蒸汽渗透与吸附耦合工艺用于乙醇脱水

A hybrid process of vapour permeation and molecular sieve adsorption for the dehydration of ethanol

蒸汽渗透与分子筛吸附耦合工艺用于乙醇脱水,充分利用了蒸汽渗透能耗低、操作简单的优点,同时充分利用了分子筛对微量水分高效吸附的特点。目前国内外对此新耦合工艺研究报导极少,其经济性试验验证及数据还非常缺乏。本文首先单独研究了蒸汽渗透过程中膜面积对渗透通量和分离因子的影响,发现渗透通量和分离因子随膜面积的增大而减小,原料侧水分越少分离越困难,膜用量将显著增多;其次,分子筛吸附试验结果表明吸附进口水分越多,则曲线透过时间越短;此外,采用透过曲线法对吸附过程进行模拟,得到了相应的吸附传质区长度、动态吸附量及饱和吸附量;最后,为了验证此耦合工艺的经济性建立了计算机经济核算模型,比较了不同试验条件下的投资及操作费用,结果表明,耦合工艺生产99.93 wt%乙醇时,蒸汽渗透膜面积为0.224 m^2时,投资及操作费用较省,且比同条件下采用单一蒸汽渗透工艺的费用低,经济性好,耦合工艺脱附液回收利用后操作费用可节省约40%。

The hybrid process of vapor permeation and molecular sieve adsorption is adopted as a solution for the dehydration of ethanol, based on the advantages of vapor permeation with low energy consumption and easy operation, and molecular sieve adsorption with high adsorption efficiency for small amount water. Current research on this new hybrid process are rarely reported at home and abroad, and its economy experimental verification and data are still few. In this work, the hybrid process was studied experimentally, and the effect of membrane area on permeation flux and separation factor was measured. The result showed that the permeation flux and separation factor were decreasing while the membrane area increasing. Effect of membrane area on membrane outlet ethanol concentration was analyzed, the results showed that the higher the ethanol concentration, the harder the separation process, and the membrane area increased geometrically. Effect of water concentration on the breakthrough curves was analyzed, the results showed that the higher the inlet water concentrations of adsorption and the shorter the breakthrough time. The adsorption process was modeled bv the breakthrough curve method. The length of mass transfer zone, the dynamic adsorption amount and the saturated adsorption amount were calculated via this method. Cost-effectiveness analysis model for the hybrid process was established. The operation cost and investment under different condition was given. The results showed that for the production of 99.93 wt% ethanol by the hybrid process, the optimal membrane area was 0.224 m2. Compared with the vapor permeation process, the hybrid process has a lower investment and operation cost. The recycled desorption liquid can decrease the operation cost by 40%.