Flue gas carbon capture using hollow fiber membrane diffuser-separator

In this work, CO 2 removal from flue gas using membrane diffuser–separator was investigated. Hollow fiber polypropylene membrane was used as the diffuser while pure water was used as the absorbent. Separation performance of the membrane diffuser–separator as a function of CO 2 concentration (6-28%-vol.) and flow rate (gas: 0.8-1.55 L.min -1 and liquid: 0.2-0.7 L.min -1 ) was investigated and optimized. It was found that CO 2 removal was significantly affected by CO 2 concentration in the feed gas. On the other hand, CO 2 flux was more influenced by flow rates of liquid and gas rather than concentration. The optimized CO 2 removal (64%) and flux (1 x 10 -4 mol.m -2 .s -1 ) were obtained at the highest gas flow rate (1.55 L.min -1 ), the lowest liquid flow rate (0.2 L.min -1 ), and 6.2%-vol. of CO 2 concentration. Outlet gas of the membrane diffuser system tends to carry some water vapor, which is affected by gas and liquid flow rate. Meanwhile, in the steady-state operation of the separator, the gas bubbles generated by the membrane diffuser take a long time to be completely degassed from the liquid phase, thus a portion of gas stream was exiting separator through liquid outlet.