Steam power plant

Steam Power Plant: Energy conversion in a thermal power station.
Limitations on conversion of heat into work, direct conversion
devices, central power station, industrial power station, captive
power station, advantages. Classification of power station on the
basis of prime-movers.
Elements of steam power plant, function of each element- generating
unit, prime mover, auxiliary equipment and turbo generator.
Revision & Improvement of thermal efficiency of Rankine cycle by
lowering exhaust pressure, increasing boiler pressure and
superheating of steam. Simple problems on Rankine efficiency.
Reheat cycle: Representation on T-S and H-S planes, flow diagram
and advantages. Simple regenerative cycle: flow diagram,
representation on T-S and H-S planes, bleeding and feed water
heating and pumping.

1. STEAM POWER PLANT
Mohit Singhal, Lecturer, GPC Shajapur

2. RATIONALE
•The power demand in the country is increasing at a very fast
pace. In fact, power production is not able to keep pace with the
demand.
•More and more steam power plants are coming up in the public
sector.
•Nuclear Power plants and gas turbine power plants are also
being set up.
•Also industries in public and private sectors are being permitted
to establish their own captive steam and diesel power plants.
•This course is aimed at providing knowledge about the systems
of power generation, and the principles of the equipments.
Mohit Singhal, Lecturer, GPC Shajapur

3. POWER PLANT
STATION
ULTIMATE AIM OF POWER PLANT
Energy ( Heat / Nuclear/
Hydro / Wind ) Electrical Energy
Mohit Singhal, Lecturer, GPC Shajapur

4. Classification of Power Plant
Power plants using Non-conventional
(renewable) sources of energy
•Solar thermal power plant
•Wind powered generation (Aero Generation)
•Tidal power plant
•Geothermal power plant
•Bio-mass power plant
•Ocean thermal power plant
•Hydro-Electric power plant
Power plants using conventional
(non-renewable) sources of energy
•Steam power plant
•Nuclear (Atomic) power plant
•Diesel power plant
•Gas power plant
Mohit Singhal, Lecturer, GPC Shajapur

5. THERMAL
PLANT
STATION
ULTIMATE AIM OF THERMAL POWER PLANT
Heat Energy Electrical Energy
Mohit Singhal, Lecturer, GPC Shajapur

6. INTRODUCTION
•AThermal(Steam)PowerPlantconvertstheheatenergyof
coalintoElectricalEnergy.Coalisburntinaboilerwhich
convertswaterintosteam.Theexpansionofsteamin
turbineproducesMechanicalPowerwhichdrivesthe
alternatorcoupledtotheturbine.ThermalPowerPlants
contributemaximumtothegenerationofPowerforany
country.
•ThermalPowerPlantsconstitute66.2%ofthetotalinstalled
captiveandnon-captivepowergenerationinIndia.
•Inthermalgeneratingstations,coal,oil&naturalgasetc.are
employedasprimarysourcesofenergy.
Mohit Singhal, Lecturer, GPC Shajapur

7. General Layout Of Thermal Power Plant
Mohit Singhal, Lecturer, GPC Shajapur

8. Main and Auxiliary Equipments
•Pulverizing plant
•Coal handling plant
•Draft fans
•Boiler
•Ash handling plant
•Turbine
•Condenser
•Cooling towers and ponds
•Feed water Pump
•Economizer
•Superheated and Reheated
•Air preheated
Mohit Singhal, Lecturer, GPC Shajapur

9. BOILER
Air
Fuel Boiler
DryerAir compressorAtmospheric Air
1.WatertubeBoilerAboilerinwhichwatercirculatesintubesheatedexternallybythefire.
2.FiretubeBoilerWaterispresentinthedruminsidetheboilerandHotairiscirculatedaround
maintainthetemperature.
Feed Water
(High Pressure & Low
Temperature ) Approx. 170 bar
Super Saturated
Steam ( High Pr.
& High Temp. )
Approx. 170 bar
& 550
Process in the Boiler
:-Heat Addition at
Constant Pressure
Mohit Singhal, Lecturer, GPC Shajapur

10. TURBINE
In a Thermal Power Plant generally 3 turbines are used to increase the efficiency.
•High Pressure Turbine(HPT): The superheated steam is directly fed to this turbine to rotate it.
•Intermediate Pressure Turbine(IPT): The out put from the HPT is reheated in a reheated(RH) and
used to rotate IPT .
•Low Pressure Turbine(LPT): The Exhausted steam from the IPT is directly fed to rotate the shaft of
LPT.
Condenser
HPT IPT LPT
RH
Super Heated Steam
Super
Heater
Generator
Steam
Shaft
Process in Steam Turbine :
Reversible Adiabatic
Expansion / Isentropic
Mohit Singhal, Lecturer, GPC Shajapur

11. CONDENSER
•Steam after rotating
steam turbine comes
to condenser.
Condenser refers
here to the shell and
tube heat exchanger
(or surface
condenser) installed
at the outlet of
steam turbine.
Process in Condenser :
Heat Rejection At Constant Pressure
Mohit Singhal, Lecturer, GPC Shajapur

12. Boiler Feed Water Pump
Cross-Sectional View of PumpProcess in Feed Water Pump:
Reversible Adiabatic Compression /
Isentropic Compression
Mohit Singhal, Lecturer, GPC Shajapur

13. Simple Rankine / Simple Vapor Power Cycle
T
2
3
41
P
v
1
2
3
4
Boiler
Turbine
Compressor
(pump)
Heat exchanger
(Condenser)
1
2
3
4
Q
out
Q
in
W
out
W
in
S
Mohit Singhal, Lecturer, GPC Shajapur

14. Limitation Of Simple Rankine Cycle
1.Toavoidtransportingandcompressingtwo-phasefluid:
•Wecantrytocondenseallfluidexitingfromtheturbineinto
saturatedliquidbeforecompresseditbyapump.
1.Whenthesaturatedvaporenterstheturbine,asitstemperatureand
pressuredecreases,condensationoccurs,leadingtoliquid.Theseliquid
dropletscansignificantlydamagetheturbinebladesduetocorrosion
and/orerosion.
•Onepossiblesolution:superheatingthevapor.
•Itcanalsoincreasethethermalefficiencyofthecycle(sinceT
H).
Mohit Singhal, Lecturer, GPC Shajapur

15. Modified Rankine cycle
T
s
3
41
2
Boiler
Turbine
(pump)
Heat exchanger
(Condenser)
1
2
3
4
Q
out
Q
in
W
out
W
in
Mohit Singhal, Lecturer, GPC Shajapur

16. Ideal Rankine Cycle -Energy analysis
•Assumptions:steady flow process, No heat generation due to friction,
neglect KE and PE changes for all four devices,
•Apply First Law of Thermodynamics in each process:
(Net heat transfer ) = (Net work out) + (Net Energy flow)
 (q
out-q
in) = (W
out-W
in) + (h
out-hin)
•1-2: Pump(q=0)
W
pump = h
2 -h
1 = v(P
2-P
1)
•2-3: Boiler(W=0) q
in= h
3-h
2
•3-4: Turbine(q=0) W
out= h
3-h
4
•4-1: Condenser(W=0) q
out= h
4-h
1
Thermal efficiencyh= W
net/q
in= 1 -q
out/q
in = 1 -(h
4-h
1)/(h
3-h
2)
W
net= W
out-W
in= (h
3-h
4) -(h
2-h
1)
T
s
3
41
2
Mohit Singhal, Lecturer, GPC Shajapur

17. Thermal Efficiency –How to enhance it?
Thermal efficiency can be improved by manipulating the temperatures and/or pressures in
various components
(a) Lowering the condensing pressure (lowers T
L, but decreases quality, x
4)
(b) Superheating the steam to a higher temperature (increases T
H but requires
higher temp. materials)
(c) Increasing the boiler pressure (increases T
H but requires higher temp. & high
pressure bearable materials)
T
s
1
2
3
4
(a) lower pressure(temp)
s
T
1
2
(b) Superheating
(c) increase pressure
s
T
1
2
3
4
Low quality
high moisture content
1
2
4
Red area = increase in W net
Blue area = decrease in W net
Mohit Singhal, Lecturer, GPC Shajapur

18. Reheating
•The optimal way of increasing the boiler pressure without increasing the
moisture contentin the exiting vapor is to reheatthe vapor after it exits from
a first-stage turbine and redirect this reheated vapor into a second turbine.
boiler
high-P
turbine
Low-P
turbine
pump
condenser
1
2
3
4
5
6
T
s
1
2
3
5
6
4
high-P
turbine
low-P
turbine
4
Mohit Singhal, Lecturer, GPC Shajapur

19. Regeneration
•From 2-2’, the average temperature is very low, therefore, the heat
addition process is at a lower temperature and therefore, the thermal
efficiency is lower. Why?
•Use a regeneratorto heat the liquid (feedwater) leaving the pump before
sending it to the boiler. This increases the average temperature during
heat addition in the boiler, hence it increases efficiency.
T
s
1
2
2’
3
4
Lower temp.
heat addition
T
s
1
2
3
4
5
6
7
Use regenerator to heat up the feedwater
higher temp.
heat addition
Extract steam @ 6
From turbine to provide
heat source in the
regenerator
Mohit Singhal, Lecturer, GPC Shajapur

20. Mohit Singhal, Lecturer, GPC Shajapur

21. Mohit Singhal, Lecturer, GPC Shajapur