Integrated UCAP (Union Carbide Alkanolamine Process). a new approach to sulfur recovery

Based on the high SO/sub 2/ adsorption capacity, exceptional selectivity for SO/sub 2/ over CO/sub 2/, up to 90Vertical Bar3< stage efficiency of adsorption, and strong inhibition of SO/sub 2/ oxidation exhibited by aqueous triethanolamine in experimental studies, Union Carbide Corp. has developed the UCAP SO/sub 2/ adsorption process, which can be used in desulfurization of refinery streams, flue gas from heaters and boilers, and sulfuric acid plant tail gas. Integrated with a single catalytic Claus reactor, UCAP makes it possible to treat streams very low in H/sub 2/S, for which the Claus process alone is uneconomical, and reduce the SO/sub 2/ level in the plant tail gas to Vertical Bar3; 50 ppm, even when the Claus unit has only 75Vertical Bar3< per pass sulfur yield. The first commercial integrated UCAP unit has been built at Gulf Oil Co.'s Venice, La., refinery. The new process also permits economical recovery of high-quality sulfur from acid gases of oil refineries, natural gas sweetening, coal gasification, or SNG plants, with very low H/sub 2/S/CO/sub 2/ ratio. The CO/sub 2/-free SO/sub 2/ regenerated from the solvent can be recycled to a Claus unit, converted to sulfuric acid, or recovered directly as salable liquid by-product.