Heat and Mass Transfer Analysis to Predict CO2 Absorption Rate in Packed Column

Abstract

In present study, a three dimensional rate based model using two-film theory and Eulerian-Lagrangian approach is developed. The model is implemented within a multiphase and multi-component system of aqueous monoethanolamine solution in a randomly packed column. The influence of liquid flow rate, inlet liquid temperature, solution initial loading, pressure drop due to solid packing and pressure drop at gas liquid interface are considered. The gas phase is considered as continuous phase and liquid phase is considered as dispersed phase. The governing equations are solved in commercial package, which is based on finite volume method. Comparison of the results of present model, which is taking into account rates of mass transfer, heat transfer and chemical reaction, with the observations from previously reported works reveals the ability of present model as predictive tool and supports the validity of present modeling procedures. The solution initial loading and liquid flow rate are the major factors that affect the performance of absorption column. The simulated results show that absorption rate decreases with increasing CO2 loading in MEA solution due to corresponding reduction in free MEA available to react with absorbed CO2 and absorption rate increases along the column height due to increase in diffusivity and reaction rate with increasing temperature. The absorber performance increases at higher liquid flow rate than at lower liquid flow rate because at higher liquid flow rate the residence time of solution decreases in the column and more MEA is available to react with CO2.