Sealing Performance of Boiler Centrifugal Induction Fans

Sealing Performance of Boiler Centrifugal Induction Fans

The sealing performance of boiler centrifugal induction fans is one of the key indicators of operational reliability, particularly when transporting toxic, hazardous, flammable, explosive, or inert gases. Poor sealing not only results in significant loss of valuable gases but can also cause severe environmental pollution. Currently, there are generally four sealing methods used in boiler centrifugal induction fans. 1. Floating Ring Seals for Boiler Centrifugal Induction Fans Floating ring seals utilize the pressure oil film formed between the main shaft and the floating ring, balancing the combined pressure of the oil film with external loads (working fluid pressure) to prevent axial leakage of the working medium. Because floating ring seals have the advantage of automatic sensing, they can reduce the sealing gap and minimize leakage. Additionally, the pressure of the sealing element can be adjusted based on the pressure of the sealed medium, and the floating ring and shaft can maintain contact to prevent mechanical wear. This type of seal is used in high-pressure applications or when transporting corrosive gases to prevent gas leakage. 2. Mechanical Seals for Boiler Centrifugal Induction Fans A mechanical face seal is a sealing device that applies preload to the friction between the stationary ring and the rotating ring via an elastic element, and achieves sealing during shaft rotation through the pressure of the compressing medium and the elastic element. Mechanical seals generally use a sealing fluid (turbine oil) with a pressure 2.5 to 3.5 times higher than that of the sealed medium. During rotation, an oil film forms on the friction surfaces. The pressure of the oil film decreases from the outer side to the inner side, reaching equilibrium with the sealing material. Since the pressure of the sealing fluid is always higher than that of the sealing material, the sealing material typically does not leak; however, the sealing fluid leaks slightly toward the inner side, and the leaked fluid is recirculated through the oil return port. Due to design differences, mechanical seals contain significantly less oil than floating seals, but both are oil-film seals. 3. Dry Gas Seals for Boiler Centrifugal Inducer Fans Dry gas seals are a type of gas film seal and represent one of the most advanced sealing technologies used in turbo compressors to achieve high sealing performance. They utilize nitrogen or other inert gases as the sealing medium. The sealing gas must be of high purity, and the gas supply system is complex.