Exergy study of amine regeneration unit for diethanolamine used in refining gas sweetening: A real start-up plant

Abstract Diethanolamine (DEA) solutions are used in refineries to sweeten gas. DEA is responsible for absorbing H2S from sour gas. In an Amine Regeneration Unit (ARU), the rich amine with H2S is regenerated. A refining column in the Middle East started commercial production in 2020. Using Aspen HYSYS V.11, an amine regeneration unit in the refinery that supplies lean amine to the delayed cooker unit for gas sweetening was simulated, and an exergy study was performed on various equipment. Exergy is destroyed in an irreversible process, while energy is converted from one type to another. The sum of the physical and chemical exergy is the total exergy. The chemical exergy was calculated using a series of equations embedded in Excel, while the physical exergy was calculated using HYSYS. The DEA concentration used is 25 wt%. Each equipment's exergy destruction rates, destruction efficiency, and percentage share of destruction were determined. The regenerator had the highest destruction rate of 2144.11 kW and an 80.21 percent share of total destruction. With a value of 326.00 kW and a percentage share of 12.20 percent of total destruction, the air cooler has the second-highest exergy rate. Exergy has a 99.70 percent overall efficiency. Due to system losses, the DEA concentration fell from 25% to 20% of the design value. The regenerator had the highest destruction rate of 2616.74 kW followed by the air cooler with a value of 294.61 kW. In DEA 20%, an exergy analysis was carried out. Exergy research showed the same percentage share distribution for equipment at a concentration of 20 DEA wt. percent. To find related equipment relationships, the results of the unit's exergy analysis were compared to those of another ARU exergy study at the same refinery plant. The regenerators were found to have the highest exergy destruction of the two units with a percentage share of the overall destruction reaching 80% followed by the air coolers with values reaching 9%.