First of all, we can check and eliminate whether the abnormal sound is caused by the failure of reducer and bearing parts. If there is no problem, it is basically friction caused by sticking. The reasons are usually: 1, serious ash blockage; 2. Deformation of the heat storage element frame or sector plate sealing sheet; 3. There is foreign body blocking on the sealing surface. But in either case, the current will rise abnormally, so it is easy to judge. There is also an abnormal air leakage, which happened in a power plant before.