Techno-economic feasibility and performance evaluation of replacing diglycolamine (DGA) with diethanolamine (DEA) in a dual-pressure gas sweetening unit: A comprehensive field case study

• Replacing imported DGA with domestic DEA cut annual solvent cost by ∼USD 152,000. • DEA increased LP absorber H 2 S removal by 34.5% and cut reboiler steam use by 9.6%. • DEA’s superior stability eliminated the energy-intensive reclaimer, saving 586 kW. • The switch reduces ∼590 tons of CO 2 emissions annually from steam savings. • Sensitivity analysis confirms robust annual savings exceeding USD 225,000. The removal of hydrogen sulfide (H 2 S) from refinery gas streams is essential for operational safety, environmental compliance, and equipment integrity. This study provides a comprehensive technical and economic evaluation of replacing diglycolamine (DGA) with diethanolamine (DEA) in a dual-pressure gas sweetening unit at the Tehran Oil Refining Company. Through a carefully managed solvent transition and continuous monitoring, DEA demonstrated superior performance. The use of DEA achieved a significant reduction in outlet H 2 S concentration, particularly in the low-pressure absorber, and simultaneously reduced steam consumption in the stripper reboiler by 9.6%. A key finding was the complete elimination of the energy-intensive reclaimer unit, which resulted in 100% energy savings for that reclaimer unit compared to its operation with DGA. Economically, the switch to DEA yielded approximately USD 152,000 in annual solvent cost savings and contributed to total annual savings exceeding USD 225,000. Additionally, DEA’s reliable domestic availability in Iran mitigates supply chain risks, establishing DEA as a technically superior, economically advantageous, and strategically resilient alternative to DGA for refinery gas sweetening applications.