210 mw powerplant

7/28/2019 210 MW Powerplant

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COAL YARD MAINTENANC

DEPARTMENT The job of the coal yard department is to transport the coal

wagons to the bunker in the power plant.

The coal is transported to the power station by road or rail a

stored in the coal storage plant. The coal is brought to the power plants through the N type

railway wagons. Mostly the coal comes from Chhattisgarh

and also from Austria.


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The rack which transports the coal consists of mostly 58 wagon

contain about 3500-4000 tones of coal.

When the plant operates on its full load conditions it needs 3 rac

about 1200 tones of coal.

When the rack enters the plant it passes through the WEIGH BR

which records the amount of coal loaded in the rack.


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COAL FLOW DIAGRAM


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WAGON TIPPLER

The wagon tippler is used for tipping thewagon in order to empty the coal from the

wagon.

The coal from the wagon goes to the chamber

where there is a net.

So coal smaller than the net goes to hopperfrom which it goes to belt conveyor system.

The coal bigger than the net is hammered

manually and become smaller and follow the

same path.


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TRANSPORTATION OF COA

Coal is supplied to apron feeder through the conveyer belt.

Apron feeder is rugged and dependable and is designed to rece

control the flow of material from bins and hoppers.

From the apron feeder it goes to tribal conveyor.

From that it goes to double roll crusher which converts big c

small lumps.

From there it goes to shuttle conveyor which shifts the coal for fee

from one belt to other when there is a problem in that belt.


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TRANSFER TOWER

Coal transfer to conveyor belt 11A/11B to conveyor belt 12A/12

tower .

In transfer tower at the end of 11A/11B there is intim

separator(IMS). Magnetic separation is a process in which magnetically suscep

is extracted from a mixture using a electromagnetic force.

Ims is half of electro magnetize of rotating bed hence it can

particles from coal and prevent boiler from damage.


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CRUSHER HOUSE (STAGE

The coal comes from the belt conveyor 2a/2b goes to the crusheare two large cylinders which crush the coal.

From there if there is need for coal in the bunker, the crutransferred to the belt 5a/5b.

If not it is transferred to the belt 3a/3b to the stacking area bywhich can open or close manually or electrically.

If there is no wagon and we need coal in the bunker then coal the staking area through belt 4a/4b to 5a/5b.


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The coal coming from the belt conveyor 12a/12b goes to the cthere are two parts in the crusher; 1- roller screen, 2- ring grinder

Roller screen is suitable for separating coarse, wet, sticky material.

coal which is smaller directly goes to the belt feeder and biggethe ring grinder which crush the coal and send it to the belt feede

If there is need of coal in the bunker it will go to the belt 16a/1in the bunker and the coal is imported then it will go to the stac

belt no.13a/13b..


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It stacks the coal when not needed in the bunker and reclaicoal when wagon is not available and need of coal rises in

bunker.

When the coal is local then it will go to the stacking hoppethrough belt 14a/14b and will be reclaimed through belt 15

From the rusher the coal is transferred to the bunker wheretransferred to the mill as per requirement.


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VIBRATING FEEDER

When two belts are offset to each other then the coal is transfe

belt to another belt by vibrating feeder as per its name it vibra

coal is transferred through offset belts.

Vibrating Feeders protect the belt conveyors from damage by

material onto the belt conveyors from storage hoppers, silos, sand dumpers at a controlled rate.

A Vibrating Feeders are operated by employing pulsating

current when passed through stator, creates a series of interrupte

armature.


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TRANSPORTATION OF COA

After transfer tower 5 and/or junction tower 2 coal is suppl

coal mill from bunkers.

Each bunker has six coal mills, hence there are total eighte

mills.

From the feeder machine coal is supplied to bunker here al

taking care of coal size.


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Regenerative feed heating Cycle

single reheat 2 HP and 3 LP He


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.

The terms regenerative and recuperative frequently ap

recovery processes involving energy that would otherwise be r

fashion. The term regenerative describes a stage of feed water

steam thus, returning best to the steam cycle from which it came

Required for the heating process has an opportunity to generate

of power en route to the heater.

For maximum cycle efficiency, the feedwater tempereture on

boiler would equal the temperature of the boiler water itself. S

noted to be an infinite number of heat addition steps, it is not pis attempted.

Regenerative feedwater heating can include low-pressure heater

the deaerator, the deaerator itself, and high-pressure units

deaerator and the boilers

o er an


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o er anAccessories


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Boiler and Accessories

ECONOMISER

BOILER DRUM

DOWN COMERS

WATER WALLS

WATER WALL PLATEN

PRIMARY SUPER HEATER

PLATEN SUPER HEAT

FINAL SUPER HEATE

REHEATER

BURNERS

IGNOTORS

FRS (FEED REGULATI

STATION)


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Fuel LIGHT DIESEL OIL (LDO)

LDO comes through tankers and is stored in the main LDO storage tan

centrifugal pump it is transferred from the tank to the boiler furnace. At t

station in the power plant LDO+AIR are sprayed in the furnace throug

igniters. So the fuel burns and helps in raising temperature of the furnac

value of LDO used is 10,700kcal/kg.

FURNACE OIL (FO)

FO comes through railway wagons. As it is very thick so we have to providof heat to convert it into liquid form of oil for tripping action. Then it is t

storage tank from where it is fed to the boiler furnace. At the fuel feedin

plant FO+STEAM are ignited in the furnace through igniter. This is done a

of LDO. The tapping for the steam is taken from PRDS header of the plant.

has a pressure of 16kgf/cm2. The calorific value of FO used is 10,400kcal/kg


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Fuel

COAL

Raw coal from the raw coal bunker is supplied to the Coal Mills b

Feeder. The Coal Mills or pulverizer pulverizes the coal to 200 m

powdered coal from the coal mills is carried to the boiler in coal

pressure hot air. The pulverized coal air mixture is burnt in thecombustion zone. Generally in modern boilers tangential firing system

coal nozzles/ guns form tangent to a circle. The temperature in fire ball

of 1300 deg.C.


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Coal Mill In coal-fired power plants coal mills are used

to Pulverize and dry the coal before it is blowninto The boiler furnace. The coal is fed into

the coal mill through a central inlet pipe

where gravity is used to lead the coal to the

bottom of the mill, where the grinding table

and some heavy rollers pulverizes the coal tothe particles.


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The primary air flow to the furnace is fed

through the mill, with the purpose of heating

and lifting the coal particles out of the mill into

the furnace. If the particles are too heavy they

will drop to the bottom of the mill and will bepulverized once more. The coal particles are

heated to 100 degrees Celsius. The primary air

temp is controlled by controlling the position

of an air mixer which mixes heated outside air

and cold outside air.

THE BOWL MILL

It consists of a rotating and grinding bowl at

the base of the mill which is motor driven.

There are three rollers aligned at 120 degrees to

each other as shown in the fig. These rollers

help in crushing the coal up to 200 mesh

fineness.


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Firing Method

Tangential Fire in chamber Different chamber at diff. el


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Arrangement of fuel input in furn

Coal is pulverized in mills at a fineness of 70% thru 200 mes

powdered coal is conveyed to furnace (at a temperature < 95

Total coal flow is distributed among running mills and fed thburners at 20-25 m/sec.

Coal flow is arranged in tiers. Maximum heat release rate muexceed plain area heat loading. It generates excessive NOx anash fused.


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Heat Generation in furnace Heat input in the furnace

Efficiency of thermal power plants is 37%-45% for differen

of cycle For typical conventional P.F. boilers, coal flow rate is

290-350 T/hr For 500 MW units

120-145 T/hr For 200 MW units

Cycle

ElectFurnace

MWQ


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Economiser

It is located below the LPSH

in the boiler and above pre

heater. It is there to improve

the efficiency of boiler by

extracting heat from fluegases to heat water and send

it to boiler drum.


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Boiler Drum

After leaving the economizer, thefeedwater reaches the drum, which is acylindrical vessel at the top of the boiler

From here the water flows by naturalcirculation through downpipes into the

boiler Saturated steam collects here ready to go

to the superheater

Drum does the important function ofseparating steam from a mixture of steamand water


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Air Pre-heater

The heat carried out with

coming out of economize

utilized for preheating th

supplying to the combustion

It is a necessary equipmenthot air for drying the coal

fuel systems to facilitate

satisfactory combustion o

furnace


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Re-heater

Power plant furnaces may have are-heater section containing tubes

heated by hot flue gases outside

the tubes.

Exhaust steam from the high

pressure turbine is rerouted to goinside the re-heater tubes to

pickup more energy to go drive

intermediate or lower pressure

turbines.


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Fan or draught system

In a boiler it is essential to supply a

controlled amount of air to the furnace

for effective combustion of fuel and to

evacuate hot gases formed in the

furnace through the various heattransfer area of the boiler.

This can be done by using a chimney or

mechanical device such as fans


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Natural draught

When the gas within the stack is hot, its specific weight wthan the cool air outside; therefore the unit pressure at the baresulting from weight of the column of hot gas within the staless than the column of extreme cool air.

The difference in the pressure will cause a flow of gaopening in base of stack. Also the chimney is form of nozz

pressure at top is very small and gases flow from high presspressure at the top.


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Mechanized draught

There are 3 types of mechanized draught systems

1) Forced draught system

2) Induced draught system

3) Balanced draught system


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Balanced draught

In this system both FD fan and ID fan are provided.

The FD fan is utilized to draw control quantity of air from atm

and force the same into furnace.

The ID fan sucks the product of combustion from furnace andischarges into chimney.

The point where draught is zero is called balancing point.


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FD

FanDuct APH Duct Furnace Duct APH

Back

passESP ID

FanDuct

Duct

+ 150mmwcl

- 5mmwcl

- 73mmwcl

- 221mmwcl

+ 36mmwcl

Balance Draught System


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DM Plant Block Diagram


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GENERAL TURBINE DATA (K


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TYPE

Horizontal

Tandem

Compounded

Axial flow

Reheat turbine

GENERATOR SPEED: 3000rpm

REACTION 90 % - IMPULSE 10 % (MIXED)

NO OF STAGES

HP cylinder 8

IP cylinder 24, double flow

LP cylinder 20, double flow

Number of extraction 6

GENERAL TURBINE DATA (K


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Impulse stage whole pressure dropin nozzle (whole enthalpy drop ischanged into kinetic energy in thenozzle)

Reaction stage pressure drop bothin stationary blades and in rotaryblades (enthalpy drop changed intokinetic energy both in stationaryblades and in the moving blades in

rotor)

How does the steam turbine work?

CONSTRUCTION OF STEAM TURBINE


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1 steam pipeline

2 inlet control valve

3 nozzle chamber

4 nozzle-box

5 outlet

6 stator

7 blade carrier

8 casing

9 rotor disc

10rotor

11journal bearing

13thrust bearing

14generator rotor

15coupling

16labyrinth packing

19steam bleeding (extraction)

21bearing pedestal

22safety governor

23main oil pump

24centrifugal governor

25turning gear

29control stage impulse bladi


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WORKING


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High Pressure Turbine

High pressure steam at 540C and147 bar pressure passes through the

high pressure turbine. The exhauststeam from this section is returned tothe boiler for reheating before beingused in the next section of the turbineset.

The blades in the high pressure

turbine are the smallest of all theturbine blades, this is because theincoming steam has very high energyand occupies a low volume. Theblades are fixed to a shaft and as thesteam hits the blades it causes theshaft to rotate.

Boiler Reheater

After expanding through the hiturbine the exhaust steam is retboiler at 335C and 35 bar preheating before being useintermediate pressure turbine.

The Reheater reheats the stetemperature of 335C back to 5

I t di t P T bi


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Intermediate Pressure Turbine

On leaving the boiler Reheater, steam enters the intermediate pressureturbine at 560C and 40 ksc pressure (1 ksc = 14.22 psi )

From here the steam goes straight to the next section of the turbine set

The steam has expanded and has less energy when it enters this section,so here the turbine blades are bigger than those in the high pressureturbine

The blades are fixed to a shaft and as the steam hits the blades it causesthe shaft to rotate

Low Pressure Turbine

From the intermediate pressure turbines, the steam continues itsexpansion in the three low pressure turbines. The steam entering theturbines is at 300C and 6 ksc pressure

To get the most work out of the steam, exhaust pressure is kept verylow, just 50 mille-bar above a complete vacuum

The tip speed of the largest blades with the shaft spinning at 3,000revolutions per minute is 2,000 kmph


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What is Ash Handling?

Ash handling refers to the method of collection, conveying, interi

load out of various types of ash residue left over from solid fuel c

processes.

The most common types of ash include bottom ash, bed ash, fly aclinkers resulting from the combustion of coal, wood and other so

Ash handling systems may employ pneumatic ash conveying or m

ash conveyors


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What is Ash?

Burning of pulverized coal in the furnace results in the genera

quantity of ash.The average ash content in Indian coal is 40%

Ash is oxidized form of the mineral matters present in coal.

Typical ash composition : SiO2, Al2O3, Fe2O3, CaO, MgO etc.

Two types are:

Bottom Ash

Fly Ash


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Bottom Ash

The ash which is directly collected from bottom of boiler is ca

ash.

Bottom ash directly falls down in water filled hopper due to gra

The percentage of bottom ash is 20% of total ash.


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Fly Ash

Fly ash, also known as flue-ash, is one of the residues gener

in combustion, and comprises the fine particles that rise with

flue gases percentage of fly is 80% of total ash.

Fly ash is collected from :-

ESP hoppers

Air preheaters hoppers

Economiser hoppers


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Ash Collections

Wet Ash Handling System


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Wet Ash Handling System

Ash generated below furnace of is calledthe bottom ash. It is Non- Combustible partof Combustion

The clinker stick to hot side walls offurnace and fall themselves into water, andget cooled.

The clinker lumps crushed to small sizes byclinker grinders and water is mixed withash.

By means of jet pumps ash is transported inslurry pipe lines to the ash slurry sump forfurther disposal.

Dry Ash Handling System


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Dry Ash Handling System If fly ash is discharge in atmosphere, it will

create heavy air pollution thereby resulting

health hazards. Hence it is necessary toprecipitate ash from flue gases.

Precipitation of ash has another advantage,it protects the wear & erosion of ID fan.

To achieve the above objectives,

Electrostatic Precipitator (ESP) is used. Asthey are efficient in precipitating particleform submicron to large size.

El t t ti P i it t


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Electrostatic Precipitator

Dry Fly Ash Extraction and


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Dry Fly Ash Extraction and

Transportation System

Ad t f Sil S t


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Advantage of Silo System

Saving of water

Energy Efficient

High reliability

Long Plant Life

Least maintenance

Chi CHIMNEY


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Induced Draught (ID) Fan

Two induced draught fans draw gases out of the boiler

The gas has already passed through the air heaters andprecipitators before it has reached these fans

The heat from the flue gases or smoke is used in the airheaters to heat up the primary and secondary air.

Chimney

A chimney is a structure which provides ventilation for hot flue gases orboiler to the outside atmosphere. Chimneys are typically vertical, or as neavertical, to ensure that the gases flow smoothly, drawing air into the combu

known as the stack, or chimney effect.

The chimney is 94.5 meters' high and 50,000 tonnes of reinforced concremake it

It consists of flues each of which serve typically two or three boilers (two un

CHIMNEY


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BOILER EFFICIENCY(Indirect M


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BOILER EFFICIENCY(Indirect M

TURBINE EFFICIENCY


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TURBINE EFFICIENCY

CONDENSER RATING AND


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CONDENSER RATING AND

EFFECTIVENESS


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FEED HEATERS EFFECTVIEN

COOLING TOWER


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COOLING TOWER

CHIMNEY


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CHIMNEY


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210 mw powerplant

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