Power Plant Engineering_ Thermal Power Station

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Power Plant Engineeing

MechanicalEngineering

PPE

Dr. M Varaprasada Rao



WELCOMEMY DEAR STUDENTS AT GIET



POWER PLANT ENGINEERING

An Introduction byDr. Varaprasada Rao

1/19/15 3Prof. Varaprasada Rao Ex.NTPC






THE PRINCIPAL INVOLVED IN THE CLASSICAL

POWER PLANT




Sources of electricity

generated

Gas power plants 10%

Coal fuel plants !.!%"il 0.#%

$ydro electric &.'%

(uclear .#%

Renewable energy

sources '.'%

1/19/15 !Prof. Varaprasada Rao Ex.NTPC



Gas power plantsGas)based plants* are en+iron,entally friendly

unli-e coal or petroleu,)based feedstoc- li-enapta

Acid rain content lower tan tose generated bycoal)based plants

Deterrent(ot too popular in India al,ost '0% of natural gas

re/uire,ents for power plants about 11& ,illion tonnesare i,ported

Re/uire,ent ,et troug i,ports are troug ostileterritories

1/19/15 "Prof. Varaprasada Rao Ex.NTPC



India

India is one of te world4s largest consu,er ofenergy

Con+entional sources5 2er,al* $ydro and

(uclear.(on) con+entional5 6ind* solar* Geoter,al*

tidal.

Installed capacity 7 1*81*!96

2er,al : 95151.796(uclear : &*1096

$ydro : !"#77.7"96

RE$ % 1!&&.196

Annual power production 7 8;0 billion <6$



=rea- up of 3ower 2er,al 3ower 3lants 7 '%

$ydro >lectric 3ower 3lants ) 1%

(uclear 3ower 3lants ) &%

Installed wind power Generation 7 #896

!0% to &0% of electrical power is lost intrans,ission and distribution



SS2>9

S2R?C2?R> "@ 3"6>R



S2R?C2?R> "@ 3"6>RSS2>93ower syste, owned by state

electricity boards.

3ri+ate sector utilities operate in

9u,bai* <ol-ata* A,edabadRegional electricity boards 7

(ortern* Soutern* >astern* 6estern*

(ort)eastern.3ower Grid corporation) Central.



2er,al 3ower 3lantsInstalled Capacity 7 #!*!#.8&96

1. Coal based 7 ''*&;.;;96

. Gas =ased 7 1&*'!&.0196!. "il =ased 7 11##.'96



General Bayout of 2er,al 3owerStation



9ain Co,ponents@uel $andling ?nit

As $andling ?nit

=oiler ?nit

@eed 6ater ?nit

Cooling 6ater ?nit

Generator ?nit

2urbine ?nit



9ain Circuit@uel And As Circuit

Air And Gas Circuit

@eed 6ater And Stea, Circuit

Cooling 6ater Circuit



@uel And As Circuit@uel stored and fed to te boiler troug

con+eyor belts. =ro-en down into propersape for co,plete burning.

As tus generated after burning is re,o+edfro, te boiler troug as andlinge/uip,ent



Air And Gas CircuitAir is re/uired for co,bustion of fuel and is

supplied troug fans

Air is passed troug air preeater to etractenergy fro, ue gases for proper burning ofte fuel

@lue gases a+e as and se+eral gases wic

are passed troug te precipitatordustcollector and go to at,ospere trougci,ney.

@ 6 t A St



@ee 6ater An Stea,CircuitStea, Con+erted to water by condenser.6ater is de,ineraliEed F ence not wasted to

a+e better econo,ic operation of te plant.

So,e part of stea, and water is lost wile

passing troug dierent parts.=oiler feed pu,p feeds water into te boiler

dru, were it is eated to for, stea,.

6et stea, is again eated in super eaterbefore passing troug te turbine

Stea, is epanded in te turbine to run it.After wic again it goes to boiler for reeating



Cooling 6ater Circuit

2o condensate te stea,* large /uantity ofcooling water is re/uired wic is ta-en fro,ri+er or pondage

After passing troug te condenser* it is fedbac- to te ri+er or 3ondage



1/19/15 Prof. Varaprasada Rao Ex.NTPC #$

il



=oiler

bi



2urbine



2urbine 7 @ull View



>cono,iEer



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1/19/15 Prof. Varaprasada Rao Ex.NTPC 31© The McGraw-Hill Companies, Inc.,1998



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Coal @ired Stea, Generator Syste,



3ri,iti+e 9etod of solid Co,bustion

Pr&'ar( A&r

S)*o+dar( A&r ,-a')

r))+ Coa-

I+*a+d)s*)+ *o0)

ra)

COCO#N#H#

V2COCO#N#H#

O#CO#N#H#O

ASH



To'()ee* +'*ra)t co,-+tor



3ysics of @ied =ed Co,bustion

A bed of sto-er)siEed coal particles is supported by agrate.

Air ows upwards troug te grate and te fuel bed.

?pon eating* coal particles Hrst undergo a stage of 2er,al preparation.

>+aporation of 9oisture drying.Distillation of V9 3yrolosis

3roduction of enoug V9 to start ignition.

Co,bustion of car.

2e coal ows slowly downward at a +elocity Vs* as te

coal burns out in te lower layer of te bed.



Auto,ation in @uel =ed Co,bustionAlso called 9ecanical Sto-ers.

2ra+elling Grate Sto-er

Cain Grate Sto-er

Spreader Sto-er

Vibrating Sto-er

?nderfeed Sto-er



2ra+elling Grate Sto-er

Boiler type: natural circulation

Firing method: stoker fired

Max. continuous rating:9,7 kg/s

Steam temperature outlet:450°C

Steam pressure outlet: 4,0 Mpa

Gross efficiency: 87

Fuel type: Bitu!inous coal

Net calorific value: "# M$/kg

%&'()*(' %-.(' '(* B-1('



%&'()*('+%-.(' '(* B-1('



$oli* )+el( /re* -oiler 0te,

2yp ca S Ee D str ut on Coa or Sto er@



@urnace



Closing Re,ar-s on Grate @iring

2e Hrst li,it on grate Hring is tat of scale.

A practical engineering li,it see,s to be reaced wente lengt and widt of te grate are about # , witgrate area ;0 ,.

At 96,* te stea, capacity at ;% eJciency wouldbe 10 96 or '0 tons per our.

In practice sto-ers a+e rarely eceeded a capacity of1! tonsour.

2e li,itation is partly grate area and partly Hringdensity.

2e li,itation on Hring density eist due to5 2e rate of ,o+e,ent of te reaction plane could not

,atc te opposed rate of fuel ow leading to blow)o.

2e eperience wit grate co,bustion led tode+elop,ent of ,any re/uire,ents for furter

de+elop,ent.



3ara,eters for Co,bustion Re/uire,ents

$eat Release RateVolu,etric Co,bustion IntensityArea Co,bustion Intensity>ecti+e Reactor $eigtCoal @iring DensityArea @iring Density3roducts of co,bustion VelocityAir VelocityCo,bustion ti,e3article $eating Rate$eat 2ransfer @lues$eat ecange surface area per unit cross sectional area

of co,bustion ca,ber* φ



$eat Release Rate 5 A Capacity Bi,it

9ost co,,on Grate Hred furnace K !0 96.

9ai,u, obtained K 10 96.

9ai,u, 3ower Generation Capacity K 0 96

@uture 3roLected Re/uire,ent K !000 96

@iring Densities Bi,its 5 An "pti,al Coice



@iring Densities Bi,its 5 An "pti,al Coice

@iring densities are epressed in two ways5

A +olu,etric co,bustion intensity* Iv.

$ig +alue of Iv

:

Compact furnace Low Capital cost Less time for combustion

Bow Values of I+

Bulky furnace

More time for combustion Low Running Cost

Area @iring Intensity* I A $ig +alue of I A Sleek furnace

ig!er combustion "emperatures Better Ignition

Bow Value of I A #oor Ignition $at furnace

Low %o &

Soli' As!



3ul+eriEed @uel Co,bustion

In+ented in 1#0.An uni+ersal coice for power plants till 1##0.

@ine particles of coal K ' ,icrons.

Surface area 5 10 ,-g.

$uge eat release per unit area 5 7 96,.

Stea, generation 5 000 tonsour.



@luid 9ecanics of Solid =eds

∆p

V)-o*&(

Sa&* )dD(+a'&* )d

,-oa&+ )d



Interacti+e Co,bustion of 3C 3articles



Interacti+e Co,bustion of 3C 3articles

,or a+ &so-a)d par&*-) a sp6)r&*a-

)+7)-op) f-a') &s for')d aro8+d 6)

par&*-).T6) f-a') a*s as a s&+0 for f8)- a+d ox()+

a+d as a so8r*) for 6)r'a- )+)r(.

If a+o6)r 8r+&+ par&*-) &s ro86 +)ar

6) par&*-) 6) CO r)-)as)d ( 6)

par&*-)s *o'p))s for ox()+ 'o-)*8-)s.

,8r6)r 6) &+)rs&&a- )'p)ra8r) a+d

sp)*&)s prof&-)s ar) a-so aff)*)d.

A so') po&+ 6) f-a')s s8rro8+d&+ )a*6

par&*-) :&-- ')r) a+d a *o''o+ f-a') &sfor')d aro8+d 6) par&*-)s.

If 'or) par&*-)s ar) ro86 +)ar 6)+ a

*o''o+ f-a') 'a( ) for')d aro8+d a+

arra( or *-o8d of par&*-)s.



Nowadays, the environment protection has

become a crucial problem and theauthorities are requested to set increasingly

more stringent limits , one of which is the

emissions from the industrial plants of solid particulate and other gaseous pollutants .

ABOUT ELECTROSTATIC

PRECIPITATOR



ABOUT ELECTROSTATIC PRECIPITATOR

Electrostatic precipitator (ESP) is a widely

used device in so many different domainsto remove the pollutant particulates,

especially in industrial plants.

What is ESP



!" ESP "!#$S

%enerally, the processes of

electrostatic precipitator are &nown as

three main stages' particle charging,

transport and collection.

Main process of ESP



Schematic of wire-plate ESP

Schematic of wire-plate electrostatic

precipitator



Mechanism of ESP

Mechanism of electrostatic precipitator



PROCESS O Particle char!in!

Particle charging is the first and

foremost beginning in processes.

s the voltage applied on precipitator

reach threshold value, the space inside

divided into ioniation region and driftregion.



The electric field magnitude around the

negative electrode is so strong that the

electrons escape from molecule.

Under the influence of electric field, the positive

ions move towards the corona, while the

negative ions and electrons towards thecollecting plates.



Particle transport

*n the moving way, under the influence ofelectric field, negative ions cohere and charge the

particles, ma&e the particles be forced towards

collecting+plate.



Particle collection

As soon as the particles reach the plate,

they will be neutralied and pac!ed by

the succeeded ones subse"uently. Thecontinuous process happens, as a result,

particles are collected on the collecting

plate.



Coal 9iningSurface 9ining

Strip 9ining

?nderground 9ining

1/19/15 "3Prof. Varaprasada Rao Ex.NTPC





Coal 3ower 3lant "peration Stea, 2urbine Generator

Is a series of steam t#r$ines interconnecte" to each other an"then a !enerator

Stea, Condenser Steam enters from the t#r$ine !enerator an" is p#mpe" into

the $ottom of the con"enser' where p#mps rec%cle thecon"ense" steam from the fee"water

Stac- Releases process emissions&




Coal 3ower 3lant "peration

1/19/15 "!Prof. Varaprasada Rao Ex.NTPC



Coal 3ower Cheap

Cheaper per #nit ener!% than oil or nat#ral !as

Will contin#e to $e an important !lo$al reso#rce

A$#n"ance Coal is the worl"0s most a$#n"ant fossil f#el

S#fficient reser(es for the ne1t 234 %ears

1/19/15 ""Prof. Varaprasada Rao Ex.NTPC



Coal

3owerEfficienc%

Lar!er power plants are more efficient

567 of the chemical ener!% is con(erte" to ener!%

Safe safest fossil f#el to transport' store an" #se

scr#$$ers

1/19/15 "%Prof. Varaprasada Rao Ex.NTPC



Coal 3ower )diJcultiesCoal)@ired 3ower 3lants are te largestcontributor of aEardous air pollutants.

o Sulfur dioxide (SO2)

o Nitrogen Oxide (NOx)

o Carbon Dioxide (CO2)

o Mercury




>ects on teen+iron,ent and $u,an ealt

CO2 8 car$on "io1i"e poll#tion' ma,in! ener!% #se the sin!le lar!est

so#rce of !reenho#se !ases in the U&S& an" the worl"

1/19/15 %$Prof. Varaprasada Rao Ex.NTPC



>ects on te en+iron,ent and



$u,an ealt 9O1

When nitro!en o1i"e chemicall%/ reacts with (olatile or!anic

compo#n"s :OC0s/ an" s#nli!ht !ro#n"-le(el o)one or smo! is

forme"&

1/19/15 %#Prof. Varaprasada Rao Ex.NTPC

>ects on te en+iron,ent and



$u,an ealt

Merc#r% One of the most "an!ero#s poll#tants release" into the

air thro#!h the e1ha#st s%stem when coal is $#rne"&

1/19/15 %3Prof. Varaprasada Rao Ex.NTPC



@uture of Coal>cono,y

"ur econo,y relies on coal i,portation andeportation

2e de,and for coal usage to pro+ide electricity willcontinue to grow




@uture of Coal Clean coal tecnology A new !eneration of coal-$#rnin! power plants with ener!% processes that

re"#ce air emissions an" other poll#tants& Clean Air Acts

Coal power plants technolo!%

m#st a"apt to the chan!in!

political climate towar"s

en(ironmental iss#es&




2er,al Stea, 3ower plants

,ainly consists of & circuitsCoal and as Circuit Coal produced in te ,ining site is

transported to power plant site

Coal andling e/uip,ent for generation ofstea,

2e co,bustion of coal produces as wic iscollected and re,o+ed to as storage yard

troug as andling e/uip,ents

1/19/15 %!Prof. Varaprasada Rao Ex.NTPC



Air and gas circuit @D or ID fans are used for supply te air to

co,bustion ca,ber of te boiler troug

air)preeater 2e air preeater is placed in te pat of ue

gases to preeat te air 2e ue gases produced by co,bustion of

fuels in te boiler furnaces after passing

around boiler tubes and super eater tubes 3ass troug a dust collector or precipitator

were ,ost of dust is re,o+ed before+enting it of to at,ospere troug ci,ney

1/19/15 %"Prof. Varaprasada Rao Ex.NTPC

@eed water and stea, circuit5



3ri,e ,o+er de+elops power by utiliEingstea, generated in te boiler

2en condenser is used to condense testea, co,ing out of pri,e ,o+er

A pu,p is used to feed te condensate to teboiler

2e condensate lea+ing te condenser iseated in feed eaters troug etractedstea, fro, lowest pressure etraction pointof te turbine

2e feed water ,ay also be supplied fro,

eternal source to co,pensate any loss ofstea, and water. In te boiler sell and tubes water circulation

is setup due to density dierence of waterbetween low and ig te,perature sections

A super eater is used to super eat te wet1/19/15 %%Prof. Varaprasada Rao Ex.NTPC








plant



p

Co,bustion of fuel is acco,plised by

,iing wit air at ele+ated te,peratures"ygen in te air ce,ically unites wit

Carbon* $ydrogen of fuels and produce eat

In ter,al power plants nor,ally stea, isproduced fro, water by using co,bustioneat of fuels >cept in Gas turbines

Various fuels were used in ter,al power

plants@ossil fuels Coal* "il F Gas

Industrial waste gases

Syntetic fuels or S(@?>BS 1/19/15 9#Prof. Varaprasada Rao Ex.NTPC

Coal



CoalCoal i the 'rinci'al energ0 o+rce )or In*ia -eca+e

o) it large *e'oit an* aaila-ilit0

Coal originate* )ro, egeta-le ,atter2 which grew,illion o) 0ear ago

Tree an* 'lant )alling into water *eca0e* an* later'ro*+ce* 'eat -og

3+ge geological +'heaal -+rie* thee -og +n*erla0er o) ilt

$+-terranean heat2 oil 're+re an* ,oe,ent o)earth4 cr+t *itille* o o,e o) the -og4 ,oit+rean* har*ene* it to )or, coal

6aicall0 clai/cation o) coal i -ae* on Ph0icalan* che,ical co,'oitionPeatLignite an* -rown coal6it+,ino+ coal

Anthracite1/19/15 93Prof. Varaprasada Rao Ex.NTPC

Coal analysis



Coa a a ys s 2wo types of coal analysis

Proi,ate Anal0i Gi+es5 =ea+ior of coal wen eated

8C :M M A % 1;;< -0 ,a

=lti,ate Anal0i

Gi+es5 ce,ical ele,ents along wit as and ,oistureC 3 ; N $ M A % 1;;< -0 ,a

based on

a as)recei+ed basis useful for co,bustion calcu

b dry or ,oisture free basis

c dry ,ineral),atter)free or co,bustible basis




Coal properties 2ere are certain properties of coal* wic arei,portant in power plant applications

2ey are

sulpur content*eating +alueas softening te,perature swelling inde

grind ability*weater ability*


Desirable properties of coal $ig caloriHc +alue



g ca o c a ue

S,all sulpur content les tan 1%

Good burning caracteristics for co,pleteco,bustion

$ig grind)ability inde

$ig weater)ability

Grading of coal done on te basis$eating +alue

SiEe

As content

Sulpur content

As softening te,perature

1/19/15 9!Prof. Varaprasada Rao Ex.NTPC



3eat

Bow grade coal

@irst stage coal for,ation

Contains #0% ,oisture

S,all a,ount of +olatile ,atter

(ot suitable for power plants

?sed in do,estic purposes

Re/uires 1) ,onts for drying in sunligt

3eat 0% water* Dried as CV of 18 9M -g

1/19/15 9"Prof. Varaprasada Rao Ex.NTPC

Bignite =rown coal



g Inter,ediate stage of coal de+elop,ent

$ig a,ount of ,oisture !0)&0%=rown in color

$ig eating +alue and carbon co,pared topeat

Sould be stored to a+oid spontaneousco,bustion

?sed in pul+eriEed for,

Can be air dried easily

Suitable for local use instead of transporting

1/19/15 9%Prof. Varaprasada Rao Ex.NTPC

=itu,inous coal



Containing &8);8% of Hed carbon and 0)&0%of V9

As content ,ay +ary 8)1 %

$ig percentage of +olatile ,atter CV of ! 9M <g

A+ailable in two for,s CA<I(G and ("( Ca-ingSub)=itu,inous is a+ing less ,oisture* as

tan lignite and no CA<I(G power* used inbri/uette or pul+eriEed for,

Se,i)=itu,inous coal ig carbon and eating+alue* contain less ,oisture* as* sulpur* FV9*$as tendency to brea- into pieces


Antracite Coals



Contains ,ore tan ;8% Hed carbon FV9 around;%

Ignites slowly as ig CV of !8 9M <gBow as* Eero CA<I(G power

DiJcult to pul+eriEe Antracite coal

1/19/15 1$$Prof. Varaprasada Rao Ex.NTPC

Bi/uid fuels



2ey are easy to andle* store and to burn 2ey a+e nearly constant eating +alues 2ey are pri,arily a ,iture of ydrocarbon

co,pounds* wic ,ay also contain nitrogen* oygenand sulpur

2e bul- of te ydrocarbons belong to te paraJnseries* li-e ,etane C$&* etane C$8 propaneC!$; and butane C&$10 wic are gaseous* andpentane C$1 eane C8$1& and octane C;$1;wic are li/uid at S23

In addition* tere can be isoparaJns* cycloparaJns and1/19/15 1$1Prof. Varaprasada Rao Ex.NTPC



Gaseous fuels



Gaseous ue s 2ransportation of natural gas is ,ade troug

pipelines

(atural gas is te cleanest of all fossil fuelsIt is free fro, as and ,ies well wit air to

undergo co,plete co,bustion producing +erylittle s,o-e

It consists of a ,iture of te ,ost +olatileparaJns),etane to pentaneIt as ig ydrogen content and produces a

considerable a,ount of water +apour wenburned

2e eat of co,bustion +aries fro, !!. to &09M,!

Since te ,aLor constituent of all natural gasesis ,etane

Bi uid natural as B(G is trans orted b1/19/15 1$3Prof. Varaprasada Rao Ex.NTPC

"ter fuelsIn* trial Wate > 6 'ro* ct



In*+trial Wate > 60'ro*+ct

blast furnace gas* co-e o+en gas* and reHnery gas

sugar factory refuse bagasseO saw ,ill wood dust*rice us-

$0nthetic )+el

Gaseous and li/uid fuels fro, coal econo,ically

and en+iron,ent friendly ,anner

Li?+i* )+el +ing ,it+re o) /ne coal in oilhae -een @nown a colloi*al )+el2 coal(in(oilan* ,ore recentl02 coal(oil ,it+re COMB

1/19/15 1$4Prof. Varaprasada Rao Ex.NTPC

Coal andling



o o

C H. P


C l C h



Coal Cr+her

1.Ring 2ype Coal Cruser

.$a,,er 9ill Coal Cruser

!.=rad @ord =rea-er

1/19/15 1$!Prof. Varaprasada Rao Ex.NTPC

Ri 2 C l C



Ring 2ype Coal Cruser

1/19/15 1$"Prof. Varaprasada Rao Ex.NTPC



$a,,er 9ill Coal Cruser

1/19/15 1$%Prof. Varaprasada Rao Ex.NTPC



"3>RA2I"( 2e coal is fed at te top

Is crused by te action of rings tat pi+ot ocentre on a rotor or by swinging a,,ers

attaced to itAdLustable screen bars deter,ine te

,ai,u, siEe of te discarged coal


=rad @ord =rea-er



1/19/15 11$Prof. Varaprasada Rao Ex.NTPC



=rad @ord =rea-er=radford brea-er wic is used for largecapacity wor-

It consists of a large cylinder ,ade up of

perforated steel plates to wic lifting sel+es are attaced on te inside 2e cylinder rotating slowly at about 0 rp,

recei+es coal at one end

2e sel+es lift te coal up and ten te coaldrops down by gra+ity


C - ti E i t



Co,-+tion E?+i',ent

)or L+,'e* coal -+rning

1. Grate)Hred furnaces

. Ca,ber)type or a,e furnaces

1/19/15 11#Prof. Varaprasada Rao Ex.NTPC



Grate


Ca,ber type



yp


Co,-+tion E?+i',ent 8or



Co,-+tion E?+i',ent 8or

6+rning Coal @uel bed furnaces coarse particles

3ul+eriEed coal furnaces Hne particles

Cyclone furnaces crused particles

@luidiEed bed furnaces crused s,allparticles


@uel bed furnaces coarse particles



2ere are two ways of feeding coal on to tegrate

1. "+erfeeding

. ?nderfeeding


"+erfeeding



g

1/19/15 11"Prof. Varaprasada Rao Ex.NTPC



"+erfeedingRecei+es fres coal fro, top surface asfollowing distinct Eones@res or green coal

Coal losing ,oisture Drying EoneCo-ing layer loosing of V9 Distillation Eone

Incandescent co-e @ied carbon is consu,edCo,bustion Eone

As layer progressi+ely cooled


"perations



3ri,ary air gets war,ed up as it ows troug

te as layerAs it passes troug te incandescent co-e

layer100 C Carbon con+erted to Carbondioide releasing eat continues till oygen isconsu,ed* if layer is tic- C" is con+erted toC" reducing layer te,perature water gasreaction also ta-es

2e strea, wile passing troug distillationEone V9 is added

In distillation Eone ,oisture is added

<now strea, contains1/19/15 119Prof. Varaprasada Rao Ex.NTPC

@or co,bustion of tis



strea,A ot ignition point In te range of 1000)1!00oCDone by pro+iding a Hre bric- lined arc wic

stores up te eat and re,ains at igte,perature

SuJcient fres airSecondary air or o+er)Hre air

2urbulence3ro+iding secondary air at rigt angles to up)

owing gas strea, e,erging out of fuel bed

1/19/15 1#$Prof. Varaprasada Rao Ex.NTPC



ResultsCarbon is in C"* C" bot are color less

Carbon wit ydrogen in V9 wic will becrac-ed to for, free carbon at ig

te,perature suspended in gas strea,If =urner is not designed properly or operated

properly leads to unburnt carbon particles tisappears as blac- s,o-e on ci,ney top

1/19/15 1#1Prof. Varaprasada Rao Ex.NTPC

?nderfeeding



?nderfeeding

1/19/15 1##Prof. Varaprasada Rao Ex.NTPC



?nderfeedingIn underfeeding coal is fed fro, below3ri,ary air passing troug oles in

tuyeres diuses troug spaces in te raw

green coal pic-ing up ,oistureIn distillation Eone to strea, V9 is addedIn incandescent Eone V9 brea-s readily

burns wit secondary air present abo+e it

were it is fed fro, topV9 burning is so,ewat cooler need

longer ti,e to ignite and burn




9ecanical Sto-ers"+erfeeding

1. 2ra+eling grate sto-er

. Cain grate sto-er

!. Spreader sto-er&. Vibrating grate sto-er

?nderfeed sto-er

. Single retort

8. 9ultiretort


2ra+eling grate sto-er






2ra+eling grate sto-erGrate surface is ,ade up of Cast Iron bars Loined togeter by lin-s to for, endless belt=elt wound around two sproc-ets

A coal gate regulates te dept of fuel bedSi,ultaneous adLust,ent of @uel bed

tic-ness* pri,ary air ow controls teburning rate so tat at te end of its rear as

only re,ains

1/19/15 1#!Prof. Varaprasada Rao Ex.NTPC

Ad+antages F



gDisad+antagesSi,ple and Initial cost is low

Reliable in ser+ice and ,aintenance is low

Gi+es ig rate of eat release per +olu,eof te furnace

Bi,ited coal can be carried on grate

Clin-er proble,s are co,,on

Ignition arces are re/uired 2ere is always so,e loss in te for, of

particles

1/19/15 1#"Prof. Varaprasada Rao Ex.NTPC

Spreader sto-er



Spreader sto-er

1/19/15 1#%Prof. Varaprasada Rao Ex.NTPC



Spreader sto-erCoal fro, opper is fed by rotating feeder@eeder nor,ally will a+e =lades Htted on

te dru,

@ine particles burn in suspensionSpeed of te feeder +aries wit te stea,

output of boilerGrate is ,ade up of CI bars* Bin-s

underneat te grate are connected to ale+er@uels used ,ay be =itu,inous* lignite*

wood waste* baggaseCoal siEe used in 8)!8 c,






?nderfeed sto-ers




9ultiple retort


syste,






=owl 9ill


=owl 9ill




=all and Race ,ill








Disad+antages

1. Added in+est,ent in coal preparation unit

. Added power needed for pul+eriEing coal

!. In+est,ent needed to re,o+e y as before illfan

&. Barge +olu,e of furnaces needed to per,itdesired eat release and to witstand ig gaste,perature


A$3 3ANLING



$D$TEMMechanical 3an*ling $0te,

30*ra+lic Ah 3an*ling $0te,

Low :elocit0 $0te,

3igh :elocit0 $0te,Pne+,atic Ah 3an*ling $0te,

$tea, et $0te,


AS$ $A(DBI(G @B"6 DIAGRA9



1/19/15 14$Prof. Varaprasada Rao Ex.NTPC

Mechanical 3an*ling $0te,



Mechanical 3an*ling $0te,


30*ra+lic Ah 3an*ling $0te, l i $



Low :elocit0 $0te,


30*ra+lic Ah 3an*ling $0te, L : l it $ t



Low :elocit0 $0te,


30*ra+lic Ah 3an*ling $0te,



0* a+ c a * g $0 e3igh :elocit0 $0te,


Pne+,atic Ah 3an*ling



g$0te,




2an- you

Documents

Power Plant Engineering_ Thermal Power Station