Patent ID: 6059857
Filing Date: 2000-05-09
Classification: B01D

Abstract:
A process for the removal of water, ionic species and particulates from a contaminated organic solvent comprising the steps:(a) vaporizing at least a portion of said contaminated organic solvent to produce (i) a vaporous feed stream comprising a mixture of solvent vapor, water vapor, ionic species and particulates, and (ii) a non-vaporous liquid effluent stream comprising a mixture of liquid solvent, liquid water, ionic species and particulates;(b) directing said non-vaporous liquid effluent stream from step (a)(ii) to means for further treatment or discharge;(c) removing water vapor from said vaporous feed stream from step (a)(i) by a vapor permeation process to produce a water vapor-depleted vaporous feed stream, said vapor permeation process comprising the steps:(i) providing a membrane having a feed side and a permeate side that is selectively permeable to water vapor;(ii) directing said vaporous feed stream from step (a)(i) to the feed side of said membrane while withdrawing a retentate stream depleted in water vapor and withdrawing a permeate stream enriched in water vapor from the permeate side of said membrane; and(iii) directing a gas phase sweep stream to the permeate side of said membrane, said sweep stream having an upstream side and a downstream side and flowing countercurrent to the flow of said vaporous feed stream of step (a)(i), wherein the partial pressure of water vapor in said sweep stream is sufficiently low that the ratio of the partial pressure of water vapor in said sweep stream to the partial pressure of water vapor in said retentate stream is less than 0.9;(d) condensing said water vapor-depleted vaprous feed stream to produce a dehydrated liquid feed stream;(e) removing particulates from said dehydrated liquid feed stream by filtration; and(f) directing said dehydrated liquid feed stream to ion-exchange contact means to produce a dehydrated, ionic species-depleted liquid feed stream.