Simulation of CO₂ Capture Process in Flue Gas from Oxy-Fuel Combustion Plant and Effects of Properties of Absorbent

Oxy-fuel combustion technology is an effective way to reduce CO₂ emissions. An ionic liquid [emim][Tf₂N] was used to capture the CO₂ in flue gas from oxy-fuel combustion plant. The process of the CO₂ capture was simulated using Aspen Plus. The results show that when the liquid– gas ratio is 1.55, the volume fraction of CO₂ in the exhaust gas is controlled to about 2%. When the desorption pressure is 0.01 MPa, desorption efficiency is 98.2%. Additionally, based on the designability of ionic liquids, a hypothesis on the physical properties of ionic liquids is proposed to evaluate their influence on the absorption process and heat exchanger design. The process evaluation results show that an ionic liquid having a large density, a large thermal conductivity, and a high heat capacity at constant pressure is advantageous. This paper shows that from capture energy consumption and lean circulation, oxy-fuel combustion is a more economical method. Furthermore, it provides a feasible path for the treatment of CO₂ in the waste gas of oxy-fuel combustion. Meanwhile, Aspen simulation helps speed up the application of ionic liquids and oxy-fuel combustion. Process evaluation helps in equipment design and selection.