In this study, air-induced segregation processes of tobacco leaf and stem particles in a novel air-separation device are simulated using a coupled Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) approach. Numerous studies have been carried out in the past to understand the segregation mechanism for rigid particles, but the segregation behavior of flexible particles has not been sufficiently examined and understood. Therefore, tobacco leaf and stem particles are treated as flexible particles, which are modelled by connecting several identical spheres with elastic bonds, and the tobacco leaf and stem particles differ in sizes, densities, and elastic moduli in the present studies. The effects of gas velocity, feed rate, particle volume concentration, and the size of computational geometry on the extent of particle segregation have been thoroughly investigated. In addition, the impact of particle size distribution on segregation is analyzed, offering a more realistic representation of tobacco leaf and stem particles. The simulation outcomes demonstrated that particle segregation is significantly affected by the gas velocity and feed rate. The impact of volume concentration is found to be less significant compared to those of the gas velocity and feed rate. This study also reveals that the optimal gas velocity required for achieving a complete segregation depends on the size of computational geometry. Finally, a set of optimal parameters is proposed to guide the design and optimization of an air separator.
 

DEM-CFD Method,Flexible Particle,Segregation,Tobacco,Air Separator