Numerical simulation of gas and particle flow in cyclone separators

Abstract

Cyclone separators are widely used in industrial applications. Their separation efficiency and pressure drop influence on the performance of processing systems. The simulations presented in this paper, the flow behavior of gas and particles is simulated by means of computational fluid dynamics with three-dimensional Eulerian-Lagrangian simulations. The RNG k-ε model and the Reynolds stress model (RSM) were used to model gas turbulence. The flow behavior is examined in the terms of velocity components, static pressure and pressure drop contour plots for flow field, and gas-solid concentration. Simulations show that the gas volume fraction is increased in the top of cyclone and that the particle concentration is increased in the bottom of cyclone under the action of gravitational force. Also the results show that the particle concentration along the radial direction of cyclone can be divided into two regions: a central region of the cyclone area with low particle concentration and the wall region with a high particle concentration. The gas and particles flow within the cyclone under the influence of centrifugal and gravitational force making the particles flow to the wall, and leading to increased particle concentration near the walls and in the bottom of cyclone. Comparison of the results given by velocity components, pressure fields and volume fraction can describe the turbulent flow. The high pressure near the wall due to centrifugal force creates a depression on the axis of the cyclone. The results of this study indicate that pressure drop increases with increasing inlet velocities for both RSM and RNG k-ε models, moreover the RSM model gives a higher pressure drop compared to the RNG k-ε model. The RSM model provides well for the forced vortex and free vortex, and better captures the phenomena within intense vortex flow in the presence of walls within cyclone separators.