Coal mills operating under positive pressure may emit powder and pollute the surrounding environment in areas that are not tightly sealed; At the same time, it is also possible for powder to leak through the gaps between the rotating parts, exacerbating the wear of the dynamic and static parts and bearings, and deteriorating the lubricating grease. Therefore, sealing measures should be taken for these parts, that is, air with higher pressure than the desiccant inside the coal mill should be sent in to prevent the escape of coal powder airflow. The source of sealed air is usually compressed air for small coal mills, while special sealed fans are installed for large coal mills. When using a cold primary fan, it can also serve as a sealing fan.
