Pressure swing adsorption process which provides product gas at decreasing bed pressure

Abstract

A pressure swing adsorption process for the separation of a pressurized feed gas containing at least one more strongly adsorbable component and at least one less strongly adsorbable component. The process comprises (a) introducing the pressurized feed gas into a feed end of an adsorber bed containing one or more solid adsorbents which preferentially adsorb the more strongly adsorbable component and withdrawing from a product end of the adsorber bed a first adsorber effluent gas enriched in the less strongly adsorbable component, wherein the first adsorber effluent gas is utilized as final product gas; (b) terminating the introduction of the pressurized feed gas into the adsorber bed while withdrawing from the product end of the adsorber bed a second adsorber effluent gas enriched in the less strongly adsorbable component, wherein the pressure in the adsorber bed decreases while the second adsorber effluent gas is withdrawn therefrom, and wherein the second adsorber effluent gas is utilized as additional final product gas; (c) depressurizing the adsorber bed to a minimum bed pressure by withdrawing additional gas therefrom; (d) repressurizing the adsorber bed by introducing repressurization gas into the bed, wherein at least a portion of the repressurization gas is provided by pressurized feed gas; and (e) repeating steps (a) through (d) in a cyclic manner. No final product gas is required for purge or repressurization in the process cycle steps.