Verfahren zur Rueckgewinnung organischer Daempfe aus Luft

US 4553983 A UPAB: 19930925 Organic vapour is recovered and concentrated from a feed stream of air having an organic vapour content of no more than 20000 ppm by vol., by (a) providing a thin semipermeable membrane having a feed side and a permeate side, a selectivity for organic vapour over air of at least 50, as measured by the ratio of organic vapour permeability to nitrogen permeability, and a permeability of organic vapour of at least 3 x 10 power (-7) cm3 (STP)cm2 sec.cm Hg; (b) passing the feed stream across the feed side of the thin semipermeable membrane while providing a pressure on the permeate side which is lower than the feed side by creating a partial vacuum on the permeate side such that organic vapour passes preferentially through the membrane to form an organic vapour depleted air stream on the feed side and an organic vapour enriched stream on the permeate side; and (c) compressing and condensing the organic vapour which has passed through the membrane to recover the vapour as a liq. USE - Recovering organic vapour from an air feed stream contg. a low concn. of organic vapour, which may be present in a high temp. air stream, to permit recovery and reuse of the solvent so recovered. 0/4