Report On Ntpc Industrial Training At Barh(patna) 495x41

REPORT ON INDUSTRIAL TRANING Prepared By

Kumar Gautam (11M168)

DEPARTMENT OF MECHANICAL ENGINEERING NATIONAL INSTITUTE OF TECHNOLOGY KARNATAKA SURATHKAL, MANGALORE-575025

CONTENTS 01.Acknowledgements. 02.Introduction of NTPC project. 03.Salient Data And Design Specification Of NTPC BARH 04.Working principle of the thermal power plant. 05.Boiler and Auxiliary.  Boilerdrum&internal......................................................  Superheater circuit..........................................................  Re-heater circuit..............................................................  Economiser......................................................................  Furnace............................................................................  PA fans.............................................................................  FD fans.............................................................................  ID fans..............................................................................  Air Heater.........................................................................  Pulveriser Plant................................................................. 06.Turbine. 07.General Description of The A 210mw (KWU) Steam Turbine. 08.Regenerative feed heating system. 09.Coal & coal handling system. 10.Conclusion.

ACKNOWLEDGEMENT

I would like to express my sincere gratitude to the management of the BARH THERMAL POWER STATION for having given this opportunity to carry out my vacation training.

I am grateful to Mr. ANURAG SINGH for his kind cooperation and helping me in gaining better practical knowledge about the way how steam produced and used to generate power.

I would like to pay my sincere gratitude to all the employee and staff of NTPC BARH for their valuable help and technical .

Finally, I would like to thank the Staff and Management of NTPC,BARH for helping me in my industrial training and their kind cooperation for gaining better practical knowledge.

INTRODUCTION OF NTPC BARH (PATNA)

Barh Super thermal power project details Capacity 3300 MV – first stage (3×600) and second stage (2×660) Estimated cost of the Project 16034 cr. (approx.) Land required Main plant and township 1268 acres, ash dyke and other 1906 acres Requirement of Coal 17.72 metric ton per year Source of Coal is Amrapali block north karnpura coalfield and Source of Water is Ganga River (180 qc ) Benefices State Bihar and Other States/ North and West union territories NTPC generates power from Coal and Gas. With an installed capacity of 30,644 MW, NTPC is the largest power generating major in the country. It has also diversified into hydro power, coal mining, power equipment manufacturing, oil & gas exploration, power trading & distribution.

SALIENT DATA AND DESIGN SPECIFICATION OF NTPC BARH ‘A’ TPS 3300MW SALIENT DATA:

     

Capacity Project cost Steam generator (boiler and aux.) Coal consumption Cooling water Transportation of the coal

3300MW(3x600 & 2x660) Rs.16034.crores M/s.BHELINDIA, 17.72 metric tone/annum 180 qc Rly. System

DESIGN PARAMETERS: BOILER: REHEAT STEAM:

 Flow  Steam pressure  Steam temperature

1900T/hr. 37.6 to 36.1 1500°

FEED WATER:

 Temperature at LOC inlet  Pressure at ECO inlet  Rate of flow ECO inlet

242°C 180 655T/hr.

FUEL:

       

F or E grade bituminous coal of C.V. Fixed carbon Volatile matter Moisture HGI Initial deformation temperature Fusion temperature Pulverisers

3750kcal/kg 28% to 21% 11% to 15% 33% to 40% 55 1350°C to 1150°C 1400°C 6 nos.

 Pulveriser XRP

803

TURBINE AND GENERATOR:

STEAM TURBINE: reaction, condensing, reheating, compound, three cylinders regenerative, throttle governed.       

Rate output Speed Pressure of the steam at inlet to ESV Temperature of the steam at inlet to ESV Condenser area Circulating water flow Condenser vacuum

horizontal

tendem

2 10000kW 3000rpm 150 535°C 11495 27000 -0.89

Feed heating system: extraction steam parameters TEMPERATURE (°C)

PRESSURE (�� ���)

FLOW T/hr.

LPH 1

84.4%dry

0.2135

3.545

LPH 2

100.0

0.8107

29.40

LPH3

199.0

2.4500

28.40

HPH5

432.2

16.100

33.36

HPH6

336.6

36.560

57.40

GENERATOR: generator 247MVA, PF 0.85 (lag), thermal voltage 15.75kV, rotor hydrogen cooling and stator water cooled.  

Seal oil pressure Hydrogen pressure

4.8 to 5.8 3.0 to 3.5

 

Stator water pressure Stator water conductivity

2.5 to 2.8 ≤1.0µ mho/cm

(hydrogen purity 98.8%)

WORKING PRINCIPLE OF THE THERMAL POWER PLANT Thermal Power Plant:-The plant in which chemical energy is converted to electrical energy. Chemical Energy →Heat Energy →Mechanical Energy →Electrical Energy Basic cycle at which thermal power plant is working is Rankine cycle. The Rankine is the ideal cycle for vapour power plant. The ideal Rankine cycle does not involve any internal irreversibility and consist following four processes. I. II. III. IV.

1-2 isentropic compression in the pump 2-3 constant pressure heat addition in the boiler 3-4 isentropic expansion in turbine 4-1 constant pressure heat rejection in the condenser

The actual vapour power cycle differs from the ideal Rankine cycle, as illustrated in fig. as a result of the irreversibility in various components. Fluid friction and heat loss to the surrounding are two common sources of the irreversibility. In the Thermal Power Plant modified form of the Rankine Cycle is use. Modification  By using of reheat  By using of regenerate  By using both regenerate and reheat

REGENERATING RANKINE CYCLE

A practical regenerating process in steam power plant is accomplished by extracting, or bleeding steam from the Turbine at various point, this steam which could have produced more work by expanding further in the Turbine, is used to heat the feed water instead. The device where the feed water is heating is heated by regeneration is called regenerator or FWH (feed water heater).

Regeneration is not only improving cycle efficiency but also provide a convenient means of desecrating the feed water to prevent corrosion in the Boiler . REHEATING RANKINE CYCLE

In reheating cycle, in between two Turbines we reheat the steam and then supply for the next Turbine. There are two major advantages, Average temperature at which heat is increase, thus increase in the cycle efficiency. Reheat is a practical solution to the excessive moisture problem in the Turbine.

BOILER: A boiler, also called steam generator, is designed so that heat transfer takes place between boiler tube bundles (also called U bundles) and boiler water in the boiling area. If the U bundles are not completely submerged, the heat transfer area, hence heat transfer rate, hence heat sink capability decreases. BOILER PARTS AND AUXILIARY DRUM AND DRUM INTERNAL: The functions of the boiler drum are. A) Separation of the saturated steam from the steam-water mixture produced by evaporating tubes. B) Mixing feed water from economiser and water separated from steam –water mixture, and recirculation through the tubes. C) Carrying out blow down for reduction of the boiler water salt concentration. D) Treatment of the boiler water by chemical. STEAM SEPARATOR: In recirculation type of the boiler the evaporating tube supply only a steam-water mixture to the drum. From this, the steam of high purity acceptable to the super heater and turbine is to be separated. This separation is to be done in the limited space in the drum. Numbers of the factors influence the separation of the water from the steam in drum; important among them are:      

The density of the water with respect to the steam. The amount of the water in the mixture delivered to drum. Viscosity, surface tension and other factor affected by pressure Water level in the drum The concentration of boiler water solids The available pressure drop from drum internal design

In this power plant TURBO SEPARATORS are use (95 separators).

SUPER HEATER CIRCUIT: Super heating of the steam is done in 14 stages. These stages having following purpose,  Heating of the steam in stage or increase of the temperature in number of the stage.  In these stages, we also use spray for cooling the steam. RE-HEATER CIRCUIT: Re-heater is use to re-heat the steam for the use of intermediate pressure turbine (at the same pressure of the outlet of the HP turbine). In the re-heater steam comes from HP turbine through CRH L&R (cold re-heat) and after re-heater steam goes to intermediate turbine through HRH L&R (hot re- heat). ECONOMISER: Economisers are provided in the boilers to improve the efficiency of the boiler by extracting the heat from the flue gases and add it as either sensible heat alone or sensible heat and latent heat to the feed water before the water enter the evaporating surface of the boiler. ADVANTAGE: provision of the economiser in the boiler brings two major advantages. 1. As the economiser recovers the heat in flue gas that leaves the boiler. 2. As the feed water is preheated in the economiser. ECONOMISER FAILURE I. II. III.

Over heating Corrosion Erosion

FURNACE: Principle at which furnace work is to convert chemical energy of the fuel into heat energy and this heat transfer to the evaporators. This is the most important part of the boiler. Principle parts of the furnace are, Burner,oil gun,air damper,shoot blower,wind box

ASH HANDLING SYSTEM: For maintaining draft in the furnace we must seal it. That is why we need to dip bottom of the boiler into the water and geared Conveyor are use to flash ash from the bottom with the help of the water.

PRIMARY AIR FANS: These are the large high pressure fans which supply the air needed to dry and transport coal either directly from coal mills to the furnace or to the intermediate bunker. These fans may be located before or after the mills equipment. The most common applications are cold primary air fans and pulveriser exhauster fans.

FORCE DRAFT FANS: Force draft fan supply air necessary for fuel combustion and must be sized to handle the stoichiometric air plus the excess air needed for the proper burning of specific fuel in addition, they provided air to make up for air heater leakage and for some sealing air requirements. INDUCED DRAFT FANS : Induced draft fan evacuate combustion products from the boiler furnace by creating sufficient negative pressure to establish a slight suction in the furnace. Since the I.D. fans have to compensate for the heavy pressure drop of the fuel gas across the boiler contour, the power requirement is very high. As such high efficient fans are demanded for this application. AIR HEATER: Air heater is an important boiler auxiliary, which primarily preheat the combustion air for rapid and efficient combustion in the furnace. The

air heaters recover the waste heat from the outgoing flue gases of the boiler and transfer the same to combustion air.  Air heater improves the boiler efficiency by 2.5%.  Air heater may be also be used for heating the air to dry the coal in the pulveriser plant. Type of the air heater: There are two main type of the air heater. a) Tubular air heater b) Plate type air heater PULVERISER PLANT: Of the three commercial fuels- coal, petroleum, natural gas, and coal is the basic fuel used in the boiler for the power generation due to its distribution and availability. Though coal can be burnt in a boiler in many ways such a hand firing, stoking firing, pulverised coal firing, cyclone furnace etc, and pulverised coal firing is favoured over other methods of burning coal because of many advantages. About 80% of the coals for the generation of electricity are burnt in the pulverised form. FUNDAMENTAL REQUIREMENT OF A PULVERISED PLANT: Supply of coal in the pulverised form to the boiler furnace can be accomplished by using different type of equipment and systems. The use of a particular type of equipment is decided on the type of coal used, boiler requirements, preference etc. 1. 2. 3. 4. 5.

Raw coal feeding Drying Grinding and circulating Classifying Transporting

RAW COAL FEEDERS: A raw coal feeder is a device that supplies the pulveriser with an uninterrupted flow of raw coal from the bunker to meet system requirements. The feeders have to regulate the rate of the coal flow corresponding to boiler load, calorific value of coal etc.

ROTARY VOLUMETRIC FEEDER: in this type of feeder, a spider wheel is keyed to the centre of a feed roll shaft. This shaft extends through a cylindrical core, which form the base of the feed roll. The core is made in two halves, which are bolted to the opposite side of the feeder body, and the spider wheel is placed in between these two halves. Numbers of plates are bolted to the spider wheel along its periphery; these are making number of pockets. When the feeder runs, the coal is received by the pockets formed by the plates and emptied into the pulveriser at a rate, which depends on the speed of the feeder. A hinged levelling gate held in place by spring pressure limits the amount of coal entering each pocket but allows age of foreign material, which might otherwise cause damage to the feeder. PULVERISERS: To effect the coal particle size reduction, needed for pulverised coal firing, machine known as pulverisers or mill are used to grind or comminute the coal. The pulverisers are generally based on rock and mineral-ore grinding machinery. Five major type of coal mills used are tabulated below according to their speed MILL

SPEED

01.Bowl mill 02.Ball mill 03.Impact or hammer mill 04.Bearer wheel mill 05.Drum mill/ tube mill

50-100rpm below 50rpm above 225rpm above 225rpm below 50rpm

BOWL MILL: Bowl mill is a vertical spindle medium speed mill. In a bowl mill the coal is pulverised between a disc called bowl rotated by the drive assembly and rollers kept above the disc loaded by spring loading device. Raymond mill mostly use in Indian Thermal Power Station. Vertically this mill is divided into four major sections; I. Mill base or gear box II. Mill side assembly III. Separator body IV. Separator body top. Coal from the raw coal feeder is fed at the centre of the bowl through a raw coal inlet chute inserted at the centre of the separator body top. Due to centrifugal force the coal moves towards the periphery. The three rolls exert the required grinding pressure through the springs. The primary air supplied to the mill side moves up through the vanes around the bowl. By the deflector liners air is deflected towards the centre of the mill which causes recirculation of coal throughout the grinding area. The airs moving upwards picks fine coal and inter the classifier through the vanes. The vanes introduces spin and as a result course particles get separated from the stream and return through the annulus between the centre of the feed pipe and classifier cone to the bowl for further grinding. Fine coal moves out with air through the multiport assembly at the outlet of the classifier. FACTORS AFFECTING MILL PERFORMANCE:

the performance of the mill plant especially the pulveriser output is affected by number of factor mainly associated with the properties of coal being ground. Important of these factors are 01.Grindability index of coal 02.Fineness of milled product 03.Moisture content 04.Size of the row coal 05.Mill wear

TURBINE: Steam turbine is a rotating machine which converts heat energy of the steam to mechanical energy. WORKING PRINCIPLE OF THE STEAM TURBINE: When the steam is allowed to expand through a narrow orifice, its assumes kinetic energy at the expense of its enthalpy. This kinetic energy changes to mechanical energy through the impact (impulse) or reaction of the steam against the blades. It should be realised that the blade of the turbine obtains no motion force from the static pressure of the steam or from any impact of the steam jet. The blades are designed in such way, that steam will guide on or off the blade without any tendency to strike it.

TURBINE TYPE: Basically there are two broad classifications of the steam turbines,

IMPULSE TURBINE: In the impulse turbine, the steam is expanding in the fixed nozzles. The high velocity steam from the nozzles does work on the moving blades which cause to rotate the shaft. The essential feature of an impulse turbine is that all pressure drops occur in nozzle only and there is no pressure drop in moving blad REACTION TURBINE: in this type, pressure is reduced in both fixed and moving blade. Both fixed and moving blades act like nozzles and are of the same shape. Work is done by the impulse affect due to the reversal of the direction of the high

velocity steam plus a reaction affect due to the expansion of the steam through the moving blades.

CLASSIFICATION OF THE STEAM TURBINE: classification of the steam turbine is done on the basics of the following.  According to the direction of the flow 01.Axial turbine 02.Radial turbine  According to the principle of action of the steam 01.Impulse turbine 02.Reaction turbine.  According to the steam condition at inlet to turbine 01.Low pressure turbine 02.Medium pressure turbine 03.High pressure turbine GENERAL DESCRIPTION OF A 210MW (KWU) STEAM TURBINE: As figure shows sectional arrangements of the 210MW steam turbine of the BHEL/KWU make. 210MW KWU turbine is a tandem compounded, three cylinders, single re-heater, condensing turbine provide entirely with reaction blading. Super heated steam (147 , 535°C) enters the HP turbine through two initial stop valves and control valves. HP cylinders have a throttle control. HP turbine comprise of 25 single flow stages. HP turbine exhaust steam (39.2 , 343°C) goes for reheating and reheated steam (34 , 535°C) comes to the intermediate pressure turbine through the two combined reheat stop and control valves. The lines, leading from the tow HP exhaust branches to re-heater, are provided with swing check valve which prevent hot steam from re-heater flow back into the HP turbine. IPT is a double flow turbine with 20 reaction stages pre flow. From IP turbine, steam goes to double flow LP turbine with 8 reaction stages per flow through cross around pipes. The steam from LPT is exhausted to condenser at a back pressure of 0.1187 bar (49°C). Extraction of the steam is bled from six points (3-LP Heater, 2-HP Heater, 1-Deaerator). The individual turbine rotors and generator rotor are connected by coupling.

KWU Turbine

REGENERATIVE FEED HEATING SYSTEM: The regenerative feed heating system of the 210MW KWU unit consists; I. II. III. IV. V. VI.

One Deaerator Three Low Pressure Heater Two High Pressure Heater One Gland Steam Cooler One Drain Cooler Two Main Ejector

DEAERATOR: The pressure of the curtain gases like oxygen, carbon dioxide, nitrogen, dissolved in water is harmful because of their corrosive attacks on the metal, particularly at elevated, temperature. Thus in the modern high pressure boiler, to prevent internal corrosion, the feed water should be free, as far as practicable, of all dissolved gases, especially oxygen. This is achieved by embodying into the freed system a deaerating unit. Apart from this, a deaerator also servers the following function;  Heating incoming feed water  To act as a reservoir to provide a sudden or instant demand

LOW PRESSURE HEATER: LPH are of the surface types. They are designed for vertical mounting and are welded mild steel construction with U-shaped . Brass tubes, with their ends rolled in steel tube plates. Water flow inside the tube in four paths and the heat steam washes the tube system from outside. The tubes are designed for the full pressure developed by the main condensate extraction pump. The tubes are ed by partition which shall prevent the vibration and also insure the even distribution of the steam.

The main fittings and assemblies on the LPHs I. II. III. IV. V. VI. VII. VIII. IX.

Water box Tube next Shell Water level gauge Lever switch Steam side relief valve Water side relief valve Pressure gauge Dial thermometer

HIGH PRESSURE HEATER: Steam extracted from Turbine is used to heat the feed water going to the Boiler. Feed will flow through the U-tube in two es whereas steam flows on the shell side of the heater. HP heater consists of three zones namely de-super heating zone, condensing zone and drain cooling zone. Steam extracted for from the Turbine first inter into de-super heating zone, where it losses the super heat, latent heat and condensate. This condensate will collected in the bottom of the heater above the tube plates. The condensate inter into the drain cooling zone from the bottom cut out and flow upwards and finally cascaded to deaerator or condenser through flash tank-2, depending upon the load on unit. Condensate losses it’s sensible heat in drain cooling zone. Total feed water first enters drain cooling zone and then condensing zone and finally de-super heater zone.

FITTING; I. II. III. IV. V.

Gauge glass for indicating the drip level Pressure gauge Safety valve shell side Isolating valve High and low level alarm switches

COAL & COAL HANDLING PLANT: coal is a heterogeneous material consisting of the macerals and minerals.

RANKING OF THE COAL: I. II. III. IV.

Anthracite Bituminous Lignite Pit

less than 5% (moisture contain) 10 – 20% 20 - 30 % 30 – 40%

CLASSIFICATION OF THE COAL: GRADE

CALORIFIC VALUE (kcal/kg)

A

6200 & above

B

5600 – 6200

C

4940 – 5600

D

4200 – 4940

E

3660 – 4200

F

2400 – 3660

G

1300 – 2400

CHARACTERISTICS OF THE COAL (use for 210MW):    

Ash Volatility Moisture Calorific value

28% 25.5% 10% 4750kcal/kg

MAIN EQUIPMENTS OF THE COAL HANDLING PLANT: there are following equipment 01.MGR- Mary go round 02.Movable head 03.Paddle feeder and hopper tippler 04.Dust separation and dust extraction 05.Conveyor 06.Magnetic separator and metal detector 07.Weighting system 08.Electro metallic vibrating feeder 09.MBF-mobile belt feeder 10.Primary sampling and secondary sampling

11.Mobile chute/mobile head 12. Movable belt feeder 13. Rail wagon or wagon 14. Hoisting device 15. Primary coal crusher 16. tripper 17. Secondary coal crusher 18. Stacker, reclaimer machine 19. Idler and pulley

CONCLUSION On the completing of my vocational training at Thermal Power Station BARH, I have come to know about how the very necessity of our life nowadays i.e. Electricity is Generated. What all the processes are needed to generate and run the power plant on 24X7 basis.

Water and air are the most precious in the world so we have to save these things by recycling water or decreasing pollution.

Training gave me an opportunity to clean my concepts from practical point of view with the availability of the machinery of such larger rate. Finally as my industrial training came to an end, I felt that this additional knowledge and exposure would certainly help me mould career in the technical field and would also give us that extra bit of advantage and recognition required to enhance my profile.