When the rotary kiln is working, there will inevitably be gaps at the joint between the rotating and stationary parts. In order to prevent the external cold air from entering and affect the normal operation and use effect of the kiln, sealing devices are installed. The main types of sealing devices mainly include the following.

1. Labyrinth seal of rotary kiln can be divided into axial seal and radial seal.

2. Face friction seal with asbestos rope.

3. Graphite block (cast iron, copper) friction seal.

4. The third heavy metal friction sealing device, which uses the support and spring to press the metal tightly on the cylinder body to seal the air flow.

If there is leakage of cold air at the kiln head, the firing temperature in the kiln will be reduced. The leakage of cold air at the kiln tail will reduce the secondary air volume, affect the ventilation and firing in the rotary kiln, increase the exhaust gas emission, and increase the negative effect of windmill and electric dust collector. Therefore, it is very necessary to set up sealing device system in the design and production of kiln.