Six adsorber pressure swing adsorption process

In a pressure swing adsorption process for the purification of a gaseous stream with the use of six adsorbers cyclically operated, wherein the gaseous stream during an adsorption phase at the highest process pressure is conducted through an adsorber, and purified gas is withdrawn from the outlet end of the adsorber, the adsorber being subjected, after termination of the adsorption phase, to a multistage cocurrent expansion, and the resultant expansion gases being utilized, in part, for pressure buildup of other, previously scavenged adsorbers and, in part, for scavenging another adsorber which is at the lowest process pressure, whereafter a countercurrent expansion is performed to the lowest process pressure and scavenging is conducted with cocurrent expansion gas from another adsorber, followed by multistage pressurizing to the adsorption pressure with cocurrent expansion gas and purified product gas,

• the improvement comprising operating the process with only one adsorber at a time in an adsorption phase, and with four or five cocurrent expansion phases, of which one yields scavenging gas for another adsorber and the remaining expansion gases are conducted in pressure equalization with other adsorbers to be pressurized.