CO2 chemical absorption from fluid catalytic cracking unit flue gases of Abadan Oil Refinery in Iran, using diethanolamine solvent
2020
Sisakht, Nader Nikeghbali | Rouzbahani, Maryam Mohammadi | Karbasi, Abdolreza | Zarinabadi, Sorosh | Sabzalipour, Sima
The Fluid Catalytic Cracking Unit process converts heavy vacuum gas oil into more valuable products in the presence of zeolite catalyst at 520 °C and 2.5 bar. The coke is burned off with air in the regenerator tower at 700 °C and 230 ton / h of flue gases are produced. The flue gases consist of CO₂ (12.7% mole), N₂ (66.2% mole), H₂O (19.2% mole), O₂ (1.7% mole), and SO₂ (0.2% mole). In this study, the chemical absorption of CO₂ in an absorption and desorption pilot plant was investigated and this process was simulated by Aspen Hysys. The pilot plant used has an absorber tower of 15 cm in diameter and a stripper tower of 10 cm. The towers were filled up to 1.5 m with 3-mm Raschig ring packing. A concentration of 30 wt% diethanolamine (DEA) solvent is used for CO₂ absorption. Absorption was carried out at 1.1 bar, solvent temperature of 40 °C, flue gas temperature of 60 °C, and liquid to gas ratio (L/G = 3.7). Amine regeneration was carried out at 125 °C and 1.9 bar. The CO₂ absorption efficiency in the pilot plant was obtained 96% and in Aspen Hysys simulation its 95%. The CO₂ recovery efficiency in the stripper tower obtained 95% and CO₂ purity is 94.6%. The overall efficiency of the chemical absorption with this process is 92%, and the regeneration energy in the stripper tower is 2.52 GJ/ton-co₂. With this method, 1003 ton/day CO₂ is captured from the FCCU flue gases and preventing emission to the atmosphere.
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