CFD simulation of a slurry bubble column: Effect of population balance kernels

In this work, CFD simulations of a slurry bubble columns were performed and validated with experimental data. The superficial gas velocities investigated in the experiments were 5 cm/s and 8 anis for a solid loading varying from 7% to 14% in a 0.14 m to 0.26 m internal diameter column. A population balance model (PBM) was implemented and solved numerically using the bubble class method. The closure kernels involved Luo's coalescence model as well as two different breakup model: Luo's and Lehr's models. The kinetic theory of granular flows (KTGF) was used to calculate the local solid viscosity. The Eulerian framework was selected for multi-phase calculations and the interphase momentum transfer for gas-liquid included drag, lift, and turbulent dispersion terms. The liquid-solid interphase involved both drag and turbulent dispersion terms. Results showed that: (a) A combination of the Luo coalescence and Luo breakup kernels (Luo-Luo) can predict similar trends for the radial profile of solid axial velocity with regards to experiments. However, at the highest superficial gas velocity in the small column, a discrepancy was observed in the results. (b) A combination of the Luo coalescence and Lehr breakup kernels (Luo-Lehr) predicted similar trends for the solid velocities when compared to empirical data, however, this combination also showed discrepancy at the highest superficial velocity tested in the small column. (c) The total gas holdup in the Luo-Luo and Luo-Lehr models are under and over predicted respectively when compared with the experimental results. (d) The mesh sensitivity results showed that a 3 mm mesh size is realistic to capture the flow fields. (e) The sensitivity analysis of the number of bubble classes showed that the radial profiles were independent to a number of bubble classes. However, the highest number of classes cover the formations of the largest bubbles. (C) 2018 Elsevier Ltd. All rights reserved.