Induction oven inductor

Abstract

Induction Oven Inductor This description relates to an induction oven inductor (20) comprising a first tube (30), through which a cooling fluid is intended to circulate, and a second tube (40), the first tube being housed within the second tube, an internal volume (50), containing a material such as a liquid, a gas, or a porous solid, or being under vacuum, being present between at least a portion of the first tube (30) and the second tube (40). Figure for the abbreviation: Figure 3

Description

Title of the invention: Inductor for induction furnace Technical field

[0001] The present description relates generally to an inductor for an induction furnace, and in particular to an inductor cooled by a cooling fluid. Prior art

[0002] [Fig.l] schematically represents an induction furnace 10. The induction furnace 10 comprises a crucible 11 surrounded by an inductor 12, which, when it has the general shape of a coil, is also called an induction coil. The crucible 11 and the part of the coil 12 surrounding the crucible 11 are arranged in an enclosure 13. A load, not visible in [Fig.l], is arranged in the crucible 11. An electric current flows in the coil 12 to generate an intense magnetic field and the heating of the load is carried out by electromagnetic induction.

[0003] To reduce heating of the coil 12 during operation, it is known to use as coil 12 a hollow profile (for example a tube) in which a cooling fluid 14 is circulated.

[0004] In the event of local rupture of the coil 12, cooling fluid may escape from the coil 12. This may cause damage to the induction furnace and / or risks for the operators of the induction furnace, in particular due to chain reactions, steam explosions, generation of explosive gases, etc. For certain applications, it is desirable that the risk of cooling fluid leakage be reduced as much as possible. Summary of the invention

[0005] An object of an embodiment is to overcome all or part of the disadvantages of known induction furnace inductors.

[0006] One embodiment provides an inductor for an induction furnace comprising a first tube, in which a cooling fluid is intended to circulate, and a second tube, the first tube being housed in the second tube, an internal volume, containing a material from among a liquid, a gas, or a porous solid, or being placed under vacuum, being present between at least a portion of the first tube and the second tube.

[0007] According to one embodiment, the first tube is in contact with the second tube.

[0008] According to one embodiment, the inductor comprises a central part comprising coils and extending at each end by a connection zone.

[0009] According to one embodiment, the first tube comprises a wall oriented towards the inside of the turns, and the first tube is in contact with said wall.

[0010] According to one embodiment, the first tube successively comprises, in each connection zone, a first portion of constant cross-section corresponding to a first cross-section, a second portion of variable cross-section from the first cross-section to a second cross-section, and a third portion of constant cross-section corresponding to the second cross-section, and the second tube successively comprises, in each connection zone, a fourth portion of constant cross-section corresponding to a third cross-section, a fifth portion of variable cross-section from the third cross-section to a fourth cross-section, and a sixth portion of constant cross-section corresponding to the fourth cross-section.

[0011] According to one embodiment, the connection between the first and second portions is not in the same plane as the connection between the fourth and fifth portions and the connection between the second and third portions is not in the same plane as the connection between the fifth and sixth portions.

[0012] An embodiment also provides an induction furnace comprising an inductor as defined above, and comprising a system for controlling the inductor comprising a first device configured to circulate a cooling fluid in the first tube and a processing module configured to detect a leak of the cooling fluid.

[0013] According to one embodiment, the induction furnace further comprises at least one sensor configured to detect a physical parameter of the internal volume or of the cooling fluid circulating in the first tube, and comprising a processing module configured to detect the occurrence of a leak of the cooling fluid out of the first tube by detecting a variation in the physical parameter.

[0014] According to one embodiment, the sensor is chosen from the group comprising a sensor of the pressure of the gas in the internal volume of the inductor, a sensor of the pressure of the cooling fluid in the first tube, a sensor of the flow rate of the cooling fluid in the first tube, a sensor of the temperature of the cooling fluid in the first tube, a sensor of the temperature of the gas in the internal volume of the inductor, and a sensor of the composition of the gas in the internal volume of the inductor.

[0015] According to one embodiment, the induction furnace further comprises a second device configured to circulate the gas in the internal volume of the inductor upon detection of a leak of the cooling fluid. Brief description of the drawings

[0016] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0017] [Fig.l], described above, is a partial and schematic cutaway perspective view of an induction furnace;

[0018] [Fig.2] is a partial and schematic perspective view of an embodiment of an induction coil for an induction furnace;

[0019] [Fig.3] is a perspective view with section, partial and schematic, of the coil of [Fig.2];

[0020] [Fig.4] is an enlarged view of a portion of [Fig.3];

[0021] [Fig.5] is a perspective view with section, partial and schematic, of a first end of the coil of [Fig.2];

[0022] [Fig.6] is a perspective view with section, partial and schematic, of a second end of the coil of [Fig.2];

[0023] [Fig.7], [Fig.8], and [Fig.9] are each a perspective view with section of the coil of [Fig.2] at the first end;

[0024] [Fig. 10] is a perspective view with section, partial and schematic, of an alternative embodiment of a coil for an induction furnace at the level of a turn;

[0025] [Fig. 1 1] is a perspective view with section, partial and schematic, of another variant embodiment of a coil for an induction furnace at the level of several turns;

[0026] [Fig. 12] is a partial and schematic perspective view of another alternative embodiment of a coil for an induction furnace;

[0027] [Fig. 13] is a perspective view with partial and schematic section of the coil of [Fig. 12] at the level of one turn; and

[0028] [Fig. 14] is a block diagram of one embodiment of a method for detecting a failure of the coil of [Fig.2]. Description of the embodiments

[0029] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties. For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been shown and are detailed.

[0030] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures or to an induction coil in a normal position of use.

[0031] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean within 10%, preferably within 5%. Unless otherwise specified, ordinal numeral adjectives, such as "first", "second", etc., are used only to distinguish elements from one another. In particular, these adjectives do not limit the described embodiments to a particular order of these elements.

[0032] [Fig. 2] is a partial and schematic perspective view of an embodiment of an induction furnace 15 comprising an inductor 20 and a system 60 for controlling the inductor 20. The inductor 20 generally has the shape of a coil and is also called an induction coil hereinafter. [Fig. 3] is a partial and schematic perspective view with section of the coil 20 of [Fig. 2], and [Fig. 4] is an enlarged view of a portion of [Fig. 3].

[0033] The coil 20 comprises a central part 22 extending, at a first end 23, by a first connection zone 24, and extending at a second end 25, opposite the first end 23, by a second connection zone 26. In the central part 22, the coil 20 forms turns 28 of axis D intended to surround a crucible, not shown. In [Fig. 3], the separation between the interior INT of the enclosure, not shown, of the induction furnace and the exterior EXT of the enclosure of the induction furnace has been indicated schematically by a vertical dotted line.

[0034] As can be seen in Figures 3 and 4, the coil 20 comprises a first tube 30, also called the inner tube, and a second tube 40, also called the outer tube. The inner tube 30 comprises first and second opposite ends 31 and 32 and the outer tube 40 comprises first and second opposite ends 41 and 42. The inner tube 30 is housed in the outer tube 40, except possibly at its ends 31 and 32. The inner tube 30 and the outer tube 40 delimit an internal volume 50 located between the inner tube 30 and the outer tube 40.According to one embodiment, the coil 20 comprises a closure piece 51 fixed to the first end 41 of the outer tube 40, connecting the outer tube 40 to the inner tube 30 at the first end 41 of the outer tube 40, and closing the inner volume 50 at the first end 41 of the outer tube 40 and the coil 20 comprises a closure piece 52 fixed to the second end 42 of the outer tube 40, connecting the outer tube 40 to the inner tube 30 at the second end 42 of the outer tube 40, and closing the inner volume 50 at the second end 42 of the outer tube 40.

[0035] A cooling fluid is present in the inner tube 30. The cooling fluid may be a coolant, for example water.

[0036] According to one embodiment, the internal volume 50 is filled with a fluid (in the liquid or gaseous state) or a porous solid, or is placed under vacuum. According to one embodiment, when the internal volume 50 is filled with a porous solid, the porous solid is a foam, fibers, or powder, in particular a metal matrix foam, for example a copper foam. According to one embodiment, when the internal volume 50 is filled with a gas, the gas is chosen from the group comprising helium, argon, nitrogen, air, a refrigerant such as Freon or a mixture of at least two of these gases. Preferably, the gas is helium. The pressure in the internal volume 50 may be higher or lower than the pressure in the internal tube 30. According to one embodiment, the pressure difference between the internal volume 50 and the internal tube 30 varies between -1 bar (-0.1 MPa) and 5 bar (0.5 MPa). According to one embodiment, the pressure in the internal volume 50 is in the range of -1 bar relative (which corresponds to an absolute pressure of 1325 Pa) to 10 bar relative (which corresponds to an absolute pressure of 1.1013 MPa). According to one embodiment, a partial vacuum is created in the internal volume 50.In this case, the pressure in the internal volume 50 is lower than the pressure of the internal tube 30. According to another embodiment, the gas pressure in the internal volume 50 is higher than the pressure of the cooling fluid. According to another embodiment, the gas pressure in the internal volume 50 is preferably higher than 500 kPa when the pressure of the cooling fluid in the internal tube 30 is of the order of 300 kPa.

[0037] The inner tube 30 and the outer tube 40 are each made of a material that is a good heat conductor and a good electrical conductor. According to one embodiment, the inner tube 30 and the outer tube 40 are, in whole or in part, made of metal or a metal alloy, for example copper, copper alloy, stainless steel, titanium alloy, aluminum alloy, or graphite.

[0038] The outer tube 40 comprises a wall 43 facing the crucible in the central portion 22. According to the embodiment illustrated in Figures 2, 3, and 4, at the turns 28, the wall 43 follows a helical curve of axis D and rests on a cylinder with a circular base of axis D. As a variant, the turns 28 may have a different shape, for example resting on a prism with a square base or corresponding to a spiral extending on a plane. According to one embodiment, the inner tube 30 is in contact with the wall 43 of the outer tube 40 at least in the central portion 22 of the coil 20. According to one embodiment, the inner tube 30 is fixed to the wall 43 of the outer tube 40, for example by welding, brazing, tacking, or any other holding device, such as for example riders.Alternatively, a gap of the internal volume 50 may be provided between the external tube 40 and the internal tube 30 if the heat exchanges between the external tube 40 and the internal tube 30 remain sufficient to allow effective cooling of the external tube 40.

[0039] According to one embodiment, devices making it possible to increase the heat exchange between the internal tube 30 and the external tube 40 can be provided, such as for example: - cooling fins present on the internal tube 30 and / or on the external tube 40; - the installation of a foam, for example a copper foam, a thermally conductive wool, or a thermal grease between the internal tube 30 and the external tube 40; - the installation of a thermal interface element; and - the production of the internal tube 30 and the external tube 40 in two materials with different expansion coefficients so as to improve the contact pressure between the internal tube 30 and the external tube 40 in operation.

[0040] The system 60 for controlling the coil 20 comprises a generator 61 connected to the outer tube 40 or to the inner tube 30 in the first connection zone 24 and in the second connection zone 26 and configured to circulate a current in the outer tube 40. The system 60 for controlling the coil 20 further comprises a device 62 for circulating the cooling fluid, for example water, in the inner tube 30, the cooling fluid being, for example, injected through the second end 32 of the inner tube 30 and being recovered through the first end 31 of the inner tube 30.

[0041] According to one embodiment, the system 60 for controlling the coil 20 further comprises a device 63 for circulating the gas in the internal volume 50, the gas being injected by a first nozzle 64 connected to the external tube 40 and opening into the volume 50, near the first end 41 of the external tube 40, and being recovered by a second nozzle 65 connected to the external tube 40 and opening into the volume 50 near the second end 42 of the external tube 40. According to one embodiment, the device 63 for circulating the gas in the internal volume 50 is not present, and the volume 50 is hermetically sealed creating a static atmosphere, and therefore static reference conditions.

[0042] According to one embodiment, the system 60 for controlling the coil 20 further comprises a processing module 64, comprising in particular a processor, for example a microcontroller, and configured to exchange data with the generator 61, the device 62, and the device 63. According to one embodiment, the system 60 for controlling the coil 20 further comprises at least one sensor 65 connected to the processing module 64.

[0043] In operation, the circulation of a current in the outer tube 40 causes the charge contained in the crucible to be heated by induction. This also causes the coil 20 to heat up, in particular in the central part 22, and in particular at the wall 43 of the outer tube 40. The circulation of the cooling fluid in the inner tube 30 allows the inner tube 30 and the outer tube 40 to be cooled by heat exchange between the inner tube 30 and the outer tube 40.

[0044] The inner tube 30 and the outer tube 40 form a double-walled enclosure. As a result, in the event of a local rupture of the inner tube 30, the cooling fluid advantageously remains contained in the internal volume 50 and does not escape outside the coil 20. Furthermore, according to an embodiment described in more detail below, a rupture of the outer tube 40 can also be detected, making it possible to put the installation into safety mode in a preventive manner, for example by draining the cooling fluid contained in the inner tube 30. Furthermore, according to an embodiment described in more detail below, a rupture of the inner tube 30 and of the outer tube 40 is detected and the most appropriate fallback mode is then executed, for example stopping the heating and / or draining the cooling fluid contained in the inner tube 30 with possibly purging the inner tube 30.In the embodiment illustrated in Figures 2 to 4, the inner tube 30 has a cross section having the shape of a square with rounded edges. In the embodiment illustrated in Figures 2 to 4, the outer tube 40 may be formed by assembling a first part and a second part, the first part corresponding to the wall 43 and the second part 44 corresponding to a wall having a cross section in the shape of a "U", which is for example welded to the wall 43. The wall 43 and the part 44 may have the same thicknesses, as shown in [Fig. 4]. Alternatively, the wall 43 and the part 44 may have different thicknesses. The wall 43 and the part 44 may be made of the same material or be made of different materials. However, the cross section of the inner tube 30 and the cross section of the outer tube 40 may be different from those shown in Figures 2 to 4.In particular, the cross section of the inner tube 30 and the cross section of the outer tube 40 at the level of the turns 28 may be circular.

[0045] The inner tube 30 and the outer tube 40 may each be formed from successive tube portions connected to each other, for example by welding, brazing, gluing, or by using a thermally conductive paste. In this case, the connections on the inner tube 30 are preferably offset relative to the connections on the outer tube 40 so as not to have any areas of mechanical weakness facing each other. In particular, this advantageously allows excessive mechanical stresses not to be exerted on the connections between the portions of the outer tube 40 in the event that a break occurs at a connection between portions of the inner tube 30.

[0046] When the cross-section of the outer tube 40 and / or the cross-section of the inner tube 30 are not circular at the central portion 22, it may nevertheless be desirable for the cross-section of the outer tube 40 and / or for the cross-section of the inner tube 30 to be circular outside the central portion 22, for example to facilitate the passage of the tubes 30 and 40 through an enclosure. For this purpose, a change in the cross-section of the cross-section of the outer tube 40 and / or a change in the cross-section of the straight section of the inner tube 30 can be produced in the first connection zone 24 and / or in the second connection zone 26.

[0047] [Fig. 5] is a partial and schematic sectional perspective view of the first connection area 24 of the coil 20 of [Fig. 2]. [Fig. 6] is a partial and schematic sectional perspective view of the second connection area 26 of the coil 20 of [Fig. 2]. [Fig. 7], [Fig. 8], and [Fig. 9] are each a sectional perspective view of the coil 20 of [Fig. 2] at different locations in the second connection area 26 of the coil 20.

[0048] In each connection zone 24, 26, the internal tube 30 successively comprises, from the end 24, 25 of the central part 22 to each end 31, 32, a portion 35 of constant section whose cross-section can correspond to that of the central part 22, for example square with rounded edges, a portion 36 of variable cross-section from the cross-section of the portion 35 to a circular cross-section, and a portion 37 of constant and circular cross-section. In each connection zone 24, 26, the external tube 40 successively comprises, from the end 24, 25 of the central part 22 to each end 41, 42, a portion 45 of constant section whose cross section is similar to that of the central part 22, for example square with rounded edges, a portion 46 of variable cross section from the cross section of the portion 45 to a circular cross section, and a portion 47 of constant and circular cross section.

[0049] According to one embodiment, neither the connection between the portions 35 and 36, nor the connection between the portions 36 and 37 are located in the same plane as the connection between the portions 45 and 46 and the connection between the portions 46 and 47. This means that the connections between the portions 35 and 36 and between the portions 36 and 37 are offset relative to the connections between the portions 45 and 46 and between the portions 46 and 47 when moving along the coil 20. When these connections are made by welding, by brazing, by gluing, or by using thermally conductive paste, this advantageously allows excessive mechanical stresses not to be exerted on the connections between the portions 45 and 46 and between the portions 46 and 47 in the event that a break occurs at the connection between the portions 35 and 36 or at the connection between sections 36 and 37.

[0050] [Fig. 10] is a perspective view with section, partial and schematic, of an alternative embodiment of the coil 20 at the level of a turn 28. The internal tube 30 and the external tube 40 of the coil 20 shown in [Fig. 10] have the same shapes as those shown in [Fig. 4] with the difference that the thickness of the wall 43 of the external tube 40 is greater than the thickness of the part 44 of the external tube 40.

[0051] [Fig. 11] is a perspective view with section, partial and schematic, of another variant embodiment of the coil 20 at the level of several turns 28. The tube The inner tube 30 and the outer tube 40 of the coil 20 shown in [Fig. 1 1] have the same shapes as those shown in [Fig. 10] except that the inner tube 30 includes cooling fins 34 which project from the wall of the inner tube 30 adjacent to the wall 43 of the outer tube 40 towards the inside of the inner tube 30. The cooling fins 34 make it possible to increase the heat exchange between the inner tube 30 and the outer tube 40.

[0052] [Fig. 12] is a partial and schematic perspective view of a variant of embodiment of the coil 20 and [Fig. 13] is a perspective view with section, partial and schematic, of the coil 20 of [Fig. 12] at the level of a turn 28. In [Fig. 12], the first and second connection zones 24, 26 are not shown. In this variant, the internal tube 30 has a cross section in the shape of a semicircle and the external tube 40 has a cross section in the shape of a semicircle.

[0053] According to one embodiment, the processing module 64 is configured to detect the occurrence of a leak of the cooling fluid out of the internal tube 30.

[0054] According to one embodiment, the sensor 65 is configured to detect a physical parameter of the cooling fluid circulating in the internal tube 30 or of the gas / vacuum contained in the internal volume 50, and the processing module 64 is configured to detect the occurrence of a leak of the cooling fluid out of the internal tube 30 by detecting a variation in the physical parameter.

[0055] According to one embodiment, the sensor 65 corresponds to a sensor of the pressure of the cooling fluid in the internal tube 30. According to one embodiment, the processing module 64 is configured to detect the occurrence of a leak of the cooling fluid out of the internal tube 30 by detecting a variation in the pressure of the cooling fluid in the internal tube 30.

[0056] According to one embodiment, the sensor 65 corresponds to a sensor of the pressure of the gas in the internal volume 50. According to one embodiment, the processing module 64 is configured to detect the occurrence of a leak of the cooling fluid out of the internal tube 30 by detecting a variation in the pressure of the gas in the internal volume 50. According to one embodiment, the pressure of the gas in the internal volume 50 is greater than the pressure of the cooling fluid in the internal tube 30. In this case, the processing module 64 can detect the occurrence of a leak of the cooling fluid out of the internal tube 30 by detecting a decrease in the pressure of the gas in the internal volume 50.

[0057] According to one embodiment, the sensor 65 corresponds to a sensor of the composition of the gas in the internal volume 50. In this case, the processing module 64 can detect the occurrence of a leak of the cooling fluid out of the internal tube 30 by the detection of traces of the cooling fluid by the sensor 65.

[0058] According to one embodiment, the sensor 65 corresponds to a flow rate sensor of the coolant in the inner tube 30. In this case, the processing module 64 can detect the occurrence of a leak of the coolant out of the inner tube 30 by detecting a variation in the flow rate of the coolant in the inner tube 30.

[0059] According to one embodiment, the sensor 65 corresponds to a sensor of the temperature of the gas in the internal volume 50. In this case, the processing module 64 can detect the occurrence of a leak of the cooling fluid out of the internal tube 30 by detecting a variation in the temperature of the gas.

[0060] According to one embodiment, the sensor 65 corresponds to a sensor of the temperature of the cooling fluid at a location of the internal tube 30. In this case, the processing module 64 can detect the occurrence of a leak of the cooling fluid out of the internal tube 30 by detecting a variation in the temperature of the cooling fluid.

[0061] According to one embodiment, the sensor 65 corresponds to a probe configured to detect flooding in the internal volume 50. In this case, the processing module 64 can detect the occurrence of a leak of the cooling fluid out of the internal tube 30 by the detection of flooding in the internal volume 50 by the probe.

[0062] According to one embodiment, the sensor 65 corresponds to a sensor configured to analyze the composition of the gas circulating in the internal volume 50 in an embodiment in which a circulation of gas is carried out in the internal volume 50. In this case, the processing module 64 can detect the occurrence of a leak of the cooling fluid out of the internal tube 30 by detecting a modification of the composition of the gas circulating in the internal volume 50.

[0063] According to one embodiment, the system 60 for controlling the coil 20 comprises at least two sensors 65 among the sensors described previously, and the processing module 64 can detect the occurrence of a leak of the cooling fluid from the internal tube 30 by detecting a variation in the physical parameters detected by these sensors 65.

[0064] [Fig. 14] is a block diagram of one embodiment of a method for detecting a failure of the coil of [Fig. 2] and protecting the induction furnace.

[0065] According to one embodiment, the method comprises successive steps 70 and 72.

[0066] In step 70, the processing module 64 detects the occurrence of a leak of the fluid from cooling outside the internal tube 30 and / or a leak from the internal volume 50 to the outside as described previously. According to one embodiment, the implementation of the two detection means makes it possible to determine more precisely the events which have occurred.

[0067] In step 72, the processing module 64 performs at least one operation aimed at protecting the induction furnace. According to one embodiment, when only a leak from the internal volume 50 to the outside is detected, a preventive safety of the cooling circuit can be carried out. According to one embodiment, the processing module 64 controls the generator 61 to stop the flow of current in the external tube 40. According to one embodiment, the processing module 64 controls the device 62 to stop the flow of the cooling fluid in the internal tube 30. Furthermore, the internal tube 30 can be closed, for example by valves, so as to minimize the leakage volume of the cooling fluid, in particular in the case of ruptures of the internal tube 30 and the external tube 40.According to one embodiment, the processing module 64 controls the device 63 to circulate a gas in the internal volume 50 of the coil 20. This advantageously allows the cooling fluid to be evacuated from the internal volume 50 via the gas circulation circuit and reduces the risk of cooling fluid leaking out of the external tube 40. This also advantageously allows degraded cooling of the inductor to be maintained by circulation of the gas which evacuates the calories from the inductor, in particular in the case of an installation having significant thermal inertia. According to one embodiment, the pressure of the gas in the internal volume 50 is greater than the pressure of the cooling fluid in the internal tube 30.In this case, during a local rupture of the inner tube 30, the gas tends to penetrate from the internal volume 50 inside the inner tube 30 through the local rupture, which reduces the risks of leakage of the cooling fluid out of the inner tube 30 through the local rupture. According to one embodiment, a rapid draining device may also be provided to drain the internal volume 50.

[0068] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

[0069] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

Claims

Claims

1. Inductor (20) for an induction furnace (15) comprising a first tube (30), in which a cooling fluid is intended to circulate, and a second tube (40), the first tube being housed in the second tube, an internal volume (50), containing a material from among a liquid, a gas, or a porous solid, or being placed under vacuum, being present between at least a portion of the first tube (30) and the second tube (40).

2. An inductor according to claim 1, wherein the first tube (30) is in contact with the second tube (40).

3. Inductor according to claim 1 or 2, comprising a central part (22) comprising turns (28) and extending at each end by a connection zone (24, 26).

4. Inductor according to claim 3, in which the second tube (40) comprises a wall (43) oriented towards the inside of the turns (28), and in which the first tube (30) is in contact with said wall (43).

5. Inductor according to claim 3 or 4, wherein the first tube (30) successively comprises, in each connection zone (24, 26), a first portion (35) of constant cross-section corresponding to a first cross-section, a second portion (36) of variable cross-section from the first cross-section to a second cross-section, and a third portion (37) of constant cross-section corresponding to the second cross-section, wherein the second tube (40) successively comprises, in each connection zone (24, 26), a fourth portion (45) of constant cross-section corresponding to a third cross-section, a fifth portion (46) of variable cross-section from the third cross-section to a fourth cross-section, and a sixth portion (47) of constant cross-section corresponding to the fourth cross-section.

6. An inductor according to claim 5, wherein the connection between the first and second portions (35, 36) is not in the same plane as the connection between the fourth and fifth portions (45, 46) and wherein the connection between the second and third portions (36, 37) is not in the same plane as the connection between the fifth and sixth portions (46, 47).

7. Induction furnace (15) comprising an inductor (22) according to any one of claims 1 to 6, and comprising a control system (60) of the inductor (20) comprising a first device (62) configured to circulate a coolant in the first tube (30) and a processing module (64) configured to detect a leak of the coolant.

8. An induction furnace according to claim 7, further comprising at least one sensor (65) configured to detect a physical parameter of the internal volume (50) or of the cooling fluid circulating in the first tube (30), and comprising a processing module (64) configured to detect the occurrence of a leak of the cooling fluid out of the first tube (30) by detecting a variation in the physical parameter.

9. An induction furnace according to claim 8, wherein the sensor (65) is selected from the group comprising a sensor for the pressure of the gas in the internal volume (50) of the inductor (20), a sensor for the pressure of the cooling fluid in the first tube (30), a sensor for the flow rate of the cooling fluid in the first tube (30), a sensor for the temperature of the cooling fluid in the first tube (30), a sensor for the temperature of the gas in the internal volume (50) of the inductor, and a sensor for the composition of the gas in the internal volume (50) of the inductor (20).

10. An induction furnace according to any one of claims 7 to 9, further comprising a second device (63) configured to circulate the gas in the internal volume (50) of the inductor (20) upon detection of a leak of the cooling fluid.

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