(30e) New Strategies for Acid Gas Enrichment

Sulphur plant performance and capacity are greatly affected by feed gas quality. Thus, increasing the H₂S content of Claus plant feeds is needed when plant throughput is limited or the sour gas has too low an H₂S:CO₂ ratio for producing satisfactory acid-gas. The key to acid gas enrichment (AGE) is selectivity, and of the generic amines, N-methyldiethanolamine (MDEA) is the most selective. The FLEXSORB® family of hindered amines is even more selective; however, these solvent are more expensive than generics.  Recently, a new patented family of HIGHSULF™ amine-based desulphurization technologies and strategies was introduced in the literature. Among other applications, the HIGHSULF technology enhances the well-known SCOT or similar processes, uses identical equipment, requires almost no additional capital investment, and produces extremely high quality Claus feed with generic MDEA, or MDEA spiked with promoters. The beauty of HIGHSULF is its simplicity—any existing AGE or SCOT unit can be switched easily to HIGHSULF and back to conventional treating without shutdown. This paper uses the ProTreat™ process simulator to substantiate the technology and to discuss several cases of both the original and extended HIGHSULF process strategies. Attention focuses on using HIGHSULF with MDEA solvents to upgrade low-quality SRU feed and to produce high H₂S gas from the SRU’s TGTU amine section. FLEXSORB or other special solvent performance can be had using HIGHSULF with generic MDEA.