CFD–DEM simulation of the gas–solid flow in a cyclone separator

• Published in: Chemical engineering science Vol. 66; no. 5; pp. 834 - 847
• Main Authors: Chu, K.W., Wang, B., Xu, D.L., Chen, Y.X., Yu, A.B.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.03.2011; Elsevier
• Subjects: Applied sciences; Centrifugation, cyclones; Chemical engineering; Computational fluid dynamics; Cyclone; Cyclones; Discrete element method; Exact sciences and technology; Gas phases; Gas–solid flow; Granular dynamics; Hydrodynamics of contact apparatus; Liquid-liquid and fluid-solid mechanical separations; Mathematical models; Navier-Stokes equations; Pressure drop; Separation; Strands; Walls; Gas–solid flow; Granular dynamics; Separation; Discrete element method; Computational fluid dynamics; Cyclone; Gas-solid flow; Two phase flow; Equation of motion; Cyclone separator; Collision; Radial flow; Hydrodynamics; Flow field; Modeling; Gas solid flow; Solids flow; Loading; Gas flow; Navier Stokes equation; Pressure drop
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2010.11.026

In this work, a numerical study of the gas–solid flow in a gas cyclone is carried out by use of the combined discrete element method (DEM) and computational fluid dynamics (CFD) model where the motion of discrete particles phase is obtained by DEM which applies Newton’s equations of motion to every individual particle and the flow of continuum fluid by the traditional CFD which solves the Navier–Stokes equations at a computational cell scale. The model successfully captures the key flow features in a gas cyclone, such as the strands flow pattern of particles, and the decrease of pressure drop and tangential velocity after loading solids. The effect of solid loading ratio is studied and analysed in terms of gas and solid flow structures, and the particle–gas, particle–particle and particle–wall interaction forces. It is found that the gas pressure drop increases first and then decreases when solids are loaded. The reaction force of particles on gas flow is mainly in the tangential direction and directs mainly upward in the axial direction. The reaction force in the tangential direction will decelerate gas phase and the upward axial force will prevent gas phase from flowing downward in the near wall region. The intensive particle–wall collision regions mainly locate in the wall opposite to the cyclone inlet and the cone wall. Moreover, as the solid loading ratio increases, number of turns travelled by solids in a cyclone decreases especially in the apex region of the cyclone while the width of solid strands increases, the pressure drop and tangential velocity decrease, the high axial velocity region moves upwards, and the radial flow of gas phase is significantly dampened.