Repressurization technique for pressure swing adsorption

Claim 1

In a pressure swing adsorption process for the separation of a gaseous mixture comprising conducting the gaseous mixture under pressure over a carbon molecular sieve adsorbent in a pressurized adsorber having an inlet and an outlet, said adsorbent being capable of adsorbing at least one component selectively over the other components; discharging from said outlet a gaseous stream enriched in one or more other components; lowering the pressure above the adsorbent for regenerating purposes wit liberation of a gaseous stream enriched in at least the one component; repressurizing the adsorber; and repeating the cycle thereover, the improvement which comprises conducting said repressurizing in at least two stages, wherein the pressure buildup in the first stage or stages to an intermediate pressure is effected relatively rapidly, and the pressure buildup in the last stage to the final adsorption pressure is conducted substantially more gradually, said improvement resulting in the diminution of a surge of undesired component in the initial stream discharged from the repressurized bed.