The carbon dioxide (CO2) emission reduction technology has the limitation of high energy consumption, and the development of new and efficient capture media is a new way to achieve green and high-value utilisation of CO2. However, ionic
liquids (ILs) have attracted the attention of researchers as a novel capture medium. In this study, Aspen Plus software was
used to examine the process of capturing CO2 from flue gas of coal-fired power plants using ILs. The physical properties
of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) were analysed using known experimental data, and a
process flow for physical absorption of CO2 was established. Based on the established full process model, a sensitivity
analysis was conducted on the absorption tower and flash tank. The process simulation results showed that increasing
the number of absorption tower plates and the lean liquid flow rate benefits CO2 absorption. The optimised absorption
pressure is 3.0 MPa, the number of trays is 15, the lean liquid absorbent flow rate is 500 kmol/hr, the lean liquid feed temperature is 50°C, and the optimal operating conditions for the flash evaporation tank are a recovery pressure of 0.3 MPa
and a recovery temperature of 150°C. The calculation of direct equipment investment cost in the process shows that with
the increase of lean liquid load, the investment cost of all equipment except for the reboiler increases.