纤维膜萃取分离器内两相流动、传质特性的研究——液体黏度的影响

Flow and Mass-Transfer of Two Fluids in Fiber Film Extractor——The Effects of Liquid Viscosity

纤维膜萃取分离器是一种新型高效传质设备。今以苯甲酸水溶液-煤油为传质体系,在一直径70mm,高2630mm的有机玻璃纤维液膜萃取分离器冷态实验装置上,考察了纤维丝填充密度1.89%～5.08%,运动黏性系数0.942～1.138mm2·s-1,水油体积流量比3～6的操作区间内,考察了原料液黏度对纤维膜分离器内两相流动、传质性能的影响。结果表明,在几种填充密度和水油比条件下,随着黏度的增加,流体停留时间延长,两相接触、混合得更均匀;传质系数呈现先增大后减小的趋势;最佳传质工况(即体积传质系数达到最大值)与原料液黏度和纤维丝填充密度密切相关。根据实验结果,给出了用于计算流体在萃取分离器内停留时间以及两相混合均匀性指数的关联式。

Fiber film extractor is a novel high-efficiency equipment for two-fluid mass-transfer.In this study,the kerosene and benzoic-acid-water were used as the experimental mass-transfer system.Varying the packed density of the fiber from 1.89% to 5.08%,the liquid viscosity from 0.942 mm2·s-1 to 1.138 mm2·s-1 and the flow ratio from 3 to 6,the effects of liquid viscosity on the performances of fiber-film extractor were investigated on a cold model of Plexiglas pipe with I.D.of 70 mm and height of 2630 mm.Under different fiber packed densities and flow ratios,the experiments show that,with increasing the liquid viscosity,the residence time of two-fluids increases sequentially;meanwhile,the contact and mixing between the two fluids become more uniform.In addition,with the increase of the liquid viscosity,the mass-transfer coefficient between the two fluids increases at first and then decreases.The optimal condition for mass-transfer appears to be closely related to the liquid viscosity as well as to the fiber packed density.Based on the experimental results,two empirical equations for predicting respectively the fluid residence time and the uniformity index of mixing in the fiber film extractor were given.