Performance Evaluation of Catalytic Combustor for High Temperature Fuel Cell System under Load Changes

摘要

The high temperature fuel cell of stationary power plant is consumed parts of induced fuel and oxidizer for the stability and the durability concerns of the fuel cell system. Since very significant amount of residual portion of fuel is exhaused without any utilization, the high temperature fuel cell is equiped with off-gas energy regenerator. Even though the fuel utilization rate is improved as technical issues are resolved, the fuel is still slipped from the high temperature fuel cell. The slipped fuel is very difficult to be combusted with conventional burner because it has lean fuel and high concentration of vapor. In this study, a catalytic combustor is applied to be used up all of slipped fuel mixture so that the flame stability of the unburned fuel mixture is ensured. The model combustor is composed of static mixer, plenum, perforate plates, and monolithic catalysts and it is designed to investigate various types of catalyst. Since the performance of catalytic combustor directly depends on the catalyst, the catalyst selection has been carried out. The operating point of the catalytic combustor is determined by cycle analysis which includes mass and heat balances of reformer, fuel cell stack, catalytic combustor and auxiliary devices. Under the operating condition, basic performance has been investigated over various parameters. Performance of catalytic combustor satisfies operating condition of rated conditions as well as those of start-up and shut-down. In this study, the performance of catalytic combustor is investigated over some start-up scenarios suggested by cycle simulation.