Abstract: A method and apparatus for the separation and recovery of SF6 from a gas mixture consisting essentially of SF6, CF4, and N2. The method and apparatus involve membrane separation to separate N2 from SF6 and CF4, and liquefaction to separate SF6 from CF4.

Abstract: A process for producing carbon dioxide from a gas stream containing same pretreats the incoming raw gas to remove contaminants and particularly to protect degradation of the membranes utilized for separation. The temperatures of the various gas streams are carefully controlled to reduce water from the stream. By-product and other gas streams of the process are recycled in order to increase efficiency by utilizing the heating or cooling properties of the streams. In addition, streams containing minor portions of carbon dioxide are returned to the system for recovery.

Abstract: A process to bulk separate H.sub.2 S and CO.sub.2 from a sour gas by first cooling the inlet sour gas, passing the cooled sour gas through a separator and removing a liquid acid gas as a bottoms product in a fractionation tower, and then either pumping or free flowing the liquid acid gas into a disposal well. Potential sulphur deposition problems are controlled by recycling liquid acid gas to the plant inlet.

Abstract: An elevated pressure nitrogen stream from an air separation plant is used to provide cooling for one or more sulphur condensers in an oxygen-enhanced Claus process for recovering sulphur.

Abstract: A process for liquefying natural gas containing mercaptans. Mercaptans are concentrated into a distillate stream by distilling the feed gas stream without specific pretreatment for mercaptans removal. Thus, the mercaptans removal equipment is much smaller since mercaptans treatment can take place at a point in the process where the flowrate is much lower. A portion of the treated distillate stream can be reinjected to the upstream distilling stage to facilitate mercaptan absorption.