Experiments and CFD-DEM simulations of cohesive particles sedimentation in stilled fluid

Abstract

Particle agglomeration is observed in slurry loop reactors due to the presence of cohesive force between the swollen polyethylene (PE) particles, which has direct impact on the hydrodynamics predictions. However, a qualitative study of the cohesive forces in the suspensions of swollen PE particle at the microscopic level is still lacking. In this study, a simulation contrast experiment method for quantification of cohesive force is proposed. The simulation method is based on a coupled computational fluid dynamics and discrete element method (CFD-DEM) approach, which have been used to study and explain the effects of cohesion on fluidization of particles. The DEM allows the dynamic simulation of the solid phase motion by tracking individual particles, whereas a CFD algorithm is commonly used to simulate the flow field of the continuous fluid phase. The swollen PE particles, initially arranged within a cylinder region in a quiescent hot dodecane, are made to fall, and their sedimentation induces the liquid flow around them. The interactions between the particle motion and the liquid flow are favorably compared with the experimental data, demonstrating the value of the cohesive energy density for the swollen PE particles is between 4000 J/m3 and 5000 J/m3.