Recovery of sulfur from hot gas desulfurization processes

Abstract

High-temperature desulfurization processes, which are being developed by METC, utilize regenerable mixed-metal sorbents, such as zinc ferrite, to remove reduced sulfur compounds from coal gasifier gases. In order to meet environmental regulations and to assure the successful development of an economical hot gas desulfurization process using regenerable sorbents, the regenerator off-gas must be treated to convert most of the SO{sub 2} to a more environmentally acceptable form of sulfur, such as elemental sulfur. The present study, which is the subject of this report, has been directed at developing techniques for this conversion. Two concepts for the conversion SO{sub 2} in the regenerator off-gas to elemental sulfur were addressed in this study. In the first concept, which was considered in the first and second years of this study, the SO{sub 2} in the off-gas is adsorbed onto a sorbent at 550 to 700{degrees}C. The sulfated sorbent is then regenerated using a reducing gas to produce an H{sub 2}S-rich gas suitable for the recovery of elemental sulfur in a Claus unit. In the second concept, which was studied in the second and third year of the contract, a near stoichiometric mixture of off-gas and reducing gas is reacted in the presence ofmore » a catalyst at 550 to 700{degrees}C to produce elemental sulfur directly in one step. 23 refs., 18 figs., 27 tabs.« less