JPH04310254A - Solid-liquid centrifugal separator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to, for example, centrifugation of a liquid to be separated containing solid particles obtained by dissolving spent nuclear fuel used in a reactor of a nuclear power plant into solid particles and a solution (processing liquid). The present invention relates to a solid-liquid centrifugal separator, and particularly relates to a vibration damping device in this solid-liquid centrifugal separator.

0002

[Prior Art] In general, in the reprocessing of spent nuclear fuel used in reactors of nuclear power plants, solid fine particles of insoluble nuclear fission products are separated from a nitric acid solution in which spent nuclear fuel is dissolved by centrifugation. A solid-liquid centrifuge is used to extract the liquid.

A solid-liquid centrifuge of this kind that has already been proposed is constructed as shown in FIG.

That is, in FIG. 10, a separation container main body 2 is vertically installed at the bottom of a pedestal 1 having a through hole 1a, and a supply pipe for the liquid to be separated ( A waste liquid introduction nozzle 3a and a cleaning nozzle 3b are provided to extend near the through hole 1a and supply the liquid to be separated into a rotating container 13, which will be described later. Further, a solid (crud) discharge port 4 is provided at the lower end 2b of the separation container main body 2, and the centrifuged solids are discharged from the discharge port 4 to the outside of the machine. . moreover,
A guide wheel plate 5 is attached to the upper part 2c of the separation container main body 2 with a slight inclination so as to guide the processing liquid.
At the middle 2d of the separation container main body 2, a processing liquid receiving tray 6 is provided.
is formed. Furthermore, a discharge port (processing liquid discharge port) 7 is attached to a part of the processing liquid receiving pan 6, and a bearing stand 8a is provided on the pedestal 1. Further, a bearing housing 8 is provided on the upper part of this bearing stand 8a, and a drive motor 9 is installed in this bearing housing 8.
is installed upside down. Further, a pair of upper and lower rolling bearings 1 are provided at the upper and lower portions of the bearing stand 8a and the bearing housing 8.
0a and 10b are provided, and these rolling bearings 10
A rotary shaft 11 is cantilevered and rotatably mounted on a and 10b. Further, an output shaft 9a of the drive motor 9 is connected to an upper part 11a of the rotating shaft 11 via a flexible coupling 12, and a rotating container 13 having a flange 13a is connected to a lower part 11b of the rotating shaft 11.
is pivoted so as to surround the supply pipe 3a for the liquid to be separated and the cleaning nozzle 3b. Furthermore, a plurality of (four in the figure) discharge holes 14 are radially bored in the upper part of the rotating container 13 so that the processing liquid is guided by the guide ring plate 5.

On the other hand, a buffer spring and an oil damper (both not shown) are installed radially in parallel between the inside of the bearing housing 8 and the rotating shaft 11.
The buffer spring and oil damper suppress displacement of the rotating container 13 within the gap formed between the rotating container 13 and the separation container main body 2 when subjected to vibration. .

That is, the rotating shaft 11 by the rotating container 13
The primary natural vibration mode is a pendulum vibration mode in which the bearing portion 10b is zero and the tip of the spherical portion has a maximum displacement. Although the frequency of this first natural vibration mode depends on the magnitude of the spring constant of the spring, it is usually set to several Hz in order to allow the vibration to pass in a low speed range. The displacement of 13 is suppressed.

Therefore, when the solid-liquid centrifuge described above drives the drive motor 9 during operation, the drive motor 9
Since the rotating shaft 11 connected to the output shaft 9a of the rotary shaft 11 rotates at high speed together with the rotating container 13 mounted on the rotating shaft 11, the liquid to be separated supplied from the supply pipe 3a to the rotating container 13 is preliminarily converted into a solid (solid). The separated solids (crud) are discharged from the crud outlet 13b of the rotary container 13 and the discharge port 4.

On the other hand, although the processing liquid centrifuged from the liquid to be separated is temporarily collected in the processing liquid receiving tray 6 of the rotating container 13, it is discharged to the outside of the machine from the above-mentioned discharge port (processing liquid discharge port) 7.

That is, as shown in FIG. 11, the processing liquid centrifuged from the liquid to be separated moves in the axial direction of the rotating container 13, and is reflected by the top plate and flange 13a of the rotating container 13, causing vibrations. do. In other words, when the wave crest moves toward the top plate, some of the processing liquid is discharged outside the machine from the above-mentioned discharge port (processing liquid discharge port) 7, but most of the processing liquid moves downward as reflected waves. It has been confirmed through experiments that fluid force can be generated.

Furthermore, the graph shown in FIG. 12 is a graph showing the relationship between the rotational speed of the rotating container 13 and the frequency of shaft vibration. The vertical axis shows the frequency of shaft vibration occurring at each rotational speed, and this graph shows the frequency of shaft vibration occurring during operation of the solid-liquid centrifuge described above.

That is, as shown in FIG. 12, in the rotational speed (a) region, the fluid moves in the circumferential direction (s, k).
= (2, 0) component and rotation synchronous component occur, and in the rotational speed (c) region, the fluid moves in the axial direction (s, k)
= (0, 1) component and a rotation synchronous component are generated, and in the rotation speed (b) region, both components of the rotation speed (a) region and (c) region are generated, which may cause large vibrations. be.

The reason why the shaft vibration increases as described above is due to the processing liquid centrifuged in the rotating container 13.

[0013]

[Problems to be Solved by the Invention] In the solid-liquid centrifuge described above, when a solution accumulates in the rotating container 13, the fluid force of this solution causes the rotating shaft 11 to vibrate. The vibration is much larger than that of normal rotational synchronization, and it not only poses a risk of making it impossible to operate, but also
When the vibration of the rotating shaft 11 becomes intense, this rotating shaft 11
Each of the bearings 10a and 10b that supports the shaft generates a large reaction force in proportion to the shaft vibration, and due to this, each of the bearings 10a and 10b that supports the
There is a possibility that the lifespan of the components a and 10b will be significantly shortened.

The present invention has been made in view of the above-mentioned circumstances, and actively suppresses the vibration of the rotating shaft due to the fluid force of the solution in the rotating container, thereby extending the life of each bearing. An object of the present invention is to provide a solid-liquid centrifugal separator that improves the operating efficiency of centrifugal separation and also improves the reliability and safety of rolling bearings.

[0015]

[Means for Solving the Problems] The present invention provides a separation container body having a discharge port vertically disposed on a pedestal, a bearing housing provided on a bearing stand of the pedestal, and a rotating shaft passed through the pedestal in the bearing housing. A rotary container having a discharge port is mounted on the rotary shaft so as to be cantilevered into the separation container body, and a supply pipe is connected to the separation container body to supply the liquid to be separated into the rotation container. A circumferential groove is formed in the rotating container, and a plurality of partition plates are provided radially within the circumferential groove,
A ring bottom cylindrical portion is formed in the lower part of the rotating container.

[0016]

[Operation] When the rotating container rotates at an ultra-high speed, the present invention
The vibration of the rotating shaft caused by the fluid force inside the rotating container is actively suppressed by the circumferential groove and multiple partition plates in the rotating container, as well as the ring bottom cylinder formed at the bottom of the rotating container, thereby extending the life of the bearing. It is designed to be significantly longer in order to improve the reliability and safety of the bearing.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

The present invention will be described with the same reference numerals attached to the same constituent members as in the above-described specific example.

In FIGS. 1 to 5, reference numeral 1 denotes a pedestal having a through hole 1a, and a separation container body 2 is vertically disposed at the bottom of this pedestal 1. 2a includes a supply pipe (waste liquid introduction nozzle) 3 for the liquid to be separated.
A and a cleaning nozzle 3b are provided so as to extend near the through hole 1a and supply the liquid to be separated into a rotating container 13, which will be described later. Also, the lower end 2b of the separation container main body 2
is provided with a discharge port (discharge port) 4 for separating liquid,
The centrifuged solid (crud) is discharged out of the machine from this discharge port 4. Further, on the upper part 2c of the separation container main body 2, a guide wheel plate 5 is arranged to hold the processing liquid (solution).
The processing liquid receiving tray 6 is formed in the middle 2d of the separation container main body 2. Furthermore, a part of the processing liquid receiving tray 6 is provided with a discharge port (processing liquid discharge port) 7.
A bearing stand 8a is provided on the pedestal 1. or,
A bearing housing 8 is provided on the upper part of this bearing stand 8a, and a drive motor 9 is installed in a reclining manner in this bearing housing 8. Further, a pair of upper and lower rolling bearings 10 are provided at the upper and lower parts of the bearing stand 8a and the bearing housing 8.
a and 10b are provided, and both rolling bearings 10a
, 10b, a rotating shaft 11 is rotatably mounted in a cantilever manner. Furthermore, in the upper part 11a of this rotating shaft 11,
An output shaft 9a of the drive motor 9 is connected via a flexible coupling 12, and a rotating container 13 is connected to the supply pipe 3 of the liquid to be separated at the lower part 11b of the rotating shaft 11.
a and the cleaning nozzle 3b. Furthermore, a plurality of (four in the figure) discharge holes 14 are radially bored in the upper outer periphery of the rotating container 13 so that the processing liquid is guided by the guide wheel plate 5.

In particular, as shown in FIGS. 2 to 4, the rotary container 13 has an upper circumferential groove 20a and a middle circumferential groove 20b.
A plurality of partition plates 21 are provided radially within the middle circumferential groove 20b so as to restrict movement of the processing liquid in the circumferential direction. Further, a ring bottom cylindrical part 22 is formed in the lower part of the rotating container 13, and as shown in FIGS. When the liquid moves in the axial direction of the rotating container 13, the rotating container 1
The vibrations are inverted and damped by the top plate 3 and the ring bottom cylindrical portion 22. That is, when the crest of the wave moves toward the top plate, most of the processing liquid accumulates in the upper circumferential groove 20a, and is then discharged to the outside of the machine from the discharge port (processing liquid discharge port) 7. Further, although a small amount of the remaining processing liquid moves downward as a reflected wave and hits the ring bottom cylinder portion 22, this reflection force is suppressed by the gravity of the processing liquid and damped.

On the other hand, FIG. 5 shows the relationship between the circumferential vibration mode and the axial vibration mode of the rotating container 13, and shows the shape of the free surface of the internal fluid of the rotating container 13. As is clear from this figure, since the plurality of partition plates 21 are provided radially to restrict the movement of the processing liquid in the circumferential direction, the processing inside the rotating container 13 is The liquid no longer moves in the circumferential direction.

Next, the present invention will be explained using mathematical formulas.

That is, as shown in FIGS. 6 and 7, when the processing liquid centrifuged from the liquid to be separated moves in the axial direction of the rotating container 13, the top plate of the rotating container 13 and the ring bottom cylinder However, when the processing liquid moves over the partition ring 20c and moves to the upper circumferential groove 20a, the magnitude of the vibration in the axial direction depends on the natural frequency of the shaft system and the flow. It depends on the degree of detuning from the frequency of physical strength, so the detuning is ±20% or more.

In other words, the fluctuation frequency of the processing liquid is as shown in FIG.
Using the signs of (a) and (b), this can be expressed mathematically as follows:
Equation 1 is obtained.

[0025]

[Equation 1] However, (j, k): number of nodes in L interval, number of nodes j in k interval, k = 1, 2, 3,... g: centrifugal acceleration g = D0 +Di
/4×ω2 L: Circumference length
L=D0 +Di /2N×πN: Number of partition plates b: Container length (length in axial direction) h
: Liquid depth ωn (j, k): It was found through experiments that this occurs at the fluctuation frequency (natural frequency) of the internal fluid at the number of (j, k) nodes.

This frequency is observed in a rotating coordinate system (a coordinate system rotating synchronously with a rotating axis), and when viewed in a stationary coordinate system, the frequency of fluctuation Ωn is the fluctuation The frequency Ωn (j, k) = ω±ω
n (j, k)......(2).

On the other hand, as shown in FIG. 9, a buffer spring 23 and an oil damper 24 are installed between the inside of the bearing stand 8 and the rotating shaft 11.
3 and the oil damper 24 are configured to suppress displacement of the rotating container 13 within the gap formed between the rotating container 13 and the separating container main body 2 when subjected to vibration.

That is, the natural vibration mode of the shaft system has the frequencies of the first natural vibration mode a and the second natural vibration mode b, and the fluid The fluctuation frequency Ωn (j, k) of ±
By creating a structure in which the shaft system is detuned by 20% or more, it is possible to operate within a range in which the response sensitivity of the shaft system is small, and it is possible to reduce shaft vibration.

[0029]

As described above, according to the present invention, a separation container main body having a discharge port is vertically disposed on a pedestal, a bearing housing is provided on a bearing stand of the pedestal, and a rotating shaft is attached to the bearing housing on the pedestal. A rotary container having a discharge port is rotatably attached to the rotary shaft, and a supply pipe is connected to the separation container main body to be separated into the rotary container. A circumferential groove is formed in the rotary container, a plurality of partition plates are provided radially within the circumferential groove, and a ring bottom cylindrical portion is formed in the lower part of the rotary container. Therefore, not only can the life of the bearing be significantly extended, but also the reliability and safety of the bearing can be improved.The structure is also simple, so it can be incorporated into existing equipment. have an effect.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a solid-liquid centrifuge of the present invention.

FIG. 2 is an enlarged sectional view of a rotating container incorporated into the solid-liquid centrifuge of the present invention.

FIG. 3 is a cross-sectional view taken along chain line A-A in FIG. 2;

FIG. 4 is a cross-sectional view taken along the chain line BB in FIG. 2.

FIG. 5 is a diagram for explaining the vibration mode of the rotating container of the solid-liquid centrifuge of the present invention.

FIG. 6 is a diagram for explaining the action of the rotating container of the solid-liquid centrifuge of the present invention.

FIG. 7 is a diagram for explaining the action of the rotating container of the solid-liquid centrifuge of the present invention.

FIGS. 8(a) and 8(b) are diagrams for explaining the mathematical formulas of the rotating container of the solid-liquid centrifuge of the present invention.

FIG. 9 is a diagram for explaining the mathematical formula of the rotating container of the solid-liquid centrifuge of the present invention.

FIG. 10 is a sectional view showing a solid-liquid centrifuge that has already been proposed.

FIG. 11 is a diagram for explaining the action of a rotating container of a solid-liquid centrifuge that has already been proposed.

FIG. 12 is a graph showing the relationship between the rotation speed and the frequency of shaft vibration of a solid-liquid centrifuge that has already been proposed.

[Explanation of symbols]

1 Mount 2 Separator body 8a Bearing stand 8 Bearing housing 11 Rotation axis 13 Rotating container 14 Discharge hole 20a Upper peripheral groove 20b Middle circumference groove 21 Partition plate 22　Ring bottom cylinder part

Claims (1)

[Claims] Claims: 1. A separation container main body having a discharge port vertically arranged on a pedestal; a bearing housing provided on a bearing stand of the mount; A rotating shaft that is rotatably mounted on the handle,
a rotating container having a discharge port mounted on the rotating shaft; a supply pipe disposed in the separation container main body so as to supply a liquid to be separated into the rotating container; and a supply pipe formed in the rotating container. A solid-liquid centrifuge comprising: a circumferential groove; a plurality of partition plates provided radially within the circumferential groove; and a ring bottom cylindrical portion formed at a lower portion of the rotating container.