In practical applications of fluidized bed such as gasification, combustion and separation, the size of solid materials is not uniform and large solids coexist with small solids. The large size difference induces characteristic motions of solids and significantly influences the mixing and segregation characteristics of the beds. However, it is difficult to predict these behaviors accurately and forces acting on large objects in fluidized bed are not fully understood.
In the present study, vertical forces acting on a single large object free-moving in gas-fluidized bed are obtained numerically by using the model proposed by Tsuji et al. (AIChE J., 60(5), pp. 1606-1620, 2014). The results are compared with the experiments under the same condition. Force measurement is performed using the Lagrangian sensor system developed by Harada et al. (Int. J. Multiphase Flow, 37, pp. 898-905, 2011); forces acting on a free-moving object are directly measured in the system. The density of large object is smaller than the apparent density of the bed and the large object is floating near the free surface of the particle bed as shown in Fig. 1. Calculation results agree well with experimental results quantitatively.