Symbiotic electric field adopting alternating-current and direct-current mixed electrodes and application of symbiotic electric field

Abstract

The invention relates to the technical field of smelting processes, in particular to a symbiotic electric field adopting alternating-current and direct-current mixed electrodes, more reasonable thermal layer distribution in smelting is achieved through distribution of electric fields generated between alternating-current electrodes and between direct-current electrodes and distribution of electric fields generated between the alternating-current electrodes and the direct-current electrodes, and power consumption is effectively reduced by about 10%. The current path is optimized, the branch current is reduced, the current from the electrode to the bottom end of smelting equipment is effectively increased, the furnace bottom temperature is increased, furnace bottom cooling is avoided, a large-area dead material area is reduced, and comprehensive melting of furnace charge is achieved. Particularly, when the device is applied to a submerged arc furnace, heat layer distribution can effectively reach the bottom of the furnace, a high-temperature area moves downwards, heat dissipation of a charge level is reduced, and unit consumption is reduced; the molten pool develops towards the width, and dead material zones are reduced. Meanwhile, the invention further provides application of the symbiotic electric field adopting the alternating current and direct current mixed electrode in smelting equipment.

Description

Technical Field

[0001] This invention relates to the field of smelting technology, specifically to a symbiotic electric field using AC / DC hybrid electrodes and its application. Background Technology

[0002] Currently, smelting processes typically include a high-temperature melting step. Especially when smelting is carried out using an electric arc furnace, the working characteristic is the use of submerged arc operation, where electrodes are inserted into the furnace charge, and the metal is melted by the resistance heat generated by the electric arc through the furnace charge.

[0003] Currently, the electric arc furnace smelting industry is divided into three types based on the power supply method: industrial frequency AC power supply type, DC power supply type, and low frequency smelting power supply type electric arc furnaces. However, each type also has its own problems.

[0004] (1) The electric arc furnace powered by AC power is the most widely used type of electric arc furnace, especially in traditional industries such as ferroalloys and calcium carbide. The equipment has a simple structure, low initial investment, and controllable maintenance costs. However, under AC power, the electrode voltage drop is large, it is difficult to input active power to the furnace bottom, the electric field between the electrodes is the strongest, most of the current flows through the electrode, the electrodes are difficult to insert deeply, the current flowing through the furnace bottom is very small, the furnace bottom temperature is too low, that is, the distribution of the heat layer of the AC furnace is unreasonable, which leads to the formation of a cold furnace bottom, resulting in difficulties in opening the furnace hole and high production power consumption.

[0005] (2) DC-powered electric arc furnaces are usually equipped with four DC electrodes. There is no electrode voltage drop, which is beneficial for conveying the furnace bottom. However, compared with AC three electrodes, the electrode spacing is smaller, the electric field between electrodes is much higher than the electric field between electrodes and the furnace bottom, and the current flowing through the furnace bottom is still smaller. The four-electrode DC furnace core has no electric arc, the power distribution is unreasonable, and the heat layer cannot effectively reach the furnace bottom. At present, there are still some DC electric arc furnaces equipped with bottom electrodes. However, the construction of high-current bottom electrodes is very difficult, and it is also easy to cause the furnace bottom to burn through, causing greater danger.

[0006] (3) The low-frequency smelting power supply type electric arc furnace is similar to the DC power supply type electric arc furnace, and only three DC electrodes are needed compared with the DC furnace; however, its manufacturing cost is higher, requiring a rectifier transformer and then an IGBT inverter. The problem of low furnace bottom current has not been significantly improved, and both it and the DC power supply type electric arc furnace have the problem of high power consumption.

[0007] Therefore, based on the above problems, it is of great significance to provide a smelting process with a reasonable heat layer distribution and improved furnace bottom power distribution. Summary of the Invention

[0008] The purpose of this invention is to provide a symbiotic electric field using AC and DC hybrid electrodes and its application, so as to solve the existing technical problems in the background art.

[0009] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: On the one hand, this application provides a symbiotic electric field using AC and DC hybrid electrodes, including an AC electric field, a DC electric field and an AC / DC hybrid electric field; The alternating electric field includes at least two alternating electrodes, which are electrically connected to an alternating power source. When energized, the alternating electrodes generate an electric arc, forming a first electric arc channel. The alternating electric field is distributed around the alternating electrodes and within the first electric arc channel. The DC electric field includes at least one DC electrode, which is electrically connected to a DC power source. When energized, the DC electrode generates an electric arc, forming a second electric arc channel. The DC electric field is distributed around the DC electrode and within the second electric arc channel. The AC / DC hybrid electric field is distributed within the third arc channel between the AC electrode and the DC electrode.

[0010] Based on the above technical solution, the first arc channel includes an arc between AC electrodes and between AC electrodes and the molten pool; the second arc channel includes an arc between a DC electrode and the molten pool; and the third arc channel includes an arc between a DC electrode and an AC electrode passing through the molten pool.

[0011] Based on the above technical solution, the current path distribution within the alternating electric field is as follows: The current flows through a star-shaped circuit formed by the AC electrode ends, the electric arc, and the molten pool; The current flows through the side of the AC electrode, through the furnace charge, and through the triangular loop formed by the other two AC electrodes; The current flows through the side of the AC electrode, through the star-shaped circuit formed by the furnace charge and the internal structure of the furnace.

[0012] Based on the above technical solution, the current path distribution within the hybrid electric field is as follows: Current flows from the anode of the DC electrode to the AC electrode, forming a main current path in the vertical direction, and the direction of the electric field is consistent with the direction of the current density.

[0013] Based on the above technical solution, the electric field intensity distribution in the AC electric field is as follows: the electric field intensity expands outward along the end of the AC electrode and decays in a scattering manner; the electric field intensity in the DC electric field is as follows: it gradually decays along the surface of the DC electrode towards the AC electrode.

[0014] Based on the above technical solution, the electric field intensity distribution in the mixed electric field is as follows: the AC electrode serves as the cathode and the DC electrode serves as the anode; along the vertical direction of the mixed electric field, the electric field intensity is relatively constant in the central region; in the boundary region, the electric field intensity increases from the central region to both ends of the electrode.

[0015] Based on the above technical solution, the AC electric field includes three AC electrodes, which are electrically connected to the three phases of the three-phase power supply, respectively.

[0016] Based on the above technical solution, the DC electrode is electrically connected to the DC power supply through an automatic converter.

[0017] On the other hand, this application also provides the application of the aforementioned symbiotic electric field using AC and DC hybrid electrodes in smelting equipment.

[0018] Based on the above technical solution, three AC electrodes are provided and are located at the top inside the smelting equipment, and the AC electrodes are arranged in parallel; the DC electrode is located at the bottom inside the smelting equipment and is below the AC electrodes.

[0019] The beneficial effects of the technical solution provided by this invention are as follows: This invention provides a symbiotic electric field using AC / DC hybrid electrodes. By distributing the electric fields between AC electrodes, between DC electrodes, and between AC and DC electrodes, a more rational heat layer distribution is achieved in smelting, effectively reducing power consumption by approximately 10%. Optimized current paths reduce branch currents, effectively increasing the current from the electrodes to the bottom of the smelting equipment, raising the furnace bottom temperature, preventing a cold furnace bottom, reducing large dead material zones, and achieving complete melting of the furnace charge. Especially when applied in submerged arc furnaces, the heat layer distribution effectively reaches the furnace bottom, the high-temperature zone shifts downward, heat dissipation from the charge surface is reduced, and unit consumption is lowered; the molten pool widens, reducing dead material zones. The invention also provides the application of the aforementioned symbiotic electric field using AC / DC hybrid electrodes in smelting equipment. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the principle of the present invention; Figure 2 This is a schematic diagram of the electric arc distribution in this invention; Figure 3 This is a potential distribution diagram between the top electrode and the bottom electrode inside the furnace body in this invention; Figure 4 Figure 1 is a schematic diagram of the electric field intensity distribution inside the furnace body in this invention; Figure 2a shows the electric field intensity distribution when only AC electrodes are included, and Figure 3b shows the electric field intensity distribution after adding DC electrodes. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments: In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] In the description of this invention, it should be understood that the terms "left", "right", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] like Figures 1 to 4 As shown, a symbiotic electric field employing AC / DC hybrid electrodes includes an AC electric field, a DC electric field, and an AC / DC hybrid electric field. The alternating electric field includes at least two alternating electrodes, which are electrically connected to an alternating power source. When energized, the alternating electrodes generate an electric arc, forming a first electric arc channel. The alternating electric field is distributed around the alternating electrodes and within the first electric arc channel. The DC electric field includes at least one DC electrode, which is electrically connected to a DC power source. When energized, the DC electrode generates an electric arc, forming a second electric arc channel. The DC electric field is distributed around the DC electrode and within the second electric arc channel. The AC / DC hybrid electric field is distributed within the third arc channel between the AC electrode and the DC electrode.

[0024] This invention provides a symbiotic electric field using AC and DC hybrid electrodes. By distributing the electric fields between AC electrodes, between DC electrodes, and between AC and DC electrodes, a more rational heat layer distribution is achieved in smelting, effectively reducing power consumption by approximately 10%. Optimized current paths reduce branch currents, effectively increasing the current from the electrodes to the bottom of the smelting equipment, raising the furnace bottom temperature, preventing a cold furnace bottom, reducing large dead material zones, and achieving complete melting of the furnace charge. Especially when applied in submerged arc furnaces, the heat layer distribution effectively reaches the furnace bottom, the high-temperature zone shifts downwards, heat dissipation from the charge surface is reduced, and unit consumption is lowered; the molten pool widens, reducing dead material zones.

[0025] Based on the above technical solution, the first arc channel includes an arc between AC electrodes and between AC electrodes and the molten pool; the second arc channel includes an arc between a DC electrode and the molten pool; and the third arc channel includes an arc between a DC electrode and an AC electrode passing through the molten pool.

[0026] like Figure 2 As shown, compared with the original AC power supply method, the arc distribution in this application has a narrower arc distribution area between AC electrodes and a lower high-temperature zone, which reduces the original AC power. The arc distribution area between the AC electrode and the molten pool, and between the AC electrode and the DC electrode, is increased, which effectively improves the problem of unreasonable distribution of the heat layer in the original furnace bottom and reduces the dead material area. At the same time, the arc distribution of the DC electrode is increased, which increases the bottom current input and is adjusted in conjunction with the AC input to make the heat layer distribution in the furnace reasonable, reduce energy consumption, and can be achieved without the need to use a high-current DC electrode, thus reducing the safety risk of burn-through at the bottom of the smelting equipment.

[0027] Based on the above technical solution, the current path distribution within the alternating electric field is as follows: The current flows through a star-shaped circuit formed by the AC electrode ends, the electric arc, and the molten pool; The current flows through the side of the AC electrode, through the furnace charge, and through the triangular loop formed by the other two AC electrodes; The current flows through the side of the AC electrode, through the star-shaped circuit formed by the furnace charge and the internal structure of the furnace. The electric arc is considered as a pure resistance, and the internal reactance of the electric furnace and the current passing through the furnace wall are ignored. The internal structure of the furnace can be a structure such as carbon bricks with good conductivity and heat insulation properties.

[0028] Based on the above technical solution, the current path distribution within the hybrid electric field is as follows: The current path distribution within the hybrid electric field is as follows: Current flows from the anode of the DC electrode to the AC electrode, forming a main current path in the vertical direction, and the direction of the electric field is consistent with the direction of the current density.

[0029] The alternating current path is as follows: the power supply flows into the top electrode through the electric furnace transformer and the short grid structure; The DC circuit path is as follows: power is supplied from the electric furnace transformer through an automatic converter, via the external busbar, into the furnace bottom electrode, and then through the furnace charge to the top electrode to form a DC circuit. In this application, the combined arrangement of AC and DC electrodes effectively optimizes the current path, reduces branch current, increases the current from the electrode to the furnace bottom, and simultaneously forms a vertical main current path and a strong electric field zone at the furnace bottom. This achieves effective melting of the furnace charge at the furnace bottom, reduces the dead material zone, and solves the long-standing industry problems of high-temperature zone shifting upwards and cold furnace bottoms in current submerged arc furnaces.

[0030] At this time, the anode of the DC electrode is at a high potential, and the AC electrode is at a low potential; the magnitude of the electric field is related to the magnitude of the applied DC power supply.

[0031] Based on the above technical solution, the electric field intensity distribution in the AC electric field is as follows: the electric field intensity expands outward along the end of the AC electrode and decays in a scattering manner; the electric field intensity in the DC electric field is as follows: it gradually decays along the surface of the DC electrode towards the AC electrode.

[0032] On vertically positioned AC electrodes, both upward and downward movement away from the electrodes result in decreased current density and decreased electric field strength. The AC electric field distribution typically exhibits non-uniformity and three-phase asymmetry. Specifically, the electric field strength shows a significant non-uniform distribution within the furnace space, mainly concentrated in the region near the electrodes and in the arc channel. The electric field strength is greatest at the electrode tip due to extremely high current density, gradually decreasing with distance from the electrode. In a three-phase AC submerged arc furnace, the electric field distribution between the three-phase electrodes may exhibit asymmetry due to the influence of electrode arrangement, differences in the conductivity of the furnace charge, and current imbalance.

[0033] The electric field distribution of the DC electrode gradually decreases towards the AC electrode along its surface and is not completely uniform. Its distribution pattern depends primarily on factors such as the electrode shape and size, and the distribution of the conductive medium between the electrodes. Different electrode geometries result in denser electric field lines at the electrode edges and tips; the electric field gradually decreases in areas farther from the electrode. The reaction state within the furnace is not completely uniform. As the controllable DC electric field increases, the molten pool expands, simultaneously enhancing the uniformity of the DC electric field. As mentioned above, the electric field generated by the AC electrode exhibits non-uniformity and three-phase asymmetry. With the total power input to the furnace remaining unchanged, the DC electric field of the bottom electrode can be increased in real-time through AC-DC hybrid electric field control. This correspondingly reduces the original AC electric field, improving both asymmetry and non-uniformity.

[0034] Adjustment of the AC electric field: By adjusting the depth of the AC electrodes and the distance between them and the DC electrodes, the distribution of the AC electric field and the current path within the AC electric field are regulated. The furnace body is divided into a molten pool zone, an arc zone, and a solid charge zone from bottom to top. The distribution of electric field intensity in each zone is as follows: Arc zone (between electrodes or between electrodes and the molten pool): High and concentrated electric field intensity; the high conductivity of the arc plasma leads to extremely high local current density; Molten pool zone (liquid charge): Good conductivity; relatively uniform electric field distribution; local disturbances occur due to the flow of the molten pool; Solid charge zone: Poor conductivity; large electric field gradient; tortuous current path. By adding a DC electrode at the bottom, the area of ​​the solid charge zone at the bottom can be reduced, the branch current can be reduced, a main current path can be formed in the vertical direction, the DC electric field intensity can be enhanced, the original electric field gradient can be reduced, the charge can be fully melted, a cold furnace bottom can be avoided, the smelting effect can be improved, and the unit consumption can be effectively reduced.

[0035] Based on the above technical solution, the electric field intensity distribution in the mixed electric field is as follows: the AC electrode serves as the cathode and the DC electrode serves as the anode; along the vertical direction of the mixed electric field, the electric field intensity is relatively constant in the central region; in the boundary region, the electric field intensity increases from the central region to both ends of the electrode.

[0036] like Figure 4 As shown in the figure, Figure a is the electric field intensity distribution inside the furnace without a bottom electrode, and Figure b is the electric field intensity distribution inside the furnace after the addition of a bottom DC electrode. The comparison shows that by setting a DC electrode at the bottom, a potential difference is formed between the anode and cathode of the DC electrode through the conductive material in the molten pool. The current is conducted through the furnace charge, forming a vertical main current path and a strong electric field area at the bottom of the furnace. This is different from the situation in traditional AC-powered submerged arc furnaces where the arc current between horizontal electrodes is the main component and the vertical arc is weak. This effectively reduces the dead material area at the bottom of the furnace and avoids the phenomenon of a cold furnace bottom.

[0037] In a hybrid electric field, the electric field intensity distribution is influenced by both AC and DC electrodes. Near the AC electrode, the electric field is weaker due to the outward decay of the AC field; near the DC electrode, it is stronger due to the enhanced electric field at the boundary region of the DC field. The area between the two electrodes is a transition zone where the electric field intensity changes gradually. This transition zone can be optimized by adjusting the AC and DC power supply parameters, resulting in more complete heating and reaction of the furnace charge. Compared to existing technologies, this application exhibits a significant advantage in electric field distribution. In traditional industrial frequency AC submerged arc furnaces, the electric field is concentrated between the electrodes, resulting in a weak electric field at the furnace bottom and poor heat layer distribution. The hybrid electric field of this invention provides a more rational electric field distribution within the furnace, shifting the high-temperature zone downwards, reducing heat dissipation from the charge surface, increasing the furnace bottom temperature, reducing the dead material zone, and optimizing the smelting effect.

[0038] Specifically, based on the potential distribution, it can be divided into 3 regions, as follows: Figure 3As shown, the electric field strength increases sharply in the boundary region, i.e., near the cathode and anode, while there is a fairly constant field at the center of most arcs. In low-current arcs, electron emission usually begins with field emission; in high-current arcs, thermionic emission dominates due to the large amount of current flowing through the electrodes.

[0039] Based on the above technical solution, the AC electric field includes three AC electrodes, which are electrically connected to the three phases of the three-phase power supply, respectively.

[0040] Based on the above technical solution, the DC electrode is electrically connected to a DC power supply via an automatic converter. The automatic converter rectifies the AC power into DC power and can also change the magnitude of the DC power. By applying external DC power, the furnace bottom current is increased, enhancing the DC electric field at the furnace bottom and expanding the bottom molten pool. This raises the furnace bottom temperature, avoids a cold furnace bottom, reduces large dead material zones, and achieves complete melting of the furnace charge.

[0041] On the other hand, this application also provides the application of the aforementioned symbiotic electric field using AC and DC hybrid electrodes in smelting equipment.

[0042] More preferably, the smelting equipment is a submerged arc furnace; it is suitable for retrofitting old furnaces without changing the original transformer, electrodes and short grid structure, thus saving investment.

[0043] Based on the above technical solution, three AC electrodes are provided and are located at the top inside the smelting equipment, and the AC electrodes are arranged in parallel; the DC electrode is located at the bottom inside the smelting equipment and is below the AC electrodes.

[0044] In a preferred embodiment, particularly in the application of electric arc furnaces, the AC electrodes are arranged in parallel at the top of the furnace interior, while the DC electrodes are positioned at the bottom. This ensures that the heat layer distribution effectively reaches the furnace bottom, lowers the high-temperature zone, reduces heat dissipation from the material surface, and is expected to reduce smelting power consumption by 10%. The optimized current path effectively increases the current from the electrodes to the furnace bottom while reducing branch current. The presence of a bottom DC electrode increases the furnace bottom temperature, widens the molten pool, and reduces dead material zones. More preferably, by measuring the voltage from each AC electrode to the DC electrode at the furnace bottom, the distance from each AC electrode to the furnace bottom can be accurately determined, achieving more precise furnace temperature control. Even more preferably, even when the bottom electrode is not in operation, the furnace can continue to operate as before, without affecting production, demonstrating excellent practical performance.

[0045] It should also be noted that the AC and DC electrode hybrid smelting method and working principle in this application can be applied not only to electric arc furnaces, but also to other smelting scenarios that require high-temperature smelting, demonstrating strong applicability.

[0046] The foregoing has shown and described the basic principles and main features of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments. Therefore, the embodiments should be considered as exemplary and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the present invention.

[0047] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A symbiotic electric field employing AC / DC hybrid electrodes, characterized in that, It includes an alternating electric field, a direct electric field, and a hybrid alternating and direct electric field; The alternating electric field includes at least three alternating electrodes, which are electrically connected to an alternating power source. When energized, the alternating electrodes generate an electric arc, forming a first electric arc channel. The alternating electric field is distributed around the alternating electrodes and within the first electric arc channel. The DC electric field includes at least one DC electrode, which is electrically connected to a DC power source. When energized, the DC electrode generates an electric arc, forming a second electric arc channel. The DC electric field is distributed around the DC electrode and within the second electric arc channel. The AC / DC hybrid electric field is distributed within the third arc channel between the AC electrode and the DC electrode.

2. The symbiotic electric field employing AC / DC hybrid electrodes according to claim 1, characterized in that, The first arc channel includes the arc between AC electrodes and between AC electrodes and the molten pool; the second arc channel includes the arc between DC electrodes and the molten pool; and the third arc channel includes the arc between DC electrodes and AC electrodes through the molten pool.

3. The symbiotic electric field employing AC / DC hybrid electrodes according to claim 1, characterized in that, The current path distribution within the alternating electric field is as follows: The current flows through a star-shaped circuit formed by the AC electrode ends, the electric arc, and the molten pool; The current flows through the side of the AC electrode, through the furnace charge, and through the triangular loop formed by the other two AC electrodes; The current flows through the side of the AC electrode, through the star-shaped circuit formed by the furnace charge and the internal structure of the furnace.

4. The symbiotic electric field employing AC / DC hybrid electrodes according to claim 1, characterized in that, The current path distribution within the hybrid electric field is as follows: Current flows from the anode of the DC electrode to the AC electrode, forming a main current path in the vertical direction, and the direction of the electric field is consistent with the direction of the current density.

5. A symbiotic electric field employing AC / DC hybrid electrodes according to claim 1, characterized in that, The electric field intensity distribution in the AC electric field is as follows: the electric field intensity expands outward along the end of the AC electrode and decreases in a scattering manner; the electric field intensity in the DC electric field is as follows: it gradually decreases along the surface of the DC electrode towards the AC electrode.

6. The symbiotic electric field employing AC / DC hybrid electrodes according to claim 1, characterized in that, The electric field intensity distribution within the mixed electric field is as follows: the AC electrode acts as the cathode, and the DC electrode acts as the anode; along the vertical direction of the mixed electric field, the electric field intensity is relatively constant in the central region; in the boundary region, the electric field intensity increases from the central region towards both ends of the electrode.

7. A symbiotic electric field employing AC / DC hybrid electrodes according to claim 1, characterized in that, The alternating current field includes three alternating current electrodes, which are electrically connected to the three phases of the three-phase power supply, respectively.

8. The symbiotic electric field employing AC / DC hybrid electrodes according to claim 1, characterized in that, The DC electrode is electrically connected to a DC power supply via an automatic converter.

9. The application of a symbiotic electric field employing AC / DC hybrid electrodes as described in any one of claims 1 to 8 in a smelting apparatus.

10. The application of a symbiotic electric field using AC / DC hybrid electrodes in smelting equipment according to claim 9, characterized in that, The AC electrodes are provided in three places and are located at the top inside the smelting equipment, and the AC electrodes are arranged in parallel; the DC electrodes are located at the bottom inside the smelting equipment and are located below the AC electrodes.

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