A study of hydrodynamics and interfacial momentum exchange terms in cylindrical bubble column by CFD

Flow fields and bubble size distribution are two critical issues in the determination of mass transfer and reaction rate in bubble columns. In this work the hydrodynamics of bubble driven flow was investigated in a laboratory scale cylindrical bubble column. The column was a semi batch reactor which was initially filled with tap water and only gas was evenly fed to the column from the bottom with different flow rates. The simulations were carried out by using Eulerian-Eulerian multiphase approach in ANSYS CFX-10. Population balances for different discretized bubble size groups were solved by using the MUSIG model and by considering the Prince and Blanch (1990) and Luo and Svendsen (1996) models for coalescence and breakage models, respectively. Proper interfacial momentum exchange closures were found by comparing the simulation results with experiments. The simulated time averaged liquid, slip and bubble velocity distributions in the column accompanied by turbulent kinetic energy distribution were validated by experimental data obtained by Particle Image Velocimetry (PIV) measurements in the same conditions. Moreover, the validated models were used to predict gas hold up, bubble size and interfacial area distribution for the same column. The effect of the inlet superficial gas velocity on simulations was also investigated.