Different Cycles in Gas Turbine & Steam Turbine

8/13/2019 Different Cycles in Gas Turbine & Steam Turbine

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Different cycles in Gas turbine& Steam Turbine

Presented By

VatsalaSharmaDy. Director

Vatsala Sharma,Dy Director


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Vatsala Sharma,DyDirector

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Energy Conversion Efficiency

Heat Input

100% 39% 61%

HeatRejected

ElectricalEnergy

Vatsala Sharma,Dy Director Avanta Power


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The change in entropy,

TdQS

In any spontaneous process,the entropy can not

decrease.

This is the second law of thermodynamics, with equality

holding for a reversible process.

.0S


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Latent Heat

T

Q added to water

watertemprises

Q = m L with L = Latent Heat L [J/kg]:

Q is the amount of heat needed to add or remove from a substance

with mass m to change the state of that substance.

Substance Lf(J/kg) Lv(J/kg)

water 33.5 x 104 22.6 x 105

water

changesto steam(boils)

steam

temprises

100oC


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The Ideal Gas Law

(review)

P V = N kB TN = number of molecules

N = number of moles (n) x NA molecules/mole

kB = Boltzmanns constant = 1.38 x 10-23J/K

P V = n R TR= ideal gas constant = NAkB = 8.31 J/mol/K


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PV Diagrams

Pf

i

f

ViVf

A gas expands (slowly) from

state i to state f. The work done

by the gas equals the area under

the PV curve.

PV Diagram-1

Pi


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Types of Cycles Carnot Cycle:- It is a hypothetical / Ideal cycle.

Rankine Cycle:- Used in Steam Cycle

Modified Rankine Cycle : Reheat & regenerative

Cycles

Binary Vapour Cycle (Working Fluid is Mercury)

Brayton Cycle:- Used hypothetical in Gas

Turbine

Otto Cycle

Diesel CycleVatsala Sharma,DyDirector

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The Carnot Cycle (Engine)

An idealreversible heat engine (no heat

engine can be more efficient than a Carnot

engine)

A 4 stage enginethat operates between 2temperature reservoirs (Thotand Tcold)

consisting of

2 isothermic phases

2 adabatic phases


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Carnot(ideal) engine:

% Efficiency = % Carnot= (QinputQout)/Qinput

since Qinput/Qout= Thot/Tcoldthe efficiency

can be written as


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Simplified Diagram


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Basic Power Plant Cycle

13

ABHeating of feed water (Sensible heat addition)

BCEvaporation of water in boiler (Latend heat addition)

CD _ Superheating of Steam (Superheat addition)

DEExpansion of steam in turbine

FA - Condensation of steam in the condenser


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Modified Rankine Cycle


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Increasing Of Thermal Efficiency

Thermal efficiency of the cycle is defined as:

Useful heat/ Total heat

Useful heat means that part of total which isused in rotating the turbine , when steam

expands adiabatically (no heat is accepted or

rejected during the process )in the turbine.


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THERMAL PROCESS LOSSES


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Hot Flue gas to Electricity ..

Basics

Coal

ChemicalEnergy

Super HeatedSteam

Pollutants

ThermalEnergy

TurbineTorque

Heat Loss

In

Condenser

KineticEnergy

ElectricalEnergy

Alternating currentin Stator

Mech. Energy

LossASHHeat

Loss

Elet. Energy

Loss


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Different Cycles in Gas Turbine & Steam Turbine

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