Increase H_2S/CO_2 Selectivity With Absorber Interstage Cooling*

摘要

This paper presents a method for improving the H_2S/CO_2 selectivity in high CO_2 content,high CO_2:H_2S 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the absorber via interstage cooling.(The interstate cooling consists of two stages whereby the semi-lean solvent is withdrawn from an absorber chimney tray,pumped through a cooler and returned to the absorber.)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 H_2S/CO_2 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.