1. The appropriately designed resistance of the air nozzles can make air distribution smooth, can have good regulation performance and can reach stable operation. 

2. The air speed of the outer cap hole is low, reducing the wear between the air nozzles. 

3. The outer is connected with the inner pipe thread, easy for maintenance. 

4. During running, the air nozzles are not easy to jam and not easy for ash blocking. 

5. They have long service life and are not easy to damage.