Integrating chemical kinetics with CFD modeling for autothermal reforming of biogas

摘要

Using biogas for hydrogen production via autothermal reforming (ATR) can potentially increase the energy conversion efficiency and correspondingly reduce environmental impact. The present study aimed to investigate the performance and characteristics of biogas ATR. A two-dimensional numerical model was developed based on the integration of computational fluid dynamics (CFD) and chemical kinetics. The mass transport, chemical reactions and heat transfer can be analyzed simultaneously in the porous domain. The results show that the presence of CO_2 in the feedstock will reduce the performance of the biogas ATR. The effects of operating and feeding conditions were examined and the optimal conditions were identified. Operating the reformer with the steam-to-CH_4 ratio (S/CH_4) and air-to-CH_4 ratio (A/CH_4) equal to 0.5 and 2, respectively, can achieve high H_2 concentration, while operation with S/CH_4 and A/CH_4 equal to 4.5 and 2, respectively, can achieve high energy efficiency. The results also show that using either H_2 or O_2 membrane in the reformer can enhance the biogas autothermal reforming performance by producing high concentration of H_2 (40-65%) and solving the harmful hot spot problems.