Electrode support for a glass manufacturing furnace

Abstract

The invention relates to a support (8) for a consumable electrode (1) immersed from the surface of a melt bath. The support (8) has a power supply system and a first cooling device (20) comprising an inner duct (12) and an outer duct (11) associated with each other for circulating a cooling liquid. The outer duct of the first cooling device is surrounded by an electrical insulator, which is surrounded by a second cooling device (22). The second cooling device (22) comprises an inner duct (17) and an outer duct (16) associated with each other for circulating a cooling liquid. The invention is characterized in that at least the outer duct of the second cooling device has a substantially parallelepiped or parallelepiped cross-section.

Description

Technical Field

[0001] This invention relates to a glass manufacturing furnace. Background Technology

[0002] This invention relates to an apparatus for melting vitrifiable materials, particularly an apparatus for producing flat glass, hollow glass or insulating fibers, hereinafter referred to as a glass manufacturing furnace.

[0003] This furnace consists of a vessel with an upper structure mounted on top. The vessel is the area where raw materials are melted. The upper structure is placed on the vessel to form an enclosed area. Therefore, the upper structure includes side walls and a crown that encloses the furnace from above.

[0004] The furnace includes heating elements for heating the raw materials to their melting temperature. These heating elements take the form of electrodes, for example, through which energy is dissipated from the so-called submerged electrodes into the melt via the Joule effect.

[0005] These heating elements include electrodes attached to a support, which includes a power supply system and an electrode cooling device. The cooling device consists of two interconnected pipes for the circulation of coolant. This is a network of pipes (called a "water jacket") suitable for circulating the cooling liquid. The outer pipes of the cooling device are surrounded by a jacket of insulating material. This jacket is in turn surrounded by a second water-jacket type device, which has two interconnected concentric pipes for the circulation of the cooling liquid.

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

[0007] This configuration makes it possible to manufacture electrode arms for small or medium-sized furnaces, i.e., the arm length does not exceed 2 meters.

[0008] However, current trends indicate a need for large furnaces capable of mass glass production. These large furnaces, however, require specialized heating systems. Therefore, when using electrodes for Joule heating, longer arms than existing ones are needed. This increased length leads to mechanical stress on the arms. Summary of the Invention

[0009] The object of the present invention is to provide a glass manufacturing furnace that provides an arm configuration that allows for increased arm length for use in large furnaces.

[0010] Therefore, the present invention relates to a support for a molten electrode immersed in a molten bath, the support having a power supply system, a first cooling device including interconnected inner and outer pipes for circulating cooling liquid, the outer pipe of the first cooling device being surrounded by an electrical insulator, the electrical insulator being surrounded by a second cooling device including interconnected inner and outer pipes for circulating cooling liquid, characterized in that at least the outer pipe of the second cooling device has a generally parallelepiped or parallelepiped cross-section.

[0011] According to one example, the cross-section of the inner pipe of the second cooling device is approximately parallelepiped or parallelepiped.

[0012] According to one example, the cross-section of the outer pipe of the first cooling device is approximately parallelepiped or parallelepiped.

[0013] According to one example, the cross-section of the inner pipe of the first cooling device is approximately parallelepiped or parallelepiped.

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

[0015] As an example, the cross-section of a non-parallelogrammian tube is circular or approximately circular.

[0016] In one example, the external pipes of the first cooling device are conductive and form an electric current supply system.

[0017] According to one example, the support has a horizontal span of more than 2,000 mm, preferably more than 2,500 mm, more preferably more than 3,000 mm, more preferably more than 3,500 mm, more preferably more than 3,700 mm, and more preferably more than 3,900 mm. Attached Figure Description

[0018] Referring to the accompanying drawings, other specific features and advantages will become apparent from the following description, given in an illustrative and entirely non-limiting manner, wherein: - Figure 1 A view of the furnace is shown; - Figure 2 The cross-section of the electrode support is shown; - Figure 3 , 5 Figures 6 and 7 schematically show cross-sectional views of a variation of the support according to the invention; - Figure 4 The cross-section of the electrode support is shown, where there is a difference in area between the square cross-section and the circular cross-section. Detailed Implementation

[0019] Figure 1 The diagram shows a portion of a furnace with an immersion electrode 1. The furnace consists of a refractory basin having a bottom 2 and side walls 3. Above the basin, a refractory roof 4 is suspended from a metal frame 5 (partially shown) spanning the furnace. A movable refractory wall 6 is provided, which, when in a lowered position (i.e., against the side walls 3), partially isolates the molten bath 7 from the surrounding atmosphere.

[0020] The opening in wall 6 is only provided for the electrode holder 8 to pass through.

[0021] When the furnace is in standby mode and no longer needs to be supplied with raw materials, furnace wall 6 is positioned at this low position. This avoids excessive heat loss and the risk of damaging all surrounding equipment.

[0022] Electrode 1 is immersed in the surface of the molten bath 7, below the raw material layer 9 to be melted. This raw material layer 9 covers the molten bath 7, the thermal insulator, and prevents heat loss during normal operation.

[0023] Electrode 1 is attached to support member 8, which includes a power supply system and a cooling device 20 for electrode 1. Figure 1 Not shown in the image. Electrode 1 is supplied with single-phase, three-phase, or two-phase current.

[0024] The support 8 itself is connected to a mechanism (not shown) that allows the electrode 1 to be removed from the bath, for example, for replacement or repair.

[0025] exist Figure 2 In this assembly, electrode 1 (e.g., made of molybdenum) is connected to pipe 11 via conductive element 10, which forms part of a conductive cooling device. Element 10 is an extension threaded onto pipe 11. Electrode 1 is attached to the other end of extension 10. This design facilitates easy disassembly of the extension 10 / electrode 1 assembly because the screw-in area is never immersed in the molten bath. In fact, if pipe 11 were longer and directly immersed in the pool, electrode 1 could be directly attached to pipe 11, for example, via a threaded connection. On the other hand, removing the electrode would be more difficult because the attachment point would be immersed in the molten bath. In our assembly, replacement is very easy, but extension 10 still needs to be replaced simultaneously with electrode 1. Extension 10 can be at least partially surrounded by a sufficiently thick refractory material to prevent direct contact with raw materials or the molten bath.

[0026] Extension 10 also allows coolant to pass through the electrode to cool it.

[0027] Screw-in attachments are attractive because they allow for quick replacement. Electrode replacements can occur frequently, not only due to wear but also because the electrodes can be altered, especially in length, thus changing the degree of immersion and consequently the energy input to the furnace. The conduit 11 can be made of metal for good rigidity and conductivity. This metal can be steel or any other possible alloy or metal.

[0028] Within the first conduit 11 is a second conduit 12, for example, concentric with the outer wall of the conduit 11. The second conduit 12 is attached to the inner surface of the first conduit 11 at various points.

[0029] The combination of these two pipes 11 and 12 allows water circulation, thus forming a first water-jacketed cooling device between the inner wall of 11 and the outer wall of 12. Since this cooling system is designed to cool electrode 1, a second pipe 12 passes through the extension 10. Therefore, the first cooling device 20 includes an inner pipe 12 and an outer pipe 11.

[0030] At the other end of the first conduit 11, a supply collar 13 (e.g., made of copper) is attached to an insulating shell 14. The collar 13 enables the first conduit 11 to reach the desired voltage, and the latter, as an electrical conductor, is able to supply power to the electrode 1 at the same voltage.

[0031] An electrical insulating material 15, advantageously made of a refractory material commercially available under the designation MURATHERM 500M, is placed around the first conduit 11. This material 15 is in the form of one or more sleeves that surround and abut against a portion of the outer surface of the first conduit 11. This electrical insulating material allows operators to approach the electrode supports without the risk of electric shock when near the molten bath. The material 15 itself is surrounded by a concentric sleeve 16 in which a cooling liquid (such as water) circulates. This "water jacket" type sleeve 16 includes an inner sleeve 17 that allows the cooling liquid to circulate, thereby forming a second cooling device 22. It is thus understood that the second cooling device 22 includes an inner conduit 17 and an outer conduit 16.

[0032] The second cooling device, which also includes two pipes, prevents the insulation material from overheating, even if the insulation material is selected to withstand fairly high temperatures and has already been partially cooled by the first cooling device.

[0033] On the other hand, even when the furnace is idle and the support 8 is mainly heated by radiation from the molten bath (in which there is no raw material layer 9), the outer surface of the electrode support 8 remains relatively cool and can be manipulated or at least approached by the operator.

[0034] Components 11, 12, 15, 16, and 17 form an empty conduit. It should be understood that components 11 and 16 are the outer conduits, and components 12 and 17 are the inner conduits.

[0035] According to the present invention, the pipes of the water-jacketed first cooling device 20 and the pipes of the water-jacketed second cooling device 22 have specific shapes and cross-sections. It should be understood that the shapes may have one or more accidental variations.

[0036] In one embodiment, the two pipes 11 and 12 of the first cooling device are circular or substantially circular. In this first embodiment, the pipes of the second cooling device are such that the sleeve 17 is circular or substantially circular, while the sleeve 16 is substantially parallelepiped or parallelepiped in shape, such as... Figure 3 As seen in the image. Preferably, the parallelepiped is square in shape.

[0037] The shape difference between the two pipes 16 and 17 of the second cooling device provides a mechanical advantage in the production of large arms. This is because the space between the two pipes 16 and 17 is the space in which the coolant circulates. When the coolant circulates, it contributes its mass to the entire electrode heating system. However, for an arm of a certain size, this mass can lead to mechanical stress. The goal is to achieve a balance between cooling performance and total weight.

[0038] The difference in shape between the two pipes results in a space that, for the same overall dimensions, has a larger surface area, such as... Figure 4 As shown in the diagram. This larger surface area enhances cooling by improving coolant circulation.

[0039] If available Figure 4 As seen in the examples, different configurations can be observed. In the first case (visible in A), the outer pipe 16 is a parallelepiped shape, while in the second case (visible in B), it is a circular outer pipe 16. Example C illustrates the difference in surface area between examples A and B. We can see that for the same overall dimensions, i.e., for the same distance between the central axis and the surface of the outer pipe 16, example A provides a larger cooling cross-sectional area. In fact, a 10 cm square gives a surface area of ​​100 square centimeters. For a circle with a diameter of 10 cm, a surface area of ​​78.5 square centimeters is obtained. This larger surface area allows more coolant to pass through. On the other hand, for the same amount of coolant, the pipe size can be reduced. This reduction in pipe size lightens the weight of the support 8 and thus increases its mechanical strength.

[0040] In such Figure 5 In the variant shown, the sleeve 16 of the second cooling device is also approximately parallelepiped or parallelepiped in shape, preferably square. Therefore, the two pipes of the second cooling device are parallelepiped, preferably square.

[0041] In another variation, the sleeve 16 and / or the tube 17 have a rectangular shape.

[0042] exist Figure 6 In the variation shown, pipe 11 also has a parallelepiped shape, preferably a square. This means that sleeve 16 and conduit 17 have a generally parallelepiped or parallelepiped shape, preferably a square. This variation does not preclude the use of circular pipes 16 and 17, but the overall size and weight would be greater.

[0043] exist Figure 7 In the variations shown, pipe 12 also has a parallelepiped shape or one of the parallelepiped shapes, preferably square. This means that pipe 11, sleeve 16, and conduit 17 also have a parallelepiped shape, preferably square. The square shape of all pipes means a larger surface area for the same footprint. Therefore, pipes 11, 12, 16, and 17 of the present invention provide better cooling compared to circular shapes. However, at the same time, this also means a smaller footprint for the same coolant flow rate.

[0044] The diagram does not show the various coolant inlet and outlet pipelines.

[0045] The coolant used for cooling is advantageously softened water, which means that the same line can be used for two cooling systems without any risk of current being conducted to an external cooling system that is also grounded.

[0046] The electrodes and their supports described in this way enable them to be used risk-free in normal operating mode because no accessible devices are powered and there is no risk of damaging the supports when the furnace is in standby mode.

[0047] Therefore, the apparatus comprising electrodes and their supports as described in this invention retains the various advantages associated with electromelting using electrodes immersed in the surface of a molten bath, as listed above. These advantages include: good heat yield; good quality of the molten material even with variations in drawing; longer furnace life due to less damage to the refractory material; and easy electrode replacement.

[0048] Furthermore, the device according to the invention enables the avoidance of fully submerged electrodes during standby periods, or the avoidance of the presence of a protection system that prevents operators from being near continuously energized components throughout the entire operation.

[0049] Alternatively, conduit 11 is not an electrical conductor. Conductivity is provided by a dedicated conduit or rod. In the case of a conduit, this can be arranged to be surrounded by conduit 11. In this way, insulating material 15 surrounds and contacts the conductive conduit. In this case, conduit 11 is, for example, a steel shell, while the dedicated conductive conduit is made of a conductive material, such as copper.

[0050] In the case of conducting electricity through the rod, the rod is ideally placed within the conduit 12. This arrangement forces the conduit 12, and therefore the conduit 11, the sleeve 16, and the casing 17, to have a larger diameter to compensate for the presence of the rod. The material used for the rod is a conductive copper-type material.

[0051] According to the invention, the support member 8 is similar to an arm with a horizontal protrusion. The horizontal span of the protrusion is greater than 2000 mm, preferably greater than 2500 mm, more preferably greater than 3000 mm, more preferably greater than 3500 mm, more preferably greater than 3700 mm, and more preferably greater than 3900 mm.

[0052] Of course, the present invention is not limited to the examples shown, but various variations and modifications can be made, which will be obvious to those skilled in the art.

Claims

1. A support (8) for a melting electrode (1) immersed in a molten bath, the support (8) having a power supply system and a first cooling device (20) comprising an interconnected inner conduit (12) and an outer conduit (11) for circulating a cooling liquid, the outer conduit of the first cooling device being surrounded by an electrical insulator, the electrical insulator being surrounded by a second cooling device (22) comprising an interconnected inner conduit (17) and an outer conduit (16) for circulating a cooling liquid, characterized in that, The second cooling device has at least one of its outer pipes having a generally parallelepiped or parallelepiped cross-section.

2. The support member according to the preceding claim, wherein, Furthermore, the cross-section of the inner pipe of the second cooling device is approximately parallelepiped, or is parallelepiped.

3. The support member according to any one of claims 1 or 2, wherein, The cross-section of the outer pipe of the first cooling device is approximately parallelepiped, or is parallelepiped.

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

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

6. The support member according to any one of claims 1 to 4, wherein, The cross-section of the pipe having a non-parallelxhedral cross-section is circular or approximately circular.

7. The support member according to any one of the preceding claims, wherein, The outer conduit of the first cooling device is conductive and forms the current supply system.

8. The support member according to any one of the preceding claims has a horizontal span 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.

Images