Separation of Alcohol−Water Solutions by Distillation through Hollow Fibers

Abstract

New results of an investigation on distillation in hollow fiber structured packing are discussed. The membranes used here for separation of methanol−, ethanol−, and 2-propanol−water solutions are nonselective coated hollow fibers, unlike those of membrane distillation. The fibers are nonselective with coating and have little resistance to mass transfer. Because liquid flows inside the lumens of the fibers and vapors flow countercurrently outside the fibers, this distillation process can avoid flooding effectively even at very high flows. As a result, when a mole fraction of alcohol equal to 0.04 was prepared as feed in all distillations, an attractive low value of the height of mass transfer unit (HTU) less than 0.1 m could be obtained at total reflux. Both the distillate concentration and the height of mass transfer unit more significantly decreased with heat rate in alcohols at low molecular weight than in those at high molecular weight. Compared with conventional structured packing, the ordinate data o...