Study on Zero CO2 Emission Atmospheric Pressure SOFC Hybrid Power System Integrated With OTM

Abstract

Based on a benchmark SOFC hybrid power system without CO2 capture, a zero CO2 emission atmospheric pressure SOFC hybrid power system integrated with oxygen ion transport membrane (OTM) is proposed. The oxygen is produced by the OTM for the oxy-fuel combustion afterburner, and the anode outlet gas of the SOFC is injected into the afterburner and then burns with the oxygen from OTM. So the combustion products of the afterburner are only composed of CO2 and H2O, CO2 in the flue gas can be separated and captured by a simple condensation method. After the recovery of heat and work by the heat recovery steam generator (HRSG) and steam turbine, part of the outlet flue gas from the HRSG is injected into the afterburner to reduce the outlet flue gas temperature of the afterburner to about 1100°C, 200°C higher than the operating temperature of OTM. The rest exits the system and CO2 is captured. The fuel utilization factor of SOFC and the pressure ratio (π) between two sides of OTM membrane as the key factors which greatly influence the overall system performance are analyzed and optimized. The research results show that the efficiency of the zero CO2 emission atmospheric pressure SOFC hybrid power system integrated with OTM is around 58.36%, only 2.48% lower than that of the benchmark system (60.84%) but 0.96% higher than that of the zero CO2 emission atmospheric pressure SOFC hybrid system integrated with the cryogenic air separation unit. The research achievements from this paper will help for further study on zero CO2 emissions SOFC hybrid power system with higher efficiency.