JP2009074103A - Electromagnetic stirring apparatus for liquid metal controlling particle entrainment from liquid metal surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic stirring apparatus for liquid metal capable of effectively entraining particles from the liquid metal surface or conversely, applying stirring to the inside of the liquid metal while preventing entrainment of the particles from the liquid metal surface. <P>SOLUTION: This electromagnetic apparatus is provided with a vessel 3 for the liquid metal, a coil 2 for generating a vertically moving magnetic field arranged at the outside of the vessel, and a coil 1 for generating a rotationary moving magnetic field, arranged at further outside of the coil 2 for generating the vertically moving magnetic field. The surface of the liquid metal 4 is kept static and flat by simultaneously applying the rotationary moving magnetic field stirring and lower-directional vertical moving magnetic field stirring to the inside of the liquid metal, and the particles on the surface of the liquid metal 4 can be stirred without being entrained into the liquid metal 4. The particles on the surface of the liquid metal 4 can efficiently be mixed into the liquid metal 4, by singly applying the upper-directional vertical moving magnetic field stirring to the inside of the liquid metal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid metal stirring device, and more particularly to a stirring device using an electromagnetic stirring device.

  In the field of metal refining, mechanical agitation (KR method or the like) is used to entrain particles from the liquid metal liquid surface (for example, see Non-Patent Document 1). This is a technique in which the stirring blade is rotated in the liquid metal and the solid scouring agent is entrained in the liquid metal, but the stirring blade is damaged by the high temperature liquid metal.

  Also, in order to efficiently entrain the solid scouring agent, a stirring blade is installed in the vicinity of the liquid metal liquid surface, and the solid scouring agent floating on the liquid surface is directly struck with the stirring blade. The liquid metal liquid surface is disturbed excessively and droplets are splashed, which is also a big problem.

  Liquid metal electromagnetic stirring devices using electromagnetic force can be stirred without contact with molten metal, and are therefore often used for high-temperature molten metal (for example, Patent Documents 1 to 3 and Non-Patent Document 2). To 4). For example, in the method involving rolling by rotating moving magnetic field stirring (see, for example, Non-Patent Document 2), it is necessary to give a very high rotational speed, and there is a problem that the deformation of the liquid level becomes large. In addition, there is one that focuses on stirring the inside of the liquid metal (see, for example, Patent Document 1), and does not focus on the control of the liquid metal liquid level, in particular, the entrainment of particles on the liquid metal liquid level.

  On the other hand, after the refining reaction is completed, it is extremely difficult to efficiently stir the inside of the liquid metal while preventing particle entrainment from the liquid surface with the conventional method, and the stirring itself is stopped or the stirring strength is weakened. There was a need to do.

Shoji Harada, Hiromi Nakamura, Satoshi Kodaira, Haruo Katayama, Hisaki Kato, Masaaki Nishi, “Extending the life of refractories for mechanically agitated desulfurization equipment (KR impeller)”, Iron and Steel, 1987, 73, p.169 Japanese Patent Laid-Open No. 54-163729 JP 2003-220323 A JP 2007-144501 A Yu. Gelfgat, M. Skopis and J. Grabis, “Electromagnetic funnel for stirring up solid reagents into molten metals”, Proc. Joint 15th Riga and 6th PAMIR Int. Conf., Riga, 2005, 2, p.19 Kenzo Ayada, “Utilization technology of moving magnetic field”, 129-130 Nishiyama Memorial Lecture, 1990, p.130 Naoji Taniguchi, Kazuyuki Ueno, Shima Shinzaki, Mitsuji Okubo, Tsutomu Ando, Norifumi Kasahara, “Electromagnetic Stirring of Liquid Metals by Simultaneous Application of Rotating Magnetic Field and Moving Magnetic Field”, Iron and Steel, 2006, 92, p. 8

  The present invention has been made paying attention to such a problem, and the particles are efficiently entrained from the liquid surface of the liquid metal, or conversely, the liquid metal is agitated while preventing the particles from being entrained from the liquid surface. An object of the present invention is to provide a liquid metal electromagnetic stirrer that can apply.

  A liquid metal electromagnetic stirring device according to the present invention includes a liquid metal container, a vertical moving magnetic field generating coil provided outside the container, and a rotational moving magnetic field provided further outside the vertical moving magnetic field generating coil. The vertical moving magnetic field generating coil and the rotary moving magnetic field generating coil can control their currents independently, and the vertical direction electromagnetic force and the rotational direction electromagnetic force can be used independently or simultaneously. By changing the connection of the vertical moving magnetic field generating coil, the direction in which the vertical moving magnetic field moves can be changed upward or downward, and the direction of the electromagnetic force in the vertical direction can be controlled. By simultaneously applying magnetic field agitation and downward vertical moving magnetic field agitation, the liquid metal liquid surface is kept calm and flat, and particles of the liquid metal liquid surface are entrained in the liquid metal. That is configured to be able to add stirring without, characterized.

  The liquid metal electromagnetic stirrer according to the present invention is configured so that particles on the liquid metal liquid surface can be efficiently mixed into the liquid metal by adding the upward vertical moving magnetic field stirring alone. Preferably it is. In addition, the liquid metal electromagnetic stirring device according to the present invention includes a state in which the rotational moving magnetic field stirring and the downward vertical moving magnetic field stirring are simultaneously applied in the middle of stirring, and the upward vertical moving magnetic field stirring is added alone. It is preferable that the state can be changed at any time. In the liquid metal electromagnetic stirring device according to the present invention, the height direction position of the liquid metal liquid surface held in the liquid metal container is set near the upper end of the vertical moving magnetic field generating coil. It is preferable that In the liquid metal electromagnetic stirrer according to the present invention, the particles on the liquid metal liquid surface may contain solid scouring agent, slag droplets, flux, metal oxide, bubbles, reinforcing particles for composite material, and the like.

The present invention succeeded in controlling the liquid metal liquid level, in particular, controlling the entrainment of particles on the liquid metal liquid level, by combining the rotary moving magnetic field stirring and the vertical moving magnetic field stirring.
By applying the upward vertical moving magnetic field stirring alone, a flow that wraps around from the periphery to the center on the liquid surface is generated, and the particles can be efficiently entrapped inside the liquid metal. Furthermore, by changing the stirring method to simultaneous application of the downward vertical moving magnetic field stirring and the rotational moving magnetic field stirring, the liquid metal can be stirred without involving particles.
In the present invention, electromagnetic stirring that is not in contact with the liquid metal is used, so there is no problem such as damage to the stirring blades. Further, since the liquid metal liquid surface is not extremely disturbed, the liquid metal droplets are hardly scattered (splash).

  According to the present invention, it becomes possible to efficiently entrain particles from the liquid surface of the liquid metal, or conversely, to apply stirring to the inside of the liquid metal while preventing particles from being entrained from the liquid surface. These stirring methods can be changed at any time even during operation, and can meet various requirements of the stirring process of the liquid metal containing particles.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Configuration of electromagnetic stirring device]
In FIG. 1, the structural example of the electromagnetic stirring apparatus by this invention is shown. The electromagnetic stirrer is composed of a rotary moving magnetic field generating coil 1 and a vertical moving magnetic field generating coil 2, and a liquid metal container 3 is installed inside thereof. The position in the height direction of the liquid level of the liquid metal 4 is set near the upper end of the electromagnetic stirring device.

  2 and 3 show a configuration example of the three-phase current applied to the vertical moving magnetic field generating coil 2 and the movement of the moving magnetic field. When a current is applied as shown in FIG. 2, the moving direction 5 of the moving magnetic field is upward, and the liquid metal 4 near the side wall surface of the liquid metal container 3 is driven upward (the liquid metal in FIG. 2). Motion direction 6). On the other hand, when current is applied as shown in FIG. 3, the moving direction 5 of the moving magnetic field is downward, and the liquid metal 4 near the side wall surface of the liquid metal container 3 is driven downward (in FIG. 3). Liquid metal motion direction 6).

  The upward vertical moving magnetic field stirring in FIG. 2 and the downward vertical moving magnetic field stirring in FIG. 3 can be changed from each other by exchanging the U phase and the W phase of the three-phase current 7. Therefore, these stirring methods can be easily changed during operation.

  As the stirring method of the electromagnetic stirrer according to the embodiment of the present invention, (b) a single application of the rotational moving magnetic field stirring, (b) a single application of the upward vertical moving magnetic field stirring, and (c) a downward vertical moving magnetic field stirring. There are five combinations of single application, (d) simultaneous application of rotational moving magnetic field stirring and upward vertical moving magnetic field stirring, and (e) simultaneous application of rotational moving magnetic field stirring and downward vertical moving magnetic field stirring, and these The stirring method can be easily changed during operation.

[Numerical calculation of electromagnetic force]
In order to grasp the electromagnetic force generated by the electromagnetic stirrer according to the present invention, an electromagnetic field analysis by numerical calculation was performed. 4-6 shows an example of the result of an electromagnetic field analysis.
FIG. 4 shows the distribution of electromagnetic force in the horizontal cross section of the liquid metal. (A) It can be seen that in the single application of the rotational moving magnetic field stirring, an electromagnetic force in the rotational direction is applied inside the liquid metal.
5 and 6 are electromagnetic force distributions in the vertical cross section of the liquid metal. As shown in FIG. 5, (b) in the single application of the upward vertical moving magnetic field stirring, the upward electromagnetic force is generated inside the liquid metal, as shown in FIG. In application, it can be seen that a downward electromagnetic force is applied to the inside of the liquid metal.

  The liquid metal is driven in a non-contact manner by these electromagnetic forces. Therefore, even if this electromagnetic stirring apparatus is applied to a high-temperature liquid metal, there is no problem such as thermal damage of the apparatus, and it can be applied even during the solidification process of the metal.

In order to verify the validity of this electromagnetic field analysis, the magnetic flux density was compared with the measured value using a gauss meter. An example of the result is shown in FIGS.
FIG. 7 shows the radial component (effective value) of the magnetic flux density generated by the single application of the rotating magnetic field stirring. In the case of the rotationally moving magnetic field, it can be seen that the magnetic field penetrates the liquid metal, so that the magnetic flux density is almost uniform inside the liquid metal.
FIG. 8 shows the radial component (effective value) of the magnetic flux density generated by the single application of vertical moving magnetic field stirring. The vertical moving magnetic field is almost zero on the central axis (r = 0 mm), and the magnetic flux density is large in the vicinity of the coil.
Both FIG. 7 and FIG. 8 show that the calculated value and the actually measured value are in good agreement, and it is understood that the electromagnetic force generated by the electromagnetic stirring device can be accurately predicted by numerical calculation.

[Numerical calculation of flow field]
Using the electromagnetic force obtained by numerical calculation, numerical calculation of the flow field and pressure field of liquid metal was performed. The results are shown in FIGS.
As shown in FIG. 9, (a) in the single application of rotating magnetic field stirring, almost no flow is generated in the vertical cross section, and the flow is mainly the rotation, and the flow as a whole is close to rigid body rotation. Yes. Due to the centrifugal force due to rotation, the pressure is higher on the outside.
As shown in FIG. 10, (b) in the single application of the vertical vertical magnetic field stirring, the liquid metal rises to the liquid level along the side wall surface of the container and flows from the periphery to the center on the liquid level. It has become. The pressure is highest near the liquid level.

As shown in FIG. 11, (c) In the single application of the vertical magnetic field stirring in the downward direction, the liquid metal descends to the bottom of the container along the side wall surface of the container, and springs from the center to the periphery on the liquid level. It is like this. The pressure is highest at the bottom of the container.
As shown in FIG. 12, it can be seen that (d) in the simultaneous application of the rotational moving magnetic field stirring and the upward vertical moving magnetic field stirring, the liquid metal rises along the side wall surface of the container and becomes a strong rotational flow. . The pressure is highest near the side wall surface of the container above the liquid metal.
As shown in FIG. 13, in the case of (e) simultaneous application of rotating and moving magnetic field stirring and downward vertical moving magnetic field stirring, the liquid metal is weakly rotating while descending along the side wall surface of the container. I understand. The pressure is highest near the side wall surface of the container below the liquid metal.

[Observation experiment involving glass beads]
A particle entrainment experiment was performed under the same experimental conditions as the numerical calculation of the flow field. The apparatus used for the experiment is shown in FIG. In the experiment, glass beads 8 with a diameter of 5.1 mm (density 2480 kg / m ³ , terminal levitation speed in liquid gallium 300 mm / s) were floated on the surface of liquid gallium (density 6090 kg / m ³ ) of liquid metal 4 Stirring was performed by five methods.
15 to 19 show the state of the liquid metal liquid surface during the experiment.

As shown in FIG. 15, (a) in the case of single application of rotational moving magnetic field stirring, the liquid surface of the liquid metal is only rotating as a whole as a whole, and particles floating on the liquid surface are caught inside. There was almost no appearance.
As shown in FIG. 16, (b) in the single application of the upward vertical moving magnetic field stirring, there is a flow in which the liquid surface of the liquid metal is drawn from the periphery to the center. The particles floating on the liquid surface are entrained in the liquid metal along this flow, and almost no particles are seen on the liquid surface.
As shown in FIG. 17, (c) in the case of single application of stirring in the downward vertical moving magnetic field, the flow is such that the liquid surface of the liquid metal springs from the center. A part of the particles floating on the surface of the liquid are caught in the liquid metal.

As shown in FIG. 18, (d) in the simultaneous application of the rotational moving magnetic field stirring and the upward vertical moving magnetic field stirring, the dent at the center of the liquid surface due to the rotational moving magnetic field stirring is further increased by the flow of the upward vertical moving magnetic field stirring. As a whole, the rotating flow is strong. Since the particles are rotating on the liquid surface, they gather at the center of the liquid by centrifugal force, and are entrained inside the liquid by the upward vertical magnetic field stirring flow.
As shown in FIG. 19, in the case of simultaneous application of (e) rotational moving magnetic field stirring and downward vertical moving magnetic field stirring, the dent in the liquid level center due to rotational moving magnetic field stirring is Corrected by springing, the liquid level is kept flat and calm. For this reason, the particles floating on the liquid surface do not move so much and are hardly caught inside the liquid metal.

  The flow state of the liquid level observed from the experiments of FIGS. 15 to 19 coincides with the numerical calculation results of FIGS. 9 to 13, and the flow field by the electromagnetic stirring device can be reproduced by the numerical calculation. I understand that.

[Quantitative evaluation of entrainment of glass beads]
In order to more quantitatively evaluate the observation results of the above particle entrainment, glass beads 8 having a diameter of 1.2 mm (density 2200 kg / m ³ , final levitation speed in liquid gallium 130 mm / s) were floated, and the liquid metal 4 The number of glass beads 8 wound inside the liquid gallium was measured. The glass beads 8 are collected by a glass bead collector (sampler) 9 on the center line of the liquid metal container 3 at a position about 1/3 of the liquid height from the bottom of the liquid metal container 3. FIG. 20 shows how the glass beads 8 are collected.

  FIG. 21 summarizes the results obtained. From FIG. 21, in the case of (a) independent application of rotating moving magnetic field stirring and (e) simultaneous application of rotating moving magnetic field stirring and downward vertical moving magnetic field stirring, almost no glass beads are caught in the liquid gallium. I understand. On the other hand, glass beads are most efficiently involved in the case of (b) single application of vertical vertical magnetic field stirring, and then (d) simultaneous application of rotary magnetic field stirring and vertical vertical magnetic field stirring. (C) It is the order of single application of the downward vertical moving magnetic field stirring.

That is, in order to efficiently entrain particles from the liquid surface of the liquid metal, (b) single application of upward vertical moving magnetic field stirring is most excellent.
On the other hand, it can be seen that (e) simultaneous application of rotational moving magnetic field stirring and downward vertical moving magnetic field stirring is excellent in order to perform stirring without entraining particles on the liquid metal surface. In this stirring method, it is possible to apply stirring while keeping the liquid level flat and quiet and preventing particle entrainment.

[Summary]
Unlike the conventional mechanical stirring by the KR method or the like, the particle entrainment from the liquid surface according to the present invention can be performed without contact with the liquid metal, so that there is no problem of damage to the stirring blade. Further, since the liquid metal liquid surface is not excessively disturbed, the liquid metal droplets are hardly scattered (splash). Furthermore, since it can be applied also during solidification, it has an advantage that it can also be applied to prevent the metal oxide from being entrained from the liquid surface during the production of a semi-molten solidified body (slurry).

It is the perspective view and sectional drawing which show the liquid metal electromagnetic stirring apparatus of embodiment of this invention. It is sectional drawing which shows the connection and movement of a moving magnetic field at the time of a vertical moving magnetic field stirring of the vertical moving magnetic field generation coil of the liquid metal electromagnetic stirring apparatus shown in FIG. It is sectional drawing which shows the connection at the time of the downward vertical movement magnetic field stirring of the coil for vertical movement magnetic field generation of the liquid metal electromagnetic stirring apparatus shown in FIG. 1, and a movement of a movement magnetic field. The numerical calculation results (current conditions: 40 Hz, 17.6 A, liquid metal: molten gallium) of the electromagnetic force (Lorentz force density) generated inside the liquid metal by the rotating moving magnetic field stirring of the liquid metal electromagnetic stirring device shown in FIG. It is a cross-sectional view shown. Numerical calculation results of the electromagnetic force (Lorentz force density) generated in the liquid metal by the vertical vertical magnetic field stirring of the liquid metal electromagnetic stirrer shown in Fig. 1 (current conditions: 65Hz, 25.8A, liquid metal: molten gallium FIG. Numerical calculation results of the electromagnetic force (Lorentz force density) generated in the liquid metal by the downward vertical moving magnetic field stirring of the liquid metal electromagnetic stirrer shown in Fig. 1 (current conditions: 65Hz, 25.8A, liquid metal: molten gallium FIG. 2 is a graph showing a comparison (current condition: 60 Hz, 10 A) between a numerical calculation result of magnetic flux density generated by a coil for generating a rotationally moving magnetic field and an actual measurement value of the liquid metal electromagnetic stirrer shown in FIG. 1. It is a graph which shows the comparison (current conditions: 60Hz, 20A) of the numerical calculation result of the magnetic flux density generated with the coil for the downward vertical movement magnetic field generation | occurrence | production of the liquid metal electromagnetic stirring apparatus shown in FIG. It is a longitudinal cross-sectional view which shows the numerical calculation result of the flow field and pressure field which generate | occur | produce in a liquid metal by the single application of a rotational movement magnetic field stirring of the liquid metal electromagnetic stirring apparatus shown in FIG. It is a longitudinal cross-sectional view which shows the numerical calculation result of the flow field and pressure field which generate | occur | produce inside a liquid metal by the single application of an upward vertical moving magnetic field stirring of the liquid metal electromagnetic stirring apparatus shown in FIG. It is a longitudinal cross-sectional view which shows the numerical calculation result of the flow field and pressure field which generate | occur | produce in a liquid metal by the single application of a downward vertical movement magnetic field stirring of the liquid metal electromagnetic stirring apparatus shown in FIG. It is a longitudinal cross-sectional view which shows the numerical calculation result of the flow field and pressure field which generate | occur | produce by the simultaneous application of rotational moving magnetic field stirring and upward vertical moving magnetic field stirring of the liquid metal electromagnetic stirring apparatus shown in FIG. It is a longitudinal cross-sectional view which shows the numerical calculation result of the flow field and pressure field which generate | occur | produce by the simultaneous application of rotational movement magnetic field stirring and downward vertical movement magnetic field stirring of the liquid metal electromagnetic stirring apparatus shown in FIG. It is sectional drawing which shows the use condition in the particle entrainment experiment of the liquid metal electromagnetic stirring apparatus shown in FIG. It is a perspective view which shows the particle entrainment state in the liquid metal in the case of single application of the rotational movement magnetic field stirring of the electromagnetic stirring apparatus of the liquid metal shown in FIG. It is a perspective view which shows the particle entrainment state in the liquid metal in the case of single application of the upward vertical moving magnetic field stirring of the liquid metal electromagnetic stirring apparatus shown in FIG. It is a perspective view which shows the particle entrainment state in the liquid metal in the case of single application of the downward vertical movement magnetic field stirring of the liquid metal electromagnetic stirring apparatus shown in FIG. It is a perspective view which shows the particle entrainment state in the liquid metal in the case of simultaneous application of rotational movement magnetic field stirring and upward vertical movement magnetic field stirring of the liquid metal electromagnetic stirring apparatus shown in FIG. It is a perspective view which shows the particle entrainment state in the liquid metal in the case of simultaneous application of rotational movement magnetic field stirring and downward vertical movement magnetic field stirring of the liquid metal electromagnetic stirring apparatus shown in FIG. It is sectional drawing which shows the sampling state of particle | grains of the liquid metal electromagnetic stirring apparatus shown in FIG. It is the table which put together the amount of particle | grain entrainment by the various stirring methods of the liquid metal electromagnetic stirring apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coil for rotational magnetic field generation 2 Coil for vertical magnetic field generation 3 Liquid metal container 4 Liquid metal 5 Movement direction of moving magnetic field 6 Movement direction of liquid metal 7 Three-phase current 8 Glass beads 9 Glass bead collector

Claims (5)

A liquid metal container, a vertical moving magnetic field generating coil provided outside the container, and a rotational moving magnetic field generating coil provided further outside the vertical moving magnetic field generating coil,
The vertical moving magnetic field generating coil and the rotating moving magnetic field generating coil can independently control their currents, and the vertical electromagnetic force and the rotational electromagnetic force can be applied individually or simultaneously,
By changing the connection of the vertical moving magnetic field generating coil, the direction of movement of the vertical moving magnetic field can be changed upward or downward, and the direction of the electromagnetic force in the vertical direction can be controlled.
By simultaneously applying rotating moving magnetic field stirring and downward vertical moving magnetic field stirring, the liquid surface of the liquid metal is kept calm and flat, and stirring is performed without entraining the particles of the liquid metal liquid surface into the liquid metal. That it is configured to
A liquid metal electromagnetic stirring device.   2. The structure according to claim 1, wherein the liquid metal liquid surface particles can be efficiently mixed into the liquid metal by independently applying the upward vertical moving magnetic field stirring. Liquid metal electromagnetic stirring device.   In the middle of stirring, the state in which the rotational moving magnetic field stirring and the downward vertical moving magnetic field stirring are simultaneously applied and the state in which the upward vertical moving magnetic field stirring is added alone can be changed as needed. The electromagnetic stirring apparatus for liquid metal according to claim 2.   2. The position in the height direction of the liquid metal liquid surface held in the liquid metal container is set in the vicinity of an upper end portion of the vertical moving magnetic field generating coil. 2. An electromagnetic stirring device for liquid metal according to 2 or 3. 5. The liquid metal according to claim 1, wherein the liquid metal liquid surface particles include solid scouring agent, slag droplets, flux, metal oxide, bubbles, and reinforcing particles for composite material. Electromagnetic stirring device.