Mechanical seal technology and its application

Mechanical seal is a device used to solve the sealing problem between the rotating shaft and the body. It is widely used in various fluid machinery and power machinery in modern industry. The basic principle of mechanical seal is to provide appropriate elastic force through elastic elements, so that the sealing end faces of the moving ring and the stationary ring are closely combined to prevent fluid leakage. This sealing technology has become an indispensable part of many industrial equipment because of its good sealing performance, long service life, small power loss and other characteristics.

The basic components of mechanical seal include four main parts: a pair of sealing end faces, compensation buffer mechanism, auxiliary sealing mechanism and drive mechanism. The sealing end face is composed of the moving ring and the stationary ring, which is the core component of the mechanical seal. During operation, the pre tightening force provided by the elastic element (such as spring) makes the sealing end faces of the moving ring and the stationary ring closely contact to form the initial seal. With the operation of the equipment, the medium pressure further compresses the sealing end face to ensure the reliability of the seal.

The sealing performance of mechanical seal not only depends on the precise processing of the sealing end face, but also is closely related to the function of the auxiliary sealing ring. The auxiliary sealing ring is used to prevent the medium from leaking along the gap between the moving ring and the shaft, as well as the gap between the stationary ring and the end cover. These sealing rings remain basically stationary during operation and belong to the category of static seals. Therefore, their materials and structures have an important impact on the sealing effect.

Dry gas seal is a special form of mechanical seal technology, which is widely used in high-speed and high-pressure fluid machinery. The working principle of dry gas seal is similar to that of traditional mechanical seal, but its sealing end face is separated by an extremely thin gas film to form a non-contact state.

This gas film generates sufficient pressure through the hydrodynamic pressure effect to separate the moving ring and the stationary ring, thus avoiding end face wear and extending the service life. The structure of dry gas seal generally includes static ring, dynamic ring assembly, auxiliary seal O-ring, spring and spring seat, etc. The special spiral groove is designed on the moving ring assembly. With the rotation of the rotor, the gas is pumped to the root of the spiral groove to form a stable gas film. The superiority of dry gas seal lies in its non-contact characteristics, which is suitable for high PV working conditions, and has the advantages of small leakage, long service life and so on. There are various structural forms of dry gas seal in practical application, such as single end face dry gas seal, tandem dry gas seal, tandem dry gas seal with intermediate gas supply and double end face dry gas seal. Each structural form is designed according to different working conditions to ensure effective sealing under various complex conditions. For example, the tandem dry gas seal improves the reliability and safety of the seal through a multi-stage sealin structure, which is suitable for occasions where a large amount of process gas leakage is not allowed. 

The continuous progress of mechanical seal and dry gas seal technology has provided strong support for the development of modern industry. Both traditional mechanical seals and advanced dry gas seals play an important role in preventing fluid leakage, improving equipment efficiency, and prolonging equipment service life. In the future, with the continuous emergence of new materials and technologies, mechanical seal technology will continue to develop in the direction of more efficient and more reliable, providing a more solid guarantee for the stable operation of industrial equipment.