Study On The Mechaism Of Backflow Undersift Of Three-Product Cyclone Classification Screen

Three-product cyclone classification screen,as a kind of new and efficient equipment for fine coal classification,has very important research value and application prospect.This article focuses on the phenomenon of "backflow" occurring in the inner flow field of the three-product cyclone classification screen,and elaborates on the characteristics of the "backflow" phenomenon.By adjusting the structural parameters of the three-product cyclone classification screen,we can analyze the influence of these parameters on the "backflow",and achieve the regulation of the "backflow",and provide important theoretical and practical significance for the subsequent equipment structure optimization.First,we choose the factors that may affect the “backflow” of three-product cyclone classification screen by consulting the literature.Through the analysis of these factors one by one,to select the specific structural parameters for the single-factor test to lay the foundation for the study.The three-dimensional model of the three-product cyclone classification screen was established by using Solidworks software.After that,ICEM software was used to mesh the three dimensional models,then the grid information was imported to FLUENT for pre-processing.The FLUENT solver is set up,including quality checking and optimization of the case,calculation model selection,fluid physical property selection,boundary condition setting and reconciliation execution.Finally,the establishment of the three-product cyclone classification screen internal flow field model is completed.By changing the three parameters of the three-product cyclone classification screen,such as the the inner diameter and outer diameter of the center tube and the pyramid ratio,the numerical simulation method is used to analyze the influence rule and regulation function of these parameters on the "backflow".When the inner diameter of the central tube of the three-product cyclone classification screen is increased,the position of the backflow in the axial direction becomes later and the area of the backflow becomes smaller,which is beneficial to the weakening of "backflow".When the outer diameter of the center tube of the three-product cyclone classification screen is increased,the position where the backflow appears in the axial direction becomes earlier,the area of the backflow increases,and sieve flow gradually becomes smaller.When decreased the cube-cone ratio of the three-product rotary flow grading screen,to a certain extent,it can weaken "backflow" and reduce the area of it,and it has a great influence on the composition of the bottom flow,sieve flow and overflow,especially it is greatly decreased the amount of discharge at the bottom outlet.In this paper,the characteristics of the pressure field and velocity field in three-product cyclone classification screen are analyzed with the software of FLUENT.The research results in this paper provide a new perspective for further study of the inner flow field of the three-product cyclone classification screen,which provides a reference for further research on the "backflow",and provides theoretical guidance for the structure optimization and technological adjustmen of the three-product cyclone classification screen...