Particle simulation of vibrated gas-fluidized beds of cohesive fine powders

TL;DR

This study employs 3D particle dynamics simulations coupled with simplified gas flow models to investigate how vibration and gas flow influence the behavior of cohesive powders in fluidized beds, revealing mechanisms behind bubble formation and fluidization enhancement.

Contribution

It introduces a simplified 1D gas flow model in particle simulations to analyze the combined effects of vibration and gas flow on cohesive powders in fluidized beds.

Findings

Vibration-induced pressure pulsation dominates in fully fluidized beds.

Vibration creates tensile stresses that break up cohesive assemblies.

Cyclic pressure pulsation increases with gas flow rate.

Abstract

We use three-dimensional particle dynamics simulations, coupled with volume-averaged gas phase hydrodynamics, to study vertically vibrated gas-fluidized beds of fine, cohesive powders. The volume-averaged interstitial gas flow is restricted to be one-dimensional (1D). This simplified model captures the spontaneous development of 1D traveling waves, which corresponds to bubble formation in real fluidized beds. We use this model to probe the manner in which vibration and gas flow combine to influence the dynamics of cohesive particles. We find that as the gas flow rate increases, cyclic pressure pulsation produced by vibration becomes more and more significant than direct impact, and in a fully fluidized bed this pulsation is virtually the only relevant mechanism. We demonstrate that vibration assists fluidization by creating large tensile stresses during transient periods, which helps break up the cohesive assembly into agglomerates.