Calculation Method of Graphite Electrode Consumption of Electric Arc Furnace Electrode

The graphite electrode consumption in electric furnaces is generally considered to be the third largest in the cost of molten steel after scrap steel and electrical energy. In Europe, the consumption range is 3 to 7 kg / t (crude steel). This article will analyze the main reasons for the differences in electrode consumption of various electric furnaces. It is also pointed out that when the influence of graphite electrode properties is small, the operating conditions of the furnace are the main factors for the change in electrode consumption.

RS Graphite Electrode
RS Graphite Electrode

Electric Arc Furnaces use electrical energy as the main energy source. Electric energy draws arcs through graphite electrode and charge discharge. Produce high temperatures up to 2000 ~ 6000 ℃. The scrap material is melted by means of arc radiation, temperature convection and heat conduction. In the configuration of graphite electrodes for steel-making electric arc furnaces, the basic principles of “ordinary power electric furnace with ordinary power graphite electrode, high power electric furnace with high power graphite electrode, and ultra high power electric furnace with ultra high power graphite electrode” should be followed .

Arc furnace electrodes, especially graphite electrode that connected by nipple joints, and can effectively prevent the electrodes from breaking during use. Electric arc furnaces are electric furnaces that use high temperatures produced by electrode arcs to smelt ores and metals. The energy is very concentrated when the gas discharge forms an arc, and the temperature in the arc zone is above 3000 ° C. For smelting metals, the electric arc furnace has greater process flexibility than other steel-making furnaces, can effectively remove impurities such as sulfur and phosphorus, the furnace temperature is easy to control, and the equipment occupies a small area.

Calculation Method of Graphite Electrode Consumption

The graphite electrode is the last part of the short-circuit power supply of the electric arc furnace. The end of the graphite electrode generates a strong arc to melt the charge and heat the molten steel, that is, the electrode is the central hub that converts electrical energy into thermal energy. The electrode is subjected to high temperature, furnace gas oxidation and colliding material impact during operation. In particular, the junction of the two electrodes has a higher resistance and lower conductivity than other places. Easy to trip, oxidize, fall off and break. As a result, the electrode is greatly consumed, and the smelting time is extended, and the productivity is reduced.

In 1982, Bowman divided the normal graphite electrode consumption into front end consumption and side consumption. Both can be calculated using the following formula:

Normal Graphite Electrode Consumption: CE = Cγ + Cs

Front-End Consumption: Cγ = Vγ · TOntap / W, Vγ = Kγ · I2 / dnγ

In the formula,

TOntap — electric furnace power transmission time, h;

W — Electric furnace tapping weight, t;

Vγ — consumption speed of electrode front end, kg / h;

Kγ-front-end consumption constant (Bowman gives Kγ = 0.0361 for AC arc furnace and n usually takes 0.58)

I ———— Arc current intensity, kA;

dγ ——— The diameter of the electrode front end, m.

Side Consumption: Cs = Vs · TTop-Top / W, Vs = 3Ks · S

In the formula,

TTop-Top — Electric furnace smelting period, h;

W — Electric furnace tapping weight, t;

Vs — consumption speed of electrode side, kg / h;

Ks — oxidation consumption rate, kg / (m2 · h);

S — oxidized surface area in the electrode furnace, m2.

At present, in the production process, the Bowman graphite electrode consumption model has been widely recognized. Wang Mingli and others believe that once the smelting process is stable, the current supplied by the power supply has the greatest impact on the electrode unit consumption.

It is generally believed that in the smelting process, the calculation of graphite electrode consumption has two concepts, net consumption and gross consumption. Net consumption refers to the technical consumption of electrodes consumed during high-temperature sublimation, oxidation and participation in smelting. Gross consumption is the sum of the net consumption and the losses that have not been participated in the smelting. In other words, the graphite electrode consumption model mentioned above is only technical consumption, that is, it is classified as net consumption. Gao Zhanbiao and others believe that at this stage the steel industry mainly uses the following two methods to calculate graphite electrode consumption.

(1) Production method

The output method is based on the amount of molten steel (finished product) produced in a certain period, and the amount of graphite electrode input during the same period minus the remaining amount on the furnace is consumed.

Gross Loss of Tons of Graphite Electrode: MM = MZ / MG

Net Consumption of Ton Steel Graphite Electrode: MJ = MC / MG

In the formula,

MZ—the total consumption of the electrode (input amount-remaining amount on the furnace), kg / t;

MC—The pure consumption of the electrode (input amount-remaining amount on the furnace-loss amount), kg / t;

MG-the amount of finished molten steel, t.

(2) Power consumption method.

The power consumption method is based on the cumulative power consumption of pure heating time in a certain period. The amount of graphite electrode input during the same period deducts the remaining amount on the furnace as the consumption (LF furnace is calculated based on the power consumption and electrode for each temperature increase of 1 ℃).

Graphite Electrode Consumption per Kilowatt Hour: MX = 1000 × MC / QH

In the formula,

MC-the pure consumption of the electrode (input amount-residual amount on the furnace-loss amount), kg / t;

QH ——— The cumulative power consumption in pure heating time, kW · h.

At this stage, when calculating the graphite electrode loss, steel companies generally include the amount that is lost without participating in the smelting. This can more fully reflect the center of gravity and key points of loss in the steelmaking process of the electric arc furnace. So as to find the shortcomings in the process parameters to solve.

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    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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        How to Choose Graphite Electrode for DC Electric Arc Furnace

        DC electric arc furnace is a new type of electric furnace steelmaking equipment developed in the early 1980s. The initial DC electric arc furnace was transformed from the original AC electric arc furnace. How to Choose Graphite Electrode for DC Electric Arc Furnace? Some used 3 graphite electrodes and some used 2 graphite electrodes.

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

        After the mid-1980s, most of the newly designed DC electric arc furnaces only used one graphite electrode. Compared with AC electric arc furnaces with three graphite electrodes of the same power, the total surface area of the electrode that was oxidized at a high temperature was greatly reduced. The DC arc furnace operating at the same high power can reduce the (hp) graphite electrode consumption per ton of steel by about 50%. DC arc furnace current does not produce skin effect and proximity effect when passing through the electrode. The current distribution is uniform on the electrode cross section, and the stability of the DC arc is good. The mechanical vibration is small during operation, and the noise of the electric furnace is also low.

        RS High Quality Graphite Electrode
        RS High Quality Graphite Electrode

        The diameter of the graphite electrode used in the DC electric arc furnace is also calculated based on the capacity of the electric furnace and the allowable current density of the electrode. For ultra-high-power electric furnaces with the same input power, a DC furnace using one graphite electrode has a larger electrode diameter. For example, an AC arc furnace with a capacity of 150t uses an electrode with a diameter of 600mm, while a DC arc furnace with the same capacity uses an electrode with a diameter of 700 ~ 750mm. DC arc furnaces have higher quality requirements for graphite electrodes than graphite electrodes used in AC arc furnaces.

        The Grade, Performance & Application of Graphite Electrodes

        Based on the different standards of various graphite electrode manufacturers, the grades of graphite electrodes are generally as follows:

        • Regular graphite electrode (RP)
        • Impregnated graphite electrode
        • High Power Graphite Electrode (HP)
        • SHP Graphite Electrode (SHP)
        • Ultra High Power Graphite Electrode (UHP)

        The graphite electrodes of Rongsheng graphite electrode manufacturer are equipped with tapered joints, which comply with national standards and international standards such as NEMA CG1, IEC 60239, JIS R7201 and so on.

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

        The use and performance of graphite electrodes:

        1. Used in steelmaking electric arc furnace, refining furnace, as conductive electrode;
        2. Used in industrial silicon furnace, yellow phosphorus furnace, corundum furnace, etc., as conductive electrode.

        Performance of Graphite Electrode:

        • Good conductivity
        • Strong thermal shock resistance
        • High mechanical strength
        Application of UHP Graphite Electrode
        Application of UHP Graphite Electrode

        Applications of graphite electrodes

        In actual use, the specifications and grades of graphite electrodes should be selected according to the specific furnace conditions. The first factor is the maximum current intensity. At the same time, the influence of other factors, such as the characteristics of the electric furnace, the type of charge, the smelting time, the amount of oxygen blowing, the mechanical requirements, and the steelmaking process system, must also be considered.

        Generally, the physical and chemical indicators of most grade graphite electrodes have been standardized. However, in the process of use, the influence of temperature on some indicators must be considered sometimes.

        RS Graphite Electrode
        RS Graphite Electrodes

        Precautions when using graphite electrodes:

        ● According to the capacity of the electric furnace and the load of the transformer, select the grade and diameter of the electrode appropriately.
        ● When charging the electric furnace, a large piece of charge should be installed on the bottom of the furnace to prevent the charge from falling and hitting the electrode. During the smelting process, a large amount of non-conductive objects, such as lime, should be prevented from accumulating directly under the electrode, otherwise it will affect the electrode current, and even cause the electrode to break.
        ● Pay attention to the position of the furnace cover. If the furnace cover is misaligned, the furnace cover will be scratched when the electrode is raised and lowered, resulting in electrode damage.
        ● When connecting the electrodes, if there is any defect in the connector plugs, replace them and then connect them.
        ● After the electrode is connected, if there is a gap on the connection surface, be sure to find out the cause. Use after the gap is eliminated.
        ● The electrode must be used vertically.
        ● The electrode holder should be clamped between the upper and lower cords of the top electrode. It is strictly forbidden to sandwich the electrode in the cord (joint hole) and the middle electrode, otherwise the electrode column may be easily broken.
        ● Because the raw materials and production processes of different manufacturers may be different, the physical and chemical properties of the electrodes are also different. It is recommended that the connectors and electrodes produced by different manufacturers not be used in series.

        RS High Quality Graphite Electrode for Sale

        RS High Quality Graphite Electrode Manufacturer. Graphite electrodes is specifically made from petroleum coke and needle coke as raw materials, and coal tar pitch as a binder, which is prepared through calcining, compounding, kneading, pressing, calcining, graphitizing and machining and is launched in an electric arc furnace electrical energy on the charge heating and melting of the conductor.

        RS Graphite Electrode
        RS Graphite Electrode

        Ultra High Power Graphite Electrode

        Ultra-high-power graphite electrode can allow current densities greater than 25 A / cm2 and are mainly used in ultra-high-power steelmaking electric arc furnaces.

        UHP Graphite Electrode Advantages

        UHP Graphite electrode has good electrical properties and chemical stability, high mechanical strength at high temperatures, less impurities, good vibration resistance. It is a good conductor of heat and electricity.

        UHP Graphite Electrode
        UHP Graphite Electrode
        • Processing speed is faster. Under normal circumstances, graphite machining speed can be 2 to 5 times faster than copper; and discharge processing speed is 2 to 3 times faster than copper;
        • The material is more difficult to deform. Obvious advantages in the thin-walled electrode processing.
        • Lighter weight. The density of graphite is only 1/5 of copper, large electrode for electrical discharge machining, can successfully lessen the gadget tool (EDM) burden; more suitable for large mould applications.
        RS Graphite Electrode Manufacturer
        RS Graphite Electrode Manufacturer

        RS Graphite Electrode Manufacturer

        According to the usage of distinct strength and current, the usage of exceptional refractory raw materials and manufacturing technology, may be divided into rp graphite electrodes, hp graphite electrodes, uhp graphite electrodes. Graphite electrode has proper electrical properties and chemical stability, excessive mechanical energy at excessive temperature, low impurity content, top vibration resistance, is a superb conductor of heat and electricity.

        Graphite Electrode Application and Advantages

        Graphite Electrode Application, in electric arc furnaces steel production, graphite electrodes are commonly used. They are currently the best products be used, and that have the high levels of electrical conductivity and the capability of maintaining the extremely excessive levels of heat generated in this working environment. Graphite electrodes are also used to refine metallic in ladle furnaces and in other smelting processes.

        Graphite Electrodes Application
        Graphite Electrodes Application

        According to the difference in power of the electricity served, RS graphite electrodes manufacturer uses different refractory raw materials and production technology, producing the graphite electrodes can be divided into ordinary power graphite electrodes, high power graphite electrode, ultra-high power graphite electrodes.

        Application of UHP Graphite Electrode
        Application of UHP Graphite Electrode

        RS Graphite electrode has good electrical properties and chemical stability. In details, all kinds of the graphite electrode has advantages of high mechanical strength, low impurity content and good vibration resistance. Graphite electrodes are good conductors of heat and electricity.

        In the graphite electrode application side, graphite electrode is widely used in:

        • steelmaking electric furnace,
        • refining furnaces,
        • submerged arc furnaces,
        • and other smelting furnaces that produce high temperatures by electric arc.
        RS Graphite Electrode for Sale
        RS Graphite Electrode for Sale

        RS graphite electrode is made from the domestic first petroleum coke and high quality needle coke and widely used in the electric furnaces refractories for production of alloy steels, metal and other refractory nonmetallic materials, etc. Graphite Electrode Application. The graphite electrodes include rp, hp graphite electrode, super high power, uhp and square electrode. The range of diameters covers from 200mm to 700mm.

        Welcome to RS, getting the details of the graphite electrodes info and the graphite electrode price. RS can confirm the quality and the quantity. For more: info@graphelectrode.com  .

        The Main Production Points of Graphite Electrode Nipples

        The production points of graphite electrode nipples have their own particularities. The thermal shock resistance of the nipples and the electrode body’s calcined product and the interface between the aggregate and the asphalt coke are different. In many areas, crack extension and extension easily occur in these areas during graphitization.

        Graphite Electrode Nipples
        Graphite Electrode Nipples

        When producing ultra high power graphite electrode nipples, while considering the effect of “flatness” on nipple products, it is also necessary to realize that the interface between aggregate and asphalt coke is more widely distributed, and there are more weak areas. There are more potential structural defects between the focal interfaces and other factors.

        graphite electrode baking
        Graphite Electrode Baking

        The surface area of the uhp graphite electrode body is smaller than the nipple blank. The unit volume of the graphite electrode nipple blank is larger than that of the large-diameter electrode body blank. The nipple blank has a relatively large amount of heat dissipation. The temperature difference between the outer periphery of the nipple in series and the core is large. It is necessary to take technological measures to make up for the unfavorable factors such as the relatively large heat dissipation of the nipple blank and the large temperature difference between the periphery and the core.

        graphite electrode nipple machining
        graphite electrode nipple machining

        For the production points of graphite electrode nipples, the conditions that each series of billets should meet are more stringent. To ensure the quality of the nipples, each series of columns must have the same temperature rise rate. The thermal insulation effect and the degree of heat loss of tandem columns in different spatial positions are different.

        The quality of graphite electrodes and connectors of Rongsheng Graphite Electrode Factory is reliable. If you want to get the graphite electrode nipple price and manufacturer information of graphite electrodes, please contact us. We will get in touch with you in the shortest time.

        350mm UHP Graphite Electrode Production

        With the increase of the proportion of electric furnace steel in the market, the demand for uhp graphite electrode has gradually increased. China’s needle coke resources are further strained, and its prices have been high and highly dependent on imports. This is not conducive to reducing the manufacturing cost of 350mm uhp graphite electrode.

        RS Graphite Electrode
        RS Graphite Electrode

        What’s Raw Material used for the UHP Graphite Electorde Production? 

        In order to reduce production costs, it is urgent to use Chinese needle coke instead of imported needle coke to produce uhp graphite electrodes. Chinese graphite electrode manufacturer, using Chinese domestic needle coke as raw material, adopts new formula and production process technology to carry out the research and development of φ 350mm UHP Graphite Electrode.

        Graphite Electrode Needle
        Graphite Electrode Needle

        Chinese graphite electrode manufacturers, through optimizing the formula and making full use of the established production process and technical conditions, use Chinese domestic needle coke to produce φ350 mm uhp graphite electrode. It can fully meet the requirements of graphite electrode users.

        The Advantages of the Chinese Needle Coke Raw Materials

        1.  The Chinese-made needle coke, as the the raw material for the graphite electrodes, which has higher ash content, higher sulfur content, smaller particle strength, and smaller particle tap density.
        2.  The graphite electrode produced from the Chinese needle coke raw material has the following physical and chemical properties: high bulk density, equivalent flexural strength, slightly lower elastic modulus, higher ash content, and higher resistivity.
        3.  Passed the trial of the steel mill, the graphite electrode has good thermal shock resistance and oxidation resistance performance, which can fully meet the customer’s normal use requirements.
        4.  Using uhp graphite electrode produced by Chinese-made needle coke, using large particle formula, the binder adopts medium-temperature modified asphalt or high-temperature modified asphalt, and adopts standard process. The level of the traditional process greatly reduces the production cost and improves the competitiveness of the product, thus achieving the purpose of replacing imported needle coke.

        Conclusion

        The test of producing φ350 mm uhp graphite electrode by using Chinese-made needle coke was successful. China’s domestic needle-shaped coke raw materials can be popularized for use on medium 400mm and φ450mm uhp graphite electrodes.

        It can be seen from the above experiments that using domestic graphite electrode raw materials and through improved production technology, it has been possible to produce 350mm graphite electrode which can meet customer needs. If you have a demand for uhp graphite electrode, please contact us. We will reply to you as soon as possible.

        UHP Graphite Electrode Used as Arc Furnace Electrodes

        UHP graphite electrodes are becoming more and more widely used. If you have an arc furnace project that requires uhp graphite electrode, or you want to get the latest graphite electrode price. Then, you need to learn more about the graphite electrode market.

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

        First, you need to find the manufacturer of the graphite electrode. There are many graphite electrode suppliers, but not every supplier is a true manufacturer of graphite electrodes. Since the graphite electrode has a complicated production process and a relatively long production cycle, its production workshop covers a large area. A graphite electrode manufacturer that can have a large production workshop must be real.

        graphite electrode production
        graphite electrode production

        Secondly, it is the quality of graphite electrodes. Due to the higher requirements of smelting in steel mills, the requirements for the quality of graphite electrodes are also higher. This requires rigorous quality inspection after graphite electrodes are machined. A full set of quality inspection equipment is also the quality guarantee required by the buyer.

        In the end, the price of graphite electrodes is much more concerned. Due to the shortage of graphite electrodes in the previous period, the graphite electrode price continued to rise during that period. As this wave recedes, the graphite electrodes price does not seem to be as high as before. As a result, it seems that the demand for graphite electrodes is not as crazy as before. Therefore, it is relatively reasonable to buy graphite electrodes now.

        uhp graphite electrodes

        When buying graphite electrodes, the most important thing is to meet the smelting needs of electric arc furnaces. Therefore, sometimes, uhp graphite electrode is not necessarily. However, for arc furnace electrodes with increasing requirements for smelting, it is still recommended to use high-quality uhp graphite electrode.