Design of SOFC based oxyfuel combustion systems with anode recycling and steam recycling options

A solid oxide fuel cell (SOFC) based power plant incorporating an oxyfuel combustion process to reduce carbon dioxide emissions is analyzed. The effects of key parameters, such as the steam-to-carbon ratio, fuel utilization factor, and temperature, on the current density, voltage, heat production, and requirements of each unit are investigated. In addition, the overall performance of the SOFC-oxyfuel integrated systems with anode recycling and steam recycling are studied and compared. The SOFC system with anode recycling provides better electrical efficiency than that with steam recycling because of the high utilization of fuel in the SOFC and the ability to integrate a fuel turbine. In the SOFC with steam recycling, a fuel turbine cannot be implemented because there is insufficient heat for preheating the inlet streams, which is primarily used to vaporize the recycling stream. The conditions for SOFC-oxyfuel combustion in systems with anode or steam recycling that provide the optimum electrical efficiency are also analyzed.