Numerical simulation of metallic solid bridging particles in a fluidized bed at high temperature

High temperature fluidization of iron particles was investigated by numerical simulation based on the discrete element method (DEM) as a case study for metallic bridging. A model was developed for metallic solid bridging by surface diffusion mechanism including the effect of surface roughness. The simulated fluidization behavior was highly time dependent, which is completely different from our previous results for liquid bridging particles [T. Mikami, H. Kamiya, M. Horio, Chem. Eng. Sci. 53 (1998) 1927.]. Both the amplitude of pressure fluctuation and the absolute value of bed pressure drop decreased with time. These tendencies agreed well with the experimental data of Mikami et al. [T. Mikami, H. Kamiya, M. Horio, Powder Techonol. 89 (1996) 231.] although temperature and bed size were different. Size and shape of agglomerates were much different for different surface roughness models. Hypha-shaped agglomerates were more dominant in the case of the lowest cohesiveness (three-microcontact-point model). The size of agglomerates grown on the wall was largest for the largest cohesiveness and smallest for the smallest cohesiveness.