report thermal

8/3/2019 Report Thermal

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Report

On

Industrial Training

(13th

June to 13th

July)

at

Suratgarh Super Thermal Power Plant

Rajasthan Rajya Vidhyut Utpadan Nigam Limited

submitted for

partially fulfillment ofaward of b.tech degree

in

Mechanical Engineering

of

Rajasthan Technical University, Kota

Submitted to:- Submitted by:-

Mrs. Bhavana Mathur Vikas Kumar Chhimpa

(Head of Department) (B.Tech, 7th Semester)

Global Institute of Technology, Jaipur

ITS-1, IT PARK, Sitapura, Jaipur-302022

(Accredited with A grade by NAAC-UGC)

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ACKNOWLEDGEMENT

Only until you've climbed the mountain can you look behind you and see the

vast distance that you've covered, and remember those you've met along the waywho made made your trek a little easier . Now that this book is finally finished

after the many miles of weary travel, I look back to those who helped me turn itinto a reality and offer my heartfelt thanks:

To my lecturers , friends and employees of SSTPP for their contribution in

completing of my training and preparation of project report successfully.

A special valuable asset was the expect lecture delivered by all thoseengineers who are working in the plant control room.

I am also grateful to safety department for the safety training that helped me

to get safe in the plant.I am grateful to HR department for the assistance they provided me for my

training.I hope this training, which is the fruit of long dedicated hours of efforts &

consistent dedication, will be also be appreciated. No work can be perfect. Iwould like to express my deep gratitude & heartiest thanks to my Head of theDepartment Mrs. Bhavana Mathur & my respective Senior Faculty Member of

the Department & my guiders Mr. Surenra Kumar & Mr. G.D. Sharamawho inspired me with the spirit to work upon challenging field, which has its

inspection in such a time when there is a fire need for new orientation.

Seminar guides:Mr. Madhvendra Saxena

Mr. Naween Jha

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TABLE OF CONTENT

Seri

al

No.

Chapter Page no.

1 PREFACE 4

2 ABOUT PLANT 5

3 SSTPS 6

4 ELETRICITY GENERRATION 7

5 TURBINE 9

6 LUBRICATION OIL SYSTEM 13

7 BOILER 14

8 BOILER FEED WATER CYCLE 199 WATER TREATMENT PLANT 21

10 CONDESTE SYSTEM 24

11 COAL HANDLING PLANT 28

12 ASH HANDLING PLANT 34

13 CONCLUSION 38

14 REFERENCE 39

PREFACE

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As engineers are only confined to theoretical knowledge, the practical training helps as engineers to

enhance their knowledge in practical knowledge. I took my practical training at Suratgarh Super

Thermal Power Station and learnt that how electricity is generated.

The objective of writing this report is to make reader familiar with the generation of electrical power and

the all basic operations involved in it, also to make reader understand various parts of the plant, the

boilers, turbo generators, transformers, coal and ash handling and various types of auxiliary equipments.

I would continue to welcome, in future also the advice and suggestions for improving the text as well as

its usefulness to the readers of this report.

ABOUT PLANT

A thermal power station is a power plant in which theprime moveris steam driven. Water is heated,

turns into steam and spins a steam turbine which drives an electrical generator. After it passes through

the turbine, the steam is condensed in a condenserand recycled to where it was heated; this is known asa Rankine cycle. The greatest variation in the design of thermal power stations is due to the different

4 G.I.T. JAIPUR
http://en.wikipedia.org/wiki/Power_planthttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wiktionary.org/wiki/prime_moverhttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Steam_turbinehttp://en.wikipedia.org/wiki/Electrical_generatorhttp://en.wikipedia.org/wiki/Condensationhttp://en.wikipedia.org/wiki/Surface_condenserhttp://en.wikipedia.org/wiki/Rankine_cyclehttp://en.wikipedia.org/wiki/Power_plant


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fuel sources. Some prefer to use the term energy centerbecause such facilities convert forms ofheat

energy into electricity. Some thermal power plants also deliver heat energy for industrial purposes, fordistrict heating, or fordesalination of water as well as delivering electrical power. A large part of human

CO2 emissions comes from fossil fueled thermal power plants; efforts to reduce these outputs are various

and widespread.

Installed capacity

.

Stage Unit Number Installed Capacity (MW) Date of Comisioning Status

Stage I 1 250 May, 1998 RunningStage I 2 250 March, 2000 Running

Stage II 3 250 October, 2001 Running

Stage II 4 250 March, 2002 Running

Stage III 5 250 June, 2003 Running

Stage IV 6 250 March, 2009 Running

ABOUT SSTPS PLANT

INSTALLED CAPACITY 1500 MW (6*250)

5 G.I.T. JAIPUR
http://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/District_heatinghttp://en.wikipedia.org/wiki/District_heatinghttp://en.wikipedia.org/wiki/Desalinationhttp://en.wikipedia.org/wiki/Watt#Megawatthttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/District_heatinghttp://en.wikipedia.org/wiki/Desalinationhttp://en.wikipedia.org/wiki/Watt#Megawatt


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LOCATION 27 KSOUTHEASTOFSURATGARH

TOTAL LAND ACQURED 5020 (BIGHA)

PLANT AREA 3810 (BIGHA)

COLONY AREA 431 (BIGHA)

RAILWAY SITE 425 (BIGHA)

HEIGHT OF BOILER 60 (METERS)

HEIGHT OF CHIMNEY 220 (METERS)

FOUNDATION DEPTH 8.5 (METER)

LENGTH OF INTAKE CANAL 1.6 KM(Indira Gandhi Canal)

ELECTRICITY GENERATION

AT SSTPS

Super Thermal Power Station burns the fuel and use the heat to raise the steam, which drives the turbo-generator. The fuel may be Fossil (Coal Oil Natural Gas) whichever fuel is used object is same, to

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convert to heat in to mechanical energy then to electrical energy by rotating a magnet inside the set of

winding. In a coal fired Super Thermal Power Station other raw materials are air and water. The coal isbrought to station by trains or other means travels from the coal handling system.

By conveyer belts to coal bunkers from where it is fed to pulverizing mills.

Mills grind it fine as face powder.

Then powdered coal mixed with preheated air is blown into boiler by a fan known as primary

air fan(PA Fan). When it burns more like a gas as solid in conventional domestic or industrial grate with

additional amount of air called secondary air supplied by Forced Draft Fan. As the coal has

been grinded so resultant ash is also as fine as powder. Some of its fine particle binds

together to form lumps, which fall into the ash pit at the bottom of furnace.

The water quenched ash from the bottom of furnace is carried out boiler to pit for subsequent

disposal.

Most of ash still in fine particles form is carried out to Electro Static Precipitators where it istrapped by electrodes charged with high voltage electricity. The dust is then conveyed to the

disposal area or to bunkers for sale.

Now after passing through ESP flue gases discharged up to chimney by Induced Draft

Fans.

Meanwhile kilometers long tubes have absorbed the heat reloaded from the coal, which lie in boilerwalls inside the tubes Boiler Feed Water which is transferred into turbine blades and rotate them . To

the end of turbine, rotor of generator is coupled, so that when the turbine rotates the rotor turns with it.

The rotor is housed inside the stator having coil of copper bars in which electricity is produced throughthe movement of magnetic field created by rotor. The electricity passes from the stator winding to the

transformer, which steps up the voltage so that it can be transmitted effectively over the power line of

grid.

The steam, which has given up its heat energy in, changed back into a condenser so that it is ready

for reuse. The cold water is continuously pumped in condenser. The steam passing around the tubes

losses heat and changes into water. But these two types of water (boiler feed water and cooling water)must never mix together. The cooling water is drawn from the river but the Boiler Feed Water must be

pure than the portable water (DM Water).

PLANT OVERVIEW

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TURBINE

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STEAM TURBIN E

I NTRODUCTION

Turbine is a machine in which a shaft is rotated steadily by impact or reaction of current or steam

of working substance (steam, air, water, gases etc.) up on blades of wheel. It converts the potential or

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kinetic energy of the working substance into mechanical power by virtue of dynamic action of working

substance. When the working substance is steam it is called the steam turbine.

PRINCIPLE OF OPERATION OF STEAM TURBINE :

Working of the steam turbine wholly depends upon the dynamic action of steam. The steam is

caused to fall in pressure in a passage of nozzle due to this fall in pressure a certain amount of heatenergy is converted into mechanical and then to kinetic energy and the steam is set moving with agreater velocity. The rapidly moving particles of steam, enter the moving part of turbine and here suffer

a change in direction of motion which gives rose to change of momentum and therefore to a force. This

constitutes the driving force of the machine. The processor of expansion and direction changing mayoccur once or a number of times in succession and may be carried out with difference of detail. The

passage of steam through moving part of the commonly called the blade is equal to that at the inlet

inside. Such a turbine is broadly termed as impulse turbine.

On the other hand the pressure of the steam at the outlet from the moving blade may be less than

that at the inlet side of the blades. The drop in pressure suffered by the steam during its flow through the

moving causes a further generation of kinetic energy within the blades and adds to the propelling forcewhich is applied to the turbine rotor. Such a turbine is broadly termed as impulse reaction turbine .

The majority of the steam turbine have therefore two important elements or sets of suchelements. These are

the nozzle in which the system expands from high pressure and a state of comparative rest to a

lower pressure and a status of comparatively rapid motion.

The blade or deflector, in which the steam particle changes its directions and hence its

momentum changes. The blades are attach to the rotating elements are attached to the stationary

part of the turbine which is usually termed as The Stator, Casing or Cylinder.Although the fundamental particles on which all steam turbine operate the same, yet the methods where

by these principles carried into effect very end as a result, certain types of turbine have come intoexistence.

Simple Impulse Steam Turbine.

Pressure Compounded Impulse Turbine.

Simple Velocity Compounded Impulse Turbine.

Pressure-Velocity Compounded Turbine.

Pure Reaction Turbine.

Impulse Reaction Turbine.

1) Steam flow :

250 MW steam turbine is a tandem compound machine with HP, IP and LP parts. The HP part is

single flow cylinder, IP & LP parts are double flow cylinders. The individual turbine rotors andgenerator rotors are rigidly coupled. The HP cylinder has a throttle control. Main steam is admitted

before blending by two combined and main stop & control valves. The HP turbine exhaust (CRH)

leading to reheated have low swing check valves that prevent back flow of hot steam from reheated into

HP turbine. The steam coming from reheated called HRH is passed to turbine via. Two combined stopand control valves. The IP turbine exhausts directly goes to LP turbine by cross ground pipes.

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2) HP Turbine :

The HP casing is a barrel type casing without axial joint. Because of its rotation symmetry the

barrel type casing remain constant in shape and leak proof during quick change in temperature. The

inner casing too is cylindrical in shape as horizontal joint flange are relieved by higher pressure arisingoutside and this can kept small. Due to this reason barrel type casing are especially suitable for quick

start up and loading.The HP turbine consists of 25 reaction stages. The moving and stationary blades are inserted intoappropriate shapes into inner casing and the shaft to reduce leakage losses at blade tips.

3) IP Turbine:

The IP part of turbine is of double flow construction. The casing of IP turbine is split

horizontally and is of double shell construction. The double flow inner casing is supported kinematicallyin outer casing. The steam from HP turbine after reheating enters the inner casing from above and below

through two inlet nozzles. The center flow compensate the axial thrust and prevent the L.P. & H.P. rotor

are connected to the rigid compiling & they have a common bearing. After passing through I.P.

turbine, the steam enter the middle part of L.P. turbine through two cross pipes.

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LUBRICATING OIL SYSTEM

A lubricantis a substance introduced to reduce friction between moving surfaces. It may also have thefunction of transporting foreign particles and of distributing heat. The property of reducing friction is

known as lubricity.

Steam inlet temperature affecting brackets, bearings etc. The arrangements of inner casing confines high

steam inlet condition to admission branch of casing, while the joints of outer casing is subjected only tolower pressure and temperature at the exhaust of inner casing. The pressure in outer casing relieves the

joint of inner casing so that this joint is to be sealed only against resulting differential pressure. The IP

turbine consist of 20 reaction stages. The moving and stationary blades are inserted in appropriatelyshaped grooves in shaft and inner casing.

inner casing consist of outer shell with provision of free Super Thermal movement. Steam admitted tothe LP turbine from IP turbine flows into the inner casing from both sides through steam inlet nozzle.

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BOILER

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BOILER

INTRODUCTION :

The utility boilers are large capacity steam generators used purely for the steam power

generation. In boiler heat energy is released from the combustion of fossil fuel and heat is transferred todifferent fluids in the system and a parts of it is lost or left out as unutilized. It is therefore essential to

study the general principle of heat transfer for understanding the design as well as the behavior of boiler

during condition of operation.

HEAT TRANSFER MODES :There are three modes of heat transfer viz. conduction, convection and radiation, one or more of

these modes for which heat source should be at higher temperature than the receiver transfers heat

energy hot surface to a heat recover.

a) Conduction :

Conduction is the heat transfer from one part of the body top another part of the same body orfrom one body to another in physical contact without appreciable displacement of the particles of the

body.

b) Convection :

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Convection is the heat transfer from one point to another within a fluid by

mixing one part with another due to the movement of the fluid. When the

movement of the fluid is caused solely by the differences in density resulting from

temperature differences within the fluid.

c) Radiation :

Radiation is the transfer of heat energy from one body to another by electromagnetic waveswhich can travel even through vacuum when radiations impinges on the body, some of the radiant

energy is re-radiated, some of it will be transmitted through the body and remainder will be absorbed.

Heat Transfer Surface Arrangement :

There are three general kinds of arrangements of heat transfer surfaces as the relative flow of

fluid in concern. They are paralleled flow, counter flow and cross flow. In parallel flow both the fluidsenter at the same relative physical location with respect to heat transfer surface, Resulting rapid rise in

temperature. In counter flow, the two fluids enter at opposite ends of the heat transfer surface and flow

in opposite direction over the surface resulting suddenrise in temperature. In cross flow the flow paths of the two fluids are perpendicular to each otherresulting gradual rise in temperature.

Heat Transfer Section :

The various heat transfer section of a boiler can be grouped as follows :-

Furnace :-The furnace design influenced by the fuel, surface, plain area (13.8610.59) volumetric (5470 m 3) and

burner clearance. The major fuels used in the steam generation are coal, oil and gas.

Super Heater & Re-heater :-The location of super thermal and re-heat is almost standard based on the past experience.

Typical arrangement of super heater and re-heater is indicated in the elevation drawing.

Economizer :-This is also convection heat transfer section located in a relatively cooler gas temperature zone

and preheats the water entering the drum. The inlet temperature should not be less than 140C from the

low temperature corrosion point of view. The outlet temperature should be 35-40C lower than the

saturation point to avoid the streaming tendency in the economizers.

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Air Heaters :-The technical developments of the air pre-heater provides regenerative type air heaters. The air

temperature required for drying in the case of coal fired boiler decided the size of heaters.

Material Selection For Heat Transfer Surfaces :The selections of the heat transfer surfaces are being done on the basis of the temperature of the

mid metal temperature as well as the outer surface temperature complete water wall system is providedwith only carbon steel where as super heater and re-heater are provided with whereas grades of ASTMspecification.

Circulation System :In natural circular system, water delivered to steam generator from feed heater which are at a

temperature well below the saturation value corresponding to that pressure. Entering the economizer, it

is heated to much greater the saturation temperature. From economizer the water enter the drum and thusjoins the circulation system through down covering water wall tubes. In water

wall tubes a part of the water is converted to steam due to boiler and the mixture flows back to the drum

on the basis of the thermo siphon principle. In drum, The steam is separated out through the steamseparators and passed to the super heaters. After the super heater when the temperature becomes high

and pressure up to 150 Kg. Steam is allowed to enter the turbine to convert potential energy to kineticenergy.

147.5Kg/

Cm2CM

C

158.6Kg/

Cm23000r

pm

195M

W

50

Hz

BOILER DRUM

TECHNICAL SPECIFICATION OF BOILER (250 MW UNITS)

Type : Direct fired, natural

Circulation balance draught water tubeboiler.

Number of units : 2

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Make : BHEL

Capacity : 375 tons per hour

Steam pressure : 139 Kg/Cm2

Efficiency : 86.6%

Number of fans in service:

ID fans : 2 Nos.

FD fans : 2 Nos.

PA fans : 2 Nos. Seal sir fan : 1 No.

Scanner air fan : 1 No.

Igniter fan : 1 No.

Steam temperature : 540C.

No. of coal mills in device : 3 Nos.

No. of soot blowers : 70 Nos.

FUEL :

A) COAL : Type : Slack coal

Quantity consumed : 3074 tons per day.

Type of handling : conveyer Ash disposal : Wet system

B) OIL :

Type : HSD and fuel oil

Quantity : a) HSD 5520 KL per year.b)Furnace oil:2880 KL per

year.

No. of chimney / stack : 1/2

Height of chimney : 180 m.

Volume of gas : 198m3/sec

Air emitted.Temperature of flue gas : 140C

ESP : One for each unit.

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HIGH PRESSURE HEATER

GENERAL DESCRIPTION :Boilers are tangentially fired, balance draft, natural circulation, radiant type, dry bottom with

direct fired pulverizing coal from blow mills. They are designed for burning low grade coal with high

ash content. Oil burners are located between coal burners for flame stabilizations. Pulverized coal is

directly fed from the coal mills to the burners at the four corners of the furnace through coal pipes. Thepulverized fuel pipes from the mills to the bunkers are provided with the basalt lined bends to reduce

erosion and to improve the life of these pipes.

For the last stage of heat recoveries there are two regenerative air heater of trisected type. The airheater has separate section for heating the primary air (required for pulverize) & the section secondaryair (required for the combustion process).

BOILER FEED WATER CYCLE

The fuel preparation section consists of primary for number bowl mill arranged for pressurized

operation. Each mill has its own raw coal from each mill is carried through pipes to the burner to the

burner to the four corners of furnace arranged for tiling tangentially arranged for firing. The burner

wind-box section is located in four corner of the furnace owing to poor grade of coal there is apercentage of mill rejects. The mill rejects are conveyed in a sluice way to an under-ground tank. From

this tank the mixture is taken to the overheads hydro-bin where water is decanted and the mill reject are

disposed off by trucking. ESP with collection efficiency of 99.8% have been provided to reduceenvironmental pollution and to minimize induce draft fan wear. A multi-flue reinforced concrete stack

with two internal flues has been provided

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Two boiler feed pumps each of 100% capacity are driven by AC motor through hydrogen

coupling with scoop tube arrangement for regulating feed water pressure for each unit.

The air required air combustion is supplied by two forced draft fans. Due to anticipated high

abrasion of ID fans impellers. Three ID fans each of 60% capacity have been provided one ID fan to

serve as standby. For ensuring safe operation of boilers, furnace safe guard supervisory system (FSS) ofcombustion engineering USA designed has been installed. This equipment symmetrically feed fuel to

the furnace as per load requirement.

The UV flame scanners installed at two elevation in each of the four corners of the furnace, scan

the flame conditions and in case of unsafe working conditions but out fuel and trip the boiler andconsequently the turbine. Turbine-boiler interlocks safe guarding the boiler against possibility furnace

explosion owing to flame failure.

Facilities have been provided to simultaneously unload and transfer 10 light oil and 40 heavy oiltankers to the designated tanks. Oil preheating arrangement is provided on the tanks floors for the heavy

oil tankers to the designated tanks. Oil preheating arrangement is provided on the tanks floors for the

heavy oil tanks.Superheated steam temperature is controlled by attemperation. Re-heater steam

temperature is primarily by tilting fuel burners through 30C and further control if

necessary is done by attemperation.

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WATER TREATMENTPLANT

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WATER TREATMENT PLANT

The principle problem in high-pressure boiler is to control corrosion and steam quality. Internal

corrosion costs power station crores of rupees in repair without strict control impurities in steam alsoform deposit over turbine blades and nozzles. The impurities present in water are as follows:-

Un-dissolved and suspended solid materials.

Dissolved salts and minerals.

Dissolved gases.

Other materials (oil, acids etc.)

Turbidity and Sediment.

Silica.

Micro Biological.

Sodium and Potassium salt.

Dissolved Sales Minerals. O2 gas.

CO2 gas.

D.M. PLANT :-In this plant process water is fed from all these dissolved salts. Equipment for

demineralization cum softening plant is supplied and is erected by M/s. Wanson

(India) Ltd., Pune. This plant consists of two streams, each stream with activated

carbon filter, weak acid, cation exchanger mixed bed exchanger. The filter water to

DM plant through 250 dia. Headers from where a heater top off has been taken tosoftening plant. Two filtered water boosters pumps are provided on filtered water

line for meeting the pressure requirement in DM plant.

Sodium Sulphate solution of required strength is dosed into different filtered

water by means of dosing pump to neutralize chlorine prior to activated carbon

filter. When water passed an activated carbon filter will remove residual chlorine

from water. Provision is made for back washing the activated carbon filter the

works acid cation unit. The deception water the weak base anion exchanger unit

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water than enters de-gasified unit where free CO2 is scrubbed out of water by

upward counter flow of low primary air flow through degasified lower and degassed

water is pumped to strong base exchanger (anion exchanger).

Arrangement for dosing ammonia solution into de-mineralized water after

mixed bed unit has been provided p+1 correction before water is taken into de-

condensate transfer pumps the DM water to unit condenser as make up. The

softening plant is designed to produce 100m3 of the softened water per stream. It

is used for bearing cooling.

C.W. PLANT:

Circulating water pump house has pumps for condensing the steam for

condenser. Five pump are used for condensing unit no. 1 & 2 and after condensingthis water is discharged back into the river.

Each pump has the capacity of 8275 m3/hr, and develops pressure about

1.94Kg/Cm2.

Three seal water pump are used for sealing circulating water pump shaft at

4.5Kg/Cm2.

Two pump for unit 1 & 2 with one stand by is used for supplying raw water tochlorified chemical dosing is done between and chlorified water is taken through

main line. From main line water passes through filter bed to filter the water.

Chlorified water is pumped to 42m elevation by two pumps of capacity 270m 3/inch

at discharge pressure of 6.9Kg/Cm2. At 42m elevation the water is stored in tank

and used for cooling the oil coolers and returned back to river. Oil coolers are

situated on ground and there are no. of trees for each unit.

B.C.W. PUMP HOUSE :-Filter water after demineralization is used for bearing cooling from BCW pump house after

passing through strainer and heat exchanger it returns at 30-25C and leave exchanger at 38C. The raw

water used in ash handling plant and remaining quantity is stored in slump of BCW pump house . From

here the water is pumped to CW pump by TWS (Traveling Water Screens) pumps are run by motor of90 KW and has a capacity of 240 Cum/hr/pump at a pressure of 5Kg/Cm2.

BCW here stand for water used for cooling oil used for cooling the bearing. In CW pump house water is

discharged from nozzle and impinged for traveling water screens for cleaning it.

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CONDENSATESYSTEM

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CONDENSATE SYSTEMA typical condensate system consists of the following:

Condenser (including hot well).

Condensate pumps.

Air extraction system.

Gland coolers and LP Heaters.

Dearator.

Condenser

The functions of condenser are: To provide lowest economic heat rejection temperature for the steam. Thus saving on steam

required per unit of electricity.

To convert exhaust steam to water for reuse thus saving on feed water requirement.

dearation of make up water introduce in the condenser.

To form a convenient point for introducing makes up water.

Type of CondenserCondenser is basically a heat exchanger and hence can be of two types;

Direct Contact Type,

Surface Contact Type.

Direct Contact Type (Jet Condenser)In this type, condensation of steam takes place by directly mixing exhaust steam and cooling

water. Requirement of cooling water is much less as compared to surface type. But cooling water should

be equal to condensate quality.

Surface Contact Type

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This type is generally used for modern steam turbine installation. Condensation of exhaust steam

takes place on the outer surface of the tubes. Which are cooled by water flowing inside them.

The condenser essentially consists of a shell which encloses the steam space. Tubes curving

cooling water pass through the steam space. The tubes are supplied cooling water from inlet water box

on one side and discharged after taking away heat from the steam, to the water outlet box on other side.

Instead of one inlet and one outlet water boxes, there may be two or more pair of separate inlet,

outlet water boxes, Each supplying cooling water to separate bundle of tubes. This enable cleaning andmaintenance of part of tubes by turbines can be kept running on a reduced load.

CONDENSATE EXTRACTION PUMPSCondensate extraction pumps are normally multistage, vertical, centrifugal pumps. They are

generally required to operate on minimum Net Positive Suction Head (NPSH). The condensate pumpsoperate on few inches of suction submergence.

A vent line connects the hot well, from the condensate pumps take suction with the condenser.

This equalizes the vapour pressure of condenser and hot well. Number of stages in the pump is determine by the discharges pressure required for the

condensate cycle in 110 MW unit. Three condensate pumps, each having 50% capacity, are provided forpumping the condensate to dearator. Condensate water is also used for:

Sealing of glands of valves operating under vacuum.

Temperature control of L.P. by pass system.

Falling siphons of main ejector and 15 m siphon of drain expander.

Actuating the force closing non-return waves of turbine steam extraction lines.

Operating of group protection device for bypassing H.P. heaters.

For cooling steam dumped through steam throw off device.

AIR EXTRACTION SYSTEMAir extraction system is needed to extract air and non-condensable gases from the condenser for

maintaining vacuum. Amount of air to be extracted from condenser during start up is quite large andextraction should be done as rapidly as possible so as to allow the turbine to be started.

To guard against excessive water vapour extraction along with air, the space beneath the air

extraction baffles has been provided with its own cooling tubes in order to condense as much watervapour as possible and thus preventing its removal from condenser.

LOW PRESSURE HEATERS

The low pressure heater is of horizontal surface type consisting of two valves, each half has beenlocated inside the upper part of each

The housing for the heater is fabricated from the M.S. plates with suitable steam inlet and drain

connections. The tube plate is of mild steel and is secured to the water box and housing by means ofstuds and nuts. U shaped tubes have been used to ensure independent expansion of tubes and the

shells. They are of solid drawn admiralty brass, 19mm external dia., 1mm and 0.75mm thick and are

expanded by rolling into the tube plate at facilitate drawl for tube replacement and maintenance.Partitions mild steel plates have been provided for supporting the tubes at intermediate points and

effective distribution of heat load all the zones of heater.

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GLAND STEAM COOLERIt cools the steam mixture sucked from turbine and seals. It is of vertical type and has two

sections. An ejector mounted on the cooler maintains constant vacuum in the first section. It also sucksthe remaining air-steam mixture from first section to second where air is let off and steam is condensed.

A part of main condensate, after main ejector, flows through the cooler tubes consisting of U-shaped

brass tubes rolled in steel tube plate. Drain from cooler is led to condenser.

GLAND COOLER

Gland cooler has been designed to condensate the leak off steam from intermediate chambers of

end earthing of HP & IP turbines. The construction of this cooler is identical with low pressure heater

no. 2,3 & 4. The main condensate flows through the tubes in four paths before leaving the cooler. Thedeal off steam enters the shell through a pipe and flow over the tube nest. The participation wall

installed in the tube system lead to zigzag flow of steam over the tube nest. Condensate of leak off steam

referred as drain trickles down the tube and is taken out from the lower portion of the shell by automaticlevel control valve, installed on the drain line.

DEAERATORThe pressure of certain gases like Oxygen, Carbon Dioxide and Ammonia, dissolved in water is

harmful because of their corrosive attack on metals, particularly at elevated temperatures. Thus inmodern high pressure boiler, to prevent internal corrosion the feed water should be free as far as

practicable of the dissolve gases, especially Oxygen. This is achieved by embodying into the freed

system a deareating unit. Apart from this, a dearator also serves the following functions: Heating incoming feeder.

To act as a reservoir to provide a sudden or instantaneous demand.

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COAL HANDLING

PLANT

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COAL HANDLING PLANT

INTRODUCTION :

It can be called as the heart of Super Thermal Power Plant because it provides the main fuel for

combustion in boiler. The coal is brought to the SSTPS through rails. There are fourteen tracks in all for

transportation of coal through rails.

The main coal sources for SSTPS are SECL (South Eastern Coalfields Limited), ECL (EasternCoalfields Limited) and BCCL (Bharat Coking Coal Limited). Everyday 3 to 4 trains of coal are

unloaded at SSTPS. Each train consist of 58 wagons and each wagon consist of 50 tons of coal. The

approximate per day consumption at SSTPS is about 1400 metric tons. It costs approximately 2 crores ofrupees per day including transportation expenses.

The coal is firstly unloaded from wagon by wagon Tripler then crushed by crushers and

magnetic pulley and pulverized to be transformed to the boiler. The whole transportation of coal isthrough conveyor belt operated by 3- Induction Motor.

The coal handling plant can be broadly divided in three sections:

Wagon Unloading System

Crushing System.

Conveying System.

WAGON UNLOADING SYSTEM :

Wagon Tripler :

It unloads the coal from wagon to hooper. The hooper, which is made up of Iron, is in the form of net so

that coal pieces of only equal to and less than 200 mm. size pass through it. The workers with the help of

hammers break the bigger ones. From the hooper coal pieces fall on the vibrator.

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It is a mechanical system having two rollers each at its end. The rollers roll with the help of a rope

moving on pulley operated by a slip ring induction motor with specification:

Rated output voltage : 71 KW.

Rated Voltage : 415 V.

Rated Current : 14.22 Amp.

No. of Phases : 3.

Frequency : 50 Hz.

The four rollers place themselves respectively behind the first and last pair of wheels of the wagon.

When the motor operates, the rollers roll in forward direction moving the wagon towards the wagon

table. On the Wagon table a limit is specified in each wagon has to be kept otherwise the triple would

not be achieved.

CRUSHING SYSTEM :

Crusher House :

It consist of crusher, which are used to crush the coal to 20 mm size. There are mainly two types

of crushers working in SSTPS :-

Primary Crushers i.e. Rail crushers

Secondary Crushers i.e. Ring granulators.

Primary Crushers :

Primary crushers are provided only in CHP stage 3 system, which breaking of coal in CHO

Stage-1 & Stage-2 system is done at wagon Tripler hooper jail up to the size of (-) 25 mm.

Roll Crushers :

Type : 80, 5 A breaker.

Capacity : 1350 TPH Rates/1500 TPHDesign.

Feed material : Rom coal.

End product size : (-) 500 mm.

Feed size : (-) 1200 mm.

Motor rating : 2 Nos. 125 KW, 100rpm. Crushers : 225.

Rotatory Breaker :

Type : 1221 Rotary Breaker.

Capacity : 800 TPH Rated/1000 TPH Design.

Feed Material : Coal with rejects.

Feed size : (-)0-500 mm.

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End product size : (-)0-200 mm.

Motor Rating : 125 HP, 1500 rpm.

Breaker rpm : 12.

Secondary Crusher :

Basically there are four ways to reduce material size : impact attrition,

: shearing and

: compression.Most of the crushers employ a combination of three crushing methods. Ring granulators crush by

compression accompanied by impact and shearing. The unique feature of this granulator is the minimum

power required for tone for this type of material to be crushed compared to that of other type of crushers.

Construction & Operation :

Secondary crushers are ring type granulators crushing at the rate of 550TPH / 750 TPH forinput size of 250 mm and output size of 20 mm. The crusher is coupled with motor and gear box by fluid

coupling.

Main parts of granulator like break plates, cages, crushing rings and other internal parts are madeof tough Manganese (Mn) steel.

The rotor consists of four rows of crushing rings each set having 20 nos. of toothed rings and 18

nos. of plain rings. In CHP Stage 1 & 2 having 64 nos. of ring hammers. These rows are hung on a pairof suspension shaft mounted on rotor discs.

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Coal Handling Plant

In coal handling plant a mass holding yard has been provided to receive the coal trains and

unloading them. The wagons are positioned on the wagon Tripler with the help of wagon handling gear.Two wagon Tripler remain standing by having a capacity to handle 12 box of wagons per hour. Coal

from wagon Tripler is discharged into two underground hooper is transferred by the two belt feeders to

either of the conveyers of 675 tons per hour capacity either of the conveyers to take coal directly to thecrusher house.

Crushers of this type employ the centrifugal force of swinging rings stroking the coal to produce the

crushing action. The coal is admitted at the top and the rings strokes the coal downward. The coal

discharges through grating at the bottom. The spacing of the bar determines the maximum size of thefinished product.

CONVEYING SYSTEM :

Stacker Re-claimer :The stacker re-claimer unit can stack the material on to the pipe and reclaim the stack filled

material and fed on to the main line conveyer. While stacking material is being fed from the main lineconveyor via Tripler unit and vibrating feeder on the intermediate conveyer which feds the boom

conveyer of the stacker cum re-claimer. During reclaiming the material discharged on to the conveyer by

the bucket fitted to the bucket wheel body and boom conveyer feeds the material on the main lineconveyer running in the reverse direction.

Conveyer Belt Specification Of Stacker Re-claimer : Belt width : 1400 mm.

Speed : 2.2 m/sec.

Schedule of Motor : All 3- induction motor.

Bucket Wheel Motor : 90 KW.

Boom Conveyor Motor : 70 KW.

Intermediate Conveyor Motor: : 90 KW.

Boom Housing Motor : 22 KW.

Slewing assembly : 10 KW.

Travel motor : 7.5 KW.

Vibrating Feeder : 26 KW.

Total installed power : 360 KW.

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Conveyer Specifications :

Capacity : 1)1350 T/H.2)750 T/H.

No. of conveyer : 38.

Horizontal length : 28 m.

Angle of induction : As per conveyor profile drg.

Lift (M) (approx) : Variable to suit the system.

Belt width : 1400 mm.

Flow Feeders :This structure is erected to serve the purpose of storage. Under ground machines are installed

known as plow feeder machines.

These machines collect the coal from conveyor and drop it to the other from one conveyor with the help

of jaws and this coal is taken to huge erected structure from where the coal falls to the ground. Jalichutes are used to prevent the dust.

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ASH HANDLING

PLANT

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ASH HANDLING PLANT

This plant can be divided into three sub-plants as follows :-

Fuel and Ash Plant. Air and Gas Plant.

Ash Disposal and Dust Collection Plant.

Fuel and Ash Plant :Coal is used as combustion material in SSTPS, in order to get an efficient utilization of coal mills. The

Pulverization also increases the overall efficiency and flexibility of boilers. However for light up andwith stand static load, oil burners are also used. Ash produced as the result of combustion of coal is

connected and removed by ash handling plant. Ash Handling Plant at SSTPS consists of specially

designed bottom ash and fly ash in electro-static precipitator economizer and pre-heaters hooper.

Air and Gas Plant :Air from atmosphere is supplied to combustion chamber of boiler through the action of forced draft fan.

In SSTPS, there are two FD fans and three ID fans available for draft system per unit. The air beforebeing supplied to the boiler passes through pre-heater where the flue gases heat it. The pre-heating of

primary air causes improved and intensified combustion of coal.

The flue gases formed due to combustion of coal first passes round the boiler tubes and then it

passes through the super heater and then through economizer. In re-heater the temperature of the steam

(CRH) coming from the HP turbines heated with increasing the number of steps of re-heater theefficiency of cycle also increases. In economizer the heat of flue gases after passing through the Electro-

Static Precipitator is exhausted through chimney.

Ash Disposal and Dust Collection Plant :SSTPS has dry bottom furnace. Ash Handling Plant consist of especially designed bottom and

fly ash system for two-path boiler. The system for both units is identical and following description isapplied to both the units of water compounded bottom ash hooper receives the bottom ash from the

furnace from where it is stored and discharged through the clinker grinder. Two slurry pumps are

provided which is common to both units and used to make slurry and further transportation to ash dyke

through pipeline.Dry free fly ash is collected in two number of 31 fly ash hooper, which are handled by two independent

flu ash system. The ash is removed from fly ash hooper in dry state is carried out to the collecting

equipment where it is mixed with water and resulting slurry sump is discharged.

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ELECTROSTATIC PRECIPITATOR

Scope and Principle of Operation :For general mankind, today an Eco-friendly industry is must. As far as air pollution is concerned

now a days various flue gases filter are there in services. The choice depends on size of suspendedparticle matter. These filters are E.S.P. Fabric filter high efficiency cyclone separation and sideling

room. For fly ash where the size of particle vary from 0.75 microns to 100 micron use gradually ESP to

purify the flue gases due to its higher efficiency and low running cost etc. In an ESP the dust lidded gasis passed through an intense electric field, which causes ionization of the gases and they changed into

ion while traveling towards opposite charged electrode get deposited as particles and thus the dust is

electrically deposited on electrode creating a field. It is continuous process.

CONTROLLER :Now a days microprocessor based intelligent controllers are used to regulate the power fed to

HVR. The controls the firing/ignition angle of Thyristors connected in parallel mode. Input out waves of

the controller and HRV are also shown above, which clearly indicates that average power fed to ESPfield can be controlled by variation of the firing angle of Thyristors.

The output of controller with respect to time is also controlled by microprocessor so that ESPoperation is smooth and efficient. The chars is as shown:

As can be seen in the event of spark between electrodes the output of controller is reduced to zero or few

millisecond for quenching the spark. Controller also takes place care of fault in KVR and gives atrapping and non-trapping alarm as per the nature of fault.

HIGH VOLTAGE RECTIFIER TRANSFORMER:HVR receives the regulated supply from controller. It steps up to high voltage rectifier. The DC supply

is fed to ESP field through its negative bushing. The positive bushing so connected to earth through

small resistance, which forms a current, feed back circuit. A very high resistance column is alsoconnected with negative bushing. It forms the voltage feed back circuit. These two feedbacks are used inthe controller for indication and control purpose.

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ASH SLURRY SUMP

Mechanical precipitators consists of number of primary cells having vanes to impart the ash

particles and coarse ash particles fall into the primary hooper. The ESP consists of a large number in

which have no collecting electrodes. In it dust particles are charged and stick to the electrodes.

E.S.P. FIELD :The field consist of emitting and collecting electrodes structure, which are totally isolated witheach other and hanging with the top roof of field. The emitting is also isolated from the roof through the

support insulators, which are supporting the emitting electrode frame works, and also the supply to these

electrodes is fed through support insulators. The collecting electrodes are of the shape of plates. Byseveral similar plates which the emitting electrode are of the shape of spring. Strong on the emitting

frame work with the help of hooks in both the ends.

The ash depositing on these electrode is rapped down by separate wrapping mechanism happensat the bottom of the field. From these hooper ash is evacuated by ash handling system and dispose to the

disposal area. The wrapping system is automatically controlled with the help of programmable metal

controller, located in the ESP auxiliaries control panels. The bottom of hooper is heated up by to avoid

any information to wet mass of fly ash especially during rainy season. The heating effect helps the dryash to flow freely during evacuation. Heaters are controlled with the help of thermostat.

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CONCLUSION

The first phase of practical training has proved to be a fruitful. It provides an opportunity for

encounter with such huge machines like Wagon Tripler, 250MW Turbines and Generators.

The architecture of the Power Plant, the way various units are linked and the way working ofwhole plant is controlled Make the student realize that engineering is not just learning the structured

description and working of various machines, but the greater part is of planning management.

It also provides an opportunity to learn how the technology is used at proper place and time can

have a lot of labor e.g. Wagon Tripler (CPH).

But there are few factors that require special mention. Training is carried out into its tree sprit. It

is recommended that there should be some project specially meant for students where presence of

authorities should be ensured. There should be strict monitoring of the performance of students and

system of grading be improved on the basis of work done.

However training has proved to be quite fruitful. It has allowed an opportunity to get an exposure

of the practical implementation to theoretical fundamentals.

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REFERENCE

SSTPS.

BRELI THERMAL PLANT, BIHAR

.

NTPC, HARIDWAR.

BHEL, HARIDWAR.

Power Plant Engineering by Dr. R.Yadav

report thermal

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