Influence of particle diameter and material properties on mixing of monodisperse spheres on a grate: Experiments and discrete element simulation

The Discrete Element Method (DEM) can help to obtain detailed information on the mixing process within a bed of fuel particles on grate firing systems. In a first study it was shown by comparing experiments on a generic grate with DEM simulations that for a granulate consisting of monodisperse spheres the influence of grate stroke length and bar velocity can be reproduced. Prior to tackling particle assemblies which are polydisperse and consist of particles of complex shape it has to be shown that the influence of particle diameter and material properties of the particles is described correctly by DEM simulations. Thus experiments with monodisperse spheres of three different diameters (5, 10, 20 mm) and two materials (plastic, wood) are compared to DEM simulations. The mixing process is measured at the front side wall and at the top surface of the particle bed and quantified by image analysis. Both visual observation and mixing parameter results attest a very good agreement between experiments and simulations. The influence of particle diameter and material properties measured in the experiments can be reproduced by DEM simulations.