Simplified multi-sphere model-based DEM simulation of particle behavior in hopper during ship loading for dust control

Abstract

In conventional ship loading with hopper, dust dispersion is a major cause of material waste and air pollution. Just as the discharge of bulk material in frequently used silo, two factors, air entrainment and particle velocity at the orifice significantly contribute to dust emission during downstream flow of free-falling particles. This study is dedicated to simulate particle behavior until approaching the hopper orifice. To improve computational efficiency, simplified multi-sphere model should be used rather than relatively accurate particle representation for actual material. However, in the pertinent literatures the degree of approximation to the particle surface for a reliable analysis of the two mentioned factors was still not documented. The objective of this paper is to evaluate the performance of different simplification methods in DEM (Discrete Element Method) simulation by testing various combinations of parameters (i.e. size, number and position of spheres), and, therefore to select a suitable particle model, based on which, the results of simulation can be used to predict granular flow after the orifice within acceptable computational time.