DOI: 10.11648/j.ogce.20261404.12 ISSN: 2376-7677

Simulation of an Acid Gas Cleaning Plant Using a Modified Absorbent (Sulfolane+Diisopropanolamine)

Manger Yilaga, Kenneth Dagde, Emmanuel Ehirim, Jaja Zina
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The removal of acid gases, particularly carbon dioxide (CO 2 ) and hydrogen sulfide (H 2 S), from natural gas streams is essential for meeting product specifications, preventing equipment corrosion, and complying with increasingly stringent environmental regulations. Conventional acid gas treatment processes commonly employ either chemical or physical solvents; however, these systems often suffer from limitations such as high energy consumption, reduced absorption efficiency, and increased operating costs. This study investigates the performance of a modified absorbent system comprising Sulfolane and Diisopropanolamine (DIPA) for acid gas removal using Aspen HYSYS simulation software. A rigorous process model consisting of an absorber and solvent regeneration unit was developed based on mass and energy conservation principles. The Peng-Robinson equation of state was employed to accurately represent the thermodynamic behaviour of the gas-liquid system. The simulation results were validated against published literature data using key performance indicators including overall acid gas removal efficiency, CO 2 removal efficiency, H 2 S removal efficiency, lean solvent purity, rich solvent loading, and reboiler duty. The developed model demonstrated excellent agreement with literature values, with deviations below 5%, confirming its reliability for performance evaluation and process optimization. Comparative analysis was carried out for DIPA, Sulfolane, and a combined Sulfolane-DIPA solvent system. The results revealed that the hybrid solvent exhibited superior performance, achieving an overall acid gas removal efficiency of 94%, compared to 88% and 90% obtained for DIPA and Sulfolane, respectively. Similarly, the blended solvent achieved the highest CO 2 removal efficiency (85%), H 2 S removal efficiency (90%), lean solvent purity (98.5%), and rich solvent loading (0.22 mol/mol), while simultaneously requiring the lowest reboiler duty of 385 kW. These findings indicate a synergistic interaction between the chemical absorption capability of DIPA and the physical absorption characteristics of Sulfolane. An economic assessment was also conducted to evaluate solvent-related operating costs. Although the combined solvent system incurred a higher annual solvent cost than the individual solvents, the enhanced acid gas removal performance and lower regeneration energy requirement suggest that the additional expenditure may be justified in applications requiring stringent gas quality specifications. The study demonstrates that the Sulfolane-DIPA blend offers a technically effective and energy-efficient alternative for industrial acid gas treatment and provides a valuable framework for future optimization and scale-up studies.

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