Physical absorption of CO_2 and H_2S from synthetic biogas at elevated pressures using hollow fiber membrane contactors: The effects of Henry's constants and gas diffusivities

摘要

The present study applies the mathematical model to investigate the physical absorption of CO2, H2S and CH4 from synthetic biogas at high pressure using hollow fiber membrane contactors. Henry's constants are considered pressure and temperature dependent, while the polarity of H2S is included in the calculation of gas diffusivities. The model was validated with the experimental data using two hollow fiber membranes, i.e., polyvinylidenefluoride (PVDF) and polytetrafluoroethylene (PTFE), to analyze membrane wetting. The effects of pressure and temperature on the CO2 and H2S absorption and CH4 loss were investigated. From the model validation, the experimental results using PVDF and PTFE at 1 bar are in good agreement with non-wetting mode. At elevated pressures, non-wetting mode results correspond with the experimental results using PTFE, while the partially wetting mode well predicts the results of PVDF. The modeling results also indicate that increasing pressure and reducing temperature improves the absorption fluxes of CO2 and H2S, while the CH4 losses in this work are lower than 5.5%. (C) 2018 Elsevier Ltd. All rights reserved.