COSWEETTM: A New Process to Reach Very High COS Specification on Natural Gas Treatment Combined with Selective H2S Removal

Abstract

COSWEETTM, developed for the treatment of COS containing natural gases, is based on a combination of deacidification with any alkanolamine solution and COS hydrolysis on a metal oxide based catalyst. Nearly complete COS conversion is reached, even at a relatively low operating temperature. Coupled with a classical sweetening unit, in which an adapted alkanolamine solvent is used in order to optimise the removal of H2S, CO2, as well as the H2S/CO2 selectivity, the high catalyst activity and the original integration of the scheme secure the COS removal at minimum extra cost. Benefits on capital and operating expenditures of the plant result both from the reduction of the absorption column and solvent flow rate and from the quality of the acid gas which has positive consequences on the design of the sulfur recovery facilities units, including Claus unit. This paper presents the complete development process approach and the results obtained on COS conversion, the model and simulation tool as well as a case study showing the advantages of coupling COSWEETTM to amine based solvent.