Integrating chemical kinetics with CFD modeling for autothermal reforming of biogas

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 CO₂ 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-CH₄ ratio (S/CH₄) and air-to-CH₄ ratio (A/CH₄) equal to 0.5 and 2, respectively, can achieve high H₂ concentration, while operation with S/CH₄ and A/CH₄ equal to 4.5 and 2, respectively, can achieve high energy efficiency. The results also show that using either H₂ or O₂ membrane in the reformer can enhance the biogas autothermal reforming performance by producing high concentration of H₂ (40-65%) and solving the harmful hot spot problems. © 2009 Professor T. Nejat Veziroglu.