EP0252843B1 - Plasma-heated rotary drum furnace mechanically fed with materials to be treated - Google Patents

Plasma-heated rotary drum furnace mechanically fed with materials to be treated Download PDF

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Publication number
EP0252843B1
EP0252843B1 EP19870401605 EP87401605A EP0252843B1 EP 0252843 B1 EP0252843 B1 EP 0252843B1 EP 19870401605 EP19870401605 EP 19870401605 EP 87401605 A EP87401605 A EP 87401605A EP 0252843 B1 EP0252843 B1 EP 0252843B1
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EP
European Patent Office
Prior art keywords
oven
axis
rotation
plasma
plasma torch
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 - Lifetime
Application number
EP19870401605
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German (de)
French (fr)
Other versions
EP0252843A1 (en
Inventor
Jacques Roussel
Ferid Nandjee
André Ducourroy
Fayez Kassabji
Richard Fautre
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Electricite de France SA
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Electricite de France SA
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Publication of EP0252843A1 publication Critical patent/EP0252843A1/en
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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/32—Arrangement of devices for charging
    • F27B7/3205—Charging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/34—Arrangements of heating devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/32—Arrangement of devices for charging
    • F27B7/3205—Charging
    • F27B2007/3211—Charging at the open end of the drum
    • F27B2007/3217—Charging at the open end of the drum axially, optionally at some distance in the kiln
    • F27B2007/3223—Charging at the open end of the drum axially, optionally at some distance in the kiln the charging device being movable axially, e.g. reciprocable
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/32—Arrangement of devices for charging
    • F27B7/3205—Charging
    • F27B2007/3211—Charging at the open end of the drum
    • F27B2007/3217—Charging at the open end of the drum axially, optionally at some distance in the kiln
    • F27B2007/3241—Charging at the open end of the drum axially, optionally at some distance in the kiln in the flame of the burner
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0006—Electric heating elements or system
    • F27D2099/0031—Plasma-torch heating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27M—INDEXING SCHEME RELATING TO ASPECTS OF THE CHARGES OR FURNACES, KILNS, OVENS OR RETORTS
    • F27M2001/00—Composition, conformation or state of the charge
    • F27M2001/03—Charges containing minerals

Definitions

  • the present invention relates to a rotary plasma oven supplying material to be treated by mechanical drive.
  • Plasma rotary ovens used for the treatment at high or very high temperature of pulverulent or granular materials has been the subject of a great deal of work to date.
  • the profitable operation of the rotary plasma ovens currently used, ovens as described in the aforementioned article requires a continuous supply of material to be treated.
  • the actual oven or oven body is inclined relative to its initial horizontal position, the oven body being driven in rotation by a motor system.
  • G and the product to be treated is introduced from a loading hopper Q disposed at the upper end of the furnace body, the material treated at high temperature being poured at the other end.
  • An axial superimposed plasma C is generated between the electrodes of the plasma torch A, B, the torch B being substantially arranged axially with respect to the axis of rotation A and the torch A being offset with respect to this axis or translated on that here, so as to allow the casting of the treated material.
  • the electrical power supplies D and F of the torches A and B make it possible to create two plasma jets which, joining together in the axis of the furnace, form a column of ionized gases conducting electricity.
  • the electrical supply E is used for the superposition of an electric arc on this gas column.
  • the temperature of the plasma arc reaching most often and possibly even exceeding 10,000 ° K, the plasma flows have a high viscosity at such temperatures, the degree of viscosity of these being an increasing function of the temperature.
  • penetration by simple gravity of the powder is almost impossible in the arc itself and the introduction of the material to be treated into the furnace or furnace body presents significant difficulties.
  • introduction of the material into the furnace body must in fact be carried out so that the material reaches the lower part of the refractory enclosure of the furnace body.
  • a lip of molten material forms on the flow edge of the introduction nozzle , preventing the introduction of the material, in the pulverulent or granular state, the system described above is satisfactory for low material flow rates.
  • the object of the present invention is to remedy the aforementioned drawbacks by using a rotary plasma oven in which the introduction of the material to be treated into the oven is ensured, in the absence of any stream of carrier gas, by only mechanical drive.
  • Another object of the present invention is the implementation of a rotary plasma oven allowing the treatment at high or very high temperature of powdery or granular materials on an industrial scale, or with material flow rates of the order of 0.5 to 1 m 3 per hour.
  • Another object of the present invention is the implementation of a rotary plasma oven of simplified design, a plasma torch being omitted, the operating parameters of the oven being able to be adapted to ensure appropriate operating conditions.
  • the rotary plasma oven comprising a mobile oven body rotating around an axis and at least one plasma torch disposed in the vicinity of one of the two ends of the oven body and the axis of rotation thereof is remarkable in that the furnace is provided with means for supplying the material to be treated making it possible to establish a supply flow substantially coaxial with the axis of rotation in order to obtain a supply of material to the furnace by mechanical drive alone .
  • the invention finds application in the treatment of powdery, granular or pasty materials such as in particular, alumina, magnesia, refractory materials.
  • the rotary plasma oven object of the invention, comprises an oven body, denoted 1 .mobile in rotation about an axis A, the oven body 1 being as described above set in motion around of axis A by means of drive means denoted G. It further comprises at least one plasma torch denoted A, B in FIG. 2, plasma torch arranged in the vicinity of one end of the furnace body 1 and the axis of rotation A.
  • the plasma furnace is provided at one end of the furnace body 1, with means denoted 2, for supplying material to be treated, making it possible to establish a supply flow for the furnace with material to be treated, substantially coaxial with the axis of rotation A.
  • These means make it possible to supply the furnace with material to be treated coaxial with the axis of rotation A, the supply of material taking place by the mere mechanical drive of the latter, in the absence of any stream of gas carrying the material.
  • the supply means 2 and the plasma torch denoted B are arranged at the same end of the furnace body 1.
  • the supply means 2 and the plasma torch denoted B are , as shown in Figure 2, concentric and admit the same axis of revolution, the axis of rotation A.
  • the supply means 2 can advantageously be constituted by a hollow Archimedes screw, the plasma torch B being arranged in the hollow part of the screw.
  • the supply means 2 are of course connected to a loading hopper denoted Q, as previously described in the description.
  • the supply means 2 and the plasma torch denoted A can be arranged at opposite ends of the oven body 1.
  • the supply means 2 and the plasma torch A then admit for the same axis of revolution the axis of rotation A of the furnace body.
  • the means 2 for supplying the material to be treated also consist of an Archimedes screw admitting for axis of revolution the axis of rotation A of the furnace body .
  • the Archimedes screw constituting the supply means 2 as shown in FIG. 4 is also connected to a loading hopper marked Q.
  • FIG. 3 appears particularly advantageous insofar as it allows the use of a rotary plasma oven of notably simplified design insofar as, in accordance with an object of the invention, one of the plasma torches, torch B, can then be deleted.
  • the end of the material supply means 2 is advantageously provided with a wearing part 20, forming an anode, this wearing part being more particularly intended to act as a counter-electrode for the torch.
  • plasma A disposed in the vicinity of the opposite end of the furnace body 1.
  • the wearing part 20 can advantageously be made of a material which is very good conductor of electricity, such as a beryllium bronze or copper or copper alloys for example.
  • the material supply means 2 can advantageously be adjustable in position relative to the corresponding end of the furnace body 1, the adjustment in position consisting of an adjustment in translation T along the axis of rotation A of the furnace body.
  • the translational adjustment means symbolically represented by T in FIGS. 3 and 4 can advantageously be constituted by support slides allowing the translation of the assembly constituted by the supply means 2 and the hopper Q in the direction A of l 'axis of rotation of the furnace body 1.
  • the means of adjustment in translation have not been shown in Figures 3 and 4 so as not to interfere with the clarity of the description of the subject of the invention.
  • the above-mentioned adjustment in translation makes it possible to obtain, as a function of the parameters for using the oven, object of the invention, and in particular the nature of the body or material to be treated, the temperature to be reached for the treatment. of the latter in the enclosure of the furnace body, an optimal adjustment of the length of plasma jet generated between the torch A and the wearing part forming anode noted 20 in FIG. 4.
  • the operating parameters of the furnace are then adapted or optimized accordingly.
  • the Archimedes screw can advantageously be provided with a double-walled envelope, denoted 201, 202, in order to allow the circulation between the aforementioned walls of a cooling fluid.
  • the cooling fluid can advantageously consist of deionized water.
  • the Archimedes screw as shown in FIG. 4, can advantageously include in the aforementioned double-walled envelope 201, 202, a propeller denoted 210, mounted on a propeller body 211, the assembly being mounted in one piece centering 212, made of a self-lubricating material.
  • the propeller 210 thus defines a helical chamber 200, in which the material to be treated is transported by mechanical drive, by setting in motion the Archimedes' screw.
  • the double-body casing 201, 202 comprises, at the end of the screw situated in the furnace body 1, an opening 204 bringing the helical chamber 200 of the screw into communication with the interior of the furnace body 1 in the vicinity of the axis of rotation A.
  • the opening 204 then allows the introduction of the material into the furnace body, substantially by gravity, substantially independently of the viscosity of the plasma jet.
  • the wear part 20 forming an anode may advantageously include a housing marked 2000, substantially annular, intended to receive a permanent magnet in the form of a torus, the permanent magnet in operation of the oven being intended to cause, by electromagnetic interaction, a precession movement of the plasma jet around the axis A, so as to obtain an average wear effect, on the contact surface of the wear part 20.
  • the rotary plasma oven object of the invention allows the introduction of powdery or granular material inside the rotary oven, through the means of supply 2 support of the anode cooled in the total absence of gas carrying the material to be treated. This introduction is of course carried out continuously, with the advantages of optimal operating conditions of the oven as described above.
  • FIG. 1 As will be seen in FIG. 1
  • the propeller body 211 can advantageously be provided with an axial orifice denoted 2110, this axial orifice 2110 opening at the wearing part, on an outlet orifice noted 2010 and by which, in operation, a gas jet is generated via an auxiliary source not shown in the drawing, in order to establish, after suitable supply of the entire device with electrical energy by means of the generators D, E, F previously described, a superposed plasma arc transferred between the wearing part forming anode 20 and the torch arranged opposite A, the gas jet thus created opening out from the orifice 2010 , then makes it possible to establish the desired electric arc between the wearing part forming anode 20 and the torch A previously described.
  • the plasma arc thus formed can then be drawn by translational movement of the supply means 2 shown in FIG. 4 so as to define a desired length of plasma arc as a function of the application considered.
  • the rotary plasma oven previously described makes it possible in particular to mechanically introduce the material to be treated into the oven, in the absence of any carrier gas with a great improvement in the thermal efficiency of the oven.
  • the amount of gas required to protect the electrode and to support the plasma arc in the furnace is in any event low and corresponds to the normal operating and establishment conditions of the plasma arc in the furnace.
  • the propeller body 211 itself is hollow, the central space of the propeller body 211 accommodating the plasma torch denoted B as it is shown in this figure.
  • the Archimedes screw formed by the propeller 210 and the propeller body 211 are then inside a double-walled cylindrical casing denoted 201, 202 and rotate around the torch denoted B by entraining the material to be treat from the hopper denoted Q to the outlet end denoted 204.
  • the supply of material to be treated is then substantially axial, the axes of the furnace or furnace body 1, of the screw formed by the screw body 211 and the propeller 210 and the torch B then being combined and corresponding to the axis A of rotation of the furnace body 1.
  • the end of the assembly formed by the plasma torch B, the propeller body 211 and the double-walled envelope 201, 202 fits into the flange of the furnace body 1 in rotation and is capable of '' be subjected to the radiation of the molten material and to the temperature prevailing near the plasma which is very high. It should be recalled that the temperature of the plasma arc near the axis of rotation A can commonly reach and even exceed temperatures above 10,000 ° K. Consequently, it is necessary to cool all of the aforementioned parts and the double-walled envelope 201, 202 is traversed by a flow of refrigerant fluid, such as deionized water and the screw of Archimedes itself.
  • refrigerant fluid such as deionized water and the screw of Archimedes itself.
  • the screw body 211 and by the propeller 210 are also traversed by a flow of refrigerant of the same kind.
  • the deionized water constituting the refrigerant for example, enters through the propeller which is itself hollow and exits through the screw body 211, the screw body 211 itself being constituted by a double-walled body.
  • the circulation of water or cooling fluid in the propeller and in the propeller body 211 can advantageously be produced from two rotary joints denoted respectively 2101 and 2110.
  • the rotary joint 2101 allows the supply of the propeller 210, proper with cooling fluid, while the rotary joint 2110 on the contrary allows the evacuation of the cooling fluid from the propeller body 211.
  • the two rotary joints 2101 and 2110 mentioned above are advantageously arranged upstream of the loading hopper Q, which is of course integral with the casing external double wall 201, 202, and in direct communication with the helical chamber 200.
  • the arrangement of the aforementioned rotary joints will not be described in detail insofar as the supply by rotary joint in a fluid , such as a coolant, of concentric rotating systems is within the competence of the skilled person and does not fall within the scope of the present invention.
  • FIGS. 5b and 5c provide a better understanding of the detail of embodiment of the relative arrangement of the propeller body 211 and of the propeller 210 with regard to the circulation of the cooling fluid.
  • the propeller 210 actually forms a circulation channel for the cooling fluid, the aforementioned circulation channel being in communication at its end, with the double-walled propeller body 211, the double wall thus being able to constitute a pipe for return of the coolant to the aforementioned rotary evacuation joint 2110.
  • the arrows indicate the direction of circulation of the cooling fluid.
  • a substantially annular partition 2112 can be provided at the end of the double-walled screw body 211, the end situated in the vicinity of the above-mentioned torch B.
  • substantially annular partition means a partition in the form of a ring having an opening allowing the passage of the cooling fluid, the latter being further guided at the orifice of communication with the double wall propeller 211, by a extension of the ring directed along a generating line of the double-walled envelope.
  • the substantially annular partition may possibly take other forms, that shown in FIGS. 5b and 5c being given by way of example only.
  • This partition 2112 has the effect of allowing the circulation of the cooling fluid along a substantially peripheral path materialized by the arrows shown in FIG. 5c, in the vicinity of the aforementioned end of the propeller body 211.
  • the propeller 210 constituting the Archimedes' screw can be formed or made of stainless steel for example, and the double-walled envelope 201, 202, can advantageously be made of a softer material, so that the latter preferably undergoes abrasion wear brought about by operation.
  • the rotary plasma oven object of the invention also includes a device for guiding and supporting the screw, as well as its drive system which can, in conventional manner, consist of an input ring on which a pinion or a belt driven by an electric motor meshes.
  • the guiding device having been described in the case of the embodiment of FIG. 3, this guiding device thus allowing, as previously described, a position adjustment in translation of the supply means 2 along the axis of rotation A as previously described, the drive system constituted by conventional elements of the technique will not be described in detail.
  • a rotary plasma oven has thus been described, making it possible to obtain both an improvement in the thermal efficiency of the oven and a very significant increase in the treatment flow rates of the material to be treated.
  • the ovens of the prior art allowing at most treatment flow rates of the order of 150 l / h, it has thus been possible to obtain an increase in flow rate of the order of a factor of three by the use of rotary kilns with plasma according to the present invention.
  • the aforementioned ovens in particular because of their greater processing capacity, can without disadvantage be used on an industrial scale for the treatment of the most diverse products.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Furnace Charging Or Discharging (AREA)
  • Gasification And Melting Of Waste (AREA)
  • Plasma Technology (AREA)

Description

La présente invention est relative à un four rotatif à plasma à alimentation en matériau à traiter par entraînement mécanique.The present invention relates to a rotary plasma oven supplying material to be treated by mechanical drive.

Les fours rotatifs à plasma utilisés pour le traitement à haute ou très haute température de matériaux pulvérulents ou granuleux, a fait l'objet jusqu'à ce jour de très nombreux travaux. Parmi les plus récents, on peut citer, notamment, dans la publication J.F.E. n° 3, publiée en Mars-Avril 1979, l'article de David Yerouchalmi intitulé "Four rotatif à haute température chauffé axialement par un plasma d'arcs pour la fusion et l'élaboration de produits ultra-réfractaires et de métaux".Plasma rotary ovens used for the treatment at high or very high temperature of pulverulent or granular materials, has been the subject of a great deal of work to date. Among the most recent, we can cite, in particular, in the publication J.F.E. n ° 3, published in March-April 1979, the article by David Yerouchalmi entitled "High temperature rotary furnace heated axially by a plasma of arcs for the fusion and the development of ultra-refractory products and metals".

L'exploitation rentable des fours tournants à plasma utilisés actuellement, fours tels que décrits dans l'article précité, passe par une alimentation continue en matériau à traiter. Dans ce but, ainsi qu'il est d'ailleurs représenté de façon schématique en figure 1, le four proprement dit ou corps de four est incliné par rapport à sa position horizontale initiale, le corps de four étant entraîné en rotation par un système moteur G, et le produit à traiter est introduit à partir d'une trémie de chargement Q disposée à l'extrémité supérieure du corps de four, la coulée du matériau traité à haute température étant effectuée à l'autre extrémité. Un plasma superposé C axial est engendré entre les électrodes de t orche à plasma A, B, la torche B étant sensiblement disposée axialement par rapport à l'axe de rotation A et la torche A étant décalée par rapport à cet axe ou translatée sur celui-ci, de façon à permettre la coulée du matériau traité. Les alimentations électriques D et F des torches A et B permettent de créer deux jets de plasma qui en se rejoignant dans l'axe du four forment une colonne de gaz ionisés conductrice de l'électricité. L'alimentation électrique E sert à la superposition d'un arc électrique sur cette colonne gazeuse. La température de l'arc plasma atteignant le plus souvent et pouvant même dépasser 10 000°K, les écoulements plasma présentent une viscosité importante à de telles températures, le degré de viscosité de ceux-ci étant une fonction croissante de la température. Du fait même de cette viscosité importante de l'arc plasma, la pénétration par simple gravité de la poudre est quasi impossible dans l'arc même et l'introduction du matériau à traiter dans le four ou corps de four présente des difficultés importantes, l'introduction du matériau dans le corps de four devant en fait être effectuée de façon à ce que le matériau atteigne la partie inférieure de l'enceinte réfractaire du corps de four. Afin d'obtenir de telles modalités d'introduction du matériau à traiter dans le four, il est nécessaire de prévoir un courant de gaz porteur du matériau pulvérulent ou granuleux à traiter, le matériau pénétrant ainsi dans le corps de four par l'intermédiaire d'une buse d'injection S sous l'effet de la gravité et du courant de gaz porteur.Bien que quelques difficultés puissent apparaître dans le cas où une lèvre de matériau fondu se forme sur le bord d'écoulement de la buse d'introduction, empêchant l'introduction du matériau, à l'état pulvérulent ou granuleux, le système précédemment décrit donne satisfaction pour de faibles débits de matériau.The profitable operation of the rotary plasma ovens currently used, ovens as described in the aforementioned article, requires a continuous supply of material to be treated. For this purpose, as is shown schematically in FIG. 1, the actual oven or oven body is inclined relative to its initial horizontal position, the oven body being driven in rotation by a motor system. G, and the product to be treated is introduced from a loading hopper Q disposed at the upper end of the furnace body, the material treated at high temperature being poured at the other end. An axial superimposed plasma C is generated between the electrodes of the plasma torch A, B, the torch B being substantially arranged axially with respect to the axis of rotation A and the torch A being offset with respect to this axis or translated on that here, so as to allow the casting of the treated material. The electrical power supplies D and F of the torches A and B make it possible to create two plasma jets which, joining together in the axis of the furnace, form a column of ionized gases conducting electricity. The electrical supply E is used for the superposition of an electric arc on this gas column. The temperature of the plasma arc reaching most often and possibly even exceeding 10,000 ° K, the plasma flows have a high viscosity at such temperatures, the degree of viscosity of these being an increasing function of the temperature. By the very fact of this high viscosity of the plasma arc, penetration by simple gravity of the powder is almost impossible in the arc itself and the introduction of the material to be treated into the furnace or furnace body presents significant difficulties. introduction of the material into the furnace body must in fact be carried out so that the material reaches the lower part of the refractory enclosure of the furnace body. In order to obtain such methods of introducing the material to be treated into the furnace, it is necessary to provide a stream of gas carrying the pulverulent or granular material to be treated, the material thus penetrating into the furnace body via '' an injection nozzle S under the effect of gravity and the current of carrier gas.Although some difficulties may appear in the case where a lip of molten material forms on the flow edge of the introduction nozzle , preventing the introduction of the material, in the pulverulent or granular state, the system described above is satisfactory for low material flow rates.

En vue d'atteindre des débits beaucoup plus importants, à l'aide du dispositif tel que décrit précédemment, il serait nécessaire d'augmenter les dimensions de la buse d'introduction et/ou d'augmenter fortement le débit et la pression du courant de gaz porteur du matériau à traiter.In order to achieve much higher flow rates, using the device as described above, it would be necessary to increase the dimensions of the introduction nozzle and / or greatly increase the flow rate and pressure of gas carrying the material to be treated.

L'augmentation des valeurs des paramètres pré- dédemment cités ne peut être valablement envisagée en raison d'une diminution correspondante du rendement énergétique du four, consécutive à une modification des conditions de formation du plasma notamment. Une augmentation importante du débit de gaz porteur, les débits de gaz plasmagène étant très faibles, apparaît notamment exclue, une extinction ou soufflage intempestif du plasma pouvant même être provoqué par un débit de gaz porteur trop important. En tout état de cause, un débit de gaz porteur important a pour effet une consommation parasite de chaleur par celui-ci, laquelle est néfaste à l'obtention d'un bon rendement du four.The increase in the values of the previously mentioned parameters cannot be validly envisaged due to a corresponding decrease in the energy efficiency of the furnace, following a modification of the conditions of plasma formation in particular. A significant increase in the flow rate of carrier gas, the plasma gas flow rates being very low, appears in particular to be excluded, an untimely extinction or blowing of the plasma which may even be caused by an excessively large flow rate of carrier gas. In any event, a high carrier gas flow has the effect of a parasitic heat consumption by the latter, which is detrimental to obtaining a good efficiency of the oven.

La présente invention a pour but de remédier aux inconvénients précités par la mise en oeuvre d'un four rotatif à plasma dans lequel l'introduction du matériau à traiter dans le four est assurée, en l'absence de tout courant de gaz porteur, par seul entraînement mécanique.The object of the present invention is to remedy the aforementioned drawbacks by using a rotary plasma oven in which the introduction of the material to be treated into the oven is ensured, in the absence of any stream of carrier gas, by only mechanical drive.

Un autre objet de la présente invention est la mise en oeuvre d'un four rotatif à plasma permettant le traitement à haute ou très haute température de matériaux pulvérulents ou granuleux à l'échelle industrielle, soit avec des débits de matériau de l'ordre de 0,5 à 1 m3 par heure.Another object of the present invention is the implementation of a rotary plasma oven allowing the treatment at high or very high temperature of powdery or granular materials on an industrial scale, or with material flow rates of the order of 0.5 to 1 m 3 per hour.

Un autre objet de la présente invention est la mise en oeuvre d'un four rotatif à plasma de conception simplifiée, une torche à plasma étant supprimée, les paramètres de fonctionnement du four pouvant être adaptés pour assurer des conditions de fonctionnement appropriées.Another object of the present invention is the implementation of a rotary plasma oven of simplified design, a plasma torch being omitted, the operating parameters of the oven being able to be adapted to ensure appropriate operating conditions.

Le four rotatif à plasma comportant un corps de four mobile en rotation autour d'un axe et au moins une torche à plasma disposée au voisinage d'une des deux extrémités du corps de four et de l'axe de rotation de celui-ci est remarquable en ce que le four est muni de moyens d'alimentation en matériau à traiter permettant d'établir un flux d'alimentation sensiblement coaxial à l'axe de rotation en vue d'obtenir une alimentation du four en matériau par le seul entraînement mécanique.The rotary plasma oven comprising a mobile oven body rotating around an axis and at least one plasma torch disposed in the vicinity of one of the two ends of the oven body and the axis of rotation thereof is remarkable in that the furnace is provided with means for supplying the material to be treated making it possible to establish a supply flow substantially coaxial with the axis of rotation in order to obtain a supply of material to the furnace by mechanical drive alone .

L'invention trouve application au traitement de matériaux pulvérulents, granuleux ou pâteux tels que notamment, l'alumine, la magnésie, les matériaux réfractaires.The invention finds application in the treatment of powdery, granular or pasty materials such as in particular, alumina, magnesia, refractory materials.

D'autres caractéristiques et avantages du four rotatif à plasma objet de l'invention apparaîtront à la lecture de la description et à l'observation des dessins ci-après dans lesquels, outre la figure 1 relative à l'art antérieur,

  • - la figure 2 représente en coupe une vue générale d'un four objet de la présente invention,
  • - la figure 3 représente, en coupe, une variante de réalisation du four objet de la présente invention,
  • - la figure 4 représente, en coupe selon un plan de symétrie longitudinal, un détail de réalisation du four objet de l'invention correspondant au mode de réalisation de la figure 3,
  • - la figure 5a représente, également en coupe, un détail de réalisation du dispositif représenté en figure 2 et les figures 5b et 5c représentent respectivement une vue agrandie de la vis d'Achimède du dispositif de la figure 5a et une vue en coupe selon un plan de coupe AA de la figure 5b.
Other characteristics and advantages of the rotary plasma oven which is the subject of the invention will appear on reading the description and the observation of the drawings below in which, in addition to FIG. 1 relating to the prior art,
  • FIG. 2 represents in section a general view of an oven object of the present invention,
  • FIG. 3 represents, in section, an alternative embodiment of the oven which is the subject of the present invention,
  • - Figure 4 shows, in section along a plane of longitudinal symmetry, a detail of the furnace which is the subject of the invention corresponding to the embodiment of FIG. 3,
  • - Figure 5a shows, also in section, a detail of the device shown in Figure 2 and Figures 5b and 5c respectively show an enlarged view of the Achimedes screw of the device of Figure 5a and a sectional view along a section plane AA of FIG. 5b.

Le four rotatif à plasma, objet de l'invention, sera tout d'abord décrit en liaison avec la figure 2. Sur l'ensemble des figures, les mêmes références désignent les mêmes éléments.The rotary plasma oven, object of the invention, will first be described in connection with Figure 2. In all of the figures, the same references designate the same elements.

Ainsi que précédemment décrit, le four rotatif à plasma, objet de l'invention, comporte un corps de four,noté 1 .mobile en rotation autour d'un axe A , le corps de four 1 étant ainsi que décrit précédemment mis en mouvement autour de l'axe A par l'intermédiaire de moyens d'entraînement notés G. Il comporte en outre au moins une torche à plasma notée A, B sur la figure 2, torche à plasma disposée au voisinage d'une extrémité du corps de four 1 et de l'axe de rotation A.As previously described, the rotary plasma oven, object of the invention, comprises an oven body, denoted 1 .mobile in rotation about an axis A, the oven body 1 being as described above set in motion around of axis A by means of drive means denoted G. It further comprises at least one plasma torch denoted A, B in FIG. 2, plasma torch arranged in the vicinity of one end of the furnace body 1 and the axis of rotation A.

Conformément à l'invention, le four à plasma est muni à une extrémité du corps de four 1, de moyens notés 2, d'alimentation en matériau à traiter, permettant d'établir un flux d'alimentation du four en matériau à traiter, sensiblement coaxial à l'axe de rotation A . Ces moyens permettent d'alimenter le four en matériau à traiter coaxialement à l'axe de rotation A , l'alimentation en matériau ayant lieu par le seul entraînement mécanique de ce dernier, en l'absence de tout courant de gaz porteur du matériau.In accordance with the invention, the plasma furnace is provided at one end of the furnace body 1, with means denoted 2, for supplying material to be treated, making it possible to establish a supply flow for the furnace with material to be treated, substantially coaxial with the axis of rotation A. These means make it possible to supply the furnace with material to be treated coaxial with the axis of rotation A, the supply of material taking place by the mere mechanical drive of the latter, in the absence of any stream of gas carrying the material.

Ainsi qu'il apparaît en outre en figure 2, les moyens d'alimentation 2 et la torche à plasma notée B sont disposés à la même extrémité du corps de four 1. Les moyens d'alimentation 2 et la torche à plasma notée B sont, ainsi que représentés en figure 2, concentriques et admettent le même axe de révolution, l'axe de rotation A.As it also appears in FIG. 2, the supply means 2 and the plasma torch denoted B are arranged at the same end of the furnace body 1. The supply means 2 and the plasma torch denoted B are , as shown in Figure 2, concentric and admit the same axis of revolution, the axis of rotation A.

Ainsi qu'il apparaît en outre en figure 2, et qu'il sera décrit plus en détail ultérieurement dans la présente description, les moyens d'alimentation 2 peuvent avantageusement être constitués par une vis d'Archimède creuse, la torche à plasma B étant disposée dans la partie creuse de la vis. Les moyens d'alimentation 2 sont bien entendu reliés à une trémie de chargement notée Q, ainsi que précédemment décrit dans la description. Ainsi, le caractère concentrique de la torche à plasma notée B et des moyens d'alimentation 2 précédemment décrits permet d'assurer une alimentation en matériau à traiter en continu, dans des conditions convenables de fonctionnement et de rendement du four, le courant de gaz porteur du matériau étant totalement supprimé et les pertes d'énergie calorifique dues à la présence du courant de gaz porteur dans l'art antérieur étant également supprimées.As it also appears in FIG. 2, and which will be described in more detail later in the present description, the supply means 2 can advantageously be constituted by a hollow Archimedes screw, the plasma torch B being arranged in the hollow part of the screw. The supply means 2 are of course connected to a loading hopper denoted Q, as previously described in the description. Thus, the concentric nature of the plasma torch denoted B and of the supply means 2 described above makes it possible to ensure a supply of material to be treated continuously, under suitable conditions of operation and efficiency of the furnace, the gas stream carrier of the material being completely eliminated and the losses of heat energy due to the presence of the current of carrier gas in the prior art also being eliminated.

Selon une variante avantageuse du four rotatif à plasma objet de l'invention représenté en figure 2, les moyens d'alimentation 2 et la torche à plasma notée A peuvent être disposés aux extrémités opposées du corps de four 1. Les moyens d'alimentation 2 et la torche à plasma A admettent alors pour même axe de révolution l'axe de rotation A du corps de four. Dans ce cas, ainsi qu'il apparaît notamment en figure 3, les moyens d'alimentation 2 en matériau à traiter sont constitués également par une vis d'Ar- chimède admettant pour axe de révolution l'axe de rotation A du corps de four. Bien entendu, la vis d'Archimède constituant les moyens d'alimentation 2 tels que représentés en figure 4 est également reliée à une trémie de chargement notée Q.According to an advantageous variant of the rotary plasma oven object of the invention shown in Figure 2, the supply means 2 and the plasma torch denoted A can be arranged at opposite ends of the oven body 1. The supply means 2 and the plasma torch A then admit for the same axis of revolution the axis of rotation A of the furnace body. In this case, as it appears in particular in FIG. 3, the means 2 for supplying the material to be treated also consist of an Archimedes screw admitting for axis of revolution the axis of rotation A of the furnace body . Of course, the Archimedes screw constituting the supply means 2 as shown in FIG. 4 is also connected to a loading hopper marked Q.

Le mode de réalisation de la figure 3 apparaît particulièrement avantageux dans la mesure où il autorise la mise en oeuvre d'un four rotatif à plasma de conception notablement simpliée dans la mesure où, conformément à un objet de l'invention, l'une des torches à plasma, la torche B, peut alors être supprimée. A cet effet, l'extrémité des moyens d'alimentation 2 en matériau est avantageusement munie d'une pièce d'usure 20, formant anode, cette pièce d'usure étant plus particulièrement destinée à jouer le rôle de contre-électrode pour la torche à plasma A disposée au voisinage de l'extrémité opposée du corps de four 1. La pièce d'usure 20 peut avantageusement être constituée en un matériau très bon conducteur de l'électricité, tel qu'un bronze au béryllium ou cuivre ou alliages cuivreux par exemple.The embodiment of FIG. 3 appears particularly advantageous insofar as it allows the use of a rotary plasma oven of notably simplified design insofar as, in accordance with an object of the invention, one of the plasma torches, torch B, can then be deleted. To this end, the end of the material supply means 2 is advantageously provided with a wearing part 20, forming an anode, this wearing part being more particularly intended to act as a counter-electrode for the torch. plasma A disposed in the vicinity of the opposite end of the furnace body 1. The wearing part 20 can advantageously be made of a material which is very good conductor of electricity, such as a beryllium bronze or copper or copper alloys for example.

Ainsi qu'il apparaît notamment en figures 3 et 4, les moyens d'alimentation 2 en matériau peuvent avantageusement être réglables en position par rapport à l'extrémité correspondante du corps de four 1, le réglage en position consistant en un réglage en translation T suivant l'axe de rotation A du corps de four. Les moyens de réglage en translation représentés symboliquement par T sur les figures 3 et 4 peuvent avantageusement être constitués par des glissières de support autorisant la translation de l'ensemble constitué par les moyens d'alimentation 2 et la trémie Q selon la direction A de l'axe de rotation du corps de four 1. Les moyens de réglage en translation n'ont pas été représentés sur les figures 3 et 4 afin de ne pas nuire à la clarté de l'exposé de l'objet de l'invention. De manière avantageuse, le réglage en translation précité permet d'obtenir, en fonction des paramètres d'utilisation du four, objet de l'invention,et notamment de la nature du corps ou matériau à traiter, de la température à atteindre pour le traitement de celui-ci dans l'enceinte du corps de four un réglage optimal de la longueur de jet de plasma engendré entre la torche A et la pièce d'usure formant anode notée 20 sur la figure 4. Les paramètres de fonctionnement du four sont alors adaptés ou optimalisés en conséquence.As it appears in particular in FIGS. 3 and 4, the material supply means 2 can advantageously be adjustable in position relative to the corresponding end of the furnace body 1, the adjustment in position consisting of an adjustment in translation T along the axis of rotation A of the furnace body. The translational adjustment means symbolically represented by T in FIGS. 3 and 4 can advantageously be constituted by support slides allowing the translation of the assembly constituted by the supply means 2 and the hopper Q in the direction A of l 'axis of rotation of the furnace body 1. The means of adjustment in translation have not been shown in Figures 3 and 4 so as not to interfere with the clarity of the description of the subject of the invention. Advantageously, the above-mentioned adjustment in translation makes it possible to obtain, as a function of the parameters for using the oven, object of the invention, and in particular the nature of the body or material to be treated, the temperature to be reached for the treatment. of the latter in the enclosure of the furnace body, an optimal adjustment of the length of plasma jet generated between the torch A and the wearing part forming anode noted 20 in FIG. 4. The operating parameters of the furnace are then adapted or optimized accordingly.

Ainsi qu'il apparaît en outre en figure 4, la vis d'Archimède peut avantageusement être munie d'une enveloppe à double paroi, notée 201, 202, afin de permettre la circulation entre les parois précitées d'un fluide de refroidissement. Le fluide de refroidissement peut avantageusement être constitué par de l'eau déionisée. La vis d'Archimède, ainsi que représentée en figure 4, peut avantageusement comprendre dans l'enveloppe à double paroi 201, 202 précitée, une hélice notée 210, montée sur un corps d'hélice 211, l'ensemble étant monté dans une pièce de centrage 212, en un matériau auto-lubrifiant. L'hélice 210 définit ainsi une chambre hélicoïdale 200, dans laquelle le matériau à traiter est transporté par entraînement mécanique, par mise en mouvement de la vis d'Archimède. L'enveloppe à double corps 201, 202 comporte, en extrémité de vis située dans le corps de four 1, une ouverture 204 mettant en communication la chambre hélicoïdale 200 de la vis et l'intérieur du corps de four 1 au voisinage de l'axe de rotation A . L'ouverture 204 permet alors l'introduction du matériau dans le corps de four, sensiblement par gravité,indépendamment sensiblement de la viscosité du jet de plasma.As it also appears in FIG. 4, the Archimedes screw can advantageously be provided with a double-walled envelope, denoted 201, 202, in order to allow the circulation between the aforementioned walls of a cooling fluid. The cooling fluid can advantageously consist of deionized water. The Archimedes screw, as shown in FIG. 4, can advantageously include in the aforementioned double-walled envelope 201, 202, a propeller denoted 210, mounted on a propeller body 211, the assembly being mounted in one piece centering 212, made of a self-lubricating material. The propeller 210 thus defines a helical chamber 200, in which the material to be treated is transported by mechanical drive, by setting in motion the Archimedes' screw. The double-body casing 201, 202 comprises, at the end of the screw situated in the furnace body 1, an opening 204 bringing the helical chamber 200 of the screw into communication with the interior of the furnace body 1 in the vicinity of the axis of rotation A. The opening 204 then allows the introduction of the material into the furnace body, substantially by gravity, substantially independently of the viscosity of the plasma jet.

Ainsi qu'on le remarquera en outre en figure 4, la pièce d'usure 20 formant anode, peut avantageusement comporter un logement noté 2000, sensiblement annulaire, destiné à recevoir un aimant permanent en forme de tore, l'aimant permanent en fonctionnement du four étant destiné à provoquer, par interaction électromagnétique un mouvement de précession du jet de plasma autour de l'axe A ,de façon à obtenir un effet de moyenne d'usure, à la surface de contact de la pièce d'usure 20.As will also be noted in FIG. 4, the wear part 20 forming an anode, may advantageously include a housing marked 2000, substantially annular, intended to receive a permanent magnet in the form of a torus, the permanent magnet in operation of the oven being intended to cause, by electromagnetic interaction, a precession movement of the plasma jet around the axis A, so as to obtain an average wear effect, on the contact surface of the wear part 20.

On comprendra que dans le mode de réalisation décrit en figures 3 et 4, le four rotatif à plasma objet de l'invention, permet l'introduction de matériau pulvérulent ou granuleux à l'intérieur du four rotatif, par l'intermédiaire des moyens d'alimentation 2 support de l'anode refroidie en l'absence totale de gaz porteur du matériau à traiter. Cette introduction bien entendu est effectuée de manière continue, avec pour avantages des conditions optimales de fonctionnement du four tel que précédemment décrit. En outre, ainsi qu'on le remarquera en figure 4, le corps d'hélice 211 peut avantageusement être muni d'un orifice axial noté 2110, cet orifice axial 2110 débouchant au niveau de la pièce d'usure, sur un orifice de sortie noté 2010 et par lequel, en fonctionnement,un jet de gaz est engendré par l'intermédiaire d'une source auxiliaire non représentée au dessin, afin d'établir, après alimentation convenable de l'ensemble du dispositif en énergie électrique au moyen des générateurs D, E, F précédememnt décrits, un arc plasma superpo-transféré entre la pièce d'usure formant anode 20 et la torche disposée en vis-à-vis notée A. Le jet de gaz ainsi créé débouchant à partir de l'orifice 2010, permet alors d'établir l'arc électrique souhaité entre la pièce d'usure formant anode 20 et la torche A précédemment décrite. L'arc plasma ainsi formé peut alors être étiré par déplacement en translation des moyens d'alimentation 2 représentés en figure 4 de façon à définir une longueur d'arc plasma souhaitée en fonction de l'application considérée.It will be understood that in the embodiment described in Figures 3 and 4, the rotary plasma oven object of the invention allows the introduction of powdery or granular material inside the rotary oven, through the means of supply 2 support of the anode cooled in the total absence of gas carrying the material to be treated. This introduction is of course carried out continuously, with the advantages of optimal operating conditions of the oven as described above. In addition, as will be seen in FIG. 4, the propeller body 211 can advantageously be provided with an axial orifice denoted 2110, this axial orifice 2110 opening at the wearing part, on an outlet orifice noted 2010 and by which, in operation, a gas jet is generated via an auxiliary source not shown in the drawing, in order to establish, after suitable supply of the entire device with electrical energy by means of the generators D, E, F previously described, a superposed plasma arc transferred between the wearing part forming anode 20 and the torch arranged opposite A, the gas jet thus created opening out from the orifice 2010 , then makes it possible to establish the desired electric arc between the wearing part forming anode 20 and the torch A previously described. The plasma arc thus formed can then be drawn by translational movement of the supply means 2 shown in FIG. 4 so as to define a desired length of plasma arc as a function of the application considered.

Le four rotatif à plasma précédemment décrit permet notamment d'introduire mécaniquement le matériau à traiter dans le four, en l'absence de tout gaz porteur avec une grande amélioration du rendement thermique du four. La quantité de gaz nécessaire à la protection de l'électrode et au support de l'arc plasma dans le four est en tout état de cause faible et correspond aux conditions normales de fonctionnement et d'établissement de l'arc plasma dans le four.The rotary plasma oven previously described makes it possible in particular to mechanically introduce the material to be treated into the oven, in the absence of any carrier gas with a great improvement in the thermal efficiency of the oven. The amount of gas required to protect the electrode and to support the plasma arc in the furnace is in any event low and corresponds to the normal operating and establishment conditions of the plasma arc in the furnace.

Un autre mode de réalisation du four rotatif à plasma objet de l'invention tel que représenté notamment en figure 2, sera décrit plus en détail en liaison avec les figures 5a, 5b, 5c.Another embodiment of the rotary plasma oven object of the invention as shown in particular in Figure 2, will be described in more detail in conjunction with Figures 5a, 5b, 5c.

On comprendra bien entendu conformément au mode de réalisation de la figure 5a, que le corps d'hélice 211, lui-même est creux, l'espace central du corps d'hélice 211 accueillant la torche à plasma notée B ainsi qu'il est représenté sur cette figure. La vis d'Archimède formée par l'hélice 210 et le corps d'hélice 211 se trouvent alors à l'intérieur d'une enveloppe cylindrique à double paroi notée 201, 202 et tournent autour de la torche notée B en entraînant le matériau à traiter depuis la trémie notée Q jusqu'à l'extrémité de sortie notée 204. L'alimentation en matériau à traiter est alors axiale sensiblement, les axes du four ou corps de four 1 , de la vis formée par le corps de vis 211 et l'hélice 210 et de la torche B étant alors confondus et correspondant à l'axe A de rotation du corps de four 1.It will of course be understood in accordance with the embodiment of FIG. 5a, that the propeller body 211, itself is hollow, the central space of the propeller body 211 accommodating the plasma torch denoted B as it is shown in this figure. The Archimedes screw formed by the propeller 210 and the propeller body 211 are then inside a double-walled cylindrical casing denoted 201, 202 and rotate around the torch denoted B by entraining the material to be treat from the hopper denoted Q to the outlet end denoted 204. The supply of material to be treated is then substantially axial, the axes of the furnace or furnace body 1, of the screw formed by the screw body 211 and the propeller 210 and the torch B then being combined and corresponding to the axis A of rotation of the furnace body 1.

L'extrémité de l'ensemble formé par la torche à plasma B, le corps d'hélice 211 et l'enveloppe à double paroi 201, 202, vient s'emboîter dans le flasque du corps de four 1 en rotation et est susceptible d'être soumis au rayonnement du matériau en fusion et à la température qui règne à proximité du plasma qui est très élevée.On rappelera pour mémoire que la température de l'arc plasma au voisinage de l'axe de rotation A peut couramment atteindre et même dépasser des températures supérieures à 10 000°K. En conséquence, il est nécessaire de refroidir l'ensemble des pièces précitées et l'enveloppe à double paroi 201, 202 est parcourue par un débit de fluide réfrigérant, tel que de l'eau déionisée et la vis d'Ar- chimède elle-même, constituée par le corps de vis 211 et par l'hélice 210 est également parcourue par un débit de fluide réfrigérant de même nature. L'eau déionisée constituant le fluide réfrigérant par exemple, rentre par l'hélice qui est elle-même creuse et ressort par le corps de vis 211, le corps de vis 211 étant constitué lui-même par un corps à double paroi. Compte tenu du fait que le corps d'hélice 211 et l'hélice elle-même 210, sont des pièces animées d'un mouvement de rotation, par rapport à l'axe A , la circulation d'eau ou fluide de refroidissement dans l'hélice et dans le corps d'hélice 211, peut avantageusement être réalisée à partir de deux joints tournants notés respectivement 2101 et 2110. Le joint tournant 2101 permet l'alimentation de l'hélice 210, proprement dite en fluide de refroidissement, alors que le joint tournant 2110 permet au contraire l'évacuation du fluide de refroidissement du corps d'hélice 211. Les deux joints tournants 2101 et 2110 précités sont avantageusement disposés en amont de la trémie de chargement Q, laquelle est bien entendu solidaire de l'enveloppe externe à double paroi 201, 202, et en communication directe avec la chambre hélicoïdale 200. L'agencement des joints tournants précités ne sera pas décrit en détail dans la mesure où l'alimentation par joint tournant en un fluide,tel qu'un fluide de refroidissement, de systèmes tournants concentriques est du domaine des compétence de l'homme de l'art et n'entre pas dans le cadre de la présente invention.The end of the assembly formed by the plasma torch B, the propeller body 211 and the double-walled envelope 201, 202, fits into the flange of the furnace body 1 in rotation and is capable of '' be subjected to the radiation of the molten material and to the temperature prevailing near the plasma which is very high. It should be recalled that the temperature of the plasma arc near the axis of rotation A can commonly reach and even exceed temperatures above 10,000 ° K. Consequently, it is necessary to cool all of the aforementioned parts and the double-walled envelope 201, 202 is traversed by a flow of refrigerant fluid, such as deionized water and the screw of Archimedes itself. even, constituted by the screw body 211 and by the propeller 210 is also traversed by a flow of refrigerant of the same kind. The deionized water constituting the refrigerant, for example, enters through the propeller which is itself hollow and exits through the screw body 211, the screw body 211 itself being constituted by a double-walled body. Taking into account that the propeller body 211 and the propeller itself 210, are parts driven by a rotational movement, relative to the axis A, the circulation of water or cooling fluid in the propeller and in the propeller body 211, can advantageously be produced from two rotary joints denoted respectively 2101 and 2110. The rotary joint 2101 allows the supply of the propeller 210, proper with cooling fluid, while the rotary joint 2110 on the contrary allows the evacuation of the cooling fluid from the propeller body 211. The two rotary joints 2101 and 2110 mentioned above are advantageously arranged upstream of the loading hopper Q, which is of course integral with the casing external double wall 201, 202, and in direct communication with the helical chamber 200. The arrangement of the aforementioned rotary joints will not be described in detail insofar as the supply by rotary joint in a fluid , such as a coolant, of concentric rotating systems is within the competence of the skilled person and does not fall within the scope of the present invention.

Les figures 5b et 5c permettent de mieux comprendre le détail de réalisation de l'agencement relatif du corps d'hélice 211 et de l'hélice 210 en ce qui concerne la circulation du fluide de refroidissement.FIGS. 5b and 5c provide a better understanding of the detail of embodiment of the relative arrangement of the propeller body 211 and of the propeller 210 with regard to the circulation of the cooling fluid.

Sur la figure 5b notamment, on constatera que l'hélice 210 forme en fait un canal de circulation du fluide de refroidissement, le canal de circulation précité étant en communication au niveau de son extrémité, avec le corps d'hélice 211 à double paroi, la double paroi pouvant ainsi constituer une canalisation de retour du fluide de refroidissement vers le joint tournant d'évacuation 2110 précité. Sur la figure 5b notamment, les flèches indiquent le sens de circulation du fluide de refroidissement. En outre, une cloison sensiblement annulaire 2112 peut être prévue en extrémité du corps de vis 211 à double paroi, extrémité située au voisinage de la torche B précitée. Par cloison sensiblement annulaire on entend une cloison en forme d'anneau présentant une ouverture permettant le passage du fluide de refroidissement, celui-ci étant en outre guidé au niveau de l'orifice de communication avec l'hélice 211 à double paroi, par un prolongement de l'anneau dirigé selon une ligne génératrice de l'enveloppe à double paroi. La cloison sensiblement annulaire peut éventuellement adopter d'autres formes, celle représentée par les figures 5b et 5c étant donnée à seul titre d'exemple. Cette cloison 2112 a pour effet de permettre la circulation du fluide de refroidissement selon un trajet sensiblement périphérique matérialisé par les flèches représentées en figure 5c, au voisinage de l'extrémité précitée du corps d'hélice 211.In FIG. 5b in particular, it will be seen that the propeller 210 actually forms a circulation channel for the cooling fluid, the aforementioned circulation channel being in communication at its end, with the double-walled propeller body 211, the double wall thus being able to constitute a pipe for return of the coolant to the aforementioned rotary evacuation joint 2110. In FIG. 5b in particular, the arrows indicate the direction of circulation of the cooling fluid. In addition, a substantially annular partition 2112 can be provided at the end of the double-walled screw body 211, the end situated in the vicinity of the above-mentioned torch B. By substantially annular partition means a partition in the form of a ring having an opening allowing the passage of the cooling fluid, the latter being further guided at the orifice of communication with the double wall propeller 211, by a extension of the ring directed along a generating line of the double-walled envelope. The substantially annular partition may possibly take other forms, that shown in FIGS. 5b and 5c being given by way of example only. This partition 2112 has the effect of allowing the circulation of the cooling fluid along a substantially peripheral path materialized by the arrows shown in FIG. 5c, in the vicinity of the aforementioned end of the propeller body 211.

L'hélice 210 constitutive de la vis d'Archimède peut être formée ou réalisée en un acier inoxydable par exemple, et l'enveloppe à double paroi 201, 202, peut avantageusement être constituée en un matériau plus tendre, afin que cette dernière subisse préférentiellement l'usure par abrasion amenée par le fonctionnement.The propeller 210 constituting the Archimedes' screw can be formed or made of stainless steel for example, and the double-walled envelope 201, 202, can advantageously be made of a softer material, so that the latter preferably undergoes abrasion wear brought about by operation.

Bien entendu, tant dans le cas du mode de réalisation de la figure 2, que dans celui de la figure 3, le four rotatif à plasma objet de l'invention comprend également un dispositif de guidage et de soutien de la vis, ainsi que son système d'entraînement qui peut, de manière classique,être constitué par une couronne d'entrée sur laquelle engrène un pignon ou une courroie entraînée par un moteur électrique. Le dispositif de guidage ayant été décrit dans le cas du mode de réalisation de la figure 3, ce dispositif de guidage permettant ainsi que décrit précédemment un réglage de position en translation du moyen d'alimentation 2 selon l'axe de rotation A tel que précédemment décrit, le système d'entraînement constitué par des éléments classiques de la technique ne sera pas décrit en détail.Of course, both in the case of the embodiment of FIG. 2, as in that of FIG. 3, the rotary plasma oven object of the invention also includes a device for guiding and supporting the screw, as well as its drive system which can, in conventional manner, consist of an input ring on which a pinion or a belt driven by an electric motor meshes. The guiding device having been described in the case of the embodiment of FIG. 3, this guiding device thus allowing, as previously described, a position adjustment in translation of the supply means 2 along the axis of rotation A as previously described, the drive system constituted by conventional elements of the technique will not be described in detail.

On a ainsi décrit un four rotatif à plasma permettant d'obtenir à la fois une amélioration du rendement thermique du four et une augmentation très importante des débits de traitement du matériau à traiter. Les fours de la technique antérieure permettant au plus des débits de traitement de l'ordre de 150 I/h, on a ainsi pu obtenir une augmentation de débit de l'ordre d'un facteur trois par la mise en oeuvre des fours rotatifs à plasma conformément à la présente invention. Les fours précités en raison notamment de leur plus grande capacité de traitement peuvent sans inconvénient être utilisés à l'échelle industrielle pour le traitement des produits les plus divers.A rotary plasma oven has thus been described, making it possible to obtain both an improvement in the thermal efficiency of the oven and a very significant increase in the treatment flow rates of the material to be treated. The ovens of the prior art allowing at most treatment flow rates of the order of 150 l / h, it has thus been possible to obtain an increase in flow rate of the order of a factor of three by the use of rotary kilns with plasma according to the present invention. The aforementioned ovens, in particular because of their greater processing capacity, can without disadvantage be used on an industrial scale for the treatment of the most diverse products.

Claims (12)

1. Plasma rotary oven comprising an oven body (1) movable in rotation about an axis (A) and at least one plasma torch (A, B) disposed in the vicinity of one end of the oven body (1) and of the axis (A) of rotation, characterized in that the said oven is equipped, at one end of the oven body (1), with feed means (2) permitting the establishment of a feed flow of material to be treated which is substantially coaxial with the axis (A) of rotation, with a view to obtaining a feed of material to the oven simply by mechanical entrainement.
2. Oven according to claim 1, characterized in that the said feed means (2) and the plasma torch (B) are disposed at the same end of the oven body (1), the feed means (2) and the plasma torch (B) being concentric and having the same axis of revolution, the axis (A) of rotation.
3. Oven according to claim 2, characterized in that the said feed means (2) consist of a hollow Archimedes screw, the said plasma torch (B) being disposed in the hollow part of the screw.
4. Oven according to claim 1, characterized in that the feed means (2) and the plasma torch (A) are disposed at opposite ends of the oven body (1), the said feed means (2) and the plasma torch (A) having, as the same axis of revolution, the axis (A) of rotation of the oven body.
5. Oven according to claim 4, characterized in that the means (2) for feeding material to be treated consist of an Archimedes screw having the axis (A) of rotation of the oven body as axis revolution.
6. Oven according to claim 5, characterized in that the end of the means (2) for feeding material is equipped with a wear piece (20) forming an anode, the said wear piece (20) forming an anode being intended to act as counter electrode for the plasma torch (A) disposed in the vicinity of the opposite end of the oven body.
7. Oven according to one of claims 4 to 6, characterized in that the position of the said means (2) for feeding material is adjustable relative to the corresponding end of the oven body (1), in translation (T) according to the axis (A) of rotation of the oven body.
8. Oven according to one of claims 3 to 7, characterized in that the Archimedes screw is equipped with a casing with a double wall (201, 202) in order to permit the circulation of a cooling fluid between the walls.
9. Oven according to claim 8, characterized in that the said casing comprises, at the end of the screw located in the oven body, an opening (204) placing the helical chamber (200) of the screw in communication with the inside of the oven body in the vicinity of the axis (A) of rotation, the said opening (204) permitting the introduction of the material into the oven body by means of gravity.
10. Oven according to claim 9, characterized in that the helical chamber (200) of the Archimedes screw is fed with material from a hopper (Q).
11. Oven according to one of claims 6 to 10, characterized in that the helix (210) of the Archimedes screw is a hollow helix, the helix body (11) also consisting of a double-walled body in order to ensure the circulation of a cooling fluid, it being possible for the said fluid to enter via the hollow helix (210) and to reemerge via the double-walled body (211).
12. Oven according to one of claims 6 to 11, characterized in that the helix (210) of the Archimedes screw consists of stainless steel, the casing consisting of a softer material.
EP19870401605 1986-07-08 1987-07-08 Plasma-heated rotary drum furnace mechanically fed with materials to be treated Expired - Lifetime EP0252843B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8609911 1986-07-08
FR8609911A FR2601441B1 (en) 1986-07-08 1986-07-08 ROTARY OVEN WITH PLASMA FEEDING MATERIAL TO BE TREATED WITH MECHANICAL DRIVE

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EP0252843A1 EP0252843A1 (en) 1988-01-13
EP0252843B1 true EP0252843B1 (en) 1990-11-22

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EP19870401605 Expired - Lifetime EP0252843B1 (en) 1986-07-08 1987-07-08 Plasma-heated rotary drum furnace mechanically fed with materials to be treated

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EP (1) EP0252843B1 (en)
DE (1) DE3766301D1 (en)
FR (1) FR2601441B1 (en)

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Publication number Priority date Publication date Assignee Title
CN107687762A (en) * 2017-09-29 2018-02-13 北京凯盛建材工程有限公司 A kind of rotary kiln material feeding system and pan feeding method
CN113154872B (en) * 2021-04-22 2022-07-19 重庆科技学院 Low-temperature plasma combined rotary kiln
DE102022130038A1 (en) 2022-11-14 2024-05-16 Khd Humboldt Wedag Gmbh Process for sintering cement clinker

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Publication number Priority date Publication date Assignee Title
US2054156A (en) * 1935-04-09 1936-09-15 Fritz A B Finkeldey Method and apparatus for feeding cement kilns
FR92209E (en) * 1964-04-03
FR1526999A (en) * 1967-02-20 1968-05-31 Commissariat Energie Atomique Rotary melting furnace
BE757149A (en) * 1969-10-24 1971-03-16 Commissariat Energie Atomique AXIAL LOADING DEVICE OF A ROTARY FUSION OVEN
BE778912A (en) * 1972-02-03 1972-08-03 Soudure Autogene Elect Rotating molten material - in fixed high temp furnace by action of rotating magnetic field
US3795752A (en) * 1973-04-25 1974-03-05 Soudure Electr Aatogene Electric furnace

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FR2601441B1 (en) 1988-11-18
EP0252843A1 (en) 1988-01-13
FR2601441A1 (en) 1988-01-15
DE3766301D1 (en) 1991-01-03

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