Test Results of a 100kW Class Mechanical Balance of Plant for High Temperature Fuel Cell Systems

A 100kW class mechanical balance of plant comprised of a catalytic combustor and an eductor has been designed and tested for high temperature fuel cell systems. The catalytic combustor, which oxidizes residual fuel in the anode exhaust gas, was operated at several conditions. Some problems arose due to local overheating or auto-ignition, which could limit the catalyst life. The combustor was designed by considering both gas mixing and gas velocity. Test results showed excellent temperature uniformity. In addition, several eductors were designed and tested to form a suction on the fuel exhaust gas and balance the pressures of both electrodes over a range of operating conditions. The tests showed that the design of the nozzle and throat played an important role in balancing the anode and cathode-side gas pressures. The results for both stand-alone and integration into another balance of plant are discussed.