Grinding Properties Analysis And Simulation Experimental Study Of Vertical Roller Mill

As the high efficiency energy saving grinding equipment, the vertical roller mill has been used more widely in the grinding field because it has the advantages of high yield, stable operation, high reliability and so on. Especially for grinding the cement raw materials in the NSP cement production field. With the extensive application of vertical roller mill and its maximization, the research on its grinding process and its grinding properties become one of the main research directions in the field of vertical roller mill. The grinding properties of vertical roller mill can be characterized by the milling capacity, that is the mill output and the unit energy consumption, the product fineness and so on. Taking the structure parameters and the process parameters which effect the mill's grinding properties as the research object, the mill's grinding properties is analyzed from three aspects: the theoretical research, the numerical simulation and experimental study.In theoretical research aspect, firstly, through the analysis of the particle layer comminution theory and the operation form of vertical roller mill, the grinding process of vertical roller mill can be divided into three phases: dense phase, the material crushing phase and the material expansion phase. Then the operating parameters are analyzed which include meshing angle, the grinding roller pressure, the relative size of grinding roller and grinding table, the speed and flux of mill ventilation, combined with the grinding process of the vertical roller mill. Thirdly , taking the compression - rebound characteristics of the material layer as the staring point, the force condition of material layer in the three phase of the mill's grinding process is analyzed. Taking the material moving trajectory on the grinding table as the introduction, the material force condition and the material radial speed on the grinding table is analyzed. Finally, the material layer state is analyzed from the following aspect: the stability and the thickness of material bed. Through the theoretical research, the relationship between the mill's grinding properties and the structure parameters and the process parameters of the vertical roller mill are obtained. The grinding pressure mainly affect the product particle size composition, namely, it mainly influence the yield of fine powder. The rotational speed of grinding table mainly influence the material force condition and the material radial speed. Thus the rotational speed of grinding table determines the material residence time in the grinding region. The material humidity mainly influence the stability of material bed. The material bed stability is poor when the material humidity at low level. It would cause the vertical roller mill vibration. When the material humidity at high level, it will cause the following phenomenon: the fine powder encapsulate around the coarse particle and it hinder the material's grinding. The thickness mainly influence the mill's operation. The vertical roller mill would vibrate whether the material bed is too thick or thin.In the numerical simulation aspect, as the key factor which influent the mill's grinding effect, the grinding layer state is analyzed using the discrete element numerical simulation method in the article. The grinding state mainly refers to the pressure distribution form which above the material layer. It depends on the vertical roller mill grinding method. In order to research the effect of grinding method on the material layer, the simplified model of the vertical roller mill which using different grinding method are established using the Solidworks software. Introduce the model to the discrete element analysis software EDEM to simulate. Through simulation, the pressure distribution chart above the material layer which located in grinding zone under different grinding method is got. And the influence law between fit form and product size is obtained too. The relationship between feed quantity and the mill operation is obtained from the simulation under different feed quantity.In the experimental study, the relationship between feed quantity and the mill operation is verified through the production process validation. And the simulation result about the tire roller is verified in the cement factory. In order to the further research, the hydraulic loading vertical roller mill experimental prototype is designed combined with the mill operation principle and the simulation results.