Upload
ngocong
View
234
Download
8
Embed Size (px)
Citation preview
Analysis of Rankine Cycle with FWHs
P M V SubbaraoProfessor
Mechanical Engineering Department
I I T DelhiEngineering solution to Pure Thoughts ..…..
Regeneration Cycle with Open FWH
’
212111 smSsmS
mixmix smSS 23
515414 smmSsmmS mixmix
556 smSS mix
S
5smmix
1m
Synthesis of Rankine Cycle with OFWH
5
p2=p6
Analysis of OFWH
h3
h6y
h2
1-y
Conservation of energy:
326 1 hhyhy 2326 hhhhy
26
23
hhhhy
Analysis of Regeneration through OFWH
26
23
hhhhy
45 hhmQ in
171 hhymQOut
pumpscondbleednet WWWW
3412 & hhhh 0
pumpsW
7565 1 hhyhhymWWW condbleednet
45
7565 1hhm
hhyhhymin
net
Q
W
35
7565 1hh
hhyhhy
35
75
35
65 1hh
hhyhhhhy
16
13
26
23
hhhh
hhhhy
Performance of FWH Cycle
0.45
0.455
0.46
0.465
0.47
0.475
0.48
0.485
0.49
0 5 10 15 20
pregen, MPa
total
~ 12MPa
wbl
eed
020406080
100120140160180200
0 5 10 15 20
65 hhy
Workoutput of bleed Steam
pregen, MPa
~ 12MPa
0
200
400
600
800
1000
1200
1400
1600
0 0.1 0.2 0.3 0.4 0.5
wbl
eed
Workoutput of bleed Steam
0
200
400
600
800
1000
1200
1400
1600
0 0.1 0.2 0.3 0.4 0.5
wbl
eed
Workoutput of bleed Steam
Progress in Rankine CycleYear 1907 1919 1938 1950 1958 1959 1966 1973 1975
MW 5 20 30 60 120 200 500 660 1300
p,MPa 1.3 1.4 4.1 6.2 10.3 16.2 15.9 15.9 24.1
Th oC 260 316 454 482 538 566 566 565 538
Tr oC -- -- -- -- 538 538 566 565 538
FHW -- 2 3 4 6 6 7 8 8
Pc,kPa 13.5 5.1 4.5 3.4 3.7 3.7 4.4 5.4 5.1
,% -- ~17 27.6 30.5 35.6 37.5 39.8 39.5 40
Open (Direct Contact) Feed Water Heater
Closed Feed Water Heater (Pumped Condensate)
Closed Feed Water Heater (Throttled Condensate)
Closed Feed Water Heater (Expanded Condensate)
Thermodynamic Analysis of A Power Plant
ANALYSIS OF ‘ith’ FEED WATER HEATER
• Mass entering the turbine is
STEAM TURBINE
n
iiSGcond ymm
1
1
yn,
hbn
yi,
hbi
y(i+1)
hb(i+1)
mie ,
hfi
mi,i,
hf(i+1)
STEAM IN
STEAM OUT
SGmSGm
Mass of steam leaving the turbine is
RESULTS
S.NO Pmax Tmax Tmin PminMpa oC oC Mpa ΔH = constant ΔT = constant Simulated
1 12.75 535 25.7 0.0033 43.4 47.6 50.642 23.5 540 26 0.0034 30.8 36.97 53.543 12.74 565 23.97 0.00298 44.39 46.72 51.24 15 550 40 0.0074 46.73 50.285 53.995 16.5 535 40 0.01 38.8 43.08 49.022
GENERATIONS = 5000 /// NO OF FEED HEATERS = 6 Thermal Efficiency
RESULTS
S.NO Pmax Tmax Tmin Pmin W bledsteam Popt
1 12.75 535 25.7 0.0033 234.2 7.28 , 4.88 , 3.42 , 3.09 , 1.326 , 0.2762 23.5 540 26 0.0034 302.093 12.74 565 23.97 0.00298 242.164 15 550 40 0.0074 270.35 16.5 535 40 0.01 249.589 5.293, 2.33, 1.096, 0.779, 0.651, 0.0674
7.28 , 4.88 , 3.42 , 3.09 , 1.326 , 0.276
5.3 , 2.23 , 1.096 , 0.779 , 0.651 , 0.06748.28, 4.88, 3.7792, 2.0907, 0.48, 0.2597
RESULTS
S.NO H2 Pmax Tmax Tmin Pmin THERMAL EFFICIENCYSimulated
1 1465 16.75 535 25.7 0.0033 49.192 1500 16.75 535 25.7 0.0033 49.0223 1550 16.75 535 25.7 0.0033 49.0224 1600 16.75 535 25.7 0.0033 49.022
NO OF FEED HEATERS = 6
Condenser
Block Diagram of A Large Steam Turbine Reheat Steam
HP
Main Steam
Steam for Reheating
IP
LPLP
CFWH 6 CFWH 5
OFWH 4
CFWH 2
CFWH 1
CFWH 3
Plow
Phigh
Regeneration cycle
Reheat-Regeneration cycle
Improvement in efficiency due to reheating in a reheat-regeneration cycle
Heater Selection and Final FeedwaterTemperature
• In order to maximize the heat rate gain possible with ultra-supercritical steam conditions, the feedwater heater arrangement also needs to be optimized.
• In general, the selection of higher steam conditions will result in additional feedwater heaters and a economically optimal higher final feedwater temperature.
• In many cases the selection of a heater above the reheat point (HARP) will also be warranted.
• The use of a separate desuperheater ahead of the top heater for units with a HARP can result in additional gains in unit performance.
Typical Single Reheat Heater Cycle with HARP
Effect of Final Feedwater Temperature and Reheat Pressure on Turbine Net Heat Rate
Double Reheat Cycle with Heater above Reheat Point
Double Reheat Super Critical Plants
Net efficiency on natural gas is expected to reach 49%. Net efficiency on coal is expected to reach 47%.
Advanced 700 8C Pulverised Coal-fired Power Plant Project