Modeling and Mass Transfer Mechanism of CO₂ Capture by Membrane Absorption from Iron and Steel Blast Furnace Gas

A process simulation model for CO₂ capture using a hollow fiber membrane absorber was developed to address the CO₂ capture requirements of blast furnace gas in steel plants. Key factors influencing membrane absorption performance were systematically investigated. The model integrated mass transfer, energy balance, reaction kinetics, and membrane wetting mechanisms. Aspen Custom Modeler was utilized to simulate the effects of absorbent temperature and blast furnace gas temperature on CO₂ removal efficiency, with comparisons to conventional absorption processes. Results demonstrated that increasing the absorbent temperature from 10 ℃ to 80 ℃ led to a significant decrease in CO₂ removal efficiency from 92.8% to 83.1%, primarily due to intensified membrane wetting (maximum wetting degree reaching 74.68%) and a shift of the absorption reaction equilibrium toward the reverse direction. When the gas temperature increased from 10 ℃ to 80 ℃, membrane absorption efficiency also declined markedly from 88.2% to 75.5%, attributed to enhanced gas-phase diffusion rates that weakened liquid-phase mass transfer. Simulation of membrane wetting behavior revealed a significant increase in wetting degree with rising absorbent temperature, which gradually increased along the absorber axis and stabilized after reaching a peak. This study elucidates the constraining mechanism of the synergistic effects of absorbent and gas temperatures and membrane wetting on mass transfer efficiency, confirming the advantages of membrane absorption under low-temperature conditions and providing a theoretical foundation for process optimization and industrial scale-up.