COMPARATIVE PERFORMANCE ANALYSIS OF INTERNAL AND EXTERNAL REFORMING OF METHANOL IN SOFC-MGT HYBRID POWER PLANTS

摘要

SOFC-MGT hybrid power plants are a very attractive near term option, as they achieve efficiencies of over 60% even for small power outputs (200-400 kW). The SOFC hybrid systems currently developed are fuelled with natural gas, which is reformed inside the same stack at about 800-900 °C. However, the use of alternative fuels with a lower reforming temperature can lead to enhanced performance of the hybrid power plant. This paper reports a comparative performance analysis of SOFC-MGT power plants fuelled by methane and methanol. Since the reforming temperature of methanol (250-300 °C) is significantly lower than that of methane (700-900 °C), for the methanol fuelled plant both internal and external reforming have been examined. The performance analysis has been carried out by considering different values for the most important operating parameters of the fuel cell. The comparative analysis has demonstrated that simply replacing methane with methanol in SOFC-MGT power plants with internal reforming slightly reduces the efficiency. However, the use of methanol in SOFC-MGT power plants with external reforming enhances efficiency significantly (by about 4 percentage points). The use of methanol with external fuel reforming raises efficiency of the stack thanks to the improved heat management and to the higher hydrogen partial pressure at the anode inlet.