JP2018116933A - Induction heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating apparatus capable of preventing a heated container from being locally heated with a simple structure.SOLUTION: An induction heating apparatus 1 comprises induction heating means 20 of heating a heated container 10 by induction heating when it is installed separated from the heated container 10 at the circumference of the cylindrical heated container 10 in which an upper surface and a lower surface are blocked by lids 11 and 12, and is set to a conductive state and heats vapor in an inner part of the heated container 10. The induction heating means 20 is constructed by a plurality of induction heating coils 21 in which a separation distance from the heated container 10 becomes same, while having the same number of windings to the heated container 10. A separation distance B of a current center of both adjacent induction heating coils 21 is one to three times of the separation distance A of the current center of each induction heating coil 21 and the heated container 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an induction heating apparatus.

  Conventionally, an induction heating coil is provided that is spaced apart from the heated container in such a manner that most of the substantially cylindrical heated container is densely wound in the vertical direction, and the induction heating coil is in an energized state. There is known an induction heating device that heats a heated container by induction heating to heat a fluid inside the heated container (for example, see Patent Document 1).

JP 2010-101564 A

  By the way, it is known that the magnitude of the induced current generated in the heated container is proportional to the magnetic field component along the outer wall of the heated container on the surface of the heated container.

  Therefore, as described above, in the induction heating apparatus in which the induction heating coil is installed away from the heated container in a mode in which the majority of the heated container is wound closely, it faces the central portion of the induction heating coil. In the place where the heat is applied, the magnetic field along the outer wall of the container to be heated becomes large, and the heat generation in the place becomes locally larger than the others. As a result, there is a problem that the heated container is distorted due to thermal expansion, or the fluid inside the heated container is locally expanded.

  In order to eliminate such problems, it is conceivable to wind the induction heating coil around the heated container in a manner in which the central part is sparse and the both ends are dense, but the adjustment of the number of turns and the support method are complicated. There was a fear of becoming.

  In view of the above circumstances, an object of the present invention is to provide an induction heating apparatus capable of preventing a heated container from being locally heated with a simple configuration.

  In order to achieve the above object, an induction heating device according to the present invention is installed around a cylindrical heated container whose upper and lower surfaces are closed by a lid, and is energized. In the induction heating apparatus for heating the fluid inside the heated container, the induction heating means has a number of windings with respect to the heated container. A plurality of induction heating coils that are the same and have the same separation distance from the heated container, and the separation distance between the current centers of the induction heating coils adjacent to each other is the same as the current center of the induction heating coil. It is characterized by being 1 to 3 times the separation distance from the heating container. Here, “the current center of the induction heating coil” indicates the center portion of the longitudinal section when the wire constituting the induction heating coil is a bundle of thin wires that are insulated, and the wire is not insulated. In the case of a bundle of thin wires, a tube or a rod, the inner end portion of the longitudinal section is shown.

  Further, the present invention is the above-described induction heating device, wherein the heated container is a rib that protrudes inward from the inner wall surface so that an internal fluid passes in a meandering manner along the central axis direction of the heated container. Is provided.

  According to the present invention, the induction heating means is composed of a plurality of induction heating coils having the same number of turns to the heated container and the same distance from the heated container. Since the separation distance of the current center is 1 to 3 times the separation distance between the current center of the induction heating coil and the heated container, the heated container is not locally heated. In addition, since the number of turns of each induction heating coil is the same, it is not necessary to adjust the number of turns, and the induction heating coil can be easily supported because it can be installed with a predetermined separation distance. Therefore, it is possible to prevent the heated container from being locally heated with a simple configuration.

FIG. 1 is a schematic diagram schematically showing a main part of an induction heating apparatus according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the generated power density on the surface of the heated container shown in FIG. FIG. 3 shows a modified example of the heated container shown in FIG. 1, and is an explanatory view showing the ribs inside the heated container and the flow of fluid. FIG. 4 shows another modified example of the heated container shown in FIG. 1, and is an explanatory view showing the ribs inside the heated container and the flow of fluid.

  Exemplary embodiments of an induction heating apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram schematically showing a main part of an induction heating apparatus according to an embodiment of the present invention. In addition, since the principal part of the induction heating apparatus is symmetrical with respect to the center line L, only the right half is shown. The induction heating apparatus 1 exemplified here includes a heated container 10, induction heating means 20, and a shield member 30.

  The heated container 10 has a cylindrical shape whose upper and lower surfaces are closed by lids 11 and 12 and is made of, for example, a high-resistance metal such as SUS having magnetism. In the heated container 10, an inlet 11 a is formed in the lower lid 11, and a discharge port 12 a is formed in the upper lid 12. The introduction port 11a is an opening for introducing steam (gas (fluid)) supplied through a supply line (not shown). The discharge port 12a is an opening for discharging the vapor that has passed through the inside to the outside.

  The induction heating means 20 is supported by a support member (not shown), and is installed around the heated container 10 so as to be separated from the heated container 10. The induction heating means 20 includes a plurality of induction heating coils 21. Each induction heating coil 21 has a cylindrical shape in which the number of turns with respect to the heated container 10 is the same and the distance from the heated container 10 is the same.

  These induction heating coils 21 are wound in the same direction and are electrically connected in a serial manner to a power converter (not shown) (not shown), and a voltage having a specific frequency is applied from the power converter. In this case, the heated container 10 is heated by induction heating. Note that the power conversion device incorporates a so-called inverter circuit, and applies an alternating current supplied from a commercial power supply to each induction heating coil 21 as an alternating current having a specific frequency.

  The shield member 30 is held by a holding member (not shown) and is made of, for example, ferrite, and is installed in a manner surrounding the upper area, the lower area, and the outer area of the induction heating means 20. The shield member 30 is for shielding magnetic flux leaking from each induction heating coil 21.

  In the induction heating means 20, the separation distance B between the current centers of the induction heating coils 21 adjacent to each other in the vertical direction is 1 to 3 times the separation distance A between the current center of the induction heating coil 21 and the heated container 10. It is arranged to be.

  Here, the current center of the induction heating coil 21 indicates a central portion of the longitudinal section when the wire constituting the induction heating coil 21 is a bundle of thin wires that have been insulated, and the wire is not insulated. In the case of a bundle of thin wires, a tube or a rod, the inner end portion of the longitudinal section is shown.

  In the induction heating apparatus 1 having the above-described configuration, a voltage having a specific frequency is applied to each induction heating coil 21 constituting the induction heating means 20 from the power converter, and the induction heating coil 21 is energized. As a result, the heated container 10 is heated by induction heating.

  Thereby, while being introduced into the inside of the heated container 10 through the introduction port 11a, the steam passing through the inside upward is heated to generate superheated steam, and the generated superheated steam is discharged to the outside from the discharge port 12a. Discharged.

  In the induction heating means 20, the separation distance B between the current centers of the induction heating coils 21 adjacent to each other in the vertical direction is 1 to 3 times the separation distance A between the current center of the induction heating coil 21 and the heated container 10. 2, when each induction heating coil 21 is energized, the generated power density on the surface of the heated container 10 is substantially uniform along the vertical direction as shown in FIG. 2. Can be. Thereby, the to-be-heated container 10 can be heated substantially uniformly, and the to-be-heated container 10 is not heated locally.

  By the way, if the separation distance B is less than 1 time of the separation distance A, the induction heating coils 21 are too close to each other, thereby causing the current center separation distance between the induction heating coils 21 adjacent to each other vertically. The magnetic field along the outer wall of the heated container 10 is increased at the location of the heated container 10 facing the portion that is approximately half of B, and the heat generation at the location is locally increased compared to the others. As a result, there is a problem that the heated container 10 is distorted due to thermal expansion, or the fluid inside the heated container 10 is locally expanded. On the other hand, when the separation distance B exceeds three times the separation distance A, the induction heating coils 21 are separated from each other, and thereby the location of the heated container 10 facing the central portion of each induction heating coil 21. However, the magnetic field along the outer wall of the container 10 to be heated is increased, and the heat generated at the location is locally increased as compared with the other.

  Here, if the separation distance B is 1 to 3 times the separation distance A, the reason why the heated container 10 can be heated substantially uniformly will be described using an example in which the induction heating coil 21 is a line current.

Among the induction heating coils 21 adjacent to each other vertically, the magnetic field component (H ₁ ) along the outer wall of the heated container 10 at the same height level as the current center of the lower induction heating coil 21 is: Assuming that the line current is I, the following equation (1) is obtained.

Formula (1)
H ₁ = I / (2π) × A × (1 / A ² + 1 / (A ² + B ² ))

On the other hand, the magnetic field component (H ₂ ) along the outer wall of the heated container 10 at a height level B / 2 above the current center of the induction heating coil 21 on the lower side is expressed as follows: It is shown by the following formula (2).

Formula (2)
_{H 2 = I / (2π)} × A × (2 / (A 2 + B 2/4))

Then, assuming that each component is equal and H ₁ = H ₂ , B = √2A is derived from the above equations (1) and (2).

  As described above, according to the induction heating apparatus 1 according to the present embodiment, the induction heating means 20 includes a plurality of windings with the same number of turns around the heated container 10 and the same distance from the heated container 10. The distance B between the current centers of the induction heating coils 21 adjacent to each other is √2 times the distance A between the current center of the induction heating coil 21 and the container 10 to be heated. Therefore, the to-be-heated container 10 is not heated locally. In addition, since the number of turns of each induction heating coil 21 is the same, it is not necessary to adjust the number of turns, and the induction heating coil 21 can be supported by being installed with a predetermined separation distance. is there. Therefore, it is possible to prevent the heated container 10 from being locally heated with a simple configuration.

  Although the induction heating coil 21 is described as an example of a line current, the width of the induction heating coil 21, the thickness of the induction heating coil 21, and the distance from the shield member 30 are adjusted so as to follow the outer wall of the container 10 to be heated. Therefore, the distance B between the current centers of the induction heating coils 21 adjacent to each other is 1 to 3 of the distance A between the current center of the induction heating coil 21 and the container 10 to be heated. By adjusting in the double range, it is possible to prevent the heated container 10 from being locally heated.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made.

  In the present embodiment, the heated container 10 has a cylindrical shape. However, in the present invention, the heated container may have a rectangular tube shape. Specifically, it may be a square cylinder having a rectangular cross section.

  In the present embodiment, the magnetic field leaking outside is shielded by the shield member 30, but in the present invention, a shield coil of a metal ring that is electrically short-circuited may be used.

  In the present invention, as shown in FIG. 3, the steam introduced from the introduction port 11a passes through the inside of the heated container 10 'in a meandering manner along the central axis direction of the heated container 10'. A plurality of ribs 13 protruding inward from the inner wall surface may be formed.

  According to such a configuration, the passing steam can be brought close to the inner wall surface, the heat of the heated container 10 ′ heated by induction heating can be effectively given to the steam, and the heating efficiency is improved. Can do. Further, a part of the steam that passes through becomes a vortex, thereby increasing the residence time inside the heated container 10 ′ and increasing the heat transfer from the heated container 10 ′ to the steam.

  In the present invention, as shown in FIG. 4, the steam introduced from the inlet 11 a passes through the inside of the heated container 10 ″ in a meandering manner along the central axis direction of the heated container 10 ″. A plurality of ribs 13 ′ protruding in a manner that gradually inclines upward from the inner wall surface to the inside may be formed.

  According to such a configuration, it is possible to promote upward flow of steam passing through the inside of the heated container 10 ″ by the inclined rib 13 ′ due to expansion due to heating.

DESCRIPTION OF SYMBOLS 1 Induction heating apparatus 10 Heated container 11 Lid 11a Inlet 12 Lid 12a Discharge port 13 Rib 20 Induction heating means 21 Induction heating coil 30 Shield member

Claims (2)

Induction heating means for heating the heated container by induction heating when it is placed around the cylindrical heated container whose upper and lower surfaces are closed by a lid and is energized. In an induction heating apparatus for heating a fluid inside the heated container,
The induction heating means is composed of a plurality of induction heating coils having the same number of turns to the heated container and the same distance from the heated container, and the current center between the induction heating coils adjacent to each other. An induction heating apparatus characterized in that a separation distance is 1 to 3 times a separation distance between a current center of the induction heating coil and the container to be heated.   The rib to be protruded inward from the inner wall surface is provided in the heated container so that an internal fluid passes in a meandering manner along a central axis direction of the heated container. 2. The induction heating apparatus according to 1.

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