Thermodynamic and economic performance study of SOFC combined cycle system using biomass and LNG coupled with CO2 recovery

Abstract

The search for more efficient, energy-saving and cleaner methods of energy utilization is a current research focus. In this study, a novel solid oxide fuel cell (SOFC) combined cycle system fueled by biomass syngas and natural gas is studied, with carbon capture by using liquefied natural gas (LNG) cold energy. In the proposed system, the exhaust from the cathode and anode outlets of SOFC is split to do work instead of the traditional approach of exhaust mixing, thus achieving CO2 capture using LNG cold energy more efficiently. The system is simulated by Aspen Plus software with embedded Fortran. The energy analysis and exergy analysis of the system are performed. The results indicate that under design conditions, the thermal efficiency, electrical efficiency and exergy efficiency of the system are 60.28 %, 66.20 % and 55.59 %, respectively. The amount of carbon capture purity and the mass flow rate of liquid CO2 are 99.35 % and 54.50 kg/h. The largest exergy loss occurs in heat exchangers, which accounts for 35.63 %. In addition, sensitivity analysis of the system is performed and the variation law of thermodynamic and economic performance with parameters is obtained based on the simulation results. This study not only provides a theoretical basis for subsequent research on the way to improve the efficiency of SOFC combined cycle system, but also provides new ideas for the efficient utilization of biomass combined with natural gas.