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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。
Aiming at the high energy consumption of gas swept membrane distillation (SGMD) process, a gas swept multi-effect membrane distillation (SGMEMD) process is designed, which is characterized by a unique heat recovery system in the traditional SGMD process. The system also has the double role of heat transfer and condensation of steam and preheating and warming of feed liquid, so as to realize the cascade recovery of steam latent heat. The effects of purge gas flow rate, feed liquid circulation flow rate, feed liquid and purge flow in the membrane module and feed liquid concentration on the membrane distillation flux and water evolution ratio (GOR) of the SGMEMD process were experimentally studied. The results showed that when the mass fraction of 2.5% NaCl solution was used as raw material liquid, the feed liquid temperature was 78 ℃, the circulating volume flow rate was 5.0L / h and the purge gas flow rate was 1.6m / s (standard state) When the scavenging and feed liquid are in reverse flow, the GOR of the SGMEMD process can reach 3.1.