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Bathinda thermal power plant mid semester report


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Bathinda thermal power plant mid semester report

  1. 1. Page | 1 Guru Nanak Dev Thermal Power Plant is a coal-based plant. The requirement of coal for four units based on specific fuel consumption of 0.60 kg / kWh. The conveying and crushing system will have the same capacity as that of the unloading system. The coal comes in as large pieces. This coal is fed to primary crushers, which reduce the size of coal pieces from 400mm to 150mm. Then the coal is sent to secondary crusher through forward conveyors where it is crushed from 150mm to 200mm as required at the mills. Then the coal is sent to boilers with the help of primary fans. The coal is burnt in the boiler. Boiler includes the pipes carrying water through them; heat produced from the combustion of coal is used to convert water in pipes into steam. This steam generated is used to run the turbine. When turbine rotates, the shaft of generator, which is mechanically coupled to the shaft of turbine, gets rotated so, three phase electric supply is produced. The basic requirements are:- ♣ Fuel (coal) ♣ Boiler ♣ Steam turbine ♣ Generator ♣ Ash handling system ♣ Unit auxiliaries INTRODUCTION
  2. 2. Page | 2 Due to high rate of increasing population day by day, widening gap between power demand and its availability was one the basic reason for envisaging the G.N.D.T.P. for the state of Punjab. The other factors favoring the installation of the thermal power station were low initial cost and comparatively less gestation period as compared to hydro electric generating stations. The foundation stone of G.N.D.T.P. at bathinda was laid on 19th November 1969, the auspicious occasion of 500th birth anniversary of great Guru Nanak DevJi. The historic town of bathinda was selected for this first and prestigious thermal project of the state due to its good railway connections for fast transportations of coal, availability of canal water and proximity to load center. The total installed capacity of the power station 440MW with four units of 110MW each. The first unit of the plant was commissioned in September, 1974. Subsequently second, third and fourth units started generation in September 1975, March 1978, and January 1979 respectively. The power available from this plant gives spin to the wheels of industry and agricultural pumping sets. BRIEF HISTORY OF PLANT
  3. 3. Page | 3 The selection of site for Thermal Power Plant is more difficult compared to Hydro Power Plant, as it involves number of factors to be considered for its economic justification. The following consideration should be examined in detail before selection of the site for the Plant. The location for plant should be made with full consideration not only of the trends in the development and location but also the availability and location of the cheapest source of primary energy:-  Availability of fuel  Ash disposal facilities  Space requirement  Nature of land  Availability of labour  Transport facilities  Public society problems  Development of Backward Area SITE SELECTION
  4. 4. Page | 4 Guru Nanak Dev Thermal Plant, Bathinda, in addition to indirect contribution in various facts of state economy, is also responsible for:- Narrowing the gap between power demand and power availability of the state. Providing employment potentials to thousands of workers. Covering the backward surrounding area into fully developed IndustrialTownship. Providing additional relief to agricultural pumping sets to meet the irrigation needs for enhancing the agriculture production. Reliability and improvement in continuity of supply and system voltage. Achieving cent percent rural electrification of the state. CONTRIBUTION OF THE PLANT
  5. 5. Page | 5 PROJECT AREA:- Power plant 238 acres Ash disposal 845 Lake 180 Residential colony 285 Marshalling yard 256 Total area 1804 TOTAL COST: - Rs. 115 crores STATION CAPACITY: - four units of 110MW.each BOILER:- Manufacturers B.H.E.L. Maximum continuous rating (M.C.R.) 375 T/hr. Superheater outlet pressure 139 kg/cm² Reheater outlet pressure 33.8 kg/cm² Final superheater/reheater temperature 540 C Feed water temperature 240 C Efficiency 86% Coal consumption per day per unit 1400 tones (Approximate) PLANT SALIENT FEATURES THE PLANT
  6. 6. Page | 6 STEAM TURBINE:- Manufacturers B.H.E.L. Rated output 110 MW. Rated speed 3000 r.p.m. Number of cylinders three Rated pressure 130 kg/cm² Rated temperature 535 C Condenser vacuum 0.9 kg/cm² GENERATOR:- Manufacturers B.H.E.L. Rated output (Unit- 1 & 2) 125000KVA (Unit -3 & 4) 137000KVA Generator voltage 11000 volts Rated phase current (unit –1 & 2) 6560 Amps. (unit –3 & 4) 7220 Amps. Generator cooling hydrogen BOILER FEED PUMPS:- Number per unit two of 100% duty each Type centrifugal Rated discharge 445 T/hr. Discharge head 1960 MWC.
  7. 7. Page | 7 Speed 4500 r.p.m. CIRCULATING WATER PUMPS:- Numbers for two units five of 50% duty each Type mixed flow Rated discharge 8600 T/hr. Discharge head 24 MWC. COOLING TOWERS:- Numbers four Water cooled 18000 T/hr. Cooling range 10 C Height 120/12metres COAL PULVERISING MILLS:- Numbers three per unit Type drum-ball Rated output 27 T/hr. Coal bunkers 16 per unit RATING OF 6.6 KV AUXILLIARY MOTORS:- Coal mill 630 KW Vapour fan 320 KW
  8. 8. Page | 8 C.W. Fan 800/746 KW Coal crusher 520 KW Primary air fan 320 KW Forced draught fan 320 KW Boiler feed pump 3500 KW Induced draught fan 900/1000 KW Condensate pump 175 KW
  9. 9. Page | 9 Coal received from collieries in the rail wagon is mechanically unloaded by Wagon Tippler and carried by belt Conveyor System Boiler Raw Coal Bunkers after crushing in the coal crusher. The crushed coal when not required for Raw Coal Bunker is carried to the coal storage area through belt conveyor. The raw coal feeder regulates the quantity of coal from coal bunker to the coal mill, where the coal is pulverized to a fine powder. The pulverized coal is then sucked by the vapour fan and finally stored in pulverized coal bunkers. The pulverized coal is then pushed to boiler furnace with the help of hot air steam supplied by primary air fan. The coal being in pulverized state gets burnt immediately in the boiler furnace, which is comprised of water tube wall all around through which water circulates. The water gets converted into steam by heat released by the combustion of fuel in the furnace. The air required for the combustion if coal is supplied by forced draught fan. This air is however heated by the outgoing flue gases in the air heaters before entering the furnace. The products of combustion in the furnace are the flue gases and the ash. About 20% of the ash falls in the bottom ash hopper of the boiler and is periodically removed mechanically. The remaining ash carried by the flue gases, is separated in the electrostatic precipitators and further disposed off in the ash damping area. The cleaner flue gases are let off to atmosphere through the chimney by induced draught fan. The chemically treated water running through the water walls of boiler furnace gets evaporated at high temperature into steam by absorption of furnace heat. The steam is further heated in the super heater. The dry steam at high temperature is then led to the turbine comprising of three cylinders. The thermal energy of this steam is utilized in turbine for rotating its shaft at high speed. The steam discharged from high pressure (H.P.) turbine is returned to boiler reheater for heating it once again before passing it into the medium pressure (M.P.) turbine. The steam is then let to the coupled to turbine shaft is the rotor of the generator, which produces electricity. The power from the generator is pumped into power grid system through the generator transformer by stepping up the voltage. WORKING OF THERMAL PLANT
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  11. 11. Page | 11 The steam after doing the useful work in turbine is condensed to water in the condenser for recycling in the boiler. The water is pumped to deaerator from the condenser by the condensate extraction pumps after being heated in the low pressure heater (L.P.H) from the deaerator, a hot water storage tank. The boiler feed pump discharge feed water to boiler at the economizer by the hot flue gases leaving the boiler, before entering the boiler drum to which the water walls and super heater of boiler are connected. The condenser is having a large number of brass tubes through which the cold water is circulated continuously for condensing the steam passing out sides the surface of the brass tubes, which has discharged down by circulating it through the cooling tower shell. The natural draught of cold air is created in the cooling tower, cools the water fall in the sump and is then recirculated by circulating water pumps to the condenser.
  12. 12. Page | 12 BOILER FEED PUMP:- As the heart is to human body, so is the boiler feed pump to the steam power plant. It is used for recycling feed water into the boiler at a high pressure for reconversion into steam. Two nos. 100% duty, barrel design, horizontal, centrifugal multistage feed pumps with hydraulic coupling are provided for each unit. This is the largest auxiliary of the power plant driven by 3500 KW electric motor. The capacity of each boiler at GURU NANAK DEV THERMAL PLANT is 375 tones/hr. The pump which supplies feed water to the boiler is named as boiler feed pump. This is the largest auxiliary in the unit with 100% capacity which takes suction of feed water from feed water tank and supplies to the boiler drum after preheating the same in HP-1, HP-2 and economizer. The delivery capacity of each boiler feed pump is 445 tones/hr. to meet better requirements corresponding to the various loads, to control steam temperature, boiler make up water etc. The detailed particulars checking of protections and inter locks, starting permission etc. are as below:- Particulars of BFP and its main motor:-  BOILER FEED PUMP: - The 110 MW turboset is provided with two boiler feed pumps, each of 100% of total quantity. It is of barrel design and is of horizontal arrangement, driven by an electric motor through a hydraulic coupling. Type 200 KHI No. of stages 6 Delivery capacity 445 t/hr. Feed water temperature 158 C Speed 4500 rpm Pressure at suction 8.30 kg/cm² Stuffing box mechanical seal Lubrication of pump by oil under pressure And motor bearing supplied by hydraulic coupling Consumption of cooling water 230 L/min. GENERAL DESCRIPTION
  13. 13. Page | 13 WATER TREATMENT PLANT:- The water before it can be used in the boiler has to be chemically treated, since untreated water results in scale formation in the boiler tubes especially at high pressure and temperatures. The water is demineralised by Ion Exchange Process. The water treatment plant has production capacity of 1800 Tonnes per day for meeting the make-up water requirement of the power station. COAL MILL:- Coal Mill pulverizes the raw coal into a fine powder before it is burnt in the boiler furnace. The pulverizing of coal is achieved with the impact of falling steel balls, weighing 52.5 tonnes, contained in the mill drum rotating at a slow speed of 17.5 r.p.m. The raw coal is dried, before pulverizing, with inert hot flue gases tapped from the boiler. Three coal mills each with a pulverizing capacity of 27 T/hr. are provided for one unit. INDUCED DRAUGHT FAN:- Two nos. axial flow Induced Draught Fans are provided for each unit to exhaust ash laden flue gases from boiler furnace through dust extraction equipment and to chimney. The fan is driven by an electric motor through a flexible coupling and is equipped with remote controlled regulating vanes to balance draught conditions in the furnace. The fan is designed to handle hot flue gases with a small percentage of abrasive particles in suspension. CONTROL ROOM:- The control room is the operational nerve center of the power plant. The performance of all the equipments of the plant is constantly monitored here with the help of sophisticated instrumentation and controllers. Any adverse deviation in the parameters of various systems is immediately indicated by visual and audio warning and suitable corrective action is taken, accordingly. The control room is air conditioned to maintain the desired temperature for proper functioning of the instruments.
  14. 14. Page | 14 WAGON TIPPLER:- The coal received from the collieries, in more than 100 rail wagons a day, is unloaded mechanically by two nos. wagon tipplers out of which one serves as a standby. Each loaded wagon is emptied by tippling it in the underground coal hopper from where the coal is carried by conveyor to the crusher house. Arrangements have been provided for weighing each rail wagon before and after tippling. Each tippler is capable of unloading 6-8 rail wagons of 55 tonnes capacity in an hour. CRUSHER HOUSE:- Coal unloaded by the wagon tippler is carried to crusher house through conveyors for crushing. Two nos. hammer type coal crushers are provided, which can crush coal to a size of 10 mm. The crushed coal is then supplied to Boiler Raw Coal Bunkers. The surplus coal is carried to coal storage area by series of conveyors. Crushing of coal is an essential requirement for its optimum pulverizing and safe storage. COOLING TOWERS:- Cooling Towers of the power plant are the land mark of the BathindaCity even for a far distance of 8-10 kilometers. One cooling tower is provided for each unit for cooling 18000 tones of water per hour by 10 C. cooling towers are massive Ferro-concrete structure having hyperbolic profile creating natural draught of air responsible for achieving the cooling effect. Cooling tower is as high as 40 storey building.
  15. 15. Page | 15 BOILER:- It is a single drum, balanced draught, natural circulation, reheat type, vertical combustion chamber consists of seamless steel tubes on all its sides through which water circulates and is converted into steam with the combustion of fuel. The temperature inside the furnace where the fuel is burnt is of the order of 1500 C. The entire boiler structure is of 42meter height. BOILER CHIMNEY:- The flue from the boiler, after removal of ash in the precipitators, are let off to atmosphere through boiler chimney, a tall ferro-concrete structure standing as high as the historic QutabMinar. Four chimneys, one for each unit, are installed. The chimney is lined with fire bricks for protection of ferro-concrete against hot flue gases. A protective coating of acid resistant paint is applied outside on its top 10 meters. CIRCULATING WATER PUMP:- Two nos. of circulating water pumps provided for each unit, circulate water at the rate of 17200 T/hr. in a closed cycle comprising of Turbine Condenser and CoolingTower. An additional Circulating Water Pump provided serves by for two units. The water requirement for bearing cooling of all the plant auxiliaries is also catered by these pumps.
  16. 16. Page | 16 Since G.N.D.T.P. units are primarily coal fired units so each boiler is provided with closed milling circuits to pulverize the raw coal which is received from coal conveying system after coal crushes before it is fired in the furnace. The necessity of pulverizing the coal is to be ensuring its maximum possible combustion in the furnace. The coal data for units are: - COAL DATA UNITS 1 & 2 UNITS 3 & 4 Type of Coal Net Calorific Value Moisture Ash Content Volatile Matter Incombustible Inlet of Coal Bituminous 4300 Kcal/kg 10 % 30 % 24 % 10 mm Bituminous 4727 Kcal/Kg 7.5 % 32 % 27 % 20 mm Raw coal of maximum size 10 mm – 20 mm is pulverized in the milling circuit and the output from the mill is fine coal. COAL MILLING PLANT
  17. 17. Page | 17 COAL MILL:- These are mainly of two types:- i) Ball Mills ii) Bowl Mills Ball Mills: -In Ball Mills there are steel balls which are revolving in horizontal cylindrical drum. These balls are free from any shaft and balls are touching with each other and with internal body of drum. These types of mills are at Bathinda Thermal Plant. On the other hand, bowl mills part of the mill contain drive system i.e. it contains 6.6 kV electric motor and gear system which translates the revolution about horizontal axis to revolve about vertical axis. The revolving vertical axis contains a bowl about the driving system. This bowl is fixed with driving and revolving with shaft. There are also three rollers which are suspended at some inclination, so that there is a gap of few mm between roller surface. These rollers are free to rotate about the axis. Bowl Mills: - The coal is grinded and then fed into the mill at the center or near of revolving bowl. It passes between the grinding ring in revolving bowl and rolls as
  18. 18. Page | 18 centrifugal force causes the material to travel towards the out perimeter of bowl. The springs, which load the rolls, impart the necessary force for grinding. The partially pulverized coal continue going up and down and over the edge of bowl. WAGON TIPPLER: The tippler is designed to work on the following cycle of operation:- Tipping 90 seconds Pause 5-12 seconds Return 90 secondS Weighing 30 seconds Total 215-222 seconds Allowing 85 seconds for wagon changing it will be seen that 12 eight-wheel wagons or 24 four-wheel wagons per hours can be tipped. However since the coal carrying capacity is 500 tones per hour load of 12 wagons comes to 8 to 9 per hour. CRUSHER HOUSE:- The crusher house accommodates the discharge ends of the conveyor 4A, 4B receiving ends of conveyor 5A, 5B and conveyor 7A and 7B, two crushers, vibrating feeders and
  19. 19. Page | 19 necessary chute work. There are two crushers each driven by 700H.P. electric motor, 3 phase, 50 cycles and 6.6 kV supply. The maximum size of the crushed coal is 10mm. The capacity of each crusher is 500 tones/hr. one crusher works at a time and the other is standby. From the crusher the coal can be fed either to the conveyors 5A, 5B or 7A, 7B by adjusting the flap provided for this purpose. There is built in arrangement of bypassing the crusher by which the coal can be fed directly to the conveyors bypassing crusher. CONVEYOR BELT AND CRUSHER HOUSE
  20. 20. Page | 20 It is main part of STEAM GENRATOR’ it is an assembly of a large no. of vertical riser tubes embedded in refractory walls. There are two boilers one for each unit. The type of the boiler is NATURAL CIRCULATION RADIENT SINGLE REHEAT boiler. The four refectory walls make a closed box called FURANCE.The walls are given special names. These are; 1. RIGHT WALL consisting 130 TUBES. 2. LEFT WALL consisting 130 TUBES. 3. FRONT WALL consisting 181 TUBES. 4. REAR WALL consisting 181 TUBES. BOILER SECTION
  21. 21. Page | 21 On the right and left wall, the WIND BOXES are installed. Thus there are Four Furnace Coroners. FRONT WALL (181) REAR WALL(181) The water tubes cool the walls by absorbing the heat and transferring it to the water running in them. The tubes are embedded in refectory walls very close (the Gap between two tubes is 10 mm). The inner diameter of the tubes is 63.5mm. JUSTIFICATION OF THE BOILER TYPE; The type of boiler is WATER TUBE, NATURAL CIRCULATION, RADIENT SINGLE REHEAT boiler. The meaning of each word has been explained below; WATER TUBE; It mean the water runs in the tubes and the fire is outside the tubes. NATURAL CIRCULATION; The CIRCULATION word mean how the water is raised in the walls. We know that the water upwards we have to supply some external power e.g., some pump system’ But here a law dose this work naturally. The saturated water collected at the bottom known as RING HEADER. The water rises from it in riser pipes naturally. There is a TWO PHASE MIXTURE of WATER and STEAM in risers. There is a DIFFERENCE BETWEEN the DENSITIES of the MIXTURE and SATURATED WATER in Ring Header. Also there is a STATIC HEAD. Due to the result of both factors there is NATURAL CIRCULATION operates in boiler. RADIENT TYPE: As the name implies, the heat is transferred from combustion gas to the water by RADIATION. The heat is then CODUCTED to water tubes and through the thickness of tubes. There is CONVECTED to the TWO PHASED MIXTURE. SINGLE REHEAT; It implies that the system is reheated only once . When the steam goes to H Turbine its temperature decreases from 540 deg to 343 deg. It is then send to reheater to increase the temp to again 540 deg.
  22. 22. Page | 22 1. It should be absolutely reliable and capable of raising maximum amount of steam for minimum fuel consumption, attention, initial cost and maintenance charges. 2. It should be light in weight and should occupy small space. 3. It should be capable of quick starting and meeting rapidly large variation of load demands. 4. The water surface and tube should be so arranged so as to avoid priming. 5. The tubes should not accumulate soot or water deposits. 6. The refractory system should be as little as possible, but sufficient to secure easy ignition and smokeless combustion of fuel on reduced load. Manufacturers B.H.E.L Maximum continuous rating 375 T/ hr Superheater outlet Pressure 139 Kg/cm2 Final Superheater Temp. 5400C Feed Water Temp. 2400C Efficiency 86% Coal Consumption Per day 1400 tones (approx.)
  23. 23. Page | 23 Spending my six months of training in Guru Nanak Dev Thermal Plant, Bathinda, I concluded that this is a very excellent industry of its own type. They have achieved milestones in the field of power generation. They guide well to every person in the industry i.e. trainees or any worker. I had an opportunity to work in various sections namely switch gear, Boiler section, Turbine section, De-mineralized water plant, E.S.P, EM-2 CELL etc. while attending various equipments and machines. I had got an endeverous knowledge about the handling of coal, various processes involved like unloading, belting, crushing and firing of coal. The other machines related to my field that I got familiar with boiler, turbine, compressors, condenser etc. I found that there existed a big gap between the working in an institute workshop and that in the industry. Above all the knowledge about the production of electricity from steam helped me a lot to discover and sort out my problems in my mind related to the steam turbine, their manufacture, their capacity, their angle of blades and their manufacturing. The training that I had undergone in this industry will definitely help me to apply theoretical knowledge to the practical situation with confidence. CONCLUTION
  24. 24. Page | 24 1. A Textbook of electrical technology (A.C & D.C Machines) – B.L.THERAJA, A.K.THERAJA 2. A coursein electricalpower: -J.B.GUPTA 3. A course in electrical & electronic measurement and instrumentation: -A.K.SAWHNEY 4. A course in electrical power: -M.L.SONI, P.V.GUPTA 5. A textbook of power plant engineering: - Er. R.K.RAJPUT 6. 7. 8. Manual of GURU NANAK DEV THERMAL PLANT, BATHINDA BIBLIOGRAPHY