Also known as: Claus unit, sulfur recovery, SRU
The process results in a molten sulfur product that can either be sold directly in liquid form or converted into solid pellets by cooling with water.
How it works
The H2S-rich gas is fed into a reaction chamber with 1/3 the stoichiometric volume of air required to burn it. Burners convert 1/3 of the H2S to SO2, which then reacts with the remaining H2S (in the presence of an alumina catalyst) to form elemental sulfur. The resulting product is cooled to condense to liquid sulfur.
The tail gas often contains small amounts of COS and CS2. To remove this, the tail gas is mixed with a small amount of hydrogen and carbon monoxide, heated, and reacted over a catalyst that converts the sulfur to H2S. This process is called the SCOT process. The H2S-rich gas can then be sent to the acid gas recovery plant and ultimately be recycled back into the sulfur plant as feed.