Method and apparatus for adjustably treating a sour gas

A method for treating a feed gas, comprising CO2, H2S and H2, to produce an H2-enriched product and an H2S-lean, CO2 product, the method comprising:

• separating the feed gas by pressure swing adsorption to form a stream of H2-enriched product gas and a stream of sour gas, the sour gas also comprising CO2, H2S and H2 but being depleted in H2 and enriched in H2S and CO2 relative to the feed gas;
• dividing the stream of sour gas into two parts;
• processing one part of said stream of sour gas in an H2S removal system to form one or more streams of sweetened gas, depleted in H2S and enriched in CO2 relative to the feed gas;
• bypassing the H2S removal system with the other part of said stream of sour gas;
• and
• combining said stream(s) of sweetened gas with said sour gas bypassing the H2S removal system to form a stream of H2S-lean, CO2 product gas;
• wherein the division of the sour gas between being sent to and processed in the H2S removal system and bypassing said system is adjusted responsive to changes in the H2S content of the sour gas, such that the proportion of the sour gas processed in the H2S removal system, as compared to bypassing said system, is increased if the H2S content rises and decreased if the H2S content drops.