Removal of by-products in method for processing a gas containing hydrogen sulfide and sulfur dioxide

• Main Authors: LECOMTE FABRICE, STREICHER CHRISTIAN, BARRERE-TRICCA CéCILE
• Format: Patent
• Language: English
• Published: 28.08.2001
• Edition: 7
• Subjects: CHEMISTRY; COMPOUNDS THEREOF; INORGANIC CHEMISTRY; METALLURGY; NON-METALLIC ELEMENTS; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TRANSPORTING

A method for processing a gas, such as a Claus tail gas, containing at least hydrogen sulfide (H2S) and at least sulfur dioxide (SO2), includes the steps of contacting the gas with a liquid solvent, such as polyethylene glycol, containing at least one catalyst, such as sodium salicylate, in a contacting stage, recovering gaseous effluent substantially containing no hydrogen sulfide and no sulfur dioxide from the contacting stage, and separating liquid sulfur from liquid solvent in a decantation zone beneath the contacting stage. In order to remove by-products, such as sulfate and thiosulfate salts, resulting from degradation of the catalyst, a liquid fraction F containing at least solvent, catalyst, sulfur and the solid by-products resulting from degradation of the catalyst is extracted from the contacting stage and sent to a processing stage distinct from the contacting stage where the liquid fraction F is heated to a temperature sufficient to at least partially crystallize the by-products, and the crystallized by-products are separated from the rest of the liquid fraction F containing at least solvent. At least a stream F1 comprising solvent, catalyst and sulfur and substantially free of the by-products and a stream F2 mostly comprising the by-products are recovered.