Bubble size distribution in a bubble column with vertical tube internals: Experiments and CFD-PBM simulations

Knowledge of bubble size distribution (BSD) is critical for controlling mass transfer and reaction in bubble column reactors. Installation of internals further complicates this issue. The effects of internals on BSD were systematically investigated through experiments and computational fluid dynamics-population balance model simulations. The experiments show a bimodal distribution of the volume-based BSD except at low superficial gas velocity of 0.01 m/s. Addition of 20% internals increases the small-bubbles fraction, making the first BSD peak more evident. Correspondingly, the simulation reveals a prominent decrease of turbulent dissipation rate and turbulent kinetic energy. Moreover, while the unresolved turbulent kinetic energy dominates in the empty columns, the resolved portion becomes the major component in the presence of internals. This suggests that internals may redistribute turbulent kinetic energy in each scale, which provides more insights into the complex flow characteristics in the presence of internals and process intensification.