An annular reactor for direct methane autothermal reforming

An annular reactor for direct autothermal reforming of methane was proposed and studied numerically. A one-dimensional heterogeneous model was developed. The effects of feed inlet temperature, initial bed temperature and reactor length were investigated systematically to elucidate the autothermal boundary conditions. Simulation results indicate overall autothermal operation can be achieved if the reactor length exceeds 0.05 m and can be sustained with feed inlet velocity in the range from 0.2 to 5.0 m s(-1). Simulation results reveal autothermacity can be kept with air-to-methane ratio of 1.0, which is lower than the theoretical value of 1.5. This is caused by the fact that most of consumed methane was oxidized only. Moreover, drastic bed temperature oscillation was observed in the start-up, which results from the mutual heat transfer between shell and tube in a small range and can be dampened by prolonging reactor length.