EP1027462A1 - Method and device for controlling the formation of foamed slag in an arc furnace - Google Patents

Method and device for controlling the formation of foamed slag in an arc furnace

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Publication number
EP1027462A1
EP1027462A1 EP98958815A EP98958815A EP1027462A1 EP 1027462 A1 EP1027462 A1 EP 1027462A1 EP 98958815 A EP98958815 A EP 98958815A EP 98958815 A EP98958815 A EP 98958815A EP 1027462 A1 EP1027462 A1 EP 1027462A1
Authority
EP
European Patent Office
Prior art keywords
arc furnace
carbon
foam slag
amount
fed
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.)
Ceased
Application number
EP98958815A
Other languages
German (de)
French (fr)
Inventor
Hans-Herbert Welker
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.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Publication of EP1027462A1 publication Critical patent/EP1027462A1/en
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • C21C5/5211—Manufacture of steel in electric furnaces in an alternating current [AC] electric arc furnace
    • C21C5/5217—Manufacture of steel in electric furnaces in an alternating current [AC] electric arc furnace equipped with burners or devices for injecting gas, i.e. oxygen, or pulverulent materials into the furnace
    • 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
    • F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
    • F27B3/28—Arrangement of controlling, monitoring, alarm or the like devices
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/36—Processes yielding slags of special composition
    • C21C2005/366—Foam slags
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C2300/00—Process aspects
    • C21C2300/02—Foam creation
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0025—Adding carbon material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the invention relates to a method and a device for controlling the foam slag formation in an arc furnace to which carbon is fed in such a way that both an at least partial encapsulation of the arc in the arc furnace takes place and an overdosed supply of carbon is avoided.
  • Foam slag is created by foaming the slag in an arc furnace with carbon dioxide or carbon monoxide and serves to shield the radiation from the arc onto the furnace wall.
  • Such an approach is e.g. known from DE 44 25 089 Cl or EP 0 637 834.
  • the foam slag is controlled as a function of a measured sound emission in the range of twice the mains / supply frequency of the arc furnace.
  • the carbon supply is increased when a switching level that can be predetermined by a control unit is exceeded and the carbon supply is reduced when the switching level is undershot.
  • EP 0 637 834 the foam slag is regulated as a function of a measured noise emission and as a function of electrical variables.
  • a disadvantage of the process according to DE 44 25 089 Cl or according to EP 0 637 834 is that the desired foam slag can be regulated only very slowly, and that conditions can occur for which the foam slag is disproportionately long is too low. In these cases, the power of the arc must be reduced, which increases the duration of the melting process. In an industrial large-scale melting process such as that used in an arc furnace is running, even a brief extension of the melting process is associated with high costs. Accordingly, it is an object of the invention to shorten the melting process in an arc furnace.
  • the object is achieved by a method according to claim 1 or a device according to claim 8.
  • the carbon is fed to the arc furnace in such a way that the arc is at least partially enveloped by foam slag in the arc furnace and an overdosed supply of carbon is avoided.
  • the amount of carbon that is fed to the arc furnace is determined using a foam slag model depending on the amount of at least one of the feed materials scrap, steel, alloying agent or additives. Alloying agents can e.g. Carbon or metals such as manganese, nickel, etc. An additive is e.g. Lime.
  • the determination of the amount of carbon that is supplied to the arc by means of a foam slag model depending on the amount of at least one of the feed materials scrap, steel, alloying agent or additives allows a desired foam slag level to be built up particularly quickly. In this way, it is possible to melt with a particularly high energy input, as a result of which the time required for melting the metal in the arc furnace is reduced.
  • the amount of carbon is determined as a function of all essential coating materials, ie scrap, steel, the essential alloying agents and the essential additives.
  • the combination of coating material rialien and energy supply allows a particularly precise prediction of the foam slag and the necessary carbon supply, whereby the desired foam slag level can be set particularly quickly and precisely.
  • the foam slag model has a neural network.
  • a neural network is particularly suitable for modeling the formation of foam slag, so that a particularly precise foam slag model is obtained by means of the neural network.
  • FIG. 1 shows a three-phase arc furnace with a device for controlling the formation of foam slag
  • FIG. 2 shows the functional interaction of the foam slag model and the arc furnace
  • FIG. 1 shows an electric arc furnace 5, which in the exemplary embodiment is designed as a three-phase electric arc furnace, with a device for controlling the formation of foam slag 4 in the electric arc furnace 5.
  • the electric arc furnace 5 three electrodes 1, 2, 3 are connected, which are connected via an adjustable transformer a three-phase power supply network 8 are connected, scrap melted so that liquid metal 6 accumulates in the lower part of the arc furnace 5.
  • Arcs 9 form between the electrodes 1, 2, 3 and the scrap or the liquid metal 6.
  • the arcs are enveloped by foam slag 4 in order to protect the walls of the arc furnace 5 from the energy radiation from the arcs 9.
  • a device for controlling the foam slag is provided.
  • this has a blow mold 10 and a computing device 11.
  • the blow mold 10 blows carbon, in particular carbon mixed with air, into the arc furnace 5, in particular into the slag above the liquid metal 6.
  • the carbon in the slag converts to carbon dioxide or carbon monoxide, so that foam slag 4 is formed.
  • the amount of carbon to be injected is determined by the computing device 11 as a function of the electrical energy supplied to the arc furnace 5 and as a function of the quantity of charging materials in the arc furnace 5.
  • Feed materials are essentially scrap, alloying agents and additives.
  • An important additive is lime, for example, which forms an important component of the foam slag 4.
  • the supply of electrical energy from the energy supply network 8 is regulated by means of the adjustable transformer 7 and / or by adjusting the height of the electrodes 1, 2, 3. Details of an advantageous regulation of the energy supply in connection with the invention can be found in DE 197 11 453, EP 0 036 122 and DE 44 15 727.
  • the energy supply, in particular the height of the electrodes 1, 2 and 3, is set as a function of the level of the foam slag 4 in the electric arc furnace 5.
  • the computing device 11 determines in a particularly advantageous manner by means of the foam slag model implemented on it, in addition to the target value for the supply of carbon, the current level of the level of the foam slag 4 in the electric arc furnace 5.
  • the regulation of the transformer 7 and the regulation of the height of the electrodes 1 , 2, 3 can also be implemented on the computing device 11 in an exemplary embodiment.
  • FIG. 1 shows, in an exemplary embodiment, an arc furnace 5 designed as a three-phase arc furnace.
  • the invention can also be used particularly advantageously for a direct current arc furnace.
  • the method according to the invention is particularly superior to the method according to DE 44 25 089 Cl and EP 0 637 834, since the significant frequencies m der
  • Noise emission or m the electrical sizes are not or only weakly present.
  • FIG. 2 shows the interaction of a foam slag model 25 with an electric arc furnace 5.
  • the essential processes that take place in the electric arc furnace 5 are the charging 22 of the electric arc furnace 5, the melting process 23 in the electric arc furnace 5 and the tapping 24 of the electric arc furnace 5, in which the liquid metal is tapped in the arc furnace 5.
  • the arc furnace 5 is loaded with a certain amount of feed materials 27 such as scrap, steel, alloying agents and / or additives.
  • Energy 28 is supplied to the arc furnace 5 during the melting process 23.
  • Carbon 29 m is also blown into the arc furnace 5.
  • a foam slag model 25 determines setpoints for the supply of carbon 29 m from the arc furnace 5 from the quantity of the feed materials 27 and the supply of energy 28.
  • the foam slag model 25 is optimized so that it supplies the arc furnace 5 with particularly precise target values for the supply of carbon 29 m.
  • the properties 30 of foam slag which is present in the arc furnace 5 during tapping 24, are fed to an evaluator 26.
  • the evaluator 26 has a learning algorithm that determines new parameters 20 for the foam slag model 25. New parameters 20 are preferably determined as a function of the properties 30 of the foam slag and the properties 19 of the foam slag determined by the foam slag part 25.
  • the properties of the foam slag are e.g. determined by an operator and entered the evaluator 26 via a human-machine interface.
  • the neural network has three input nodes 31, 32, 33, the neural network via the input node 31 information about the amount of scrap in the electric arc furnace, via the input node 32 information about the amount of energy supplied and via the input node 33 information about the supplied Amount of lime to be fed.
  • the neural network has a level with hidden neurons 34, 35 and 36 and an output node 37, via which a setpoint for the carbon supply is output.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)

Abstract

The invention relates to a method and device for controlling the formation of foamed slag in an arc furnace (5) to which the carbon is fed in such a way that the arc is at least partially enveloped in the arc furnace (5) and an over abundant feeding of carbon is avoided. The quantity of the carbon which is fed to the arc furnace is thus determined by means of a foamed slag model (25) according to the quantity of at least one of the coating materials comprised of scrap metal, steel, alloy material or admixtures.

Description

Beschreibungdescription
Verfahren und Einrichtung zur Steuerung der Schaumschlacke- bildung m einem LichtbogenofenMethod and device for controlling foam slag formation in an arc furnace
Die Erfindung betrifft ein Verfahren bzw. eine Einrichtung zur Steuerung der Schaumschlackebildung m einem Lichtbogenofen, dem Kohlenstoff derart zugeführt wird, daß sowohl eine mindestens teilweise Einhüllung des Lichtbogens im Lichtbogenofen erfolgt als auch eine überdosierte Zufuhr von Kohlenstoff vermieden wird.The invention relates to a method and a device for controlling the foam slag formation in an arc furnace to which carbon is fed in such a way that both an at least partial encapsulation of the arc in the arc furnace takes place and an overdosed supply of carbon is avoided.
Schaumschlacke entsteht durch Aufschäumen der Schlacke m einem Lichtbogenofen mit Kohlenstoffdioxid oder Kohlenstoffmon- oxid und dient zum Abschirmen der Strahlung des Lichtbogens auf die Ofenwand. Ein derartiges Vorgehen ist z.B. aus der DE 44 25 089 Cl oder der EP 0 637 834 bekannt. Gemäß der DE 44 25 089 Cl wird die Schaumschlacke m .Abhängigkeit von einer gemessenen Schallemission im Bereich der zweifachen Netz-/Versorgungsfrequenz, des Lichtbogenofens geregelt. Dabei wird bei einem Überschreiten eines durch eine Steuereinheit vorgebbaren Schaltpegels die Kohlenstoffzufuhr erhöht und bei einem Unterschreiten die Kohlenstoffzufuhr vermindert. Gemäß der EP 0 637 834 wird die Schaumschlacke m Ab- hangigkeit von einer gemessenen Schallemission sowie m Abhängigkeit elektrischer Großen geregelt.Foam slag is created by foaming the slag in an arc furnace with carbon dioxide or carbon monoxide and serves to shield the radiation from the arc onto the furnace wall. Such an approach is e.g. known from DE 44 25 089 Cl or EP 0 637 834. According to DE 44 25 089 Cl, the foam slag is controlled as a function of a measured sound emission in the range of twice the mains / supply frequency of the arc furnace. The carbon supply is increased when a switching level that can be predetermined by a control unit is exceeded and the carbon supply is reduced when the switching level is undershot. According to EP 0 637 834, the foam slag is regulated as a function of a measured noise emission and as a function of electrical variables.
Bei dem Verfahren gemäß der DE 44 25 089 Cl bzw. gemäß der EP 0 637 834 ist nachteilig, daß die gewünschte Schaumschlak- ke nur sehr langsam geregelt werden kann, und daß es für unverhältnismäßig lange Zeitabschnitte zu Zustanden kommen kann, m denen die Schaumschlacke zu gering ist. In diesen Fallen ist die Leistung des Lichtbogens zurückzufahren, was die Dauer des Schmelzprozesses erhöht. Bei einem mdustriel- len Großschmelzprozeß, wie er m einem Lichtbogenofen ab- lauft, ist selbst eine kurzzeitige Verlängerung des Schmelzprozesses mit hohen Kosten verbunden. Entsprechend ist es Aufgabe der Erfindung, den Schmelzprozeß m einem Lichtbogenofen zu verkurzen.A disadvantage of the process according to DE 44 25 089 Cl or according to EP 0 637 834 is that the desired foam slag can be regulated only very slowly, and that conditions can occur for which the foam slag is disproportionately long is too low. In these cases, the power of the arc must be reduced, which increases the duration of the melting process. In an industrial large-scale melting process such as that used in an arc furnace is running, even a brief extension of the melting process is associated with high costs. Accordingly, it is an object of the invention to shorten the melting process in an arc furnace.
Die Aufgabe wird erfmdungsgemaß durch ein Verfahren gemäß Anspruch 1 bzw. eine Einrichtung gemäß Anspruch 8 gelost. Dabei wird dem Lichtbogenofen der Kohlenstoff derart zugeführt, daß sowohl eine mindestens teilweise Einhüllung des Lichtbo- gens durch Schaumschlacke im Lichtbogenofen erfolgt als auch eine überdosierte Zufuhr von Kohlenstoff vermieden wird. Er- fmdungsgemaß wird die Menge des Kohlenstoffs, der dem Lichtbogenofen zugeführt wird, mittels eines Schaumschlackenmodells m Abhängigkeit der Menge zumindest eines der Beschik- kungsmateπalien Schrott, Stahl, Legierungsmittel oder Zusatzstoffe ermittelt. Legierungsmittel können z.B. Kohlenstoff oder Metalle wie Mangan, Nickel usw. sein. Ein Zusatzstoff ist z.B. Kalk. Das Ermitteln der Menge des Kohlenstoffs, der dem Lichtbogen zugeführt wird, mittels eines Schaumschlackenmodells m Abhängigkeit der Menge zumindest eines der Beschickungsmaterialien Schrott, Stahl, Legierungs- mittel oder Zusatzstoffe erlaubt ein besonders schnelles Aufbauen eines gewünschten Schaumschlackepegels. Auf diese Weise kann unter besonders hoher Energiezufuhr geschmolzen werden, wodurch sich die notwendige Zeit für das Schmelzen des Metalls im Lichtbogenofen verringert.According to the invention, the object is achieved by a method according to claim 1 or a device according to claim 8. The carbon is fed to the arc furnace in such a way that the arc is at least partially enveloped by foam slag in the arc furnace and an overdosed supply of carbon is avoided. According to the invention, the amount of carbon that is fed to the arc furnace is determined using a foam slag model depending on the amount of at least one of the feed materials scrap, steel, alloying agent or additives. Alloying agents can e.g. Carbon or metals such as manganese, nickel, etc. An additive is e.g. Lime. The determination of the amount of carbon that is supplied to the arc by means of a foam slag model depending on the amount of at least one of the feed materials scrap, steel, alloying agent or additives allows a desired foam slag level to be built up particularly quickly. In this way, it is possible to melt with a particularly high energy input, as a result of which the time required for melting the metal in the arc furnace is reduced.
In besonders vorteilhafter Ausgestaltung der Erfindung wird die Menge des Kohlenstoffs m Abhängigkeit aller wesentlichen Beschichtungsmaterialien, d.h. Schrott, Stahl, der wesentlichen Legierungsmittel und der wesentlichen Zusatzstoffe ermittelt. Außerdem ist es besonders vorteilhaft, die Menge des Kohlenstoffs, der m den Ofen eingeblasen werden soll, zusätzlich m Abhängigkeit der Energiezufuhr m den Lichtbo- genofen zu ermitteln. Die Kombination aus Beschichtungsmate- rialien und Energiezufuhr erlaubt eine besonders präzise Vorhersage der Schaumschlacke und der notwendigen Kohlenstoffzufuhr, wodurch besonders schnell und präzise der gewünschte Schaumschlackenpegel eingestellt werden kann.In a particularly advantageous embodiment of the invention, the amount of carbon is determined as a function of all essential coating materials, ie scrap, steel, the essential alloying agents and the essential additives. In addition, it is particularly advantageous to additionally determine the amount of carbon to be blown into the furnace in dependence on the energy supply in the arc furnace. The combination of coating material rialien and energy supply allows a particularly precise prediction of the foam slag and the necessary carbon supply, whereby the desired foam slag level can be set particularly quickly and precisely.
In einer weiterhin vorteilhaften Ausgestaltung der Erfindung weist das Schaumschlackenmodell ein neuronales Netz auf. Ein neuronales Netz ist besonders geeignet, die Bildung von Schaumschlacke zu modellieren, so daß sich mittels des neuro- nalen Netzes ein besonders präzises Schaumschlackenmodell ergibt.In a further advantageous embodiment of the invention, the foam slag model has a neural network. A neural network is particularly suitable for modeling the formation of foam slag, so that a particularly precise foam slag model is obtained by means of the neural network.
Weitere Vorteile und Einzelheiten ergeben sich aus der nachfolgenden Beschreibung von Ausführungsbeispielen. Im einzelnen zeigen:Further advantages and details emerge from the following description of exemplary embodiments. In detail show:
FIG 1 einen Drehstromlichtbogenofen mit einer Einrichtung zur Steuerung der Schaumschlackenbildung, FIG 2 das funktionale Zusammenwirken von Schaumschlacken- modell und Lichtbogenofen,1 shows a three-phase arc furnace with a device for controlling the formation of foam slag, FIG. 2 shows the functional interaction of the foam slag model and the arc furnace,
FIG 3 ein neuronales Netz.3 shows a neural network.
FIG 1 zeigt einen Lichtbogenofen 5, der in der beispielhaften Ausgestaltung als Drehstromlichtbogenofen ausgebildet ist, mit einer Einrichtung zur Steuerung der Bildung von Schaumschlacke 4 im Lichtbogenofen 5. Im Lichtbogenofen 5 wird mit drei Elektroden 1, 2, 3, die über einen stellbaren Transformator an ein dreiphasiges Energieversorgungsnetz 8 angeschlossen sind, Schrott geschmolzen, so daß sich flüssiges Metall 6 im unteren Teil des Lichtbogenofens 5 ansammelt. Zwischen den Elektroden 1, 2, 3 und dem Schrott bzw. dem flüssigen Metall 6 bilden sich Lichtbögen 9 aus. Die Lichtbögen werden von Schaumschlacke 4 eingehüllt, um die Wände des Lichtbogenofens 5 vor der Energieabstrahlung der Lichtbögen 9 zu schützen. Zum Aufbau eines gewünschten Pegels von Schaum- schlacke 4 ist eine Einrichtung zur Steuerung der Schaumschlacke vorgesehen. Diese weist in beispielhafter Ausgestaltung eine Blaskokille 10 sowie eine Recheneinrichtung 11 auf. Mittels der Blaskokille 10 wird Kohlenstoff, insbesondere mit Luft gemischter Kohlenstoff, in den Lichtbogenofen 5, insbesondere in die Schlacke oberhalb des flüssige Metalls 6, geblasen. In der Schlacke wandelt sich der Kohlenstoff in Kohlenstoffdioxid oder Kohlenstoffmonoxid um, so daß Schaumschlacke 4 entsteht. Des Menge des einzublasenden Kohlen- stoffs wird durch die Recheneinrichtung 11 in Abhängigkeit der dem Lichtbogenofen 5 zugeführten elektrischen Energie sowie in Abhängigkeit der Menge der Beschickungsmaterialien in den Lichtenbogenofen 5 ermittelt. Beschickungsmaterialien sind im wesentlichen Schrott, Legierungsmittel und Zusatz- stoffe. Ferner kann es vorgesehen werden, den Lichtbogenofen 5 auch mit Stahl zu beschicken. Ein wichtiger Zusatzstoff ist z.B. Kalk, der einen wichtigen Bestandteil der Schaumschlacke 4 bildet.1 shows an electric arc furnace 5, which in the exemplary embodiment is designed as a three-phase electric arc furnace, with a device for controlling the formation of foam slag 4 in the electric arc furnace 5. In the electric arc furnace 5, three electrodes 1, 2, 3 are connected, which are connected via an adjustable transformer a three-phase power supply network 8 are connected, scrap melted so that liquid metal 6 accumulates in the lower part of the arc furnace 5. Arcs 9 form between the electrodes 1, 2, 3 and the scrap or the liquid metal 6. The arcs are enveloped by foam slag 4 in order to protect the walls of the arc furnace 5 from the energy radiation from the arcs 9. To build up a desired level of foam slag 4, a device for controlling the foam slag is provided. In an exemplary embodiment, this has a blow mold 10 and a computing device 11. The blow mold 10 blows carbon, in particular carbon mixed with air, into the arc furnace 5, in particular into the slag above the liquid metal 6. The carbon in the slag converts to carbon dioxide or carbon monoxide, so that foam slag 4 is formed. The amount of carbon to be injected is determined by the computing device 11 as a function of the electrical energy supplied to the arc furnace 5 and as a function of the quantity of charging materials in the arc furnace 5. Feed materials are essentially scrap, alloying agents and additives. Furthermore, provision can also be made for charging the arc furnace 5 with steel. An important additive is lime, for example, which forms an important component of the foam slag 4.
Die Zufuhr elektrischer Energie aus dem Energieversorgungsnetz 8 wird in beispielhafter Ausgestaltung mittels des einstellbaren Transformators 7 und/oder durch Verstellung der Höhe der Elektroden 1, 2, 3 geregelt. Einzelheiten einer vorteilhaften Regelung der Energiezufuhr im Zusammenhang mit der Erfindung können der DE 197 11 453, der EP 0 036 122 und der DE 44 15 727 entnommen werden. Die Energiezufuhr, insbesondere die Höhe der Elektroden 1, 2 und 3, wird in .Abhängigkeit der Höhe des Pegels der Schaumschlacke 4 im Lichtbogenofen 5 eingestellt. Dazu ermittelt die Recheneinrichtung 11 in be- sonders vorteilhafter Weise mittels des auf ihr implementierten Schaumschlackenmodells neben dem Sollwert für die Zufuhr von Kohlenstoff die aktuelle Höhe des Pegels der Schaumschlacke 4 im Lichtbogenofen 5. Die Regelung des Transformators 7 sowie die Regelung der Höhe der Elektroden 1, 2, 3 können m beispielhafter Ausgestaltung auch auf der Rechen- emπchtung 11 implementiert werden.In an exemplary embodiment, the supply of electrical energy from the energy supply network 8 is regulated by means of the adjustable transformer 7 and / or by adjusting the height of the electrodes 1, 2, 3. Details of an advantageous regulation of the energy supply in connection with the invention can be found in DE 197 11 453, EP 0 036 122 and DE 44 15 727. The energy supply, in particular the height of the electrodes 1, 2 and 3, is set as a function of the level of the foam slag 4 in the electric arc furnace 5. For this purpose, the computing device 11 determines in a particularly advantageous manner by means of the foam slag model implemented on it, in addition to the target value for the supply of carbon, the current level of the level of the foam slag 4 in the electric arc furnace 5. The regulation of the transformer 7 and the regulation of the height of the electrodes 1 , 2, 3 can also be implemented on the computing device 11 in an exemplary embodiment.
FIG 1 zeigt m beispielhafter Ausgestaltung einen als Dreh- stromlichtbogenofen ausgebildeten Lichtbogenofen 5. Die Erfindung ist jedoch auch besonders vorteilhaft für einen Gleichstromlichtbogenofen einzusetzen. In bezug auf einen Gleichstromlichtbogenofen ist das erfmdungsgemaße Verfahren den Verfahren gemäß DE 44 25 089 Cl und der EP 0 637 834 be- sonders überlegen, da die signifikanten Frequenzen m der1 shows, in an exemplary embodiment, an arc furnace 5 designed as a three-phase arc furnace. However, the invention can also be used particularly advantageously for a direct current arc furnace. With regard to a direct current arc furnace, the method according to the invention is particularly superior to the method according to DE 44 25 089 Cl and EP 0 637 834, since the significant frequencies m der
Schallemission bzw. m den elektrischen Großen nicht oder nur schwach vorhanden sind.Noise emission or m the electrical sizes are not or only weakly present.
FIG 2 zeigt das Zusammenwirken eines Schaumschlackenmodells 25 mit einem Lichtbogenofen 5. Die wesentlichen Prozesse, die im Lichtbogenofen 5 ablaufen, sind das Beschicken 22 des Lichtbogenofens 5, der Schmelzprozeß 23 im Lichtbogenofen 5 sowie der Abstich 24 des Lichtbogenofens 5, bei dem das flussige Metall im Lichtbogenofen 5 abgestochen wird. Beim Be- schicken 22 des Lichtbogenofens 5 wird der Lichtbogenofen 5 mit einer bestimmten Menge von Beschickungsmaterialien 27 wie Schrott, Stahl, Legierungsmittel und/oder Zusatzstoffe beschickt. Wahrend des Schmelzprozesses 23 wird dem Lichtbogenofen 5 Energie 28 zugeführt. Außerdem wird Kohlenstoff 29 m den Lichtbogenofen 5 eingeblasen. Aus der Menge der Beschickungsmaterialien 27 sowie der Zufuhr von Energie 28 ermittelt ein Schaumschlackenmodell 25 Sollwerte für die Zufuhr von Kohlenstoff 29 m den Lichtbogenofen 5.2 shows the interaction of a foam slag model 25 with an electric arc furnace 5. The essential processes that take place in the electric arc furnace 5 are the charging 22 of the electric arc furnace 5, the melting process 23 in the electric arc furnace 5 and the tapping 24 of the electric arc furnace 5, in which the liquid metal is tapped in the arc furnace 5. When charging 22 the arc furnace 5, the arc furnace 5 is loaded with a certain amount of feed materials 27 such as scrap, steel, alloying agents and / or additives. Energy 28 is supplied to the arc furnace 5 during the melting process 23. Carbon 29 m is also blown into the arc furnace 5. A foam slag model 25 determines setpoints for the supply of carbon 29 m from the arc furnace 5 from the quantity of the feed materials 27 and the supply of energy 28.
In vorteilhafter Ausgestaltung kann vorgesehen werden, das Schaumschlackenmodell 25 zu optimieren, so daß es besonders präzise Sollwerte für die Zufuhr von Kohlenstoff 29 m den Lichtbogenofen 5 liefert. Dazu werden die Eigenschaften 30 von Schaumschlacke, die beim Abstich 24 im Lichtbogenofen 5 vorhanden ist, einem Bewerter 26 zugeführt. Der Bewerter 26 weist einen Lernalgorithmus auf, der neue Parameter 20 für das Schaumschlackenmodell 25 ermittelt. Die Ermittlung neuer Parameter 20 erfolgt vorzugsweise m Abhängigkeit der Eigenschaften 30 der Schaumschlacke sowie der vom Schaumschlacken- modeil 25 ermittelten Eigenschaften 19 der Schaumschlacke.In an advantageous embodiment, it can be provided that the foam slag model 25 is optimized so that it supplies the arc furnace 5 with particularly precise target values for the supply of carbon 29 m. For this purpose, the properties 30 of foam slag, which is present in the arc furnace 5 during tapping 24, are fed to an evaluator 26. The evaluator 26 has a learning algorithm that determines new parameters 20 for the foam slag model 25. New parameters 20 are preferably determined as a function of the properties 30 of the foam slag and the properties 19 of the foam slag determined by the foam slag part 25.
Die Eigenschaften 30 der Schaumschlacke werden z.B. von einem Bediener bestimmt und über eine Mensch-Maschine-Schnittstelle m den Bewerter 26 eingegeben.The properties of the foam slag are e.g. determined by an operator and entered the evaluator 26 via a human-machine interface.
FIG 3 zeigt ein Ausfuhrungsbeispiel für ein neuronales Netz, das als einfaches Ausfuhrungsbeispiel für ein Schaumschlak- kenmodell einsetzbar ist. Das neuronale Netz weist drei Eingangsknoten 31, 32, 33 auf, wobei dem neuronalen Netz über den Eingangsknoten 31 Information über die Menge des Schrotts im Lichtbogenofen, über den Eingangsknoten 32 Information über die Menge an zugefuhrter Energie und über den Eingangsknoten 33 Information über die zugefuhrte Menge von Kalk zugeführt werden. Das neuronale Netz weist eine Ebene mit verdeckten Neuronen 34, 35 und 36 sowie einen Ausgangsknoten 37 auf, über den ein Sollwert für die Kohlenstoffzufuhr ausgegeben wird. 3 shows an exemplary embodiment of a neural network which can be used as a simple exemplary embodiment of a foam slag model. The neural network has three input nodes 31, 32, 33, the neural network via the input node 31 information about the amount of scrap in the electric arc furnace, via the input node 32 information about the amount of energy supplied and via the input node 33 information about the supplied Amount of lime to be fed. The neural network has a level with hidden neurons 34, 35 and 36 and an output node 37, via which a setpoint for the carbon supply is output.

Claims

Patentansprüche claims
1. Verfahren zur Steuerung der Schaumschlackenbildung m einem Lichtbogenofen (5) , dem Kohlenstoff derart zugeführt wird, daß sowohl eine mindestens teilweise Einhüllung des1. A method for controlling the foam slag formation in an arc furnace (5), the carbon is fed in such a way that both an at least partial encapsulation of the
Lichtbogens im Lichtbogenofen (5) erfolgt als auch eine überdosierte Zufuhr von Kohlenstoff vermieden w rd, d a d u r c h g e k e n n z e i c h n e t, daß die Menge des Kohlenstoffs (29) , der dem Lichtbogenofen zugeführt wird, mittels eines Schaumschlackenmodells (25) m .Abhängigkeit der Menge zumindest eines der Beschickungsmaterialien (27) Schrott, Stahl, Legierungsmittel oder Zusatzstoffe ermittelt wird.Arc in the arc furnace (5) and an overdosed supply of carbon are avoided, characterized in that the amount of carbon (29) which is fed to the arc furnace is by means of a foam slag model (25) with a dependence on the amount of at least one of the feed materials (27) scrap, steel, alloying agents or additives are determined.
2. Verfahren nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, daß die Menge des Kohlenstoffs (29) , der dem Lichtbogenofen zugeführt wird, mittels des Schaumschlackenmodells (25) m Abhängigkeit der Menge der Beschickungsmaterialien (27) Schrott, Stahl, Legierungsmittel und Zusatzstoffe ermittelt wird.2. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that the amount of carbon (29) which is fed to the arc furnace is determined by means of the foam slag model (25) depending on the amount of feed materials (27) scrap, steel, alloying agents and additives.
3. Verfahren nach Anspruch 1 oder 2, d a d u r c h g e k e n n z e i c h n e t, daß die Menge des Kohlenstoffs (29) , der dem Lichtbogenofen zugeführt wird, mittels des Schaumschlackenmodells (25) m Abhängigkeit der Energiezufuhr (28) m den Lichtbogenofen (5) ermittelt wird.3. The method of claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the amount of carbon (29) which is fed to the arc furnace, by means of the foam slag model (25) m depending on the energy supply (28) m the arc furnace (5) is determined.
4. Verfahren nach Anspruch 1, 2 oder 3, d a d u r c h g e k e n n z e i c h n e t, daß die Menge des Kohlenstoffs (29) , der dem Lichtbogenofen zugeführt wird, mittels eines neuronalen Netzes, das das Schaumschlackenmodell (25) aufweist, ermittelt wird. 4. The method according to claim 1, 2 or 3, characterized in that the amount of carbon (29) which is fed to the electric arc furnace is determined by means of a neural network which has the foam slag model (25).
5. Verfahren nach Anspruch 4, d a d u r c h g e k e n n z e i c h n e t, daß das neuronale Netz mit einer Analyse der Eigenschaften der Schaumschlacke beim Abstich des Lichtbogenofens (5) trai- niert wird.5. The method as claimed in claim 4, so that the neural network is trained with an analysis of the properties of the foam slag when tapping the arc furnace (5).
6. Verfahren nach einem der vorhergehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, daß mittels des Schaumschlackenmodells (25) die chemischen und/oder physikalischen Eigenschaften (19) der Schaumschlacke (4) im Lichtbogenofen (5) ermittelt werden.6. The method according to any one of the preceding claims, that the chemical and / or physical properties (19) of the foam slag (4) in the arc furnace (5) are determined by means of the foam slag model (25).
7. Verfahren nach Anspruch 6, d a d u r c h g e k e n n z e i c h n e t, daß mittels des Schaumschlackenmodells (25) die Höhe der Schaumschlacke (4) im Lichtbogenofen (5) ermittelt wird.7. The method according to claim 6, d a d u r c h g e k e n n z e i c h n e t that the height of the foam slag (4) in the electric arc furnace (5) is determined by means of the foam slag model (25).
8. Einrichtung zur Steuerung der Schaumschlackenbildung in einem Lichtbogenofen (5) zur Durchführung des Verfahrens nach einem der vorhergehenden Ansprüche, wobei die Einrichtung zur Steuerung der Schaumschlackenbildung in dem Lichtbogenofen (5) eine Kohlenstoffzuführeinrichtung (10) aufweist, mittels der dem Lichtbogenofen (5) Kohlenstoff derart zugeführt wird, daß sowohl eine mindestens teilweise Einhüllung des Lichtbo- gens im Lichtbogenofen (5) erreicht als auch eine überdosierte Zufuhr von Kohlenstoff vermieden wird, d a d u r c h g e k e n n z e i c h n e t, daß Einrichtung zur Steuerung der Schaumschlackenbildung eine Recheneinrichtung (11) zur Steuerung der Kohlenstoffzuführ- einrichtung (10) aufweist, wobei die Recheneinrichtung (11) ein Schaumschlackenmodell (25) zur Ermittlung der Menge des Kohlenstoffs (29) , der dem Lichtbogenofen zugeführt wird, in Abhängigkeit der Menge zumindest eines der Beschickungsmaterialien (27), Schrott, Stahl, Legierungsmittel oder Zusatz- stoffe, aufweist. 8. Device for controlling the foam slag formation in an arc furnace (5) for carrying out the method according to one of the preceding claims, wherein the device for controlling the foam slag formation in the arc furnace (5) has a carbon feed device (10) by means of which the arc furnace (5) Carbon is fed in such a way that both an at least partial encapsulation of the arc in the arc furnace (5) is achieved and an overdosed supply of carbon is avoided, characterized in that the device for controlling the formation of foam slag comprises a computing device (11) for controlling the carbon supply device (10), the computing device (11) having a foam slag model (25) for determining the amount of carbon (29) that is fed to the electric arc furnace as a function of the amount of at least one of the feed materials (27), scrap, steel, alloying agent or Additives, proof t.
9. Einrichtung nach .Anspruch 8, d a d u r c h g e k e n n z e i c h n e t, daß das Schaumschlackenmodell (25) ein neuronales Netz aufweist . 9. Device according to claim 8, so that the foam slag model (25) has a neural network.
EP98958815A 1997-10-31 1998-10-19 Method and device for controlling the formation of foamed slag in an arc furnace Ceased EP1027462A1 (en)

Applications Claiming Priority (3)

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DE1997148310 DE19748310C1 (en) 1997-10-31 1997-10-31 Controlling formation of foam slag in an electric arc furnace
DE19748310 1997-10-31
PCT/DE1998/003062 WO1999023264A1 (en) 1997-10-31 1998-10-19 Method and device for controlling the formation of foamed slag in an arc furnace

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