EP0750450A1 - Plasma torch having an essentially axisymmetrical general structure - Google Patents

Plasma torch having an essentially axisymmetrical general structure Download PDF

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Publication number
EP0750450A1
EP0750450A1 EP96450016A EP96450016A EP0750450A1 EP 0750450 A1 EP0750450 A1 EP 0750450A1 EP 96450016 A EP96450016 A EP 96450016A EP 96450016 A EP96450016 A EP 96450016A EP 0750450 A1 EP0750450 A1 EP 0750450A1
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EP
European Patent Office
Prior art keywords
torch
envelope
electrode
external
rod
Prior art date
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Granted
Application number
EP96450016A
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German (de)
French (fr)
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EP0750450B1 (en
Inventor
Daniel Loubet
Jean-Marie Jacques Spariat
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EADS Launch Vehicles SA
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Airbus Group SAS
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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00Generating plasma; Handling plasma
    • H05H1/24Generating plasma
    • H05H1/26Plasma torches
    • H05H1/32Plasma torches using an arc
    • H05H1/34Details, e.g. electrodes, nozzles
    • H05H1/40Details, e.g. electrodes, nozzles using applied magnetic fields, e.g. for focusing or rotating the arc
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00Generating plasma; Handling plasma
    • H05H1/24Generating plasma
    • H05H1/26Plasma torches
    • H05H1/28Cooling arrangements
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00Generating plasma; Handling plasma
    • H05H1/24Generating plasma
    • H05H1/26Plasma torches
    • H05H1/32Plasma torches using an arc
    • H05H1/34Details, e.g. electrodes, nozzles
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00Generating plasma; Handling plasma
    • H05H1/24Generating plasma
    • H05H1/26Plasma torches
    • H05H1/32Plasma torches using an arc
    • H05H1/34Details, e.g. electrodes, nozzles
    • H05H1/3431Coaxial cylindrical electrodes
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00Generating plasma; Handling plasma
    • H05H1/24Generating plasma
    • H05H1/26Plasma torches
    • H05H1/32Plasma torches using an arc
    • H05H1/34Details, e.g. electrodes, nozzles
    • H05H1/3489Means for contact starting

Definitions

  • the present invention relates to plasma torches, in particular, but not exclusively, to non-transferred arc torches.
  • a plasma torch of this type comprises two coaxial tubular electrodes, in extension of one another and each arranged in a support surrounding it. Means are provided for producing the initiation of an electric arc between the two electrodes, as well as means for injecting a plasma gas, such as air, into a chamber between the electrodes. In each electrode support are also provided means for cooling the electrodes.
  • the plasma torch is provided with means for moving the attachment foot of the electric arc on the upstream electrode, consisting of an electromagnetic coil surrounding the support of said upstream electrode.
  • the invention applies more particularly to a plasma torch, the ignition of the electric arc of which is produced by a temporary short circuit established between the electrodes by means of the momentary movement of the upstream electrode. in contact with the downstream electrode, using a jack device, called a choke jack.
  • This embodiment relates to a compact plasma torch of reduced size intended in particular to be mounted in furnaces for vitrification of waste.
  • This torch generally comprises a tubular casing in which said upstream and downstream electrodes are housed, as well as the plasma gas injection system, the electrode cooling system, the device for displacement of the upstream electrode for start-up purposes and the arc foot displacement field coil.
  • Said casing is connected, at its proximal end, to a connector block, ensuring fluid and electrical connections with the exterior of the torch, which is fixed to the wall of an oven by a clamping system at the height of the junction between said tubular casing and the rear connector part, the tubular casing part, commonly called a naked torch, being engaged in the furnace.
  • the cooling of the electrodes is not optimal and the complexity of the cooling circuit results in significant pressure drops, requiring the use of high operating pressures, for example of the order of 12 bars.
  • this high pressure sounds on the pressure necessary to control the cylinder for moving the upstream electrode, at start-up, since during the retraction of the upstream electrode, following start-up, said cylinder must overcome the thrust downstream exerted by the coolant on the upstream electrode. This is how commonly a pressure of the order of 160 bars is necessary for actuating said cylinder.
  • this type of torch does not offer good accessibility to the wearing parts of the torch (upstream and downstream electrodes) as well as to adjustments, for example example of position and stroke of the choke cylinder. lt is almost necessary to completely disassemble the torch.
  • the present invention aims to overcome the various drawbacks mentioned above of this type of plasma torch and more generally of plasma torches of the non-transferred arc type or of the transferred arc type, whatever the starting system used, by proposing a torch with a simplified general architecture, almost entirely axi-symmetrical and therefore facilitating both the production of the torch and its maintenance.
  • Such an arrangement makes it possible to reduce the number of parts of the torch and above all to give it the desired length, in relation to that of the successive envelopes, the naked torch receiving, whatever its length, standard internal elements, that is to say the electrode (s), the field coil, the plasma gas injection system, the separators of the cooling circuit and the starting means.
  • a starting device comprising a so-called choke cylinder acting on the upstream electrode to bring it momentarily closer to the downstream electrode
  • said choke cylinder is disposed outside the body of said external structure and comprises a rod which passes right through the cylinder, is connected to the upstream electrode by a connecting rod extending in the body of the external structure and to the interior of said internal envelope and has a section allowing said incoming flow of cooling fluid to exert on said cylinder rod a back pressure tending to counterbalance the pressure of said fluid on the upstream electrode, while the outer end of the cylinder rod is provided with means for adjusting the stroke of this rod.
  • the structure according to the invention also makes it possible to substantially simplify the cooling circuit which has much lower pressure losses than those of the known torch cooling circuit, thus making it possible, with equal cooling capacity, to significantly reduce the pressure required for the fluid. , for example from 12 to 6 bars, with the advantageous indirect consequence, in the case of non-transferred arc torches and starting choke cylinder, of a reduction in proportion to the pressure necessary to actuate the choke cylinder.
  • FIG. 1 a plasma torch according to the invention, usable for example in a waste vitrification oven, consisting of two essential parts, namely a front part called naked torch 1 of generally cylindrical shape and a rear part called connection 2 formed by an external structure ensuring the fluidic and electrical connections of the torch with the outside and allowing the transport and the handling of the torch.
  • a front part called naked torch 1 of generally cylindrical shape
  • connection 2 formed by an external structure ensuring the fluidic and electrical connections of the torch with the outside and allowing the transport and the handling of the torch.
  • the naked torch 1 has a distal end or nose 3, of slightly reduced diameter, while the structure 2, called external because it remains outside the oven when the naked torch 1 is introduced into the latter by an appropriate opening made in the wall, consists of a tubular body 4 coaxial with the naked torch 1, provided at its ends with two flanges 5 in the form of a diamond and carrying at their ends journals 6 of lift, in the known manner, from the torch to a handling spreader (not shown).
  • the naked torch 1 comprises a supporting structure (FIG. 2) formed of three coaxial envelopes partially overlapping, namely a metallic external envelope 7, an intermediate metallic envelope 8 and an internal envelope 9 made of material electrically insulating.
  • the casing 7 is cylindrical, extends over the entire length of the naked torch 1 and is connected at its proximal end to the tubular body 4 of the external structure 2 by an annular connecting piece 10.
  • the envelope 8 is also cylindrical, extends substantially over the length of the envelope 7 of the largest diameter, as well as inside the body 4 to which it is tightly fixed, by a threaded crown 11, approximately in the central area.
  • annular space 12 communicating with an annular space 13 defined between the body 4 and the envelope 8.
  • the space 13 communicates by a passage, represented at 14 in FIG. 1 and symbolized by the same reference numeral in FIG. 2, with a pipe (not shown) for the return of the cooling fluid, in this case water. demineralized, from the hot part of the torch.
  • the intermediate casing 8 serves as a support for an annular separator 15 of the cooling circuit of the downstream electrode 16 which is a conventional annular electrode whose distal end is fixed to the nose of the torch.
  • the distal end of the intermediate envelope 8 also serves, as will be seen below, for fixing the plasma gas injection system 17 and the distal end of the upstream electrode 18 which is also an annular electrode conventional coaxial, like the downstream electrode 16, to the axis 19 of the torch.
  • the casing 9 is a cylindrical tube which extends substantially between the proximal end of the upstream electrode 18 and a place on the body 4 slightly behind the part 11 while being fixed to said body 4 by a threaded crown 20.
  • the tube 9 thus defines, with the intermediate envelope 8, an annular space 21 communicating, on the structure side 2, with an annular space 22 internal to the body 4 and communicating, by a passage represented at 23 in FIG. 1 and only symbolized by the same reference. digital in FIG. 2, with a pipe (not shown) for supplying plasma-generating fluid, in this case air.
  • the distal end of the internal envelope 9 is in sealed contact with the end of an annular separator 24 of the cooling circuit of the upstream electrode 18.
  • the distal end of the separator 24 is connected to the distal end of the intermediate casing 8 by means of an annular connecting piece 26 of electrically insulating material, support for the plasma gas injection system 17.
  • This injection system (see also FIG. 4) comprises an annular perforated grid 27, made of electrically insulating material, arranged in the interval between electrodes 16,18 and on the external face of which is provided a homogenization chamber 28, produced in room 26.
  • the chamber 28 communicates through holes 29 passing through the part 26 with the space 21.
  • the holes 29, six in number (cf. FIG. 4 on which a complete section of the part 26 is shown in perspective) are regularly distributed and their axes 30 do not intersect the axis of the part 26 in order to create a vortex effect when the air enters through the holes 29 in the homogenization chamber 28.
  • the part 26 is pierced with a series of holes 31 with axes parallel to the axis of the part 26, that is to say the axis 19 of the torch, in order to ensure the continuity of the cooling circuit, successively of the upstream electrode 18 and the field coil 25, then of the downstream electrode 16.
  • an abutment pin 35 said to be ignition.
  • the upstream electrode 18 is fixed to the end of a metal rod 36, for example made of copper, itself fixed to the end of a transmission axis 37 of electrically insulating material, of large section and the end of which is slidably mounted in a bore 38 of a flange 39 attached to the external end of the body 4.
  • a metal rod 36 for example made of copper, itself fixed to the end of a transmission axis 37 of electrically insulating material, of large section and the end of which is slidably mounted in a bore 38 of a flange 39 attached to the external end of the body 4.
  • Said sliding end of the axis 37 is integral with a rod 40 extending inside a hollow rod 41 of a choke cylinder 42 fixed to the flange 39, outside the body 4.
  • the hollow rod 41 passes completely through the jack 42 and is secured, at its outer end, to the rod 40 by means of a pair 43 of nut and lock nut. At its other end, the rod 41 is in abutment against a washer 44 integral with the rod 40, by means of a damping spring 45.
  • a screw stop 46 adjustable in position on the jack rod 41, allows, by modifying its distance from the end of the jack 42, to adjust the stroke of the jack rod.
  • the rod 36 carries a metal bush 47 mounted to slide and integral with the support of the field coil 25 to the winding of which said bush 47 is connected.
  • a socket 49 for electrical connection to the coil 25 is fixed to the end of an electrical connection rod 50, parallel to the axis 19, extending opposite the internal tubular casing 9 and passing through the body 4 to be attached to the flange 39, the material of which is of course not electrically conductive.
  • the rod 50 is connected to an electrical connection terminal 51 (plus pole), the minus pole being constituted by the connection terminal 52, connected to the metal body 4.
  • the electrical circuit for supplying the electrodes therefore comprises the rod 50, the part 49, the field coil 25 which is mounted in series, the part 47, the rod 36, the upstream electrode 18, the downstream electrode 16, the torch nose, outer casing 7 and body 4.
  • the internal envelope 9 is in contact by its internal face with a space 53 delimited by the body 4 and in the axis of which extend the rods 36 and 37.
  • This space 53 communicates by a passage, represented at 54 in FIG. 1 and only symbolized by the same reference numeral in FIG. 2, capable of being connected to a pipe (not shown) for the arrival of cooling water from the torch.
  • the cooling water circuit thus consists of the space 53, which communicates through holes 48a formed in the part 47 with an annular space 48b formed between the end piece 48c of the upstream electrode 18 and an annular deflector 48d forming venturi, integral with the coil 25 and channeling water to the space between the upstream electrode 18 and the field coil 25.
  • the water passes into the space between the coil 25 and the tube 33, into space 32 (via perforations 55 to the proximal end of the tube 33), in the passages 31, in the space 34, then in the space 12 and finally in the space 13.
  • This circuit thus completely and directly licks the electrically conductive parts 50,49,47, the upstream tip 48c, then the external face of the upstream electrode 18, the two faces of the field coil 25, the injection system 17, the external face of the downstream electrode 16 and finally the external face of the naked torch 1, over its entire length.
  • Such a circuit is relatively simple in comparison with those of traditional torches. It optimally cools the hot parts of the torch, as well as all of its outer casing 7, which allows the torch to face without damaging the temperatures prevailing in a vitrification oven and which can greatly exceed 1600 ° C, or even reach 2000 ° C.
  • the pressure drops of the cooling circuit are reduced compared to those of conventional circuits, which makes it possible to lower the operating pressure of the source of cooling water for the torch.
  • the pressure of the cooling water has been reduced from 12 to 6 bars.
  • the particular mounting of the choke cylinder 42, completely outside of the body 4, with the connecting rod 37 with a large section immersed in the cooling water at the inlet of the torch allows, on the one hand, adjustment of the cylinder stroke and easy maintenance and, on the other hand, to control the cylinder 42 with a fluid at reduced pressure compared to the usual starters cylinders.
  • the upstream electrode 18 is brought, by the jack 42, into contact with the stop pin 35 at start-up.
  • the jack 42 can only be supplied with a pressure which is largely half as low. If the pressure necessary for the choke cylinder can even be lowered sufficiently, for example up to 7 bars, one can consider using to actuate the cylinder cooling water from the torch.
  • the concentric structure of the envelopes 7,8,9 allows easy access to the interior of the torch, starting by depositing the external envelope 7, for example to replace the electrodes or any other part or for any operation maintenance or repair.
  • connection rod 50 is simply plugged in, by means of the connecting piece. 49, on connection and / or centering pins 56 integral with the coil 25 and the separator 24.
  • distal end of the casing 9 is not integral with the separator 24, which allows the extraction of the casing 9 alone from the torch, to access the fixing (11) of the intermediate envelope 8.
  • the invention is obviously not limited to the embodiment shown and described above, but on the contrary covers all its variants, in particular with regard to the arrangement of the plasma gas injector system 17, the arrangement of the field coil 25, the means for controlling the displacement of the upstream electrode at start-up, or even the arrangement of the external structure 2.
  • the invention applies generally to all types of plasma torches with non-transferred arc, whatever the starting system, as well as to all types of plasma torches with transferred arc.

Abstract

A plasma torch with an essentially axisymmetrical general structure incorporates: (a) a naked torch part (1) in which are arranged one or two tubular electrodes cooled by an appropriate cooling circuit, a field coil (25) and some means (17) for injecting a plasma gas, together with some means (42) for assuring the starting of the torch; and (b) an external structure (2) in which are regrouped the fluid and electrical linkages external to the torch. The naked part (1) of the torch has a carrier structure formed from three coaxial envelopes: namely, an external metal envelope, an intermediate metal envelope defining with the external envelope the return circuit for the cooling fluid, and an internal envelope defining with the intermediate envelope the inlet circuit for the plasma gas to the injection system and channelling through its inner face the inlet flow of the cooling fluid to the electrodes and the field coil.

Description

La présente invention a trait aux torches à plasma, en particulier, mais non exclusivement, aux torches à arc non-transféré.The present invention relates to plasma torches, in particular, but not exclusively, to non-transferred arc torches.

D'une manière générale, une torche à plasma de ce type comprend deux électrodes tubulaires coaxiales, en prolongement l'une de l'autre et agencées chacune dans un support l'entourant. Des moyens sont prévus pour produire l'amorçage d'un arc électrique entre les deux électrodes, ainsi que des moyens pour injecter un gaz plasmagène, tel que de l'air, dans une chambre, entre les électrodes. Dans chaque support d'électrode sont également prévus des moyens de refroidissement des électrodes.In general, a plasma torch of this type comprises two coaxial tubular electrodes, in extension of one another and each arranged in a support surrounding it. Means are provided for producing the initiation of an electric arc between the two electrodes, as well as means for injecting a plasma gas, such as air, into a chamber between the electrodes. In each electrode support are also provided means for cooling the electrodes.

En outre, avantageusement, la torche à plasma est munie de moyens pour déplacer le pied d'accrochage de l'arc électrique sur l'électrode amont, constitués d'une bobine électromagnétique entourant le support de ladite électrode amont.In addition, advantageously, the plasma torch is provided with means for moving the attachment foot of the electric arc on the upstream electrode, consisting of an electromagnetic coil surrounding the support of said upstream electrode.

Plus précisément encore, l'invention s'applique plus particulièrement à une torche à plasma dont l'amorçage de l'arc électrique est réalisé par un court-circuit temporaire établi entre les électrodes par l'intermédiaire du déplacement momentané de l'électrode amont au contact de l'électrode aval, à l'aide d'un dispositif à vérin, dit vérin starter.Even more precisely, the invention applies more particularly to a plasma torch, the ignition of the electric arc of which is produced by a temporary short circuit established between the electrodes by means of the momentary movement of the upstream electrode. in contact with the downstream electrode, using a jack device, called a choke jack.

Pour illustrer plus précisément ce type de torche à plasma auquel se réfère plus particulièrement la présente invention, on pourra se reporter utilement au mode de réalisation de la figure 4 du document FR-A-2.654.294.To illustrate more precisely this type of plasma torch to which the present invention more particularly refers, reference may usefully be made to the embodiment of FIG. 4 of document FR-A-2,654,294.

Ce mode de réalisation se rapporte à une torche à plasma compacte et d'encombrement réduit destinée notamment à être montée dans des fours de vitrification de déchets.This embodiment relates to a compact plasma torch of reduced size intended in particular to be mounted in furnaces for vitrification of waste.

Cette torche comporte, d'une manière générale, une enveloppe tubulaire dans laquelle sont logées lesdites électrodes amont et aval, ainsi que le système d'injection de gaz plasmagène, le système de refroidissement des électrodes, le dispositif à vérin de déplacement de l'électrode amont à des fins de démarrage et la bobine de champ de déplacement du pied d'arc.This torch generally comprises a tubular casing in which said upstream and downstream electrodes are housed, as well as the plasma gas injection system, the electrode cooling system, the device for displacement of the upstream electrode for start-up purposes and the arc foot displacement field coil.

Ladite enveloppe est reliée, à son extrémité proximale, à un bloc de connectique, assurant les liaisons fluidiques et électriques avec l'extérieur de la torche, laquelle est fixée sur la paroi d'un four par un système de bridage à hauteur de la jonction entre ladite enveloppe tubulaire et la partie connectique arrière, la partie enveloppe tubulaire, communément appelée torche nue, étant engagée dans le four.Said casing is connected, at its proximal end, to a connector block, ensuring fluid and electrical connections with the exterior of the torch, which is fixed to the wall of an oven by a clamping system at the height of the junction between said tubular casing and the rear connector part, the tubular casing part, commonly called a naked torch, being engaged in the furnace.

La conception de ce type de torche à plasma est complexe et ne permet pas la réalisation facile de torches nues de différentes longueurs susceptibles de répondre à des besoins industriels spécifiques.The design of this type of plasma torch is complex and does not allow the easy production of naked torches of different lengths capable of meeting specific industrial needs.

De plus, le refroidissement des électrodes n'est pas optimal et la complexité du circuit de refroidissement entraîne des pertes de charge importantes obligeant de recourir à des pressions de service élevées, par exemple de l'ordre de 12 bars.In addition, the cooling of the electrodes is not optimal and the complexity of the cooling circuit results in significant pressure drops, requiring the use of high operating pressures, for example of the order of 12 bars.

En outre, cette pression élevée retentit sur la pression nécessaire à la commande du vérin de déplacement de l'électrode amont, au démarrage, puisqu'au cours de la rétraction de l'électrode amont, consécutive au démarrage, ledit vérin doit surmonter la poussée vers l'aval exercée par le fluide de refroidissement sur l'électrode amont. C'est ainsi que communément une pression de l'ordre de 160 bars est nécessaire à l'actionnement dudit vérin.In addition, this high pressure sounds on the pressure necessary to control the cylinder for moving the upstream electrode, at start-up, since during the retraction of the upstream electrode, following start-up, said cylinder must overcome the thrust downstream exerted by the coolant on the upstream electrode. This is how commonly a pressure of the order of 160 bars is necessary for actuating said cylinder.

Enfin, ce type de torche n'offre pas une bonne accessibilité aux pièces d'usure de la torche (électrodes amont et aval) ainsi qu'aux réglages, par exemple de position et de course du vérin starter. ll faut en effet pratiquement démonter complètement la torche.Finally, this type of torch does not offer good accessibility to the wearing parts of the torch (upstream and downstream electrodes) as well as to adjustments, for example example of position and stroke of the choke cylinder. lt is almost necessary to completely disassemble the torch.

La présente invention vise à palier les divers inconvénients rappelés ci-dessus de ce type de torche à plasma et plus généralement de torches à plasma du type à arc non-transféré ou du type à arc transféré, quel que soit le système de démarrage utilisé, en proposant une torche à architecture générale simplifiée, presqu'entièrement axi-symétrique et facilitant donc à la fois la réalisation de la torche et sa maintenance.The present invention aims to overcome the various drawbacks mentioned above of this type of plasma torch and more generally of plasma torches of the non-transferred arc type or of the transferred arc type, whatever the starting system used, by proposing a torch with a simplified general architecture, almost entirely axi-symmetrical and therefore facilitating both the production of the torch and its maintenance.

A cet effet, l'invention a pour objet une torche à plasma à structure générale sensiblement axi-symétrique, du type comprenant :

  • une partie tubulaire dite torche nue dans laquelle sont disposées une électrode unique dite amont ou une paire d'électrodes coaxiales dites amont et aval, les électrodes étant tubulaires et refroidies par un circuit de refroidissement approprié, une bobine dite de champ de déplacement du pied d'arc et des moyens pour injecter un gaz plasmagène en aval de l'électrode amont ou entre l'électrode amont et l'électrode aval, des moyens étant en outre prévus pour assurer le démarrage de la torche, et
  • une structure dite externe, solidaire de la torche nue à son extrémité proximale et dans laquelle sont regroupées les liaisons fluidiques et électriques avec l'extérieur de la torche,
caractérisée en ce que ladite torche nue comporte une structure porteuse formée de trois enveloppes coaxiales se recouvrant au moins partiellement, solidaires de ladite structure externe, à savoir une enveloppe externe métallique, une enveloppe intermédiaire métallique définissant avec l'enveloppe externe le circuit de retour du fluide de refroidissement de la ou des électrodes et de la bobine, et une enveloppe interne définissant avec l'enveloppe intermédiaire le circuit d'admission du gaz plasmagène auxdits moyens d'injection et canalisant par sa face interne le flux entrant du fluide de refroidissement en direction de l'électrode amont, de la bobine de champ et éventuellement de l'électrode aval.To this end, the subject of the invention is a plasma torch with a generally axi-symmetrical general structure, of the type comprising:
  • a tubular part called naked torch in which are disposed a single electrode called upstream or a pair of coaxial electrodes called upstream and downstream, the electrodes being tubular and cooled by an appropriate cooling circuit, a coil called field of displacement of the foot d arc and means for injecting a plasma gas downstream of the upstream electrode or between the upstream electrode and the downstream electrode, means being furthermore provided for ensuring the starting of the torch, and
  • a so-called external structure, integral with the naked torch at its proximal end and in which the fluid and electrical connections with the outside of the torch are grouped,
characterized in that said naked torch comprises a support structure formed of three coaxial envelopes overlapping at least partially, integral with said external structure, namely a metallic external envelope, a metallic intermediate envelope defining with the external envelope the return circuit of the coolant for the electrode (s) and the coil, and an internal envelope defining with the intermediate envelope the circuit for admitting the plasma gas to said injection means and channeling by its internal face the incoming flow of the cooling fluid direction of the upstream electrode, the field coil and possibly the downstream electrode.

Un tel agencement permet de réduire le nombre de pièces de la torche et surtout de donner à celle-ci la longueur que l'on veut, en rapport avec celle des enveloppes successives, la torche nue recevant, quelle que soit sa longueur, des éléments internes standards, c'est-à-dire la ou les électrodes, la bobine de champ, le système d'injection de gaz plasmagène, les séparateurs du circuit de refroidissement et les moyens de démarrage.Such an arrangement makes it possible to reduce the number of parts of the torch and above all to give it the desired length, in relation to that of the successive envelopes, the naked torch receiving, whatever its length, standard internal elements, that is to say the electrode (s), the field coil, the plasma gas injection system, the separators of the cooling circuit and the starting means.

Suivant une application particulière de l'invention à une torche à plasma à arc non-transféré munie d'un dispositif de démarrage comportant un vérin dit starter agissant sur l'électrode amont pour la rapprocher momentanément de l'électrode aval, ledit vérin starter est disposé à l'extérieur du corps de ladite structure externe et comporte une tige qui traverse de part en part le vérin, est reliée à l'électrode amont par une tige de liaison s'étendant dans le corps de la structure externe et à l'intérieur de ladite enveloppe interne et présente une section permettant audit flux entrant du fluide de refroidissement d'exercer sur ladite tige de vérin une contre-pression tendant à contrebalancer la pression dudit fluide sur l'électrode amont, cependant que l'extrémité externe de la tige du vérin est munie de moyens de réglage de la course de cette tige.According to a particular application of the invention to a plasma torch with non-transferred arc provided with a starting device comprising a so-called choke cylinder acting on the upstream electrode to bring it momentarily closer to the downstream electrode, said choke cylinder is disposed outside the body of said external structure and comprises a rod which passes right through the cylinder, is connected to the upstream electrode by a connecting rod extending in the body of the external structure and to the interior of said internal envelope and has a section allowing said incoming flow of cooling fluid to exert on said cylinder rod a back pressure tending to counterbalance the pressure of said fluid on the upstream electrode, while the outer end of the cylinder rod is provided with means for adjusting the stroke of this rod.

La structure selon l'invention permet également de simplifier substantiellement le circuit de refroidissement qui présente des pertes en charges bien moindres que celles du circuit de refroidissement des torches connues, permettant ainsi, à capacité de refroidissement égale, de réduire sensiblement la pression nécessaire au fluide, par exemple de 12 à 6 bars, avec la conséquence indirecte avantageuse, dans le cas de torches à arc non-transféré et à vérin starter de démarrage, d'une réduction en proportion de la pression nécessaire pour actionner le vérin starter.The structure according to the invention also makes it possible to substantially simplify the cooling circuit which has much lower pressure losses than those of the known torch cooling circuit, thus making it possible, with equal cooling capacity, to significantly reduce the pressure required for the fluid. , for example from 12 to 6 bars, with the advantageous indirect consequence, in the case of non-transferred arc torches and starting choke cylinder, of a reduction in proportion to the pressure necessary to actuate the choke cylinder.

D'autres caractéristiques et avantages ressortiront de la description qui va suivre d'un mode de réalisation d'une torche à plasma selon l'invention, description donnée à titre d'exemple uniquement et en regard des dessins annexés sur lesquels :

  • Figure 1 est une vue en perspective schématisée d'une torche à plasma conforme à l'invention ;
  • Figure 2, fractionnée respectivement en 2a,2b et 2c à des fins de lisibilité, est une demi-vue en coupe axiale de la torche de la figure 1 ;
  • Figure 3 est une demi-vue partielle en section sagittale de la partie de la torche à hauteur de la liaison électrique entre l'électrode amont et la tige de connexion, et
  • Figure 4 est une demi-vue partielle en section sagittale de la partie de la torche à hauteur du système d'injection de gaz plasmagène.
Other characteristics and advantages will emerge from the description which follows of an embodiment of a plasma torch according to the invention, description given by way of example only and with reference to the appended drawings in which:
  • Figure 1 is a schematic perspective view of a plasma torch according to the invention;
  • Figure 2, divided respectively into 2a, 2b and 2c for readability, is a half-view in axial section of the torch of Figure 1;
  • FIG. 3 is a partial half-view in sagittal section of the part of the torch at the height of the electrical connection between the upstream electrode and the connection rod, and
  • Figure 4 is a partial half-view in sagittal section of the part of the torch at the level of the plasma gas injection system.

Sur la figure 1 est représentée une torche à plasma selon l'invention, utilisable par exemple dans un four de vitrification de déchets, constituée de deux parties essentielles, à savoir une partie avant dite torche nue 1 de forme générale cylindrique et une partie arrière dite connectique 2 formée par une structure externe assurant les liaisons fluidiques et électriques de la torche avec l'extérieur et permettant le transport et la manipulation de la torche.In Figure 1 is shown a plasma torch according to the invention, usable for example in a waste vitrification oven, consisting of two essential parts, namely a front part called naked torch 1 of generally cylindrical shape and a rear part called connection 2 formed by an external structure ensuring the fluidic and electrical connections of the torch with the outside and allowing the transport and the handling of the torch.

La torche nue 1 présente une extrémité distale ou nez 3, de diamètre légèrement réduit, cependant que la structure 2, dite externe car demeurant à l'extérieur du four lorsque la torche nue 1 est introduite dans ce dernier par une ouverture appropriée ménagée dans la paroi, est constituée d'un corps tubulaire 4 coaxial à la torche nue 1, muni à ses extrémités de deux brides 5 en forme de losange et portant à leurs extrémités des tourillons 6 de sustentation, à la manière connue, de la torche à un palonnier de manutention (non représenté).The naked torch 1 has a distal end or nose 3, of slightly reduced diameter, while the structure 2, called external because it remains outside the oven when the naked torch 1 is introduced into the latter by an appropriate opening made in the wall, consists of a tubular body 4 coaxial with the naked torch 1, provided at its ends with two flanges 5 in the form of a diamond and carrying at their ends journals 6 of lift, in the known manner, from the torch to a handling spreader (not shown).

La torche nue 1, suivant une caractéristique de l'invention, comporte une structure porteuse (figure 2) formée de trois enveloppes coaxiales se recouvrant partiellement, à savoir une enveloppe externe métallique 7, une enveloppe intermédiaire métallique 8 et une enveloppe interne 9 en matériau isolant électriquement.The naked torch 1, according to a characteristic of the invention, comprises a supporting structure (FIG. 2) formed of three coaxial envelopes partially overlapping, namely a metallic external envelope 7, an intermediate metallic envelope 8 and an internal envelope 9 made of material electrically insulating.

L'enveloppe 7 est cylindrique, s'étend sur toute la longueur de la torche nue 1 et est reliée à son extrémité proximale au corps tubulaire 4 de la structure externe 2 par une pièce de liaison annulaire 10.The casing 7 is cylindrical, extends over the entire length of the naked torch 1 and is connected at its proximal end to the tubular body 4 of the external structure 2 by an annular connecting piece 10.

L'enveloppe 8 est également cylindrique, s'étend sensiblement sur la longueur de l'enveloppe 7 de diamètre le plus grand, ainsi qu'à l'intérieur du corps 4 auquel elle est fixée de manière étanche, par une couronne filetée 11, approximativement dans la zone centrale.The envelope 8 is also cylindrical, extends substantially over the length of the envelope 7 of the largest diameter, as well as inside the body 4 to which it is tightly fixed, by a threaded crown 11, approximately in the central area.

Entre les deux enveloppes 7,8 est ainsi ménagé un espace annulaire 12 communiquant avec un espace annulaire 13 défini entre le corps 4 et l'enveloppe 8.Between the two envelopes 7,8 is thus formed an annular space 12 communicating with an annular space 13 defined between the body 4 and the envelope 8.

L'espace 13 communique par un passage, représenté en 14 sur la figure 1 et symbolisé par la même référence numérique sur la figure 2, avec une canalisation (non représentée) de retour du fluide de refroidissement, en l'occurrence de l'eau déminéralisée, de la partie chaude de la torche. A son extrémité distale, l'enveloppe intermédiaire 8 sert de support à un séparateur annulaire 15 du circuit de refroidissement de l'électrode aval 16 qui est une électrode annulaire conventionnelle dont l'extrémité distale est fixée au nez de la torche.The space 13 communicates by a passage, represented at 14 in FIG. 1 and symbolized by the same reference numeral in FIG. 2, with a pipe (not shown) for the return of the cooling fluid, in this case water. demineralized, from the hot part of the torch. At its distal end, the intermediate casing 8 serves as a support for an annular separator 15 of the cooling circuit of the downstream electrode 16 which is a conventional annular electrode whose distal end is fixed to the nose of the torch.

L'extrémité distale de l'enveloppe intermédiaire 8 sert également, comme on le verra plus loin, à la fixation du système d'injection de gaz plasmagène 17 et de l'extrémité distale de l'électrode amont 18 qui est une électrode annulaire également conventionnelle coaxiale, comme l'électrode aval 16, à l'axe 19 de la torche.The distal end of the intermediate envelope 8 also serves, as will be seen below, for fixing the plasma gas injection system 17 and the distal end of the upstream electrode 18 which is also an annular electrode conventional coaxial, like the downstream electrode 16, to the axis 19 of the torch.

L'enveloppe 9 est un tube cylindrique qui s'étend sensiblement entre l'extrémité proximale de l'électrode amont 18 et un endroit du corps 4 légèrement en arrière de la pièce 11 en étant fixé audit corps 4 par une couronne filetée 20.The casing 9 is a cylindrical tube which extends substantially between the proximal end of the upstream electrode 18 and a place on the body 4 slightly behind the part 11 while being fixed to said body 4 by a threaded crown 20.

Le tube 9 définit ainsi avec l'enveloppe intermédiaire 8 un espace annulaire 21 communiquant, côté structure 2, avec un espace annulaire 22 interne au corps 4 et communiquant, par un passage représenté en 23 sur la figure 1 et seulement symbolisé par la même référence numérique sur la figure 2, avec une canalisation (non représentée) d'amenée de fluide plasmagène, en l'occurrence de l'air.The tube 9 thus defines, with the intermediate envelope 8, an annular space 21 communicating, on the structure side 2, with an annular space 22 internal to the body 4 and communicating, by a passage represented at 23 in FIG. 1 and only symbolized by the same reference. digital in FIG. 2, with a pipe (not shown) for supplying plasma-generating fluid, in this case air.

L'extrémité distale de l'enveloppe interne 9 est en contact étanche avec l'extrémité d'un séparateur annulaire 24 du circuit de refroidissement de l'électrode amont 18.The distal end of the internal envelope 9 is in sealed contact with the end of an annular separator 24 of the cooling circuit of the upstream electrode 18.

Une bobine électromagnétique tubulaire dite de champ 25, également conventionnelle et destinée, à la manière connue, à déplacer le pied d'arc sur l'électrode amont 18 enveloppe extérieurement cette électrode.A tubular electromagnetic coil called field 25, also conventional and intended, in the known manner, to move the arc foot on the upstream electrode 18 externally envelops this electrode.

L'extrémité distale du séparateur 24 est reliée à l'extrémité distale de l'enveloppe intermédiaire 8 par le biais d'une pièce annulaire de liaison 26 en matériau isolant électriquement, support du système d'injection de gaz plasmagène 17.The distal end of the separator 24 is connected to the distal end of the intermediate casing 8 by means of an annular connecting piece 26 of electrically insulating material, support for the plasma gas injection system 17.

Ce système d'injection (voir aussi figure 4) comprend une grille ajourée annulaire 27, en matériau isolant électriquement, disposée dans l'intervalle entre électrodes 16,18 et sur la face externe de laquelle est ménagée une chambre d'homogénéisation 28, réalisée dans la pièce 26.This injection system (see also FIG. 4) comprises an annular perforated grid 27, made of electrically insulating material, arranged in the interval between electrodes 16,18 and on the external face of which is provided a homogenization chamber 28, produced in room 26.

La chambre 28 communique par des trous 29 traversant la pièce 26 avec l'espace 21. Les trous 29, au nombre de six (cf. figure 4 sur laquelle une section complète de la pièce 26 est représentée en perspective) sont régulièrement répartis et leurs axes 30 ne coupent pas l'axe de la pièce 26 afin de créer un effet de vortex lorsque l'air pénètre par les trous 29 dans la chambre d'homogénéisation 28.The chamber 28 communicates through holes 29 passing through the part 26 with the space 21. The holes 29, six in number (cf. FIG. 4 on which a complete section of the part 26 is shown in perspective) are regularly distributed and their axes 30 do not intersect the axis of the part 26 in order to create a vortex effect when the air enters through the holes 29 in the homogenization chamber 28.

En outre, la pièce 26 est percée d'une série de trous 31 d'axes parallèles à l'axe de la pièce 26, c'est-à-dire l'axe 19 de la torche, afin d'assurer la continuité du circuit de refroidissement, successivement de l'électrode amont 18 et de la bobine de champ 25, puis de l'électrode aval 16.In addition, the part 26 is pierced with a series of holes 31 with axes parallel to the axis of the part 26, that is to say the axis 19 of the torch, in order to ensure the continuity of the cooling circuit, successively of the upstream electrode 18 and the field coil 25, then of the downstream electrode 16.

Sur la figure 2, on peut observer que les trous 31 font communiquer un espace annulaire 32 défini entre le séparateur 24 et un tube séparateur 33 enveloppant à distance la bobine de champ 25 et un espace annulaire 34 délimité entre le séparateur 15 et l'électrode aval 16.In FIG. 2, it can be observed that the holes 31 make an annular space 32 defined between the separator 24 and a separator tube 33 communicate, enveloping the field coil 25 and a annular space 34 delimited between the separator 15 and the electrode. downstream 16.

A l'extrémité proximale de l'électrode aval 16, en regard de l'électrode amont 18, est fixé un pion-butée 35 dit d'allumage.At the proximal end of the downstream electrode 16, facing the upstream electrode 18, is fixed an abutment pin 35 said to be ignition.

A son extrémité proximale l'électrode amont 18 est fixée à l'extrémité d'une tige métallique 36, par exemple en cuivre, elle-même fixée à l'extrémité d'un axe de transmission 37 en matériau isolant électriquement, de forte section et dont l'extrémité est montée coulissante dans un alésage 38 d'un flasque 39 rapporté sur l'extrémité externe du corps 4.At its proximal end the upstream electrode 18 is fixed to the end of a metal rod 36, for example made of copper, itself fixed to the end of a transmission axis 37 of electrically insulating material, of large section and the end of which is slidably mounted in a bore 38 of a flange 39 attached to the external end of the body 4.

Ladite extrémité coulissante de l'axe 37 est solidaire d'une tige 40 s'étendant à l'intérieur d'une tige creuse 41 d'un vérin starter 42 fixé au flasque 39, extérieurement au corps 4.Said sliding end of the axis 37 is integral with a rod 40 extending inside a hollow rod 41 of a choke cylinder 42 fixed to the flange 39, outside the body 4.

La tige creuse 41 traverse complètement le vérin 42 et est solidaire, à son extrémité externe, de la tige 40 par l'intermédiaire d'une paire 43 d'écrou et contre-écrou. A son autre extrémité, la tige 41 est en appui contre une rondelle 44 solidaire de la tige 40, par l'intermédiaire d'un ressort amortisseur 45. Une butée à vis 46, réglable en position sur la tige de vérin 41, permet, par modification de son éloignement vis à vis de l'extrémité du vérin 42, de régler la course de la tige de vérin.The hollow rod 41 passes completely through the jack 42 and is secured, at its outer end, to the rod 40 by means of a pair 43 of nut and lock nut. At its other end, the rod 41 is in abutment against a washer 44 integral with the rod 40, by means of a damping spring 45. A screw stop 46, adjustable in position on the jack rod 41, allows, by modifying its distance from the end of the jack 42, to adjust the stroke of the jack rod.

La tige 36 porte une douille métallique 47 montée coulissante et solidaire du support de la bobine de champ 25 à l'enroulement de laquelle est connectée ladite douille 47.The rod 36 carries a metal bush 47 mounted to slide and integral with the support of the field coil 25 to the winding of which said bush 47 is connected.

Une douille 49 de connexion électrique à la bobine 25 est fixée à l'extrémité d'une tige de connexion électrique 50, parallèle à l'axe 19, s'étendant en regard de l'enveloppe tubulaire interne 9 et traversant le corps 4 pour être fixée au flasque 39 dont le matériau est bien entendu non conducteur de l'électricité.A socket 49 for electrical connection to the coil 25 is fixed to the end of an electrical connection rod 50, parallel to the axis 19, extending opposite the internal tubular casing 9 and passing through the body 4 to be attached to the flange 39, the material of which is of course not electrically conductive.

La tige 50 est reliée à une borne de connexion électrique 51 (pôle plus), le pôle moins étant constitué par la borne de connexion 52, reliée au corps métallique 4.The rod 50 is connected to an electrical connection terminal 51 (plus pole), the minus pole being constituted by the connection terminal 52, connected to the metal body 4.

Le circuit électrique d'alimentation des électrodes comprend donc la tige 50, la pièce 49, la bobine de champ 25 qui est montée en série, la pièce 47, la tige 36, l'électrode amont 18, l'électrode aval 16, le nez de la torche, l'enveloppe externe 7 et le corps 4.The electrical circuit for supplying the electrodes therefore comprises the rod 50, the part 49, the field coil 25 which is mounted in series, the part 47, the rod 36, the upstream electrode 18, the downstream electrode 16, the torch nose, outer casing 7 and body 4.

L'enveloppe interne 9 est en contact par sa face interne avec un espace 53 délimité par le corps 4 et dans l'axe duquel s'étendent les tiges 36 et 37.The internal envelope 9 is in contact by its internal face with a space 53 delimited by the body 4 and in the axis of which extend the rods 36 and 37.

Cet espace 53 communique par un passage, représenté en 54 sur la figure 1 et seulement symbolisé par la même référence numérique sur la figure 2, susceptible d'être connecté à une canalisation (non représentée) d'arrivée d'eau de refroidissement de la torche.This space 53 communicates by a passage, represented at 54 in FIG. 1 and only symbolized by the same reference numeral in FIG. 2, capable of being connected to a pipe (not shown) for the arrival of cooling water from the torch.

Le circuit d'eau de refroidissement est ainsi constitué de l'espace 53, lequel communique par des trous 48a ménagés dans la pièce 47 avec un espace annulaire 48b ménagé entre l'embout 48c de l'électrode amont 18 et un déflecteur annulaire 48d formant venturi, solidaire de la bobine 25 et canalisant l'eau vers l'espace entre l'électrode amont 18 et la bobine de champ 25. Ensuite, l'eau passe dans l'espace entre la bobine 25 et le tube 33, dans l'espace 32 (via des perforations 55 à l'extrémité proximale du tube 33), dans les passages 31, dans l'espace 34, puis dans l'espace 12 et enfin dans l'espace 13. Ce circuit lèche ainsi complètement et de manière la plus directe possible les parties électriquement conductrices 50,49,47, l'embout amont 48c, puis la face externe de l'électrode amont 18, les deux faces de la bobine de champ 25, le système d'injection 17, la face externe de l'électrode aval 16 et enfin la face externe de la torche nue 1, sur la totalité de sa longueur.The cooling water circuit thus consists of the space 53, which communicates through holes 48a formed in the part 47 with an annular space 48b formed between the end piece 48c of the upstream electrode 18 and an annular deflector 48d forming venturi, integral with the coil 25 and channeling water to the space between the upstream electrode 18 and the field coil 25. Next, the water passes into the space between the coil 25 and the tube 33, into space 32 (via perforations 55 to the proximal end of the tube 33), in the passages 31, in the space 34, then in the space 12 and finally in the space 13. This circuit thus completely and directly licks the electrically conductive parts 50,49,47, the upstream tip 48c, then the external face of the upstream electrode 18, the two faces of the field coil 25, the injection system 17, the external face of the downstream electrode 16 and finally the external face of the naked torch 1, over its entire length.

Un tel circuit est relativement simple en comparaison avec ceux des torches traditionnelles. Il refroidit de façon optimale les parties chaudes de la torche, ainsi que la totalité de son enveloppe externe 7, ce qui permet à la torche d'affronter sans endommagement les températures régnant dans un four de vitrification et qui peuvent largement dépasser 1600°C, voire atteindre 2000°C.Such a circuit is relatively simple in comparison with those of traditional torches. It optimally cools the hot parts of the torch, as well as all of its outer casing 7, which allows the torch to face without damaging the temperatures prevailing in a vitrification oven and which can greatly exceed 1600 ° C, or even reach 2000 ° C.

De plus, les pertes de charge du circuit de refroidissement sont réduites par rapport à celles des circuits conventionnels, ce qui permet d'abaisser la pression de service de la source d'eau de refroidissement de la torche. C'est ainsi que pour un type de torche à arc non transféré de la Demanderesse, la pression de l'eau de refroidissement a été ramenée de 12 à 6 bars.In addition, the pressure drops of the cooling circuit are reduced compared to those of conventional circuits, which makes it possible to lower the operating pressure of the source of cooling water for the torch. Thus, for a type of arc torch not transferred from the Applicant, the pressure of the cooling water has been reduced from 12 to 6 bars.

ll est important de remarquer que la conception sous forme d'enveloppes tubulaires concentriques 7,8 et 9 de la structure portant les organes essentiels (électrodes, injecteur, bobine de champ) de la torche et les reliant au bloc connectique 2, permet une grande liberté dans la détermination de la longueur de la torche nue 1.It is important to note that the design in the form of concentric tubular casings 7, 8 and 9 of the structure carrying the essential organs (electrodes, injector, field coil) of the torch and connecting them to the connector block 2, allows a large freedom in determining the length of the naked torch 1.

Pour s'en convaincre, il suffit de se reporter, sur la figure 2, à la zone de la torche à hauteur de la tige 36, pour constater que les modifications de longueur de la torche nue auront simplement un retentissement sur la longueur des enveloppes 7,8,9 et des tiges 36,37,50.To be convinced, it suffices to refer, in FIG. 2, to the zone of the torch at the height of the rod 36, to note that the modifications of length of the naked torch will simply have an impact on the length of the envelopes 7,8,9 and rods 36,37,50.

Ainsi des torches nues de différentes longueurs pourront être équipées intérieurement des mêmes organes (électrodes, injecteur, bobine de champ, séparateurs, pièces de liaison électriques, etc...), les circulations de fluides (air et eau) étant assurées de la même manière par l'intermédiaire des espaces ménagés entre les différentes enveloppes 7,8,9.Thus naked torches of different lengths can be internally equipped with the same organs (electrodes, injector, field coil, separators, electrical connection parts, etc.), the circulation of fluids (air and water) being provided in the same way through the spaces provided between the various envelopes 7,8,9.

Suivant une autre caractéristique importante de l'invention, le montage particulier du vérin starter 42, complètement à l'extérieur du corps 4, avec la tige de connexion 37 à forte section baignant dans l'eau de refroidissement à l'entrée de la torche, permet, d'une part, un réglage de la course du vérin et une maintenance faciles et, d'autre part, de commander le vérin 42 avec un fluide à pression réduite par rapport aux vérins starters habituels.According to another important characteristic of the invention, the particular mounting of the choke cylinder 42, completely outside of the body 4, with the connecting rod 37 with a large section immersed in the cooling water at the inlet of the torch , allows, on the one hand, adjustment of the cylinder stroke and easy maintenance and, on the other hand, to control the cylinder 42 with a fluid at reduced pressure compared to the usual starters cylinders.

En effet, l'électrode amont des torches de ce type étant refroidie sur l'extérieur, la pression de l'eau crée sur l'électrode une poussée importante vers l'aval.Indeed, the upstream electrode of torches of this type being cooled on the outside, the water pressure creates on the electrode a significant thrust downstream.

Or, au démarrage, l'électrode amont 18 est amenée, par le vérin 42, au contact avec le pion-butée 35 au démarrage.However, at start-up, the upstream electrode 18 is brought, by the jack 42, into contact with the stop pin 35 at start-up.

La durée de ce contact doit être juste suffisante pour éviter les conséquences néfastes d'un court-circuit direct à très fort ampérage. Il est alors nécessaire d'envoyer au vérin starter la puissance adaptée pour la rétraction brutale de l'électrode amont, laquelle puissance doit surmonter ladite poussée vers l'aval occasionnée par l'eau de refroidissement.The duration of this contact must be just sufficient to avoid the harmful consequences of a direct short circuit with very high amperage. It is then necessary to send to the choke jack the power suitable for the abrupt retraction of the upstream electrode, which power must overcome said push downstream caused by the cooling water.

En prévoyant, conformément à l'invention, une section très importante à la tige de connexion 37, on compense pratiquement ladite poussée vers l'aval, en sorte que l'on a besoin d'un effort moindre de la part du vérin 42.By providing, in accordance with the invention, a very large section at the connection rod 37, this said downward thrust is practically compensated for, so that less effort is required on the part of the jack 42.

Ainsi, au lieu d'une pression habituelle de l'ordre de 160 bars, le vérin 42 peut n'être alimenté qu'à une pression largement de moitié moindre. Si la pression nécessaire au vérin starter peut même être suffisamment abaissée, par exemple jusqu'à 7 bars, on peut envisager d'utiliser pour actionner le vérin l'eau de refroidissement de la torche.Thus, instead of a usual pressure of the order of 160 bars, the jack 42 can only be supplied with a pressure which is largely half as low. If the pressure necessary for the choke cylinder can even be lowered sufficiently, for example up to 7 bars, one can consider using to actuate the cylinder cooling water from the torch.

Par ailleurs, la structure concentrique des enveloppes 7,8,9, permet un accès facile à l'intérieur de la torche, en commençant par déposer l'enveloppe externe 7, par exemple pour remplacer les électrodes ou toute autre pièce ou pour toute opération de maintenance ou de réparation.Furthermore, the concentric structure of the envelopes 7,8,9, allows easy access to the interior of the torch, starting by depositing the external envelope 7, for example to replace the electrodes or any other part or for any operation maintenance or repair.

A ce propos, il est à noter que l'extrémité de la tige de connexion électrique 50 est simplement enfichée, par l'intermédiaire de la pièce de liaison 49, sur des pions de connexion et/ou centrage 56 solidaires de la bobine 25 et du séparateur 24.In this regard, it should be noted that the end of the electrical connection rod 50 is simply plugged in, by means of the connecting piece. 49, on connection and / or centering pins 56 integral with the coil 25 and the separator 24.

ll est également à noter que l'extrémité distale de l'enveloppe 9 n'est pas solidaire du séparateur 24, ce qui autorise l'extraction hors de la torche de l'enveloppe 9 seule, pour accéder à la fixation (11) de l'enveloppe intermédiaire 8.It should also be noted that the distal end of the casing 9 is not integral with the separator 24, which allows the extraction of the casing 9 alone from the torch, to access the fixing (11) of the intermediate envelope 8.

Le positionnement mutuel des enveloppes 7,8,9 est assuré par exemple par de simples plots de guidage 57.The mutual positioning of the envelopes 7, 8, 9 is ensured for example by simple guide pads 57.

L'invention n'est évidemment pas limitée au mode de réalisation représenté et décrit ci-dessus, mais en couvre au contraire toutes les variantes, notamment en ce qui concerne l'agencement du système injecteur de gaz plasmagène 17, l'agencement de la bobine de champ 25, les moyens de commande de déplacement de l'électrode amont au démarrage, ou encore l'agencement de la structure externe 2.The invention is obviously not limited to the embodiment shown and described above, but on the contrary covers all its variants, in particular with regard to the arrangement of the plasma gas injector system 17, the arrangement of the field coil 25, the means for controlling the displacement of the upstream electrode at start-up, or even the arrangement of the external structure 2.

Enfin, l'invention s'applique d'une manière générale à tous types de torches à plasma à arc non-transféré, quel que soit le système de démarrage, ainsi qu'à tous types de torches à plasma à arc transféré.Finally, the invention applies generally to all types of plasma torches with non-transferred arc, whatever the starting system, as well as to all types of plasma torches with transferred arc.

Claims (5)

Torche à plasma à structure générale sensiblement axi-symétrique, du type comprenant : - une partie tubulaire dite torche nue (1) dans laquelle sont disposées une électrode unique dite amont ou une paire d'électrodes coaxiales dites amont (18) et aval (16), les électrodes étant tubulaires et refroidies par un circuit de refroidissement approprié, une bobine dite de champ (25) de déplacement du pied d'arc et des moyens (17) pour injecter un gaz plasmagène en aval de l'électrode amont ou entre l'électrode amont (18) et l'électrode aval (16), des moyens (42) étant en outre prévus pour assurer le démarrage de la torche, et - une structure dite externe (2), solidaire de la torche nue (1) à son extrémité proximale et dans laquelle sont regroupées les liaisons fluidiques et électriques avec l'extérieur de la torche, caractérisée en ce que ladite torche nue (1) comporte une structure porteuse formée de trois enveloppes coaxiales se recouvrant au moins partiellement, solidaires de ladite structure externe (2), à savoir une enveloppe externe (7) métallique, une enveloppe intermédiaire (8) métallique définissant avec l'enveloppe externe (7) le circuit de retour du fluide de refroidissement de la ou des électrodes (18,16) et de la bobine (25), et une enveloppe interne (9) définissant avec l'enveloppe intermédiaire (8) le circuit d'admission du gaz plasmagène auxdits moyens d'injection (17) et canalisant par sa face interne le flux entrant du fluide de refroidissement en direction de l'électrode amont (18), de la bobine de champ (25) et éventuellement de l'électrode aval (16).Plasma torch with a generally axi-symmetrical general structure, of the type comprising: a tubular part known as a naked torch (1) in which a single so-called upstream electrode or a pair of coaxial electrodes called upstream (18) and downstream (16) are arranged, the electrodes being tubular and cooled by an appropriate cooling circuit, a so-called field coil (25) for displacement of the arc foot and means (17) for injecting a plasma gas downstream of the upstream electrode or between the upstream electrode (18) and the downstream electrode (16) , means (42) being further provided for starting the torch, and - a so-called external structure (2), integral with the naked torch (1) at its proximal end and in which the fluid and electrical connections with the outside of the torch are grouped, characterized in that said naked torch (1) comprises a support structure formed by three coaxial envelopes overlapping at least partially, integral with said external structure (2), namely an external envelope (7) made of metal, an intermediate envelope (8) metallic defining with the external envelope (7) the return circuit of the coolant of the electrode (s) (18,16) and the coil (25), and an internal envelope (9) defining with the intermediate envelope ( 8) the plasma gas intake circuit to said injection means (17) and channeling via its internal face the incoming flow of cooling fluid towards the upstream electrode (18), the field coil (25) and possibly the downstream electrode (16). Torche suivant la revendication 1, du type à arc non-transféré, munie d'un dispositif de démarrage comportant un vérin dit starter (42) agissant sur l'électrode amont (18) pour la rapprocher momentanément de l'électrode aval (16), caractérisée en ce que ledit vérin starter (42) est disposé à l'extérieur du corps (4) de ladite structure externe et comporte une tige (41) qui traverse de part en part le vérin, est reliée à l'électrode amont (18) par une tige de liaison (37) s'étendant dans le corps (4) de la structure externe et à l'intérieur de ladite enveloppe interne( 9) et présente une section permettant audit flux entrant du fluide de refroidissement d'exercer sur ladite tige de vérin (41) une contre-pression tendant à contrebalancer la pression dudit fluide sur l'électrode amont (18), cependant que l'extrémité externe de la tige (41) du vérin est munie de moyens (46) de réglage de la course de cette tige (41).Torch according to claim 1, of the non-transferred arc type, provided with a starting device comprising a so-called starter cylinder (42) acting on the upstream electrode (18) to momentarily bring it closer to the downstream electrode (16) , characterized in that said choke cylinder (42) is disposed outside the body (4) of said external structure and comprises a rod (41) which passes right through the cylinder, is connected to the upstream electrode ( 18) by a connecting rod (37) extending in the body (4) of the external structure and inside said internal envelope (9) and has a section allowing said incoming flow of cooling fluid to exert on said cylinder rod (41 ) a back pressure tending to counterbalance the pressure of said fluid on the upstream electrode (18), while the external end of the rod (41) of the jack is provided with means (46) for adjusting the stroke of this rod (41). Torche suivant la revendication 1 ou 2, caractérisée en ce que la bobine de champ (25) entoure extérieurement l'électrode amont (18), est refroidie sur ses faces interne et externe et est reliée électriquement, d'une part, par une liaison enfichable (49,56) avec une tige de connexion électrique (50) disposée à l'intérieur de ladite enveloppe interne (9) et connectée à son autre extrémité à une borne électrique (51) de la structure externe (2) et, d'autre part, à l'électrode amont (18) par une connexion à contact glissant avec la tige (36,37) de liaison entre le vérin starter (42) et ladite électrode amont (18).Torch according to claim 1 or 2, characterized in that the field coil (25) externally surrounds the upstream electrode (18), is cooled on its internal and external faces and is electrically connected, on the one hand, by a connection pluggable (49,56) with an electrical connection rod (50) disposed inside said internal casing (9) and connected at its other end to an electrical terminal (51) of the external structure (2) and, d 'other hand, to the upstream electrode (18) by a sliding contact connection with the rod (36,37) connecting between the choke cylinder (42) and said upstream electrode (18). Torche suivant l'une des revendications 1 à 3, caractérisée en ce que les espaces (12,21,53) délimités respectivement entre l'enveloppe externe (7) et l'enveloppe intermédiaire (8), entre l'enveloppe intermédiaire (8) et l'enveloppe interne (9) et à l'intérieur de l'enveloppe interne (9), communiquent respectivement avec un premier espace annulaire (13), un deuxième espace annulaire (22) et un troisième espace (53), tous les trois ménagés dans ladite structure externe (2), lesdits troisième et premier espaces (53,13) communiquant respectivement avec une arrivée (54) et une sortie (14) de fluide de refroidissement de la torche, cependant que ledit deuxième espace (22) communique avec une source (23) de gaz plasmagène.Torch according to one of claims 1 to 3, characterized in that the spaces (12,21,53) defined respectively between the outer casing (7) and the intermediate casing (8), between the intermediate casing (8 ) and the internal envelope (9) and inside the internal envelope (9), communicate respectively with a first annular space (13), a second annular space (22) and a third space (53), all the three formed in said external structure (2), said third and first spaces (53,13) communicating respectively with an inlet (54) and an outlet (14) of coolant for the torch, while said second space (22 ) communicates with a source (23) of plasma gas. Torche suivant l'une des revendications 2 à 4, caractérisée en ce que les moyens d'injection de gaz plasmagène (17) sont disposés à l'intérieur de l'enveloppe intermédiaire et constitués d'une pièce annulaire (26) munie de passages (29) en direction d'une chambre d'homogénéisation (28) agencée sur la face interne de ladite pièce (26) et de passages (31) coaxiaux à l'axe (19) de la torche, assurant la continuité du circuit de refroidissement des faces externes des électrodes amont (18) et aval (16) et d'une grille ajourée d'injection (27) en regard de ladite chambre d'homogénéisation (28), agencée dans l'intervalle entre lesdites électrodes (18,16).Torch according to one of Claims 2 to 4, characterized in that the means for injecting plasma gas (17) are arranged inside the intermediate envelope and consist of an annular part (26) provided with passages (29) in the direction of a homogenization chamber (28) arranged on the internal face of said part (26) and passages (31) coaxial with the axis (19) of the torch, ensuring the continuity of the circuit of cooling of the external faces of the upstream (18) and downstream (16) electrodes and of a perforated injection grid (27) in sight of said homogenization chamber (28), arranged in the gap between said electrodes (18,16).
EP96450016A 1995-06-23 1996-06-19 Plasma torch having an essentially axisymmetrical general structure Expired - Lifetime EP0750450B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9507790 1995-06-23
FR9507790A FR2735940B1 (en) 1995-06-23 1995-06-23 PLASMA TORCH WITH A SUBSTANTIALLY AXI-SYMMETRICAL STRUCTURE

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EP0750450A1 true EP0750450A1 (en) 1996-12-27
EP0750450B1 EP0750450B1 (en) 2000-09-27

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EP (1) EP0750450B1 (en)
JP (1) JP4108775B2 (en)
CA (1) CA2179655C (en)
DE (1) DE69610464T2 (en)
FR (1) FR2735940B1 (en)
ZA (1) ZA965303B (en)

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DE19842074B4 (en) * 1998-09-15 2004-06-03 Castolin S.A. Anode for plasma application torches
JP4044397B2 (en) * 2001-10-15 2008-02-06 積水化学工業株式会社 Plasma surface treatment equipment
DK2514280T3 (en) * 2009-12-15 2014-09-01 Univ Danmarks Tekniske Apparatus for treating a surface with at least one sliding arc source

Citations (4)

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Publication number Priority date Publication date Assignee Title
EP0427592A1 (en) * 1989-11-08 1991-05-15 AEROSPATIALE Société Nationale Industrielle Plasma torch with short-circuit arc starting
EP0427590A1 (en) * 1989-11-08 1991-05-15 AEROSPATIALE Société Nationale Industrielle Plasma torch with electromagnetic coil for rotating the arc
EP0490882A1 (en) * 1987-01-30 1992-06-17 Hypertherm, Inc. Arc plasma torch and method using contact starting
US5362939A (en) * 1993-12-01 1994-11-08 Fluidyne Engineering Corporation Convertible plasma arc torch and method of use

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Publication number Priority date Publication date Assignee Title
US4668853A (en) * 1985-10-31 1987-05-26 Westinghouse Electric Corp. Arc-heated plasma lance

Patent Citations (4)

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Publication number Priority date Publication date Assignee Title
EP0490882A1 (en) * 1987-01-30 1992-06-17 Hypertherm, Inc. Arc plasma torch and method using contact starting
EP0427592A1 (en) * 1989-11-08 1991-05-15 AEROSPATIALE Société Nationale Industrielle Plasma torch with short-circuit arc starting
EP0427590A1 (en) * 1989-11-08 1991-05-15 AEROSPATIALE Société Nationale Industrielle Plasma torch with electromagnetic coil for rotating the arc
US5362939A (en) * 1993-12-01 1994-11-08 Fluidyne Engineering Corporation Convertible plasma arc torch and method of use

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JPH09115689A (en) 1997-05-02
FR2735940B1 (en) 1997-09-19
CA2179655C (en) 2007-08-21
FR2735940A1 (en) 1996-12-27
EP0750450B1 (en) 2000-09-27
US5695664A (en) 1997-12-09
DE69610464D1 (en) 2000-11-02
ZA965303B (en) 1997-04-14
DE69610464T2 (en) 2001-07-19
CA2179655A1 (en) 1996-12-24
JP4108775B2 (en) 2008-06-25

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