EP0230255A2 - Induction coil for crucible induction furnaces - Google Patents

Induction coil for crucible induction furnaces Download PDF

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Publication number
EP0230255A2
EP0230255A2 EP87100362A EP87100362A EP0230255A2 EP 0230255 A2 EP0230255 A2 EP 0230255A2 EP 87100362 A EP87100362 A EP 87100362A EP 87100362 A EP87100362 A EP 87100362A EP 0230255 A2 EP0230255 A2 EP 0230255A2
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EP
European Patent Office
Prior art keywords
coil
induction
crucible
cooling
coil sections
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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.)
Withdrawn
Application number
EP87100362A
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German (de)
French (fr)
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EP0230255A3 (en
Inventor
Dieter Dipl.-Ing. Schluckebier
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Otto Junker GmbH
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Otto Junker GmbH
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Publication date
Application filed by Otto Junker GmbH filed Critical Otto Junker GmbH
Publication of EP0230255A2 publication Critical patent/EP0230255A2/en
Publication of EP0230255A3 publication Critical patent/EP0230255A3/en
Withdrawn legal-status Critical Current

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    • 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
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/22—Furnaces without an endless core
    • H05B6/24—Crucible furnaces
    • 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
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/42—Cooling of coils

Definitions

  • the invention relates to an induction coil for induction crucible furnaces consisting of a plurality of coil sections which can be acted upon independently of one another and arranged coaxially one above the other.
  • Crucible furnaces with several coil sections are known for example from DE-AS 1 037 613.
  • the coil sections made of copper or aluminum profile can be loaded independently of one another, so that the thermal energy can only be supplied to the feed material limited to certain crucible zones.
  • both the loaded and each non-switched-on coil section are cooled by water which is passed through a cooling channel located in the coil profile. In this way, the outer wall of the crucible is cooled approximately uniformly over the entire coil height.
  • the object of the invention is therefore to increase the power consumption in the induction crucible furnaces mentioned at the outset lower and thus improve the overall efficiency of the ovens.
  • an induction coil of the type mentioned in the introduction in that the coil sections are arranged at a distance from one another and are surrounded on the outside by magnetic yokes and in that there is at least one cooling coil made of non-magnetic steel in the intermediate space or in the intermediate spaces between the coil sections.
  • cooling coil is to be understood as a coil section that cannot be connected to the power supply system, the windings of which consist of a hollow profile made of non-magnetic steel connected to a cooling water network. It is generally known to arrange such cooling coils above and below the induction coil in order to be able to cool the upper and lower crucible side wall parts which are not covered by the induction coil and thus to prevent thermal stress cracks in the crucible lining.
  • the induction coil according to the invention can also be designed so that each cooling coil consists of several turns and has a height of 100 to 250 mm.
  • the induction coil according to the invention can improve the overall efficiency by up to 8% if the sub-coils are operated at the mains frequency. With a medium frequency connection, an even higher improvement in the overall efficiency is achieved.
  • the furnace crucible made of ceramic ramming mass is designated 1. This is surrounded in its lower part by the lower coil section 2 and in its upper part by the upper coil section 3. Both coil sections 2 and 3 can be connected independently of one another to a suitable power network. Both coil sections 2, 3 are connected to a cooling water network via connections not shown in the drawing.
  • the lower coil section 2 and the upper coil section 3 are spaced apart. In the resulting space there is a cooling coil 4 with several cooling windings made of non-magnetic hollow steel profile.
  • the cooling coil 4 can also be connected to a cooling water network. However, it is not connected to a power grid.
  • the coil sections 2, 3 and the cooling coil 4 are surrounded on the outside by perpendicularly arranged magnetic yokes 5 for returning the electric field of the induction coil consisting of the coil sections 2, 3.
  • the crucible 1 is surrounded by three coil sections 6, 7, 8 which can be acted upon independently of one another and two cooling coils 9, 10.
  • Yokes 5 are also present in this exemplary embodiment.
  • the distance between the coil sections 2, 3, 6, 7, 8 which can be acted upon independently of one another or the height of the cooling coils 4, 9, 10 is 100 to 250 mm, depending on the choice of frequency and other factors. This means that copper and aluminum can be loaded independently of one another placed coil sections outside the main electrical field of the adjacent coil sections. Since the cooling coils 4, 9, 10 consist of non-magnetic steel, no or hardly any thermal energy is induced in them from the electrical field of the coil sections.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Furnace Details (AREA)

Abstract

An induction coil for crucible induction furnaces constructed from a plurality of coil sections (2,3,6,7,8) to which power can be applied separately from one another, and which are arranged coaxially at a distance above one another. In the intermediate space between in each case two coil sections (2,3,6,7,8) there is located in each case at least one cooling coil (4,9,10) of non-magnetic steel. The height of the cooling coil (4,9,10) or the cooling coils is between 100 and 250 mm. <IMAGE>

Description

Die Erfindung betrifft eine aus mehreren unabhängig voneinan­der beaufschlagbaren, koaxial übereinander angeordneten Spu­lenabschnitten bestehende Induktionsspule für Induktionstie­gelöfen.The invention relates to an induction coil for induction crucible furnaces consisting of a plurality of coil sections which can be acted upon independently of one another and arranged coaxially one above the other.

Tiegelöfen mit mehreren Spulenabschnitten sind beispielsweise aus der DE-AS 1 037 613 bekannt. Die aus Kupfer- oder Alumi­nium-Profil bestehenden Spulenabschnitte können unabhängig voneinander beaufschlagt werden, wodurch die Wärmeenergie nur auf bestimmte Tiegelzonen begrenzt dem Einsatzgut zugeführt werden kann. Während des Betriebes des Ofens sind sowohl je­der beaufschlagte als auch jeder nicht eingeschaltete Spulen­abschnitt mittels Wasser gekühlt, das durch einen im Spulen­profil befindlichen Kühlkanal hindurchgeleitet wird. Auf die­se Weise wird die Tiegelaußenwand über die gesamte Spulenhöhe in etwa gleichmäßig gekühlt.Crucible furnaces with several coil sections are known for example from DE-AS 1 037 613. The coil sections made of copper or aluminum profile can be loaded independently of one another, so that the thermal energy can only be supplied to the feed material limited to certain crucible zones. During operation of the furnace, both the loaded and each non-switched-on coil section are cooled by water which is passed through a cooling channel located in the coil profile. In this way, the outer wall of the crucible is cooled approximately uniformly over the entire coil height.

So ist es z.B. möglich, beim Anfahren des Induktionstiegel­ofens lediglich den unteren Spulenabschnitt bzw. die unteren Spulenabschnitte einzuschalten. Entsprechend dem Ansteigen des Schmelzbadspiegels kann sodann der nächst höhere Spulen­abschnitt eingeschaltet werden, so daß die Energie jeweils in Nähe des Badspiegels in die Schmelze induziert wird. Dadurch erhält man jeweils an der Badoberfläche eine intensive Badbe­wegung, die besonders beim Einschmelzen von kleinstückigem Material und für das Aufkohlen von Schmelzen erwünscht ist. Darüberhinaus ist eine optimale Leistungsausnutzung des Ofens gewährleistet.So it is e.g. possible to switch on only the lower coil section or the lower coil sections when starting the induction crucible furnace. The next higher coil section can then be switched on in accordance with the increase in the molten pool level, so that the energy is induced into the melt in the vicinity of the pool level. This results in an intensive bath movement on the surface of the bath, which is particularly desirable when melting small pieces of material and for carburizing melts. In addition, optimal performance of the furnace is guaranteed.

Andererseits ist es bei einem Induktionsofen mit mehreren ge­trennt beaufschlagbaren Spulenabschnitten möglich, die Bad­oberfläche relativ ruhig zu halten, während im unteren Schmelzbadbereich eine intensive Badbewegung erzeugt wird. In einem solchen Falle wird der obere Spulenabschnitt bzw. wer­den die oberen Spulenabschnitte nicht beaufschlagt.On the other hand, in the case of an induction furnace with a plurality of coil sections which can be acted upon separately, it is possible to keep the bath surface relatively calm, while an intensive bath movement is generated in the lower melt pool region. In such a case, the upper coil section or the upper coil sections are not acted upon.

Diese an sich vorteilhafte Betriebsweise von Induktonstiegel­öfen mit getrennt voneinander beaufschlagbaren Spulenab­schnitten hat jedoch den Nachteil eines relativ hohen Strom­verbrauches sowohl bei Netzfrequenz- als auch bei Mittelfre­quenz-Anschluß der Spulenabschnitte.However, this advantageous mode of operation of inductor crucible furnaces with separately operable coil sections has the disadvantage of a relatively high power consumption when the coil sections are connected to both the mains frequency and the medium frequency.

Der Grund dafür besteht bei den bisher praktisch ohne Zwi­schenraum koaxial übereinander angeordneten Spulenabschnitten darin, daß der jeweils ausgeschaltete Spulenabschnitt teil­weise im elektrischen Hauptfeld des benachbarten beaufschlag­ten Spulenabschnittes liegt und somit aufgeheizt wird, wenn nicht die induzierte Wärmeenergie durch das Kühlwasser abge­führt wird.The reason for this in the case of the coil sections which have been arranged coaxially one above the other to date with practically no space is that the coil section which is in each case switched off lies partially in the main electrical field of the adjacent charged coil section and is therefore heated unless the induced thermal energy is dissipated by the cooling water.

Die Erfindung hat sich daher die Aufgabe gestellt, den Strom­verbrauch bei den eingangs genannten Induktionstiegelöfen zu senken und damit den Gesamtwirkungsgrad der Öfen zu verbes­sern.The object of the invention is therefore to increase the power consumption in the induction crucible furnaces mentioned at the outset lower and thus improve the overall efficiency of the ovens.

Das wird erfindungsgemäß mit einer Induktionsspule der ein­gangs erwähnten Art dadurch gelöst, daß die Spulenabschnitte mit Abstand voneinander angeordnet sind und außen von Magnet­jochen umgeben sind und daß sich in dem Zwischenraum bzw. in den Zwischenräumen zwischen den Spulenabschnitten jeweils we­nigstens eine Kühlspule aus unmagnetischem Stahl befindet.This is achieved according to the invention with an induction coil of the type mentioned in the introduction in that the coil sections are arranged at a distance from one another and are surrounded on the outside by magnetic yokes and in that there is at least one cooling coil made of non-magnetic steel in the intermediate space or in the intermediate spaces between the coil sections.

Unter dem Begriff "Kühlspule" ist ein nicht an das Stromnetz anschließbarer Spulenabschnitt zu verstehen, dessen Windungen aus einem an ein Kühlwassernetz angeschlossenen Hohlprofil aus unmagnetischem Stahl bestehen. Es ist allgemein bekannt, solche Kühlspulen oberhalb und unterhalb der Induktionsspule anzuordnen, um die nicht von der Induktionsspule bedeckten oberen und unteren Tiegelseitenwandteile ausreichend kühlen zu können und damit Wärmespannungsrissen in der Tiegelaus­kleidung vorzubeugen.The term “cooling coil” is to be understood as a coil section that cannot be connected to the power supply system, the windings of which consist of a hollow profile made of non-magnetic steel connected to a cooling water network. It is generally known to arrange such cooling coils above and below the induction coil in order to be able to cool the upper and lower crucible side wall parts which are not covered by the induction coil and thus to prevent thermal stress cracks in the crucible lining.

Die erfindungsgemäße Induktionsspule kann ferner so ausgebil­det sein, daß daß jede Kühlspule aus mehreren Windungen be­steht und eine Höhe von 100 bis 250 mm hat.The induction coil according to the invention can also be designed so that each cooling coil consists of several turns and has a height of 100 to 250 mm.

Durch die erfindungsgemäße Induktionsspule kann eine Verbes­serung des Gesamtwirkungsgrades bis zu 8% erreicht werden, wenn die Teilspulen mit Netzfrequenz betrieben werden. Bei Mittelfrequenzanschluß wird eine noch höhere Verbesserung des Gesamtwirkungsgrades erreicht.The induction coil according to the invention can improve the overall efficiency by up to 8% if the sub-coils are operated at the mains frequency. With a medium frequency connection, an even higher improvement in the overall efficiency is achieved.

An Hand von Ausführungsbeispielen wird die Neuerung näher er­läutert. Es zeigt:

  • Fig.1 einen vertikalen Schnitt durch einen Induktionstiegel­ofen mit zwei unabhängig voneinander beaufschlagbaren Spulenabschnitten und
  • Fig.2 einen solchen Ofen mit drei unabhängig voneinader be­aufschlagbaren Spulenabschnitten.
The innovation is explained in more detail using exemplary embodiments. It shows:
  • 1 shows a vertical section through an induction crucible furnace with two independently acting coil sections and
  • 2 shows such an oven with three coil sections which can be acted upon independently of one another.

In Fig. 1 ist der Ofentiegel aus keramischer Stampfmasse mit 1 bezeichnet. Dieser wird in seinem unteren Teil von dem un­teren Spulenabschnitt 2 und in seinem oberen Teil von dem oberen Spulenabschnitt 3 umgeben. Beide Spulenabschnitte 2 und 3 können unabhängig voneinander an ein geeignetes Strom­netz angeschlossen werden. Über in der Zeichnung nicht darge­stellte Anschlüsse sind beide Spulenabschnitte 2,3 mit einem Kühlwassernetz verbunden.In Fig. 1, the furnace crucible made of ceramic ramming mass is designated 1. This is surrounded in its lower part by the lower coil section 2 and in its upper part by the upper coil section 3. Both coil sections 2 and 3 can be connected independently of one another to a suitable power network. Both coil sections 2, 3 are connected to a cooling water network via connections not shown in the drawing.

Der untere Spulenabschnitt 2 und der obere Spulenabschnitt 3 sind im Abstand voneinander angeordnet. In dem dadurch ent­stehenden Zwischenraum befindet sich eine Kühlspule 4 mit mehreren Kühlwindungen aus unmagnetischem Stahlhohlprofil. Die Kühlspule 4 ist ebenfalls an ein Kühlwassernetz an­schließbar. Sie wird jedoch nicht an ein Stromnetz ange­schlossen.The lower coil section 2 and the upper coil section 3 are spaced apart. In the resulting space there is a cooling coil 4 with several cooling windings made of non-magnetic hollow steel profile. The cooling coil 4 can also be connected to a cooling water network. However, it is not connected to a power grid.

Die Spulenabschnitte 2,3 sowie die Kühlspule 4 sind außen von senkrecht angeordneten magnetischen Jochen 5 zur Rückführung des elektrischen Feldes der aus den Spulenabschnitten 2,3 be­stehenden Induktionsspule umgeben.The coil sections 2, 3 and the cooling coil 4 are surrounded on the outside by perpendicularly arranged magnetic yokes 5 for returning the electric field of the induction coil consisting of the coil sections 2, 3.

Bei dem in Fig. 2 dargestellten Induktionstiegelofen umgeben den Tiegel 1 drei unabhängig voneinander beaufschlagbare Spu­lenabschnitte 6,7,8 sowie zwei Kühlspulen 9,10. Auch bei die­sem Ausführungsbeispiel sind Joche 5 vorhanden.In the induction crucible furnace shown in FIG. 2, the crucible 1 is surrounded by three coil sections 6, 7, 8 which can be acted upon independently of one another and two cooling coils 9, 10. Yokes 5 are also present in this exemplary embodiment.

Der Abstand zwischen den unabhängig voneinander beaufschlag­baren Spulenabschnitten 2,3,6,7,8 bzw. die Höhe der Kühlspu­len 4,9,10 beträgt je nach Wahl der Frequenz sowie anderer Faktoren 100 bis 250 mm. Damit liegen die unabhängig vonein­ander beaufschlagbaren und aus Kupfer oder Aluminium herge­ stellten Spulenabschnitte außerhalb des elektrischen Haupt­feldes der jeweils benachbarten Spulenabschnitte. Da die Kühlspulen 4,9,10 aus unmagnetischem Stahl bestehen, wird in diesen keine bzw. kaum Wärmeenergie aus dem elektrischen Feld der Spulenabschnitte induziert.The distance between the coil sections 2, 3, 6, 7, 8 which can be acted upon independently of one another or the height of the cooling coils 4, 9, 10 is 100 to 250 mm, depending on the choice of frequency and other factors. This means that copper and aluminum can be loaded independently of one another placed coil sections outside the main electrical field of the adjacent coil sections. Since the cooling coils 4, 9, 10 consist of non-magnetic steel, no or hardly any thermal energy is induced in them from the electrical field of the coil sections.

Claims (2)

1. Aus mehreren unabhängig voneinander beaufschlagba­ren, koaxial übereinader angeordneten Spulenabschnitten be­stehende Induktionsspule für Induktionstiegelöfen, da­durch gekennzeichnet, daß die Spulenab­schnitte (2,3,6,7,8) mit Abstand voneinander angeordnet sind und außen von Magnetjochen (5) umgeben sind und daß sich in dem Zwischenraum bzw. in den Zwischenräumen zwischen den Spu­lenabschnitten jeweils wenigstens eine Kühlspule (4,9,10) aus unmagnetischem Stahl befindet.1. consisting of a plurality of independently actable, coaxially arranged coil sections arranged induction coil for induction crucible furnaces, characterized in that the coil sections (2,3,6,7,8) are spaced from each other and are externally surrounded by magnetic yokes (5) and that there is at least one cooling coil (4, 9, 10) made of non-magnetic steel in the intermediate space or in the intermediate spaces between the coil sections. 2. Vorrichtung nach Anspruch 1, dadurch gekennzeich­net, daß jede Kühlspule (4,9,10) aus mehreren Windungen be­steht und eine Höhe von 100 bis 250 mm hat.2. Device according to claim 1, characterized in that each cooling coil (4,9,10) consists of several turns and has a height of 100 to 250 mm.
EP87100362A 1986-01-16 1987-01-14 Induction coil for crucible induction furnaces Withdrawn EP0230255A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19868600893 DE8600893U1 (en) 1986-01-16 1986-01-16 Induction coil for induction crucible furnaces
DE8600893U 1986-01-16

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EP0230255A2 true EP0230255A2 (en) 1987-07-29
EP0230255A3 EP0230255A3 (en) 1988-03-09

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0465406A2 (en) * 1990-07-06 1992-01-08 Sulzer Chemtech AG Process for the continous melting of solid or viscous products

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR817998A (en) * 1936-02-17 1937-09-15 Union Aciers Fins High and low frequency induction furnace
FR894271A (en) * 1942-05-02 1944-12-19 Ind Termo Elettro Meccanica G Electric induction furnace operating with three-phase current at industrial frequency for melting metals and light alloys
DE1037613B (en) * 1952-05-20 1958-08-28 Otto Junker Fa Process for melting down loose, small pieces of metal

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR817998A (en) * 1936-02-17 1937-09-15 Union Aciers Fins High and low frequency induction furnace
FR894271A (en) * 1942-05-02 1944-12-19 Ind Termo Elettro Meccanica G Electric induction furnace operating with three-phase current at industrial frequency for melting metals and light alloys
DE1037613B (en) * 1952-05-20 1958-08-28 Otto Junker Fa Process for melting down loose, small pieces of metal

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0465406A2 (en) * 1990-07-06 1992-01-08 Sulzer Chemtech AG Process for the continous melting of solid or viscous products
CH680198A5 (en) * 1990-07-06 1992-07-15 Sulzer Ag
EP0465406A3 (en) * 1990-07-06 1992-09-02 Gebrueder Sulzer Aktiengesellschaft Process for the continous melting of solid or viscous products

Also Published As

Publication number Publication date
EP0230255A3 (en) 1988-03-09
DE8600893U1 (en) 1986-03-06

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