Patent ID: 6923844

Claim:
A gas separation method in which principal gas components are separated from a feed gas that includes at least a first gas component and a second gas component using a pressure swing adsorption method, comprising: a first separation step in which the first gas component is separated as a first gas product by using a first adsorbent that hardly adsorbs the first gas component and easily adsorbs the second gas component; and a second separation step in which the second gas component is separated as a second gas product by using a second adsorbent that easily adsorbs the first gas component and hardly adsorbs the second gas component; wherein in the first and second separation step, a circulating feed gas is used as the gas to be separated, where the circulating feed gas consists of recovered discharge gases that are discharged when the adsorbents are regenerated and the feed gas; and based on at least one of the component concentration in the circulating feed gas and the pressure of the gas delivery path, the second gas product is extracted at a constant outflow rate and component concentration by controlling the outflow rate of the first gas product.