EP0071517A1 - Arrangement for connecting and supporting a cooled composite electrode of an electric-arc furnace - Google Patents

Abstract

Device intended for the electrical connecting, the hydraulic connecting, and the mechanical supporting of a cooled composite electrode for an electric-arc furnace. It comprises a lateral head (3) adjoining the upper metal column (2) of the electrode and allowing fixing thereof to the end of the electrode-holder arm (4), the said metal column being extended at its upper part by at least two hollow metal appendages (5, 6) allowing the joining of the said metal column, on the one hand to the bus-tubes (7) for conveying the electric current, and on the other hand to the cooling liquid circulating circuit passing inside these bus-tubes as well as inside the said metal column. <IMAGE>

Description

The present invention relates to a device intended for electrical connection, for hydraulic connection, and for mechanical support of a cooled composite electrode for an electric arc furnace intended for example to equip a steelworks.

Known, inter alia from U.S. Patent 4,121,042, so-called "composite" cooled electrodes. These electrodes, which have an upper part. metallic and cooled by water circulation and a part. inferior to graphite., allow significant reductions in graphite consumption. The electrical connection and the electrode support are provided by a clamp enclosing the metal part of the electrode, said clamp being most often cooled by circulation of water.

• - le dispositif de support et connexion à pince est de construction mécanique encombrante., ce qui ne permet pas de rapprocher suffisamment les électrodes les unes des autres. Or, on sait que plus on rapproche les électrodes les unes des autres, plus. on diminue la réactance du four et les pertes électriques, donc plus on augmente son rendement.
• - la pince enserrant la partie métallique de l'électrode, on court le risque que le contact électrique ne se fasse que selon une. génératrice. On doit donc, pour éviter ce risque., placer un insert annulaire en graphite dans la pince, afin d'assurer un contact large sans problèmes. La connexion électrique entre la barre-ominbus d'amenée du courant et l'électrode passe alors par trois contacts successifs : un premier contact entre la cosse du tube-omnibus et la queue de pince,
• . un second contact entre la pince et l'insert en graphite, un troisième contact entre l'insert en graphite et l'électrode.
• - comme il est en général nécessaire de refroidir aussi bien l'électrode que la pince, on doit prévoir deux circuits de refroidissement ce qui conduit à des installations complexes et onéreuses.

These known devices have some drawbacks:

• - The support device and clamp connection is cumbersome mechanical construction., which does not allow to bring the electrodes sufficiently close to each other. Now, we know that the closer we get the electrodes to each other, the more. the reactance of the furnace and the electrical losses are reduced, therefore the more its efficiency is increased.
• - the clamp enclosing the metal part of the electrode, there is the risk that the electrical contact is made only in one. generator. To avoid this risk, an annular graphite insert must therefore be placed in the pliers to ensure wide contact without problems. The electrical connection between the busbar and the electrode then passes through three successive contacts: a first contact between the terminal of the bus tube and the tail of the clamp,
• . a second contact between the pliers and the graphite insert, a third contact between the graphite insert and the electrode.
• - as it is generally necessary to cool both the electrode and the clamp, two cooling circuits must be provided for this which leads to complex and expensive installations.

The connection and support device according to the invention does not have these drawbacks. It is characterized in that it comprises a lateral head adjoining to. the upper metal column of the electrode and allowing its attachment to the end of an electrode-carrying arm, in that said metal column is provided at its upper part with at least one member allowing its connection to the bus-tubes of 'electric current and coolant supply, and in that it is provided with means for hydraulically connecting the hollow inner part. of each bus tube respectively at the inlet and at the outlet of the coolant circulation circuit passing inside said metal column.

• -la figure 1 est une vue en perspective partiellement éclatée d'une électrode composite de four électrique connectée conformément à l'invention.
• - la figure 2 est une coupe partielle selon la direction AA' de la figure 1 et montrant une des deux connexions"queue d'électrode-cosse de tube omnibus".
• - la figure 3 est une coupe longitudinale partielle de l'électrode composite de la figure 1, montrant la circulation du liquide de refroidissement dans le corps de celle-ci.

The invention will be better understood with the aid of the following description of a nonlimiting exemplary embodiment, with reference to the appended drawings in which

• FIG. 1 is a partially exploded perspective view of a composite electrode of an electric oven connected in accordance with the invention.
• - Figure 2 is a partial section along the direction AA 'of Figure 1 and showing one of the two connections "tail of electrode-bus tube lug".
• - Figure 3 is a partial longitudinal section of the composite electrode of Figure 1, showing the circulation of the coolant in the body thereof.

FIG. 1 schematically represents a composite electrode according to the invention, conventionally comprising a lower body 1 in the form of a graphite column, and an upper body 2 in the form of a metal column, hollow and cooled, by circulation of water.

According to the invention, the upper part of the electrode has a head. lateral 3, also metallic and welded to the metallic column 2, this lateral head being intended to be bolted to the electrode-carrying arm 4, of which only the end has been shown in the drawing. Furthermore, the metal column 2 is extended at its upper part by two appendages (5,6) hollow and of rectangular section, forming an electrode tail and therefore intended for. both at connection column 2 to the bus bars 7 for supplying the electric current and the cooling water, a single bus bar 7 having been shown in the drawing, and to the supply as well as to the return from. cooling water in and out. of the metal column 2.

The electrical connection and the cooling circuit will now be described in more detail, also with the aid of FIGS. 2 and 3:

As seen in the drawings, each bus bar 7 has one. flattened end 70 called lug. Each terminal such as 70 is pierced longitudinally with a channel 71 of sufficient section to allow the flow of cooling water supplied by the inner channel of one of the two bars to pass. omnibus 7. The electrical contact between the terminal 70 and the corresponding appendix 5 is made by clamping one on the other at. using eight tie rods 8 and two clamping plates 9.

The continuity of the hydraulic circuit is ensured for each lug-appendage pair by a tube, such as the tube 10 shown, connecting the upstream end of the channel 50 passing through the corresponding appendix 5, to the downstream end of the channel 71 passing through the lug. 70.

FIG. 3 shows, purely for description, the conventional circuit in itself, for cooling the metal column 2. In this figure, the circuit traversed by the cooling water is indicated by arrows. We can also see the bi-frusto-conical connecting piece 11 between the upper metal column 2 and the lower column 1 made of graphite, this element also being known per se.

Claims (2)

1. Connection and support device for a cooled composite electrode for an electric arc furnace, characterized in that it comprises a lateral head (3) adjoining the upper metal column (2) of the electrode and allowing it to be fixed to the end of the electrode-carrying arm (4), in that said metal column is provided at its lower part with at least one member (5,6) allowing its electrical connection to the bus-tubes (7) of supply of electric current and coolant, and in that it is provided with means C (10) making it possible to hydraulically connect the hollow interior part of each bus-tube respectively to the inlet and the outlet of the circulation circuit of coolant passing inside said metal column. 2. Device according to claim 1, characterized in that said members are hollow metal appendages (5,6) extending the upper part of said metal column, and in that these hollow appendages constitute the inlet and outlet channels of said metal column cooling circuit.

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