Discrete Element Modeling of Hemp Particle Separation Using a 3D Vibratory Separator.

Abstract

Existing cleaning equipment was ineffective for cleaning processed hemp material (a mixture of fibre, core, and chaff). One of the major obstacles was the lack of the knowledge on the cleaning process. In this study, a 3D vibratory separator (screen-type) was experimentally studied for cleaning processed hemp material through separating chaffs (small particles) from the other particles (larger particles) in a mixture. In the experiment, the separation efficiency of the 3D vibratory separator was measured for different horizontal and vertical vibratory settings of the separator. Results showed that the separation efficiency varied from 23 to 86%, depending on the vibratory settings. The low separation efficiency was due to the fact that chaff was held within the entangled fibre, which prevented chaff from passing through the screen. A numerical model was developed to simulate the 3D vibratory separator using the discrete element method (DEM). The main model components included virtual particles of processed hemp material as well as a virtual 3D vibratory separator. The model is able to deal with mixtures of different particle sizes and different portions of fibre, core, and chaff particles, and predict the separation rates and efficiencies of the 3D vibratory separator. When compared with the measured separation rate, the simulated separation rate was higher towards the end of separation processes due to inexistence of fibre tangle problem in the virtual hemp particles. However, the trend of simulated values could adequately explain that of the measurements.