以煤层气为燃料的固体氧化物燃料电池发电系统的模拟与分析

Simulation and Analysis of the Coal Seam Methane Fueled Solid Oxide Fuel Cell Power Generation System

固体氧化物燃料电池(solid oxide fuel cell,SOFC)发电具有效率高、噪声低、排放低的优点。为评估煤层气SOFC发电系统性能,并与现有燃气内燃机发电技术进行对比,在AspenPlus模拟环境中构建了SOFC发电系统流程,研究30%和91%煤层气浓度下水碳比、电流密度、空气预热温度等参数对系统性能的影响,并与燃气内燃机发电进行技术经济性比较。结果表明,使用30%浓度煤层气时,SOFC发电效率为38.7%,略低于燃气内燃机发电效率,年CO2排放量与燃气内燃机接近;使用91%浓度煤层气时,SOFC发电效率为53.2%,高出燃气内燃机13.4%,年燃料成本降低24%,年CO2排放量相比燃气内燃机降低23%;受大量冷却空气的影响,SOFC的NOx排放是燃气内燃机的2倍。由结果可知,当煤层气浓度在30%以上时,SOFC相比燃气内燃机才具有效率优势;煤层气浓度越高,SOFC的效率优势越明显;当煤层气浓度低于30%时,建议仍使用燃气内燃机进行发电。

The solid oxide fuel cell(SOFC) possesses the advantages of high efficiency, low noise and low emissions. To evaluate the performance of SOFC when fueled by coal seam methane, and compare SOFC with internal combustion engine(ICE), the SOFC power generation system model was built, simulated and analyzed in Aspen Plus. Key system parameters, such as steam to carbon ratio, current density and air preheat temperature, were studied to gain information of their effects on the system performance, for CSM of both 30% and 91% concentration. The technical economy of SOFC and ICE was compared. For CSM of 30% concentration, the efficiency of SOFC is 38.7%, which is slightly lower than that of ICE, the annual CO2 emission is close to that of ICE. For CSM of 91% concentration, the efficiency of SOFC is 53.2%, which is higher than that of ICE by 13.4%, the annual fuel cost is reduced by 24%, the annual CO2 emission is reduced by 23%. Due to the cooling demand of the SOFC stack by large amount of fresh air, the NOx emission of SOFC is twice as that of ICE. The SOFC tends to gain efficiency advantage over ICE for CSM concentration higher than 30% and the efficiency advantage tends to enlarge when the CSM concentration is higher. While for CSM with concentration lower than 30%, the ICE is recommended for power generation.