3D modeling of hydrodynamics and physical mass transfer characteristics of liquid film flows in structured packing elements

Post-combustion CO₂ capture by chemical absorption in structured packed columns has been technically and commercially proven as a viable option to be deployed for carbon emissions mitigation. In this work, a three dimensional CFD model at small scale for hydrodynamics and physical mass transfer in structured packing elements is developed. The results from the present model are validated with theory and reported experimental data. For hydrodynamics, the liquid film thickness and wetted area are calculated whereas for mass transfer, the Sherwood number and concentrations of dissolved species are predicted. The CFD results match reasonably with experimental and theoretical data. Furthermore, the influence of texture patterns and the liquid phase viscosity on the wetted area is studied. It is found that both parameters have a strong influence on the results. For physical mass transfer, the study of the transient behavior and the impact of the liquid load on the absorption rate is assessed. It is observed that lower liquid loads maximize mass transfer coefficients but also enhance liquid misdistribution (i.e. with the possibility of hindering mass transfer). An optimum liquid load is found where the effect of liquid misdistribution can be avoided, maximizing gas absorption.