LAUSR

Abstract The high pressure absorption of carbon dioxide (CO2) from a distilled ethane stream at Phase 19 of South Pars Gas Complex (in Iran) has been simulated by Aspen Plus using non-random two-liquid and Peng-Robinson models in addition to the technical and operational data. The plant employs 40 wt% diethanolamine (DEA) solution as the actual absorbent in a conventional column. The potential single and blended absorbents including methyldiethanolamine (MDEA), piperazine (PZ) + MDEA, and DEA + MDEA have been modelled to estimate the outlet CO2 and sulfur compounds concentrations, CO2 loading, reboiler power supply and regeneration heat duty to determine the most efficient substitute. The model is in good agreement with the real data of the plant. The rate-based simulation results reveal that CO2 and H2S concentrations have nearly reached zero while the total sulfur content is below the demanded specification (10 ppm wt) by the application of a blended amine solution with a low PZ concentration as 1 wt% PZ + 39 wt% MDEA in the operational limits of 110–120 ton/hr and 40–55 °C , suggesting that the PZ + MDEA solution can be used as the most appropriate alternative to the 40 wt% DEA solution due to the higher CO2 concentration (1.950% mole) and CO2 loading (0.216) of the rich solution as well as the lower required regeneration heat duty (10.590 GJ).