Thermal Power Plant Auditing

PRESENTATION ON ESSENTIAL REQUIREMENTS FOR ENERGY AUDITS IN THERMAL POWER STATIONS BY H.S.Bedi Sr. Vice President (Power)

Energo Engineering Projects Ltd. A-57/4, Okhla Industrial Area, Phase – II, New Delhi - 110020

1

“You cannot Manage what you cannot Measure” (Accurately) - Jack Welch, CEO, General Electric 2

PATTERN OF ENERGY CONSUMPTION IN THERMAL POWER STATION

TYPICAL PLANT LOSSES 4

ECONOMIC ASPECTS OF INEFFICIENT MACHINES (200 MW) SHORT FALL

LOSS IN CRORES PER ANNUM

TURBINE CYCLE HEAT RATE

1.0 %

5.0

BOILER EFFICIENCY

1.0%

1.75

AUX. POWER CONSUMPTION

5.0 %

1.25

5

REQUIREMENT – 1 1.1

ACCURACY OF COLLECTED DATA

–

Collected data has to be most accurate & doubtless.

–

Use calibrated and accurate instruments better conforming to ASME-PTC standards

–

1.0% Error in data means unreliability and 25000 tons of coal loss/annum for 200 MW Unit or approx Rs. 5 crores / year based on assumption that •TG cycle heat rate is taken as 2000 kcal / kwh •Coal CV is taken as 4000 kcal / kg •Price of coal taken as Rs. 2000 / ton

–

Loss increases with machine size 6

1.2

EFFECT OF INSTRUMENTATION ON ACCURACY

A. Plant on-line instruments with few audit instruments Accuracy around 3.0%. B. Accurate calibrated instruments as per ASME-PTC-6 for steam turbine& ASME-PTC-4-1 for Boilers. Accuracy around 0.5 % 1.3

– –

EFFECT OF PROCEDURE ON ACCURACY OTHER THAN ASME-PTC-6 for steam turbines and ASME – PTC-4.1 for boiler Error in Boiler Energy Audit – around 2.0% Error in steam turbine Energy Audit – around 3.0% 7

1.4

TOTAL ERROR BECAUSE OF

INSTRUMENTATION & PROCEDURE INACCURACY 6.0% NOTE: DIFFERENCE

IN

COST

OF

ENERGY

AUDIT

BETWEEN AUDIT BY ACCURATE INSTRUMENTS AS PER ASME AND NORMAL INSTRUMENTS IS 12 TO 14 LACS AS AGAINST 6 TO 8 LACS. 8

EFFECT OF INSTRUMENT INACCURACY ON HP/IP Turbine Efficiency Main Steam HPT Efficiency

Pressure Kg/cm2

Temp Deg C

Pressure Kg/cm2

Temp Deg C

1

1

1

1

0.6 %

0.6 %

2.0 %

0.7 %

IPT Inlet IPT Efficiency

HPT Exhaust

IPT Exhaust

Pressure Kg/cm2

Temp Deg C

Pressure Kg/cm2

Temp Deg C

1

1

1

1

1.2 %

0.3 %

6.0 %

0.4 % 9

EFFECT ON HEAT RATE FOR PARAMETER DEVIATION (500MW UNIT) DEVIATION IN PARAMETER

EFFECT ON HEAT RATE (KCAL/KWH)

1.

HPT inlet press. by 5.0 ata

6.25

2.

HPT inlet temperature by 10.0deg C

6.0

3.

IPT inlet temperature by 10.0deg C

5.6

4.

Condenser pressure by 10.0 mm of Hg

9.0

5.

RH spray water quantity by 1.0%

4.0

6.

HPT Cylinder efficiency by 1.0%

3.5

7.

IPT Cylinder efficiency by 1.0%

4.0 10

REQUIRED ACCURACY AND CALIBRATION OF THE INSTRUMENTS The proposed instruments should have following level of accuracy. i. ii.

Thermocouples and PRTs – ASME special class ‘A’ i.e ½ DIN tolerance Pressure and differential pressure 0.1% transmitters better than iii. Power Meter for generator & 0.1% Unit Aux Power measurement iv Data Logger 0.03% v Power transducers / Load Analyser 0.5% vi Flue gas analyser 0.5% vii Ultrasonic flow meters 0.5% viii Anemometer 1.0% ix Infrared Thermometer 1.0% x Lux meter 1.0% xi RH meter 1.0% These should be duly calibrated from NABL accredited lab. The above accuracies for S.No. I to V are as per ASME specified for Performance Evaluation of Thermal Power Plants. 11

REQUIREMENT – II PROPER SCHEMES FOR ENERGY AUDIT FG

Expansion Bellow

Economizer HVS

APH

APH

Sampling Locations FG 12

Annexure - I BOILER EFFICIENCY AND APH TEST SCHEME & INSTRUMENTATION DIAGRAM 1. Grid measurement for gas composition and gas temp. at air pre heater inlet / outlet. W/6

W/3

T1 N11 N12 N13

T2 N21 N22 N23

W/3

W/6 T3 N31 N32 N33

D/6

D/3 DEPTH

D/3

D/6 13

14

15

ENERGY AUDIT SCHEME FOR 210 LMW STEAM TURBINE

16

REQUIREMENT - III FREQUENCY OF READINGS FOR ACCURATE DATA COLLECTION TURBINE CYCLE AUDIT Pressure Temperature Flow Power Levels

-

5 Minutes 5 Minutes 1 Minute 1 Minute 10 Minutes

-

15 to 30 Minutes ½ to one hour

BOILER UNIT AUDIT Temperature Flue Gas Composition

DURATION OF AUDIT TEST Turbine Cycle Boiler Unit

-

2 Hrs 4 Hrs 17

REQUIREMENT – 4 SCOPE OF WORK (SPEC) FOR ENERGY AUDIT OF A TYPICAL THERMAL POWER PLANT UNITS A. BOILER •

Boiler efficiency by heat loss method as per ASME PTC-4-1 guidelines and give break up of losses

•

Furnace air ingress at different levels upto I.D.Fans

•

Air heater performance  Gas side efficiency  Air side and gas side pressure drop across APH  Air leakage across APH  X – ratio i.e heat capacity of air to gas capacity.

•

Aux power consumption and combined efficiency of fan and motors of ID, FD & PA fans.

•

18 Aux power consumption of coal mills, feeders vs loading.

B. 1.

TURBINE Turbine cycle heat rate as per ASME-PTC-6 methodology and instrumentation

2.

HP and IP cylinders efficiency

3. 4.

Turbine pressure survey TTD & DCA of HP / LP heaters Pressure drop across heaters

5.

Condenser performance i.e 

Condenser back pressure after duly considering the effect of present C.W inlet temp, C.W flow, heat load on condenser and air ingress to condenser vis-à-vis design conditions



C.W side pressure drop in condenser

1.

Cycle losses

2.

Performance of turbine glands

3.

Ejector performance 19

C.

ELECTRICAL SYSTEM

1

Motors

• Assessment of Loading condition of HT and LT motors of Boiler area, Turbine area and Balance of Plant area. • Assessment of operating parameters like load variation, Power factor of HT and LT motors consuming power more than 50 KW.

2

Capacitors

• Assessment of health of capacitors.

3

Plant Lighting system

• Lighting load survey and Assessment of installed load efficacy (I.L.E) and I.L.E ratio at various areas of plant.

20

D.

Pump performance for BFPs, CEPs, Aux C.W.P & C.W.P and pumps consuming power more than 50 KW etc.

•

Check Performance of the pumps by comparing the corrected measured flow at operating speed to design speed with that of the expected flow derived from the characteristic curves against the corrected total dynamic head at design speed.

•

Determine Pump efficiency as the ratio of power input to the pump shaft to hydraulic power.

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E A.

Insulation Audit: Walk through survey of Boiler, Turbine and associated steam piping to identify the damaged and Hot spot area.

B.

Surface temperature measurement at the damaged and Hot spot area by infrared temperature indicator.

C.

Estimation of heat loss in the hot spots and damaged insulation area.

F

Balance Of Plant

(i)

Compressed air system:

•

Free Air Delivery i.e. Capacity evaluation of the Plant and Instrument air compressors. •

Checking volumetric efficiency of compressors.

•

Assessment of compressed air leakage quantity. 22

(ii)

Air conditioning system:

•

Performance evaluation of AC Plant w.r.t net cooling / refrigeration capacity along with heat load of Air handling unit and energy requirements.

(iii)

Ash Plant

•

Performance of ash Slurry pumps through power measurement and flow measurement.

•

Ash water ratio assessment and recommendations for optimization in water and power consumption.

(iv)

Cooling Tower Performance It shall include establishment of

•

Liquid/Gas ratio

•

23 Cooling tower effectiveness, approach and range

(V)

Coal Handling Plant

Input Power measurement of all the key equipment of the CHP area like: Paddle feeders, Conveyors, Stacker & Re-claimer, Wagon Tipplers, Crushers,

NOTE: •

ENERGY CONSERVATION MEASURES TO BE SUGGESTED IN ALL THE ABOVE AREAS OF AUDIT.

•

ENERGY AUDIT PROCEDURE TO BE SUBMITTED ALONG WITH AUDIT MEASUREMENT SCHEMES AND APPROVED 24

1.0 • • • • • • • • • • • •

USEFULNESS OF ENERGY AUDIT IN THERMAL POWER STATION Identifies wastage areas of fuel, power and water utilization. Reduction in cost of generation by implementing findings of EA. Increases power generation by efficient utilization of steam in turbine cycle and reduction in Aux Power Consumption. Maintenance planning and availability improvement. Provides guidance in loading sequences of the units. Identification and rectification of errors in on-line instruments. Leads to reduction in green house gases. Utilizes specialized services of experienced engineers. Training of O&M staff for efficient control of unit operation. Improves competitiveness by reducing unit generation. Creates bench mark for all equipments and systems. Fulfills bureau of energy efficiency mandatory requirement of Energy Audit. 25

METHODS / OBSERVATIONS FOR SAVINGS ENERGY IN POWER PLANT 1) Operation of machine at very low turbine I/L parameters. 2) Operation of turbine at lower loads. 3) HP and IP turbine cylinder efficiencies are very low. 4) Main steam and HRH inlet temperature to turbine very low. 5) RH pressure drop high. 6) High quantity of SH Spray and its tapings before HPH-5 resulting in loss of heat because of changed cycle. 26

METHODS / OBSERVATIONS FOR SAVINGS ENERGY IN POWER PLANT 7)

HP heater no. 5 out of service.

8)

Turbine cycle not operating as per design scheme i.e. Ejector and Deaerator pegging steam from PRDS header as against normal source from deaerator & extraction steam respectively.

9)

Passing of turbine cycle drain valves.

10) Make up quantity to cycle is very high which indicates excessive system

steam (heat) loss.

11) TTD & DCA of heaters high. 27

METHODS / OBSERVATIONS FOR SAVINGS ENERGY IN POWER PLANT 12)

Condenser air ingress and dirty tubes.

13)

Under loading of motors

14)

Excessive air leakage in compressed air system

15)

Faulty insulation

16)

Drain valves passing

17)

Air ingress to Boiler furnace

18)

FAD of compressors low 28

Thanks… Energo Engineering Projects Ltd. A-57/4, Okhla Industrial Area, Phase – II Phone: +91 - 11 - 26385323/ 28/ 29/ 38 Fax: +91 – 11 – 26385333 E-mail: [email protected] [email protected] Web: www.energoindia.com 29