IMPROVED PROCESS FOR TREATING H2S-LEAN STREAMS WITH RECYCLE OF SOx FROM BURNER

摘要

This invention is directed to an improved process for conversion of H2S to sulfur, using MOST (Mobil Offgas Sulfur Treatment) catalyst or sorbent. The sorbent is typically a magnesium-aluminate spinel, with oxidation promoters such as ceria and vanadia. H2S from the feed gas is used to regenerate sulfated sorbent, simultaneously producing elemental sulfur which is then condensed out. The improvement involves recycling a portion of the effluent from a downstream burner to mix with the feed to the sorbent. Thus some of the stoichiometric oxygen required for conversion of H2S to S is supplied in the form of SO2 by this pre-combustion step, instead of coming totally from the oxidized/sulfated solid sorbent. This can decrease the amount of sorbent required, as well as the frequency of regenerations, thus reducing process cost. The hot recylce gas also helps to heat the feed stream.