In some thermal power plants in our country, there are frequent issues with boilerInduced draft fanash accumulation and vibration. Therefore, it is necessary to frequently shut down the induced draft fan and clean the dust during operation, which not only limits and affects the output of the unit but can sometimes even lead to accidents due to excessive vibration of the induced draft fan. There are many factors that cause ash accumulation and vibration in the induced draft fan, which are usually directly related to the type of induced draft fan, the type of dust collector installed in front of the fan, the type of coal, and the operating mode.

　　Typically, during the operation of the induced draft fan, due to reasons such as gas vortex, rough surface of the blades, and Brownian motion of dust particles, dust tends to accumulate on the non-working surfaces of the fan blades. Experiments have shown that the blade profile of the induced draft fan has a certain impact on the degree of dust accumulation. The induced draft fans assembled in the first phase of our company consist of three machines and are single-suction centrifugal fans with backward-swept hollow blades; the second phase unitsInduced draft fanare double-suction centrifugal fans with front flat plate structure. In actual operation, the structure of the first-stage airfoil induced draft fan is more prone to dust accumulation and vibration than the second-stage fan. However, for the same type of induced draft fans with different impeller diameters, larger diameter impellers are more likely to experience imbalance and vibration.

　　In addition, for airfoil hollow blade induced draft fans, once the blades wear during operation, dust particles can enter the blade cavity, quickly damaging the dynamic balance of the induced draft fan rotor and causing vibration. If this occurs, even if there is no dust on the blades, the vibration of the fan cannot be eliminated.

　　The amount of dust accumulation and adhesion strength on the non-working surfaces of the induced draft fan blades is closely related toInduced draft fanthe type and efficiency of the dust collector used in the front. Generally speaking, loosely bound dust with lower strength will adhere to the blades of dry dust collectors, while cement-like hard dust will adhere to the non-working surfaces of the blades of wet dust collectors; using high-efficiency dust collectors (such as electrostatic precipitators, bag filters, etc.) can significantly reduce the degree of dust accumulation on the induced draft fan blades.

　　Wet dust collectors can cause serious moisture issues in the flue gas entering the induced draft fan. This is because, during the operation of the water film dust collector, some tiny water droplets are carried into the induced draft fan along with the dust in the flue gas. At the same time, if the ambient air temperature is low, the water vapor entering the induced draft fan with the flue gas will condense and mix with the dust, forming a mortar that adheres to the blades. Most of this mortar sticks to the non-working surfaces of the fan blades and the front and rear discs of the impeller. During the operation of the induced draft fan, the moisture contained in the mortar will gradually evaporate, forming a relatively hard ash shell that gradually thickens. When the dust on the induced draft fan blades reaches a certain mass, under the combined action of its own weight and the centrifugal force of rotation, some dust blocks will fall off, disrupting the balance of the induced draft fan rotor and causing vibration. When the amount of dust removal water is excessive during operation, or when the dust collector frequently clogs, or during sudden changes in ambient temperature and humid seasons, the amount of water carried by the flue gas in the water film dust collector will increase.