SF/sub 6/ reclaimer from SF/sub 6/N/sub 2/ mixtures by gas separation with molecular sieving effect

Abstract

This paper discusses the various methods for sulfur hexafluoride (SF/sub 6/) separation from a mixture of low concentrations of SF/sub 6/ in N/sub 2/ pressure swing adsorption (PSA) with a suitable kind of synthetic zeolite, which has the expected molecular sieving effect. This molecular sieving effect, derived from molecular size difference between SF/sub 6/ and N/sub 2/, is confirmed by the difference between two equivalent volumes filled with SF/sub 6/ and N/sub 2/. Prototype equipment of SF/sub 6/ separation and liquefaction, that is about 1 m cube in size and 150 kg in weight, has been assembled and tested. The ability of gas mixture handling is 13 l/min on average, and the SF/sub 6/ content is reduced to 0.0% (undetectable level) in separated N/sub 2/ to exhaust into the atmosphere.