Start‐Up and Load‐Change Behavior of a Catalytic Burner for a Fuel‐Cell‐Based APU for Diesel Fuel

Abstract

AbstractThe catalytic burner CAB 4 was developed for a fuel‐cell‐based diesel‐APU (auxiliary power unit) with a capacity of 14.5 kWth,APU. In order to operate a catalytic burner in such an APU, several requirements must be met. Normal operation involves combustion of anode off‐gas from the fuel cell. If the fuel cell malfunctions or if the gas quality is insufficient, the burner must also be able to fully convert the reformate while by‐passing the fuel cell. It must be possible to catalytically ignite the burner using a reformate with increased CO‐concentration. The burner must fully convert all combustible components in the fuel‐gas at all operating points. The energy contained in the fuel gas is utilized in the CAB to generate superheated steam with no oscillations and to supply this steam to the autothermal reformer. When the fuel processing system is being shut down, the burner should be able to continue providing steam for sweeping the downstream reactors for a limited period of time. Catalytic ignition of the CAB 4 was demonstrated with a reformate containing up to 5 mol.% CO. The behavior of the burner was characterized in steady‐state operation, during load changes, during transitions in the operating mode, and during shut‐down.