Effect of Particle Size on Solids Distribution in Dense Gas-Liquid-Solid Flow in a Slurry Bubble Column

Slurry bubble column reactors are predominantly used to perform solid-catalysed gas-liquid reactions such as resid-hydrocracking, etc. In addition to other operating and design parameters, particle size distribution (PSD) of solids can have a significant influence solids distribution and consequently on the performance of slurry bubble column (SBC). In most of the previous studies, either mono-dispersed particles or particles with narrow size distribution are considered. Mixing and segregation of particles of different size and their influence on solids distribution and hydrodynamics are not yet well understood, which is the main objective of the present work. In this work, using Eulerian multifluid CFD model and KTGF, we have investigated the effect of PSD on mixing and segregation of particles of different size and their influence and solids distribution and hydrodynamics.

We have implemented widely-used closure models for gas-liquid and liquid-solid phase interactions in the commercial solver and performed simulations of air-water-glassbead system with a constant particle size (d_p=250 μm), for wide range of superficial gas velocities (U_g=5-30 cm/s) covering homogeneous and churn turbulent flow. We compared the predictions of overall gas volume fraction and gas volume fraction distribution measured earlier in our research group. The predictions were further improved by incorporating non-drag inter-phase coupling forces along with bubble swarm corrections. We have used the experimentally-validated model to understand the effects of PSD on solids distribution, segregation and mixing of particles, for a wide range of U_g (=5-30 cm/s). In particularly, we are working on understanding the mechanisms of segregation and mixing in bubbly and churn turbulent flow conditions. Further details of the computational model, experimental validation and result will be presented at the conference. Eulerian CFD models, capable of accurately predicting the solids distribution and segregation/mixing characteristics will be very useful in design and performance optimization of three-phase slurry reactors.