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
Avanta Power
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Energy Conversion Efficiency
Heat Input
100% 39% 61%
HeatRejected
ElectricalEnergy
Vatsala Sharma,Dy Director Avanta Power
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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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
Vatsala Sharma,DyDirector
Avanta Power
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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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
Vatsala Sharma,DyDirector
Avanta Power
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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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
Vatsala Sharma,DyDirector
Avanta Power
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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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
Vatsala Sharma,DyDirector
Avanta Power
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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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
Avanta Power
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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
Vatsala Sharma,DyDirector
Avanta Power
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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Carnot(ideal) engine:
% Efficiency = % Carnot= (QinputQout)/Qinput
since Qinput/Qout= Thot/Tcoldthe efficiency
can be written as
Vatsala Sharma,DyDirector
Avanta Power
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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Vatsala Sharma,DyDirector
Avanta Power
Simplified Diagram
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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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
Vatsala Sharma,DyDirector
Avanta Power
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Modified Rankine Cycle
Vatsala Sharma,DyDirector
Avanta Power
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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Vatsala Sharma,DyDirector
Avanta Power
8/13/2019 Different Cycles in Gas Turbine & Steam Turbine
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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.
Vatsala Sharma,DyDirector
Avanta Power
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THERMAL PROCESS LOSSES
Vatsala Sharma,DyDirector
Avanta Power
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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
Vatsala Sharma,DyDirector
Avanta Power
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