Effect of membrane module arrangement of gas–liquid membrane contacting process on CO2 absorption performance: A modeling study

Mathematical models have been developed to analyze and predict the physical absorption performance of CO2 through hollow fiber membrane contactors with different membrane module arrangements. The membrane contactor module is operated under partially wetted and counter-current flow mode. Four membrane module arrangements including single-stage module (SM), in parallel two-stage module (IP-TM), in series two-stage module with separated liquid flow (IS-TMS) and in series two-stage module with combined liquid flow (IS-TMC) are considered. The difference in module arrangement results in different degree of membrane wetting and concentration profiles along the module. The simulation is performed at the liquid flow rates in a range of 5.67–15.75 m3/s. At low liquid flow rate (up to 7.5 × 10−5 m3/s) at which the penetration of liquid into membrane pores is less than 7.6%, the total resistance is dominated by liquid phase. The absorption performance shown in term of contact area can be ranked as SM > IS-TMC > IP-TM > IS-TMS. For high liquid flow rate, the gas phase resistance becomes comparable to the liquid phase resistance. The IS-TMS shows highest absorption performance followed by IP-TM, IS-TMC and SM, respectively. The effects of important design parameters including gas composition (CO2–CH4), split ratio of liquid (α), the fraction of CO2 removal at the middle and exit of stage (xM, xexit), liquid temperature and number of stage on required contact area are also investigated.