Experimental studies on simultaneous removal of CO2 and SO2 in a polypropylene hollow fiber membrane contactor

Membrane gas absorption technology is a promising alternative to conventional technologies for the mitigation of acid gases. In this study, simultaneous removal of SO2 and CO2 from coal-fired flue gas was carried out in a polypropylene hollow fiber membrane contactor using aqueous monoethanolamine as the absorbent. The influences of liquid and gas flow rates on the simultaneous absorption performance of CO2 and SO2 were investigated. The experimental results indicated that the membrane contactor could eliminate these two sour gases simultaneously and effectively. Absorption of SO2 and CO2 was enhanced by the increase in liquid flow rate and decrease in gas flow rate. It was observed that a small amount of SO2 in the flue gas had a slight influence on the absorption of CO2. In addition, the membrane contactor was operated continuously for two weeks to evaluate its duration performance. The results showed that the CO2 mass transfer rate was decreased significantly with the operating time due to partial wetting of membrane pores. After 14 days of continuous operation, the CO2 mass transfer rate of the wetted membrane contactor was decreased by 41% but could be retrieved to 86% of the fresh one by increasing the gas phase pressure.

► SO2 and CO2 could be simultaneously removed by membrane gas absorption technology.
► The existence of SO2 has a slight influence on CO2 absorption.
► Partial membrane wetting results in deterioration of system absorption performance.
► Performance of wetted membrane contactor could be retrieved to 86% of fresh one.