| abstract |
A method and system for removing hydrogen sulfide from a hot gas. In a moving bed absorber, sulfur compounds in the hot gas moving in a direction which is countercurrent to the direciton of movement of the movable bed of metal oxide, react with metal oxide to form metal sulfide. The metal sulfide is regenerated to re-usable metal oxide in a moving bed regenerator. The regeneration is carried out with an oxygen-containing gas in which regenerator off-gas serves as a diluent to control oxygen concentration. In the regenerator, spent metal sulfide moves progressively through a single regeneration vessel having first, second and third regeneration stages. In the first and second regeneration stages, first and second oxygen and sulfur dioxide-containing gases move, respectively, in a direction which is cocurrent with the direction of movement of a movable bed of spent metal sulfide. In the third regeneration stage, an oxygen-containing gas moves in a direction which is countercurrent to the direction of movement of the movable bed of metal sulfide from the second regeneration stage. The combined gases derived from the first, second and third regeneration stages and which are rich in sulfur dioxide and lean in oxygen, are removed from the regenerator as off-gas and used as diluent with air, oxygen-enriched air or pure oxygen to provide the low oxygen concentration in the oxygen-containing gas introduced into the first and second regeneration stages. |