The Claus sulfur conversion process recovers up to 97% of the sulfur from acid gas streams. The Fluor hydrogenation/amine process converts sulfur dioxide (SO2), COS, carbon disulfide (CS2), elemental sulfur and other sulfur species in the Claus tail gas to hydrogen sulfide (H2S). The H2S is then removed via selective amine treating to achieve a total sulfur recovery efficiency of up to 99.99%.
Air and natural gas are combusted under substoichiometric conditions in a reducing gas generator (1). The hot combustion product reducing gases, carbon monoxide (CO) and hydrogen (H2), are mixed with the Claus tail gases in a mixing chamber (2) integral with the reducing gas generator. The cobalt molybdenum (CoMo) catalyst in the reactor (3) hydrogenates/hydrolyzes all the sulfur species in the gas mixture to H2S.
The hydrogenated tail gas is then cooled in the effluent cooler (4), generating steam in the process. The effluent gas is further cooled in a direct contact quench tower (5) to condense and remove water. The condensed water, which contains a small amount of H2S, is treated in a sour-water stripper where the H2S is removed and returned to the Claus unit. The Fluor design optionally uses a desuperheating section with an alkaline circulation to remove any potential SO2 breakthrough from the hydrogenation reactor. This design feature is especially useful when the downstream amine unit operates with an expensive proprietary amine.
After quench cooling, the hydrogenated tail gas is then treated by a highly efficient selective amine to remove H2S. In the absorber (6), the H2S is selectively absorbed in the amine while rejecting as much CO2 as possible. The rich amine solution is then regenerated in the stripper (7) and circulated back to the absorber. Acid gas from the stripper is recycled back to the upstream Claus unit. The process can achieve a total sulfur recovery efficiency of up to 99.99%
Licensor: Fluor Enterprises, Inc.,