Industrial electric heating furnaces – Arc furnace device – Power supply system
Patent
1996-07-18
1997-11-11
Hoang, Tu B.
Industrial electric heating furnaces
Arc furnace device
Power supply system
373 50, 373104, H05B 7156
Patent
active
056871872
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for regulating the position of the tip of an electrode which is immersed in an electric furnace heated by electric arc or resistance heating. The electrode is fastened to a bearing device and preparations are introduced into the electrode. The length of the electrode is calculated by registering the distance between a specific point up until evaporation of the preparation.
2. Description of the Prior Art
In electric furnaces or other installations which use consumable electrodes, it is necessary to know the precise position of the individual electrodes. This is of particular importance for installations in which the electrode tips cannot be seen during furnace operation, for example in the case of closed furnaces or furnaces where the batch is covered. In the case of processes for the production of iron-containing alloys, self-baking electrodes are used, while in the production of silicon metal, pre-baked electrodes are used, these being necessary because of the required purity of the product.
Since the knowledge of the exact position of the electrode tip is of great importance for the smelter, recourse is nowadays often also made to processes in which the position of the tip is registered mechanically/optically. This, however, requires the smelting process to be interrupted and the tip to be driven out of the batch or out of the melt for the purpose of measurement or estimation. Furthermore, processes which can be carried out during furnace operation are known.
Thus, German Offenlegungsschrift 25 22 801 discloses a process for measuring the length or immersion depth of a hollow electrode which is immersed into the charged hearth of an electrothermal smelting furnace. In this process the lowering of a measuring rod is measured on a cord and, taking into account the state of baking of the electrode mount, the immersion depth of the electrode into the charge is determined.
To carry out the process, a so-called hollow electrode is necessary, as is complicated sealing of the hollow electrode from the furnace gas. Furthermore, so-called depth-sounding probes are attached to the cords, and are lowered onto the solid base of the furnace until the weight is completely relieved, with the known difficulties of precisely feeding the cord through the seal without influencing the measurement accuracy. The fact that the level and the material composition of the solid base of the bottom are undefinable and depend on the process has proven to be a further disadvantage of this process.
DE 36 00 662 A1 discloses a process for measuring the depth of lowering of an electrode of an electric arc furnace, in which measuring lines which can be consumed by the thermal energy of the melt bath are introduced into the electrodes, as far as the bottom end thereof. The intention is to register electrical or acoustic signals using the measuring lines.
The disadvantage of the process known from this reference is the thermal influence on the measuring line, which, in addition, also depends still more rapidly during the vertical movement of an electrode as a function of the bath, the batch located thereon, and the lining located in the furnace vessel.
When a Soderberg electrode is used, the influence of the electric conductivity of the baked electrode body between the lines cannot be controlled. This stems from the nonuniform properties of the baked electrode compound along the vertical axis because of the discontinuous filling of the electrode as the result of electrical or metallurgical causes.
Furthermore, GDR Patent 136 402 discloses a process for determining the free length of electrodes of the Soderberg type in electric furnaces, in which process the length of the advance of the electrode is measured from the passage of a radioactive preparation, fixed in the electrode, through a specific point up until evaporation of the radioactive preparation in the electric arc zone, and the free electrode length is calculated therefrom.
In the case of this
REFERENCES:
patent: 4580272 (1986-04-01), Honkaniemi et al.
patent: 5331661 (1994-07-01), Maguire et al.
patent: 5568506 (1996-10-01), Schlienger
Kunze Jurgen
Weischedel Walter
Hoang Tu B.
Mannesmann Aktiengesellschaft
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