In recent years, vertical roller mill are warmly favored by enterprise because of its advantages:low power consumption, incorporate grinding,dying and powder selection as a whole,wide range application for material,convenient adjustment for fineness and kinds etc;

However, vertical roller mills are a big controversy in grinding system now, as final grinding of cement, not only it has requirements for fineness, but also it has requirements for particle size distribution. Professor Zhang Changsen believed that requirements of cement fineness can be adjusted through grinding pressure, and the requirement for cement particle size distribution can be adjusted through inside separator and outside powder selection system. Different vertical roller mills have adopted different powder selection devices or other machine structure settings.

Professor Zhang Changsen showed that different vertical roller mills have adopted different powder selection devices, but working principles are same basically, both of them are by means of adjusting ventilation and roller speed or adjusting at the same time to reach the requirement of product particle size distribution. In the process of actual production, not only can it adjust product particle size distribution by means of above methods, but also other measures, such as measures of adjusting the height of gauge ring, millstone grinding pressure, until it is up to the requirement of product required.

China cement grinding technology and equipment has developed rapidly for more than decade, cement grinding station system which is widely used, exists varying degrees in energy saving space and power consumption reducing now. To carry out green energy saving grinding system, it is not only the means of reducing cost and improving efficiency but also the measures of realizing industry upgrade and energy saving and emission reduction.