DEM numerical simulation of wet cohesive particles in a spout fluid bed

Abstract

The dynamic behavior of wet cohesive particles is greatly different from that of dry particles in a spout–fluid bed. A modified discrete element model (DEM) for wet particles is established by adding an additional module to consider the presence of the liquid bridge. DEM simulations are conducted for the dry and wet granular systems and the geometry of the bed is the same as the experimental one of Link et al. The influences of drag models and liquid contents are investigated. It is found that the Koch–Hill drag model predicts a dominant peak, the same as the measured results of Link et al., in the frequency domain of the dynamic pressure drop under Case A. However, the Gidaspow drag model fails to catch this phenomenon. With an increase of the liquid content, the fluctuation range of the pressure drop increases firstly and then decreases rapidly under Case A, but it monotonically increases under Case B. In the spout–fluid bed, dead zones, where the particles are de-fluidized, appear at the corners. The inclined angle and the area of the dead zone expand with the increase of the liquid content, which makes the value of the final Lacey mixing index decrease.