中空纤维膜吸收CO_2过程的膜浸润研究

Study of membrane wetting in the process of CO_2 absorption by a polyvinylidenefluoride(PVDF) hollow fiber membrane

采用聚偏氟乙烯(PVDF)中空纤维膜组件吸收CO2,研究了二乙醇胺(DEA)水溶液对疏水微孔膜的润湿作用。实验分别考察不同吸收液浓度、温度、流速以及气体流速对膜润湿的影响,并通过对膜吸收和膜浸润过程的理论分析,建立了考虑孔径分布和浸润时间影响的相对浸润深度表达式。实验结果表明:随着吸收过程的进行,膜孔的平均相对浸润深度η逐渐增加,导致膜相传质系数k m随时间逐渐下降,虽然η增加缓慢且幅度很小,但由此引起的k m下降却非常明显;随着DEA浓度增加,膜孔的平均相对浸润深度η值变小;升高温度或提高液相流速都会使η增加,但温度对膜浸润的影响更加明显;在气相阻力可以忽略的条件下,改变气相流速对膜浸润的影响不大。

We have studied the membrane wetting in diethanolamine solution during CO2 capture in microporous polyvinylidene （PVDF） hollow fiber membrane contactors. The relative wetting depth （r/） was established, taking the membrane pore distribution and operating time into consideration. The experimental results showed that even al- though the relative wetting depth increased very slowly with time, the membrane mass transfer coefficient decreased significantly. We also studied the effects of varying the absorbent concentration, temperature, liquid flow rate and gas flow rate on membrane wetting. The relative wetting depth decreased with increasing concentration; increasing the temperature or the liquid velocity both increased the membrane wetting; however, changing the gas flow rate had no effect on the membrane wetting.