Prof. Dr.-Ing. B. Epple Energy Systems & Technology www.est.tu-darmstadt.de Technische Universität Darmstadt Feasibility Study on Carbonate Looping Process for Post Combustion CO 2 -Capture from Coal fired Power Plants B. Epple und J. Ströhle 4th International Workshop on In-Situ CO 2 Removal London, 7-9 July 2008
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.tu-darmstadt.de
Technische Universität Darmstadt
Feasibility Study on Carbonate Looping Process for Post Combustion CO2-Capture
from Coal fired Power Plants
B. Epple und J. Ströhle
4th International Workshop on In-Situ CO2 RemovalLondon, 7-9 July 2008
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.de
CO2 Capture from Coal-Fired Power PlantsOverview of Processes
•• FlueFlue gas gas scrubbingscrubbing (z.B. MEA (z.B. MEA scrubbingscrubbing))– Very high energy demand (Δη ~ 14%), high costs– Environmental problems (toxic absorbents)– „Post-combustion“ technology -> retrofit possible– Far developed
•• OxyfuelOxyfuel combustioncombustion– High energy demand (air separation) – Need for further development (e.g. steam generator/burner)
•• GasificationGasification technology (IGCC)technology (IGCC)– „Pre-combustion“ technology– High energy demand, high costs, complex process– Need for further development (e.g. H2 gas turbine)
•• Membrane Membrane processesprocesses (z.B. AZEP, Oxycoal)– Oxyfuel technology– Low energy demand– High need for development (e.g. materials)
Alternatives: “Oxyfuel“ Chemical LoopingChemical Looping„Post-combustion“ Carbonate LoopingCarbonate Looping
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.de
„Post Combustion“
Carbonate Looping
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deCarbonate-Looping Principle
CaO
CaCO3
CO2 to compressionDecarbonated
flue gas
Flue gas from power plant AshDeactiveted lime
Make-up CaCO3
O2
Fuel
CARBONATOR650 °C
CALCINER900 °C
• „Post-combustion“ process• Energy demand for O2 supply to calciner (~1/3 of oxyfuel)
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deCarbonate Looping: Reaktivity of CaO
• Application to continuous operation of two reactors
• Active fraction of CaO (Formula of Abanades (2005)) :
0
0
(1 )(1 )
m wcarb w
R m
f f FX fF F f
× − ×= +
+ × −
• Experiments in batch reactor withcyclic carbonisation/calcination(Abanades, 2002)
• Decrease of reactivity of CaO withnumber of cycles
• Reactivity converges againstconstant values of approx. 15 %
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deProcess Scheme for Retrofit
Cold end of reference power plant 1052 MWel
CaO/CaCO
Q3
Carbonator
650 °CCalciner
CO reduced2
flue gas
CO compression2
CaCO
3
O2
CaCO3
CaO
FanFGD
Coal
Q2 Q4
Q1
900 °C
Preheater3
3
ASU
Source: Romeo et al.Mod. by EST TU Darmstadt
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deReference Power Plant 1052 MWel
Hard coalFuel45,6% (net)Efficiency1052MWel (net)2308MWthPower
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deASPEN Model: Carbonate Looping
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deASPEN-Modell: Assumptions
• Flue gas from reference plant after FGD
• Aim: 80 % CO2 capture in carbonator
• Pressure increase by fan before carbonator: 200 mbar
• 99 % SO2 capture in carbonator und calciner
• Coal burn-out in calciner: 99,5 %
• Oxygen excess in calciner: λ = 1,1
• O2 purity after ASU: 95 %
• Energy demand for ASU: 185 kWh/t O2 (Source: IVD Stuttgart)
• Cooling of flue gases in steam generator down to 330 °C; below coolingfor internal pre-heating down to ~100 °C
• Water/steam process according to reference plant
• 100 % CO2 capture in calciner
• CO2 compression treated separately (considered later)
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deASPEN Results: Mass Flows
0
1000
2000
3000
4000
5000
6000
7000
8000
0 25 50 75 100 125 150 175Makeup [t/h]
Zirk
ulie
rend
er M
asse
nstr
om [t
/h]
0
50
100
150
200
250
Koh
lest
rom
[t/h
]
zirkulierender Massenstrom [t/h]
Kohlestrom [t/h]
High Makeup rate (at constant CO2 capture rate in carbonator of 80 %):→ High Active fraction of CaO → low circulating mass flow required→ Low energy demand in calciner for heating CaCO3 from 650 to 900 °C
Circ
ulat
ing
mas
sflo
w[t/
h]
Coa
lmas
sflo
w[t/
h]
Circulating mass flow [t/h]
Coal mass flow [t/h]
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deASPEN Results: Efficiency
High Makeup rate (at constant CO2 capture rate in carbonator of 80 %):→ Lower energy demand for heating solids, but higher energy demand for first
calcination of fresh limestone→ Less CO2 from coal in calciner (i.e. captured by 100 %)
-4,0
-3,5
-3,0
-2,5
-2,0
0 25 50 75 100 125 150 175Makeup [t/h]
Wirk
ungs
grad
einb
uße
[%-P
unkt
e]
80
85
90
95
100
CO
2-Ef
fizie
nz [%
]
WirkungsgradeinbußeCO2-Effizienz
( ), ,
el, KW el, CL
Kohle KW Kohle CL u
P P m m H
η +=
+
,2
, , ,
22 2 2
CL outCO
KW RG CL fuel CL makeup
COX
CO CO CO=
+ +
* without CO2compression
*
Plan
t effi
cien
cydr
op [%
poi
nts]
CO
2ef
ficie
ncy
[%]
Plant efficiency drop [% points]CO2 efficiency [%]
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deHeat Balance of Steam Generator
Boundary conditions:
Steam parameters as in referenceplant:
SH: 600 °C, 285 bar
RH: 620 °C, 59 bar
ΔT > 23 K
Feed wate before ECO: 307 °C
Cooling of flue gas down to 330 °C
Results (APROS):
Live steam: 476,6 kg/s
El. gross power: 636,2 MW (as in ASPEN results)Calciner Carbonator
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deALSTOM CFB Boiler > 200 MWel
Customer Power plant Country Gross
[MWel]
Year of commis- sioning
Fuel
China Guodian Corp. Xialongtan China 300 2007 Bituminous coal China Guodian Corp. Xialongtan China 300 2007 Bituminous coal Qinhuangdao Power Qinhuangdao #6 China 300 2007 Brown coal Qinhuangdao Power Qinhuangdao #5 China 300 2007 Brown coal Yunnan Datang Honghe Kaiyuan 1 China 300 2006 Anthracite Yunnan Datang Honghe Kaiyuan 2 China 300 2006 Bituminous coal Sichuan Baima Power Baima China 300 2005 Bituminous coal East Kentucky Power Gilbert/Spurlock USA 268 2004 Bituminous coal ENEL Sulcis Italy 340 2004 Bituminous coal Reliant Seward #2 USA 290 2004 Waste coal Reliant Seward #1 USA 290 2004 Waste coal AES Puerto Rico Guayama 1 Puerto Rico 250 2002 Bituminous coal AES Puerto Rico Guayama 2 Puerto Rico 250 2002 Bituminous coal Choctaw Generation Red Hills 1 USA 250 2001 Brown coal Choctaw Generation Red Hills 2 USA 250 2001 Brown coal AES Warrior Run Warrior Run USA 208 2000 Bituminous coal Korea Electric Power Tonghae 1 South Korea 220 1998 Anthracite Korea Electric Power Tonghae 2 South Korea 220 1998 Anthracite EdF/Soprolif Provence IV France 250 1995 Lignite
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.de
Largest CFB Boiler
293 m2
Quelle: Foster Wheeler
Lagisza/PL 460 MWe CFB , Commissioning 2008
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deConclusions
Chemical Looping:
•potentially lowest efficiency drop (< 1 % without CO2 compression)
•restricted suitability for retrofit of existing power plants (CFB)
•promising option for new power plants with CO2 capture
Carbonate Looping:
•efficiency drop (less than 3 % * ) mainly due to supply of O2, but significantly lower than oxyfuel combustion or MEA scrubbing
*plus CO2 compression = in total 6 % efficiency drop
•well suited for retrofit of existing power plants (repowering)
For further investigation regarding in 1 MWth scale at TU Darmstadt
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.de
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Combustion chamber for exhaust gas generation
bottom ash
Ash
container
fabric filter
combustion chamber
blower
flue gases
Main items for modifications- ignition device- chamber (combustion volume)- bottom ash separation- fly-ashes (blower, filter)
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.de
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CFB600Thermal duty up to 1MW
height 10 m
Pressure 200mbar
External diameter 1,3 m
Internal diameter 0,6 m
Baghouse working T 140-180 °C
Carbonator
CFB600 as Carbonator
• primary air and flue gas source
• connection with the calciner
• dust separation and extraction
Venturi scrubber
Carbonator
Baghouse filterHeat exchanger
By-pass
Start-up
burner
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.de
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Calciner (or Gasifier)ACFBG
Thermal duty 1500 kW
Flue gas T 700 - 1000 °C
height 10,5 m
External diameter 1000 mm
Internal diameter 400 mm
Baghouse working T 300-400 °C
Reactor pressure0-100MBAR
(G)
ACFBG as Calciner- pipe connections- gasification mode
Flue gases
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CO
2-Ab
sche
idun
g in
koh
lebe
feue
rten
Kraf
twer
ken
mitt
els
Kalk
stei
n
Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deAnsichten 3D-Modell
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CO
2-Ab
sche
idun
g in
koh
lebe
feue
rten
Kraf
twer
ken
mitt
els
Kalk
stei
n
Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deAnsichten 3D-Modell
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.deAcknowledgements
• The financial support by the German Ministry of Economics and Technology (BMWi) und the Utility Companies (EON; EnBW; Evonik; RWE)
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.de
„OXYFUEL“
Chemical Looping
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Prof. Dr.-Ing. B. EppleEnergy Systems & Technologywww.est.TU-Darmstadt.de
Chemical-Looping Principle
(1)Air reactor
2 MexOy-1 + O2 2 MexOy
(2) Fuel reactor
MexOy + Fuel MexOy-1 + CO2 + H2O
AIR
MexOy
CO2 H2ON2
Fuel
MexOy-1
(1)Air
reactor
(2)Fuel
reactor
• „Oxyfuel process“• No energy demand for separation of N2/O2
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