JPH034795Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a roots blower for nuclear power generation facilities, and is a simple blower used to suck air samples near the reactor core and guide them to radioactivity detection equipment. Stage~
A multi-stage Roots blower is used to ensure that even if the sample is contaminated with radioactivity, it will not leak from the housing and contaminate the outside air.

(Prior technology) In nuclear power generation facilities, radioactivity equipment is used to detect leakage of radioactivity into the outside air near the reactor core. Single to several stages of blowers are used to guide the air. However, conventional blowers use oil seals, mechanical seals, etc. to seal the rotor drive shaft, which requires the use of oil as the shaft sealing material, and if radioactivity adheres to the shaft sealing oil. There is a risk that oil gas containing radioactivity will be released into the atmosphere and cause radioactivity problems. Another drawback is that treatment facilities are required after removing radioactivity from the oil, which increases costs.

(Problems to be solved by the present invention/purpose of the invention) Blower that does not use shaft sealing oil has single-stage to
A multi-stage roots blower is most suitable. However, one of the rotor drive shafts of a Roots blower is driven by a motor shaft, and the other rotor shaft is interlocked in the meshing direction by a timing gear, so that the one drive shaft is completely sealed and the air to be sucked is Although it is almost impossible to prevent sample leakage at all, if the radioactivity detection equipment discovers that the aspirated sample air is contaminated with radioactivity, radioactivity may be released from the Roots blower. Even if we take immediate action to stop the reactor operation, there will of course be a delay of several hours, and the Roots blower operation will have to be stopped to remove the sample air. It is also impossible for safety reasons to interrupt suction.
In order to deal with such a case, the present invention aims to configure the Roots blower so that the suction sample air does not leak.

(Means for solving the problems) The present invention has a configuration that meets the above objectives,
A driven yoke with a driven magnet inserted into the drive shaft of one Roots rotor is fixed, and a can that surrounds and seals the yoke is attached to the drive shaft to prevent leakage of the sucked air sample from near the core of the reactor. The drive yoke is fixed to the seal case on the housing side, and a drive yoke with a drive magnet inserted is fixed to the motor shaft, and the drive yoke is rotated around the outer periphery of the can, and the driven yoke is rotated in conjunction with the drive yoke. This Roots blower for nuclear reactor power generation facilities has a structure that does not leak suction sample air at all, although it has some disadvantages in pump efficiency.

(Embodiment) A preferred embodiment of the present invention will be described with reference to the accompanying drawings.

The figure shows a three-stage Roots blower 1, in which the casing 2 is divided into a first stage chamber 5, a second stage chamber
It is divided into a tiered chamber 6 and a third tiered chamber 7, and each tiered chamber 5, 6,
Roots-type rotors that rotate in the meshing direction are fitted on the left and right sides of 7, and a drive type rotor drive shaft 8 is passed through one rotor of each stage chamber, and a driven type rotor drive shaft (not shown) is passed through the other rotor. , each drive shaft is passed through the housings 9 and 10 on both sides of the casing, each is sealed with oil by an oil seal 11 and supported by a bearing 12, a gear cover 13 is attached to the outside of the housing 9, and oil is applied to the housing 9 of the gear cover 13 on each drive shaft. Stop collar 1
4, and a timing gear 15 is fixed to each drive shaft through the collar 14. In addition, a sample collection pipe (not shown) that passes through the air chamber near the core of the reactor is connected to the suction port of the first stage chamber 6, and the discharge port of the same chamber 6 is connected to the suction port of the second stage chamber 6 by a pipe or the like 16. and connect the discharge port of the same chamber 6 with a pipe etc. 17,
It is connected to the suction port of the third stage chamber 7, and the discharge port of the same chamber 7 is connected to the radioactivity detection equipment through a pipe or the like.

In addition, a seal case 21 is attached to the end face of the housing 10.
A driven yoke 22 in which an annular driven magnet 23 is inserted is attached to the rotor drive shaft 8 protruding from the case 21, and a synthetic resin can 24 that covers the circumferential surface and end surface of the yoke 22 is fixed to the seal case 21. do. 25 is a motor, and a motor shaft 26 is concentric with the rotor drive shaft 8.
A drive yoke 27 into which an annular drive magnet 28 is inserted is attached to the drive yoke 27. Driven magnet 23
and the drive magnet 28 have opposite polarities on their corresponding surfaces via the can 24. 29 is the outer periphery of the drive yoke and the motor case and housing 10
It is a yoke cover with both ends fixed to.

A gas purge circuit 3 that maintains the inside and outside of each bearing 12 of the housings 9 and 10 at the same pressure.
1,32 can be provided.

(Function) The present invention has a discharge port for sending radiation to a radioactivity detection device in the casing 2 and a seal case 21 on the housing 10 side.
The can 24 is fixed to the driven yoke 22 and surrounds the driven yoke 22.
The can 24 prevents the suction air sample from leaking into the outside air, and the motor 25 controls the rotation of the rotor drive shaft 8 via the seal case 21 between the drive yoke 2 and the drive yoke 2 facing the outer periphery.
7, the driven magnet 23 inserted into the driven yoke 22 provided on the inner periphery of the seal case and attached to the rotor drive shaft 8 is rotated in the opposite direction.

(Effects) The present invention uses a can 24 that is pivotally supported by the housing 10 of the rotor drive shaft 8 and is fixed to a seal case 21 whose end is attached to the end face of the housing 10, so that the sample air sucked from near the core of the reactor is The rotation of the rotor drive shaft 8 by the motor shaft 16 is rotated by the drive magnet 28 of the drive yoke 27 attached to the motor shaft 26 on the outer periphery of the can 24.
As a result, the rotor drive shaft 8 is
The driven magnet 23 of the driven yoke 22 attached to
Since the rotor drive shaft 8 can be rotated in a subordinate manner, the rotor drive shaft 8 can be rotated while completely preventing the leakage into the outside air, thereby achieving the effect of providing an oil-less roots blower for use in nuclear power generation facilities as intended. Motsu.

[Brief explanation of the drawing]

The accompanying drawing is a partially cutaway side view showing an embodiment of the present invention. 1... Roots blower, 2... Casing, 8
...Rotor drive shaft, 10...Housing, 21...
... Seal case, 22 ... Driven yoke, 23 ...
Driven magnet, 24...Can, 26...Motor shaft, 27...Drive yoke, 28...Drive magnet, 29...Yoke cover.

Claims (1)

[Scope of utility model registration request] A driven yoke with a driven magnet inserted into the drive shaft of one Roots rotor is fixed, and a can that surrounds and seals the yoke is attached to the drive shaft to prevent leakage of the sucked air sample from near the core of the reactor. The drive yoke is fixed to the seal case on the housing side, and a drive yoke with a drive magnet inserted is fixed to the motor shaft, and the drive yoke is rotated around the outer periphery of the can, and the driven yoke is rotated in conjunction with the drive yoke. Roots blower for nuclear power generation facilities.