Advanced Power Plants Coal Fired Steam Power Plant
Transcript of Advanced Power Plants Coal Fired Steam Power Plant
Technische Universität München
Advanced Power Plants
Coal Fired Steam Power Plant
Prof. Dr.-Ing. H. Spliethoff
Lehrstuhl für Energiesysteme
Technische Universität München
Content
1. Situation today
2. Efficiency: achievements and outlook
3. Future – discussion of the energy concept
4. Flexibility of power plants
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1. Today
Requirements: today (Germany)
Today (2010): Share of renewables 16 %, Wind 26 GW, PV 17 GW
Source: Spliethoff: et. al, CIT 2011
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1. Today
Power Plant Capacity and Production (2010)
Economic and environmental motivation for an efficiency increase
13%
31%
14%
3%
3%
3%
33%
Capacity [%] Total: 168 GW
nuclear
coal
domestic gas
oil
pump storage
others*
renewables
23%
42%
14%
1%
1%
3% 16%
Production [%] Total: 621 TWh :
full load hours
(calculated)
Total:
1825 h/a (21%)
Coal
5000 h/a (58 %)
Source: Spliethoff: et. al, CIT 2011
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2. Efficiency
Possibilities to increase efficiency
• Increasing the average temperature of heat
addition
• Decreasing the average temperature of heat
removal
• Reducing losses • Design
• Operation
• Part load
• Start-up, shut-down
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2. Efficiency
Temperature of heat addition
• Live steam pressure and
temperature: 200 bar/540°C/540 °C
300 bar/ 600°C/620 °C
Δη =2,5 %
• Double RH
• Feed water preheating:
+30-40 k 0,7 %
0%
2%
4%
6%
8%
10%
12%
550 575 600 625 650 675 700
Live steam temperature =Reheat temperature [°C]
Re
lati
ve
ch
an
ge
in
eff
icie
nc
y [
%]
190 bar
250 bar300 bar350 bar
Source: Spliethoff: Power Generation from Solid Fuels, Springer 2010
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2. Efficiency
Limitations by materials
MS-Pressure
MS-Temperature
RH-Temperature
Membrane wall Pipes Headers
Source: Alstom
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2. Efficiency
Temp. heat extraction – Wet Cooling
2-8
• Reduction of condenser temperature by 10 K 1,2 %
• lowest possible condensation temperature: wet bulb or wet air temperature
• difference is caused by:
– terminal temperature difference of the condenser
– cooling range (= warm-up margin)
– approach
• Economic optimization
Kondensat-temperatur= 36 °C
Warmwasser-temperatur= 28 °C
Kaltwasser-temperatur= 20 °C
Feuchtluft-temperatur= 6,6 °C
Kondensator-grädigkeit
Kühlzonenbreite
Kühlgrenz-abstand
Trockenluft-temperatur= 8,5 °C
terminal temperature
difference of condenser
Condensate
temperature
= 36 °C
Warm water
temperature
= 34,5 °C
Cold water
temperature
= 20 °C
Wet-bulb
temperature
= 6.6 °C
cooling range
Approach
dry air
temperature
= 8.5 °C
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3. Efficiency
Losses
– Steam generator losses
– Turbine losses
– Pipe losses
– Generator losses
– Auxiliary power demand
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2. Efficiency
Steam Generator Losses
Steam Generator Losses Old Plant (1980) Modern Plant
air ratio 1,3 1,15
exhaust temperature 130 C 110 C
exhaust losses 5,3 % 3,8 %
radiation losses steam generator 0,25 % 0,3 %
losses through unused fuel
flue ash 0,2 % < 0,3 %
coarse ash 0,1 % < 0,2 %
sensible heat
flue ash 0,02 % 0,03 %
coarse ash 0,04 % 0,04 %
total 5,9 % 4,6 %
Source: Spliethoff: Power Generation from Solid Fuels, Springer 2010
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82
84
86
88
90
92
94
96
1940 1960 1980 2000 2020
Ise
ntr
op
ic t
urb
ine
eff
icie
ncy
[%
]
Year
Werte aus Diagramm
Zusatzwerte
3. Efficiency
Isentropic turbine efficiency
Billotet 1995
Add.values
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2. Efficiency
Brown coal – External Predrying
• External pre-drying leads to
efficiencies comparable to
hard coal, because
– Steam generator losses
are limited (seperated
vapors removal)
– The drying medium is used
at low temperatures
• Efficiency is higher than that of
hard coal, if the condensation
heat of vapors is used
• Improvement by 5 % is
possible
dryer flue
gas
mill coal dust and
carrier gas
superheated steam ~150°C
brown coal
condensation
heat
water
carrier gas
pre-drying at low
temperatures
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2. Efficiency
Reference power plant
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2. Efficiency
Data Hard Coal Steam Power Plants
Circuit Zolling Staudinger Rostock NRW
R&D
Thermie
R&D
Thermie
initial Operation 1985 1992 1994 Projekt Projekt Projekt
net Output [MW] 450 510 510 556 556 556
LS-pressure [bar] 247 250 262 285 350 375
LS-temperature [°C] 536 540 545 600 700 700
RH-temperature [°C] 538 560 562 620 720 720 / 720
RH-pressure [bar] 49 53 54 60 60 120 / 23,5
condensation
pressure [bar] 0,04 0,038/0,052 0,027/0,033 0,045 0,045 0,045
cooling
cooling
tower/river
cooling
tower
cooling
tower/ocean
cooling
tower
cooling
tower
cooling
tower
feed water
temperature [°C] 270 270 270 304 304 335
number of preheaters 8 7 7 8 8 8
efficiency [%] 41,3 42,7 43,8 45,9 48,7 50,1
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2. Efficiency
Average operational efficiency
0 100 200 300 400 500 600
30
32
34
36
38
40
42
44
46
48
50
> 2004
< 1990
1990 - 2004
best point <2004
full load 6000 >2004
best point 1990-2004
full load 5000 1990-2004
best point <1990
full load 5000 <1990
Eff
icie
ncy
Capacity (MWe netto))data from Theis 2005
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3. Future
Goals of the energy concept
-100
0
100
200
300
400
500
600
700
2008 2020 2030 2040 2050
ele
ctr
icity [T
Wh
]
year
import/export conventional renewable energies consumption of electricity
Source: Spliethoff et. al, CIT 2011
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3. Future
Goals Energy Concept
2008 2020 2030 2040 2050
Power generation D 637
TWh
- 8-10
%
-20-27
%
-30 -38 -45-48
Share of coal 43 % 37 % 30 % 20 % 18 %
Full load operation
hours Bit. C.
Brown C.
4500
6800
3300
6300
3400
4000
3700
3000
4800
5200
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4. Flexibility
Requirements: tomorrow (Germany)
Morgen
Tomorrow (2020)
• Installed capacity:
Wind 46 GW
PV 50 GW
• Constant consumption
Tomorrow (xxxx)
• Installed capacity:
Wind 75 GW
50 GW PV
Requirement for low minimum load
Source: Spliethoff: et. al, CIT 2011
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3. Flexibility
Change of power from Renewables 2020
0
10.000
20.000
30.000
40.000
50.000
0 6 12 18 24
ca
pa
city [M
W]
time [h]
-3.000
-1.500
0
1.500
3.000
0 6 12 18 24gra
die
nt [M
W/1
5m
in]
time [h]
Forcast of a winter
day (27.1.2010):
• 46 GW Wind
• 50 GW PV
Requirement for fast load change and start-up
Source: Spliethoff: et. al, CIT 2011
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4. Flexibility
Load change capability
Data from Lambertz, RWE
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25
load [
%]
time [min]
dry lignite technology hard coal CCP nuclear power plant
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4. Flexibility
Load range – Minimum load – Coal
• Load range 30/40 % -100 %
• Firing stability determines minimum load
– Requirement: safe operation in case of a mill failure
• Minimim load
– Pure coal firing: 35-40 % 25 %
– oil/ ng support: 25 %
• Change of once-through to circulation results in limitations
• Brown coal appr.50 %,
• Dried brown coal comparible to hard coal
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4. Flexibiliy
Load Change Capability
• Secondary Control
– Only by fuel mass flow
• Delay of the mill (Storage of the mill)
• Pressure increase of boiler (Gliding pressure)
– Big load changes > 20 % 3-6 % / min
• Limit by turbine inlet temp. 1-2 k/min
– Small load changes < 20 % 1-2 % / min
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4. Flexibility
Start-up, Shut-down
Old Coal
Plant
New
Coal
Plant
CC new
Hot start up (8h) 2 h 1-2 h 0,5-1 h
Warm start-up (48 h) 4-5 h 3 h 1-1,5 h
Cold start-up (72 h) 4 h 2-3 h
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Conclusions for coal fired power plants
- Substantial efficiency increase in the past
- Flexibility requirements
- Minimum load and load change capability comparable to CC
- Start-up slower
- Full load operation hours of coal fired pp will decrease
Economic conflict: efficiency
- Coal: Gasification concepts become more attractive
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Thank You
for Your Attention