Analysis Of The Flow Field In Vertical Roller Mill Chamber Based On Multiphase Flow Technology

The flow field of powder transportation process in the vertical roller mill was analyzed to study the effect of mill structure on the powder transportation process. SolidWorks and Computational Fluid Dynamics (CFD) Fluent softwares were used to create three dimensional flow simplified chamber model of the vertical roller mill powder transportation on the basis of characteristics of the transportation process and mill structure.Based on the CFD technology and engineering fluid dynamics theory, Mixture multiphase flow numerical model and RSM turbulent numerical model of CFD technology were chose to study the traits of the gas-solid two-phase flow field in the vertical roller mill chamber. The analysis shows that there is visible 3-D rotation turbulent flow in the chamber flow field and there is intense turbulent pulsation in the table-roller flow field to be the main gas-solid flow coupling field. There is high speed flow in the table-shell flow field and there is only rotation flow trait in the roller-separator flow field. What is more, the parameters features in the flow field near the separator wall boundary suitable for the hydrodynamics continuity theory and the Bernoulli equation fluid theory show that the less the rotation wall boundaries, the more steady the gas-solid flow. And there are asymmetry features in the partial flow field and linear characteristics near the wall boundaries in the chamber flow field.With the increase of gas flux of vertical roller mill, the pressure drop and velocity of the gas-solid flow are increased. The higher speed and pressure benefit the process of powder transportation. But at the same time, the transportation process will be slower and the dissipation of internal friction force and energy in the mill will be increased due to the more turbulent vortexes induced by the higher inertia force of the higher speed flow. The analysis of the flow pressure near the separator wall flow field under the influence of different gas fluxes shows that gas-solid turbulent pulsation is not only related to the flow inertial force, but also related to the flow wall boundaries.Combined with the study on the chamber flow field, the principles of approaches used in measuring engineering flow field were analyzed and the suitable measure tool was chose to study the gas-solid flow field. Then the flow field was analyzed by the simulation and engineering data. The engineering analysis of gas-solid flow in the HRM mill is rational to indicate that the numerical models of Mixture and RSM are suitable for the 3-D rotation flow field and there is visible difference between the parameters of flow field on the different conditions of gas flux. The engineering analysis shows that the gas inlet flux should be adjusted to the working mill to improve the efficiency of powder transportation. And the influence of chamber wall on the flow field shows that it is not enough to enhance the efficiency of vertical roller mill through the approach of changing gas fluxes, but also it should modify the partial structures of the mill.Based on the analysis of numerical simulation and engineering analysis of the flow field, the paper shows that mill structural modification should concentrate on table, rollers and separator structures. Then the scheme of filter cone was created according to the separator original structure and the modification chamber flow field model was built. The gas-solid flow field of chamber modification model was studied to show that turbulent vortexes are reduced in the modification flow field because of the reduction of the zones between filter cone and rollers. The reduction of turbulent pulsation, postponement and vertical turbulent vortexes profit the powder transportation. The analysis of the modification model enhances the original simulation analysis and the influence of analysis in chamber flow field on modifying optimization design of vertical roller mill.