Study on CO_2 Removal from Air by Hollow - fiber Membrane Contactor

摘要

For C0_2 removal from air, two kinds of alkanolamines as the absorbents, A and B, were chosen. The experimental system contains two polypropylene hollow - fiber membrane modules used for absorption and desorption ( regeneration of absorbent) . The absorption, desorption and continuous absorption - desorption tests were carried out respectively. The effect of absorbent flow rate VL and air flow rate VG on mass transfer coefficient Ka for absorption, and the effect of operating condition on regeneration of absorbent was investigated. The experimental results showed that related concentration y_(out)/y_(in) decreased with increasing of V_L and increased with increasing of V_G. In the absorption process, the Ka for absorbent A was at least 3 times that for absorbent B, but in the regeneration processes it was reverse. The absorption effect of shell - flow model was better than that of fiber- flow model. When the absorption and regeneration temperature was about 20°C and 35°C respectively in the process, CO_2 concentration can be decreased from 1.0% to 0.3% in air at the outlet. Mass transport in gas phase is the controlling step for absorbent A. However, for absorbent Bit was controlled by liquid phase. The Ka got from mathematical model agreed with the experimental results. Based on this investigation the preliminary scheme of the prototype used for removing CO_2 from air was design.