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Numerical analysis was carried out on the dripping and holdup behaviors in the lower part of a blast furnace for coke bed structures having different shapes; a discrete element method smoothed particle hydrodynamics scheme was used considering the size distribution immediately above the raceway. Even for coke beds with similar void fractions, the averaged-coke-shape factors such as ϕ and (ϕD) 2 give little clear correlation for holdup sites. Instead of averaged-coke-shape information, only the direct evaluation of the void shape of the packed bed can explicitly trace the holdup site.

This study attempted to conduct a topological data analysis of groups of particles in packed-bed structures to provide quantitative evaluations of void shapes. This study examined the spatial correlation between the packed bed structure and the holdup sites through geometric data obtained from the coordinates of the various particles composing the packed bed to isolate characteristic structural data for liquid holdup sites in a packed bed. When the study defined "bottlenecks" as narrow areas of a scale below capillary length, it was discovered that, in packed beds consisting of particles of a single diameter, the contribution to holdup was related to the number density of bottlenecks. Regarding the dependence on the void fraction of the holdup sites, as trends were demonstrated that differed from the continuous change that accompanies changes in the modified Capillary number, the difference from the dimensionless correlation occurs. When particles of differing diameters intermingle, the bottleneck number density increases near particles with small diameter, and the percentage of blockages from droplets increases. As position and density differ depending on the particle packing method, it is suggested that holdup sites decrease in number when particles with small diameter are appropriately dispersed.