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Effect of Reheating and Feed Water Heating on Steam Generation
P M V SubbaraoProfessor
Mechanical Engineering Department
Good to Turbine and Cycle…..What about Steam Generator ???
Effect of Reheat Pressure
prh/pmax
0.2 0.4 0.6 0.8 1.0
~0.3
Selection of Optimal Reheat Point
Reheat Supercritical Rankine Cycle
1
2
2s
3
4
5
6
Reheating : A Means to implement High Live Steam Pressure
Impr
ovem
ent i
n E
ffic
ienc
y, % 593/6210C
593/5930C565/5930C
565/5650C
538/5650C
538/5380C
Supercritical
Single-Reheat Ultrasupercritical Product LineGE Power
Super Critical Cycle ~ 1990
Double Reheat Ultra Super Critical Cycle
8
Reheater Pressure Optimization forDouble Reheat Units
Impr
ovem
ent i
n E
ffic
ienc
y, %
Scope for Double Reheat in Ultra CriticalCycles
5380C
6100C
6100C
5380C
P,bar 350150
Super Critical Cycle of Year 2005
Double Reheat Super Critical Plants
Net efficiency on natural gas is expected to reach 49%. Net efficiency on coal is expected to reach 47%.
Super Critical Cycle of year 2010
> 50 %
Double-Reheat Ultrasupercritical Product LineGE Power
Ultra Supercritical Installations of The World
C
C
CC
Reassessment Thru Carnot Model
s
Non-Isentropic Expansion !!!
A Macro Carnot Cycle !!!!
Ideal Regenerative Cycle
Regenerative Turbine
Regenerative heat transfer. Change in kinetic and potential energies are negligible
3
4
T
inin mmCMSSSF ::
CVout
outin
inCV WgzVhmgzVhmQ
22
CVoutoutininREGEN WhmhmQ
ssuming a single fluid entering and leaving…
2374 hhmhhmhhmQW outinREGENCV
REGENQ
Analysis of Regeneration Cycle
s
12
2374
17
34
hhmW
hhhhmW
hhmQ
hhmQ
pump
turbine
out
in
additionHeat of Rate
outputPower Net cycle theof Efficiency
34
17
34
1734 1hh
hh
hhm
hhhhm
in
net
Q
W
smS