................................................................................29 Titan 130 Experience ..................................................................................................................30 ATS Program Goals ....................................................................................................................32 Test Summary – Short-Term Tests.............................................................................................34 Taurus 60-7800 Performance .....................................................................................................37

Saturn Questions 12

Comparison of Carbon Seals and Labyrinth Seals .....................................................................43

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Message to the GTUA Solar is pleased to be invited to participate in the 46th Gas Turbine Users’ Association Conference in Banff, Alberta, Canada. We believe the GTUA provides an excellent opportunity to address issues of concern to users of Solar’s turbomachinery and to keep our customers informed of the latest advancements in product development and service support capability. We would like to thank this year’s conference host, TransCanada PipeLines Limited, for sponsoring the 2001 meeting. Since the business environment is rapidly changing for many of our users, we are committed to evolve to meet those changes. For your informational needs, for example, we issued a number of new or revised Service Bulletins since last year’s GTUA conference and provided more options in communicating with Solar via our web site at "www.solarturbines.com." We endeavored to answer all the GTUA 2001 questions asked of Solar in an open and candid manner and trust they will meet your expectations. For your convenience, this CD-ROM contains an Appendix of any source material referenced in the answers, as well as other supplemental material. Solar Turbines is committed to continually improve the quality of its products and services. We appreciate this opportunity and place a great deal of importance on our participation in the GTUA conference because it allows us to gain a better understanding of the issues that are important to our users. Our primary objective in this effort is to remain worthy of your continued support.

Dave Esbeck Vice President Customer Services

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General Questions

Solar Turbines Incorporated Authors:

GTUA 2001

B. Perretti and B. Eldridge

General Question Number 1 Users are concerned about the experience and training of some field service reps especially with regards to their ability to deal with both the mechanical and instrument/electrical aspects of packages. Please clarify: • • • • •

Meaning of Solar Skill Levels (experience and training) of FSR’s (including Solar, ESI and SAMS) Clarify responsibilities of Solar, ESI and SAMS Process for resolving customer dissatisfaction with FSR’s Relation of FSR’s to RFE’s Expectations and processing of FSR reports on visits.

ANSWER

BACKGROUND

Solar’s Field Service Representatives (FSRs) are well versed in the system design of compression and power generation equipment, as well as offskid ancillary and balance of plant subsystems. They are supported by Regional Field Engineers (RFEs) strategically located in Solar's Field offices, design engineers, and a Response Center in the Customer Services Support Center, which is tasked with closed-loop case management for Field problems and related issues. FSRs have four job classifications focused on turbomachinery. Energy Services International Limited (ESI) and Solar Asset Management Services (SAMS) technicians provide support for turbomachinery, as well as a wide range of plant equipment. FSRs are responsible for supporting Solar’s gas turbines worldwide, while ESI and SAMS technicians support turbomachinery operation and maintenance services, which can require balance of plant equipment. Solar’s local District Service Manager should be contacted to resolve any dissatisfaction with an FSR in the Field. FSRs are supported by RFEs with sophisticated technical analysis of turbomachinery, driven equipment and related subsystems. As a report of their site visit, FSRs are expected to complete a Customer Support Activity (CSA) form.

Our service support philosophy is to provide systems personnel to maintain Solar’s turbomachinery and balance of plant equipment. Currently, our Field Operations Group employs 226 FSRs, 26 RFEs, 408 ESI technicians, and 146 SAMS technicians. Solar’s support teams are located in six regions around the world to meet our diverse user base. These regions are divided into 18 service districts. FSRs in a given region report to a District Manager and are supported by Regional Field Engineers (RFEs) in the analysis and resolution of complex equipment issues (Figure 1).

Field Personnel Skill Levels FSRs are skilled technicians trained to diagnose, maintain, and repair turbomachinery equipment and provide support for Solar’s fleet of more than 11,000 gas turbines worldwide. ESI and SAMS technicians provide the turbomachinery operation and maintenance services, which may include balance of plant equipment. Solar’s Field personnel have the following job classification codes: • FSR Level I – Entry level technicians who are usually recruited from Solar’s test cells and technical schools or who have previous industrial gas turbine experience. They generally provide maintenance services and support senior level FSRs during start-ups. 1

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Regional Service Manager Oversees All Customer Services Activities throughout Regional Field Offices

District Service Manager Manages Customer Services Operations in Local Geographic Area

Regional Field Engineers

Field Service Representatives

Tasked to Provide Expert Engineering for Comprehensive Support of Your Solar Package

Skilled Technicians to Diagnose, Maintain, and Repair Your Turbomachinery Application 01G1-1

Figure 1. Field Operations Organization

• FSR Level II – Intermediate level technicians who usually have been with Solar for five or more years. They generally provide the same FSR Level I service and support, as well as call out assistance and product problem resolution services.

training, and an introduction to Solar’s Response Center. Seven days are devoted to Field safety, including lockout / tagout, work place hazards, confined space entry, emergency, high voltage safety and hearing conservation. Two weeks are devoted to the fundamentals of turbomachinery and subsystem operations and maintenance and control system logic.

• FSR Levels III and IV – Advanced level technicians who usually have been with Solar for 10 or more years. They provide system commissioning and start-up, as well as advanced troubleshooting.

Advanced Training. Later during the first year, these FSRs receive an additional eight weeks of training in HRD and advanced turbomachinery course content. HRD training includes problem solving, influencing skills, user sensitivity, and technical report writing. Since control systems are becoming more complex and integrated into the balance of plant, considerable time and effort are spent on programmable logic controller (PLC) fundamentals and system troubleshooting, both in the lab and on simulators. Safety is integrated into the program at all levels. Other advanced training courses are available on Solar’s microprocessor-based Turbotronic control system and gas compressor and power generation principles and applications. These courses are normally held at our San Diego, California, and Mabank, Texas, training locations.

FSRs are sent to user sites based on the job skills they have to provide for the required services, not on their classification code.

Field Personnel Training Solar’s FSR, ESI and SAMS technicians receive continuous training through classroom courses and on-the-job training. In the first quarter of 2001, Solar implemented a newly developed training program for all Field Operations personnel that includes basic technical and safety training, as well as human resources development (HRD) skills.

Basic Training. All new hire FSR, ESI and SAMS technicians receive a four-week training program at Solar’s headquarters in San Diego, California. This program consists of a core curriculum on understanding Solar’s global user base, products and internal business processes, which includes the completion of Customer Support Activity reports, Department of Transportation (DOT) testing and

Continuing Development. Continuing development training is available to increase and expand the skill levels of our representatives and technicians. Technical training covers such topics as microprocessor controls, surge control, vibration, analytical troubleshooting, borescoping, and fire 2

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and gas detection, while HRD training covers such topics as effective teaming, project management, and goal setting. Again, safety is a prime focus in these programs.

01G1-2A

Responsibilities of Field Personnel A growing and important aspect of Solar’s Field Operations involves Energy Services International Limited, Solar’s subsidiary administered in Dublin, Ireland, and Solar’s Asset Management Services, headquartered in San Diego. ESI operates in Europe, Africa, the Middle East and Asia, while SAMS operates in North and South America. Their charter is to provide operation and maintenance services to our users. With these two organizations, Solar is able to operate complete facilities, providing plant optimization and cost reduction. In addition, Solar provides personnel to operate various plants, including cogeneration and combined-cycle power plants, offshore oil production platforms, and gas pipeline compressor stations (Figure 2). ESI and SAMS technicians require the same level of turbomachinery expertise as FSRs. They also require knowledge of a wide range of balance of plant equipment, as covered in various types of asset management services contracts: • Full Service Asset Management Services – Consist of turbomachinery and balance of plant operations and maintenance services, including after-market products, services, and parts. Full Service agreements provide the highest level of service and the most valuable plant performance guarantees.

01G1-2B

• Maintenance Management – Consist of equipment maintenance and repair. Asset Management Services supplies the personnel necessary to develop and implement a long-term preventive and predictive maintenance program, manage parts inventory, coordinate with outside contractors when necessary, perform normal daily maintenance, and conduct major maintenance.

01G1-2C

Full-Time Maintenance – A full-time maintenance staff is provided at the customer’s site. These personnel supplement the user’s work force and enhance the skill levels as necessary.

Figure 2. Asset Management Services

• Technical Services – Consist of providing an operations and maintenance consultant on a full-time basis at the user’s facilities.

chinery on-the-job training and formal classroom training, turbomachinery maintenance labor, and major maintenance scheduling and tracking. Further training is site / facility specific and focused on operation and maintenance.

• Technical Education Services and Training – Involve plant management and assistance with staff selection, providing turboma3

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GTUA 2001 age upgrades and in-situ refurbishments, including control system upgrades. FSRs also provide Field repair of major turbine components, such as combustors and power turbines.

Resolving Dissatisfaction with FSR The process for resolving customer dissatisfaction with FSRs regarding an issue in the Field is to immediately contact the local District Service Manager. Should a user have further issues, the Regional Manager should be contacted. (Please refer to the list of Solar’s Customer Services offices, which includes addresses and telephone and fax numbers.)

FSR Report Processing Solar’s process for Field office reporting is for the FSR to complete a CSA form (Figure 4) upon completion of work done at a user’s site. This information is provided to Solar’s local Field office and San Diego for Field issue resolution and invoicing. The CSA requires a user’s signature upon completion of the work required. A copy is left with the user upon the FSRs departure from the site. The remaining CSA copies are submitted to Solar’s local Field office for processing. A copy is reviewed by the District Service Manager and filed for future reference. Copies are then sent to San Diego for database input and invoicing, as well as issue identification and resolution. Solar’s manual CSA process is being replaced with a fully integrated, computerized “Field Service Management” program that will allow the District office to schedule the correct level of FSR to the site quickly and efficiently. With electronic access to the equipment bill of material, package configuration, and service call documentation, the FSR will be able to review previous repairs, providing added efficiency in problem resolution, identify and order parts on line, and review Solar’s current inventory position. All data will be shared in a common database, integrating Design Engineering, Manufacturing and Response Center with the Field. These enhancements will provide the best value of integrated services for the diverse service requirements of our users.

Relationship of Field Personnel RFEs are responsible for supporting the needs of the FSRs, by providing sophisticated technical analysis of, and advanced troubleshooting techniques for, turbomachinery, driven equipment, and related subsystems. They also conduct both analytical and more practical hands-on training for the FSRs. The RFEs have access to Solar’s Response Center, which identifies Field issues on a “case” basis (Figure 3). The Response Center, in turn, supports the local FSR with real-time information from Solar’s integrated databases. Finally, the resolution for a case is fed back to Solar’s Design Engineering and Manufacturing engineers so that the underlying problem is eliminated in future generation designs. FSRs are responsible for commissioning and start-up of turbomachinery packages and systems; call out services are provided on a 24 / 7 (24 hours a day, 7 days a week) basis, supported by our District offices located in 37 strategic areas in 20 countries; advanced troubleshooting; in-Field repairs on centrifugal compressors and pumps, pack-

Customer Satisfaction Survey Solar conducts an annual customer satisfaction survey to measure our performance in relationship to customer needs and expectations. Figure 5 plots relative customer importance versus our performance based on the survey. Our customers have rated seven Field Service areas of high importance. Over the past 10 years, Solar has remained consistent in these surveys and continues to see a positive trend. We appreciate the feedback we receive from the GTUA regarding our performance, along with all of our customers who participated in these surveys.

Figure 3. Response Center

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01G1-4

RELATIVE IMPORTANCE (CUSTOMER)

Figure 4. Customer Support Activity Form

High 1. Assistance with Field Problems 2. Knows Customer's Needs 3. Evening/Weekend Assistance

Trend

4. Field Service 5. Holiday Assistance 6. Mechanical Expertise 7. Electrical Expertise

High PERFORMANCE RATINGS (SOLAR) 01G1-5

Figure 5. Customer Satisfaction Survey

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Solar Turbines Incorporated Author:

GTUA 2001

B. Armstrong

General Question Number 2 Please report to users on Solar’s work on compression system controls (including surge control) especially: • • • • •

Report on internal Solar Focus Group Development of algorithms and selection of operating schemes Progress on engineering all system components. Plans to form strategic partnerships Skills of engineers and FSR’s to set up, support and troubleshoot control schemes. pressors, including process control, load sharing, anti-surge control, and surge margin optimization. These options are integrated into the main package programmable logic controller (PLC) based control system to provide close coupling and precise control. Apart from the necessary package instrumentation, no additional controls hardware is required. Data are available to other supervisory monitoring systems via a serial communication link.

ANSWER Over the past three years, Solar has enhanced its anti-surge control design and has added an option to allow similar units to load share without supervisory control. Solar's internal focus group recommended improvements in documentation and Field personnel training. Solar is now modelling compressor performance on head-versus-flow rather than on the differential pressures of the compressor and the flow meter. We have developed component source specifications and component arrangement recommendations for new and existing installations. We are also working toward forming strategic partnerships with compression control system suppliers. Solar has developed improved documentation and training to enhance the control system skill levels of its Field Service Representatives (FSRs).

Report on Internal Solar Focus Group Solar created a focus group to review how balance of plant control, including anti-surge control, is handled and how it can be improved. It examined the process from the proposal phase through commissioning and subsequent Field service. The group concluded that while significant improvements have been made in recent years in the design of the underlying software and hardware used for anti-surge control, changes were required to improve the documentation being sent to the Field and the training of Field Service personnel. Key aspects discussed were:

BACKGROUND Solar’s level of expertise in the area of compressor control has expanded considerably over the past 10 years, as its installed base has grown. Significant improvements have been made and Solar is committed to providing superior products and services. Solar continues to develop and improve both the underlying products and the processes for applying them to projects involving its compression system controls. Solar provides a number of options for the control and management of turbine driven com-

Design. Solar’s compressor controls provide important advantages to the user. Process (or performance) and anti-surge control are available for both single units and multiple units operating in series and/or parallel. Control is integrated into the main PLC and, thus, does not require separate hardware, minimizing the amount of space required for the total control system. The integrated control (1) eliminates potential interface problems between separate controllers and the main turbine compres6

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sor control system and (2) simplifies connections to package and field instrumentation. The recently developed unit-based load-sharing feature permits load sharing and surge margin optimization between like units without the need for a separate external controller.

performance so that it can anticipate when a surge event is about to occur. It then takes corrective action, typically by opening the anti-surge recycle valve, to move the compressor operating point away from surge. Solar’s original control system used a relationship of pressure differential across the compressor (DP) versus pressure differential across the flow meter (dp) plate to model surge. This was basically an electronic model of a pneumatic control system. Also, the earlier anti-surge system used a straight-line approximation of this relationship, which meant it was accurate over only a narrow operating range. Two years ago, Solar switched to a head-versus-flow relationship and a third-order polynomial equation to model compressor performance. In addition, instead of using actual head and actual flow, the new system uses reduced head and reduced flow, values of head and flow that are mathematically reduced to remove common factors. The result is a system that is largely independent of the specific gravity of the process gas and provides much greater accuracy and responsiveness. Figure 6 shows a typical anti-surge control screen from Solar’s control system. The cursor indicates the operating point of the compressor. From left to right, the three sloped lines are the surge line, the control line, and the deadband line, respectively. For convenience these are shown as straight lines, which represent tangents to the actual curved performance lines at the operating conditions, as indicated in Figure 7. As the operating point moves, the slope of these tangential lines will change.

Organization. A Balance of Plant group was created in 1999 within the Controls Development department to provide increased focus on compressor control. This group includes engineers with hands-on design and commissioning experience in compressor control. The objective of the group is to provide overall direction for compressor control and to support design engineers and Field Service personnel on more complex projects.

Documentation. A Balance of Plant Functional Specification was introduced as a required drawing on compressor packages. This document, developed in conjunction with the user, defines the specific controls philosophy and logic applicable to each project and details all inputs and outputs (I/O) related to the balance of plant equipment. Training. Additional training and increased support are required for Solar’s FSRs, who are the key user interface during commissioning and subsequent equipment service and authorized site changes.

Future Development. Solar’s future plans call for the increased use of “onskid” controls. The key components of the system, including the processor and I/O modules, are mounted on the package skid. Connection to the control room is via serial communication links instead of multi-conductor cabling, with a significant reduction in cost and physical bulk. Considerable development work has been devoted to reducing the size of the controls so that they can be mounted onskid. The integrated nature of Solar’s compressor controls makes them fully compatible with the onskid concept. Solar provides one point of responsibility for the control system, reducing the possibility of disputes if performance or operating problems arise. In addition, the system uses an open architecture that offers flexibility to users for service options.

Development of Algorithms and Selection of Operating Schemes The objective of the anti-surge control system is to prevent the compressor from ever reaching the point of surge. To achieve this, the control system uses a mathematical model of the compressor

01G2-1

Figure 6. Anti-Surge Control Screen

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GTUA 2001 installation of any one element can compromise the overall performance or make the system inoperative. Solar’s experience indicates that Field problems are sometimes attributable to hardware. Accurate signals from instrumentation and fast acting valves are critical, since fast response is an essential part of any anti-surge system. Figure 8 shows a simplified schematic diagram of a typical compressor with an anti-surge recycle loop. Solar has developed stringent source specifications for valves, positioners, transmitters and other components and continues to work with key industry suppliers to help improve individual components. The current recommended valve arrangement is shown in Figure 9 for a globe valve and includes an electropneumatic positioner, a position transmitter, a three-way solenoid valve, needle and check valves, an exhaust booster, and a regulated air supply. This set-up, in conjunction with the latest software, has been proven to provide a high level of response and control. The exhaust booster, for example, was developed by a supplier based on recommendations from Solar’s engineers. When a large rapid change in the position of the anti-surge valve is required, it will vent instrument air in a controlled manner. The booster has proved superior to standard quick exhaust devices in its ability to prevent valve overshoot.

Control Deadband

REDUCED HEAD FACTOR

Surge

REDUCED FLOW FACTOR 01G2-2

Figure 7. Anti-Surge Control Lines

Progress on Engineering All System Components An anti-surge control system requires the successful combination of piping layout, hardware such as valves and positioners, and the necessary electronic software-based control. Improper selection or

ENGINE

COMPRESSOR VV

SV

DV

AFTERCOOLER

TT

FT

PT

PT

TT

LV SCRUBBER

ANTI-SURGE CONTROLLER LIMIT SWITCH

= = = =

TT =

4 - 20 mA POSITION TRANSMITTER 4 - 20 mA

SOLENOID ENABLE 24 VDC

SV LV VV DV

FT = PT =

SUCTION VALVE LOADING VALVE VENT VALVE DISCHARGE VALVE TEMPERATURE TRANSMITTER FLOW TRANSMITTER PRESSURE TRANSMITTER

FAIL OPEN ANTI-SURGE CONTROL VALVE

01G2-3

Figure 8. Typical Anti-Surge Control Recycle Loop 8

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purchase order. This includes better pre-order definition and more accurate costing through earlier involvement of the third party, as well as a more standardized approach to engineering the interface between the other equipment and Solar’s controls.

NEEDLE VALVE & CHECK VALVE EXHAUST BOOSTER

24 VDC THREE-WAY SOLENOID VALVE

Skills of Engineers and FSRs to Set Up, Support and Troubleshoot Control Schemes Solar has a network of Field Service offices around the world. The key individuals involved in the commissioning and service of packages, including the tuning of the compressor controls, are the FSRs. They are supported on more difficult technical issues by the Regional Field Engineers (RFEs) and, when required, by factory process control engineers from the Balance of Plant group. Solar recognizes that the level of training and expertise of the FSRs varies and this has affected the successful installation of some projects. The following areas have been addressed to improve this situation:

POSITION TRANSMITTER

ELECTROPNEUMATIC POSITIONER

4 - 20 mA Limit Switch Closed Limit Switch Open 4 - 20 mA INSTRUMENT AIR SUPPLY PRESSURE REGULATOR

Solar does recognize that in some situations it is not practical to change hardware already installed in the Field. In these cases, Solar's engineers work with the user and modify the software to optimize the performance of the existing hardware.

Documentation. The Balance of Plant Functional Specification has greatly improved the definition process so that the software and hardware configuration shipped to the site accurately reflects user requirements. A manual on anti-surge and process control for centrifugal compressor applications has been written to help Solar’s personnel and user personnel better understand how these controls are implemented. The relevant sections of the Operation and Maintenance Instructions (OMI) manuals have been updated to reflect the latest information.

Possible Strategic Partnerships

Training. The compressor controls course spon-

Discussions have been held with other suppliers of anti-surge control systems to explore possible cooperative efforts. At this time, however, no decision has been made to form a strategic partnership. Steps have been taken to improve the process for including third-party anti-surge systems on Solar’s

sored by Solar’s Technical Training department has been updated to cover the latest information. This course is available to user personnel and Solar’s employees. Both formal and informal training sessions are being held with FSRs and RFEs to raise the overall level of expertise within the company.

01G2-4

Figure 9. Recommended Valve Arrangement

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Solar Turbines Incorporated Author:

GTUA 2001

S. McLoughlin

General Question Number 3 Users are concerned about quality control and change control of software. Please address the following issues for new and existing software: • • • • •

Verification that software is correct prior to shipment Control and verification of FSR changes FSR training/guidelines/authority levels for changes and tuning. Procedures used for tuning Documentation of site changes (both for user and vendor) and verification of software changes made by Solar’s FSRs or Regional Field Engineers (RFEs). As skilled technicians trained to diagnose, maintain, and repair user equipment, Solar’s FSRs are empowered to make the software modifications needed for the user’s turbomachinery to operate within normal parameters per Solar's specifications. Solar recognizes that more complete documentation, instructions and training courses for tuning procedures are required. Although general tuning procedures have been documented, some of the existing procedures are currently being updated and new procedures are being developed.

ANSWER Over the past five years, Solar has developed new tools, processes, and measurements that focus on improving software quality and control. Current development activities include functional block programming, remote monitoring / tuning, and certified modular software. Solar has developed check programs to verify that the control system software is correct prior to shipment. Our software verification process is designed to capture, validate and document control system changes made by our Field personnel. Solar's Field Service Representatives (FSRs) receive solid technical support, as well as hands-on control system troubleshooting and Turbotronic simulator training. Our general tuning procedures include documentation, instrumentation and static loop checks, along with dynamic tuning where possible. Site changes to the control system software are documented in a "history" file as confirmed by Solar's Release Group in San Diego.

Verification of Software prior to Shipment To improve the reliability and quality of its control software, Solar has created many internal software check programs (tools). These programs help minimize the communication errors, ladder errors and display errors, which may be introduced after completion of dynamic test, on initial “as-shipped” and on official “as-installed” releases. They perform most of the checks and balances of the data between the programmable logic controller (PLC) program and the display computer files, making the Design Engineer more efficient in producing quality software. One program, for example, was created to transfer the PLC symbols and address comments from the PLC program to the display computer files, so there is exact correlation between the ladder diagram and displayed messages. This program provides valuable feedback during the design process, reporting exceptions that need to be corrected.

BACKGROUND Solar continuously strives to strengthen the processes and tools involved in software quality and control. The current software release process ensures that all “as-tested” or “field-returned” software is captured, verified and used in generating the “as-shipped,” “as-installed,” or “post commissioning” software releases. This process involves ISO 9000 procedures governing the documentation

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GTUA 2001 • “Standard” (composite) software modules are validated by an independent review of the code and a test in the Systems Engineering facility control console, a test using simulation equipment, or a test project console and package.

To ensure proper verification of the software during the release process, Solar uses a process to validate that the project software is functioning properly before any official release. Checking the as-shipped release software (Rev_A0) consists of the following main steps:

• After-market and new “project” (custom) software are tested using simulation equipment. Additional verification for new project software and after-market refurbishment project software occurs during a dynamic test conducted in a production test cell with the project skid and control console in accordance with Solar’s ISO 9000 procedures.

1. Initial Check – Confirm visually that all needed drawing files are present, that the directory structure is correct, and that the history file is properly documented. 2. Create Disks / Load Software a. Use Diskmaker Tool to verify that pointers are correct and needed files are present. b. Load PLC software files into PLC to assure there are no faults. c.

Post Commissioning. To promote consistent handling of post-commissioning software modifications, Solar developed an improved process for commissioned software control and verification. This process is intended to ensure that software quality is not compromised and that the latest site software is archived for future use. At the conclusion of a post commissioning update, the FSR or RFE sends a copy to San Diego of the “as-found” and “as-left” software installed in the user’s control system. An updated description of the changes between these two sets of software is also returned to the San Diego Release Group via electronic mail, the Commissioning Engineer, or the Customer Services Project Manager. The Controls Group in San Diego reviews those software changes made by Solar’s FSRs or RFEs only. User changes are not reviewed and, thus, Solar does not assume any liability resulting from changes made by personnel not authorized by Solar. Software changes should be made through Solar’s appropriate Field Service office to ensure the safety and performance of the engine / package are not compromised.

Load display software files into display computer to check for warnings or errors. If display loads correctly, check menu selections and communication between PLC and display.

3. Diagnose Problems – If display software does not load correctly, diagnose problem. Then notify Design Engineer to make corrections and repeat testing with revised software. 4. Release – Archive software, notify all appropriate individuals, and update release log.

Control and Verification of Changes In conjunction with the software release process and software quality checks, Solar has uses a software verification process. Software is developed for new or after-market projects by modifying “composite” software in an existing standard database. The project software is customized and developed on a personal computer to create the “initial release.” During testing of that release, required changes are incorporated via “updates” or “intermediate releases.” After test, the “as-tested” software is captured and used to generate the “asshipped” release. During commissioning of the equipment, the Design Engineer may issue “other” releases to be sent to the Field to resolve any user site issues. When commissioning is complete, the Field-returned software is captured and sent back to San Diego to generate the “as-installed” release. Prior to any official release, the Design Engineer reviews all software differences and clarifies any issues with the FSR or RFE. Solar’s internal software verification, prior to any “as-shipped” software release, involves the following:

Field Service Representative Training, Guidelines and Authority Solar’s FSRs represent a well-trained, motivated and talented work force dedicated to resolving user site software issues. They are empowered to change the control software to ensure that the turbomachinery operates within normal safety and performance parameters per Solar's specifications. For technical support, they interact with the RFEs, Design Engineers or Customer Services Response Center. The FSRs also attend an intensive oneweek controls system programming course, which offers hands-on troubleshooting through the use of

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a control system simulator. The FSR is given a oneday refresher course on troubleshooting theory, then allowed four days to actually troubleshoot the control system for problems applicable to both compressors and generators. Additionally, the FSR has the opportunity to reinforce programming skills by going on-line with a Turbotronic simulator. This PLC trainer is designed to demonstrate logic instructions and turbine control principles. Upon successful completion of the course, the FSR has learned all the necessary procedures for making Field changes to the control system hardware and software.

• Static loop check • Dynamic tuning

Documentation of Site Changes All changes to software, including the initial internal release, must be noted in the “history” file that forms part of the overall software file structure. This file resides in the drawing software folder and has the filename "xxxxx.his" where "xxxxx" is the fivedigit Sales Order (or Project Definition) number. This file allows anyone working on the software to view what prior revisions were made and why. To ensure proper documentation of site changes, Solar’s San Diego based Release Group adheres to a strict procedure. The Release Group confirms that Field-returned software contains an updated history file. If no changes were made to the software, then the history file must state: “no modifications.” The Release Group archives the Field software and notifies the Commissioning Engineer or Customer Services Project Manager, Design Engineer and Engineering Group Leader that the returned software has been archived and is ready for the review and release process. If the history file is missing or not updated, the Release Group notifies the Commissioning Group for new projects or Customer Services Project Management for aftermarket projects, and the appropriate District Manager, that the software has been rejected.

Procedures Used for Tuning Solar is developing more complete documentation, instructions and training courses for closed-loop tuning procedures. Our internal software verification processes in dynamic test complete a majority of the pre-tuning requirements for specific applications, such as fuel, guide vane, bleed valve, and SoLoNOx control. These processes ensure that Solar delivers a high quality software product to its users that requires only fine tuning at the user’s site. Systems such as surge, import / export, process, and boiler control are statically tested rather than dynamically tested. Presently, some existing tuning procedures are being updated, while new specific control loop tuning procedures are being developed. Solar’s general tuning procedures involve: • Loop functional documentation review • Instrumentation and actuator check

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Solar Turbines Incorporated Author:

GTUA 2001

E. Corzine

General Question Number 4 Describe new software developments. TT4000 is a scalable system that has the capability for enhanced data logging, report generation, remote communications, and event notification of remote personnel. This design provides an excellent foundation for future growth and extension of the product.

ANSWER Solar is committed to maintaining a leadership position in gas turbine control and monitoring. To maintain this position, Solar continuously reviews technology advancements, user requirements, and industry trends in hardware and software. This information enables Solar to develop controls solutions that address the complex requirements of gas turbine control and monitoring.

Scalable Family of Products The first offering in Solar’s scalable family of display products (Figure 10) is TT4000. TT4000 is a “full scale “ HMI that replaces our older TT2000 DOSbased HMI. It is a Windows NT / 2000 based system offered in a range of hardware configurations from desktop to industrial rack-mounted solutions. TT4000 is capable of collecting large amounts of historical data. Typically, a TT4000 project is configured to collect from four to five gigabytes of data. Additionally, TT4000 has advanced alarming capabilities, including the ability to send a fax, page, or E-mail based on alarm condition. Other key features of TT4000 include on-line help, real-time trending of tag information, and an off-line historical data analysis application. TT4000 Lite is Solar’s next offering in the scalable family of display products. TT4000 Lite is an onskid Class I, Div. 2 display system with a NEMA 4X rating. Offered as a Panelview replacement, TT4000 Lite provides access to the last 5000 events and a limited subset of the full-scale TT4000 historical data-logging configuration. The primary interface is a 10.4-inch touch screen (Figure 11). To meet temperature and vibration requirements, the standard hard drive is replaced by a solid-state hard drive. TT4000 Brick is a new product under development that has no user interface. It is a small stand-alone (“brick”) computer capable of offering process data using HTML and XML Internet technologies. TT4000 Brick will provide a centralized “view” into the process for those systems that may not contain other display technology entry points like TT4000 or TT4000 Lite systems.

BACKGROUND Solar’s current software development is divided into two areas: human machine interface (HMI) and programmable logic controller (PLC). Solar launched a cross-functional team to review the current HMI and PLC standard, internal and external user requirements, and industry trends. This team then established the objectives and requirements for the next generation HMI and PLC products.

Human Machine Interface The design objective for Solar's new HMI standard, TT4000, is to provide users with information to improve their equipment operation. The basis of TT4000 is an open architecture that adheres to industry standards, including the following: • Operating System – Windows NT / 2000 • Display Viewer – Active X • Database – ODBC (Open DataBase Connectivity) • Scripting – VBA (Visual Basic for Applications) • Communication Technology – OPC (OLE for Process Control)

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TT4000 • TT2000 TT4000 Lite • PanelView TT4000 Brick • Real-Time • Small Historical • No Hard Drive

• Real-Time • Historical Display • Trending

• Real-Time • Simple Screens • Historical Data

• Predictive • Windows NT / 2000

• Embedded Windows

• No Display • Windows CE Under Development

SCOPE AND FUNCTIONALITY 01G4-1

Figure 10. Solar's Family of Scalable Products

1. The first communication path is to the onskid controllers. This onskid or offskid communications path can be either DF1 serial, ControlNet Version 1.5, Ethernet or combination. 2. The second communication path is to the user's local area Ethernet network. This path enables the user to monitor process data. Additionally, network printers can be used for TT4000 screen prints and reports. 3. The third communication path is intended for remote connectivity either via serial, modem or other global communications equipment. This communication path allows remote connectivity to view, retrieve and archive process data. The combination of state-of-the-art hardware and software technologies enables the TT4000 to be applied across a wide range of projects. The same TT4000 application can be used for single units or multiple units, for onskid or offskid, or highly complex station control systems. The communications structure of TT4000 enables information to be available when and where it is needed.

01G4-2

Figure 11. TT4000 Lite Touch Screen

Connectivity. Solar’s scalable family of display products share the same three communication paths (Figure 12):

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Onskid

GTUA 2001

Controller(s) Satellite Controller A Controller D Controller C

Controller B Data

Data

COMM Solar Intranet RS232 Work Station

Radio Tower Internal Modem Telephone Line

Control Console

Modem Pool

Work Station

Web Server

Ethernet

Line Printer

IBM Compatible Laser Printer

Data

Customer Equipment

01G4-3

Figure 12. Connectivity of Solar's Products

Programmable Logic Controller The design objective of the new PLC control system is to provide a modular subsystem-based software and hardware solution. Using industry standard, leading edge hardware and software technology, there will be long-term stability and supplier support for the new design. IEC 61131-3 compliant programming software is used to create pre-certified software modules. This solution provides a design that enables fast project execution, reduces project errors, increases overall integrity, and ensures longterm viability of the new PLC control system. New hardware development is based on the Allen-Bradley Logix family of processors and ControlNet 1.5. The Logix family offers a range of products based on the same processor architecture. This solution enables software to be written in one programming environment, RS Logix 5000. The software created with RS Logix 5000 can then be used to program both the rack-mounted Logix 5550 (Figure 13) and the DIN rail-mounted Logix 5434 (Figure 14). This promotes application flexibility. All new hardware development incorporates ControlNet 1.5 for communications. For example, the combination generator control module (CGCM)

01G4-4

Figure 13. Rack-Mounted Logix 5550

(Figure 15) combines the line synchronizer module (LSM), the generator voltage regulator, and the generator protective functions in one module and is connected to the Logix Controller on ControlNet. The CGCM communicates both configuration information and data to and from the Logix Controller via ControlNet.

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GTUA 2001 The programming environment for the PLC is Windows NT / 2000. This provides a common operating system for both the HMI and PLC. Multiple programming methods are incorporated. Ladder and Function Block Programming (Figure 16) are currently supported. Sequential Function Chart Programming is currently in development. The new PLC system consists of functionally based subsystem modules, such as start, lube, and fuel systems. These software modules are pretested and certified. Automation tools are then used to select the appropriate certified modules and generate the application software based on project requirements. The completed application is then processed through an automated test suite to ensure overall system integrity. These new processes and procedures reduce the possibilities of errors introduced each time a project is generated.

01G4-5

Figure 14. DIN Rail-Mounted Logix 5434

01G4-6

Figure 15. Combination Generator Control Module

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01G4-6

01G4-7

Figure 16. Ladder and Function Block Programming

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Solar Turbines Incorporated Author:

GTUA 2001

D. Manteuffel

General Question Number 5 Please provide update on development in time between overhaul (TBO) management, life assessment and changes to improve TBO. This question applies to engine and accessories. Also, address any changes in time limited components that may permit users to defer TBO. ability of a failure based on analysis of engine performance data plus the economic consequences of engine failure, including the cost of deferred production due to the incremental downtime associated with an unplanned engine change out. To simply extend the service life period by only extending the operating period will result in the operator taking on additional risk, as shown in the "typical profile" in Figure 17. Solar’s interest is in exploring methodologies that shift the entire curve to the right, as shown in the "enhanced profile" in Figure 17, thereby allowing increased operating periods without operators having to take on additional risks. The question then becomes one of accurate and timely assessment of the life of the engine and key accessories all along the operating curve, and becomes more critical as the operating hours increase. Assessment of engine life is a function of the ability to gather accurate engine condition data in a timely manner, to interpret that data accurately and to use that interpretation to predict future engine performance. Hardware, software and communications advances have all contributed to the improvements in this life assessment decision. Solar is monitoring these new technologies and adapting them to improve both the interpretation process, as well as the data gathering process. (Please refer to GTUA 2001 General Question Number 4). Wireless and other communications technology advancements have made remote monitoring highly desirable, so engineering expertise can be centralized and leveraged to cover multiple sites of rotating equipment. Improved data retrieval and display programs have improved the ability to reduce the data and to correlate events. None of this, however, is very beneficial if the information cannot be used to accurately predict the ability of the engine to run until, or beyond, the next scheduled maintenance shutdown.

ANSWER In its response to the GTUA in 1998, Solar stated that the recommended overhaul interval is 30,000 hours for all of Solar's engines in continuous duty service. This recognizes that our installed fleet of more than 11,000 gas turbine packages worldwide is exposed to a wide range of environmental, maintenance and service conditions that are largely beyond our control. Solar, however, supports user efforts to increase TBO, without sacrificing reliability and durability, via robust maintenance practices, along with monitoring of fluid (air, fuel, water, and oil) quality and operating profile. In fact, a growing number of Solar's turbine users are gaining experience in operating equipment beyond the recommended time between overhauls (TBO).

BACKGROUND Solar shared its life determination methodologies with the GTUA in 1998. (Please refer to GTUA 1998 General Question to Solar Number 1.) In our continuing efforts to extend time between overhauls, Solar’s philosophy is to continuously evaluate and eliminate reasons that may cause an engine to be removed from service when it might be otherwise running acceptably. We are focusing on the continuous enhancement of product durability, utilizing removal-for-cause strategies, and improving on-line data gathering and analysis techniques.

Life Assessment Decision TBO management is essentially a risk management decision based on an analysis of engine condition. The decision to remove a high-time engine from service is evaluated in terms of the trade-off between (1) the desire to continue running until the next scheduled maintenance shutdown that would allow for a planned change out and (2) the prob-

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Figure 17. Typical Risk Profile

Life assessment decisions are generally based on the deterioration of a measured parameter trended over time, with the knowledge of the baseline. Occasionally, an event will occur where a discrete event will precipitate a life assessment decision. Trend data gathered while the engine is running should be, whenever feasible, supplemented with information gathered from borescope inspections and a lube oil sampling program. The objective is a decision point where an engine is removed from service for a defined cause rather than simply on a time schedule.

more critical ones that are indicative of in-service condition of the lubricating oil are Total Acid Number (TAN), Rotary Bomb Oxidation Test (RBOT), Foaming, and Air Release. For reciprocating engines, it is normal for wear metals to gradually increase over time. A sharp increase in the rate of accumulation in the lube oil would signal a potential problem. Wear metals in gas turbines with hydrodynamic bearings, however, typically reach an equilibrium level very quickly, then remain constant in the absence of unusual wear. Monitoring other engine parameters, such as vibrations, temperatures of oil drains, and the T5 spread, are normally used to identify an engine problem. Vibration monitoring can be particularly challenging. To ensure consistent vibration measurements, the same points and equipment should be used for data acquisition. In analyzing vibration data, absolute vibration limits should be considered, as well as trends to determine the operating condition of the package. This trending capability can be an integral part of the microprocessor-based turbine control and monitoring system. Care must be exercised to differentiate a problem with a package component or a faulty sensing device from a true problem with the engine. Some engines removed from service and sent in for overhaul, due to suspected vibration problems, were found to have vibration levels well within specification limits when the engines were tested prior to overhaul. The actual problems ranged from

Removal for Cause TBO management by users should include a comprehensive maintenance program to help ensure that the equipment is removed for major repair or overhaul for a verified reason. (Please refer to Solar’s paper “Increasing Turbine Life through Improved Maintenance Procedures,” TTS104.) Lube oil analysis and vibration measurements are critical components of this type of program. Lube oil analysis is an excellent maintenance procedure to help determine the condition of the engine. Spectrochemical oil analysis is used to detect changes in the condition of the oil as operating hours increase. Solar’s engineering specification ES 9-224, contains guidelines and limits for the measurements of oil characteristics. (Please refer to Solar's paper "Lube Oils for the Industrial Gas Turbine," TTS106.) Of these various properties, the 19

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improper equipment alignment, coupling wear or imbalance, coupling lubrication or grease, and worn trunnion mounts, to imbalance or vibration problems in the turbine’s driven equipment.

Life Limited Components One consideration that is clearly identified as life limiting to a running engine is the expiration of creep life of turbine disks. As a part of our continuing effort to better understand the boundaries in TBO management, Solar has re-evaluated the creep life limits on these disks. This activity required our Engineering staff to re-evaluate our design assumptions, which included validating our temperature understanding, using our latest finite element analysis tools to calculate the disk stresses, and incorporate our latest understanding of the disk material properties, both stress rupture and creep. This analysis provided a better picture of the theoretical design life. These results were then compared with results of our Field experience and a review was made of any Field failures that may identify potential life-limiting concerns. A material test program of high-time disks was also conducted to help validate our calculated lives. The result of this activity established the ability to extend the service lives of several turbine disks with no compromise in product integrity (Table 5). The somewhat conservative position to extend the lives an increment of 30,000 hours (or one typical overhaul period) has been taken. As these disks near this new life limit, the process will be done again. This approach provides the opportunity to continually test the design assumptions and extend the life in a safe and responsible manner. All engine accessories, such as pumps, valves, sensors and controls, have been selected to perform satisfactorily for at least 30,000 hours before maintenance or replacement is needed. Some items, such as electric motor bearings, filters, certain pumps, and other components require maintenance at intervals less than 30,000 hours. In these cases, the Operation and Maintenance Instruction (OMI) manual should identify the required actions. Solar, as a result of this question from the GTUA, is doing a review to ensure that all items needing regular maintenance are identified in the OMI manual.

Environmental Considerations One of the most powerful ways to improve durability and reliability and to extend TBO is to carefully control the quality of the air, fuel, lubrication oil and wash water. Poor performance of the air inlet system can lead to compressor fouling, which results in reduced performance and salt deposits especially in a marine atmosphere. Fuel quality can also have a profound impact on an engine’s durability and reliability. Salt contamination is a significant concern with liquid fuel, which also frequently contains some amount of sulfur, leading to hot corrosion. This type of contamination can be managed with proper fuel handling and filtration techniques. Liquids entrained in gaseous fuels have always been problematic, and the increased focus on dry low emissions combustion systems has only heightened this concern. Liquids can cause hot streaks or localized burning on hot section components, which greatly reduce turbine life. The quality of engine wash water is a maintenance item that frequently receives little attention, but can have a profound impact on engine life. The presence of sodium or potassium in the wash water or an incomplete rinse, which can leave salt deposits in the turbine section of the engine, can lead to hot corrosion. The presence of particulates or an incomplete rinse cycle can introduce this contamination into the variable vane bushings, causing them to partially freeze during future run cycles. The actuation of the vanes during subsequent start / stop cycles tends to bend the vane arms, which then mis-positions the vanes. High cycle fatigue failure of one of the turbine compressor blades is an occasional serious consequence of mispositioned variable guide vanes.

Table 5. Disk Life Extension Turbine Disk Material Operating Life, hours

V57

Inconel 718

Before

Current

Before

Current

Saturn 20

100,000

130,000

150,000

150,000

Centaur 40

100,000

130,000

120,000

150,000

Centaur 50

100,000

130,000

120,000

120,000

Taurus 60

100,000

130,000

120,000

120,000

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Solar recognizes that, on a limited number of projects, some components, such as pumps, were supplied that did not meet the 30,000-hour life and were not identified in the OMI manual as such. Solar is taking corrective action to ensure that this will not reoccur.

Taurus 70 Gas Turbine. The Taurus 70 compressor is a growth derivative of the Centaur 40 compressor. In order to increase the airflow for the Taurus 70, two stages were added to the front of the compressor. At the 1999 GTUA meeting in Dubai, fatigue cracking of the third-stage compressor blade was discussed. (Please refer to GTUA 1999 Taurus Question Number 1.) Due to the critical nature of the issue, Solar has continued to investigate the blade design. The engineering analysis showed the blade attachment to have a relatively high stress level in the dovetail and that the maximum alternating stress, due to blade vibrations, was superimposed over this high stress location. The subsequent redesign effort created a more massive attachment, which decoupled the location of the maximum static stress and the maximum dynamic stress. The benefit of the redesign effort on fatigue life is clearly illustrated in the Goodman diagram shown in Figure 18. The original design using material in the 621°C (1150°F) age condition failed to meet our basic design goal for alternating stress capability. Decreasing the aging temperature to 552°C (1025°F) increased the material endurance limit, and consequently the blade's capability, to above the alternating stress capability goal. In the redesigned blade, the lower mean stress and the improved material properties combine to provide a substantially improved alternating stress capability. As an added benefit of the redesign effort, the airfoil was slightly retapered to better position the airfoil’s resonant frequency with respect to the third and fourth engine orders. This is believed to make a more robust blade design and totally eliminate the potential for fatigue failures. The new blade has been in full production since December 2000 for all new and overhauled engines.

Durability Enhancements Some examples of our focus on continuous enhancement of product durability involve the Taurus 60, Taurus 70 and Centaur 40 gas turbines. Mars gas turbine durability enhancements are discussed in GTUA 2001 Mars Question Number 1.

Taurus 60 Gas Turbine. Over the past few years, the Taurus 60 gas turbine has received several durability enhancements in conjunction with a series of thermal uprates. The non-cooled secondstage turbine blade has typically been a life-limited component, although not to the extent of impacting 30,000+ hours of operation. Raising the firing temperature from 1010 to 1046°C (1850 to 1885°F), however, required a material change from IN 738 LC to MAR M 247. This increase in alloy capability provides a life similar to that of the original Taurus 60 engine. Our current uprate activity to raise the firing temperature to 1066°C (1950°F) will include a change in blade material to the single-crystal alloy CMSX-3. This alloy selection will actually provide greater blade life and assure the ability to provide a minimum of two overhaul cycles. The Taurus 60 second-stage nozzle has also received a material upgrade from the cobalt alloy FS-414 to the nickel-based alloy MAR M 247. The new alloy provides superior creep resistance and enhanced precious metal coating performance. Remanufacturing of the FS-414 nozzles requires a hot forming operation to re-establish the position of the inner shroud with respect to the outer shroud. The improved strength of the new alloy will eliminate the need for this operation and improve the remanufacturability of the part. The alloy is also suitable for the 1066°C (1950°F) turbine rotor inlet temperature (TRIT) uprate. Additional component cooling will also be utilized. Through a combination of the nozzle creep and the positional tolerance of the second-stage diaphragm with respect to the second-stage rotor, a potential for interference existed. A design study was undertaken and the outcome was to define a more optimally positioned diaphragm. Since this change was put into production, rotor lock-ups due to the second-stage diaphragm have been eliminated.

Centaur 40 Gas Turbine. The Centaur 40 engine has been in production for many years and has received several uprates to meet user requirements. The uprate from the -4500 to the -4700 configuration has shown an increasing difficulty in meeting specification performance in the -4700 configuration, requiring specialized build techniques to achieve acceptable performance. An engineering study was conducted; the results of which showed the turbine nozzle case to be non-uniformly cooled. This, in turn, caused the nozzle case to become out of round, which negatively impacted the ability to control tip clearances and to perform to specification. The design effort resulted in the cooling circuit

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Taurus 70

ALTERNATING STRESS

17-4 PH (1150°F)

17-4 PH (1025°F) Current Design Improvement due to Redesign of Blade Attachment Design Goal

Improvement due to Material Properties

Original Design

MEAN STRESS 01G5-2

Figure 18. Goodman Diagram for First-Stage Disk

These product durability enhancements, along with continuing efforts to assess engine and accessory life and to promote optimal maintenance practices, should help users make critical decisions regarding removal for cause versus schedule.

being optimized to more uniformly cool the nozzle case. This allowed for a more optimal setting of the turbine blade clearance. The optimized engines have shown less engine-to-engine variation in performance and much less difficulty in engines meeting specification requirements.

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C. Brown and G.Vavrek

General Question Number 6 What is Solar doing to remove the need for backup post lube on Centaur 50, Taurus, Mars, Titan and future developments? ANSWER

Trade-Offs between Babbitt and Bronze Bearings

Backup post lube is required on all Centaur 50, Taurus 60, Taurus 70, Mars 90, Mars 100, and Titan 130 gas turbine products to prevent overheating of the tilting-pad babbitt material. At this time, Solar does not have any immediate plans to change the bearing material to eliminate the backup post lube requirement.

Table 6 shows that tin bronze is superior in three of five categories. Solar’s main turbine shaft bearings, however, are very lightly loaded. Static loading rarely exceeds 689 kPa (100 psi) and dynamic pressures rarely exceed 2758 kPa (400 psi). Thus, the superior load capacity and fatigue strength of tin bronze provide no practical advantages. For Solar, the choice between bearing lining materials comes down to the conformability of the tin babbitt versus the higher operating temperature limits of the tin bronze. Conformability protects the shaft (journal) when particulate oil contamination is present. This provides life-cycle cost benefits during service and at overhaul, since the turbine shaft may not require any repair or only minor repair before being returned to service. The higher operating temperature limits of tin bronze allow the bearings to survive post-lube interruption. This eliminates the need for back-up post lube, with its added costs to install and maintain. Based on 40 years of gas turbine experience in mostly continuous duty applications, Solar has chosen the tin babbitt material bearing to optimize the durability of its Centaur 50, Taurus 60, Taurus

BACKGROUND Solar has spent a great deal of effort analyzing bearing failure mechanisms and weighing the tradeoffs between bronze and babbitt material bearings. Bronze bearings usually do not require post lube, while babbitt material bearings do require post lube. Post lube oil circulation is required to cool the engine after operation. The backup post lube system provides this cooling in the event of a failure of the post lube (primary) system. Solar’s post lube and backup post lube systems are either battery powered or pneumatically powered. In the late 1980’s, Solar decided that durability was paramount to meeting user needs for continuous operation and chose babbitt material bearings. Our Field experience shows that these bearings have excellent durability, even during times when the oil may be contaminated.

Table 6. Bearing Lining Characteristics Characteristic Conformability and Embeddability Operating Temperature Limit Load Capacity Fatigue Strength Corrosion Resistance

Tin Babbitt

Tin Bronze

Excellent

Poor

150°C (300°F) 550-10 340 kPa (80-1500 psi) Poor Excellent

260+°C (500+°F) 27 575+ kPa (4000+ psi) Excellent Very Good

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70, Mars and Titan 130 gas turbine products. Backup post lube, however, is required on these products to prevent overheating of the tilting-pad babbitt material.

offered as an option only, and that post lube may still be required with the bronze bearing option.

Service Bulletin References The following Service Bulletins provide more information about back-up post lube system improvements and maintenance:

Development of Bronze Bearings As part of a long-term study, bronze bearings have been installed in a Mars in-house development engine in the No. 3 bearing location. Solar will then evaluate the viability of using bronze bearings. The qualification process will include a field evaluation effort and economic justification before the bronze bearing is released into production. Presently, our best estimate is that the bronze bearing will not replace the standard babbitt bearing; but will be

• SB 5.9/103 • SB 6.5/107 • SB 6.5/108 • SB 6.5/109 • SB 6.6/102

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Solar Turbines Incorporated Authors:

GTUA 2001

T. Clayton and D. Phaneuf

General Question Number 7 Explain process for controlling the configuration of retrofits and upgrades (especially controls but also mechanical)

quent modifications that we are aware of. The original package "As Built" bill of material is retrieved from our configuration database by referencing the original project definition (PD) number. Subsequent retrofits and modifications are retrieved by referencing the sales order (S.O.) number of those jobs.

ANSWER Controlling the configuration of retrofits and upgrades has been a multi-step process. Depending on the project, it may involve documenting user requirements, developing bills of material, filing service reports, updating the configuration database, archiving controls software changes, providing kit instructions, and revising drawings and manuals. Solar expects our Enterprise Resource Planning (ERP) initiative to enhance this process through the development of automated Service Bills of Materials and updated Service Parts Lists.

4. Any requests for additional information and/or, depending on the complexity of the project, a site survey, are communicated to Solar’s local Field office, which then clarifies the issues with the user. Project definition is finalized through these clarification discussions and communications with the user, which is an iterative process. It is directed through the local Field office to ensure that local concerns and installation issues are addressed. At this point, the intent is to identify any configuration differences between the configuration data that Solar is using and any local knowledge or modifications that may impact or inhibit the installation of the retrofit kit or upgrade under discussion.

BACKGROUND Current Process Solar handles major configuration modifications, such as retrofits and upgrades, on a project basis. The change process is essentially the same for mechanical, electrical, and controls changes and, in general, proceeds as follows: (Please refer to GTUA 2001 General Question Number 3 for details specific to software configuration control.)

5. The changes in project scope that result from the user’s review of Solar’s proposal are either appended to the proposal or the proposal is revised to reflect these changes

1. Initially, the user contacts Solar’s local Field Service office to communicate specific needs, such as a desire to increase power. Dialog at the local level is critical to ensure Solar’s thorough understanding of the requirement.

3. The San Diego support organization accesses Solar’s configuration records, which include an

6. At an internal project coordination meeting, the purchase order and proposal are reviewed in detail with the departments responsible for hardware and software deliverables, in order to obtain design commitments and to confirm delivery estimates. An internal sales order document is generated that details the scope of supply and the delivery schedule, and a sales order number is assigned. The project schedule is loaded into the Project Scheduling System to track completion dates and design reviews.

“As Built” bill of materials, “As Installed” drawings and software revisions, and any subse-

7. The detailed bill of material for retrofits and upgrades is reviewed as the design progresses

2. User requirements are formalized by Solar’s local contact, via a Field inquiry form that is sent to a Project Manager in San Diego. When a project involves only a control system retrofit, an applications check sheet (ACS) is used and the request goes directly into the Controls Engineering organization.

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to make certain that all parts selected are of the current standard and are supportable through the Service Parts organization. Solar’s Design Change Request (DCR) process enables cross-functional engineering departments to review the intended duty of parts / components that require modification or update.

of the equipment and availability of documentation.

Future Developments Solar records and retains the Manufacturing bills of material for the original equipment under the original project definition number. The material and configurations for subsequent modifications are recorded under their own project definition or sales order. In the past, updating these was a multi-step, manual process. Our continuing effort is to automate the process wherever possible so that the original bill of material may be updated effectively to provide the user with an “active” bill of material that accurately reflects the current configuration for the operating equipment. Solar is in the early phases of implementing an ERP initiative to significantly increase the functionality of the current process. With this business tool, we expect to:

8. A copy of the sales order is sent to Solar’s Response Center administrator for updating the user equipment configuration database. 9. Many retrofit and upgrade kits include instructions that are formatted to be retained by the user as an addendum to their Operation and Maintenance Instruction (OMI) manual. 10. If a controls logic change is required, the revised software is provided through Solar’s local office, which retains a copy. 11. If Solar's Field Service Representatives (FSR) participate in the installation associated with the retrofit or upgrade, a Customer Support Activity (CSA) report is completed to detail the work and to document the configuration change. Copies of this documentation are retained by the user and the local Field office.

• Retain the final Manufacturing bill of material and then be able to “filter” it to produce a Service, or Support, bill of material. • Modify the Service bill of material, which will detail the major systems and maintenance items, when configuration changes do occur.

12. If applicable, a copy of the “As Installed” software will be returned to Solar for archiving. Copies are retained both in the local Field office and in San Diego.

• Allow easy update of the Service bill of material by the San Diego-based engineering functions, or by the FSR via their reporting mechanism following completion of modification work in the Field.

13. Drawings will be marked up to reflect the “As Installed” configuration. Copies are retained at the user’s site, in Solar's local Field office and in San Diego. If revised drawings are part of the project scope, the "As Installed" drawings will be returned to San Diego to be reissued. Updating the OMI manual depends on the vintage

• Provide faster updating of the service parts lists for user equipment to facilitate the ordering and provisioning of parts.

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General 7

Solar Turbines Incorporated Authors:

GTUA 2001

S. Navidi and T. Lazet

General Question Number 8 Advise current experience with resolving “pancake valve” problems. What is being done to ensure new pancake valves fit on older packages. exhaust collector areas during engine nonoperation conditions. The valve consists of two symmetrical cast housings that are bolted together. As part of the valve assembly, one housing has a threaded port to allow installation of an external connection, while the other housing has a preinstalled fitting, which functions as the valve seat, and the other external connection fitting. A spring lever holds a nitrided steel ball that functions as the valve shutoff component. When unpressurized, the lever holds the ball off the sealing fitting and the valve stays in an open position (Figure 20), allowing for drainage. During the start cycle as engine compressor discharge pressure rises, the airflow through the valve increases, causing sufficient pressure differential across the ball / lever assembly to force the ball to seat on the machined fitting (Figure 20). When the ball is seated, the pressure inside the valve rises and maintains the ball securely on the machined seat. The pre-installed machined fitting in the housing is critical to the proper functioning of the valve, since this is the valve sealing surface.

ANSWER Solar has made several material and process improvements to the pancake valve to resolve air leakage, sealing and closing problems. Our retrofit kit addresses the form, fit and function issues associated with installing the new valves on older packages.

BACKGROUND The “pancake valve” is so called due to its unique shape (Figure 19). It is a specially designed drain valve whose purpose is to facilitate the drainage of liquids, such as water or unburned liquid fuel, that have accumulated in the gas turbine combustor and

01G8-1

01G8-2

Figure 19. Valve Assembly

Figure 20. Valve Components 27

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Two drain valves are combined to properly seal the exhaust collector and the combustor during engine operation. The two drain valves are required due to the significantly different pressures that exist during engine operation between the high-pressure combustor and the low-pressure exhaust collector. The upper valve is used to drain the exhaust collector, while the lower valve is used to drain both the exhaust collector and the combustor (Figures 21 and 22). FROM EXHAUST COLLECTOR

01G8-4

FROM COMBUSTOR DRAIN

01G8-4

Figure 22. Two Drain Valve Assembly

TO PACKAGE DRAIN

the sealing ball material was changed to a corrosion-resistant nitrided tool steel. These changes to the aluminum body valve for the Saturn 10 through Taurus 70 packages were announced in Service Bulletin 8.12/102 in June of 1995. Finally, the package tubing used to connect the valves in the package was increased in size from 3/8 in. to 1/2 in. to improve valve closing functionality. Solar also previously changed the package tube fittings from 37½ degree flare to Swagelok compression fittings. Consequently, the retrofit kit, which incorrectly recommended that the 37½ degree flare sealing fitting be removed and replaced with a Swagelok fitting, resulted in excessive valve leakage. The retrofit kit has since been revised and a label added to the valve body warning against rotation of the sealing fitting. Service Bulletin 8.12/102 has also been reissued.

01G8-3

Figure 21. Cross Section of Two Valve Assembly (from retrofit kit 176968)

Improvements Over the past several years, Solar has made several improvements to the drain valves and how they are installed. First, an asbestos gasket was replaced with a non-asbestos gasket. Then, the number of bolts used to hold the two housings together was increased from 6 to 12 to eliminate an air leakage problem at the housing split line. Also,

Recommendations Since the machined sealing fitting is the valve seat, it is critical that the fitting not be loosened or re moved, because the sealing ball surface of the 28

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fitting is cold formed for tight shutoff. Tampering with this fitting causes improper functioning of the valve and results in excessive air leakage. Anytime it is necessary to install or remove a drain valve, it is important to use a wrench to hold this fitting so that it does not rotate relative to the valve housing. It is also important that the valves be installed with the tube connections in the vertical position to prevent the collection of liquids in the valve housing.

Interchangeability The aforementioned changes made to the new aluminum body valve do not affect interchangeability, with the exception that the increase in the number of mounting bolts may interfere with the valve mounting bracket. The retrofit kit addresses reworking the bracket to accept the increased number of bolts. Table 7 gives the old and new part numbers for Solar's pancake valves.

Table 7. Pancake Valve Part Numbers Engine Model

Solar's Part Number Old

Saturn 10 and Saturn 20 Centaur 40 and Centaur 50 Taurus 60 and Taurus 70 Mars 90 and Mars 100 Titan 130

Valve Body Material*

New

901086C91 or 1020281-100

Aluminum

117901-103

Stainless Steel

190786-100 117901-100

* The aluminum and stainless steel valves are not interchangeable.

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Solar Turbines Incorporated Authors:

GTUA 2001

G. Rocha and J. McClain

General Question Number 9 Please update users on Titan and Mercury experience and failure mechanisms. Table 8. Titan 130 Experience (as of April 2001)

ANSWER The Titan 130 industrial gas turbine was introduced in 1998 and has gained Field experience in mechanical-drive, compressor-set and electrical power generation applications. Product durability has been demonstrated with successful completion of an extended Field evaluation program at a commercial installation. Three minor product quality issues, involving the SoLoNOx gas fuel injectors, Stage 2 diaphragm, and Stage 2 turbine blade damper, were identified and addressed. The Mercury 50 industrial gas turbine is currently in full-scale development and Field service evaluation. More than 7000 hours of operation have been accumulated to date. Only two significant issues have been noted with this new engine. First, the compressor first bend mode is in the operating range. Although this does not result in a failure, it does require significant effort to trim balance the engine. Second, several welds in the recuperator are overstressed. As a result, recuperator air leaks can occur after only a relatively few hours of operation. Efforts are currently under way to correct both of these issues prior to commercial release.

Units Sold

42

Product Applications: Compressor Set / Mechanical-Drive Generator Set / Power Generation Units in Service

19 23 10

Total Fleet Hours

+55,000

High-Time Installed Hours

+15,000

turbine was thoroughly inspected and placed into normal commercial service with mutual agreement between Solar and the user. Based on early Field operating experience, minor design improvements to the gas turbine, package systems and controls systems have been implemented to optimize product performance, durability and reliability. The Titan 130 gas turbine design is an aerodynamic scale up of the existing Taurus 70 product. The engine features a modified Mars air compressor and turbine section components directly scaled up from the Taurus 70. The two-shaft engine is nominally rated at 14 540 kW (19,500 hp) with a simple-cycle thermal efficiency of more than 35% at ISO operating conditions (Figure 23). The singleshaft model is rated at 14 000 kWe and 34.4% efficiency at the generator terminals. Both models are available with two combustor options: a dry, low-pollutant emissions combustion system featuring Solar’s proven SoLoNOx technology or a diffusion-flame type combustor adapted from Solar's proven Mars gas turbine. (Please refer to GTUA 2001 Mars Question Number 1.)

BACKGROUND Titan 130 Gas Turbine Experience More than 40 two-shaft and single-shaft Titan gas turbines have been sold as of April 2001. These units have accumulated more than 55,000 hours of operation, with the high-time installation exceeding 15,000 hours (Table 8). The first Titan 130 mechanical-drive package was installed at a gas compressor station and operated by the user under typical pipeline gas transmission service conditions. The unit was inspected and monitored throughout the evaluation period by Solar's Engineering and Field Service personnel to record operating condition and assess product durability. At the conclusion of the planned 8000-hour evaluation period, the gas

Titan 130 Gas Turbine Failure Mechanisms Factory testing, Field evaluation testing, and initial operating experience validated the design limits and areas for improving product durability.

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Solar Turbines Incorporated

GTUA 2001 lations, all current Field units feature case bleed SoLoNOx combustion systems.

fi

Stage 2 Diaphragm. Inspection of the above engine, which was returned for repair, revealed a circumferential fracture in the web region of the Stage 2 diaphragm. The static component separates the Stage 1 and Stage 2 turbine disks and is held in position by the Stage 2 nozzle segments. The component was manufactured from a highstrength nickel-based alloy via a ring-rolled forging process. Based on finite element analysis results, mechanical loads are relatively low. Metallurgical evaluations confirmed adequate material properties in the tangential orientation, but sub-optimum material properties in the radial direction. Test-bar data from radial specimens confirmed low stress-rupture properties and notch-sensitivity characteristics. If the failure mechanism is due to the notch-sensitivity of the material, time-to-fracture and crack propagation rates cannot be accurately predicted. A material change to a similar alloy had previously been implemented to provide improved properties in both tangential and radial orientations with a ring-rolled forging process. Only initial production units are affected and continuous operation is considered a low risk.

01G9-1

Figure 23. Titan 130 Two-Shaft Gas Turbine

Design improvements and manufacturing process optimization were implemented as the new gas turbine transitioned from introductory to fullproduction status. Early Field experience led to modifications in three areas that enhanced the durability and functionality of the Titan 130 gas turbine.

SoLoNOx Gas Fuel Injectors. During a routine inspection of a two-shaft gas turbine at a pipeline compressor station, Solar's Field Service personnel detected over-temperature of the lean, premix SoLoNOx injector tips. The unit accumulated approximately 4000 hours of operation and was operating in satisfactory condition just prior to the inspection. Root-cause evaluations determined that improper control of the variable air management system (VAMS) at full-load conditions resulted in increased injector tip metal temperatures. A control logic revision for cold-ambient effects had not been implemented. Damaged injectors were replaced and the unit continued normal operations. After a scheduled engine exchange, the engine was later returned to the factory for repair of metal spray damage to the combustor liner and first turbine stage components. Although the VAM system proved effective for emissions control across most of the expected operating range, bleed assist was still required at low output loads to meet carbon monoxide (CO) emission levels. A product design improvement was implemented to remove VAMS from the SoLoNOx combustion system and simplify the overall Titan gas turbine. Except for two instal-

Stage 2 Turbine Blade Damper. Minor foreign object damage (FOD) was discovered at the Stage 2 turbine blade of a two-shaft gas turbine. The engine accumulated approximately 3100 hours of operation and was operating in satisfactory condition prior to the detected failure. Disassembly inspection confirmed one Stage 2 turbine blade damper component failed, causing minor damage to a few turbine blade tips. Failure analysis was initiated to determine the root cause of the blade damper failure. Metallurgical and manufacturing inspection data did not uncover any material defects or manufacturing anomalies in the failed and non-failed dampers. Quality records and first article qualification reports indicate all casting quality requirements were compliant. Fractured surface inspection indicated a stress-rupture failure mechanism. Analytical stress results, however, are wellbelow mechanical property limits and do not support a stress-rupture failure mode. Inspection of non-failed dampers did not reveal any surface defects or cracks. Dimensional inspections on blade and damper assembly interface surfaces revealed no discrepancies.

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GTUA 2001 stood. One of the key design requirements for the Mercury 50 engine was to optimize the modularity of the design. Since hot section components, particularly combustion liners, are the highest maintenance items in the engine, the engine was arranged to allow for the easiest replacement of these components. It was determined that the optimal layout of the engine would position the compressor behind the turbine. This would simplify the recuperator interface and reduce the size of the package. This novel engine layout was one of the most significant innovations of the Mercury 50 engine definition. Shaft dynamics, combustor size, cost, and overall package dimensions were all factored into the engine arrangement decision. This unique arrangement also allowed for the smallest engine / package footprint (Figure 25).

Mercury 50 Gas Turbine Experience The U.S. Department of Energy (DOE) initiated a program for advanced turbine systems (ATS) to serve industrial power generation markets. The objective of the cooperative agreements granted under the program was to join the DOE with industry in research and development, leading to commercial offerings in the private sector. The ATS program was envisioned to provide a power plant with ultra-high efficiency, environmental superiority, and cost competitiveness. Solar’s Mercury 50 engine (Figure 24) was the result of this program. The Mercury 50 evolved into a 4.2-MWe recuperated-cycle, single-shaft turbine with 38% efficiency (versus baseline of 28.2%) at the terminals on a 15°C (59°F) day at sea level. This engine met all the ATS program goals (Table 9). A significant effort was spent over the first several months of the contract in refining the concept for the Mercury 50. During this period, engine cycle studies played a major role in determining the progress of the engine layout. Each contributor to overall thermal efficiency was examined in detail so that the sensitivity and relationship of each aero-thermal and mechanical design parameter to the efficiency goal was fully under-

In-House Test Results. Throughout testing of the Mercury development engines, a great deal of data was obtained. Some of the data are still under evaluation. Much of the data has verified the design calculations and was used to make successful design improvements. The development test cell is configured to do a wide range of tests efficiently and has a staff that is knowledgeable with the engine hardware, the engine’s operating characteristics, and the instrumentation necessary to acquire critical data. To date, nearly 3000 hours of in-house testing have been completed on three development engines (Figure 26). In addition, more than 4000 hours of Field evaluation testing have been completed on the two high-time Field units. Solar performed a total of six short-term development tests in our development test cell using two development engines. The objective tests ranged from thermal paint tests to blade dynamic tests (Table 10). In addition to these short-term tests, Solar performed an extended endurance test at our Harbor Drive facility (Figure 27). A complete Mercury package was installed and connected to the local grid. This unit provided the majority of electrical power required at the Harbor Drive facility throughout most of 2000. More than 2500 hours of operation have been accumulated on this unit.

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Figure 24. Cutaway of the Mercury 50 Engine

Table 9. ATS Program Goals Program Criteria % Efficiency Improvement (vs Baseline) at bus bar Cost of Power, % NOx, ppmv Availability, %

ATS Program Goal

Mercury Target

Demonstrated in Test

+15 (vs 28.2) = 32.4% -10 <9 97

+35 (vs 28.2) = 38.0% -15 <9 97

+29 (vs 28.2) = 36.3% -13 <9 TBD

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Figure 25. Engine Cross Section Showing Airflow

Field Service Evaluation. In addition to these inhouse tests, five evaluation sites have accumulated more than 4000 operating hours:

8000

Hours on Test

7000

Mercury 50 Test Program

6000

1. WMC Phosphate processing plant in Queensland, Australia

5000 4000

2. Municipal utility in Rochelle, Illinois, U.S.A. 2576

3000

2072

3. University in Clemson, South Carolina, U.S.A. (Recently installed)

2030

2000 1000

4. Rural utility in Lamar, Colorado, U.S.A. (Being installed

95.7

297

S/N 001

S/N 002

0 S/N 004

WMC

Test Engine

Rochelle

5. Hospital outside Paris, France. (Being installed)

01G9-4

Figure 26. Test Hours through 2000

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Table 10. Test Summary – Short-Term Tests Engine S/N – Build ESN 1-1 ESN 2-1 ESN 1-2 ESN 2-2 ESN 1-3 ESN 2-3

Test Hours

Objective

91 135 2 159 3 3

Engine Operability Engine Performance Turbine Thermal Paint Test Engine Performance Blade Dynamics – Rotating Instrumentation Turbine Performance

Early engine experience identified three areas for improvement:

Rotordynamics. As a result of engine testing in 1999, the compressor first bend vibratory mode was found to be in the operating range. The frequency of this mode was coincident with 90% operating speed. Although the engine could pass through the mode and operate normally, the vibration levels while passing through the mode were quite high. This was determined to be unacceptable for large volume production. Therefore, the center section of the engine was redesigned to move the vibratory mode above the operating range. The rotor system was shortened by 152 mm (6 in.), the center frame was replaced with a much stiffer exhaust diffuser, and the compressor rotor was stiffened. As a result, the compressor first bend mode has been shifted to approximately 120% operating speed. Hardware is currently being procured to test this revised configuration.

01G9-5a

Recuperator. Endurance testing during 1999 and 2000 also identified a shortcoming in the design of the recuperator. The recuperator is a complex structure and accurately predicting stress levels within it is difficult. Testing revealed that the stress in several of the welds exceeded allowable levels. For the revised configuration, the alloy of selected components has been changed from 347SS to Haynes 230. This will more than double the allowable stress in the critical welds.

Performance. In addition, several modifications were incorporated into the design to increase engine performance. Three hundred cells were added to the recuperator, end wall film cooling was added to the Stage 1 turbine nozzle, and compressor Stages 1 and 2 were re-redesigned. It is anticipated these modifications will allow the engine to meet the Mercury target performance given in Table 9.

01G9-5b

Figure 27. Mercury 50 Development Test Cell and Harbor Drive Facility

34

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Solar Turbines Incorporated Author:

GTUA 2001

R. Eimers

General Question Number 10 Does Solar have any new developments of interest to users? ANSWER New developments at Solar include uprates of the Taurus 70 and Taurus 60 gas turbines, a new Taurus 60 mobile power unit, and advancements in combustion system technology.

BACKGROUND Taurus 70 Gas Turbine The Taurus 70 was introduced in a hot-end drive, two-shaft configuration (Figure 28) in 1995 and in a cold-end drive, single-shaft configuration (Figure 29) for generator applications in 1999. The air compressor section of the engine consists of a modified Taurus 60 compressor with an additional stage on the front to increase airflow and an additional stage on the back to raise pressure ratio. The combustor and turbine sections were new, but adopted Mars gas turbine technology: the initial firing temperature and pressure ratio were the same as the Mars gas turbine. At the initial production firing temperature of 1120°C (2050°F), the rating was 7230 kW (9700 hp) for the mechanical-

01G10-2

Figure 29. Taurus 70 Single-Shaft Gas Turbine

drive version and 7200 kWe for the generator set. With the use of advanced aerodynamics and heat transfer technologies, 34% thermal efficiency was achieved. The durability of the Taurus 70 has been excellent, with the initial Field evaluation engine actually achieving 41,000 hours before being returned for overhaul. To date, a total of 124 engines have been sold, with a total of more than one million fleet operating hours. As mentioned in GTUA 2001 General Question Number 9 relative to our Titan 130 experience, the Titan 130 is an aerodynamic scale up of the Taurus 70 gas turbine. With the use of today’s parametric design and analytical tools, it is possible to modify and uprate the two engines with essentially parallel development efforts. Hence, the cold-end drive, single-shaft versions of these engines for generator applications were introduced within six months of each other and the recent increase in firing temperature to 1150°C (2100°F) that was applied to the Titan 130 engine is also being applied to the Taurus 70 engine. The increase in firing temperature will result in a 6.2% increase in shaft power to 7690 kW (10,310 hp) for mechanical-drive applications and a rating of

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Figure 28. Taurus 70 Two-Shaft Gas Turbine 35

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GTUA 2001

7520 kWe for generator applications. Thermal efficiency at the shaft increases to 34.8%, while efficiency at the generator terminals increases to 33.8%. For exhaust heat recovery applications, the exhaust temperature increases by 14°C (26°F) to 485°C (906°F). The design changes for the Taurus 70 to accommodate the increase in firing temperature are basically the same as the design changes we made to the Titan 130 engine. The primary change is to the Stage 1 and 2 turbine blade material with the incorporation of single-crystal alloys and a redesign of the SoLoNOx combustor / injector system. There were also some minor changes to optimize the secondary cooling flows and effectiveness. The low emissions SoLoNOx version of the engine for both mechanical-drive and generator applications has been in production since July 2000. The conventional combustion version is currently undergoing qualification testing and will be available for production shipments in November 2001.

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Figure 31. Taurus 60 Single-Shaft Gas Turbine

first and second-stage nozzles is being incorporated to allow an increase in firing temperature from 1029 to 1065°C (1885 to 1950°F), with no degradation in durability. Design of forward and aft rim seals on the Stage 1 turbine disk is also being modified, as well as a new Stage 2 nozzle casting and changes to the compressor aft hub material. Thermal efficiency will change from 30.3 to 30.4% in the single-shaft configuration, while the two-shaft configuration will remain at its current level. Exhaust temperatures will increase from 485 to 510°C (905 to 950°F) for the single-shaft and from 490 to 510°C (914 to 950°F) for the two-shaft configuration (Table 11). The first performance testing is scheduled for May 2001 and the first production shipments for the single-shaft, cold-end drive version for generator applications is scheduled for June 2001. The first production package for the two-shaft, hot-end drive version is scheduled for October 2001. The development of the SoLoNOx combustor with the new augmented backside cooling (ABC) liner for the Taurus 60 is scheduled for an engine test in July 2001. In October 2001, Solar plans to ship the first production packages for both the coldend and hot-end drives, gas only. In March 2002, the first dual fuel engines are scheduled to be available. All of these component upgrades will be retrofittable to existing Taurus 60 gas turbine packages at overhaul.

Taurus 60 Gas Turbine Since its introduction in 1989, the Taurus 60 gas turbine (Figures 30 and 31) has been the fastest growing population of any industrial gas turbine in th the world. The 1000 unit was shipped the first quarter of 2001 and the installed units have accumulated more than 20 million operating hours. The current rating of the single-shaft, cold-end drive version is 5200 kWe, with plans in progress to upgrade the performance to 5500 kWe. An improvement in the material for the first and secondstage blades and revised cooling systems for the

Mobile Power Unit. The Taurus 60 gas turbine generator package is now being packaged as a mobile power unit to produce reliable, low-cost, onsite peaking power to optimize service for seasonal or cyclical loads (Figure 32).

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Figure 30. Taurus 60 Two-Shaft Gas Turbine

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Table 11. Taurus 60-7800 ISO Performance – 15°C (59°F), Sea Level Performance

Current

Uprate

Single-Shaft • Turbine Rotor Inlet Temperature

1029°C (1885°F) 5200 kWe 30.3%

1065°C (1950°F) 5500 kWe 30.4%

485°C (905°F)

510°C (950°F)

• Thermal Efficiency

1090°C (1995°F) 5330 kW (7150 hp) 32.0%

1065°C (1950°F) 5740 kW (7700 hp) 32.0%

• Exhaust Temperature

490°C (914°F)

510°C (950°F)

• Output Power • Terminal Efficiency at Terminals • Exhaust Temperature Two-Shaft • Turbine Rotor Inlet Temperature • Output Power

Combustion System Developments In 1992, Solar introduced the first industrial gas turbines employing a lean-premixed combustion system for emissions control. Since then, Solar has placed more than 730 SoLoNOx gas turbines into service. These turbines are routinely meeting emissions limits as strict as 25 ppmv NOx and 50 ppmv CO (15% O2) on natural gas. Other gas turbine manufacturers have followed suit and, at this time, nearly every manufacturer has introduced a dry low emissions (DLE) gas turbine product line based on lean-premixed combustion. Advantages of lean-premixed combustion include the concept’s proven potential for low NOx emissions, a similarity in physical arrangement to conventional combustion system hardware, and Solar’s extensive lean-premixed technology base developed through earlier research work. For more details on Solar’s combustion system developments, please refer to the technical paper "Developments in SoLoNOx Low Emission Systems," TPSoLoNOx.

01G10-5

Figure 32. Taurus 60 Mobile Power Unit

Introduced in November 2000, the Taurus 60 mobile power unit is a trailer-mounted system that is highway transportable and easy to install and relocate, making it ideal for rental fleets and utility equipment pools. The compact footprint minimizes the space requirements at substations or commercial / industrial facilities. It comes standard with low emissions, state-of-the-art, SoLoNOx dry low NOx combustion system technology, making it environmentally friendly and easy to permit. The unit is dispatchable to be on line in six minutes from cold start. A dual fuel combustion system provides the flexibility of operating on either natural gas or diesel fuel. It features a range of control system options for remote operation and SCADA integration, as well as KVAR control for excellent reactive power capability. The unit is offered with a wide range of product support programs, ancillary support systems, site preparation, set-up, and commissioning.

Advanced Combustor Technologies In response to the trend toward more stringent emissions regulations, gas turbine manufacturers are assessing their current lean-premixed systems to establish viable combustion system enhancements. The areas that exhibit the greatest potential for technology developments include: • Control of combustor pressure oscillations • Control system development • More robust dual fuel capability • Advanced combustor liner technologies 37

General 10

Solar Turbines Incorporated

GTUA 2001 Currently, more than 100 dual fuel engines have been sold and the high-time unit has more than 45,000 operating hours. Dual fuel injectors are available for retrofit into existing gas-only turbine engines. The need for dual fuel injectors to have gas and liquid fuel main passages, gas and liquid fuel pilot passages, and a pilot air passage makes these injectors very complex. Blockage of liquid fuel ports or the degradation of liquid fuel injection patterns due to coking is a major concern in the dual fuel SoLoNOx design and is the primary focus of our near-term development efforts.

Combustor Pressure Oscillations. The introduction of lean-premixed combustion systems for gas turbines has raised manufacturer awareness of the consequences of large combustor pressure oscillations. Simply put, lean flames have a greater tendency to cause pressure oscillations, which can lead to engine damage. It is recognized that the reduced stability of a lean-premixed flame contributes to combustor oscillations. One of the keys to the long-term resolution of this problem is design optimization of the fuel injector premixing section. Improved fuel injector configurations have now been developed. Pressure oscillations are low at all points within the operating envelope and do not require high levels of pilot fuel. These new fuel injector designs are now being incorporated into production machines and have provided additional margin against the NOx guarantee level of 25 ppmv.

Advanced Combustor Liners. The development of an advanced combustion liner with more effective cooling technologies will provide a two-fold benefit in terms of emissions. First, CO emissions will be reduced due to the improved ability to control reaction quenching. Second, the lower CO levels will allow combustor reoptimization to a lower flame temperature. This will produce lower NOx levels, along with lower CO concentrations. A enabling technology being advanced is the augmented backside cooled (ABC) liner. Backsidecooled liners forego cooling air injection completely. Instead, combustor wall temperatures are controlled solely through convective cooling by a high velocity airstream on the cold side of the liner. In most instances, the high heat flux from the flame requires augmenting of the backside convective process to keep liner wall temperatures from becoming excessive. Turbulators in the form of trip strips, fins, and pins act to increase the cooling flow turbulence at the liner wall and augment the heat removal process. An additional degree of liner protection can be achieved through the application of a thermal barrier coating (TBC) on the hot sides of the liner walls. Development test results with this technology are very encouraging, with significant reductions in emissions and uniform combustor wall temperatures. Field testing of a production configuration is under way and several additional units will be commissioned in the near future.

Control Systems. The SoLoNOx gas turbine control system is identical to the conventional gas turbine control system at start-up and low-load operation, but differs when the gas turbine operates in the low emissions mode (above approximately 30 to 50% of the rated load). The control system for SoLoNOx engines modulates the variable geometry systems to keep the combustion primary zone temperature within a specified range. Accurate control of the primary zone temperature is critical to controlling NOx and CO emissions. Future operating objectives will require advanced control algorithms and closed-loop control systems with electric actuation of variable pilot and main fuel control valves to more accurately maintain the engine primary zone temperature (Tpz). Dual Fuel Capability. Dual fuel capabilities can improve equipment availability during periods of primary fuel curtailment and potentially offer the ability to arrange a more user-favorable price structure for the primary fuel. The first dual fuel SoLoNOx combustion system in the Centaur 50 gas turbine was commissioned in November 1994.

38

General 10

Mars Question

Solar Turbines Incorporated Author:

GTUA 2001

C. Brown

Mars Question Number 1 What is current experience with T14000 and T15000 and what failure mechanisms have been seen? was replaced. (Please refer to GTUA 2000 Mars Question Number 4 and Service Bulletin 8.8/112.)

ANSWER As of March 2001, there are 405 Mars 14000 and Mars 15000 gas turbine packages throughout the world, with approximately 4.6 million total operating hours. Past issues have been addressed in previous GTUA reports and/or Service Bulletins. Current issues are discussed herein with the implementation plan in progress.

Dual Fuel Injector Fouling. Mars 100 dual fuel units experienced fouling of the injector gas fuel passages. Liquid fuel was found to migrate into the gas side and clog (coke) the passageway. A purge kit using turbine compressor discharge pressure (PCD) air was developed and implemented to remedy this situation. The purge kit was retrofitted into Field units and introduced into new production units in June 1999. (Please refer to GTUA 2000 Mars Question Number 1 and Service Bulletin 3.3/106.)

BACKGROUND Mars 100 Gas Turbine The Mars 100 product line (Figure 33) consists of the 14000 model (introduced in 1989) and the 15000 model (introduced in 1995). The 15000 differs from the 14000 in that compressor airflow is increased by opening up the flow path at the firstand second-stage compressor blades. The Mars 100 is an uprate of the Mars 90 product line, which consists of the 12000 model and the 13000 model. The uprate included the following:

PCD Purge System. Two units retrofitted with the new PCD purge kit experienced failures. In both cases, severe Stage 1 nozzle damage was evident, consistent with burning in the turbine cooling flow circuit. Based on our investigation, improper or incomplete implementation of the purge system logic is believed to be the cause of these failures.

• Firing temperature increased from 1055 to 1120°C (1935 to 2050°F) turbine rotor inlet temperature (TRIT).

Starter Clutch Durability. The Mars starter clutch began having durability problems in late 1997. This sprag-type clutch underwent two redesigns and was recently upgraded with the introduction of a new spline-type clutch. (Please refer to GTUA 2000 Mars Question Number 5 and GTUA 1999 Mars Question Number 6.) This new clutch reduces stress levels and eliminates starter motor rotation after starter dropout. Clutches with the new design, introduced into production engines in the first quarter 2001, are available if users wish to upgrade their existing clutch. (Please refer to Service Bulletin 2.0/102 and Service Bulletin 2.0/103.)

• Stage 1 blade material changed from Mar M 247 Equiax to CMSX-4. • Stage 2 blade material changed from IN 792 to CMSX-3. • Cooling flow modifications introduced into Stage 2 nozzle.

Past Issues Addressed Previously at GTUA Combustor Liner Panel Distortion. Mars 100 conventional combustion units in operation with P/N 198834 injectors exhibited distortion of the combustor liner cooling panels due to overheating of the liner. This was resolved by introducing the P/N 301380 “cutback” injector. In some cases, the liner

Bearing Failures. The Mars product line featured tri-metal radial bearings. When these bearings are exposed to high temperatures over an extended period of time, they become susceptible to corrosion. After an extensive development effort, the tri39

Mars 1

Solar Turbines Incorporated

GTUA 2001

Figure 33. Typical Mars Gas Turbine Cutaway

metal bearing was replaced with the bi-metal bearing design, in addition to other improvements. (Please refer to GTUA 2000 Mars Question Number 3 and GTUA 1999 Mars Question Number 3.) The bi-metal bearing has not suffered a corrosion failure in the Mars product line to date. Approximately two- thirds of the nearly 750 Mars 100 and Mars 90 engines in the fleet have the latest bearing configuration.

5.9/103, 6.5/107, 6.5/108, 6.5/109, and 6.6/102 announced improvements to the post shutdown lubrication system, re-emphasizing to users the need for proper post lubrication and maintenance of the subsystems associated with providing this lubrication. Compressor Blade Failures. Since 1989, one Stage 8 and six Stage 14 cast compressor blades have failed in high-cycle fatigue. The problem, whose root cause was improper grinding of the dovetail, has been corrected in manufacturing for both new production and overhauled units.

Interruption of Post Shutdown Bearing Lubrication Failures. The radial bearings in the Mars engine must go through a post shutdown lubrication cycle. If this cycle is interrupted for more than 20 minutes, bearing damage will likely occur, most notably to the No. 2 and No. 3 bearings and especially if a restart is attempted before the bearings have had a chance to cooldown. Service Bulletins

Variable Stator Vane Lockup. Several Stage 3 and Stage 4 forged compressor blades failed in high-cycle fatigue. The root cause of the failure was attributed to external contamination of the inlet guide vane (IGV) mechanism, preventing proper 40

Mars 1

Solar Turbines Incorporated

GTUA 2001

guide vane operation and causing amplified aerodynamic blade excitation. (Please refer to Service Bulletin 8.6/107.)

Number 7. The SoLoNOx process, which uses a lean premix of fuel and air, must maintain a balance between emissions control and combustor pressure oscillations or combustor rumble. Oscillations and/or rumble have been reported at some Mars gas turbine installations where operation over a wide range of ambient temperatures at varying loads is necessary. Information on combustion instability characterized by combustor oscillations and rumble, together with the description of a kit for monitoring oscillations is described in Service Bulletin 5.4/116. Combustor oscillations were resolved by the new SoLoNox injector P/N 300457. The injector fuel spokes were moved 3/8 of an inch downstream, fully attenuating the 360-Hz oscillations. The technical details of this effort are found in ASME paper number 99-GT-052. In conjunction with the P/N 300457 injectors described above, a variable pilot fuel system was incorporated to maintain part-load emissions compliance and increase rumble margin. In very general terms, smaller percent pilot is required at or near full load to meet NOx compliance, and percent pilot is increased at lower load ranges to provide combustor stability without compromising emissions. The variable pilot system uses a new wide range fuel control valve. The entire system is now standard on all new production packages and is recommended for Field units. A Service Bulletin describing the availability of the wide range fuel control system is forthcoming.

Current Issues SoLoNOx Engines and Part-Load Operation. Three issues have been associated with some Mars SoLoNOx units run primarily at part load and particularly at low ambient temperatures: 1. Case bleed duct hose failures 2. Combustor liner cracking 3. Combustion instability First, the single 4-in. diameter bleed hose between the combustor case and the exhaust collector was developed to replace the injector bleed manifolds on SoLoNOx units. The design and implementation of the hose was accelerated to provide an immediate remedy to the injector bleed hose failures, which had potential safety implications. The engineering qualification process, which was delayed until after the hoses were installed in the Field, found the hoses to be subject to highcycle fatigue failure. Subsequently, the 4-in. diameter hoses are being replaced with a 6-in. diameter hose. Since March 2000, approximately 40 units have received the larger hose and no problems have been reported. The 6-in. diameter hose kit can be ordered through Service Bulletin 8.8/108B. Second, testing conducted in Solar’s development test facilities in San Diego found that changing the extraction of bleed airflow from the injectors to a port on the combustor case caused a disturbance in the combustor liner cooling flow. It was determined that during part-load operation, a vortex is set up in the region between the bleed port and the combustor liner. This vortex is strong enough to draw combustion air back through combustor liner cooling holes in the liner. This uneven temperature distribution caused some liners to crack downstream of the disturbance. A baffle was designed and is available as a Field retrofit. A Service Bulletin to announce this retrofit will be issued shortly. Third, operation of Mars SoLoNOx engines at part load may cause combustor instability. This subject was reported in GTUA 1999 Mars Question Number 4 and GTUA 1997 Mars Question

Collapsed Oil Drain in Engines with a Scavenged Bearing Lubrication System. An oil drain tube collapsed in a Mars 100 standard combustion dual fuel unit on the test stand. The engine was designed with a scavenged bearing lubrication system for operation on an oil and gas production tanker (FPSO). The drain collapsed because stiffening tubes were not installed in the drain passageway as specified on the engineering drawings. Oil backed up into the compressor diffuser housing and turbine nozzle case areas. The insulation surrounding the No. 2 bearing housing became soaked with oil and caught fire. This problem was successfully corrected. Also, a retrofit kit is being developed to repair the 13 known units in the Field with this particular scavenged bearing lubrication system design.

41

Mars 1

Saturn Questions

Solar Turbines Incorporated Author:

GTUA 2001

J. Frailich

Saturn Question Number 1 What is the current experience with T1600 and what failure mechanisms have been seen? • Increased life span of the first- and secondstage blades through a material change from Mar-M-421 to Mar-M-247 DS and Mar-M-247 Equiax, respectively, along with the addition of corrosion-resistant platinum aluminide coating.

ANSWER The operating performance of the Saturn 1601 and 1602 gas turbine packages has been very positive. Only eight units, representing 6.1% of the total installed population, were returned due to a failure mechanism.

• Improved rotordynamics through the incorporation of the No. 3 tilt-pad bearing in singleshaft engines and the No. 4 and No. 5 ramp bearings of the power turbine in two-shaft engines.

BACKGROUND Solar’s extensive experience with previous Saturn gas turbine models (Figures 34 and 35) has successfully been applied to the Saturn 1600 product line. This has resulted in a robust and reliable power plant that has logged more than 2.7 million hours in the field without major technical difficulties. Since their inception in 1995, out of 131 units, which have been deployed to areas around the world covering nearly all environmental conditions, seven units were returned for their scheduled inspection and repair to Solar’s overhaul facilities after 30,000 hours of operation. Eight units experienced the following failure mechanisms: • Three units – Compressor rotor forward cone spline damage • Three units – Carbon seal damage

01S1-1 01S1-1

• One unit – High vibration levels

Figure 34. Saturn Two-Shaft Engine

• One unit – High emissions Of these four reasons for engine removal, only the damaged spline required design modification. This involved engineering an improved fit to prevent excessive wear between the forward cone and the gearbox hub coupling interface.

Product Improvements The product was also upgraded in two significant areas, which were prompted by ongoing product improvement:

01S1-2

Figure 35. Saturn Single-Shaft Engine

42

Saturn 1

Solar Turbines Incorporated Author:

GTUA 2001

J. Frailich

Saturn Question Number 2 What developments are underway to improve carbon seals throughout Saturn range. No. 2 and No. 3 bearing areas would not be a costeffective solution for Saturn gas turbine users.

ANSWER No developments are under way to improve carbon seals in Saturn gas turbine models.

Economic Considerations Switching to labyrinth seals would require a major redesign of the compressor aft hub and the No. 2 and No. 3 bearing housings. It would also have a major impact at overhaul due to the higher repair costs involved.

BACKGROUND The Saturn gas turbine has had a successful track record for 40 years operating in a wide variety of applications. The only option for improving the carbon seals used in the Saturn product line is to replace them with labyrinth seals. Based on an analysis of economic and mechanical considerations, modifications to the sealing systems in the

Mechanical Considerations Table 12 compares the two types of seals.

Table 12. Comparison of Carbon Seals and Labyrinth Seals Type of Seal

Favorable Considerations

Unfavorable Considerations

Carbon Seals (Contact Type)

1. Carbon self-lubricating capability allows dry running at extreme operating conditions. 2. Double sealing capability in axial and radial directions. 3. Leakage ranges from zero to minimum amounts. 4. Floating capability of carbon elements allows for shaftdisplacement compensation. 5. Compact construction simplifies installation where space is limited and replacement when damaged.

1. Require precise location with respect to sealing surface. 2. Must keep surface flatness and surface finish within close tolerances. 3. Life is dependent on mechanical loads acting on carbon elements.

Labyrinth Seals (NonContacting Type)

1. Cause no frictional losses. 2. Require no axial adjustment. 3. Life is dependent on degree of rotor operational instabilities.

1. Leakage is dependent on seal-to-shaft clearance. 2. Require a high degree of rotor concentricity to achieve minimum to no rubbing. 3. For incidental rubbing, a soft surface must be provided. 4. Manufacturing requires complex processes and so does their repair.

43

Saturn 2

Solar Turbines Incorporated Author:

GTUA 2001

C. Aylwin

Saturn Question Number 3 Please confirm that there are no plans for phase out of Saturn. Advise plans for upgrades to Saturn including on skid controls and SoLoNOx. Advise any developments of a successor in the 1 MW class. shaft 1210 kWe rating for generator sets. There are no plans for further power upgrades at this time or for the incorporation of a dry low emissions (DLE) combustion system. New production units are available with onskid controls. Solar’s Package Refurbishment facility in Mabank, Texas, offers a wide range of package and control upgrades for the Saturn product, including:

ANSWER Solar does not have any plans to phase out the Saturn gas turbine, to upgrade the Saturn gas turbine for SoLoNOx combustion system, or to develop a successor for the Saturn gas turbine. The Saturn gas turbine, however, is now available with onskid controls.

BACKGROUND

• Onskid PLC controls with remote communications options

Since its introduction in 1960, the Saturn industrial gas turbine has been an industry leader in the 1000-kW (1500-hp) class with its rugged durability and 4800 units installed throughout the world. The current plans for the Saturn turbine are focused on refinement of the package features at its two-shaft 1185-kW (1590-hp) rating for compressor sets and mechanical-drive packages and its single-

• Fuel, start and lubrication systems • Increased power output • Compressor restages • Package enclosure with fire systems • Water injection for emissions control

44

Saturn 3

General All Question

Solar Turbines Incorporated Author:

GTUA 2001

S. Sedgewick

General Question to All Manufacturers Number 1 Advise Solar’s plans for Internet technology to support users. that addresses the continually changing user needs throughout a project’s life cycle; from design, construction, and operation to refurbishment or decommissioning. The result of this team’s work is a strategy that utilizes personalized, interactive, webbased technology to optimize the value, speed, accuracy, and efficiency of user interactions. Using world-class, state-of-the-art content management software, Solar launched the new site (Figure 36) in April 2001. Based on priorities conveyed by Solar's customers, this release included general information about Solar Turbines, our

ANSWER Solar recently launched an updated website. Several releases are planned for this site, which underscores our commitment to make the information you need as accessible to you as possible. We invite you to visit us and encourage you to register at: www.solarturbines.com

BACKGROUND In 2000, Solar put together a diverse, crossfunctional team to design an e-business strategy

01GA1-1

Figure 36. Solar's Updated Web Site 45

All 1

Solar Turbines Incorporated

GTUA 2001

products and services, as well as applications of our products. Users are encouraged to register since that will provide a more personalized web experience. As Solar continues to expand our web site and enhance the site's functionalities, some of the features to be made available through a series of web site releases include:

Solar’s objective is to enhance customer personalization for their specific site, making the customer's experience more comfortable, pertinent and efficient. Solar is also developing additional functionality through targeted applications designed to empower and inform our customer' regarding planning and procurement processes. Understanding that each customer's relationship and interface with Solar is unique, by design the site will focus on complementing our existing support and communication channels through this information technology pathway. Solar has dedicated a team of people actively engaged in growing our web site to address the breadth of our customers' needs. Leveraging the openness and goodwill throughout our end-user constituency, we aspire to work closely with our customers to refine and enrich their experience with Solar's web site.

• Detailed product brochures • Technical training course information and scheduling • Service Bulletins • Technical papers • Customer-specific as-shipped photographs • Case studies • Customer-specific Operation and Maintenance Instruction manuals

46

All 1

Appendix

Solar Turbines Incorporated

GTUA 2001

Appendix REFERENCE MATERIAL Source material referenced in Solar's GTUA 2001 Report are provided in this section.

Number

Section Reference

Title

Prior GTUA Answers M-7

GTUA 1997 Mars Question Number 7...................................................................................M-1

GS-1

GTUA 1998 General Question to Solar Number 1.................................................................G-5

T70-1

GTUA 1999 Taurus Question Number 1 ...............................................................................G-5

M-3

GTUA 1999 Mars Question Number 3...................................................................................M-1

M-4

GTUA 1999 Mars Question Number 4...................................................................................M-1

M-6

GTUA 1999 Mars Question Number 6....................................................................... M-5 (2000) M-1

M-1

GTUA 2000 Mars Question Number 1...................................................................................M-1

M-3

GTUA 2000 Mars Question Number 3...................................................................................M-1

M-4

GTUA 2000 Mars Question Number 4...................................................................................M-1

M-5

GTUA 2000 Mars Question Number 5...................................................................................M-1

Technical Papers ASME 99-GT-052

Passive Control of Combustion Instability in Lean Premixed Combustors ...............M-1

TPSoLoNOx

Developments in SoLoNOx Low Emission Systems...............................................G-10

TTS104

Increasing Turbine Life through Improved Maintenance Procedures ......... GS-1 (1998) G-5

TTS106

Lube Oils for the Industrial Gas Turbine ...................................................................G-5

Service Bulletins 2.0/102A

Mars Overrunning (Sprag) Clutch)............................................................................. M-6 (1999) M-1

2.0/103

Starter Clutch Improvement ...................................................................................................M-1

3.3/106A

Fuel Migration ............................................................................................................ M-1 (2000) M-1

5.4/116

Mars SoLoNOx Combustor Oscillations and Combustor Rumble .........................................M-1

5.9/103A

Battery Charger Adjustments ..................................................................................... M-3 (1999) M-3 (2000) G-6 M-1

A-1

Appendix

Solar Turbines Incorporated

GTUA 2001

Service Bulletins, Contd 6.0/123A

Changes in Lube Oil Pressure and Temperature to Increase Lube Oil Life .............. M-3 (1999)

6.5/107

Post Lube Requirements after Engine Shutdown ...................................................... M-3 (1999) M-3 (2000) G-6 M-1

6.5/108B

Backup Post Lubrication Control System Enhancements.......................................... M-3 (1999) M-3 (2000) G-6 M-1

6.5/109A

Periodic Battery Maintenance and Testing of Backup Lube System ......................... M-3 (1999) M-3 (2000) G-6 M-1

6.6/102

Mars Pneumatic Backup Lube Oil Pump Replacement.........................................................G-6 M-1

8.6/107

Variable Stator Vane Lockup .................................................................................................M-1

8.8/108B

Fuel Injector Bleed Hose Failures and Case Bleed Duct Failures .........................................M-1

8.8/112

Mars 100 Standard Combustion Combustor Liner / Injector Durability..................................M-1

8.12/102A Combustor/Exhaust Collector Drain Valve.............................................................................G-8

Engineering Specification ES 9-98E

Fuel, Air, and Water (or Steam) for Solar Gas Turbine Engines............................... M-7 (1997) M-4 (1999) G-5

A-2

Appendix

Author: K. Kubarych/A. Criqui Presenter: A. Criqui

General Question to Solar Number 1 What is the time between overhauls for all Solar engines - Saturn, Centaur, Taurus and Mars? We would like this answered for different loads and are start-ups cycles part of the equation?

(At the GTUA session on June 15, 1998, Solar showed actual data on early engine returns, expressed as an annual percent of the operating fleet of similar engines. Returns for extraneous causes, such as mentioned herein, were not included. These data are not included in this book for competitive reasons.) The recommended overhaul interval for all Solar engines is 30,000 hours. Actual experience varies widely and the following sections explain the factors involved. This recommendation not to exceed 30,000 hours between overhauls applies to all engines rated for continuous duty service irrespective of the actual load profile. Solar does not apply a penalty for start cycles except where multiple starts per day are routine, as in marine propulsion service.

As a general rule, corrosion and high cycle fatigue are the primary concerns of the cold sections of the engine such as the compressor. The hot section has life limitations from creep/stress rupture, high and low cycle fatigue, high temperature oxidation, and hot corrosion. Life of oil film journal and thrust bearings is theoretically unlimited, but, practically, may wear or suffer corrosion effects due to degraded oil.

COMPRESSOR SECTION BACKGROUND

Corrosion of the compressor section has historically been a significant life-limiting factor. However, with the use of more corrosion-resistant materials, such as 17-4 PH stainless steel and Alloy 718, and the development of compressor coatings, such as the widely used SermeTel inorganic aluminum coatings and better inlet air filtration, compressor corrosion is much less of a problem in today's gas turbines. The primary design consideration for compressor durability is the avoidance of fatigue failures. Careful design analysis is required to accurately understand the natural frequencies of each airfoil, both rotating and stationary. The analytical capability available to today s design engineer has significantly improved with the implementation of computer modeling and finite element analysis (FEA). Sophisticated computer modeling can accurately predict the airfoil natural frequencies, allowing rapid optimization of the airfoil geometry so as to avoid any known sources of excitation. The results are typically shown on a Campbell diagram (Figure GS1-1). Because knowledge of excitation sources is incomplete and the fact that white noise is always present, accurate fatigue properties of the airfoil materials are required and used in an analysis to assess the airfoil durability under a

Solar has developed life determination methodologies over the past 35 years that are intended to assure designs that provide long and reliable service lives. The goal of any design life methodology is to adequately account for any potential failure and wear-out mechanisms. In most cases, a balance between component design life and cost must be made. The design of a complex machine, such as a gas turbine, requires extensive analysis and testing. Unlike flight propulsion engines, industrial gas turbines do not experience a "typical" duty cycle. One engine may be in a base-load power generation application, another in a low power gas compression application, and a third in intermediate or standby service. These require the gas turbine designer to resort to the worst-case scenarios while developing the design. Solar has traditionally based its design life on continuous duty at maximum power or $T5 topped# conditions. The fundamental life-limiting considerations typically are creep and stress rupture, high and low cycle fatigue, corrosion, high temperature oxidation, and wear. Each one of these material degradation mechanisms must be accounted for in a successful design. GS-1

Figure GS1-1. Campbell Diagram and Computer-Generated Mode Shapes

temperature air heats the airfoil and, with today's firing temperatures, the airfoil, if not cooled, would only have a life of a few hours. By passing compressor discharge air through the hollow airfoil, the metal temperature is reduced. A balance must be struck between the amount of cooling air used and the airfoil wall thickness. The greater the amount of air used, the cooler the airfoil metal will be, however, this comes at a loss to the thermodynamic cycle efficiency. Likewise, the thicker the airfoil wall, the lower the stress and the longer the life. However, a thicker wall is more difficult to cool and requires more cooling air. Typically, a Solar gas turbine air-cooled blade design goal will be based on a 60,000-hour life so as to allow for two overhaul periods. The blade airfoil stresses and temperatures will then be optimized to achieve this life goal. The design methodology typically employs stress rupture data in the form of a Larson-Miller parameter plot and must be developed by material testing at conditions similar to those expected in the engine (Figure GS1-3). The Larson-Miller parameter combines temperature and time into one variable and, when plotted against stress, provides a means to rapidly optimize blade life.

forced excitation. The design goal is to have adequate dynamic capability to withstand reasonable levels of broad band excitation.

TURBINE SECTION Stress Rupture Considerations The hot section of a gas turbine represents the most challenging section of the engine in terms of assessing life. Many components are expected to operate for long periods of time at high temperatures and at high stresses. It is the clear challenge of a gas turbine design effort to accurately establish the temperature the materials must withstand and create a geometry that develops stresses at a level that yields adequate life. The life can be set by either using creep or stress rupture criteria depending upon the quality and availability of the materials data. Due to the greater abundance of stress rupture data, these data are the most commonly used criteria. For example, an air-cooled Stage 1 turbine blade is the collaborative effort among an aerodynamicist, a heat transfer engineer, and a structural design engineer (Figure GS1-2). The airfoil shape is optimized to extract an optimal amount of work from the gas path air. This high GS-2

Figure GS1-3. Creep/Stress Rupture Material Testing

Environmental Considerations In the design of high temperature components, the effects of high temperature oxidation must also be considered. Oxidation rates for a particular material must be measured experimentally in a laboratory. Then, through a knowledge of the gas turbine component temperature, an assessment of life can be made. Because it is nearly impossible to reproduce in the laboratory the exact conditions a gas turbine component will see, a certain amount of empirical judgment is also required. Hot corrosion

Figure GS1-2. Cooled Turbine Blade Design Generation

GS-3

is another life-limiting concern and is most commonly associated with the effects of fuel contaminated with sodium and sulfur, although air contaminated with sodium and potassium can lead to severe corrosion attack. The sodium and sulfur combine in the combustor to form sodium sulfate, which can precipitate as a liquid salt on hot section component surfaces. This molten salt tends to flux away the native protective oxide on the superalloy surface, leaving it essentially unprotected and vulnerable to additional oxidation. Rapid material wastage rates can result from these cooperative actions and will significantly reduce component life.

Fatigue Considerations Turbine blades experience forced vibration due to perturbations in the gas stream. Most significant are integral excitations caused by wakes coming off upstream components, such as struts, injectors and nozzles. The blockages or disturbances to the steady gas stream superimpose multiple excitations per revolution or engine order (EO) excitations. These frequencies or integral order excitations are carefully avoided by tuning the airfoil s natural frequencies to avoid resonance within the operating range. In addition to forced vibration of integral sources, random vibration is experienced as the perturbations in pressure fields mix out in the gas stream. The response due to the low level, random forcing functions is damped out through the combination of mechanical damping systems and designing to robust fatigue margins. Component testing is carried out to verify natural frequencies and fatigue resistance. Solar s frequency response test facility incorporates laser holography and shaker table vibration testing to ensure durable operation (Figure GS1-4).

Figure GS1-4. Natural Mode Frequency Testing

TURBINE DISKS area is subjected to significant thermal transient conditions caused by start/stop cycles. The resulting thermally induced strains can give rise to LCF cracking. The interaction between stress rupture and LCF in this region is very complex and not well behaved. Therefore, Solar uses a conservative approach of designing for low stresses and eliminating fatigue as a concern in areas that are life limited by stress rupture. Working with materials engineers, a careful choice of disk materials is made in order to assure the proper performance in this region. A critical safety consideration is the design margin in the hub region

A critical design element in a gas turbine is the disk. Compressor disks are not significantly influenced by temperature, making their design fairly straightforward and typically very long lived (~250,000 hours). On the other hand, turbine disk design is very much affected by temperature and requires careful evaluation of stress rupture and low cycle fatigue (LCF). Typically, the entire volume of the disk must meet the stress rupture life criterion, which is generally set at ~100,000 hours. This becomes a bit challenging in the vicinity of the blade attachment slots due to the stress concentrations arising from the fir-tree configuration. This same GS-4

as relatively heavy, low stress castings and have no impact on the TBO of an engine. Corrosion and thermal fatigue cracking can and do cause distress to housings and casings on occasion, although this distress is rarely the primary cause for an engine overhaul. However, the damage does increase the complexity of the overhaul and repair activities and is, therefore, an issue of concern to the design community. Solar makes extensive use of coatings to inhibit corrosive attack, and advanced thermal modeling is being employed to minimize cracking. Advanced repair techniques are being developed and deployed to extend the useful life of these components. A recent example is with the Mars turbine nozzle case. A small portion of the forward end of the nozzle case is subjected to high temperatures and suffers oxidation damage to the extent that, once out of service, the part cannot go back into service. A repair has been developed, fully qualified, and is currently in production that removes the damaged forward portion and a new forging is electron-beam (E-B) welded to the remaining aft portion. The E-B weld is located in a low stress area. After welding, the part is machined to regain the original design intent and recoated to the same requirements as a new component (Figure GS1-6). Development and field testing have indicated the repaired part to be the equal of a new component.

of a turbine disk. The disk must be protected from overspeed conditions. The design philosophy utilized at Solar is to set section stresses such that the strongest blade will separate before the weakest disk post will fail and that the disk burst speed is higher than the blade shed speed. This assures a blade shed will occur prior to a disk burst. The hub of a turbine disk is also susceptible to LCF damage and consequent failure. LCF loading is strongly influenced by start/stop thermal transients. A detailed thermal analysis is performed to accurately predict the thermal strains and their locations. Typically, the high stress locations are in the vicinity of a center bore or through bolt holes (Figure GS1-5). Solar designs for 5000 start/stop cycles or greater than once per day for 100,000 hours. This limit is set through a combination of material properties and imposed stresses, including consideration for fatigue crack growth rates. The useful life of a turbine disk is highly dependent upon the quality of the disk material, and careful nondestructive inspections are employed during component manufacturing.

STATIC COMPONENTS Housings and casings are typically industrial style, rugged and long lived. They are generally designed

Figure GS1-6. Fully Re-machined Nozzle Support Case

Figure GS1-5. Turbine Disk Stress Distribution

GS-5

through stringent control of the gas temperature during the start cycle to eliminate any unacceptable high temperature conditions that would lead to accelerated life consumption. Solar routinely utilizes a hot restart during shop testing to expose the engine to the worst-case thermal transient prior to measuring the guarantee performance point. This assures the user that the engine has experienced the most adverse condition due to thermal transients while still meeting the guaranteed performance and that further loss of performance due to thermal transients will be minimal. Start/stop cycles do lead to LCF life consumption, which affects primarily the turbine disks. First-stage turbine nozzle trailing edges are also prone to thermal/mechanical fatigue, which presents neither a performance nor a durability liability during the standard overhaul period. This type of cracking does, however, affect component reuse and remanufacturability and is, therefore, the subject of continuing development work to enhance crack resistance through improved cooling and/or the use of thermal barrier coatings. The results of Solar s marine turbine program directly support the success of our design philosophy. The leading experience with high start/stop applications is in the Taurus 60 Marine program where our high time engine has experienced service lives of more than 9000 hours and greater than 2300 start/stop cycles, with no reported loss in performance as measured by vessel speed. This very demanding service is giving the Taurus 60M gas turbine a tough test, and the results are showing that the turbine design is meeting the challenge.

TRIBOLOGY Wear can occur wherever adjacent components experience relative motion. Clearly, an area subject to wear is the bearing. Solar uses fluid-film bearings that are proven to be durable and capable of providing long-life service, provided the fluid film remains intact. Solar strives to provide bearings and lubrication systems capable of meeting the service requirements. Seals represent another potential area subject to wear. Care during the design is taken to select the most appropriate materials and establish the most effective dimensional tolerances to minimize contact, yet provide adequate sealing. Solar conducts extensive development testing to identify optimum seal configurations and material pair combinations (Figure GS1-7).

Diagnostics

Figure GS1-7. Solar s Seal Test Facility

Designed into every Solar gas turbine package are diagnostic capabilities that help provide early warning of potential problems. Adequate lubrication is essential in achieving intended bearing lives; therefore, oil temperatures and pressures are continuously regulated and monitored to assure their proper functioning. Direct measurement of bearing pad temperatures is available in several models and this, too, provides an indication of the bearing condition. In an effort to protect the engine from serious damage due to a bearing failure, vibration monitoring devices are provided on all Solar engines and packages. These include casemounted velocity probes, proven useful on the older Saturn and Centaur 40 gas turbine models, and direct reading proximity probes on all newer engine models.

LIFE CONSUMPTION: TIME AND CYCLES Solar has taken the position during all of its programs that the gas turbine operating life is separate and independent from its cyclic life and claims no start cycle debit in operating life. The operating life and time between overhauls are determined by the design life considerations, with particular concern for wear out mechanisms that lead to performance degradation. Solar s approach to turbine design utilizes analysis and testing to account for the transient conditions associated with start/stop cycles. The allowance for start/stop cycles is designed into Solar s products, not added on. The impact of starts on life is further reduced

GS-6

LIFE ESTIMATION METHODS Solar believes that there is a better way to estimate the remaining life of a gas turbine than time between overhauls (TBO) or mean time between failures (MTBF). This is because a turbine is normally overhauled at prescribed intervals and, thus, does not operate in the wear out zone of the failure curve. Figure GS1-8 is a general failure rate-versustime curve, often called the $bathtub# curve. It applies to most devices, even to human life. There are three distinct zones. The first is the infant or start-up failures region. This is followed by a period of roughly constant failure rate, attributed to random causes. The third region, where the curve slope begins increasing, is the wear out failure area. This three-region curve can be constructed for anything that has a finite service life. Each region can be treated mathematically, such as by using Weibull analysis, to quantify behavior. For a device that is operated until it fails, such as a light bulb, the MTBF is the point where half of the original population of similar light bulbs has failed (Figure GS1-9). However, most gas turbines are overhauled at regular intervals to restore performance. While a few users do run their engines to destruction, this is seldom wise from an economic viewpoint. With modern turbines, with their cooled blades and nozzles and other expensive components, the economics almost always favor periodic overhaul rather than running until a failure occurs. Other factors here are the high costs of consequential failures and of unplanned production outages. Referring to Figure GS1-10, the user of a gas turbine obtains protection against infant failures by

virtue of factory testing. Then, by overhauling at the recommended interval, the engine is kept out of the wear out failure zone and should operate for several overhauls until the time limit of some component is approached and the engine is retired. An example would be the turbine disks as discussed above. The true risk is then that of random failures up to the next scheduled overhaul. With proper care and maintenance, the concern should be not with mean time between failures, but with the failure rate in the middle zone where virtually all operation takes place. This middle risk zone of random failures is, of course, a major focus for Solar s technical and support functions as we deploy tools such as pareto analyses and root cause-and-effect analysis to minimize failures.

Figure GS1-8. General Failure Rate-vs-Time Curve

Figure GS1-10. Risk Assessment

Figure GS1-9. Mean Time between Failures or Time between Overhauls

GS-7

ency. (Please see the paper $Increasing Turbine Life through Improved Maintenance Procedures,# TTS 104 in the appendix of this book for more on this.) Users frequently ask to see actual failure data for each engine model. To be meaningful, this information must be such that the user can rely on it for planning, budgeting and comparison of competing products. Engines are returned for many reasons other than for failures chargeable to the manufacturer. These range from elective uprates to high time (scheduled) overhauls to failures due to unpredictable events such as lightning strikes. If returns for all reasons were included, then the results would be distorted and not useful for planning. At the GTUA session on June 15, 1998, Solar showed actual data on early engine returns, expressed as an annual percent of the operating fleet of similar engines. Returns for extraneous causes, such as mentioned above, were not included. Significantly, the return rate is independent of time in service, supporting the fact that the engines do not enter the $wear-out# zone, but remain in the middle zone of the curve where $random# causes predominate. We believe that life estimation for a properly maintained gas turbine is different than for a consumable device, that rate of failure is the most meaningful concept, and that validity is achieved by including all engines that are returned for reasons chargeable to the manufacturer.

Of course, the operating environment plays a role too. Figure GS1-11 shows, in a relative way, the effects of certain variables on turbine life. If the middle line is for typical service, the lower line represents an engine in part-load operation, at low ambient temperatures, and with excellent air, fuel and water quality, along with the best level of maintenance. Engines such as these are sometimes returned for their first overhaul with more than 80,000 hours. The upper line represents full load, high ambient temperatures, poor air, fuel and water, and substandard maintenance. It is not possible to put numbers on these factors, but they certainly do affect life as well as operating effici-

Figure GS1-11. Gas Turbine Failure Rates: Environmental Effects

GS-8


     Author:



M. Kelly


     
     

             

                (Since the Taurus 70 compressor is derived from the Centaur 40 compressor with the addition of two forward stages, the 0 and 00 stages, Solar refers to a blade in the third row, or “third stage blade,” as a first-stage compressor blade.)


 Solar has development activities under way to design an injector that avoids oscillations over a broad range of pilot fuel levels. Development testing of SoLoNOx injectors is an ongoing task, and the latest improvements will be made available as they move into production. We also modified the first-stage (third-row) compressor blades to substantially improve the fatigue endurance limit. The new blades are being used on all current Taurus 70 production gas turbines and are available for replacement at overhaul or in the field.

 !       Solar’s approach to oscillation control is to (1) carefully optimize injector design so that pressure pulsation’s caused by the combustion heat release process are minimized and (2) add pilot fuel to stabilize the primary zone fuel-to-air ratio. In the Taurus 70 gas turbine, oscillations are avoided at low levels (below
2%) of pilot fuel addition and at high levels (above
8%) of pilot fuel addition. The mid-ranges of pilot fuel flow do tend to excite oscillations and are to be avoided. A few packages, through a miscommunication that has since been corrected, had the pilot fuel set up to run in the range where oscillations are promoted, which resulted in fatigue damage to the combustor liner and surrounding sheet metal structure. The typical type of liner damage experienced is shown in Figure 33. In those cases where the mid-range flows were used, the pilot fuel levels were adjusted to a non-oscillating

Figure 33. Failed Combustor Liner 43

Taurus 70-1




    

condition and the problem has not reoccurred. When operating at low pilot fuel flow levels, the gas turbine’s ability to handle large load transients can be problematic and careful tuning of the control system is required. Field operation of Solar’s SoLoNOx systems has shown that fuel quality, especially fuel-borne condensed liquids, is also a major contributor to combustor oscillations. (Refer to Engineering Specification ES 9-98 and Service Bulletin 3.5/102 provided in the Appendix of this report.) This form of contamination has been identified as a potential source of Taurus 70 gas turbine field issues. To resolve this, the affected user was requested to install coalescing filters and provide a minimum of 6C (10F) fuel superheat to remove the liquids from the gas. At another user site, improved fuel handling techniques has apparently not totally eliminated the oscillation condition, although it is not as yet known why. Consequently, a set of prototype development injectors was installed at this site to enable a field evaluation of a new injector design. These injectors are less prone to cause oscillations, but are not optimized for emissions. The injectors are operating oscillation free, giving confidence that the development work is progressing in a positive direction.

origin. Fatigue failures are random and probabilistic, particularly when considering the fact that two Taurus 70 gas turbines have accumulated in excess of 23,000 failure-free operating hours. Nevertheless, to add even greater design margin to the Taurus 70 compressor blade, modifications were made to the blade profile to increase the blade’s first fundamental bend mode and to the heat treatment of the 17-4 PH material, which provided a substantial improvement in the fatigue endurance limit. All current Taurus 70 production gas turbines use the new blades. All other Taurus 70 gas turbines will be upgraded with the new blades at their next scheduled overhaul or may be replaced in the field, which is facilitated by the horizontally split compressor case, at the appropriate service opportunity.

!

  "  Four Taurus 70 gas turbines had first-stage (third-row) compressor (Figure 34) blade failures, which resulted in significant collateral damage to the gas turbine. An analysis by Solar’s Engineering department identified a high stress condition in the blade root consistent with the fatigue crack

Taurus 70-1

Figure 34. Taurus 70 Compressor Rotor

44


     Author:



R. Morgan


 

 '              

   
      

   "

            

 
            ()'            

 $" 

bearing health care program to identify engines at risk of bearing problems. To date, customers have been contacted and more than 20% of the engines in operation, which were identified as high risk engines, have been assessed. Based on the results of the assessment, control software improvements have been incorporated and monitoring programs have been established to track bearing condition. Where appropriate, engine changeouts or repairs were conducted in advance of an engine failure. More than 30% of the more than 600 Mars engine fleet now has the latest bearing configuration. Bearing failures encountered over the past year have consisted of either bearings of the old design or problems with the postlube system after an engine shutdown. With regard to the latter, Solar would like to stress the requirement to maintain oil flow in the lubrication system for four hours after an engine shutdown. This is required to prevent the bearings from exceeding the allowable temperature range during thermal soakback. Failure to meet this requirement can result in severe damage to the No. 2 and No. 3 bearings. Solar has published four Service Bulletins (provided in the Appendix of this report) on this subject:

As reported to the GTUA for the past few years, several changes have been made to the Mars bearing system. These changes, shown in Figure 40, have resulted in a more robust bearing system with significantly improved bearing durability. (Refer also to Service Bulletin 6.0/123 provided in the Appendix of this report.) To date, the results of this program have been extremely successful. No problems have been encountered as a result of the design modifications, and there have been no new bearing failures related to increased bearing clearance due to corrosion. In the last year, the Mars engine fleet accumulated a significant number of operating hours with the new bearing system. As discussed in last year’s presentation, Solar proactively initiated a







SB5.9/103 SB6.5/107 SB6.5/108 SB6.5/109

These Service Bulletins define the postlube requirements and configuration and control enhancements that will significantly improve the robustness of the postlube system. We encourage you to review them in detail and contact your Solar representative to discuss implementation of these enhancements where appropriate.

Figure 40. Improvements to the No. 2 and No. 3 Bearing Areas 49

Mars 3

 Authors:


     R. Steele, D. Rawlins and R. Morgan


 

 *           

    #  &+


%

The Mars effusion-cooled combustor liner (Figure 41) has successfully progressed through rigorous in-house development tests and more than 20,000 hours of field evaluation. It was released into production as the standard combustor liner for new Mars 100S gas turbines in May 1999. The same fuel injector configuration is used with the effusion-cooled liner as with the original louvercooled combustor liner. Solar utilizes the term “rumble” to characterize low frequency pressure fluctuations (20 to 60 Hz) within the combustor that are associated with the SoLoNOx system operating too closely to the lean extinction limit, the point where the flame is extinguished within the combustion system. Solar’s experience has shown that the potential for a SoLoNOx gas turbine to enter into a “rumble” mode of operation is usually caused by either insufficient

The new effusion-cooled liner is slightly more susceptible to combustor rumble at part-load/low ambient operating conditions than the original louver-cooled combustor liner due to leaner operation of the combustor primary zone. This issue has been successfully overcome and demonstrated on gas turbines operating over a wide range of ambient conditions by increasing the part-load pilot fuel flow. Solar is developing a continuously variable pilot fuel control system, which will allow the emissions to be optimized throughout the gas turbine load range, while providing adequate margin against combustor rumble. Solar expects to have this variable pilot system available later this year. With proper gas turbine setup and clean fuel, rumble has not been an issue for SoLoNOx gas turbines.

 ! Solar continues to develop advanced combustor liner cooling concepts to reduce the amount of cooling air required to maintain acceptable liner metal wall temperatures. This reduction in the level of required cooling air provides three major benefits: 1. It allows for additional air to be used in dilution trimming of the hot gases entering the turbine hot section for improved durability. 2. It allows leaner operation of the combustor primary zone for lower NOx emissions. 3. It reduces thermal quenching of the combustion reactions along the liner walls, resulting in lower CO emissions.

Mars 4

Figure 41. Effusion-Cooled Combustor Liner

50


    

 Currently, Mars gas turbine packages use a fixed continuous pilot arrangement (pilot No. 2) with fixed No. 1 and No. 3 pilots for start-up and transient conditions. A variable continuous pilot arrangement with a range of 1-to-10% pilot fuel, which combines the No. 2 and No. 3 pilot functions, is being developed. This is similar to the current SoLoNOx pilot system used on the Centaur gas turbine. A wide range pilot system that consolidates all gas fuel pilot functions into one valve is also being developed. Sustained operation in a “rumble” or “combustor oscillation” mode can significantly compromise reaching the full durability potential of the SoLoNOx system and should be avoided. With proper set-up and maintenance, the SoLoNOx system has demonstrated the ability to meet and exceed the product durability targets.

pilot fuel, low flame temperature caused by incorrect parameters in the gas turbine control logic, or blockage of the gas distribution spokes within the fuel injector caused from fuel that does not meet the cleanliness requirements in Solar’s Engineering Specification 9-98 (provided in the Appendix of this report). A different potential form of acoustic pressure fluctuations within a SoLoNOx combustion system is referred to as “combustion-induced pressure oscillations.” These oscillations are at a higher frequency (200 to 500 Hz) than “rumble” and are the result of an aerothermal/acoustic coupling between the fuel injector and the combustor liner volume. Solar controls these oscillations through careful design of the fuel injector geometry or through use of pilot fuel to stabilize the flame. The effusion-cooled combustor liner volume is similar to the original louvered design and, thus, has no significant effect on combustor oscillations.

51

Mars 4

Solar Turbines Incorporated

Author:

GTUA’99

D. Bergen

Mars Question Number 6 Explain experience and any issues around electro-hydraulic starts and sprag clutch. attributed to quality and/or process problems at the clutch supplier. Solar replaced the sprag clutch supplier in January 1998. The sprag clutch assembly from the new supplier does not experience the “roll over” failures experienced with the sprag clutch assembly from the previous supplier. The new assembly has a higher torque capacity, however, and is prone to overrun the starter after starter dropout, which causes clutch bearing wear problems not seen with the original clutch. The clutch continues to rotate, even though it is disengaged, due to the viscous drag between the rotating and stationary components. This condition is visually observable and is usually associated with direct ac start systems. Pneumatic starters may overrun, but this is not considered a problem since the starter is continuously lubricated and rated for higher speeds. The ac hydraulic starter will not overrun due to hydraulic lock-up designed into the system. To deal with the vibration issue, a new clutch configuration (Figure 43) was designed that provides acceptable performance and is an improvement over the previous configuration in several ways. (Refer to Service Bulletin 2.0/102 provided in the Appendix of this report.) The sprag lift-off speeds have been reduced from the 7500-to9500 rpm range to the 4000-to-6200 rpm range. The sprag clutch assemblies are now 100% tested and inspected prior to use, which reduces the possibility of the clutch not completely disengaging above starter dropout speeds. Also, a 100-lb spring preload has been incorporated into the clutch bearing assembly to ensure proper loading and location of the ball bearings in the raceway of the angular contact bearings to reduce the risk of bearing wear. This configuration does experience some minor bearing wear, but the wear does not pose a significant life problem. Solar is continuing to

ANSWER Since the introduction of the Mars gas turbine in 1977, Solar has had good experience overall with the sprag clutch system used with all Mars start systems. In the fall of 1997, however, some of these systems began experiencing problems with the sprag clutch. The problems primarily centered on improper operation of the sprag clutch itself, not allowing proper disengagement of the starter from the gas producer above starter dropout speeds. A successful reconfiguration that gives acceptable performance results was introduced and is available for field replacement. Solar also embarked on a product improvement program working together with several qualified clutch suppliers and anticipates production implementation of an even more durable clutch system in early 2000.

BACKGROUND Solar currently uses one sprag-type clutch configuration for all Mars start systems, including ac hydraulic, direct ac, and pneumatic configurations. The purpose of the sprag clutch is to lock the starter to the turbine during starting and to fully and auto-matically disengage the starter from the turbine after accelerating the turbine beyond starter dropout speed. In late 1997, Solar became aware of quality issues relating to the sprag clutch system used on the Mars gas turbine. These problems generally surfaced during production test and commissioning, where the sprag clutches would move past center (“roll-over”) and permanently lock the starter to the gas producer, causing the starter to remain engaged up to full gas producer speed. The primary cause of the failures was isolated to the sprag assembly. Although the defect in the sprag assembly was never fully isolated, it has been

55

Mars 6

GTUA’99

Solar Turbines Incorporated

evaluate this configuration and to work with the new supplier on quality and process issues to develop a more durable sprag clutch system early in the year 2000.

Figure 43. Improved Sprag Clutch Assembly

Mars 6

56

Solar Turbines Incorporated

GTUA2000

Author: T. Batakis

Mars Question Number 1 Provide details of developments to overcome dual fuel nozzle plugging. the gas fuel passages during liquid fuel operation, thus preventing the recirculating airflow from occurring. This purge system draws high-pressure air from the combustor case, through two special hightemperature-rated ball valves in series, and into a special port on the gas fuel manifold, using 1.0-in. diameter tubing. The airflow rate is controlled by a metering orifice and is designed to safely overcome the pressure variations within the combustor using a minimal purge flow rate. The two ball valves provide a safety check against leakage from the gas manifold to the engine case. The space between the two valves is vented to atmosphere through a small orifice and the pressure in the space is monitored. This allows the valves to be cycled individually and the pressure response to be interpreted to assure that the valves are functioning properly. This pressure signal is also used to detect a valve leak during gas fuel operation. Retrofit kits have been designed and implemented in many of the Mars dual fuel engines. The early kits take the purge air from a special ring installed at the engine bleed valve connection. Later kits will use the production configuration, which takes the purge air from a combustor case borescope port. A sophisticated software program is required to operate the purge system. This includes system monitoring, to assure proper function, and safety logic, to prevent engine damage in the event of a system failure. A thorough failure mode and effects analysis (FMEA) was conducted to identify all possible failure scenarios and determine the best control response for each case. Our experience to date indicates that the gas manifold purge system works as intended to eliminate the issue of gas fuel passage fouling due to liquid fuel migration.

ANSWER The Mars dual fuel conventional (non-SoLoNOx) combustion engine has experienced several recent and somewhat related fuel system issues of varying severity. These have all been resolved with hardware and software modifications to the engine and its control system. All of the modifications are retrofittable and are being implemented in field, overhaul, and production engines.

BACKGROUND The three issues involved with Mars dual fuel conventional combustion engines are: 1. Gas fuel passage fouling 2. Fuel injector fouling and erosion 3. Ignition failure on liquid starts These issues will be addressed in Service Bulletin 3.3/106, the latest version of which is provided in the Appendix to this report.

Gas Fuel Passage Fouling Gas fuel passage fouling is due to “liquid fuel migration.” This refers to the propensity for liquid fuel to enter the gas fuel passages of the fuel injector, during liquid fuel operation, where it solidifies to obstruct the gas fuel flow during subsequent gas fuel operation. Liquid fuel is carried into the gas fuel injector passages, from the tip of the injector, by a small recirculating airflow in the gas fuel delivery system, which is generated by small pressure differentials within the combustor. The solution to this problem is the incorporation of a gas manifold purge system (Figure 20) that uses high-pressure engine air to continuously purge

25

Mars 1

GTUA2000

Solar Turbines Incorporated

Figure 20. Gas Manifold Purge System promotes hot corrosion of the fuel injector face shroud. Reports from the problem engine sites show that the damaged injectors were in the lower engine positions, while the upper injectors were undamaged. The effectiveness of the liquid fuel purge depends on the duration of the purge timer and the engine condition when the liquid fuel supply is terminated. Upon shutdown from full load on liquid fuel, the purge starts with full engine pressure, which decays as the engine decelerates. Upon shutdown from idle, the purge starts with lower engine pressure and decays as the engine decelerates. After a fuel transfer from liquid fuel to gas fuel, the purge has full engine pressure available for the duration of the purge. After a failed start on liquid, the purge has only engine crank speed pressure for purging.

Fuel Injector Fouling and Erosion Several users of Mars dual fuel conventional combustion engines reported severe fuel injector fouling of the swirler air passages and erosion of the face shroud, after operating on liquid fuel. In some cases, the cause of this problem was found to be inadequate purging of the liquid fuel manifold (Figure 21) after liquid fuel operation. Liquid fuel is purged from the fuel injectors, supply manifold, and connecting tubes whenever the liquid fuel is turned off. The purge system uses high-pressure engine air to force residual fuel back through the manifold inlet port and then into a drain. A control timer limits the purge duration. Fuel that is not purged from the fuel system will settle in the bottom of the manifold and flow into the combustor case through the lower injectors. This fuel cokes up the hot fuel injector heads and

Mars 1

26

Solar Turbines Incorporated

GTUA2000

Water condensation in the air-assist manifold occurs when hot pressurized engine air, which is driven by small pressure differentials within the combustor, recirculates through the cool air manifold. This air is quenched on the manifold wall, precipitating into moisture that then collects in the bottom of the manifold. Engine sites with high ambient humidity are more likely to encounter this problem than other sites. Field experiments indicate that activating the engine air-assist during the pre-start engine crank can clear the water in the torch. This purges the water from the torch air passages prior to the first ignition attempt. Work is continuing to verify the effectiveness of this change under all operating conditions and to modify the control logic accordingly.

Figure 21. Liquid Fuel Manifold

Field tests have revealed that the standard Mars purge timer may have been set for a duration that was too short to adequately purge the liquid fuel system under all operating conditions. Recent test results suggest a purge time of 90 seconds is adequate for normal engine operating conditions. Implementation of this purge timer setting is credited with the elimination of the fuel injector fouling and erosion described above. Work is continuing to define the optimal purge duration for each engine operating condition. It is also important to keep the drains clear and to avoid any backpressure in the system.

Ignition Failure on Liquid Starts Some Mars dual fuel conventional combustion system engines have experienced ignition failures due to water condensation in the air-assist manifold. This water collects in the manifold and flows into the torch ignitor (Figure 22) through the torch air-assist port and hampers torch ignition on liquid fuel due to degraded fuel atomization. Typically, the second start attempt is successful, since the water is purged from the system during the first start attempt. Thus, this is more of a nuisance than a critical issue.

Figure 22. Dual Fuel Torch Ignitor

27

Mars 1

Solar Turbines Incorporated

Author:

GTUA2000

R. Morgan

Mars Question Number 3 Provide general update on bearing modifications and recent experience. The Mars engine fleet has continued to accumulate operating hours with the new bearing system since the system’s incorporation in 1997. All production, overhaul or retrofit engines have used the new bearing system. At this time, more than 50% of the nearly 700 Mars engine fleet has the latest bearing configuration. Bearing failures have declined even further since last year’s report to the GTUA. Similar to the experience upon which we reported last year, all of the failures in the past year consisted of either bearings of the old design or bearings that were damaged due to an interruption of the post-lube system after an engine shutdown. With regard to the latter, Solar would like to stress the requirement to maintain oil flow in the lubrication system for four hours after an

ANSWER As reported to the GTUA for the past few years, several modifications have been made to the Mars bearing system. These improvements have resulted in a more robust bearing system with significantly improved bearing durability.

BACKGROUND As presented to the GTUA last year, modifications to the Mars bearing system (Figure 23) have been extremely successful. No problems have been reported as a result of the design modifications, and there have been no reported bearing failures related to increased bearing clearance due to corrosion. This year, we can report that this success has continued.

Figure 23. Improvements to the No. 2 and No. 3 Bearing Areas 31

Mars 3

GTUA2000

Solar Turbines Incorporated


SB6.5/108

engine shutdown. This is required to prevent the bearings from exceeding the allowable temperature range during thermal soakback. Failure to meet this requirement can result in severe damage to the No. 2 and No. 3 bearings. Solar has published four Service Bulletins (provided in the Appendix to this report) on this subject:


SB6.5/109

These bulletins define the post-lube requirements and configuration and control enhancements that significantly improve the reliability of the postlube system. We encourage you to review them in detail and contact your Solar Field Service Representative to discuss implementation of these enhancements where appropriate.


SB5.9/103
SB6.5/107

Mars 3

32

Solar Turbines Incorporated

Author:

GTUA2000

T. Batakis

Mars Question Number 4 Provide update on problems associated with effusion cooled injectors.

ANSWER

Problem Description

In late 1998, a generic durability problem with the Mars 100 conventional (non-SoLoNOx) combustion engine was identified. An intensive effort was launched to investigate the issue and provide a solution, which resulted in a modified fuel injector design. The modified fuel injectors can be retrofitted in fielded engines with minimal impact on customer operations. Production and overhaul engines have incorporated the modified injector design since mid1999. In addition, a modified combustor liner design is being developed to enhance liner durability, but is not required to achieve the combustion system design life target with the modified fuel injectors. No performance penalties are incurred with either the fuel injector or liner design modifications.

With the 198834 fuel injector (Figure 24), the Mars 100 conventional combustion system performed exceptionally well, except the combustor liner life was limited by thermal degradation of the primary zone outer wall and did not meet the 30,000-hour design objective. The durability problem originated with an excessive local heat flux to the liner, at the point where the fuel injector swirl-cone impinged on the outer wall. This high heat flux produced high liner temperatures and high thermal stresses in the wall-cooling louver at this location (Figure 25). The cooling louver gradually distorted until it touched the outer wall and closed the film-cooling gap. Deprived of film cooling air, the liner downstream of the closed cooling strip overheated and burned

BACKGROUND The two major components of the combustion system are the combustor liner and the fuel injector. These two components function together to mix and burn the fuel and air and deliver hot gas to the turbine with a prescribed temperature profile. Proper distribution of fuel and air within the liner is critical in achieving the performance objectives of the combustion system. These objectives include controlled emissions limits, high combustion efficiency, adequate flame stability, and limited liner metal temperatures to satisfy the system life requirements. In late 1996, the Mars 100 conventional combustion fuel injector was changed from P/N 173470 (gas fuel) and P/N 198337 (dual fuel) to P/N 198834. This change was made to incorporate an effusion-cooled face shroud on the injector tip, reducing tip metal temperatures and eliminating premature thermal erosion of the injector tip.

Figure 24. Previous Fuel Injector

33

Mars 4

GTUA2000

Solar Turbines Incorporated

Figure 25. Liner Durability Problem

through. Additional overheating occurred just upstream of the damaged film-cooling strip due to the same high heat flux, eventually causing burnthrough in this location as well. Such damage typically occurred in up to 21 liner locations corresponding with the location of each of the 21 fuel injectors. Rig and engine tests of this combustion system revealed excessively high local metal temperatures in the outer liner at the same location where damage was observed in the field. Thermal/stress analyses of the outer liner under the measured operating conditions verified the observed mechanical behavior of the liner and supported the operating problem described above. Consequently, fuel injector modifications were developed to reduce the peak local heat flux to the outer wall.

Mars 4

Problem Solution The fuel injector modifications reduce the cone angle of the fuel injector air swirler to move the impingement point of the fuel/air mixture further downstream on the outer liner wall. This dilutes the fuel/air mixture and reduces the heat flux at the wall impingement location. The P/N 301380 modified fuel injector (Figure 26) alone provides an adequate solution to the liner durability problem. That is, liner design life is achieved with the modified injector without requiring a liner change. The modified fuel injectors can be retrofitted onsite and will ensure acceptable combustor liner life, even for liners that may have previously suffered minor thermal degradation arising from operation with the P/N 198834 fuel injectors.

34

Solar Turbines Incorporated

GTUA2000

liner damage in fielded engines to assist in determining whether or not the liner should be replaced when the modified fuel injectors are installed. A liner with limited damage can be safely operated until the next scheduled overhaul, provided the modified fuel injectors are installed to arrest the durability problem.

Additional Enhancements To further enhance performance of the combustion system, modifications to the combustor liner were investigated. The liner modifications consist of shortening the film cooling panels to increase the overall film cooling effectiveness in the primary zone, shortening the cooling strip overhang to increase its stiffness, and redistributing the cooling air to provide more air to the high heat flux area. The combustor liner design change currently in process is intended to offer an additional improvement in liner durability, but again is not required to achieve the system design life with the modified fuel injectors. Modifications to the combustor liner will be incorporated in production and overhaul engines upon completion of development and design qualification testing.

Figure 26. Modified Fuel Injector Engine and rig qualification tests were conducted to validate the modified fuel injector design. This design has been incorporated in production and overhaul engine configurations and is available for field retrofit. Rig tests were also conducted to determine the level of combustor liner damage that can be tolerated with the modified fuel injectors. From this testing, criteria have been established to assess

35

Mars 4

Solar Turbines Incorporated

Author:

GTUA2000

D. Baker

Mars Question Number 5 Provide an update on current experience and development of sprag clutch. rather than through the high stress cam surfaces of the sprag design. In addition, the new design will not cause the starter to rotate after starter drop-out. When the turbine speed exceeds the starter speed on acceleration, the spline assembly automatically and completely disengages the turbine from the starter motor. A comparison of the current and replacement clutch systems is shown in Figure 27. Solar anticipates releasing this new clutch system into production, and to the field for retrofit purposes, in the third quarter of this year. The replacement clutch system will be field retrofittable for current Mars configurations. As indicated in our response last year, overrunning of the previously furnished pneumatic starter designed by Solar is not considered a problem, since the starter is oil lubricated and rated for the higher speeds.

ANSWER As part of the continuing effort to improve product reliability and durability, Solar has assessed several start clutch options and has begun qualifying a new start clutch assembly. The qualification should be completed by the third quarter of this year.

BACKGROUND Solar updated the GTUA last year on our progress with sprag clutches. (Please refer to GTUA’99 "Mars Question Number 6" provided in the Appendix to this report.) In the year since, Solar has evaluated a number of start clutches and has selected a new start clutch assembly that incorporates a spline clutch system. Changing to a spline clutch is expected to significantly improve the reliability of the Mars start clutch system. Starting torque is transmitted through low-stressed splines

37

Mars 5

GTUA2000

Solar Turbines Incorporated

Figure 27. Comparison of Current Sprag Clutch Assembly and New Spline Clutch Assembly

Mars 5

38

Developments in SoLoNOx Low Emissions Systems

Contents Page

INTRODUCTION

1

LEAN-PREMIXED COMBUSTION

1

SOLONOX DEVELOPMENT

3

MAINTAINING PRODUCT STABILITY

8

ADVANCED COMBUSTOR TECHNOLOGIES

10

SUMMARY

14

BIBLIOGRAPHY

15

Cat and Caterpillar are trademarks of Caterpillar Inc. Solar, Centaur , Taurus, Mars, Titan, and SoLoNOx are trademarks of Solar Turbines Incorporated. Specifications subject to change without notice. Printed in U.S.A. Copyright © 2000 by Solar Turbines Incorporated. All rights reserved. TPSoLoNOx/200

Developments in SoLoNOx Low Emissions Systems K.O. Smith, Ph.D. D.C. Rawlins, Ph.D. Combustion Engineering

INTRODUCTION

LEAN-PREMIXED COMBUSTION

In 1992, Solar introduced the first industrial gas turbines employing a lean-premixed combustion system for emissions control. Since then, Solar has placed more than 680 SoLoNOx™ gas turbines into service. These turbines are routinely meeting emissions limits as strict as 25 ppmv NOx and 50 ppmv CO (15% O2) on natural gas. Other gas turbine manufacturers have followed suit, and, at this time, nearly every manufacturer has introduced a low emissions gas turbine product line based on lean-premixed combustion. Despite the significant improvement in gas turbine emissions over the last eight years, regulatory agencies continue to consider and implement more stringent emissions regulations. For example, NOx control levels for gas turbines have been set as low as 2.5 ppmv in areas within California. Levels this low require the use of expensive exhaust gas cleanup systems in addition to advanced low NOx combustion technology. CO levels as low as 10 ppmv may be required by future emissions regulations. The primary purpose of this paper is to provide a broad overview of Solar’s low emissions combustor development and how it is being shaped by emissions regulations that are continually changing. Discussed in this paper is a description of the development and present status of SoLoNOx; a discussion of how increasingly restrictive emissions regulations impact industrial gas turbine production; and a review of new combustion technologies with the potential to achieve lower emissions levels. Solar continues to explore combustion technologies in the belief that clean combustion is a more cost-effective path to low emissions than exhaust gas cleanup.

SoLoNOx employs lean-premixed combustion to reduce NOx emissions. Lean-premixed combustion reduces the conversion of atmospheric nitrogen to NOx by reducing the combustor flame temperature. Since NOx formation rates are strongly dependent on flame temperature, lowering flame temperature (by lean operation) is an extremely effective strategy for reducing NOx emissions (Figure 1). Lean combustion is enhanced by premixing the fuel and combustor airflows upstream of the combustor primary zone. This premixing prevents stoichiometric burning locally within the flame, thus ensuring the entire flame is at a fuel lean condition. There are three aspects of lean-premixed combustion that warrant attention: • CO/NOx tradeoff • Combustor operating range • Combustor pressure oscillations

CO/NOx Tradeoff Since the flame temperature of a lean-premixed combustor is designed to be near the lean flammability limit, lean-premixed combustor performance is characterized by a CO/NOx tradeoff (Figure 2). At the combustor design point, both CO and NOx are below target levels; however, deviations from the design point flame temperature cause emissions to increase. A reduction in temperature tends to increase CO emissions due to incomplete combustion; an increase in temperature will increase NOx. This tradeoff must be addressed during part-load turbine operation when the combustor is required to run at an even leaner condition. The tradeoff also comes into play in devel-

1

AIR INLET

3700˚F

NOx EMISSIONS

Conventional

2000˚F

SWIRLER FUEL

NOx

Notes: (1) Conventional Combustors Have High Flame Temperatures

FLAME TEMPERATURE (3)

(2) SoLoNOx Combustors Operate with Lower Flame Temperatures and Lower NOx Emissions (3) NOx Emissions Increase Rapidly with Flame Temperature FLAME TEMPERATURE

Lean Premixed

Conventional (1)

PREMIXING ZONE

AIR INLET

2800˚F

2000˚F

Lean Premixed

SWIRLER PILOT FUEL

(2)

LEAN

MAIN FUEL

RICH

FUEL/AIR RATIO

981484-005M

Figure 1. How Lean-Premixed Combustion Reduces NOx Emissions

opment efforts to reduce lean-premixed combustor NOx emissions by further reducing the primary zone design point temperature.

emissions limits can be satisfied. As a gas turbine moves away from full-load operation, a lean-premixed combustor will eventually produce excessive CO emissions. To broaden the operating range, low emissions gas turbines can use variable geometry to maintain the combustor primary zone at its optimum low emissions point despite load changes. Variable geometry involves combustor airflow control within the gas turbine to maintain a nearly constant flame temperature. The current generation of low emissions gas turbines uses compressor air bleed at part-load to broaden the operating range of the lean-premixed combustion system. Although effective, compressor bleed results in a reduction in part-load efficiency because high pressure air is vented to the atmosphere upstream of the gas generator. Some applications such as single-shaft gas turbines can use the inlet guide vanes (IGV) to perform the variable geometry function without an efficiency impact; however, the IGV technique is not applicable to two-shaft gas turbines.

Combustor Operating Range

Combustor Pressure Oscillations

In a gas turbine, the lean-premixed CO/NOx tradeoff is manifested as a limited load range over which

The introduction of lean-premixed combustion systems for gas turbines has raised manufacturer aware-

CO AND NOx EMISSIONS

CO

Low Emissions Operating Range

NOx

PRIMARY ZONE FUEL / AIR RATIO 082-002M

Figure 2. Typical Lean-Premixed Combustor Emissions

2

• Exchangeability – SoLoNOx engines to be

ness of the consequences of large combustor pressure oscillations. Simply put, lean flames have a greater tendency to cause pressure oscillations that can lead to engine damage. It is recognized that the reduced stability of a lean-premixed flame contributes to combustor oscillations. Despite increased awareness, however, manufacturers are still working to develop design methodologies and combustion system features that prevent excessive combustor pressure oscillations.

compatible with conventional packages with only minor package modifications.

Combustion System Development of the SoLoNOx combustion system required modifications to the following gas turbine components:

• • • • • •

The three lean-premixed combustion system characteristics previously identified represent significant constraints in efforts to develop advanced combustion systems that will further reduce gas turbine NOx and CO emissions.

Combustor liner Fuel injectors Variable geometry systems Engine casings Control system Fuel system

Combustor Liner

SOLONOX DEVELOPMENT

The lean-premixed combustor liner is generally similar to a conventional liner in terms of geometry, materials and construction (Figure 3). The most significant difference in the lean-premixed liner is an increase in combustor volume. The larger volume is required to ensure complete combustion and low CO and UHC emissions at the lower overall flame temperature of the lean-premixed combustor (Figure 4). Since combustor length, was constrained by the engine exchangeability objective, the increased combustor volume was achieved by increasing the outer liner diameter. The larger liner required an increase in the diameter of the combustor housing (Figure 5).

In 1987, Solar began a major development effort to integrate dry, low NOx combustion technology into its product lines. Several potential low NOx combustion techniques were evaluated and lean-premixed combustion was selected as the most promising approach for near-term application. Advantages of lean-premixed combustion include the concept’s proven potential for low NOx emissions, general similarity of combustion system hardware to that used in conventional gas turbines, and Solar’s extensive lean-premixed technology base developed through earlier research work. The goals and objectives established for the SoLoNOx development program were: • Emissions (ppmv @15% O2) – Natural Gas: NOx < 42 (introduction level) < 25 (final level) CO < 50 UHC < 25 – No. 2 Diesel NOx < 96 (introduction level - gas start only) < 60 (final level) CO < 50 UHC < 25 • Low Emissions Operating Range – Continuous compliance over the 50-to-100% load range of the engine with ambient temperatures above -20°C (0°F). • Performance – Unchanged design point output power and heat rate compared to a conventional unit. • RAMD – Unchanged reliability, availability, maintainability and durability levels compared to the conventional unit.

082-055M/S

Figure 3. Lean-Premixed Annular Combustor Inlet Section

3

been developed to give improved CO compliance at ambient temperatures below -20°C (0°F). The current production SoLoNOx combustors use louvers on the inside of the liner to direct air axially along the walls to produce a protective film of cooling air between the wall and the hot combustion gases (Figure 6). This method of liner cooling is commonly used in industrial and aircraft gas turbine combustors. The cooling air film gradually mixes with the hot gas stream; thus, a succession of louvers must be placed along the liner to maintain the required temperatures. This method of wall cooling uses relatively high levels of cooling air because the wall just downstream of the louver must be overcooled in order to keep the wall adjacent to the next louver below the maximum temperature limit. Effusion cooling of the combustor walls has been developed for the SoLoNOx combustor liners in order to reduce the cooling air required and, in turn, reduce CO emissions. The injection of cooling air along the combustor wall can quench the combustion reactions in the wall region and, thus, contributing to CO and UHC emissions. The basic geometry of the effusion-cooled liner is the same as the louvered version. Effusion cooling is obtained by starting a film of air with a cooling louver at the front of the combustor and then continuously feeding this film with additional air through a multitude of small diameter holes laser drilled at an angle of 20 degrees to the wall surface (Figure 7). An effusion liner has the total cooling air reduced by 20% relative to the louvered liner. The thermal gradients in an effusion liner are significantly less than in

HE-0129

Figure 4. Comparison of Conventional and SoLoNOx Combustor Liners

CONVENTIONAL

SOLONOX

082-054M/S

COMBUSTOR WALL

CONVECTOR

Figure 5. Comparison of Conventional and SoLoNOx Combustion Systems (Cross Sections)

A second difference in the lean-premixed liner is the absence of large air injection ports in the combustor primary zone. All air used in the combustion process is introduced through the air swirlers of the fuel injectors. The remaining compressor delivery air is used for cooling the walls or for dilution to achieve the specified radial temperature profile and pattern factors at the combustor exit. Early SoLoNOx combustor liners incorporate conventional air film louver wall cooling techniques. More recently, an improved effusion-cooled liner design has

HOT GAS COOLING AIR

SPLASH PLATES (louvers) 120-002M

Figure 6. Louver Cooling Design

4

COMBUSTOR WALL

EFFUSION HOLES

CONVECTOR

HOT GAS

COOLING AIR FILM STARTING SLOT

120-003M

Figure 7. Effusion Cooling Design

082-060M/S

Figure 9. Comparison of SoLoNOx and Conventional Fuel Injectors

the louvered liner while still maintaining acceptable wall temperatures. Additional cooling effectiveness is achieved by adding an impingement shield to the SoLoNOx combustor liner and combining air impingement on the back side of the combustor wall with effusion through the wall (Figure 8).

fuel tubes injects natural gas fuel into the air just downstream of the air swirler. Uniform mixing of the fuel and air occurs within the annular premixing chamber prior to reaching the combustor primary zone. The strong swirl stabilizes the combustion process in the primary zone by establishing a recirculation zone that draws reacted hot gases back upstream, thus providing a continuous ignition source. Above 50% engine load, the majority of the fuel (approximately 90 to 100%) is introduced through the main fuel tubes.

Fuel Injectors SoLoNOx fuel injectors (Figure 9) are significantly larger than their conventional counterparts due to the higher airflow through the injector air swirlers and the required volume of the premixing chamber used to mix the fuel and air. The injector module includes a premixing main fuel injector, a pilot fuel injector, and in some cases a variable geometry system for partload control purposes. Main Fuel Circuit. The premixing main fuel injector uses an axial swirler to impart a high degree of swirl to the primary zone air. A series of multi-orificed, radialCOMBUSTOR WALL

IMPINGEMENT SHIELD

Pilot Fuel Circuit. The pilot fuel injector circuit is used mainly for lightoff and low load operation. The pilot fuel injector consists of an air swirler and tangential fuel inlet ports to provide partial premixing of air and fuel prior to combustion. During lightoff and low load operation, approximately 30 to 50% of the fuel passes through the pilot injector, providing a rich fuel/ air mixture. Combustor stability is enhanced in this mode compared to lean-premixed operation, although NOx and CO emissions are higher. Above 50% engine load, the pilot fuel is reduced to less than 10% of the total fuel flow to optimize emissions performance. The pilot fuel is also momentarily increased during off-load transients to help stabilize the flame during the transient.

EFFUSION HOLES

Variable Geometry Systems Several variable geometry systems have been employed to avoid lean extinction and broaden the low emissions operating range of the lean-premixed SoLoNOx combustion system. Different variable geometry design approaches were used initially in SoLoNOx systems for the Taurus™ 70, Mars® and

HOT GAS COOLING AIR

FILM STARTING SLOT

082-059M

Figure 8. Impingement/Effusion Cooling Design

5

Titan™ gas turbines than were used for the Centaur® and Taurus 60 gas turbines. Each technique, however, ultimately provided control of the primary zone airflow to maintain the primary zone fuel/air ratio near its optimum low emissions level during part-load engine operation. Casing Bleed. Two-shaft Centaur 40S, Centaur 50S, and Taurus 60S gas turbines used for gas compression and mechanical drives, bleed air from the combustor casing at part load. This method of variable geometry has proved effective in controlling the CO emissions while using the production bleed valve of conventional engines. A consequence of air bleed, however, is a deterioration in engine part-load thermal efficiency since compressed bleed air no longer enters the turbine section of the engine to produce power. Inlet Guide Vanes. Single-shaft Centaur 40S, Centaur 50S, and Taurus 60S gas turbines used for power generation, maintain optimum primary zone fuel/air ratios by modulating the compressor inlet guide vanes (IGV). Closing the IGVs reduces the airflow through the engine compressor and combustor. No bleeding of high pressure air is required. Swirler Inlet Valve. In addition to casing bleed, Centaur 40S, Centaur 50S, and Taurus 60S gas turbine fuel injectors have a two-position swirler inlet valve (SIV) located upstream of the main air swirler, which is used to control the airflow into the combustor primary zone. This valve is pneumatically actuated from outside the combustor casing. In the open position, full airflow passes through the swirler. In the closed position, the slotted SIV reduces the primary zone airflow. By closing the SIV, the primary zone fuel/air ratio is changed in a step-wise fashion. Additional low emissions combustor operating range is obtained without any heat rate penalty. Injector Bleed. In an effort to improve part-load heat rate, the initial fuel injectors for the Taurus 70 and Mars gas turbines incorporated a different type of variable geometry system. A bleed port upstream of the main air swirler of each injector was used to bleed compressor discharge air slectively from the injectors. The 14 fuel injector bleed ports were connected to a common manifold and a single butterfly valve was used to control the bleed flow. Bleeding primarily from the fuel injectors reduced the total amount of bleed air and, thus, minimized the effects on heat rate. Due to system cost and durability issues associated with the air ducting components, injector bleed has now been replaced with a casing bleed configuration on these engines.

Engine Casings New combustor casings are required for the SoLoNOx system due to the increased diameter of the combustor liner and larger fuel injectors. This larger combustor case also requires modification to the mating compressor diffuser and gas producer turbine cases. The overall length of the engine remains unchanged.

Control System The SoLoNOx gas turbine control system is identical to the conventional gas turbine system at start-up and low load operation, but differs when the gas turbine operates in the low emissions mode (above approximately 30 to 50% of rated load). The control system for SoLoNOx engines modulates the variable geometry systems to keep the combustion primary zone temperature within a specified range. Accurate control of the primary zone temperature is critical to controlling NOx and CO emissions; however, direct measurement of this temperature, which is greater than 1540°C (2800°F), over an extended period of time is impractical. Standard gas turbines use the power turbine inlet temperature (T5) as an indirect measurement of the combustor exit or turbine inlet temperature. The initial release of the SoLoNOx gas turbine also used T5 for control. To control the SoLoNOx engine primary zone temperature (Tpz) , the combustion zone temperature is derived from a thermodynamic heat balance across the combustion system. The parameters used in this calculation are the compressor discharge temperature, the power turbine inlet temperature, the flow split between the combustor primary zone air and the total combustor airflow, and the ratio of the power turbine inlet temperature to the first-stage turbine inlet temperature (T3).

Fuel System The natural gas fuel system for SoLoNOx gas turbines includes two separate fuel circuits: one for the pilot system and one for the main. Separate fuel manifolds are used to supply pilot and main gas to the respective fuel circuits of each fuel injector. The pilot and main throttle valves are both controlled with a single fuel actuator. During start-up and low load operation, both fuel circuits are active. When the engine is in the low emissions mode, a pilot fuel shutoff valve closes. A fixed percentage of the total fuel continues to flow through the pilot circuit via an orifice in parallel with the pilot shutoff valve. This fixed pilot flow is used to stabilize the flame.

6

Initial Field Test Engines

designs are now being incorporated into production machines and have allowed the NOx guarantee level to be reduced to 25 ppmv.

The first prototype production SoLoNOx gas turbines used in gas transmission service were installed at customer field evaluation sites in 1992. A Centaur 50S gas turbine, rated at 4100 kW (5500 hp), was installed at the El Paso Natural Gas Company (EPNG) Window Rock Station near Window Rock, Arizona (Figure 10). In mid-1992, a Mars 100S gas turbine, rated at 10 500 kW (14,000 hp), was installed at the Pacific Gas Transmission (PGT) station near Rosalia, Washington.

Dual Fuel Capability The design of the prototype dual fuel injectors installed in three Centaur 50S generator packages in Germany at the end of 1994 is shown in Figure 11. The design concept is based on an air-blast injection system for the liquid fuel delivery. This design has been successful in meeting the introductory requirements for the liquid fuel option, but development to meet the final emissions goals continues.

Recent In-House Development The most recent SoLoNOx development activities have been concentrated in two main areas:

Production Engines Production Centaur, Taurus, Mars and Titan SoLoNOx gas turbines are now in service as prime movers for gas transmission, mechanical-drive applications, and power generation throughout the U.S., Canada, Europe, and Japan. These engines have demonstrated the capability of meeting the emissions guarantees at ambient temperatures between -20°C (0°F) in Canada and 50°C (120°F) in the Arizona/California desert. Operation has also been successful on lower Btu fuels such as Dutch Groningen gas, but with slightly higher

• Fuel injector modifications to allow a reduction in the guaranteed NOx level from 42 to 25 ppmv on natural gas fuel • Fuel injector development for No. 2 diesel firing

25 ppm NOx Guarantee Level Early development testing of the SoLoNOx system revealed that the combustion pressure oscillations became unacceptably high as NOx emissions were reduced to target levels. This was addressed in the short term by raising the pilot fuel flow that reduced the pressure oscillations to acceptable levels. Increasing the pilot fuel flow, however, increased both NOx and CO levels, limiting SoLoNOx production units to a NOx guarantee of 42 ppmv. The key to the long-term resolution of this problem was design optimization of the fuel injector premixing section. Improved fuel injector configurations have now been developed. Pressure oscillations are low at all points within the operating envelope and do not require high levels of pilot fuel. These new fuel injector

LIQUID FUEL

MAIN GAS FUEL SPOKES

PREMIX CHAMBER

PILOT GAS

PILOT CHAMBER

PILOT AIR MAIN AIR

AIR BLAST PORT

LIQUID INJECTION PORTS

082-063M/S

Figure 10. Centaur 50S Engine Installed at EPNG, Window Rock Station, Arizona

Figure 11. Prototype Dual Fuel Injector Design

7

082-062M

• Ability to address technical “surprises” that arise during product introduction or extended operation in the field. A prime example is the occurrence of unacceptably high combustor pressure oscillations, which have forced combustion system design changes throughout the entire gas turbine manufacturing community.

CO emissions than natural gas. The experience to date has shown excellent durability of the SoLoNOx combustion hardware. Inspections of the high time engines indicate that these engines will have life expectancies equivalent to Solar’s conventional engines. Table 1 presents a compilation of SoLoNOx engine operating experience.

In this environment of ever-changing driving forces, it is unlikely that low emissions combustion systems will be able to maintain complete design stability.

Table 1. SoLoNOx Experience through Dec 1999 Type

Units Sold

Estimated Hours (Millions)

Centaur 40 Centaur 50 Mercury 50 Taurus 60 Taurus 70 Mars 90 Mars 100 Titan 130 Total

81 91 9 249 83 34 124 11 682

1787 1509 2 3645 659 660 1393 10 9545

Combustor Performance Functions A well-designed gas turbine combustor must satisfy a wide range of performance criteria. The primary goal of achieving essentially 100% combustion efficiency is only one of many requirements. Other requirements include: • Producing a specific radial exit temperature profile in the gas flow delivered to the turbine section of the engine • Having a generally uniform circumferential exit temperature (as reflected in the pattern factor) to ensure turbine nozzle durability • Having sufficient operating stability to permit engine light-off and acceleration to full-load conditions • Providing combustion stability during large onand off-load transients operating without excessive combustor pressure oscillations • Maintaining sufficiently low material temperatures to meet durability requirements (30,000 hours for Solar) even under highly cyclic operating conditions • Burning widely different fuels (gases and liquids) in dual fuel systems • Avoiding coking of combustor components during liquid fuel operation • Functioning acceptably with engine inlet temperatures that may range from -20°F to as high as 120°F • Functioning acceptably in different configurations of the same turbine product. For example, gas turbines for power generation have different operating characteristics than engines for mechanical-drive applications. In addition, operating characteristics may vary in engines that are specifically designated to operate at extremely hot or extremely cold customer sites. • Meeting all of the above requirements while maintaining trace emissions concentrations (NOx, CO and UHC) at low ppm levels

MAINTAINING PRODUCT STABILITY It is understandable that one might assume SoLoNOx to be a mature Solar gas turbine technology now that eight years have passed and hundreds of turbines have been installed since 1992. Yet, numerous forces have been at work over this time period that have required SoLoNOx to evolve technically. A look to the future suggests that these same forces will continue to act. To remain competitive, SoLoNOx, as well as other dry low emissions (DLE) systems, will have to evolve. The forces that are driving the evolution of SoLoNOx include: • Continuing need to reduce NOx emissions to 25 ppm and lower to meet increasingly strict air quality regulations • Promulgation of increasingly strict CO emissions limits • Market desire for dual fuel capability (natural gas and No. 2 distillate) at many power generation sites and the growing desire to utilize a broad range of alternate fuels that need to have no visible smoke when operating on liquid fuels, even during transient operation • Product cost reductions • Need to uprate engine performance over time to meet customer requirements • Desire to introduce new turbine products to provide a more diversified product line

8

• Uniformity with which fuel is delivered to each of the 12 to 14 injectors. Non-uniform fuel flows will lead to non-uniform flame temperatures in the combustor. High local flame temperatures will contribute to high NOx, while low temperature zones may cause excessive CO emissions. • Variable rates of air leakage through seals between the combustor and other engine components can lead to air maldistributions. Seals must provide for differential thermal expansion between engine components without allowing excessive air leakage through the seal.

Clearly, combustor development can be a challenging activity, particularly when stringent emissions requirements exist. Compounding this challenge is the complexity of the gas turbine combustion process. The combustion process involves highly turbulent, reacting, high temperature, two-phase (for liquid fuels) flows that defy accurate quantitative modeling. Consequently, commercial combustor development always involves an iterative process of analysis, design, and performance testing.

Meeting Emissions Guarantees Although gas turbine output, efficiency and cost are the most important considerations for the majority of turbine operators, emissions have become a “gate” through which turbines must pass to compete in emissions-sensitive markets. Simplistically, the turbine manufacturer has two emissions-related milestones that must be met to ensure a viable low emissions product. First, the turbine manufacturing process must be sufficiently repeatable to ensure that new engines consistently meet their emissions guarantees during both preshipment testing and engine start-up at the customer’s site. In addition, the manufacturer must establish a design that is sufficiently robust to meet emissions guarantees over an extended period of operation at the customer’s site.

One final phenomenon that impacts engine test success relates to the occurrence of unacceptably high combustor pressure oscillations. Combustor oscillations tend to be of the “rumble” type (below 100 Hz) or of the “buzz” type (200 to 500 Hz). Excessive oscillations can lead to engine shutdown from high rotor vibrations or component failure due to high-cycle fatigue. At the present time, the elements of combustor design that lead to high amplitude oscillations are not well understood. The primary means of combating oscillations is through the use of pilot flames to enhance the stability of the main flames downstream of each fuel injector. In cases where oscillations occur, the amount of fuel needed for the pilot injectors varies from engine to engine. This is largely a reflection of manufacturing variability. In extreme cases, the pilot fuel required to dampen oscillations may be so large as to push NOx emissions above guaranteed levels. Combustor pressure oscillations are undoubtedly the most frustrating characteristic of lean-premixed combustion systems. Two engines, nominally identical, may have very different levels of oscillations. Attempts to correlate oscillations with engine hardware characteristics (manufacturing variances) have not been completely successful.

Meeting Emissions Guarantees at the Factory By and large, the major challenge in routinely meeting emissions guarantees with new engines relates to airflow management within the turbine. Production processes and tooling must be maintained so that the precise airflow distribution required within the engine is achieved. This includes the percentage of air flowing to the fuel injectors and combustor liner, and through other passages used to cool turbine components downstream of the combustor. Manufacturing variations in any of the injector flow areas (there are 12 to 14 nominally identical injectors in Solar’s low emissions engines), in the open area of the combustor liner, or in the orifices used to control turbine cooling will have a direct impact on the flame temperature in the primary zone of the combustor. Since NOx emissions are exponentially sensitive to flame temperature, airflow distribution is critical in meeting emissions guarantees. If too much air passes through one or more of the injectors, CO emissions may be excessive. If too little air enters the combustor through the injectors, NOx emissions may be higher than guaranteed. Other factors that influence the emissions achieved with new turbines include:

Meeting Emissions Guarantees in the Field The sensitivity of emissions to combustor and engine component design features was discussed above. From that discussion, it is clear that degradation in the combustion system components through extended operation in the field may also impact emissions. The potential mechanisms for emissions degradation are many, including: • Blockage of liner cooling holes by particulate matter or thermal distortion of the liner cooling louvers • Fretting of component interfaces that leads to increased air leakage with time

9

The development of robust low emissions gas turbines across a product line is now fully appreciated as the formidable task that it is. Low emissions turbine development in a regulatory environment, in which the emissions targets are changing with time and are established on a regional basis, adds additional complexity to an already complex task. Manufacturers have to stretch their development resources to address issues at two levels. At the first level, the challenge is to maintain a growing fleet of engines and assure that current emissions regulations can be met. At another level, resources are needed to continue technology development for the stricter emissions requirements that are anticipated for the future, but not quantified definitively (either control level or implementation date). Virtually every aspect of gas turbine manufacturing is in a cascade effect (Figure 12). The engineering and manufacturing challenges are considerable. The costs to the manufacturer are much greater than the cost increments reflected on the engine price tag. In light of the now recognized technical challenges, the progress made in the last eight years in reducing gas turbine NOx emissions from hundreds of parts per million to under 25 ppm should be recognized as a major technical achievement and a significant factor in improved air quality. Manufacturers, however, are still working to stabilize their product lines to consistently meet the 25 ppm NOx need. Industry needs a reasonable time to complete this step before it can effectively address the development of cost-effective systems for even lower emissions levels.

• Formation of local cracks in the liner due to highcycle fatigue, thermal stresses, or oxidation blockage of gas fuel ports, typically near 0.89mm (0.035-in.) diameter, or liquid fuel ports by fuel contaminants • Blockage of liquid fuel ports or the degradation of liquid fuel injection patterns due to coking • Fuel leakage within the injectors due to thermal or mechanical stresses. The need for dual fuel injectors to have gas and liquid fuel main passages, gas and liquid fuel pilot passages, and a pilot air passage makes these injectors very complex. The potential for internal leakage is considerable. Since component life is affected by turbine duty cycle, so too are emissions. Engines experiencing frequent cyclic loading and engines operated at peak conditions can be expected to show degradation in hardware more rapidly and have a higher potential for undesirably high emissions. Additionally, regarding turbine component degradation with time, two other factors may be significant in causing turbine emissions to be different in the field from emissions measured at the factory. First, a wider variation in ambient temperatures at the operator’s site will almost always occur relative to Solar’s test venue in San Diego. Extremely hot or cold ambient conditions will impact NOx and CO emissions. In addition, as neither natural gas nor No. 2 diesel are pure fuels, fuel composition variations can cause variations in emissions levels. This may not only occur between two different test sites, but also at an operator’s site where significant fuel composition variations occur over the life of the engine.

ADVANCED COMBUSTOR TECHNOLOGIES In response to the trend toward more stringent emissions regulations, gas turbine manufacturers are assessing their current lean-premixed systems to establish viable combustion system enhancements. The areas that exhibit the greatest potential for lower emissions include advanced combustor liners and more effective variable geometry systems.

Product Stability Status Based on the rapidly growing experience base with lean-premixed combustion systems, gas turbine manufacturers are now well aware that emissions are extremely sensitive to a number of factors, some of which are beyond the control of the manufacturer. These factors include: • • • • • • • •

Advanced Combustor Liners

Combustor and engine design parameters Manufacturing variability Ambient conditions Fuel composition variations Component degradation over time Fuel quality (contaminants) Engine duty cycle Combustor pressure oscillations

The present generation of lean-premixed combustors primarily uses film cooling to maintain acceptably low combustor wall temperatures. Film cooling involves the passage of cooling air through holes in the liner and the formation of a cooling film on the hot side of the liner using internally positioned louvers. Preliminary research has shown that the method used to cool a lean-premixed combustor liner can have a significant effect on emissions. Specifically,

10

MANDATED EMISSIONS REDUCTION

COMBUSTION SYSTEM REDESIGN

PERFORMANCE ISSUES

• Air Management • Low Emissions Operating Range • Transient Stability

DEVELOPMENT TEST

• Radial Profile • Emissions Tradeoffs • Oscillations • Rumble

• T5 Spread • Pattern Factor

• Rig Modifications • Controls Development • Field Testing

MANUFACTURE

• Tighter Manufacturing Tolerances • Tooling Mods/Replacement • Tighter QC

PRODUCTION TEST

• Lower 1st Test Success • Modified Test Specs • Measurement Accuracy

• Competing GT Manufacturers • Other Prime Movers • Electric Utility Grid

COST

DURABILITY

FIELD SUPPORT

• Injectors • Liners • Nozzles • Blades • Reliability • Maintainability • Overhaul Frequency • Retrofit Capability • Availability 19990469-001M

Figure 12. Cascading Effects of Reduced Emissions Limits

conventional film cooling can lead to reaction quenching at the combustor primary zone wall. This quenching process leads to high CO emissions because the CO, a combustion intermediate, is prevented from oxidizing to CO2. The quenching is traceable to the injection of a relatively large flow of cooling air into the primary zone. The development of an advanced liner that does not promote reaction quenching will provide a two-fold benefit in terms of emissions. First, of course, CO emissions will be reduced. Additionally, the lower CO levels will allow combustor reoptimization to a lower flame temperature. This will produce lower NOx levels along with the lower CO concentrations. Development work is ongoing in an effort to mitigate the reaction quenching characteristic of film cooling. Technologies being studied include augmented backside-cooled (ABC) and ceramic combustor liners.

are controlled solely through convective cooling by a high velocity airstream on the cold side of the liner (Figure 13). In most instances, the high heat flux from the flame requires augmenting of the backside conBACKSIDE-COOLED CYLINDER COOLING AIR

CONVECTOR

PRIMARY ZONE

COOLING AIR

BACKSIDE-COOLED CYLINDER

CONVECTOR

Augmented Backside-Cooled (ABC) Liners

120-004M

Backside-cooled liners forego cooling air injection completely. Instead, combustor wall temperatures

Figure 13. Augmented Backside-Cooled (ABC) Combustor Cross Section

11

gas turbine in a joint Solar/Department of Energy (DOE) program . One of the primary program goals is to explore the potential for lower emissions using these advanced combustor technologies. The ABC combustor utilizes a backside-cooled primary zone with the dome and dilution sections maintaining the current production metal configuration (Figure 14). A yttria-stabilized zirconia TBC is applied to the hot sides of the two primary zone cylinders. Testing to date has been very successful. A short in-house gas turbine test documented performance and acceptable wall temperatures at full-load conditions. A 50-hour cyclic test was completed to evaluate the TBC spalling resistance. Results from both tests are encouraging and significant emissions reductions with this liner design were observed. Figure 15 presents typical ABC liner emissions data.

vective process to keep liner wall temperatures from becoming excessive. Turbulators in the form of trip strips, fins, and pins act to increase the cooling flow turbulence at the liner wall and augment the heat removal process. Although effective in reducing CO formation through quenching, backside cooling is a challenge to implement because of the high flame temperatures and heat fluxes associated with gas turbine combustors. An additional degree of liner protection can be achieved through the application of a thermal barrier coating (TBC) on the hot sides of the liner walls. These TBCs are frequently composed of zirconia-based materials that are plasmasprayed on the liner. A typical TBC of approximately 0.25 mm (0.01 in.) can reduce wall temperatures by approximately 40oC (72oF).

Ceramic Combustor Liners The ceramic combustor addresses the CO quenching issue in the same manner as the ABC liner. Cooling air injection through the liner is avoided, thus providing potential emissions benefits. These emissions benefits have been found to be very similar to those of the ABC combustor. In the ceramic combustor configuration employing a continuous fiber ceramic composites (CFCCs) design, the inner and outer combustor cylinders that form the combustor primary zone have been redesigned to incorporate CFCC cylinders. The ceramic cylinders are housed within metallic cylinders that bear the structural and pressure loads on the assembly. The advantage of the ceramic combustor versus an ABC combustor is that ceramic materials can tolerate higher temperatures. Typical CFCC materials are expected to give good service at liner temperatures near 1100oC (2011oF) as opposed to the 850oC (1560oF) limit for typical metallic combustor liners. Monolithic ceramics can tolerate even higher temperatures, but are characteristically brittle. Currently, the high risk of turbine damage from these brittle materials effectively precludes their use in an industrial gas turbine. Although CFCCs can tolerate higher temperatures, when used as a combustor material they still require cooling. Back-side cooling of the primary zone CFCC cylinders is needed to moderate wall temperatures for good durability. Use of a metallic housing for the CFCC liners makes it more difficult to obtain adequate CFCC cooling.

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Figure 14. ABC Combustor for Centaur 50S Turbine

NOx AND CO @15% O2, ppm

25

20

15

NOx Full Load

10

5 CO 0 0

Development Status

1

2 3 4 5 6 APPROXIMATE % PILOT FUEL FLOW

7

8 120-008M

Initial development work on both an ABC combustor and a ceramic combustor is directed at the Centaur 50

Figure 15. Typical ABC Liner Emissions (Full Load)

12

Variable Geometry Systems

At the present time, a field test of a production prototype Centaur 50 ABC combustor is ongoing. The field test will demonstrate performance over an extended time period and over a wider range of turbine operation. More than 10,000 hours of successful operation have been logged. The prototype ceramic combustor design parallels the ABC design (Figure 16). The primary zone combustor cylinders of the production Centaur 50 gas turbine liner were replaced with SiC CFCC cylinders. The combustor has undergone extensive testing at Solar in both combustor rigs and an in-house gas turbine. The testing has documented that the CFCC combustor meets all performance goals established for the liner and has emissions essentially identical to the ABC combustor. At this point, the development focus is on CFCC material durability. In a 4000-hour field evaluation, the CFCC cylinders showed a moderate degree of oxidation. It has been determined that the 1200oC (2190oF) temperature limit specified early in the program for these materials is too high for a gas turbine environment. Design modifications have been completed to augment the cooling of the CFCC cylinders and to drop the temperatures to the 1100oC (2011oF) level. Durability is expected to increase at the lower temperature. Field testing of this combustor design is under way. In general, the Solar/DOE program results have demonstrated a significant emissions advantage with the CFCC and ABC combustors. In terms of the CFCC liner, additional testing is expected to document material durability. CFCC costs, however, are still considered too high for widespread commercial acceptance.

Variable geometry systems provide control over the airflow entering the gas turbine combustor primary and dilution zones. In a non-variable geometry combustion system, the flow split between the primary and dilution zones remains constant as turbine load varies. As a result, the operating range over which low emissions can be maintained is quite narrow. Varying the combustor airflow split allows the primary zone stoichiometry to be maintained at an optimum condition across a larger portion of the turbine load range. The ultimate benefit is a wider range of low emissions operation due to a finer degree of control over the combustion process. Current lean-premixed gas turbines use compressor air bleed or inlet guide vane (IGV) modulation to perform the variable geometry function. Although effective, both approaches have a negative impact. Air bleed results in a loss in turbine efficiency at part load. IGV modulation is suitable only for single-shaft gas turbines, where the compressor and gas generator are mechanically linked, and for cogeneration applications which can result in excessive boiler inlet temperatures at part-load conditions. Variable power turbine nozzles can be used to perform the variable geometry function; however, the use of modulating components in the high temperature turbine section raises gas turbine durability issues. Development work is focused on a system that will enhance the performance of low emissions gas turbines at part load.

Variable Geometry Valve System Solar is developing a variable geometry system for near-term applications where this function is removed from the fuel injector and performed by a series of valves external to the combustor liner/fuel injector subsystem. Figure 17 depicts such a system being developed for the new 14.5-MW (19,500-hp) Titan 130 gas turbine. In the Titan 130 gas turbine design, variable geometry valves are integrated into the combustor housing. The housing divides the compressor discharge flow into two airstreams that flow separately to the injectors and the combustor liner. The series of 14 variable geometry valves can be modulated to alter the flow split between the injectors and the liner. The variable geometry valve system has the potential advantage of better durability than the variable geometry injectors due to of its rugged design. This valve system, however, does have two shortcomings. First, it provides flow control over the total airflow to

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Figure 16. CFCC Liner for Centaur 50S Gas Turbine

13

Concept Description

VARIABLE GEOMETRY VALVE

Catalytic combustion produces extremely low NOx levels by operating at very low flame temperatures of 1250 to 1350oC (2280 to 2460oF). Catalytic combustor flame temperatures are below levels that can be sustained in a lean-premixed combustor. The major element of this ultra-low NOx technology is a catalytic reactor that initiates and stabilizes the combustion process at conditions not normally sustainable through homogeneous (lean-premixed) combustion. Catalytic combustor components for gas turbine applications are illustrated in Figure 18. The catalytic system has a number of features that are reminiscent of lean-premixed combustion and, in fact, a catalytic combustor can correctly be considered a catalytically stabilized, lean-premixed system. A typical catalytic combustor includes the following components: preburner, fuel injection/premixing section, catalytic reactor, homogeneous burn-out zone, part-load injector, and variable geometry system. All but the preburner and catalytic reactor are found in some form in the lean-premixed combustor.

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Figure 17. Titan 130 Gas Turbine Variable Geometry System

the injectors rather than controlling the flow into each of the injectors. Thus, the system relies on manufacturing repeatability and pretesting of the injectors to ensure that equal flows are passing through each injector. Second, the variable geometry valve system does not have the capability to control each injector separately if needed for further emissions reductions in the future.

PREMIXER

CATALYST BED

POST-CATALYST COMBUSTOR

1316°C (2400°F)

Wa = 30%

Catalytic Combustion The success of the first-generation lean-premixed combustion system has established that the technology is well-suited to meet NOx emissions levels as low as 25 ppmv. Development test data and production system performance suggest that leanpremixed combustion has the potential for even lower NOx levels. Lean-premixed combustion should be capable of meeting 15 ppmv NOx limits and perhaps limits as low as 9 ppmv. However, for a 9 ppmv NOx lean-premixed system, there may be significant load-range restrictions on the gas turbine, particularly if CO emissions limits are reduced from today’s requirements. To achieve NOx emissions levels of 9 ppmv and not compromise turbine performance, it may be necessary to find an alternative to lean-premixed combustion. Catalytic combustion, or some yet to be recognized technology, will be necessary at the 5 ppmv NOx level, a level that is beyond the capabilities of lean-premixed combustion.

MAIN FUEL INJECTOR

PART-LOAD INJECTOR

1121°C (2050°F)

Wa = 70% VARIABLE GEOMETRY SYSTEM 120-017M

Figure 18. Catalytic Combustor Schematic

SUMMARY Despite the great success of the first-generation low emissions gas turbines in lowering NOx emissions, manufacturers are dealing with the reality of even more stringent emissions regulations. Gas turbine manufacturers are working to improve the leanpremixed combustion systems used in current low

14

BIBLIOGRAPHY

emissions gas turbines and develop new and cleaner combustion technologies. Improvements being advanced for lean-premixed combustion systems include advanced liner cooling technologies and more effective variable geometry systems. These technologies are well along in their development and are nearing or are already in the field-test stage. Full commercialization will depend upon a combination of technical success, market need, and economics. Experience with lean-premixed systems over the last few years indicates that there is a practical lower NOx limit associated with lean-premixed combustion. This limit appears to be in the 9-to-15 ppmv range. To achieve NOx levels below this through low emissions combustion, gas turbine manufacturers are looking to catalytic combustion as the most likely candidate. Although under development for nearly 20 years, catalytic combustion has yet to prove itself totally in a gas turbine environment. This is attributable to both unresolved technical issues and the lack of a significant market need. The state of catalytic combustion today is comparable to the status of lean-premixed combustion 10 years ago. Significant rig testing is ongoing, but the technology has not yet progressed to the long-term field-test stage. Significant technical milestones in the areas of catalyst and substrate durability, system integration and controls remain to be achieved. Additionally, the economics of the technology need to be established as acceptable for the catalytic combustor to succeed in the marketplace. One issue affecting the development of advanced gas turbine combustion technology is the uncertainty in emissions levels that will be required in the future and a timeline for their implementation. Manufacturers are unable to focus development resources costeffectively on well-established emissions targets, but must broaden development efforts to meet a range of emissions constraints. With limited resources available, this results in a slower pace of technology development.

Etheridge, C.J., 1994, “Mars SoLoNOx Lean-Premix Combustion Technology in Production,” ASME Paper 94-GT-255, International Gas Turbine and Aeroengine Congress and Exposition, The Hague, Netherlands. Mutasim, Z.Z., 1998, “Coating Technology Advancements for Industrial Gas Turbines,” TTS117, Turbomachinery Technology Seminar, Solar Turbines Incorporated, San Diego, California. Rocha, G., Etheridge, C.J., and Hunsberger, R.E., 1998, “Evolution of the Titan 130 Industrial Gas Turbine,” TTS122, Turbomachinery Technology Seminar, Solar Turbines Incorporated, San Diego, California. Schneider, P.H., 1998, “New Technologies in Advanced Turbine Systems,” TTS130, Turbomachinery Technology Seminar, Solar Turbines Incorporated, San Diego, California. Smith, K.O. and Fahme A., 1996, “Experimental Assessment of the Emissions Benefits of a Ceramic Gas Turbine Combustor,” ASME Paper 96-GT-318, International Gas Turbine and Aeroengine Congress and Exhibition, Birmingham, United Kingdom. Smith, K.O. and Fahme, A., 1997, “Testing of a Full Scale, Low Emissions, Ceramic Gas Turbine Combustor,” ASME Paper 97-GT-156, International Gas Turbine and Aeroengine Congress and Exhibition, Orlando, Florida. Smith, K.O. and Fahme, A., 1998, “BacksideCooled Combustor Liner for Lean Premixed Combustion,” International Gas Turbine and Aeroengine Congress and Exhibition, Stockholm, Sweden. Solt, J.C., 1997, Catalytica, personnal communication, Mountainview, California. van Roode, M., Brentnall, W.D., Smith, K.O., Edwards, B.D., Faulder, L.J., and Norton, P.F., 1996, “Ceramic Stationary Gas Turbine Development Program-Third Annual Summary,” ASME Paper 96GT-460, International Gas Turbine and Aeroengine Congress and Exhibition, Birmingham, United Kingdom.

15

Turbomachinery Technology Seminar

Increasing Turbine Life through Improved Maintenance Procedures

Contents Page INTRODUCTION

104-1

BACKGROUND

104-1

INLET AIR CONSIDERATIONS

104-2

WATER QUALITY ISSUES

104-5

FUEL QUALITY ISSUES

104-7

LUBE OIL CONSIDERATIONS

104-8

VIBRATION PROBLEMS

104-9

HEAT RECOVERY PROBLEMS

104-10

MAINTENANCE PROGRAM BENEFITS

104-10

SUMMARY

104-11

BIBLIOGRAPHY

104-12

Cat and Caterpillar are trademarks of Caterpillar Inc. Solar, Saturn, Centaur , Taurus, Mars, Turbotronic, and SoLoNO x are trademarks of Solar Turbines Incorporated. Specifications subject to change without notice. Printed in U.S.A. Copyright © 1995 by Solar Turbines Incorporated. All rights reserved. TTS104/395

Increasing Turbine Life through Improved Maintenance Procedures Q.K. Stewart Regional Service Manager – Eastern U.S.

INTRODUCTION Gas turbine overhaul is the largest single maintenance expense that turbomachinery users will face over the service life of their equipment. Fortunately, most modern turbomachinery has been designed to operate continuously for years before an overhaul. Many turbomachinery users routinely operate their gas turbine packages 30,000 to 40,000 hours before gas turbine overhaul is performed. Some turbines have logged over 100,000 operating hours before they were overhauled. Due to several improvements in industrial gas turbine design, maintainability, reliability, and durability, the overwhelming majority of gas turbines are removed for overhaul in a nonfailed condition. Several turbomachinery users remove these nonfailed gas turbines as part of a “fired-hour” overhaul agreement with Solar. Regardless of the level of maintenance performed on the turbomachinery, however, overhaul of the gas turbine is inevitable. This paper examines maintenance and operating practices that could increase the time between inspections (TBI) at an overhaul facility, and reduce the risks of more costly unscheduled equipment outages.

BACKGROUND Although turbomachinery overhaul is the greatest single maintenance expense in equipment lifecycle cost analysis, unscheduled or unexpected gas turbine outages could be the costliest of all events. With an unscheduled turbine outage, the damage to the engine is almost always more extensive than what would be expected at a planned overhaul interval for a properly maintained unit. This usually requires the replacement of significantly more parts and components in the turbine, and the damage to the turbine parts and components is usually more severe. Such extensive turbine damage often

eliminates the more cost-effective option of repairing only slightly damaged or worn parts and material. Consideration also needs to be given to the cost of premature turbine overhauls from the perspective of the present value of the earlier-than-expected overhaul expense. For example, if a turbine owner anticipates achieving 30,000 operating hours (about 3.5 years of continuous service) between overhaul intervals, and if an unexpected turbine outage occurred after only 15,000 operating hours (slightly less than two years of continuous service), the additional present value cost to the owner would be $14,490 assuming a $100,000 overhaul expense at a 7% effective capital borrowing rate. The turbine owner would have a newly overhauled turbine engine that may reasonably be estimated to operate 30,000 hours until the next overhaul cycle, but the first overhaul occurred two years earlier than originally planned, and all subsequent overhauls for that turbine will be scheduled 15,000 hours or two years sooner than planned, given the same projected service life. The costliest aspect of an unexpected or unplanned turbine failure is the unavailability of turbomachinery that is critical to business operations. This is especially true in the oil and gas production, gas transmission, and power generation industries, where unexpected turbine outages can result in significant costs or revenue losses in millions of dollars. For example, a 2983-kW (4000-hp) turbine-driven compressor package in an offshore gas gathering application compressing 50 million standard cubic feet per day (scfd) at a compression ratio of 3.2 to 1 would result in a $100,000 per day revenue loss at a gas cost of $2 per thousand scf. The truly unfortunate aspect of most unexpected turbine outages is that such problems could often have been avoided if there had been greater attention given to turbomachinery maintenance. lt is estimated that fully 30% of the overhauls in the

104-1

745-to-3730 kW (1000-to-5000 hp) range are a result of poor maintenance practice and that most unscheduled equipment outages are preventable. If all unscheduled equipment failures could be eliminated, the average product TBI in the 745-to3730 kW (1000-to-5000 hp) range could be increased by 17%. From an equipment cost standpoint, this equates to a 22% overall reduction in overhaul costs that turbomachinery owners would pay if maintenance programs were improved to avoid unscheduled equipment outages. With this basic understanding of how costly unscheduled gas turbine outages can be, several primary areas should be reviewed where poor maintenance practices typically result in premature gas turbine overhauls and failures. These areas include inlet air, water, fuel, lube oil, vibration, and heat recovery systems. Some of these maintenance issues are relatively well known to experienced turbine users, but problems continue to occur which could have been prevented by proper maintenance programs and timely corrective action.

quate supply of clean air. Most air inlet systems have metal ducting and supports made of carbon-based steel. This steel is painted first with an inorganic zinc primer, then with an epoxy polyamide primer and, finally, with a polyurethane top coating. These metal air inlet ducts generally use rubber gaskets and waterproof sealants at joints and flanges to prevent air from bypassing the filter media. However, even the best air inlet systems often deteriorate with the passage of time and exposure to the elements and, without corrective maintenance, some of these materials may break loose and cause FOD to the compressor. For example, compressor damage and fouling may result from: • Chipping or scaling (Figure 2) of the paint in the air inlet system • Rust scale (Figure 3) where oxidized material is ingested into the engine • Ingestion of sound attenuating or silencing material

INLET AIR CONSIDERATIONS One of the most prevalent causes of unscheduled outage is poor air inlet/filtration system maintenance, which commonly results in foreign object damage (FOD) and/or fouling to the turbine compressor section. Such damage or fouling necessitates expensive compressor section rework that is not usually required during routine overhauls.

Foreign Object Damage When new turbomachinery equipment is ordered, great care generally is taken to ensure that air inlet (Figure 1) and filter systems are specified and installed on the turbine, which will provide an ade104-004M/S

Figure 2. Paint Peeling within Air Inlet System

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Figure 1. Typical New Air Inlet System

Figure 3. Area Rusted through in Air Inlet System

104-2

Ducting gaskets and sealing material also may become hardened or brittle and crack with age. If these materials disintegrate, they can enter the inlet airstream and cause damage when they are ingested by the engine.

Unfiltered Contaminants The ingestion of contaminated air resulting from air inlet system leakage or dirty or deficient filtration media also can cause extensive corrosive pitting throughout an engine. Compressor blades and stator vanes (Figure 4) sustain the majority of the damage. Contaminated air also can enter the buffer seal air passages, causing friction, wear and damage to the carbon seals (Figure 5). Wear on the forward turbine seal allows oil to seep past the seals and into the compressor airstream, adding more contamination to the compressor section. Air inlet systems frequently are equipped with “blow-in doors,” which are actuated and opened (Figure 6) if the pressure differential across the filter media becomes too high. Without proper maintenance, these systems sometimes malfunction or simply remain open if the differential across the air filter remains high. As with other types of leaks in the air inlet system, an open blow-in door will cause a reduction in air inlet filter back pressure, but unfiltered air will continue to enter the turbine.

In addition, some air inlet systems are rendered ineffective due to cavitation of the filter media (Figure 7) or improper sealing or seating of the air filters in the filter housings. In cases of premature overhaul or failure, the air inlet system itself all too frequently has not been included in a planned maintenance program. The entire air inlet system should be inspected both inside and out on a yearly basis, preferably prior to the start of the winter operating season. Maintenance Recommendations. The system should be checked thoroughly for signs of rust, peeling paint on the inside of the air inlet ducting, leaks in the air inlet system, and cracking of gasket or silicon material on ducting joints and covers. For a 2983-kW (4000-hp) ISO-rated gas turbine, a 25.4 mm (1 in.) air inlet system pressure differential causes a power loss of approximately 0.5%. Proper operation of all air inlet “blow-in” doors should be verified and the differential pressure measurements across the filter media must be within allowable limits.

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Figure 6. Air Inlet Housing with Top Mounted Blow-In Door

Figure 4. Contaminated Stator Vanes

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Figure 5. Damaged Carbon Seal and Bearing

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Figure 7. Air Inlet Filter Needing Replacement

104-3

lt is important to ensure that any silencing material used in the air inlet system has not deteriorated so it will not break loose and cause FOD to the compressor section. ln some cases, as when operating conditions have changed substantially or where damage or deterioration to the existing air inlet system is extensive, it may be advisable to install a new air inlet system (Figure 8) with maintenancesaving features, such as self-cleaning pre-filters and/or stainless-steel duct work for offshore and corrosive environments. Avoiding dirty or fouled engine air compressors may be the biggest opportunity for turbine operators to increase efficiency and reduce operating costs. However, compressor water washing (Figure 9) is a routine maintenance task that often is taken for granted. Some turbine owners clean their turbine air compressors on a regular time interval, while others will perform compressor cleaning only when compressor discharge pressure (Pcd) has declined, usually about 5% from baseline (Figure 10). It is best to establish the compressor discharge pressure baseline, which may vary somewhat with changes in ambient temperature, when the equipment is new or when the gas turbine has just been overhauled. A fouled compressor penalizes engine operation because more fuel is required to maintain the same power output. ln T5 temperature-topped operation, reduced compressor discharge pressure associated with fouling equates to a loss in mechanical or electrical output. Every year, several gas turbines are removed from operating service for overhaul only to find that the loss of performance was due to a fouled compressor and that the compressor section of the turbine needed to be thoroughly cleaned.

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Figure 9. Typical Water Washing Process

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Figure 8. New “Huff-and-Puff” Air Filter System

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Figure 10. Typical Turbotronic Display of Pcd over Time

104-4

The gas turbine manufacturer’s guidelines provided in the operation and maintenance manuals and in applicable service bulletins should be followed carefully when compressor cleaning is undertaken. Using the right quantity of compressor cleaning agent is essential because an insufficient amount will not provide adequate results and using too much cleaner may cause bent airfoils in the compressor, as well as bearing damage from excessive loading. Another important step is to ensure that all liquid is purged from the engine following routine water-wash cleanings. Some overhauls become necessary as a direct result of inadequate purging of cleaning fluids that subsequently cause corrosion in the compressor variable guide vane area. The operator also should make sure that the entire diameter of the compressor is cleaned. Cleaning one section of the assembly will improve compressor discharge pressure only slightly and may create an imbalance that will cause compressor rotor vibration. Use of abrasive turbine compressor cleaning agents should be used as a last resort on some engines and never on second-generation engines with compressor coatings and internally cooled nozzles and blades. To prevent thermal shock to engine components, a cool-down procedure may be required before water or other liquids are injected into the compressor assembly.

the air inlet duct, which allow water to seep into the inlet system, or moisture, which puddles in low spots inside the air inlet duct. After solidifying, the ice slags off and impinges upon the first-stage compressor blades. Many turbine operators have the impression that ice ingestion is a serious problem only in extremely cold ambient temperatures. However, most damage from ice ingestion occurs during turbine operation in ambients between -7 and 5°C (20 and 40°F) and when there is some evidence of moisture, such as fog, rain, or snow. Ice ingestion damage to an engine generally will result in a slight loss of turbine performance and often is accompanied by a noticeably different noise profile during turbine operation.

Ice Ingestion

Hot Corrosion

During winter, engines may fail from ice ingestion. The FOD generally is not extensive because the ingested ice ordinarily damages only a few first-stage compressor blades (Figure 11) and then breaks up and melts as the ice moves aft through the compressor rotor. The ice usually forms due to either leaks in

Before the recent introduction and acceptance of dry, lean-premixed combustion technology for NOx pre-

Maintenance Recommendations. Although anti-icing features are available commercially for air inlet systems, the best means to prevent ice ingestion is to seal any leaks in the system and to prevent water or snow from accumulating on top of them.

WATER QUALITY ISSUES ln recent years, overhauls have increased due to operators using water beyond specification limits in combustor water-injection systems for NOx emission control (Figure 12) or in evaporative coolers to cool the turbine inlet air.

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Figure 11. First-Stage Compressor Blade with Ice Damage

Figure 12. Typical Package with Water Injection for NOx Control

104-5

vention, the most popular means to reduce NOx formation was to inject water or steam into the combustor. While this process has been effective, several engines have sustained significant hot corrosion damage in their combustor and gas producer sections due to the high levels of sodium commonly found in untreated water. Figure 13 shows a first-stage turbine blade that sustained extreme hot corrosion damage after a few hours of operation with water for NOx control which did not meet manufacturer specifications. Evaporative coolers or chillers (Figure 14) have been used by turbine operators in locations with high ambient temperatures and relatively low humidity to reduce air inlet temperatures and, thus, to increase engine output. However, water or mist carry-over into the turbine can occur from evaporative coolers. If the water used for the evaporative cooler does not meet manufacturer specifications, extensive damage to the turbine hot section components can occur. Figure 15 illustrates the damage to a first-stage blade where untreated evaporative cooling water carried over into the turbine.

Maintenance Recommendations. To overcome problems associated with hot corrosion of turbine components, the water specifications always must be adhered to stringently for all water ingested. This includes water that is used for wet NOx control, evaporative air inlet coolers, or compressor wash water. Continuous water quality monitoring is essential for water-injected NOx reduction systems because, given the large quantities of water required, even a few hours operation with water that is out of specification can cause serious damage. The turbine should

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Figure 14. Typical Evaporative Cooler

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Figure 15. First-Stage Turbine Blade Damage from Out of Specification Evaporative Cooler Water Carry-Over

104-013M/S

Figure 13. First-Stage Turbine Blade with Hot Corrosion Damage

not be operated when the NOx reduction water fails to meet specifications. Turbine users might seriously consider retrofitting their turbine units with the latest technology of dry, low NOx turbine combustion systems at the next overhaul cycle. The initial cost of the dry, low NOx retrofit most likely will be more than offset by the costs of maintaining the typically high volumes of treated water required to achieve the same level of NOx reduction. For example, 11 L/m (3 gpm) are typically required for a

104-6

3356-kW (4500-hp) turbine operating with a 0.65 water-to-fuel ratio.

FUEL QUALITY ISSUES Localized thermal damage in the combustor and firststage nozzle area and thermal erosion and coking of fuel injectors are symptomatic of liquid hydrocarbons in a gas turbine fuel system. While such liquids occur more prevalently in natural gas gathering and gas reinjection applications, gas pipelines also may contain some accumulated hydrocarbon liquids due to leaks in gas compressor oil seals upstream of the engine compressor and/or condensation resulting from gas pressure drops across valves and pressure regulators.

a. Normal Condition

104-019M/CD

Gas Fuels Untreated wellhead gas or associated gas recovered during oil production also may have fuel-bound contaminants, especially sulfur. Any such sulfur in excess of specification which enters the turbine combustion process may cause material sulfidation and rapid erosion of turbine hot section components. Figure 16 shows the carbon build-up, resulting from impurities in the fuel, on the gas fuel injector nozzles from a gas turbine. Blockage of some of the fuel ports occurred in several of the nozzles. This restriction or blocking (Figure 17) forces the natural gas out of the other unblocked ports at a higher pressure, which causes the flame pattern in the combustor to move aft. The aft movement of the flame pattern will cause thermal erosion on the firststage turbine nozzle (Figure 18). The blockage also will divert the gas flow and can cause thermal erosion of the combustor outer liner as well (Figure 19).

104-030M/CD

b. Condition with Clogged Fuel Injectors Figure 17. Combustor Flame Patterns

104-020M/S

Figure 18. First-Stage Nozzle Damage

104-021M/S

104-018M/S

Figure 16. Carbon Build Up on Fuel Nozzles

Figure 19. Combustor Liner Thermal Damage

104-7

Liquid Fuels Liquid fuels also have the potential to become contaminated, most commonly due to the presence of water or paraffin waxes or through poor or dirty fuel storage. Liquid fuels need to be checked periodically on dual fuel and standby power generation units for water accumulation and contamination. While gas turbines can operate on a wide variety of fuels, a review of fuel suitability and compliance with manufacturer specifications is critical for turbine life.

filter and separator systems are installed. At sites where fuel gas pressures drop more than 14 bar (200 psi) to operating fuel gas pressure, consideration should also be given to the installation of fuel gas heaters to prevent liquid condensation.

LUBE OIL CONSIDERATIONS Turbine failure due to lube oil issues has caused problems for some operators. Wear metals and contaminants that are not filtered out of the lube oil system can cause scoring on bearings and journals.

Maintenance Recommendations. Damage to en-

Contaminated Oil

gines from liquid hydrocarbons in the fuel gas can be avoided by the installation and proper maintenance of fuel filter and separator systems (Figure 20) installed near the turbine package. Analysis of gas fuel contaminants always should be made and liquids in the gas fuel control filter should be checked. Scrubber vessels, while important for removing large quantities of liquids, usually are not adequate for gas turbine fuel systems. Proper maintenance of scrubber vessel level switches and dump valves is required, even if fuel

Lube oil contamination frequently is a result of adding oil or oil additives which do not comply with manufacturer specifications. ln the case of turbine-driven gas boost compressors with wet oil seal systems, the oil can become contaminated after extended use and reflect an increase in acidity. ln other cases, sealing material commonly used on gearboxes and interconnect coupling covers can deteriorate and be carried into the lube oil sump. Figure 21 shows thrust bearings from a gas turbine that has been operated with contaminated lube oil. There are numerous small scratches on the surface of the babbitt material and the accumulation of babbitt in the oiling glands of the aft thrust washer. Over an extended period of time, this babbitt would build up in the oiling glands and restrict the flow of lube oil to the bearing, resulting in oil starvation and bearing failure. Some lube oil-related failures are the result of starting or operating the engine in cold ambient temperatures without heating the lube oil sump or bypassing the lube oil coolers until the lube oil has reached a satisfactory operating temperature.

104-023M/S

104-022M/S

Figure 20. Typical Fuel Gas Filter/Separator

Figure 21. Thrust Washers

104-8

Depending on lube oil type, the oil operating temperature without a sump heater should be between 16 and 30°C (60 and 85°F). Maintenance Recommendations. Lube oil analysis (Figure 22) is an excellent maintenance tool to help determine the condition of the engine. Spectrochemical oil analysis to detect increased levels of wear metals is available from a variety of sources. The analysis also should check for oil viscosity, the presence of water, and the total acid number. The key to a successful lube oil analysis program is to watch for changes and trends in the condition of the oil over time. Turbine lube oil needs to be changed only if the oil is beyond manufacturer specifications. In the event of a change to a different lube oil or oil additive when the oil tank is refilled, the operator must make sure it meets the gas turbine manufacturer’s specification. When a different viscosity oil is used, it is important for the recommended oil operating temperature to be considered, particularly during starts in colder weather. Many older gas turbine packages do not have lube oil tank heaters. A change to a different viscosity oil may require installation of a lube oil heater. In addition, the experienced operator will, upon removal of any major turbine component, always check the lube oil for metal contaminants and examine the bottom of the oil tank sump for unusual accumulations.

VIBRATION PROBLEMS ln the past decade, real-time vibration analysis (Figure 23) has become widely available in the turbomachinery industry. However, the absence of

104-025M/S

Figure 23. Typical CSI Vibration System Equipment

vibration data or inaccurate data has resulted in some operators experiencing costly equipment outages and avoidable overhaul costs. Sometimes, suspected engines are removed from service and sent in for overhaul due to suspected vibration problems only to be found to have vibration levels well within specification when the turbines are run in a test cell prior to overhaul. While there undoubtedly was high vibration in the turbine package, the problem was due to improper equipment alignment, coupling wear or imbalance, coupling lubrication or grease, worn trunnion mounts (on older packages), and imbalance or vibration problems in the turbine’s driven equipment.

Maintenance Recommendations. Vibration mea-

104-024M/S

Figure 22. Typical Lube Oil Analysis Data Sheet

surements should be made consistent by ensuring that the same points and equipment are used for data acquisition. In analyzing vibration data, absolute vibration limits should be considered, as well as trends to determine what is going on in the package. Microprocessor-based turbine control systems (Figure 24) are well suited for gathering and trending vibration data over time. Alignment verification and coupling checks should be made on an annual basis or whenever major turbine components are exchanged or overhauled. Particular care should be taken on older turbine packages to ensure that engine trunnion mounts are not worn and that inlet and exhaust systems or boost compressor suction and discharge piping do not contribute to turbine package vibration.

104-9

Many good vibration analysis programs (Figure 25) are available to customers. As with lube oil analysis, the key to good equipment vibration programs is establishing a vibration baseline or signature at the time a new turbine is installed or just after overhaul.

HEAT RECOVERY PROBLEMS Gas turbines are extremely well suited for applications with exhaust heat recovery (Figure 26). The utilization of exhaust thermal energy from a turbine can achieve 70% net system efficiency unfired and 84% efficiency with supplemental firing. However, the addition of an exhaust heat recovery system must be undertaken carefully to ensure that the heat recovery system does not damage or impair turbomachinery life.

104-027M/S

Figure 24. Typical Turbotronic Vibration Display Summary

104-028M/S

Figure 26. Typical Package with Waste Heat Recovery

The most common exhaust heat system problem resulting in damage to the turbine is malfunction of the exhaust diverter valves. If a gas turbine is shut down with its diverter valve open (Figure 27) and heat continues to be supplied to its exhaust heat recovery equipment either via supplemental firing or from the exhaust of another operating package, there will be a back flow of hot air through the idle turbine which can damage its variable geometry grommets. Turbine damage also will occur occasionally due to a diverter or exhaust system weather cover being in a closed or partially closed position during turbine start, thereby causing low speed turbine surge. Maintenance Recommendations. Exhaust back pressure should be monitored and maintenance checks performed regularly for turbines fitted with exhaust heat recovery systems to ensure the proper operation of exhaust heat diverter valves. Any installed weatherhoods and covers also should be included during the maintenance checks. It is worth noting that every 25.4 mm (1 in.) of water back pressure imposed by the heat recovery equipment on the turbine exhaust will exact a penalty of about 7.5 kW (10 hp) for a 3000-kW (4000-hp) gas turbine. Turbine control systems can be designed or modified to notify turbine operators when hot air from exhaust heat recovery systems feeds back or leaks through the diverter valves.

MAINTENANCE PROGRAM BENEFITS

104-026M/S

Figure 25. Typical CSI Vibration Survey Data

A well-planned and properly executed maintenance program will provide numerous benefits to the gas turbine owner, including avoidance of unscheduled equipment outages, increased overhaul intervals, and lower overhaul and operating expenses.

104-10

EXHAUST BYPASS SILENCER

AIR INLET FILTER

EXHAUST SILENCER

HEAT RECOVERY STEAM GENERATOR (HRSG)

GENERATOR GAS TURBINE DIVERTER VALVE

SUPPLEMENTARY BURNER

104-029M

Figure 27. Diverter Valves in Waste Heat Ducting

When allowed to persist, all of the problems discussed above, including inlet air considerations, water quality issues, fuel quality issues, lube oil considerations, vibration problems, and heat recovery problems, will result in a reduction in equipment performance and possibly either immediate or longterm damage to the turbine equipment. Component damage as a result of these problems almost always will be evident at overhaul. Furthermore, problems such as a dirty turbine compressor section or a high air inlet filter differential can result not only in earlier and costlier turbine overhauls, but also in loss of turbine efficiency and additional operating costs. For example, a 3505-kW (4700-hp) turbine will lose about 22 kW (30 hp) for each psi of compressor discharge pressure lost due to contamination. A 5% decline in compressor discharge pressure would equate to a loss of 145 kW (200 hp), with the fuel flow remaining constant. If the natural gas cost were $2 per thousand scf, this would result in an additional fuel cost of $35,000 annually. The most serious economic effect on the turbine operator, however, would be the loss of production and profit that the equipment could have generated. If the 3505-kW (4700-hp) turbine in this example were in a power generation application, the 5% de-

cline in Pcd would result in a loss of approximately $300 every day on power produced at $0.08/kWh.

SUMMARY Turbomachinery owners should make the effort to improve or correct maintenance practices to improve equipment performance, extend the time between overhaul, and increase the life of the equipment. Operators should witness the disassembly of the unit in the overhaul shop, even if an exchange engine is used, because this will help them understand what was wrong inside the unit and gain additional insights into what may have caused the damage. Owners should review the condition of the engine, study the engine condition report and then take the next steps by performing a root-cause analysis of the problems. Those findings should initiate positive changes in maintenance and operating procedures. One of the major advantages of recent advancements in microprocessor-based turbine control systems is their ability to not only record performance data, such as compressor discharge pressure, vibration data, operating temperatures, and turbine power output, but also to trend the data and to predict when corrective action such as compressor cleaning needs to be performed.

104-11

By incorporation of improved maintenance practices and control system advancements, turbine users can help avoid unscheduled equipment outages, increase the average time between inspections (TBls), reduce the cost of overhaul expense, lower the cost of turbine operation, and increase the value of their turbomachinery.

BIBLIOGRAPHY Corzine, E.S., 1995, “Turbine Control Systems Update,” TTS72, Turbomachinery Technology Seminar, Solar Turbines Incorporated, San Diego, California. Jepson, P.B., 1989, “Documenting and Reducing Gas Compression Equipment Maintenance Costs,” TTS58, Turbomachinery Technology Seminar, Solar Turbines Incorporated, San Diego, California.

Lehmann, D.M. and Keller, B.B., 1986, “Technological Advancements for Servicing of Turbomachinery,” TTS35, Turbomachinery Technology Seminar, Solar Turbines Incorporated, San Diego, California. Hsu, L.L. and Aurrecoechea, J.M., 1995, “Air, Fuel and Water Management,” TTS89, Turbomachinery Technology Seminar, Solar Turbines Incorporated, San Diego, California. Ryan, W.T. and Tse, K.B., 1995, “Interpretation of Vibration Data on High Speed Turbomachinery,” TTS112, Turbomachinery Technology Seminar, Solar Turbines Incorporated, San Diego, California. Woods, C.S. and Bliss, W.J., 1992, “Quality in Maintenance,” TTS81, Turbomachinery Technology Seminar, Solar Turbines Incorporated, San Diego, California.

104-12

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mars, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

2.0/102A April 1998 February 1999 Mars All Mars Turbines with Hydraulic, Pneumatic and Electric Start Systems

SUBJECT: MARS OVERRUNNING (SPRAG) CLUTCH Type of Change:

Product Improvement

Recommended Compliance:

Information

Purpose: To alert Customers of the availability of an improved sprag clutch for the Mars start system. GENERAL INFORMATION: Continued product development has resulted in the availability of an improved overrunning (sprag) clutch for the Mars Turbine start system. Solar now incorporates the newest version Accessory Drive Assembly (P/N 117850-30) in all new production start systems and the improvement is available for all replacements in the field. DESCRIPTION: The previous P/N 117850-10 and P/N 117850-20 Accessory Drive Assemblies can be upgraded to a P/N 117850-30. The new overrunning starter clutch has inherent friction that causes the starter to rotate after starter dropout. It is normal for this to occur, and speeds up to 5400 rpm can be reached without any detrimental effect to the starter system.

SERVICE BULLETIN NUMBER: 2.0/102A

Page 1 of 2

ACTION: To order an upgraded Accessory Drive Assemblies P/N 117850-30 contact your Solar Service Parts Representative or to obtain more information regarding this product improvement contact your local Solar Field Service Office.

Page 2 of 2

SERVICE BULLETIN NUMBER: 2.0/102A

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

2.0/103 April 2001 Mars/Titan All Mars/Titan Turbines with Hydraulic or Electric Start Systems

SUBJECT: STARTER CLUTCH IMPROVEMENT Type of Change:

Product Improvement

Recommended Compliance:

Information

Purpose: To announce the availability of an improved clutch for the Mars and Titan start systems. GENERAL INFORMATION: Continued product development has produced an improved clutch system for the Mars and Titan turbine starter systems. This improved design incorporates a Synchro-Self-Shifting Clutch system that will improve the Mars and Titan clutch assembly’s reliability. In addition, the new clutch assembly will not cause the starter to rotate after starter drop-off. Solar now incorporates this improved design of the starter clutch assembly, P/N 301575-100, in all new production hydraulic and electric start systems. The previous P/N 117850-10, P/N 117850-20 and 117850-30 clutch assemblies employs a sprag clutch (Figure 1) and can be upgraded to the improved design P/N 301575-100 (Figure 2), at the customer’s discretion.

SERVICE BULLETIN NUMBER: 2.0/103

Page 1 of 3

ACTION: To order an upgraded clutch assembly Solar P/N 301575-100, contact the local Solar Service Parts department. The following table list retrofit kit part numbers:

Kit Part Numbers

Product/Model

1046632-1XX

Mars GS

1046632-2XX

Mars CS/MD

1046632-3XX

Titan CS/MD

Please contact the local Solar Field Service office for assistance as required.

Figure 1 Sprag Clutch Assembly

Page 2 of 3

SERVICE BULLETIN NUMBER: 2.0/103

Figure 2 Synchro-Self-Shifting Clutch P/N301575-100 Keylist for Figure 2 1

Output Clutch Ring

2

Helical Sliding Component

3

Output Assembly

4

Rotor Shaft

5

Starter

6

Primary Pawl

7

Ratchet

8

Secondary Pawl

SERVICE BULLETIN NUMBER: 2.0/103

Page 3 of 3

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

3.3/106A June 1999 April 2001 Mars 90, Mars 100 All Mars Standard Combustion "Dual Fuel" Applications

SUBJECT: FUEL MIGRATION; LIQUID COLLECTION IN STATIONARY FUEL AND AIR LINES —REVISION NOTICE— This revision replaces Service Bulletin 3.3/106. The previous bulletin must be removed and discarded. This version announces the availability of an improved retrofit kit.

Type of Change:

Product Improvement

Recommended Compliance:

Earliest Convenience

Purpose: •

To announce the availability of an improved retrofit kit to alleviate the fuel migration problem of dual fuel Mars engines.

•

To inform customers about additional kit modifications and control logic changes to optimize the purging of the air assist and liquid fuel lines after a turbine shut down.

SERVICE BULLETIN NUMBER: 3.3/106A

Page 1 of 5

GENERAL INFORMATION: The original purge kit released in 1999 prevented liquid fuel migration into the gas fuel manifold. This kit has now been optimized and expanded to correct other problems with liquids collecting in fuel and air assist lines of running and/or stationary gas turbine packages. PURPOSE OF RETROFIT KIT: 1.

Prevent liquid fuel migration (original kit): Mars dual fuel units with standard combustion systems operating on liquid fuel have been experiencing problems associated with migration of liquid fuel into the gas fuel manifold. The liquid fuel cokes in the injector passages, causing problems with subsequent gas fuel operation. Also, some of the injector fuel lines were found to have excessively elevated temperatures at the sites with the fuel migration problem. Both problems are caused by recirculation of combustor air between injectors with slightly different pressure levels (cross flow).

2.

Additional problems addressed in the modified kit: •

The reverse-flow purging of the liquid fuel lines after a transfer to gas fuel or after a package shut down is sometimes incomplete. The problem is most severe if a liquid fuel line purge is initiated after an aborted start attempt on a hot engine. PCD pressure is very low at that time. The driving force to back-purge the fuel lines and injectors is missing and not all fuel is purged. The residual fuel remaining in the liquid fuel lines and injectors may coke up and block the injectors.

•

Condensed water and other liquids may accumulate in the air assist lines during turbine operation and/or after a package shut down. During a start attempt on liquid fuel, this liquid is blown into the torch, delaying or preventing light off. In cold weather, the liquid may freeze during package standstill, completely preventing any further start up.

DESCRIPTION OF KIT: 1.

ORIGINAL KIT: The PCD forward purge system has been developed for the Mars dual fuel standard engines to alleviate the fuel migration problem on a running turbine. This system prevents the entrapment of liquid fuel into the gas passageways of the dual fuel injectors and the resulting plugging of these passageways with coke and carbon. A positive flow of PCD air through the gas fuel manifold and the gas passageways of the injectors prevents the entrance of liquid fuel. This positive flow of PCD is achieved by the use of a connecting line between the combustion chamber housing and the gas fuel manifold through two automated high temperature shutoff valves. The pressure drop across the combustor liner provides the pressure differential to achieve the airflow. Without this purging

Page 2 of 5

SERVICE BULLETIN NUMBER: 3.3/106A

airflow, liquid fuel can be carried into the gas passageways by "cross flow" due to the small pressure differences around the combustor. 2.

KIT MODIFICATIONS: The latest kit contains modifications based on experience gained with operating packages. •

A larger dP transmitter range allows the use of a less sensitive test orifice and permits differential pressure measurements across the whole operating range.

• 3.

PCD air is taken from a separate take-off port on the combustor housing to prevent interference with the bleed valve operation. ADITIONAL FEATURES OF REVISED KIT: •

The liquid fuel purge time (back purge) after a package shut down has been lengthened to 180 seconds to ensure complete drainage of the fuel system. The first 120 seconds are continuous purge, followed by four (4) cycles of ten (10) seconds off/five (5) seconds on (pulse purges), to allow any trapped fuel to collect and then be removed. The original purge time of 20 seconds is insufficient.

•

After a package shut down, the combustor air pressure (PCD) available to induce reversed flow decreases rapidly due to the falling gas producer speed. Therefore, the starter is engaged to keep the engine turning at purge crank speed. This produces a certain PCD pressure and guarantees a minimum driving force to back-purge the fuel injectors, providing the additional purging needed.

•

After an unsuccessful light-off attempt on diesel fuel, the turbine continues to crank for another 180 seconds. As with the purge after a shutdown, there is 120 seconds of continuous back purge, followed by four (4) five (5) second pulse purges with ten (10) seconds between.

•

The air assist system is activated during engine roll down to blow out possible liquids accumulated during engine operation ("forward purge" of air assist line into the coasting turbine). Liquids could freeze during package standstill and may prevent the next start up.

•

Liquids collecting in the air assist and fuel manifolds during package standstill (condensed water, lube oil, residual liquid fuel) must be purged. To remove those liquids, the start up sequence has been altered: •

The liquid fuel purge valves are being re-opened during the turbine purge crank cycle for a final fuel line blow back.

•

The torch drain valve is re-opened during the turbine purge cycle to remove possible condensed water, fuel and lube oil from the torch before light off.

SERVICE BULLETIN NUMBER: 3.3/106A

Page 3 of 5

•

If a start on liquid fuel is selected, the air assist solenoid is activated during the first 45 seconds of purge crank to blow the line clean and to improve the torch operation.

•

After a fuel transfer from liquid to gas, the purging sequence of the liquid fuel remaining in the liquid fuel system has been changed. As with a shutdown purge, there is continuous purge, followed by four (4) pulse purges. The duration of the continuous purge varies with load as follows: •

90 seconds under 25% load

•

45 seconds from 25% to 50% load

•

25 seconds from 50% to 75% load

•

15 seconds above 75% load

ACTION REQUIRED: Gas fuel line purge kits have been developed for field installation on dual fuel packages to correct the fuel migration problem. Contact your local Solar Field Service office for assistance in ordering the appropriate Retrofit Kit and to schedule its installation. The kit will be provided free of charge. The software included in the new kit also addresses and corrects the additional fuel line purge problems mentioned in this Service Bulletin. Most modifications are software changes only, but one small wiring change is required for full implementation of the modifications. The torch drain valve solenoid (L 348-3) must be electrically separated from the liquid torch valve control (L348-1) and must be connected to a separate discrete output of the PLC. In most applications, both solenoid valves are already individually wired from the control panel to the valve inside the package; but they are operated by a single common output relay in the control panel. Wiring changes are limited to separating this common control signal inside the control panel. Customers using an earlier version of this kit should obtain and incorporate the latest hardware changes and software modifications. Contact your local Solar Field Service office for assistance.

Page 4 of 5

SERVICE BULLETIN NUMBER: 3.3/106A

The retrofit kit must be installed and tested according to the installation instructions included in the kit. Failure to do so may result in severe equipment failure and /or bodily injury. Air or Nitrogen with a pressure of at least 300 PSI (20 bar) is required to test the system. The liquid drain connection at the package edge must be an atmospheric drain with no backpressure. Besides liquids (fuel, water), air and small amounts of fuel gas may get purged through this connection. Liquids and the gaseous media must be safely disposed off according to local regulations. See Service Bulletin 22.0/100 for additional information (Liquid Fuel Purge, chapter 8). The forward purge system uses customer-supplied pilot air to operate the critical high temperature ball valves. The pilot air supply must remain active during the whole package operation. After above modifications, the air-assist system is being activated for an additional 45 seconds during each turbine start and stop cycle. Customers with marginal compressed air systems might have to increase their air storage capacity or might have to shorten the recommended purge times to prevent the depletion of their air supply. See your individual fuel schematic and Mechanical Installation Instruction for shop air flow and pressure requirements.

KIT PART NO.

APPLICATION

1036817-1xx

NEC CERTIFICATION

1036817-2xx

CENELEC CERTIFICATION

SERVICE BULLETIN NUMBER: 3.3/106A

Page 5 of 5

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

5.4/116 October 1996 Mars All SoLoNox

SUBJECT: MARS SOLONOX COMBUSTOR OSCILLATIONS AND COMBUSTOR RUMBLE Type of Change:

Product Information

Recommended Compliance:

Earliest Convenience

Purpose: 1.

To inform Solar Customers of the potential for combustor oscillations and combustor rumble in Mars SoLoNox systems.

2.

To inform Solar Customers of the field retrofit kit designed to monitor combustor oscillations.

GENERAL INFORMATION: - Combustor Oscillations Mars SoLoNOx engines have occasionally exhibited an oscillation phenomena during operation. This is caused by pressure pulsations inside of the combustor. These pulsations reduce and increase fuel flow through the injectors, in turn amplifying the oscillation effect. An open bleed valve also contributes to this activity, so oscillations at part load are even more likely to occur. The oscillations, normally seen at approximately 360 Hz, can be picked up on the number three bearing proximitor probe. Extended operation of engine with excessive oscillations could result in decreased durability of combustion and other system components.

SERVICE BULLETIN NUMBER: 5.4/116

Page 1 of 2

In order to expand our database of operating unit histories, each occurrence should be properly documented. A pulsation monitor, included in kit 1006692-103, should be installed to continuously monitor and collect vibration history on the number three bearing. The monitor (Solar P/N 1006285- 1), normally mounted on the back of one of the control console doors, receives inputs from the gas producer key phasor as well as the number three bearing vertical proximitor probe. The module monitors for peaks between 320 and 380 Hz and sends a 4-20 mA output signal to a PLC analog input module. 4 mA corresponds to a 0 mil and 20 mA corresponds to 1.0 mil vibration amplitude. The latest software configuration will record a discrete event in the event log any time vibration amplitude stays above .25 mils for more than ten seconds and annunciate an alarm whenever vibration levels exceed 0.40 mils for more than ten seconds. Additionally, average and maximum hourly vibration levels and corresponding gas producer speeds will be recorded and saved as snapshot data. Solar will collect history data from the monitor at appropriate site visits. - Combustor Rumble Another rare but potential phenomena that is unique to lean burn, low emissions engines is known as combustor rumble. It is important to differentiate between combustor oscillations and combustor rumble. The rumble is a low frequency (25-35 Hz), partial flameout phenomena that occurs only when there is injector clogging or other fuel supply problems. This is usually audible in structures surrounding the equipment and sometimes from distances of several hundred feet. The condition is very serious and can quickly lead to severe engine damage. A monitoring setup for engine rumble is presently being developed and will be announced via a revision to this Service Bulletin. If this condition is observed in the field it should be reported immediately to your local Solar District Office. ACTION REQUIRED: – If the kit is not installed, order and install per kit instructions. The kit is provided free of charge. Contact your local Solar District Office for assistance. – Contact your local Solar District Office as soon as possible to report any package where alarm annunciations have occurred or previous prolonged periods of vibration are suspected. – Contact your local Solar District Office to report any instance of combustor rumble. KIT REQUIRED: Field retrofit kit number 1006692-103.

Page 2 of 2

SERVICE BULLETIN NUMBER: 5.4/116

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

5.9/103A October 1997 June 1999 All All

SUBJECT: BATTERY CHARGER ADJUSTMENTS —REVISION NOTICE— This revision replaces Service Bulletin 5.9/103. The previous issue must be removed and discarded.

Type of Change:

Product Information

Recommended Compliance:

Earliest Convenience

Purpose: To ensure your battery charger is adjusted correctly for your battery type. GENERAL INFORMATION: In several recent instances, engine bearings have been damaged after loss of AC power. The root cause was traced to improper settings on the battery charger that resulted in the battery not being charged sufficiently to perform the required backup post-lube cycle when commercial AC power was lost. When commercial AC power is lost the DC backup post-lube cycle is critical to prevent damage to engine bearings. Both 24 volt and 120 Vdc systems are affected. Battery chargers that are supplied by Solar are usually pre-adjusted for use with lead-calcium (VRLA) batteries. (A tag in the battery charger indicates the factory settings as-shipped.) In-field

SERVICE BULLETIN NUMBER: 5.9/103A

Page 1 of 3

re-adjustment of the float voltage and high-rate voltage settings are required for use with other battery types. If re-adjustment is not provided, it is possible that damage to the battery could occur due to over-charging or the battery could not be adequately charged. This could very likely result in an inability to perform the required back-up post-lube cycle when commercial AC power is lost. Both 24V and 120Vdc systems are affected, as applicable to your site. ACTION REQUIRED: The required float-voltage and high-rate-voltage settings are accomplished by adjusting appropriate multi-turn potentiometers which are on a printed-circuit card in the battery charger. See the battery charger operations manual for specific instructions. (For chargers in NEMA-3R enclosures, the manual is in a pocket on the inside of the door.) SET POINTS Unless indicated otherwise for specific sales orders, the following settings should be used. Before making these adjustments, ensure the battery charger output current is less than half the charger nameplate rating. Voltmeter used for adjustments should be accurate within ± 0.5%. Number of Cells

Float Setting

High-Rate Setting

Lead-Calcium (VRLA)

12

27.1V

27.5V

Lead-Acid

12

25.8V

28.8V

Ni-Cd

20

28.4V

31.5V

Lead-Calcium (VRLA)

60

135V

137V

Lead-Acid

60

129V

140V

Ni-Cd

96

135V

150V

Battery Type

24VDC

120VDC

Set "Float" voltage before adjusting "High Rate" voltage.

The "Current Limit" potentiometer is set at the factory and sealed. Do not change this adjustment. An improper setting may damage the rectifier. Under no circumstances should the rectifier current exceed the nameplate value. Damage may occur if misadjusted.

Page 2 of 3

SERVICE BULLETIN NUMBER: 5.9/103A

The "Float/High Rate" switch controls the "High Rate" charge. Never leave the switch in the "High Rate" position for long periods of time. Excessive "High Rate" charging will cause the battery cells to gas (through electrolysis) and dissociate the water in the electrolyte into hydrogen and oxygen. Never let the electrolyte level drop below the minimum level line.

OPERATIONS NOTE Refer to battery charger operation and maintenance manual for specific step-by-step instructions. Although the above procedure is accomplished with the battery charger operating, the following comments apply any time that it is necessary to turn the charger "ON" or "OFF": 1.

Manual turn-on of the charger should be accomplished by using the AC switch or circuit breaker. That is, the DC output circuit breaker should be closed first, then the AC switch or circuit breaker should be closed.

2.

When turning the battery charger off, the AC switch or circuit breaker should be opened first, then the DC circuit breaker may be opened.

3.

Make sure the turbine is shut down and the post-lube cycle is complete before turning off the battery charger.

SERVICE BULLETIN NUMBER: 5.9/103A

Page 3 of 3

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

6.0/123A July 1996 June 1999 MARS ALL

SUBJECT: CHANGES IN LUBE OIL PRESSURE AND TEMPERATURE TO INCREASE LUBE OIL LIFE —REVISION NOTICE— This revision replaces Service Bulletin 6.0/123. The previous issue may be removed and discarded.

Type of Change:

Product Improvement

Recommended Compliance:

Earliest Convenience

Purpose: To clarify changes recommended in operating Mars Turbine Packages. The recommended changes help to increase the turbine oil life and to avoid oil related problems: •

Inform customers about recent design changes in Mars Turbines to reduce oil oxidation.

•

Announce the widening of the acceptable lube oil temperature range to allow package operation with lower bulk oil temperatures.

•

Recommend lowered package lube oil temperatures for continuous operation.

•

Give guidelines regarding the package lube oil pressure in order to optimize oil flow to the turbine bearings.

•

Revision A: Clarify the modifications recommended on "Jordan" temperature control valves.

SERVICE BULLETIN NUMBER: 6.0/123A

Page 1 of 10

GENERAL INFORMATION: This bulletin will discuss lube oil degradation, lube oil pressure setting, lube oil temperature control settings and and provide inspection procedures. Lube Oil Degradation: In some instances Mars turbine packages have exhibited oil-related problems. These problems have been generally associated with rapid oil degradation, heavy coking of the labyrinth seal in the No. 2/3 bearing area and, in a few instances, sump oil fires. Oil degradation can lead to corrosion problems and eventual failure in the main bearings. Solar addressed these problems with design changes in the #2/3 bearing area (New Bi-Metal bearings with increased oil flow, Tungsten Carbide labyrinth seal teeth, improved seals to prevent hot air leaks past the oil supply tubes, preventing heat conduction into the bearing cap area). All new and recently overhauled Mars turbines incorporate these improvements. Oil life is directly related to oil temperature. In order to reduce the oil temperature, Solar has approved lower lube oil supply temperatures for all Mars turbines. High oil temperatures in the bearing #2/3 area and sump temperatures are being reduced by lowered supply oil temperatures, lowered heat conduction and increased bearing oil flow. Customers can further slow the lube oil degradation with simple operational changes and better thermal management in the existing lube system. Solar recommends reducing the bulk oil temperature by lowering thermostat settings and avoiding marginal oil pressures. Lube Oil Pressure: The recommended Mars package lube oil pressure is a compromise between several requirements. The oil system in a package not only supplies the Mars turbine, but also the driven equipment (generator, compressor, pump) and in some applications also a gearbox. Often, the supply pressure requirements for these items are different. Solar therefore uses the lube oil manifold pressure to specify the nominal package oil pressure range. All gauges, pressure switches and transmitters are connected to the main lube oil manifold, indicating and limiting manifold pressure. PRESSURE REQUIREMENTS: •

Mars Turbine Supply Pressure: Solar specifications require a lube oil pressure of 26 to 45 PSIG (1.8 to 3.1 bar) at the oil inlet flange of a Mars turbine. All turbine oil seals are designed for this lube oil pressure range and no internal or external oil leaks should occur during normal operation or during the post lube cycle.

Page 2 of 10

SERVICE BULLETIN NUMBER: 6.0/123A

•

Gearbox and Driven Equipment Oil Supply Pressure: Compressors and gearboxes are selected in such a way, that the individual operating oil pressure ranges coincide with the turbine lube oil pressure or at least overlap for a large part of the range.

•

Supply line restrictions: Supply lines between manifold and final equipment (turbine, compressor, and generator) are sized for minimal losses. The pressure loss is normally negligible (less than 1PSID; 0.07 bar with cool oil), but has to be considered if additional restrictions such as oil flow meters, start-up strainers or similar devices are installed. A clean start-up strainer introduces a pressure loss of about 10 PSID (0.7 bar) with cold lube oil. The pressure drop is considerably less when the oil is at its operating temperature (1 PSID, 0.07 bar).

•

Package Manifold Pressure: The nominal package operating oil pressure (design pressure) is selected to satisfy all of the above requirements. The pressure range is set at 35 ± 5 PSIG (2.4 ± 0.3 bar), measured at the manifold. All package components (turbine and driven equipment) are able to operate satisfactorily with a lube oil supply pressure inside these limits. NOTE Packages should not be operated continuously with a manifold pressure below 30 PSIG (2.1 bar). The minimum lube oil pressure of 26 PSIG (1.8 bar; instantaneous shut down) is an absolute minimum threshold and is intended to avoid a trip during relatively short system upsets.

RECOMMENDATION: Maintain the package manifold oil pressure at 35 ± 5 PSIG (2.4 ± 0.3 bar). If necessary, adjust the lube oil pressure regulator to remain within this pressure range under all operating conditions. Do not operate Mars turbine packages for extended periods with lube oil manifold pressures below 30 PSI (2.1 bar). Lube Oil Temperature: All Solar packages are designed to operate at ambient temperatures up to 140F (60C). Bearing #2/3 drain temperatures exceed 200F (93C) at those high ambient temperatures and raise the oil tank temperature. Though a certain operating oil temperature is necessary to prevent the accumulation of water in the oil (condense water etc.), extremely high oil temperatures accelerate oil oxidation and adversely affect the lube oil live: SERVICE BULLETIN NUMBER: 6.0/123A

Page 3 of 10

•

The rate of lube oil oxidation increases rapidly at temperatures above 200F (93C) and shortens the useful oil life.

•

Higher lube oil supply temperatures reduce internal turbine cooling and elevate the housing temperature in the seal area for bearings #2/3. Lube oil may get locally overheated and may carbonize. The carbon produced can act as an abrasive and can wear the edges of the labyrinth seals.

In most Solar packages, air-to-oil coolers are used to maintain the desired lube oil temperature. At low and moderate ambient temperatures, the temperature control valve (thermostat) is modulating and partially bypassing the lube oil cooler to keep the oil temperature within the recommended operating range. At high ambient temperatures, the temperature control valve is wide open and the lube oil manifold temperature starts to drift upwards. The oil cooler will now maintain a fixed air-to-oil differential temperature. MARS PACKAGE OIL TEMPERATURES: To minimize the adverse long-term effect of high oil temperatures, Solar has widened the acceptable lube oil temperature range for the Mars turbine and all Solar designed gas compressors. This allows a reduction of the operating oil temperatures by lowering the temperature control valve setpoint. The oil cooler loop opens earlier, decreasing oil temperatures. To increase the customer awareness about possible lube oil degradation at increased operating temperatures, Solar recommends to lower the "Lube-Oil-Temperature-High" alarm setting to 160F (71C) for lube oils with a viscosity grade of C32 or C46. Table 1 lists the modified alarm setpoints and recommended lube oil header temperatures. •

Newer packages are equipped with larger oil coolers and are able to maintain the lowered oil temperatures at all specified ambient temperatures.

•

Older packages can achieve lowered oil temperatures during cold and moderate ambient temperatures only, when the thermal control valve is operating and is diverting part of the lube oil flow around the cooler. The oil temperature cannot be reduced on a really hot day due to cooler limitations (all the oil is already pumped through the cooler).

RECOMMENDATION: •

Take advantage of the widened lube oil temperature range on Mars turbines and reduce the operating oil temperature of your package. Most packages use temperature control valves with fixed thermostat cartridges. The whole cartridge must be replaced in this case. On certain packages, an adjustable setpoint can be lowered on the temperature control valve (Table 1).

•

Lower the "High Lube Oil Temperature" alarm setpoint to 160F (71C) if you operate your package with C46 grade oil. Do not lower the shut down level of 180F (82C; C46 grade

Page 4 of 10

SERVICE BULLETIN NUMBER: 6.0/123A

oil only) to avoid trips on a hot day. The lowered "high lube oil temperature" alarm setting will alert you to possible oil degradation and shortened oil life.

Table 1 New and Original Mars Package Lube Oil Header Temperatures (hot engine). Lube Oil Viscosity Grade Manifold Oil Temperature

C32

C46

Original:

New:

Original:

New:

Continuous Operating Limits

130 - 165F 54 - 74C

110 - 160F 43 - 71C

150 - 180F 66 - 82C

125 - 160F 52 - 71C

Recommended Operating Range

140 - 145F 60 - 63C

120 -125F 49 - 52C

155 - 160F 68 -71C

135 - 140F 57 - 60C

High Temperature Alarm

160F 71C

160F 71C

175F 79C

160F 71C

High Temperature Shut Down

165F 74C

165F 74C

180F 82C

180F 82C

Please note that the individual site cooler performance may be insufficient to maintain lowered header temperatures at very high ambient temperatures.

ACTION REQUIRED: 1.

Verify Lube Oil Pressure: •

Maintain a lube oil manifold pressure of 35 ± 5 PSIG (2.4 ± 0.3 bar). Review your records and note the lube oil manifold pressure at different ambient temperatures and loads. Adjust the lube oil pressure regulator, if the manifold pressure falls outside these limits under certain operating condition.

•

2.

Inspect the lube oil system in your Mars package. Make sure that pressure losses between the lube oil manifold and the turbine inlet flanges are minimal. Do not run turbines in commercial operation with flow meters or start-up strainers installed. If required, increase lube oil header pressure to offset flow meter or start-up strainer pressure losses. Lower Lube Oil Operating Temperatures: Temperature control valves from several different vendors are used in Mars turbine packages and adjustment procedures differ. To lower the lube oil operating temperature, the

SERVICE BULLETIN NUMBER: 6.0/123A

Page 5 of 10

temperature control valve may require resetting or thermostat cartridges may have to be replaced. Make sure you have new cartridges and/or gaskets available before you work on any temperature control valve. Replacement cartridges and gaskets can be ordered through your normal Solar Service Parts channels. 3.

Modify Software Setpoints: Temperature setpoint changes are required for correct package operation with lowered lube oil temperatures. (See also Service Bulletin 6.0/116A): •

If C46 grade lube oil is used, lower the "high lube oil temperature alarm" setpoint to 160F (71C).

•

On packages with electric cooler fans, lower the lube oil cooler fan “on-off” setpoints if C32 grade oil is used. The old setpoints (120F; 49C “on”, 100F; 38C “off”) must be reduced to 100F (38C) “on” and 80F (27C) “off”. For C46 oil the cooler fan setpoints can be left at 120F “on” and 100F “off”.

•

Mars turbines built after January 1994 use a tilting pad thrust bearing in the gas producer rotor. Packages using those turbines require additional software changes. The logic introduced in Service Bulletin 8.9/104 must be modified: Lower the minimum threshold temperature for activation of the thrust bearing differential temperature protection. Change the threshold temperature from 130F (54C) to 110F (43C) for C32 oil and to 125F (52C) for C46 oil. The alarm and shut down values for the thrust bearing absolute and differential temperatures do not change with the introduction of lowered lube oil temperatures.

The minimum oil temperature required for package start-up and the maximum acceptable oil temperatures are not affected by above changes. The setpoints for “start permissive” and high temperature “alarm” and “shut down” should not be changed except where noted. 4.

Modify Temperature Control Valves (if required): a.

“Jordan”temperature control valve. Two different types of “Jordan“ temperature control valves were used in Mars Turbine Packages. Valve modifications or a complete exchange are required to stabilize the operation of these valves.

Page 6 of 10

SERVICE BULLETIN NUMBER: 6.0/123A

Procedure: •

Two-way valve P/N 120458 This valve is plumbed in parallel to the cooler (bypass valve) and controls the manifold temperature. The valve uses an external temperature sensor installed in the lube oil manifold. To reduce the manifold temperature, simply lower the temperature setpoint until you reach the desired manifold temperature. Valves variations with and without manual temperature control override exist in the field. Both valves operate identically. The basic valve is designed to maintain very tight temperature limits. In Solar’s application as lube oil temperature control valve, tight control is not required. Valves P/N 120458-2 to -17 have too little "droop" and are unstable. These valves require modifications before satisfactory operation is achieved. Order retrofit kit P/N 120458-30. The kit includes a new control head and a stiffer spring together with the necessary instructions and is suitable for valves with and without manual override. The modified valves should be re-identified with new part numbers: P/N 120458-20 (valve without manual override) P/N 120458-21 (valve includes a manual override).

•

Three-way "Jordan" valve P/N 190976 Very few packages were equipped with these valves. Valves cannot be modified in the field and were replaced in all known applications. Order retrofit kit P/N 1018296KI00B if your package still contains a 3-way "Jordan" valve. The kit includes a new "Robertshaw" valve and all necessary hardware for a "drop-in" replacement. The 3-way "Robertshaw" valve included in the kit is P/N 120713-16 and has an operating range of 136 - 152F (58 - 67C). The valve controls the tank temperature and not the manifold temperature and is acceptable for most cases (See "Robertshaw" valve below).

b.

"Robertshaw" temperature control valve P/N 120713. Though this is a 3-way valve, Solar plumbs the valve in parallel to the cooler and uses it as a 2-way valve. The valve acts as a "diverter" valve, bypassing lube oil around the cooler as long as the oil tank temperature is low. The temperature sensing cartridge inside the valve points towards the oil inlet (from the pump) and controls the supply temperature. This temperature is essentially the lube oil tank temperature and is about 25 to 30F (14 to 17 C) above the manifold temperature. The valve starts to restrict the cooler bypass flow when the oil temperature reaches the valve operating range (147 -160F; 64 - 71C in older packages using C32 oil). At oil tank temperatures above 160F (71C), the valve is closed and the oncoming

SERVICE BULLETIN NUMBER: 6.0/123A

Page 7 of 10

oil is forced to flow through the cooler. No fixed manifold temperature is maintained, since the control valve stabilizes the tank temperature and not the manifold temperature. Procedure:

Page 8 of 10

•

Review your records and record the lube oil manifold temperature at low and moderate ambient temperatures during part and at full load operation. Under these conditions, the temperature control valve is modulating and stabilizes the tank temperature. If the recorded lube oil manifold temperatures are considerably above the new "Recommended Operating Range" (Table 1), a new control valve cartridge (poppet) should be installed:

•

Determine the maximum permitted oil temperature decrease by calculating the difference between the lowest manifold temperature (observed in the previous step) and the lower number of the "Recommended Operating Range" (Table 1). This is the "optimum temperature decrease".

•

Determine your control valve part number from the actual part or from the lube oil schematic.

•

Consult Table 2 and read the nominal "valve operating range" for your particular valve. Please note that this valve controls the tank temperature and not the manifold temperature.

•

Subtract the calculated "optimum temperature decrease" from the nominal "valve operating range" found in the previous step. This is the new "ideal lube oil tank temperature operating range".

•

Consult Table 2 and select the nearest "Replacement Temperature Element" above the "ideal lube oil tank temperature operating range" determined in the previous step. This temperature element is the best compromise possible. Order this element set.

•

Replace element set. See Operation and Service Manual under Vendor information.

SERVICE BULLETIN NUMBER: 6.0/123A

Table 2 "Robertshaw" Lube Oil Temperature Control Valve (P/N 120713) Valve Operating Range

c.

Solar Part Number:

C

F

Complete Replacement Valve

Replacement Temperature Element

58 - 67

136 - 152

120713-16

120713-32

64 - 71

147 - 160

120713-5

120713-30

71 - 79

160 - 175

120713-6

120713-31

67 - 74

152 - 166

N/A

120713-33

Early Mars packages: Early Mars packages use a lube oil block which incorporates five thermostat cartridges. The cartridge valves operate similar to the "Robertshaw" valve discussed above, but the individual cartridges are externally accessible and can be exchanged. Again, no clear manifold temperature can be given due to the fact that the tank temperature is controlled and not the manifold temperature. NOTE

The cartridge valves actually perform a double duty, being combined thermostat / differential pressure valves. The cartridge valves will also open, if the pressure drop across the cooler exceeds 50 PSID (3.5 bar d).

Procedure:

SERVICE BULLETIN NUMBER: 6.0/123A

•

Determine the correct temperature range of your replacement cartridges from Table 3. Use a similar procedure as described under the "Robertshaw" valves.

•

Order five new cartridges per package and replace existing valves. All replacement cartridges are supplied with new o-rings.

Page 9 of 10

Table 3 Early Mars Temperature Control Cartridge Valves Temperature Range (start to close to fully closed)

d.

Solar Part Numbers:

C

F

Cartridge

27-49

80-120

120391-1

38-60

100-140

120391-2

49-71

120-160

120391-3

60-85

140-185

120391-4

"Amot"valve P/N 120337. Newer Mars packages use an "Amot" valve for lube oil temperature regulation (Solar P/N 120337). This is a true 3-way valve controlling the lube oil manifold temperature. The sensing cartridges (thermostats) are installed in the outlet port of the valve. As long as the control valve is modulating, the manifold temperature remains within the operating range listed in Table 4. The table can be used directly to order replacement cartridges. Each element kit contains all the hardware required to modify one valve.

Table 4 "AMOT" Temperature Control Valves Operating Temperature Range

Maximum Continuous Manifold Temperature

Solar Part Number:

F

C

F

C

Complete Valve

Temperature Element Kit

135 - 151

57 - 66

165

74

120337-1

120337-30

124 - 140

51 - 60

180

82

120337-3

120337-31

110 - 131

43 - 55

165

74

120337-15

120337-32

Please note the maximum temperature limits of the Amot elements. If observed summertime manifold temperatures exceed these values; the temperature elements will be permanently damaged. For C46 grade oil, temperature control valve P/N120337-3 or element kit P/N 120337-31 must be used.

Page 10 of 10

SERVICE BULLETIN NUMBER: 6.0/123A

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

6.5/107 June 1997 All All

SUBJECT: POST LUBE REQUIREMENTS AFTER ENGINE SHUTDOWN Type of Change:

Product Information

Recommended Compliance:

Information

Purpose: To provide information to customers on post lube oil requirements for the engine bearings. This service bulletin emphasizes the importance of the post lube oil in protecting the engine after shutdown. GENERAL INFORMATION: Solar Turbines packages are equipped with a primary post lube oil system to protect the engine bearings from damage due to heat soak from hot internal engine components. Depending upon the type of engine and application, many packages are also equipped with a backup post lube oil system. The primary post lube oil pump is usually driven by either an A.C. power or pneumatic motor. The backup post lube oil pump is usually driven by a D.C. motor. After engine shutdown, the post lube oil is automatically supplied by the primary post lube system. In the event of the failure of the primary system, the post lube is supplied by the D.C. backup; if installed on the package. In most cases, the post lube systems on Solar packages have been adequate and have worked properly in protecting the engine bearings after engine shutdown. However, there have been some engine failures because the primary post lube and it’s backup system did not operate after the engine shutdown.

SERVICE BULLETIN NUMBER: 6.5/107

Page 1 of 3

The following defines post lube requirements for current production engines: Mars 90, 100, and Taurus 70 Engines (SoLoNOx and Non-SoLoNOx) A post lube cycle is initiated after any gas turbine shutdown, other than fire emergency, where the gas producer has exceeded 65% (Ngp) of rated speed. For new engines built in 1997, post lube is required when the engine has achieved light off (T5 average ò 400F). The post lube cycle allows lube oil to continue to be pumped though the gas turbine bearings to remove the residual heat build up in the bearing areas. The turbine can be started any time during the 4 hour post lube cycle. The post lube cycle consists of the following: 1.

A minimum four hour cycle. The post lube cycle must be completed even if it is interrupted by an aborted start or test crank. The cycle may be continuous or consist of a continuous one hour cycle followed by a three hour intermittent cycle of 2.5 minutes post lube on and 9.5 minutes post lube off. Many Mars units in the field have a three hour intermittent cycle of 2.5 minutes post lube on and 12.5 minutes lube off.

2.

The minimum lube oil header pressure allowed for the post lube cycle is 8 psig, maximum pressure allowed is 25 psig.

Saturn 10, 20, Centaur 40, 50, Taurus 60, (SoLoNOx and Non- SoLoNOx) A post lube cycle is initiated after any gas turbine shutdown, other than fire emergency, where the gas producer has exceeded 65% (Ngp) of rated speed. For new engines built in 1997, post lube is required when the engine has achieved light off (T5 average ≥ 400F). The post lube cycle allows lube oil to continue to be pumped though the gas turbine bearings to remove the residual heat build up in the bearing areas. The turbine can be started any time during the 55 minutes post lube cycle. The post lube cycle consists of the following: 1.

A minimum 55 minutes continuous cycle. The post lube must be completed even if it is interrupted by an aborted start or test crank. Many Saturn 10 units in the field have 30 minutes continuous post lube cycle.

2.

A minimum lube oil header pressure allowed for the post lube cycle is 6 psig, maximum pressure allowed is 25 psig.

Post Lube in the Event of Fire or Plant Emergency Shut Down (for all Engines) If the engine is shutdown due to fire, the engine shall continue to be lubricated until the run down timer is done. The post lube shall then be postponed for a maximum time of 20 minutes. The post lube can be started any time during this period by acknowledging and resetting the alarm. After the 20 minutes timer is done, the control shall initiate the post lube. If a post lube is still not desired, a manual intervention is required to stop the post lube. If a hot engine has been without post lube for longer than 20 minutes, the engine bearings may require inspection. Page 2 of 3

SERVICE BULLETIN NUMBER: 6.5/107

ACTION REQUIRED: 1.

Review the post lube system installed on your package to check that the engine bearings are properly protected after any engine shutdown.

2.

The post lube requirements discussed in this service bulletin may not be specific to your package. If you have questions or need field service assistance, contact the Solar field service representative in your area.

SERVICE BULLETIN NUMBER: 6.5/107

Page 3 of 3

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mars, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

6.5/108B April 1998 March 1999 Mars All Turbotronics Controls Systems

SUBJECT: BACKUP POST LUBRICATION CONTROL SYSTEM ENHANCEMENTS Type of Change:

Product Reliability

Recommended Compliance:

Next Maintenance

Purpose: To announce the availability of backup post lubrication control system enhancements designed to increase the reliability of the backup lube oil supply system. NOTE The intent of this Service Bulletin is to improve product reliability to safeguard our customer’s equipment in the event of a shutdown. The information in this Service Bulletin implements enhancements to assure the post lube oil pump operates for the full post lube cycle. There may be facility related circumstances which necessitate the site operator to interrupt the post lube cycle. These site related circumstances should be considered when incorporating the backup postlube enhancements contained in this document.

GENERAL INFORMATION: Solar Turbines Mars packages are equipped with an auxiliary pre-post lube oil system to lubricate the bearings before start-up and to protect the engine bearings from damage after a shut down due to heat soak from hot internal engine components. The auxiliary post lube oil pump is usually driven

SERVICE BULLETIN NUMBER: 6.5/108B

Page 1 of 3

by an A.C. motor. The backup post lube oil pump is driven by a D.C. motor, VFD/AC motor or pneumatic motor.

POST LUBRICATION OF A HOT TURBINE IS CRITICAL TO PREVENT BEARING DAMAGE. LUBE OIL FLOW DURING EQUIPMENT ROLL-DOWN IS ESSENTIAL.

During and after engine shutdown, the post lube oil is automatically supplied by the auxiliary post lube system. In the event of the failure of the auxiliary system, the post lube is supplied by the backup system. In most cases, the post lube systems on Solar packages have been adequate and have worked properly in protecting the engine bearings after engine shutdown. However, there have been some recent engine failures which occurred when A.C. power was lost and the D.C.or pneumatic backup system failed to operate after the engine shutdown. Packages with electrically driven main lube oil pumps appear to be the most susceptible to this type of failure. Investigation of the failures has led to several control system enhancements and new recommended maintenance procedures. The first recommendation was communicated in Service Bulletin 5.9/103, "Battery Charger Adjustments" released October 1997. The second recommendation "suggested annual battery maintenance and testing of backup lube system" was communicated as Service Bulletin 6.5/109, released June 1998. The third recommendation communicated by this bulletin is to incorporate controls modifications to improve and periodically test the operation of the backup post lube pump and to lockout the turbine upon loss of post lubrication as defined in this Service Bulletin. Solar has developed a retrofit kit #1028812-1XX that is designed to perform several functions that will increase the dependability of the backup post lube system. Logic change recommendations included in the kit are tailored for Turbotronics 2.0 and 3.0 control systems, but the hardware and generic instructions can also be used to modify older packages in similar ways. The key features of the kit are: – Modifications of the P.L.C. logic to perform a backup lube pump check every 24 hours. NOTE Daily use of this check may not be practical for pneumatic backup lube system due to fugitive emission issues. Solar recommends that this check be done as often as is practical subject to site condition requirements.

– Incorporation of a "fail-safe" DC backup pump relay which activates the emergency lube pump when the 24 Vdc control power fails.

Page 2 of 3

SERVICE BULLETIN NUMBER: 6.5/108B

– Additional logic to inhibit Mars engine restart for 12 hours or until a complete four-hours post lube cycle has been completed, if post lube is interrupted for more than 20 minutes. – An increase in the rundown timer from 3 to 20 minutes. Solar control systems are designed for uninterrupted power supplies. If the PLC fails or the 24 Vdc control power is interrupted, the logic changes recommended in the above kit will correctly activate the backup pump ( 120 Vdc must be available if back up lube is DC operated).

THE D.C. PUMP MIGHT STOP AND POSTLUBE MIGHT BE INTERRUPTED IF THE NORMAL CONTROL SYSTEM IS RE-ACTIVATED DURING EMERGENCY POSTLUBE. MANUALLY INITIATE POSTLUBE IN THIS CASE.

ACTION REQUIRED: Order retrofit kit #1028812-1XX (at no charge) from your Solar Service Parts representative. It is recommended that Solar Field Service personnel perform the installation of the kit. The installation of the kit involves modification of control system logic, electrical wiring modification, piping modification and system verification. Please contact your local Solar District Field Service office for assistance.

SERVICE BULLETIN NUMBER: 6.5/108B

Page 3 of 3

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

6.5/109A June 1998 June 1999 All All

SUBJECT: PERIODIC BATTERY MAINTENANCE AND TESTING OF BACKUP LUBE SYSTEM —REVISION NOTICE— This revision replaces Service Bulletin 6.5/109. The previous issue may be removed and discarded.

Type of Change:

Product Reliability

Recommended Compliance:

Next Maintenance

Purpose: To provide a recommended procedure for a monthly inspection of the battery system, semi-annual battery maintenance and annual operational check of the backup lube system to ensure that these systems are operating properly and are capable of providing the full lube cycle. GENERAL INFORMATION: In recent instances, engine bearings have been damaged after loss of ac power. In some of these situations, the cause was traced to improper settings on the battery chargers. This issue has been addressed by Service Bulletin 5.9/103A. A procedure has also been implemented to perform brief daily tests on the backup lube system operation on Mars and Taurus 70 packages. These package modifications are addressed by Service Bulletin 6.5/108B.

SERVICE BULLETIN NUMBER: 6.5/109A

Page 1 of 7

This Service Bulletin outlines the procedure to periodically operate the backup lube system through a battery test period. As a part of this procedure, it is important to also perform monthly battery inspections and semi-annual maintenance on the battery assemblies. Although this bulletin addresses turbine packages with a dc backup lube system, the same procedure should be used for packages that have a pneumatic backup lube system. ACTION REQUIRED: Monthly Battery Inspection A visual inspection of the battery should be performed at least once per month. This will aid in assuring the battery system is capable of satisfying its design requirements.

Remember that the battery is electrically live at all times and cannot be isolated in the conventional sense, although the voltage at any point can be reduced by the removal of the appropriate inter-unit connectors. Take care that short circuits are not caused by accidentally dropping or touching metal objects onto the cellblock terminals. When working with batteries, always wear the proper protective equipment.

PROCEDURE: 1.

Check general appearance and cleanliness of the battery rack and battery rack area. Inspect the battery rack for stability and signs of corrosion. Clean as required. Check that all bolts are properly tightened.

2.

Check general appearance and cleanliness of the battery. Check battery cellblocks for cracks or leakage of electrolyte. Clean as required. (Do not use solvents on battery cells. See manufacturer’s instructions for maintenance procedures.)

3.

Where applicable, visually check the electrolyte level of all battery cells. If required, add distilled or de-ionized water to bring the electrolyte up to the desired level.

4.

Visually confirm that all battery connections are in place.

5.

Check general appearance and cleanliness of the battery charger. Check the float voltage on the charger voltmeter. Confirm this reading corresponds to the voltage given in Service Bulletin 5.9/103A: Battery Charger Adjustments, for the appropriate battery type.

6.

Record and retain data for future reference.

Page 2 of 7

SERVICE BULLETIN NUMBER: 6.5/109A

Semi-Annual Battery Maintenance For the semi-annual battery maintenance, it is necessary for the battery to be in a passive conditionneither being charged nor discharged. This requires that the turbine is stopped, post-lube cycle completed, and the control system shut down. The battery chargers must be turned off, and if there are battery circuit breakers they should be opened.

Prior to start of work, follow proper lock out and tagging procedures to isolate hazardous energy sources. Read the battery manufacturer’s Material Safety Data Sheet and understand the hazards associated with handling or working with the battery electrolyte / acid. Batteries generate Hydrogen Gas that is highly flammable. To avoid risk of fire and explosion, keep sparks or other sources of ignition away from batteries.

Nickel Cadmium Battery - the alkaline electrolyte is a strong caustic agent. Contact with electrolyte solution causes very rapid, severe damage to human tissue. It is also extremely corrosive to eye tissue. May cause serious burns to the skin. Do not inhale or ingest.

Lead Acid Battery - the sulfuric acid is a strong corrosive agent that can burn the skin, eyes, and respiratory system. Do not inhale or ingest.

When working with batteries, always wear the proper protective equipment including, but not limited to, protective rubber gloves, chemical goggles or full-face shield, rubber boots, rubber apron, and long sleeved clothing. Remove all jewelry such as watches, rings, bracelets, or other metal jewelry. Use only insulated tools.

SERVICE BULLETIN NUMBER: 6.5/109A

Page 3 of 7

Never work on 120V batteries alone unless the high voltage danger is minimized by first removing an inter-cell (inter-row) cable so that the battery assembly temporarily consists of two 60V sub-assemblies. Be certain that all loads are first disconnected and be certain that the battery charger is turned off at both its ac input and dc output.

PROCEDURE: 1.

Perform steps 1 through 5 in the Monthly Battery Inspection section above.

2.

Measure the overall voltage of the complete battery assembly (or of the two 60-volt sub-assemblies). Also measure the voltage of individual cells (or of multi-cell blocks if individual cells cannot be measured). Record these measurements for future reference.

3.

3. If the voltage of one or more cells is noticeably lower than for other cells, it is advisable to measure the specific gravity of all cells (excepting "sealed" cells). Low specific gravity for a lead-acid cell usually indicates that the cell is not charged. The specific gravity of nickel-cadmium cells does not change with charge-discharge conditions. Refer to manufacturer’s electrolyte instructions for appropriate specific gravity readings.

Never permit a hydrometer to be used for both lead-acid and Ni-Cd cells, as the inadvertent mixing of even a small amount of electrolyte between the battery types can cause failure of the batteries! If there are discrepancies in the voltages and/or the specific gravities of a few cells, it is advisable to further examine these cells for deformation of the case, deformation or discoloration of the internal plates, excessive shedding or flaking at the plates, electrolyte leakage at the terminal posts, etc., as this may be an indication of impending cell failure.

If a single lead-acid cell, or up to three Ni-Cd cells, are questionable in a 120V assembly, they may be temporarily disconnected and bypassed with a suitable jumper cable. However, the battery charger must be re-adjusted to compensate for cell removal. Similarly, one Ni-Cd cell may be removed from a 24V assembly if necessary. 4.

Page 4 of 7

If the battery checks indicate that the battery is within acceptable tolerances, then re-connect the cable that may have been used to isolate the two sections of the 120V battery. Re-coat the battery terminal connections with no-oxide grease, but do not allow grease to get onto plastic components on the cell covers. For automotive/truck batteries SERVICE BULLETIN NUMBER: 6.5/109A

(which are usually in 12-volt block arrays), a petroleum jelly such as Vaseline may be used. 5.

If the annual tests of the dc or pneumatic backup post-lube motor are to be performed right away, then proceed to the next section of this service bulletin. If the backup lube motor tests are not going to be performed at this time, then re-close the battery circuit breakers if applicable, and turn on the battery chargers. Verify that the battery chargers are operating satisfactorily.

6.

Record and retain data for future reference.

Annual Post-Lube System Tests Verify the integrity of the dc backup lube system and the available battery capacity at least once per year. With the engine shut down and the post-lube timer timed-out, lock-out the normal post-lube pump and operate the backup dc lube oil system for 90 minutes on Mars, Titan and Taurus 70 turbines, 55 minutes on Centaur and Taurus 60 turbines and 30 minutes on Saturn turbines. Monitor system operation and battery voltage during this time. Preliminary Conditions - Batteries should be fully charged prior to performing these tests. Per battery manufacturers’ definitions, this requires that the batteries be on float charge for a minimum 72-hour continuous period with no loads which exceed the battery charger output current capabilities. (If there were no loads on the system at the end of the charge period, the battery charger output current would be less than two amps.) PROCEDURE: 1.

Select a suitable test time when the engine is not used for eight hours and the station is manned for the first two hours. Make sure that batteries are fully charged as described above. Complete Semi-Annual Battery Maintenance procedure as described above.

2.

Hook up a voltmeter or a strip chart recorder to the battery terminals. Do not continue test if battery voltage does not correspond to the voltages given in Service Bulletin 5.9/103A: Battery Charger Adjustments.

3.

Install a dc clamp-on ammeter into the dc motor supply lines and monitor the motor current. Some systems have a shunt installed in the motor supply lines to facilitate this reading.

4.

Turn off battery charger.

5.

Activate backup dc lube oil pump. Run the pump for a continuous period as noted in the table below.

6.

Monitor lube oil header pressure. The post-lube pressure must be at a minimum as listed in the table below at all times. If this minimum pressure cannot be maintained, interrupt test and correct system.

SERVICE BULLETIN NUMBER: 6.5/109A

Page 5 of 7

7.

The lube oil header pressure is not allowed to exceed the maximum listed in the following table. Finish the test in this case and correct afterwards (see Service Bulletin 6.5/105 for orifice in lube oil line). Minimum Pressure

Maximum Pressure

Pump Test Time

Saturn 10/20

4 psig

25 psig

30 min.

Centaur 40/50

4 psig

25 psig

55 min.

Taurus 60

4 psig

25 psig

55 min.

Taurus 70

4 psig

25 psig

90 min.

Mars 90/100

8 psig

18 psig

90 min.

Titan 130

8 psig

18 psig

90 min.

Turbine

8.

Monitor the backup dc motor current. The current should not exceed the dc motor nameplate reading regardless of lube oil temperature.

9.

Check dc motor starter contactor and its thermal overload setting. The motor should not be allowed to trip. Give ample margin when setting the thermal overload. Remember that this is an emergency lube oil pump and you are trying to protect the whole turbine and not just the electric dc motor.

10.

Monitor lube oil temperature and the corresponding dc motor current draw. Compare with records about normal post-lube temperatures in summer and winter. The relationship may require higher thermal overload settings for extreme winter operation.

11.

Measure and record the battery voltage shortly after starting the post-lube cycle, before it is completed and after the completion of this test. These readings give important information about the health and capacity of your battery system. Correct system and/or replace batteries if problems are found. (In some cases a battery problem may be caused by errors in battery charger settings, low battery electrolyte levels in one or more cells, or inadequate torque on battery terminals or downstream electrical connections). Minimum Acceptable Battery Voltages: 24V Battery

120V Battery

Pump running: 20.8 Vdc

Pump running: 104 Vdc

After pump stops: 22.8 Vdc

After pump stops: 114 Vdc

Do not permit a 24V battery to operate below 19.2 Vdc. Do not permit a 120V battery to operate below 96 Vdc.

Page 6 of 7

SERVICE BULLETIN NUMBER: 6.5/109A

12.

After the completion of the backup post-lube test restore normal pre/post-lube system and re-activate battery charger. Let batteries re-charge for a minimum of six (6) hours. By observing the dc ammeter on the battery charger, confirm the battery is being charged.

13.

Put engine back into service. Record and retain data for future reference.

SERVICE BULLETIN NUMBER: 6.5/109A

Page 7 of 7

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

6.6/102 March 1992 Mars All Units with pneumatic backup lube oil pump

SUBJECT: MARS PNEUMATIC BACKUP LUBE OIL PUMP REPLACEMENT Type of Change:

Product Information

Recommended Compliance:

Information

Purpose: To announce the availability of new pneumatic motor (Solar Part Number 186998-1) and pump assembly (P/N 190234-100). GENERAL INFORMATION: The pump/pneumatic motor P/N 120520-3 has been discontinued and replaced by pneumatic motor, P/N 186998-1 and pump assembly, P/N 190234-100. Minor system alterations are required as specified in the retrofit kit, P/N 179821K100. Performance of the new motor/pump assembly is the same as the replaced assembly. ACTION REQUIRED: When replacement of the pneumatic motor, P/N 120520-3 is required, order the replacement retrofit kit, P/N 179821K100. The kit includes all necessary instructions for removal of the replaced assembly, all the necessary parts, and the installation procedure for the new pump and motor assembly.

SERVICE BULLETIN NUMBER: 6.6/102

Page 1 of 1

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

8.6/107 February 2000 Mars 90 and Mars 100 All

SUBJECT: VARIABLE STATOR VANE LOCKUP Type of Change:

Product Information

Recommended Compliance:

Earliest Convenience

Purpose: This Service Bulletin alerts the field that variable stator vanes can lockup, a condition that potentially could lead to engine failure. GENERAL INFORMATION: There have been reports of compressor failures related to variable stator vane lockup. Lockup can be caused by excessive rust buildup that bonds the stator shafts to the housing bushings (see Figure 1). Additionally, contamination from particulates can build up and cause the vanes to lockup. When individual vanes in a stator row are locked in a fixed position or become stiff (limited rotation), these vanes could be out of position with the remaining vanes in that row. This could disrupt airflow through the compressor and create localized areas of turbulent air. As the compressor blades rotate through this turbulent air, abnormally large dynamic forces are applied to the blades. These forces may result in fatigue failure of the compressor blades.

SERVICE BULLETIN NUMBER: 8.6/107

Page 1 of 3

Figure 1 Vane Stem, Bushing and Case Rust

ACTION REQUIRED: Proper maintenance is important to ensure proper turbine operation and prevent unscheduled downtime. The following recommendations should be part of the maintenance program to ensure proper turbine operation and longevity. •

Engines should be visually inspected periodically for signs of contamination (rust, excessive sand, dirt or bent stator arms) in and around the variable stator vanes and associated hardware. Engines, which operate in corrosive environments e.g. off shore, should be inspected more frequently.

•

Units that have been shut down for an extended period time or show signs of corrosion should have each stage of variable stators rotated by hand to verify freedom of movement before operation. NOTE Under no circumstances, should an engine be operated with seized stators. Rust or particular buildup must be removed from around the guide vanes prior to continued engine operation. If assistance is required to remove contamination or to repair a bent stator arm contract the local Solar district office.

Page 2 of 3

SERVICE BULLETIN NUMBER: 8.6/107

•

To minimize ingestion of contaminants, the air inlet system should be visually inspected for leaks and the air filter delta P should be recorded and monitored.

In addition to the maintenance checks, the following are documents that provide information relevant to proper stator vane operation. •

Engineering Specification (ES) 9-62 verifying the proper fluids and procedures for ingestive cleaning are being met (especially run time after water wash).

•

ES 1565 (section 4.1) verifying that all air filter requirements for the Mars engine are being met.

•

Service Bulletin 8.6/106 provides information to set up and adjust the Inlet Guide Vane (IGV) and variable stators to an optimum schedule.

To obtain a copy of the Service Bulletin or the Engineering Specifications referenced in this Service Bulletin please contact the local Solar district office.

SERVICE BULLETIN NUMBER: 8.6/107

Page 3 of 3

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

8.8/108B November 1998 June 2000 Mars 90S, Mars 100S All Mars SoLoNOx “Gas Fuel Only” Applications

SUBJECT: FUEL INJECTOR BLEED HOSE FAILURES AND CASE BLEED DUCT FAILURES PRODUCT SAFETY

—REVISION NOTICE— This revision replaces Service Bulletin 8.8/108A and announces updated retrofit kits and a separate kit providing a new more durable 6" bleed duct replacing the previous 4" bleed duct.

Type of Change:

Personnel Safety

Recommended Compliance:

Mandatory

Purpose: The purpose of this Service Bulletin is to announce the availability of an updated retrofit kit to change Mars SoLoNOx engines from the injector bleed system to a case bleed system. This change eliminates the injector bleed hose and therefore eliminates a safety hazard first describe in Product Advisory 8.8/108A released August 1997. This bulletin also announces durability improvements to the case bleed system, available both in the updated kits and as a separate retrofit kit. Included in these improvements is a 6" bleed duct configuration that replaces the 4" duct originally provided with the case bleed system that had experienced some premature failures.

SERVICE BULLETIN NUMBER: 8.8/108B

Page 1 of 8

GENERAL INFORMATION:

FAILURE TO TAKE CORRECTIVE ACTION COULD RESULT IN DAMAGE TO PROPERTY AND SERIOUS BODILY INJURY OR DEATH.

THIS WARNING IS STILL IN EFFECT UNTIL YOUR PACKAGE HAS COMPLETED THE RETROFIT TO CASE BLEED CONFIGURED WITH THE 6" BLEED DUCT. DURING OPERATION, PERSONNEL SHOULD REMAIN OUTSIDE OF ANY ENCLOSED PACKAGE, AND WELL AWAY FROM THE BLEED MANIFOLD AREA OF UNENCLOSED MARS SOLONOX PACKAGES. (See Figures 1 and 2)

Background Information: Since December 1995, four Mars SoLoNOx injector bleed hoses have ruptured during operation. These failures caused a significant discharge of high temperature, high-pressure air near the engine, and discharged metal debris from the hose. In one instance, fire was reported exiting the failed injector hose. In each of these cases, the extent of damage was minor and no personnel have been injured. Although only four incidents of bleed hose failures have been reported a hose rupture presents a potential serious personnel safety concern. The aforementioned incidents led to the introduction of the case bleed system described below. Most of the operating fleet has been retrofitted with the system. Subsequently, reports of bleed duct failures at several sites configured with case bleed have been received. Packages operating for extended periods at part load/high bleed conditions appear to be the most susceptible. Damage from 4" bleed duct failures have varied from hot Pcd bleed air leakage into the surrounding areas to full separation and rupture of the hose, creating a serious potential safety issue. General Information: Solar has developed an alternative method for removing bleed air from the combustor in order to maintain control over emissions during part load operation. This is achieved by bleeding air directly from the combustor case, similar to the design of 2-shaft Centaur and Taurus 60 SoLoNOx engines. This system can be easily retrofitted onto existing Mars engines by removing the injector manifold bleed system, and replacing it with a single port case bleed. This new bleed system was incorporated in new production engines and overhaul engines beginning in August 1998. The case bleed retrofit requires removing the injector bleed hoses from each injector, removing the bleed manifold, 6" bleed valve and ducting. A 3" combustor bleed port is available on the right side of the engine (aft looking forward) and a 90-elbow 3" to 4" adapter piece is attached to this port. A new 4" bleed valve is mounted to the flange and a new 6" flexible duct is then attached to Page 2 of 8

SERVICE BULLETIN NUMBER: 8.8/108B

the exhaust collector at the location of the 4" port. A new bleed diverter must also be installed in the collector. The diverter requires cutting and welding to install and is necessary to prevent high velocity air from impinging on the exhaust collector aft panel. Installation instructions are included in the retrofit kit. The only skid modification required is the re-routing of the electric and hydraulic control for the new bleed valve. Minor software changes are required to the bleed valve schedule for surge avoidance during startup, and the T5 setpoints for part load emissions control should be verified, although experience to date has shown they will rarely need to be adjusted.

Figure 1 Typical Unenclosed Mars SoLoNOx Package

As indicated above, the latest version of the case bleed retrofit kit incorporates the change from a 4" bleed duct to a 6" bleed duct to address durability and safety concerns. No physical changes are required on the fuel injectors, other than removing the flexible bleed ducting, and installing a cap on the injector bleed flange. This cap is secured in place with the same clamp that was used to hold the flexible ducting.

SERVICE BULLETIN NUMBER: 8.8/108B

Page 3 of 8

Figure 2 Main Area of Concern

ACTION REQUIRED: I. Units configured with Injector Bleed System. Contact your local Solar Field Service office for assistance in ordering the appropriate Retrofit Kits (provided at no charge), and to schedule the case bleed modification. See Figures 3, 4, and 5 to aid in selection of appropriate kits. For each package order: 1.

one Actuator kit (1032269-1XX) for units with ‘Tactair’ actuator or (1032269-2XX) for units with ’Moog’ actuator. (Figure 3)

2.

one Package kit (1032271-1XX). (Figure 4)

3.

one 6" Bleed Duct and Diverter kit (1042502-XXX). (Figure 5) NOTE The following actions (A, B, and C) are still in effect until your package has completed the retrofit to case bleed. These modifications were announced in Service Bulletin 8.8/108A in June of 1999.

Page 4 of 8

SERVICE BULLETIN NUMBER: 8.8/108B

UNTIL YOUR PACKAGE HAS COMPLETED THE RETROFIT TO CASE BLEED, DURING OPERATION, PERSONNEL SHOULD REMAIN OUTSIDE OF ANY ENCLOSED PACKAGE, AND WELL AWAY FROM THE AIR MANIFOLD AREA OF UNENCLOSED MARS SOLONOX PACKAGES. (See Figures 1 and 2) A.

A retrofit kit has been developed for installation on the bleed manifold to allow for detection of fuel within the bleed system. The kit, P/N 1025052-100, includes tube, ball valve, clamps, brackets, and all necessary components to install on your package. The kit is designed for use with Customer supplied gas monitors or other detection system. Detection of 2% of Lower Explosive Limit (L.E.L.) indicates a potential injector fuel tube leak and requires an immediate shutdown of the engine for further investigation. At that time fuel injectors should be inspected immediately and replaced as required. Contact your local Solar District Field Service office for assistance. Order kit P/N 1025052-100 from Solar Service Parts. The kit will be provided at no charge.

B.

Solar is available to perform an inspection of your fuel injectors. Please contact your local Solar District Field Service office to schedule injector inspection.

C.

Solar has completed a design for a rigid bleed system cover, initially intended to replace existing insulation blankets on bleed system components. When installed, this cover would also significantly minimize the potential for injury in event of a hose rupture. Please contact your local Solar District Field Service office for information.

II. Units already configured with the case bleed system and with the original 4" bleed duct. Contact your local Solar Field Service office for assistance in ordering the appropriate Retrofit Kit (provided at no charge). For each package order one 6" Bleed Duct and Diverter Kit (1042502XXX). See figure 5 to select the appropriate kit.

SERVICE BULLETIN NUMBER: 8.8/108B

Page 5 of 8

Figure 3 Mars Case Bleed Selection Guide - Actuator Kits

Page 6 of 8

SERVICE BULLETIN NUMBER: 8.8/108B

Figure 4 Mars Case Bleed Selection Guide - Package Kit

SERVICE BULLETIN NUMBER: 8.8/108B

Page 7 of 8

Figure 5 Selection Guide - 6” Bleed Duct and 6” Diverter Kit

Page 8 of 8

SERVICE BULLETIN NUMBER: 8.8/108B

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mars, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

8.8/112 June 1999 Mars M 100

SUBJECT: MARS 100 STANDARD COMBUSTION COMBUSTOR LINER/INJECTOR DURABILITY Type of Change:

Product Reliability

Recommended Compliance:

Earliest Convenience

Purpose: The purpose of this Service Bulletin is to alert Customers to a potential durability issue with Mars standard combustion combustor liners. GENERAL INFORMATION: A number of Mars 100 standard combustion combustor liners (P/N 241600) have been found by boroscope inspection to be suffering from thermal distress after a relatively low number of hours of operation. This distress is initially manifested as cracking emanating from cooling air holes located immediately downstream of the injectors, and may progress to thermal erosion and burn-through of the cooling holes. This distress in its early stages has been found in engines with as few as 1,700 hours and can reach a significantly more advanced stage of deterioration by 4,000 hours of operation. Factors such as poor fuel quality, particularly liquids in gas fuel, and continuous operation at full load can accelerate the deterioration. The existence of this deterioration is not initially apparent from either turbine performance or T5 spread measurements and must be detected by boroscope inspection. If allowed to go unchecked, the liner distress may require a replacement of the combustor liner. No cases to date have resulted in collateral damage to the engine.

SERVICE BULLETIN NUMBER: 8.8/112

Page 1 of 2

The problem has been discovered on Mars 100 (T14000 or T15000) engines operating on gas fuel and fitted with either the effusion-cooled gas only injector or dual fuel injector (P/N 198834). ACTION REQUIRED: Each of Solar’s District Field Service offices has a list of those engines, which are or may potentially be at risk, and they will be contacting customers with such engines to set up an inspection of the combustor liner and fuel injectors. You can also contact the local Solar District office to confirm which, if any, of the engines in your Mars 100 fleet may be at risk and discuss actions required. A modification to the current injector design has been confirmed through testing to substantially reduce outer liner temperature. This injector (P/N 301380) will be incorporated in all new and overhauled engines and will be available for retrofits over the next several months. Pending availability of this injector, an alternate injector design (P/N 124835-500 for gas fuel and P/N 198337-20X for dual fuel engines) can be installed temporarily to arrest or prevent combustor liner thermal distress. Combustor liner replacement may also be required based on assessment of combustor liner condition during boroscope inspection. In the event that either the combustor liner or the fuel injectors require replacement, it is essential that the replaced parts be returned as expeditiously as possible to Solar’s refurbishment center in Mabank, Texas. Solar personnel on site to perform the component replacements will provide assistance to help ensure prompt return of replaced parts.

Page 2 of 2

SERVICE BULLETIN NUMBER: 8.8/112

SERVICE BULLETIN NOTICE:

The Type of Change and Recommended Compliance specified reflects Solar’s best judgment regarding the Service Bulletin. All questions should be directed to your Solar Field Service Representative. Solar, Saturn, Centaur, Taurus, Mercury, Mars, Titan, SoLoNOx, and Turbotronic are trademarks of Solar Turbines Incorporated. Cat and Caterpillar are trademarks of Caterpillar Inc. Specifications subject to change without notice.

NUMBER: ISSUED: REVISED: PRODUCT: MODEL(S): Specifics:

8.12/102A June 1995 March 2001 Saturn, Centaur All

SUBJECT: COMBUSTOR/EXHAUST COLLECTOR DRAIN VALVE —REVISION NOTICE— This revision replaces Service Bulletin 8.12/102. The previous bulletin must be removed and discarded. This version announces availability of an improved drain valve, retrofit kit, and installation instructions.

Type of Change:

Product Improvement

Recommended Compliance:

As Required

Purpose: To announce the availability of improved combustor/exhaust drain valve and field retrofit kit. GENERAL INFORMATION: The existing valves, Solar P/N 901086C91 and 190786-100 (Figure 1) have been in operation for a number of years. Some of these valves develop combustor discharge gas leaks through the gasket or sealing ball and fitting. Solar has developed an improved higher-pressure valve, together with instructions for installation. The new valve, Solar P/N 1020281-100 (Figure 2) has been successfully laboratory and field-tested. The new valve is used on current production models. The new valve assembly has twelve bolts at the flange, compared to the old valve assembly, which has only six bolts.

SERVICE BULLETIN NUMBER: 8.12/102A

Page 1 of 3

ACTION REQUIRED: If the combustor/exhaust drain valve on the unit has leakage at the gasket area or excessive leakage through the valve, replace the existing valve with the improved valve using field retrofit kit, Solar P/N 179902K105B. This kit includes all necessary parts and instructions for field modification. Please contact the Solar Field Service office for assistance as required.

Figure 1 Existing combustor/Exhaust Drain Valve.

Page 2 of 3

SERVICE BULLETIN NUMBER: 8.12/102A

Figure 2 Improved Combustor/Exhaust Drain Valve.

SERVICE BULLETIN NUMBER: 8.12/102A

Page 3 of 3

Solar Turbines Incorporated

GTUA 2001

ACRONYMS ABC

Augmented Backside Cooled

ACS

Application Check Sheet

ATS

Advanced Turbine Systems

CED

Cold-End Drive

CGCM

Combination Generator Control Module

CO

Carbon Monoxide

CSA

Customer Support Activity

DCR

Design Change Request

DF1

Communications Protocol of the External System Link

DIN

Deutches Institute der Normen (German Specification Institute)

DLE

Dry Low Emission

DOE

Department of Energy

DOS

Disc Operating System

DOT

Department of Transportation

DP

Differential Pressure (compressor)

dp

Differential Pressure (flow meter)

ERP

Enterprise Resource Planning

ESI

Energy Services International Limited

FOD

Foreign Object Damage

FPSO

Floating Production, Storage and Offloading

FSR

Field Service Representative

HED

Hot-End Drive

HMI

Human Machine Interface

HRD

Human Resources Development

HTML

Hyper-Text Markup Language

IEC

International Electrical Code

IGV

Inlet Guide Vane

I/O

Input/Output

ISO

International Organization for Standardization

KVAR

Kilovolt Amp Reactive

LSM

Line Synchronization Module

NEMA

National Electrical Manufacturers' Association

NOx

Oxides of Nitrogen

ODBC

Open Data Base Connectivity

OLE

Object Linking and Embedding

OMI

Operation and Maintenance Instructions

OPC

OLE for Process Control A-3

Appendix

Solar Turbines Incorporated

GTUA 2001

ACRONYMS, Contd O2

Oxygen

Pcd

Compressor Discharge Pressure

PD

Project Definition

PLC

Programmable Logic Controller

P/N

Part Number

RBOT

Rotary Bomb Oxidation Test

RFE

Regional Field Engineers

RS

Recommended Standard of the Electronic Industries Association (EIA)

SAMS

Solar Asset Management Services

SCADA

Supervisory, Control and Data Acquisition System

TAN

Toxic Acid Number

TBC

Thermal Barrier Coating

Tpz

Primary Zone Temperature

TRIT

Turbine Rotor Inlet Temperature

T5

Power Turbine Inlet Temperature

VAMS

Variable Air Management System

VBA

Visual Basic for Applications

XML

Dynamic Markup Language

A-4

Appendix

Solar Turbines Incorporated

GTUA 2001

SOLAR’S CUSTOMER SERVICES OFFICES – INTERNATIONAL Argentina

Indonesia

Turbigas Solar S.A. J. Salguero 2745 – Office 21/22 (1425) Buenos Aires, Argentina Phone: [5411] 4802-8200 Fax: [5411] 4801-0066

P.T. Solar Services Indonesia rd Gedung Menara Perdana 3 Floor Jalan H.R. Rasuna Said Kav. C-17 Jakarta, Indonesia 12940 Phone: [6221] 522-0860 Fax: [6221] 522-0864

Australia – Melbourne Solar Turbines Australia 38 Kingsley Close Rowville, Victoria 3178 Australia Phone: [613] 9764-1411 Fax: [613] 9764-0025

Ireland

Australia – Perth

Malaysia

Energy Services International Ltd Boghall Road, Bray County, Wicklow Ireland Phone: [3531] 2768400 Fax: [3531] 2867797

Delcom Services SDN. BHD. No. 42, Jalan 1/82B, Bangsar Utama Bangsar, 59000 Kuala Lumpur, Malaysia Phone: [603] 282-6091 Fax: [603] 282-6313

Solar Turbines Australia 6/48 Vinnicombe Drive Canningvale, WA 6155 Australia Phone: [618] 9455-6566 Fax: [618] 9455-6466

Mexico – Carmen

Belgium

Turbinas Solar, S.A. de C.V. Calle 31, No. 113 Colonia Aviacion C.P. 24170 Cd. Del Carmen, Campeche Mexico Phone: [52938] 2-4038 Fax: [52938] 2-8906

Solar Turbines Europe S.A. Avenue Des Etats-Unis 1, Boite Postale 1 B-6041 Gosselies, Belgium Phone: [3271] 25-3000 Fax: [3271] 344739

Brazil

Mexico – Mexico City

Caterpillar Brasil Ltda Avenue Marechal Camara, 160-Gr 523/4/5 20020-080 Rio de Janeiro, RJ Brazil Phone: [5521] 215-5671 Fax: [5521] 215-5673

Turbinas Solar, S.A. de C.V. Bosque de Alisos No. 45B-1 Piso Arcos Oriente, Bosques de Las Lomas Mexico, D.F.C.P. 05120 Phone: [525] 570-3850 Fax: [525] 570-3994

Canada – Edmonton Solar Turbines Canada Ltd. th 2510 - 84 Avenue Edmonton, Alberta T6P 1K3 Canada Phone: (780) 464-8900 Fax: (780) 464-8942

Mexico – Veracruz Turbinas Solar, S.A. de C.V. Av. Framboyanes, M6 L1 Cd. Ind. B. Pagliai Phone: [522] 989-7900 Fax: [522] 989-7938

China Caterpillar China, Ltd. Beijing Liaison Office Room 801, Tower A, Full Link Plaza No. 18 Chaoyangmenwai Avenue Beijing, 100020 People’s Republic of China Phone: [8610] 6588-1625 Fax: [8610] 6588-1629

Internet: www.solarturbines.com

Mexico – Villahermosa Solar Turbines Villahermosa Campo Samaria 100, Conj. Giraldas Casa 7 Fracc, Carrizal C.P. 86038 Mexico Phone: [5293] 16-5381 Fax: [5293] 16-2932

A-5

Appendix

Solar Turbines Incorporated

GTUA 2001

SOLAR’S CUSTOMER SERVICES OFFICES – INTERNATIONAL, CONTD Nigeria

United Kingdom – Aberdeen

Solar Turbines Services Nigeria Limited 36 Trans Amadi Industrial Estate P.O. Box 3783 Port Harcourt, Nigeria Phone: [23484] 230186 Fax: [23484] 230185

Solar Turbines Europe S.A. Unit 2, Hareness Circle Altens, Aberdeen, Scotland AB12 3LY UK Phone: [441224] 291919 Fax: [441224] 291910

United Kingdom – London

Singapore

Solar Turbines Europe S.A. Suite H, Centennial Court, Easthampstead Road Bracknell, England RG12 1YQ UK Phone: [441344] 782920 Fax: [441344] 782930

Solar Turbines International Company 7 Tractor Road, Singapore 627968 Republic of Singapore Phone: [65] 6608800 Fax: [65] 6608856

Venezuela

United Arab Emirates

CENTEC C.A. Multicentro Empresarial del Este Ed. Miranda, Torre B, Piso 16 Av. Fco. De Miranda, Chacao Caracas, Venezuela Phone: [582] 263-2755 Fax: [582] 263-3014

Solar Turbines Europe S.A. Office 503/504, Bin Ham Building Trade Center Road, P.O. Box 12023 Dubai, United Arab Emirates Phone: [9714] 3593818 Fax: [9714] 3593802

Internet: www.solarturbines.com

A-6

Appendix

Solar Turbines Incorporated

GTUA 2001

SOLAR’S CUSTOMER SERVICES OFFICES – U.S.A. Anchorage

Miami

Solar Turbines Incorporated 524 West International Airport Road Anchorage, AK 99518-1105 Phone: (907) 562-2440 Fax: (907) 561-2591

Solar Turbines Incorporated th 10691 S.W. 88 Street, Suite 109 Miami, Fl 33176 Phone: (305) 279-6270 Fax: (305) 595-2575

Chicago

New Orleans

Solar Turbines Incorporated 40 Shuman Boulevard,Suite 350 Naperville, IL 60563 Phone: (630) 527-1700 Fax: (630) 527-1997

Solar Turbines Incorporated 6128 Jefferson Highway New Orleans, LA 70123 Phone: (504) 734-8241 Fax: (504) 736-9186

Houston

New York

Solar Turbines Incorporated 13105 Northwest Freeway, Suite 400 Houston, TX 77040 Phone: (713) 895-2300 Fax: (713) 895-4240

Solar Turbines Incorporated Sherbrooke Center 600 East Crescent Avenue, Suite 305 Upper Saddle River, NJ 07458 Phone: (201) 825-8200 Fax: (201) 825-8454

Los Angeles

Odessa

Solar Turbines Incorporated 2121 S. Towne Centre Place, Suite 370 Anaheim, CA 92806 Phone: (714) 937-0360 Fax: (714) 937-1411

Solar Turbines Incorporated 2626 J.B.S. Parkway, Suite B-110 Odessa, TX 79761-1947 Phone: (915) 367-5055 Fax: (915) 367-9523

Lafayette

Salt Lake City

Solar Turbines Incorporated 1501 Ambassador Caffery Parkway Lafayette, LA 70506 Phone: (337) 988-7400 Fax: (337) 988-7434

Internet: www.solarturbines.com

Solar Turbines Incorporated 6965 Union Park Center, Suite 460 Midvale, UT 84047 Phone: (801) 352-5100 Fax: (801) 352-5151

A-7

Appendix