The vertical roller mill mainly consists of a grinding system, a drying system, a powder selection system, a feeding system, an external circulation system, etc., and the crushing material is squeezed by the regular movement of the main auxiliary grinding roller and the grinding table, and the feeding system falls. The material on the grinding table is crushed and crushed by the main auxiliary grinding roller. The pulverized material is blown up by the hot disc of the wind ring as the grinding disc rotates to the edge of the grinding table, and the first separation and drying of the particles is completed, and a part of the large granular material is not Pneumatic transport, falling to the bottom of the disc, re-entering the feeding system from the external circulation system, and then entering the grinding system again, and another part of the material particles are pneumatically transported and dried, and enter the powder sorting system at the top of the vertical mill. The material particles are separated twice in the interior of the classifier, and the qualified fine powder particles are taken out of the vertical mill by the hot air, and the unqualified ash bucket is again grounded on the grinding disc and ground again.
Although the vertical grinding has high efficiency, less pollution to the environment and low energy consumption, it also encounters many bad problems in the production process, such as mill vibration, excessive noise, powder transport and selection. Powder efficiency is low, production does not meet design requirements, and so on. These problems have seriously affected the promotion and application of vertical mills. Experts and scholars at home and abroad have conducted research and analysis on the problems encountered in vertical mill production.
The reason why the vertical roller mill generates vibration and proposes a certain solution:
(1) There are metal impurities in the material. The solution is to strictly select the materials.
(2) If the material is too large, the material layer is too thick, which causes the air volume in the mill to be insufficient, the circulation inside the material is intensified, and the grinding roller is too high to cause vibration. In this case, the feed amount should be reduced in time, the air intake should be adjusted, and the system should be kept ventilated.
(3) Excessive thin layer can also cause vibration of the mill. A reasonable abrasive layer cannot be formed on the grinding disc, causing vibration between the grinding roller and the grinding table. At this time, we should increase the feed amount, reduce the amount of air intake and increase the water appropriately to form an effective material layer.
(4) The air intake of the system is unreasonable and the material entering the mill is unstable. Under the condition of keeping the unloading unobstructed, the air intake amount is reasonably selected.
(5) The grinding grain size is too large or too small. When the particle size is too large, we should increase the feed amount slightly, reduce the inlet air volume and the inlet air temperature; when the particle size is too small, we should reduce the internal temperature of the mill, reduce the speed of the powder separator, and increase the moisture in the mill.
Earlier, some researchers thought that the process parameters such as the amount of feed of the vertical roller mill, the particle size of the material, the pressure of the grinding roller and the shape of the grinding roller have a great influence on the grinding efficiency of the vertical mill, and they have been studied through scientific and reasonable experiments. In the application of ultra-fine grinding, the vertical roller mill can be used for ultra-fine grinding, but it is equipped with a precision classifier, which is mainly suitable for ultra-fine grinding of medium-hard materials.
After that, the vertical roller mill realized the innovative design of structural upgrade and transformation, developed the domestic large-scale raw material vertical mill, and successfully put into trial operation. The main technical indicators have reached the international ranks well, filling the domestic large-scale vertical mill can not produce. The blank has completed the independent design and production of large-scale mechanical equipment required for the 3000t/d cement clinker production line, effectively improving the competitiveness of China's cement industry as a whole.