乙醇水溶液真空膜蒸馏分离过程的模拟分析

真空膜蒸馏技术可用于分离水溶液中的有机挥发性化合物(VOCs),是一种治理遭受VOCs污染工业废水的新方法.对低浓度乙醇水溶液二元体系下的真空膜蒸馏过程展开了模拟分析,膜内的传质按Knudsen扩散原理考虑,界面上的平衡关系按Van Laar活度系数法给出.模拟结果表明:过程的操作参数对分离效率有较大的影响,进口温度、料液流量、浓度和真空度增加,膜通量将增加;分离因子随进口温度、真空度、浓度增加而减少,料液流量对分离因子影响与真空侧流动形式有关.真空侧流动形式对分离因子有一定的影响,并流条件下,分离因子最大.

Numerical simulation on vacuum membrane distillation process of ethanol - aqueous mixtures

Vacuum membrane distillation(VMD) was investigated as a possible alternative technique for the removal of volatile organic compounds(VOCs) from contaminated water.In this paper,a mathematical model of vacuum membrane distillation that based on Knudsen diffusion principle for low concentration ethanol-aqueous mixtures was setup and solved by numerical method.In this model,vapor-liquid equilibrium is calculated according to Van Laar method.The simulation result shows that the impact of operation variables such as feed concentration,flow rate,temperature and downstream pressure has a great effect on the separation efficiency.The flux is increasing with feed concentration,flow rate,temperature and degree of vacuum increasing.The separation factor is decreasing with feed concentration,temperature and degree of vacuum increasing.Downstream direction in shell-side also has an effect on the separation factor and the value of separation factor is biggest in the co-current flow condition.