Fractionation of multicomponent dimethylnaphthelenes feeds by selective

Abstract

A process and system for separating a preferentially crystallizable component A from a feed, wherein a series of zones are used between which mother liquor can flow without passage of crystallized material. Liquid feed is introduced to a zone other than the end zone from which effluent rich in component A is withdrawn. During one stage gradating crystallization temperature pattern is established throughout the series ranging from relatively low to relatively high, causing component A to crystallize in each zone; and mother liquor is caused to flow toward the low temperature end, while a portion of previously withdrawn effluent rich in component A is returned to the higher temperature end and effluent lean in component A is removed from the lower temperature end. In another stage a higher temperature pattern is established throughout the series whereby at least a portion of crystallized material melts in each zone, and mother liquor is caused to flow in the opposite direction while an equivalent amount of effluent rich in component A is withdrawn from said end zone.