Persian Gulf University Journal of Oil, Gas and Petrochemical Technology 2383-2770 12 2 2025 10 01 Optimal solvent definition for gas treatment units with the aim of acid gas enrichment 67 79 239127 10.22034/jogpt.2025.513545.1137 EN Mohammad Amin Tarokh Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran Mehdi Karimi Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran 0000-0002-0063-5431 Ali Garmroudi Asil Department of Chemical Engineering, Faculty of Engineering, Bojnord University, Bojnord, Iran Journal Article 2025 03 22 Increasing the concentration of H2S in the acid gas entering the sulfur recovery unit is one of the key parameters for enhancing the sulfur recovery efficiency. This research aims to determine the optimal solvent for a gas treatment unit with a focus on enriching hydrogen sulfide gas in the feed of the sulfur recovery unit. The data from the design of an industrial-scale gas-treating unit was utilized to achieve the research objectives. For simulation, analysis of results, and plotting graphs, ASPEN-HYSYS V11 and DESIGN EXPERT V10 software were employed, respectively. The solvents available in the GPSA handbook were utilized for the solvent and additives selection. In the formulation of a composite solvent, DEA and MDEA solvents were considered as the base solvents, considering the weight percentage range used in the gas processing industry, and other solvents were considered as additives to the composite solvent. Simulation results were analyzed by comparing them with the standards of the Iranian National Gas Company. The results indicated that the combination of MDEA with 42.5wt% as the base solvent and Sulfolane with 7.5wt% as an additive will be the optimum solvent. The reason for this selection is that there will be the maximum H2S concentration in the acid gas while adhering to the mentioned standards. The optimum solvent can increase the concentration of H2S from 33.6 mol% to 41.84 mol% in the acidic gas to the Sulphur recovery unit. https://jogpt.pgu.ac.ir/article_239127_cd8a97015b6894707d6737cf993789a0.pdf