Tag: arc furnace electrodes

Advantages of DC Electric Arc Furnace Electrodes

In the use of arc furnace electrodes, the advantages of using DC electric arc furnace electrodes compared to AC power supply are obvious in the heat transfer of the metallurgical process.

Graphite Electrode used in DC Electric Arc Furnace
Electric Arc Furnace Electrodes

Disadvantages of AC Power Supply for Electric Arc Furnace

When the arc furnace is powered by an AC power supply, it has four main disadvantages: unstable arc; severe voltage flicker effect; very low electrode life; furnace wall loss is particularly serious. The reason for the unstable arc is that the arc is continuously extinguished and restarted at a frequency of 50 times per second. The lag of restarting the arc depends on the position of the electrode relative to the charge, the current setting value, and the furnace atmosphere and temperature.

uhp graphite electordes for Arc Furnaces
uhp graphite electordes for Arc Furnaces

Advantages of DC Electric Arc Furnace Electrodes

The DC arc is superior to the AC arc in terms of stability and unidirectionality, which has great benefits for heat transfer in the metallurgical process. Theoretical analysis points out that the use of direct current instead of alternating current is a major technical innovation measure. Since the DC current has no zero-crossing problem, the arc stability is improved, and the interference to the power grid is also reduced. In DC arc furnaces, the method of smelting metals using DC current is basically the same as AC arc furnaces. However, because the anode heat on the charge side is high, the “electricity-heat” conversion efficiency of the DC arc is high.

Schematic Diagram of DC Electric Arc Furnace Double Electrodes
Schematic Diagram of DC Electric Arc Furnace Double Electrodes

In a two-electrode DC arc furnace, the arc burns between the two electrodes and the charge. The DC arc furnace uses a thyristor converter to convert AC to DC. The electric current is transferred into the furnace by means of a large current loop and double electrodes, so there is no need to provide furnace bottom electrodes.

RS Graphite Electrode Manufacturer
RS Graphite Electrode Manufacturer

Graphite Electrode Manufacturers

Buy graphite electrode, graphite electrode manufacturers in india. As a manufacturer of graphite electrodes, it aims to provide high-quality graphite electrode products for electric arc furnace steelmaking. No matter where you buy the graphite electrode, please identify the graphite electrode manufacturer. If you encounter any problems in the process of using graphite electrodes, please leave a message to us, we can communicate and discuss.

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    Analysis of AC Arc Furnace Electrodes Loosening in Steel Making

    Over the past decade or so, with the optimization of short processes and the development of refining processes, EAF steelmaking furnace has been greatly improved. Mainly manifested in large-scale and ultra-high power. The power supply mode is AC and DC. The difference between the two is that there are three graphite electrodes on the top of the AC arc furnace, which are connected to A, B and C three-phase alternating current. The DC arc furnace adds a set of rectifier equipment to change the input power from AC to DC. The graphite electrode on the furnace top was changed from three to one, and a bottom electrode was added on the furnace bottom. At present, about 80% of China’s steel-making enterprises still use AC arc furnaces.

    RS High Quality Graphite Electrode
    RS High Quality Graphite Electrode

    AC Arc Furnace Electrodes Loosening

    In AC arc furnace steelmaking, the current and voltage transmitted from the short wire are then transmitted to the electrode through the electrode holder. And an arc is generated between the electrode and the charge to melt the scrap. Only then can other steelmaking processes be completed. As shown below.

    Main Circuit of Steel Making Electric Arc Furnace
    Main Circuit of Steel Making Electric Arc Furnace

    Over the years, the loosening of the AC arc furnace electrodes has frequently occurred. The graphite electrodes or the nipples electrodes thread is damaged and cannot be reused, and the consumption is increased, which brings direct or indirect losses to the steel mill and the graphite electrode manufacturers. It even caused the steel mill to question and claim the quality of the graphite electrode from the manufacturing plant.

    Effect of Three-phase Alternating Current on Graphite Electrode

    To this end, graphite electrode manufacturers start qualitative analysis from the perspective of electric and magnetic fields by consulting relevant data. It was found that the direction of the phase sequence has a great influence on the loosening of the electrode.

    Effect of Three-phase AC on Loosening of Graphite Electrode
    Effect of Three-phase AC on Loosening of Graphite Electrode

    A, B, and C three-phase AC arc furnaces will generate a rotating magnetic field and a rotating magnetic moment to the electrodes. When A, B, and C are in the clockwise phase sequence, the direction of the rotating magnetic distance is also clockwise, which is exactly in the same direction as the electrode thread loosening, which is easy to cause the electrode joint to loosen. Conversely, when A, B, and C are in the counterclockwise phase sequence, the purpose of tightening the electrode joint can be achieved.

    Conclusion

    Based on the above analysis, we have taken corresponding improvement measures for the loosening of electrodes in some steel mills. Adjusting the phase sequence in time has obtained obvious results. For example, the electric arc furnaces of a company’s steelmaking plant have loosened multi-phase electrodes after they were put into production. After adjusting the phase sequence counterclockwise, the arc furnace electrodes did not come off again.

    If your AC arc furnace, during the smelting process, if the electrodes frequently loose and fall off. Please check the phase sequence first to ensure that the phase sequence is adjusted to the counterclockwise direction. Then determine whether the electrode is loose due to other reasons. This can reduce the cost of consumption and improve economic efficiency.

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