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Parametric Analysis of Combined Cycle Power Plant using Steam Jet

Inlet Cooling

Kumar Sourav a,*, Dhaneshwar ahto b

a!"! Student, De#t! of echanical "ngg!, $irla Institute of %echnology,esra,&anchi, India

bAsst! Professor, De#t! of echanical "ngg!, $irla Institute of %echnology,esra,&anchi, India

Abstract

Combined cycle #ower #lant integrates two cycles ' $rayton cycle ()as %urbine and &an+ine

cycle (Steam %urbine with the obective of increasing overall efficiency! A demonstration #lant

using this cooling technology does not e-ist so far, therefore the o#erational behavior has notbeen investigates so far! %he combined cycle #ower #lant em#loyed in this #roect uses Steam et

cooling in order to cool the inlet.air entering the com#ressor! %he cooling is done in order to

increase the efficiency of the overall combined cycle #ower #lant as well as to reduce the lossesdue to the high tem#erature occurring inside the com#ressor! Also, the #ower consumed by thecom#ressor increases in #ro#ortion to the inta+e air tem#erature without there being a

corres#onding increase in the out#ut from the turbine! %he theory involved in the et cooling is

that an eva#oration of / +g of water leads to cooling of about 01C! %he #arametric analysis isdone using A%2A$3!

Keywords4 5&S), Steam %urbine, Steam Jet &efrigeration, %urbine Inlet %em#erature

1. Introduction

"lectrical energy is a basic re6uirement for

the sustenance and develo#ment of themodern society! India is marching towards

achieving a desirable status of a develo#ed

country with ra#id strides! "nsuring

uninterru#ted su##ly of energy to su##orteconomic and commercial activities is

essential for sustainable economic growth!

In true sense, sustainable develo#mentshould be widely s#read in all three

dimensions . social, economic, andenvironmental! 7or all these areas, energy is#erha#s the most im#ortant as#ect! %he

#roduction and the consum#tion #atterns at

the local and the global scale, determine notonly all the activities in society, but also

some maor environmental issues li+e

#ollution, green house effect, and

desertification! ost of the generation today

is met by #lants utili8ing fossil fuels li+ecoal, natural gas and uranium! 9ith the

increase in the demand of electric#owermore generation is re6uired! %his #roblem

can be solved by increasing the generationby either increasing the number of

generating stations or by increasing the

efficiency of the e-isting #lants! Asincreasing the number of generatingstations

would be uneconomical and would cause#roblems related to installation, thegeneration has to be increased by the later

method! %he #lants using fossil fuels as their

source of energy have low efficiency as theyare not able to fully utili8e the calorific

value of the fuel! Combined cycle #ower

#lant integrates two cycles ' $rayton cycle

aCorresponding Author Contact : [email protected], Ph: 8238!2!31
mailto:[email protected]:[email protected]

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()as %urbine and &an+ine cycle (Steam

%urbine

2. Model Construction

%he system com#rises of a 5eat recovery

steam generator (5&S), steam turbine,

boiler feed #um#, a condensate #um# and a

deaerator! %he 5&S) used is a single#ressure system without su##lementary

firing! %he 5&S) consists of an eva#orator,an economi8er and a su#erheater! $y

su#er#osing a high tem#erature #ower #lant

as a to##ing unit to the steam #lant , a higher

energy conversion efficiency from fuel toelectricity can be achieved, since the

combined #lant o#erates through a higher

tem#erature range! In the basic form ofCombined cycle #ower #lant, a gas turbine

e-hausting into a heat recovery steamgenerator that su##lies steam to a steam

turbine cycle is the most efficient system of

generating electricity today!

3. Working

Combined cycle #ower #lant as in name

suggests, it combines e-isting gas and steam

technologies into one unit, yielding

significant im#rovements in thermalefficiency over conventional steam #lant!

%he air which is #urified then com#ressedand mi-ed with natural gas and ignited,

which causes it to e-#and! %he #ressure

created from the e-#ansion s#ins the turbine

blades, which are attached to a shaft and agenerator, creating electricity! In second ste#

the heat of the gas turbine:s e-haust is used

to generate steam by #assing it through aheat recovery steam generator (5&S) with

a live steam tem#erature between ;= ?C!

7ig /! $asic Combined Cycle

In 5eat &ecovery Steam )enerator highly#urified water flows in tubes and the hot

gases #asses a around that and thus

#roducing steam !%he steam then rotates thesteam turbine and cou#led generator to

#roduce "lectricity! %he hot gases leave the

5&S) at around /;= degrees centigrade andare discharged into the atmos#here! %he5&S) is basically a heat e-changer, or

rather a series of heat e-changers! %he5&S) can rely on natural circulation or

utili8e forced circulation using #um#s! AsaCorresponding Author Contact : [email protected], Ph: 8238!2!31

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the hot e-haust gases flow #ast the heat

e-changer tubes in which hot watercirculates, heat is absorbed causing the

creation of steam in the tubes! %he tubes are

arranged in sections, or modules, each

serving a different function in the #roduction

of dry su#erheated steam! %hese modulesare referred to as economi8ers, eva#orators,

su#erheaters@reheaters and #reheaters!

omenclature

CC Combustion Chamber

)% )as %urbine

S5 Su#erheater

"B "va#orator

"C "conomi8er

PD Pressure Drum

S% Steam %urbine

ma ass flow rate of air

%/ Com#ressor Inlet %em#erature

% %urbine Inlet %em#erature

Stwor+ Steam %urbine 9or+

%g; Stac+ tem#erature

%I% %urbine Inlet %em#erature

CP Coefficient of Performance


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Proposed Model:

7ig!< Combined Cycle em#loying Steam Jet &efrigeration

%he model #ro#osed here is consists of a

steam et refrigration system where steam

bleeding ta+es #lace at a certain #ressure!

Esing the eector com#ression a low

#ressure system is created inside and

entrainment ta+es #lace! 9ater gets cooleddue to eva#oration and is su##lied to the

heat e-changer where ambient air at higher

tem#erature gets cooled and is finally

transferred to the inlet of com#ressor! Since

the mass flow rate of air increases as a result

of increase in the density of air , more steam

gets generated in the 5&S)! 7inally, theoverall #lant efficiency increases!

Corresponding T-S iagra!:aCorresponding Author Contact : [email protected], Ph: 8238!2!31

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7ig! %em#erature."ntro#y Diagram

"esults:

7ig!;! %/ vs! Com#ressor 9or+ 7ig!0! % vs! )as %urbine "fficiency

7ig!F! % vs! stwor+ 7ig!G! % vs! efficiency


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7ig!F! % vs! %g;

%(%I%

%g; ms Hms/ Hms< Steamturbine.

wor+

overallefficiency

/== 0/!=// =!/ /;== 0/=!G> =!/= =!==FG /=!F/;= 0=!=

/0== 0=>G =!/= =!==>= /0!;/F= 0

/F== ;;!/0> =!G =!/= =!== />>!/ 0!>F

/G== ;>0!>G =!> =!/= =!=/

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"e#erences:

/L Irimescu Adrian, 2elea Dorin, %hermodynamic Analysis of gas turbine #owered cogeneration

systems, Journal of Scientific and Industrial &esearch, Bol F, July

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