EP0109356A2

EP0109356A2 - Electrode for high temperature processes and its use

Info

Publication number: EP0109356A2
Application number: EP83810487A
Authority: EP
Inventors: Dieter Dr. Zöllner; Inge Dr. Lauterbach-Dammler; Thomas Dr. Taube; Herbert Prof. Dr. Wilhelmi; Kurt Prof. Dr. Kegel
Original assignee: Arc Technologies Systems Ltd
Current assignee: Arc Technologies Systems Ltd
Priority date: 1982-11-12
Filing date: 1983-10-21
Publication date: 1984-05-23
Also published as: EP0109356A3; JPS59194392A

Abstract

Electrode for high-temperature processes, comprising an active section and a cooling section attached to it and extending into the furnace interior, said cooling section (3) comprising at least one heat pipe (5) with a polytropic heat exchanger in the furnace interior which has an additional cooling system (e.g. 6 in Fig. 1) forthe dissipation of heat. The additional cooling system may comprise further heat pipes, a gas and/or a fluid circulation system, with the cooling fluid being pumped, and/or a heat insulation.

The electrode is intended for use in high-temperature processes, particularly in the production of steel. It is characterized by a safe and flexible manoeuvrability.

Description

FIELD OF THE INVENTION

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.

BACKGROUND OF THE INVENTION

Electrodes which comprise an active section and a separate cooled section have been known for some time. Thus, 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.
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.
Another solution is offered by US-PS 4,145,564, in which a replaceable graphite section is connected to the lower end of a metal shaft. The protection of the metal shaft from the heat is provided by fire-proof ceramic rings placed on the metal shaft without compulsory cooling. However, experiments have shown that this solution is not really or not at all suited for a number of applications, since the thermal protection of the easily melting metal shaft is only insufficient.
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. In practical operation, 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.
Therefore, there is a constant demand for electrodes the design of which permits not only a wide range of applications but also a safe and energy-saving current supply to the active section, even if the individual areas are exposed to high temperatures and fluctuations in heat intensity as well as heat quantity.

OBJECT OF THE INVENTION

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.
This problem is solved by the creation of an electrode of the type mentioned at the beginning. 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.
Thus 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.
Among other considerations, 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.
According to one embodiment of the invention, 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. For example, 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. According to another embodiment, which may also be preferable within the framework of the invention, 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.
The term "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. However, the term "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. As a rule, 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.
According to a perferred embodiment of the invention, 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. In case of a combination electrode which is to be employed in the production of steel, 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. On the other hand 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. Within the framework of the invention it is, therefore, especially preferred, if 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. As mentioned earlier, 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.
An especially safe and flexible system is provided particularly by two preferred embodiments of the present invention: If the 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. By using 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. 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. Within the framework of the invention, 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. According to an advantageous embodiment of the invention, the heat pipe(s) may be cooled by a predetermined gas flow in order to dissipate heat in a controlled manner.
According to a suitable embodiment of the invention, 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.
In order to obtain optimum heat dissipation and/or heat absorption, 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. In this case the heat pipes are connected by spacers or in marginal zones they may, occasionally, be communicatin^gly 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. As a result of this flat connection of heat pipes in certain sections, e.g. by means of special sheet steel or intermediate layers or the like, the external heat insulation layers will have a better support and/or mounting.
No matter whether it is a combination of axially parallel and radially arranged heat pipes, or a combination of compulsory circulation cooling employing pumps with heat pipes, or a system of heat pipes with external heat insulation that is used, 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.
According to a preferred embodiment of the present invention 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. Depending on the application of the electrode it may be favourable to have 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. On the one hand it may be used to "observe" the behaviour of the active section, since any breakage or other changes would be reflected in a pressure drop. On the other hand, the gas may be supplied to increase the efficiency of the electrode operation, to reduce side oxidation , or the like. For this purpose inert gases, such as argon, as well as reactive gases, such as hydrocarbon components or plasma flows, are suitable for arc stabilization.
Incidentally, there may be a plurality of high-temperature resistant plates, e.g. for separating individual cooling zones of the cooling section. In this case the heat pipes of the respective zone may be mounted to the plate or they may pass the plate like a punched disk.
As a rule, 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.
If the electrode according to the invention is to be employed in steel production or for other purposes, it may be preferred that 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.
In case of electrodes which are intended for electric arc operations it is generally necessary to protect at least that part of the electrode which is adjacent to the active section and which remains in the furnace interior during operation.
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. In connection with the electrode according to the invention, "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.
Within the framework of the invention it is preferred that 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).
According to an alternative embodiment of the present invention, 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. Instead of graphite, ceramic, electrically conductive materials, such as zirconium oxide, silicon carbide, tantalum carbide, or the like, may also be used as active sections.
Finally, it is also possible and for certain applications within the framework of the invention preferred if the cooling section and the active section of the electrode can be moved towards each other. In this case 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.
Within the framework of the invention, 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.

BRIEF DESCRIPTION OF THE DRAWINGS

Further preferred embodiments of the electrode according to the invention are illustrated in the accompanying figures in which

Figure 1 is a vertical sectional view of an electrode according to the invention the cooling section of which incorporates a system of axially and radially arranged heat pipes in combination with a water cooling cycle.
Figures 2 are vertical sectional views of an electrode
and 3 according to the invention, with a system of axially and radially arranged heat pipes.
Figure 4 is a vertical sectional view of the cooling section of a combination electrode.
Figure 5 is a vertical sectional view of the upper final portion of the cooling section of an electrode according to the invention.
Figure 6 is a cross-sectional view of the portion of the cooling section shown in Figure 5.
Figure 7 is a vertical sectional view of the upper portion of the cooling section of an electrode according to the invention.
Figure 8 is a cross-sectional view of the cooling section shown in Figure 7.
Figure 9 is a cross-sectional view of the cooling section with a system of heat pipes starting at varying heights and ending in a plurality of limbs to improve heat absorption.
Figure 10 is a vertical sectional view of an electrode according to the invention whose cooling section and active portion can be moved towards each other.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 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. Due to the assembly of heat pipes, the heat is transported to the upper portion of the cooling section 3 from where it is dissipated by a water cooling cycle. During furnace operatio: 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. Instead of water, 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. In this case the active sections 7 may also consist of conventional ceramic materials.
Figure 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. To facilitate the exchange of heat, 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.
Figure 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. In this case, 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 electrodes and electrode parts illustrated in the figures constitute preferred embodiments of the invention. Corresponding designs and designs resulting from these embodiments are, therefore, explicitly covered by this invention.
It is also advantageous to employ the electrode according to the invention in the reductive production of materials in reduction furnaces. In 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. Within the framework of the invention and its use, the additional introduction of gas is also included. On the one hand, 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. In contrast to the conventional operation, 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.

Claims

1. An electrode for high-temperature processes, comprising an active section and a cooling section extending into the furnace interior, said cooling section (3) comprising at least one heat pipe (5) with a polytropic heat exchanger in the furnace interior which has an additional cooling system (e.g. 6 in Fig. 1) for the dissipation of heat.

2. The electrode of claim 1, said additional cooling system comprising further heat pipes (6), a gas or fluid cooling cycle (4, 10) or a system comprising either of the two.

3. The electrode of claim 1 or 2, said cooling section (3) comprising a system of heat pipes (5, 6) in at least two zones in such a manner that there is a heat exchange between the condensation zone of the lower heat pipes and the evaporation zone of the heat pipes of the neighbouring zone.

4. The electrode of claim 1, 2 or 3, said cooling section (3) comprising a system of axially parallel and radially arranged heat pipes (5, 6).

5. The electrode of claim 1, 2, 3 or 4, said cooling section (3 comprising at least one axially parallel heat pipe (5) in combination with the additional cooling system (e.g. 6 in Fig. 1) for the dissipation of radially admitted heat.

6. The electrode of claim 5, said additional cooling system constituting a fluid or gas cooling cycle in the radial zone.

7. The electrode as claimed in any of the preceding claims, said cooling section (3) comprising heat pipes (5) the evaporation section of which is located in the axial marginal zone near the active section (7), and heat pipes (6) the evaporation section of which is located in the side zone of the cooling section (3). The use of the electrode in electric arc furnaces with plasma introduction may be especially preferred within the framework of the invention. In this connection it is explicitly stated that a pulsating introduction of the plasma may be favourable and is expressly within the scope of the invention.

The invention entails a number of advantages. They result from an especially flexible electrode operation which permits the safe and selective dissipation of varying heat quantities admitted axially as well as radially in practical operation. The use of axially and radially arranged heat pipes and cooling media such as sodium and lithium are the reasons why it is no longer necessary to introduce water into the furnace proper. The heat transferred to the end of the electrode outside the furnace may be safely dissipated by means of a water-cooled end piece. In addition, safety is enhanced by the possibility to add to the heat pipes a fluid cooling cycle with pumped transfer which is switched on whenever there is special stress. Finally, this additional fluid pumping cycle also guarantees the flawless operation of the heat pipes, leaving radially admitted heat no chance of disturbing or preventing their operation.

8. The electrode as claimed in any of the preceding claims, with at least part of the radially arranged heat pipes (6) being bent.

9. The electrode as claimed in any of the preceding claims, said heat pipe(s) (5, 6) in the evaporation zone and/or condensation zone having a flat design.

10. The electrode of claim 9, said heat pipe(s) (5, 6) in the condensation and/or evaporation zone ending in a plurality of limbs.

11. The electrode as claimed in any of the preceding claims, said heat pipe(s) (5, 6) in combination with the additional cooling system constituting the cooling section (3).

12. The electrode as claimed in any of the preceding claims, said heat pipe(s) (5, 6) in combination with the additional cooling system being assembled in structural zones.

13. The electrode of claim 1, said heat pipe (5, 6) and/or said cooling section (3) constituting the current supply to the active section (7).

14. The electrode of claim 1, the cooling systems of the cooling section (3) being protected from the active section (7) by means of a high-temperature resistant plate (9).

15. The electrode of claim 14, said high-temperature resistant plate (9) being punched.

16. The electrode of claims 1, 14, and 15, said high-temperature resistant plate (9) having connection pieces for the attachment of the active section (7).

17. The electrode of claim 1, said cooling section (3) incorporating the cooling systems being connected to the active section (7) by means of a nipple (11).

18. The electrode of claim 1, said additional cooling system constituting an external, high-temperature resistant heat insulation (2).

19. The electrode as claimed in any of the preceding claims, said heat insulation (2) consisting of coated carbon, ceramic and/or compound materials having carbon and ceramic shares.

20. The electrode of claim 19, said heat insulation (2) comprising removable mouldings in such a manner that there is an air gap between cooling section (3) and heat insulation (2).

21. The electrode of claim 19, said cooling systems (5, 6; 4, 10) being directly embedded in the heat-insulating material (2).

22. The electrode as claimed in any of the preceding claims, characterized in that the condensation part of the heat pipes (5, 6) in the upper end section of the electrode may be engaged with a fluid cooling cycle (4, 10) which, if required, also constitutes the current supply.

23. The electrode of claim 22, the final piece constituting a cap with internally located pipes (10) of a water- cooling system which comprises the upper end and part of the side zone of the cooling section (3).

24. The electrode as claimed in any of the preceding claims, the active section (7) attached to the cooling section (3) consisting of graphite or electrically conductive ceramic material.

25. The electrode as claimed in any of the preceding claims, said heat pipe(s) (5, 6) being(a)gravitation heat pipe(s) and/or(a)Wick heat pipe(s).

26. The electrode as claimed in any of the preceding claims, said heat pipes (5, 6) being cooled by a predetermined gas flow.

27. The electrode as claimed in any of the preceding claims, said cooling section (3) constituting a jacket system, the active section (7) being fed there through.

28. Use of the electrode as claimed in any of the preceding claims 1 to 27 for the production of steel in arc or plasma furnaces.

29. Use of the electrode as claimed in claim 28 for the production of steel in arc or plasma furnaces, with gas being simultaneously supplied.

30. Use of the electrode as claimed in any of the preceding claims 1 to 27 for the production of materials in the reduction furnace.