EP0056225A1 - Plasma melting furnace - Google Patents

Plasma melting furnace Download PDF

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Publication number
EP0056225A1
EP0056225A1 EP81890211A EP81890211A EP0056225A1 EP 0056225 A1 EP0056225 A1 EP 0056225A1 EP 81890211 A EP81890211 A EP 81890211A EP 81890211 A EP81890211 A EP 81890211A EP 0056225 A1 EP0056225 A1 EP 0056225A1
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EP
European Patent Office
Prior art keywords
bottom electrode
metal layer
melting furnace
electrode
plasma melting
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Granted
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EP81890211A
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German (de)
French (fr)
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EP0056225B1 (en
Inventor
Walter Dipl.-Ing. Dr. Lugscheider
Ernst Riegler
Ernst Zajicek
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Voestalpine AG
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Voestalpine AG
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    • 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
    • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
    • F27B3/08—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces heated electrically, with or without any other source of heat
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/16—Remelting metals
    • C22B9/22—Remelting metals with heating by wave energy or particle radiation
    • C22B9/226—Remelting metals with heating by wave energy or particle radiation by electric discharge, e.g. plasma
    • 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
    • H05B7/02—Details
    • H05B7/06—Electrodes
    • 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
    • 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
    • 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
    • H05H1/3473—Safety means

Definitions

  • the invention relates to a plasma melting furnace with a water-cooled bottom electrode made of copper, a temperature sensor connected to the bottom electrode and a wear part made of steel covering the bottom electrode in the bottom of the furnace, at least one counter electrode being arranged at a distance above the wearing part to form the plasma jet.
  • the plasma jet is guided between the bottom electrode (anode) and the counter electrode (s) (cathode (s)).
  • the water-cooled bottom electrode is monitored by means of a temperature measuring device, u. the electrodes are switched off when a certain temperature is exceeded in order to prevent water from breaking through into the steel bath of the furnace.
  • the refractory lining of the furnace wears out, whereby the wear part on the base electrode melts accordingly and shortens in the direction of the water-cooled base electrode.
  • the bottom electrode carries the current of all plasma torches.
  • the total current of the bottom electrode is between 10,000 and 50,000 A.
  • the decisive factor for the smooth functioning of the furnace is good contact of the scrap or bath with the wearing part on the bottom electrode.
  • In the case of insufficient electrical conductivity of the contact point in the In the area of the bottom electrode there is the possibility of forming secondary arcs between the scrap and the wearing part.
  • Such secondary arcs can lead to severe local overheating on the wearing part and on the bottom electrode itself, so that there is a risk of the entire bottom electrode melting through (in the manner of a flame cut) down to the water-cooled part.
  • the pressurized cooling water would penetrate into the hearth below the molten bath and lead to detonating gas explosions and thus to a hazard to the furnace and the operating personnel.
  • the process of melting the electrode takes place at a very high speed, so that the temperature measuring device is unable to give a warning message in order to shut down the system.
  • the invention has for its object to provide a furnace of the type mentioned, in which the risk of melting the bottom electrode down to its water-cooled part due to secondary arcs is avoided.
  • a metal layer of lead or zinc, cadmium, gallium, indium, tin, antimony or bismuth or their alloys is preferably provided in the two-component and multi-component system.
  • the metal layer expediently rests on the end face of the base electrode.
  • the metal layer is designed as a covering hood surrounding the upper part of the base electrode with a protruding edge flange.
  • the metal layer has a thickness between 5 and 30 mm, preferably a thickness of about 20 mm.
  • the wearing part, the metal layer and the upper part of the base electrode are combined to form a coherent structural unit by a connecting part which is preferably L-shaped in cross section.
  • Fig. 1 shows a plasma melting plant in side view and Fig. 2 in plan.
  • Fig. 3 shows a section through the axis of the bottom electrode of the plasma melting plant in a schematic representation.
  • An upper part 1 of a plasma melting furnace, in particular a plasma primary melting furnace, is provided with a cover 2, which is supported by a cover supporting structure 3.
  • a flue gas manifold 4 projects from the cover to a suction device, not shown.
  • the lid lifting mechanism 5 and the lid pivoting mechanism 6 are arranged laterally next to the furnace upper part 1.
  • the furnace lower part 7 rests with weighing beams 8 on raceways 9 supported on the foundation 10.
  • Each of the three plasma torches 11 is movably supported on an inclined burner mechanism 12.
  • the slag door is designated 13 and the pouring spout 14.
  • the bottom electrode 16 arranged centrally in the bottom 15 of the plasma melting furnace protrudes through the metal jacket 17 of the furnace into the interior thereof.
  • the refractory lining 18 has a recess at this point, which is closed by a steel wear part 19 against the bottom electrode 16.
  • a metal layer 21 made of a metal with low thermal conductivity and with a low melting point compared to copper and with a high melting enthalpy, preferably a metal layer made of lead, is provided, which not only covers the end face of the electrode, but also also surrounds the electrode peripherally at its end.
  • An outwardly projecting edge flange 22 of this metal layer has an outer diameter which corresponds to the diameter of the wear part 19.
  • a connecting part 23 with an L-shaped cross section is provided, which is fastened on the one hand to the electrode with a weld seam 24 and on the other hand to the wearing part with a weld seam 25.
  • the wearing part, the metal layer and the bottom electrode are combined to form one structural unit.
  • a cooling water supply pipe 27 projects, through which cooling water presses is directed.
  • a temperature sensor 28 is installed in the peripheral side wall of the electrode, which causes the electrodes to be switched off when a maximum permissible temperature is exceeded.
  • the molten steel in the furnace is designated 29.
  • the function of the metal layer is as follows: If a secondary arc is formed, this burns through the wearing part 19 at the speed of a flame cut a channel reaching to the metal layer, which in the illustrated embodiment consists of lead with a thickness of 20 mm. Starting at the interface with the lead layer, a much larger metal volume of the lead layer is melted by the thermal energy input of the secondary arc than previously in the wear part made of steel. After the molten lead is created within a closed volume, the arc is extinguished by the liquid pressure of the molten metal in this area, thus preventing the melting process from proceeding further.
  • lead or its alloys with tin and / or zinc offers the particular advantage of being immiscible or only slightly miscible in the molten state with all steel iron materials for which a plasma furnace is used; mixing with the melt melted in the plasma melting furnace or its contamination is thereby avoided.
  • the thickness of the metal layer depends on the thermodynamic properties of the metal used. A thickness of 20 mm has proven to be particularly advantageous for lead. The layer thickness can be between 5 and 30 mm.

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  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • General Engineering & Computer Science (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Gasification And Melting Of Waste (AREA)
  • Furnace Details (AREA)
  • Plasma Technology (AREA)
  • Discharge Heating (AREA)

Abstract

Bei einem Plasmaschmelzofen mit einer wassergekühlten Bodenelektrode (16) aus Kupfer und einem mit der Bodenelektrode verbundenen Temperaturfühler (28) ist im Boden (17, 18) des Ofens ein die Bodenelektrode abdeckender Verschliessteil (19) aus Stahl vorgesehen, wobei mindestens eine Gegenelektrode zur Ausbildung des Plasmastrahles im Abstand oberhalb des Verschliessteiles (19) angeordnet ist. Um die Gefahr des Durchschmelzens der Bodenelektrode (16) bis in ihren wassergekühlten Teil infolge eines Sekundär-Lichtbogens zu vermeiden, ist zwischen der Bodenelektrode (16) und dem Verschliessteil (19) eine Metallschicht (21) aus einem Metall mit geringer thermischer Leitfähigkeit und mit niedrigem Schmelzpunkt gegenüber Kupfer sowie mit hoher Schmelzenthalpie, vorzugsweise eine Metallschicht aus Blei oder seinen Legierungen mit Zinn und/oder Zink vorgesehen.In a plasma melting furnace with a water-cooled bottom electrode (16) made of copper and a temperature sensor (28) connected to the bottom electrode, a steel closing part (19) covering the bottom electrode is provided in the bottom (17, 18) of the furnace, at least one counter electrode being used for the formation of the plasma jet is arranged at a distance above the closing part (19). In order to avoid the risk of the bottom electrode (16) melting through to its water-cooled part as a result of a secondary arc, there is a metal layer (21) made of a metal with low thermal conductivity and with between the bottom electrode (16) and the closing part (19) Low melting point compared to copper and high enthalpy of fusion, preferably a metal layer made of lead or its alloys with tin and / or zinc is provided.

Description

Die Erfindung betrifft einen Plasmaschmelzofen mit einer wassergekühlten Bodenelektrode aus Kupfer, einem mit der Bodenelektrode verbundenen Temperaturfühler und einem im Boden des Ofens die Bodenelektrode abdeckenden Verschleißteil aus Stahl, wobei mindestens eine Gegenelektrode zur Ausbildung des Plasmastrahles im Abstand oberhalb des Verschleißteiles angeordnet ist.The invention relates to a plasma melting furnace with a water-cooled bottom electrode made of copper, a temperature sensor connected to the bottom electrode and a wear part made of steel covering the bottom electrode in the bottom of the furnace, at least one counter electrode being arranged at a distance above the wearing part to form the plasma jet.

Bei einem Plasmaschmelzofen dieser Art wird der Plasmastrahl zwischen der Bodenelektrode (Anode) und der oder den Gegenelektrode(n) (Kathode(n)) geführt. Die wassergekühlte Bodenelektrode wird mittels einer Temperaturmeßeinrichtung überwacht, u. zw. werden bei Überschreiten einer bestimmten Temperatur die Elektroden abgeschaltet, um einen Durchbruch von Wasser in das Stahlbad des Ofens zu vermeiden.In a plasma melting furnace of this type, the plasma jet is guided between the bottom electrode (anode) and the counter electrode (s) (cathode (s)). The water-cooled bottom electrode is monitored by means of a temperature measuring device, u. the electrodes are switched off when a certain temperature is exceeded in order to prevent water from breaking through into the steel bath of the furnace.

Im Laufe der Ofenreise verschleißt die feuerfeste Auskleidung des Ofens, wobei der Verschleißteil an der Bodenelektrode entsprechend abschmilzt und sich in Richtung der wassergekühlten Bodenelektrode verkürzt. Die Bodenelektrode trägt bei einer Mehrzahl von Gegenelektroden den Strom aller Plasmabrenner.During the course of the furnace journey, the refractory lining of the furnace wears out, whereby the wear part on the base electrode melts accordingly and shortens in the direction of the water-cooled base electrode. In the case of a plurality of counter electrodes, the bottom electrode carries the current of all plasma torches.

Bei den üblichen technischen Größen bekannter Plasmaöfen liegt der Summenstrom der Bodenelektrode zwischen 10000 bis 50000 A. Ausschlaggebend für die reibungslose Funktion des Ofens ist ein guter Kontakt des Schrottes oder Bades mit dem Verschleißteil an der Bodenelektrode. Im Falle ungenügender elektrischer Leitfähigkeit der Kontaktstelle im Bereich der Bodenelektrode besteht die Möglichkeit der Ausbildung von Sekundär-Lichtbögen zwischen dem Schrott und dem Verschleißteil.In the usual technical sizes of known plasma furnaces, the total current of the bottom electrode is between 10,000 and 50,000 A. The decisive factor for the smooth functioning of the furnace is good contact of the scrap or bath with the wearing part on the bottom electrode. In the case of insufficient electrical conductivity of the contact point in the In the area of the bottom electrode there is the possibility of forming secondary arcs between the scrap and the wearing part.

Gegen Ende der Ofenreise kann es weiters vorkommen, daß beim Schrottsetzen die feuerfeste Auskleidung in unmittelbarer Nähe der Bodenelektrode beschädigt wird. Dies kann ebenfalls dazu führen, daß sich zwischen einem Schrottstück und dem Verschleißteil an der Bodenelektrode ein Sekundär-Lichtbogen bildet.Towards the end of the furnace journey, it can also happen that the refractory lining in the immediate vicinity of the base electrode is damaged when the scrap is placed. This can also lead to the formation of a secondary arc between a scrap piece and the wearing part on the bottom electrode.

Solche sekundäre Lichtbögen können zu einer starken örtlichen Überhitzung an dem Verschleißteil und an der Bodenelektrode selbst führen, so daß die Gefahr eines Durchschmelzens der gesamten Bodenelektrode (nach der Art eines Brennschnittes) bis in den wassergekühlten Teil besteht. In einem solchen Durchbruchsfall würde das unter Druck stehende Kühlwasser unterhalb des schmelzflüssigen Bades in den Herd eindringen und zu Knallgasexplosionen und damit zu einer Gefährdung des Ofens und des Bedienungspersonals führen. Der Vorgang des Durchschmelzens der Elektrode erfolgt mit sehr großer Geschwindigkeit, so daß die Temperaturmeßeinrichtung nicht in der Lage ist, eine Warnmeldung zu geben, um die Anlage abzustellen.Such secondary arcs can lead to severe local overheating on the wearing part and on the bottom electrode itself, so that there is a risk of the entire bottom electrode melting through (in the manner of a flame cut) down to the water-cooled part. In such a breakthrough case, the pressurized cooling water would penetrate into the hearth below the molten bath and lead to detonating gas explosions and thus to a hazard to the furnace and the operating personnel. The process of melting the electrode takes place at a very high speed, so that the temperature measuring device is unable to give a warning message in order to shut down the system.

Die Erfindung stellt sich die Aufgabe, einen Ofen der eingangs bezeichneten Art zu schaffen, bei dem die Gefahr des Durchschmelzens der Bodenelektrode bis in ihren wassergekühlten Teil infolge von Sekundär-Lichtbögen vermieden wird.The invention has for its object to provide a furnace of the type mentioned, in which the risk of melting the bottom electrode down to its water-cooled part due to secondary arcs is avoided.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß zwischen der Bodenelektrode und dem Verschleißteil eine Metallschicht aus einem Metall mit geringer thermischer Leitfähigkeit und mit niedrigem Schmelzpunkt gegenüber Kupfer sowie mit hoher Schmelzenthalpie, vorzugsweise eine Metallschicht aus Blei oder seinen Legierungen mit Zinn und/oder Zink vorgesehen ist.This object is achieved in that between the bottom electrode and the wearing part, a metal layer made of a metal with low thermal conductivity and with a low melting point compared to copper and with a high one Enthalpy of fusion, preferably a metal layer of lead or its alloys with tin and / or zinc is provided.

Vorzugsweise ist eine Metallschicht aus Blei oder Zink, Kadmium, Gallium, Indium, Zinn, Antimon oder Wismut oder deren Legierungen im Zweistoff- als auch Mehrstoffsystem vorgesehen.A metal layer of lead or zinc, cadmium, gallium, indium, tin, antimony or bismuth or their alloys is preferably provided in the two-component and multi-component system.

Zweckmäßig liegt die Metallschicht an der Stirnfläche der Bodenelektrode an.The metal layer expediently rests on the end face of the base electrode.

Nach einer bevorzugten Ausführungsform ist die Metallschicht als den Oberteil der Bodenelektrode umgebende Abdeckhaube mit einem abstehenden Randflansch ausgebildet.According to a preferred embodiment, the metal layer is designed as a covering hood surrounding the upper part of the base electrode with a protruding edge flange.

Die Metallschicht weist eine Dicke zwischen 5 und 30 mm, vorzugsweise eine Dicke von etwa 20 mm, auf.The metal layer has a thickness between 5 and 30 mm, preferably a thickness of about 20 mm.

Nach einer weiteren bevorzugten Ausführungsform sind der Verschleißteil, die Metallschicht und der Oberteil der Bodenelektrode durch einen im Querschnitt vorzugsweise L-förmig geformten Verbindungsteil zu einer zusammenhängenden Baueinheit vereinigt.According to a further preferred embodiment, the wearing part, the metal layer and the upper part of the base electrode are combined to form a coherent structural unit by a connecting part which is preferably L-shaped in cross section.

Die Erfindung ist nachfolgend anhand der Zeichnung näher erläutert, wobei Fig. 1 eine Plasmaschmelzanlage in Seitenansicht und Fig. 2 im Grundriß zeigen. Fig. 3 stellt einen Schnitt durch die Achse der Bodenelektrode der Plasmaschmelzanlage in schematischer Darstellung dar.The invention is explained in more detail below with reference to the drawing, in which Fig. 1 shows a plasma melting plant in side view and Fig. 2 in plan. Fig. 3 shows a section through the axis of the bottom electrode of the plasma melting plant in a schematic representation.

Ein Ofenoberteil 1 eines Plasmaschmelzofens, insbesondere eines Plasmaprimärschmelzofens, ist mit einem Deckel 2, der von einem Deckeltragwerk 3 getragen ist, versehen.An upper part 1 of a plasma melting furnace, in particular a plasma primary melting furnace, is provided with a cover 2, which is supported by a cover supporting structure 3.

Von dem Deckel aus ragt ein Rauchgaskrümmer 4 zu einer nicht dargestellten Absaugung. Seitlich neben dem Ofenoberteil 1 ist das Deckelhubwerk 5 und das Deckelschwenkwerk 6 angeordnet. Der Ofenunterteil 7 ruht mit Wiegebalken 8 auf am Fundament 10 abgestützten Laufbahnen 9. Jeder der drei Plasmabrenner 11 ist auf einem Schrägbrennermechanismus 12 verfahrbar gelagert. Die Schlackentüre ist mit 13 und die Abgießschnauze mit 14 bezeichnet.A flue gas manifold 4 projects from the cover to a suction device, not shown. The lid lifting mechanism 5 and the lid pivoting mechanism 6 are arranged laterally next to the furnace upper part 1. The furnace lower part 7 rests with weighing beams 8 on raceways 9 supported on the foundation 10. Each of the three plasma torches 11 is movably supported on an inclined burner mechanism 12. The slag door is designated 13 and the pouring spout 14.

Wie aus Fig. 3 ersichtlich ist, ragt die im Boden 15 des Plasmaschmelzofens zentral angeordnete Bodenelektrode 16 durch den Metallmantel 17 des Ofens in das Innere desselben. Die feuerfeste Auskleidung 18 weist an dieser Stelle eine Ausnehmung auf, die von einem Verschleißteil 19 aus Stahl gegen die Bodenelektrode 16 geschlossen ist. Zwischen dem Verschleißteil 19 und der Stirnfläche 20 der Elektrode ist eine Metallschicht 21 aus einem Metall mit geringer thermischer Leitfähigkeit und mit niedrigem Schmelzpunkt gegenüber Kupfer sowie mit hoher Schmelzenthalpie, vorzugsweise eine Metallschicht aus Blei, vorgesehen, die nicht nur die Stirnfläche der Elektrode bedeckt, sondern die Elektrode an ihrem Ende auch peripher umgibt. Ein nach außen abstehender Randflansch 22 dieser Metallschicht weist einen äußeren Durchmesser auf, der dem Durchmesser des Verschleißteiles 19 entspricht.As can be seen from FIG. 3, the bottom electrode 16 arranged centrally in the bottom 15 of the plasma melting furnace protrudes through the metal jacket 17 of the furnace into the interior thereof. The refractory lining 18 has a recess at this point, which is closed by a steel wear part 19 against the bottom electrode 16. Between the wear part 19 and the end face 20 of the electrode, a metal layer 21 made of a metal with low thermal conductivity and with a low melting point compared to copper and with a high melting enthalpy, preferably a metal layer made of lead, is provided, which not only covers the end face of the electrode, but also also surrounds the electrode peripherally at its end. An outwardly projecting edge flange 22 of this metal layer has an outer diameter which corresponds to the diameter of the wear part 19.

Zur sicheren Verbindung des Verschleißteiles mit der Bodenelektrode ist ein im Querschnitt L-förmiger Verbindungsteil 23 vorgesehen, der einerseits an der Elektrode mit einer Schweißnaht 24 und anderseits am Verschleißteil mit einer Schweißnaht 25 befestigt ist. Dadurch werden der Verschleißteil, die Metallschicht und die Bodenelektrode zu einer Baueinheit vereinigt.To securely connect the wearing part to the bottom electrode, a connecting part 23 with an L-shaped cross section is provided, which is fastened on the one hand to the electrode with a weld seam 24 and on the other hand to the wearing part with a weld seam 25. As a result, the wearing part, the metal layer and the bottom electrode are combined to form one structural unit.

In den Hohlraum 26 der Bodenelektrode ragt ein Kühlwasserzuführungsrohr 27, durch welches Kühlwasser mit Druck eingeleitet wird. In der peripheren Seitenwand der Elektrode ist ein Temperaturfühler 28 eingebaut, der bei überschreiten einer maximal zulässigen Temperatur ein Abschalten der Elektroden bewirkt. Die im Ofen befindliche Stahlschmelze ist mit 29 bezeichnet.In the cavity 26 of the bottom electrode, a cooling water supply pipe 27 projects, through which cooling water presses is directed. A temperature sensor 28 is installed in the peripheral side wall of the electrode, which causes the electrodes to be switched off when a maximum permissible temperature is exceeded. The molten steel in the furnace is designated 29.

Die Funktion der Metallschicht ist folgende: Kommt es zur Bildung eines Sekundär-Lichtbogens, so brennt dieser durch den Verschleißteil 19 mit der Geschwindigkeit eines Brennschnittes einen bis zur Metallschicht, die beim dargestellten Ausführungsbeispiel aus Blei in einer Dicke von 20 mm besteht, reichenden Kanal. Beginnend an der Grenzfläche zur Bleischicht wird durch den Wärmeenergie-Eintrag des Sekundär-Lichtbogens ein wesentlich größeres Metallvolumen der Bleischicht aufgeschmolzen als vorangehend im Verschleißteil aus Stahl. Nachdem das geschmolzene Blei innerhalb eines geschlossenen Volumens entsteht, wird der Lichtbogen durch den Flüssigkeitsdruck des aufgeschmolzenen Metalls in diesem Bereich gelöscht und damit ein weiteres Fortschreiten des Durchschmelzvorganges verhindert.The function of the metal layer is as follows: If a secondary arc is formed, this burns through the wearing part 19 at the speed of a flame cut a channel reaching to the metal layer, which in the illustrated embodiment consists of lead with a thickness of 20 mm. Starting at the interface with the lead layer, a much larger metal volume of the lead layer is melted by the thermal energy input of the secondary arc than previously in the wear part made of steel. After the molten lead is created within a closed volume, the arc is extinguished by the liquid pressure of the molten metal in this area, thus preventing the melting process from proceeding further.

Die Verwendung von Blei bzw. dessen Legierungen mit Zinn und/oder Zink bietet den besonderen Vorteil der Unmischbarkeit bzw. nur geringen Mischbarkeit im aufgeschmolzenen Zustand mit allen Stahleisen-Werkstoffen, für die ein Plasmaofen in Verwendung kommt; dadurch wird eine Vermischung mit der im Plasmaschmelzofen aufgeschmolzenen Schmelze bzw. deren Verunreinigung vermieden.The use of lead or its alloys with tin and / or zinc offers the particular advantage of being immiscible or only slightly miscible in the molten state with all steel iron materials for which a plasma furnace is used; mixing with the melt melted in the plasma melting furnace or its contamination is thereby avoided.

Die Dicke der Metallschicht richtet sich nach den thermodynamischen Eigenschaften des verwendeten Metalles. Für Blei hat sich eine Dicke von 20 mm als besonders vorteilhaft erwiesen. Die Schichtdicke kann zwischen 5 und 30 mm liegen.The thickness of the metal layer depends on the thermodynamic properties of the metal used. A thickness of 20 mm has proven to be particularly advantageous for lead. The layer thickness can be between 5 and 30 mm.

Ist die Metallschicht 21 zwischen der wassergekühlten Elektrode 16 und dem Verschleißteil 19 nicht vorhanden, so kommt es bei Bildung eines Sekundär-Lichtbogens zu einer starken örtlichen überhitzung, deren Bereich relativ klein ist, da die hohe thermische Leitfähigkeit zum gekühlten Bereich der Elektrode sehr rasch eine Erstarrungsfront ausbildet.If the metal layer 21 between the water-cooled electrode 16 and the wearing part 19 is not present, then there is a strong local overheating when a secondary arc is formed, the area of which is relatively small, since the high thermal conductivity to the cooled area of the electrode very quickly results Solidification front.

Dadurch ist das Angebot an geschmolzenem Metall im Bereich des erhitzenden örtlichen Sekundär-Lichtbogens sehr gering,und es besteht keine Chance einer Auslöschung des Sekundär-Lichtbogens durch geschmolzenes Metall und Zufließen des Schmelzkanales. Das Resultat eines solchen Vorganges ist ein freier Kanal durch den Verschleißteil und das Elektrodenmaterial bis zum Kühlwasserbereich, ähnlich einem Trennschnitt mit der Folge des Wassereintrittes in die Schmelze.As a result, the supply of molten metal in the area of the heating local secondary arc is very small, and there is no chance of the secondary arc being extinguished by molten metal and the melting channel flowing in. The result of such a process is a free channel through the wear part and the electrode material up to the cooling water area, similar to a separating cut with the consequence of water entering the melt.

Claims (6)

1. Plasmaschmelzofen mit einer wassergekühlten Bodenelektrode (16) aus Kupfer, einem mit der Bodenelektrode verbundenen Temperaturfühler (28) und einem im Boden (17, 18) des Ofens die Bodenelektrode (16) abdekkenden Verschleißteil (19) aus Stahl, wobei mindestens eine Gegenelektrode (11) zur Ausbildung des Plasmastrahles im Abstand oberhalb des Verschleißteiles (19) angeordnet ist, dadurch gekennzeichnet, daß zwischen der Bodenelektrode (16) und dem Verschleißteil (19) eine Metallschicht (21) aus einem Metall mit geringer thermischer Leitfähigkeit und mit niedrigem Schmelzpunkt gegenüber Kupfer sowie mit hoher Schmelzenthalpie, vorzugsweise eine Metallschicht aus Blei oder seinen Legierungen mit Zinn und/oder Zink vorgesehen ist.1. plasma melting furnace with a water-cooled bottom electrode (16) made of copper, a temperature sensor (28) connected to the bottom electrode and a wear part (19) covering the bottom electrode (16) of steel in the bottom (17, 18) of the furnace, at least one counter electrode (11) for forming the plasma jet is arranged at a distance above the wearing part (19), characterized in that between the bottom electrode (16) and the wearing part (19) is a metal layer (21) made of a metal with low thermal conductivity and a low melting point compared with copper and with a high enthalpy of fusion, preferably a metal layer made of lead or its alloys with tin and / or zinc is provided. 2. Plasmaschmelzofen nach Anspruch 1, dadurch gekennzeichnet, daß eine Metallschicht (21) aus Blei oder Zink, Kadmium, Gallium, Indium, Zinn, Antimon oder Wismut oder deren Legierungen im Zweistoff- als auch Mehrstoffsystem vorgesehen ist.2. Plasma melting furnace according to claim 1, characterized in that a metal layer (21) made of lead or zinc, cadmium, gallium, indium, tin, antimony or bismuth or their alloys is provided in the two-component and multi-component system. 3. Plasmaschmelzofen nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Metallschicht (21) an der Stirnfläche (20) der Bodenelektrode (16) anliegt.3. Plasma melting furnace according to claim 1 or 2, characterized in that the metal layer (21) on the end face (20) of the bottom electrode (16) abuts. 4. Plasmaschmelzofen nach den Ansprüchen 1 bis 3, dadurch gekennzeichnet, daß die Metallschicht (21) als den Oberteil der Bodenelektrode (16) umgebende Abdeckhaube mit einem abstehenden Randflansch (22) ausgebildet ist.4. Plasma melting furnace according to claims 1 to 3, characterized in that the metal layer (21) as the upper part of the bottom electrode (16) surrounding the hood is formed with a protruding edge flange (22). 5. Plasmaschmelzofen nach den Ansprüchen 1 bis 4, dadurch gekennzeichnet, daß die Metallschicht (21) eine Dicke zwischen 5 und 30 mm, vorzugsweise eine Dicke von etwa 20 mm aufweist.5. Plasma melting furnace according to claims 1 to 4, characterized in that the metal layer (21) has a thickness between 5 and 30 mm, preferably a thickness of about 20 mm. 6. Plasmaschmelzofen nach den Ansprüchen 1 bis 5, dadurch gekennzeichnet, daß der Verschleißteil (19), die Metallschicht (21) und der Oberteil der Bodenelektrode (16) durch einen im Querschnitt vorzugsweise L-förmig geformten Verbindungsteil (23) zu einer zusammenhängenden Baueinheit vereinigt sind.6. Plasma melting furnace according to claims 1 to 5, characterized in that the wearing part (19), the metal layer (21) and the upper part of the bottom electrode (16) by a cross-section, preferably L-shaped connecting part (23) to form a coherent structural unit are united.
EP81890211A 1981-01-08 1981-12-28 Plasma melting furnace Expired EP0056225B1 (en)

Applications Claiming Priority (2)

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AT31/81 1981-01-08
AT3181 1981-01-08

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EP0056225B1 EP0056225B1 (en) 1984-05-23

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JP (1) JPS594630B2 (en)
CA (1) CA1168683A (en)
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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0118412A2 (en) * 1983-02-03 1984-09-12 VOEST-ALPINE Aktiengesellschaft Method of carrying out melting, melt-metallurgical and/or reduction-metallurgical processes in a plasma melting furnace as well as an arrangement for carrying out the method
GB2149279A (en) * 1983-10-28 1985-06-05 Mannesmann Ag Vessel with fluid cooled electrode
EP0178981A1 (en) * 1984-10-01 1986-04-23 UNION SIDERURGIQUE DU NORD ET DE L'EST DE LA FRANCE par abréviation "USINOR" Electrode structure for a molten metal bath
FR2591325A1 (en) * 1985-12-05 1987-06-12 Mannesmann Ag BACKGROUND ELECTRODE FOR FUSION OVENS
AT385520B (en) * 1986-07-22 1988-04-11 Voest Alpine Ag METHOD FOR PRODUCING COPPER AND OVEN FOR CARRYING OUT THE METHOD
DE4026897A1 (en) * 1990-08-23 1992-02-27 Mannesmann Ag Metallurgical vessel for electric arc furnace - has two=part electrode in base with connections for current and cooling water
FR2682003A1 (en) * 1991-09-30 1993-04-02 Siderurgie Fse Inst Rech WALL ELECTRODE FOR DIRECT CURRENT ELECTRIC METALLURGICAL OVEN.
EP0649270A1 (en) * 1993-10-15 1995-04-19 USINOR SACILOR Société Anonyme Metallurgical vessel with a bottom electrode

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT382595B (en) * 1982-12-22 1987-03-10 Sueddeutsche Kalkstickstoff PLANT FOR THE PRODUCTION OF CALCIUM CARBIDE
JPS604787A (en) * 1983-06-22 1985-01-11 石川島播磨重工業株式会社 Furnace-bottom electrode of direct current arc furnace

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1941282A1 (en) * 1968-08-15 1970-02-19 United States Steel Corp Process for refining steel by remelting it in a plasma arc
US3671655A (en) * 1969-12-25 1972-06-20 Daido Steel Co Ltd Electrical transfer type plasma arc melting furnace
US3790742A (en) * 1971-08-24 1974-02-05 Messer Griesheim Gmbh Nozzle
DE2715697A1 (en) * 1977-04-07 1978-10-19 Barbaschin Hermetically sealable arc furnace - used for the plasma arc welding of high alloy steels and other alloys
DE2755560A1 (en) * 1977-12-07 1979-06-21 Inst Elektroswarki Patona ELECTRODE UNIT FOR PLASMA CARTRIDGE

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1271093A (en) * 1917-03-01 1918-07-02 Frederick T Snyder Electric-furnace contact.
US3717713A (en) * 1971-02-18 1973-02-20 M Schlienger Arc furnace crucible
US4101725A (en) * 1976-08-16 1978-07-18 Nikolai Semenovich Shelepov Hearth electrode for melting furnaces
US4137422A (en) * 1977-04-19 1979-01-30 Barbashin Oleg A Airtight metal melting furnace

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1941282A1 (en) * 1968-08-15 1970-02-19 United States Steel Corp Process for refining steel by remelting it in a plasma arc
US3671655A (en) * 1969-12-25 1972-06-20 Daido Steel Co Ltd Electrical transfer type plasma arc melting furnace
US3790742A (en) * 1971-08-24 1974-02-05 Messer Griesheim Gmbh Nozzle
DE2715697A1 (en) * 1977-04-07 1978-10-19 Barbaschin Hermetically sealable arc furnace - used for the plasma arc welding of high alloy steels and other alloys
DE2755560A1 (en) * 1977-12-07 1979-06-21 Inst Elektroswarki Patona ELECTRODE UNIT FOR PLASMA CARTRIDGE

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0118412A2 (en) * 1983-02-03 1984-09-12 VOEST-ALPINE Aktiengesellschaft Method of carrying out melting, melt-metallurgical and/or reduction-metallurgical processes in a plasma melting furnace as well as an arrangement for carrying out the method
EP0118412A3 (en) * 1983-02-03 1985-04-17 VOEST-ALPINE Aktiengesellschaft Method of carrying out melting, melt-metallurgical and/or reduction-metallurgical processes in a plasma melting furnace as well as an arrangement for carrying out the method
GB2149279A (en) * 1983-10-28 1985-06-05 Mannesmann Ag Vessel with fluid cooled electrode
FR2558677A1 (en) * 1983-10-28 1985-07-26 Mannesmann Ag ARRANGEMENT OF ELECTRODES IN CONTAINERS SUBJECT TO THERMAL CONSTRAINTS
EP0178981A1 (en) * 1984-10-01 1986-04-23 UNION SIDERURGIQUE DU NORD ET DE L'EST DE LA FRANCE par abréviation "USINOR" Electrode structure for a molten metal bath
FR2591325A1 (en) * 1985-12-05 1987-06-12 Mannesmann Ag BACKGROUND ELECTRODE FOR FUSION OVENS
AT385520B (en) * 1986-07-22 1988-04-11 Voest Alpine Ag METHOD FOR PRODUCING COPPER AND OVEN FOR CARRYING OUT THE METHOD
DE4026897A1 (en) * 1990-08-23 1992-02-27 Mannesmann Ag Metallurgical vessel for electric arc furnace - has two=part electrode in base with connections for current and cooling water
FR2682003A1 (en) * 1991-09-30 1993-04-02 Siderurgie Fse Inst Rech WALL ELECTRODE FOR DIRECT CURRENT ELECTRIC METALLURGICAL OVEN.
EP0536018A1 (en) * 1991-09-30 1993-04-07 Irsid Wall electrode for metallurgical electric direct current furnace
US5287382A (en) * 1991-09-30 1994-02-15 Unimetal Wall electrode for a DC electric metallurgical furnace
EP0649270A1 (en) * 1993-10-15 1995-04-19 USINOR SACILOR Société Anonyme Metallurgical vessel with a bottom electrode
FR2711233A1 (en) * 1993-10-15 1995-04-21 Usinor Sacilor Metallurgical vessel having a sole electrode
US5588018A (en) * 1993-10-15 1996-12-24 Usinor Sacilor Societe Metallurgical container comprising a hearth bottom electrode

Also Published As

Publication number Publication date
FI814185L (en) 1982-07-09
CA1168683A (en) 1984-06-05
US4423512A (en) 1983-12-27
DE3163776D1 (en) 1984-06-28
EP0056225B1 (en) 1984-05-23
ES508569A0 (en) 1982-11-01
ES8301089A1 (en) 1982-11-01
JPS57142476A (en) 1982-09-03
ZA818985B (en) 1983-03-30
JPS594630B2 (en) 1984-01-31

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