Simulation study on the flow and mass transfer processes of CO₂ absorption by co-current flow of amine droplets and microbubbles

Chemical absorption is a well-established technology for CO₂ capture, and enhancing absorption is an effective strategy for improving capture efficiency. This study proposed a novel multiflow reactor that integrates droplets and microbubbles. A mathematical model was developed to simulate the co-current absorption of CO₂ using amine droplets and microbubbles, and the flow and mass transfer characteristics of this configuration were analyzed under various operating conditions. The results demonstrated that larger droplets are less affected by the co-current gas flow, while smaller droplets are more influenced by it. As the column height decreases, the proportion of larger droplets increases, while the fraction of smaller droplets diminishes. Reducing the microbubble diameter increases the gas–liquid interfacial area, significantly enhancing CO₂ removal efficiency. Although the liquid holdup of microbubbles has a minimal effect on the absorption rate, it influences the overall capture efficiency. The spray system achieved removal efficiencies of 87.56 % and 85.01 % at CO₂ concentrations of 10 vol% and 15 vol%, respectively, within an 8-meter height range. Additionally, the total CO₂ removal efficiency exceeded 90 % when the microbubble system was connected in tandem at distances of 1 m, 3 m, and 5 m from the nozzle. This study provides theoretical insights for the design and optimization of multiflow absorption columns that couple droplets with microbubbles.