Integrated Absorption and Regeneration Membrane Contactor Technology for Removal of CO2 and H2S from Natural Gas

Regeneration of rich amine using membrane contactor (MBC) is studied with observation on factors of operating temperature, flowrate and pressure. The desorption of CO2 and H2S were analyzed, and as a result operating pressure and liquid temperature were identified as the most significant parameters affecting desorption. Higher acid gas flux was observed at higher temperature and higher flowrate. Desorption of CO2 at higher flowrate is limited by the membrane contact area; whilst H2S was more readily desorbed. The higher operating transmembrane pressure of 0.3 barg is preferred as it provided good control during regeneration operation. The optimized parameter for rich amine regeneration was determined through ANOVA analysis using DesignExpert software. The optimum condition was found to be at 90 °C and 0.3 barg; these parameters were then used for the integrated operation of the absorption and regeneration membrane contactor. Continuous integrated testing was carried out and successfully met the specification for both sections. The absorption membrane contactor was able to remove CO2 from 25% down to 6.5% and H2S from 500ppm to below 20ppm. The regeneration section maintained good desorption of H2S where the recycled amine had less than 200ppm and for CO2 desorption 0.2 mol CO2/mol amine loading was removed.