US Patent 7635408 Methods and configurations for acid gas enrichment

Hydrogen sulfide is selectively enriched from an acid gas (1) that comprises relatively large quantities of carbon dioxide using a configuration in which a portion of an isolated hydrogen sulfide stream is introduced into an absorber (51) operating as a carbon dioxide rejecter. The resulting concentrated hydrogen sulfide enriched solvent (4) is then further used (directly or indirectly) to absorb hydrogen sulfide from an acid feed gas.