CFD modeling of CO₂ capture in a packed column using amine-based nanofluids: Effects of Al2O3, SiO2 and TiO2 nanoparticles

CO₂ emissions are a critical environmental concern driving global climate change, particularly the rise in Earth's average temperatures. Therefore, reducing CO₂ release into the atmosphere is essential. One promising solution for capturing and removing CO₂ from industrial gas streams is the use of absorption columns with amine-based solutions. In this study, an amine absorption column in a petrochemical plant was investigated. The column consists of two sections with different diameters: The column’s upper section features a smaller diameter, while the lower section is broader. The column receives lean amine at its uppermost section, with semi-lean amine being fed where the diameter changes. Nanofluid solutions containing Al₂O₃, SiO₂, and TiO₂ nanoparticles were utilized. The flow rates of both amine streams were kept constant, while the inlet gas flow rates were set at 215, 161, and 140 tons per hour. Nanofluids with weight concentrations of 0.03, 0.05, and 0.1 wt% and particle sizes of 20, 50, and 80 nanometers were considered. The study focused on analyzing CO₂ concentration profiles along the column, mass transfer coefficient, absorption efficiency and pressure drop in the presence of amine and nanofluid solutions. Results show elevated gas velocities correlate with diminished CO₂ removal performance in all cases. Also, the numerical simulation results indicate that increasing wt% leads to higher CO₂ absorption efficiency and mass transfer coefficient. Furthermore, comparison between nanoparticles of different sizes shows that smaller particles exhibit better performance.