Transport of small particles through a 3D packing of spheres: experimental and numerical approaches

Abstract

In this paper, we study the transport of particles through a porous structure. Experimentally, we focus our attention on the dependence of the mean transit time on some parameters like the number of small particles injected in the structure, and the height of the packing. We have developed a numerical model, based on a DEM method, to simulate the experiment. This model is useful for accessing the internal structure of the packing and for analysing precisely the influence of the restitution coefficient and the size ratio between spheres.

Effect of DEM Parameters on the Simulated Inter-particle Percolation of Pellets into Coke during Burden Descent in the Blast Furnace

“…5 cially for larger expansions (x > 0.6). Thus, if the pellets bounce more they can more easily find their way into the space between coke particles, giving an increase in f. This observation is consistent with the results of the study of Lomine and Oger: 6) Pellets with higher restitution coefficients spend less time to percolate through coke layer, which means that the total number of pellet particles that percolate throughout the coke layer to the bottom plate, depicted in Fig. 6, is higher.…”

“…The difference in percolation between pellets of diameters 3 mm and 4 mm is, however, rather small. It should be noted that the condition for Dpe = 4 mm still exceeds the critical ratio 6,29) of bed (coke) particle diameter to percolating (pellet) particle diameter, which expresses the lowest value of Dco/Dpe at which the smaller particle can drain through the bed. The results indicate that increasing the size of the percolating particles is a feasible method to reduce inter-particle percolation.…”

“…Richard et al 5) proposed a Monte Carlo method to simulate the inter-particle percolation of a fine particle through a packing of monosize spheres. Lomine and Oger, 6) in turn, performed experiments and discrete element method (DEM) simulation to analyze transport properties of particles through porous structure and analyzed the influence of the restitution coefficient and the size ratio between spheres. Rahman and Zhu 7,8) and Li et al 9) used DEM to investigate percolation behavior, including percolation velocity, residence time distribution and radial dispersion under various conditions and found the simulation results consistent with the experiments reported by Bridgwater.…”

Rheology of evolving bidisperse granular media

“…A rough estimate of the drainage speed of these particles is about 1 mm/sec, although some particles travel through the bed several times faster whereas others never make it out of the bed. Comparison with drainage experiments of Lomine and Oger [34] without shearing is difficult because different bead size ratios were used; however, shearing significantly accelerates the drainage rate (factor of five or more).…”

“…Segregation studies by Lominé and Oger [34,35] examined the percolation of smaller particles, diameter d 1 , draining through a static, dense granular bed of larger particles, diameter d 0 . If they are sufficiently small, d 1 ≤ d 0 /6.46, the small beads poured onto a granular bed percolate through the bed similar to a pachinko gaming machine.…”