Electrode support for glassmaking furnace

Abstract

The present invention relates to a support (8) for a molten electrode (1) settling from the surface of a molten bath, wherein the support (8) comprises a power supply system and a first cooling device (20) having an inner pipe (12) and an outer pipe (11) linked together for the circulation of a coolant, the outer pipe of the first cooling device being surrounded by an electrical circuit breaker, the electrical circuit breaker being surrounded by a second cooling device (22) having an inner pipe (17) and an outer pipe (16) linked together for the circulation of a coolant. The present invention is characterized in that at least the outer pipe of the second cooling device is substantially parallelepiped, or has a cross-section that is parallelepiped.

Description

Technical Field

[0001] The present invention relates to a glass melting furnace.

Background Art

[0002] The present invention relates to an apparatus for melting glassifiable materials, particularly an apparatus used for producing flat glass, hollow glass, or insulating fibers, which will hereinafter be referred to as a glass melting furnace.

[0003] Such a furnace consists of a tank on which an upper structure is placed. The tank is a region for melting raw materials. The upper structure is arranged on the tank and forms a sealed region. Therefore, this upper structure has a side wall portion and a crown portion that closes the furnace from above.

[0004] This furnace has heating means for raising the raw materials to the melting temperature. These heating means are in the form of, for example, electrodes, and energy is dissipated from the so-called immersion electrodes into the melt through them by the Joule effect.

[0005] These heating means have electrodes attached to a support having a power supply system and an electrode cooling device. The cooling device consists of two pipes associated with each other to circulate a coolant. This is a network of pipes (known as a "water jacket") adapted to the circulation of the cooling fluid. The outer pipe of this cooling device is surrounded by a jacket of a blocking material (insulating material). This jacket is further surrounded by a second water jacket type device having two concentric pipes associated with each other to circulate a coolant.

[0006] In this known system, the pipes of the two water jacket type cooling devices are circular.

[0007] This configuration makes it possible to create electrode arms for small or medium-sized furnaces, i.e., arms of 2m or less.

[0008] However, current trends indicate the need for large furnaces capable of producing large quantities of glass. These large furnaces, however, require specialized heating systems. Therefore, in the case of Joule heating using electrodes, they need to have longer arms than existing ones. This relatively large length creates mechanical stress on the arms. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The object of the present invention is to provide a glassmaking furnace that provides an arm configuration that allows for an increase in their length for use in a large furnace. [Means for solving the problem]

[0010] For this purpose, the present invention relates to a support for a molten electrode settling from the surface of a molten bath, wherein the support comprises a current supply system and a first cooling device having inner and outer pipes linked together for the circulation of a coolant, the outer pipe of the first cooling device being surrounded by an electrical circuit breaker (electrical insulator), the electrical circuit breaker being surrounded by a second cooling device having inner and outer pipes linked together for the circulation of a coolant, and the support is characterized in that at least the outer pipe of the second cooling device has a substantially parallelepiped cross-section, or a cross-section that is parallelepiped.

[0011] For example, the cross-section of the inner pipe of the second cooling device is substantially parallelepiped, or parallelepiped.

[0012] For example, the cross-section of the outer pipe of the first cooling device is substantially parallelepiped, or parallelepiped.

[0013] For example, the cross-section of the inner pipe of the first cooling device is substantially parallelepiped, or parallelepiped.

[0014] For example, the cross-section of a parallelepiped is square.

[0015] For example, the cross-section of a pipe that is not parallelepiped is circular, or substantially circular.

[0016] In one example, the outer pipe of the first cooling device is conductive and forms a current supply system.

[0017] For example, the support has a horizontal extension of more than 2000 mm, preferably more than 2500 mm, more preferably more than 3000 mm, more preferably more than 3500 mm, more preferably more than 3700 mm, and more preferably more than 3900 mm.

[0018] Other features and advantages are given in an illustrative and non-limiting manner with reference to the attached drawings and will become apparent from the description below. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 shows a diagram of the furnace. [Figure 2] Figure 2 shows a cross-sectional view of the electrode support. [Figure 3] Figure 3 schematically shows a cross-sectional view of a modified example of the support according to the present invention. [Figure 4] Figure 4 is a cross-sectional view of the electrode support showing the area difference between a square cross-section and a circular cross-section. [Figure 5] Figure 5 schematically shows a cross-sectional view of a modified example of the support according to the present invention. [Figure 6] Figure 6 schematically shows a cross-sectional view of a modified example of the support according to the present invention. [Figure 7] Figure 7 schematically shows a cross-sectional view of a modified example of the support according to the present invention.

Mode for Carrying Out the Invention

[0020] The figure shown in FIG. 1 shows a part of a melting furnace having an immersion electrode 1. The furnace consists of a refractory tank having a bottom 2 and side wall portions 3. Above the tank, a refractory top 4 is suspended from a metal frame 5, which is only partially shown, and the metal frame 5 straddles the furnace. A movable refractory wall portion 6 is provided, which, when in the lowered position, i.e., when placed on the side wall portion 3, partially isolates the molten bath 7 from the surrounding atmosphere.

[0021] Only the opening in the wall portion 6 is provided for passing the electrode holder 8.

[0022] This lowered position of the wall portion 6 is applied when the furnace is in the standby mode and there is no need to supply raw materials. This avoids excessive heat loss and the risk of damaging all peripheral equipment.

[0023] The electrode 1 is immersed within the surface of the molten bath 7 below the layer 9 of the raw material to be melted. This layer 9 covers the molten bath 7 during normal operation, thermally insulating the tank and preventing heat loss.

[0024] The electrode 1 is attached to a support 8, which has a power supply system and a cooling device 20 for the electrode 1, and these are not shown in this FIG. 1. A single-phase, three-phase or two-phase current is supplied to the electrode 1.

[0025] The support 8 itself is connected to a mechanism (not shown) that enables the electrode 1 to be removed from the bath, for example for replacement or repair.

[0026] In Figure 2, electrode 1, made of molybdenum for example, is attached to pipe 11 via current-conducting element 10, which forms part of a current-conducting cooling device. Element 10 is an extension that screws onto pipe 11. Electrode 1 is attached to the other end of this extension 10. This design facilitates the disassembly of the extension 10 / electrode 1 assembly because the screw-in area is not immersed in the molten bath. In fact, if pipe 11 were relatively long and directly immersed in the bath, it would be possible to attach electrode 1 directly to it, for example, by screwing it in. On the other hand, removing the electrode would be much more difficult because the attachment point is immersed in the molten bath.

[0027] In this assembly, replacement is very easy, but it requires that the extension 10 be replaced at the same time as the electrode 1. The extension 10 may be covered at least partially with a refractory material of sufficient thickness to prevent direct contact with the raw material or molten bath.

[0028] The extension 10 also allows the coolant to reach the electrodes and cool them.

[0029] Screw-in mounting is advantageous in that it allows for quick replacement. Electrode replacement can occur frequently not only due to wear and damage, but also because changing the electrodes, particularly in terms of length, alters the immersion level and thus changes the amount of energy input to the furnace. Pipe 11 may be made of metal for good rigidity and conductivity. This metal may be steel, or any other alloy or metal.

[0030] A second pipe 12 exists within the first pipe 11, and this second pipe 12 is, for example, concentric with the outer wall of pipe 11. This second pipe 12 is attached to the inner surface of the first pipe 11 at multiple locations.

[0031] The combination of these two pipes 11 and 12 allows water to circulate, thus forming a first water jacket type cooling device between the inner wall of 11 and the outer wall of 12. Since the cooling system is designed to cool the electrode 1, the second pipe 12 passes through the extension 10. Thus, it is understood that the first cooling device 20 has an inner pipe 12 and an outer pipe 11.

[0032] At the other end of the first pipe 11, a supply collar 13, made of, for example, copper, is attached to the circuit breaker casing 14 (insulating casing 14). This collar 13 enables the first pipe 11 to be guided to a predetermined voltage, and the latter, being an electrical conductor, supplies this same voltage to the electrode 1.

[0033] An electrical shielding material 15 (electrical insulating material 15) is placed around the first pipe 11, which is advantageously made of a fire-resistant material of the type commercially available as MURATHEM500M. The material 15 is in the form of one or more sleeves, which surround and rest on a portion of the outer surface of the first pipe 11. This electrical shielding material allows workers approaching the molten bath to access electrode supports without any risk of electric shock. The material 15 itself is surrounded by a concentric envelope 16 through which a coolant, such as water, circulates. This "water jacket" type envelope 16 includes an inner sleeve 17, which allows for the circulation of the coolant, forming a second cooling device 22. Thus, it is understood that the second cooling device 22 has an inner pipe 17 and an outer pipe 16.

[0034] This second cooling device has two pipes and prevents the insulating material from overheating, even if it is selected to withstand fairly high temperatures and has already been partially cooled by the first cooling device.

[0035] On the other hand, the outer surface of the electrode support 8 is kept at a relatively low temperature and can be touched, or at least approached, by an operator, even when the furnace is idle and the support 8 is essentially heated by radiation from the molten bath where the raw material layer 9 does not exist.

[0036] Various elements 11, 12, 15, 16, and 17 constitute a hollow pipe. It is understood that elements 11 and 16 are the outer pipe, and elements 12 and 17 are the inner pipe.

[0037] According to the present invention, the pipes of the first water jacket type cooling device 20 and the pipes of the second water jacket type cooling device 22 have specific shapes and cross-sections. It is understood that the described shapes may sometimes have one or more variations.

[0038] In one embodiment, the two pipes 11 and 12 of the first cooling device are circular or substantially circular. In this first embodiment, as can be seen in Figure 3, the envelope 17 of the second cooling device is circular or substantially circular, while the sleeve 16 is substantially parallelepiped or parallelepiped. Preferably, this parallelepiped shape is square.

[0039] The difference in shape between the two pipes 16 and 17 of the second cooling device provides a mechanical advantage in terms of generating a large arm. This is because the space between the two pipes 16 and 17 is the space through which the coolant circulates. As it circulates, this coolant brings its mass to the entire electrode-type heating system. However, with respect to an arm of a certain size, this mass causes mechanical stress. The objective is to achieve a balance between cooling performance and overall weight.

[0040] As can be seen in Figure 4, the difference in the shapes of the two pipes results in a space with a relatively large surface area for the same overall dimensions. This relatively large surface area improves cooling by improving coolant circulation.

[0041] As can be seen from Figure 4, examples of configurations include the first case shown in A, which has a parallelepiped outer pipe 16, and the second case shown in B, which has a circular outer pipe 16. Example C shows the difference in surface area between Example A and Example B. It can be seen that when the overall dimensions are the same, i.e., the distance between the central axis and the surface of the outer pipe 16 is the same, Example A provides a relatively large cooling cross-sectional area. In fact, a 10cm square has a 100cm cross-sectional area 2 This results in a surface area of ​​78.5 cm² for a circle with a diameter of 10 cm. 2 A large surface area is obtained. This relatively large surface area allows a relatively large amount of coolant to pass through. On the other hand, it is also possible to reduce the size of the pipe for the same amount of coolant. This reduction in pipe size reduces the weight of the support 8 and therefore improves its mechanical strength.

[0042] In the modified example shown in Figure 5, the envelope 16 of the second cooling device is also substantially parallelepiped, or parallelepiped, preferably square. Therefore, the two pipes of the second cooling device are parallelepiped, preferably square.

[0043] In another variation, the envelope 16 and / or sleeve 17 have a rectangular shape.

[0044] In the modified version shown in Figure 6, the pipe 11 also has a parallelepiped shape, preferably a square. This means that the envelope 16 and sleeve 17 have a substantially parallelepiped shape, or a parallelepiped shape, preferably a square. This modification does not prevent the use of circular pipes 16 and 17, but the overall dimensions and weight are relatively larger.

[0045] In the modified form shown in Figure 7, pipe 12 also has a substantially parallelepiped shape, or a parallelepiped shape, preferably a square shape. This means that pipe 11, envelope 16, and sleeve 17 have a parallelepiped shape, preferably a square shape. Having all pipes in a square shape means a relatively large surface area for the same footprint. Therefore, compared to a circular shape, pipes 11, 12, 16, and 17 of the present invention provide relatively good cooling. However, at the same time, this means a relatively small footprint for the same coolant flow rate.

[0046] The inlet and outlet lines for the various coolants are not shown in the diagram.

[0047] The coolant used for cooling is preferably demineralized water, which means that the same circuit can be used for both cooling systems without any risk of current conduction to the external cooling system, which is also grounded.

[0048] The electrodes and their supports described herein can be used without hazard in normal operating modes since the accessible equipment is not energized, and can also be used without risk of damage to the supports when the furnace is in standby mode.

[0049] Accordingly, the apparatus having electrodes and their supports, as described in the present invention, retains various advantages associated with electromelting using electrodes settled within the surface of a molten bath. These include good heat yield, good quality of molten material unaffected by drawout changes, a relatively long furnace service life due to relatively little damage to refractories, and easy electrode replacement.

[0050] Furthermore, the apparatus according to the present invention makes it possible to avoid the need for a protective system that prevents the electrodes from being completely immersed during the standby period or to prevent workers from approaching the area around an element that is continuously supplied with energy.

[0051] Alternatively, pipe 11 is not an electrical conductor. The electrical conductor is provided by a dedicated conduit or rod. In the case of a conduit, it may be arranged to surround pipe 11. In this way, the barrier material 15 surrounds and is in contact with the conductive conduit. In this case, pipe 11 is a casing made of, for example, steel, while the conduit dedicated to electrical conduction is made of a conductive material, such as copper.

[0052] In the case of conduction via a rod, the rod is ideally placed inside the pipe 12. This arrangement requires the pipe 12, and consequently the pipe 11, envelope 16, and sleeve 17, to have relatively large diameters, thereby compensating for the presence of the rod. The material used for the rod is a conductive copper-type material.

[0053] According to the present invention, the support 8 is similar to an arm having a horizontal projection. This projection has a horizontal extension of more than 2000 mm, preferably more than 2500 mm, more preferably more than 3000 mm, more preferably more than 3500 mm, more preferably more than 3700 mm, and more preferably more than 3900 mm.

[0054] Naturally, the present invention is not limited to the examples shown, and various modifications and alterations that would be obvious to those skilled in the art are readily possible.

Claims

1. A support (8) for a molten electrode (1) settling from the surface of a molten bath, wherein the support (8) comprises a power supply system and a first cooling device (20), the first cooling device (20) comprises an inner pipe (12) and an outer pipe (11) linked to each other for the circulation of a coolant, the outer pipe of the first cooling device is surrounded by an electrical circuit breaker, the electrical circuit breaker is surrounded by a second cooling device (22), the second cooling device (22) comprises an inner pipe (17) and an outer pipe (16) linked to each other for the circulation of a coolant, and at least the outer pipe of the second cooling device is substantially parallelepiped, or has a cross-section that is parallelepiped.

2. Furthermore, the support according to claim 1, wherein the cross-section of the inner pipe of the second cooling device is substantially parallelepiped or parallelepiped.

3. Furthermore, the support according to claim 1 or 2, wherein the cross-section of the outer pipe of the first cooling device is substantially parallelepiped or parallelepiped.

4. Furthermore, the support according to any one of claims 1 to 3, wherein the cross-section of the inner pipe of the first cooling device is substantially parallelepiped or parallelepiped.

5. The support according to any one of claims 1 to 4, wherein the cross-section of the parallelepiped is square.

6. The support according to any one of claims 1 to 4, wherein the cross-section of the pipe having a cross-section that is not parallelepiped is circular or substantially circular.

7. The support according to any one of claims 1 to 6, wherein the outer pipe of the first cooling device is conductive and forms a current supply system.

8. A support according to any one of claims 1 to 7, having a horizontal extension of more than 2000 mm, preferably more than 2500 mm, more preferably more than 3000 mm, more preferably more than 3500 mm, more preferably more than 3700 mm, and more preferably more than 3900 mm.

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