DEM Study Of Indented Cylinder Separator’s Structural Design And Research

The precise sorting of whole and broken rice is an important part of the rice processing process.The selling price of rice on the domestic and international markets is closely related to its processing accuracy,grain size,broken rice content,chalkiness and imperfect particles.Among these,the broken rice content of rice is an extremely important quality requirement.In order to meet market demand and improve the economic efficiency of the grain processing industry,grain companies use a variety of separating machines to classify rice,of which the indented cylinder separators has an irreplaceable role.In the past,the design of cylinder separators has relied on a combination of experimentation and experience,resulting in a gap between the quality and speed of the cylinder separators compared to foreign sorters.Therefore,this paper proposes an optimised design method for cylinder separators based on the clarification of the movement characteristics of rice particles in the cylinder,which is of great engineering significance and scientific value.This study takes the analysis of the mixing process of the cylinder separator as the starting point.Firstly,the discrete element method analysis model of the cylinder separator is established,and the Lacey index is used to investigate the influence of the cylinder rotation rate and the cylinder filling rate on the radial and axial mixing and segregation of the whole broken rice in the mixing area.With the movement of the cylinder system,the polarisation index of the particle system fluctuates periodically in both the radial and axial directions,and the mixing and polarisation of the particles in the system shows alternating mixing-polarisation-mixing processes.Next,the effects of drum speed and the tilt angle of the drum axis on the distribution functions of the detachment angle of whole and broken rice particles were investigated,and the differences in the distribution of the detachment angle were quantified using the Kullback-Leibler scatter(KL distance).The Kullback-Leibler scatter increases and then decreases as the drum speed increases and the axial tilt angle decreases,with the peak value achieved at 50% of the drum speed and 4° of the axial tilt angle,which corresponds to the optimum drum speed and axial tilt angle.The influence of the baffle angle and length of the collection chute on the sorting quality was also investigated.The separation efficiency and loss rate increase rapidly with time as the angle of inclination of the collecting trough increases,then the trend increases gradually and the sorting time decreases rapidly;the best sorting quality is achieved when the angle of inclination of the collecting trough is 68°.The separation efficiency and losses increase first and then decrease as the length of the collection chute baffle increases.The sorting time decreases rapidly.The best sorting quality is achieved at a collecting chute baffle to drum radius ratio of 0.6.Finally,by establishing a regression model,the influence of each parameter of the drum sorter(rotation rate,drum axis tilt angle,collection chute inclination angle,collection chute baffle length)on the separation efficiency,loss rate and sorting time is studied,and the influence of each factor on the sorting quality is clarified,and the parameters are optimised to obtain the optimum parameters.