Centrifugal fans are used in the induced draft fans of dust removal equipment in many manufacturers. However, as the use time increases, the centrifugal fans will experience vibration and imbalance. The main reason for this phenomenon is the scaling on the surface of the impeller. The fan load is increased, and the air induction effect of the gas is also affected. What are the methods to solve the scaling of the centrifugal fan impeller?
1) Causes and effects of scaling of centrifugal fan impellers
Centrifugal fans that are prone to impeller scaling are mainly used for the induced draft work of wet dust removal equipment. The flue gas purified by the wet dust removal device has a high humidity. Although the unremoved dust particles are small, the viscosity is very high. When they pass through the centrifugal fan, they will be adsorbed on the non-working surface of the blade under the action of the gas vortex, especially at the inlet and outlet of the non-working surface, serious dust fouling will be formed and gradually thickened. When part of the dust falls off under the combined action of centrifugal force and vibration, the balance of the impeller will be destroyed, and the entire centrifugal fan will generate stronger vibration, thereby affecting the draft effect.
2)the solution to the centrifugal fan impeller scaling method
1. Water spray for descaling
Water spray descaling is a commonly used impeller descaling method. The water spray system is installed on the casing of the centrifugal fan and consists of pipes, 3 nozzles (1 at the outlet of the impeller and 2 at the inlet) and drainage holes. . The water source is generally tap water with a pressure of about 0.3MPa. This method is usually effective, but the disadvantage is that it takes a long time for descaling each time it is shut down, and it needs to be shut down several times a month for descaling, which affects the normal use of the unit.
2. High pressure gas descaling
The high-pressure gas descaling system adopts a structure similar to that of the water spray system, but its pipeline is a high-pressure pipeline, a special nozzle and a high-pressure gas source. This kind of device can quickly and effectively descale the blades. It can turn on the high-pressure air source during the normal shutdown of the centrifugal fan, and the descaler can be completed in only tens of seconds. Due to the simple and convenient operation, it can be carried out many times a day, which not only solves the laborious and time-consuming problem of manual descaling, but also significantly reduces the production cost of the entire unit. The main problem of this system is whether the user has an existing high-pressure gas source (the pressure is between 0.8 and 1.5MPa, and compressed air or nitrogen can be used), otherwise, special high-pressure compressor equipment is required.
3. Air flow continuously purging and descaling
Structurally, the continuous purging device does not require an external air source. It uses the exhaust pressure of the centrifugal fan itself to lead a small amount of flue gas (1%~2% of the rated air volume) from the inside of the centrifugal fan to the special nozzle. The nozzle is located at the inlet of the impeller, which coughs the flue gas to the non-working surface of the blade at a high speed. This purging is continuous. It starts with the opening of the centrifugal fan, not only can it just stick to the blade. The dust is blown off, and it can also prevent the accumulation of dust and thickening, and there is no need to stop the machine for descaling. The device has a simple structure, little modification to the centrifugal fan, and good anti-scaling effect.
