B131 ガスタービン・固体酸化物形燃料電池ハイブリッドシステムの作動特性に対する燃料組成の影響(分散エネルギーシステムにおける要素技術とその集積化3)

Abstract

Solid oxide fuel cells (SOFC) are expected to become highly efficient power generation devices in distributed energy systems. The fuel flexibility of SOFC is appropriate for the small-scale power generation driven with the fuel derived from biomass resources. In this paper, the effects of fuel composition on a micro gas turbine (μGT)-solid oxide fuel cell (SOFC) hybrid power generation system is investigated by using the part-load performance prediction analysis based on thermodynamic cycle simulation. The four different fuel compositions, i.e., CH_4/H_2O, CH_4/H_2, CH_4/CO and CH_4/CO_2, are taken up, and the volume fractions of methane are fixed at 50% in the all cycle analyses. As a result, it is found that the power generation efficiencies of the mixed fuel cases are lower than the efficiency of methane case, because the μGT fractional power increases in the case of the mixed fuel. Carbon monoxide has a most significant effect on the performance degradation among the four mixed fuel cases. The major factor of the μGT power increase depends on the change of air flow rate, which is caused by the variation in the balance of the heat released from the SOFC and the heat absorbed into the reforming process. This characteristics means that the operating conditions of the μGT with the mixed fuels become overload to obtain the same power output as the standard value of the methane case.