Comparison of equilibrium and non-equilibrium models of a tray column for post-combustion CO2 capture using DEA-promoted potassium carbonate solution

In this study, the equilibrium and non-equilibrium models for CO2 absorption from natural gas stream by DEA-promoted potassium carbonate solution in a tray column were developed and compared with each other. The Electrolyte NRTL thermodynamic model was utilized to calculate the activity coefficient in the liquid phase, and the SRK equation of state was used for the gas phase. The non-equilibrium model was based on the two-film theory, and the effect of film discretization was examined. The equilibrium model was based on the theoretical number of stages combined with the concept of Murphree efficiency from 0.1 to 0.3 for three stages in the lower section of the column and 0.4 from stage 4 onwards. A thermodynamic study was performed to describe the equilibrium behavior of the solvent. All the necessary reactions in the liquid phase were considered in all simulations. The models were validated by comparing the obtained results with the published experimental data. Results of absorber column simulation show that the non-equilibrium model gives a better prediction of the temperature and concentration profiles as compared to the equilibrium model.