Numerical Studies on Particle Dynamics in a Spouted Bed

Abstract

A coupled computational fluid dynamics (CFD)discrete element method (DEM) technique has been adopted to examine the dynamic behavior of particles in a rectangular spouted bed. Eulerian method has been used to solve the Navier−Stokes equation for the gas phase (for the CFD) and Lagrangian method (for the DEM) for the particle phase, where the k−ϵ two-equation turbulence model has been used to capture the effect of gas-phase turbulence. In the present work, we sought to predict the minimum spouting velocity (U ms ) numerically for a fixed bed height and particular particle properties. The effects of the inelastic collision and the friction on translational and rotational dynamics of the particles in spout, annulus, and fountain zones have been brought out with the intensive parametric study. The results reported here would be a way forward for a better understanding of the spouted bed processing where translational and rotational dynamics of particles play a key role.

Computational Fluid Dynamics–Discrete Element Method Studies on Dynamics and Segregation in Spouted Bed with Polydispersed Particles

“…It is worth noting that, to predict and confirm the minimum spouting velocity from the pressure drop−gas velocity profile, a parallel analysis of the void fraction contour is also essential. 41,51 Variations in the numerically obtained void fraction contour with increasing and decreasing gas velocities are shown in Figure 2i−n. When the gas velocity is decreased from a spouted state, below a critical value, the top spout above the bed collapses, and an increase in pressure drop is observed (point F in the profile).…”

“…Similar observations for monodispersed particles are also reported in our earlier work. 41 The axial velocity (V z /U g ) is independent of particle size at any bed location. Away from the spout axis, a negative value of V z in the annulus and fountain zone signifies the downward motion of particles.…”

“…49 A detailed discussion of the required number of particles to obtain statistically convergent dynamics and the requirement of the bed dimensions so that the pseudo-2D assumption is valid is available in an earlier work. 41 All the simulation parameters are provided in Table 2.…”

“…However, the minimum size of the grid cannot be lower than the size of the particles. A detailed discussion has been presented by Raman et al 41 Marchelli et al 49 have also discussed the accuracy and convergence of CFD−DEM simulations. The Supporting Information presents the grid independence study and the experimental validation.…”

“…Application of a conical spouted bed reactor (CSBR) in the continuous pyrolysis of high-density polyethylene 37 and an assessment of particle segregation in the process of waste valorization in a conical spouted bed are also reported. 38 Very recently Raman et al 41 performed numerical studies to investigate the effects of inelastic collision and friction on the particle-phase dynamics at different zones of the spouted bed with monosized particles.…”