Abstract: A natural gas feed stream containing significant quantities of nitrogen and/or carbon dioxide can be increased to a content of greater than 95 percent by volume of natural gas, and preferably greater than about 98 percent, by passing the natural gas feed stream sequentially through three adsorbent beds that are cycled through seven phases comprising: an adsorption phase to adsorb a first gas, a first depressurization phase to remove feed gas from the voids in the adsorbent bed, a recycle phase to remove a second gas from the adsorbent by the passage of a second depressurization gas therethrough and to produce a recycle gas, a second depressurization phase to reduce the adsorbent bed pressure to about ambient and to produce the second depressurization gas, an evacuation phase where the pressure in the adsorbent is further reduced and an enriched primary gas product stream recovered, a pressurization phase where the pressure in the adsorbent bed is increased using secondary product gas from a bed in an adsorpti

Abstract: The present process is directed to the efficient recovery of helium gas from gas streams which contain about 25 percent by volume or more helium. The process comprises two stages of pressure swing adsorption, each stage being comprised of a plurality of interconnected adsorbent beds. In the first stage of pressure swing adsorption which is comprised of about five phases, the helium content of the gas stream is increased to 95 percent by volume or more. A secondary product gas stream from the first stage of pressure swing adsorption is fed to the second stage of pressure swing adsorption. The second stage of pressure swing adsorption increases the helium content of this primarily non-helium product gas to more than about 50 percent by volume. This gas now with a helium content of more than about 50 percent by volume is fed along with the gas stream as the input gas to the first stage of pressure swing adsorption.