DE1930052A1 - Special large graphite electrode for the high performance operation of electric arc furnaces - Google Patents

Description

C. CONRADTY Nuremberg 2 June 11, 1969 MAIL COMPARTMENT 4M

IrgA Pl 3/132

Special large graphite electrode for high-performance operation of electric arc furnaces

The invention provides a large electrode G _r aphit for electric arc furnaces.

They require extremely high electrical power in the technical Transferring the melting operation of an electric arc furnace to the material to be melted and heated in the hearth leads to numerous improvements the graphite electrodes. However, one is concerned with the current carrying capacity of the massive graphite electrodes reached a fundamental limit. In order to be even higher in spite of the borderline situation with the current carrying capacity of the graphite electrodes To be able to transfer services, one gives way to the tension side the end. You increase the electrical voltage with the same amperage but causes other difficulties in the arc furnace operation after himself. The arc, which is longer due to the higher voltage, shows unsteady burning behavior and calls through its wandering results in great turbulence in the bath surface, which causes steel and sole blocks to be thrown out against the surface of the bath lateral hearth lining and thus their economically unacceptable excessive wear and tear.

So we had to look for possibilities, the arc to stabilize. For this purpose, hollow electrodes made of graphite were used. Due to the tendency of the arc base to burn inside the central bores, stabilization was achieved, the gases stabilizing through the supply of the arc, such as argon, as well as duroh stabilizing additives on the walls of the Electrode could be improved.

Although these methods have shown many advantages, they were very often the graphite consumption figures are higher than expected or, in the case of the gas-stabilized hollow electrode, the operating costs too high.

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Around this · disadvantages to τβrhiäder and the electrical · load capacity To further increase, according to the invention, a large wick electrode developed.

Dooht electrodes with a small diameter are known in principle for use with cinema projection lamps and for lighting purposes. Ss are charcoal products in the dimensions up to 20 mm in diameter and about 50 mm in length.

The goal-lying invention is concerned with the transfer of this mn and per se known principle of Lei stungs increase το η electrodes on large electrodes for the arc furnace. The gate part of these new electrodes results from a multitude of individual sound effects.
1.) Higher electrical current carrying capacity.

For example, while a normal graphite electrode of 20 "diameter an electrical current rating of 50 kl owned by impregnation with tar and pitch Gate of the graphitizing gate increased to almost 60 kA can be, are with the erfindungegemäflen Doohtelectrodes such loads also made possible without impregnation process, it being evident that even services τοη 70 kA tone of 20 "graphite wick can be electrodetected can. The main parts of the impregnated electrodes, such as There is no increased risk of hitting due to the high sealing and thus reduced thermosohook strength with the wick electrode. Similar to the hollow electrode, operational reliability is even significantly increased, since it is porous Dooht structure in comparison to the MaeeiTelectrode, the graphite dohtelectrode also possesses the wick to expand possibilities.

2.) In the case of the hollow electrode, the stabilization effect is τοη Drilling freeze dependent, so that a relatively high graphite cross cut is required to produce a sufficient bore size.

The wick electrode comes in comparison with very small ones Holes. For an electrode with a diameter

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Claims (1)

knife 300 mm, for example, a hole of 10 mm for Achieving the desired stabilizing effect. 3.) The Doohtelectrode produces a completely calm burning Arc, the almost ideal sinusoidal voltage characteristic shows and thus allows very long arcs with high voltages. 4-.) The consumption of the ground electrode is due to the graphite evaporation, necessary to maintain the arc is determined and is proportional to the charge transported in the arc. The arc stabilization of the Graphite can be transferred away to this and so the graphite consumption can be reduced by suitable dosing. The compound η TiO / 1 TIH described in patent application P 15 39 383.6 shows particularly favorable results (η ■ 1 to 4) in the wick size as an arc tube. Sohut »addressed: Special large graphite electrode for high-performance operation of arc furnaces, characterized in that it contains an arc stabilizing wick. 009 882/084?