Process design of continuous-flow pervaporation separation for alcohol dehydration

The separation characteristics of the PVA-CS (polyvinyl alcohol-chitosan) b lended composite membrane for dehydration of ethanol-water mixture are exam ined. The relationships of flux and separation factor with the feed concent ration and operation temperature are established. Using this correlated equ ation, the continuous-flow pervaporation process about 500 kilolitres/year dehydrated ethanol is designed. The numbers of stage and reheater are calcu lated by stage-by-stage method for two kinds of cascades: one with equal me mbrane area and the other with 10 degreesC of temperature decrement per sec tion. The results show that when the numbers of stage and reheater are the same, the cascade with 10 degreesC of temperature decrement has more advant ages than that with equal membrane area. The influences of feed concentrati on and flow rate on the numbers of stage and reheater in the cascades are d iscussed.