Hydrostatic and hydrodynamic combined type three-stage mechanical seal device for nuclear main pump

Abstract

The invention relates to a hydrostatic and hydrodynamic combined type three-stage mechanical seal device for a nuclear main pump, which comprises three-stage seals connected in series and is characterized in that the first-stage seal is a hydrostatic mechanical seal, the second-stage seal is a hydrodynamic mechanical seal, and the third-stage seal is a contact type mechanical seal. In the second-stage hydrodynamic mechanical seal, on the sealing end surface of a second-stage seal dynamic ring or a second-stage seal static ring, a plurality of groups of fluid shaped grooves which are uniformlydistributed along the circumferential direction are arranged outside the sealing end surface, and each group of shaped grooves comprise an arc groove and a left inclined groove and a right inclined groove which are symmetrically distributed by using the arc groove as a center. In the invention, when the nuclear main pump is in the normal working state, the first-stage hydrostatic mechanical seal bears most of the pressure of the system and runs stably; and after the first-stage seal fails, the second-stage mechanical seal completely can bear the pressure of the whole system and run stably andreliably.

Description

technical field [0001] The invention relates to a mechanical seal device for a nuclear main pump, more specifically, to a mechanical seal device for a nuclear power plant reactor coolant pump. Background technique [0002] The mechanical seal is an indispensable part of the fluid rotating machine, used to prevent the medium from leaking along the gap between the rotating shaft and the housing, and its sealing performance directly affects and determines the working performance of the main engine. Mechanical seals are divided into contact mechanical seals and non-contact mechanical seals. Among them, non-contact mechanical seals are divided into hydrostatic and hydrodynamic mechanical seals. The principle of the hydrostatic mechanical seal is: a sealing end face of the mechanical seal is set as a special geometric gap. When the mechanical seal is in a static state, the pressure fluid can enter the sealing surface, and the hydrostatic pressure is generated by the pressure drop ...

AI Technical Summary

Problems solved by technology

But the disadvantages are: the hydrodynamic pressure effect cannot be established during the pump start and stop stages, and there is a short-term friction and wear problem on the sealing surface. In addition, the leakage of the third-stage seal is still radioactive coolant medium

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