Process for producing purified gas from gas comprising H2S, CO2 and HCN and/or COS

A process for producing a purified gas from a feed gas comprising H2S, CO2 and a contaminant of either HCN or COS, or both, the process comprising the steps of:

• (a) contacting the feed gas with a HCN/COS hydrolysis sorbent in the presence of water in a HCN/COS hydrolysis unit, thereby obtaining gas depleted in the contaminant;
• (b) contacting the gas depleted in the contaminant with an absorbing liquid in an H2S/CO2 absorber to remove H2S and CO2, thereby obtaining the purified gas and an absorbing liquid rich in H2S and CO2;
• (c) heating and de-pressurising at least part of the absorbing liquid rich in H2S and CO2 to obtain a hot flash gas enriched in CO2 and an absorbing liquid enriched in H2S;
• (d) contacting the absorbing liquid enriched in H2S at elevated temperature with a stripping gas, thereby transferring H2S to the stripping gas to obtain a regenerated absorbing liquid and a stripping gas rich in H2S;
• and
• (e) leading at least part of the hot flash gas enriched in CO2 to the HCN/COS hydrolysis unit;
• wherein the operating conditions of the H2S/CO2 absorber in step (b) are chosen such that H2S is absorbed preferentially with respect to CO2;
• wherein the stripping gas rich in H2S comprises in the range of from 30 to 90 volume % of H2S;
• wherein the feed gas comprises at least 0.5 volume % of CO2;
• wherein step (c) is performed at a temperature in the range of from 90 to 120° C. and a pressure in the range of from 2 to 4 bara;
• and, wherein the hot flash gas obtained in step (c) comprises in the range of from 10 to 90 volume % of CO2.