The amount of water flowing through the cylinder of the LM vertical roller mill should correspond to the material throughput of the LM vertical roller mill and be controlled within an appropriate range.The water flowing through the cylinder of the LM vertical roller mill is mainly composed of the carrying water and the underflow of the cyclone.Under normal conditions, the bottom water flow of the hydrocyclone generally remains unchanged, but the premise is to ensure that the bottom flow sand setting nozzle of the hydrocyclone is free of wear.When the bottom flow sand setting nozzle of the hydrocyclone is worn, the working conditions of the hydrocyclone itself change, which will increase the bottom water flow of the hydrocyclone and reduce the top flow overflow, resulting in an increase in the water entering the LM vertical roller mill.