EP0200637B1 - Apparatus for the production of a high temperature gas jet - Google Patents

Apparatus for the production of a high temperature gas jet Download PDF

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Publication number
EP0200637B1
EP0200637B1 EP86400868A EP86400868A EP0200637B1 EP 0200637 B1 EP0200637 B1 EP 0200637B1 EP 86400868 A EP86400868 A EP 86400868A EP 86400868 A EP86400868 A EP 86400868A EP 0200637 B1 EP0200637 B1 EP 0200637B1
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EP
European Patent Office
Prior art keywords
tube
gas
heating tube
enclosure
closure plate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP86400868A
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German (de)
French (fr)
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EP0200637A1 (en
Inventor
Guy Salinier
Philippe Renault
Pierre Lelong
Christophe Dembinski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Application filed by LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude filed Critical LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority to AT86400868T priority Critical patent/ATE40741T1/en
Publication of EP0200637A1 publication Critical patent/EP0200637A1/en
Application granted granted Critical
Publication of EP0200637B1 publication Critical patent/EP0200637B1/en
Expired legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/38—Torches, e.g. for brazing or heating
    • F23D14/42—Torches, e.g. for brazing or heating for cutting

Definitions

  • the present invention relates to an apparatus for producing a jet of gas at high temperature, comprising an enclosure, means for introducing a gas into this enclosure, means for heating the gas in the enclosure and means for evacuation of hot gas from the enclosure.
  • jets of hot oxidizing gas in particular oxygen
  • the flame-cutting technique uses a torch from which a high-speed oxygen jet comes out surrounded by a heating flame.
  • peripheral heating flame is essential for initiating the reaction. After priming, the essential role of this heating flame is to maintain the upper edge of the bleeding front at a temperature sufficient for the sheath of liquid slag to be renewed.
  • the necessary calories being provided by the iron oxidation reaction the heating in fact occurs only to avoid risk of defusing.
  • thermoelectric generator this gas being able to be an oxidizing gas by applications such as metallurgy, oxy-fuel burners, etc ... or a non-oxidizing or inert gas, such as nitrogen, etc. in applications, for example, of the heat treatment type.
  • German patent 726 668 It is known from German patent 726 668 to cool the mixing nozzle of a torch using cutting oxygen, brought around the latter in a coil surrounding the nozzle, the oxygen being thus preheated by recovery part of the heat given off by the oxy-cutting reaction.
  • the object of the present invention is therefore to provide a device of particularly simple design, having good thermal efficiency and making it possible to produce at its outlet a jet of gas at a very high temperature, which can reach 1600 ° C. at most.
  • the apparatus according to the invention is characterized in that the gas heating means consist, on the one hand, of a heating tube extending longitudinally in the enclosure and constituting a heating resistor, this tube comprising electrical connection means for the connection of this resistor to electrical supply means, and on the other hand, heat exchanger means arranged around the heating tube and in thermal contact therewith, said means forming at least one pipe gas pipe extending from the introduction means and opening into the interior of the tube through an opening located near one end of the heating tube, a second end communicates with the means for discharging the hot gas from the enclosure, the gas thus being heated in the heat exchanger means before passing inside the heating tube to finally flow through the means for removing the hot gas from the enclosure.
  • the gas heating means consist, on the one hand, of a heating tube extending longitudinally in the enclosure and constituting a heating resistor, this tube comprising electrical connection means for the connection of this resistor to electrical supply means, and on the other hand, heat exchanger means arranged around the heating tube and in thermal contact therewith, said means forming
  • the apparatus shown in FIG. 1 comprises a tubular enclosure 1, for example made of stainless steel or of refractory material, the two opposite ends of which are closed by transverse flanges 2 and 3 respectively.
  • the straight closing flange 3 is welded to the right end of the tubular enclosure 1 while the left flange 2 is removably mounted on a flange 4 welded to the left end of the enclosure 1 and it is fixed to this flange 4 by means of bolts 5.
  • This closing flange 2 constitutes a support for two electrical supply terminals, one of which forms part of an electrical contact 6 engaged inside the enclosure 1, mounted to slide axially in the flange 2 and which is biased towards inside the enclosure by a spring 7 compressed between two washers 8 and 9, for example made of alumina.
  • the washer 8 is held in abutment against a collar 6a of the contact 6 while the insulating sleeve 9 is engaged through the central part of the closing flange 2.
  • the contact 6 projects axially outside the closing flange 2 and its outer end constitutes a terminal which can be connected to the positive pole of a DC power source, the negative pole of which is connected to the closing flange 2, for example by means of a terminal immobilized by one of the bolts 5 forming a negative terminal.
  • the device can also operate with an alternative power source.
  • a heating element 11 constituted by a tube made of a ceramic material such as zirconia or lanthanum chromite or the two associated for example.
  • a ceramic material such as zirconia or lanthanum chromite or the two associated for example.
  • a ceramic compound has the particularity of being both refractory (melting around 2,500 ° C.) and electrical conductor from room temperature.
  • This ceramic tube preferably consists of a part resistant central and end conductive parts having a resistivity about ten times lower than that of the central part.
  • the extreme parts with low resistivity may comprise, on the ceramic tube with constant resistivity, platinum-plated external zones.
  • the tube 11 could be entirely electrically resistant.
  • the ceramic heating tube 11 is fitted, at its right end, into a housing 3a of the same diameter provided in the internal front face of the right closing flange 3 and it is applied against the bottom of this housing 3a under the effect of the pressure exerted by the contact 6 on its opposite end, under the action of the spring 7.
  • this contact 6 is applied against the front face of a conductive end piece 12 itself pressing against the left end of the heating tube in ceramic 11.
  • the extreme left part of the heating tube 11 and the conductive washer 12 are housed in the internal recess of an alumina ring 13 engaged in the enclosure 1 and whose external diameter corresponds to the internal diameter of this enclosure.
  • the ceramic heating tube 11 may or may not have a machined outer surface. This surface may, for example, have a thread or even longitudinal grooves.
  • the ceramic heating tube 11 is surrounded, over most of its length, by a heat exchanger made of thermally conductive material.
  • This heat exchanger can be constituted by at least one internal tube 14 made of dense thermally conductive material, (for example made of alumina or lanthanum chromite) which is itself surrounded by an external tube 15 made of porous thermally conductive material, (for example made of alumina porous).
  • an external tube 15 made of porous thermally conductive material for example made of alumina porous.
  • a winding of zirconia felt 16 can optionally be provided between the external tube 15 made of porous alumina and the tubular enclosure 1.
  • the gas which must be heated flows through an external coil 17 which is wound around the tubular enclosure 1 and in thermal contact with it.
  • the gas is introduced into the coil 17 at its left end, that is to say the one where the contact 6 is located, and it penetrates inside the enclosure 1, at the right end of the coil which communicates with the interior of the enclosure 1, by means of a hole 18 drilled at this location in the wall of this enclosure.
  • the gas which enters the enclosure 1 at its right end then flows, in the pipes 117, 118 as indicated by the arrows, longitudinally from right to left, through the external porous alumina tube 15 which may optionally have longitudinal grooves to facilitate this flow, and possibly through the zirconia felt winding 16 if the latter is present.
  • the gas leaves in a space delimited between this left end and the alumina ring 13, then it reverses its direction of flow by passing, from left to right, between the tube dense alumina 14 and the ceramic heating tube 11.
  • This flow can be facilitated by the presence of longitudinal grooves or of a thread, on the external surface of the heating tube 11 or on the internal surface of the dense alumina tube 14.
  • the heating tube 11 has, in its wall, at least one opening 19 which allows the gas to pass inside the tube 11.
  • the hot gas can then leave the device, flowing, in the form an axial jet, through an outlet nozzle 21 fixed removably, by means of screws 22, on the right closing flange 3.
  • This nozzle 21 can be a well-known flame-cutting nozzle, cooled or not.
  • this nozzle 1 is cooled by water supplied by a pipe 23. It also has an inlet port 24 for connection to a source of heating gas.
  • the ceramic tube 11 When the appliance is in operation, the ceramic tube 11 is heated by the electric current passing from the contact 6, through the conductive washer 12, then over the entire length of the heating tube 11 to the left closing flange 2 which is connected to the negative pole of the electrical power source, i.e. to ground. Due to the passage of this electric current, the ceramic tube 11 heats up in its central part with high resistivity, so that the temperature of this central part can wait for approximately 1,800 ° C. in normal operation. The end parts of the heating tube 11 reach a temperature below 400 ° C, due to their much lower resistivity, which allows good electrical contact to be maintained.
  • the heating tube 11 can be supplied with alternating or direct current, this heating tube behaving like a pure resistance.
  • the tubes 14 of dense alumina and 15 of porous alumina heat up together with the internal heating tube 11 and in turn heat the enclosure 1 and the coil 17.
  • the gas flowing in the coil 17 is gradually preheated therein. ci, it enters the enclosure 1, at the outlet of the coil 17, then continues to heat up when it flows first from the right to the left through the external porous alumina tube 15 and possibly the winding of zirconia felt 16, then from left to right between the dense alumina tube 14 and the heating tube 11.
  • the gas jet leaving the nozzle 21 can reach a temperature in the region of 1600 ° C. .
  • coaxial alumina tubes 14 and 15 are preferably used between the central heating tube and the external enclosure 1, it is also possible to use tubes of another material, for example lanthanum chromite .
  • the dense alumina tube 14 is advantageously used because it has good thermal characteristics, an expansion coefficient close to that of the lanthanum chromite constituting the heating tube 11 and it also withstands very high temperatures.
  • the porous alumina tube 15 which is preferably used around the dense alumina tube 14, offers the advantage of being a better thermal insulator than the dense alumina.
  • the winding of zirconia felt 16 which is optionally provided between the porous alumina tube 15 and the enclosure 1, makes it possible to reinforce the insulation and also to provide a significant exchange surface for the gas which also preheats on passing through it.
  • the electrical contact 6 is resiliently biased by the spring 7 against the heating tube 11, by means of the conductive washer 12. This allows the axial expansion and contraction of the heating tube 11 while retaining good electrical contact. This expansion or contraction which is transmitted to the external part of the contact 6, can optionally be used for regulating the temperature of the heating tube 11.
  • the extreme left part of the enclosure 1 where the electrical contact 6 is located is advantageously cooled by a circulation of water in an internal tube 25 fixed, for example, to the internal face of the flange 4.
  • the coil 17 which is traversed by the still relatively cold gas is advantageously covered with a layer 26 of a thermally insulating material, the latter being in turn surrounded by an external cylinder 27.
  • a dense alumina tube 28 is housed coaxially inside the heating tube 11 and this tube 28 is engaged, by its straight end, in a housing for same diameter provided in the internal face of the right closing flange 3.
  • This flange is, in this case, removably mounted on a cylindrical support 29 welded to the right end of the enclosure 1, the fixing of the removable flange 3 on the support 29 being produced by means of screws 31.
  • the housing 3a In the internal face of the removable closing flange 3 are formed, on the one hand, the housing 3a, of relatively large diameter, receiving the right end of the heating tube 11, and on the other share another housing 3b, of smaller diameter than the previous one but deeper, receiving the right end of the inner tube 28 of dense alumina.
  • a platinum cup 32 is interposed between the extreme right part of the heating tube 11 and its housing 3a in the closing flange 3.
  • the internal tube 14 of dense alumina has a length greater than that of the external tube 15 of porous alumina.
  • the tube 15 made of porous alumina extends to the left front face 29a of the support 29 while the tube 14 of dense alumina penetrates inside this support 29 and passes completely through it to come into contact at its straight end with the internal face of the removable closing flange 3.
  • An asbestos washer is interposed between the extreme right part of the dense alumina tube 14 and the cylindrical internal wall of the support 29, this washer being axially tightened by an internal coaxial flange 30 of the right closing flange 3.
  • the inner tube 28 of dense alumina stops, inside the heating tube 11, at a certain distance from the left end of the latter. Furthermore, the electrical contact 6 is supported on a conductive tip 33 containing a platinum cup 34 which covers the left end of the heating tube 11 which is platinized.
  • the conductive end piece 33 is extended to the right by an axial finger 35 extending partly inside the inner tube 28 of dense alumina.
  • the inner tube 28 of dense alumina has at least one longitudinal slot 36 allowing the passage of the gas inside the tube 28.
  • FIG. 3 illustrates an alternative embodiment of the apparatus similar to that of FIG. 2 but in which the oxygen cutting nozzle 21 and the electrical contact 10 are not cooled by a circulation of water.
  • the contact 6 extends inside a finned radiator 37 mounted on the left closing flange 2 and which thus ensures the natural cooling of the contact 6.
  • the device does not include more coil which is replaced by a cylindrical chamber 17a surrounding the heat exchanger 14, 15.
  • the heating tube 11 is immobilized, in its extreme right part, that is to say that which is close to the outlet nozzle 21, by means of a clamp 38 in stainless steel with interposition of an asbestos ring 39 between the extreme right part of the heating tube 11 and the right closing flange 3.
  • the gas is introduced into a thread 17b at its end located on the right side, that is to say on the side of the outlet nozzle 21, this thread 17b being machined in the external surface of the tubular enclosure 1.
  • the gas penetrates inside the enclosure 1 by holes 18 located in the left part of the enclosure 1.
  • the gas penetrating inside the enclosure 1 flows from the left to the right through the external porous alumina tube 15 then from the right to left between the inner tube 14 of dense alumina and the heating tube 11, it penetrates inside this heated tube ant by passing through the slots 19 provided in the extreme left part of the heating tube 11 and it flows axially to the right, in the direction of the outlet nozzle 21.
  • On this nozzle is fixed an alumina tube 41, of small length and which extends inside the extreme right part of the heating tube 11.
  • the dense alumina tube 14 is immobilized by a cable gland 42 near the electrical contact 6. Furthermore, the cooling of the left part of the device is obtained by means of 'a circulation of water in an extense cylindrical chamber 25a.
  • the extreme left part of the heating tube 11 is directly connected to an electrical supply terminal 43, carried by the left closing flange 2, by means of a braid 44.
  • a thermocouple 45 used for regulation, can be also inserted axially inside the heating tube 11, through the left closing flange 2. It is also possible to introduce longitudinally, into the heating tube 11, another tube for heating or preheating any fluid, through this tube of refractory material.
  • FIG. 6 represents a preferred embodiment of the invention in which the enclosure (right part of the figure) has a structure similar to that of the preceding figures, the introduction of hot gas being however made by the end opening of the heating tube, while the electrical supply means of the heating tube (left part of the figure), have a structure adapted to the internal expansion movements of the heating tube.
  • the apparatus according to this variant comprises an outer protective casing 101 surrounding the enclosure formed by the tubes 102 and 104 arranged coaxially, for example made of refractory steel, between which a gas circulation space 103 is provided.
  • This space 103 has the shape of a helix, machined in the external surface of 104, the gas being introduced through the orifice 123 at the end (left in the figure) of the enclosure, and leaving through the orifice 120 (right end in the figure) to follow the channel 105 located between the inner wall of the tube 104 and a first alumina tube 106, inert, not heating, the gas thus returning to the level of the left end. It then follows the channel 107 located between the first tube and a second tube 108 of the same kind as 107.
  • the gas thus returns to the level of the right end of the enclosure or a passage 121 is provided for returning the gas in contact with the outer face of the heating tube 111 in the channel 109, located between the last and the second alumina tube 108.
  • the gas then enters the interior of the heating tube 1 1 1 via openings 110 located in the centralizer 124 which also brings the electrical voltage to the heating tube 1 1 by the electrical contact 126.
  • the flow of current takes place at the level of the annular rim 112.
  • the gas passes through the entire heating tube and is evacuated (at the right end of the figure), through the opening 114 placed in the axis of the heating tube 111 , in the flange 115.
  • a nozzle 116 the channel 1 17 is placed in the extension of the channel 114, said nozzle also comprising a fuel supply channel 118.
  • This nozzle makes it possible to use hot gas, for example oxygen in an oxy-fuel torch or an oxy-fuel burner.
  • the flange 115 is electrically connected to the heating tube by a washer 113, for example made of platinum, crimped at the end of the heating tube 111, for example made of lanthanum chromite.
  • the electrical circuit is closed up to the electrical connection 135, by means of the steel tubes 102 and 104, held coaxially by the other flange 127 on which the conductive parts 128 and 136 are fixed, enveloping the electrical connections.
  • the electrical contact 126 the end of which forms a centering device 124 of the heating tube 111 is electrically isolated from the contact envelope part 128 by a sliding part 125, integral with the contact 126, capable of sliding inside the part 128 against which it possibly comes into abutment at 138 under the thrust of the spring 131, thus making it possible to maintain the heating tube 111 in position, an expansion of the latter compressing said spring.
  • the end (left in the figure) of the contact 126 is connected to a flexible wire 130, for example of platinum of sufficient length to absorb the expansions of the device, the other end of which is integral with the contact 133 fixed in the parts insulators 132 and 139 from which opens the second electrical contact 134 for connecting the heating tube to electrical supply means not shown in the figure.
  • the part 132 comprises an annular housing in which the said spring 131 bears.
  • the part 136 which surrounds the insulating parts 125, 132, 139 comprises a space 137 for the circulation of cooling water at the level of the electrical contacts, in order to preserve the characteristics of the spring and the enclosure seals. It should be noted that in operation the spring 131 makes it possible to maintain the electrical contact between the heating tube 111, and the contact 126, both in contraction and in expansion.
  • a heating tube made of lanthanum chromite, zirconia, molybdenum bisilicide or silicon carbon is used.
  • carbon, graphite, molybdenum, tungsten, tantalum, silicon carbide can also be used.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Resistance Heating (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
  • Gas Burners (AREA)

Abstract

A tubular case closed at its two ends respectively by a first side wall carrying two electric supply terminals and a second side wall carrying a hot gas outlet nozzle for discharging a jet of heated oxygen. A heating tube extends axially through the case constituting a heating resistance, the wall or this heating tube being provided in one of its end portions with at least one opening for the passage of the gas to the interior of the heating tube and the outlet nozzle. The case also includes a heat exchanger of thermoconductive material and gas pre-heating means.

Description

La présente invention concerne un appareil pour la production d'un jet de gaz à haute température, comportant une enceinte, des moyens d'introduction d'un gaz dans cette enceinte, des moyens de chauffage du gaz dans l'enceinte et des moyens d'évacuation du gaz chaud de l'enceinte.The present invention relates to an apparatus for producing a jet of gas at high temperature, comprising an enclosure, means for introducing a gas into this enclosure, means for heating the gas in the enclosure and means for evacuation of hot gas from the enclosure.

Dans divers domaines industriels on utilise des jets de gaz oxydant chaud, notamment d'oxygène. Par exemple la technique d'oxycoupage met en oeuvre un chalumeau dont sort un jet d'oxygène à grande vitesse entouré par une flamme de chauffe.In various industrial fields, jets of hot oxidizing gas, in particular oxygen, are used. For example, the flame-cutting technique uses a torch from which a high-speed oxygen jet comes out surrounded by a heating flame.

Le phénomène chimique intervenant dans l'oxycoupage n'est pas très bien connu. Il apparaît probablement une oxydation du fer sous forme d'oxydes (FeO, Fe203, Fe304) oxydes qui ont une température de fusion inférieure à celle du métal. On observe en fait la présence d'une gaine liquide et brillante entre le jet d'oxygène et le front de saignée, cette gaine liquide étant entraînée par le jet d'oxygène et évacuée vers l'extérieur sous forme de gouttelettes et d'étincelles. L'oxygène doit diffuser dans cette zone liquide pour entretenir la réaction de combustion du fer. Comme cette réaction est fortement exothermique, les calories libérées servent ensuite à entretenir la haute température nécessaire à la fusion des oxydes.The chemical phenomenon involved in flame cutting is not very well known. There is probably an oxidation of iron in the form of oxides (FeO, Fe 2 0 3 , Fe 3 0 4 ) oxides which have a lower melting temperature than that of the metal. We actually observe the presence of a shiny liquid sheath between the oxygen jet and the bleeding front, this liquid sheath being entrained by the oxygen jet and discharged to the outside in the form of droplets and sparks . Oxygen must diffuse in this liquid zone to maintain the iron combustion reaction. As this reaction is highly exothermic, the calories released are then used to maintain the high temperature necessary for the fusion of the oxides.

Actuellement la flamme de chauffe périphérique est indispensable pour l'amorçage de la réaction. Après l'amorçage le rôle essentiel de cette flamme de chauffe est de maintenir l'arête supérieure du front de saignée à une température suffisante pour que la gaine de scories liquides puisse se renouveler. Toutefois les calories nécessaires étant apportées par la réaction d'oxydation du fer, la chauffe n'intervient en fait que pour éviter des riques de désamorçage.Currently the peripheral heating flame is essential for initiating the reaction. After priming, the essential role of this heating flame is to maintain the upper edge of the bleeding front at a temperature sufficient for the sheath of liquid slag to be renewed. However, the necessary calories being provided by the iron oxidation reaction, the heating in fact occurs only to avoid risk of defusing.

Il apparaît donc intéressant de pouvoir se passer de la présence permanente de cette flamme de chauffe, et/ou alors augmenter la vitesse de coupe et ceci constituant l'un des buts visée par l'invention.It therefore appears advantageous to be able to dispense with the permanent presence of this heating flame, and / or then increase the cutting speed and this constituting one of the aims of the invention.

Par ailleurs, dans d'autres secteurs industriels il est également souhaitable de pouvoir disposer d'un générateur de gaz chaud, ce gaz pouvant être un gaz oxydant par des applications telles que la métallurgie, les brûleurs oxy-combustibles, etc... ou un gaz non oxydant ou inerte, tel que l'azote, ... dans des applications, par exemple, du type traitement thermique.Furthermore, in other industrial sectors, it is also desirable to be able to have a hot gas generator, this gas being able to be an oxidizing gas by applications such as metallurgy, oxy-fuel burners, etc ... or a non-oxidizing or inert gas, such as nitrogen, etc. in applications, for example, of the heat treatment type.

Il est connu du brevet allemand 726 668 de refroidir la buse de mélange d'un chalumeau à l'aide de l'oxygène de coupe, amené autour de celle-ci dans un serpentin entourant la buse, l'oxygène étant ainsi préchauffé par récupération d'une partie de la chaleur dégagée par la réaction d'oxy-coupage.It is known from German patent 726 668 to cool the mixing nozzle of a torch using cutting oxygen, brought around the latter in a coil surrounding the nozzle, the oxygen being thus preheated by recovery part of the heat given off by the oxy-cutting reaction.

S'il est envisagé dans ce brevet de récupérer une partie de la chaleur dégagée par la coupe, ceci a essentiellement pour butde refroidir la buse de coupe et éviter un circuit supplémentaire de refroidissement à l'eau.If it is envisaged in this patent to recover part of the heat given off by the cutting, this essentially has the aim of cooling the cutting nozzle and avoiding an additional water cooling circuit.

La présente invention a donc pour but de fournir un appareil de conception particulièrement simple, ayant un bon rendement thermique et permettant de produire à sa sortie un jet de gaz à une température très élevée, pouvant atteindre 1 600°C au plus.The object of the present invention is therefore to provide a device of particularly simple design, having good thermal efficiency and making it possible to produce at its outlet a jet of gas at a very high temperature, which can reach 1600 ° C. at most.

L'appareil selon l'invention est caractérisé en ce que les moyens de chauffage du gaz sont constitués, d'une part, d'un tube chauffant s'étendant longitudinalement dans l'enceinte et constituant une résistance de chauffage, ce tube comportant des moyens de liaison électrique pour la connexion de cette résistance à des moyens d'alimentation électrique, et d'autre part, de moyens échangeurs de chaleur disposés autour du tube chauffant et en contact thermique avec celui-ci, lesdits moyens formant au moins une canalisation de conduite du gaz s'étendant depuis les moyens d'introduction et débouchant à l'intérieur du tube par une ouverture située à proximité d'une extrémité du tube chauffant, dont une seconde extrémité communique avec les moyens d'évacuation du gaz chaud de l'enceinte, le gaz étant ainsi chauffé dans les moyens échangeurs de chaleur avant der passer à l'intérieur du tube chauffant pour s'écouler finalement à travers les moyens d'évacuation du gaz chaud de l'enceinte.The apparatus according to the invention is characterized in that the gas heating means consist, on the one hand, of a heating tube extending longitudinally in the enclosure and constituting a heating resistor, this tube comprising electrical connection means for the connection of this resistor to electrical supply means, and on the other hand, heat exchanger means arranged around the heating tube and in thermal contact therewith, said means forming at least one pipe gas pipe extending from the introduction means and opening into the interior of the tube through an opening located near one end of the heating tube, a second end communicates with the means for discharging the hot gas from the enclosure, the gas thus being heated in the heat exchanger means before passing inside the heating tube to finally flow through the means for removing the hot gas from the enclosure.

On décrira ci-après, à titre d'exemples non limitatifs, diverses formes d'exécution de la présente invention, en référence au dessin annexé sur lequel:

  • la figure 1 est une vue en coupe axiale d'un appareil pour la production d'un jet de gaz à haute température, utilisable notamment pour une opération d'oxycoupage;
  • les figures 2, 3, 4, 5 et 6 sont des vues en coupe de variantes d'exécution de l'appareil.
Various embodiments of the present invention will be described below, by way of non-limiting examples, with reference to the appended drawing in which:
  • Figure 1 is an axial sectional view of an apparatus for producing a gas jet at high temperature, usable in particular for an oxygen cutting operation;
  • Figures 2, 3, 4, 5 and 6 are sectional views of alternative embodiments of the device.

L'appareil représenté sur la figure 1 comprend une enceinte tubulaire 1, par exemple en acier inoxydable ou en matière réfractaire, dont les deux extrémités opposées sont respectivement fermées par des flasques transversaux 2 et 3. Le flasque de fermeture droit 3 est soudé sur l'extrémité droite de l'enceinte tubulaire 1 tandis que le flasque gauche 2 est monté de manière amovible sur une bride 4 soudée à l'extrémité gauche de l'enceinte 1 et il est fixé sur cette bride 4 au moyen de boulons 5. Ce flasque de fermeture 2 constitue un support pour deux bornes d'alimentation électrique dont l'une fait partie d'un contact électrique 6 engagé à l'intérieur de l'enceinte 1, monté à coulissement axial dans le flasque 2 et qui est sollicité vers l'intérieur de l'enceinte par un ressort 7 comprimé entre deux rondelles 8 et 9, par exemple en alumine. La rondelle 8 est maintenue en appui contre un collet 6a du contact 6 tandis que le manchon isolant 9 est engagé à travers la partie centrale du flasque de fermeture 2. Le contact 6 fait saillie axialement à l'extérieur du flasque de fermeture 2 et son extrémité externe constitue une borne pouvant être raccordée au pôle positif d'une source d'alimentation électrique continue dont le pôle négatif est relié au flasque de fermeture 2, par exemple au moyen d'une cosse immobilisée par l'un des boulons 5 formant une borne négative. Toutefois l'appareil peut fonctionner également avec une source d'alimentation électrique alternative.The apparatus shown in FIG. 1 comprises a tubular enclosure 1, for example made of stainless steel or of refractory material, the two opposite ends of which are closed by transverse flanges 2 and 3 respectively. The straight closing flange 3 is welded to the right end of the tubular enclosure 1 while the left flange 2 is removably mounted on a flange 4 welded to the left end of the enclosure 1 and it is fixed to this flange 4 by means of bolts 5. This closing flange 2 constitutes a support for two electrical supply terminals, one of which forms part of an electrical contact 6 engaged inside the enclosure 1, mounted to slide axially in the flange 2 and which is biased towards inside the enclosure by a spring 7 compressed between two washers 8 and 9, for example made of alumina. The washer 8 is held in abutment against a collar 6a of the contact 6 while the insulating sleeve 9 is engaged through the central part of the closing flange 2. The contact 6 projects axially outside the closing flange 2 and its outer end constitutes a terminal which can be connected to the positive pole of a DC power source, the negative pole of which is connected to the closing flange 2, for example by means of a terminal immobilized by one of the bolts 5 forming a negative terminal. However, the device can also operate with an alternative power source.

A l'intérieur de l'enceinte 1 est logé un élément chauffant 11 constitué par un tube en un matériau céramique tel que la zircone ou le chromite de lanthane ou les deux associés par exemple. Un tel composé céramique présente la particularité d'être à la fois réfractaire (fusion vers 2 500°C) et conducteur électrique dès la température ambiante. Ce tube en céramique est constitué, de préférence, d'une partie centrale résistante et de parties extrêmes conductrices ayant une résistivité environ dix fois plus faible que celle de la partie centrale. Les parties extrêmes à faible résistivité peuvent comporter, sur le tube en céramique à résistivité constante, des zones externes platinées. Toutefois, suivant une variante, le tube 11 pourrait être entièrement résistant électriquement.Inside the enclosure 1 is housed a heating element 11 constituted by a tube made of a ceramic material such as zirconia or lanthanum chromite or the two associated for example. Such a ceramic compound has the particularity of being both refractory (melting around 2,500 ° C.) and electrical conductor from room temperature. This ceramic tube preferably consists of a part resistant central and end conductive parts having a resistivity about ten times lower than that of the central part. The extreme parts with low resistivity may comprise, on the ceramic tube with constant resistivity, platinum-plated external zones. However, according to a variant, the tube 11 could be entirely electrically resistant.

Le tube chauffant en céramique 11 est emboîté, à son extrémité droite, dans un logement 3a de même diamètre prévu dans la face frontale interne du fiasque de fermeture droit 3 et il est appliqué contre le fond de ce logement 3a sous l'effet de la pression exercée par le contact 6 sur son extrémité opposée, sous l'action du ressort 7. En fait ce contact 6 est appliqué contre la face frontale d'un embout conducteur 12 lui-même en appui contre l'extrémité gauche du tube chauffant en céramique 11. La partie extrême gauche du tube chauffant 11 et la rondelle conductrice 12 sont logées dans l'évidement interne d'une bague 13 en alumine engagée dans l'enceinte 1 et dont le diamètre externe correspond au diamètre interne de cette enceinte.The ceramic heating tube 11 is fitted, at its right end, into a housing 3a of the same diameter provided in the internal front face of the right closing flange 3 and it is applied against the bottom of this housing 3a under the effect of the pressure exerted by the contact 6 on its opposite end, under the action of the spring 7. In fact this contact 6 is applied against the front face of a conductive end piece 12 itself pressing against the left end of the heating tube in ceramic 11. The extreme left part of the heating tube 11 and the conductive washer 12 are housed in the internal recess of an alumina ring 13 engaged in the enclosure 1 and whose external diameter corresponds to the internal diameter of this enclosure.

Le tube chauffant en céramique 11 peut avoir ou non une surface externe usinée. Cette surface peut, par exemple, présenter un filetage ou encore des cannelures longitudinales.The ceramic heating tube 11 may or may not have a machined outer surface. This surface may, for example, have a thread or even longitudinal grooves.

Le tube chauffant en céramique 11 est entouré, sur la plus grande partie de sa longueur, par un échangeur de chaleur en matériau thermoconducteur. Cet échangeur de chaleur peut être constitué par au moins un tube interne 14 en matériau thermoconducteur dense, (par exemple en alumine ou chromite de lanthane) lequel est lui-même entouré par un tube externe 15 en matériau thermoconducteur poreux, (par exemple en alumine poreuse). Enfin on peut prévoir éventuellement un enroulement de feutre de zircone 16 entre le tube externe 15 en alumine poreuse et l'enceinte tubulaire 1.The ceramic heating tube 11 is surrounded, over most of its length, by a heat exchanger made of thermally conductive material. This heat exchanger can be constituted by at least one internal tube 14 made of dense thermally conductive material, (for example made of alumina or lanthanum chromite) which is itself surrounded by an external tube 15 made of porous thermally conductive material, (for example made of alumina porous). Finally, a winding of zirconia felt 16 can optionally be provided between the external tube 15 made of porous alumina and the tubular enclosure 1.

Le gaz qui doit être chauffé, tel que de l'oxygène ou de l'air par exemple, s'écoule à travers un serpentin externe 17 qui est enroulé autour de l'enceinte tubulaire 1 et en contact thermique avec elle-ci. Le gaz est introduit dans le serpentin 17 à son extrémité gauche, c'est-à-dire celle où se trouve le contact 6, et il pénètre à l'intérieur de l'enceinte 1, à l'extrémité droite du serpentin qui communique avec l'intérieur de l'enceinte 1, par l'intermédiaire d'un trou 18 percé à cet endroit dans la paroi de cette enceinte. Le gaz qui pénètre dans l'enceinte 1 à son extrémité droite, s'écoule ensuite, dans les canalisations 117, 118 comme il est indiqué par les flèches, longitudinalement de la droite vers la gauche, à travers le tube d'alumine poreuse externe 15 qui peut présenter éventuellement des rainures longitudinales pour faciliter cet écoulement, et éventuellement à travers l'enroulement de feutre de zircone 16 si celui-ci est présent. A l'extrémité gauche du tube en alumine poreuse 15 le gaz sort dans un espace délimité entre cet extrémité gauche et la bague 13 en alumine, puis il inverse son sens d'écoulement en passant, de la gauche vers la droite, entre le tube alumine dense 14 et le tube chauffant en céramique 11. Cet écoulement peut être facilité par la présence de rainures longitudinales ou d'un filetage, sur la surface externe du tube chauffant 11 ou sur la surface interne du tube en alumine dense 14. Dans sa partie droite le tube chauffant 11 présente , dans sa paroi, au moins une ouverture 19 qui permet au gaz de passer à l'intérieur du tube 11. Le gaz chaud peut alors sortir de l'appareil, en s'écoulant, sous la forme d'un jet axial, à travers une buse de sortie 21 fixée de manière amovible, au moyen de vis 22, sur le flasque de fermeture droit 3. Cette buse 21 peut être une buse d'oxycoupage bien connue, refroidie ou non. Dans l'exemple non limitatif illustré sur la figure 1 cette buse 1 est refroidie par de l'eau amenée par une canalisation 23. Elle présente également un orifice d'entrée 24 pour le raccordement à une source de gaz de chauffe.The gas which must be heated, such as oxygen or air for example, flows through an external coil 17 which is wound around the tubular enclosure 1 and in thermal contact with it. The gas is introduced into the coil 17 at its left end, that is to say the one where the contact 6 is located, and it penetrates inside the enclosure 1, at the right end of the coil which communicates with the interior of the enclosure 1, by means of a hole 18 drilled at this location in the wall of this enclosure. The gas which enters the enclosure 1 at its right end, then flows, in the pipes 117, 118 as indicated by the arrows, longitudinally from right to left, through the external porous alumina tube 15 which may optionally have longitudinal grooves to facilitate this flow, and possibly through the zirconia felt winding 16 if the latter is present. At the left end of the porous alumina tube 15 the gas leaves in a space delimited between this left end and the alumina ring 13, then it reverses its direction of flow by passing, from left to right, between the tube dense alumina 14 and the ceramic heating tube 11. This flow can be facilitated by the presence of longitudinal grooves or of a thread, on the external surface of the heating tube 11 or on the internal surface of the dense alumina tube 14. In its right side the heating tube 11 has, in its wall, at least one opening 19 which allows the gas to pass inside the tube 11. The hot gas can then leave the device, flowing, in the form an axial jet, through an outlet nozzle 21 fixed removably, by means of screws 22, on the right closing flange 3. This nozzle 21 can be a well-known flame-cutting nozzle, cooled or not. In the nonlimiting example illustrated in FIG. 1, this nozzle 1 is cooled by water supplied by a pipe 23. It also has an inlet port 24 for connection to a source of heating gas.

Lorsque l'appareil est en fonctionnement, le tube en céramique 11 est chauffé par le courant électrique passant à partir du contact 6, à travers la rondelle conductrice 12, puis sur toute la longueur du tube chauffant 11 jusqu'au flasque de fermeture gauche 2 qui est relié au pôle négatif de la source d'alimentation électrique, c'est-à-dire à la masse. Du fait du passage de ce courant électrique, le tube 11 en céramique s'échauffe dans sa partie centrale à résistivité élevé, si bien que la température de cette partie centrale peut attendre environ 1 800°C en fonctionnement normal. Les parties extrêmes du tube chauffant 11 atteignent, elles, une température inférieure à 400°C, du fait de leur résistivité beaucoup plus faible, ce qui permet de conserver un bon contact électrique. L'alimentation du tube chauffant 11 peut s'effectuer en courant alternatif ou continu, ce tube chauffant se comportant comme une résistance pure. La mesure de l'intensité et de la tension du courant permet de régler la puissance Joule fournie au tube chauffant 11 et par conséquent la puissance calorifique qui peut être absorbée par le gaz. Les tubes 14 en alumine dense et 15 en alumine poreuse s'échauffent conjointement avec le tube chauffant interne 11 et échauffant à leur tour l'enceinte 1 et le serpentin 17. Le gaz s'écoulant dans le serpentin 17 est préchauffé progressivement dans celui-ci, il pénètre dans l'enceinte 1, à la sortie du serpentin 17, puis continue à s'échauffer lors de son écoulement d'abord de la droite vers le gauche à travers le tube d'alumine poreuse externe 15 et éventuellement l'enroulement de feutre de zircone 16, puis de la gauche vers la droite entre le tube d'alumine dense 14 et le tube chauffant 11. De ce fait le jet de gaz sortant de la buse 21 peut atteindre une température voisine de 1 600°C.When the appliance is in operation, the ceramic tube 11 is heated by the electric current passing from the contact 6, through the conductive washer 12, then over the entire length of the heating tube 11 to the left closing flange 2 which is connected to the negative pole of the electrical power source, i.e. to ground. Due to the passage of this electric current, the ceramic tube 11 heats up in its central part with high resistivity, so that the temperature of this central part can wait for approximately 1,800 ° C. in normal operation. The end parts of the heating tube 11 reach a temperature below 400 ° C, due to their much lower resistivity, which allows good electrical contact to be maintained. The heating tube 11 can be supplied with alternating or direct current, this heating tube behaving like a pure resistance. Measuring the intensity and the voltage of the current makes it possible to adjust the Joule power supplied to the heating tube 11 and consequently the calorific power which can be absorbed by the gas. The tubes 14 of dense alumina and 15 of porous alumina heat up together with the internal heating tube 11 and in turn heat the enclosure 1 and the coil 17. The gas flowing in the coil 17 is gradually preheated therein. ci, it enters the enclosure 1, at the outlet of the coil 17, then continues to heat up when it flows first from the right to the left through the external porous alumina tube 15 and possibly the winding of zirconia felt 16, then from left to right between the dense alumina tube 14 and the heating tube 11. As a result, the gas jet leaving the nozzle 21 can reach a temperature in the region of 1600 ° C. .

Bien que l'on utilise de préférence, entre le tube chauffant central et l'enceinte externe 1, des tubes 14 et 15 coaxiaux en alumine, il est également possible d'employer des tubes en une autre matière, par exemple en chromite de lanthane. Le tube 14 en alumine dense est avantageusement utilisé car il présente de bonnes caractéristiques thermiques, un coefficient de dilation voisin de celui du chromite de lanthane constituant le tube chauffant 11 et il supporte également les très hautes températures. Le tube d'alumine poreuse 15 qui est de préférence utilisé autour du tube 14 en alumine dense, offre l'avantage d'être un meilleur isolant thermique que l'alumine dense.Although coaxial alumina tubes 14 and 15 are preferably used between the central heating tube and the external enclosure 1, it is also possible to use tubes of another material, for example lanthanum chromite . The dense alumina tube 14 is advantageously used because it has good thermal characteristics, an expansion coefficient close to that of the lanthanum chromite constituting the heating tube 11 and it also withstands very high temperatures. The porous alumina tube 15 which is preferably used around the dense alumina tube 14, offers the advantage of being a better thermal insulator than the dense alumina.

L'enroulement de feutre de zircone 16 qui est prévu éventuellement entre le tube d'alumine poreuse 15 et l'enceinte 1, permet de renforcer l'isolation et de fournir également une surface d'échange important au gaz qui se préchauffe également en le traversant.The winding of zirconia felt 16 which is optionally provided between the porous alumina tube 15 and the enclosure 1, makes it possible to reinforce the insulation and also to provide a significant exchange surface for the gas which also preheats on passing through it.

Comme il a été décrit précédemment, le contact électrique 6 est sollicité élastiquement par le ressort 7 contre le tube chauffant 11, par l'intermédiaire de la rondelle conductrice 12. Ceci permet la dilatation et la contraction axiales du du tube chauffant 11 tout en conservant un bon contact électrique. Cette dilatation ou contraction qui est transmise à la partie externe du contact 6, peut être éventuellement utilisée pour la régulation de la température du tube chauffant 11.As described above, the electrical contact 6 is resiliently biased by the spring 7 against the heating tube 11, by means of the conductive washer 12. This allows the axial expansion and contraction of the heating tube 11 while retaining good electrical contact. This expansion or contraction which is transmitted to the external part of the contact 6, can optionally be used for regulating the temperature of the heating tube 11.

La partie extrême gauche de l'enceinte 1 où se trouve situé le contact électrique 6, est avantageusement refroidie par une circulation d'eau dans un tube interne 25 fixé, par exemple, à la face interne de la bride 4. Pour parfaire la présentation de l'ensemble de l'appareil, le serpentin 17 qui est parcouru par le gaz encore relativement froid, est avantageusement recouvert d'une couche 26 en une matière isolante thermiquement, cette dernière étant à son tour entourée par un cylindre externe 27.The extreme left part of the enclosure 1 where the electrical contact 6 is located, is advantageously cooled by a circulation of water in an internal tube 25 fixed, for example, to the internal face of the flange 4. To perfect the presentation of the entire apparatus, the coil 17 which is traversed by the still relatively cold gas, is advantageously covered with a layer 26 of a thermally insulating material, the latter being in turn surrounded by an external cylinder 27.

Dans la variante d'exécution de l'appareil qui est illustrée sur la figure 2 un tube 28 en alumine dense est logé coaxialement à l'intérieur du tube chauffant 11 et ce tube 28 est engagé, par son extrémité droite, dans un logement de même diamètre prévu dans la face interne du flasque de fermeture droit 3. Ce flasque est, dans ce cas, monté amovible sur un support cylindrique 29 soudé à l'extrémité droite de l'enceinte 1, la fixation du flasque amovible 3 sur le support 29 étant réalisée au moyen de vis 31. Dans la face interne du flasque de fermeture amovible 3 sont ménagés, d'une part, le logement 3a, de diamètre relativement grand, recevant l'extrémité droite du tube chauffant 11, et d'autre part un autre logement 3b, de plus petit diamètre que le précédent mais plus profond, recevant l'extrémité droite du tube interne 28 en alumine dense. Une coupelle en platine 32 est interposée entre la partie extrême droite du tube chauffant 11 et son logement 3a dans le flasque de fermeture 3.In the variant embodiment of the device which is illustrated in FIG. 2, a dense alumina tube 28 is housed coaxially inside the heating tube 11 and this tube 28 is engaged, by its straight end, in a housing for same diameter provided in the internal face of the right closing flange 3. This flange is, in this case, removably mounted on a cylindrical support 29 welded to the right end of the enclosure 1, the fixing of the removable flange 3 on the support 29 being produced by means of screws 31. In the internal face of the removable closing flange 3 are formed, on the one hand, the housing 3a, of relatively large diameter, receiving the right end of the heating tube 11, and on the other share another housing 3b, of smaller diameter than the previous one but deeper, receiving the right end of the inner tube 28 of dense alumina. A platinum cup 32 is interposed between the extreme right part of the heating tube 11 and its housing 3a in the closing flange 3.

Par ailleurs dans la forme d'exécution illustrée sur la figure 2 le tube interne 14 en alumine dense a une longueur supérieure à celle du tube externe 15 en alumine poreuse. En fait le tube 15 en alumine poreuse s'etend jusqu'à la face frontale gauche 29a du support 29 tandis que le tube 14 en alumine dense pénètre à l'intérieur de ce support 29 et le traverse totalement pour venir en contact, à son extrémité droite avec la face interne du flasque de fermeture amovible 3. Une rondelle d'amiante est interposée entre la partie extrême droite du tube 14 en alumine dense et la paroi interne cylindrique du support 29, cette rondelle étant serrée axialement par une collerette coaxiale interne 30 du flasque de fermeture droit 3.Furthermore, in the embodiment illustrated in FIG. 2, the internal tube 14 of dense alumina has a length greater than that of the external tube 15 of porous alumina. In fact the tube 15 made of porous alumina extends to the left front face 29a of the support 29 while the tube 14 of dense alumina penetrates inside this support 29 and passes completely through it to come into contact at its straight end with the internal face of the removable closing flange 3. An asbestos washer is interposed between the extreme right part of the dense alumina tube 14 and the cylindrical internal wall of the support 29, this washer being axially tightened by an internal coaxial flange 30 of the right closing flange 3.

Le tube interne 28 en alumine dense s'arrête, à l'intérieur du tube chauffant 11, à une certaine distance de l'extrémité gauche de celui-ci. Par ailleurs le contact électrique 6 prend appui sur un embout conducteur 33 contenant une coupelle en platine 34 qui coiffre l'extrémité gauche du tube chauffant 11 qui est platinée. L'embout conducteur 33 est prolongé vers la droite par un doigt axial 35 s'étendant en partie à l'intérieur du tube interne 28 en alumine dense.The inner tube 28 of dense alumina stops, inside the heating tube 11, at a certain distance from the left end of the latter. Furthermore, the electrical contact 6 is supported on a conductive tip 33 containing a platinum cup 34 which covers the left end of the heating tube 11 which is platinized. The conductive end piece 33 is extended to the right by an axial finger 35 extending partly inside the inner tube 28 of dense alumina.

Dans sa partie extrême gauche le tube interne 28 en alumine dense présente au moins une fente longitudinale 36 permettant le passage du gaz à l'intérieur du tube 28.In its extreme left part, the inner tube 28 of dense alumina has at least one longitudinal slot 36 allowing the passage of the gas inside the tube 28.

Avec cette disposition le gaz qui pénètre à l'intérieur du tube chauffant 11, à travers les trous ou fentes 19 prévus dans sa partie extrême droite, s'écoule une nouvelle fois à l'intérieur du tube 11 vers la gauche, dans l'espace délimité entre ce tube chauffant et le tube interne 28 en alumine dense, puis il passe à travers la ou les fentes 36 prévues dans la partie extrême gauche du tube 28 pour s'écouler de nouveau à l'intérieur du tube 28 de la gauche vers la droite en direction de la base de sortie 21.With this arrangement, the gas which penetrates inside the heating tube 11, through the holes or slots 19 provided in its extreme right part, again flows inside the tube 11 to the left, into the space delimited between this heating tube and the internal tube 28 made of dense alumina, then it passes through the slot or slots 36 provided in the extreme left part of the tube 28 to flow again inside the tube 28 from the left to the right towards the exit base 21.

La figure 3 illustre une variante d'exécution de l'appareil semblable à celle de la figure 2 mais dans laquelle la buse d'oxycoupage 21 et le contact électrique 10 ne sont pas refroidis par une circulation d'eau. Dans ce cas le contact 6 s'étend à l'intérieur d'un radiateur à ailettes 37 monté sur le flasque de fermeture gauche 2 et qui assure ainsi le refroidissement naturel du contact 6. Par ailleurs, dans cette variante l'appareil ne comporte plus de serpentin lequel est remplacé par une chambre cylindrique 17a entourant l'échangeur de chaleur 14, 15.FIG. 3 illustrates an alternative embodiment of the apparatus similar to that of FIG. 2 but in which the oxygen cutting nozzle 21 and the electrical contact 10 are not cooled by a circulation of water. In this case the contact 6 extends inside a finned radiator 37 mounted on the left closing flange 2 and which thus ensures the natural cooling of the contact 6. Furthermore, in this variant the device does not include more coil which is replaced by a cylindrical chamber 17a surrounding the heat exchanger 14, 15.

Dans la variante d'exécution illustrée sur la figure 4 le tube chauffant 11 est immobilisé, dans sa partie extrême droite, c'est-à-dire celle qui est proche de la buse de sortie 21, au moyen d'une pince 38 en acier inoxidable avec interposition d'une bague 39 en amiante entre la partie extrême droite du tube chauffant 11 et le flasque de fermeture droit 3. Par ailleurs, dans cette forme d'exécution, le gaz est introduit dans un filetage 17b à son extrémité située du côté droit, c'est-à-dire du côté de la buse de sortie 21, ce filetage 17b étant usiné dans la surface externe de l'enceinte tubulaire 1. Le gaz pénètre à l'intérieur de l'enceinte 1 par des trous 18 situés dans la partie gauche de l'enceinte 1. De ce fait le gaz pénètrant à l'intérieur de l'enceinte 1 s'écoule de la gauche vers la droite à travers le tube d'alumine poreuse externe 15 puis de la droite vers la gauche entre le tube interne 14 en alumine dense et le tube chauffant 11, il pénètre à l'intérieur de ce tube chauffant en passant à travers les fentes 19 prévues dans la partie extrême gauche du tube chauffant 11 et il s'écoule axialement vers la droite, en direction de la buse de sortie 21. Sur cette buse est fixé un tube 41 en alumine, de petite longueur et qui s'étend à l'intérieur de la partie extrême droite du tube chauffant 11.In the alternative embodiment illustrated in FIG. 4, the heating tube 11 is immobilized, in its extreme right part, that is to say that which is close to the outlet nozzle 21, by means of a clamp 38 in stainless steel with interposition of an asbestos ring 39 between the extreme right part of the heating tube 11 and the right closing flange 3. Furthermore, in this embodiment, the gas is introduced into a thread 17b at its end located on the right side, that is to say on the side of the outlet nozzle 21, this thread 17b being machined in the external surface of the tubular enclosure 1. The gas penetrates inside the enclosure 1 by holes 18 located in the left part of the enclosure 1. As a result the gas penetrating inside the enclosure 1 flows from the left to the right through the external porous alumina tube 15 then from the right to left between the inner tube 14 of dense alumina and the heating tube 11, it penetrates inside this heated tube ant by passing through the slots 19 provided in the extreme left part of the heating tube 11 and it flows axially to the right, in the direction of the outlet nozzle 21. On this nozzle is fixed an alumina tube 41, of small length and which extends inside the extreme right part of the heating tube 11.

Dans la forme d'exécution illustrée sur la figure 4 le tube 14 en alumine dense est immobilisé par un presse-étoupe 42 à proximité du contact électrique 6. Par ailleurs, le refroidissement de la partie gauche de l'appareil est obtenu au moyen d'une circulation d'eau dans une chambre cylindrique extense 25a.In the embodiment illustrated in FIG. 4, the dense alumina tube 14 is immobilized by a cable gland 42 near the electrical contact 6. Furthermore, the cooling of the left part of the device is obtained by means of 'a circulation of water in an extense cylindrical chamber 25a.

Dans la variante d'exécution illustrée sur la figure 5 la partie extrême gauche du tube chauffant 11 est reliée directement à une borne d'alimentation électrique 43, portée par le flasque de fermeture gauche 2, par l'intermédiaire d'une tresse 44. Par ailleurs, un thermocouple 45, servant à la régulation, peut être également introduit axialement à l'intérieur du tube chauffant 11, à travers le flasque de fermeture gauche 2. On peut également introduire longitudinalement, dans le tube chauffant 11, un autre tube pour le chauffage ou préchauffage d'un fluide quelconque, au travers de ce tube en matériau réfractaire.In the alternative embodiment illustrated in FIG. 5, the extreme left part of the heating tube 11 is directly connected to an electrical supply terminal 43, carried by the left closing flange 2, by means of a braid 44. In addition, a thermocouple 45, used for regulation, can be also inserted axially inside the heating tube 11, through the left closing flange 2. It is also possible to introduce longitudinally, into the heating tube 11, another tube for heating or preheating any fluid, through this tube of refractory material.

La figure 6 représente un mode préférentiel de l'invention dans lequel l'enceinte (partie droite de la figure) a une structure semblable à celle des figures précédentes, l'introduction de gaz chaud se faisant cependant par l'ouverture d'extrémité du tube chauffant, tandis que les moyens d'alimentation électrique du tube chauffant (partie gauche de la figure), ont une structure adaptée aux mouvements de dilatation interne du tube chauffant.FIG. 6 represents a preferred embodiment of the invention in which the enclosure (right part of the figure) has a structure similar to that of the preceding figures, the introduction of hot gas being however made by the end opening of the heating tube, while the electrical supply means of the heating tube (left part of the figure), have a structure adapted to the internal expansion movements of the heating tube.

L'appareil selon cette variante comporte une enveloppe extérieure 101 de protection entourant l'enceinte formée par les tubes 102 et 104 disposés coaxialement, par exemple en acier réfractaire, entre lesquels un espace de circulation des gaz 103 est ménagé. Cet espace 103 a la forme d'une hélice, usinée dans la surface externe de 104, le gaz étant introduit par l'orifice 123 au niveau de l'extrémité (gauche sur la figure) de l'enceinte, et sortant par l'orifice 120 (extrémité droite sur la figure) pour suivre le canal 105 situé entre la paroi intérieure du tube 104 et un premier tube 106 en alumine, inerte, non chauffant, le gaz revenant ainsi au niveau de l'extrémité gauche. Il suit alors le canal 107 situé entre le premier tube et un second tube 108 de même nature que 107. Le gaz revient ainsi au niveau de l'extrémité droite de l'enceinte ou un passage 121 est prévu pour renvoyer le gaz au contact de la face extérieure du tube chauffant 111 dans le canal 109, situé entre le dernier et le second tube en alumine 108. Le gaz pénètre ensuite à l'intérieur du tube chauffant 1 1 1 par l'intermédiaire d'ouvertures 110 situées dans le centreur 124 qui amène également la tension électrique au tube chauffant 1 1 par le contact électrique 126.The apparatus according to this variant comprises an outer protective casing 101 surrounding the enclosure formed by the tubes 102 and 104 arranged coaxially, for example made of refractory steel, between which a gas circulation space 103 is provided. This space 103 has the shape of a helix, machined in the external surface of 104, the gas being introduced through the orifice 123 at the end (left in the figure) of the enclosure, and leaving through the orifice 120 (right end in the figure) to follow the channel 105 located between the inner wall of the tube 104 and a first alumina tube 106, inert, not heating, the gas thus returning to the level of the left end. It then follows the channel 107 located between the first tube and a second tube 108 of the same kind as 107. The gas thus returns to the level of the right end of the enclosure or a passage 121 is provided for returning the gas in contact with the outer face of the heating tube 111 in the channel 109, located between the last and the second alumina tube 108. The gas then enters the interior of the heating tube 1 1 1 via openings 110 located in the centralizer 124 which also brings the electrical voltage to the heating tube 1 1 by the electrical contact 126.

Le passage du courant s'effectue au niveau du rebord annulaire 112. Le gaz traverse tout le tube chauffant et s'évacue (à l'extrémité droite de la figure), par l'ouverture 114 placée dans l'axe du tube chauffant 111, dans le flasque 115. Sur celui-ci est fixé, dans l'exemple de la figure une buse 116 dont le canal 1 17 est placé dans le prolongement du canal 114, ladite buse comportant également un canal 118 d'amenée de combustible.The flow of current takes place at the level of the annular rim 112. The gas passes through the entire heating tube and is evacuated (at the right end of the figure), through the opening 114 placed in the axis of the heating tube 111 , in the flange 115. On this is fixed, in the example of the figure a nozzle 116, the channel 1 17 is placed in the extension of the channel 114, said nozzle also comprising a fuel supply channel 118.

Cette buse permet d'utiliser le gaz chaud, par exemple l'oxygène dans un chalumeau oxy-combustible ou un brûleur oxy-combustible.This nozzle makes it possible to use hot gas, for example oxygen in an oxy-fuel torch or an oxy-fuel burner.

Le flasque 115 est électriquement relié au tube chauffant par une rondelle 113 par exemple en platine, sertie à l'extrémité du tube chauffant 111, par exemple en chromite de lanthane.The flange 115 is electrically connected to the heating tube by a washer 113, for example made of platinum, crimped at the end of the heating tube 111, for example made of lanthanum chromite.

Le circuit électrique est refermé jusqu'à la connexion électrique 135, par l'intermédiaire des tubes en acier 102 et 104, maintenus coaxialement par l'autre flasque 127 sur lequel sont fixées les pièces conductrices 128 et 136, enveloppant les connexions électriques.The electrical circuit is closed up to the electrical connection 135, by means of the steel tubes 102 and 104, held coaxially by the other flange 127 on which the conductive parts 128 and 136 are fixed, enveloping the electrical connections.

Le contact électrique 126 dont l'extrémité forme un centreur 124 du tube chauffant 111 est isolé électriquement de la pièce enveloppe de contact 128 par une pièce coulissante 125, solidaire du contact 126, pouvant coulisser à l'intérieur de la pièce 128 contre laquelle elle vient éventuellement en butée en 138 sous la poussée du ressort 131, permettant ainsi de maintenir en position le tube chauffant 111, une dilatation de celui-ci comprimant ledit ressort. L'extrémité (gauche sur la figure) du contact 126 est reliée à un fil souple 130, par exemple en platine de longueur suffisante pour absorber les dilatations de l'appareil, dont l'autre extrémité est solidaire du contact 133 fixé dans les pièces isolantes 132 et 139 d'où débouche le second contact électrique 134 de connexion du tube chauffant à des moyens d'alimentation électrique non représentés sur la figure. La pièce 132 comporte un logement annulaire dans lequel vient s'appuyer ledit ressort 131. La pièce 136 qui entoure les pièces isolantes 125, 132, 139 comporte un espace 137 pour la circulation d'eau de refroidissement au niveau des contacts électriques, afin de préserver les caractéristiques du ressort et des joints d'étanchéité de l'enceinte. Il faut noter qu'en fonctionnement le ressort 131 permet de maintenir le contact électrique entre le tube chauffant 111, et le contact 126, tant en contraction qu'en dilatation.The electrical contact 126, the end of which forms a centering device 124 of the heating tube 111 is electrically isolated from the contact envelope part 128 by a sliding part 125, integral with the contact 126, capable of sliding inside the part 128 against which it possibly comes into abutment at 138 under the thrust of the spring 131, thus making it possible to maintain the heating tube 111 in position, an expansion of the latter compressing said spring. The end (left in the figure) of the contact 126 is connected to a flexible wire 130, for example of platinum of sufficient length to absorb the expansions of the device, the other end of which is integral with the contact 133 fixed in the parts insulators 132 and 139 from which opens the second electrical contact 134 for connecting the heating tube to electrical supply means not shown in the figure. The part 132 comprises an annular housing in which the said spring 131 bears. The part 136 which surrounds the insulating parts 125, 132, 139 comprises a space 137 for the circulation of cooling water at the level of the electrical contacts, in order to preserve the characteristics of the spring and the enclosure seals. It should be noted that in operation the spring 131 makes it possible to maintain the electrical contact between the heating tube 111, and the contact 126, both in contraction and in expansion.

Pour le chauffage des gaz oxydants, on utilise un tube chauffant en chromite de lanthane, zircone, bisiliciure de molybdène ou carbone de silicium. Pour les gaz neutres ou réducteurs, on peut utiliser également le carbone, le graphite, molybdène, tungstène, tantale, carbure de silicium.For the heating of oxidizing gases, a heating tube made of lanthanum chromite, zirconia, molybdenum bisilicide or silicon carbon is used. For neutral or reducing gases, carbon, graphite, molybdenum, tungsten, tantalum, silicon carbide can also be used.

D'une manière générale et quel que soit le gaz, on utilisera un matériau qui, par effet Joule, peut atteindre au plus une température de l'ordre de 2.300°C.In general and whatever the gas, a material will be used which, by the Joule effect, can reach at most a temperature of the order of 2,300 ° C.

Afin d'augmenter la température du gaz sortant de l'appareil, à débit constant, il est souhaitable de placer plusieurs tubes chauffants, coaxialement, avec une circulation de gaz entre eux sous forme de chicanes longitudinales (comme c'est le cas entre les tubes 106, 108, et 111) ou par usinage d'un canal hélicoïdal à la surface d'un tube qui vient se glisser exactement dans l'autre, ou a peu près (comme c'est le cas pour les tubes 102 et 104).In order to increase the temperature of the gas leaving the device, at constant flow, it is desirable to place several heating tubes, coaxially, with a gas circulation between them in the form of longitudinal baffles (as is the case between the tubes 106, 108, and 111) or by machining a helical channel on the surface of a tube which comes to slip exactly into the other, or approximately (as is the case for tubes 102 and 104 ).

Claims (26)

1. Apparatus for producing a jet of gas at high temperature comprising a tubular enclosure, means for feeding a gas into this enclosure, means for heating the gas within the enclosure and means for discharging the hot gas from the enclosure, characterised in that the gas heating means consist on the one hand of a heating tube (11) extending longitudinally within the enclosure (1) and forming a heating resistance, this tube (11) comprising electrical connecting means for connection of this resistance to electrical supply means and on the other hand heat exchanger means (14, 15, 16, 17) arranged around the heating tube and in thermal contact therewith, the said exchanger means (14, 15, 16, 17) forming at least one gas ducting channel (117, 118) extending from the infeed means (18) and opening into the inside of the tube via an opening (19; 36) situated close to one end of the heating tube (11) the other end of which is in communication with the means for discharging the hot gas from the enclosure, the gas thus being heated within the heat exchanger means before passing to the inside of the heating tube, to flow finally through the means for discharging the hot gas from the enclosure.
2. Apparatus according to claim 1, characterised in that the opening of the heating tube is formed by one of the ends of the said tube.
3. Apparatus according to claim 1, characterised in that the opening of the heating tube is formed in the lateral surface of the said tube.
4. Apparatus according to one of claims 1 to 3, characterised in that the means for discharging the hot gas from the enclosure are formed by a nozzle connected to the outlet end of the heating tube.
5. Apparatus according to one of claims 1 to 4, characterised in that it further comprises gas preheating means (17, 17a, 17b) at least partially surrounding the enclosure so that the gas may be preheated before penetrating into the enclosure.
6. Apparatus according to one of claims 1 to 5, characterised in that the enclosure is closed at its two ends respectively by two transverse plates, a first plate carrying two terminals insulated from each other, for connection to the electrical supply means, and a second plate traversed by the means for discharging the hot gas from the enclosure.
7. Apparatus according to one of claims 1 to 6, characterised in that the heating tube (11) is of a material selected from one or more material such as zirconia, lanthanum chromite, silicon carbide, molybdenum disilicide, carbon, graphite, molybdenum, tungsten and tantalum.
8. Apparatus according to one of the claims 1 to 7, characterised in that the heating tube (11) comprises a resistive central part able to heat up by the Joule effect and at least one end of a material of low electrical resistivity.
9. Apparatus according to any one of the preceding claims, characterised in that the heat exchanger means are constituted by at least one internal tube (14) of dense thermoconductive material which is itself surrounded by an external tube (15) of thermoconductive material.
10. Apparatus according to claim 9, characterised in that it comprises a wrapping of zirconia felt (16) around the external tube (15) of porous alumina.
11. Apparatus according to one of claims 6 to 10, characterised in that the gas heating means comprising preheating means (17) the entry of which into the enclosure (1) is situated at the side of the first plate (2) carrying electrical connection means, their outlet end being in communication with the inside of the tubular enclosure (1) via a hole (18) situated at the side of the second closure plate (3) carrying the outlet nozzle (21), the heating tube (11) being pierced by at least one gas passage hole or slot (19) situated on the side of the second closure plate (3).
12. Apparatus according to claim 6, characterised in that the opening (19) is situated on the side of the second closure plate (3).
13. Apparatus according to one of claims 6 to 11, characterised in that the inlet of the gas preheating means (17) is situated on the side of the second closure plate (3) carrying the outlet nozzle (21), their outlet end being in communication with the inside of the tubular enclosure (1) via a hole (18) situated on the side of the firtst closure plate (2), the heating tube (11) being pierced by at least one hole or slot (19) in its extreme portion facing towards the first closure plate (2).
14. Apparatus according to any one of the preceding claims, characterised in that a screwthread or longitudinal grooves (103) are provided for passage of the gas, within the heat exchanger means (102, 104, 106, 108) in the outer and/or inner surface of at least one of the tubes (102, 104, 106, 108) constituting the said heat exchanger means.
15. Apparatus according to one of the claims 6 to 14, characterised in that a tube (28) of thermoconductive material is axially engaged in the heating tube (11) in abutment against the second closure plate (3) and this refractory tube (28) terminates at a distance from the end of the heating tube (11) which faces towards the first closure plate (2).
16. Apparatus according to claim 15, characterised in that the internal tube of thermoconductive material (28) extends over the greater part of the length of the heating tube (11) to close to its end facing towards the first closure plate (2), and the tube (28) is pierced in this extreme part by at least one hole or slot (36) for passage of the gas in the direction of the outlet nozzle (21).
17. Apparatus according to claim 6, characterised in that the first closure plate (2) carries in its central portion an insulating sleeve (9) which is traversed by an electrical contact (6) engaged within the enclosure (1), mounted with axial slidability in the plate (2) and biased towards the inside of the enclosure by a spring (7), the contact (6) being urged under pressure against a conductive end piece (12) which itself bears against the end of the heating tube (11) which faces towards the first closure plate (2), the opposite end of the heating tube (11) being inserted into a seat (3a) provided in the second closure plate (3) carrying the outlet nozzle (21).
18. Apparatus according to claim 6, characterised in that the end of the heating tube (11) which faces towards the first closure plate (2) is connected to an electrical supply terminal (43) carried by the first closure plate (2), via a braided conductor (44) and a thermocouple (45), or another tube for heating any kind of fluid fed into the heating tube (11) through the first closure plate (2).
19. Apparatus according to claim 17, characterised in that the first closure plate (2) is in thermal contact with a chamber (25a) or a tube (25) traversed by cooling water.
20. Apparatus according to claim 6, characterised in that the first closure plate (2) is in thermal contact with a radiator (37) to ensure its cooling by means of air.
21. Apparatus according to the preceding claim 5, characterised in that the gas preheating means are constituted by a coil (17) surrounding the tubular enclosure (1) and in thermal contact therewith.
22. Apparatus according to claim 5, characterised in that the gas preheating means are constituted by a cylindrical chamber (17a) surrounding the heat exchanger (14, 15).
23. Apparatus according to claim 5, characterised in that the gas prehating means are constituted by a screwthread (17b) machined into the outer surface of the tubular enclosure (1).
24. Apparatus according to claim 5, characterised in that the heating tube (111) is held in position by a centering device (124) comprising openings (110) allowing the gas to be fed from the preheating means (102, 104, 106, 108) into the heating tube (111) via one of its ends.
25. Apparatus according to claim 24, characterised in that the centering device (124) also carries electrical contact (126) movable in translation in such a way as to follow the longitudinal expansions of the heating tube (111).
26. Apparatus according to claim 25, characterised in that the movable electrical contact (126) is connected via a flexible wire (130) to a fixed electrical contact (133) fixed to the casing element (136) but electrically insulated therefrom.
EP86400868A 1985-04-25 1986-04-22 Apparatus for the production of a high temperature gas jet Expired EP0200637B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86400868T ATE40741T1 (en) 1985-04-25 1986-04-22 APPARATUS FOR GENERATION OF A HIGH TEMPERATURE GAS JET.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8506306 1985-04-25
FR8506306A FR2581168B1 (en) 1985-04-25 1985-04-25 APPARATUS FOR THE PRODUCTION OF A HIGH TEMPERATURE GAS JET

Publications (2)

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EP0200637A1 EP0200637A1 (en) 1986-11-05
EP0200637B1 true EP0200637B1 (en) 1989-02-08

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US (1) US4725715A (en)
EP (1) EP0200637B1 (en)
JP (1) JPS61276615A (en)
AT (1) ATE40741T1 (en)
CA (1) CA1253851A (en)
DE (1) DE3662074D1 (en)
FR (1) FR2581168B1 (en)

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Also Published As

Publication number Publication date
ATE40741T1 (en) 1989-02-15
CA1253851A (en) 1989-05-09
FR2581168A1 (en) 1986-10-31
JPS61276615A (en) 1986-12-06
FR2581168B1 (en) 1987-06-05
EP0200637A1 (en) 1986-11-05
US4725715A (en) 1988-02-16
DE3662074D1 (en) 1989-03-16

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