JP2016035811A - Fluid heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heat the fluid to be heated efficiently, while allowing down-sizing of the entire apparatus.SOLUTION: A fluid heating apparatus includes a heating element 2 which generates heat by electromagnetic induction, and an induction coil 3 wound around the heating element 2, and generating magnetic flux in the heating element 2. The induction coil 3 has a first coil element 31 consisting of a hollow conductor tube through which cooling fluid flows, and a second coil element 32 consisting of a solid conductor connected electrically with the first coil element 31. Furthermore, the fluid heating apparatus is configured so that the cooling fluid flowing through the hollow conductor tube is heated, as a fluid to be heated, by the heating element 2, and the second coil element 32 is provided while being wound around the outer periphery of the first coil element 31.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fluid heating apparatus that heats a fluid to be heated, such as water, using a heating element that generates heat by electromagnetic induction.

  As a conventional fluid heating device, for example, as shown in Patent Document 1, an induction coil wound around an outer peripheral portion of a container (cylindrical body) made of an insulator and an induction space accommodated in the internal space of the container are heated. Some have a metal body. This fluid heating apparatus induction-heats a metal body by applying an alternating voltage to an induction coil. And the to-be-heated fluid introduced into the container is heated by the induction-heated metal body, and is led out from the container.

  Further, as a conventional fluid heating device, for example, as shown in Patent Document 2, an induction coil wound around the outer periphery of a container, a heating element that is housed in the inner space of the container and is induction-heated, and a target to be heated Some have a preheating tube that preheats fluid and introduces it into the vessel. This fluid heating apparatus induction heats a heating element by applying an alternating voltage to an induction coil. In addition, this fluid heating device has a preheating tube wound around the outside of the induction coil, and heats the fluid to be heated flowing through the preheating tube by heating the preheating tube by electromagnetic induction by energizing the induction coil. It is configured to be preheated.

  Here, in the fluid heating apparatus as described above, as a configuration for cooling the induction coil, as shown in Patent Document 3, a hollow conductor tube is used for the induction coil, and a cooling fluid is provided inside the hollow conductor tube. The thing of the composition which flows is considered. In addition, this fluid heating apparatus is configured to introduce the cooling fluid that has flowed through the aerial conductor tube into the container as the fluid to be heated.

  However, as shown in Patent Document 3, the winding by the hollow conductor tube has a problem that the induction coil becomes larger and the fluid heating device becomes larger than the winding by the solid conductor having the same cross-sectional area. . Further, since the hollow conductor tube itself generates Joule heat, the induction coil is heated to a high temperature, which is a disadvantage in terms of thermal safety.

JP 2006-147431 A JP 2009-174768 A JP 2006-064367 A

  Accordingly, the present invention has been made to solve the above-mentioned problems, and it is possible to reduce the size of the entire apparatus, and not only to efficiently heat the fluid to be heated but also to improve the thermal safety. It is to be an issue.

  That is, the fluid heating device according to the present invention includes a heating element that generates heat by electromagnetic induction and heats the fluid to be heated, and an induction coil that is wound around the heating element and generates a magnetic flux inside the heating element. The induction coil has a first coil element made of a hollow conductor tube through which a cooling fluid flows, and a second coil element made of a solid conducting wire electrically connected to the first coil element, The cooling fluid that has flowed through the hollow conductor tube is configured to be heated by the heating element as the fluid to be heated, and the second coil element is wound around the outer periphery of the first coil element. It is characterized by being.

  In such a case, since a part of the induction coil is formed from a hollow conductor tube, the heat leaking outside from the heating element is absorbed and a cooling effect is exhibited. Since it forms from the solid conducting wire, the whole induction coil can be reduced in size. Further, since the cooling fluid flowing through the hollow conductor tube is used as the heated fluid, the heated fluid can be preheated and the heating efficiency of the heated fluid can be improved. Further, since the first coil element is wound on the inner side, the cooling fluid (heated fluid) can be efficiently preheated using the heat leaked from the heating element to the outside. Furthermore, since the 1st coil element which consists of a hollow conductor tube exhibits the function which interrupts | blocks the heat which leaks outside from a heat generating body, the thermal safety of a fluid heating apparatus can be improved.

It is desirable that the heating element has an internal channel through which the fluid to be heated flows, and the internal channel of the hollow conductor tube is connected to the internal channel of the heating element.
In this case, since the heating element and the hollow conductor tube are directly connected, it is not necessary to provide another intermediate container between the heating element and the hollow conductor tube, which can contribute to downsizing of the apparatus.

It is desirable to further include a substantially cylindrical iron core element provided so as to cover the outside of the induction coil and forming a magnetic path together with the heating element.
If this is the case, the magnetic resistance of the magnetic flux generated by the induction coil can be reduced, and more magnetic flux can be passed through the heating element, and the heating element can be efficiently heated. Moreover, since the outer side of the induction coil is covered with the iron core element, the heat leaking from the heating element to the outside can be confined in the iron core element, and the thermal safety of the fluid heating device can be improved.

  As a specific embodiment of the heating element, it is desirable that the heating element includes a container formed of a nonmagnetic material and a heat generating element formed of a magnetic material disposed in an internal space of the container. . As described above, since the heat generating element is accommodated in the container made of the non-magnetic material, the thermal safety of the fluid heating device can be improved.

The heating element has a substantially columnar shape and has flange portions formed to extend outward at both axial end portions thereof, and the induction coil is configured to have the two flange portions on the outer periphery of the heating element. It is desirable that the iron core element is provided at the outer end of the two flange portions so as to cover the outer side of the induction coil.
In this case, since the induction coil is arranged in the space formed by the two flange portions and the iron core element, the heat leaking from the outer peripheral surface of the heating element to the outside is confined in the iron core element. Using heat, the cooling fluid (heated fluid) flowing through the hollow conductor tube can be efficiently preheated.

An internal flow path of the heating element includes a first flow path in which the fluid to be heated flows from one axial end to the other axial end, and the heated to the axial one end from the other axial end. It is desirable that the first flow path and the second flow path be in communication with each other.
In this case, since the internal flow path of the heating element is folded back at one end in the axial direction or the other end in the axial direction, the distance between the internal flow paths of the heating element is increased, and the heating element and the fluid to be heated are in contact with each other. The area can be increased, and the heated fluid can be efficiently heated.

The second flow path is formed along the axial direction at the center of the heating element, and a plurality of the first flow paths are formed along the axial direction outside the second flow path, It is desirable that the heated fluid that has flowed through the plurality of first flow paths join together and flow through the second flow path.
In this case, since the plurality of first flow paths are provided, the contact area between the heating element and the fluid to be heated can be increased and the fluid to be heated can be efficiently heated. Moreover, since the fluid to be heated that has flowed through the plurality of first flow paths is merged with the second flow path, it is easy to take out the heated fluid to be heated by removing the fluid to be heated from the second flow path. Can do.

It is desirable that the fluid heating device further includes a first fluid circulation pipe that is provided in the flange portion and through which a fluid that exchanges heat with the flange portion flows.
If it is this, the temperature adjustment of a flange part will be attained, for example, a flange part can be cooled and the thermal safety of an apparatus can be improved.

It is desirable that the fluid flowing through the first fluid circulation pipe is heated by the heating element as the fluid to be heated.
In this case, for example, the heat of the heated fluid can be preheated using the heat of the flange such as heat leaking from the flange to the outside, and the heating efficiency of the heated fluid can be improved.

  As a specific embodiment of the induction coil, the direction of the magnetic flux generated by the first coil element is the same as the direction of the magnetic flux generated by the second coil element. It is desirable that the coil elements are connected in series.

A downstream connection terminal to which the second coil element or an AC power source is connected is provided at or near the connection portion of the first coil element to the heating element, and the fluid heating device is connected to the downstream connection. It is desirable to further include a second fluid circulation pipe that is provided in the terminal and through which a fluid that exchanges heat with the downstream connection terminal flows.
Since the heated fluid preheated by the first coil element passes through the connection portion of the first coil element (hollow conductor tube) to the heating element, the downstream connection terminal provided at or near the connection portion has a high temperature. As a result, the internal resistance increases. For this reason, by providing the second fluid circulation pipe, it is possible to adjust the temperature of the downstream connection terminal, for example, the temperature of the downstream connection terminal can be reduced, and the increase in internal resistance is suppressed to improve the heating efficiency. Can be made.

It is desirable that the fluid flowing through the second fluid circulation pipe is heated by the heating element as the fluid to be heated.
In this case, for example, the fluid to be heated can be preheated using the heat of the downstream connection terminal such as the heat leaking outside from the downstream connection terminal, and the heating efficiency of the fluid to be heated can be improved. .

  It is desirable that the fluid to be heated is water and that generates superheated steam by induction heat generation of the heating element.

  According to the present invention configured as described above, the entire apparatus can be reduced in size, the heated fluid can be efficiently heated, and the thermal safety of the fluid heating apparatus can be improved.

The figure which shows typically the structure of the fluid heating apparatus which concerns on one Embodiment of this invention. AA line sectional view in the embodiment. The figure which shows typically the structure of the fluid heating apparatus which concerns on deformation | transformation embodiment.

  Hereinafter, an embodiment of a fluid heating device according to the present invention will be described with reference to the drawings.

<1. Device configuration>
The fluid heating apparatus 100 according to the present embodiment heats water, which is a fluid to be heated, to generate superheated steam, and generates heat by electromagnetic induction to heat the fluid to be heated as shown in FIG. A body 2, an induction coil 3 that is wound around the heating element 2 and generates a magnetic flux inside the heating element 2, and is provided so as to cover the outside of the induction coil 3. And an iron core element 4 having a substantially cylindrical shape. Hereinafter, each part will be described in detail.

  The heating element 2 is made of carbon steel such as S45C and has a substantially cylindrical shape. Specifically, the heating element 2 has an internal flow path 2R through which a fluid to be heated flows.

  The internal flow path 2R of the heating element 2 includes a first flow path 2R1 through which a fluid to be heated flows from the axial one end 2a toward the other axial end 2b, and an axial second end 2b to the axial one end 2a. A second flow path 2R2 through which the fluid to be heated flows, and a connection flow path 2R3 that connects the first flow path 2R1 and the second flow path 2R2 to each other.

  Each of the first flow path 2R1 and the second flow path 2R2 is a linear flow path that is formed linearly from the axial one end 2a to the other axial end 2b of the heating element 2. One second flow path 2R2 is formed along the axial direction at the center of the heating element 2, and the first flow path 2R1 extends along the axial direction radially outward of the second flow path 2R2. A plurality (12 in FIG. 2) are formed. In the present embodiment, the channel cross-sectional area of the second channel 2R2 is formed larger than the channel cross-sectional area of the first channel 2R1. The plurality of first flow paths R1 have the same flow path cross-sectional area, and are formed at equal intervals on the outer side in the radial direction of the second flow path 2R2.

  The connection flow path 2R3 is formed at the other axial end 2b of the heating element 2, and communicates the first flow path 2R1 and the second flow path 2R2 at the other axial end 2b. . The connection flow path 2R3 of the present embodiment is formed so that all of the plurality of first flow paths 2R1 communicate with one second flow path 2R2. Specifically, the connection flow path 2R3 is the axis of the heating element 2. On the side wall of the other end 2b in the direction, the recess is formed to include the other end opening of the plurality of first flow paths 2R1 and the other end opening of the second flow path 2R2.

  Furthermore, the heating element 2 of the present embodiment has a branch flow path 2R4 for branching and introducing the fluid to be heated introduced from the axial one end 2a of the heating element 2 into the plurality of first flow paths 2R1. ing.

  This branch channel 2R4 is for introducing the fluid to be heated introduced from the introduction port 2P1 formed on the side wall of the axial end portion 2a of the heating element 2 into the plurality of first channels 2R1. Specifically, the branch flow path 2R4 is an annular flow path formed on the side wall of the axial one end portion 2a of the heating element 2 so as to include one end openings of the plurality of first flow paths 2R1.

  The fluid to be heated introduced from the introduction port 2P1 in the heating element 2 configured in this way is branched into a plurality of first flow paths 2R1 by the branch flow path 2R4 and from the axial one end 2a to the other axial end 2b. The fluid to be heated that has flowed through the plurality of first flow paths 2R1 by the connection flow path 2R3 joins at the other end 2b in the axial direction and flows to the second flow path 2R2. And the to-be-heated fluid (superheated water vapor | steam) which flowed in 2nd flow path 2R2 toward the axial direction one end part 2a from the axial other end part 2b was derived | led-out formed in the side wall of the axial direction one end part 2a of the heat generating body 2. It is led out of the apparatus from the port 2P2 and used for heat treatment. In the present embodiment, an external pipe H1 is connected to the derivation port 2P2.

  The induction coil 3 includes a first coil element 31 made of a hollow conductor tube through which a cooling fluid flows, and a second coil element 32 made of a solid conductor electrically connected to the first coil element 31. Yes.

  In the first coil element 31 and the second coil element 32, the direction of the magnetic flux generated in the heating element 2 by the first coil element 31 and the direction of the magnetic flux generated in the heating element 2 by the second coil element 32 are the same. Are connected in series.

  Specifically, the first coil element 31 and the second coil element 32 are wound around the outer periphery of the heating element 2 between the flange parts 21 and 22 formed at the axial ends 2a and 2b of the heating element 2. Is provided. The flange portions 21 and 22 extend radially outward from the outer peripheral surface of the heating element 2 at both axial end portions 2 a and 2 b of the heating element 2. More specifically, the first coil element 31 is provided by being wound between the flange portions 21 and 22 on the outer periphery of the heating element 2, and the second coil element 32 is wound on the outer periphery of the first coil element 31. It is provided in a substantially concentric manner by turning. FIG. 1 shows a state in which the first coil element 31 is wound in two layers and the second coil element 32 is wound in three layers, but the present invention is not limited to this, Single-layer winding may be used, and multilayer winding other than the above may be used.

  One end portion 31 a of the hollow conductor tube that is the first coil element 31 is connected to an introduction port 2 </ b> P <b> 1 provided on the side wall of the axial end portion 2 a of the heating element 2. Thereby, the internal flow path of the hollow conductor tube is connected to the internal flow path 2R of the heating element 2, and the cooling fluid that has flowed through the first coil element 31 that is the hollow conductor pipe is heated by the heating element 2 as a fluid to be heated. Heated.

  In addition, a downstream connection terminal 311 to which one power supply terminal of an AC power supply (not shown) is connected is provided at or near one end 31a which is a connection portion of the first coil element 31 to the heating element 2. . Further, the other end portion 31 b of the first coil element 31 is provided with an upstream connection terminal 312 to which one end portion of the second coil element 32 or an intermediate conductor connected to the second coil element 32 is connected. The other power supply terminal of the AC power supply is connected to the other end of the second coil element 32.

  In the present embodiment, the flange portion 21 of the axial one end portion 2a has, for example, a through hole or the like for extending the one end portion 31a and the other end portion 31b of the first coil element 31 to the outside of the flange portion 21. A take-out portion 211 is formed. In addition, the downstream connection terminal 311 and the upstream connection terminal 312 are provided on the one end portion 31 a and the other end portion 31 b of the first coil element 31 at portions extending outward from the take-out portion 211 of the flange portion 21.

  The iron core element 4 is provided at the radially outer ends of the two flange portions 21 and 22 so as to cover the entire outer circumference of the induction coil 3 in the radial direction. The iron core element 4 has a substantially cylindrical shape, and is disposed concentrically with the heating element 2 by being provided on the two flange portions 21 and 22. With this configuration, the induction coil 3 (the first coil element 31 and the second coil element 32) is schematically formed by the outer peripheral surface of the heating element 2, the two flange portions 21 and 22, and the inner peripheral surface of the iron core element 4. It becomes the structure accommodated in the space which makes a cylindrical shape.

  The iron core element 4 of the present embodiment is a cylindrical iron core formed by stacking a plurality of magnetic steel plates 41 having a curved portion whose cross-section in the width direction has a curved shape such as an involute curve shape, shifted in the width direction and stacked. . Note that the magnetic steel plate 41 shown in FIG. 2 has a bent portion formed by bending in the same direction as the bending direction of the bending portion, continuously from the inner diameter side end portion in the width direction of the bending portion.

  In the fluid heating apparatus 100 of the present embodiment configured as described above, by applying an AC voltage to the downstream connection terminal 311 of the first coil element 31 and the other end of the second coil element 32 by an AC power source, a heating element The magnetic flux passes through the interior of 2 along the axial direction, and the magnetic flux flows to the iron core element 4 via the flange portions 21 and 22. By the passage of the magnetic flux, an induced current flows through the heating element 2 and the heating element 2 generates Joule heat. Thereby, the fluid to be heated flowing through the internal flow path 2R of the heating element 2 is heated.

  At this time, the hollow conductor tube which is the first coil element 31 is heated by energization when an AC voltage is applied, and is also heated by the heat transmitted from the outer peripheral surface of the heating element 2. As a result, the heated fluid introduced into the internal flow path 2 </ b> R of the heating element 2 is preheated by the first coil element 31. In addition, the first coil element 31 absorbs heat from the heating element 2, and the heat from the heating element 2 is not easily transmitted to the second coil element 32.

  Moreover, in this embodiment, the 1st fluid circulation pipe 5 through which the fluid which performs heat exchange between the flange parts 21 and 22 flows is provided. In the first fluid circulation pipe 5 of the present embodiment, heat is received from the flange portions 21 and 22, and a fluid for cooling the flange portions 21 and 22 flows. In addition, by controlling the temperature of the fluid flowing through the first fluid circulation pipe 5, the flange portions 21 and 22 can be kept at a predetermined temperature, or the flange portions 21 and 22 can be heated.

  The first fluid circulation pipe 5 is provided on the outer surface in the axial direction of the flange portions 21 and 22 in direct contact or via a member having high thermal conductivity. Specifically, the first fluid circulation pipe 5 is provided over the entire circumferential direction on the axially outer side surfaces of the flange portions 21 and 22. The first fluid circulation pipe 5 is connected to a hollow conductor pipe which is the first coil element 31, and the fluid flowing through the first fluid circulation pipe 5 flows into the heating element 2 after flowing through the first coil element 31. It is configured to be introduced. In addition, it is good also as a structure which introduces the fluid which flowed through the 1st fluid circulation pipe 5 directly into the heat generating body 2. FIG. Moreover, you may form in the inside of the flange parts 21 and 22 the flow path through which the fluid which performs heat exchange with the flange parts 21 and 22 flows.

  Furthermore, in this embodiment, the 2nd fluid circulation pipe 6 through which the fluid which performs heat exchange between the downstream connection terminals 311 of the 1st coil element 31 flows is provided. In the second fluid circulation pipe 6 of this embodiment, a fluid for receiving heat from the downstream connection terminal 311 and cooling the downstream connection terminal 311 flows. In addition, by controlling the temperature of the fluid flowing through the second fluid circulation pipe 6, the downstream connection terminal 311 can be kept at a predetermined temperature, or the downstream connection terminal 311 can be heated.

  The second fluid circulation pipe 6 is provided in direct contact with the downstream connection terminal 311 or via a member having high thermal conductivity. The second fluid circulation pipe 6 is connected to a hollow conductor pipe which is the first coil element 31, and the fluid flowing through the second fluid circulation pipe 6 flows into the heating element 2 after flowing through the first coil element 31. It is configured to be introduced. The fluid flowing through the second fluid circulation pipe 6 may be directly introduced into the heating element 2, or the second fluid circulation pipe 6 may be connected to the first fluid circulation pipe 5. Further, the second fluid circulation pipe 6 may be integrally formed with the downstream connection terminal 311.

<2. Effects of this embodiment>
According to the fluid heating apparatus 100 configured as described above, a part of the induction coil 3 is formed from the hollow conductor tube (first coil element 31), and therefore, the heat leaking outside from the heating element 2 is absorbed. While exhibiting a cooling effect, since the induction coil 3 is partially formed from the solid conductor (second coil element 32), the entire induction coil 3 can be reduced in size. Further, since the cooling fluid that has flowed through the hollow conductor tube (first coil element 31) is used as the heated fluid, the heated fluid can be preheated, and the heating efficiency of the heated fluid can be improved. Furthermore, since the first coil element 31 is wound on the inner side, the cooling fluid (heated fluid) can be preheated efficiently by using the heat leaked to the outside from the heating element 2. Furthermore, since the first coil element 31 formed of the hollow conductor tube exhibits a function of blocking heat leaking from the heating element 2 to the outside, the thermal safety of the fluid heating device 100 can be improved.

  Moreover, according to the fluid heating apparatus 100 of the present embodiment, since the iron core element 4 is provided on the two flange portions 21 and 22 of the heating element 2, the magnetic resistance of the magnetic flux generated by the induction coil 3 can be reduced, and more A lot of magnetic flux can be passed through the heating element 2, and the heating element 2 can be efficiently heated. In addition, since the induction coil 3 is arranged in a space formed by the two flange portions 21 and 22 and the iron core element 4, heat leaking from the heating element 2 to the outside can be confined in the iron core element 4. It is possible to further improve the thermal safety of the fluid heating device 100.

<3. Modified Embodiment of the Present Invention>
The present invention is not limited to the above embodiment.

  For example, the internal flow path of the heating element in the above embodiment is composed of a plurality of first flow paths and a single second flow path, but is composed of a plurality of first flow paths and a plurality of second flow paths. It may be. At this time, one second channel may be configured to communicate with one first channel, or a plurality of second channels may communicate with one first channel. You may comprise, and you may comprise so that one 2nd flow path may be connected with respect to several 1st flow paths. In addition, when it has a some 2nd flow path, it is desirable to join the some 2nd flow path and to derive a to-be-heated fluid (superheated steam) from the derivation | leading-out port of a heat generating body.

  Moreover, although the internal flow path of the heating element of the above embodiment is configured to be folded once at the other axial end, it may be folded back at the other axial end and one axial end to be folded back multiple times as a whole. good.

  Furthermore, in the embodiment, the entire heating element is made of a magnetic material, but a part of the heating element may be made of a magnetic material. Specifically, as shown in FIG. 3, the heating element 2 includes a housing 201 formed of a nonmagnetic material, and a heating element (iron core element) made of a magnetic material disposed in the internal space of the housing 201. 202 may be adopted. In the case shown in FIG. 3, the container 201 has a substantially cylindrical shape, and the first flow path 2 </ b> R <b> 1 is formed on the side peripheral wall of the container 201. An introduction port 2P1 and a lead-out port 2P2 are formed in the container 201. A heating element 202 having a substantially cylindrical shape is disposed in the inner space of the container 201 along the central axis direction. With this configuration, a substantially cylindrical space formed between the container 201 and the heat generating element 202 becomes the second flow path 2R2.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 ... Fluid heating apparatus 2 ... Heat generating body 2R ... Internal flow path 2R1 ... 1st flow path 2R2 ... 2nd flow path 21, 22 ... Flange part 3 ... Induction coil 31 ... 1st coil element 311 ... Downstream connection terminal 32 ... 2nd coil element 4 ... Core element 5 ... 1st fluid circulation pipe 6 ... 2nd fluid circulation pipe

Claims (13)

A heating element that generates heat by electromagnetic induction and heats the fluid to be heated;
An induction coil that is wound around the heating element and generates a magnetic flux inside the heating element;
The induction coil has a first coil element made of a hollow conductor tube through which a cooling fluid flows, and a second coil element made of a solid conductor electrically connected to the first coil element;
The cooling fluid flowing through the hollow conductor tube is configured to be heated by the heating element as the heated fluid,
The fluid heating apparatus in which the second coil element is provided by being wound around an outer periphery of the first coil element. The heating element has an internal flow path through which the fluid to be heated flows.
The fluid heating apparatus according to claim 1, wherein an internal flow path of the hollow conductor tube is connected to an internal flow path of the heating element.   The fluid heating apparatus according to claim 1, further comprising a substantially cylindrical iron core element that is provided so as to cover the outside of the induction coil and forms a magnetic path together with the heating element. The heating element has a substantially columnar shape, and has flange portions formed extending outwardly at both axial end portions thereof,
The induction coil is provided by being wound between the two flange portions on the outer periphery of the heating element,
The fluid heating apparatus according to claim 3, wherein the iron core element is provided at an outer end portion of the two flange portions so as to cover an outer side of the induction coil.   An internal flow path of the heating element includes a first flow path in which the fluid to be heated flows from one axial end to the other axial end, and the heated to the axial one end from the other axial end. The fluid heating apparatus according to claim 1, further comprising a second flow path through which a fluid flows, wherein the first flow path and the second flow path communicate with each other. The second flow path is formed along the axial direction at the center of the heating element,
A plurality of the first flow paths are formed along the axial direction outside the second flow paths;
The fluid heating apparatus according to claim 5, wherein the fluids to be heated that have flowed through the plurality of first flow paths merge to flow through the second flow path.   The fluid heating according to any one of claims 1 to 6, wherein the heating element includes a container formed of a non-magnetic material and a heating element formed of a magnetic material disposed in an internal space of the container. apparatus.   The fluid heating apparatus according to claim 4, further comprising a first fluid circulation pipe that is provided in the flange portion and through which a fluid that exchanges heat with the flange portion flows.   The fluid heating apparatus according to claim 8, wherein the fluid flowing through the first fluid circulation pipe is configured to be heated by the heating element as the fluid to be heated.   The first coil element and the second coil element are connected in series so that the direction of magnetic flux generated by the first coil element and the direction of magnetic flux generated by the second coil element are the same. The fluid heating apparatus according to any one of claims 9 to 10. A downstream connection terminal to which the second coil element or an AC power source is connected is provided at or near the connection portion to the heating element in the first coil element,
The fluid heating apparatus according to claim 10, further comprising a second fluid circulation pipe provided in the downstream connection terminal and through which a fluid exchanging heat with the downstream connection terminal flows.   The fluid heating apparatus according to claim 11, wherein the fluid flowing through the second fluid circulation pipe is heated by the heating element as the fluid to be heated. The heated fluid is water;
The fluid heating device according to any one of claims 1 to 12, wherein superheated steam is generated by induction heat generation of the heating element.