EP0109356A2 - Elektrode für Hochtemperaturverfahren und ihre Anwendung - Google Patents

Elektrode für Hochtemperaturverfahren und ihre Anwendung Download PDF

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Publication number
EP0109356A2
EP0109356A2 EP83810487A EP83810487A EP0109356A2 EP 0109356 A2 EP0109356 A2 EP 0109356A2 EP 83810487 A EP83810487 A EP 83810487A EP 83810487 A EP83810487 A EP 83810487A EP 0109356 A2 EP0109356 A2 EP 0109356A2
Authority
EP
European Patent Office
Prior art keywords
electrode
heat
cooling
section
heat pipes
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.)
Withdrawn
Application number
EP83810487A
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English (en)
French (fr)
Other versions
EP0109356A3 (de
Inventor
Dieter Dr. Zöllner
Inge Dr. Lauterbach-Dammler
Thomas Dr. Taube
Herbert Prof. Dr. Wilhelmi
Kurt Prof. Dr. Kegel
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.)
Arc Technologies Systems Ltd
Original Assignee
Arc Technologies Systems Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Arc Technologies Systems Ltd filed Critical Arc Technologies Systems Ltd
Publication of EP0109356A2 publication Critical patent/EP0109356A2/de
Publication of EP0109356A3 publication Critical patent/EP0109356A3/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • H05B7/02—Details
    • H05B7/12—Arrangements for cooling, sealing or protecting electrodes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B7/00—Heating by electric discharge
    • H05B7/02—Details
    • H05B7/10—Mountings, supports, terminals or arrangements for feeding or guiding electrodes
    • H05B7/101—Mountings, supports or terminals at head of electrode, i.e. at the end remote from the arc

Definitions

  • the invention relates to electrodes for high-temperature processes, comprising an active section and a cooling section extending into the furnace interior, and to their use.
  • Electrodes which comprise an active section and a separate cooled section have been known for some time.
  • electrodes comprising a metallic, liquid-cooled upper section and a lower section of consumable material, preferably graphite, which is attached to the upper section, are generally referred to as combination electrodes.
  • the European patent application No. 80 106 581.4 describes a combination electrode of this type. Having been employed successfully, these electrodes are replacing conventional electrodes of graphite columns to an increasing extent.
  • electrodes When employed in industrial furnaces, particularly electric arc furnaces, electrodes are exposed to high stress. In addition to the mechanical stress caused by dipping the electrode in molten metal, splashes of molten metal and slag hitting parts of the electrode which are not immersed, disturbances as a result of undesired arc migration or the like, problems of heat stress are of special importance.
  • the active sections of electrodes are frequently operated at high working temperatures, particularly in arc furnace operation, which means that the section attached to the active section also has to take up considerable heat quantities.-However, this section frequently consists of relatively low-melting material, e.g. copper. As a result, cooling and, if required, heat insulation will be necessary.
  • Cooling of the upper section of combination electrodes is frequently achieved via cooling agent chambers with supply and return ducts, e.g. of the type described in the European application No. 80 106 579.8.
  • the introduction of the most usual cooling'medium, namely water, into the cooling cycle of the electrode, at least part of which may be located in the interior of the furnace, may cause difficulties in practical operation, if the metal shaft and thus the cooling ducts are mechanically damaged or if the coolant supply is interrupted.
  • US-PS 4,287,045 describes a cooled electrode intended for use in molten metal baths.
  • This electrode which is inserted from the side, comprises a metal section reaching the molten metal which has a direct power supply.
  • This metal section incorporates a heat pipe.
  • this electrode has a number of drawbacks. They result from the direct introduction of the heat pipe into the partially melting metal section over a considerable distance, lack of heat dissipation depending on heat direction, and the easy “drying out” of the heat pipe, if the heat hitting the metal section becomes too high. Due to its susceptibility, this electrode is firmly built into the furnace wall.
  • the object of the present invention is, therefore, to create electrodes for high-temperature processes which permit safe operation even if operating conditions change, while the protection of the cooling section attached to the active section is guaranteed in an efficient and flexible manner.
  • the cooling section of this electrode comprises at least one heat pipe with a polytropic heat exchanger in the furnace interior in which heat is dissipated by means of an additional cooling system.
  • the cooling system of the cooling section comprises a heat pipe within the cooling section as well as an additional cooling system which may comprise further heat pipes or a gas cooling cycle or a fluid cooling cycle, or a combination of the two.
  • the present invention is based on the realization that an effective protection of the section attached to the active section can be obtained, if two conventional cooling systems are combined in a suitable manner. Surprisingly, the results are a high flexibility, great operational safety, and a highly favourable energy supply.
  • the cooling section of the electrode may comprise a system of heat pipes in two zones, frequently, however, in three or four zones. It is especially advantageous, if there is a heat - exchange between the condensation zone of the heat pipes located further down and the evaporation zone of the neighbouring heat pipes.
  • Such an arrangement which may be achieved in various ways, guarantees the predetermined heat transfer from one heat pipe to the following, since the heat released as a result of condensation is used for the evaporation of the cooling medium of the subsequent heat pipe.
  • Such an assembly may be achieved in various ways.
  • the contacting condensation and evaporation zones of the two heat pipes may comprise extended contact surfaces in order to obtain a heat exchange area that is as large as possible.
  • Axially parallel heat pipes may include a kind of sleeve attached to one heat pipe into which the second pipe is introduced in their evaporation and/or condensation areas, thereby providing large surfaces.
  • the heat pipes in the different zones are placed one on top of the other, with the upper heat pipe surrounding the lower portion of the subsequen lower heat pipe in a "hat-like" manner.
  • heat pipe selected within the framework of the invention is well-known.
  • the transfer of heat in heat pipes is the result of a phase change of the cooling agent the circulation of which is either favoured or obtained (e.g. in a capillary system or wick) by the surface tension forces of the fluid.
  • heat pipe shall also include heat pipes based on the principle of gravitation, i.e. so-called “gravitational heat pipes", which have no wick insert.
  • the assembly of heat pipes in two, but frequently more zones also permits the use of different cooling media in the heat pipes of these zones.
  • the cooling agent used in the lowest zone i.e. the zone adjacent to the active section, may be e.g. sodium, caesium, lithium, or even mercury.
  • These cooling agents may also be used in the heat pipes of the subsequent zones, they may, however, be replaced by other conventional cooling agents for the medium temperature range.
  • the cooling section comprises a system of axially parallel, radially arranged heat pipes, which, in turn,may be distributed over a plurality of zones along the electrode axis.
  • the axially parallel and simultaneously radial assembly of the heat pipes makes sure that the heat is dissipated in the direction of the electrode axis as well as from the radial region of the electrode.
  • the heat is admitted from various directions: on the one hand axially from the glowing tip of the active section in the front portion where the electric arc comes from.
  • the electrode also takes up heat in the laterial regions as a result of the furnace atmosphere, side oxidation or the like.
  • the temperatures in the axial and radial regions of the section to be cooled may, however, considerably vary over its entire length.
  • the radially arranged heat pipes also guarantee the safe operation of the axially parallel heat pipes, since their cooling agent circulation would be disturbed in case of extreme stress due to lateral heat, with the returning fluid evaporating prematurely.
  • the cooling section of the electrode comprises at least one axially parallel heat pipe in combination with an additional cooling system, wich dissipates radial heat.
  • this additional cooling system may consist in a fluid cooling cycle, a gas cooling cycle or in radially arranged heat pipes or in a combination thereof.
  • This additional cooling system may also have heat-insulating properties and serve as heat insulation.
  • cooling section of the electrode comprises a system of axially parallel and radially arranged heat pipes
  • this arrangement will mutually guarantee the flawless operation of the various heat pipes.
  • metallic fluids or the like it will be possible to prevent the introduction of undesired cooling agents, e.g. water, into the electric arc furnace, into which the cooled shaft of the electrode is also inserted.
  • the other preferred alternative of the invention i.e. a combination of axially parallel heat pipes with an additional fluid or gas cooling cycle in the radial zone, also offers special advantages During ordinary operation, cooling of the electrode may e.g.
  • the heat pipes may be carried out by the heat pipes only, while in case of special stress a conventional fluid or gas cooling cycle with supply and return ducts for the cooling medium will be added.
  • fluid cooling or gas cooling
  • the terms "fluid cooling” or "gas cooling” are used to describe such conventional systems where the circulation of the cooling system is achieved by means of a pump, while the corresponding circulation in the closed system of the heat pipe is induced by surface tension forces or gravitation.
  • the heat pipe(s) may be cooled by a predetermined gas flow in order to dissipate heat in a controlled manner.
  • the electrode may be designed in such a way that the cooling section comprises heat pipes the evaporation zone of which is located in the axial threshold region near the active section, and heat pipes the evaporation zone of which is located in the lateral region of the cooling section.
  • the radially arranged heat pipes which are intended for the dissipation of heat from the radial regions of the cooling section, may be straight or bent.
  • the latter type has proved especially useful for the dissipation of heat from the final portion of the electrode, since there it is no longer necessary to "distinguish" between axially parallel and radially arranged heat pipes.
  • the heat pipes in the condensation and/or evaporation zones may have a flat design or end in a plurality of limbs in a conventional manner. This ensures that the heat is absorbed over large areas in an especially effective manner.
  • the heat pipes or the combination of heat pipes and an additional fluid or gas cooling cycle may already constitute the cooling section proper of the electrode.
  • the heat pipes are connected by spacers or in marginal zones they may, occasionally, be communicatin g ly connected.
  • This kind of assembly of the heat pipes and, if required, of the supply and return ducts of the additional fluid cooling cycle (gas cooling cycle) facilitates the attachment of the active portion in the lower section and, as a rule, improves heat dissipation in the upper end section of the electrode.
  • the external heat insulation layers will have a better support and/or mounting.
  • each of these combinations may either constitute the cooling section proper or it may be combined or embedded in a shaft. At any rate, it is preferred that the cooling section and/or the heat pipes constitute(s) the current supply to the active section.
  • the cooling systems of the cooling section may be separated from the active section by a high-temperature resistant plate.
  • This plate may e.g. consist of high-melting carbides and/or nitrides, e.g. of graphite impregnated with silicon, circon oxide, or the like, which may provide a certain additional "buffer" against mechanical and thermal stress.
  • a high-temperature resistant plate that is punched. This is especially important, if gas is passed through the active section(s) of the electrode. The passage of gas may be necessary for a number of reasons.
  • the gas may be supplied to increase the efficiency of the electrode operation, to reduce side oxidation , or the like.
  • inert gases such as argon
  • reactive gases such as hydrocarbon components or plasma flows
  • the heat pipes of the respective zone may be mounted to the plate or they may pass the plate like a punched disk.
  • the cooling section comprising the cooling systems of the electrode in accordance with the invention is connected to the active section by means of a nipple.
  • This nipple may consist of graphite or conductive metal. If high-temperature resistant plates are employed, they may have connection pieces for the attachment of the active section which are e.g. designed like a nipple.
  • the heat pipes or the cooling combination of the cooling section are (is) protected by an additional, external, high-temperature resistant heat insulation.
  • This heat insulation may cover the entire area of the cooling section or,depending on the type of application, it may cover only parts thereof.
  • the "heat insulation”, which also constitutes a “thermal shield” against an undesired lateral attack of the electric arc on the cooling section, e.g. when drawing the arc between cooling section and furnace, may consist of different materials.
  • "heat insulations" of coated graphite and/or compound materials which comprise carbon and ceramic shares are especially preferred. Ceramic materials may, however, also be used.
  • the heat insulation consists of removable mouldings.
  • the most expedient solution is to leave an air gap between cooling section and thermal insulation. It is, however, also possible to put the mouldings directly on the cooling section and/or to mount them by means of guides, e.g. dovetail guides or in another manner (e.g. by means of internal pressing rings).
  • the cooling systems may also be directly embedded in the heat insulation material.
  • a preferred embodiment of the electrode according to the invention concerns the active graphite section which is attached to the cooling section.
  • ceramic, electrically conductive materials such as zirconium oxide, silicon carbide, tantalum carbide, or the like, may also be used as active sections.
  • the cooling section and the active section of the electrode can be moved towards each other.
  • the cooling section constitutes a jacket system through wnicn tne active portion is fed.
  • the current supply to the electrode preferable passes to the cooling section, and from the cooling section via contact points to the active section.
  • the points of contact may e.g. consist of graphite.
  • the jacket system comprises e.g. a combination of axially arranged heat pipes with a heat insulation on the outside. It is, however, also possible that the jacket system incorporates additional, radially arranged heat pipes and/or cooling systems in which the cooling medium is transferred by pumping.
  • FIG. 1 is the schematic illustration of one embodiment of an electrode according to the invention in which an axially arranged heat pipe 5 is combined with radially arranged heat pipes 6 with a fluid cooling cycle comprising a supply duct 10 and a return duct 4.
  • the electrode is held by a fixing device 1, which also provides the current supply 12.
  • the electrode is protected by a high-temperature resistant heat insulation 2, which rests snugly on the outside of the cooling section 3.
  • the heat pipes 5 and 6 are separated from the fluid cooling cycle located in the upper portion of the cooling section by a high-temperature resistant plate 9.
  • the connection between the cooling section 3 and the active section 7 is obtained by means of a nipple 11, which may consist e.g. 'of graphite, a highly conductive material or a metal alloy.
  • the electrode is introduced into the furnace roof 8 in such a manner that part of the cooling section 3 remains within the interior of the furnace.
  • the electrode may be adjusted for operation by means of the support 1.
  • the electrode shown in Figure 1 is suited for the production of steel in electric arc furnaces, with an active section 7 of e.g. graphite.
  • the electrode illustrated in Figure 2 has a plurality of active sections 7, which are each connected to the cooling section 3 of the electrode by means of a nipple 11.
  • This electrode is designed in such a way that gas may be introduced through a central duct into the zone of active sections 7. Instead of nitrogen, which has already been indicated, other gases such as air, argon, reactive gases, or the like may, naturally, also be introduced.
  • the axially and radially arranged heat pipes 5, 6 are again kept at a distance by means of plates 9 mounted at different heights of the cooling section.
  • the heat insulation 2 e.g. of coated graphite and/or ceramic materials or graphite containing ceramic shares, comprises individual, removable mouldings 2, which make it easy to carry out repairs of the electrode.
  • the heat is transported to the upper portion of the cooling section 3 from where it is dissipated by a water cooling cycle.
  • the electrode may be moved in such a manner that the upper portion of the cooling section 9 with the water cooling cycle remains outside the furnace roof.
  • other cooling fluids may be used as well.
  • the electrode may e.g. be employed in plasma arc operations, but it may also be used for the production of materials in reduction furnaces.
  • the active sections 7 may also consist of conventional ceramic materials.
  • FIG. 3 also shows a portion of the cooling section 3 of a combination electrode according to the invention.
  • the cooling section comprises axially arranged heat pipes 5 as well as radially arranged heat pipes 6, which are located at varying heights of the electrode to ensure the dissipation of heat in the cooling section in a controlled manner.
  • Figure 4 illustrates radially arranged heat pipes of the cooling section 3, with a heat exchange between the condensation zone of the lower heat pipes and the evaporation zone of the adjacent heat pipes.
  • the upper heat pipes are put on the respective lower heat pipes in a hat-like manner.
  • the heat conveyed upwards in this manner may be dissipated through cooling ducts 10 not shown in greater detail.
  • This figures only shows the combination of heat pipe and heat insulation 2 according to the invention, with the heat insulation again comprising attachable mouldings.
  • Figures 5 and 6 show an embodiment of the upper part of the cooling section 3 of the electrode according to the invention, with the heat pipes ending in a type of ring. From there the heat is dissipated by a fluid cooling cycle, the the fluid cooling ducts covering the inner as well as the outer region of the heat pipe condensation zones. To improve heat transfer, the interspaces between the heat pipes 5, 6 are surrounded by a highly heat-conducting material.
  • Figures 7 and 8 illustrate another embodiment of the heat transfer from the heat pipes to a fluid cooling cycle located outside the furnace roof in the electrode. In their upper region, the heat pipes are bent in a "loop-type" manner to obtain a larger heat exchange area.
  • Figure 9 shows that the heat pipes 6 within the cooling section 3 end in a plurality of limbs.
  • FIG 10 illustrates a feed-through version of the electrode according to the invention whose active section 7 and cooling section 3 can be separately adjusted during furnace operation. Therefore, there is a separate support 1 for the cooling section 3 and there are further supports for the active section 7, which may consist of a number of carbon sections. The individual carbon sections may e.g. be connected by nipples.
  • the cooling section 3 will comprise axially arranged heat pipes 5 in combination with a heat insulation 2 made up by e.g. screwed-on graphite rings with a ceramic coating. With this type of electrode,the current is supplied also via support 1 to the cooling section 3. This has, however, not been specifically illustrated.
  • the current transfer from the cooling section 3 to the active section 7 may be obtained by one or several contacting points 14, which are schematically illustrated in the lower portion of the active section 7. If there are no contacting points, it may be advantageous to cover the internal zone of the cooling section 3 of the feed-through electrode with an electrically insulating layer 13.
  • the electrode according to the invention in the reductive production of materials in reduction furnaces.
  • these furnaces it may be used e.g. for the production of ferroalloys, but also for cleaning processes, e.g. in sublimation processes (e.g. yellow phosphorus) or the like.
  • the electrodes are, however, also especially suited for the production of steel in electric arc furnaces.
  • the additional introduction of gas is also included.
  • the gas supply may contribute to the protection of the electrodes, on the other it may enhance the efficiency of electrode operation, e.g.by stabilizing the electric arc, or the like.
  • the electric arc is first drawn in the usual manner, but is then supported by a plasma current, while, in addition, an alternating current superposition may occur at the same time.
  • the combination of electric arc plasma operation and heat pipe for the first time permits the almost complete utilization of the heat to be dissipated from the electrode. This may be achieved in various ways in the same process or in other processes, e.g. also in regenerative processes.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Furnace Details (AREA)
  • Discharge Heating (AREA)
EP83810487A 1982-11-12 1983-10-21 Elektrode für Hochtemperaturverfahren und ihre Anwendung Withdrawn EP0109356A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH660382 1982-11-12
CH6603/82 1982-11-12

Publications (2)

Publication Number Publication Date
EP0109356A2 true EP0109356A2 (de) 1984-05-23
EP0109356A3 EP0109356A3 (de) 1985-04-24

Family

ID=4312177

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83810487A Withdrawn EP0109356A3 (de) 1982-11-12 1983-10-21 Elektrode für Hochtemperaturverfahren und ihre Anwendung

Country Status (2)

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EP (1) EP0109356A3 (de)
JP (1) JPS59194392A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0135473A1 (de) * 1983-08-13 1985-03-27 Arc Technologies Systems, Ltd. Elektrodenvorrichtung für Lichtbogenöfen
EP0157104A1 (de) * 1984-02-24 1985-10-09 C. CONRADTY NÜRNBERG GmbH & Co. KG Verfahren und Vorrichtung zum Schmelzen und Erhitzen von Werkstoffen
EP0202352A1 (de) * 1985-05-22 1986-11-26 C. CONRADTY NÜRNBERG GmbH & Co. KG Plasmabrenner
CN103256705A (zh) * 2012-02-16 2013-08-21 朱杰 冷凝式径向热管锅炉
CN113932602A (zh) * 2021-09-02 2022-01-14 山东晶盾新材料科技有限公司 一种用于快速热压烧结的自动化连续生产装置
CN114071819A (zh) * 2022-01-18 2022-02-18 中国空气动力研究与发展中心超高速空气动力研究所 一种水冷可调节补偿热阴极装置
WO2024178630A1 (zh) * 2023-02-28 2024-09-06 宁德烯铖科技有限公司 石墨化炉和电池生产系统

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3375314A (en) * 1964-10-08 1968-03-26 Boeing Co Electrode for glass melting furnaces
US3605436A (en) * 1969-08-29 1971-09-20 Oscar Elbridge Gammill Jr Centrifugal absorption air conditioner
US3750745A (en) * 1970-07-06 1973-08-07 R Moore High heat flux heat pipe
DE2730884B2 (de) * 1977-07-08 1980-11-13 Korf-Stahl Ag, 7570 Baden-Baden Elektrode für Lichtbogenöfen mit einem flüssigkeitsgekühlten Mantel
DE2834838A1 (de) * 1978-08-09 1980-02-21 Daimler Benz Ag Waermeuebertragung nach dem prinzip des waermerohres

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0135473A1 (de) * 1983-08-13 1985-03-27 Arc Technologies Systems, Ltd. Elektrodenvorrichtung für Lichtbogenöfen
EP0157104A1 (de) * 1984-02-24 1985-10-09 C. CONRADTY NÜRNBERG GmbH & Co. KG Verfahren und Vorrichtung zum Schmelzen und Erhitzen von Werkstoffen
EP0202352A1 (de) * 1985-05-22 1986-11-26 C. CONRADTY NÜRNBERG GmbH & Co. KG Plasmabrenner
CN103256705A (zh) * 2012-02-16 2013-08-21 朱杰 冷凝式径向热管锅炉
CN103256705B (zh) * 2012-02-16 2015-04-08 朱杰 冷凝式径向热管锅炉
CN113932602A (zh) * 2021-09-02 2022-01-14 山东晶盾新材料科技有限公司 一种用于快速热压烧结的自动化连续生产装置
CN113932602B (zh) * 2021-09-02 2023-10-31 山东晶盾新材料科技有限公司 一种用于快速热压烧结的自动化连续生产装置
CN114071819A (zh) * 2022-01-18 2022-02-18 中国空气动力研究与发展中心超高速空气动力研究所 一种水冷可调节补偿热阴极装置
CN114071819B (zh) * 2022-01-18 2022-03-18 中国空气动力研究与发展中心超高速空气动力研究所 一种水冷可调节补偿热阴极装置
WO2024178630A1 (zh) * 2023-02-28 2024-09-06 宁德烯铖科技有限公司 石墨化炉和电池生产系统

Also Published As

Publication number Publication date
EP0109356A3 (de) 1985-04-24
JPS59194392A (ja) 1984-11-05

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Inventor name: LAUTERBACH-DAMMLER, INGE, DR.

Inventor name: WILHELMI, HERBERT, PROF. DR.

Inventor name: TAUBE, THOMAS, DR.

Inventor name: ZOELLNER, DIETER, DR.

Inventor name: KEGEL, KURT, PROF. DR.