Numerical comparison of gas‐liquid bubble columns and gas‐solid fluidized beds

Abstract

This paper investigates the degree of similarity between fluidized beds and bubble columns based on Eulerian-Eulerian two-dimensional simulations of an air-water bubble column and an air-FCC fluidized bed. Predictions for both systems are compared with available hydrodynamic experimental data, i.e. bed expansion, local axial velocity, local gas hold-up, and wall pressure fluctuations at different heights and for different gas velocities. Dynamic characteristics of the simulated pressure fluctuations are compared with measured fluctuations. The local gas holdup in the bubble column and bubble volume fraction in the fluidized bed are qualitatively analogous and, to a lesser degree, quantitatively similar. It is also demonstrated that the liquid and solid velocities are distributed in similar manners. The mean bubble diameters in the bubble column and fluidized bed are more similar at low gas velocities than at higher gas velocities. Frequency spectra of the fluidized bed and bubble column reveal differences and similarities related to the liquid and solid properties. The outcome of this work can be used to improve procedures for hydrodynamic characterization of both systems for scale-up purposes based on hydrodynamic similarities and differences.

CFD–PBM Simulation on Bubble Size Distribution in a Gas–Liquid–Solid Flow Three-Phase Flow Stirred Tank

“…The simulation results are in good agreement with the experimental data. Krishna et al 9 and Abbasi et al 10 proposed that the hydrodynamic behaviors of a gas−liquid bubble column and a gas−solid fluidized bed are not only qualitatively but also quantitatively similar. The average bubble diameters in the two systems are comparable, especially at low gas velocities.…”

A CFD based empirical model for assessing gas holdup in bubble columns

“…Due to a bubble column's efficiency and capability in the intense mixing of gas and liquid phases, they have wide utilization in various engineering fields such as chemical, biochemical, and energy storage industries . Some application examples of bubble column reactors are biohoch reactors, airlifts, and chemical gas cleaning units . One of the important dimensionless hydrodynamic parameters that shows the efficiency of the bubble column is gas holdup, which is defined as the volume of the gas phase to total volume.…”