Increase H2S/CO2 Selectivity With Absorber Interstage Cooling

摘要

This paper presents a method for improving the H2S/CO2 selectivity in high CO2 content, high CO2:H2S ratio gas treating applications using MDEA. This work shows that significant improvements in the selectivity of the MDEA solvent can be attained by removing heat from the absorber via interstage cooling. (The interstate cooling consists of two stages whereby the semi-lean solvent is withdrawn from an absorber chimney tray, pumped through a cooler and returned to the absorber.) This interstage cooling, combined with additional lean solvent cooling, allows enough improvement in the H2S/CO2 selectivity so that the required heat removal can be accomplished with a conventional cooling water medium. In contrast, if only the lean solvent is cooled, an equivalent improvement in performance will require a much colder cooling medium, such as a refrigerant. The work was co-developed by Shell Global Solutions, Motiva Enterprises, and Black & Veatch in a study at Motiva's Delaware City Refinery.