EP2255139A1 - Electrically heated shaft furnace - Google Patents

Electrically heated shaft furnace

Info

Publication number
EP2255139A1
EP2255139A1 EP08847704A EP08847704A EP2255139A1 EP 2255139 A1 EP2255139 A1 EP 2255139A1 EP 08847704 A EP08847704 A EP 08847704A EP 08847704 A EP08847704 A EP 08847704A EP 2255139 A1 EP2255139 A1 EP 2255139A1
Authority
EP
European Patent Office
Prior art keywords
shaft furnace
furnace according
graphite
heating
rods
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.)
Granted
Application number
EP08847704A
Other languages
German (de)
French (fr)
Other versions
EP2255139B1 (en
Inventor
Alfred Edlinger
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.)
SGL Carbon SE
Original Assignee
Patco Engineering GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AT18032007A external-priority patent/AT506021B1/en
Application filed by Patco Engineering GmbH filed Critical Patco Engineering GmbH
Priority to PL08847704T priority Critical patent/PL2255139T3/en
Publication of EP2255139A1 publication Critical patent/EP2255139A1/en
Application granted granted Critical
Publication of EP2255139B1 publication Critical patent/EP2255139B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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
    • F27B1/00—Shaft or like vertical or substantially vertical furnaces
    • F27B1/08—Shaft or like vertical or substantially vertical furnaces heated otherwise than by solid fuel mixed with charge
    • 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
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/06—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated
    • F27B9/062—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated electrically heated
    • F27B9/063—Resistor heating, e.g. with resistors also emitting IR rays
    • 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
    • F27D11/00—Arrangement of elements for electric heating in or on furnaces
    • F27D11/02—Ohmic resistance heating
    • 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
    • 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
    • H05B3/00—Ohmic-resistance heating
    • H05B3/62—Heating elements specially adapted for 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
    • H05B6/22—Furnaces without an endless core

Definitions

  • the invention relates to an electrically heated shaft furnace with at least one heating element formed by electrical conductors.
  • WO 2006/079132 A1 proposed a method and a device for reducing metal oxide-containing slags or glasses and / or degassing mineral melts, in which the molten slags were fed onto an inductively heated coke bed.
  • the batch was fed to a shaft furnace and the coke bed was inductively heated to temperatures which ensured that a melt would be formed until the tapping point or that the melting temperature would be maintained.
  • inductively heated coke a bed with high reduction potential was provided, so that the reduction of oxidic or organics contaminated slags and metallurgical dusts could be carried out even with high levels of chromium oxide and vanadium oxide slag in a simple manner.
  • Induction heated ovens are also known as crucible furnaces.
  • electrically heated furnaces the electrical resistance of the melt was mostly utilized and the electrical energy was applied via electrodes immersed in the melt.
  • the transfer of heat by induction only with high efficiency succeeds when only small distances must be bridged between the induction coil and the inductively heated medium.
  • melts this means that corresponding heat is also radiated into the induction coils, so that in the case of copper windings water-cooled copper pipes have been proposed as a conductor.
  • water-cooled conductors have a significant power loss.
  • the invention now aims to provide an embodiment for the electric heating of a shaft furnace, in which high power energy can be introduced with low power loss or alternatively other forms of electrical heating can be realized and with the provided in the prior art complex water cooling can be avoided.
  • the invention electrically heated shaft furnace of the type mentioned initially consists essentially in that the heating elements of carbon, in particular graphite exist.
  • the choice of carbon or graphite for the conductor and thus the heating element has the consequence that here a highly refractory material is used, which requires no expensive cooling more.
  • the conductivity of carbon or of graphite increases with increasing temperature, so that a corresponding stepwise heating seems advantageous, for which at the beginning, for example, the conductor can be switched in the manner of a resistance heater.
  • the heating elements as embedded in or on a refractory support or arranged conductor tracks made of graphite and preferably be formed by Graphitringen or ring segments or alternatively by coal, coke or graphite rods.
  • Graphite usually has less than half the conductivity of copper, whereby correspondingly large graphite inducers or graphite conductor cross sections must be provided. In a particularly simple manner, this can be ensured that the formation is made such that the jacket of the shaft furnace made of refractory material and grooves on its inner surface, in particular helical grooves for receiving conductor tracks formed of graphite having.
  • the conductor layer or the graphite rings can in this case be incorporated directly into the refractory jacket of the shaft furnace, with graphite itself being an excellent refractory material and remaining dimensionally stable even at very high temperatures.
  • the induction losses in the case of inductive heating increase quadratically with the distance between the inductor and the material to be coupled, for example a coke bed, the induction losses can be substantially minimized by the conductor being embedded directly in the refractory material, with only a corresponding electric current Isolation between a coke bed and the inductor is required, but for which particularly simple measures are sufficient.
  • the training is in this case made such that the inner shell is lined with a refractory insulating layer or foil or insulation mat, wherein preferably the refractory material and / or the insulating layer of MgO or Al 2 O 3 is formed.
  • the coke bed can be treated simultaneously with a correspondingly large grain size such that the depth of the grooves in the jacket is greater than the width of the strip conductors or of the graphite rings is and the radial distance of the conductor tracks from the axis or the inner diameter of the graphite rings is greater than the inner diameter of the shell of the shaft furnace is selected.
  • the electrical connection to the conductor tracks succeeds such that the graphite rings are slotted on their circumference and the free ends of the rings can be applied in parallel or in series to a current source.
  • the training can be made with advantage so that the tracks of mashed graphite powder or a with electrically conductive substances, in particular thermally dissociating salts are doped.
  • the heating elements are formed along a helical line or annularly arranged conductor tracks made of carbon, but can be made in a particularly simple manner, the formation that the heating elements of coal, coke or graphite rods are formed.
  • the arrangement is preferably such that the heating rods are arranged substantially parallel to the axis of the tubular shaft furnace, wherein advantageously the shaft furnace is cylindrical and a plurality of heating rods are arranged on a circle extending concentrically to the axis.
  • the shaft furnace is cylindrical and a plurality of heating rods are arranged on a circle extending concentrically to the axis.
  • the corresponding electrode material can be graphitized and is characterized by extremely high, even mechanical, stability.
  • heating elements parallel to the axis of a shaft furnace allows for all abundance to realize any circuits of these heating elements, the training can be made with advantage so that the heating elements each at one end to an adjacent end of an adjacent heater in the circumferential direction of the shaft furnace are connected.
  • connection of adjacent heating rods can advantageously be switchable, wherein the heating elements can be connected to one another or can be connected separately to the power source.
  • steel or slurry (CaF 2 / Al 2 0 3 / Ca0) can be melted, wherein due to the high temperatures, the melting or the reducing melting of silicon, silicon carbide, iron silicon or phosphorus succeeds in an advantageous manner.
  • Induction melting furnaces in which refractory steel alloys are melted under vacuum or under inert gas, are a possible application example here.
  • the possible risk of explosion is eliminated because, in the case of leaks, leakage of water may result in the formation of oxyhydrogen gas, in which case hydrogen could diffuse into the molten steel.
  • the use of the refractory conductor material makes it possible to choose the temperature of the conductor substantially equal to the temperature of the material to be treated, whereby the conductivity increases significantly.
  • a further increase in the conductivity at higher temperatures succeeds, as already mentioned above, by admixing thermally dissociating metal salts, which are very good conductors at high temperatures.
  • the electrically heated shaft furnace according to the invention is suitable both as an induction furnace and as a conductively heated furnace, wherein in the case of electrically conductive batches and in particular in the case of a coke bed or a crucible with molten steel temperatures of about 2300 ° C can be readily realized.
  • Graphite remains dimensionally stable in a reducing atmosphere up to temperatures of about 3400 ° C, with pure resistance heating, the heat transfer via radiation and conduction with very high efficiency succeeds.
  • FIG. 1 is a plan view of a slotted graphite ring
  • FIG. 2 is a sectional view in the direction of arrow II - II of FIG. 1
  • FIG. 3 is a sectional view in the direction of arrow III - III of FIG. 1.
  • the sectional view FIGS. 2 and 3 each show only half the shaft furnace in section.
  • Fig. 4 shows an axial section through a modified embodiment of the shaft furnace with rod-shaped heating elements
  • Fig. 5 is a section along the line V, V of Fig. 4
  • Fig. 6 shows a modified embodiment in a representation corresponding to FIG. 5
  • 7 shows a cross section through a modified embodiment with axially parallel conductor tracks.
  • Fig. 1 denotes a slotted graphite ring, whose free ends open into end faces 2 and 3. About these end faces 2 and 3, the slotted graphite rings can be contacted electrically and are acted upon accordingly with direct current, low frequency or high frequency alternating current.
  • the free end faces 2 of the slotted rings can be seen in each case.
  • current is applied to the lowermost end face 2 over the region a and contacting the following graphite ring 1 takes place via adjacent end faces 3 in the vertical direction in turn - twisted by an angle of about 180 ° - the contacting of adjacent end faces 2 to achieve a series connection of the rings takes place.
  • About the terminals 6 and 7 can be supplied here DC or low-frequency alternating current.
  • a parallel circuit is recommended, as can be seen in the axial region b, the corresponding terminals are designated here 8 and 9 and two each in Achsrich- tion successive rings 1 are connected in parallel.
  • Such a parallel connection leads to a reduction of the required voltage in the case of inductive heating, so that the danger and rollover potential is reduced.
  • the training on the axial height of the shaft furnace 5 can be chosen flexibly and it can optionally be made in individual axial Busch a parallel circuit or a serial circuit in order to be able to take into account the respective lent temperature profiles.
  • Fig. 4 shows a cross section through a shaft furnace 10, in the refractory shell 11 rod-shaped heating elements 12 are embedded.
  • the rod-shaped heating elements 12 are formed here by graphite rods.
  • the adjacent ends of such graphite rods 12 may be selectively connected to each other via conductive connections 13 at one end and conductive connections 14 at the other end of the rods, whereby a series connection of three adjacent graphite rods 12 can be realized.
  • the ends of the total resistance and the total inductance achieved by this series connection can be used correspondingly both when used as inductive heating with the connection of alternating current, and from conductive heating with connection of direct current.
  • the circuit of the individual bars results here from the sectional view of FIG. 7, wherein a total of a cage made of graphite rods can be formed as an inductor, wherein the individual graphite rods of the cage can be connected in parallel or in series.
  • the slightly modified embodiment according to FIG. 6, the illustration of which corresponds essentially to the illustration according to FIG. 5, reveals a multilayer construction of the jacket and is preferably used at maximum temperatures in order to obtain graffiti. to cause reactions.
  • the heating elements 12 are in this case surrounded by a first jacket made of graphite, wherein this first jacket 15 can be composed of individual segments.
  • the freestanding graphite rods or graphite electrodes can, if necessary, be purged with inert gas if necessary, for which inlet openings 16 are provided.
  • the graphite shell 15 is surrounded on the outside by another shell made of refractory material, which is denoted by 17.
  • Such a design can be used, for example, for the graphitization of carbon rods, as indicated schematically by a coextruded rubber 18, which can be conveyed in the direction of the arrow 19 through the shaft furnace.
  • graphitization of coke extrudate 18 can also be achieved, as a result of which the crystallization of the carbon in the coextrudate 18 can be effected.
  • Fig. 7 schematically different application examples of the shaft furnace are shown, again a modified design of the shaft furnace is provided.
  • the shell 11 of refractory material grooves 20 are provided here, which are dovetail-shaped and the conductor tracks or graphite rods 21 included.
  • the inner surface of this graphite rod or strip is in this case at a greater radial distance from the shaft 22 of the shaft furnace than the inner wall 23 of the refractory shell, so that in the case of the use of a Koksbettes for smelting reduction directly conductive contact between the coke bed and the graphite bar is prevented.
  • Such a feed or such a use of a coke bed is indicated by the Koks publishede.
  • a melt can be produced and the shaft furnace as a crucible for melting Steel are used.
  • the melt is indicated schematically at 24 here.
  • the method can be used so that a graphite heat exchanger, indicated by the reference numeral 25, is used for the production of tertiary slag.
  • the graphite rods can be operated both as a conductor and as an inductor, the field lines extending through the axial cavity of the shaft furnace.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Furnace Details (AREA)

Abstract

The invention relates to an electrically heated shaft furnace (5) comprising at least one heating element (12) which is configured by conductors. The invention is characterized in that the one or more heating elements (12) consist of carbon.

Description

Elektrisch beheizter SchachtofenElectrically heated shaft furnace
Die Erfindung bezieht sich auf einen elektrisch beheizten Schachtofen mit wenigstens einem von elektrischen Leitern gebildeten Heizelement.The invention relates to an electrically heated shaft furnace with at least one heating element formed by electrical conductors.
In der WO 2006/079132 Al wurde ein Verfahren und eine Vorrichtung zum Reduzieren von metalloxidhaltigen Schlacken bzw. Gläsern und/oder Entgasen von mineralischen Schmelzen vorge- schlagen, bei welcher die schmelzflüssigen Schlacken auf ein induktiv beheiztes Koksbett aufgegeben wurden. Die Charge wurde hierbei einem Schachtofen zugeführt und das Koksbett induktiv auf Temperaturen aufgeheizt, welche sicherstellen, dass sich bis zum Abstichende eine Schmelze ausbildet oder die Schmelz- temperatur aufrecht erhalten wird. Durch den Einsatz von induktiv beheiztem Koks wurde ein Bett mit hohem Reduktionspotential bereitgestellt, sodass die Reduktion von oxidischen bzw. mit Organika belasteten Schlacken und metallurischen Stäuben auch mit hohen Gehalten an Chromoxid- und Vanadiumoxid- schlacken in einfacher Weise vorgenommen werden konnte. Induktiv beheizte Öfen sind auch als Tiegelöfen bekannt. Im Fall von elektrisch beheizten Öfen wurde zumeist der elektrische Widerstand der Schmelze genützt und die elektrische Energie über in die Schmelze eintauchende Elektroden aufgebracht. Für eine induktive Heizung wurden bereits Kupferspulen vorgeschlagen, wobei die Übertragung von Wärme durch Induktion nur dann mit hohem Wirkungsgrad gelingt, wenn zwischen der Induktionsspule und dem induktiv zu beheizendem Medium nur geringe Abstände überbrückt werden müssen. Im Falle von Schmelzen bedeutet dies, dass entsprechende Wärme auch in die Induktionsspulen abgestrahlt wird, sodass im Falle von Kupferwicklungen wassergekühlte Kupferrohre als Leiter vorgeschlagen wurden. Wassergekühlte Leiter weisen aber eine bedeutende Verlustleistung auf. Die Erfindung zielt nun darauf ab, eine Ausbildung für die elektrische Beheizung eines Schachtofens zu schaffen, bei welcher mit geringer Verlustleistung Hochfrequenzenergie eingebracht werden kann oder wahlweise andere Formen der elektri- sehen Beheizung realisiert werden können und mit der die beim Stand der Technik vorgesehene aufwendige Wasserkühlung vermieden werden kann.WO 2006/079132 A1 proposed a method and a device for reducing metal oxide-containing slags or glasses and / or degassing mineral melts, in which the molten slags were fed onto an inductively heated coke bed. The batch was fed to a shaft furnace and the coke bed was inductively heated to temperatures which ensured that a melt would be formed until the tapping point or that the melting temperature would be maintained. Through the use of inductively heated coke, a bed with high reduction potential was provided, so that the reduction of oxidic or organics contaminated slags and metallurgical dusts could be carried out even with high levels of chromium oxide and vanadium oxide slag in a simple manner. Induction heated ovens are also known as crucible furnaces. In the case of electrically heated furnaces, the electrical resistance of the melt was mostly utilized and the electrical energy was applied via electrodes immersed in the melt. For an inductive heating copper coils have been proposed, the transfer of heat by induction only with high efficiency succeeds when only small distances must be bridged between the induction coil and the inductively heated medium. In the case of melts, this means that corresponding heat is also radiated into the induction coils, so that in the case of copper windings water-cooled copper pipes have been proposed as a conductor. However, water-cooled conductors have a significant power loss. The invention now aims to provide an embodiment for the electric heating of a shaft furnace, in which high power energy can be introduced with low power loss or alternatively other forms of electrical heating can be realized and with the provided in the prior art complex water cooling can be avoided.
Zur Lösung dieser Aufgabe besteht der erfindungsgemäße elekt- risch beheizte Schachtofen der eingangs genannten Art im Wesentlichen darin, dass die Heizelemente aus Kohlenstoff, insbesondere Graphit, bestehen. Die Wahl von Kohlenstoff bzw. Graphit für den Leiter und damit das Heizelement hat zur Folge, dass hier ein hochfeuerfestes Material eingesetzt wird, das keine aufwendige Kühlung mehr erfordert. Die Leitfähigkeit von Kohlenstoff bzw. von Graphit steigt mit zunehmender Temperatur, sodass eine entsprechende stufenweise Erhitzung vorteilhaft erscheint, wofür zu Beginn beispielsweise auch der Leiter nach Art einer Widerstandsheizung geschaltet werden kann.To achieve this object, the invention electrically heated shaft furnace of the type mentioned initially consists essentially in that the heating elements of carbon, in particular graphite exist. The choice of carbon or graphite for the conductor and thus the heating element has the consequence that here a highly refractory material is used, which requires no expensive cooling more. The conductivity of carbon or of graphite increases with increasing temperature, so that a corresponding stepwise heating seems advantageous, for which at the beginning, for example, the conductor can be switched in the manner of a resistance heater.
In besonders vorteilhafter Weise können die Heizelemente als in oder an einem feuerfesten Träger eingebettete oder angeordnete Leiterbahnen aus Graphit bestehen und vorzugsweise von Graphitringen oder -ringsegmenten oder alternativ von Kohle-, Koks- oder Graphitstäben gebildet sein.In a particularly advantageous manner, the heating elements as embedded in or on a refractory support or arranged conductor tracks made of graphite and preferably be formed by Graphitringen or ring segments or alternatively by coal, coke or graphite rods.
Graphit hat in der Regel weniger als die Hälfte der Leitfähigkeit von Kupfer, wodurch entsprechend große Graphit-Induktoren bzw. Graphit-Leiterquerschnitte vorgesehen werden müssen. In besonders einfacher Weise kann dies dadurch sichergestellt werden, dass die Ausbildung so getroffen ist, dass der Mantel des Schachtofens aus feuerfestem Material besteht und an seiner Innenfläche Rillen, insbesondere schraubenlinienförmige Rillen für die Aufnahme von aus Graphit gebildeten Leiterbahnen aufweist. Die Leiterschicht bzw. die Graphitringe können hierbei unmittelbar in die Feuerfestummantelung des Schachtofens eingearbeitet werden, wobei Graphit selbst ein hervorragendes refaktäres Material ist und auch bei sehr hohen Tempera- turen formbeständig bleibt. Da die Induktionsverluste im Fall einer induktiven Beheizung quadratisch mit dem Abstand zwischen dem Induktor und dem anzukoppelnden Material, beispielsweise einem Koksbett, steigen, können die Induktionsverluste dadurch wesentlich minimiert werden, dass der Leiter unmittelbar in das feuerfeste Material eingebettet ist, wobei lediglich eine entsprechende elektrische Isolation zwischen einem Koksbett und dem Induktor erforderlich ist, wofür aber besonders einfache Maßnahmen ausreichen.Graphite usually has less than half the conductivity of copper, whereby correspondingly large graphite inducers or graphite conductor cross sections must be provided. In a particularly simple manner, this can be ensured that the formation is made such that the jacket of the shaft furnace made of refractory material and grooves on its inner surface, in particular helical grooves for receiving conductor tracks formed of graphite having. The conductor layer or the graphite rings can in this case be incorporated directly into the refractory jacket of the shaft furnace, with graphite itself being an excellent refractory material and remaining dimensionally stable even at very high temperatures. Since the induction losses in the case of inductive heating increase quadratically with the distance between the inductor and the material to be coupled, for example a coke bed, the induction losses can be substantially minimized by the conductor being embedded directly in the refractory material, with only a corresponding electric current Isolation between a coke bed and the inductor is required, but for which particularly simple measures are sufficient.
Mit Vorteil wird die Ausbildung hierbei so getroffen, dass der Innenmantel mit einer feuerfesten Isolationsschicht bzw. Folie oder Isolationsmatte ausgekleidet ist, wobei vorzugsweise das feuerfeste Material und/oder die Isolationsschicht aus MgO oder Al2O3 gebildet ist. Alternativ zu dieser Verwendung einer Folie kann bei entsprechend schmalen Rillen und einem entsprechenden Dimensionieren der Leiterbahnen bzw. der Graphitringe bei gleichzeitig entsprechend großer Korngröße der Koksschüttung so vorgegangen werden, dass die Tiefe der Rillen im Mantel größer als die Breite der Leiterbahnen bzw. der Graphitringe gewählt ist und der radiale Abstand der Leiterbahnen von der Achse bzw. der Innendurchmesser der Graphitringe größer als der Innendurchmesser des Mantels des Schachtofens gewählt ist.Advantageously, the training is in this case made such that the inner shell is lined with a refractory insulating layer or foil or insulation mat, wherein preferably the refractory material and / or the insulating layer of MgO or Al 2 O 3 is formed. As an alternative to this use of a film, with correspondingly narrow grooves and a corresponding dimensioning of the strip conductors or of the graphite rings, the coke bed can be treated simultaneously with a correspondingly large grain size such that the depth of the grooves in the jacket is greater than the width of the strip conductors or of the graphite rings is and the radial distance of the conductor tracks from the axis or the inner diameter of the graphite rings is greater than the inner diameter of the shell of the shaft furnace is selected.
In besonders einfacher Weise gelingt der elektrische Anschluss an die Leiterbahnen so, dass die Graphitringe an ihrem Umfang geschlitzt ausgebildet sind und die freien Enden der Ringe parallel oder in Serie an eine Stromquelle anlegbar sind. Die Ausbildung kann hierbei mit Vorteil so getroffen sein, dass die Leiterbahnen aus gestampftem Graphitpulver oder einem mit elektrisch leitenden Substanzen, insbesondere thermisch dissoziierenden Salzen dotiert ausgebildet sind.In a particularly simple manner, the electrical connection to the conductor tracks succeeds such that the graphite rings are slotted on their circumference and the free ends of the rings can be applied in parallel or in series to a current source. The training can be made with advantage so that the tracks of mashed graphite powder or a with electrically conductive substances, in particular thermally dissociating salts are doped.
Alternativ zu der beschriebenen Ausbildung, bei welcher die Heizelemente von längs einer Schraubenlinie oder kreisringförmig angeordneten Leiterbahnen aus Kohlenstoff gebildet sind, kann aber in besonders einfacher Weise die Ausbildung so getroffen sein, dass die Heizelemente von Kohle-, Koks- oder Graphitstäben gebildet sind. In diesem Falle ist die Anordnung bevorzugt so getroffen, dass die Heizstäbe im Wesentlichen parallel zur Achse des rohrförmigen Schachtofens angeordnet sind, wobei mit Vorteil der Schachtofen zylindrisch ausgebildet ist und eine Mehrzahl von Heizstäben auf einem konzentrisch zur Achse verlaufenden Kreis angeordnet sind. Bei dieser Ausbildung kann mit KohlenstoffStäben gearbeitet werden, wie sie auch als Elektroden für Elektroofen zum Einsatz gelangen. Das entsprechende Elektrodenmaterial kann graphitiert werden und zeichnet sich durch überaus hohe, auch mechanische, Stabilität aus. Die Anordnung von derartigen Heizstäben parallel zur Achse eines Schachtofens erlaubt es zu allem Überfluss beliebige Schaltungen dieser Heizstäbe zu realisieren, wobei die Ausbildung mit Vorteil so getroffen sein kann, dass die Heizstäbe jeweils an einem Ende mit einem benachbarten Ende eines in Umfangsrichtung des Schachtofens benachbarten Heizstabes verbunden sind. Bei einer derartigen Ausbildung kann mit Vorteil die Verbindung benachbarter Heizstäbe schaltbar sein, wobei die Heizstäbe wahlweise miteinander verbindbar oder gesondert mit der Stromquelle verbindbar sind. In Umfangsrichtung gesehen können somit einzelne Heizstäbe in Serie oder parallel geschaltet betrieben werden, wobei zu allem Überfluss einzelne Heizstäbe oder Gruppen von Heizstäben mit unterschiedlicher Frequenz zur induktiven Erwärmung eingesetzt werden können, oder aber beispielsweise auch teilweise durch Beaufschlagung mit Gleichstrom als konduktiv thermische Heizstrahler Verwendung finden. Die Bauweise als Schachtofen, bei welchem der gesamte Mantel induktive und/oder konduktive Heizelemente trägt, mit welchen überaus hohen Temperaturen ohne weiteres realisiert werden können, ermöglicht hier besonders bevorzugte Verwendungen eines derartigen Schachtofens. Erfindungsgemäß besteht eine derartige bevorzugte Verwendung darin, dass der Schachtofen zum Graphiti- sieren von KohlenstoffStäben verwendet wird, welche in axialer Richtung durch den Ofen hindurch geführt werden. Bedingt durch die überaus hohen Temperaturen ist es auf diese Weise sogar möglich, graphitisierte Stäbe und insbesondere Elektroden kontinuierlich herzustellen. Eine weitere besonders vorteilhafte Verwendung des erfindungsgemäßen Schachtofens besteht darin, dass Stahl oder Drittelschlacke (CaF2/Al203/Ca0) erschmolzen werden kann, wobei auf Grund der hohen Temperaturen auch die Aufschmelzung bzw. das reduzierende Erschmelzen von Silizium, Siliziumcarbid, Eisensilizium oder Phosphor in vorteilhafter Weise gelingt.Alternatively to the described embodiment, in which the heating elements are formed along a helical line or annularly arranged conductor tracks made of carbon, but can be made in a particularly simple manner, the formation that the heating elements of coal, coke or graphite rods are formed. In this case, the arrangement is preferably such that the heating rods are arranged substantially parallel to the axis of the tubular shaft furnace, wherein advantageously the shaft furnace is cylindrical and a plurality of heating rods are arranged on a circle extending concentrically to the axis. In this training can be used with carbon rods, as they are used as electrodes for electric furnace. The corresponding electrode material can be graphitized and is characterized by extremely high, even mechanical, stability. The arrangement of such heating elements parallel to the axis of a shaft furnace allows for all abundance to realize any circuits of these heating elements, the training can be made with advantage so that the heating elements each at one end to an adjacent end of an adjacent heater in the circumferential direction of the shaft furnace are connected. In such a configuration, the connection of adjacent heating rods can advantageously be switchable, wherein the heating elements can be connected to one another or can be connected separately to the power source. Seen in the circumferential direction thus individual heating elements can be operated in series or connected in parallel, to be abundant individual heating elements or groups of heating elements with different frequency can be used for inductive heating, or, for example, partly by applying direct current as a conductive thermal radiant heater use , The design as shaft furnace, in which the entire jacket carries inductive and / or conductive heating elements, with which extremely high temperatures can be readily realized, allows particularly preferred uses of such a shaft furnace. According to the invention, such a preferred use is that the shaft furnace is used for graphitizing carbon rods which are passed through the furnace in the axial direction. Due to the extremely high temperatures, it is even possible in this way to produce graphitized rods and in particular electrodes continuously. Another particularly advantageous use of the shaft furnace according to the invention is that steel or slurry (CaF 2 / Al 2 0 3 / Ca0) can be melted, wherein due to the high temperatures, the melting or the reducing melting of silicon, silicon carbide, iron silicon or phosphorus succeeds in an advantageous manner.
Prinzipiell eignet sich ein aus Kohlenstoff bzw. Graphit gebildeter Leiter für den Einsatz über einen überaus großen Frequenzbereich, wobei im Fall von Gleichstrom bzw. Wechselstrom mit Frequenz f = O eine rein konduktive Erhitzung der Graphitleiterbahnen, insbesonders Stäbe oder Ringsegmente, auf Grund des ohmschen Widerstandes erfolgt. Wenn Wechselstrom angelegt wird, dann wird je nach Frequenz des Wechselstroms die Widerstandsheizung oder eine Induktionserhitzung des Einsatzgutes, beispielsweise eines Koksbettes oder im Falle eines Tiegels einer Stahlschmelze, erfolgen, wobei die Verwendung von Graphit als Leiter überall dort besonders vorteilhaft ist, wo neutrale bis reduktive Bedingungen herrschen. Induktionsschmelzöfen, bei denen im Vakuum oder unter Inertgas hochschmelzende Stahllegierungen erschmolzen werden, sind hier ein mögliches Anwendungsbeispiel. Gegenüber wassergekühlten Kup- ferspulen wird hier die mögliche Explosionsgefahr eliminiert, da es im Fall von Leckstellen bei Austreten von Wasser zur Bildung von Knallgas kommen kann, wobei zu allem Überfluss Wasserstoff in die Stahlschmelze diffundieren könnte. Die Verwendung des hochfeuerfesten Leitermaterials erlaubt es, die Temperatur des Leiters im Wesentlichen gleich der Temperatur des Behandlungsgutes zu wählen, womit die Leitfähigkeit signifikant ansteigt. Eine weitere Erhöhung der Leitfähigkeit bei höheren Temperaturen gelingt wie bereits oben erwähnt durch Beimengen von thermisch dissoziierenden Metallsalzen, welche bei hohen Temperaturen sehr gute Leiter darstellen.In principle, a conductor made of carbon or graphite is suitable for use over a very large frequency range, wherein in the case of direct current or alternating current with frequency f = 0 a purely conductive heating of the graphite conductor tracks, in particular rods or ring segments, due to the ohmic resistance he follows. If alternating current is applied, depending on the frequency of the alternating current, the resistance heating or an induction heating of the feed, for example a coke bed or in the case of a crucible of molten steel, take place, the use of graphite as a conductor is particularly advantageous wherever neutral to reductive Conditions prevail. Induction melting furnaces, in which refractory steel alloys are melted under vacuum or under inert gas, are a possible application example here. Compared to water-cooled copper Here, the possible risk of explosion is eliminated because, in the case of leaks, leakage of water may result in the formation of oxyhydrogen gas, in which case hydrogen could diffuse into the molten steel. The use of the refractory conductor material makes it possible to choose the temperature of the conductor substantially equal to the temperature of the material to be treated, whereby the conductivity increases significantly. A further increase in the conductivity at higher temperatures succeeds, as already mentioned above, by admixing thermally dissociating metal salts, which are very good conductors at high temperatures.
Prinzipiell eignet sich der erfindungsgemäße elektrisch beheizte Schachtofen sowohl als Induktionsofen als auch als konduktiv beheizter Ofen, wobei im Falle elektrisch leitender Chargen und insbesondere im Falle eines Koksbettes oder eines Tiegels mit Stahlschmelze Temperaturen von ungefähr 2300° C ohne weiteres realisiert werden können. Graphit bleibt in reduzierender Atmosphäre bis zu Temperaturen von etwa 3400° C formbeständig, wobei bei reiner Widerstandserhitzung die Wärmeübertragung über Strahlung und Leitung mit sehr hohem Wirkungsgrad gelingt.In principle, the electrically heated shaft furnace according to the invention is suitable both as an induction furnace and as a conductively heated furnace, wherein in the case of electrically conductive batches and in particular in the case of a coke bed or a crucible with molten steel temperatures of about 2300 ° C can be readily realized. Graphite remains dimensionally stable in a reducing atmosphere up to temperatures of about 3400 ° C, with pure resistance heating, the heat transfer via radiation and conduction with very high efficiency succeeds.
Die Erfindung wird nachfolgend anhand eines in der Zeichnung schematisch dargestellten Ausführungsbeispiels eines Schacht- ofens näher erläutert. In dieser zeigen Fig. 1 eine Draufsicht auf einen geschlitzten Graphitring, Fig. 2 eine Schnittdarstellung in Richtung des Pfeiles II - II der Fig. 1 und Fig. 3 eine Schnittdarstellung in Richtung des Pfeiles III - III der Fig. 1. Die Schnittdarstellung nach Fig. 2 und Fig. 3 zeigen hierbei jeweils nur den halben Schachtofen im Schnitt. Fig. 4 zeigt einen Axialschnitt durch eine abgewandelte Ausbildung des Schachtofens mit stabförmigen Heizelementen, Fig. 5 einen Schnitt nach der Linie V, V der Fig. 4, Fig. 6 eine abgewandelte Ausbildung in einer Darstellung entsprechend der Fig. 5 und Fig. 7 einen Querschnitt durch eine abgewandelte Ausbildung mit achsparallel verlaufenden Leiterbahnen.The invention will be explained in more detail with reference to an embodiment of a shaft furnace schematically illustrated in the drawing. 1 is a plan view of a slotted graphite ring, FIG. 2 is a sectional view in the direction of arrow II - II of FIG. 1 and FIG. 3 is a sectional view in the direction of arrow III - III of FIG. 1. The sectional view FIGS. 2 and 3 each show only half the shaft furnace in section. Fig. 4 shows an axial section through a modified embodiment of the shaft furnace with rod-shaped heating elements, Fig. 5 is a section along the line V, V of Fig. 4, Fig. 6 shows a modified embodiment in a representation corresponding to FIG. 5 and 7 shows a cross section through a modified embodiment with axially parallel conductor tracks.
In Fig. 1 ist mit 1 ein geschlitzter Graphitring bezeichnet, dessen freie Enden in Stirnflächen 2 und 3 münden. Über diese Stirnflächen 2 und 3 können die geschlitzten Graphitringe elektrisch kontaktiert werden und entsprechend mit Gleichstrom, niederfrequentem oder hochfrequentem Wechselstrom beaufschlagt werden.In Fig. 1, 1 denotes a slotted graphite ring, whose free ends open into end faces 2 and 3. About these end faces 2 and 3, the slotted graphite rings can be contacted electrically and are acted upon accordingly with direct current, low frequency or high frequency alternating current.
Bei der Darstellung nach Fig. 2 sind jeweils die Kontaktflächen 3 ersichtlich, die bei in Richtung der Achse 4 des Schachtofens 5 übereinander liegenden Graphitringen miteinander verbunden sind. Über den Bereich a sind hierbei, wie sich in Kombination mit der Darstellung nach Fig. 3 ergibt, die Graphitringe in Serie geschaltet, wohingegen über den axialen Bereich b zwei Graphitringe parallel zu einander betrieben werden.In the illustration according to FIG. 2, in each case the contact surfaces 3 can be seen, which are connected to one another in the direction of the axis 4 of the shaft furnace 5 lying graphite rings. Over the range a, the graphite rings are connected in series, as is shown in combination with the illustration according to FIG. 3, whereas two graphite rings are operated parallel to one another over the axial region b.
Bei der Darstellung nach Fig. 3 sind jeweils die freien Stirn- flächen 2 der geschlitzten Ringe ersichtlich. In Kombination mit der Darstellung nach Fig. 2 mit den Stirnflächen 3 ergibt sich somit, dass über den Bereich a Strom an die unterste Stirnfläche 2 angelegt wird und in der Folge über in Höhenrichtung benachbarte Stirnflächen 3 die Kontaktierung auf den nachfolgenden Graphitring 1 erfolgt, worauf wiederum - um einen Winkel von etwa 180° verdreht - die Kontaktierung benachbarter Stirnflächen 2 zur Erzielung einer Serienschaltung der Ringe erfolgt. Über die Anschlüsse 6 und 7 kann hier Gleichstrom oder niederfrequenter Wechselstrom zugeführt werden. Für die Zufuhr von hochfrequentem Wechselstrom und insbesondere für den Einsatz bei Frequenzen von über 60 kHz, und zwar bis etwa 350 kHz, empfiehlt sich eine Parallelschaltung, wie sie im axialen Bereich b ersichtlich ist, wobei die entsprechenden Anschlüsse hier mit 8 und 9 bezeichnet sind und jeweils zwei in Achsrich- tung aufeinander folgende Ringe 1 parallel geschaltet sind. Eine derartige Parallelschaltung führt zu einer Verringerung der benötigten Spannung im Falle einer induktiven Beheizung, sodass das Gefahren- und Überschlagspotenzial verringert wird.In the illustration according to FIG. 3, the free end faces 2 of the slotted rings can be seen in each case. In combination with the illustration according to FIG. 2 with the end faces 3, it follows that current is applied to the lowermost end face 2 over the region a and contacting the following graphite ring 1 takes place via adjacent end faces 3 in the vertical direction in turn - twisted by an angle of about 180 ° - the contacting of adjacent end faces 2 to achieve a series connection of the rings takes place. About the terminals 6 and 7 can be supplied here DC or low-frequency alternating current. For the supply of high-frequency alternating current and in particular for use at frequencies of over 60 kHz, and up to about 350 kHz, a parallel circuit is recommended, as can be seen in the axial region b, the corresponding terminals are designated here 8 and 9 and two each in Achsrich- tion successive rings 1 are connected in parallel. Such a parallel connection leads to a reduction of the required voltage in the case of inductive heating, so that the danger and rollover potential is reduced.
Im Prinzip kann die Ausbildung über die axiale Höhe des Schachtofens 5 flexibel gewählt werden und es kann wahlweise in einzelnen axialen Breichen eine Parallelschaltung oder eine serielle Schaltung vorgenommen werden um den jeweils erforder- liehen Temperaturprofilen Rechnung tragen zu können.In principle, the training on the axial height of the shaft furnace 5 can be chosen flexibly and it can optionally be made in individual axial Breichen a parallel circuit or a serial circuit in order to be able to take into account the respective lent temperature profiles.
Fig. 4 zeigt einen Querschnitt durch einen Schachtofen 10, in dessen feuerfesten Mantel 11 stabförmig Heizelemente 12 eingelassen sind. Die stabförmigen Heizelemente 12 sind hierbei von Graphitstäben gebildet. Die benachbarten Enden derartiger Graphitstäbe 12 können wahlweise über leitende Verbindungen 13 an einem Ende und leitenden Verbindungen 14 am anderen Ende der Stäbe jeweils mit einander verbunden sein, wodurch sich eine Serienschaltung von drei neben einander angeordneten Graphit- Stäben 12 realisieren lässt. Die durch diese Serienschaltung erzielten Enden des Gesamtwiderstandes und der Gesamtinduktivität kann sowohl bei Verwendung als induktive Beheizung unter Anschluss von Wechselstrom, als auch von konduktiver Heizung unter Anschluss von Gleichstrom entsprechend verwendet werden. Die Schaltung der einzelnen Stäbe ergibt sich hierbei aus der Schnittdarstellung nach Fig. 7, wobei sich insgesamt ein Käfig aus Graphitstäben als Induktor ausbilden lässt, wobei die einzelnen Graphitstäbe des Käfigs parallel oder seriell geschaltet werden können.Fig. 4 shows a cross section through a shaft furnace 10, in the refractory shell 11 rod-shaped heating elements 12 are embedded. The rod-shaped heating elements 12 are formed here by graphite rods. The adjacent ends of such graphite rods 12 may be selectively connected to each other via conductive connections 13 at one end and conductive connections 14 at the other end of the rods, whereby a series connection of three adjacent graphite rods 12 can be realized. The ends of the total resistance and the total inductance achieved by this series connection can be used correspondingly both when used as inductive heating with the connection of alternating current, and from conductive heating with connection of direct current. The circuit of the individual bars results here from the sectional view of FIG. 7, wherein a total of a cage made of graphite rods can be formed as an inductor, wherein the individual graphite rods of the cage can be connected in parallel or in series.
Die leicht abgewandelte Ausbildung nach Fig. 6, deren Darstellung im Wesentlichen der Darstellung nach Fig. 5 entspricht, lässt einen mehrschichtigen Aufbau des Mantels erkennen und ist bevorzugt bei Höchsttemperaturen eingesezt, um Grahitierungs- reaktionen hervorzurufen. Die Heizelemente 12 sind hierbei von einem ersten Mantel aus Graphit umgeben, wobei dieser erste Mantel 15 aus einzelnen Segmenten zusammengesetzt werden kann. Die freistehenden GraphitStäbe bzw. Graphitelektroden können hierbei, soweit es erforderliche ist, gegebenenfalls mit Inertgas gespült werden, wofür Einlassöffnungen 16 vorgesehen sind. Der Graphitmantel 15 wird außen von einem weiteren Mantel aus feuerfestem Material umgeben, welcher mit 17 bezeichnet wird. Eine derartige Ausbildung kann beispielsweise für das Graphiti- sieren von KohlenstoffStäben verwendet werden, wie dies schematisch durch ein Koksextrudat 18 angedeutet ist, welches in Richtung des Pfeiles 19 durch den Schachtofen hindurch gefördert werden kann. Bei entsprechend hoher Temperatur und entsprechender Verweilzeit kann neben einem kontinuierlichen Backen auch ein Graphitieren von Koksextrudat 18 erzielt werden, wodurch die Kristallisation des Kohlenstoffs im Koksextrudat 18 bewirkt werden kann.The slightly modified embodiment according to FIG. 6, the illustration of which corresponds essentially to the illustration according to FIG. 5, reveals a multilayer construction of the jacket and is preferably used at maximum temperatures in order to obtain graffiti. to cause reactions. The heating elements 12 are in this case surrounded by a first jacket made of graphite, wherein this first jacket 15 can be composed of individual segments. The freestanding graphite rods or graphite electrodes can, if necessary, be purged with inert gas if necessary, for which inlet openings 16 are provided. The graphite shell 15 is surrounded on the outside by another shell made of refractory material, which is denoted by 17. Such a design can be used, for example, for the graphitization of carbon rods, as indicated schematically by a coextruded rubber 18, which can be conveyed in the direction of the arrow 19 through the shaft furnace. At a correspondingly high temperature and appropriate residence time, in addition to continuous baking, graphitization of coke extrudate 18 can also be achieved, as a result of which the crystallization of the carbon in the coextrudate 18 can be effected.
In Fig. 7 werden schematisch verschiedene Anwendungsbeispiele des Schachtofens dargestellt, wobei wiederum eine abgewandelte Ausbildung des Schachtofens vorgesehen ist. In dem Mantel 11 aus feuerfestem Material sind hier Nuten 20 vorgesehen, welche Schwalbenschwanzförmig ausgebildet sind und die Leiterbahnen bzw. Graphitstäbe 21 enthalten. Die innere Fläche dieses Graphitstabes bzw. der Leiterbahn ist hierbei auf einem größeren radialen Abstand von der Achse 22 des Schachtofens als die Innenwand 23 des feuerfesten Mantels, sodass im Falle der Verwendung eines Koksbettes zur Schmelzreduktion eine unmittelbar leitende Berührung zwischen dem Koksbett und dem Graphit- stab verhindert wird. Eine derartige Beschickung bzw. ein derartiger Einsatz eines Koksbettes ist durch die Koksstücke angedeutet. Alternativ kann wie in einem weiteren Segment des Schachtofens im Querschnitt angedeutet, eine Schmelze hergestellt werden und der Schachtofen als Tiegel zum Schmelzen von Stahl eingesetzt werden. Die Schmelze ist hierbei schematisch mit 24 angedeutet. In einem weiteren Abschnitt 25, welcher eine weitere mögliche Verwendung des Schachtofens verdeutlicht, kann das Verfahren so verwendet werden, das ein Graphitwärmetau- scher, mit dem Bezugszeichen 25 angedeutet, zur Herstellung von Drittelschlacke eingesetzt wird.In Fig. 7 schematically different application examples of the shaft furnace are shown, again a modified design of the shaft furnace is provided. In the shell 11 of refractory material grooves 20 are provided here, which are dovetail-shaped and the conductor tracks or graphite rods 21 included. The inner surface of this graphite rod or strip is in this case at a greater radial distance from the shaft 22 of the shaft furnace than the inner wall 23 of the refractory shell, so that in the case of the use of a Koksbettes for smelting reduction directly conductive contact between the coke bed and the graphite bar is prevented. Such a feed or such a use of a coke bed is indicated by the Koksstücke. Alternatively, as in a further segment of the shaft furnace indicated in cross-section, a melt can be produced and the shaft furnace as a crucible for melting Steel are used. The melt is indicated schematically at 24 here. In a further section 25, which illustrates a further possible use of the shaft furnace, the method can be used so that a graphite heat exchanger, indicated by the reference numeral 25, is used for the production of tertiary slag.
Prinzipiell können die Graphitstäbe sowohl als Konduktor als auch als Induktor betrieben werden, wobei die Feldlinien sich durch den axialen Hohlraum des Schachtofens erstrecken. In principle, the graphite rods can be operated both as a conductor and as an inductor, the field lines extending through the axial cavity of the shaft furnace.

Claims

Patentansprüche : Claims:
1. Elektrisch beheizter Schachtofen mit wenigstens einem von elektrischen Leitern gebildeten Heizelement, dadurch gekennzeichnet, dass das oder die Heizelement (e) (12) aus Kohlenstoff bestehen.1. Electrically heated shaft furnace with at least one heating element formed by electrical conductors, characterized in that the heating element or elements (12) consist of carbon.
2. Schachtofen nach Anspruch 1, dadurch gekennzeichnet, dass die Heizelemente (12) als in oder an einem feuerfesten Träger eingebettete oder angeordnete Leiterbahnen aus Graphit bestehen.2. shaft furnace according to claim 1, characterized in that the heating elements (12) as embedded in or on a refractory support or arranged conductor tracks made of graphite.
3. Schachtofen nach Anspruch 1 oder 2 , dadurch gekennzeich- net, dass die Heizelemente (12) von in Umfangsrichtung in Form von Ringen, Ringsegmenten (1) oder einer Schraubenlinie angeordneten Leitern gebildet sind.3. shaft furnace according to claim 1 or 2, characterized marked, that the heating elements (12) are arranged in the circumferential direction in the form of rings, ring segments (1) or a helix arranged conductors.
4. Schachtofen nach Anspruch 1, 2 oder 3, dadurch gekenn- zeichnet, dass die Heizelemente (12) von Kohle-, Koks- oder4. shaft furnace according to claim 1, 2 or 3, characterized in that the heating elements (12) of coal, coke or
Graphitstäben gebildet sind.Graphite rods are formed.
5. Schachtofen nach Anspruch 4, dadurch gekennzeichnet, dass die Heizstäbe (12) im Wesentlichen parallel zur Achse des rohrförmigen Schachtofens angeordnet sind.5. shaft furnace according to claim 4, characterized in that the heating rods (12) are arranged substantially parallel to the axis of the tubular shaft furnace.
6. Schachtofen nach Anspruch 4 oder 5, dadurch gekennzeichnet, dass der Schachtofen (5) zylindrisch ausgebildet ist und eine Mehrzahl von Heizstäben (12) auf einem konzentrisch zur Achse (22) verlaufenden Kreis angeordnet sind.6. shaft furnace according to claim 4 or 5, characterized in that the shaft furnace (5) is cylindrical and a plurality of heating rods (12) on a concentric to the axis (22) extending circle are arranged.
7. Schachtofen nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass der Mantel (17) des Schachtofens aus feuerfestem Material besteht und an seiner Innenfläche Rillen, insbesondere schraubenlinienförmige Rillen (10) für die Aufnahme von aus Graphit gebildeten Leiterbahnen aufweist.7. shaft furnace according to one of claims 1 to 6, characterized in that the jacket (17) of the shaft furnace made of refractory material and grooves on its inner surface, in particular helical grooves (10) for receiving graphite formed tracks.
8. Schachtofen nach einem der Ansprüche 1 bis 7 , dadurch gekennzeichnet, dass der Innenmantel (15) mit einer feuerfesten8. shaft furnace according to one of claims 1 to 7, characterized in that the inner jacket (15) with a refractory
Isolationsschicht bzw. Folie oder Isolationsmatte ausgekleidet ist.Insulating layer or foil or insulation mat is lined.
9. Schachtofen nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass das feuerfeste Material und/oder die9. shaft furnace according to one of claims 1 to 8, characterized in that the refractory material and / or the
Isolationsschicht aus MgO, Al2O3 oder Schamotte gebildet ist.Insulation layer of MgO, Al 2 O 3 or chamotte is formed.
10. Schachtofen nach einem der Ansprüche 1 bis 3 oder 7 bis 9, dadurch gekennzeichnet, dass die Graphitringe an ihrem Umfang geschlitzt ausgebildet sind und die freien Enden (2, 3) der Ringe parallel oder in Serie an eine Stromquelle anlegbar sind.10. shaft furnace according to one of claims 1 to 3 or 7 to 9, characterized in that the graphite rings are formed slotted at its periphery and the free ends (2, 3) of the rings can be applied in parallel or in series to a power source.
11. Schachtofen nach einem der Ansprüche 1 bis 10, dadurch gekennzeichnet, dass die Leiterbahnen aus gestampftem Graphit- pulver oder einem mit elektrisch leitenden Substanzen, insbesondere thermisch dissoziierenden Salzen dotiert ausgebildet sind.11. Shaft furnace according to one of claims 1 to 10, characterized in that the conductor tracks of stamped graphite powder or doped with electrically conductive substances, in particular thermally dissociated salts are formed.
12. Schachtofen nach einem der Ansprüche 1 bis 11, dadurch gekennzeichnet, dass die Tiefe der Rillen (20) im Mantel (15) größer als die Breite der Leiterbahnen bzw. der Graphitringe gewählt ist und der radiale Abstand der Leiterbahnen von der Achse (22) bzw. der Innendurchmesser der Graphitringe größer als der Innendurchmesser des Mantels (15) des Schachtofens (5) gewählt ist.12. shaft furnace according to one of claims 1 to 11, characterized in that the depth of the grooves (20) in the jacket (15) is greater than the width of the conductor tracks or the graphite rings is selected and the radial distance of the conductor tracks from the axis (22 ) or the inner diameter of the graphite rings is greater than the inner diameter of the jacket (15) of the shaft furnace (5) is selected.
13. Schachtofen nach einem der Ansprüche 1 oder 4 bis 9, dadurch gekennzeichnet, dass die Heizstäbe (12) jeweils an einem Ende mit einem benachbarten Ende eines in Umfangsrichtung des Schachtofens benachbarten Heizstabes (12) verbunden sind.13. shaft furnace according to one of claims 1 or 4 to 9, characterized in that the heating elements (12) respectively one end connected to an adjacent end of a heater rod (12) adjacent in the circumferential direction of the shaft furnace.
14. Schachtofen nach Anspruch 13, dadurch gekennzeichnet, dass die Verbindung benachbarter Heizstäbe (12) schaltbar ist und die Heizstäbe (12) wahlweise miteinander verbindbar oder gesondert mit der Stromquelle verbindbar sind.14. shaft furnace according to claim 13, characterized in that the connection of adjacent heating rods (12) is switchable and the heating elements (12) are selectively connectable to each other or separately connected to the power source.
15. Verwendung eines Schachtofens nach einem der Ansprüche 1 bis 14 zum Graphitisieren von KohlenstoffStäben, welche in axialer Richtung durch den Ofen (5) hindurch geführt werden.15. Use of a shaft furnace according to one of claims 1 to 14 for graphitizing carbon rods which are guided in the axial direction through the furnace (5).
16. Verwendung eines Schachtofens nach einem der Ansprüche 1 bis 14 zum Einschmelzen von Stahl bzw. zur Herstellung von Si, SiC, FeSi, FeCr, FeMn, FeV, P oder Drittelschlacke (CaF2/Al203/Ca0) . 16. Use of a shaft furnace according to one of claims 1 to 14 for melting steel or for the production of Si, SiC, FeSi, FeCr, FeMn, FeV, P or thirds slag (CaF 2 / Al 2 0 3 / Ca0).
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PL2255139T3 (en) 2014-03-31

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