Process for producing a purified synthesis gas stream

摘要

A process for producing a purified synthesis gas stream from a feed synthesis gas stream comprising besides the main constituents carbon monoxide and hydrogen also hydrogen sulphide,HCN and/or COS, the process comprising the steps of: (a) removing HCN and/or COS by contacting the feed synthesis gas stream with a water gas shift catalyst in a shift reactor in the presence of steam/waterto react at least part of the carbon monoxide tocarbon dioxide, and to obtain a synthesis gas stream depleted in HCN and/or in COS; (b) removing hydrogen sulphide in the synthesis gas stream depleted in HCN and/or in COS by contacting this gas stream in a HS-removal zone with an aqueous alkaline washing liquid to obtain a HS-depleted synthesis gas stream and a sulphide-comprising aqueous stream; (c) contacting the sulphide-comprising aqueous stream with ulphide-oxidizing bacteria in the presence of oxygen in a bioreactor to obtain a sulphur slurry and a regenerated aqueous alkaline washing liquid; (d) removing carbon dioxide from the HS-depleted synthesis gas stream, to obtain the purified synthesis gas stream and a gas stream enriched in CO..