Process for recovering organic vapors from air

Claim 1

A process for separating and recovering organic vapors from a feedstream of organic vapor and air wherein organic vapors are present in the "window concentration" range, being too high for conventional carbon adsorption an tool low for efficeint compression/condensation recovery, comprising the steps of: (a) providing a semipermeable membrane means for separating organic vapors rom air having a feed side and a permeate side wherein said semipermeable membrane means is characterized as having a selectivity for allowing the passage of organic vapor relative to air or for allowing the passage of air relative to organic vapor of at least 10 and permeablility for the permeate gas of greater than 1×10 -7 cm 3 (STP).cm.cm -2 .cmHg -1 .sec -1 ; (b) passing a feed stream of organic vapor and air, wherein said organic vapor is present in the "window concentration " range of about 6 volume percent to about 30 volume percent organic vapor, across the feed side of the semipermeable membrane such that organic vapor or air, but not both, passes preferentially through the membrane to form an organic vapor depleted air stream characterized by an organic vapor concentration below the "window concentration" range and an organic vapor enriched stream characterized by an organic vapor concentration above the "window concentration " range; (c) subjecting said organic vapor depleted air stream produced in step (b) to carbon adsorption, thus separating and recovering organic vapor therefrom; and (d) subjecting said enriched stream produced in step (b) to compression and condensation, thus separating and recovering organic vapor therefrom.