Simulation and comparison of Sulfinol solvent performance with Amine solvents in removing sulfur compounds and acid gases from natural sour gas

• Different solvent alternatives has been studied for Ilam gas refinery in Iran.
• New gas processing plants presented using different mixtures of solvents.
• 35–50% reduction in solvent circulation for new plant with Sulfinol process.
• 10–25% lower energy consumption for plant using Sulfinol process.
• Higher selectivity of H2S in absorption when Sulfinol-M used as a solvent.

Natural gas issued from well production has to be treated to remove acid gases (CO2 and H2S) and sulfur compounds so that it meets transport requirements and sale gas specifications. Two great families of solvents are used for this kind of gas treatment: chemical and physical solvents. Ilam gas refinery (one of the main gas refineries in Iran) discharges high levels of mercaptans in the production of raw LPG and condensates, and also there are problems with sulfur compounds because of the lack of Merox unit. In this research, we carry out the simulation and study of removing acid gases (CO2, H2S) and sulfur compounds (methyl and ethyl mercaptans, dimethyl-sulfide, COS) with mixed solvent Sulfinol (Sulfolane + MDEA + H2O) and DGA, MDEA + AMP solvents and compare it with the present solvent MDEA. The purpose of this research is the feasibility study of utilizing Sulfinol-M solvent to replace the aqueous amine solvent in the gas sweetening unit of Ilam gas refinery. The results of the simulation show that more than 30–40% of mercaptans along with sour gas is absorbed with Sulfinol-M solvent of lower flow rate and a considerable 10–25% less energy is required for solvent regeneration; furthermore, very little waste of solvent is observed compared with amine solvents (MDEA + AMP, DGA, MDEA). Many of the process parameters are controlled more easily than amine solvents with the characteristic of the composition of Sulfinol-M compound and there will be energy and economic saving in different sections of mercaptan and acid gas absorption.