An overview of dry gas seal

Dry gas seal At the end of 1960s from the gas dynamic development of a new type of non-contact pressure bearing on the basis of the seal. The sealing principle of the use of fluid dynamics, the seals to achieve non-contact operation by dynamic pressure groove on the sealing end surface and. After several years of research, the British John crane company in the late seventy's first dry gas seal will be applied to offshore platforms for gas transportation equipment, and success. Dry gas seal is the first to address the issue of high-speed centrifugal compressor seal, the sealing non-contact operation, the seal friction material from the PV value of the basic restrictions, especially suitable for high speed and high pressure seal device. With the dry gas seal technology has become more sophisticated, increasingly broad range of applications, at present, is gradually dry gas seal in centrifugal pump and agitator are applied. In a word, where the use of mechanical seals can be used the occasion of dry gas seal. Compared with mechanical seal, dry gas seal has the following advantages:

1, sealing and long service life, stable and reliable operation;

2, the sealing power consumption is small, only about 5% of the contact type mechanical seal;

3, compared with other non-contact seal, dry gas seal a small amount of gas leakage;

4, can achieve zero emission of medium, is a kind of environmental protection type seal;

5, the auxiliary seal system is simple and reliable, does not require the use of maintenance;

Two, the centrifugal pump with dry gas seal

Centrifugal pump for liquid media. According to different condition, can adopt the following seal form:

1, double face dry gas seal

Double face dry gas seal seal can be used in most of the centrifugal pump, it has the following characteristics:

1) "gas block" instead of traditional "liquid blocking" principle, which uses sealing gas instead of sealing liquid with pressure with pressure, to ensure the realization of "zero emission process medium";

2) set of non-contact sealing operation, the power consumption of the seal is only for the traditional double end 5%, service life is 5 times longer than traditional seal;

3) auxiliary system has the advantages of simple structure, ensure the process medium is not contaminated and process medium leakage to atmosphere, completely get rid of the dependence on traditional double mechanical seal oil system. Seal gas using industrial nitrogen or industrial wind instrument, the medium pressure is higher than 0.15 0.2MPa.

Deficiency of pump with double face dry gas seal is:

1) need some pressure on the air, the air pressure is higher than the medium pressure of at least 0.2MPa;

2) trace gas into the process.

2, the tandem dry gas seal

Pump with tandem dry gas seal has the following characteristics:

1) dry gas seal and mechanical seal contact series mechanical seal, main seal, dry gas seal for sealing;

2) dry gas seal and the main seal between introducing nitrogen, ensure that the main seal has a certain pressure, greatly extend the service life of the main seal;

3) the main sealing process with medium leakage sealing gas discharged into the torch, ensure the process medium leakage to atmosphere, is a kind of environmental protection type seal;

4) the main seal, dry gas seal in a short period of time to play the role of the main seal to prevent leakage of large amount of process medium to the atmosphere.

5) the seal on the service life of the mechanical seal on the service life, usually in the 2 - 3 years.

6) the seal is mainly used for volatile medium occasions, such as liquid hydrocarbon medium; not high seal gas pressure.

The seal is inadequate:

1) the dry gas seal is not the full sense of the seal, the overall performance of a mechanical seal and dry gas seal.

2) the seals for volatile medium occasions, using a narrow range.