Vizag Steel Plant

VIZAG STEEL PLANT ABSTRACT

Steel has always been the backbone of nation's economy. From an annual production of 13 million ton in 1900, global steel production raised to 300 million ton in 1950 and to 842 million ton in 2000. India produces 30 million ton per annum from 9 major plants. The major steel plants contribute 19 million tones and the rest is contributed by secondary sector. Visakhapatnam Steel Plant is one of the 6 integrated steel plants contributing 3.51 million ton of liquid steel per annum. It is the only steel plant in India accredited with ISO 9001, ISO 14001, and OHSAS 18001 certificates for Quality environment and Safety aspects of the steel making activities. With the improvement in operating performance of major units and efficient maintenance and material handling system the plant has made a turn around and achieved net profit of 2100 crore rupees during the current fiscal 2004-05. This project deals with the Design verification of critical Trunnion ring of a process equipment LD Converter used for steel making process. The LD converter is a steel shell lined with refractory material used for handling the molten steel at 1650° C. The vessel is suspended on a trunnion ring with four numbers of tie rods and rotates at 0.1-1.0 RPM by means of four hung reducers and one special reducer with motors of 4 - 172KW DC. The trunnion ring is box section with plates 140mm having forged end journals and the entire assembly weighs around 147 Tons carrying 1000 Tons of vessel with hot metal. The linear dimension of the trunnion ring will be around 14 Meters and the straightness of the surface should be 1 mm over 1000mm span. General norms of the life of the trunnion is around 1 0 Years but the it is to be changed with the survey readings if the deformation exceeds the limit. In converter No.1, the survey readings depicted around 20mm deformation and is to be changed in a planned shutdown as the repair takes around 40 days shutdown of the process equipment. Keeping this in mind a new trunnion ring was imported from the Russia and is observed the changes in the design

compared to the existing trunnion in the hole sizes 0300 fTom 0180. It is necessary to verify the design before implementation about the safety of the system.

In this regard after visiting the site and collecting the necessary dimensions a 3Dimensional modeling using CATIA has been done for the existing and modified design. Also the model has been imported to ANSYS and the von-mises stresses have been obtained by applying fixed support constraint and loading conditions and the stresses induced in the trunnion ring is around 25.32 N/mm2 in the existing trunnion and 36.5 N/mm2 in the modified trunnion ring. With the material of ASTM-A36 of the trunnion, the existing Factor of safety is reduced fTom 11 to 8 and as per the norms for the structural the allowed factor of safety shall be above 5. Hence the design is safe for the operation. The data is presented with 3D model of objects, meshed images and von-mises stresses. The present analysis was done only in static case. This can be further extended to dynamics considering the rotation of the trunnion ring. As the technological developments are taking place in steel making process there is an .

ample scope of adopting new design Russian LD converter trunnions with the adoption Top cone water cooling system coupled with bottom bath agitation facilities which require bigger hole sizes in the trunnion end journals, the designs become critical and requires thorough analysis.

SOCIAL RESPONSIBILITY Peripheral development and special concern for the displaced persons underling the Visakhapatnam steel plant's commitment and concern for the social and regional development around it. As a special gesture for the welfare of the displaced persons, Visakhapatnam steel plant

provided them with over 5,900 jobs, which constitute more than 1/3 of its total non-executive manpower. In the recruitment policies of VSP displaced persons have been given several concessions in the areas of educational qualifications, age and skill levels. As a part of social responsibility VSP took a massive afforestration program has been launched in and around the plant. Out of the total 9,200 hectares of area 3,600 hectares has been ear marked for afforestation. Along the land boundary of VSP a green belt of half a kilometer has been delineated for afforestation. 1.4 lakh trees have been planted in 100 hectares during 94-95 and 1.22 lakhs of trees has been planted in 207 hectares during 95-96.3 million trees for 3MT of steel was the slogan ofVSP.

That target also achieved. VSP has been complying with statutory standards of both Andhra Pradesh pollution control board and central pollution control board. It has been closely maintaining 31 major stack emissions and 8 ambient air-monitoring areas out side steel plant. I

. Mission and Core values of VISAKHAP A TNAM STE PLANT :.

Vision: To be a continuously growing world-class company. We shall:

.:. Harness our growth potential and sustain profitable growth. .:. Deliver high quality and cost competitive products and be the first choice of the customer. .:. Create an inspiring work environment to unleash the creative energy of people. .:. Achieve excellence in enterprise management. .:. Be a respected citizen, ensure clean and green environment and develop vibrant communities around us.

Mission: To attain 10 million ton liquid steel capacity through technological up- gradation, Operational efficiency, to produce steels of international standards of cost and quality to meet the aspirations of the stake holders.

Core-values: .:. Commitment .:. Customer satisfaction .:. Continuous improvement .:. Concern for environment .:. Creativity and innovation

OVERVIEW TO VIZAG STEEL PLANT

GENERAL SURVEY OF IRON AND STEEL MAKING IN INDIA India is the third largest producer of iron and steel in the common wealth nations (surpassed only by the UK and Canada) and is 16th among the steel producers of the world. At present, India's capacity of steel production is nearly 1.5% of the total world production. The Tata Iron and Steel Co., Jamshedpur (Bihar), Indian iron and steel Co., Burnapur (West Bengal), Visveswaraya iron and steel limited, badhravali (Karnataka) and a few electric arc furnaces were the only steel plants in India until 1955.three new public sector plants under Hindustan steel Ltd,. Were established in the period 1955-60 at Bhilai (MP), Rourkela (Orissa) and Durgapur (WB). Each of these has their own coke-ovens which supply the large amount

of coke needed for steel manufacturer. The plant at Bhilai and Durgapur employs the basic open-hearth process of steel making. The Rourkela plant is unique in the fact that it employs L-D process for manufacturing 75% of steel. The output of the remainder (Le., balance of25% of steel) is by the basic open-hearth process. At present there are eight integrated steel plants and about 174 mini steel plants. The integrated steel plant located at Jamshedpur (TISCO) is the only private sector plant, and the rest are in public sector. Integrated steel plants in public sector are: 1. Indian iron and steel Co., (IISC,), Burnapur (WB) 2. Viswesraya iron and steel Ltd,.(VISL), Badhravali (Karnataka) 3. Rourkela steel plant (RSP), Rourkela (Orissa) 4. Bhilai steel plant (BSP), bhilai (MP) 5. Bokaro steel plant (BSL), Bokaro (Bihar) 6. Durgapur steel plant (DSP), Durgapur (WB) 7. Visakhapatnam steel plant (VSP), Visakhapatnam (AP). The visakhapatnam steel plant is designed to produce three million tons of liquid steel per annum to be converted to 2.656 million tons per annum of saleable steel. In addition, Visakhapatnam steel plant will produce annually about 5.56 lakh tons of pig iron and various by-products for sale.

LOCATION: The plant is located in Visakhapatnam City, which is on the coast of Bay of Bengal. Visakhapatnam city is an important commercial center of Andhra Pradesh. It has the deepest port and is one of the principal outlets for country's exporting Iron ore. The city has many large industries such as

the Hindustan Petroleum Refinery, Bharat Heavy Plates and Vessels ltd., Coromandal Fertilizers, Hindustan Zinc, Hindustan Shipyard etc. The city is situated on the main broad gauge railway line between Calcutta and Madras and is well connected with other major cities and state capitals by rail, road and air. The Visakhapatnam steel plant is located 16 Kms. to the southwest of the Visakhapatnam Port and is about 26 Ian ITom Visakhapatnam city. The town ship and the plant have been built on an area of 27,000 acres, between the national highway no.5 and the Bay of Bengal.

CLIMATE: Visakhapatnam has warm and humid climate. April to June are the warmest months of the year and December to February are the coldest months of the year. The city benefits ITom the Southwest monsoons (June to September) & Northeast monsoons (October to December). The average annual

rainfall

is

973.6mm

and

highest

mean

montWy

maximum

temperature is 37.8 degrees centigrade. THE DEPARTMENTS: There are altogether 25 departments in Vizag Steel Plant. These have been divided into two categories as Core Zone and Service Zone. Some of them are as follows: Core Zone: Blast Furnace, Coke Ovens, Steel Melt Shop, Mills, Sinter Plant, and Raw Material Handling Plant. Service Zone: Thermal Power Plant, Calcined Refractory Manufacturing Plant

Coke

Ovens

&

Coal

Chemical

Plant: Coking coal after selective crushing and

proper

blending

is

subjected

to

destructive

distillation (heating in the absence of air) in the Coke Ovens. After heating for nearly a period of 1618 hours at a temperature of about 1100°C, coke is obtained and is used as a fuel as well as reducing agent in the Blast Furnace. The Coke Ovens of VSP are engineering feats by themselves. They are the tallest ovens constructed in the country. There are three batteries, each having 67 ovens. Each oven is having a volume of 41.6 cu.m and can hold 31.6 T of dry coal charge. The carbonization time is 16 hours. A mixture of blast furnace gas and coke oven gas having a calorific value of 1000 Kcal/NM3 supplies the heat for carbonization. Another feature is the dry cooling of coke carried out by the inert gas nitrogen thus, reducing

pollution

considerably.

Besides,

a

bio-chemical

plant

separately undertakes the treatment of effluents. By-products like benzene, toluene, xylene, naphthalene, coal tar, creosote oil, pitch, ammonium sulphate and benzol products are also recovered from the coke ovens gas. VSP produces, among other by-products, pushkala a prime fertilizer based on ammonium sulphate.

Sinter Plant:

Iron ore fines, coke breeze, limestone and dolomite along with recycled metallurgical wastes are converted into agglomerated mass at the Sinter Plant, which forms 80% of iron bearing charge in the Blast Furnace. The Sinter

Plant

comprises

of

two

sinter

machines each having 312 square metres of grate area with a total , production capacity of 5.256 million tons per annum. Hot sinter, discharged ITom sintering machine at 900 degrees centigrade, is crushed to 15mm size in a spiked single roll crusher with a 1300 X 4200 mm rotor. Unsintered grains are liberated as sinter returns.

Blast Furnace: VSP has two Blast Furnaces with a useful volume of 3200 cu. m. each. Blast Furnace is charged with coke, iron ore and sinter ITom the top and produces about 5000 tons of molten iron per day. Its novel circular cast house with four tap holes ensures continuous tapping of hot metal. There are four hot blast stoves for each furnace with a total heating surface of 224000 square metre. The dome is heated to a temperature

of

1450

degrees

maximum,

while

the

waste

flue

temperature is 400degrees centigrade. The stoves are capable of giving a blast temperature up to 1300degrees centigrade. A mixture of blast furnace gas and coke oven

gas having a calorific value of 1100 KcalINM3 heats stoves. Gas mixing station is provided to mix BF gas and coke oven gas in required proportion and to get the necessary calorific value. Separate stations are provided for each furnace. The annual production capacity of these Blast Furnaces is 3.4 million tons of liquid lron.

Steel

Melt

Shoo

&

Continuous

CastinS!: Three topblown converters, each of 133 cu.m. Volume, produce a total of 3.51 million tons of liquid steel per annum. This liquid steel thus produced is casted in six-4 strand bloom casters. A special feature in energy conservation is the collection of Converter gas to be used as a fuel in the plant. The entire molten steel at VSP is continuously cast at the radial type continuous casting machines resulting in significant energy conservation and better quality steel. 100% Continuous casting on such a large scale has been conceived for the first time in India.

RollinS! Mills: The cast blooms trom continuous casting department are heated and rolled in the three high speed and fully automated rolling mills namely Light & Medium Merchant Mill, Wire Rod Mill and Medium Merchant & Structural Mill, to produce various long products like reinforcement bars, rounds, squares, flats, angles, channels, billets, wire rods etc. Technologies adopted at Rolling Mills include world-class Stelmor and Tempcore processes.

MODERN TECHNOLOGY:

Visakhapatnam Steel plant is the most sophisticated and modem integrated steel plant in the country. Modem technology has been adopted in many areas of production, some of them for the first time in

the country. Among these are: 1.

Selective crushing of coal.

2.

7 meter tall coke ovens

3.

Dry quenching of coke.

4.

On ground blending of Sinter base mix.

5.

Conveyor charging and bell less top for blast furnace.

6.

Cast house slag granulation for blast furnace.

7.

100% continuous casting of liquid steel

8. Gas expansion turbine for power generation utilizing blast furnace top gas pressure 9. Hot metal desulphurisation 10. Extensive treatment facilities of effluents for ensuring proper environmental protection. 11. Computerization for process control 12. Sophisticated, high speed and high production rolling mills.

MAJOR PLANT FACILITIES: The production facilities in the Visakhapatnam steel plant are most modem amongst the steel industry in the country. The know-how and the technology have been acquired from different parts of the world from the reputed and established sources. Some of the novelties of the Visakhapatnam steel plant are: 1. in the

7-meter height coke ovens ofVSP are the tallest so far built

country. Dry quenching of coke has been adopted which will not only improve the quality of coke and economics of coke production, but also contribute significantly to the reduction of environment pollution. 2.

Base mix yard for sinter plant introduced for the first time in

the country helps in excellent blending of the feed material to the sinter machine and production of consistent good quality sinter. 3.

With useful volume of 3200 cubic meters each the two blast

furnaces have bell less top charging equipment and 100% cast house slag granulation. The granulation of the entire molten slag arising at the furnace cast house avoids the need to transport molten slag and optimizes utilization of slag. 4.

100% continuous casting ofliquid steel into blooms result in

less and better quality of blooms. 5.

The VSP have three sophisticated and large rolling mills with

the latest features of automation and optimization. 6. The operations of blast furnaces, steel melting shop and rolling mills have been entirely computerized to ensure consistent quality and efficient performance. The major production departments of Visakhapatnam steel plant are the raw materials handling system, coke ovens, sinter plant, blast furnace, and steel melting shop and rolling mills. Extensive facilities have been provided for repair maintenance as well as manufacturing of spare parts. There is a Central machine shop, Structural shop, forge shop, foundry, wood working shop and loco repair shop. Visakhapatnam steel plant has got its own Air separation plant for production of oxygen and acetylene plant for production of acetylene

gas. A captive power plant has also been provided for power generation with 4 units, three of 60MW generation and one 67MW capacity. RAW MATERIAL LINKAGES: The steel plant is getting it supply of iron ore-lumps and fines from the Bailadilla deposits in Madhya Pradesh, blast furnace grade lime stone from the Jaggayyapeta in Andhra Pradesh, SMS grade lime stone from Badnapur in MP, blast furnace grade lime stone from the Kotni-sonor deposits in MP. Most of cocking coal requirement will be met by imports through the Visakhapatnam harbor while the balance will come from the Bengal-Bihar area. Coal for power generation will come from Anantha deposits of Talc her region in Orissa. POWER SUPPLY: Peak construction power requirements were about 12MV A This was arranged from the Gajuwaka substation of APSEB at 33KV. The Plant has in-plant power generation from a power plant having 3 Nos, of 60 MW sets installed. An additional requirement of operational power, around 150 MV A, is being met from APSEB grid. Operational power supply is initially at 220 KV, which is subsequently stepped down to 400 KV. WATER SUPPLY: Requirements of water during the peak of construction were of the order of 4.5 mgd. This was met from the Meghadrigedda, and Raiwada schemes of Andhra Pradesh State Government. Operational water requirements 70 mgd of the steel plant are being met ftom the Yeleru water supply scheme provided by the A.P. State Government. This involved construction of a storage reservoir at Yeleswaram and a 153 Kms. long linked canal to the plant site apart from the Kanithi Balancing Reservoir.

Product Mix:

The product mix of VIZAG Steel Plant

compnses

.

Wire Rods

. .

. . . .

Bars Angles Channe ls Beams Rounds Billets

The Plant also produces Pig Iron, Granulated Slag and Coal Chemicals. The

rolled

products

find

extensive

usage

in

the

Construction,

Inftastructure, Railways, Power, Oil, defense, and Transport and Ship Building sectors. Bars and Rods are used mainly for re-inforced concrete work

for

housing,

construction

of

dams,

buildings

&

factories,

manufacture of agricultural implements, fabrication of light engineering components. The Wire Rods are used in Wire Drawing industry for electrodes, transmission lines and weld ability requirements. The structurals find application in engineering, house building, agricultural implements, machinery, transmission towers, etc.

BRIEF ON STEEL MELTING SHOP OF VSP

In line with international levels of operation, the levels of steel production can be considerably higher than that what was envisaged in the revised DPR. Each converter with a volume of 133M3 is capable of producing 150 tons of liquid steel per heat and considering 10,000 heats annually per operating converter, a liquid steel achievable ftom one operating converter. Thus with the installation of third converter in SMS the shop has the potential to produce about 3.0MT of liquid steel. Accordingly, it is proposed to install one more converter and two additional bloom casters in SMS-l, within the area provided for the future expansion. As a result, SMS-2 need not be installed. To achieve the production of3.0 MT per year the following is a must: ~ Silicon content of hot metal should not exceed 1% ~ Lime used as flux should have 90-92 %(CaO + MgO) and Si02 content should not exceed 2.5%. This may necessitate import of highgrade limestone.

~ Converter lining life should be 300 heats, and the relining time should not exceed 5 days.

~ The blowing time should not be more than 18 minutes and the gas cleaning system shall be adequate to meet this requirement. ~ Each bloom caster is required to cast 10 heats in sequence. The machine availability may have to be increased to 310 days per year. ~ The capacity of cranes, transfer cars etc. marginally increased to handle 150 tons per heat.

FACILITIES: The major facilities are as follows: 3.0 MT Stage 1. Production (T lye) (a) Liquid steel (b) Cast blooms (1) 250x320 MM (2) 250x250 MM 3,000,000 1,915,000 2. Facilities (a) mixers (b)Hot L-D metal Converters

905,000 2x1300T 2x1333

(c) Continuous casting machines 3x4-strand

2x 1300-7 torpedo cars of 300T cap 3x133M3 6x4 -strand

REFRACTORIES FOR SMS: to 1.0 Mt of HIM can be held with this lining over a year. ~ FOR CONVERTER LINING: Permanent lining is by chrome magnesite ~ High grog bricks line hot metal ladle, and medium heat duty bricks bricks. Working lining is by pitch -bonded magnesia enriched are used as back-up lining. Life is 500 dolomite bricks. Magnesite blocks lineheats. tap hole. Lining life is 300 heats. ~ For slide gate refTactories high alumina based material is used. ~ High alumina bricks line steel teeming ladles as working lining and ~ medium heat duty fireclay bricks as back up. Life is 15-20 heats. ~ ~ Mixer lining is by high duty magnesite bricks, and back-up lining is by mica insulation bricks. Alumino-silicate bricks line Root. Up

Fire clay and high grog bricks line Tundishes and slag boxes. Stopper rods for tundishes are corundum graphite mono-block stopper rods, Al203 graphite nozzles. Submerged nozzle is

corundum graphite; lining life of tundishes is 10 heats for working lining.

LAYOUT: The LD Converter building 36m towards north end and a new scrap aisle is provide adjacent to the charging aisle. The ladle preparation bay is extended by the north end to facility installation of new ladle preparation bay is extended by the north end to facilitate installation of new ladle preparation facilities. The continuous casting department is extended by 102m towards north end for relocation of CCM-4 and housing the 5th and 6th bloom casters.

CONVERTERS: The tap-to-tap cycle time is

Timing in min.

. Charging of scrap . Charging of hot metal . Oxygen blowing . Intermediate slag off

.

Sampling, temperature recording etc. Steel tapping

. . Draining of slag . Preparation of converter . Unforeseen days Total: Provision is kept for production of 59 heats per day.

3 4 1 8 3 5 6 2 3 6 50

SAILENT FEATURES OF THE CONVERTERS:

·

Converter capacity, tons

·

Effective volume of converter M3 · Converter specific

volume, M3 rr · Mouth diameter inside lining, nun 150 145 0.95 2700

·

Weight of converter lining including bottom lining,tons

455

·

Thickness of working lining, mm

780

·

Thickness of permanent lining, mm

230

·

Weight ofline shell with trunnion ring and bottom, tons

849

·

Weight of lined bottom, tons

·

Speed of converter tilting, rpm: Max.

1.0

·

Min.

0.1

·

Lance movement speed, mtslsec: nominal

·

Minimum

·

Lance travel, mm

·

Oxygen working pressure

15 KSCG

·

Water working pressure

12 KSCG

60

0.88 0.2 15000

Suppressed combustion type gas collection, cooling and cleaning system is provided. This system comprises of tube-bar-tube type skirt, gas cooling hood, closed loop type gas cooling arrangement with fin-fan cooler, gas duct, ill fan, change over valve, flare satack, gas holder,

electrostatic precipitator, booster fan etc. the gas is being recovered and when the gas composition is acceptable.

AUTIOMATION AND CONTROL

CONVERTER CONTROL SYSTEM: Following level hierarchical system is provided: level-l consists of process control computer system for overall shop management, coordination, and data acquisition and monitoring. Level-2: Blowing: micro computer system for on line dynamic end point control using sub lance and set point control and Level 3 :Distributed control systems for control and monitoring of the process parameters, flux and Ferro alloys charging control, main and sub lance position control etc. This works in conjunction with electric controls including thyristor converters and programmable logic controller for sequential and safe operation of process equipment. SLAG YARD: The estimated slag arising is about 2000 kg per ton of cast bloom and one slag pot of 16M3_18M3 is adequate for one heat. The filled slag pot fTom the converter is transported to slag yard by self propelled slag transfer car. Two 100+20 T EOT cranes, lime spraying unit, 10T steel ball, slag dump car etc., are provided. Pits are provided for dumping, cooling and crushing: Operation of dump car provided with tilting mechanism is controlled fTom a control post. There are four lime-spraying points. After cooling, the slag cakes are broken by 10T steel ball by magnet crane. The steel jams are used as plant return scrap. Broken slags are removed fTom pit by shovel, pay loader and loaded into dumpers for disposal by road. The total area required for slag dumping is about 9800 sq.m. In

the slag yard of about 8280 sq.m. is available. Therefore, an additional area of about 1500 sq.m. is provided by extension of slag yard 96 M toward end.. SCRAP PROCESSING AND STORSGE YARDS: Plant returns scrap and purchased are stored here. There are two yards. In yard nO.1 about 38,000 T/yr. Of steel scrap is cut to require and has two 1ST magnet cranes. In scrap yard no.2 about 60,000 T/yr. Of scrap is processed. This yard has four 1ST magnet cranes. The sized purchased scrap is received by rail. This yard can store about 19 days stock. Oxy-acetylene torches and 02 lancing do cutting of scrap. An alligator type scrap-cutting shear is provided in each yard for preparing scrap to be added during argon rinsing. Self-loading and unloading trucks will be used for transport of scrap to SMS. SKULL BREAKER: About 52,000 T of steel and iron-scrap is processed here. A 20 t overhead crane with detachable magnet is used for dropping a 10 T steel ball to break the ladle skull and other pieces. A 50/20 T crane with detachable magnet is used for lading and unloading of wagons and for supplying and removing scrap fTom the crushing pit. Oxy-acetylene torches do cutting.

Section through the BOF vessel during oxygen blowing.