Study On Flow Field And Grading Screening Performance Of Vertical Roller Mill Based On Gas-Solid Two-phase Flow

In the cement industry and other non-metallic mineral industries,vertical roller mill is widely used in comparison with other grinding equipment,but currently there is a lack of comprehensive understanding of the flow field and particle grading screening performance of vertical roller mill.Therefore,this paper applies the CFD technology to the vertical roller mill,and establishes the mesh division method and numerical simulation calculation model.The gas-solid two-phase flow field and the grading and screening performance are comprehensively studied.The specific work content and research results are as follows:HRM1700X vertical roller mill is an industrial grade experimental mill that can measure actual production data.A suitable coupling calculation model of HRM1700 X vertical roller mill is established.The DPM model of Euler-Lagrange method is used to simulate particle movement and grading screening process.The turbulence model adopts the standard k-? model;the discrete format adopts the QUICK format;the pressure interpolation format adopts the PRESTO! format;the pressure velocity coupling format adopts the SIMPLEC algorithm;and the multi-reference coordinate system model(MRF)is used to simulate the rotating of the separator blade.According to the design parameters of vertical roller mill,the three-dimensional model of vertical roller mill is established,and the flow field model of vertical roller mill is extracted by Spaceclaim.ICEM CFD is used to mesh the vertical roller mill flow field,the grid file is imported into Fluent,the appropriate coupling calculation model is selected,and the boundary conditions are set according to the actual working conditions.Firstly,when the vertical roller mill is unloaded,the gas phase flow field in the mill is simulated.Then the material particles are loaded,and the velocity field,pressure field and discrete phase distribution of the gas-solid two-phase flow in the mill are analyzed in detail.Finally,the simulation results are compared with those of Tongxiang Jushi Company's experimental vertical mill production data to verify the correctness of the coupled calculation model.By changing the operation parameters and structure parameters of vertical roller mill,the purposes of optimizing the flow field and improving the classification efficiency of vertical roller mill are achieved.According to the numerical simulation results,the following conclusions are obtained: the pressure loss of the vertical roller mill,the pressure loss of the wind ring grinding roller area and the pressure loss of the separator are increased with the increase of the air volume,and the optimal system air volume is 50000m3/h;The pressure loss of the separator area increases with the increase of the rotational speed of the moving blade and the decrease of the grading particle size,while the area of the wind ring mill roll is almost unaffected,and the optimal rotational speed of the moving blade is 200r/min;The LV type moving blade grading ring area airflow has larger radial speed,with the smallest crusher area pressure loss 1216 Pa and the highest classification efficiency,the actual production should use LV type moving blade;With the increase of the number of moving blades,the particle size of the particles is continuously reduced,and the pressure loss of the powder separator is increased.In order to improve the quality of the finished product,150 moving blades can be selected;When the inclination angle of the upper casing of the classifier is 65°,the particle size is less than 45?m,and the airflow has a large radial velocity,which ensures the uniformity and stability of the airflow in the vertical direction of the classifier,and is more conducive to particle grading screening.According to the applied coupling calculation model and numerical calculation method,it is possible to study the flow field of the vertical roller mill and optimize the grading and screening performance,provide technical guidance for the vertical grinding energy-saving transformation,and promote the progress of the traditional cement industry.