Simulated exergy and energy performance comparison of physical-chemical and chemical solvents in a sour gas treatment plant

A feasibility simulation study evaluates the utilization of the physical-chemical solvent Sulfolane plus Methyl di-ethanol amine (MDEA) plus H2O (Sulfinol-M), to replace the aqueous amine solvent (MDEA) currently used in the sour-gas treatment unit of the large-scale Khangiran gas processing plant (Iran). Physical-chemical solvents, such as Sulfinol-M, have the advantages over chemical solvents in that: (1) their absorption of pollutants is not limited by their stoichiometry; (2) they can be easily regenerated by reduction of pressure alone; and, (3) they demonstrate a strong capability to remove sulphur compounds. The simulation and exergy analysis of this gas treatment plant compare the performance of the currently used MDEA solvent with the Sulfinol-M solvent in various concentrations. The influences of different parameters, including inlet solvent temperature, composition and flow rate of solvents on the removal of H2S and CO2, together with associated exergy and energy losses are evaluated for the MDEA solvent and a range of concentrations of the Sulfinol-M solvent. The simulated exergy analysis demonstrates suitable absorption of acid gases by the Sulfinol-M solvent for less energy and cost than the MDEA solvent.