Process for reducing the sulfur content in flue gases of a sulfur production unit

摘要

In a process of decreasing the sulfur content of exhaust gases obtained during the recovery of sulfur from acid gases containing H2S and other S-containing compounds in the Claus process, the acid gases which contain H2S and other S-containing compounds are reacted in a Claus plant to form elemental sulfur. A gas which contains H2S or SO2 is subsequently added at a controlled rate to maintain a stoichiometric ratio of 2:1 of H2S to SO2 in the tail gas from the Claus plant. The gas which contains H2S or SO2 may be added to the tail gas from the Claus plant or before the last contacting stage of a multistage Claus plant. During the addition of a gas which contains H2S, the Claus plant can be operated at an H2S to SO2 ratio of or below 2:1. During the addition of a gas which contains SO2 the Claus plant can be operated at an H2S to SO2 ratio of or above 2:1. The H2S and SO2 contained in the tail gas are chemically reacted to form elementary sulfur in a tail gas-desulfurizing plant and the sulfur is withdrawn.