Simulation of mass-loading effects in gas-solid cyclone separators

Three-dimensional, time-dependent Eulerian-Lagrangian simulations of the turbulent gas-solid flow in a cyclone separator have been performed. The Eulerian description of the gas flow is based on lattice-Boltzmann discretization of 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 10⁷ inside the cyclone at any moment in time) as clusters of particles (parcels), we study the effect of particle-to-gas coupling on the gas flow and particle behavior at appreciable mass-loading (0.05 and 0.1). The presence of solid particles causes the cyclone to lose some swirl intensity. Furthermore, the turbulence of the gas flow gets strongly damped. These two effects have significant consequences for the way the particles of different sizes get dispersed in the gas flow. It is anticipated that the collection efficiency gets affected in opposite senses: negatively by the loss-of-swirl, positively by the reduced turbulence.