Hollow Fiber Membrane Process for Simultaneous Absorption of CO2 and SO2 from Flue Gas

Membrane gas contactors are a promising alternative to conventional post combustion carbon capture technologies. However, residuals of other acid gas compounds can exist in the flue gas streams emitted from industrial facilities that might have a notable impact on the absorption performance of the membrane system. Simultaneous removal of CO₂ and SO₂ from a simulated flue gas stream was carried out in a polytetrafluoroethylene (PTFE) hollow fiber gas-liquid membrane contacting (GLMC) system using different scrubbing solutions. A series of experiments was conducted to study the effects of operating conditions such as gas and liquid cross flow velocity, concentration of feed gas, absorbent nature and concentration, and long-term performance of the GLMC system on the removal efficiencies and mass transfer rates of CO₂ and SO₂. Experimental results indicated that simultaneous absorption of CO₂ and SO₂ enhanced with increasing the liquid-phase cross flow velocity, decreasing gas-phase cross flow velocity, and using chemical stripping absorbents. Moreover, sodium hydroxide is a more superior absorbents in compared with alkanolamine solutions for the co-capture of CO₂ and SO₂ gases. It was observed that low concentrations of SO₂ in the feed gas had a minimal impact on the decarbonization of GLMC system. The durability of the membrane system was also evaluated by running the simultaneous gas removal experiments over a 24-hour period. Consistency of the absorption efficiency results confirmed the potential of using PTFE membrane system for the simultaneous absorption of CO₂ and SO₂ gases.