EP0671116A1 - Electric melting device - Google Patents

Electric melting device

Info

Publication number
EP0671116A1
EP0671116A1 EP94928439A EP94928439A EP0671116A1 EP 0671116 A1 EP0671116 A1 EP 0671116A1 EP 94928439 A EP94928439 A EP 94928439A EP 94928439 A EP94928439 A EP 94928439A EP 0671116 A1 EP0671116 A1 EP 0671116A1
Authority
EP
European Patent Office
Prior art keywords
electrode
support
cooling system
cooling
electrodes
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP94928439A
Other languages
German (de)
French (fr)
Other versions
EP0671116B1 (en
Inventor
Gérard Delahalle
Stéphane Maugendre
Thierry Caillaud
Pierre Peigne
François Szalata
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Isover SA France
Original Assignee
Saint Gobain Isover SA France
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Saint Gobain Isover SA France filed Critical Saint Gobain Isover SA France
Publication of EP0671116A1 publication Critical patent/EP0671116A1/en
Application granted granted Critical
Publication of EP0671116B1 publication Critical patent/EP0671116B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/02—Details
    • H05B3/03—Electrodes

Definitions

  • the invention relates to electric fusion techniques and relates more particularly to those in which energy is dissipated by the Joule effect in the molten mass from plunging electrodes.
  • glass production facilities operating on large quantities were provided with melting furnaces supplied with fossil fuel, such as fuel oil or gas. This was in particular the case for large capacity continuous production plants supplying, for example, flat glass or glass.
  • electrical energy when it was used, was mainly used as a local backup to maintain the temperature of the glass in the coolest areas, or outside the oven on its way to the place of transformation or to develop certain convection movements to promote homogenization, refining or transport of the molten material.
  • the electrodes are arranged vertically in the bath from the bottom of the oven. In other embodiments, there are also electrodes passing through the side walls of the furnace.
  • the immersion of the electrodes also allows a convenient and very uniform supply of the surface of the bath with a composition of raw materials.
  • the constitution of a relatively thick layer of composition to be melted, floating on the molten bath, is useful indeed for several reasons. It forms, in contact with the molten bath, the permanent reserve of material necessary for continuous operation. It also protects the molten bath from high heat loss by convection in contact with the atmosphere and especially by radiation.
  • ovens of the type described in the aforementioned document find very important industrial applications, they do not necessarily make it possible to best meet all the requirements encountered in practice.
  • Such a transformation is not possible when it comes to implanting electrodes in the hearth or in the side walls of the furnace.
  • Ovens with submerged electrodes offer limited possibilities for electrode adjustment. If they lead to completely satisfactory performance for a certain regime, they are less suitable for frequent and / or substantial modifications of this operating regime.
  • the plunging electrode technique locates the hottest areas at the top of the molten bath and thus alleviates these problems.
  • this technique makes it possible to modify the immersion depth of the electrodes and therefore the temperature gradient. This allows changes in the oven temperature without changing the temperature of the hearth and, consequently, the temperature of the glass leaving the oven.
  • a usual solution consists in raising the immersing electrodes during a standby phase and in maintaining a sufficient temperature in the bath by submerged electrodes most often placed on the walls.
  • This technique is effective but we find the problems associated with immersed electrodes although in the present case, they operate at lower voltages since they only maintain the temperature of the already molten bath.
  • submerged electrodes require additional investment costs.
  • Such a device most often consists of a wire mesh which prevents employees from accessing the oven.
  • certain measures which require the presence of an operator near the bath and therefore of electrode supports put this operator in danger.
  • the object of the invention is to provide a device for the electrical melting of a vitrifiable charge which acts either under normal operating conditions or during standby without the intervention of submerged electrodes and without risk for operators.
  • a fusion electrode support immersed from the surface of a molten bath, said support comprising a current supply system and having thermal protection on the surface, said surface being isolated from the voltage of the current conductor.
  • the current supply system is a cooling system, of the "water-jacket" type conducting electric current.
  • This device is then surrounded by an electrical insulator, advantageously made of a material resistant to very high temperatures.
  • the insulation which is chosen to withstand high temperatures is advantageously cooled by the circulation of water from the current conducting cooling system.
  • the invention advantageously proposes to surround the electrical insulator with a second cooling system of the "water-jacket" type. It is thus possible to choose a material for the electrical insulator resistant to lower temperatures. In addition, such a material generally sees its electrical insulation properties improve at low temperature.
  • the electrode support thus proposed therefore comprises two cooling systems.
  • the cooling systems are advantageously produced by circulating water.
  • the internal system being current conductor electric for supplying the electrode, the invention provides two separate water circulation circuits so that the current-carrying water circulating in the cooling system supplying the electrode does not provide a voltage at the level of the second cooling system which would then no longer have any utility.
  • the two cooling systems are supplied by the same water circuit, the water being demineralized so that it does not conduct current.
  • the device for supplying water outside the electrode support can thus be limited to a single circuit.
  • FIGS. 1, 2 and 3 represent:
  • FIG. 1 a section of a partial schematic representation of an oven having electrodes immersed vertically from the surface
  • FIG. 2 a diagram of an embodiment according to the invention of an electrode and its support.
  • FIG. 1 represents part of a melting furnace associated with plunging electrodes 1.
  • the furnace is constituted by a refractory basin composed of the bottom 2 and the side walls 3. Above the basin, the refractory vault 4 is suspended from a metal frame 5 partially shown, said metal frame 5 overlapping the oven.
  • Movable refractory walls 6 are provided which, when they are in the low position, that is to say resting on the side walls 3, make it possible to partially isolate the molten bath 7 from the surrounding atmosphere.
  • the electrode 1 As regards the electrode 1, it is immersed on the surface of the fusion bath 7 under the layer 9 of raw materials to be melted. This layer 9 which covers the fusion bath 7 in normal operating mode, thermally insulates the basin and makes it possible to avoid heat loss.
  • the electrode 1 is fixed to the support 8 which comprises the electrical supply system and a device for cooling the electrode 1, which are not shown in this FIG. 1.
  • the support 8 is itself connected to a mechanism, not shown, which makes it possible in particular to remove an electrode 1 from the bath, for example for a change or a repair.
  • the electrode 1 and its support 8 are more precisely represented and show the advantages of the invention.
  • the electrode 1, usually made of molybdenum, is fixed by means of a current conducting element 10 to the tube 11 which constitutes the electric current conducting cooling device.
  • the element 10 is an extension which is fixed to the tube 11 by screwing. At the other end of this extension 10, the electrode 1 is fixed.
  • Such an embodiment makes it possible to easily disassemble the set extension 10 / electrode 1 because the place of the screwing never dips in the bath. fusion. Indeed, if the tube 11 was longer and came to soak directly in the bath, it would be possible to directly attach the electrode 1 to it, for example by screwing.
  • the extension 10 can be surrounded, at least partially, by a refractory material sufficiently thick to avoid direct contact with raw materials or the molten bath.
  • the extension 10 also allows the passage of the coolant to the electrode so that it is cooled.
  • Screw fixing is interesting because it allows quick replacement. Electrode replacements can be frequent because they do not only intervene in the event of wear but also make it possible to modify the electrodes and in particular their length so as to modify the level of immersion and therefore the energy intake. in the oven.
  • the tube 11 can be made of steel so that it has good rigidity and conduction properties.
  • a second tube 12 for example concentric.
  • This second tube 12 is for example fixed at different points to the internal surface of the tube 11.
  • the association of these two tubes 11 and 12 allows water to circulate and thus constitutes a water-type cooling device. jacket.
  • the cooling system being designed so as to cool the electrode 1, the tube 12 crosses the extension 10.
  • a supply col ⁇ 13 for example copper itself placed within an insulating formwork 14.
  • This collar 13 allows to put the tube 11 at the desired voltage, and the latter being electrically conductive, supplying the electrode 1 with this same voltage.
  • an electrical insulating material 15 advantageously made of a refractory material of the type of the electrical insulator sold under the reference MURATHERM 500 M.
  • the material 15 is made in the form of one or more sleeves which envelop and are supported on a part of the external surface of the tube 11. This electrical insulating material therefore allows access to the electrode support without any risk of electrocution for operators who must approach the weld pool.
  • the material 15 is itself surrounded by a concentric envelope 16 in which circulates a cooling liquid such as water.
  • This envelope 16 of the "water-jacket" type comprises an internal sleeve 17 which allows the circulation of water.
  • This second cooling device makes it possible on the one hand to avoid overheating of the insulating material even if it is chosen as being able to withstand fairly high temperatures and if it is already partly cooled by the first cooling system .
  • the various elements cited 11, 12, 15, 16, 17 constitute tubes, for example, concentric, placed around one another.
  • a cooling device of the "water-jacket" type, current conductor consisting of two concentric tubes 18, 19 is surrounded by one or more sleeves 20 made of an electrically insulating material and having good thermal insulation and good temperature resistance.
  • Thermal protection of the surface of the electrode support is then obtained on the one hand, by the very nature of the sleeve 20 and on the other hand, by the presence of the cooling device which makes it possible to cool this sleeve 20 .
  • the electrical protection is provided by the sleeve 20 which envelops the current conducting tube 19.
  • the various pipes allowing the arrival and departure of the cooling water are not shown in the figures.
  • the water used for cooling is advantageously demineralized water, which makes it possible to use the same circuits for the two cooling systems without the risk of conduction of the current to the external cooling system, which is also connected To the earth.
  • the unnumbered arrows indicate the different circuits followed by the coolant.
  • the electrode associated with its support thus described according to the invention allows on the one hand a risk-free use in normal operating mode since no accessible device is energized and on the other hand a use without risk of degradation of the support when the oven is put on hold.
  • the device composed of the electrode and of its support according to the invention therefore makes it possible to conserve the various advantages, linked to the electrical fusion by electrode immersed from the surface of the fusion bath, which have been listed previously. These are, for example, good thermal yields, good quality of the molten material despite changes in draft, an increase in the life of the furnace because the refractories are less attacked or because it is easy to change an electrode.
  • the device according to the invention makes it possible to avoid the presence of fully submerged electrodes for the pilot light periods or else the full-time presence of a protection system avoiding the presence of operators near the elements continuously. under tension.

Landscapes

  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Furnace Details (AREA)
  • Resistance Heating (AREA)
  • Control Of Resistance Heating (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Discharge Heating (AREA)

Abstract

The invention relates to electric melting technique, and particularly to technique where energy is dissipated by Joule effect in the melt from downwardly immersed electrodes. A support (8) for an electrode (1) of this type comprises a power supply system and a cooling system, and is provided on its surface with thermal protection, said surface being insulated with respect to voltage in the power conductor.

Description

DISPOSITIF POUR LA FUSION ELECTRIQUE DEVICE FOR ELECTRICAL FUSION
L'invention est relative aux techniques de fusion électrique et concerne plus particulièrement celles dans lesquelles l'énergie est dissipée par effet Joule dans la masse fondue à partir d'électrodes plongeantes. Pendant longtemps, les installations de production de verre opérant sur de grandes quantités ont été pourvues de fours de fusion alimentés en combustible fossile, tel que fioul ou gaz. C'était en particulier le cas pour les ins¬ tallations de production en continu de grande capacité fournissant par exemple le verre plat ou le verre de bout- eillerie. Sur ces grands fours l'énergie électrique, lorsqu'elle était utilisée, l'était essentiellement comme appoint local pour maintenir la température du verre dans les zones les moins chaudes, ou en dehors du four dans son cheminement vers le lieu de transformation ou encore pour développer certains mouvements de convection pour favoriser l'homogénéisation, l'affinage ou le transport du matériau fondu.The invention relates to electric fusion techniques and relates more particularly to those in which energy is dissipated by the Joule effect in the molten mass from plunging electrodes. For a long time, glass production facilities operating on large quantities were provided with melting furnaces supplied with fossil fuel, such as fuel oil or gas. This was in particular the case for large capacity continuous production plants supplying, for example, flat glass or glass. On these large ovens, electrical energy, when it was used, was mainly used as a local backup to maintain the temperature of the glass in the coolest areas, or outside the oven on its way to the place of transformation or to develop certain convection movements to promote homogenization, refining or transport of the molten material.
La fusion électrique proprement dite est d'abord ap- parue sur des petites unités pour lesquelles une grande souplesse dans les conditions d'utilisation semblait né¬ cessaire. Les fluctuations des coûts énergétiques et la maîtrise progressive de certains problèmes d'ordre techno¬ logique ont conduit plus récemment au développement d'uni- tés de production importantes dans lesquelles l'ensemble du processus de fusion, à l'exception de la mise en service, se déroule en ayant recours à l'énergie électrique. Ce dé¬ veloppement requiert la solution de problèmes technologi¬ ques extrêmement délicats.The actual electric fusion was first appeared on small units for which a great flexibility in the conditions of use seemed necessary. Fluctuations in energy costs and the gradual mastery of certain technological problems have more recently led to the development of large production units in which the entire fusion process, with the exception of the service, takes place using electrical energy. This development requires the solution of extremely delicate technological problems.
FaBLLEDEREMPLACEMENT REGLE26 C'est ainsi que, notamment pour éviter la question de l'oxydation des électrodes à la surface du bain en fusion, il a été proposé de les immerger complètement. C'est la solution retenue, par exemple, dans la demande de brevet français publiée sous le numéro FR-A-2 552 073. Dans ce document, les électrodes sont disposées verticalement dans le bain à partir de la sole du four. Dans d'autres réali¬ sations, on trouve aussi des électrodes passant par les parois latérales du four. Indépendamment des avantages qu'elle procure vis-à-vis des problèmes de corrosion, l'immersion des électrodes permet aussi une alimentation commode et bien uniforme de la surface du bain en composition de matières premières. La constitution d'une couche relativement épaisse de composi- tion à fondre, surnageant sur le bain fondu, est utile en effet pour plusieurs raisons. Elle forme, au contact du bain en fusion, la réserve permanente de matière nécessaire au fonctionnement continu. Elle protège aussi le bain en fusion d'une forte déperdition calorifique par convection au contact de l'atmosphère et surtout par rayonnement.FABLESLOCATION RULE26 Thus, in particular to avoid the question of the oxidation of the electrodes on the surface of the molten bath, it has been proposed to immerse them completely. This is the solution adopted, for example, in the French patent application published under the number FR-A-2 552 073. In this document, the electrodes are arranged vertically in the bath from the bottom of the oven. In other embodiments, there are also electrodes passing through the side walls of the furnace. Independently of the advantages which it provides with regard to corrosion problems, the immersion of the electrodes also allows a convenient and very uniform supply of the surface of the bath with a composition of raw materials. The constitution of a relatively thick layer of composition to be melted, floating on the molten bath, is useful indeed for several reasons. It forms, in contact with the molten bath, the permanent reserve of material necessary for continuous operation. It also protects the molten bath from high heat loss by convection in contact with the atmosphere and especially by radiation.
Si les fours du type décrit dans le document précité trouvent des applications industrielles très importantes, ils ne permettent pas de répondre nécessairement au mieux à toutes les exigences rencontrées dans la pratique. A titre d'exemple il est souhaitable, dans certains cas, et dans le but évident de limiter les coûts d'investissement, de transformer les installations fonctionnant avec des brûleurs en conservant le plus possible des éléments exis¬ tants et notamment les matériaux réfractaires constituant le bassin. Une telle transformation n'est pas possible lorsqu'il s'agit d'implanter des électrodes dans la sole ou dans les parois latérales du four.If the ovens of the type described in the aforementioned document find very important industrial applications, they do not necessarily make it possible to best meet all the requirements encountered in practice. By way of example it is desirable, in certain cases, and with the obvious aim of limiting investment costs, to transform the installations operating with burners while keeping as much as possible of the existing elements and in particular the refractory materials constituting The Pelvis. Such a transformation is not possible when it comes to implanting electrodes in the hearth or in the side walls of the furnace.
Les fours dont les électrodes sont immergées offrent des possibilités limitées de réglage des électrodes. S'ils conduisent à des performances tout à fait satisfaisantes pour un certain régime, ils se prêtent moins bien à des modifications fréquentes et/ou substantielles de ce régime de fonctionnement.Ovens with submerged electrodes offer limited possibilities for electrode adjustment. If they lead to completely satisfactory performance for a certain regime, they are less suitable for frequent and / or substantial modifications of this operating regime.
Par ailleurs, même si la technologie des électrodes immergées est maintenant bien maîtrisée et que l'on peut envisager une longévité des électrodes comparable à celles des réfractaires, le risque de la détérioration prématurée d'une ou plusieurs électrodes venant compromettre le bon fonctionnement ne peut être complètement écarté.By the way, even if the electrode technology submerged is now well under control and one can envisage a longevity of the electrodes comparable to those of the refractories, the risk of the premature deterioration of one or more electrodes coming to compromise the good operation cannot be completely ruled out.
Une autre solution notamment décrite dans la demande de brevet français publiée sous le numéro 2 599 734 con¬ siste à plonger des électrodes par la surface libre du bain de matière fondue. Cette technique présente un certain nombre d'avantages. Tout d'abord, elle évite bien entendu les difficultés liées au passage de ces électrodes à tra¬ vers le refractaire, et, également, les problèmes de rem¬ placement d'électrodes usées, d'étanchéité ou encore d'usure des réfractaires, notamment dus à une température élevée qui favorise l'attaque du refractaire et à de puis¬ sants courants de convection qui se développent à son con¬ tact.Another solution, notably described in the French patent application published under the number 2,599,734, consists in immersing electrodes through the free surface of the molten bath. This technique has a number of advantages. First of all, it of course avoids the difficulties associated with the passage of these electrodes through the refractory, and, also, the problems of replacing worn electrodes, sealing or even wear of the refractories, in particular due to a high temperature which favors the attack of the refractory and to powerful convection currents which develop in its contact.
La technique des électrodes plongeantes localise les zones les plus chaudes à la partie supérieure du bain fondu et atténue ainsi ces problèmes.The plunging electrode technique locates the hottest areas at the top of the molten bath and thus alleviates these problems.
Par ailleurs, cette technique permet de modifier la profondeur d'immersion des électrodes et donc le gradient de température. Cela autorise des modifications de tirée du four sans changer la température de la sole et, par consé- quent, la température du verre à la sortie du four.Furthermore, this technique makes it possible to modify the immersion depth of the electrodes and therefore the temperature gradient. This allows changes in the oven temperature without changing the temperature of the hearth and, consequently, the temperature of the glass leaving the oven.
De plus, l'expérience montre que cette technique a un rendement thermique très satisfaisant et conduit à une bonne qualité du matériau fondu.In addition, experience has shown that this technique has a very satisfactory thermal yield and leads to good quality of the molten material.
Ces électrodes plongeantes sont habituellement fixées sur des supports qui surplombent le bassin de fusion à partir des côtés de celui-ci. La demande FR-A-2 599 734 décrit un tel support qui se compose d'un bras qui comporte des canalisations pour la circulation du liquide de re¬ froidissement et un câble électrique pour l'alimentation de l'électrode, et du support d'électrode proprement dit.These plunging electrodes are usually fixed on supports which overhang the melting basin from the sides thereof. Application FR-A-2 599 734 describes such a support which consists of an arm which includes pipes for the circulation of the cooling liquid and an electric cable for the supply of the electrode, and of the support d 'actual electrode.
En régime normal de fonctionnement, une couche de composition déposée à la surface du bain en fusion, qui constitue une protection contre les déperditions thermi¬ ques, évite une trop forte élévation de la température du bras qui surplombe le bain en fusion.In normal operating conditions, a layer of composition deposited on the surface of the molten bath, which constitutes protection against thermal losses, avoids too high a rise in the temperature of the arm that overlooks the molten bath.
Par contre, lors d'une phase de mise en veille, au cours de laquelle la couche protectrice de matières pre¬ mières est, soit d'épaisseur très réduite, soit absente, la température du bras devient très élevée et entraîne une dégradation du système d'alimentation électrique.On the other hand, during a standby phase, during which the protective layer of raw materials is either very reduced in thickness or absent, the temperature of the arm becomes very high and leads to degradation of the system. power supply.
Pour éviter cet inconvénient, une solution habituelle consiste au cours d'une phase de mise en veille à relever les électrodes plongeantes et à maintenir une température suffisante dans le bain par des électrodes immergées le plus souvent placées sur les parois. Cette technique est efficace mais on retrouve les problèmes liés aux électrodes immergées bien que dans le cas présent, elles fonctionnent sous des tensions plus faibles puisqu'elles ne font que maintenir la température du bain déjà fondu. De plus, de telles électrodes immergées nécessitent des coûts d'inves¬ tissements supplémentaires.To avoid this drawback, a usual solution consists in raising the immersing electrodes during a standby phase and in maintaining a sufficient temperature in the bath by submerged electrodes most often placed on the walls. This technique is effective but we find the problems associated with immersed electrodes although in the present case, they operate at lower voltages since they only maintain the temperature of the already molten bath. In addition, such submerged electrodes require additional investment costs.
Une autre solution proposée, notamment décrite dans le brevet US 4,965,812, consiste à utiliser un support d'électrode constitué essentiellement d'un système de re¬ froidissement de type " ater-jacket" conducteur de courant. Le système d'alimentation est alors continuelle¬ ment réfrigéré et donc protégé de l'élévation de tempéra¬ ture qui intervient lors d'une phase de mise en veille. Par contre, ce type d'installation nécessite un dispositif de protection car les supports d'électrodes sont maintenus sous tension en permanence.Another solution proposed, notably described in US Pat. No. 4,965,812, consists in using an electrode support essentially consisting of a cooling system of the "conductor-jacket" type, current conductor. The supply system is then continuously refrigerated and therefore protected from the rise in temperature which occurs during a standby phase. On the other hand, this type of installation requires a protective device because the electrode supports are kept under tension permanently.
Un tel dispositif consiste le plus souvent en un grillage qui interdit l'accès du four aux employés. Cepen- dant certaines mesures qui nécessitent la présence d'un opérateur à proximité du bain et donc des supports d'élec¬ trodes mettent cet opérateur en danger.Such a device most often consists of a wire mesh which prevents employees from accessing the oven. However, certain measures which require the presence of an operator near the bath and therefore of electrode supports put this operator in danger.
L'invention a pour but un dispositif pour la fusion électrique de charge vitrifiable qui agit soit en régime normal de fonctionnement, soit en période de veille sans l'intervention d'électrodes immergées et sans risque pour les opérateurs.The object of the invention is to provide a device for the electrical melting of a vitrifiable charge which acts either under normal operating conditions or during standby without the intervention of submerged electrodes and without risk for operators.
Ce but est atteint selon l'invention par un support d'électrode de fusion immergée à partir de la surface d'un bain de fusion, ledit support comportant un système d'ame¬ née de courant et présentant en surface une protection thermique, ladite surface étant isolée par rapport à la tension du conducteur de courant. Un tel support d'électrode satisfait aux problèmes posés par les techniques antérieures. En effet, il n'existe plus de risque, pour les opérateurs, lié au maintien de la tension d'alimentation de l'électrode. Et, lors d'une mise en veille du four de fusion, l'élévation de température due notamment au rayonnement du bain de verre fondu n'entraîne pas la dégradation du support puisque celui-ci possède une surface isolée thermiquement.This object is achieved according to the invention by a fusion electrode support immersed from the surface of a molten bath, said support comprising a current supply system and having thermal protection on the surface, said surface being isolated from the voltage of the current conductor. Such an electrode support satisfies the problems posed by the prior techniques. In fact, there is no longer any risk for operators linked to maintaining the supply voltage of the electrode. And, during a standby of the melting furnace, the rise in temperature due in particular to the radiation of the molten glass bath does not cause the degradation of the support since it has a thermally insulated surface.
Dans une variante préférée de l'invention, le système d'amenée de courant est un système de refroidissement, du type "water-jacket" conducteur de courant électrique. Ce dispositif est alors entouré d'un isolant électrique, avantageusement en un matériau résistant à des températures très élevées.In a preferred variant of the invention, the current supply system is a cooling system, of the "water-jacket" type conducting electric current. This device is then surrounded by an electrical insulator, advantageously made of a material resistant to very high temperatures.
L'isolant qui est choisi pour résister à des tempéra- tures élevées est avantageusement refroidi par la circula¬ tion d'eau du système de refroidissement conducteur de courant.The insulation which is chosen to withstand high temperatures is advantageously cooled by the circulation of water from the current conducting cooling system.
Lors d'une mise en veille, la température du support devenant très élevée du fait du rayonnement, il est néces- saire de choisir un matériau isolant résistant à ces tem¬ pératures et a priori très onéreux.During standby, the temperature of the support becoming very high due to the radiation, it is necessary to choose an insulating material resistant to these temperatures and a priori very expensive.
L'invention propose avantageusement d'entourer l'isolant électrique d'un second système de refroidissement du type "water-jacket". Il est ainsi possible de choisir un matériau pour l'isolant électrique résistant à des tempé¬ ratures inférieures. De plus, un tel matériau voit géné¬ ralement ses propriétés d'isolation électrique s'améliorer à basse température.The invention advantageously proposes to surround the electrical insulator with a second cooling system of the "water-jacket" type. It is thus possible to choose a material for the electrical insulator resistant to lower temperatures. In addition, such a material generally sees its electrical insulation properties improve at low temperature.
D'autre part, le refroidissement de ce matériau isolant électrique permet d'assurer sa pérennité.On the other hand, the cooling of this electrical insulating material ensures its durability.
Le support d'électrode ainsi proposé comporte donc deux systèmes de refroidissement. Les systèmes de refroi¬ dissement sont avantageusement réalisés par circulation d'eau. Le système interne étant conducteur de courant électrique pour l'alimentation de l'électrode, l'invention prévoit deux circuits distincts de circulation d'eau de façon à ce que l'eau conductrice de courant et circulant dans le système de refroidissement alimentant l'électrode n'apporte pas une tension au niveau du second système de refroidissement qui n'aurait plus alors aucune utilité.The electrode support thus proposed therefore comprises two cooling systems. The cooling systems are advantageously produced by circulating water. The internal system being current conductor electric for supplying the electrode, the invention provides two separate water circulation circuits so that the current-carrying water circulating in the cooling system supplying the electrode does not provide a voltage at the level of the second cooling system which would then no longer have any utility.
Selon un autre mode, préféré, de l'invention, les deux systèmes de refroidissement sont alimentés par un même circuit d'eau, l'eau étant déminéralisée de sorte qu'elle soit non conductrice de courant. Le dispositif d'alimenta¬ tion d'eau extérieur au support d'électrode peut ainsi être limité à un circuit unique.According to another preferred mode of the invention, the two cooling systems are supplied by the same water circuit, the water being demineralized so that it does not conduct current. The device for supplying water outside the electrode support can thus be limited to a single circuit.
D'autres détails et caractéristiques avantageux de l'invention ressortent ci-après de la description des exemples de réalisation décrits en référence aux figures 1, 2 et 3 qui représentent :Other details and advantageous characteristics of the invention emerge below from the description of the exemplary embodiments described with reference to FIGS. 1, 2 and 3 which represent:
- figure 1, une coupe d'une représentation schématique partielle d'un four comportant des électrodes immergées verticalement à partir de la surface, - figure 2, un schéma d'une réalisation selon l'in¬ vention d'une électrode et de son support.- Figure 1, a section of a partial schematic representation of an oven having electrodes immersed vertically from the surface, - Figure 2, a diagram of an embodiment according to the invention of an electrode and its support.
- figure 3, une représentation schématique d'une partie d'un support selon une autre réalisation de l'in¬ vention. Le schéma de la figure 1 représente une partie d'un four de fusion associé à des électrodes plongeantes 1. Le four est constitué par un bassin refractaire composé de la sole 2 et des parois latérales 3. Au-dessus du bassin, la voûte refractaire 4 est suspendue à un bâti métallique 5 partiellement représenté, ledit bâti métallique 5 chevau¬ chant le four.- Figure 3, a schematic representation of part of a support according to another embodiment of the invention. The diagram in FIG. 1 represents part of a melting furnace associated with plunging electrodes 1. The furnace is constituted by a refractory basin composed of the bottom 2 and the side walls 3. Above the basin, the refractory vault 4 is suspended from a metal frame 5 partially shown, said metal frame 5 overlapping the oven.
Il est prévu des parois réfractaires mobiles 6 qui lorsqu'elles sont en position basse, c'est-à-dire en appui sur les parois latérales 3, permettent d'isoler partielle- ment le bain en fusion 7 de l'atmosphère environnante.Movable refractory walls 6 are provided which, when they are in the low position, that is to say resting on the side walls 3, make it possible to partially isolate the molten bath 7 from the surrounding atmosphere.
Seules des ouvertures dans les parois 6 sont prévues pour le passage des supports d'électrodes 8.Only openings in the walls 6 are provided for the passage of the electrode supports 8.
Cette position basse des parois 6 est adoptée lorsque le four est mis en état de veille et qu'il n'est plus nécessaire de l'alimenter en matières premières. Cela per¬ met d'éviter une déperdition thermique trop importante, et le risque de dégrader tout le matériel environnant.This low position of the walls 6 is adopted when the oven is put in standby state and it is no longer necessary to feed it with raw materials. This makes it possible to avoid excessive heat loss, and the risk of degrading all the surrounding material.
En ce qui concerne l'électrode 1 celle-ci est immergée à la surface du bain de fusion 7 sous la couche 9 de ma¬ tières premières à fondre. Cette couche 9 qui recouvre le bain de fusion 7 en mode de fonctionnement normal, isole thermiquement le bassin et permet d'éviter les déperditions thermiques. L'électrode 1 est fixée au support 8 qui comprend le système d'alimentation électrique et un dispositif de re¬ froidissement de l'électrode 1, qui ne sont pas représentés sur cette figure 1.As regards the electrode 1, it is immersed on the surface of the fusion bath 7 under the layer 9 of raw materials to be melted. This layer 9 which covers the fusion bath 7 in normal operating mode, thermally insulates the basin and makes it possible to avoid heat loss. The electrode 1 is fixed to the support 8 which comprises the electrical supply system and a device for cooling the electrode 1, which are not shown in this FIG. 1.
Le support 8 est lui-même raccordé à un mécanisme non représenté qui permet notamment de retirer une électrode 1 du bain par exemple pour un changement ou une réparation.The support 8 is itself connected to a mechanism, not shown, which makes it possible in particular to remove an electrode 1 from the bath, for example for a change or a repair.
Sur la figure 2, l'électrode 1 et son support 8 sont plus précisément représentés et font ressortir les avan¬ tages de l'invention. L'électrode 1, habituellement en molybdène, est fixée par l'intermédiaire d'un élément 10, conducteur de courant, au tube 11 qui constitue le dispositif de refroidissement conducteur de courant électrique. L'élément 10 est une al¬ longe qui se fixe au tube 11 par vissage. A l'autre extré- mité de cette allonge 10, on fixe l'électrode 1. Une telle réalisation permet de pouvoir démonter facilement l'ensem¬ ble allonge 10/électrode 1 car l'endroit du vissage ne trempe jamais dans le bain de fusion. En effet, si le tube 11 était plus long et venait tremper directement dans le bain, il serait possible de fixer directement l'électrode 1 sur celui-ci par exemple par vissage. Par contre, il de¬ viendrait beaucoup plus délicat de procéder au démontage de l'électrode, le point d'attache ayant trempé dans le bain de fusion. Selon notre montage le changement est très fa- cile mais nécesite tout de même de remplacer l'allonge 10 en même temps que l'électrode 1. Cette allonge 10 peut être entourée, au moins partiellement, d'un matériau refractaire suffisamment épais pour éviter un contact direct avec les matières premières ou le bain fondu. D'autre part, l'allonge 10 permet également le passage du liquide de refroidissement jusqu'à l'électrode de façon à ce que celle-ci soit refroidie.In FIG. 2, the electrode 1 and its support 8 are more precisely represented and show the advantages of the invention. The electrode 1, usually made of molybdenum, is fixed by means of a current conducting element 10 to the tube 11 which constitutes the electric current conducting cooling device. The element 10 is an extension which is fixed to the tube 11 by screwing. At the other end of this extension 10, the electrode 1 is fixed. Such an embodiment makes it possible to easily disassemble the set extension 10 / electrode 1 because the place of the screwing never dips in the bath. fusion. Indeed, if the tube 11 was longer and came to soak directly in the bath, it would be possible to directly attach the electrode 1 to it, for example by screwing. On the other hand, it would be much more difficult to disassemble the electrode, the attachment point having soaked in the molten bath. According to our assembly, the change is very easy but still requires replacing the extension 10 at the same time as the electrode 1. This extension 10 can be surrounded, at least partially, by a refractory material sufficiently thick to avoid direct contact with raw materials or the molten bath. On the other hand, the extension 10 also allows the passage of the coolant to the electrode so that it is cooled.
La fixation par vissage est intéressante car elle permet un remplacement rapide. Les remplacements d'élec¬ trodes peuvent être fréquents car ils n'interviennent pas uniquement en cas d'usure mais permettent également de mo¬ difier les électrodes et notamment leur longueur de façon à modifier le niveau d'immersion et donc l'apport énergétique au sein du four. Le tube 11 peut être réalisé en acier de façon à ce qu'il ait de bonnes propriétés de rigidité et de conduction.Screw fixing is interesting because it allows quick replacement. Electrode replacements can be frequent because they do not only intervene in the event of wear but also make it possible to modify the electrodes and in particular their length so as to modify the level of immersion and therefore the energy intake. in the oven. The tube 11 can be made of steel so that it has good rigidity and conduction properties.
Au sein de ce tube 11, est placé un second tube 12, par exemple concentrique. Ce second tube 12 est par exemple fixé en différents points à la surface interne du tube 11. L'association de ces deux tubes 11 et 12 permet une circu¬ lation d'eau et constitue ainsi un dispositif de refroi¬ dissement de type water-jacket. Le système de refroidisse¬ ment étant conçu de façon à refroidir l'électrode 1, le tube 12 traverse l'allonge 10.Within this tube 11 is placed a second tube 12, for example concentric. This second tube 12 is for example fixed at different points to the internal surface of the tube 11. The association of these two tubes 11 and 12 allows water to circulate and thus constitutes a water-type cooling device. jacket. The cooling system being designed so as to cool the electrode 1, the tube 12 crosses the extension 10.
A l'autre extrémité du tube 11 vient se fixer un col¬ lier 13 d'alimentation par exemple en cuivre lui-même placé au sein d'un coffrage isolant 14. Ce collier 13 permet de mettre le tube 11 à la tension désirée, et celui-ci étant conducteur électrique d'alimenter l'électrode 1 sous cette même tension.At the other end of the tube 11 is fixed a supply col¬ 13 for example copper itself placed within an insulating formwork 14. This collar 13 allows to put the tube 11 at the desired voltage, and the latter being electrically conductive, supplying the electrode 1 with this same voltage.
Autour du tube 11 est placé un matériau 15 isolant électrique avantageusement réalisé en un matériau refrac¬ taire du type de l'isolant électrique commercialisé sous la référence MURATHERM 500 M. Le matériau 15 est réalisé sous forme d'un ou plusieurs manchons qui enveloppent et prennent appui sur une partie de la surface externe du tube 11. Ce matériau isolant électrique permet donc une acces¬ sibilité au support d'électrode sans aucun risque d'élec- trocution pour les opérateurs qui doivent approcher du bain de fusion. Le matériau 15 est lui-même entouré d'une enve¬ loppe 16 concentrique dans laquelle circule un liquide de refroidissement tel que de l'eau. Cette enveloppe 16 du type "water-jacket" comprend un manchon 17 interne qui permet la circulation de l'eau.Around the tube 11 is placed an electrical insulating material 15 advantageously made of a refractory material of the type of the electrical insulator sold under the reference MURATHERM 500 M. The material 15 is made in the form of one or more sleeves which envelop and are supported on a part of the external surface of the tube 11. This electrical insulating material therefore allows access to the electrode support without any risk of electrocution for operators who must approach the weld pool. The material 15 is itself surrounded by a concentric envelope 16 in which circulates a cooling liquid such as water. This envelope 16 of the "water-jacket" type comprises an internal sleeve 17 which allows the circulation of water.
Ce second dispositif de refroidissement permet d'une part d'éviter une surchauffe du matériau isolant même si celui-ci est choisi comme pouvant résister à des tempéra- tures assez élevées et s'il est déjà en partie refroidi par le premier système de refroidissement.This second cooling device makes it possible on the one hand to avoid overheating of the insulating material even if it is chosen as being able to withstand fairly high temperatures and if it is already partly cooled by the first cooling system .
D'autre part, il permet d'obtenir une surface externe du support d'électrode 8, qui reste relativement froide et peut permettre une manipulation ou tout au moins l'approche d'un opérateur même lorsque le four est en veilleuse et que le support 8 est chauffé essentiellement par le rayonnement issu du bain de fusion où la couche 9 de matière première est absente.On the other hand, it makes it possible to obtain an external surface of the electrode support 8, which remains relatively cold and can allow manipulation or at least the approach of an operator even when the oven is on standby and the support 8 is heated mainly by radiation from the melt where the layer 9 of raw material is absent.
Les différents éléments cités 11, 12, 15, 16, 17 constituent des tubes, par exemple, concentriques, placés les uns autour des autres.The various elements cited 11, 12, 15, 16, 17 constitute tubes, for example, concentric, placed around one another.
Dans le cas de la figure 3, un dispositif de refroi¬ dissement du type "water-jacket", conducteur de courant, constitué de deux tubes concentriques 18, 19 est entouré d'un ou plusieurs manchons 20 en un matériau isolant élec¬ trique et présentant une bonne isolation thermique et une bonne tenue en température.In the case of FIG. 3, a cooling device of the "water-jacket" type, current conductor, consisting of two concentric tubes 18, 19 is surrounded by one or more sleeves 20 made of an electrically insulating material and having good thermal insulation and good temperature resistance.
La protection thermique de la surface du support d'électrode est alors obtenue d'une part, par la nature même du manchon 20 et d'autre part, par la présence du dis¬ positif de refroidissement qui permet de refroidir ce man¬ chon 20.Thermal protection of the surface of the electrode support is then obtained on the one hand, by the very nature of the sleeve 20 and on the other hand, by the presence of the cooling device which makes it possible to cool this sleeve 20 .
La protection électrique est apportée par le manchon 20 qui enveloppe le tube 19 conducteur de courant. Les différentes canalisations permettant l'arrivée et le départ de l'eau de refroidissement ne sont pas repré¬ sentées sur les figures.The electrical protection is provided by the sleeve 20 which envelops the current conducting tube 19. The various pipes allowing the arrival and departure of the cooling water are not shown in the figures.
L'eau utilisée pour le refroidissement est avanta¬ geusement une eau déminéralisée, ce qui permet d'utiliser les mêmes circuits pour les deux systèmes de refroidisse¬ ment sans risque de conduction du courant vers le système de refroidissement externe, qui est par ailleurs relié à la terre.The water used for cooling is advantageously demineralized water, which makes it possible to use the same circuits for the two cooling systems without the risk of conduction of the current to the external cooling system, which is also connected To the earth.
Les flèches non numérotées indiquent les différents circuits suivis par le liquide de refroidissement.The unnumbered arrows indicate the different circuits followed by the coolant.
L'électrode associée à son support ainsi décrite selon l'invention permet d'une part une utilisation sans risque en mode de fonctionnement normal puisque aucun dispositif accessible n'est sous tension et d'autre part une utilisa¬ tion sans risque de dégradation du support lorsque le four est mis en veilleuse.The electrode associated with its support thus described according to the invention allows on the one hand a risk-free use in normal operating mode since no accessible device is energized and on the other hand a use without risk of degradation of the support when the oven is put on hold.
Le dispositif composé de l'électrode et de son support selon l'invention permet donc de conserver les différents avantages, liés à la fusion électrique par électrode im¬ mergée à partir de la surface du bain de fusion, qui ont été énumérés précédemment. Il s'agit par exemple, des bons rendements thermiques, de la bonne qualité du matériau fondu malgré des modifications de tirée, de l'augmentation de durée de vie du four car les réfractaires sont moins attaqués ou bien parce qu'il est aisé de changer une élec¬ trode.The device composed of the electrode and of its support according to the invention therefore makes it possible to conserve the various advantages, linked to the electrical fusion by electrode immersed from the surface of the fusion bath, which have been listed previously. These are, for example, good thermal yields, good quality of the molten material despite changes in draft, an increase in the life of the furnace because the refractories are less attacked or because it is easy to change an electrode.
De plus, le dispositif selon l'invention permet d'éviter la présence d'électrodes totalement immergées pour les périodes de veilleuse ou bien la présence à plein temps d'un système de protection évitant la présence des opéra¬ teurs à proximité des éléments continuellement sous ten¬ sion. In addition, the device according to the invention makes it possible to avoid the presence of fully submerged electrodes for the pilot light periods or else the full-time presence of a protection system avoiding the presence of operators near the elements continuously. under tension.

Claims

REVENDICATIONS
1. Support (8) d'électrode (1) de fusion immergée à partir de la surface d'un bain de fusion, ledit support (8) comportant un système d'amenée de courant et un dispositif de refroidissement, caractérisé en ce que le support pré¬ sente en surface une protection thermique et en ce que la¬ dite surface est isolée par rapport à la tension du con¬ ducteur de courant.1. Support (8) for a fusion electrode (1) immersed from the surface of a fusion bath, said support (8) comprising a current supply system and a cooling device, characterized in that the support has a thermal protection on the surface and in that the said surface is isolated from the voltage of the current conductor.
2. Support d'électrode selon la revendication 1, ca- ractérisé en ce que le système d'amenée de courant est un système de refroidissement de type "water-jacket" (11, 12, 18, 19), conducteur de courant et en ce que ce système de refroidissement est entouré d'un isolant électrique (15, 20). 2. An electrode holder according to claim 1, characterized in that the current supply system is a cooling system of the "water-jacket" type (11, 12, 18, 19), current conductor and in that this cooling system is surrounded by an electrical insulator (15, 20).
3. Support d'électrode selon la revendication 2, ca¬ ractérisé en ce que l'isolant électrique (15, 20) est en un matériau résistant à des températures élevées.3. An electrode support according to claim 2, ca¬ characterized in that the electrical insulator (15, 20) is made of a material resistant to high temperatures.
4. Support d'électrode selon l'une des revendications 2 ou 3, caractérisé en ce que l'isolant électrique (15) est entouré d'un système de refroidissement du type "water-j¬ acket" (16, 17).4. An electrode support according to one of claims 2 or 3, characterized in that the electrical insulator (15) is surrounded by a cooling system of the "water-j¬ acket" type (16, 17).
5. Support d'électrode selon la revendication 4, ca¬ ractérisé en ce que le fluide du système de refroidissement (16, 17) entourant l'isolant électrique est conduit par un circuit différent du circuit de refroidissement (11, 12) conducteur de courant.5. An electrode support according to claim 4, ca¬ characterized in that the fluid of the cooling system (16, 17) surrounding the electrical insulator is conducted by a circuit different from the cooling circuit (11, 12) conductor of current.
6. Support d'électrode selon la revendication 4, ca¬ ractérisé en ce que le fluide du système de refroidissement (16, 17) entourant l'isolant électrique est conduit par le circuit qui alimente le système de refroidissement (11, 12) conducteur de courant et en ce que le fluide est de l'eau déminéralisée. 6. electrode holder according to claim 4, ca¬ characterized in that the fluid of the cooling system (16, 17) surrounding the electrical insulator is conducted by the circuit which supplies the cooling system (11, 12) conductive current and in that the fluid is demineralized water.
EP94928439A 1993-09-30 1994-09-27 Electric melting device Expired - Lifetime EP0671116B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9311679 1993-09-30
FR9311679 1993-09-30
PCT/FR1994/001124 WO1995009518A1 (en) 1993-09-30 1994-09-27 Electric melting device

Publications (2)

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EP0671116A1 true EP0671116A1 (en) 1995-09-13
EP0671116B1 EP0671116B1 (en) 2003-07-02

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JP (1) JP3655308B2 (en)
KR (1) KR100391193B1 (en)
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BR (1) BR9405619A (en)
CA (1) CA2150236A1 (en)
DE (1) DE69432892T2 (en)
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FR2741227A1 (en) * 1995-11-14 1997-05-16 Verrerie & Cristallerie Long life electrode esp. for glass melting furnace
US6377604B1 (en) 2000-11-09 2002-04-23 Dixie Arc, Inc. Current-conducting arm for an electric arc furnace
JP2010238639A (en) * 2009-03-31 2010-10-21 Frontier Engineering Co Ltd Refrigerant tube, electrode body, and continuous energization heating device
US8743926B2 (en) * 2010-08-10 2014-06-03 H.C. Starck Inc. Liquid cooled glass metal electrode
CN104136849A (en) * 2012-02-22 2014-11-05 克利尔赛恩燃烧公司 Cooled electrode and burner system including a cooled electrode
FR3142185A1 (en) 2022-11-18 2024-05-24 Saint-Gobain Isover Electric glass furnace

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US2599179A (en) * 1949-07-14 1952-06-03 Kellogg M W Co Furnace electrode
US3327040A (en) * 1963-08-07 1967-06-20 Exxon Research Engineering Co Electrode installation
US4477911A (en) * 1982-12-02 1984-10-16 Westinghouse Electric Corp. Integral heat pipe-electrode
EP0135473A1 (en) * 1983-08-13 1985-03-27 Arc Technologies Systems, Ltd. Electrode assembly for arc furnaces
EP0202352A1 (en) * 1985-05-22 1986-11-26 C. CONRADTY NÜRNBERG GmbH & Co. KG Plasma torch
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CN1054960C (en) 2000-07-26
ES2202328T3 (en) 2004-04-01
DE69432892T2 (en) 2004-05-27
NO313170B1 (en) 2002-08-19
KR960702724A (en) 1996-04-27
DE69432892D1 (en) 2003-08-07
NO952020L (en) 1995-05-22
JP3655308B2 (en) 2005-06-02
NO952020D0 (en) 1995-05-22
EP0671116B1 (en) 2003-07-02
WO1995009518A1 (en) 1995-04-06
US5596598A (en) 1997-01-21
JPH08504055A (en) 1996-04-30
FI952603A0 (en) 1995-05-29
BR9405619A (en) 1999-09-08
DK0671116T3 (en) 2003-10-27
CN1115199A (en) 1996-01-17
FI952603A (en) 1995-05-29
ZA947131B (en) 1995-05-08
KR100391193B1 (en) 2003-12-01
CA2150236A1 (en) 1995-04-06

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