Abstract: The present invention is an improved process for the production of nitrogen and oxygen that uses a double distillation column arrangement. The improvement to the process is the recycling of at least a portion of the oxygen-enriched waste stream to the bottom of the high pressure column. As a result of this improvement, the process is capable of making a nitrogen product with high purity (e.g., 5 ppm oxygen product) at high pressures (e.g., 40 to 150 psia) while simultaneously producing high purity oxygen (e.g., 99.6% oxygen). Nitrogen is produced only from the high pressure column.

Abstract: A process is set forth for recovery of nitrogen from a feed gas stream, containing nitrogen and oxygen, using a cryogenic separation wherein a recycle stream having an oxygen content above that of the feed gas stream is recycled separately and independent of the feed gas stream to the cryogenic separation zone without any intervening process step that would decrease the oxygen content of the recycle stream.

Abstract: The present invention is an improvement to a standard nitrogen generator. The improvement is two-fold; first, the addition of one or more distillation stages above the reboiler, which stages effectively transform the reboiler/condenser into a partial low pressure column and allow further separation (rectification) of the nitrogen generator bottoms liquid into two streams. Second, the recycle of the overhead stream (at a composition close to that of air) from the top of the low pressure column to the main air compressor. Additionally, at least a portion of the oxygen-enriched stream that exits the low pressure column below the bottom tray is expanded to provide refrigeration for the cycle.

Abstract: Separation and individual recovery of high purity hydrogen and carbon monoxide from a mixed gas stream containing these compounds in association with carbon dioxide and one or more minor components such as particularly methane, is achieved by pressure swing adsorption to remove contained carbon dioxide from the charged gas, and further treatment of the CO.sub.2 -freed gas product by a sequence of steps utilizing (a) pressure swing adsorption and (b) selective permeation through a series of semi-permeable membranes, which steps (a) and (b) are carried out in either order of sequence.

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: Hydrogen and carbon monoxide are each separately recovered in high yield from a multicomponent gas stream containing these compounds together with carbon dioxide and a zero to minor amount of one or more gaseous components from the group consisting of nitrogen, methane, water vapor and C.sub.2 -C.sub.6 hydrocarbons, by a process wherein the multicomponent gas stream, such as that obtained by steam methane reforming, is initially treated in a pressure swing adsorption unit to remove water and CO.sub.2, and the obtained effluent freed of CO.sub.2 and water is then further subjected to (1) cryogenic fractionation to condense CO and to (2) hydrogen purification by selective adsorption (in either order) to recover high purity carbon monoxide and essentially pure hydrogen. The CO.sub.2 -laden adsorbent is regenerated by purging with a H.sub.2 O and CO.sub.2 -free waste gas stream from the hydrogen purification adsorbent bed or from the cryogenic fractionation or from both of these.