JPS5927224B2 - Transfer device for magnetic powder and granules - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic powder transfer device that uses magnetism to transport and remove magnetic powder that has accumulated inside a pipe or the like and cannot be transported by a fluid.

For example, in the piping and tank equipment of the primary or secondary cooling water system of a nuclear power plant, fine particles generated from fuel rods, piping, etc. = CANADIAN REA
CTORUNKNOWNDEPO8IT) is often deposited.

The above cloud is mostly composed of magnetite (Fe304) and magnetite (γ-F e20.), which exhibit ferromagnetism.
It is composed of iron oxide fine particles containing hematite (α-Fe203), which is weakly magnetic, and has a considerably high radioactivity, so repair work or periodic maintenance work should be carried out in areas where this is accumulated. The risk of exposure to radiation is high and the work is dangerous.

Clouds tend to accumulate in places where the flow is slow, such as inside piping or tanks, and it has been revealed that clouds often accumulate in the cavity between the safe ent sozzle and the thermal sleeve, for example.

If workers approach the vicinity of such deposited areas to carry out the above-mentioned repair work or periodic inspection work, they will be forced to perform extremely dangerous work, and therefore, the daily work of workers for these works will be reduced. Regarding time, the amount of radiation exposure per hour is regulated by laws and regulations. It's not fun.

Previously, the idea was that clouds were insensitive to magnetism, so active countermeasures were not taken, but instead people approached the work area using materials such as lead to protect themselves from radiation.

However, this method requires a considerable number of man-hours for the shielding work, and has the disadvantage that the shielding material is placed in a narrow area around the reactor, which significantly impairs work efficiency.Furthermore, the shielding material is heavy. Therefore, it is inconvenient to handle (in terms of location) and poses a safety problem.

Therefore, it becomes necessary to remove the cloud from the deposited area, but in the case of atomic couplants, it is difficult to cut the sedge cap more than necessary due to structural or legal regulations, so it is necessary to use forced air blowing from the outside or jet cleaning. Cloud migration is almost impossible.

Therefore, in recent years, the present invention has developed a method of magnetically moving clouds based on the idea that ferromagnetic magnetite and magnetite fine particles are deposited by enclosing hematite, which is treated as a substantially non-magnetic material. has already been proposed.

On the other hand, known techniques include: ■ A method that generates a flat traveling magnetic field using three-phase alternating current used in linear motors, etc.; ■ A method that mechanically moves an alternating magnetic field generated by the rotation of an AC electromagnet, a DC electromagnet, or a permanent magnet. , ■ A method of mechanically moving a DC magnetic field using a DC electromagnet or permanent magnet.

However, the transfer efficiency of each of these methods & L cloud is at most 10%, and there are problems such as the need to enlarge the work space.

The purpose of the present invention is to solve the above-mentioned problems and to efficiently transport clouds and other magnetic particles that have accumulated in a space. A DC excitation device applies a magnetic field to magnetize the material, and a coil is installed at a winding angle of approximately 30 degrees in a slot on the outer circumference of the cylindrical magnetic material in order to transport the magnetic powder particles magnetized by the device using an alternating magnetic field. The present invention is characterized in that it uses a 3-Japanese pattern magnetic field generator arranged so as to form a V4 full-pitch winding.

Embodiments of the present invention will be described below with reference to the drawings.

The present invention basically involves magnetizing magnetic particles, such as cloud particles, deposited inside pipes, etc., to make them behave, and in this state, automatically magnetically using a three-phase rotating alternating magnetic field. It moves and removes the cloud.

To be more specific, FIGS. 1 to 4 show an example of a three-phase rotating alternating magnetic field generator 1 as an exciter for magnetically moving a cloud. For example, on the outer surface of a cylindrical magnetic body 2, A slot is provided at a required angle in the axial direction,
A coil 3 which has been insulated is wound around all the nodes and buried in the slot, and a non-magnetic cover 4 is applied to the outside of the coil 3, and the coil 3 is assembled into a non-magnetic housing 5, and a power plug is connected to the coil 3. Connect a three-phase AC source (not shown) through 6,
The cloud particles are rotated and moved so as to follow a composite vector F (see FIG. 14) of the vector of the rotating alternating magnetic field generated by the coil 3 and the cloud's own weight or force such as viscosity.

The arrangement of the coil 3 is as shown in FIG. 3, which is a cross-sectional section taken along line 1 in FIG.

The coils 3a to 3f are electrically connected as shown in FIG. 4, and in FIG.
) without a dash indicates that the current flows upward perpendicular to the paper, and with a dash (') indicates that the current flows downward perpendicular to the paper. The one with it and the one without it form a single coil.

Also, if the winding angle of the coil 3 is set to about 30 degrees,
The experimental results of the present inventors have revealed that both stirring and transporting of the cloud can be effectively performed using a rotating alternating magnetic field.

If the above-mentioned angle is small, the cloud transfer speed will be high, but the cloud stirring will be poor, resulting in poor transfer efficiency.

Also, if the angle is increased, the stirring action becomes more consistent, but the cloud transport speed decreases.

It has been found that an angle of around 30 degrees is the optimal angle, as the stirring force of the cloud is sufficient and the cloud can be transported at an effective speed.

7 is a ventilation hole for self-convection.

Figures 5 and 6 show an example of a DC excitation device 8 as a magnetizer for magnetizing clouds deposited inside pipes etc. to facilitate transfer. ■
A coil 10 is attached to a molded yoke 9 as shown in the figure, the coil 10 is connected to a DC power source via a terminal plate 11, and a shaft 12 is attached to the center of both ends of the yoke 9.
A triangular platform 13 having wheels 14 for traveling at the lower end
The upper end of the above-mentioned one shaft 1 is attached via a bearing 15.
By operating the bundle 16 attached to the ends of the coil 10, the entire yoke 9 can be rotated using the bases 13 at both ends as support bases, and a sensor 1T such as a thermocouple is fixed to the coil 10 to detect the heat generated by the coil 100. A plug 19 attached to a fixed plate 18 fixed to the yoke 9 is connected to the sensor 17, and the heat generated by the coil 100 is extracted from the plug 19 as a signal.

Next, FIG. 1 shows an example of a power supply circuit system according to the present invention, which is connected to the rotating alternating magnetic field generating device 1 via a cable 24 and controls voltage adjustment, energization time adjustment, etc. for the device 1. The control circuit 21 is connected to the DC excitation device 8 as the magnetizer via a cable 25.
a control circuit 22 for controlling smoothing and voltage adjustment or energization time adjustment, and heat-sensitive elements 28 and 29 fixed to the rotating alternating magnetic field generator 1 and the DC excitation device 8, respectively.
is connected to the element 28 via a cable 26, 27.
．． 29, the control circuit 210 input switch 30 or the control circuit 220 input switch 3
A sequence control circuit 23 configured to control 0'
and is built into the power supply 20.

With the above configuration, for example, as shown in FIG. 8! i
The operation will be explained by taking as an example the transfer and removal of a cloud deposited in the cavity between the safe end nozzle 31 and the thermal sleeve 32 of the child couplant.

First, as described above, the nozzle 31 and the thermal sleeve 32 are
If a cloud is deposited between the two, as shown in FIGS. 9 and 10, a DC excitation device 8 is installed inside the thermal sleeve 32 to apply a DC magnetic field to the cloud.

In this case, the state of the magnetic flux Φ is as shown in Fig. 11,
The magnetic flux generated by the DC excitation device 8 forms a magnetic closed circuit via a safe end nozzle 31 made of iron or the like.

For this reason, even if the excitation current of the DC excitation device 8 is small, it is possible to efficiently magnetize the magnet.

When a cloud is magnetized, it becomes more likely to behave and move.

FIGS. 12 and 13 show an experimental example of magnetization of powder and granular material. In the experimental example, a mixture in which magnetite a, makhemite b, and hematite C were physically mixed was used as a sample as the powder and granular material.

Before the DC magnetic field is applied by the DC excitation device 8, the fine particles are deposited in an orderly manner as shown in Fig. 12, but when the DC magnetic field is applied, magnetite a1 makhemite b1 hematite C
behaves due to magnetic force, magnetite a, maghemite b
are attracted, but these fine particles act to incorporate hematite c and form secondary particles, forming a bridge of particles as shown in Figure 13, and magnetite a and maghemite b gather on the outside. The shape has hematite c in the center.

This shape remains unchanged even when the DC excitation device 8 is turned off due to the residual magnetization of the magnetite a1 maghemite b particles, creating a state in which the particles can easily move.

In the case of a cloud, it is actually produced entirely chemically, so the magnetite (Fe) is contained in one particle.
3o4), maghemite (γ-Fe2O3), and hematite (α-Fe203) are mixed in.

Since each particle always contains particles that are sensitive to magnetism, when a DC magnetic field is applied by the DC excitation device 8,
This means that the overall movement conditions are better than in the above experimental example.

In addition, when magnetizing the cloud deposited between the thermal sleeve 32 and the nozzle 31, since the DC excitation device 8 is configured to be rotatable, it can be magnetized over the entire circumference, and the cloud at any location can be magnetized. It can be made easy to move.

After magnetization is completed as described above, a rotating alternating magnetic field is applied to the magnetized cloud to move the cloud.

In this case, the DC excitation device 8 is extracted from the thermal sleeve 32, the rotating alternating magnetic field generator 1 is assembled into the thermal sleeve 32 as shown in FIGS. 14 and 15, and the coil 3 is energized from the three-phase AC power source. let

As a result, the magnetized cloud is stirred and at the same time moved in the direction of the composite vector F of the vector of the rotating alternating magnetic field generated by the coil 3 and the force such as the weight or viscosity of the cloud particles, and is moved inside the furnace. They are sequentially moved toward the center and are dropped into the furnace and removed as shown by the arrow.

At this time, by setting the winding angle of the coil 3 to the required angle as described above, it is possible to stir the cloud with a large force and simultaneously transport the cloud at a high speed.

Furthermore, by appropriately changing the frequency applied to the rotating alternating magnetic field generator 1, the amount of cloud transport can be significantly increased compared to the case where the same frequency is simply applied.

In this way, before the cloud is transferred by the rotating alternating magnetic field generator 1, a DC magnetic field is applied to the deposited cloud by the DC excitation device 8 to make it behave, and then the magnetized cloud is transferred by the rotating alternating magnetic field. , cloud transfer and removal can be performed with high efficiency.

Regarding this point, the present inventors experimented on the transfer efficiency in cases where the powder or granule was magnetized before moving it in a rotating alternating magnetic field and in cases where it was not magnetized. The transfer efficiency was much better when the magnet was magnetized than when it was not magnetized.

The results of this experiment were as shown in Tables 1 and 2.

In addition, in the experiment, maghemite (γ-Fe2O
3) and hematite (α-Fe203),
Forty grams of the mixture was deposited and transferred in an alternating magnetic field and the remainder was measured to determine transfer efficiency.

Magnetization was performed by applying a DC current of 200 V and 100 A for 3 seconds, and movement was performed by applying a three-phase AC current of 50 Hz for 5 minutes.

As is clear from the table above, if the accumulated powder is magnetized with the DC excitation device 8 before being moved by an alternating magnetic field, the transfer rate will be faster than when the powder is not magnetized. It can be seen that the efficiency can be significantly improved, and even if the excitation current of the alternating magnetic field generator 1 is reduced, a considerable effect can be obtained.

In the case of cloud, it is chemically generated as mentioned above, and includes magnetite (F e a 04 ), maghemite (γ-F e 20g ), hematite (
Since α-Fe203) is mixed together to form one particle, it can be transferred with higher efficiency than the above-mentioned transfer efficiency of the mixture.

The present inventors conducted an implementation test of cloud removal in the thermal sleeve part in an actual atomic couplant, and the first
The radiation reduction rate associated with cloud transport and removal was measured at each location of A to G in Fig. 6 A.

The reduction ratio of each part is as shown in FIG.

As is clear from this, when the cloud is transferred by an alternating magnetic field after magnetization, the cloud can be transferred and removed with a transfer efficiency of about 60 to 80%.

This highly efficient cloud transfer/removal has been achieved for the first time in accordance with the present invention.

Although the present invention has been explained above, the present invention is not limited to the above-mentioned embodiments. For example, the explanation has been mainly about clouds deposited on the thermal sleeve of an atomic couplant. It goes without saying that it can be applied to a wide range of applications for transfer and removal of If the DC excitation device 8 is used, it goes without saying that it should be divided into several parts so that the devices 8 and 1 can be placed outside the tube, and that a permanent magnet may be used as the DC excitation device 8.

As described above, according to the present invention, (1) Transfer and removal of the accumulated magnetic powder is carried out using a rotating alternating magnetic field after magnetization, so the transfer efficiency of the powder can be greatly improved. I can do it.

(ii) In the case of an atomic couplant, for example, by setting the outer diameter of the device so that it can be incorporated into the inner diameter of the thermal sleeve, it can be made lightweight and easy to handle, and does not require extra work space. Since the powder and granules can be automatically removed by self-propelled movement, it is particularly effective in narrow spaces such as atomic couplants.

(iii) When applied to an atomic couplant, the radioactive cloud can be transferred and removed with high efficiency, resulting in a reliable reduction in radiation dose, extending the working time of each worker per day, and improving safety. You can improve your sexual performance.

(IV) By equipping the power supply with a heat-sensitive element and a sequence circuit having an interlock function, it is possible to improve the reliability of the DC excitation device and the rotating alternating magnetic field generator.

(v) The winding angle of the coil is approximately 30 degrees, and the structure is such that the winding angle is approximately 30 degrees and the winding angle is 3/3, making it possible to create a uniform magnetic density and magnetic field gradient without interruption of the magnetic field. It is possible to transfer the particles by placing them on a magnetic field, and the transfer efficiency of the powder and granules can be significantly improved.

In addition, it has been experimentally confirmed that when the winding angle is, for example, 25 degrees or 40 degrees, or when winding is other than 34 full-pitch windings, the magnetic field becomes uneven and hardly any powder or granules are transferred.

It can produce excellent effects such as

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of the rotating alternating magnetic field generator according to the present invention, FIG. 2 is a view taken in the direction of the ■ arrow in FIG. 1, and FIG. An explanatory diagram showing,
FIG. 4 is an explanatory diagram showing the method of connecting the coils of the device shown in FIG. 1, FIG. 5 is a side view of the DC excitation device according to the present invention, and FIG.
The figures are a view in the direction of the ■ arrow in Fig. 5, Fig. 7 is a circuit diagram showing the configuration of the power supply in the present invention, Fig. 8 is a sectional view showing the state in which cloud is deposited on the thermal sleeve portion of the atomic couplant, and Fig. 9 is an explanatory diagram showing the state of magnetizing the cloud, No. 10
The figure is a sectional view taken along the line X-X in Figure 9, Figure 11 is an explanatory diagram showing the magnetic flux of the DC magnetic field, Figures 12 and 13 are experimental examples, and Figure 12 shows the state of the magnetic flux before magnetization. Phase diagram of powder and granular material, 1st
Figure 3 is a diagram of the state of the powder after magnetization, Figure 14 is an explanatory diagram showing the state in which the cloud is transferred, and Figure 15 is the X in Figure 14.
V-Xv sectional view, FIG. 16A1 is an explanatory diagram showing the measurement location after cloud removal, and FIG. 17 is a graph showing cloud transfer efficiency at the measurement location. 1... Three-phase rotating alternating magnetic field generator, 3... Coil,
8... DC excitation device, 9... Yoke, 10... Coil, 13... Stand, 16... Handle, 20...
Power supply, 21° 22... Control circuit, 23... Sequence control circuit, 28.29... Heat sensitive element, 31... Safe end nozzle #, 32... Thermal IJ-7'
.

Claims (1)

[Claims] 1. A DC excitation device that applies a DC magnetic field to magnetize the magnetic powder deposited in the space, and a slot on the outer periphery of the cylindrical magnetic material to transport the magnetic powder magnetized by the device using an alternating magnetic field. Incline the coil to a winding angle of about 30 degrees 3/,
1. A transfer device for magnetic powder, characterized in that it uses a three-phase variable magnetic field generator arranged so as to form a full-pitch winding.