Electric arc furnace, method of operating an electric arc furnace and system for inducing vibrations

Abstract

The present disclosure provides an electric arc furnace for melting a metal-containing material, in particular a scrap pile, comprising: a power supply (110); at least one electrode (121) electrically connected to the power supply (110) for receiving an amount of electrical power from the power supply (110) to generate an electric arc; a furnace body (130) for containing the metal-containing material; an electrode positioning system (120) for positioning the at least one electrode (121) relative to the furnace body (130) and / or relative to a bath level; and a control unit (140) for controlling operation of the electric arc furnace, the control unit (140) being connected to the power supply (110) and the electrode positioning system (120) to control their operation; wherein the control unit (140) is configured for intermittently operating the electric arc furnace in a vibration induction mode; wherein, in the vibration induction mode, the control unit (140) operates the electric arc furnace to induce vibrations to the metal-containing material. The present disclosure also provides a method for operating an electric arc furnace and a system for inducing vibrations to a metal-containing material being melted in an electric arc furnace.

Description

Technical Field

[0001] This disclosure relates to an electric arc furnace for melting a metallic material, particularly a waste stockpile; a method for operating an electric arc furnace for melting a metallic material, particularly a waste stockpile; and a system for inducing vibrations in a metallic material, particularly a waste stockpile, which is being melted in the electric arc furnace. Background Technology

[0002] Electric arc furnaces can be used to melt solid materials containing metals (such as ores) into desired and undesirable materials using high heat. The heat is generated using electric arcs, which are created between at least one electrode and a pool of molten material typically melting within the furnace, or within the furnace body forming the anode. Electric arc furnaces can also be used to melt materials such as scrap steel, or to refine molten metals. To generate the electric arc, at least one electrode of an electric arc furnace is typically powered by an electrical source.

[0003] Especially when melting waste piles in an electric arc furnace, a cavity can form around at least one electrode and the arc, which will collapse from time to time. This can be referred to as a cavity collapse.

[0004] Collapsed cavities can have various disadvantages affecting the productivity of electric arc furnaces. For example, they can lead to increased production time, increased wear and tear, health and safety concerns (because damaged electrodes need to be replaced under hazardous conditions), and increased use of consumables. The later the cavitation occurs during melting, the greater its impact on the process. Summary of the Invention

[0005] Various aspects and advantages of this disclosure will be set forth in part in the description which follows, or may be apparent from the description or may be learned by practice of this disclosure.

[0006] This disclosure provides an electric arc furnace, a method of operating the electric arc furnace, and a system for inducing vibrations in a molten metallic material within the electric arc furnace, such that the metallic material is forced to move substantially continuously toward at least one electrode. Compared to standard operation of the electric arc furnace, cavities formed during the melting process can be forced to collapse in their early stages. As the cavities collapse, gravity forces the metallic material to fill them, thereby causing the metallic material to move at least partially toward at least one electrode.

[0007] In one example, this disclosure provides an electric arc furnace for melting metallic materials, particularly scrap heaps. The electric arc furnace has a power source and at least one electrode electrically connected to the power source for receiving a quantity of electricity from the power source, causing the at least one electrode to generate an electric arc. The electric arc furnace also has a furnace body for containing the metallic material and an electrode positioning system for positioning the at least one electrode relative to the furnace body and / or relative to the molten pool level. Furthermore, the electric arc furnace includes a control unit for controlling the operation of the electric arc furnace. The control unit is connected to the power source and the electrode positioning system for controlling their operation. The control unit is configured to operate the electric arc furnace intermittently in a vibration-induced mode. In the vibration-induced mode, the control unit operates the electric arc furnace to induce vibrations towards the metallic material.

[0008] In another example, this disclosure provides a method for operating an electric arc furnace for melting metallic materials, particularly waste piles. The method includes: containing the metallic material in a furnace body; supplying a quantity of electricity to at least one electrode via a power source to generate an electric arc; positioning the at least one electrode relative to the furnace body via an electrode positioning system; and controlling the operation of the electric arc furnace via a control unit. The control unit is configured to operate the electric arc furnace intermittently in a vibration-induced mode. In the vibration-induced mode, vibration is induced in the metallic material.

[0009] In yet another example, this disclosure provides a system for inducing vibration in a metallic material, particularly a waste pile. The metallic material is being melted in an electric arc furnace. The system includes a control unit for controlling the operation of the electric arc furnace. The control unit is connected to a power supply for powering the electric arc furnace; and the control unit is connected to an electrode positioning system for positioning at least one electrode relative to the furnace body containing the metallic material. The control unit is configured to operate the electric arc furnace intermittently in a vibration-induced mode. In the vibration-induced mode, vibration is induced in the metallic material.

[0010] Details of one or more aspects of this disclosure are set forth in the accompanying drawings and the following description. Other features, objects, and advantages of the technology described in this disclosure will become apparent from the specification, drawings, and claims. Attached Figure Description

[0011] Referring to the accompanying drawings, the complete and feasible disclosure of this invention is set forth in the specification, in which:

[0012] Figure 1 This is a schematic diagram of an electric arc furnace according to an embodiment of the present disclosure.

[0013] Figure 2 This is a schematic diagram illustrating the control of certain parameters during operation of an electric arc furnace according to an embodiment of the present disclosure.

[0014] Figure 3This is a schematic diagram of a method for operating an electric arc furnace according to an embodiment of the present disclosure. Detailed Implementation

[0015] This disclosure generally relates to an electric arc furnace controlled to avoid relatively large cavity collapse by inducing vibrations into a metallic material. The electric arc furnace operating according to this disclosure operates intermittently in a vibration-induced mode to intentionally induce (e.g., significantly) stronger vibrations compared to a standard operating mode. Vibrations can also occur during the operation of prior art electric arc furnaces, for example, due to cavity collapse or other causes arising from standard operation. As used herein, when referring to the induction of vibration, it generally refers to a vibration-induced mode used to intentionally induce relatively strong vibrations. In the vibration operating mode, the electric arc furnace typically operates in a manner different from the standard operating mode. The cavity collapses at least partially due to the induced vibrations. In some examples, the electric arc furnace is controlled to induce vibrations into the metallic material via an electric arc.

[0016] Generally, this disclosure describes an electric arc furnace for melting metallic materials, particularly scrap heaps. As used herein, the term "electric arc furnace" can refer to an AC electric arc furnace operated by alternating current and / or a DC electric arc furnace operated by direct current. Electric arc furnaces can be used to melt metallic materials, such as scrap steel.

[0017] The electric arc furnace includes a power source. The power source may include a power source such as a field generator, a public power grid, and / or the like. A field generator may include a diesel power plant, a coal-fired power plant, a renewable energy power plant, and / or the like. The power source may include power electronic equipment, one or more inverters, transformers, and / or reactors. In some embodiments, the power source may be connected in series with the reactor and transformer.

[0018] The electric arc furnace also includes at least one electrode. This electrode may be referred to as a melting electrode. The electrode may be a graphite electrode. The at least one electrode is electrically connected to a power source. The power source supplies a certain amount of electricity to the at least one electrode, causing the at least one electrode to generate an electric arc. The electric arc furnace may include more than one electrode. In particular, an AC electric arc furnace may include at least three electrodes, and in some examples at least six electrodes. In embodiments, a DC electric arc furnace may include more than one electrode, particularly more than two electrodes, and in some examples more than three electrodes, such as four or five electrodes.

[0019] In addition, an electric arc furnace includes a furnace body for containing metallic materials. Typically, depending on the type of electric arc furnace (e.g., AC or DC), the furnace body and / or the metallic material act as the anode during operation, while at least one electrode typically acts as the cathode.

[0020] To position at least one electrode relative to the furnace body, the electric arc furnace includes an electrode positioning system. Typically, the electrode positioning system may include a hydraulic device, a motor (e.g., a linear motor and / or a servo motor), and / or the like for raising or lowering at least one electrode. Each electrode can be raised or lowered independently of each other. During operation of the electric arc furnace, at least one electrode can be positioned relative to the molten pool level. During operation of the electric arc furnace, the molten pool level can change substantially continuously. In particular, the molten pool level changes as the metallic material is melted.

[0021] The operation of the electric arc furnace is controlled by a control unit. The control unit can be a single component, or it can include multiple units that control each other and / or individually the operation of the electric arc furnace. The control unit is connected to the power supply and electrode positioning system to control their operation.

[0022] The control unit is configured to operate the electric arc furnace intermittently in vibration-induced mode. According to one aspect, vibration-induced mode is a dedicated operating mode, and the controller is configured to enter and exit this dedicated operating mode.

[0023] As used herein, the term "intermittently" can include multiple entry and exit from vibration-induced mode during operation, such that the arc repeatedly operates in vibration-induced mode within short time intervals interspersed with another (non-vibration-induced) operating mode. Multiple vibration-induced mode intervals may exist, and the duration of each vibration-induced mode interval may be shorter than the surrounding intervals of another operating mode. Thus, the term "intermittently" can include, for example, operating the electric arc furnace in vibration-induced mode for less than half (particularly at most one-third) of the operating time between the entry of at least one electrode and the completion of the melting process (i.e., when the metallic material is fully molten). The term "intermittently" can also refer to the periodic operation of the electric arc furnace in vibration-induced mode, such as during one or more steps of the melting process.

[0024] In vibration-induced mode, the control unit operates the electric arc furnace to induce vibration in the metallic material. Operating the electric arc furnace according to this disclosure may include intentionally and temporarily increasing vibration so that one or more cavities in the metallic material, particularly in waste piles, are forced to collapse substantially permanently. By doing so, large cavities cannot be formed. In other words, significantly stronger vibrations are intentionally induced in vibration-induced mode compared to the standard operating mode of the electric arc furnace.

[0025] Embodiments of this disclosure can reduce melting process time, thereby lowering costs; make electric arc furnace operation safer; reduce energy consumption of electrical and chemical energy; reduce electrode wear (because oxidation time can be reduced and electrode breakage due to mechanical loads acting on the electrodes, especially during large cavern collapses); and / or achieve higher yields when converting metallic materials into, for example, steel. Furthermore, fluctuations in the duration of the melting process can be reduced.

[0026] In some examples, the electric arc furnace may include a shaking device for inducing vibrations in metallic materials by mechanically inducing vibrations at least on the furnace body.

[0027] In an embodiment, in vibration-induced mode, the control unit operates the electrode positioning system and power supply such that an electric arc generated by at least one electrode induces vibration in the metallic material. This type of embodiment can be advantageous because the vibration-induced mode can be implemented in the operation of the electric arc furnace without requiring costly modifications to the furnace. Here, the vibration-induced mode is a dedicated mode that can be specifically enabled and disabled. In an embodiment, the vibration-induced mode is enabled by modifying operating parameters according to the vibration-induced mode, whereby the operating parameters differ from those set in another (normal) operating mode (according to different specifications). Operating parameters may, for example, include setpoints for current, voltage, arc length, or related parameters. In an embodiment, a dedicated vibration-induced mode specification for setting the operating parameters can be activated, which differs from the specification in another (normal) operating mode. In one embodiment, the vibration-induced mode can be set to TRUE, thereby activating the vibration-induced mode specification. In an embodiment, the operating parameters can be changed incrementally when entering and exiting the vibration-induced mode.

[0028] Unstable arcs typically induce significantly more vibrations than stable arcs; that is, the more the arc "twistrims," ​​the more vibrations it induces. For example, an arc can be destabilized by reducing the amount of current flowing through at least one electrode. In other examples, an arc can be destabilized by increasing the arc length (e.g., compared to operating modes before and after the vibration-induced operating mode). Such embodiments can reduce the likelihood of arc loss events. According to embodiments, the power supply can be configured to allow independent control of a first control variable related to current and a second control variable related to voltage. Specifically, since voltage is typically controlled by raising and lowering at least one electrode using an electrode positioning system, the power supply can allow control of the first control variable related to current independent of the second control variable related to voltage. In some examples, the power supply may include a power electronic converter. In embodiments, the first and / or second control variables may be related to impedance.

[0029] In vibration-induced mode, the control unit can operate the power supply and / or electrode positioning system to increase the voltage (or vice versa) without reducing the current. In vibration-induced mode, the control unit can also operate the electrode positioning system to increase the arc length of at least one electrode. As used herein, "increase arc length" can refer to an increase compared to standard operating mode. Typically, the arc length can be increased by increasing the vertical distance between the molten pool level and at least one electrode. The arc length can also be increased by raising at least one electrode using the electrode positioning system. Before and after (in between) vibration-induced mode, the system reverts to standard operating mode, which is a mode different from vibration-induced mode.

[0030] In embodiments, in the vibration-induced mode, the arc length and / or current can be adapted at least partially to be substantially continuous. As used herein, the term "at least partially adapted" can refer to at least one time interval in which the vibration-induced mode is activated. For example, a control unit can be configured to operate a power supply and / or an electrode positioning system to change the arc length of at least one electrode. The current can remain constant. According to embodiments, in the vibration-induced mode, the electrode positioning system can be configured to substantially raise and lower at least one electrode throughout the entire corresponding time interval in which the vibration-induced mode is activated. Such embodiments can induce vibrations with a variety of frequencies, thereby increasing the likelihood of exciting metallic materials to cause cave collapse. In particular, by scanning or otherwise continuously modifying operating parameters, such embodiments can induce vibrations with a variety of frequencies and may also achieve the excitation of metallic materials at resonant frequencies. By operating at resonance, the natural frequencies of metallic materials can be triggered, thereby more effectively forcing cave collapse.

[0031] Resonance in metallic materials can be detected by adapting the arc length and / or current in a vibration-induced mode and by directly or indirectly measuring the vibration (directly or indirectly, e.g., by an electrical signal indicating the vibration). According to an embodiment, operating parameters can be tuned to values ​​indicating the detected resonance for operation under resonance conditions.

[0032] According to embodiments, closed-loop control can be provided for tuning operating parameters toward resonant conditions. The closed-loop control may include adapting operating parameters—such as arc length and / or current in a vibration-induced mode—detecting resonant conditions indicating resonance in a metallic material, and adjusting the operating parameters to operate under resonant conditions. Therefore, the closed-loop control is designed to adjust operating parameters toward resonant conditions. For example, if / as soon as resonance is detected, the closed-loop control can be configured to control the arc length and / or current to remain substantially constant.

[0033] Furthermore, an electric arc can be generated by supplying power to at least one electrode at a detected resonant electrical frequency. The power at the detected resonant electrical frequency can, for example, be superimposed on the base power supplied to the electrode, such as from an AC power source or from a DC power source, and power the electrode.

[0034] In one embodiment, the control unit can be configured to activate a vibration-induced mode when at least one electrode is at a predetermined height relative to the furnace body and / or the molten pool level. According to another embodiment, the control unit can be configured to activate a vibration-induced mode when the voltage is at a specific value. In another embodiment, the control unit can be configured to activate a vibration-induced mode during a single melting process when a certain amount of electrical energy has been applied to the electric arc furnace. The melting process may include steps such as drilling in at least one electrode, melting of the metallic material, and may terminate when substantially all of the metallic material to be melted is in a molten state. In another embodiment, the control unit can be configured to activate a vibration-induced mode when current fluctuations and / or voltage fluctuations drop below a specific value.

[0035] According to an embodiment, the control unit can be configured to stop the vibration-induced mode after a predetermined operating time and / or when a predetermined amount of electrical energy (e.g., in MWh) is detected from the power source and / or when a predetermined arc power stability index is detected. "Stop vibration-induced mode" can refer to a stop for the entire melting process.

[0036] Arc power stability indices can be correlated with current fluctuations, voltage fluctuations, acoustic signals, furnace vibrations, and / or furnace temperature. For example, harmonics (e.g., voltage and / or current harmonics) can indicate arc stability, particularly the number of harmonics, and more specifically, the number of atypical harmonics. Acoustic signals can indicate the sound of a cavern collapsing. Temperature typically rises near the end of the melting process. Arc power stability indices can be correlated with absolute values ​​and / or relative values ​​(e.g., for a specific time interval).

[0037] In embodiments, the control unit can operate the electric arc furnace in vibration-induced mode for a maximum of 5 minutes within 10 minutes, particularly for a maximum of 4 minutes within 10 minutes, and preferably for a maximum of 3 minutes within 10 minutes. According to embodiments, the control unit can operate in vibration-induced mode for at least 1 second during certain steps of the melting process, particularly for at least 3 seconds. Such embodiments can avoid adverse feedback to the public power grid, particularly flicker.

[0038] According to an embodiment, the control unit can be configured to operate only a single electrode of at least one electrode simultaneously in a vibration-induced mode, particularly only two electrodes of at least one electrode.

[0039] In some embodiments, the control unit can operate the electric arc furnace in a vibration-induced mode. As used herein, "mode" can refer to a mode that induces vibration in metallic materials. For example, the control unit can be configured to induce vibration by operating the power supply and / or electrode positioning system to increase the voltage (or vice versa) for a first electrode without decreasing the current; and to induce vibration by operating the electrode positioning system to increase the arc length of the first electrode. Subsequently, the control unit can be configured to induce vibration by operating the power supply and / or electrode positioning system to increase the voltage (or vice versa) for a second electrode without decreasing the current; and to induce vibration by operating the electrode positioning system to increase the arc length of the second electrode. In some embodiments, the control unit operates the electric arc furnace such that both the first and second electrodes simultaneously or alternately provide increased arc lengths, for example, depending on the process steps of the melting process.

[0040] According to embodiments, the control unit can operate the electric arc furnace to induce vibration based on an artificial intelligence-based scheme. For example, the artificial intelligence can determine when to activate the vibration-induced mode, when to deactivate the vibration-induced mode and / or mode, for example, based on multiple control parameters, such as parameters related to voltage and / or current, acoustic signals, etc., as also described in this disclosure. Such embodiments may include a learning process for the control unit.

[0041] In one embodiment, the electric arc furnace may include at least three electrodes, and a power source may supply power to the at least three electrodes such that each of the three electrodes receives one phase. Each phase may be controlled independently of each other by current and voltage.

[0042] According to an embodiment, the control unit is configured to reduce a certain amount of power received by at least one electrode that is not operating in a vibration-induced mode (e.g., energy-saving mode).

[0043] On the other hand, a method is provided for operating an electric arc furnace for melting metallic materials, particularly waste piles. The method includes containing the metallic material in a furnace body; supplying a certain amount of electricity to at least one electrode via a power source to generate an electric arc; positioning the at least one electrode relative to the furnace body and / or relative to the molten pool level via an electrode positioning system; and controlling the operation of the electric arc furnace via a control unit; wherein the control unit is configured to operate the electric arc furnace intermittently in a vibration-induced mode; wherein, in the vibration-induced mode, vibration is induced in the metallic material.

[0044] In an embodiment, in the vibration-induced mode, the electrode positioning system and power supply can be operated via a control unit so that an electric arc generated by at least one electrode induces vibration in the metallic material.

[0045] According to an embodiment, supplying a certain amount of power to at least one electrode via a power source to generate an electric arc may include: independently controlling a first control variable related to current and a second control variable related to voltage. In vibration-induced mode, the method may include operating the power source via a control unit to increase the voltage without decreasing the current (or vice versa); and may also include operating an electrode positioning system via a control unit to increase the arc length of at least one electrode.

[0046] In the embodiments, the arc length and / or current can be adapted substantially continuously in the vibration-induced mode.

[0047] According to an embodiment, a vibration-induced mode can be activated when at least one electrode is at a predetermined height relative to the furnace body and / or relative to the molten pool level.

[0048] In an embodiment, the vibration-induced mode may be deactivated after a predetermined operating time and / or when a predetermined amount of electrical energy from the power source is detected and / or when a predetermined arc power stability index is detected.

[0049] According to an embodiment, the electric arc furnace can be operated in vibration-induced mode for a maximum of 5 minutes within 10 minutes, particularly for a maximum of 4 minutes within 10 minutes, and preferably for a maximum of 3 minutes within 10 minutes. In an embodiment, the vibration-induced mode can be activated for at least 1 second, particularly at least 3 seconds, within 30 seconds of a process step in the melting process.

[0050] In an embodiment, the vibration-induced mode may be activated simultaneously for only one of the at least one electrodes, and particularly for two of the at least one electrodes.

[0051] According to an embodiment, the power source can supply power to at least three electrodes, such that each of the three electrodes receives one phase.

[0052] In an embodiment, the method may further include reducing a certain amount of power received by electrodes that are not operating in vibration-induced mode.

[0053] According to another aspect, a system for inducing vibration in a metallic material, particularly a waste pile, is provided. The metallic material is being melted in an electric arc furnace. The system includes a control unit for controlling the operation of the electric arc furnace. The control unit is connected to a power supply for powering the electric arc furnace. The control unit is also connected to an electrode positioning system for positioning at least one electrode relative to the furnace body containing the metallic material and / or relative to the molten pool level. The control unit is configured to operate the electric arc furnace intermittently in a vibration-induced mode. In the vibration-induced mode, vibration is induced in the metallic material.

[0054] Reference will now be made in detail to embodiments of the present disclosure, some examples of which are illustrated in the accompanying drawings. Each example is provided by way of interpreting the disclosure rather than limiting it. For example, features illustrated or described as part of an embodiment may be used with other embodiments to produce further embodiments. The drawings may not be drawn to scale.

[0055] Figure 1 An electric arc furnace and a system for inducing vibrations in a metallic material are schematically illustrated according to embodiments of the present disclosure.

[0056] An electric arc furnace can be used to melt metallic materials, such as waste heaps. The electric arc furnace includes a power source 110 and at least one electrode 121. The electrode is electrically connected to the power source 110 and receives a certain amount of electricity from the power source 110. The power source includes a power supply 111, such as a public power grid or the like. The electric arc furnace also includes a furnace body 130 that houses the metallic material and an electrode positioning system 120 for positioning the electrode relative to the furnace body 130.

[0057] The control unit 140 is used to control the operation of the electric arc furnace. The control unit 140 is connected to the power supply 110 and the electrode positioning system 120 to control their operation.

[0058] For example, the control unit 140 can control the power supply 110 to provide a certain amount of power to the electrode 121, and can control the electrode positioning system 120 so that the electrode 121 ignites an electric arc between the electrode 121 and the furnace body 130, the metallic material and / or the fluid (such as molten material or slag) contained in the furnace body 130.

[0059] The melting process may include: filling the furnace body 130 with a metallic material, vertically positioning the electrode 121 above the furnace body 130, drilling a hole into the metallic material and the furnace body 130 with the electrode 121, and melting the metallic material. An electric arc melts the metallic material. Typically, especially after drilling, the metallic material melts from bottom to top, i.e., starting from the bottom of the furnace body 130. This can create a cavity.

[0060] The control unit 140 operates the electric arc furnace intermittently in vibration-induced mode. In vibration-induced mode, vibration is induced in the metallic material.

[0061] For example, vibration can force the metallic material to move at least partially toward the electrode 121. In other words, vibration forces the metallic material to move upward / downward, rather than relying solely on gravity (where gravity forces, for example, a cave to collapse because the metallic material that initially supported other metallic materials above has been melted).

[0062] This can be achieved, for example, by shaking the furnace body 130 with a shaking device to mechanically induce vibration in the metal-containing material. Alternatively or additionally, the control unit 140 can operate the electrode positioning system 120 and the power supply 110 so that the electric arc generated by the electrode 121 induces vibration in the metal-containing material.

[0063] To induce vibration via an electric arc, power supply 110 allows independent control of a first control variable related to current (also known as arc current) and a second control variable related to voltage (also known as arc voltage), for example, by including a power electronic converter 112. Power supply 110 may also include a transformer defining a low-voltage side toward electrode 121 and a high-voltage side toward power supply 111. Power electronic converter 112 may be arranged on the high-voltage side and / or the low-voltage side of the transformer. In vibration-induced mode, control unit 140 operates power supply 110 and / or the electrode positioning system to increase voltage without decreasing current, and operates electrode positioning system 120 to increase the arc length of electrode 120. Thus, vibration is induced in the metallic material without the risk of arc loss events that reduce the efficiency of the melting process.

[0064] Figure 2 A schematic diagram illustrating the control of certain parameters during operation of an electric arc furnace according to an embodiment of the present disclosure is shown.

[0065] An electric arc furnace can be as follows: Figure 1 The electric arc furnace can be embodied in a configuration whereby the control unit 140 operates the electrode positioning system 120 and the power supply 110, causing an electric arc generated by at least one electrode 121 to induce vibrations in the metallic material.

[0066] The x-axis 201 can refer to, for example, time, the first y-axis 202 can refer to voltage, and the second y-axis 203 can refer to current.

[0067] The electric arc furnace includes three electrodes 121, namely a first electrode, a second electrode, and a third electrode. The electric arc furnace may include any other number of electrodes 121.

[0068] The electric arc furnace can be, for example, an AC electric arc furnace. A first electrode can receive a first phase, a second electrode can receive a second phase, and a third electrode can receive a third phase. Each phase includes arc voltages 211, 212, and 213 and arc currents 214, 215, and 216. Arc voltages 211, 212, and 213 in… Figure 2 The figure shows the phase-to-phase voltage.

[0069] The control unit 140 controls the power supply 110 and the electrode positioning system 120 to set the arc voltages 211, 212, 213 and the arc currents 214, 215, 216.

[0070] The electric arc furnace can be a DC electric arc furnace. In this case, the arc voltages 211, 212, and 213 and the arc currents 214, 215, and 216 can be similar to those in an AC electric furnace, each referring to a single electrode.

[0071] In the first section 221, the control unit 140 can operate the electrode positioning system 120 and the power supply 110 for borehole entry. In some examples, vibration-induced mode is not used during borehole entry of the electrode 121.

[0072] Subsequently, in the second section 222, the melting of the metallic material begins or continues. The control unit 140 operates the electric arc furnace intermittently in vibration-induced mode.

[0073] Control unit 140 initiates the vibration-induced mode at activation point 224. Activation point 224 may refer to the time when the first electrode is at a predetermined height relative to the furnace body and / or relative to the molten pool level. Activation point 224 may refer to the time when a certain amount of energy has been applied to the electric arc furnace. In some embodiments, activation point 224 may be determined as the moment when the current fluctuations of the arc currents 214, 215, 216 and / or the voltage fluctuations of the arc voltages 211, 212, 213 drop below a specific value. This specific value may be an absolute value of a specific time interval, such as the average value of that time interval. This specific value may also be a relative value. A relative value may refer to a comparison of the fluctuations of a specific time interval with the fluctuations of a previous time interval or the like.

[0074] In vibration-induced mode, control unit 140 controls electrode positioning system 120 to raise the first electrode. The distance between the bottom of furnace body 130 and the bottom of the first electrode increases. Therefore, the arc voltage 211 increases. Figure 2 It can be seen that the arc current 214, which is also associated with the first electrode, has not decreased. This reduces the risk of arc loss events.

[0075] During a time interval 223 of, for example, 15 to 25 seconds, vibrations are induced in the metallic material by an electric arc established by the first electrode. The second and third electrodes can be controlled to continue normal operation.

[0076] After time interval 223, control unit 140 returns to standard operating mode, and the first electrode is de-energized. Arc voltage 211 decreases. Arc current 214 remains substantially constant.

[0077] Subsequently, the control unit 140 returns to the vibration-induced mode by raising the second electrode through the control electrode positioning system 120. The distance between the bottom of the furnace body 130 and the bottom of the second electrode increases. Therefore, the arc voltage 212 increases. Figure 2As can be seen, the arc current 215 associated with the second electrode did not decrease. The arc length associated with the second electrode remained essentially continuous in the vibration-induced mode. The control unit 140 then operated the electric arc furnace back to the standard operating mode.

[0078] Subsequently, the control unit 140 returns to the vibration-induced mode by raising the third electrode through the control electrode positioning system 120. The distance between the bottom of the furnace body 130 and the bottom of the third electrode increases. Therefore, the arc voltage 213 increases. Figure 2 As can be seen, the arc current 216, which is also related to the third electrode, did not decrease.

[0079] In some embodiments, the control unit 140 operates the electric arc furnace intermittently in a vibration-induced mode. This mode can be used to determine when to initiate the vibration-induced mode, when to operate one or more electrodes in the vibration-induced mode, the time interval for operating one or more electrodes in the vibration-induced mode, when to end the intermittent operation of the electric arc furnace in the vibration-induced mode, and the number of electrodes used to induce vibration, etc. This mode can be a periodic mode. This mode can be based on artificial intelligence. For example, the control unit 140 can be configured to adapt the mode based on artificial intelligence and process parameters (such as acoustic signals, temperature, arc current parameters, and / or arc voltage parameters such as fluctuations, and / or the like). The process parameters can be related to one or more previous melting processes.

[0080] like Figure 2 As shown, the control unit 140 operates the electric arc furnace intermittently in a vibration-induced mode according to a pattern. For example, the time interval between two stages of operating the electric arc furnace in the vibration-induced mode can increase and / or decrease towards the end of the curve.

[0081] In an embodiment, the control unit 140 can reduce a certain amount of power received by at least one electrode that is not operating in vibration-induced mode. For example, when the control unit 140 controls the electrode positioning system 120 and the power supply 110 to increase the arc voltage 211 associated with the first electrode, a certain amount of power received by the second electrode and / or a certain amount of power received by the third electrode can be reduced.

[0082] Control unit 140 terminates the vibration-induced mode at end point 225. End point 225 may refer to the time elapsed since a predetermined operating time has been reached. End point 225 may refer to the time since a certain amount of energy has been applied to the electric arc furnace. In some examples, an arc power stability index may be detected to determine end point 225. The arc power stability index may be related to the temperature within the furnace body 130, or, for example, to the number of collapse cavities and / or collapse cavities.

[0083] Figure 3 A method of operating an electric arc furnace according to an embodiment of the present disclosure is illustrated schematically.

[0084] This method is used for melting metallic materials, particularly scrap heaps. The method includes containing the metallic material in a furnace body 310; supplying a certain amount of electricity to at least one electrode via a power source to generate an electric arc 320; positioning at least one electrode 330 relative to the furnace body and / or relative to the molten pool level via an electrode positioning system; and controlling the operation of the electric arc furnace 340 via a control unit. The control unit operates the electric arc furnace 350 intermittently in a vibration-induced mode, thereby inducing vibration towards the metallic material.

[0085] In some embodiments, the method may include reducing a certain amount of power 360 received by electrodes not operating in vibration-induced mode.

[0086] Therefore, an electric arc furnace for melting metallic materials, particularly waste piles, has been presented in the foregoing description with reference to specific examples; a method for operating an electric arc furnace for melting metallic materials, particularly waste piles; and a system for inducing vibrations in metallic materials, particularly waste piles, which are being melted in the electric arc furnace. It should be understood that the various aspects disclosed herein can be combined in combinations other than the specific combinations presented in the accompanying drawings. It should be understood that various modifications can be made to the referenced examples without departing from the scope of this disclosure and the appended claims.

Claims

1. An electric arc furnace for melting metallic materials, wherein the metallic materials are particularly scrap heaps, the electric arc furnace comprising: Power supply (110); At least one electrode (121) is electrically connected to the power source (110) for receiving a certain amount of power from the power source (110) to generate an electric arc; Furnace body (130), the furnace body being used to contain the metal-containing material; An electrode positioning system (120) is used to position at least one electrode (121) relative to the furnace body (130) and / or relative to the molten pool level. as well as A control unit (140) is used to control the operation of the electric arc furnace. The control unit (140) is connected to the power supply (110) and the electrode positioning system (120) to control their operation. The control unit (140) is configured to operate the electric arc furnace intermittently in a vibration-induced mode; In the vibration-induced mode, the control unit (140) operates the electric arc furnace to induce vibration in the metal-containing material.

2. The electric arc furnace according to claim 1, wherein, In the vibration-induced mode, the control unit (140) operates the electrode positioning system (120) and the power supply (110) such that the electric arc generated by the at least one electrode (121) induces the vibration in the metallic material.

3. The electric arc furnace according to claim 2, wherein the power supply (110) is configured to allow independent control of a first control variable related to current and a second control variable related to voltage; in particular, wherein, In the vibration-induced mode, the control unit (140) operates the power supply (110) and / or the electrode positioning system (120) to increase the voltage without decreasing the current, or vice versa; and in particular, in the vibration-induced mode, the control unit (140) operates the electrode positioning system (120) to increase the arc length of the at least one electrode (121).

4. The electric arc furnace according to claim 3, wherein in the vibration-induced mode, the arc length and / or the current are at least partially substantially continuously adapted.

5. The electric arc furnace according to any one of claims 2 to 4, wherein the control unit (140) is configured to activate the vibration-induced mode when the at least one electrode (121) is at a predetermined height relative to the molten pool level and / or the furnace body (130).

6. The electric arc furnace according to any one of claims 2 to 5, wherein the control unit (140) is configured to terminate the intermittent operation of the electric arc furnace in the vibration-induced mode after a predetermined operating time and / or when a predetermined amount of electrical energy supplied by the power source (110) is detected and / or when a predetermined arc power stability index is detected.

7. The electric arc furnace according to any one of claims 2 to 6, wherein the control unit (140) operates the electric arc furnace for a maximum of 5 minutes within 10 minutes, particularly for a maximum of 4 minutes within 10 minutes, and preferably for a maximum of 3 minutes within 10 minutes in the vibration-induced mode.

8. The electric arc furnace according to any one of claims 2 to 7, wherein the control unit (140) is configured to operate only a single electrode of the at least one electrode (121) simultaneously in the vibration-induced mode, particularly only two electrodes of the plurality of electrodes (121).

9. The electric arc furnace according to any one of claims 2 to 8, wherein the electric arc furnace comprises at least three electrodes; and wherein the power source (110) supplies power to the at least three electrodes such that each of the three electrodes receives a phase.

10. The electric arc furnace according to any one of claims 2 to 9, wherein the control unit (140) is configured to reduce the amount of power received by at least one electrode that is not operating in the vibration-induced mode.

11. A method of operating an electric arc furnace for melting a metallic material, particularly a waste stockpile, the method comprising: The metal-containing material is contained in the furnace body (310). A certain amount of power is supplied to at least one electrode via a power source to generate an electric arc (320). The at least one electrode (330) is positioned relative to the furnace body via an electrode positioning system; and The operation of the electric arc furnace is controlled via a control unit (340). The control unit is configured to operate the electric arc furnace (350) intermittently in vibration-induced mode. In the vibration-induced mode, the vibration is induced in the metallic material.

12. The method of operating an electric arc furnace according to claim 11, wherein, In the vibration-induced mode, the electrode positioning system and the power supply are operated via the control unit, such that the electric arc generated by the at least one electrode induces the vibration in the metallic material.

13. The method of operating an electric arc furnace according to claim 12, wherein supplying a certain amount of electricity to the at least one electrode via a power source to generate an electric arc comprises: Independently control the first control variable related to current and the second control variable related to voltage; in particular, The method further includes, in the vibration-induced mode, operating the power supply via the control unit to increase the voltage without decreasing the current, or vice versa; and in particular, The method further includes, in the vibration-induced mode, operating the electrode positioning system via the control unit to increase the arc length of the at least one electrode; and in particular, In the vibration-induced mode, the arc length and / or the current are at least partially substantially continuous.

14. The method of operating an electric arc furnace according to any one of claims 12 to 13, wherein the vibration-induced mode is activated when the at least one electrode is at a predetermined height relative to the furnace body.

15. The method of operating an electric arc furnace according to any one of claims 12 to 14, wherein the control unit is configured to terminate intermittent operation of the electric arc furnace in vibration-induced mode after a predetermined operating time and / or when a predetermined amount of electrical energy from the power source is detected and / or when a predetermined arc power stability index is detected.

16. The method of operating an electric arc furnace according to any one of claims 12 to 15, wherein the electric arc furnace is operated in the vibration-induced mode for a maximum of 5 minutes within 10 minutes, particularly for a maximum of 4 minutes within 10 minutes, preferably for a maximum of 3 minutes within 10 minutes.

17. The method of operating an electric arc furnace according to any one of claims 12 to 16, wherein the vibration-induced mode is activated simultaneously only for a single electrode of the at least one electrode, particularly for only two electrodes of a plurality of electrodes.

18. The method of operating an electric arc furnace according to any one of claims 12 to 17, wherein the power source supplies power to at least three electrodes such that each of the three electrodes receives a phase.

19. The method of operating an electric arc furnace according to any one of claims 12 to 18, wherein the method further comprises: Reduce the amount of power received by at least one electrode that is not operating in the vibration-induced mode (360).

20. A system for inducing vibration in a metallic material, particularly a waste stockpile, the metallic material being melted in an electric arc furnace, the system comprising: Control unit (140), the control unit being used to control the operation of the electric arc furnace; The control unit is connected to a power supply (110) for supplying power to the electric arc furnace; and is connected to an electrode positioning system (120) for positioning at least one electrode (121) relative to the furnace body (130) containing the metallic material and / or relative to the molten pool level. The control unit (140) is configured to operate the electric arc furnace intermittently in a vibration-induced mode; In the vibration-induced mode, vibration is induced in the metallic material.

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