95268739 Project Report on Thermal Plant

7/23/2019 95268739 Project Report on Thermal Plant

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Industrial TrainingReport

On Water Treatment and Coaltesting At

Guru Nanak Dev Thermal

Plant Bathinda

Submitted By: Sapandeep Singh 2012052


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!nder the guidan"e o#

$rs%&r%$e"hani"al Dptt%'dd% S%&% T%T% "ellGNDTP(Bathinda

Department of MechanicalEngineering

S!!M MA"#A$ "STT%TE O& TEC'"O$O()*

MA+TA,

')*N+,-&DG&$&NT

DECLARATION

hereby declare that the pro-ect .or/ entitled 0Water treatment

and coal testing1 is an authentic record of my o.n .or/ carried

out at Bathinda as re2uirements of si3 months ndustrial Training

for the a.ard of the degree of B4E4 at %ni5ersity nstitute of

Engineering 6 Technology* #an-ab %ni5ersity* Chandigarh under

the guidance of Er4 T4"4Bansal and Mrs4 An-ali (upta* during 7-an8

9May 9;794


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student

Date: 9


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;;mm to 7;mm4 Then the coal is sent to secondary crusher

through for.ard con5eyors .here it is crushed from 7;mm to

9;mm as re2uired at the mills4 Then the coal is sent to boilers

.ith the help of primary fans4 The coal is burnt in the boiler4 Boiler

includes the pipes carrying .ater through them heat produced

from the combustion of coal is used to con5ert .ater in pipes into

steam4 This steam generated is used to run the turbine4 When

turbine rotates* the shaft of generator* .hich is mechanically

coupled to the shaft of turbine* gets rotated so* three phases

electric supply is produced4

The basic re2uirements are:8

&uel coal

Boiler

Steam turbine

(enerator

Ash handling system

%nit au3iliaries

.IST+R/

4


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Due to high rate of increasing population day by day* .idening

gap bet.een po.er demand and its a5ailability .as one the basic

reason for en5isaging the (4"4D4T4#4 for the state of #un-ab4 The

other factors fa5oring the installation of the thermal po.er station

.ere lo. initial cost and comparati5ely less gestation period as

compared to hydro electric generating stations4 The foundation

stone of (4"4D4T4#4 at bathinda .as laid on 7th"o5ember 7>*

the auspicious occasion of ;;thbirth anni5ersary of great (uru

"ana/ De5 +i4

The historic to.n of bathinda .as selected for this =rst andprestigious thermal pro-ect of the state due to its good rail.ay

connections for fast transportations of coal* a5ailability of canal

.ater and pro3imity to load center4

The total installed capacity of the po.er station ;MW .ith

four units of 77;MW each4 The =rst unit of the plant .as

commissioned in September* 7F4 Subse2uently second* third

and fourth units started generation in September 7F* March

7F


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-'ND$'R*S

').I&&D

(4"4D4T4#4 .on an a.ard of ,s4 G47> crores from (o5t4 of

ndia for better performance in 7


7/63

(4"4D4T4#4 had achie5ed a generation of 9F99; $%1s at

a #$f of F;H and registering an oil consumption as lo. as

74F>ml?/.h during the year 7G8 has bro/en all pre5ious

records of performance since the inception of plant4

,+R*ING 'T GNDTP

Coal recei5ed from collieries in the rail .agon is

mechanically unloaded by Wagon Tippler and carried by belt

Con5eyor System Boiler ,a. Coal Bun/ers after crushing in the

coal crusher4 The crushed coal .hen not re2uired for ,a. Coal

Bun/er is carried to the coal storage area through belt con5eyor4

The ra. coal feeder regulates the 2uantity of coal from coal

bun/er to the coal mill* .here the coal is pul5eri@ed to a =ne

po.der4 The pul5eri@ed coal is then suc/ed by the 5apour fan and

=nally stored in pul5eri@ed coal bun/ers4 The pul5eri@ed coal is

then pushed to boiler furnace .ith the help of hot air steam

supplied by primary air fan4 The coal being in pul5eri@ed state

gets burnt immediately in the boiler furnace* .hich is comprised

of .ater tube .all all around through .hich .ater circulates4 The.ater gets con5erted into steam by heat released by the

combustion of fuel in the furnace4 The air re2uired for the

combustion if coal is supplied by forced draught fan4 This air is


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ho.e5er heated by the outgoing Iue gases in the air heaters

before entering the furnace4

The products of combustion in the furnace are the Iue gases

and the ash4 About 9;H of the ash falls in the bottom ash hopper

of the boiler and is periodically remo5ed mechanically4 The

remaining ash carried by the Iue gases* is separated in the

electrostatic precipitators and further disposed oJ in the ash

damping area4 The cleaner Iue gases are let oJ to atmosphere

through the chimney by induced draught fan4

The chemically treated .ater running through the .ater

.alls of boiler furnace gets e5aporated at high temperature into

steam by absorption of furnace heat4 The steam is further heated

in the super heater4 The dry steam at high temperature is then led

to the turbine comprising of three cylinders4 The thermal energy

of this steam is utili@ed in turbine for rotating its shaft at high

speed4 The steam discharged from high pressure '4#4 turbine is

returned to boiler reheater for heating it once again before

passing it into the medium pressure M4#4 turbine4 The steam is

then let to the coupled to turbine shaft is the rotor of the

generator* .hich produces electricity4 The po.er from the

generator is pumped into po.er grid system through the

generator transformer by stepping up the 5oltage4


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The steam after doing the useful .or/ in turbine is condensed to

.ater in the condenser for recycling in the boiler4 The .ater is

pumped to deaerator from the condenser by the condensate

e3traction pumps after being heated in the lo. pressure heater$4#4' from the deaerator* a hot .ater storage tan/4 The boiler

feed pump discharge feed .ater to boiler at the economi@er by

the hot Iue gases lea5ing the boiler* before entering the boiler

drum to .hich the .ater .alls and super heater of boiler are

connected4

The condenser is ha5ing a large number of brass tubesthrough .hich the cold .ater is circulated continuously for

condensing the steam passing out sides the surface of the brass

tubes* .hich has discharged do.n by circulating it through the

cooling to.er shell4 The natural draught of cold air is created in


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the cooling to.er* cools the .ater fall in the sump and is then

recirculated by circulating .ater pumps to the condenser4

P-'NTS S'-I&NT

&'T!R&S

PR+3&)T 'R&'4

#o.er plant 9G< acres

Ash disposal


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Total area 7


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,ated pressure 7G; /g?cmK

,ated temperature GC

Condenser 5acuum ;4 /g?cmK

G&N&R'T+R4

Manufacturers B4'4E4$4

,ated output

%nit8 7 6 9 79;;;!A

%nit 8G 6 7GF;;;!A

(enerator 5oltage 77;;; 5olts

,ated phase current

%nit N7 6 9 >>; Amps4

unit NG 6 F99; Amps4

(enerator cooling hydrogen

B+I-&R &&D P!$PS4

"umber per unit t.o of 7;;H duty each

Type centrifugal

,ated discharge T?hr4

Discharge head 7>; MWC4

Speed ;; r4p4m4


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)IR)!-'TING ,'T&R P!$PS4

"umbers for t.o units =5e of ;H duty each

Type mi3ed Io.

,ated discharge ;; T?hr4

Discharge head 9 MWC4

)++-ING T+,&RS4

"umbers four

Water cooled 7


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Coal crusher 9; !W

#rimary air fan G9; !W

&orced draught fan G9; !W

Boiler feed pump G;; !W

nduced draught fan ;;?7;;; !W

Condensate pump 7F !W

DI&R&NT )&--S +

P-'NT

).P 8)oal .andling Plant9

The (4"4D4T4#4 units are primarily coal8=red units and the coal

consumption at ma3imum continuous rating M4C4,4 per unit is

about < T?'r4 the coal used at (4"4D4T4#4 is of bituminous and

sub8bituminous type and this is recei5ed from some collieries of

M4#4 and Bihar4


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!N-+'DING + )+'-4

n order to unload coal from the .agons* t.o ,otaside

Tipplers of Elecon ma/e are pro5ided4 Each is capable of

unloading 79 open types of .agons per hour4 "ormally one tippler

.ill be in operation .hile the other .ill be standby4 The loaded

.agons are brought to the tippler side by the loco shunters4 Then

.ith the help of inhaul beetle one .agon is brought on the tippler

table4 The .agon is then tilted upside do.n and emptied in the

hopper do.n belo.4 The tippler is e2uipped .ith the integral

.eighbridge machine4 This machine consists of a set of .eighingle5ers centrally disposed relati5e to tippler4 The rail platform rests

on the .eighing girders and free from rest of the tippler .hen the

.agon is being .eighed4 After .eighing the loaded .agons is

tipped and returned empty to the .eighing girders and again

.eighed4 Thus the diJerence of the gross .eight and the tare

.eight gi5es the .eight of the .agon contents4 The tipplers are

run by motors of


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screen gets bloc/ed* a pay loader truc/ can be employed .hich

.ill lift all the o5er si@ed coal and ta/e it to a suitable place .here

it can be bro/en either manually or by a crusher4 Thus it .ill sa5e

time as the trolleys can be emptied faster* sa5ing damages4

!S& + -+'D )&-- T/P& ,&IG.BRIDG& +R ,&IG.$&NT

IN $+TI+N 4

$oad ceil type .eighbridges are sometimes called dynamic

.eighbridge because the .agons can be handled o5er them at a

ma3imum speed of up to 79 m4p4h4 They consists of t.o platforms

one for gross and one for tare .eights4 Each .agon .eight is

automatically printed out and so is the rail.ay loop4 &irst the

gross .eights are established and memori@ed* then the train is

mo5ed o5er the rail trac/ hopper for discharge* after the emptytrain is mo5ed out o5er the tare .eighbridge platform .here the

tare .eights are printed out4 &inally the total net .eight is

computed and printed out4 The load cells at each .eighbridge are

connected to a digiti@er suitable for con5erting the analogue

output of the load cell into digital form4


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Wagon Tippler

When coal reaches the plant* normal si@e of coal is about ;;mm

primary crusher 79;mm secondary crusher 9mm

coal mill pul5arised coal *feeded in boiler4

Before this boiler is preheated .ith oil upto G;;c*then oil supply

is cut do.n4


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Con5eyer Belt


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Boilers

t is a single drum* balanced draught* natural circulation* reheat

type* 5ertical combustion chamber consists of seamless steel

tubes on all its sides through .hich .ater circulates and is

con5erted into steam .ith the combustion of fuel4 The

temperature inside the furnace .here the fuel is burnt is of the

order of 7;;C4 The entire boiler structure is of 9meter height4

B+I-&R ).I$N&/4 The Iue from the boiler* after remo5al of ash in the

precipitators* is let oJ to atmosphere through boiler chimney* a

tall &erro8concrete structure standing as high as the historic utab

Minar4 &our chimneys* one for each unit* are installed4 The

chimney is lined .ith =re bric/s for protection of &erro8concrete

against hot Iue gases4 A protecti5e coating of acid resistant paint

is applied outside on its top 7; meters4

Boilers burn the fuel transferred from the tan/ and use the

resulting heat to con5ert .ater into steam4 nside the boilers are

tens of thousands of .ater8carrying tubes4 When combustion

commences* the temperature inside the boilers rises to bet.een

7*7;; and 7*;;PC* the .ater inside the tubes is turned into high8temperature and high8pressure steam* and the steam is

transferred to the steam turbines4


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)IR)!-'TING ,'T&R P!$P4

T.o nos4 of circulating .ater pumps pro5ided for each unit*

circulate .ater at the rate of 7F9;; T?hr4 in a closed cycle

comprising of Turbine Condenser and Cooling To.er4 An additional

Circulating Water #ump pro5ided ser5es by for t.o units4 The

.ater re2uirement for bearing cooling of all the plant au3iliaries is

also catered by these pumps4

Boiler


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Boiler spe"i:"ations

&eed .ater temperature 9;C

&inal super heater?reheater temperature ;C

Super heater outlet pressure 7G/g?cmK

ELciency H

Coal consumption per day per unit 7;; tones

Appro3imate


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Tur;ines

The steam rotates the turbine blades at a high speed of G*;;;

rpm4 This turns the po.er generator* .hich is directly connected

to the turbines* and electricity is produced as a result4 This

electric po.er is then deli5ered along po.er transmission lines

and through substations to the homes of customers4

Turbine is a prime mo5er for the (enerator in the po.er plant4 n

steam turbine* the potential energy of steam is transformed into

/inetic energy and later in its turn is transformed into the

mechanical energy of the rotation of the turbine shaft4 The

common types of turbines are:8

I$P!-S& T!RBIN&4n this type of turbine* steam

e3pands in the no@@les and its pressure does not alter as it

mo5es o5er the blades4

R&')TI+N T!RBIN&4n this type of turbine* the

steam e3pands continuously as it passes o5er the blades andthus there is a gradual fall in pressure during e3pansion4


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I$P!-S&

T!RBIN& R&')TI+N T!RBIN&

DiJerent types of steam turbines are used in Thermal #o.er

#lant but the ones .hich are used at (4"4D4T4#4 are categori@ed as

follo.s:8

Sr% No% T


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G4 mpulse?,eaction mpulse

4 Condensing?"on8condensing Condensing

4 ,eheat?"on8reheat ,eheat

>4 ,egenerati5e?"on8 ,egenerati5e With bypass

ST87

F4 With bypass?Without bypass Without bypass

ST89

MA" TEC'"CA$ DATA

a The basic parameters:

,ated output measured at Terminal of the generator4

77;4;;;!W

Economical output4

4;;;!W

,ated speed4 G4;;;,#M

,ated temp4 of stearn -ust before the stop 5al5e4

GC

Ma3 Temp4 of steam before the stop 5al5e4

C


25/63

,ated pressure of steam before the M# casing4

G74>GC

Ma34 pressure of steam before the M# casing

GC

,ated temp4 of steam before the M# casing4

GC

Ma34 temp4 of steam before the M# casing4

C

b System of turbine:

(o5erning 5al5es Q9 interceptor 5al5es '# cylinder8 9 ,o.

Curtis .heel Q< mo5ing .heels4

Wt4 Of '# rotor appro34 *;; !g4

M# cylinder 8 79 Mo5ing .heels4

Wt4 Of M# rotor4 Appro34 77*;;; !g4

$# cylinder 8 Mo5ing .heels of double Io. design4

Wt4 Of M# rotor appro34 9*;;; !g4

Direction of the turbine rotation 8 To the right* .hen loo/ing at the

turbine from the front bearing pedestal4


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General Spe"i:"ations o# Tur;ine

Manufacturers B4'4E4$4

,ated output 77; MW4

,ated speed G;;; r4p4m4

"umber of cylinders three

,ated pressure 7G; /g?cmK


27/63

,ated temperature GC

T!RB+G&N&R'T+R4

The hydrogen8cooled generator is directly coupled to the

turbine shaft rotating at speed of G;;; rpm generating electricity

at 77;;; 5olts4 The turbine is hori@ontal* three casings* reheat*

steam condensing* regenerati5e and of impulse type e2uipped

.ith a precise oil operated speed go5ernor4 The generated 5oltage

is stepped by unit po.er transformer to state grid system4

)ir"ulating =ater pump4

T.o nos4 of circulating .ater pumps pro5ided for each unit*

circulate .ater at the rate of 7F9;; T?hr4 in a closed cycle

comprising of Turbine Condenser and Cooling To.er4 An additional

Circulating Water #ump pro5ided ser5es by for t.o units4 The

.ater re2uirement for bearing cooling of all the plant au3iliaries is

also catered by these pumps4

N&&D + ' )+ND&NS&R4 A condenser .here the e3haust

steam from the turbine is condensed* operates at a pressure

lo.er than atmosphere4 There are t.o ob-ects of using a


28/63

condenser in a steam plant4 There are t.o ob-ects of using a

condenser in a steam plant:8

- To reduce the turbine e3haust pressure so as to increase the

speci=c output of turbine4 f the CW cooling .ater

temperature in a condenser is lo. enough4 t creates a bac/

pressure 5acuum for the turbine4 This pressure is e2ual to

the saturation pressure corresponding to the condensing

steam temperature4 Which is a function of cooling .ater

temperature4 t is /no.n that the enthalpy drop or turbine

.or/ per unit pressure drop is much greater at the lo.

pressure end than at the high pressure end of a turbine4

- A condenser by lo.ering the bac/ pressure say 74;7G to

;4;F bar* thus increases the plant eLciency and reduces

the steam Io. for a gi5en output4 The lo.er the pressure*

the greater the output and eLciency4 t is important to use

lo.est possible cooling .ater temperature4

This reduces the temperature rise of cooling .ater in the

condenser tubes to 8


29/63

T/P&S4There are t.o broad classi=cations:8

a Direct contact type condenser:8 .here the condensate and

cooling .ater directly mi3 and come out as a single

stream4

b Surface condenser:8 .hich are shell and tube heat

e3changers .here the t.o Iuids do not come in direct

contact and heat released by the condensation of steam is

transferred through .alls of the tubes into the cooling

.ater continuously circulating inside them4

DIR&)T )+NT')T )+ND&NS&RS4

- Spra< "ondenser

- Barometri" "ondenser

- 3et "ondenser

n the spray condenser* the cooling .ater is sprayed into the

steam4 Steam by mi3ing directly .ith cold .ater gets

condensed4 The e3haust steam from the turbine at state 9

mi3es .ith cooling .ater at state to produce saturated .ater

at state G* .hich is pumped to state 4

n barometric condenser* the cooling .ater is made to fall in

a series of baRes to e3pose large surface area for the steam

fed from belo. to come in direct contact4 The steam condenses

and falls in a tail pipe to the hot .ell belo.4 By 5irtue of its

static head* the tail pipe compresses the mi3ture to

atmospheric pressure4


30/63

n a -et condenser* the height of the tail pipe is reduced by

replacing it .ith a diJuser4 The diJuser helps raising the

pressure in a short distance than a tail pipe4

S!R')& )+ND&NS&RS4 Surface condenser is another type

of condenser used in po.er plants4 n (%,% "A"A! DE

T'E,MA$ #$A"T surface condensers are used4 These are

essentially shell and tube heat e3changers4 &or the

con5enience of cleaning and maintenance cooling .ater Io.s

through the tubes and steam condenses outside the tubes4 n

our plant surface condenses t.o passes of .ater bo3es on each

side4 The hot .ell acts as a reser5oir of the condensate4 The

condenser plays a 5ital role4 n our plant t.o surface

condensers are used in one plant1s unit4 There are >


31/63

)+ND&NS'T& )/)-&4 Steam after .or/ing in the three

casings of the turbine i4e4 '4#4* M4#4 and $4#4 casing is considered

in t.o surface condensers in each unit installed -ust belo. the

$4#4 turbine1s e3haust hood4 The condenser so to call hot .ell

from .here it is pumped up to deaerator by condensate

e3traction pumps through diJerent heating stages4 The

diJerent heating stages through .hich the condensate Io.s

and gets heated up gradually before =nally reaching the

deaerator feed .ater tan/ are as belo.:8

.&'TING ST'G& T&$P% RIS& 'T !-- -+'D

Main steam -et air e-ector G8


32/63

)+ND&NS&R4 The function of the surface condenser is to

condense the steam e3hausted from the $4#4 casing and to

create 5acuum in order to increase the heat drop4 Capacity of

each hot .ell is >9;; liters and the temperature of condensate

in the hot .ell is about ;8C4

P'RTI)!-'RS + )+ND&NS'T&4

&7TR')TI+N P!$P4

"umber of pumps: G for each unit .ith ;H capacity each* one

stand by4

"umber of stages: >

Discharge pressure: 9;4894 /g?cmK

Suction pressure: 8;4< to N;4 /g?cmK

ST&'$ 3&T 'IR &3&)T+R4

The main function of steam -et air e-ector is to maintain the5acuum in the steam condenser by e-ecting the air and non8

condensate gases4 The steam from pressure reducing station is

supplied to steam -et air e-ector4 This steam .hen passed through

the no@@les in a 5enturi de5elops pressure drop* .hich causes the

air and non considerable gases to rush from the condenser* thus

maintaining the re2uired 5acuum in the condenser4 After that heat

of this steam is utili@ed in heating up the main condensate Io.ing

through in the steam -et air e-ector4 The steam -et air e-ector is

built up in the condenser4


33/63

-+, PR&SS!R& .&'T&RS4

There are =5e numbers of $4#4 heaters through .hich the main

condensate Io.s and gets heated up gradually in each stage of

heaters before =nally going to the deaerator4

The $4#4 heaters 7 and 9 are in t.o parts and placed in the

e3haust hood of condenser i4e4 e3haust hood of $4#4 turbine and

are connected in series4 $4#4'48G* $4#4'48 and $4#4'48 are placed in

chimney steam condenser and gland steam condenser in the

condensate Io. circuit4 The charging steam to these heaters is

gi5en from the steam e3tractions ta/en from the $4#4 6 M4#4

cylinders of the turbine4 Steam e3traction to $4#4'487 is ta/en from

$4#4 casing in t.o parallel Io.s* same in $4#4'4894 Steam to $4#4'48G

is also ta/en from $4#4 casing4 Where as steam to $4#4'48 and

$4#4'48 is ta/en from M4#4 casing4

The main condensate gets heated up by about 7;;C after

passing through these heating stages4 The condensate of heating

steam in these $4#4 heaters is /no.n as drip4

).I$N&/ ST&'$ )+ND&NS&R4

t is a sort of heater in .hich .aste chimney steam* ta/en from

the outer lea/s of the gland seals of '4#4* M4#4 and $4#4 cylinders of

the turbine* is utili@ed in heating up the main condensate4 The

drip of chimney steam condenser is generally mi3ed .ith air and

is collected in impure condensate tan/ from .here it is pumped to

Ioor drains4


34/63

G-'ND ST&'$ )+ND&NS&R4

t is also a sort of heaters* steam to gland steam condenser is

ta/en from inner lea/s of the sealing glands of '4#4 and front

gland of M4#4 cylinders of the turbine and after heating the main

condensate* the drip of gland steam condenser being pure* is

directly ta/en to the hot .ell4


35/63

)ooling to=ers4

)ooling To=ers


36/63

Cooling To.ers of the po.er plant are the land mar/ of the

Bathinda City e5en for a far distance of


37/63

'sh pre"ipitators

,+R*ING PRIN)IP-& + &SP


38/63

The electrostatic precipitator installed at ("DT#*Bathinda

units to e3tract dust* utili@es electrostatic forces to separate dust

particles from the gas be cleaned4 The gas is conducted to a

chamber containing Curtains of 5ertical steel plates4 These

curtains di5ide the chamber into a number of parallel gas

passages4 A frame .ith secured .ires is located .ithin each

passage4 All the frames are lin/ed to each passage4 The frames

are lin/ed to each other to form a rigid frame.or/4

The entire frame .or/s is held in place by four support

insulators* .hich is electrically from all* .hich are grounded4

A high 5oltage direct current is applied bet.een the

frame.or/ the ground thereby creating a strong electrical =eld

bet.een the .ires in the frame.or/ and the steel curtains4 The

electrical become strongest near the surface of the .ires* so

strong that an electrical discharge4 The corona discharge

de5elops along the .ires4 The gas is ioni@ed in the corona

discharge and large 2uantity of positi5e and negati5e ions are

formed4 The positi5e ions are immediately attracted to.ards the

negati5e .ires by the strength of the =eld indicate the negati5e

ions ho.e5er ha5e to tra5erse the entire space bet.een the

electrodes to reach positi5e curtains4

Enroute to.ards the steel curtains* the ions collide and

adhere to the particles in the gas4 The particles thereby become

electrically charged and also begin to tra5el in the same direction

as the ions to.ards the steel curtains4 The electrical force on each


39/63

particle becomes much greater than the gra5itational force on the

particle4 The speed of migration to.ards to steel curtains is

therefore much greater than the speed of sedimentation in free

fall4

The Iy ash carried by outgoing Iue gases is arrested at t.o

stages4 n the mechanical precipitators* the coarse ash particles

are separated out by centrifugal action4 n the Electrostatic

#recipitators* the =ner ash particles in the Iue gases are made to

pass through high 5oltage electric =eld* .here these particles get

ioni@ed and are attracted to.ards the collecting electrodes4 The

dry ash is collected in the hoppers underneath and further

deposited oJ in Ash Disposal Area4


40/63

Pro>e"t

,ater treatment and )oal

testing

Boiler is the heart of thermal plant* its main purpose is to con5ert

.ater into steam4

"atura l . ater is a5ai lable in abundance* but it contains

impurities in many forms .hich are as follo.ing types4

Types of impuritiesU4


41/63

Water hardness is primarily because of calcium and

magnesium minerals* and hardness is responsible for

scale formation4

Carbonates or temporary hardness8 0Ca1 and 0Mg1bicarbonates are responsible for al/aline hardness* but

on applying heat release )+2 and form soft scale4

"on8Carbonates or permanent hardness8 due to presence of

salt of calcium and magnesium but in form of sulphates and

chlorides4 On applying heat these ppt4 out and form

hard scale* .hich is diLcult to remo5e4

Water Al/alinity is because of bicarbonates*

carbonates4

Al/alinity can con5ert to )+2 in steam4 This

causes corrosion4

When p' is belo. the recommended range chances of

corrosion increases* and .hen it is abo5e

recommended 5alue then chances of scaling increases4

Boiler scale lo.ers heat transfer due to lo. thermalconducti5ity4 'eat transfer may be reduced as much as

87;H by the presence of scale4


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Due to s"aling #ollo=ing are the negative e?e"ts on

the =orking o# plant

a4 increased fuel bill by decreasing the operating eLciencyb4 thermal damage

c4 increased cleaning time and cleaning costs

d4 reduced .or/ing life of a boiler4

Pre Treatment o#

,ater

)anal =ater

-ake

-ake

-ake

Intake pump


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)lari:er 8'lumdosing9

To ma/e .ater free from suspended* colloidal and organic

impurities*process in5ol5ed in pre8treatment are:8'9 Settling and )oagulation

Coagulant turbidity* micro8organismsreacts .ith the

al/alinity of the .ater to form a gelatinous precipitate

)lear =ell


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)lear =ell

Pump )lear =ell

iii ii i


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Sand ilters

Sand :lters

B9 iltration

#assage of Iuid through a porous medium using sand =lter

arrangement to remo5e matters holding suspension4

74 Suspended silt

94 Clay

G4 Colloids

4 Micro organisms including algae* bacteria and 5irus


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Demineralisation

S


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D$ Plant -a


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)ation e@"hangermainly remo5es Calcium* Magnesium*

sulfates* chloride* nitrates and sodium salts al/alinity from

ra. .ater4

n cation e3changer positi5e ion of the salt is e3changedby the'Q ion

On discharging* it is charged .ith ;;!g of G;H'cl4

)ation &@"hanger


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Carbon dio3ide generated by dissociation of carbonic acid at

cation outlet .ater* is remo5ed by degassersystem4

Water from outlet of cation e3changer is made to fall

from a height* and a pressuri@ed air is blo.n upstream

of the .ater Io. to separate gases4

Degasser Blo=er

Degasser

Tan/


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'nion e@"hangersremo5e the highly dissociated acids li/e

'9So* '"oG*

'cl from the eRuent of cation e3changer4

n anion e3changer negati5e charged part of the salt is

e3changed by the O'8ion4

On discharging* it is charged .ith 9;;!g of

F4H"aO'4

'nion &@"hanger


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$i@ed;ed

Deionisation

ERuent .ater after anion e3changer may still ha5e some saltsdue to them its conducti5ity is around 787 micro4mhos4 F

p' 7;* so it is further passed through Mi3ed Bed Deioniser* as

sho.n belo.4The mi3ed bed mi3ture of Cation and Anion resins

form in=nite numbers of demineralising stages through .hich DM

.ater passing and thus remo5ing the traces of minerals4 By this

method demineralised .ater of e3tremely pure 2uality is

achie5ed4

$i@ ;ed deioniser


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On discharging* it is charged .ith 7;;/g in-ection of each 'cl

and "aO'4

GNDTP has 2 units o# D$ Plant( ea"h having "apa"it

95268739 Project Report on Thermal Plant

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