Shaft seal of nuclear grade centrifugal fan

Abstract

The invention discloses a shaft seal of a nuclear grade centrifugal fan. The shaft seal comprises a transmission shaft and a fan volute. A flow guiding air returning cavity wrapped by a flow guiding air returning cavity casing is arranged on the right side of the fan volute, the fan volute and the flow guiding air returning cavity are in clearance fit with the transmission shaft, one end of an air returning pipe is further connected in the flow guiding air returning cavity, the other end of the air returning pipe is connected with a fan air inlet, sealing fillers are arranged at the right end of the flow guiding air returning cavity, the sealing fillers and the transmission shaft are matched closely, a sealing cover is arranged on the sealing fillers, and the sealing cover is further fixedly connected with the flow guiding air returning cavity casing. The shaft seal solves the problem in the prior art and has the advantages of being reasonable in structure, simple in maintaining, low in leakage quantity, safe and reliable and the like.

Description

[0001] technical field [0002] The invention relates to a shaft seal, in particular to a shaft seal of a nuclear-grade centrifugal fan. Background technique [0003] According to the provisions of Part BA of ASME AG 1-2003 of the US "Nuclear Air and Gas Handling Regulations" that are currently followed by fans in nuclear power plants in the world, the shaft leakage limit for centrifugal fans that transport radiant air or gas is: fan rated 0.01% of air volume / fan pressure per 249Pa, or less than 0.852m 3 / h, take the larger value of the two. Since there must be a certain gap between the rotating shaft of the centrifugal fan and the stationary volute, and there is a certain pressure difference inside and outside the volute (formed by the internal pressure of the fan and the external atmospheric pressure), the shaft must be sealed to prevent leakage If the amount exceeds the specified range, it will cause nuclear radioactive pollution. At present, it is known that the shaft...

AI Technical Summary

Problems solved by technology

The disadvantage is that it is not tightly sealed to the gas, the reliability is poor, and the leakage often exceeds the requirements of the above specifications; in addition, the pressing force required for installation is large, which is likely to cause running wear and heat, and the grease in the packing will flow out, requiring frequent adjustment or replacement. Packing, short maintenance intervals

Although the leakage prevention effect of the mechanical seal device in the blower and compressor is indeed very good, the mechanism is too complicated: an additional oil supply or air supply device is required for sealing. In recent years, another shaft seal has been used in other industries. Sealing structure - carbon ring seal also needs to add nitrogen to ensure the sealing effect, its disadvantages are the same as mechanical seals

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