Device for heating products by cross-current induction

Abstract

The inductor (20) is intended to heat a flat product (1) by cross-current induction, the product having an upper surface (1fs) and a lower surface (1fi), the inductor including a plurality of coils (2as, 2ai, 2bs, 2bi) having a plurality of surfaces (S2as, S2ai, S2bs, S2bi) extending over a plurality of planes (P2as, P2ai, P2bs, P2bi) substantially parallel to one another and a thickness (Eas, Eai, Ebs, Ebi) along a direction perpendicular to these planes, the inductor also including a central region (3) between the plurality of coils intended to receive the product (1). At least two coils (2as, 2ai) are arranged on a first side of the central region (3) and at least two coils (2bs, 2bi) are arranged on a second side of the central region (3) opposite the first side. On the same side of the central region (3), the coils (2ai, 2bi) closest to the surface (1fs, 1fi) of the product are spaced a first distance (Dai, Dbi) from that surface, and the other coils are positioned at a distance from the surface of the product at least equal to the first distance (Dai, Dbi) plus the thickness (Eai, Ebi) of the coils positioned between the other coils and the surface of the product. The surfaces of the coils (P2as, P2ai, P2bs, P2bi) at least partially overlap.

Description

[Technical Field]

[0001] [Specify related technical field] The present invention relates to a device for heating products, in particular flat products such as slabs, thin slabs and strips, by cross-current induction. [Background technology]

[0002] [Technical problem addressed by the invention] An apparatus for heating a product by cross-current induction mainly consists of a power source, an inductor, and elements for electrical connections between these equipment devices.

[0003] Cross-current induction heating makes it possible to efficiently heat products with low magnetic permeability. For example, conventionally, the maximum permeability was approximately 2,500 kW / m. 2 Using high power densities, it is possible to heat carbon steel above its Curie point.

[0004] Nevertheless, this power density may be insufficient to achieve the desired temperature rise over a length limited by dimensional or process constraints.

[0005] In the steel industry, continuous casting allows for the continuous and direct production of flat products from molten metal contained in a ladle. The resulting products can be slabs, typically 35–80 mm thick, thin slabs, typically 5–35 mm thick, or strip, typically less than 5 mm thick. After the metal solidifies and cools rapidly in the ingot mold, induction heating creates the appropriate conditions for rolling, typically at temperatures between 1100°C and 1250°C, to obtain the desired product cross-section and metallurgy. Depending on the production capacity of the continuous caster, the power required to bring the product up to the rolling temperature can be several megawatts. Considering the rolling temperature level and the required power, the heating method is known to be a cross-current induction system. However, known high-flux cross-current inductors allow only a limited power of approximately 1.5 MW. To deliver the required useful power, several inductors are arranged in series. The resulting total length can be large, e.g., 20 m. Steelmakers want to reduce this length as much as possible. Furthermore, the temperature profile of the product at the end of heating is a factor that determines the quality of the rolling. Current transverse flow heaters allow adjustment of this temperature profile to limit overheating of the edges, although only within a limited adjustment range that does not fully meet the needs of steelmakers.

[0006] The present invention provides a solution to these problems by using inductors and heating equipment that have a much higher power density injected into the product, making it possible to obtain better temperature homogeneity for the product and providing a wider adjustment range for the temperature profile of the product. Summary of the Invention

[0007] [DISCLOSURE OF THE INVENTION] According to a first aspect of the present invention, an inductor intended to heat a flat product by cross-current induction is proposed, the product having an upper surface and a lower surface, the inductor comprising a plurality of coils having surfaces substantially parallel to each other and a thickness along a direction perpendicular to these planes, the inductor also comprising a central region between the plurality of coils intended to receive the product, at least two coils are arranged on a first side of the central region and at least two coils are arranged on a second side of the central region opposite the first side, the coil closest to the outer surface of the product being spaced a first distance from said surface on the same side of the central region, the other coil being arranged at a distance from the outer surface of the product at least equal to the first distance plus the thickness of the coil arranged between the other coil and the outer surface of the product, the surfaces of the plurality of coils at least partially overlapping.

[0008] The presence of at least two coils, at least partially overlapping on each side of the product, makes it possible to vary the magnetic field lines generated and to control the temperature rise per unit area in the product.

[0009] The invention is particularly useful for inductors with multiple coils of high magnetic flux, i.e. inductors made of a specific conductor, such as those described by the applicant in patent application FR 2 989 817, which comprises, for example, multiple strands arranged around a tube forming a core through which a cooling fluid passes.

[0010] According to the present invention, multiple coils arranged on the same side of the product are as close as possible to each other, preferably in contact with each other, along a direction perpendicular to the surface on which they extend, thereby limiting parasitic heating and the loss of conductor efficiency that would result from the areas between the multiple coils.

[0011] According to one embodiment of the present invention, the relative positions of the multiple coils with respect to each other can be adjusted so that the central axes of the multiple coils perpendicular to the surface on which the multiple coils extend all coincide, so that the central axes of the multiple coils all differ, or so that some central axes coincide and the remaining central axes differ along a direction parallel to the surface.

[0012] According to one possibility, the relative position of the coils with respect to one another is adjustable based on the width of the product and / or based on the length of the product.

[0013] In accordance with the present invention, multiple coils located on the same side of the heated product can be offset off-center relative to one another, either only along the transverse direction relative to the product, only along the longitudinal direction relative to the product, or both along the longitudinal and transverse directions relative to the product.

[0014] Similarly, the coils on each side of the product can face each other, or they can be offset off-center only transversely to the product, only longitudinally to the product, or both longitudinally and transversely to the product. The offset can relate to only a portion of the coils. For example, in an inductor according to the present invention having two coils on each side of the product, the two coils closest to the product can face each other, while the other two coils can be offset off-center, or vice versa. The opposing coil position is the most efficient position. Offsetting the coils can be implemented to specifically affect the temperature profile of the product, but it can result in a reduction in the efficiency of the installation.

[0015] According to the present invention, the relative positions of the coils in the inductor are also adjustable to change the distance between the substantially parallel surfaces on either side of the product across which the coils extend, i.e., to change the air gap.

[0016] Thus, according to the present invention, it is possible to change the distance between the multiple coils and the product, i.e., to increase or decrease the air gap. Therefore, if it is desired to reduce the power density conducted to the product, it is possible to increase the air gap, for example, to reduce temperature non-uniformities in the product that would result from an excessively high power density. Advantageously, the operation of the multiple coils is performed so that the product is centered between the multiple coils, i.e., so that the distance between the product and the first coil located on each side of the product is substantially the same.

[0017] On the same side of the product, a second coil originating from the product surface is positioned at a distance from the product at least equal to the distance from the first coil multiplied by the thickness of the first coil. According to the present invention, the distance between multiple coils positioned on the same side of the heated product can be varied, thereby moving the second coil away from the first coil to change the power density delivered to the product. In configurations with three or more coils on one side of the product, the positions of the complementary multiple coils can also be adjusted relative to one another to move them away from the product or closer to the product.

[0018] According to a second aspect of the present invention, there is provided a cross-current induction heating installation for a product, comprising at least one inductor according to one of the variants of the above-described embodiment and at least one power supply electrically connected to the inductor.

[0019] Depending on the characteristics of the inductor and the power source, the electrical connection between these two pieces of equipment may include a current step-up or step-down transformer and / or capacitor.

[0020] The facility may include means for making it possible to vary the distance of the coil from the face of the product nearest the coil.

[0021] According to one possibility, the installation may comprise means making it possible to change the relative position of the first coil with respect to the second coil based on the width of the product and / or based on the length of the product.

[0022] According to an alternative embodiment of the present invention, the coils of the inductor located on one side of a central region of the inductor are powered by a first power source of the at least one power supply, and the coils located on the other side of the central region are powered by a second power source of the at least one power supply.

[0023] According to another embodiment of the present invention, the two coils closest to the central region are powered by a first power supply of at least one power supply, and the two coils furthest from the central region are powered by a second power supply of at least one power supply. In cases where the inductor includes five or more coils, the coils disposed between the two coils closest to the central region and the two coils furthest from the central region are powered by one or the other of the two power supplies.

[0024] The multiple power sources may be located on the same side of the product, along a lateral direction relative to the product, or along this lateral direction on each side of the product.

[0025] Thus, in an embodiment of the present invention having two coils on each side of a central region, the two coils closest to the central region, comprising a first coil pair, can be powered by a first power source located on one side of the product, and the two coils furthest from the central region, comprising a second coil pair, can be powered by a second power source located on the other side of the product.

[0026] According to an alternative embodiment of the present invention, the two power sources have different powers, but the maximum flow of power that can be conducted to the product by the two coil pairs will vary.

[0027] According to an alternative embodiment of the present invention, the transverse flow induction heating equipment includes at least two consecutive inductors along the longitudinal direction of the product. Thus, for example, a first inductor is intended to ensure a first increase in the product temperature, and a second inductor is intended to ensure a complementary increase in the product temperature. The two inductors can have the same effect on the product's temperature profile at the inductor's outlet, or can have different, e.g., opposite, effects depending on the relative positions of the coils in the inductor. As a result, for example, the first inductor can have coils operating positions along the transverse direction of the product that result in a sharp increase in temperature at one of the product's two edges, while the second inductor has coils operating positions opposite to the first that result in a sharp increase in temperature at the other edge of the product. Therefore, by adjusting the product's temperature profile after each inductor, it is possible to obtain a desired temperature profile at the outlet of the final inductor. For example, using a solution including two consecutive inductors and a product entering the first inductor with its edges cooler than its center, the first inductor can raise the temperature level at the first edge of the product, and the second inductor can raise the temperature at the second edge of the product so that at the exit of the second inductor the product has reached the desired temperature rise and has a homogeneous temperature profile, or the desired temperature profile.

[0028] According to a third aspect of the present invention, a method for cross-current induction heating of a product is proposed using an installation according to one of the above-described embodiments, characterized in that the relative positions of multiple coils in the inductor are adjusted relative to each other and relative to the product in accordance with a target product temperature profile at the inductor outlet.

[0029] The position of the coils can be adjusted manually by an operator who places the coils and then locks them into their working position. The adjustment can be performed using mechanical means, e.g., a rack or slide movement system. It can also be triggered by electrical, pneumatic, or hydraulic means, e.g., by a jack. The adjustment can also be automated by motorizing the operation.

[0030] The adjustments regarding the position of the multiple coils can be performed by operator action or automatically according to the product characteristics, in particular the product width and / or the desired temperature profile of the product at the outlet of the inductor. [Brief explanation of the drawings]

[0031] Other features and advantages of the present invention will become apparent from the following detailed description, which is to be better understood in conjunction with the accompanying drawings.

[0032] [Figure 1] 1 is a schematic longitudinal cross-sectional view of an inductor in a first operating position according to one embodiment of the present invention; [Figure 2] 2 is a schematic cross-sectional view of the inductor shown in FIG. 1 in the same operating position as in FIG. 1; [Figure 3] FIG. 3 is a schematic top view of the inductor shown in the previous figures in the same operating position as in FIGS. 1 and 2; [Figure 4] FIG. 2 is a schematic top view of the inductor shown in the previous figure in a second operating position. [Figure 5] 5 is a schematic cross-sectional view of the same position as in FIG. 4 and shown in the previous drawing. [Figure 6] FIG. 10 is a schematic top view of the inductor shown in the previous figure in a third position. [Figure 7] FIG. 7 is a schematic longitudinal cross-sectional view of the inductor shown in the previous drawing, taken at the same position as in FIG. 6. [Figure 8] 4 is a schematic longitudinal cross-sectional view of the inductor shown in the previous figure in a fourth position; FIG. [Figure 9] 1A and 1B are schematic longitudinal cross-sectional views of an inductor according to the invention in two embodiments relative to a cylinder head, the upper part of the diagram illustrating a first example and the lower part of the diagram illustrating a second example. [Figure 10] 1 is a typical electronic circuit diagram illustrating a first example of the connection of multiple coils in an inductor according to the present invention. FIG. [Figure 11] FIG. 10 is a typical electronic circuit diagram illustrating a second example of the connection of multiple coils in an inductor according to the present invention. [Figure 12] FIG. 10 is a typical electronic circuit diagram illustrating a third example of the connection of multiple coils in an inductor according to the present invention. [Figure 13] FIG. 10 is a typical electronic circuit diagram illustrating a fourth example of the connection of multiple coils in an inductor according to the present invention. [Figure 14] 1 is a diagram illustrating an example of implementation of the method according to the invention, along with the evolution of the transverse temperature profile of the product at the outlet of four successive inductors according to the invention;

[0033] The embodiments described below are in no way limiting, and it is possible to contemplate variations of the invention that include only a selection of the described features, in particular, if this selection of features confers a technical advantage or is sufficient to distinguish the invention from the prior art, including at least one preferably functional feature without structural details, or including only a portion of structural details, including at least one preferably functional feature, if this portion alone is sufficient to confer a technical advantage or distinguish the invention from the prior art.

[0034] In the remainder of this description, elements having the same or similar structure will be designated by the same reference. DETAILED DESCRIPTION OF THE INVENTION

[0035] [Detailed Description of the Invention] 1 to 8 illustrate the same embodiment of an inductor 20 according to the invention in various possible operating positions, which inductor makes it possible to heat a flat product 1, which defines a longitudinal direction along its length and a transverse direction along its width.

[0036] A cross-current inductor typically consists of multiple coils that generate an electromagnetic field at the origin of heating the product, and multiple cylinder heads intended to improve the efficiency of the inductor by conducting this electromagnetic field. On each side of the product to be heated, the multiple coils and the multiple cylinder heads are fixed on a flat plate. The inductor typically includes a thermal protection that constitutes a barrier against radiation from the product. This thermal protection can also be airtight if the product needs to be placed in an atmosphere other than air, for example, an atmosphere that does not oxidize the product. As a variant, the airtightness can be achieved separately from the thermal protection. To simplify the representation of the invention, only multiple coils are shown in the drawings.

[0037] Figures 1 to 3 illustrate inductor 20 in a first example of an operating position: Figure 1 is a longitudinal cross-sectional view of the inductor, Figure 2 is a transverse cross-sectional view of the inductor, and Figure 3 is a top view of the inductor.

[0038] The inductor 20 includes two pairs of coils 2as, 2ai, 2bs, and 2bi, arranged on either side of a central region 3 in which the product to be heated 1 is located. It can be seen from Figures 1 to 3 that in this example operating position, the four coils are completely overlapped, and their central axes 4as, 4ai, 4bs, and 4bi are aligned in the longitudinal and lateral directions. This configuration is suitable, for example, for cases where the dimensions of the multiple coils allow them to cover the width of the product to be heated when multiple coils are overlapped.

[0039] From the top surface 1fs of the heated product 1, the first coil 2ai is at a distance Dai, i.e., the plane P2ai on which the surface S2ai of the coil 2ai is located is spaced a distance Dai from the top surface 1fs of the product. This distance Dai strongly influences the power density transferred by the coil to the product. To be able to adjust the power transferred to the strip, this distance can be adjusted by the means 21 shown in FIG. 2.

[0040] This means 21 comprises, for example, a worm whose longitudinal axis is perpendicular to the surface 1fs of the product and a nut fixed to the coil with which it cooperates, so that the position of the coil is adjusted by the rotation of the worm. Means 21 can also be a rack, a linear motor, a jack, or any other known means.

[0041] The second coil 2as is positioned at a distance Das from the upper surface 1fs of the product, i.e., the plane P2as on which the surface S2as of the coil 2as is located is spaced a distance Das from the upper surface 1fs of the product. This distance Das is at least equal to the distance Dai at which the first coil is positioned, multiplied by the thickness of the first coil. This distance Das also strongly influences the power density transmitted by the coil to the product. To enable adjustment of the power transmitted to the strip, the distance Das can also be adjusted by a second means 21 shown in FIG. 2.

[0042] From the surface 1fi of the unheated product 1, the first coil 2bi is at a distance Dbi, i.e., the plane P2bi on which the surface S2bi of the coil 2bi is located is spaced a distance Dbi from the bottom surface 1fi of the product. This distance Dbi strongly influences the power density transferred by the coil to the product. To allow for adjustment of the power transferred to the strip, this distance can be adjusted by the means 21 shown in Figure 2.

[0043] The second coil 2bs is positioned at a distance Dbs from the bottom surface 1fi of the product, i.e., the plane P2bs on which the surface S2bs of the coil 2bs is located is spaced a distance Dbs from the bottom surface 1fi of the product. This distance Dbs is at least equal to the distance Dbi at which the first coil is positioned, multiplied by the thickness of the first coil. This distance Dbs also strongly influences the power density transmitted by the coil to the product. To enable adjustment of the power transmitted to the strip, the distance Dbs can be adjusted by a second means 21 shown in FIG. 2.

[0044] Figures 4 and 5 illustrate the inductor 20 in a second operating position, which accommodates a larger product width than the first example operating position. Figure 4 is a top view of the inductor, and Figure 5 is a cross-sectional view of the inductor. The vertical cross-section of the inductor would be the same as Figure 1, and the position of the coils along the vertical direction would be the same for these two example operating positions. In this second operating position, the coils are offset laterally off-center to cover the entire width of the product.

[0045] The longitudinal position of the coil can be adjusted by means 22 shown in Fig. 4. This means 22 comprises, for example, a worm whose longitudinal axis is parallel to the surface 1fs of the product and a nut fixed on the coil with which the worm cooperates. The position of the coil is thus adjusted by rotation of the worm. The means 22 can also be a rack, a linear motor, a jack, or any other known means. In the embodiment of Fig. 4, two coils arranged on the same surface of the product are provided with means 22 for adjusting their lateral position. According to another embodiment of the invention, only one coil is provided with means 22 for adjusting its longitudinal position.

[0046] Figures 6 and 7 illustrate inductor 20 in a third operating position. Figure 6 is a top view of the inductor, and Figure 7 is a longitudinal cross-sectional view of the inductor. The cross-sectional view of the inductor would be the same as Figure 5, and the positions of the coils along the lateral direction would be the same for the second and third operating position examples.

[0047] The longitudinal position of the coils can be adjusted by means 23 shown in Figure 6. This means 23 may be similar to or different from the means for adjusting the transverse position of the coils. In the embodiment of Figure 6, two coils arranged on the same side of the product are provided with means 23 for adjusting the longitudinal position of the two coils. According to another embodiment of the invention, only one coil is provided with means 23 for adjusting its longitudinal position.

[0048] 8 shows inductor 20 in a fourth position in a longitudinal cross section. This example illustrates an operating position in which there is asymmetry between the coils relative to the heated product. Thus, coil 2as is not opposite coil 2bs. Any other variations in asymmetry are possible according to the invention.

[0049] The coil is advantageously made by an assembly of conductors. Each conductor comprises a number of strands of an electrically conductive material, for example copper, arranged around a tube of electrically insulating material that forms a core through which the cooling fluid passes. The strands are impregnated with an electrically insulating paste with good thermal conductivity to ensure good heat conduction between the strands and the tube. The coil is made by an assembly of conductors, for example, arranged side by side in the same plane of the coil. At each end, the conductors are electrically connected to one another by connecting elements to a power source. Likewise, at each end, the tubes of insulating material open into a cavity that forms a manifold for supplying or discharging the cooling fluid, depending on the end.

[0050] Advantageously, the coil comprises two assemblies, superimposed and juxtaposed as described above, i.e. two layers of conductors lying in two parallel planes. In an alternative embodiment, the elements for connecting to a power supply and / or the points for connecting to a cooling fluid are common to the two layers of conductors.

[0051] To simplify the drawings illustrating the coils, the electrical or hydraulic connections to the coils are not shown.

[0052] According to an alternative embodiment of the present invention, an inductor includes at least one cylinder head on each side of the product. The cylinder head is made of laminated silicon steel sheets separated by electrical insulators. This lamination allows the cylinder head to conduct the electromagnetic field generated by the coils while preventing current from flowing through the cylinder head. FIG. 9 illustrates two embodiments of a cylinder head 5 in a longitudinal cross-section at the mid-width of the product 1, keeping in mind that in an actual inductor, the cylinder heads are identical on both sides of the inductor. In the upper part of the drawing, the cylinder head has a central extension located inside the coils. This is not present in the embodiment variant shown in the lower part of the drawing. The efficiency of the cylinder head is greater when it includes a central extension, but this limits the lateral movement possible for the coils. Conversely, an inductor with a cylinder head without a central extension will have lower efficiency, but it allows for a wider adjustment range for the relative positions of the coils.

[0053] 10 to 13 are simplified electronic circuit diagrams illustrating, by way of non-limiting example, various variations for connecting an inductor with two pairs of coils according to the present invention.

[0054] 10 illustrates a vertical / parallel arrangement in which a power supply 6 feeds four coils in an inductor, with two coils 2as, 2ai located on the same side of the product connected in parallel, and the other two coils 2bs, 2bi located on the opposite side of the product also connected in parallel, with the two pairs of coils connected in series. The circuit includes a capacitor 7 arranged in series.

[0055] Figure 11 illustrates a series arrangement in which an inductor is powered by two power sources 6. One power source 6 powers the pair of coils 2as, 2bs furthest from the product, which are connected in series. The second power source 6 powers the pair of coils 2ai, 2bi closest to the product, which are also connected in series. Each circuit includes a capacitor 7 arranged in series.

[0056] 12 also illustrates a configuration with two power supplies 6, but with the coils connected in parallel. Thus, one power supply 6 powers the pair of coils 2as, 2as furthest from the product, which are connected in parallel, and a second power supply 6 powers the pair of coils 2ai, 2bi closest to the product, which are also connected in parallel. Again, each circuit includes a capacitor 7 arranged in series.

[0057] In the variations shown in Figures 11 and 12, two power sources 6 can be located on the same side of the product, or one power source can be located on each side of the product.

[0058] Figure 13 illustrates a configuration closest to that shown in Figure 12, in which the inductors are powered by a dual-output power supply 6. One output of the power supply 6 powers the pair of coils 2as, 2bs furthest from the product, which are connected in series. The second output of the power supply 6 powers the pair of coils 2ai, 2bi closest to the product, which are also connected in series. Again, each circuit includes a capacitor 7 arranged in series.

[0059] According to an example of the invention applied to the production of thin steel slabs by continuous casting, four successive stations allow the product temperature to be raised from 900°C to 1000°C. Each station is equipped with a power supply connected to an inductor having two coils located on each side of the product. The coils are electrically connected according to the schematic diagram in Figure 10. They are powered by a current of up to 4000 A at a voltage of 2500 V and a frequency of 1000 Hz. The relative positions of the coils in the four stations are adjusted to obtain a 1000°C product at the output with the desired transverse temperature profile.

[0060] FIG. 14 shows a diagram of the cross-sectional temperature variation of a product, illustrating an embodiment of the method according to the present invention, for this example applied to the reheating of a thin slab. The y-axis of this diagram represents the temperature of the product, and the x-axis represents the width of the product. Curve A represents the cross-sectional temperature profile of the product at the inlet of the first inductor, where the edges of the product are significantly cooler than the center. Curve B represents the temperature profile of the product at the outlet of the first inductor. The relative positions of the coils in the first inductor correspond to promote strong heating of the edge of the product located on the left side of the diagram. Curve C represents the temperature profile of the product at the outlet of the second inductor. The relative positions of the coils in the second inductor correspond to promote greater heating of the edge of the product located on the right side of the diagram. Curve D represents the temperature profile of the product at the outlet of the third inductor. The relative positions of the coils in the third inductor correspond to promote slightly greater heating of the edge located on the left side of the diagram. Curve E represents the temperature profile of the product at the outlet of the fourth and final inductor. The relative positions of the coils in the final inductor correspond to promote slightly greater heating towards the right-hand edge of the diagram in order to obtain a homogeneous temperature profile in the product.

Claims

1. An inductor (20) intended to heat a flat product (1) by cross-current induction, comprising: said product having an upper surface (1fs) and a lower surface (1fi), The inductor includes a plurality of plate-shaped coils (2as, 2ai, 2bs, 2bi) having a plurality of surfaces (S2as, S2ai, S2bs, S2bi) extending across a plurality of planes (P2as, P2ai, P2bs, P2bi) that are substantially parallel to one another, and a thickness (Eas, Eai, Ebs, Ebi) along a direction perpendicular to the planes, The inductor also includes a central area (3) between the coils intended to receive the product (1), At least two coils (2as, 2ai) are arranged on a first side of said central region (3), At least two coils (2bs, 2bi) are arranged on a second side of the central region (3) opposite to the first side, the coils (2ai, 2bi) closest to the product on the same side of the central region (3) are spaced a first distance (Dai) from the product, and the other coils are positioned at a distance from the product at least equal to the first distance (Dai, Dbi) plus the thickness (Eai, Ebi) of the coils positioned between the other coils and the product; the surfaces (S2as, S2ai, S2bs, S2bi) of the coils at least partially overlap; It is characterized by Each of the plurality of plate-shaped coils (2as, 2ai, 2bs, 2bi) has a central axis (4as, 4ai, 4bs, 4bi) perpendicular to the plurality of planes (P2as, P2ai, P2bs, P2bi), The relative positions of the coils with respect to each other are adjustable along a direction parallel to the planes (P2as, P2ai, P2bs, P2bi) in all three ways: (i) so that the central axes (4as, 4ai, 4bs, 4bi) of the coils all coincide, (ii) so that the central axes of the coils all differ, and (iii) so that some coincide and the rest differ; The inductor further characterized by:

2. The inductor of claim 1 , wherein the relative positions of the coils with respect to one another are adjustable based on the width of the product and / or based on the length of the product.

3. 2. An inductor according to claim 1, characterized in that the relative positions of the coils with respect to each other are adjustable so as to change the distance between two substantially parallel surfaces (S2as, S2ai, S2bs, S2bi) on which the coils extend.

4. 4. The inductor of claim 3, wherein the relative positions of the coils are adjustable to change the distance of the coils from the product nearest the coils.

5. At least one inductor (20) according to any one of claims 1 to 4; at least one power source (10) electrically connected to the inductor; 1. An installation for cross-current induction heating of a product (1), comprising:

6. 6. An installation for transverse current induction heating of products (1) according to claim 5, characterized in that it comprises means (21) by which the distance of the coil from the product nearest to the coil can be varied.

7. 6. An installation for transverse current induction heating of a product (1) according to claim 5, characterized in that it comprises means (22, 23) capable of changing the relative position of the first of the two coils with respect to the second of the two coils depending on the width and / or length of the product.

8. 6. The installation for transverse current induction heating of a product (1) according to claim 5, characterized in that the coils (2as, 2ai, 2bs, 2bi) of the inductor (20) arranged on one side of the central region (3) of the inductor are powered by a first power source (10) of the at least one power source (10), and the coils arranged on the other side of the central region (3) are powered by a second power source (10) of the at least one power source.

9. 6. An installation for transverse current induction heating of a product (1) according to claim 5, characterized in that the coils (2ai, 2bi) closest to the central region are powered by a first power source (10) of the at least one power source (10), and the coils (2as, 2bs) furthest from the product are powered by a second power source (10) of the at least one power source (10).

10. 10. An installation for transverse current induction heating of a product (1) according to any one of claims 5 to 9, characterized in that it comprises at least two inductors (20) successively arranged along the longitudinal direction of the product.

11. 11. A method for cross-current induction heating of a product (1) by means of an installation according to any one of claims 5 to 10, comprising:

10. A method according to claim 9, wherein the relative positions of the coils (2as, 2ai, 2bs, 2bi) in the inductor (20) with respect to each other and to the product are adjusted according to a desired temperature profile of the product at the outlet of the inductor.

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