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WO2005052448A1 - Rotating hearth furnace for waste with a hazard potential - Google Patents

Rotating hearth furnace for waste with a hazard potential Download PDF

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Publication number
WO2005052448A1
WO2005052448A1 PCT/EP2004/007283 EP2004007283W WO2005052448A1 WO 2005052448 A1 WO2005052448 A1 WO 2005052448A1 EP 2004007283 W EP2004007283 W EP 2004007283W WO 2005052448 A1 WO2005052448 A1 WO 2005052448A1
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WO
WIPO (PCT)
Prior art keywords
furnace
electrodes
rotary hearth
hearth furnace
lining
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
PCT/EP2004/007283
Other languages
German (de)
French (fr)
Inventor
Robert Ineichen
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.)
Zwilag Zwischenlager Wuerenlingen AG
Original Assignee
Zwilag Zwischenlager Wuerenlingen 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
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Application filed by Zwilag Zwischenlager Wuerenlingen AG filed Critical Zwilag Zwischenlager Wuerenlingen AG
Priority to JP2006540190A priority Critical patent/JP2007511732A/en
Publication of WO2005052448A1 publication Critical patent/WO2005052448A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
    • F23G5/085—High-temperature heating means, e.g. plasma, for partly melting the waste
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
    • F23G5/10—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating electric
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2203/00—Furnace arrangements
    • F23G2203/20—Rotary drum furnace
    • F23G2203/202—Rotary drum furnace rotating around substantially vertical axis
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2900/00—Special features of, or arrangements for incinerators
    • F23G2900/508—Providing additional energy for combustion, e.g. by using supplementary heating
    • F23G2900/51001—Providing additional energy for combustion, e.g. by using supplementary heating using arc discharge electrodes to provide heat

Definitions

  • the invention relates to a furnace, in particular a rotary hearth furnace for waste with potential Ge, especially for radioactive and toxic waste.
  • furnaces such as. B. induction furnaces, arc furnaces or plasma furnaces for the treatment of toxic and / or radioactive waste are known.
  • inert atmosphere in the plasma furnace and the high arc temperatures of 10000 ° C to 15000 ° C lead to a complete decomposition of the materials to be treated. Solid residues of these materials can in turn be fixed in a glass matrix and thus encapsulated in relation to the environment.
  • EP 0 636 839 B1 describes a rotary hearth furnace with such a plasma torch energy source.
  • the cylindrical furnace chamber of the plasma rotary hearth furnace has a central pouring opening located in the axis of rotation, through which the glazed residues of the decomposed waste are poured.
  • the energy required for the decomposition is supplied by means of a transferring arc plasma torch which is in electrical contact with the bottom of the furnace or parts thereof.
  • Graphite stones or electrically conductive, thermally resistant ramming compounds are usually used in the furnace floor for the electrical coupling of the transferring direct current plasma torch.
  • these conductive materials have a number of disadvantages. Depending on the chemical composition settlement of the melt to be treated, these electrically conductive materials have an insufficient service life.
  • the furnace or the furnace floor lining only withstands the stress of the company for a limited period of time. Frequent renewals of the furnace floor lining are the result.
  • thermal loads occur in the furnace construction in the vicinity of the furnace floor lining. Active cooling may even be necessary here.
  • a furnace floor lining made of electrically conductive materials it is not possible to provide a safety insulation layer which could prevent the risk of a furnace breakthrough in or on the furnace structure underneath.
  • the object of the present invention is to avoid the disadvantages of the known and, in particular, to provide a furnace for the plasma combustion and melting technology with improved current flow in the furnace bottom and to increase the service life.
  • the furnace according to the invention for the plasma combustion and melting technology contains a furnace trough (centrifuge) with furnace bottom and furnace side wall, the furnace centrifuge having a thermally and chemically resistant lining material on the inside, and a pouring opening preferably arranged in the axis of rotation of the rotary hearth furnace.
  • the resistant brick lining material leads electrodes into the furnace chamber.
  • the invention offers Shielding the furnace structure against the effects of combustion, a number of advantages.
  • the service life of the rotary hearth furnace is significantly extended, since the lining material does not have to be used for the transmission of the electrical current.
  • the use of electrodes, which are sealed by the lining material, on the one hand results in a safe current supply and improved control engineering aspects. It is important for the arrangement of the electrodes in the lining that an even current flow is guaranteed under the intended operating conditions.
  • the electrodes should therefore be arranged on the base surface at a predetermined distance from one another so that an interruption of the plasma torch arc can be ruled out.
  • This maximum distance is dependent on electrical parameters such as voltage, current, the distance to the plasma electrode and the conductivity of materials, in particular liquid, viscous or possibly largely solid materials, which may be located in the furnace pan during operation.
  • the thickness of such a loading of the furnace trough also influences the maximum distance. This maximum distance can easily be determined for the person skilled in the art on the basis of experience and the specified working parameters.
  • Uniform plasma generation therefore preferably means a constant energy / current flow according to the parameters specified by the control.
  • At least 60 electrodes are preferably arranged per m 2 of area of the furnace floor. This number of electrodes is each also depending on the furnace geometry, the dimensions of the electrodes, the plasma torch output and the waste spectrum to be processed. For example, more electrodes must be used for electrodes with a small cross-section.
  • Electrodes which consist of steel or Cu alloys are preferably used in the rotary hearth furnace according to the invention. Such electrodes have several advantages. On the one hand, the materials of these electrodes have very good electrical conductivity, so that the size of the electrodes can be chosen to be smaller and the applied electrical parameters, especially the voltage, can be kept lower. On the other hand, the electrodes can be produced and exchanged separately from the lining of the furnace trough, whereby a further cost advantage in production and maintenance can be achieved.
  • the cross section of the electrodes preferably has a dimension between 5 and 60 mm, preferably between 10 and 50 mm.
  • the length of the electrodes is between 250 and 800 mm, preferably between 300 and 700 mm, or is determined depending on the required floor lining thickness.
  • a uniform size of the cross section is advantageously chosen, so that a simple production of the lining of the furnace floor is possible. Due to the necessary inclination of the furnace floor towards that in the center, i.e.
  • the required length of the electrodes used can vary depending on the distance to the pour opening in the pour opening arranged in the axis of rotation.
  • the lining material for the furnace trough is advantageously selected from the resistant materials usually used in furnace construction.
  • Exemplary materials are casting compounds, ramming compounds, cast or pressed shaped blocks, in particular special of corundum, chromium corundum and / or mixtures containing high alumina. Combinations of these different materials are also conceivable.
  • the selection of these masonry or refractory materials can largely be geared to requirements with regard to service life, without being significantly restricted by requirements for the power supply.
  • the pouring opening is likewise advantageously designed as a central opening in a one-piece block (pouring stone) of a lining material. This ensures that the melting material flowing out cannot damage the furnace structure in the region of the pouring opening.
  • the structural separation of the cast stone from the rest of the furnace floor makes it easier to manufacture and maintain the furnace pan. An expansion of the pouring opening due to material erosion can be reduced or even avoided by choosing an appropriate lining material.
  • the electrodes on the underside of the furnace floor lining are electrically conductively connected to the furnace floor support structure, preferably made of steel.
  • the furnace floor lining preferably has a layer structure. This contains a layer of the lining material on the inside, ie the side facing a reaction chamber, and at least one stabilization or insulation layer. The stabilization or insulation layer rests on the furnace floor support structure.
  • This furnace floor support structure is designed to be electrically conductive and is connected to the electrical circuit by means of several current collector brushes. Particularly good stability properties result if the electrodes are directly connected to this furnace floor support structure in a form-fitting manner.
  • the electrodes are preferably arranged with their longitudinal axis slightly inclined with respect to the surface of the furnace floor support structure. This arrangement avoids structural weak points in the transition area between the electrode and the surrounding lining material.
  • the contact surface of the electrode at the interface with the support structure has an oval cross section.
  • Figure 2 is a plan view of the furnace floor.
  • FIG. 1 shows a simplified illustration of an oven 1 according to the invention.
  • the furnace 1 comprises the furnace trough 2 and a furnace floor support structure 9 for the furnace trough 2.
  • the furnace trough contains a support structure 8 for the furnace wall lining 4, stabilization or insulation structures 10, 11, 12 and a casting stone 13 with the centrally arranged, that is, the pouring opening 6 coinciding with the axis of rotation R.
  • the furnace wall 4 and the furnace floor lining 3 are supported by the stabilization or insulation layers 10, 11, 12.
  • the electrodes 7 for current conduction for the plasma arc generation are arranged on four circles arranged concentrically around the pouring opening 6.
  • the electrodes also pass through the stabilization or insulation layer 10, 11, 12 and hen with the furnace floor support structure 9 in electrical contact.
  • the current collector brushes 14 are indicated in FIG. 1.
  • the furnace floor support structure 9 has a U-shaped cross-sectional profile that is open at the top, so that the support structure 8 is encompassed.
  • the current collector brushes 14, their holders 15 and the cables 16 provide the electrical connection for closing the circuit for the plasma generation.
  • the rotary hearth furnace is set in rotation by means of drive units 20.
  • the bearing bracket 18 is in turn supported on a stationary bearing 17.
  • FIG. 30 A specific arrangement for the electrodes 7 is shown in FIG. 30 electrodes 7 each are arranged concentrically around the pouring opening 6 on four circles of different sizes.
  • the electrodes 7 made of steel St 37-2 have a diameter of 15 mm and a length between 411 and 436 mm.
  • the length differences result due to the inclination of the furnace floor 3 and the horizontally arranged furnace floor support structure 9, the longer electrodes 7 are arranged on the circles with the larger circumference.
  • the differences in the diameters are in each case 200 mm, the smallest circle diameter being 1085 mm is.
  • the inner diameter of the furnace side wall 4 is 2041 mm.
  • the casting opening 6 has a diameter of 80 mm
  • the casting stone 13 has an outer diameter on the furnace bottom 3 of 460 mm or 640 mm.
  • the sequence of the individual components of the rotary hearth furnace 1, with a procedure from the outside in, is as follows:
  • the electrical connection through the cable 16, the holder 15 and the current collector brushes 14 are above the bearing structure 18 in the plan view
  • the support structure 8 and lining 5 of the furnace trough 2 follow in the direction of the furnace center.
  • the lining 5 consists of casting compounds, ramming compounds, cast or pressed shaped blocks, in particular of corundum, chromium corundum and / or mixtures containing high alumina.
  • the radially offset arrangement of the electrodes 7 in relation to the electrodes in the adjacent arrangement circles is clearly recognizable in the plan view.
  • the electrodes 7 are each separated by an angle Al of 12 °.
  • the minimum angle A2 between two electrodes 7 located on radially successive arrangement circles is 6 °.
  • the arrangement of the electrodes 7 and their dimensions are for a current of a plasma torch with a maximum output of 1.2 MW, respectively. designed for a maximum operating current of 2000 A.
  • the dimensioning and arrangement of the electrodes must be adjusted accordingly for changed operating conditions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Furnace Details (AREA)
  • Gasification And Melting Of Waste (AREA)
  • Processing Of Solid Wastes (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)
  • Discharge Heating (AREA)

Abstract

The current flow required in a rotating hearth furnace (1) for the production of a transferring direct current plasma electric arc occurs in an arrangement comprising a plurality of electrodes (7) which are arranged inside the furnace bottom (3). The spatial arrangement of the electrodes (7) and the dimensioning thereof is essentially influenced by the predetermined operating conditions.

Description

DREHHERD-OFEN FÜR ABFALLE MIT GEFAHRDUNGSPOTENTIAL TURNING OVEN FOR WASTE WITH HAZARDOUS POTENTIAL

Die Erfindung betrifft einen Ofen, insbesondere einen Drehherd- Ofen für Abfälle mit Ge ährdungspotential, vor allem für radioaktive und toxische Abfälle.The invention relates to a furnace, in particular a rotary hearth furnace for waste with potential Ge, especially for radioactive and toxic waste.

Eine Reihe von Abfällen weist ein erhebliches Gefährdungspotential auf, das eine weitergehende Behandlung zwingend erforderlich macht. Es sind verschiedene Ofentypen, wie z. B. Induktionsöfen, Lichtbogenöfen oder Plasmaöfen für die Behandlung toxischer und/oder radioaktiver Abfälle bekannt. Besonders die inerte Atmosphäre im Plasmaofen sowie die hohen Lichtbogen- Temperaturen von 10000°C bis 15000°C führen zu einer vollständigen Zersetzung der zu behandelnden Materialien. Feste Rückstände dieser Materialien können wiederum in einer Glasmatrix fixiert und so gegenüber der Umwelt verkapselt werden.A number of wastes have a considerable risk potential, which makes further treatment absolutely necessary. There are different types of furnaces, such as. B. induction furnaces, arc furnaces or plasma furnaces for the treatment of toxic and / or radioactive waste are known. Especially the inert atmosphere in the plasma furnace and the high arc temperatures of 10000 ° C to 15000 ° C lead to a complete decomposition of the materials to be treated. Solid residues of these materials can in turn be fixed in a glass matrix and thus encapsulated in relation to the environment.

In EP 0 636 839 Bl wird ein Drehherd-Ofen mit einer derartigen Plasmabrenner-Energiequelle beschrieben. Die zylInderförmige Ofenkammer des Plasmadrehherd-Ofens weist eine in der Rotationsachse gelegene, zentrale Abguss-Öffnung auf, durch die die verglasten Rückstände des zersetzten Abfalls abgegossen werden. Mittels eines transferierenden Lichtbogen-Plasmabrenners, welcher mit dem Boden des Ofens bzw. Teilen davon in elektrischem Kontakt steht, wird die zur Zersetzung erforderliche Energie zugeführt .EP 0 636 839 B1 describes a rotary hearth furnace with such a plasma torch energy source. The cylindrical furnace chamber of the plasma rotary hearth furnace has a central pouring opening located in the axis of rotation, through which the glazed residues of the decomposed waste are poured. The energy required for the decomposition is supplied by means of a transferring arc plasma torch which is in electrical contact with the bottom of the furnace or parts thereof.

Üblicherweise werden im Ofenboden Grafitsteine oder elektrisch leitende, thermisch resistente Stampfmassen für die elektrische Kopplung des transferierenden Gleichstrom-Plasmabrenners eingesetzt. Allerdings weisen diese leitfähigen Materialien eine Reihe von Nachteilen auf . In Abhängigkeit der chemischen Zusammen- setzung des zu behandelnden Schmelzgutes besitzen diese elektrisch leitfähigen Materialien eine unzureichende Standzeit. Der Ofen bzw. die Ofenboden-Ausmauerunj widersteht nur zeitlich eingeschränkt den Belastungen des Betriebes. Häufige Erneuerungen der Ofenboden-Ausmauerung sind die Folge. Andererseits treten durch die gute Wärmeleitfähigkeit der Grafitsteine bzw. Stampfmassen thermische Belastungen bei der Ofen-Konstruktion in Nachbarschaft zur Ofenboden-Ausmauerung auf. Gegebenenfalls ist hier sogar eine aktive Kühlung notwendig. Bei einer Ofenboden- Ausmauerung aus elektrisch leitfähigen Materialien ist es nicht möglich, eine Sicherheitsisolationsschicht vorzusehen, die das Risiko eines Ofendurchbruchs in bzw. auf die darunter befindliche Ofenkonstruktion verhindern könnte.Graphite stones or electrically conductive, thermally resistant ramming compounds are usually used in the furnace floor for the electrical coupling of the transferring direct current plasma torch. However, these conductive materials have a number of disadvantages. Depending on the chemical composition settlement of the melt to be treated, these electrically conductive materials have an insufficient service life. The furnace or the furnace floor lining only withstands the stress of the company for a limited period of time. Frequent renewals of the furnace floor lining are the result. On the other hand, due to the good thermal conductivity of the graphite stones or ramming masses, thermal loads occur in the furnace construction in the vicinity of the furnace floor lining. Active cooling may even be necessary here. In the case of a furnace floor lining made of electrically conductive materials, it is not possible to provide a safety insulation layer which could prevent the risk of a furnace breakthrough in or on the furnace structure underneath.

Aufgabe der vorliegenden Erfindung ist es, die Nachteile des Bekannten zu vermeiden und insbesondere einen Ofen für die Plasma- verbrennungs- und Schmelztechnik mit verbesserter Stromführung im Ofenboden bereitzustellen und die Standzeiten zu vergrössern.The object of the present invention is to avoid the disadvantages of the known and, in particular, to provide a furnace for the plasma combustion and melting technology with improved current flow in the furnace bottom and to increase the service life.

Die Aufgabe wird durch einen Ofen, gemäss den Merkmalen des unabhängigen Anspruchs gelöst .The object is achieved by an oven in accordance with the features of the independent claim.

Der erfindungsgemässe Ofen für die Plasmaverbrennungs- und Schmelztechnik enthält eine Ofenwanne (Zentrifuge) mit Ofenboden und Ofenseitenwand, wobei die Ofen-Zentrifuge auf einer Innenseite ein thermisch und chemisch resistentes Ausmauerungsmaterial aufweist, und eine vorzugsweise in der Rotationsachse des Drehherd-Ofens angeordnete Abgussöffnung. Durch das resistente Ausmauerungsmaterial sind Elektroden in den Ofenraum durchgeführt .The furnace according to the invention for the plasma combustion and melting technology contains a furnace trough (centrifuge) with furnace bottom and furnace side wall, the furnace centrifuge having a thermally and chemically resistant lining material on the inside, and a pouring opening preferably arranged in the axis of rotation of the rotary hearth furnace. The resistant brick lining material leads electrodes into the furnace chamber.

Die Erfindung bietet durch die Trennung der bislang kombinierten Ausführung der elektrischen Zuleitung und der widerstandfähigen Abschirmung der Ofenstruktur gegenüber Verbrennungseinflüssen, eine Reihe von Vorteilen. Durch die Auskleidung der Ofenwanne mit einem geeigneteren, thermisch und chemisch widerstandsfähigerem Ausmauerungsmaterial wird die Nutzungsdauer des Drehherd- Ofens wesentlich verlängert, da das Ausmauerungsmaterial nicht für die Durchleitung des elektrischen Stroms herangezogen werden muss . Der Einsatz von Elektroden, welche dichtend vom Ausmauerungsmaterial umschlossen sind, bewirkt einerseits eine sichere Stromführung sowie verbesserte steuerungstechnische Aspekte. Wichtig für die Anordnung der Elektroden in der Ausmauerungsmasse ist, dass bei den vorgesehenen Betriebsbedingungen eine gleichmässige Stromführung gewährleistet ist. Dies bedeutet, dass trotz der punktuellen Zuführung der elektrischen Energie dennoch eine weitgehend homogene Lichtbogen-Plasmaerzeugung in der Ofenwanne bei der Rotation des Drehherd-Ofens erzielt wird. Die Elektroden sollen also auf der Bodenfläche mit vorbestimmter Distanz zueinander angeordnet sein, damit eine Unterbrechung des Plasmabrenner-Lichtbogens ausgeschlossen werden kann. Diese maximale Distanz ist abhängig von elektrischen Parametern wie Spannung, Strom, dem Abstand zur Plasmaelektrode sowie der Leitfähigkeit von Materialien, insbesondere flüssigen, zähflüssigen oder eventuell weitgehend festen Materialien, welche sich während des Betriebs innerhalb der Ofenwanne befinden können. Neben der Leitfähigkeit dieses Materials nimmt auch die Dicke einer solchen Beschickung der Ofenwanne Ξinfluss auf die Maximal- Distanz. Für den Fachmann ist diese Maximal-Distanz, aufgrund der Erfahrung sowie der vorgegebenen Arbeitsparameter einfach ermittelbar. Gleichmässige Plasmaerzeugung bedeutet also vorzugsweise einen konstanten Energie-/Stromfluss gemäss den über die Regelung vorgegebenen Parametern.By separating the previously combined design of the electrical supply line and the resistant one, the invention offers Shielding the furnace structure against the effects of combustion, a number of advantages. By lining the furnace trough with a more suitable, thermally and chemically more resistant lining material, the service life of the rotary hearth furnace is significantly extended, since the lining material does not have to be used for the transmission of the electrical current. The use of electrodes, which are sealed by the lining material, on the one hand results in a safe current supply and improved control engineering aspects. It is important for the arrangement of the electrodes in the lining that an even current flow is guaranteed under the intended operating conditions. This means that despite the selective supply of electrical energy, largely homogeneous arc plasma generation in the furnace trough is achieved when the rotary hearth furnace rotates. The electrodes should therefore be arranged on the base surface at a predetermined distance from one another so that an interruption of the plasma torch arc can be ruled out. This maximum distance is dependent on electrical parameters such as voltage, current, the distance to the plasma electrode and the conductivity of materials, in particular liquid, viscous or possibly largely solid materials, which may be located in the furnace pan during operation. In addition to the conductivity of this material, the thickness of such a loading of the furnace trough also influences the maximum distance. This maximum distance can easily be determined for the person skilled in the art on the basis of experience and the specified working parameters. Uniform plasma generation therefore preferably means a constant energy / current flow according to the parameters specified by the control.

Vorzugsweise sind mindestens 60 Elektroden pro m2 Fläche des Ofenbodens angeordnet. Diese Anzahl der Elektroden ist jeweils auch abhängig von der Ofengeometrie, den Dimensionen der Elektroden, der Plasmabrennerleistung sowie dem zu verarbeitenden Abfallspektrum. Beispielsweise müssen bei Elektroden mit geringem Querschnitt mehr Elektroden eingesetzt werden.At least 60 electrodes are preferably arranged per m 2 of area of the furnace floor. This number of electrodes is each also depending on the furnace geometry, the dimensions of the electrodes, the plasma torch output and the waste spectrum to be processed. For example, more electrodes must be used for electrodes with a small cross-section.

Bevorzugt werden in dem erfindungsgemässen Drehherd-Ofen Elektroden eingesetzt, welche aus Stahl oder Cu-Legierungen bestehen. Derartige Elektroden weisen mehrere Vorteile auf. Einerseits besitzen die Materialien dieser Elektroden eine sehr gute elektrische Leitfähigkeit, so dass die Grδsse der Elektroden kleiner gewählt werden kann und die angelegten elektrischen Parameter, vor allem die Spannung niedriger gehalten werden kann. Andererseits sind die Elektroden getrennt von der Ausmauerung der Ofenwanne herstellbar und austauschbar, wodurch ein weiterer Kostenvorteil bei Herstellung und Unterhalt erzielbar ist.Electrodes which consist of steel or Cu alloys are preferably used in the rotary hearth furnace according to the invention. Such electrodes have several advantages. On the one hand, the materials of these electrodes have very good electrical conductivity, so that the size of the electrodes can be chosen to be smaller and the applied electrical parameters, especially the voltage, can be kept lower. On the other hand, the electrodes can be produced and exchanged separately from the lining of the furnace trough, whereby a further cost advantage in production and maintenance can be achieved.

Bevorzugt weisen die Elektroden im Querschnitt eine Abmessung zwischen 5 und 60mm, bevorzugt zwischen 10 und 50 mm auf. Die Länge der Elektroden beträgt zwischen 250 und 800 mm vorzugsweise zwischen 300 und 700 mm, oder wird in Abhängigkeit der erforderlichen Bodenausmauerungsdicke bestimmt. Bei der Wahl der Elektroden wird vorteilhaft eine einheitliche Grosse des Querschnitts gewählt, damit eine einfache Herstellung der Ausmauerung des Ofenbodens möglich ist. Aufgrund der notwendigen Neigung des Ofenbodens hin zu der im Zentrum, d.h. in der Rotationsachse angeordneten Abgussöffnung kann die erforderliche Länge der eingesetzten Elektroden in Abhängigkeit vom Abstand zur Abgussöffnung variieren.The cross section of the electrodes preferably has a dimension between 5 and 60 mm, preferably between 10 and 50 mm. The length of the electrodes is between 250 and 800 mm, preferably between 300 and 700 mm, or is determined depending on the required floor lining thickness. When choosing the electrodes, a uniform size of the cross section is advantageously chosen, so that a simple production of the lining of the furnace floor is possible. Due to the necessary inclination of the furnace floor towards that in the center, i.e. The required length of the electrodes used can vary depending on the distance to the pour opening in the pour opening arranged in the axis of rotation.

Vorteilhaft ist das Ausmauerungsmaterial für die Ofenwanne aus den im Ofenbau üblicherweise eingesetzten, widerstandfähigen Materialien ausgewählt. Beispielhafte Materialien sind Vergussmassen, Stampfmassen, gegossene oder gepresste Formsteine, insbe- sondere aus Korund, Chromkorund und/oder hochtonerdehaltige Mischungen. Vorstellbar sind auch Kombinationen aus diesen verschiedenen Materialien. Die Auswahl dieser Ausmauerungs- bzw. Refrakturmaterialien kann weitgehend auf Erfordernisse im Hinblick auf Standzeiten ausgerichtet werden, ohne durch Anforderungen für die Stromführung wesentlich eingeschränkt zu werden. Ebenfalls vorteilhaft ist die Abgussssδffnung als zentrale Öffnung in einem einstückigen Block (Abgussstein) eines Ausmauerungsmaterials ausgeführt. Es wird dadurch sichergestellt, dass durch das ausfliessende Schmelzgut keine Beschädigung der Ofenstruktur im Bereich der Abgusssöffnung eintreten kann. Die bauliche Trennung des Abgussteins vom restlichen Ofenboden erleichtert die Herstellung bzw. Wartung der Ofenwanne. Eine Erweiterung der Abgussöffnung durch Materialerrosion kann durch die Wahl eines entsprechenden Auskleidungsmaterials reduziert oder sogar vermieden werden.The lining material for the furnace trough is advantageously selected from the resistant materials usually used in furnace construction. Exemplary materials are casting compounds, ramming compounds, cast or pressed shaped blocks, in particular special of corundum, chromium corundum and / or mixtures containing high alumina. Combinations of these different materials are also conceivable. The selection of these masonry or refractory materials can largely be geared to requirements with regard to service life, without being significantly restricted by requirements for the power supply. The pouring opening is likewise advantageously designed as a central opening in a one-piece block (pouring stone) of a lining material. This ensures that the melting material flowing out cannot damage the furnace structure in the region of the pouring opening. The structural separation of the cast stone from the rest of the furnace floor makes it easier to manufacture and maintain the furnace pan. An expansion of the pouring opening due to material erosion can be reduced or even avoided by choosing an appropriate lining material.

In einer weiteren Ausführungsform sind die Elektroden auf der Unterseite der Ofenboden-Ausmauerung elektrisch leitend mit der Ofenboden-Tragstruktur vorzugsweise aus Stahl verbunden. Die Ofenboden-Ausmauerung weist dabei vorzugsweise eine Schicht- Struktur auf. Diese enthält eine Schicht des Ausmauerungsmaterials auf der Innenseite, d.h. der einem Reaktionsraum zugewandten Seite, und mindestens eine Stabilierungs- bzw. Isolationsschicht. Die Stabilierungs- bzw. Isolationsschicht ruht auf der Ofenboden-Tragstruktur. Diese Ofenboden-Tragstruktur ist elektrisch leitend ausgebildet und ist mittels mehreren Stromabnehmerbürsten an den elektrischen Stromkreis angeschlossen. Besonders gute Stabilitätseigenschaften ergeben sich wenn die Elektroden unmittelbar mit dieser Ofenboden-Tragstruktur formschlüssig verbunden sind. Die Elektroden sind mit ihrer Längsachse vorzugsweise etwas geneigt gegenüber der Oberfläche der Ofenboden-Tragstruktur angeordnet . Diese Anordnung vermeidet strukturelle Schwachstellen im Übergangsbereich zwischen der Elektrode und dem umgebenden Aus- mauerungsmaterial .In a further embodiment, the electrodes on the underside of the furnace floor lining are electrically conductively connected to the furnace floor support structure, preferably made of steel. The furnace floor lining preferably has a layer structure. This contains a layer of the lining material on the inside, ie the side facing a reaction chamber, and at least one stabilization or insulation layer. The stabilization or insulation layer rests on the furnace floor support structure. This furnace floor support structure is designed to be electrically conductive and is connected to the electrical circuit by means of several current collector brushes. Particularly good stability properties result if the electrodes are directly connected to this furnace floor support structure in a form-fitting manner. The electrodes are preferably arranged with their longitudinal axis slightly inclined with respect to the surface of the furnace floor support structure. This arrangement avoids structural weak points in the transition area between the electrode and the surrounding lining material.

Aufgrund der Neigung des Ofenbodens und der vorzugsweisen horizontalen Ofenboden-Tragstruktur weist die Kontaktfläche der Elektrode an der Grenzfläche zur Tragstruktur einen ovalen Querschnitt auf .Due to the inclination of the furnace floor and the preferably horizontal furnace floor support structure, the contact surface of the electrode at the interface with the support structure has an oval cross section.

Im folgenden wird die Erfindung anhand der Figuren näher ausgeführt . Es zeigenThe invention is explained in more detail below with reference to the figures. Show it

Figur 1 einen Querschnitt des Drehherd-Ofens, und1 shows a cross section of the rotary hearth furnace, and

Figur 2 eine Aufsicht auf den Ofenboden.Figure 2 is a plan view of the furnace floor.

Eine vereinfachte Darstellung eines erfindungsgemässen Ofens 1 gibt Figur 1 wieder. Der Ofen 1 umfasst die Ofenwanne 2 sowie eine Ofenboden-Tragstruktur 9 für die Ofenwanne 2. Die Ofenwanne enthält eine Stützstruktur 8 für die Ofenwand-Ausmauerung 4, Stabilisierungs- bzw. Isolationsstrukturen 10, 11, 12 sowie einen Abgussstein 13 mit der zentral angeordneten, d.h. mit der Rotationsachse R zusammenfallenden Abgussöffnung 6. Die Ofenwand- 4 und die Ofenboden-Ausmauerung 3 werden von den Stabilisierungs- bzw. Isolationsschichten 10, 11, 12 getragen. In der Ofenboden-Ausmauerung 3 sind auf vier konzentrisch um die Abgussöffnung 6 angeordneten Kreisen die Elektroden 7 zur Stromführung für die Plasmalichtbogen-Erzeugung angeordnet. Die Elektroden treten neben der Ausmauerung 3 auch durch die Stabilisierungs- bzw. Isolationsschicht 10, 11, 12 hindurch und ste- hen mit der Ofenboden-Tragstruktur 9 in elektrischem Kontakt. Die Stromabnehmerbürsten 14 sind in Figur 1 angedeutet.FIG. 1 shows a simplified illustration of an oven 1 according to the invention. The furnace 1 comprises the furnace trough 2 and a furnace floor support structure 9 for the furnace trough 2. The furnace trough contains a support structure 8 for the furnace wall lining 4, stabilization or insulation structures 10, 11, 12 and a casting stone 13 with the centrally arranged, that is, the pouring opening 6 coinciding with the axis of rotation R. The furnace wall 4 and the furnace floor lining 3 are supported by the stabilization or insulation layers 10, 11, 12. In the furnace floor brick lining 3, the electrodes 7 for current conduction for the plasma arc generation are arranged on four circles arranged concentrically around the pouring opening 6. In addition to the lining 3, the electrodes also pass through the stabilization or insulation layer 10, 11, 12 and hen with the furnace floor support structure 9 in electrical contact. The current collector brushes 14 are indicated in FIG. 1.

Die Ofenboden-Tragstruktur 9 weist ein nach oben offenes, U- förmiges Querschnittprofil auf, so dass die Stützstruktur 8 um- fasst wird. Auf der Umfangseite der Ofenboden-Tragstruktur 9 wird durch die Stromabnehmerbürsten 14, deren Halterungen 15 und die Kabel 16 die elektrische Verbindung zum Schliessen des Stromkreises für die Plasmaerzeugung hergestellt. Mittels Antriebseinheiten 20 wird der Drehherd-Ofen in Rotation versetzt. D^ie Antriebseinheiten 20 wirken auf einen Zahnkranz 19, welcher an einer Lagerhaiterung 18 mit der Ofenboden-Tragstruktur 9 der Ofenwanne 2 befestigt ist. Die Lagerhalterung 18 stützt sich wiederum auf einem ortsfesten Lager 17 ab. Durch die Anpassung der Rotationsgeschwindigkeit des Ofens 1 wird während des Betriebs des Drehherd-Ofens eine in die Ofenwanne 2 eingebrachte Glasmasse, aufgrund der Zentrifugalkraft gegen die Ofenseitenwand 4 gedrückt. Für die Entleerung des Ofens wird die Rotationsgeschwindigkeit derart reduziert, dass die Ausflussmenge unter Berücksichtigung der vorhandenen Neigung des Ofenbodens 3 hin zur Abgusssöffnung 6 fliesst.The furnace floor support structure 9 has a U-shaped cross-sectional profile that is open at the top, so that the support structure 8 is encompassed. On the circumferential side of the furnace floor support structure 9, the current collector brushes 14, their holders 15 and the cables 16 provide the electrical connection for closing the circuit for the plasma generation. The rotary hearth furnace is set in rotation by means of drive units 20. D ^ ie drive units 20 acting on a toothed rim 19, which is attached to a Lagerhaiterung 18 with the furnace bottom support structure 9 of the lower shell. 2 The bearing bracket 18 is in turn supported on a stationary bearing 17. By adjusting the rotational speed of the furnace 1, a glass mass introduced into the furnace trough 2 is pressed against the furnace side wall 4 due to the centrifugal force during the operation of the rotary hearth furnace. For the emptying of the furnace, the rotational speed is reduced in such a way that the outflow quantity flows towards the pouring opening 6, taking into account the existing inclination of the furnace bottom 3.

In Figur 2 ist eine spezifische Anordnung für die Elektroden 7 wiedergegeben. Jeweils je 30 Elektroden 7 sind auf vier, unterschiedlich grossen Kreisen konzentrisch um die Abgussöffnung 6 angeordnet. Die Elektroden 7 aus Stahl St 37-2 besitzen einen Durchmesser von 15 mm und weisen eine Länge zwischen 411 und 436 mm auf. Die Längenunterschiede resultieren aufgrund der Neigung des Ofenbodens 3 und der waagrecht angeordneten Ofenboden- Tragstruktur 9, die jeweils längeren Elektroden 7 sind dabei auf den Kreisen mit dem jeweils grösseren Umfang angeordnet. Gemäss dem Ausführungsbeispiel betragen die Unterschiede der Durchmesser jeweils 200 mm, wobei der kleinste Kreisdurchmesser 1085 mm beträgt . Der innere Durchmesser der Ofenseitenwand 4 beträgt 2041 mm. Die Abgussöffnung 6 besitzt einen Durchmesser von 80 mm, der Abgussstein 13 einen äusseren Durchmesser am Ofenboden 3 von 460 mm oder 640 mm.A specific arrangement for the electrodes 7 is shown in FIG. 30 electrodes 7 each are arranged concentrically around the pouring opening 6 on four circles of different sizes. The electrodes 7 made of steel St 37-2 have a diameter of 15 mm and a length between 411 and 436 mm. The length differences result due to the inclination of the furnace floor 3 and the horizontally arranged furnace floor support structure 9, the longer electrodes 7 are arranged on the circles with the larger circumference. According to the exemplary embodiment, the differences in the diameters are in each case 200 mm, the smallest circle diameter being 1085 mm is. The inner diameter of the furnace side wall 4 is 2041 mm. The casting opening 6 has a diameter of 80 mm, the casting stone 13 has an outer diameter on the furnace bottom 3 of 460 mm or 640 mm.

Die Abfolge der einzelnen Bestandteile des Drehherd-Ofens 1 gestaltet sich, bei einer Vorgehensweise von aussen nach innen wie folgt: Die elektrische Verbindung durch das Kabel 16, die Halte- rung 15 und die Stromabnehmerbürsten 14 liegen in der Draufsicht oberhalb der Lagerstruktur 18. Die Stromabnehmerbürsten 14, welche beispielsweise aus einer Cu-Legierung bestehen, liegen am Aussenumfang der Ofenboden- ragstruktur 9 an. In Richtung Ofenzentrum folgt die Stützstruktur 8 sowie Auskleidung 5 der Ofenwanne 2. Die Auskleidung 5 besteht aus Vergussmassen, Stampfmassen, gegossene oder gepresste Formsteine, insbesondere aus Korund, Chromkorund und/oder hochtonerdehaltige Mischungen. Deutlich erkennbar in der Draufsicht ist die radial versetzte Anordnung der Elektroden 7 in Bezug auf die Elektroden in den benachbarten Anordnungskreisen. Innerhalb eines solchen Kreis sind die Elektroden 7 jeweils durch einen Winkel AI von 12° getrennt angeordnet. Der minimale Winkel A2 zwischen zwei, auf radial nach aussen aufeinanderfolgenden Anordnungskreisen befindlichen Elektroden 7 beträgt 6°. Die Anordnung der Elektroden 7 sowie deren Dimensionierung sind für eine Stromstärke eines Plasmabrenners mit einer maximalen Leistung von 1,2 MW, resp. einem maximalen Betriebsstrom von 2000 A ausgelegt.The sequence of the individual components of the rotary hearth furnace 1, with a procedure from the outside in, is as follows: The electrical connection through the cable 16, the holder 15 and the current collector brushes 14 are above the bearing structure 18 in the plan view Current collector brushes 14, which consist for example of a Cu alloy, rest on the outer circumference of the furnace base support structure 9. The support structure 8 and lining 5 of the furnace trough 2 follow in the direction of the furnace center. The lining 5 consists of casting compounds, ramming compounds, cast or pressed shaped blocks, in particular of corundum, chromium corundum and / or mixtures containing high alumina. The radially offset arrangement of the electrodes 7 in relation to the electrodes in the adjacent arrangement circles is clearly recognizable in the plan view. Within such a circle, the electrodes 7 are each separated by an angle Al of 12 °. The minimum angle A2 between two electrodes 7 located on radially successive arrangement circles is 6 °. The arrangement of the electrodes 7 and their dimensions are for a current of a plasma torch with a maximum output of 1.2 MW, respectively. designed for a maximum operating current of 2000 A.

Für geänderte Betriebsbedingungen ist die Dimensionierung sowie die Anordnung der Elektroden entsprechend anzupassen. The dimensioning and arrangement of the electrodes must be adjusted accordingly for changed operating conditions.

Claims

Patentansprüche claims 1. Drehherd-Ofen (1) mit einem Plasmabrenner als Energiequelle enthaltend, eine Ofenwanne (2) mit Ofenboden (3) und Ofenseitenwand (4) , wobei die Ofenwanne (3) auf einer Innenseite ein thermisch und chemisch resistentes Ausmauerungsmaterial (5) aufweist, und ein Abgussöffnung (13) , dadurch gekennzeichnet, dass durch das Ausmauerungsmaterial (5) des Ofenbodens (3) eine Mehrzahl von Elektroden (7) durchgeführt wird.1. Rotary hearth furnace (1) with a plasma torch as an energy source containing a furnace pan (2) with furnace bottom (3) and furnace side wall (4), the furnace pan (3) having a thermally and chemically resistant lining material (5) on an inside , and a pouring opening (13), characterized in that a plurality of electrodes (7) is passed through the lining material (5) of the furnace base (3). 2. Drehherd-Ofen (1) nach Anspruch 1, dadurch gekennzeichnet, dass die Elektroden derart angeordnet sind, dass ein sicherer Stromfluss gewährleistet ist.2. rotary hearth furnace (1) according to claim 1, characterized in that the electrodes are arranged such that a safe current flow is ensured. 3. Drehherd-Ofen (1) nach Anspruch 1, dadurch gekennzeichnet, dass im Bereich der Plasma-Erzeugung mindestens 60 Elektroden (7) pro m2 Fläche des Ofenbodens (3) angeordnet sind.3. Rotary hearth furnace (1) according to claim 1, characterized in that at least 60 electrodes (7) per m 2 area of the furnace floor (3) are arranged in the region of the plasma generation. 4. Drehherd-Ofen (1) nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Elektroden (7) aus Stahl oder Cu- Legierungen bestehen.4. rotary hearth furnace (1) according to claim 1 or 2, characterized in that the electrodes (7) consist of steel or copper alloys. 5. Drehherd-Ofen (1) nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Elektroden (7) eine Abmessung im Querschnitt zwischen 5 und 60 mm, vorzugsweise zwischen 10 und 50 mm und in der Länge zwischen 250 und 800 mm bevorzugt zwischen 300 und 700 mm aufweisen.5. rotary hearth furnace (1) according to any one of the preceding claims, characterized in that the electrodes (7) have a dimension in cross section between 5 and 60 mm, preferably between 10 and 50 mm and in length between 250 and 800 mm, preferably between 300 and 700 mm. 6. Drehherd-Ofen (1) nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Ausmauerungsmaterial (5) ausgewählt ist der Gruppe bestehend aus Vergussmasse, Stampfmasse, aus gegossenen oder gepressten Formsteinen, insbesondere aus Korund, Chromkorund und/oder hochtonerde- haltige Mischungen und Kombinationen davon.6. rotary hearth furnace (1) according to any one of the preceding claims, characterized in that the lining material (5) is selected from the group consisting of casting compound, ramming compound, from cast or pressed molded blocks, in particular from corundum, chromium corundum and / or mixtures containing high alumina and combinations thereof. Drehherd-Ofen (1) nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Elektroden (7) mit einer Ofenboden-Tragstruktur (9) unterhalb der Ofenboden- Ausmauerung (3) elektrisch leitend verbunden sind. Rotary hearth furnace (1) according to one of the preceding claims, characterized in that the electrodes (7) are electrically conductively connected to a furnace base support structure (9) below the furnace base lining (3).
PCT/EP2004/007283 2003-11-18 2004-07-03 Rotating hearth furnace for waste with a hazard potential Ceased WO2005052448A1 (en)

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EP03405818A EP1533567A1 (en) 2003-11-18 2003-11-18 Furnace with rotating hearth for dangerous wastes

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CN106734166A (en) * 2016-12-23 2017-05-31 核工业西南物理研究院 The device of Low Temperature Plasma Treating persistent organism contaminated soil
CN108178472A (en) * 2018-02-24 2018-06-19 航天慧能（江苏）环境工程有限公司 A kind of greasy dirt plasma handling system and method

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