Hydrogen sulfide removal from coal gasification

COMBISULF A process for removing sulfur compounds from the gases from combined-cycle power plants with integrated coal gasification. Carbonyl sulfide is removed by catalytic hydrolysis hydrogen sulfide is removed by selective absorbtion in aqueous MEDA and the sulfur is recovered from both processes by a modified Claus unit. Developed by Krupp Koppers and first operated in Spain in 1996. See PRENFLO. 

Many processes have been developed for the removal of hydrogen sulfide from gas streams. They can be classified as liquid absorption, liquid oxidation, dry oxidation, and adsorption. One of these processes is usually included in a coal gasification or liquefaction flowsheet since the coal sulfur is converted to H2S and finally elemental sulfur. The Stretford and Townsend direct HpS to S processes and the Recti sol process followed by a Claus plant are frequently included on coal conversion flowsheets (1 ). Kohl and Riesenfeld (2) present pertinent details for many commercial processes. 

Acid Gas Components. The oil and gas industries have a long history of effectively removing and processing carbon dioxide, hydrogen sulfide, and carbonyl sulfide, (collectively termed acid gases because they are acidic) from fuel gas streams. It is common to remove H2S and CO2 from raw natural gas before the gas enters the natural gas pipeline system. In coal gasification, a portion of the feed coal converts to CO2. 

When the feed to a synthesis operation is derived from the gasification of coal or heavy oil rather than from the reforming of natural gas, it will normally contain COS as well as H2S. If hydrogen sulfide is removed from the gas and the gas is then passed through a shift conversion catalyst, the COS will be converted to H2S (at approximately its equilibrium concentration), and the H2S produced can then be removed in a later step. On the other hand, if the gas... 

---