Conception of a Pulverized Coal Fired Power Plant with Carbon Capture around a Supercritical Carbon Dioxide Brayton Cycle

AbstractPower generation efficiency penalty is the main concern about carbon capture technologies. Improvement of power plant efficiency due to higher steam condition is frequently foreseen to outbalance the carbon capture penalty. This work focuses on the conceptual design of two coal-fired power plants using CO2 as working fluid: one with post- combustion MEA-based CO2 capture and one with oxy-combustion CO2 capture with cryogenic air separation. Two maximal supercritical CO2 temperatures are investigated (620 and 700°C). The combination of a Brayton supercritical CO2 power cycle, a coal boiler and a capture process allows significant increase of the overall plant efficiency. Both post-combustion and oxy-combustion capture processes lead to a very high overall plant efficiency: approximately 41.5% for a 620°C power cycle and 44.5% for a 700°C power cycle. Oxy-combustion seems best fitted for supercritical CO2 Brayton cycle due to a simpler thermal integration and the CO2 purification devices already integrated in the CO2 processing unit. Main resulting technological challenges are the very large heat exchanger needed in the CO2 cycle in order to achieve high power cycle efficiency and the development of supercritical CO2 turbine significantly different than steam or gas turbine especially because of the very large effort on wheel and the small size of the equipment. Numerous technological developments on process component will be necessary and a representative CO2 cycle pilot plant will be needed to assess CO2 leakage, corrosion and flexibility issues