Exploring the multiphase flow and mass transfer characteristics for desulfurization in an upflow biogas reactor

Abstract

With the increasing requirements for biogas desulfurization, the LO-CAT process design needed to be optimized to meet the production requirements. The purpose of this study was to establish a joint optimization model based on two-film theory and response surface methodology (RSM) to investigate the gas-liquid flow, mass transfer, and chemical reaction processes of the biogas reactor and to obtain the optimal operating conditions. The model was validated based on the measured data of the biogas reactor in a 355 KW desulfurization unit at the landfill. It was revealed that the optimal parameters for the gas-liquid flow field were a particle diameter of 3100 µm, a liquid/gas ratio of 19 L/m3, a nozzle angle of 55°, and an inlet velocity of 16 m/s. The effect of inlet velocity was most significant in the LO-CAT process due to its internal extended entrance. The synergistic modulation between gas and liquid then improved the homogeneity of the flow field through vortices, increasing flow field uniformity by 20.8%. The absorption of H2S was closely related to the change in flow pattern; the mass transfer process was mainly limited by the "liquid membrane limitation." Optimized parameter desulphurization efficiency increased by 28.76%. This study provided practical significance for the rational design and optimized operation of industrial biogas purification plants based on multiphase flow reaction transfer.