Dynamic modelling based on surface renewal theory, model validation and process analysis of rotating packed bed absorber for carbon capture

Abstract

Rotating packed beds can reduce the equipment size and costs in solvent-based carbon capture. However, difficulties are encountered when modelling rotating packed beds due to turbulent fluid flows inside rotating packed beds and the cross-sectional area of mass transfer unit that changes with radius. This study aims to develop a validated dynamic model of a rotating packed bed absorber and to carry out process analysis through steady state and dynamic simulations. Innovatively, the dynamic model was developed based on surface renewal theory for mass transfer. The model can calculate distributed mass transfer coefficients and other key variables related with absorption performance. Experiments were carried out and new experimental data for the rotating packed bed absorber under realistic operating conditions were obtained for model validation. Process analysis about the effects of key operational variables such as rotating speed, liquid-gas ratio and solvent concentration on absorption performance was performed with benchmark MEA solvent. It was found that the optimal MEA concentration is around 70 wt%. Dynamic simulation results reveal that the RPB absorber has fast responses for process changes. This new distributed dynamic model and the insights obtained through process simulation will promote rotating packed bed technology towards its industrial deployment in large scale carbon capture processes.