Glass furnace armature

Abstract

Glass Furnace Frame The invention relates to a glass furnace (1), at least partly electric, comprising a melting tank (2) made of refractory materials, adapted to contain a bath (3) of molten glassable materials, and a plurality of heating electrodes (4) adapted to supply electric current to said bath, said tank (2) being held in place by a metallic frame (6), said furnace being characterized in that said frame (6) comprises a set of electrical insulators (7) which form an electrical containment barrier for the tank (2). Figure for the abstract: Fig. 1

Description

Title of the invention: Glass furnace armature

[0001] The present invention belongs to the general field of glass production. More particularly, it relates to a glass furnace, at least partially electric, adapted for melting vitrifiable materials. It also relates to a process for melting vitrifiable materials so as to be able to manufacture glass. The invention finds a particularly advantageous, though by no means limiting, application in the production of glass wool, rock wool, textile glass yarns, and / or flat or hollow glass.

[0002] In this description, "vitrifiable materials" or "raw materials" means all materials, natural ores or synthesized products, recycled materials such as cullet, etc., that can be used in the composition used to feed a glass furnace. This includes silica sand, but also all additives (sodium carbonate, limestone, dolomite, alumina, etc.), waste (including mineral fibers) that may come from the production of said fibers or from construction or deconstruction sites, all possible liquid or solid fuels (plastic, composite or non-composite material, organic matter, coal), and all types of cullet.Also included are recyclable materials containing combustible (organic) elements, such as, for example, coated mineral fibers with a binder (of the type used in thermal or acoustic insulation or in reinforcing plastics), laminated glass with polyvinyl butyral polymer sheets such as windshields, glass bottles (household cullet), or any type of composite material combining glass and plastics such as certain bottles. Also recyclable are glass-metal composites or metallic composites such as functionalized glass with coatings containing metals. In the description, the "glass bath" or "glass bath" refers to the product of melting these raw materials.

[0003] Similarly, "glass" is understood to mean glass in the broad sense, that is to say, encompassing any material with a vitreous matrix, glass-ceramic or ceramic.

[0004] In addition, the term "manufacturing" includes the indispensable melting stage of the vitrifiable materials and, where applicable, all subsequent / complementary stages aimed at refining / conditioning the molten glass for its final shaping, in particular in the form of flat glass (windows), hollow glass (flaps, bottles), glass in the form of mineral wool (in particular rock wool or glass wool) used for its thermal or acoustic insulation properties, or even possibly glass in the form of so-called textile yarns used in reinforcement.

[0005] Various examples of electric furnace designs are known from the prior art, in which the current is conducted in the bath of vitrifiable materials by heating electrodes. Such electrodes can be of the so-called "immersed" type - being arranged vertically in the bath from the floor of the furnace or horizontally, passing through the side walls of the furnace - and / or of the "plunging" type, being immersed from the free surface of the bath.

[0006] Surprisingly, the inventors observed leakage currents through the refractory melting chamber of the glass furnace, despite the electrically insulating nature of these materials. This is explained by the localized reduction in the chamber's thickness due to corrosion of the refractories by the glass bath during the furnace's lifespan, and / or by the infiltration of conductive liquid glass into the chamber's thickness. These unwanted leakage currents cause localized heating of the refractory material, which reduces its durability. Furthermore, they represent an unnecessary energy loss that impacts the furnace's energy balance. The grounding short circuits generated by these leakage currents can also damage the equipment.Finally, these leakage currents increase the risk of electrocution – of potentially fatal intensity – for an operator positioned near the furnace in the event of accidental contact with a live part.

[0007] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above.

[0008] To this end, and according to a first aspect, the invention relates to a glass furnace at least partly electric comprising a melting tank made of refractory materials, adapted to contain a bath of molten vitrifiable materials, and a plurality of heating electrodes adapted to bring electric current into said bath, said tank being held in place by a metal frame, said furnace being characterized in that said frame comprises a set of electrical insulators which form an electrical containment barrier of the tank.

[0009] For the purposes of this invention, the metal reinforcement refers to an assembly designed to hold together, reinforce, and support the various parts of the refractory tank. For the purposes of this invention, and in accordance with ISO / R836 or AFNOR NF B 40-001 standards, "refractory" materials are defined as materials and products other than metals and alloys (including those containing a metallic component), whose pyroscopic resistance is equivalent to at least 1500 °C. This definition means that the refractory materials must withstand at least 1500 °C without softening or collapsing under their own weight, according to the standard of the pyroscopic resistance test.

[0010] The invention is based, on the one hand, on the surprising observation made by the inventors of the existence of leakage currents through the melting tank of the glass furnace made of refractory materials, despite the electrical insulating nature of the latter, and on the other hand on the new and inventive concept of equipping the metal frame which holds the tank in place with a set of electrical insulators in order to electrically confine this melting tank and thus avoid or at least limit the generation of these leakage currents.

[0011] The prohibition of these leakage currents makes it possible to limit the risks of premature degradation of the tank, to reduce the energy consumption of the furnace or at least, to optimize its melting capacity, to prevent short circuits to earth which can damage the equipment, and to limit the risks of electrocution of an operator.

[0012] According to a particular embodiment, the glass furnace comprises a vault, preferably cold, held in place by said metal framework, said set of electrical insulators also forming an electrical containment barrier of the vault.

[0013] According to a particular embodiment, at least one electrical insulator is arranged in direct contact with the tank or vault.

[0014] Such a positioning of the electrical insulator makes it possible to spatially limit the extent of the areas that can be energized, and therefore the risks of electrocution.

[0015] According to a particular embodiment, at least one electrical insulator is separated from the tank or vault by means of at least one element of said reinforcement.

[0016] Such a so-called "remote" mounting of the electrical insulator is easier to implement, but has the disadvantage of extending to a part of the armature the area that can be energized.

[0017] According to a particular embodiment, said frame comprises at least one pusher for retaining a side wall of the tank or vault, preferably by means of a grating, an angle iron or U-shaped iron, or a plate, and at least one electrical insulator arranged between the pusher and the tank or vault, preferably between the pusher on one side and the grating, iron, or plate on the other.

[0018] Such a push button therefore constitutes an example of an electrical insulator suitable for being mounted alternately in direct contact with the tank or vault, or in a "remote" manner within the frame.

[0019] According to a particular embodiment, said electrical insulator assembly includes an electrical insulation sleeve of a plate, or of a shaft, intended to be in electrical contact with the tank or the vault.

[0020] Such a sleeve therefore constitutes an example of an electrical insulator suitable for being mounted in a "remote" manner within the armature.

[0021] According to a particular embodiment, said set of electrical insulators includes a brick, preferably made of zircon, suitable for electrically insulating a beam and / or a flat iron intended to be in contact with the tank or the vault, said brick being preferably fixed within an omega iron.

[0022] Such a brick therefore constitutes an example of an electrical insulator suitable for being mounted in a "remote" manner within the frame.

[0023] According to a particular embodiment, at least one of said electrical insulators belongs to the group comprising zircon, insulators with high electrical resistivity and high compressive strength, such as Isoref 140, high-performance plastics, composite fibers (epoxy glass, fiber cement), materials based on mica laminated with resins.

[0024] This group of materials combines electrical and mechanical insulation performance, and is therefore particularly suitable for the invention.

[0025] According to a particular embodiment, said set of electrical insulators also forms an electrical containment barrier for said heating electrodes.

[0026] The inventors have indeed observed the existence of leakage currents flowing through the heating electrodes. The electrical insulation of the latter provides a solution to this risk.

[0027] According to a particular embodiment, the glass furnace includes at least one instrument for measuring a physical variable within the tank and / or the vault, preferably a thermocouple, said set of electrical insulators also forming an electrical containment barrier for said measuring instrument.

[0028] The inventors have indeed observed the existence of leakage currents flowing through such a measuring instrument. The electrical insulation of the latter provides a solution to this risk.

[0029] According to a particular embodiment, the glass furnace is characterized in that it is fully electric, in that it preferably comprises a cold vault, and in that said melting tank is preferably dimensioned such that said molten glass bath has a surface area greater than 6 m², preferably greater than 13 m², preferably greater than 19 m², preferably greater than 25 m², preferably greater than 40 m², preferably greater than 60 m², preferably greater than 100 m², and preferably has a distance between two opposite walls of said tank greater than 2.5 m, preferably greater than 3.1 m, preferably greater than 5 m, preferably greater than 6.5 m

[0030] Such dimensions relate to so-called large electric furnaces, for which the implementation of a two-phase system is particularly advantageous.

[0031] According to a particular embodiment, the glass furnace is of a hybrid type and includes combustion heating means, preferably burners submerged and / or emerged, and a warm vault.

[0032] According to a particular embodiment, at least one heating electrode is immersed from the free surface of said bath and supplied with electric current by an electrical installation adapted to generate a two-phase or three-phase alternating current.

[0033] Compared with so-called "immersed" type electrodes, immersion electrodes offer a number of advantages. First, they avoid the difficulties associated with the passage of immersed electrodes through the refractory, and also the problems of replacing these electrodes when worn, the problems of sealing the melting tank or even of wear of the refractories, in particular due to a high temperature which promotes the attack of the refractory and to powerful convection currents which develop near the electrodes during operation.

[0034] Three-phase current offers numerous advantages, foremost among them the fact that it is the so-called "industrial" current commonly distributed to factories by energy suppliers, hence the resulting adaptation of machinery. Three-phase current also delivers instantaneous power without a pulsed component, unlike, for example, single-phase current. It should be noted, however, that the principle of phase balance tends towards the implementation of a triangular or hexagonal arrangement of the electrodes on the surface of the glass bath. While such a geometric constraint does not appear a priori to pose a prohibitive problem in the context of a small electric furnace, it does pose one in the context of a large electric furnace, where the glass bath extends over more than 25 m², preferably more than 49 m², and where the edge-to-edge width of the glass bath is greater than 5 m, preferably greater than 7 m.In such a configuration, and given the aforementioned geometric constraints, the current tends to concentrate between the electrodes on the same edge of the vat and / or adjacent edges, thus reducing the distance traveled by the current within the glass bath and consequently the resistance of the glass bath to the passage of this current. For a predetermined electrical power corresponding to the energy required to melt the glassable materials, and in the context of a glass bath offering only low resistance, it is therefore necessary to increase the intensity of the current delivered. However, the wear of the electrodes and the refractories constituting the vat increases with the intensity of the current delivered per electrode.To address this wear problem, the obvious solution is to distribute the delivered current between a larger number of electrodes, which, however, has the disadvantage of increasing the operating costs of these electrodes – since there are more of them – without resolving certain problems of inhomogeneity in the distribution of the electrical current within the glass bath.

[0035] According to a particular embodiment, the invention relates to a process for melting vitrifiable materials implemented by means of such a glass furnace, and characterized in that it comprises at least one step of electrically heating said bath of molten vitrifiable materials by means of said plurality of electrodes.

[0036] According to a particular embodiment, the invention also relates to a method for manufacturing glass wool, rock wool, textile glass yarns and / or flat or hollow glass, characterized in that it implements such a melting process.

[0037] Other features and advantages of the present invention will become apparent from the description given below, with reference to the attached drawings which illustrate an example of an embodiment without any limiting character.

[0038] In the figures: [Fig.1] [Fig.1] schematically represents, in profile view, an electric glass furnace according to a particular embodiment of the invention; [Fig.2] [Fig.2] schematically represents, in profile view, a type of electrical insulator mounted on a pusher of the armature of an electric glass furnace according to a particular embodiment of the invention; [Fig.3] [Fig.3] schematically represents, in profile view, a type of electrical insulator, in this case a sleeve, mounted on the frame of an electric glass furnace according to a particular embodiment of the invention; [Fig.4] [Fig.4] schematically represents, in profile view, a type of electrical insulator, in this case a brick, mounted on the frame of an electric glass furnace according to a particular embodiment of the invention; [Fig.5] [Fig.5] is a flow diagram illustrating the successive steps of a manufacturing process according to a particular embodiment of the invention.

[0039] Figure 1 schematically represents, in profile view, an electric glass furnace 1. Such a glass furnace 1 comprises a melting tank 2 made of refractory materials adapted to contain a bath 3 of molten glassable materials and a plurality of electrodes 4, including immersed electrodes (only one is shown in Figure 1 for illustrative simplification) and plunge electrodes, the arms of which have a square cross-section, which are immersed from the free surface of said bath 3. All these electrodes 4 are supplied with electric current by an electrical installation. A glass furnace 1 according to the invention is particularly characterized in that said electrical installation is adapted to generate a two-phase alternating current.

[0040] According to the particular embodiment illustrated in [Fig.1], the furnace 1 is totally electric and is equipped with a cold vault 5. According to alternative embodiments, such a glass furnace is of hybrid type and includes, in addition to electrodes, combustion heating means, preferably immersed and / or emerged burners, and a hot vault.

[0041] As illustrated in [Fig. 1], the tank 2 and the vault 5 are held in place by a metal frame 6. This frame 6 comprises a set of electrical insulators 7 that form an electrical containment barrier for the tank 2 and the vault 5. This makes it possible to prevent, or at least limit, the generation of leakage currents from the glass bath. These electrical insulators can take different forms and be implemented in different mechanical systems within the metal frame, as detailed later in this description.

[0042] According to a particular embodiment illustrated in [Fig. 2], such an electrical insulator 7 is mounted on a pusher 8 that retains a side wall of the tank 2 (or the vault 5). More precisely, the electrical insulator 7, in the form of a plate, is arranged in direct contact with the tank 2, between the pusher 8 and the tank. As illustrated in [Fig. 1], a grating, an angle iron or U-shaped iron, or a plate 14, can be arranged between the electrical insulator 7 and the tank 8, in particular to distribute the compressive forces exerted by the pusher 8 over a larger surface area of ​​the tank. The electrical insulator 7 is then arranged in a so-called "offset" mounting, since it is separated from the tank 2 by means of at least one element of the metal reinforcement 6.

[0043] According to a particular embodiment illustrated in [Fig. 3], the electrical insulator assembly 7 comprises an electrical insulation sleeve 9 arranged around a metal plate 11 which is itself in electrical contact with the tank 2 (or the vault 5). The sleeve 9 is then arranged in a so-called "offset" configuration, since it is separated from the tank 2 by means of at least one element of the metal reinforcement 6, in this case, the metal plate 11.

[0044] According to a particular embodiment illustrated in [Fig.4], the electrical insulator assembly 7 comprises a zirconium brick 10 or any other refractory or insulating material of sufficient electrical resistivity and compressive strength, such as Isoref C140 for example, which is arranged between an omega iron 13 on the one hand, and a flat iron 12 on the other hand, this flat iron 12 being itself in contact with the base of the tank 2. The brick 10 is then arranged according to a so-called "offset" mounting, since it is separated from the tank 2 by means of at least one element of the metallic reinforcement 6, in this case, the flat iron 12.

[0045] Fig. 5 is a flow diagram illustrating the successive stages of a manufacturing process according to a particular embodiment of the invention, which includes a first stage SI of melting vitrifiable materials by electrical heating of said bath 3 of vitrifiable materials by means of a two-phase alternating current, and a second stage S2 of manufacturing glass wool, rock wool, textile glass yarns and / or flat or hollow glass.

Claims

Demands

1. Glass furnace (1) at least partly electric comprising a melting tank (2) made of refractory materials, adapted to contain a bath (3) of molten vitrifiable materials, and a plurality of heating electrodes (4) adapted to bring electric current into said bath, said tank (2) being held in place by a metallic frame (6), said furnace being characterized in that said frame (6) comprises a set of electrical insulators (7) which form an electrical containment barrier of the tank (2).

2. Glass furnace (1) according to claim 2, characterized in that it comprises a vault (5), preferably cold, held in place by said metallic frame (6), said set of electrical insulators (7) also forming an electrical containment barrier of the vault (5).

3. Glass furnace (1) according to any one of claims 1 and 2, characterized in that at least one electrical insulator (7) is arranged in direct contact with the tank (2) or the vault (5).

4. Glass furnace (1) according to any one of claims 1 to 3, characterized in that at least one electrical insulator (7) is separated from the tank (2) or the vault (5) by means of at least one element of said armature (6).

5. Glass furnace (1) according to any one of claims 1 to 4, characterized in that said frame (6) comprises at least one pusher (8) for holding a side wall of the tank (2) or the vault (5), preferably by means of a grating, an angle iron or U-shaped iron, or a plate (14), and at least one electrical insulator (7) arranged between the pusher (8) and the tank (2) or the vault (5), preferably between the pusher (8) on the one hand and the grating, the iron, or the plate on the other hand.

6. Glass furnace (1) according to any one of claims 1 to 5, characterized in that said electrical insulator assembly (7) comprises an electrical insulation sleeve (9) of a plate (11), or of a shaft, intended to be in electrical contact with the tank (2) or the vault (5).

7. Glass furnace (1) according to any one of claims 1 to 6, characterized in that said electrical insulator assembly (7) comprises a brick (10), preferably made of zirconia, adapted to electrically insulate a beam and / or a flat bar (12) intended to be in contact with the furnace (2) or the vault (5), said brick (10) being preferably fixed within of an omega iron (13).

8. Glass furnace (1) according to any one of claims 1 to 7, characterized in that at least one of said electrical insulators (7) belongs to the group comprising zircon or any other refractory material or insulators, such as Isoref C140, composite fibers (epoxy glass, fiber cement), materials based on mica laminated with resins.

9. Glass furnace (1) according to any one of claims 1 to 8, characterized in that said set of electrical insulators (7) also forms an electrical containment barrier of said heating electrodes (4).

10. Glass furnace (1) according to any one of claims 1 to 9, characterized in that it comprises at least one instrument for measuring a physical variable within the tank (2) and / or the vault (5), preferably a thermocouple, said set of electrical insulators (7) also forming an electrical containment barrier for said measuring instrument.

11. Glass furnace (1) according to any one of claims 1 to 10, characterized in that it is totally electric, that it preferably comprises a cold vault, and in that said melting tank is preferably dimensioned so that said bath of molten vitrifiable materials has a surface area greater than 6 m2, preferably greater than 13 m2, preferably greater than 19 m2, preferably greater than 25 m2, preferably greater than 40 m2, preferably greater than 60 m2, preferably greater than 100 m2, and has a distance between two opposite walls of said tank greater than 2.5 m, preferably greater than 3.1 m, preferably greater than 5 m, preferably greater than 6.5 m.

12. Glass furnace (1) according to any one of claims 1 to 10, characterized in that it is of hybrid type and comprises combustion heating means, preferably immersed and / or emerged burners, and a hot dome.

13. Glass furnace (1) according to any one of claims 1 to 11 characterized in that at least one heating electrode (4) is immersed from the free surface of said bath (3) and supplied with electric current by an electrical installation adapted to generate a two-phase or three-phase alternating current.

14. A method for melting vitrifiable materials implemented using a glass furnace according to any one of claims 1 to 13, characterized in that it includes at least one step (SI) of electrically heating said bath (3) of molten vitrifiable materials by means of said plurality of electrodes (4).

15. A manufacturing process (S2) of glass wool, rock wool, textile glass yarns and / or flat or hollow glass, characterized in that it implements a melting process according to claim 14.

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