JPS59348A - Centrifugal separator - Google Patents

Abstract

PURPOSE:To prevent the contact of a shaft and a shield wall when earthquake occurs, by a mechanism wherein a spherical surface seat is mounted to the lower part of a bearing cylinder while a spherical surface part engaged therewith is provided in a bearing box and the shaft amplitude of a shield wall piercing part is minimized. CONSTITUTION:A centrifugal separator consists of a shaft 6 having a rotor 5 secured to the lower end thereof and downwardly extended into a shield wall 1 from the piercing hole 14 thereof and a bearing cylinder 7 supporting said shaft 6 in a freely revolvable manner. The aforementioned bearing cylinder 7 is provided in the bearing box 3 provided on the upper surface of the shield wall 1 wile the bearing box 3 has an upwardry convexed sherical surface part 16 and the bearing cylinder 7 is supported by a downwardly concaved spherical surface seat 17 engaged with said spherical surface part 16. In this case, each center of radius of curvature 18 of the aforementioned spherical surface part 16 and the spherical surface seat 17 is made present within the wall thickness of the wall 1. In addition, the aforementioned hole 14 is formed into a hand drum shape and the part corresponding to the aforementioned center of radius of curvature 18 is brought to a min. diameter to position the center of radius of curvature 18 above the center of gravity 19 of an axis.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to centrifugal separators such as centrifugal clarifiers and centrifugal extractors used in nuclear fuel reprocessing.

[Technical background of the invention]

In a nuclear fuel reprocessing plant, spent nuclear fuel is dissolved in nitric acid, and U (uranium) and P (plutonium) are extracted from this solution and recycled for use. In this reprocessing process, in order to avoid insoluble residues generated during the dissolution of nuclear fuel from entering the U and P extraction process, the insoluble residues are removed using a centrifugal clarifier or the like prior to the extraction process, and the solvent is then damaged by radioactivity. In order to reduce the amount, U and P are extracted using a centrifugal extractor.

A conventional centrifugal extractor has the configuration shown in FIG. That is, since the liquid to be treated has strong radioactivity, the rotary drive mechanism 2 and the rotary shaft bearing box 3 are provided above the shielding wall 1, and the liquid contact part 4 is provided below. As described above, since the rotational drive mechanism 2 is located above the shielding wall 1 and the liquid contact portion 4 is located below, the axial length of the shaft 6 that drives the rotating body 5 becomes long. Moreover, since the radiation level below the shielding wall 1 is extremely high, it is not possible to install a bearing that requires maintenance, and the shaft 6 is supported only near its upper end by a cantilever.

As a countermeasure against vibrations caused by the rotation of the shaft 6 and earthquakes, the bearing tube 7 in the bearing box 3 is provided with a downwardly convex spherical section 8 concentric with the bearing tube 7, and this spherical section 8 is connected to the bearing box. 3, thereby engaging the spherical seat 9 provided in the bearing tube 7.
It is possible to swing the head around the center of curvature of the spherical part 8. Note that a damper 11 is provided between the flange 9a of the spherical seat 9 and the flange of the bearing tube 7. Further, a rod 13 to which spring pressure is applied by a spring 12 is in contact with the lower end of the lower cylinder 9a of the spherical seat 9.

In the above configuration, by appropriately selecting the damper 11 and the spring 12, the critical speed of the shaft system, for example, the low-order critical speed, can be made sub-critical by setting it above the rated rotation speed.
This can be considered in terms of rotational performance.

[Problems with background technology]

In the conventional centrifugal extractor with the above configuration, the center of oscillation of the bearing tube 7 is located above the spherical seat 9 because the spherical seat 9 is concave upward and the spherical portion 8 is convex downward. The distance from the center of the axis to the lower end of the axis 6 is the dog. Therefore, the amount of displacement of the lower end of the shaft during an earthquake, that is, the amplitude of the oscillation, becomes too large, and the shaft 6 comes into contact with the through hole 14 of the shielding wall 1, which may cause a serious accident.

In order to prevent the above-mentioned contact, the diameter of the through hole 14 is set to a dog size,
Although the gap between the shaft 6 through hole 14 is narrowed, the spring 12
, either increase the constant of the damper 11 to limit the swing width, but the former poses a radiation shielding problem, and the latter loses the meaning of being able to swing due to the spherical part and spherical seat. Not only this, but also the bearing load increases, which is undesirable.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and aims to provide a centrifugal separator that has a critical speed of the shaft system, has sufficient earthquake resistance, and is free from the risk of the shaft coming into contact with the shielding wall penetration hole during an earthquake. The purpose is

[Summary of the Invention] In the present invention, the bearing tube is provided with a downwardly concave spherical seat, and the bearing box is provided with an upwardly convex spherical portion that engages with the spherical seat. has achieved its purpose.

[Embodiments of the invention]

In FIG. 2, the same parts as in FIG.
, an upwardly convex spherical portion] 6 is provided at its upper end, and a downwardly concave spherical seat 17 that engages with the spherical portion 16 is provided on the bearing tube 7.
is the provision. Spherical part 16 c7) 7 Rough') 16
A damper 11 is provided between a and the 7 runci at the upper part of the bearing tube 7. Note that a spring pressure is applied by a spring 12 to the lower end of the bearing cylinder 7, and a 7'ct''13 is brought into contact with the lower end.

In the centrifugal extractor of the present invention having the above configuration, since the spherical seat 17 is concave downward and the spherical part 16 is convex upward, the center of curvature 18 of these is below the spherical seat, and the axis 6 is centered at the center of curvature 18. Since the swing is performed centering on the shaft, the swing width at the lower end of the shaft can be made smaller than that of conventional centrifugal shaft extractors.

Therefore, even if the gap between the shaft 6 and the through hole 14 of the shielding wall 1 is small, there is no risk that the shaft 6 and the through hole 14 will come into contact during an earthquake.

Note that if the radius of curvature of the spherical portion 16 and the spherical seat 170 is appropriately selected so that the center of curvature 18 is located at the center of the upper and lower surfaces of the shielding wall 1, that is, at the center of the wall thickness, as shown in FIG. Since the amplitude of the opposing portion of the shielding wall IK during an earthquake can be minimized, the gap between one through hole 14 and the shaft 6 can be minimized, which is advantageous in terms of shielding. In addition, in the above case, since the shaft 6 is displaced point-symmetrically with respect to the center of curvature 18, the through hole 14 of the shielding wall 1 is made so that the portion facing the center of curvature 18 has the minimum diameter as shown in FIG. It should be possible to increase the permissible amplitude of the shaft 6 during an earthquake, and to minimize the increase in the amount of radiation leakage. Furthermore, if the center of curvature 18 is located above the center of gravity 19 of the shaft system, the shaft will not slip off the bottom of the spherical surface.

The invention is not limited to the above embodiments. That is, it can be applied not only to the exemplified centrifugal extractor but also to a centrifugal clarifier and the like.

〔Effect of the invention〕

In the centrifugal separator of the present invention having the above configuration, the center of the swing of the shaft during an earthquake is located below the spherical seat, and the swing width of the portion of the shaft that penetrates the shielding wall during an earthquake is small, so that the through-hole diameter Avoid contact between the shaft and the shield type without unnecessarily increasing the Therefore, the amount of increase in radiation leakage can be minimized.

Since the swing width is still limited without increasing the tamper or spring constant, the meaning of providing the spherical seat is not lost, and the bearing load does not increase.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional centrifugal extractor, FIG. 2 is a sectional view of an embodiment of the present invention, and FIG. 3 is a sectional view of a main part of a modification thereof. DESCRIPTION OF SYMBOLS 1... Shielding wall, 3... Bearing box, 4... Wetted part, 5... Rotating body, 6... Shaft, 8.16
... Spherical part, 9.17... Spherical seat, 10.18...
・Center of curvature, 11... Damper, 12... Spring,
13...Rod, 14...Through hole. Application agent Patent attorney Gobe Kikuchi#/l! 1 □ Shi1・kan2i1 2 31st I

Claims (1)

[Claims of Claims] (1) A rotating body is rotatably supported by a bearing cylinder in a bearing box provided on the soil surface of the shielding wall, extends below the shielding wall from a through hole in the shielding wall, and has a rotating body fixed to its lower end. The shaft having a shaft is characterized in that an upwardly convex spherical part is provided in the bearing box, and the bearing tube is supported by the spherical part by a concave spherical seat at the lower part 1 that engages with the spherical part. centrifuge. (2) The center of curvature of the spherical portion and the spherical seat is within the thickness of the shielding wall.
1(3) The centrifugal separator according to claim 1, characterized in that the center of curvature of the spherical portion and the spherical seat is located at the center of the wall thickness of the shield wall type. Machine. (4) The centrifugal separator according to Claims 2 and 3, wherein the through hole is of a conical shape with a minimum diameter at a portion facing the center of curvature. (5) The centrifugal separator according to any one of claims 1 to 4, wherein the center of curvature is located above the center of gravity of the shaft system.