EP4680907A1

EP4680907A1 - Channel induction furnace

Info

Publication number: EP4680907A1
Application number: EP24711995.1A
Authority: EP
Inventors: Kevin KUCMAN; David C. Smith
Original assignee: Foseco International Ltd
Current assignee: Foseco International Ltd
Priority date: 2023-03-14
Filing date: 2024-03-12
Publication date: 2026-01-21
Also published as: MX2025010855A; WO2024189017A1; AU2024237288A1; CN120813809A

Abstract

The present invention relates to a channel induction furnace, a refractory enclosure to be used in a channel induction furnace, and a process for renewing a lining in a channel induction furnace. The channel induction furnace and the refractory enclosure are asymmetrical: their front side differs from their rear side. The refractory enclosure comprises one or more tubular sections made of a single piece of refractory material produced outside the channel induction furnace.

Description

Channel induction furnace

Field of the invention

[0001] The present invention relates to a channel induction furnace, a refractory enclosure to be used in a channel induction furnace, and a process for renewing a lining in a channel induction furnace. The channel induction furnace is for example suitable for receiving, melting, and discharging cast iron.

Description of prior art

[0002] Channel induction furnaces comprise an internal volume suitable for receiving molten metal and an induction unit connected to the internal volume by a throat. The magnetic field generated by an induction coil of the induction unit heats the molten metal, which circulates between the induction unit and the internal volume.

[0003] The internal volume is laterally surrounded by a lining of refractory material that has to be regularly renewed. The traditional way for renewing the refractory lining is to build it in situ, within the channel induction furnace. This makes it possible to match the shape of the lining with the shape of the channel induction furnace, even when the shape is asymmetrical. A problem of this traditional renewing process is that the channel induction furnace is out of service during the in situ building of the refractory lining.

Summary of the invention

[0004] It is an object of the present invention to decrease the down time due to lining renewal in a channel induction furnace.

[0005] This object is achieved by a refractory lining which is a lateral enclosure made of refractory material and is called refractory enclosure in the present document. The refractory enclosure comprises at least one tubular section forming a wall laterally circumscribing part of the internal volume. Each tubular section is made of a single piece of refractory material produced outside the channel induction furnace and installed, as a piece, inside the channel induction furnace. This production, outside the channel induction furnace, reduces the downtime required to renew the refractory lining: the time to place the refractory lining as a tubular piece is much lower than the time required to build a tubular wall. [0006] The refractory enclosure is asymmetrical: the horizontal cross-sections of its front side and its rear side are different. Moreover, the front side of the refractory enclosure comprises an opening designed to be aligned with a spout of the channel induction furnace. The opening is bored on one of the one or more tubular sections. The asymmetry of the refractory enclosure and the opening on its front side facilitate the discharging of molten metal by tilting the furnace around a horizontal tilting axis. Having the opening already on a tubular section before the tubular section is installed within the channel induction furnace decreases even more the downtime of the channel induction furnace since it simplifies the installation of the spout.

[0007] A channel induction furnace for receiving, melting, and discharging metal, according to the invention comprises:

• an internal volume suitable for receiving molten metal, the internal volume having the shape of a cup;

• an external enclosure surrounding the internal volume;

• a rear side;

• a front side comprising a spout for discharging molten metal;

• a horizontal tilting axis extending through the front side;

• an induction coil located below the internal volume;

• a bottom comprising a refractory floor defining a lower limit of the volume; and

• a refractory enclosure laterally surrounding the internal volume for receiving molten metal, the refractory enclosure comprising a rear side matching the rear side of the channel induction furnace and a front side matching the front side of the channel induction furnace and comprising: o one or more tubular sections, each tubular section forming a wall laterally circumscribing part of the internal volume and being made of a single piece of refractory material produced outside the channel induction furnace, o an opening aligned with the spout, located on the front side of the refractory enclosure, being on one of the one or more tubular sections, and extending between an internal surface and an external surface of the refractory enclosure, wherein the front side of the refractory enclosure has a different shape in a horizontal cross-section than the rear side of the refractory enclosure.

[0008] A refractory enclosure according to the invention comprises:

• one or more tubular sections, each tubular section forming a wall laterally circumscribing part of the internal volume and being made of a single piece of refractory material, and

• an opening on a front side of the refractory enclosure, being on one of the one or more tubular sections, and extending between an internal surface and an external surface of the refractory enclosure; wherein the front side of the refractory enclosure has a different shape in a horizontal cross-section than a rear side of the refractory enclosure.

[0009] The invention may involve any of the following features, isolated, in combination with any other feature, or in combination with any number of other features:

- the front side and the rear side of the refractory enclosure join on a first vertical plane;

- the front side of the refractory enclosure comprises a plurality of vertical portions, each vertical portion being angled with respect to at least one adjacent vertical portion;

- the vertical portions are planar;

- the plurality of vertical portions comprises a first vertical portion and a second vertical portion angled by an angle 2a between 100° and 170°, the first vertical portion being the mirror image in a second vertical plane of the second vertical portion, the opening being located across the second vertical plane;

- on the rear side of the refractory enclosure, the external surface and/ the internal surface fits an arc of a circle;

- the opening is within the circle;

- each tubular section is precast and dried before being placed in the channel induction furnace; - the external enclosure comprises an internal wall made of a refractory material provided in a granular form that is aggregated within the channel induction furnace to become a solid material;

- the refractory enclosure laterally surrounds the refractory floor;

- the refractory enclosure comprises at least two tubular sections staked on each other and blocked horizontally by a system of tongue and groove between a lower surface of the tubular section located at the top and an upper surface of the tubular section located at the bottom;

- the opening has a width of at least 10% of a front-rear extension of the internal volume and a depth of at least 10% of the front-rear extension of the internal volume;

- the refractory enclosure has a thickness, between the internal surface and the external surface, of at least 10% of a front-rear extension of the internal volume;

- the refractory enclosure comprises an upper surface comprising at least three lifting holes; and/or

- each tubular section is made of a single material.

[0010] A process according to the invention, being for renewing a lining in the channel induction furnace, comprises the steps of:

• providing a well having a lateral external wall and a base, an induction coil, and a horizontal tilting axis;

• casting, outside the channel induction furnace, one or more tubular sections, each tubular section being cast as a single piece of refractory material, each tubular section having a front side and a rear side that are different in shape, the front side of one tubular section comprising an opening; and

• placing the one or more tubular sections on top of each other within the well to form a refractory enclosure laterally surrounding the internal volume for receiving molten metal, in such a way that the opening is located on a front side of the refractory enclosure, and extends between an internal surface and an external surface of the refractory enclosure, and in such a way that the rear side of each tubular section matches a rear side of the channel induction furnace, and that the front side of each tubular section matches a front side of the channel induction furnace, the horizontal tilting axis extending through the front side of the channel induction furnace.

[0011] The process according to the invention may involve any of the following steps, isolated, in combination with any other feature and/or step, or in combination with any number of other features and/or steps:

- after placing at least one of the one or more tubular sections, the steps of: o inserting a refractory material in a granular form between the external wall and the tubular section, and o aggregating the refractory material in a granular form to become a solid material forming at least part of an internal wall;

- a step of casting or ramming a refractory floor on the base within the refractory enclosure; and/or

- a subsequent step of adding a spout aligned with the opening.

Brief description of the drawings

[0012] These and further aspects of the invention will be explained in greater detail by way of examples and with reference to the accompanying drawings in which:

Figure 1 is a 3D schematic illustration of a refractory enclosure,

Figure 2 is a schematic top view of a refractory enclosure,

Figure 3 is a schematic rear-front cross-section of a channel induction furnace,

Figure 4 is a schematic top view of a channel induction furnace, and

Figures 5a to 5i are schematic rear-front cross-section of a channel induction furnace during lining renewal.

Detailed description of preferred embodiments [0013] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto. The drawings described are only schematic and are non limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes.

[0014] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. The terms are interchangeable under appropriate circumstances and the embodiments of the invention can operate in other sequences than described or illustrated herein.

[0015] The term “comprising”, used in the claims, should not be interpreted as being restricted to the elements or steps listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising A and B” should not be limited to devices consisting only of components A and B, rather with respect to the present invention, the only enumerated components of the device are A and B, and further the claim should be interpreted as including equivalents of those components.

[0016] Within the frame of the present document, the vertical direction bears reference 1001 , the rear-front direction bears reference 1002, and the right-left direction bears reference 1003. These directions are perpendicular. These directions are considered when the channel induction furnace is not tilted.

[0017] Within the frame of the present document, a “tubular” device is a device surrounding laterally, on 360°, a space, and opening longitudinally on an upper base and lower base. The cross-section of a tubular device may be of any closed shape: circular, polygonal, totally irregular...

[0018] Within the frame of the present document, a “cylindrical” device has a circular cross-section.

[0019] Figures 1 and 2 represent a refractory enclosure 1 to be used in a channel induction furnace 100 (visible on Figure 3 for example). The refractory enclosure 1 may be called “refractory lining” or “working lining”. It is preferably the layer of the channel induction furnace directly in contact with the molten metal. The refractory enclosure 1 is tubular and surrounds, on 360°, an internal volume 4 for receiving molten metal. The refractory enclosure 1 is not cylindrical. The refractory enclosure 1 has preferably a height 14 between 0.5 and 10 meters. The refractory enclosure 1 has an upper surface 50, which is preferably bored with at least three lifting holes 51 for the purpose of attaching a lifting device. The refractory enclosure 1 has an internal surface 11 and an external surface 12. A front-rear extension 5 (visible Figure 3) of the internal volume 4 is measured along the rear-front direction 1002 between two opposite points of the internal surface 11 . The refractory enclosure 1 has a thickness 13, measured between the internal surface 11 and the external surface 12, that is preferably at least 10% of a front-rear extension 5 of the internal volume 4.

[0020] The refractory enclosure 1 comprises one or more tubular sections 10, 20. Each tubular section 10, 20 is a wall laterally circumscribing a horizontal slice of the internal volume 4. Each tubular section 10, 20 is made of a single piece of refractory material, preferably of a single material. Each tubular section 10, 20 may be called “precast” in the sense that is produced, preferably by casting and drying, outside the channel induction furnace, before being placed inside the channel induction furnace. In exemplary embodiments illustrated in some Figures of the present document, the refractory enclosure 1 comprises a first tubular section 10 located at the top of the refractory enclosure 1 , and a second tubular section 20 located at the bottom of the refractory enclosure 1. The first 10 and second 20 tubular sections have identical horizontal cross-sections. The refractory enclosure 1 may comprise only one tubular section 10 or more than two tubular sections within departing from the scope of the present invention.

[0021] The refractory enclosure 1 has a front side 30 and a rear side 40 joining on the left and on the right on a first vertical plane 2, which is perpendicular to the rear-front direction 1002. The refractory enclosure 1 is preferably symmetrical with respect to a second vertical plane 3, which is perpendicular to the right-left direction 1003. The rear side 40 has preferably a semi-circular horizontal cross-section. Preferably, the external surface 12 fits an arc of a circle 90 on 180° along the rear side 40. The front side 30 does not have a semi-circular horizontal cross-section. Preferably, at least part of the external surface 12 along the front side 30 is within the circle 90. [0022] In an embodiment of the invention, the front side 30 comprises a plurality of vertical portions 41 , 42, 43, 44, 45. Each tubular section 10, 20 comprises a part of each vertical portion 41 , 42, 43, 44, 45. Two adjacent vertical portions are angled with respect to each other. The vertical portions 41 , 42, 43, 44, 45 are preferably planar. Amongst the vertical portions 41 , 42, 43, 44, 45, a first vertical portion 41 and a second vertical portion 42 are mirror images in the second vertical plan 3. The first vertical portion 41 and the second vertical portion 42 may, for example, be adjacent or be connected through a third vertical portion 43 parallel to the first vertical plane 2. An angle between any of the first vertical portion 41 and the second vertical portion 42 and the second vertical plan 3 is referred to as a. The first vertical portion 41 and the second vertical portion 42 are preferably angled by an angle, 2a, between 100° and 170°, even if they are not adjacent as illustrated on Figure 2.

[0023] In a variant of said embodiment, the first vertical portion 41 is connected to the front side 30 via a fourth vertical portion 44, and the second vertical portion 42 is connected to the front side 30 via a fifth vertical portion 45. The fourth vertical portion 44 and the fifth vertical portion 45 are preferably parallel to the second vertical plane 3.

[0024] The front side 30 is traversed by an opening 15 extending between the internal surface 11 and the external surface 12. If the refractory enclosure 1 comprises only one tubular section 10, the opening 15 is on this tubular section 10; if the refractory enclosure 1 comprises a plurality of tubular sections 10, 20, the opening 15 is one tubular section of the plurality of tubular sections 10, 20. The opening 15 is on the front of the refractory enclosure 1 , located across the second vertical plane 3. The opening 15 is preferably within the circle 90. The opening 15 is preferably a notch on the upper surface 50, but it may be located at any height of the refractory enclosure. Preferably, one of the lifting holes 51 is in the opening 15. Preferably, the opening 15 has a width 16 of at least 10% of a front-rear extension 5 of the internal volume 4 and/or a depth 17 (visible at Figure 3) of at least 10% of the front-rear extension 5 of the internal volume 4. The opening 15 may be located at a junction between the first vertical portion 41 and the second vertical portion 42 or on the third vertical portion 43.

[0025] Figures 3 and 4 represent a channel induction furnace 100 comprising a refractory enclosure 1 . The channel induction furnace 100 comprises a front side 30F, including the front side 30 of the refractory enclosure 1 ; and a rear side 40F including the rear side 40 of the refractory enclosure 1. The front side 30F of the channel induction furnace 100 has a different shape in a horizontal cross-section than the rear side 40F of the channel induction furnace 100.

[0026] When pouring the metal for discharging it from the internal volume 4, the molten metal flows along a spout 130 aligned with the opening 15. During the discharge, the spout 130 moves down while the rear side 40F move up by a tilting about a horizontal tilting axis 120. The horizontal tilting axis 120 extends through the front side 30F. Part of the spout 130 may be received in the opening 15 of the refractory enclosure 1 (as exemplified in Figure 3) or the spout 130 may be shifted frontwards with respect to the opening 15 (as exemplified in Figure 5i).

[0027] The channel induction furnace 100 comprises an external enclosure 140 laterally surrounding the refractory enclosure 1 . The external enclosure 140 comprises an internal wall 141 in contact with the refractory enclosure 1 and an external wall 142 around the internal wall 141. The internal wall 141 is preferably made of a dry vibratable refractory material, which is a refractory material provided in a granular form and solidified. A new internal wall 141 is created at each renewal of the refractory enclosure 1. The external wall 142 is preferably made of refractory bricks. It may remain or be replaced together with the renewal of the refractory enclosure 1 .

[0028] The channel induction furnace 100 comprises a bottom including a base 160 and a refractory floor 150 located on the base 160. The refractory floor 150 is the lower limit of the internal volume 4. The internal volume 4, delimited by the refractory enclosure 1 and the refractory floor 150, has the shape of a cup. An inductor throat 170 extends vertically through the base 160 and the refractory floor 150. An induction coil 110 is located below the base 160.

[0029] The refractory floor 150 may be surrounded by the refractory enclosure 1 , as illustrated at Figure 3. The bottom of the internal surface of the refractory enclosure 1 may be cut by a groove 21 receiving a protrusion of the refractory floor 150. The first 10 and the second 20 tubular sections may be assembled through a system of tongue and groove 60 between a lower surface of the first tubular section 10 and an upper surface of the second tubular section 20.

[0030] The refractory enclosure 1 preferably comprises a castable material. The castable material has preferably a density between 2000 and 4000 kg/m³, which provides a good trade off to be light enough for the transport as a precast shape, and heavy enough to enclose molten metal. The castable material has preferably an apparent porosity between 5% and 30%. In an embodiment of the invention, the refractory enclosure 1 comprises at least 60% of alumina in weight, preferably at least 10% of silicon carbide in weight, and more preferably at least 0.5% of carbon in weight. An example of a material suitable for the refractory enclosure 1 comprises, in weight:

• between 70 and 80 % AI2O3,

• between 10 and 25 % SiC, and

• between 0.5 and 3.0 % C.

[0031] The spout 130 preferably comprises a material that can be cast, pumped and/or shotcreted. This material has preferably an apparent porosity for a given prefired temperature lower than the apparent porosity of the refractory enclosure 1 material and/or a density lower than the density of the refractory enclosure 1 material. It has preferably an apparent porosity between 5% and 30%. It has preferably a density between 1500 and 3500 kg/m³. In an embodiment of the invention, the spout 130 comprises at least 60% of alumina in weight, and preferably at least 15% of silicon oxide in weight. An example of a material suitable for the spout 130 comprises, in weight:

• between 15 and 30 % SiO2, and

• between 60 and 85 % AI2O3.

[0032] The floor 150 preferably comprises a material that is a dry vibration cement, more preferably of a material able to develop a mullite bond from a threshold temperature. The threshold temperature is preferably between 800°C and 1500°C. It has preferably an apparent porosity between 15% and 25%. It has preferably a density between 2000 and 4000 kg/m³. In an embodiment of the invention, the floor 150 comprises at least 85% of alumina in weight, and preferably at least 3.0% of silicon oxide in weight. An example of a material suitable for the floor 150 comprises, in weight:

• between 0.5 and 10 % SiO2, and between 80 and 99 % AI2O3. [0033] The internal wall 141 preferably comprises a material that is a dry vibration cement, more preferably of a material able to develop a mullite bond from a threshold temperature. The threshold temperature is preferably between 800°C and 1500°C. It has preferably an apparent porosity between 15% and 25%. It has preferably a density between 2000 and 4000 kg/m³. In an embodiment of the invention, the internal wall 141 comprises at least 85% of alumina in weight, and preferably at least 3.0% of silicon oxide in weight. An example of a material suitable for the internal wall 141 comprises, in weight:

• between 0.5 and 10 % SiO2, and

• between 80 and 99 % AI2O3.

[0034] Figures 5a to 5i illustrate possible steps of a process for renewing a lining, which is also called “working lining”, in a channel induction furnace 100. Figure 5a illustrates the situation 150 before the installation of the lining, with the induction coil 110, the horizontal tilting axis 120, the inductor throat 170, the lateral external wall 142 and the base 160. The lateral external wall 142 and the base 160 define a well 200. Outside the channel induction furnace 100 (i.e. outside the well 200), preferably outside the factory where the channel induction furnace 100 is located, the tubular sections 10, 20 are cast. Each tubular section 10, 20 is cast as a single piece of refractory material.

[0035] As illustrated at Figure 5b, the bottom tubular section, on the illustrated embodiment the second tubular section 20, is placed 510 on the base 160 in such a way that it is surrounded by the lateral external wall 142. At Figure 5c, a refractory material in a granular form is inserted 530 between the external wall 142 and the bottom tubular section. Preferably, the granular material is not filled up to the upper surface of the bottom tubular section. At Figure 5d, the refractory material is aggregated 535 to become a solid material forming the bottom part of the internal wall 141. At Figure 5e, the top tubular section, on the illustrated embodiment the first tubular section 10, is then placed 540 on the bottom tubular section. A mortar may be applied between the two stacked tubular sections. At Figure 5f, the refractory material in a granular form is then inserted 550 between the external wall 142 and the top tubular section. At Figure 5g, the refractory material is aggregated 555 to become a solid material forming the top part of the internal wall 141. A sintering of the internal wall 141 may occur once the channel induction furnace 100 is heated in service.

[0036] Figure 5h illustrates a step 560 of creating, for example by casting or ramming, the refractory floor 150 on the base 160. This step 560 is preferably performed after the solidification 535 of at least the bottom part of the internal wall 141 . It may occur for example between step 535 and step 540, or after step 555.

[0037] Figure 5i illustrates a step 570 of adding the spout 130 radially aligned with the opening 15. The spout 130 is preferably cast in place, but it may be precast without departing from the scope of the invention.

[0038] In other words, the invention relates to a channel induction furnace 100, a refractory enclosure 1 to be used in a channel induction furnace 100, and a process for renewing a lining in a channel induction furnace 100. The channel induction furnace 100 and the refractory enclosure 1 are asymmetrical: their front side 30F, 30 differs from their rear side 40F, 40. The refractory enclosure 1 comprises one or more tubular sections 10, 20 made of a single piece of refractory material produced outside the channel induction furnace.

[0039] Although the present invention has been described above with respect to particular embodiments, it will readily be appreciated that other embodiments are also possible.

Claims

1. A channel induction furnace (100) for receiving, melting, and discharging metal and comprising:

• an internal volume (4) suitable for receiving molten metal, the internal volume (4) having the shape of a cup;

• an external enclosure (140) surrounding the internal volume (4);

• a rear side (40F);

• a front side (30F) comprising a spout (130) for discharging molten metal;

• a horizontal tilting axis (120) extending through the front side (30F);

• an induction coil (110) located below the internal volume (4);

• a bottom comprising a refractory floor (150) defining a lower limit of the volume (4); and

• a refractory enclosure (1 ) laterally surrounding the internal volume (4) for receiving molten metal, the refractory enclosure (1) comprising a rear side (40) matching the rear side (40F) of the channel induction furnace (100) and a front side (30) matching the front side (30F) of the channel induction furnace (100) and comprising: o one or more tubular sections (10, 20), each tubular section (10, 20) forming a wall laterally circumscribing part of the internal volume (4) and being made of a single piece of refractory material produced outside the channel induction furnace (100), o an opening (15) aligned with the spout (130), located on the front side (30) of the refractory enclosure (1), being on one of the one or more tubular sections (10, 20), and extending between an internal surface (11) and an external surface (12) of the refractory enclosure (1), wherein the front side (30) of the refractory enclosure (1) has a different shape in a horizontal cross-section than the rear side (40) of the refractory enclosure (1).

2. The channel induction furnace according to claim 1 , wherein the front side (30) and the rear side (40) of the refractory enclosure (1 ) join on a first vertical plane (2).

3. The channel induction furnace according to any of claims 1 and 2, wherein the front side (30) of the refractory enclosure (1) comprises a plurality of vertical portions (41 , 42, 43, 44, 45), each vertical portion being angled with respect to at least one adjacent vertical portion (41 , 42, 43, 44, 45).

4. The channel induction furnace according to any of claims 1 to 3, wherein the vertical portions (41 , 42, 43, 44, 45) are planar.

5. The channel induction furnace according to claim 3, wherein the plurality of vertical portions comprises a first vertical portion (41) and a second vertical portion (42) angled by an angle (2a) between 100° and 170°, the first vertical portion (41) being the mirror image in a second vertical plane (3) of the second vertical portion (42), the opening (15) extending through the second vertical plane (3).

6. The channel induction furnace according to any of claims 1 to 5, wherein on the rear side (40) of the refractory enclosure (1), the external surface (12) fits an arc of a circle (90).

7. The channel induction furnace according to claim 6, wherein the opening (15) is within the circle (90).

8. The channel induction furnace according to any of claims 1 to 7, wherein each tubular section (10, 20) is precast and dried before being placed in the channel induction furnace (100).

9. The channel induction furnace according to any of claims 1 to 8, wherein the external enclosure (140) comprises an internal wall (141 ) made of a refractory material provided in a granular form that is aggregated within the channel induction furnace (100) to become a solid material.

10. The channel induction furnace according to any of claims 1 to 9, wherein the refractory enclosure (1) laterally surrounds the refractory floor (150).

11. The channel induction furnace according to any of claims 1 to 10, wherein the refractory enclosure (1) comprises at least two tubular sections (10, 20) staked on each other and blocked horizontally by a system of tongue and groove (60) between a lower surface of the tubular section (10) located at the top and an upper surface of the tubular section (20) located at the bottom.

12. A refractory enclosure (1 ) to be used in the channel induction furnace (100) of any of claims 1 to 11 , laterally surrounding an internal volume (4) for receiving molten metal, and comprising:

• one or more tubular sections (10, 20), each tubular section (10, 20) forming a wall laterally circumscribing part of the internal volume (4) and being made of a single piece of refractory material, and

• an opening (15) on a front side (30) of the refractory enclosure (1 ), being on one of the one or more tubular sections (10, 20), and extending between an internal surface (11) and an external surface (12) of the refractory enclosure (1); wherein the front side (30) of the refractory enclosure (1) has a different shape in a horizontal cross-section than a rear side (40) of the refractory enclosure (1).

13. The refractory enclosure according to claim 12, wherein the opening (15) has a width (16) of at least 10% of a front-rear extension (5) of the internal volume (4) and a depth (17) of at least 10% of the front-rear extension (5) of the internal volume (4).

14. The refractory enclosure according to any of claims 12 and 13, having a thickness (13), between the internal surface (11) and the external surface (12), of at least 10% of a front-rear extension (5) of the internal volume (4).

15. The refractory enclosure according to any of claims 12 to 14, comprising an upper surface (50) comprising at least three lifting holes (51).

16. The refractory enclosure according to any of claims 12 to 15, wherein each tubular section (10, 20) is made of a single material.

17. A process for renewing a lining in the channel induction furnace (100) of any of claims 1 to 11 , the process comprising the steps of:

• providing (510) a well (200) having a lateral external wall (142) and a base (160), an induction coil (110), and a horizontal tilting axis (120);

• casting, outside the channel induction furnace (100), one or more tubular sections (10, 20), each tubular section (10, 20) being cast as a single piece of refractory material, each tubular section (10, 20) having a front side (30) and a rear side (40) that are different in shape, the front side of one tubular section (10) comprising an opening (15); and

• placing (520, 540) the one or more tubular sections (10, 20) on top of each other within the well (200) to form a refractory enclosure (1) laterally surrounding the internal volume (4) for receiving molten metal, in such a way that the opening (15) is located on a front side (30) of the refractory enclosure (1), and extends between an internal surface (11) and an external surface (12) of the refractory enclosure (1), and in such a way that the rear side (40) of each tubular section (10, 20) matches a rear side (40F) of the channel induction furnace (100), and that the front side (30) of each tubular section (10, 20) matches a front side (30F) of the channel induction furnace (100), the horizontal tilting axis (120) extending through the front side (30F) of the channel induction furnace (100).

18. Process according to claim 17, comprising, after placing (520, 540) at least one of the one or more tubular sections (10, 20), the steps of:

• inserting (530, 550) a refractory material in a granular form between the external wall (142) and the tubular section (10, 20), and

• aggregating (535, 555) the refractory material in a granular form to become a solid material forming at least part of an internal wall (141).

19. Process according to any of claims 17 and 18, comprising a step of casting or ramming (560) a refractory floor (150) on the base (160) within the refractory enclosure (1).

20. Process according to any of claims 17 to 19, comprising a subsequent step of adding (570) a spout (130) aligned with the opening (15).