Flow Uniformity of Catalytic Burner for Off-Gas Combustion of Molten Carbonate Fuel Cell

A catalytic combustor is a device to burn out the fuel by surface combustion that is used for the combustion of anode off-gas of molten carbonate fuel cell. By employing the catalytic combustor, the purified exhaust gas is able to be recirculated into the cathode channel for CO2 supply to improve thermal efficiency. The design of catalytic combustor depends on many parameters but the flow uniformity is particularly important during the emergency shut-down of fuel cell stack. Right before the temperature control of catalytic combustor is not yet activated, the catalytic combustor should burn out more than two times of rated amount of fuel flow rate. At the over-loaded condition, assurance of flow uniformity at the inlet of catalytic combustor can reduce the damage of catalytic burner caused by local hot zone. In this study, the flow uniformity of the catalytic combustor is investigated in two steps such as preliminary step with model combustor and main analysis step with practical 250 kW catalytic combustor. The 0.5 kW and 5 kW class combustors are applied for preliminary step. In preliminary step, the model combustor is used to determine supporting matters for the flow uniformity. Inlet direction of mixing chamber below the catalytic combustor is also examined in the preliminary step. In the main analysis step, flow uniformity of scale-up combustor has been examined with selected supporting matter and inlet direction into mixing chamber. Geometric and operating parameters are investigated. In particular, the flow rate at off-design operating condition has been examined.