WO2001059184A1 - Device for short circuiting electrolytic cell - Google Patents

Device for short circuiting electrolytic cell Download PDF

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Publication number
WO2001059184A1
WO2001059184A1 PCT/FR2001/000375 FR0100375W WO0159184A1 WO 2001059184 A1 WO2001059184 A1 WO 2001059184A1 FR 0100375 W FR0100375 W FR 0100375W WO 0159184 A1 WO0159184 A1 WO 0159184A1
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Prior art keywords
cell
value
short
voltage
electrolysis
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Application number
PCT/FR2001/000375
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French (fr)
Inventor
Michel Pillet
Original Assignee
Amc S.A.R.L
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Publication date
Application filed by Amc S.A.R.L filed Critical Amc S.A.R.L
Priority to EP01907741A priority Critical patent/EP1257689A1/en
Priority to AU2001235638A priority patent/AU2001235638A1/en
Publication of WO2001059184A1 publication Critical patent/WO2001059184A1/en

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/60—Constructional parts of cells
    • C25B9/65—Means for supplying current; Electrode connections; Electric inter-cell connections
    • C25B9/66—Electric inter-cell connections including jumper switches

Definitions

  • the present invention relates to devices for short-circuiting devices consuming electricity connected in series in a high intensity electrical circuit and more particularly a device for short-circuiting an electrolysis cell.
  • High intensity electrical circuits are used in various applications such as electrolysis rooms, test stations or electric ovens. These circuits generally carry intensities ranging from 10 to 400 kiloamperes (A).
  • A kiloamperes
  • the cell which must be stopped is generally short-circuited, which makes it possible to keep the other cells in operation.
  • the short-circuiting operation consists in coming to connect a short-circuiting circuit or short-circuiter, to the cathode of the previous cell (i.e. to the current output electrode) and to the anode of the next cell ( ie at the current input electrode) After closing the short-circuit switch, the high-intensity electric current supplying the cells flows into the latter, the cell is then no longer fed
  • the traditional solution is to inject neutralizing products into the cell, during the short-circuiting. It may for example be bisulfite. This operation obliges operators to intervene in dangerous conditions by discharging several hundred liters of products into the cell through an orifice.
  • the object of the invention is to overcome these drawbacks by providing a short-circuiting device which makes it possible to cancel the reverse current which is created in a cell. electrolysis when it is short-circuited and which therefore makes it possible to avoid degradation of the electrodes, while maintaining polarization in the cell.
  • the invention relates to a device for short-circuiting an electrolysis cell, connected in series to at least one other electrolysis cell in an electrolysis room, intended to be connected to the terminals of the electrolysis cell of so that it is no longer supplied.
  • This device comprises at least one variable resistor whose value is defined so that the voltage across the terminals of the cell has a value at least equal to a predetermined minimum value making it possible to prevent the formation of a reverse current to the inside the cell, this reverse current being due to an electromotive force produced inside the cell, when the latter is no longer supplied.
  • FIG. 1 represents the assembly of an electrolysis room composed of several electrolysis cells connected in series.
  • FIG. 2 represents the evolution of the current circulating in the electrolysis cell as a function of the voltage exerted across its terminals.
  • FIG. 3 represents the evolution of the reverse voltage occurring in the electrolysis cell, when the latter is short-circuited, as a function of time.
  • FIG. 4 represents the short-circuiting device according to the invention connected to the terminals of the electrolysis cell.
  • An electrolysis room is generally made up of electrolysis cells 10, the number of which generally varies between 20 and 200, connected in series via an electrical circuit 12.
  • the current which supplies the electrolysis cells is a direct current obtained thanks to a rectifier 14. This rectifier transforms the medium voltage alternating current which it receives via a connection 16, in a low voltage direct current enabling the electrolysis cells to be supplied.
  • a high intensity direct current of constant and adjustable value is applied to the electrolysis cells.
  • the behavior of the electrolysis cells implies that its resistance varies as a function of the voltage U which is applied across the terminals of these cells.
  • the current I supplying the electrolysis cells varies as a function of the voltage. Indeed, when the value of the voltage is between 0 and an X value, the current does not pass through the electrolysis cells.
  • the intensity of the current flowing in the cell increases to reach a maximum value Z, corresponding to the value of the current supplied by the rectifier, when the voltage has a value Y. For voltage values greater than Y, the intensity of the current flowing in the cell remains at its maximum value.
  • the operation of the electrolysis cell is therefore optimal when the voltage has a value equal to Y, that is to say when the value of the current which passes through the cell is equal to that of the current supplied by the rectifier.
  • the X and Y voltage values are different depending on the type of electrolysis cell used.
  • the voltage value X at the terminals of the cell allowing current to flow in the cell is for example 2.35 volts (V).
  • the value Y of voltage at the terminals of the cell enabling the totality of the current supplied by the rectifier flowing in the cell to be obtained, is 3.5 V.
  • the voltage at the terminals of the cell is less than 2.35 V , the cell behaves like a capacity which discharges This phenomenon is however transitory.
  • this value can be for example 1.8 V
  • a short-circuiting voltage, or bias voltage at the terminals of the electrolysis cell, the value of which is at least U max, ie 1.8 V in the example above.
  • this voltage must not have a value greater than 2.35 V in order not to trigger electrolysis.
  • FIG. 4 represents the short-circuiting device according to the invention, in a preferred embodiment.
  • a short-circuiting device composed of a variable resistor 20, a detector 22 and a controller 24 is connected to the terminals of this cell.
  • the detector 22 regularly measures the voltage across the terminals of cell 18, a voltage which is equal to RI, R being the variable resistance of the short-circuiting circuit and I the intensity of the current supplied by the rectifier.
  • the short-circuiting voltage must have a minimum value of 1.8 V and a maximum value of 2.35 V
  • the value of the voltage detected by the detector 22 is supplied to the controller 24.
  • the latter acts on the variable resistor 20 and varies its value so that the voltage at the terminals of the cell is always between U max and X, it is at say 1.8 volts and 2.35 volts in the example above.
  • Another advantage of being able to modify the value of the resistance at the terminals of the electrolysis cell by means of the short-circuiting device resides in the case where the intensity of the current supplied to the electrolysis room by the rectifier is deliberately modified by technical staff. Indeed, the intensity of the high intensity current supplying an electrolysis room can be fixed at a value between 70 and 140 kiloamperes (kA), as required. Thanks to the short-circuiting device according to the invention, the voltage at the terminals of the short-circuited electrolysis cells will always be sufficient to avoid the formation of reverse current and therefore the degradation of the electrodes regardless of the intensity of the current supplying the electrolysis room.
  • the variable resistance of the short-circuiting device can take various forms.
  • the resistance can be adjusted continuously as a function of variations in intensity.
  • the variable resistor can also consist of several resistors connected in parallel. According to a particular embodiment, these resistors are connected or disconnected so as to vary the value of the overall resistance. Indeed, knowing that the overall resistance decreases when the number of resistors connected in parallel increases and that it increases when their number decreases, it is easy to vary the overall resistance to adapt its value to that of the intensity in order to obtain a constant voltage across the electrolysis cell.
  • the short-circuiting technique is only used temporarily. In fact, in the hours following the short-circuiting, the tank is generally emptied of its electrolyte, in order to undergo the maintenance operation. There is no longer any risk of degradation of the electrodes.
  • the device according to the invention therefore makes it possible to isolate one or more electrolysis cells, without immobilizing the entire electrolysis room, which would have a very high cost. Compared to conventional short-circuiting devices, it makes it possible to maintain a voltage at the terminals of the isolated cells which is large enough to prevent the production of a reverse current which would degrade the electrodes. Thus, cell maintenance is much more flexible since there is no longer any risk of degradation over time. In addition, this system makes it possible, thanks to its variable resistance, to maintain a predetermined constant voltage value, despite voluntary or involuntary variations in intensity.
  • this device makes it possible to overcome the constraints created by the use of dangerous materials such as asbestos still necessary to protect the electrodes of the electrolysis cells.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Abstract

The invention concerns a device for short-circuiting an electrolytic cell (18), connected in series to at least another electrolytic cell in an electrolysis room, designed to be connected to the terminals of the electrolytic cells such that it is no longer powered. Said device comprises a variable resistance (20) whereof the value is defined by a controller (24) on the basis of the voltage value at the terminals of the cell detected by a sensor (22) so that said voltage should have a value at least equal to a predetermined minimum value for preventing the formation of a backward current inside the cell, said backward current being due to an electromotive force produced inside the cell when the latter is no longer powered.

Description

Dispositxf de court-circuitage de cellule d' électrolyse Electrolysis cell short-circuiting device
Domaine techniqueTechnical area
La présente invention concerne les dispositifs pour court-circuiter des appareils consommateurs d'électricité connectés en série dans un circuit électrique haute intensité et plus particulièrement un dispositif pour court-circuiter une cellule d'électrolyse.The present invention relates to devices for short-circuiting devices consuming electricity connected in series in a high intensity electrical circuit and more particularly a device for short-circuiting an electrolysis cell.
Etat de la techniqueState of the art
Les circuits électriques à haute intensité sont utilisés dans différentes applications telles que les salles d'électrolyse, les stations d'essais ou les fours électriques Ces circuits véhiculent généralement des intensités allant de 10 à 400 kiloampères ( A) . Dans le cas de cellules d'électrolyse connectées en série, il est parfois nécessaire d'isoler une cellule afin d'effectuer des opérations de maintenance par exemple. Afin de ne pas immobiliser complètement la salle d'électrolyse et donc l'intégralité des cellules pendant la durée de maintenance, on procède généralement au court-circuitage de la cellule qui doit être arrêtée, ce qui permet de maintenir les autres cellules en fonctionnement .High intensity electrical circuits are used in various applications such as electrolysis rooms, test stations or electric ovens. These circuits generally carry intensities ranging from 10 to 400 kiloamperes (A). In the case of electrolysis cells connected in series, it is sometimes necessary to isolate a cell in order to carry out maintenance operations for example. In order not to completely immobilize the electrolysis room and therefore all of the cells during the maintenance period, the cell which must be stopped is generally short-circuited, which makes it possible to keep the other cells in operation.
L'opération de court-circuitage consiste à venir connecter un circuit de court-circuitage ou court-circuiteur, à la cathode de la cellule précédente (c'est à dire à l'électrode de sortie du courant) et à l'anode de la cellule suivante (c'est à dire à l'électrode d'entrée du courant) Après fermeture de l'interrupteur du court-circuiteur , le courant électrique haute intensité alimentant les cellules passe dans ce dernier, la cellule n'est alors plus alimentéeThe short-circuiting operation consists in coming to connect a short-circuiting circuit or short-circuiter, to the cathode of the previous cell (i.e. to the current output electrode) and to the anode of the next cell ( ie at the current input electrode) After closing the short-circuit switch, the high-intensity electric current supplying the cells flows into the latter, the cell is then no longer fed
Cependant, lors du court-circuitage des cellules d'électrolyse, il apparaît un courant inverse dans la cellule, allant de la cathode à l'anode, s 'ajoutant au courant dévié dans le court -circuiteur . La valeur de ce courant inverse est directement proportionnelle à la force électromotrice de la batterie que constitue alors la cellule d'électrolyse et inversement proportionnelle à la résistance du circuit de court-circuitage .However, during the short-circuiting of the electrolysis cells, there appears a reverse current in the cell, going from the cathode to the anode, adding to the current deflected in the short-circuiter. The value of this reverse current is directly proportional to the electromotive force of the battery which then constitutes the electrolysis cell and inversely proportional to the resistance of the short-circuit.
Ce courant inverse produit une dégradation de la cathode par la migration de composés métalliques dans le revêtement de cathode .This reverse current produces degradation of the cathode by the migration of metal compounds into the cathode coating.
En plus du problème de la dégradation de la cathode, dans le cas des cellules d'électrolyse pour la production de chlore et de soude, cette dégradation entraîne un risque important d'explosion. En effet, la séparation hydrogène / chlore n'est plus effective. Il apparaît alors un risque de production simultanée d'hydrogène et de chlore sur la même électrode, avec une possibilité d'explosion majeure.In addition to the problem of degradation of the cathode, in the case of electrolysis cells for the production of chlorine and soda, this degradation involves a significant risk of explosion. Indeed, the hydrogen / chlorine separation is no longer effective. There is then a risk of simultaneous production of hydrogen and chlorine on the same electrode, with the possibility of a major explosion.
Afin de pallier cet inconvénient, les cathodes des cellules d'électrolyse ont été traditionnellement recouvertes d'un revêtement en amiante. Cependant, pour des raisons de santé publique, l'utilisation de l'amiante a été interdite. Le remplacement nécessaire de l'amiante a conduit les fabricants de cellules d'électrolyse à mettre au point des matériaux de substitution, tel que le Polyramix®. Toutefois, ces matériaux sont très sensibles aux migrations métalliques et donc aux courants inverses. La dégradation du revêtement de substitution par les courants inverses est rapide.In order to overcome this drawback, the cathodes of the electrolysis cells have traditionally been covered with an asbestos coating. However, for public health reasons, the use of asbestos has been banned. The necessary replacement of asbestos has led manufacturers of electrolysis cells to develop alternative materials, such as Polyramix®. However, these materials are very sensitive to metallic migrations and therefore to reverse currents. The degradation of the substitution coating by reverse currents is rapid.
La solution traditionnelle est d'injecter dans la cellule, pendant le court-circuitage, des produits neutralisants. Il peut s'agir par exemple de bisulfite. Cette opération oblige des opérateurs à intervenir dans des conditions dangereuses en déversant dans la cellule par un orifice, plusieurs centaines de litres de produits.The traditional solution is to inject neutralizing products into the cell, during the short-circuiting. It may for example be bisulfite. This operation obliges operators to intervene in dangerous conditions by discharging several hundred liters of products into the cell through an orifice.
Aucune solution n'étant vraiment efficace, l'utilisation de l'amiante a été prolongée, le temps de trouver de nouvelles solutions. Cependant, les problèmes de santé publique et d'environnement subsistent.No solution being really effective, the use of asbestos was prolonged, the time to find new solutions. However, public health and environmental problems remain.
Exposé de l'invention Le but de 1 ' invention est de pallier ces inconvénients en fournissant un dispositif de court-circuitage qui permet d'annuler le courant inverse qui se crée dans une cellule d'électrolyse lorsque celle-ci est court-circuitée et qui permet donc d'éviter la dégradation des électrodes, tout en maintenant une polarisation dans la cellule.Description of the invention The object of the invention is to overcome these drawbacks by providing a short-circuiting device which makes it possible to cancel the reverse current which is created in a cell. electrolysis when it is short-circuited and which therefore makes it possible to avoid degradation of the electrodes, while maintaining polarization in the cell.
L'invention concerne un dispositif de court-circuitage d'une cellule d'électrolyse, connectée en série à au moins une autre cellule d'électrolyse dans une salle d'électrolyse, destiné à être connecté aux bornes de la cellule d'électrolyse de manière à ce que celle-ci ne soit plus alimentée. Ce dispositif comprend au moins une résistance variable dont la valeur est définie de manière à ce que la tension aux bornes de la cellule ait une valeur au moins égale à une valeur minimale prédéterminée permettant d'empêcher la formation d'un courant inverse à l'intérieur de la cellule, ce courant inverse étant dû à une force électromotrice produite à l'intérieur de la cellule, lorsque celle-ci n'est plus alimentée .The invention relates to a device for short-circuiting an electrolysis cell, connected in series to at least one other electrolysis cell in an electrolysis room, intended to be connected to the terminals of the electrolysis cell of so that it is no longer supplied. This device comprises at least one variable resistor whose value is defined so that the voltage across the terminals of the cell has a value at least equal to a predetermined minimum value making it possible to prevent the formation of a reverse current to the inside the cell, this reverse current being due to an electromotive force produced inside the cell, when the latter is no longer supplied.
Description brève des figuresBrief description of the figures
Les buts, objets et caractéristiques de l'invention ressortiront mieux à la lecture de la description qui suit faite en référence aux dessins joints dans lesquels :The aims, objects and characteristics of the invention will emerge more clearly on reading the following description made with reference to the accompanying drawings in which:
La figure 1 représente le montage d'une salle d'électrolyse composée de plusieurs cellules d'électrolyse connectée en série. La figure 2 représente l'évolution du courant circulant dans la cellule d'électrolyse en fonction de la tension exercée aux bornes de celle-ci.FIG. 1 represents the assembly of an electrolysis room composed of several electrolysis cells connected in series. FIG. 2 represents the evolution of the current circulating in the electrolysis cell as a function of the voltage exerted across its terminals.
La figure 3 représente l'évolution de la tension inverse se produisant dans la cellule d'électrolyse, lorsque celle-ci est court-circuitée, en fonction du temps.FIG. 3 represents the evolution of the reverse voltage occurring in the electrolysis cell, when the latter is short-circuited, as a function of time.
La figure 4 représente le dispositif de court-circuitage selon 1 ' invention connecté aux bornes de la cellule d' électrolyse .FIG. 4 represents the short-circuiting device according to the invention connected to the terminals of the electrolysis cell.
Description détaillée de 1 ' inventionDetailed description of the invention
Une salle d'électrolyse est généralement constituée de cellules d'électrolyse 10, dont le nombre varie généralement entre 20 et 200, connectées en série par l'intermédiaire d'un circuit électrique 12. Le courant qui alimente les cellules d'électrolyse est un courant continu obtenu grâce à un redresseur 14. Ce redresseur transforme le courant alternatif moyenne tension qu'il reçoit par une connexion 16, en un courant continu basse tension permettant d'alimenter les cellules d'électrolyse.An electrolysis room is generally made up of electrolysis cells 10, the number of which generally varies between 20 and 200, connected in series via an electrical circuit 12. The current which supplies the electrolysis cells is a direct current obtained thanks to a rectifier 14. This rectifier transforms the medium voltage alternating current which it receives via a connection 16, in a low voltage direct current enabling the electrolysis cells to be supplied.
On applique aux cellules d'électrolyse, un courant continu haute intensité de valeur constante et réglable. Toutefois, on constate que le comportement des cellules d'électrolyse implique que la résistance de celle-ci varie en fonction de la tension U qu'on applique aux bornes de ces cellules. Selon la figure 2, on constate donc que le courant I alimentant les cellules d'électrolyse varie en fonction de la tension. En effet, lorsque la valeur de la tension est comprise entre 0 et une valeur X, le courant ne passe pas dans les cellules d'électrolyse. Lorsque la tension est comprise entre une valeur X et une valeur Y, l'intensité du courant circulant dans la cellule augmente pour atteindre une valeur maximale Z, correspondant à la valeur du courant fourni par le redresseur, lorsque la tension a une valeur Y. Pour des valeurs de tension supérieures à Y, l'intensité du courant circulant dans la cellule demeure à sa valeur maximale.A high intensity direct current of constant and adjustable value is applied to the electrolysis cells. However, it can be seen that the behavior of the electrolysis cells implies that its resistance varies as a function of the voltage U which is applied across the terminals of these cells. According to FIG. 2, it can therefore be seen that the current I supplying the electrolysis cells varies as a function of the voltage. Indeed, when the value of the voltage is between 0 and an X value, the current does not pass through the electrolysis cells. When the voltage is between a value X and a value Y, the intensity of the current flowing in the cell increases to reach a maximum value Z, corresponding to the value of the current supplied by the rectifier, when the voltage has a value Y. For voltage values greater than Y, the intensity of the current flowing in the cell remains at its maximum value.
Le fonctionnement de la cellule d'électrolyse est donc optimal lorsque la tension a une valeur égale à Y, c'est à dire lorsque la valeur du courant qui passe dans la cellule est égale à celle du courant fourni par le redresseur. Les valeurs de tension X et Y sont différentes selon le type de cellule d'électrolyse utilisée. Dans le cas d'une cellule d'électrolyse chlore / soude, la valeur X de tension aux bornes de la cellule permettant de faire circuler du courant dans la cellule est par exemple 2,35 volts (V) . La valeur Y de tension aux bornes de la cellule permettant d'avoir la totalité du courant fourni par le redresseur qui circule dans la cellule, est de 3,5 V. Lorsque la tension aux bornes de la cellule est inférieure à 2,35 V, la cellule se comporte comme une capacité qui se décharge Ce phénomène est cependant transitoire .The operation of the electrolysis cell is therefore optimal when the voltage has a value equal to Y, that is to say when the value of the current which passes through the cell is equal to that of the current supplied by the rectifier. The X and Y voltage values are different depending on the type of electrolysis cell used. In the case of a chlorine / sodium hydroxide electrolysis cell, the voltage value X at the terminals of the cell allowing current to flow in the cell is for example 2.35 volts (V). The value Y of voltage at the terminals of the cell enabling the totality of the current supplied by the rectifier flowing in the cell to be obtained, is 3.5 V. When the voltage at the terminals of the cell is less than 2.35 V , the cell behaves like a capacity which discharges This phenomenon is however transitory.
Comme mentionné précédemment, lorsqu'on court-circuite une cellule d'électrolyse pour effectuer, par exemple, une opération de maintenance et qu'on ne maintient pas une tension suffisante aux bornes de cette cellule, un courant inverse apparaît. Ce courant dépend d'une force électromotrice qui se crée dans la cellule. L'évolution de cette force électromotrice au cours du temps est représentée par la courbe illustrée sur la figure 3. Au vu de cette courbe, on constate que la force électromotrice est transitoire. La valeur maximale Umax est obtenue au bout d'un temps t0 égal à quelques secondes ou millisecondes selon le type de cellules d'électrolyse utilisées. Elle décroît rapidement pour tendre vers une valeur très faible en quelques heures. La valeur maximale de la force électromotrice varie en fonction du type de cellules d'électrolyse. Pour une cellule d'électrolyse chlore / soude, cette valeur peut être par exemple de 1,8 V Afin d'empêcher l'apparition de cette force électromotrice, il est nécessaire d'appliquer une tension de court-circuitage, ou tension de polarisation, aux bornes de la cellule d'électrolyse dont la valeur est au minimum de Umax soit 1,8 V dans l'exemple ci-dessus. De même, cette tension ne doit pas avoir une valeur supérieure à 2,35 V afin de ne pas déclencher 1 ' électrolyse .As mentioned previously, when an electrolysis cell is short-circuited to carry out, for example, a maintenance operation and a sufficient voltage is not maintained at the terminals of this cell, a reverse current appears. This current depends on an electromotive force which is created in the cell. The evolution of this electromotive force over time is represented by the curve illustrated in FIG. 3. In view of this curve, it can be seen that the electromotive force is transient. The maximum value U max is obtained after a time t 0 equal to a few seconds or milliseconds depending on the type of electrolysis cells used. It decreases rapidly, reaching a very low value in a few hours. The maximum value of the electromotive force varies according to the type of electrolysis cells. For a chlorine / sodium hydroxide electrolysis cell, this value can be for example 1.8 V In order to prevent the appearance of this electromotive force, it is necessary to apply a short-circuiting voltage, or bias voltage , at the terminals of the electrolysis cell, the value of which is at least U max, ie 1.8 V in the example above. Likewise, this voltage must not have a value greater than 2.35 V in order not to trigger electrolysis.
La figure 4 représente le dispositif de court-circuitage selon l'invention, dans un mode de réalisation préféré. Lorsqu'on veut isoler une cellule d'électrolyse 18, on branche aux bornes de cette cellule, un dispositif de court-circuitage composé d'une résistance variable 20, d'un détecteur 22 et d'un contrôleur 24 Le détecteur 22 mesure régulièrement la tension aux bornes de la cellule 18, tension qui est égale à RI, R étant la résistance variable du circuit de court - circuitage et I l'intensité du courant fourni par le redresseur. Dans le cas d'une cellule d'électrolyse chlore / soude, la tension de court-circuitage doit avoir une valeur minimale de 1,8 V et une valeur maximale de 2,35 V La valeur de tension détectée par le détecteur 22 est fournie au contrôleur 24. Ce dernier agit sur la résistance variable 20 et fait varier sa valeur de telle sorte que la tension aux bornes de la cellule soit toujours comprise entre Umax et X, c'est à dire 1,8 volts et 2,35 volts dans l'exemple ci-dessus.FIG. 4 represents the short-circuiting device according to the invention, in a preferred embodiment. When an electrolysis cell 18 is to be isolated, a short-circuiting device composed of a variable resistor 20, a detector 22 and a controller 24 is connected to the terminals of this cell. The detector 22 regularly measures the voltage across the terminals of cell 18, a voltage which is equal to RI, R being the variable resistance of the short-circuiting circuit and I the intensity of the current supplied by the rectifier. In the case of a chlorine / sodium hydroxide electrolysis cell, the short-circuiting voltage must have a minimum value of 1.8 V and a maximum value of 2.35 V The value of the voltage detected by the detector 22 is supplied to the controller 24. The latter acts on the variable resistor 20 and varies its value so that the voltage at the terminals of the cell is always between U max and X, it is at say 1.8 volts and 2.35 volts in the example above.
Un autre intérêt de pouvoir modifier la valeur de la résistance aux bornes de la cellule d'électrolyse grâce au dispositif de court-circuitage réside dans le cas où l'intensité du courant fourni à la salle d'électrolyse par le redresseur est volontairement modifiée par le personnel technique. En effet, l'intensité du courant haute intensité alimentant une salle d'électrolyse peut être fixée à une valeur comprise entre 70 et 140 kiloampères (kA) , selon les besoins. Grâce au dispositif de court-circuitage selon l'invention, la tension aux bornes des cellules d'électrolyse court-circuitées sera toujours suffisante pour éviter la formation de courant inverse et donc la dégradation des électrodes quelle que soit l'intensité du courant alimentant la salle d'électrolyse. La résistance variable du dispositif de court-circuitage peut se présenter sous différentes formes. Elle peut tout d'abord être constituée par un rhéostat. Selon ce mode de réalisation, la résistance peut être réglée de façon continue en fonction des variations de l'intensité. La résistance variable peut également être constituée par plusieurs résistances connectées en parallèle. Selon un mode de réalisation particulier, ces résistances sont connectées ou déconnectées de façon à faire varier la valeur de la résistance globale. En effet, sachant que la résistance globale diminue lorsque le nombre de résistances connectées en parallèle augmente et qu'elle augmente quand leur nombre diminue, il est facile de faire varier la résistance globale pour adapter sa valeur à celle de l'intensité afin d'obtenir une tension constante aux bornes de la cellule d'électrolyse. La technique de court-circuitage n'est employée que de façon temporaire. En effet, dans les heures qui suivent le court-circuitage, la cuve est généralement vidée de son électrolyte, afin de subir l'opération de maintenance. Il n'y alors plus aucun risque de dégradation des électrodes.Another advantage of being able to modify the value of the resistance at the terminals of the electrolysis cell by means of the short-circuiting device resides in the case where the intensity of the current supplied to the electrolysis room by the rectifier is deliberately modified by technical staff. Indeed, the intensity of the high intensity current supplying an electrolysis room can be fixed at a value between 70 and 140 kiloamperes (kA), as required. Thanks to the short-circuiting device according to the invention, the voltage at the terminals of the short-circuited electrolysis cells will always be sufficient to avoid the formation of reverse current and therefore the degradation of the electrodes regardless of the intensity of the current supplying the electrolysis room. The variable resistance of the short-circuiting device can take various forms. It can first of all be constituted by a rheostat. According to this embodiment, the resistance can be adjusted continuously as a function of variations in intensity. The variable resistor can also consist of several resistors connected in parallel. According to a particular embodiment, these resistors are connected or disconnected so as to vary the value of the overall resistance. Indeed, knowing that the overall resistance decreases when the number of resistors connected in parallel increases and that it increases when their number decreases, it is easy to vary the overall resistance to adapt its value to that of the intensity in order to obtain a constant voltage across the electrolysis cell. The short-circuiting technique is only used temporarily. In fact, in the hours following the short-circuiting, the tank is generally emptied of its electrolyte, in order to undergo the maintenance operation. There is no longer any risk of degradation of the electrodes.
Le dispositif selon l'invention permet donc d'isoler une ou plusieurs cellules d'électrolyse, sans immobiliser la salle d'électrolyse en entier, ce qui aurait un coût très important. Par rapport aux dispositifs de court-circuitage classiques, il permet de maintenir une tension aux bornes des cellules isolées suffisamment importante pour empêcher la production d'un courant inverse qui dégraderait les électrodes. Ainsi, la maintenance des cellules est beaucoup plus souple puisqu'il n'existe plus de risque de dégradation dans le temps. De plus, ce système permet, grâce à sa résistance variable, de maintenir une valeur de tension constante prédéterminée, malgré les variations d'intensité volontaires ou involontaires .The device according to the invention therefore makes it possible to isolate one or more electrolysis cells, without immobilizing the entire electrolysis room, which would have a very high cost. Compared to conventional short-circuiting devices, it makes it possible to maintain a voltage at the terminals of the isolated cells which is large enough to prevent the production of a reverse current which would degrade the electrodes. Thus, cell maintenance is much more flexible since there is no longer any risk of degradation over time. In addition, this system makes it possible, thanks to its variable resistance, to maintain a predetermined constant voltage value, despite voluntary or involuntary variations in intensity.
Enfin, ce dispositif permet de s'affranchir des contraintes créées par l'utilisation de matériaux dangereux tels que l'amiante encore nécessaire pour protéger les électrodes des cellules d'électrolyse. Finally, this device makes it possible to overcome the constraints created by the use of dangerous materials such as asbestos still necessary to protect the electrodes of the electrolysis cells.

Claims

REVENDICATIONS
1. Dispositif de court-circuitage d'une cellule d'électrolyse (18) connectée en série à au moins une autre cellule d'électrolyse dans une salle d'électrolyse, destine a être connecté aux bornes de ladite cellule d'électrolyse, et comprenant au moins une résistance variable (20) dont la valeur est définie de manière à ce que la tension aux bornes de ladite cellule ait une valeur au moins égale à une valeur minimale prédéterminée permettant d'empêcher la formation d'un courant inverse à l'intérieur de ladite cellule, ledit courant inverse étant dû à une force électromotrice produite a l'intérieur de ladite cellule, lorsque celle-ci n'est plus alimentée ; ledit dispositif étant caractérisé en ce qu'il comprend également un détecteur (22) connecté aux bornes de la cellule d'électrolyse pour détecter la valeur de la tension aux bornes de ladite cellule d'électrolyse et un contrôleur (24) pour modifier la valeur de ladite résistance variable en réponse à la valeur de la tension fournie par ledit détecteur, afin de maintenir la valeur de cette tension au moins égale à ladite valeur de tension minimale prédéterminée.1. Device for short-circuiting an electrolysis cell (18) connected in series to at least one other electrolysis cell in an electrolysis room, intended to be connected to the terminals of said electrolysis cell, and comprising at least one variable resistor (20) whose value is defined so that the voltage across said cell has a value at least equal to a predetermined minimum value making it possible to prevent the formation of a reverse current at l inside said cell, said reverse current being due to an electromotive force produced inside said cell, when the latter is no longer supplied; said device being characterized in that it also comprises a detector (22) connected to the terminals of the electrolysis cell for detecting the value of the voltage at the terminals of said electrolysis cell and a controller (24) for modifying the value of said variable resistance in response to the value of the voltage supplied by said detector, in order to maintain the value of this voltage at least equal to said predetermined minimum voltage value.
2. Dispositif de court-circuitage selon la revendication 1, dans lequel ladite résistance variable (20) est constituée par un rhéostat .2. A short-circuiting device according to claim 1, in which said variable resistor (20) is constituted by a rheostat.
3. Dispositif de court-circuitage selon la revendication 1 ou 2, dans lequel ladite résistance variable (20) est constituée par plusieurs résistances connectées en parallèle.3. Short-circuiting device according to claim 1 or 2, wherein said variable resistor (20) consists of several resistors connected in parallel.
4. Dispositif de court-circuitage selon l'une des revendications précédentes, dans lequel la valeur de ladite résistance variable (20) est déterminée de manière à ce que la tension aux bornes de la cellule d'électrolyse (18) soit inférieure à une valeur maximale prédéterminée à partir de laquelle 1 ' électrolyse se déclenche. 4. Short-circuiting device according to one of the preceding claims, in which the value of said variable resistance (20) is determined so that the voltage across the terminals of the electrolysis cell (18) is less than a predetermined maximum value from which the electrolysis starts.
5. Dispositif de court-circuitage selon la revendication 4, dans lequel la valeur maximale prédéterminée de la tension aux bornes de ladite cellule (18) est de 2,35 volts.5. A short-circuiting device according to claim 4, in which the predetermined maximum value of the voltage across said cell (18) is 2.35 volts.
6. Dispositif de court-circuitage selon l'une des revendications précédentes, dans lequel la valeur minimale prédéterminée de la tension aux bornes de ladite cellule (18) est de 1,8 volts.6. Short-circuiting device according to one of the preceding claims, wherein the predetermined minimum value of the voltage across said cell (18) is 1.8 volts.
7. Dispositif de court-circuitage selon l'une des revendications précédentes, dans lequel le courant fourni aux cellules d'électrolyse a une valeur constante et réglable.7. Short-circuiting device according to one of the preceding claims, in which the current supplied to the electrolysis cells has a constant and adjustable value.
8. Dispositif de court-circuitage selon la revendication 7, dans lequel l'intensité dudit courant stable et réglable est comprise entre 70 et 140 kiloampères. 8. A short-circuiting device according to claim 7, in which the intensity of said stable and adjustable current is between 70 and 140 kiloamperes.
PCT/FR2001/000375 2000-02-11 2001-02-09 Device for short circuiting electrolytic cell WO2001059184A1 (en)

Priority Applications (2)

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EP01907741A EP1257689A1 (en) 2000-02-11 2001-02-09 Device for short circuiting electrolytic cell
AU2001235638A AU2001235638A1 (en) 2000-02-11 2001-02-09 Device for short circuiting electrolytic cell

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0001925A FR2805098B1 (en) 2000-02-11 2000-02-11 ELECTROLYSIS CELL SHORT-CIRCUIT DEVICE
FR00/01925 2000-02-11

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Publication number Priority date Publication date Assignee Title
CN114555867A (en) * 2019-09-17 2022-05-27 Amc公司 Electrolysis tank power supply circuit comprising a short-circuit device and a circuit breaker

Citations (3)

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Publication number Priority date Publication date Assignee Title
US4169775A (en) * 1978-07-31 1979-10-02 Olin Corporation Protection of the low hydrogen overvoltage catalytic coatings
US4421614A (en) * 1980-12-03 1983-12-20 Chlorine Engineers Corp. Ltd. Method of bypassing electric current of electrolytic cells
US4589966A (en) * 1985-10-03 1986-05-20 Olin Corporation Membrane cell jumper switch

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
US4169775A (en) * 1978-07-31 1979-10-02 Olin Corporation Protection of the low hydrogen overvoltage catalytic coatings
US4421614A (en) * 1980-12-03 1983-12-20 Chlorine Engineers Corp. Ltd. Method of bypassing electric current of electrolytic cells
US4589966A (en) * 1985-10-03 1986-05-20 Olin Corporation Membrane cell jumper switch

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114555867A (en) * 2019-09-17 2022-05-27 Amc公司 Electrolysis tank power supply circuit comprising a short-circuit device and a circuit breaker

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AU2001235638A1 (en) 2001-08-20
FR2805098A1 (en) 2001-08-17
EP1257689A1 (en) 2002-11-20
FR2805098B1 (en) 2003-10-17

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