Investigations on transport behaviours of rotating packed bed for CO2 capture by chemical absorption using CFD simulation

A rotating packed bed (RPB) has been proposed to overcome the limitations of high operating and capital costs involved in conventional columns which are used for chemical absorption-based carbon dioxide (CO₂) capture. The design of large-scale RPBs depends on their transport characteristics. Owing to the difficulties in predicting the transport characteristics of RPBs experimentally, Computational Fluid Dynamics (CFD) simulation has been implemented. In this study, a two-dimensional (2D) volume of fluid (VOF) simulation is conducted to predict transport characteristics of RPB including, hydrodynamics, and physical and reactive mass transfers. To predict hydrodynamics of RPBs accurately, the liquid holdup by CFD simulation is compared against experimental prediction, showing a strong agreement between simulation and experimentation. Various liquid phase flow patterns within RPB are observed and these are cross-referenced with findings in the existing literature. Additionally, the impacts of rotational motion and flow rate are further assessed in the study. For the mass transfer performance, the prediction of the volumetric mass transfer coefficient, k_La_e of the air-water system from CFD simulation is studied. Two different mass transfer theories such as surface renewal theory and penetration theory are studied to predict k_La_e. It is observed that the k_La_e from the penetration theory closely follows the trend of the experimental data. Finally, a 2D simulation of the reactive absorption of CO₂ by diethylenetriamine (DETA) in RPB is developed and compared with the existing available data in the literature. The present model underpredicts CO₂ capture efficiency in RPB, which needs further improvement in reaction kinetics. In general, the present CFD model has the capability of predicting the transport characteristics of RPB.