The reasons are as follows: (1) The fan is airfoil, and the blade head is easy to accumulate dust due to the large camber of the airfoil; (2) The selection range of fans is large. When the unit is at full load, the opening of the damper of the induced draft fan is only 60%, and the opening of the damper door is small, which leads to the large airflow pre-rotation at the inlet of the fan and aggravates the dust accumulation on the blades.

According to the field situation, it is decided to adopt the suggestion of replacing the straight blade impeller put forward by thermal engineering, and reduce the dust accumulation on the blade by changing the streamline of the blade.

The blower and induced draft fan are reformed, that is, the blower is changed to 553 high-efficiency blower and the induced draft fan is changed to 468 straight-blade fan. At the same time, the support of flue is checked. The results show that due to the high sulfur content of coal, some flue supports have been corroded and broken, and the shell of induced draft fan has been seriously deformed, which also confirms the speculation that the vibration of flue is caused by its own lack of stiffness, so it has been replaced and strengthened.

From June, 5438 to October, 2000, after the overhaul, there was no more flue vibration and dust accumulation in induced draft fan, and the power consumption of blower and induced draft fan decreased, which ensured the safe and economic operation of the unit.