Evaluation of Post-Combustion CO 2 -Capture using Piperazine- Promoted Potassium Carbonate Alfons Kather Jochen Oexmann Institute of Energy Systems Prof. Dr.-Ing. A. Kather Promoted Potassium Carbonate in a Coal Fired Power Station 11 th Workshop of the Post-Combustion CO 2 -Capture Network Vienna, 21 st May 2008
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Evaluation of Post-Combustion Alfons Kather Jochen Oexmann ... Mtg/01-03 -- J... · • Chemical absorption of CO 2 with K 2CO 3/PZ described by reaction scheme:-2 2 - - 3-2 - - 3
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Evaluation of Post-Combustion
CO2-Capture using Piperazine-
Promoted Potassium Carbonate
Alfons Kather
Jochen Oexmann
Institute of Energy Systems
Prof. Dr.-Ing. A. Kather
Promoted Potassium Carbonate
in a Coal Fired Power Station
11th Workshop of the Post-Combustion CO2-Capture NetworkVienna, 21st May 2008
Agenda
• CO2-Capture with K2CO3/PZ
▸ Thermodynamic model
▸ Boundary conditions
• CO2-Compression
• Power Plant Integration
• Results
11th Workshop of the InternationalNetwork for CO2 Capture, May 2008, Vienna
• Results
▸ Specific reboiler heat duty
▸ Specific power loss of overall integrated process
• Column Design
▸ Absorber and desorber sizes
• Comparison to MEA
• Summary and Outlook
2
K2CO3 / PZ as an Alternative Solvent for PCC
• CO2-capture process with MEA is considered the reference in post-
combustion CO2-capture, as
▸ Experience from commercial processes exist
▸ Drawbacks: corrosivity, degradation and large regeneration heat duty
• Potassium Carbonate (K2CO3)
▸ Cheap
▸
11th Workshop of the InternationalNetwork for CO2 Capture, May 2008, Vienna
▸ Non-volatile
▸ Non-toxic
▸ But: low rate of absorption at atmospheric pressure
• Promotion with Piperazine (PZ)
▸ Two amine functional groups ⇨ large capacity + high rate of absorption
▸ Less sensitive towards O2, SOx and NOx than MEA
3►Introduction
Thermodynamics
• Chemical absorption of CO2 with K2CO3/PZ described by reaction scheme:
-
22
--
3
-
2
--
3
32
-2
332
-
3
-
3322
-
32
PZH PZCOOPZ HPZCOO
OH )PZ(COOHCO PZCOO
OH PZCOOHCO PZ
OH PZOH PZH
CO OHOH HCO
HCO OHOH 2 CO
OH OHOH 2
+→←+
+→←+
+→←+
+→←+
+→←+
+→←+
+→←
+
++
+
+
+
rate of
absorption
11th Workshop of the InternationalNetwork for CO2 Capture, May 2008, Vienna
• Carbamate reactions dominant for overall absorption rate
• Electrolyte Non Randomness Two Liquid Model (eNRTL) in ASPEN Plus
• eNRTL parameters regressed by Hilliard (2007)
4
-
33
2
332
HCO K KHCO
CO K 2 COK
+→
+→+
−+
►CO2-capture
Interfaces to Power Plant
from FGD to atmosphere
to storage
desorberAbsorber
intercooled compression
cooling dutyheat duty power duty
preheater
11th Workshop of the InternationalNetwork for CO2 Capture, May 2008, Vienna 5
steam/condensate from/to
power plant
HX
desorberAbsorber
blower
rich solvent pump
reboiler
flue gas cooler
to water conditioning
lean solvent pump
►CO2-capture
Boundary Conditions
• Flue gas mass flow 577 kg / s
• Flue gas temperature from FGD 47 °C
• Flue gas temperature at absorber inlet 62 °C
• Flue gas CO2 concentration 14.2 vol% (wet)
15.9 vol% (dry)
• Absorber solvent inlet temperature 40 °C
11th Workshop of the InternationalNetwork for CO2 Capture, May 2008, Vienna 6
• Lean-rich heat exchanger LMTD 5 K
• Reboiler temperature difference 10 K
• CO2 condition at compressor outlet 40 °C / 110 bara
• Analysed solvents 2.5 m K2CO3 / 2.5 m PZ (S2.5,2.5)
3.2 m K2CO3 / 1.6 m PZ (S3.2,1.6)
4.8 m K2CO3 / 0.6 m PZ (S4.8,0.6)
3.0 m K2CO3 (S3.0)
• Lean Loading varied for minimisation of reboiler duty
►CO2-capture
CO2-Compression
• Simulation tool: ASPEN Plus
• Technical data
▸ 2 parallel trains of similar geartype compressors with 5 radial stages (ηi= 0,84....0,87)