Industrial electric heating furnaces – Arc furnace device – Furnace body detail
Patent
1996-05-28
1998-11-10
Hoang, Tu B.
Industrial electric heating furnaces
Arc furnace device
Furnace body detail
373 94, H05B 702
Patent
active
058355235
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bottom electrode for a metallurgical vessel which is operated with direct current. Such an electrode consists of two parts of different material which can be connected with each other. The one part is arranged substantially outside the bottom of the vessel and faces the outside of the vessel and is acted on by a coolant. The inner part faces the inside of the vessel and is developed as a wear element in contact with the molten metal present in the vessel.
2. Description of the Prior Art
Metallurgical vessels operated with direct current, in particular furnaces for the melting of scrap, have in the region of their body, at least one electrode which is generally developed as an anode. These bottom electrodes are located below the surface of the liquid metal during the melting process and are subject not only to the stressing by the electric current but also to thermal, chemical and erosive stresses exerted by the molten metal. In order to reduce the thermal wear, a number of these bottom electrodes are cooled in operating practice.
Thus, a metallic electrode is known from German reference DE-OS 05 40 26 897 which passes through the furnace wall of a dc arc furnace and contacts at one end the melt contained in the vessel, while at its other end it can be connected to sources for the supply of electricity and cooling fluid. This electrode consists of two bars which can be connected to each other and the bar which is in contact with the melt consists of a material comparable with the melt. During operation, the end of this bar is melted by contact with the melt and transported away by the movement of the bath.
From EP 00 12 050, a bottom electrode which is in contact with a molten mass of metal is known in which means are provided on the end facing the melt for reducing the heat-flow movements of the molten metal mass in their vicinity. These means are formed of a plurality of elongated refractory parts which are arranged parallel to each other and lengthen the electrically conductive body in the direction towards the molten mass. The refractory parts can in this connection be completely recessed in the electrically conductive body.
The connecting device known from the European reference has cooling elements which extend deep into the refractory lining of the metallurgical vessel. This bottom electrode not only is of a different type of construction, which is questionable for reasons of operating safety, but it also acts directly on the tip of the electrode by the high cooling effect of the cooling elements arranged in the vicinity of the head. In addition, it has the disadvantage that, upon the melting of the electrode head, the elongated refractory parts are flushed out of the metal region.
German reference DE-PS 219 575 discloses a hearth electrode for electric furnaces. This electrode consists of carbon-free material which is conductive at only higher temperature. Bars of iron or other metal, depending on the material to be treated, are uniformly distributed over the entire hearth surface facing the electrode and bear the hearth. The flush ends of the bars pass through the hearth material and are embedded in a current feed plate.
German reference DE 412 9756 A1 discloses a metallurgical vessel having a refractory lining in which an anode of an DC arc device is present in the region of the bottom of the vessel; A metallic broom-like element, which has bristols that are directed towards the inside of the vessel, is introduced at a predetermined place into the furnace vessel, which in itself is free of refractory material.
SUMMARY OF THE INVENTION
The object of the invention is to create, with simple means, a regeneratable bottom electrode of the type in question which is of long life and suitable for maintenance and which, with dependable transfer of the electric current, has a positive effect on the wear of the refractory lining surrounding it.
Pursuant to this object, and others which will become apparent hereafter,
REFERENCES:
patent: 4697273 (1987-09-01), Cordier
patent: 4754464 (1988-06-01), Feuerstake
patent: 4947405 (1990-08-01), Okada
patent: 5153896 (1992-10-01), Hamy et al.
patent: 5268924 (1993-12-01), Sakakibara et al.
patent: 5371759 (1994-12-01), Wells et al.
patent: 5490163 (1996-02-01), Blumenfeld et al.
patent: 5588018 (1996-12-01), Destannes
Becker Lutz
Feuerstacke Ewald
Hofmann Werner
Schaefers Gerhard
Hoang Tu B.
Mannesmann Aktiengesellschaft
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