Characteristics of liquid flow in a rotating packed bed for CO2 capture: A CFD analysis

- A 2D CFD model is built using a fine grid to resolve the liquid flow in an RPB.
- The model predictions are in reasonable agreement with observations.
- On increasing the MEA concentration, the degree of liquid dispersion decreases.
- High rotational speed decreases the holdup and increases the liquid dispersion.
- At a high contact angle, more liquid droplets are formed but holdup decreases.

Rotating packed beds (RPBs) have been proposed as an emerging technology to be used for post-combustion CO2 capture (PCC) from the flue gas. However, due to the complex structure of the packing in RPBs, characteristics of the liquid flow within RPBs are very difficult to be fully investigated by experimental methods. Therefore, in this paper, a two-dimensional (2D) CFD model has been built for analysing the characteristics of liquid flow within an RPB. The volume of fluid (VOF) multiphase flow model is implemented to calculate the flow field and capture the interface between the gas and liquid phases in the RPB. The simulation results show good agreement with the experimental data. The distinct liquid flow patterns in different regions of an RPB are clearly observed. The simulation results indicate that increasing the rotational speed dramatically decreases the liquid holdup and increases the degree of the liquid dispersion. The increasing liquid jet velocity decreases the liquid residence time but slightly increases the liquid holdup. In addition, the liquid holdup increases and the degree of the liquid dispersion decreases with increasing MEA concentration, but the effects are weaker at a higher rotational speed. With the increasing of the contact angle, both the liquid holdup and the degree of the liquid dispersion are reduced. This proposed model leads to a much better understanding of the liquid flow characteristics within RPBs.