气扫式多效膜蒸馏过程研究

PROCESS STUDY ON SWEEPING GAS MULTIPLE-EFFECT MEMBRANE DISTILLATION

针对气扫式膜蒸馏(SGMD)过程能耗高的问题,设计了1种气扫式多效膜蒸馏(SGMEMD)过程,其特征是在传统SGMD过程中设立独特的热量回用系统。该系统同时具有蒸汽的换热冷凝与料液的预热升温双重作用,从而实现蒸汽潜热的梯级回收利用。实验研究了吹扫气流速、料液循环流量、膜组件内料液与吹扫气流向、料液浓度对SGMEMD过程膜蒸馏通量和造水比(GOR)的影响。结果表明,当采用质量分数2.5%的NaCl溶液作为原料液,料液温度为78℃、循环体积流量为5.0L/h、吹扫气流速为1.6m/s(标准状态),膜组件内吹扫气与料液为逆向流动时,SGMEMD过程的GOR可达3.1。

Based on the high energy consumption of sweeping gas membrane distillation （SGMD） process, a novel sweeping gas multiple-effect membrane distillation process （SGMEMD） was designed. The process was set up for the first time coupled with a special latent-heat recovery system where the vapors got condensed and the feed was heated up simultaneously. Thus the latent-heat could be recycled gradually and effectively. The effects of sweeping gas flow velocity, feed circulation volumetric flow, the flow direction between feed and sweeping gas in the modules and the feed concentration on the permeate flux and the Gained Output Ratio （GOR） were investigated. The process could reach a GOR of 3.1 when the mass fraction of NaC1 solution with a 2.5% was used to experiment, the feed temperature was 78 ℃, feed circulation volumetric flow was 5.0 L/h, sweeping gas velocity was 1.6 m/s （under standard state conditions）, the flow direction between feed and sweeping gas was counter flow.