Detailed Modeling of Melt Dripping in Coke Bed by DEM – SPH

Abstract

A high-resolution numerical model was performed for a detailed understanding of packed-bed structures constructed by actual scale cokes, and the molten slag (SiO 2-CaO-Al 2 O 3) trickle flow characteristics in the lower part of an actual blast furnace. Smoothed particle hydrodynamics (SPH) simulations can track the motion of liquids containing dispersed droplets, and the discrete element method (DEM) with a multisphere approach makes possible to simulate non-spherical solid-particle motion. We carried out highresolution large-scale trickle flow simulations using more than 10 million particles, carried out case studies of statistical processing, and evaluated the effects of physical properties varied by the composition or temperature of slag samples. We clarified that there is a limitation to predict the holdup accurately based on the capillary number, which is a widely used approach. We analyzed the influence of melt viscosity on trickle flow, and clarified that an increase in viscosity increases holdup because limiting the effective flow path and suppressing the dispersion of the droplets promoted the enlargement of each stagnant droplet. This detailed direct dynamic model could explain the mechanism underlying different holdup tendencies in conventional research.

Holdup Characteristics of Melt in Coke Beds of Different Shapes

“…Coke samples with density ρ = 1 050 kg/m 3 , dynamic friction coefficient = 0.43, Young's modulus = 2.4 GPa, and Poisson ratio = 0.35 were employed. 15) The position and rotation angles of each coke sample were determined by using a pseudorandom number, and the packing simulation into a box-type container with 0.20-m sides was performed. Next, we simulated the slag trickle flow in the coke-packed bed.…”

“…Based on this approach, a method was suggested to track numerically the coke bed structure, local void shape, and molten slag flow. [14][15][16][17] In this research, we aim to determine for the first time a direct relationship between coke shape information and holdup sites exerted by the shape of the coke by using the above-mentioned approach.…”

Method for Simulating Gas Permeability of a Coke Bed Including Fines Based on 3D Imaging on the Coke Particle Morphology

“…The obtained surface coordinates were converted into standard triangulated language (STL), in other words, the surface shape was polygonated with a triangular mesh. 26) To apply this shape information to the MS-DEM, the spherical particles in the model were filled to conform to the shape. With these procedures, the shape variations of the individual coke samples with degradation can be obtained.…”

Numerical Study of Binary Trickle Flow of Liquid Iron and Molten Slag in Coke Bed by Smoothed Particle Hydrodynamics

“…It is necessary to determine the time change of each melt velocity to consider the dripping mechanism leading to this result. The average velocity in the gravitational direction per unit time is given, considering the temporal change in the center of gravity of each phase, as follows [44]: Figure 4 shows the volume distribution of liquid iron and molten slag in the height direction at t = 0.20 and 1.20 s. In Figure 4a, liquid iron almost has the same distribution at t = 0.20 s, irrespective of the presence of slag and the change in θs. Conversely, at t = 1.20 s, the liquid iron with slag exists at a lower height compared to "without slag" iron.…”

“…It is necessary to determine the time change of each melt velocity to consider the dripping mechanism leading to this result. The average velocity in the gravitational direction per unit time is given, considering the temporal change in the center of gravity of each phase, as follows [44]: [45] and also appears to follow the Darcy-type equation. From a detailed perspective, however, the liquid iron tends to increase the dripping rate because of the presence of slag.…”