JP2008132521A - Induction heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating device for induction-heating an injection nozzle, in which an induction coil prepared by spirally winding a wire in a rectangular shape as a whole is disposed bendingly along the outer peripheral face of the injection nozzle for molten metal to improve heating efficiency. <P>SOLUTION: In the induction heating device, the induction coil 1a prepared by spirally winding a Cu tube 2 in a rectangular shape as a whole is arranged bendingly along the outer peripheral face of the injection nozzle for molten metal in order to induction-heat the injection nozzle. The distance pa between Cu tubes 2 adjacent to each other except in the center part 3 is shorter than the distance la between Cu tubes 2 adjacent across the center part 3 in at least one direction of the longitudinal and transverse directions of the rectangular induction coil 1a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an induction heating apparatus suitable for induction heating an immersion nozzle that injects molten steel stored in a tundish into a mold, for example, in a continuous casting facility in the steel manufacturing industry.

  In the continuous casting facility, the molten steel in the ladle 50 is supplied to the tundish 51 through the long nozzle 52 as shown in FIG. The molten steel stored in the tundish 51 is poured into a mold (water-cooled mold) 54 through an immersion nozzle 53, and is drawn down and hardened together with cooling.

  In such a continuous casting facility, the immersion nozzle 53 is heated in order to prevent the temperature of molten steel passing through the immersion nozzle 53 from decreasing and to reduce the thermal load of the immersion nozzle 53.

  For example, Patent Document 1 discloses a method using a burner capable of supplying fuel gas and oxygen from an upper pouring port of an immersion nozzle or a lower discharge hole.

  However, in the method disclosed in Patent Document 1, heating takes time, and the refractory constituting the immersion nozzle is deteriorated during heating, which may cause troubles such as spalling during actual operation. . Moreover, since the heating temperature by the burner is usually lower than the temperature of molten steel (1500 to 1530 ° C.) (1000 to 1200 ° C.), if the immersion nozzle contacts the molten steel during actual operation, troubles such as cracking due to thermal stress occur. There is a risk that.

  On the other hand, Patent Document 2 discloses a method of performing induction heating by inserting a cylindrical induction coil inside an immersion nozzle, and Patent Document 3 includes a cylindrical coil disposed outside the immersion nozzle. A method of performing induction heating is disclosed.

  However, in the method disclosed in Patent Document 2, the immersion nozzle can be heated to a high temperature of about 1400 ° C. in a short time. However, since the induction coil is inserted into the immersion nozzle, the refractory of the immersion nozzle and the induction coil are in contact with each other. As a result, the immersion nozzle and the induction coil are damaged, and the life is shortened. In addition, carbon and antioxidants blended in the refractory of the immersion nozzle are removed by contact, and troubles such as spalling and excessive melting may occur during actual operation. Further, since a mechanism for inserting the induction coil into the submerged nozzle is necessary, installation is expensive. Furthermore, it is necessary to prepare induction coils having different outer diameters in accordance with immersion nozzles having different inner diameters.

  In the method disclosed in Patent Document 3, a magnetic field is generated parallel to the outer surface of the immersion nozzle, that is, parallel to the axis of the immersion nozzle, so that the outer surface of the uneven immersion nozzle is uniform. In particular, the slag-in portion protruding compared to other portions may be excessively heated. Further, it is necessary to prepare coils having different inner diameters in accordance with the immersion nozzles having different outer diameters.

Japanese Patent Laid-Open No. 61-262455 JP-A-9-122901 JP 2002-336842 A

  In view of the above-described problems, the applicant of the present application has disclosed that in Japanese Patent Application No. 2006-5104, the induction coil is placed along the outer peripheral surface of the immersion nozzle so that the winding center direction of the induction coil intersects the immersion nozzle. Proposes a heating device that can heat the immersion nozzle uniformly by providing a longer life of the coil, less deterioration of the immersion nozzle, and less influence of irregularities on the outer surface of the immersion nozzle. is doing.

  Hereinafter, the heating apparatus proposed by the present applicant will be described with reference to FIGS. As shown in FIG. 5, the induction heating device 10, in the continuous casting facility 11, before pouring molten steel supplied from a ladle (not shown) from the tundish 12 to a mold (not shown). This is a device for heating the immersion nozzle 13 attached to the dish 12. For example, the tundish 12 is provided with a sliding nozzle 14, and the immersion nozzle 13 is attached to the tundish 12 via the sliding nozzle 14.

  The immersion nozzle 13 is formed of a conductive material such as alumina graphite containing carbon for the purpose of preventing oxidation of molten steel poured from the tundish 12 into the mold. As shown in FIG. 6, the shape of the immersion nozzle 13 is a cylindrical shape whose bottom is substantially closed, and a pouring port 15 into which molten steel is poured at the top and two holes facing the lower side surface. The provided discharge hole 16 is provided, and a thick slag line portion 17 is formed at the center in the height direction. A refractory 18 coated with an antioxidant is provided inside the immersion nozzle 13. Further, an argon gas supply hole 19 for supplying argon gas from the outer surface side to the inner side of the immersion nozzle 13 is provided in the upper part of the immersion nozzle 13. A stainless trunnion (not shown) provided with a bar-like horizontal member (not shown) for installing the immersion nozzle 13 on the tundish 12 is integrally formed on the outer side of the upper end of the immersion nozzle 13. Installed.

  As shown in FIGS. 7 to 9, a plurality of, for example, two induction coils 20 and 21 divided into two are arranged along the outer peripheral surface of the immersion nozzle 13. The induction coils 20, 21 are, for example, welded to a copper tube having a rectangular cross section to form a spiral shape, and then curved along the outer surface of the immersion nozzle 13, as shown in FIG. (It is a curved plane). The two induction coils 20 and 21 are opposed to each other with the immersion nozzle 13 in the center, and the winding cores of the induction coils 20 and 21 are arranged in the vicinity of the thick slag-in portion 17.

  Further, one end side of each of the spiral centers of the induction coils 20 and 21 is connected via a connecting fitting 22 by a connecting pipe 25 formed of a copper pipe 24 having a circular cross section whose outer side is covered with a heat insulating material 23. The other end sides of the induction coils 20 and 21 are paired and connected to a power source (not shown) to form one circuit. The power source is, for example, AC 200/220 V, 60 Hz, and 26 KvA, the output of the induction coils 20 and 21 is 20 kW at maximum, the frequency is 5 to 40 kHz, for example, 20 kHz, and the immersion nozzle 13 is, for example, 1200 to 1530 ° C. Heat. Furthermore, in order to prevent the induction coils 20 and 21 from being heated by radiant heat and resistance heating when the immersion nozzle 13 is heated, for example, the induction coil 20 is connected to the other end side of the induction coil 20 to which the induction coil 21 is connected. , 21 is connected to a cooling water supply pipe (not shown) for supplying cooling water.

  Here, as shown in FIG. 10, the winding directions of the induction coils 20, 21 arranged opposite to each other are arranged, for example, with the induction coil 20 on the front side of the immersion nozzle 13 and the induction coil 21 on the back side of the immersion nozzle 13. Assuming that the current flows from the induction coil 20 side to the induction coil 21 side via the connecting tube 25, the current flows clockwise through the induction coil 20 and the induction coil 21 as viewed from the front. The winding direction of the induction coils 20 and 21 is counterclockwise when the current is passed from the induction coil 20 side to the induction coil 21 side through the connecting tube 25 when viewed in front from the induction coil 20 and the induction coil 21. A current may flow through the induction coils 20, 21 and the current flowing through the induction coils 20, 21 may be in the reverse direction.

  The induction coils 20 and 21 have a plan view of the immersion nozzle 13, and the winding core direction of the induction coils 20 and 21 intersects with the immersion nozzle 13 (for example, the axial center 26 or the hollow portion of the immersion nozzle 13). When the nozzle 13 is viewed from the side, the surfaces of the induction coils 20 and 21 are arranged so that the surfaces of the induction coils 20 and 21 are parallel to the immersion nozzle 13, that is, parallel to the immersion nozzle 13. Since the angle is 90 degrees, many lines of magnetic force (not shown) intersect with the immersion nozzle 13 are generated, and these lines of magnetic force pass through the immersion nozzle 13 to cause an eddy current (not shown) in the immersion nozzle 13. The immersion nozzle 13 is heated by this eddy current. As a result, the outer surface of the immersion nozzle 13 can be heated uniformly with little influence of the unevenness. The induction coils 20 and 21 may be arranged so that the surfaces of the induction coils 20 and 21 are inclined with respect to the immersion nozzle 13 at, for example, more than 0 degree and 30 degrees or less. For example, the submerged nozzle 13 can be heated uniformly by varying the distance between the slag-in portion 17 and the induction coils 20 and 21 and the distance between the discharge hole 16 and the induction coils 20 and 21.

  Furthermore, it has a gas heating means 30 for heating the immersion nozzle 13 with a high temperature gas. The gas heating means 30 is disposed below the immersion nozzle 13 by being inserted into the immersion nozzle 13 through the discharge hole 16 of the immersion nozzle 13 and the immersion nozzle 13, and the coke oven is provided in the immersion nozzle 13 by the ejector effect. It has a COG gas supply pipe 32 that supplies gas (COG), and the inner surface of the immersion nozzle 13 can be heated by a high-temperature gas generated by burning COG. As shown in FIG. 5, the gas heating means 30 has a preheating burner 42 disposed in a through hole 41 of a tundish cover 40 installed on the upper portion of the tundish 12, and the tundish 12 is heated by the preheating burner 42. The inside can be heated at the same time. In the preheating bar bar 42, a molten steel stopper 43 disposed in the tundish 12, an upper nozzle 45 and a lower nozzle 46 provided in a molten steel discharge port 44 at the bottom of the tundish 12, the sliding nozzle 14, and the immersion nozzle 13. The upper part can be heated.

  Next, a method for heating the immersion nozzle 13 using the heating device 10 will be described. Before injecting molten steel from the tundish 12 of the continuous casting equipment 11 into the mold, the two induction coils 20, 21 curved along the outer peripheral surface of the immersion nozzle 13 attached to the tundish 12 via the sliding nozzle 14. Are arranged in the vicinity of the discharge hole 16 of the immersion nozzle 13 and the outer surface of the slag line portion 17 so that the winding center direction of each induction coil 20, 21 intersects the immersion nozzle 13. Further, the air supply pipe 31 is disposed inside the immersion nozzle 13 from the discharge hole 16 of the immersion nozzle 13, and the COG gas supply pipe 32 is disposed below the immersion nozzle 13. Further, the tundish cover 40 is disposed on the tundish 12, and the preheating burner 42 is disposed in the through hole 41 of the tundish cover 40.

  First, the inner surface and upper part of the immersion nozzle 13 are heated to, for example, a temperature range of 700 ° C. or higher (700 to 1100 ° C.), for example, 1000 ° C. by the gas heating means 30. At this time, the inner surface of the immersion nozzle 13 is heated by the high temperature gas from the air supply pipe 31 and the COG gas supply pipe 32, and the upper part of the immersion nozzle 13 and the inside of the tundish 12 are heated by the preheating burner 42.

  After the temperature of the immersion nozzle 13 reaches, for example, about 1000 ° C., the power supply connected to the induction coils 20 and 21 has a maximum output of 20 kW to the induction coils 20 and 21, and the frequency is 5 to 40 kHz. The immersion nozzle 13 is heated to 1200 to 1530 ° C., for example, 1400 ° C. by applying a current of 20 kHz. Since induction heating by the induction coils 20 and 21 is performed in a temperature range where the temperature of the immersion nozzle 13 is 700 ° C. or higher, the time during which the immersion nozzle 13 is exposed to 700 ° C. or more is shortened, and the refractory 18 of the immersion nozzle 13 is attached to the refractory 18. Degradation of the applied antioxidant can be prevented. The induction heating may be performed by the induction coils 20 and 21 when the temperature of the immersion nozzle 13 is less than 700 ° C. However, since the electricity bill becomes high, the induction heating by the induction coils 20 and 21 is performed at the temperature of the immersion nozzle 13. Is preferably performed in a temperature range of 700 ° C. or higher. Further, at the time of induction heating by the induction coils 20 and 21, heating with a high temperature gas by the gas heating means 30 may or may not be performed.

  Moreover, the lower limit of the heating temperature of the immersion nozzle is 1200 ° C., preferably 1300 ° C., more preferably 1350 ° C., and the upper limit is about 1530 ° C. which is the temperature of the molten steel. In addition, since the temperature of the immersion nozzle 13 falls after completion | finish of the heating of the immersion nozzle 13 until the pouring of molten steel, it is good also as the heating temperature of the immersion nozzle 13 higher than the temperature of molten steel, for example, about 1600 degreeC. Further, at the time of heating, cooling water is supplied to the inside of the induction coils 20 and 21 at, for example, 4 liters / minute to prevent the induction coils 20 and 21 from being heated by the radiant heat and resistance heating of the immersion nozzle 13.

  As described above, the induction coils 20 and 21 reduce the influence of the unevenness on the outer surface of the immersion nozzle 13 by generating a large magnetic field in the direction intersecting the outer surface of the immersion nozzle 13 to reduce the immersion. The nozzle 13 is heated uniformly. Further, the induction coils 20 and 21 are curved along the outer surface of the immersion nozzle 13 so that the distance between the induction coils 20 and 21 and the immersion nozzle 13 is constant, and the immersion nozzle 13 is heated more uniformly.

  In addition, the induction coils 20 and 21 are divided into a plurality of parts so that they can be easily attached to and detached from the immersion nozzle 13. In particular, when the induction coils 20 and 21 are attached to and detached from the immersion nozzle 13, the induction coils 20 and 21 and the immersion nozzle 13 are arranged. Are not slid and contacted, and the deterioration of the immersion nozzle 13 and the induction coils 20 and 21 is prevented. Further, since the plurality of induction coils 20 and 21 can be adjusted and arranged according to the outer diameter of the immersion nozzle 13, cylindrical induction coils having various inner diameters matched to the outer diameter of the immersion nozzle 13 as in the past. It is not necessary, and the number of spare parts for non-operational induction coils can be reduced.

  In addition, the induction coils 20 and 21 are disposed in the vicinity of the outer surface of the discharge hole 16 and the slag-in portion 17 of the immersion nozzle 13 to uniformly heat the portion that is easily spalled, thereby preventing the immersion nozzle 13 from being damaged. . Furthermore, since the part which is hard to heat with the induction coils 20 and 21 is heated by the gas heating means 30, the immersion nozzle 13 can be heated more uniformly.

  The heating apparatus proposed by the applicant of the present application has been described above. When induction heating is performed by the induction coils 20 and 21 as described above, it is required to improve the heat generation efficiency.

  The present invention has been made in view of the above points, and an induction coil having a linear member spiraled so as to have a rectangular shape as a whole is curved along the outer peripheral surface of a molten metal injection nozzle. It is an object of the present invention to provide an induction heating apparatus that heats the injection nozzle by heating the inside of the injection nozzle at a portion facing the induction coil and to improve the heat generation efficiency.

In the induction heating apparatus of the present invention, an induction coil in which a linear member is spirally formed so as to be rectangular as a whole is arranged by being curved along the outer peripheral surface of a molten metal injection nozzle, and the injection nozzle is arranged. An induction heating apparatus that performs induction heating, wherein at least one of a longitudinal direction and a lateral direction of the rectangular induction coil is adjacent to a portion other than the center portion, compared to a distance between adjacent linear members across the center portion. It is characterized in that the distance between the matching linear members is shortened.
Another feature of the induction heating device of the present invention is that the injection nozzle is a nozzle for injecting molten metal from a ladle into a tundish in a continuous casting facility, or injecting molten metal from a tundish into a mold. It is in the point which is a nozzle to do.
Another feature of the induction heating device according to the present invention is that at least one of the longitudinal direction and the lateral direction of the rectangular induction coil has an equal interval between adjacent linear members other than the central portion. There is in point.
Another feature of the induction heating apparatus according to the present invention is that the linear member is made of a metal tube.

  According to the present invention, in at least one of the longitudinal direction and the lateral direction of the rectangular induction coil, the distance between adjacent linear members other than the central portion is larger than the distance between adjacent linear members across the central portion. By shortening the distance, the inside of the injection nozzle at the portion facing the induction coil can be uniformly heated and the heat generation efficiency can be improved.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 (a) shows an induction coil 1a of an induction heating device according to an embodiment of the present invention. The induction coil 1a is configured such that a copper tube 2 having a rectangular cross section is spirally formed on substantially the same plane so as to be rectangular as a whole. The rectangular induction coil 1a corresponds to the induction coils 20 and 21 described above, and is arranged to be curved along the outer peripheral surface of the immersion nozzle.

  In FIG. 1 (a), x is the vertical interval la of the center portion (spiral center portion) 3, that is, the distance la between the copper tubes 2 adjacent to each other across the center portion 3, and the longitudinal direction of the induction coil 1a. (Vertical direction) Expressed as a ratio to the height L. For example, if x = 0.5, it means that the vertical distance of the central portion 3 is half the height L of the induction coil. In the induction coil 1a, x = 0.65.

  In the induction coil 1a, the distance between the copper pipes 2 adjacent to each other up and down other than the central portion 3 is pa, which is equal. In addition, the distance pa between the copper pipes 2 adjacent in the vertical direction other than the central part 3 is shorter than the distance la between the copper pipes 2 adjacent in the vertical direction in the central part 3. That is, compared to the central portion 3, the copper tubes 2 are densely arranged around the periphery (other than the central portion 3).

  The induction coil 1b shown in FIG. 1 (b) also has a copper tube 2 having a rectangular cross section spiraled on substantially the same plane so that the whole becomes a rectangular shape, and x = 0.11. .

  In the induction coil 1b, the distances between the copper pipes 2 adjacent to each other up and down except for the central portion 3 are pb, and are equally spaced. The distance pb between the copper pipes 2 adjacent to each other in the vertical direction other than the central part 3 is shorter than the distance lb between the copper pipes 2 adjacent in the vertical direction at the central part 3. That is, compared to the central portion 3, the copper tubes 2 are densely arranged around the periphery (other than the central portion 3).

  Here, the induction coils 1a and 1b shown in FIGS. 1A and 1B have the same copper tube 2, the same size (rectangular area), and the same number of turns, but the ratio x is different. That is, in the induction coil 1b, x = 0.11 and the vertical interval lb of the central portion 3 is relatively short in the longitudinal direction of the induction coil 1b. On the other hand, in the induction coil 1a, x = 0.65, and the vertical interval la of the central portion 3 is relatively long in the longitudinal direction of the induction coil 1a.

  As a result, in the induction coil 1b shown in FIG. 1 (b), the distance pb between the copper tubes 2 adjacent to each other in the vertical direction other than the central portion 3 is slightly shorter than the vertical interval lb of the central portion 3. It is about the same level. On the other hand, in the induction coil 1a shown in FIG. 1A, the distance pa between the copper pipes 2 adjacent to each other up and down other than the central portion 3 is significantly shorter than the vertical interval la of the central portion 3. That is, in the induction coil 1a, the upper and lower intervals of the central portion 3 are longer than those of the induction coil 1b, and the degree of density of the copper tube 2 in the periphery (other than the central portion 3) is high. .

  FIG. 2 shows a spatial magnetic flux density distribution generated in the immersion nozzle by the current flowing through the induction coils 1a and 1b. FIG. 3 shows a magnetic field distribution in which eddy currents induced in the outer wall of the immersion nozzle, which is an object to be heated, are generated by the magnetic field generated by the induction coils 1a and 1b. 2 and 3, the horizontal axis represents the normalized magnetic flux density, and the vertical axis represents the normalized distance (height) from the lower end of the induction coil. In FIGS. 2 and 3, Example 1 shows the result of the induction coil 1b, and Example 2 shows the result of the induction coil 1a. The degree of bending of the induction coils 1a and 1b, the conditions of the current applied to the induction coils 1a and 1b, and the like are matched.

  When the vertical distance lb of the central portion 3 is shortened as in the induction coil 1b, the magnetic field of the induction coil itself is small and the distribution is uneven. On the other hand, when the vertical interval la of the central portion 3 is increased as in the induction coil 1a and the distance Pa between the copper tubes 2 in the periphery (other than the central portion 3) is shortened to increase the degree of density, In the vicinity of the upper and lower ends of the coil 1a, the current density (ampere × number of turns) is increased, and the magnetic field emission capability of the entire induction coil is increased although the magnetic field at the center is reduced. As a result, the heat generation density can be increased in the vicinity of the upper and lower ends without greatly reducing the heat generation density in the central portion of the induction coil, so that the total heat generation amount can be increased.

  In FIG. 3, since the magnetic field by eddy current ∝ eddy current and the square of eddy current ∝ heat density, the relationship of ∝ heat density (square of magnetic field by eddy current) holds. From this figure, it can be seen that the induction coil 1a (example 2) generates heat more uniformly in the coil height direction. Further, since the overall heat generation amount is correlated with the area surrounded by the graph of FIG. 3 and the vertical axis (straight line of magnetic flux density = 0), the induction coil 1a (example 2) also increases the overall heat generation amount. I understand that.

  FIG. 4 shows the total calorific value when using induction coils (including induction coils 1a and 1b) having the same copper tube 2, the same size (rectangular area) and the same number of turns, but with the ratio x changed. FIG. In FIG. 4, the horizontal axis represents the ratio x of the central interval with respect to the entire coil, and the vertical axis represents the total heat generation normalized by setting the induction coil 1 b (x = 0.11) to 1.0.

  As shown in FIG. 4, in the case of the same copper tube 2, the same size (rectangular area), and the same number of turns, if x is increased, that is, the vertical distance of the central portion 3 is increased and the central portion 3 is also increased. As the density of the copper tube 2 is increased, the overall heat generation amount can be increased and the heat generation efficiency can be improved. For example, the total heat generation amount in the induction coil 1a is increased 1.39 times compared to the total heat generation amount in the induction coil 1b.

  The distance p between the copper tubes 2 adjacent to each other up and down except for the central portion 3 is limited in its shortest distance because an insulating layer must be secured between the copper tubes 2. In other words, the distance p between the copper pipes 2 adjacent to each other up and down other than the central part 3 is shortened and the degree of denseness of the copper pipe 2 other than the central part 3 is increased, as long as it is allowed within the limit range. Thus, the overall heat generation amount can be increased accordingly.

  As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention. For example, in the above-described embodiment, the longitudinal direction (vertical direction) of the induction coils 1a and 1b has been described, but also in the lateral direction, other than the central portion 3 as compared with the distance between the copper tubes 2 adjacent to the left and right in the central portion 3. Even when the distance between the copper pipes 2 adjacent to each other on the left and right is shortened, the total heat generation amount can be increased.

  Moreover, the heating apparatus demonstrated with reference to FIGS. 5-10 is an example, For example, you may use the induction heating apparatus of this invention for the long nozzle which inject | pours molten steel from a ladle to a tundish. One or three or more induction coils may be arranged around the immersion nozzle. Furthermore, you may make it provide the rotation means which rotates an induction coil relatively centering on the axis center of an immersion nozzle with respect to an immersion nozzle.

It is a figure which shows the induction coil of the induction heating apparatus which concerns on embodiment of this invention. It is a characteristic view which shows the space magnetic flux density distribution by the electric current which flows into an induction coil. It is a characteristic view which shows the magnetic field distribution which the eddy current induced in the immersion nozzle which is an object to be heated is generated by the magnetic field generated by the induction coil. It is a figure which shows the whole emitted-heat amount at the time of using the same copper pipe, the same magnitude | size (rectangular area), the same number of turns, but having changed the ratio x. It is a figure which shows the use condition of the heating apparatus using an induction coil. It is a figure which shows the example of the immersion nozzle heated with the heating apparatus using an induction coil. It is a front view of the heating apparatus using an induction coil. It is a side view of the heating apparatus using an induction coil. It is a top view of the heating apparatus using an induction coil. It is a figure for demonstrating an induction coil. It is a figure for demonstrating a continuous casting installation.

Explanation of symbols

1a induction coil 1b induction coil 2 copper tube 3 center of induction coil

Claims (4)

An induction heating device that induction-heats the injection nozzle by arranging an induction coil in which a linear member is spiraled so as to be rectangular as a whole, is curved along the outer peripheral surface of the injection nozzle of molten metal. And
In at least one of the vertical direction and the horizontal direction of the rectangular induction coil, the distance between adjacent linear members other than the central part is shorter than the distance between adjacent linear members across the central part. An induction heating device characterized by that.   The induction heating according to claim 1, wherein the injection nozzle is a nozzle that injects molten metal from a ladle into a tundish in a continuous casting facility, or a nozzle that injects molten metal from a tundish into a mold. apparatus.   The induction heating according to claim 1 or 2, wherein in at least one of the longitudinal direction and the lateral direction of the rectangular induction coil, adjacent linear members other than the central portion are equally spaced. apparatus.   The induction heating apparatus according to claim 1, wherein the linear member is made of a metal tube.

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