APP OFWG capacity building course, Thurs/Friday 5/6 February, 2009Korean Electrical Power Research Institute (KEPRI), Daejeon, Korea
Professor Terry Wall and Dr Jianglong Yu
University of Newcastle, Australia
Lecture 1b: Fluidised-Bed Oxyfuel Combustion
Boiler or Gas Turbine
Ash removal / cooler /
condenser / FGD
Steam Turbine
Purification / compression
Steam
Oxygen
Fuel
Power
CO2 (SO2)
CO2 –rich Flue Gas
Air Separation unit (ASU)
Air
Recycled Flue Gas (RFG)
Nitrogen
Conc. Stream of CO2
Vent
Oxy- fuel flowsheet for first generation technology, showing additional units for a retrofit in red
Oxy- fuel flowsheet for CFB
(Nsakala, Liljedahl et al. 2007)
Oxy- fuel flowsheet for CFB
Nsakala, Liljedah et al. 2006
Oxy- fuel flowsheet for CFB
(Nsakala, Liljedahl et al. 2007)
Oxy- fuel flowsheet for CFB
(Nsakala, Liljedahl et al. 2007)
ASUCO2 handling
Purification; compression; transportation; storageReplacement of nitrogen with recycled CO2
Combustion environment of fuel•Fuel reactivity•Retrofit•Impurity formation and emission
Impurity impact on CO2 handling
Common Issues with Oxy-Combustion for CCS
Replacement of nitrogen with recycled CO2
Fluidizing propertiesSOx removal (carbonation of lime)Recirculation (fluidizing and carbonation)
Specific concerns with oxy-combustion CFB
Typical Flue Gas Composition
(Nsakala, Liljedahl et al. 2007)
Carbonation of lime
(Nsakala, Liljedahl et al. 2007)
CaO+CO2 CaCO3
Plant Auxiliary Power for CFB
Gas processing system: 0.129
ASU: 0.172
Traditional Aux Power: 0.74
Net Plant Output Comparison for CFB
Net Plant Thermal Efficiency for CFB
Thermal efficiency of Oxy-combustion for CFB
(Ochs, Oryshchyn et al. 2004)
Boiler Efficiency Comparison (CFB)
CO2 Emissions per kWh (CFB)
Heat transfer: Other relevant study (CFB)
Through early modelling although CO2 has a different thermodynamic properties, under the same oxygen content, oxy-combustion heat transfer does not differ much from air combustion because oxy-combustion has a lower flame temperature;
CFD based modelling indicated that when oxygen content in the oxy-combustion increases from 21% to 29%, combustion efficiency and boiler efficiency increase. But further increase in oxygen content does not significantly improve the efficiency and 30% above oxygen causes other problems and safety concerns. The oxygen content in oxy-combustion therefore vary from 21% to 29%.
Combustion efficiency (cfb)
O2
Com
bust
ion
effic
ienc
y
O2
Boi
ler
effic
ienc
y
(Zhejiang 2003)
SO2 formation (CFB )
(CFD, Zhejiang 2003)
O2
SO2 emission Normalized SO2 emission
O2
SO2 formation (CFB )
(Timo Eriksson et al, 2008)
NOx emission (CFB )
(CFD, Zhejiang 2003)
O2
SO2 emission Normalized SO2 emission
O2
Li, H., J. Yan, et al. (2009)
Impurity impacts on the purification process in oxy-fuel combustion based CO2 capture and storage system
CRR=92.15%
Thank you for your attention!
