ANHYDROUS ETHANOL DISTILLATION METHOD AND APPARATUS

摘要

An improved distillation method and apparatus are provided for recovering anhydrous ethanol from fermentation or synthetic feedstocks. The system includes at least one stripper-rectifier tower, a dehydrating tower, and an azeotropic agent stripping tower. Substantial energy savings are realized by operating the dehydrating tower, and preferably also the azeotropic agent stripping tower, at a higher pressure than the stripper-rectifier tower and by condensing the overhead vapors from the dehydrating tower (or dehydrating tower and azeotropic agent stripping tower) to provide the heat required in the stripper-rectifier tower. In a preferred embodiment, two stripper-rectifier towers are used, one operating at a higher pressure than the other, in which case the higher pressure tower is heated as just described and the overhead vapors from the higher pressure tower are condensed to supply the heat required in the lower pressure tower. Further energy savings are accomplished by preheating the feedstock by means of the heat contained in the stripper-rectifier tower overhead (the lower pressure stripper rectifier tower in the case where two such towers are used) and also by the heat contained in the stripper-rectifier bottoms.