EP0270520B1 - Méthode d'allumage d'un arc à plasma - Google Patents

Méthode d'allumage d'un arc à plasma Download PDF

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Publication number
EP0270520B1
EP0270520B1 EP87890271A EP87890271A EP0270520B1 EP 0270520 B1 EP0270520 B1 EP 0270520B1 EP 87890271 A EP87890271 A EP 87890271A EP 87890271 A EP87890271 A EP 87890271A EP 0270520 B1 EP0270520 B1 EP 0270520B1
Authority
EP
European Patent Office
Prior art keywords
auxiliary
plasma
burner
melting stock
circuit
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
EP87890271A
Other languages
German (de)
English (en)
Other versions
EP0270520A2 (fr
EP0270520A3 (en
Inventor
Heinz Dipl.-Ing. Dr. techn. Müller
Reinhard Dipl.-Ing. Buzzi
Gerhard Dipl.-Ing. Scheiblhofer
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.)
Primetals Technologies Austria GmbH
Original Assignee
Voest Alpine Industrienlagenbau GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Voest Alpine Industrienlagenbau GmbH filed Critical Voest Alpine Industrienlagenbau GmbH
Publication of EP0270520A2 publication Critical patent/EP0270520A2/fr
Publication of EP0270520A3 publication Critical patent/EP0270520A3/de
Application granted granted Critical
Publication of EP0270520B1 publication Critical patent/EP0270520B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H05B7/005—Electrical diagrams
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • H05H1/36—Circuit arrangements

Definitions

  • an auxiliary plasma arc being ignited when the main circuit is already connected to the plasma torch between the electrode of the plasma torch and a torch jacket surrounding the electrode and blown by adding gas to a length of about 10 cm, whereupon the plasma torch is brought closer to the melting material placed in the furnace vessel until the main plasma arc ignites. The plasma torch is then moved back to the desired position.
  • the invention aims to avoid these disadvantages and difficulties and has as its object to provide a method for igniting a plasma arc and a device for carrying out the method, which ensure high and uniform burner service lives, particularly in high-performance furnaces.
  • This object is achieved in a method of the type described in the introduction in that, with the main circuit switched off, the electrode of the plasma torch and the melt material charged in the furnace vessel are placed on the auxiliary circuit and an auxiliary plasma arc is ignited between the plasma torch and the melt material, whereupon the plasma torch is separated from the melt material is moved back with the extension of the auxiliary plasma arc and then the main circuit is connected to the plasma torch and the melting material and the plasma arc is ignited.
  • the plasma arc is only ignited when the plasma torch is at a safe distance from the melting material, splashes occurring during the ignition process can no longer reach the plasma torch. While the auxiliary plasma arc is ignited, touching the torch with the melted material is irrelevant, since the current flowing through the auxiliary circuit does not destroy the electrode of the plasma torch or the torch jacket. Since the plasma arc is only ignited when the plasma torch is far away from the melting material, there can be none even if the slag cover is poorly conductive or the furnace atmosphere is cold - i.e. with short ignition intervals Damage to the electrode of the plasma torch or the torch jacket.
  • auxiliary plasma arc that is burning between the melting material and the plasma torch between the electrode of the plasma torch and the torch jacket surrounding the electrode and connected to the auxiliary circuit, which is preferably at the same potential as the melting material is, an auxiliary plasma arc ignited with the aid of the auxiliary circuit, whereupon the plasma torch is brought closer to the melting material until this auxiliary plasma arc overturns on the melting material.
  • the burner jacket is preferably separated from the auxiliary circuit.
  • the current of the auxiliary circuit flowing over the melting material is advantageously measured and a switching device which switches off the burner jacket from the auxiliary circuit is actuated as a function of the measured current of the auxiliary circuit, as a result of which the thermal load on the burner can be kept very low and time and energy savings result.
  • the switching device is advantageously actuated when a partial current flows. Furthermore, the burner does not need to be moved any closer to the melting material than is absolutely necessary. This process step also enables fully automatic control of the ignition process.
  • the voltage of the auxiliary circuit is advantageously measured after the ignition of the auxiliary plasma arc between the plasma torch and the melting material the connection of the main circuit depending on the measured voltage.
  • the plasma arc is switched on automatically, without having to take distance measurements between the burner and the melting material or having to observe this distance. This also saves time and energy.
  • a device for carrying out the method with a metallurgical furnace vessel having a plasma torch which plasma torch can be connected to a main circuit and to an auxiliary circuit and can be moved to different heights by means of an actuator relative to the bottom of the furnace vessel, is characterized in that the auxiliary circuit has a Switching device having line is connected to the melting material in terms of lines.
  • the auxiliary circuit can be connected to the burner jacket with a line branching from the line leading to the melting material and equipped with a switching device.
  • a current measuring device is advantageously provided in the line leading to the melting material and is connected via a control line to the switching device provided in the line leading to the burner jacket.
  • a voltage measuring device is expediently provided in the auxiliary circuit and is connected to a switching device provided in the main circuit by means of a control line.
  • FIG. 1 a vertical section through an oven vessel and FIG. 2 a Show circuit diagram for performing the ignition process according to the invention.
  • 3 shows a schematic diagram of a circuit diagram for a three-phase plasma torch.
  • a plasma furnace 1 has a furnace vessel 3 provided with a refractory lining 2 and is covered by a cover 4. An opening 5 is provided centrally in the cover 4, through which a plasma torch 6 projects.
  • the plasma torch 6 can be raised and lowered by means of an actuator 7, so that it can be approached or removed from the melting material 9 charged in the furnace interior 8.
  • a bottom electrode 11 is arranged centrally and opposite the plasma torch 6.
  • the plasma torch 6 is formed by a central electrode 12 and a torch jacket 13, which is preferably water-cooled and surrounds the electrode.
  • the plasma torch 6 and the bottom electrode 11 (and thus the melting material 9) can be connected to an auxiliary circuit 14 and / or to a main circuit 15.
  • the current source of the auxiliary circuit 14 is designated 16. It is via a main switching device 17, a transformer 18 and a rectifier 19 by means of a line 20 connected to the negative potential with the electrode 12 of the plasma torch 6 and by means of a line 21 connected to the positive potential with the melting material 9 via the bottom electrode 11 connected.
  • Controllable switching devices 22 are provided both in the line 20 leading to the electrode 12 and in the line 21 leading to the melt 9.
  • a series resistor 23 is also provided in the line 20 leading to the electrode 12 of the plasma torch 6 for current limitation and determination of the operating point.
  • the same is effected by a choke inserted between the transformer 18 and the rectifier 19.
  • a voltmeter 29 is connected, which is connected by means of a control line 30 to a switching device 31 which is provided in the main circuit 15.
  • the main circuit 15 is connected to a main power source 32 via a transformer 33 and a rectifier 34.
  • a DC choke 35 is provided between the switching device 31 of the main circuit 15 and the connection to the electrode 12 of the plasma torch 6.
  • the function of the facility is as follows: To ignite the plasma arc, when the main circuit 15 is switched off, the switching devices 22 provided in the lines 20, 21 to the electrode 12 of the plasma torch 6 and to the bottom electrode 11 are first closed, but the switching device 28 remains open. The switching device 25 provided in the line 24, which is connected to the burner jacket 13, and the main switching device 17 of the auxiliary circuit 14 are then closed. The burner jacket 13 and the melting material 9 is not yet at the same potential.
  • auxiliary plasma arc is then ignited between the burner electrode 12 and the burner jacket 13 with the aid of an auxiliary igniter 36.
  • the plasma burner 6 is still at a greater distance 37 from the melt material 9 (or the bath surface).
  • the plasma torch is brought closer to the melting material 9 by means of the actuator 7, and so on. until an auxiliary plasma arc ignites between the melt 9 and the burner electrode 12 or the auxiliary plasma arc ignited first between the burner jacket 13 and the electrode 12 of the plasma torch 6 overlaps the melt 9 due to the lower voltage drop.
  • the ammeter 27 is used to determine this flashover. As soon as it registers a certain minimum value, the burner jacket 13 is separated from the auxiliary circuit 14, and so on. by opening the switching device 25 arranged in the line 24 leading to the burner jacket 13. This is accomplished via a control line 38 which connects this switching device 25 to the ammeter 27. The entire current of the auxiliary circuit 14 is thus conducted via the bottom electrode 11.
  • the plasma torch 6 is moved back from the melt 9, whereby the auxiliary plasma arc burning between the burner electrode 12 and the melt 9 is extended.
  • a predetermined extent which depends, among other things, on the distance of the plasma torch 6 from the melt material 9, which is determined by means of the voltmeter 29, is carried out via the from the voltmeter 29 to the switching device 31 of the main circuit 15 leading control line 30 of the main circuit 15 is placed on the melt 9 and the burner electrode 12, whereby the plasma arc ignites instantaneously.
  • a distance 37 of the plasma torch 6 from the melting material of approximately 30 cm Thereupon the auxiliary circuit 14 is separated both from the melting material 9 and from the burner electrode 12, etc. by opening switchgear 17, 22 and 28.
  • the invention is not limited to the exemplary embodiment shown, but can be modified in various ways. It can be implemented not only in direct current circuits, but also in alternating current circuits.
  • a basic circuit for three-phase plasma torches is shown in FIG. 3, the ignition devices 39 shown there with broken lines each comprising the circuit parts which are enclosed in the rectangle 40 formed by broken lines in FIG. 2.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Gasification And Melting Of Waste (AREA)
  • Furnace Details (AREA)
  • Plasma Technology (AREA)

Claims (9)

  1. Procédé pour allumer un arc à plasma alimenté par un circuit électrique principal (15) d'une torche à plasma (6) prévue dans une carcasse de four métallurgique (3) à l'aide d'un arc à plasma auxiliaire alimenté par un circuit électrique auxiliaire (14), caractérisé en ce que l'on relie l'électrode (12) de la torche à plasma (6) et la matière à fondre ou en fusion (9) chargée dans la carcasse de four (3) au circuit auxiliaire (14) alors que le circuit principal (15) est déconnecté, et on allume entre la torche à plasma (6) et la matière (9) un arc à plasma auxiliaire, on fait reculer ensuite la torche à plasma (6) de la matière (9), en allongeant l'arc à plasma auxiliaire, puis on relie le circuit principal (15) à la torche à plasma et à la matière (9) et on allume l'arc à plasma.
  2. Procédé selon la revendication 1, caractérisé en ce que, avant d'allumer l'arc à plasma auxiliaire entre la matière à fondre ou en fusion (9) et la torche à plasma (6), on allume, à l'aide du circuit électrique auxiliaire (14), un arc à plasma auxiliaire entre l'électrode (12) de la torche à plasma et l'enveloppe (13) de la torche, enveloppe qui entoure l'électrode (12) et est reliée au circuit auxiliaire (14), l'enveloppe (13) de la torche se trouvant de préférence au même potentiel que la matière (9), et on approche ensuite la torche à plasma (6) de la matière jusqu'à ce que cet arc à plasma auxiliaire passe sur là matière à fondre ou en fusion (9).
  3. Procédé selon la revendication 2, caractérisé en ce que, lorsque l'arc à plasma auxiliaire établi entre la matière à fondre ou en fusion (9) et l'électrode (12) de la torche à plasma (6) a commencé à faire circuler au moins un courant partiel, on coupe l'enveloppe (13) de la torche du circuit électrique auxiliaire (14).
  4. Procédé selon la revendication 3, caractérisé en ce que l'on mesure le courant dit circuit électrique auxiliaire (14) circulant par la matière à fondre ou en fusion (9) et on actionne un appareil interrupteur (25) coupant l'enveloppe (13) de la torche du circuit auxiliaire (14) en fonction du courant mesuré de ce circuit auxiliaire.
  5. Procédé selon une ou plusieurs des revendications 1 à 4, caractérisé en ce que, après l'allumage de l'arc à plasma auxiliaire contre la torche (6) et la matière à fondre ou en fusion (9), on mesure la tension du circuit électrique auxiliaire (14) et on effectue la connexion du circuit électrique principal (15) en fonction de la tension mesurée.
  6. Dispositif pour la mise en oeuvre du procédé selon une ou plusieurs des revendications 1 à 5, comprenant une carcasse de four métallurgique (3) présentant une torche à plasma (6) qui peut être raccordée à un circuit électrique principal (15) et un circuit électrique auxiliaire (14) et est déplaçable à différentes positions en hauteur par rapport au fond (10) de le carcasse de four (3) au moyen d'une servocommande (7), caractérisé en ce que le circuit auxiliaire (14) est relié électriquement à la matière à fondre ou en fusion (9) par une ligne (21) contenant un appareil interrupteur (28).
  7. Dispositif selon la revendication 6, caractérisé en ce que le circuit auxiliaire (14) peut être raccordé à l'enveloppe (13) de la torche par une ligne (24), munie d'un appareil interrupteur (25), qui est branchée en dérivation sur la ligne (21) menant à la matière à fondre ou en fusion (9).
  8. Dispositif selon la revendication 7, caractérise en ce qu'un appareil de mesure de l'intensité du courant (27) est prévu dans la ligne (21) menant à la matière à fondre ou en fusion (9), appareil de mesure qui est relié par une ligne de commande (38) à l'appareil interrupteur (25) prévu dans la ligne (24) menant à l'enveloppe (13) de la torche.
  9. Dispositif selon une ou plusieurs des revendications 6 à 8, caractérisé en ce qu'un appareil de mesure de tension (29) est prévu dans le circuit électrique auxiliaire (14) et est relié par une ligne de commande (30) à un appareil interrupteur (31) prévu dans le circuit électrique principal (15).
EP87890271A 1986-12-01 1987-11-26 Méthode d'allumage d'un arc à plasma Expired - Lifetime EP0270520B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT0319486A AT386717B (de) 1986-12-01 1986-12-01 Verfahren zum zuenden eines plasmabogens
AT3194/86 1986-12-01

Publications (3)

Publication Number Publication Date
EP0270520A2 EP0270520A2 (fr) 1988-06-08
EP0270520A3 EP0270520A3 (en) 1989-02-01
EP0270520B1 true EP0270520B1 (fr) 1993-01-13

Family

ID=3546806

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87890271A Expired - Lifetime EP0270520B1 (fr) 1986-12-01 1987-11-26 Méthode d'allumage d'un arc à plasma

Country Status (8)

Country Link
US (1) US4764208A (fr)
EP (1) EP0270520B1 (fr)
JP (1) JPS63148600A (fr)
AT (1) AT386717B (fr)
DD (1) DD269741A5 (fr)
DE (1) DE3783586D1 (fr)
FI (1) FI875211A (fr)
NO (1) NO169690C (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5444208A (en) * 1993-03-29 1995-08-22 Fmc Corporation Multiple source plasma generation and injection device

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2119179A6 (fr) * 1970-12-23 1972-08-04 Anvar
BE809746A (fr) * 1974-01-15 1974-05-02 Alimentation en courants electriques (continu et alternatif) d'installations de plasmas a hautes temperatures.
AT331434B (de) * 1974-05-28 1976-08-25 Ver Edelstahlwerke Ag Verfahren zum entfernen unerwunschter elemente, insbesondere h2 und o2 beim elektroschlackenumschmelzen und anordnung zur durchfuhrung des verfahrens
DD122908A1 (fr) * 1975-12-19 1976-11-05
CA1173784A (fr) * 1981-07-30 1984-09-04 William H. Gauvin Reacteur a transport d'arc au plasma pour la chimie et la metallurgie
AT372977B (de) * 1982-01-19 1983-12-12 Voest Alpine Ag Verfahren und einrichtung zur reduktion von oxidhaeltigen feinteiligen erzen
DE3375805D1 (en) * 1982-12-22 1988-04-07 Voest Alpine Ag Method of carrying out metallurgical or chemical processes, and a low-shaft furnace
US4580029A (en) * 1983-10-27 1986-04-01 Union Carbide Corporation Plasma arc power supply and method
AT388271B (de) * 1984-09-26 1989-05-26 Voest Alpine Ag Regelungsvorrichtung fuer einen hochleistungsplasmabrenner, insbesondere fuer einen schmelzofen
CA1278431C (fr) * 1985-09-26 1991-01-02 Nicholas Adrian Barcza Production thermique de magnesium

Also Published As

Publication number Publication date
DE3783586D1 (de) 1993-02-25
FI875211A (fi) 1988-06-02
JPS63148600A (ja) 1988-06-21
NO874991D0 (no) 1987-11-30
NO169690C (no) 1992-07-22
NO874991L (no) 1988-06-02
FI875211A0 (fi) 1987-11-25
NO169690B (no) 1992-04-13
US4764208A (en) 1988-08-16
AT386717B (de) 1988-10-10
EP0270520A2 (fr) 1988-06-08
EP0270520A3 (en) 1989-02-01
ATA319486A (de) 1988-02-15
DD269741A5 (de) 1989-07-05

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