Particle effects on the hydrodynamics in slurry bubble column reactors: A review from multiscale mechanisms

Particles can appear as catalyst, reactant or product in various gas-liquid-solid three-phase production processes. Slurry bubble column reactors (SBCRs), as a kind of three-phase reactors, are preferred for phase contacting and mixing. However, literature studies concerning the effects of particles on the hydrodynamics of SBCRs are manifold and inconsistent in conclusions. Essentially, the multiscale interactions between particles, turbulent eddies and bubbles determine the reactor performance. This review focuses on revealing the particle effects in SBCRs from the perspective of multiscale mechanisms. Macroscopic hydrodynamic changes due to particle effects in literature are summarized. Dimensionless parameters, including the Stokes number, the solid-to-liquid density ratio, the ratio of particle and liquid characteristic lengths, the contact angle and the particle volume fraction are adopted to evaluate the characteristics of gas-liquid-solid flows. The relationships between particle influencing mechanisms and these parameters are analyzed and determined. Inconsistent experimental results are explained by different ranges of these dimensionless parameters. Moreover, particle effects at the mesoscale and microscale, such as the influence on the bubble dynamics and the pivoting effect on the turbulence energy spectrum, are elaborated. Finally, progress in modeling the SBCRs with consideration of particles effects using the Euler method are introduced. This review aims to improve the overall understanding of the complex hydrodynamics in the SBCRs. (c) 2024 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.