1. When the dynamic combustion was put into operation, serious air distribution imbalance or burning too much power happens.
2. Before the boiler is started, the fluidization air nozzles are blocked too much or there are  wear -resistant materials and other debris left in boiler.
3. During shutdown of the boiler, the fuel is not fully burnt, causing car precipitation or coking at low temperature.
4. The bed temperature is too high or the melting point of fuel coal and bed material is too low.
5. The fluidization air volume is low, and poor fluidization happens for long time.
6. During operation of the boiler, the proportioning of air and coal is not proper for a long time, so the coal is excessively fed.（lsh）