Two‐way coupled large‐eddy simulations of the gas‐solid flow in cyclone separators

Abstract

in Wiley InterScience (www.interscience.wiley.com).Three-dimensional (3-D), time-dependent Eulerian-Lagrangian simulations of the turbulent gas-solid flow in cyclone separators have been performed. The gas flow is simulated with the lattice-Boltzmann method. It solves the filtered Navier-Stokes equations, where the Smagorinsky subgrid-scale model has been used to represent the effect of the filtered scales. Through this large-eddy representation of the gas flow, solid particles with different sizes are tracked. By viewing the individual particles (of which there are some 10 7 inside the cyclone at any moment in time) as clusters of particles (parcels), the effect of particle-to-gas coupling on the gas-flow and particle behavior at modest mass-loadings (up to 0.2 kg dust per kg air) is studied. The numerical approach is able to capture the effect of mass loading on the swirl intensity as reported in the experimental literature. The performance of a Stairmand high-efficiency cyclone under various loading conditions is systematically studied. The presence of solid particles causes the cyclone to lose swirl intensity. Furthermore, the turbulence of the gas flow gets strongly damped. These two effects have significant consequences for the performance of the cyclone. The pressure drop monotonically decreases with mass loading. The collection efficiency responds in a more complicated manner to the mass loading, with mostly increased cut sizes, and increased overall efficiencies.

Study of Particle in Cyclones

“…The collection efficiency obtained with one-way coupling are slightly lower compared to simulation with two-way coupling. Like tendency was to be observed by Derksen et al (2008). The simulation of the mean tangential and axial velocity (Figures 2 and 3) were not observed differences between simulation with one-way coupling and two-way coupling.…”

“…The source term is calculated using the concept "Particles -Source-InCell" method. Derksen et al (2006); Derksen et al (2008) and Wan et al (2008) used the Lagrange approach with this method and to simulate the coupling of the phases in the cyclone.…”

“…According Derksen (2003), Derksen et al (2006), Derksen et al (2008) and Utakir et al (2010) turbulence in the cyclone plays an important role in the process of separation of the particles. The particle can modify the formation of swirls and the turbulence intensity of the continuous phase.…”

“…The particle can modify the formation of swirls and the turbulence intensity of the continuous phase. The swirls and turbulence are reduced with the increasing mass of the particle (Derksen et al, 2008). Derksen et al (2006) and Derken et al (2008) observed that the presence of particles reduced the intensity of the turbulence and swirls and creates a strong damping of the turbulence; swirls intensity decreased more in the lower part of the cyclone.…”

Turbulence Modelling of a Single-Phase Flow Cyclone Gasifier

“…Others later reported an appropriate agreement with experimental data using a more complex Reynolds Stress turbulence model [15] [16]. Moreover, more demanding modeling with large eddy simulations (LES) was found to give an improved agreement with LDA measurements [17] [18] [19] [20] [21].…”