Abstract: A crude helium product is produced from a natural gas stream containing helium by rectification of the feed gas in a dephlegmator heat exchanger. The process is fully auto-refrigerated, and is capable of achieving a helium recovery of 99% without the use of a recycle compressor or a heat pump compressor. A nitrogen product stream can be produced by addition of a second rectification circuit in the dephlegmator heat exchanger.

Abstract: The present invention is a process for prefractionating a pressurized, helium-containing feed gas mixture (typically containing helium, natural gas and nitrogen) to produce a helium-enriched stream which comprises the following steps: (a) the pressurized, helium-containing feed gas mixture is liquefied and subcooled by indirect heat exchange; (b) the liquefied, subcooled, pressurized, helium-containing feed gas mixture is expanded whereby it is partially vaporized, thus producing a partially vaporized frationation feed stream; (c) the partially vaporized frationation feed stream is stripped in a cryogenic distillation column thereby producing as an overhead, the helium-enriched stream, and a bottoms liquid, the helium-lean stream; and (d) the cryogenic distillation column is reboiled by vaporizing at least a portion of the helium-lean stream. The present invention is also applicable as an improvement to a process for the production of a crude helium product (i.e.,>30 vol % helium).

Abstract: High purity methane is recovered from a fuel gas stream containing the same in admixture with mainly nitrogen and carbon dioxide, by first removing the carbon dioxide by selective adsorption in a PSA system and separating the remaining nitrogen from the methane by cryogenic distillation, the rejected nitrogen being employed for purging the CO.sub.2 -laden adsorbent beds of the PSA system. Cyclic regeneration of the sorbent-laden bed may entail nitrogen purge with or without including a carbon dioxide rinse, or the nitrogen purge of the sorbent-laden bed may be used in combination with pressure let-down by gas withdrawal into one or more companion beds.

Abstract: An absorptive distillation using a C.sub.7 to C.sub.8 physical solvent without overhead condenser-reflux duty is described for separation of carbon dioxide from methane, wherein the separation preferentially uses heat energy in contrast to mechanical energy or power.

Abstract: A process is set forth for the separation of carbon dioxide from propane and higher alkanes using a carbon dioxide-loaded lean oil solvent and higher solvent flows and heat utilizations rather than mechanical energy utilization. A high pressure carbon dioxide product is produced, making the invention valuable in carbon dioxide miscible flood enhanced petroleum recovery operations.