Smelting system adopting alternating current and direct current mixed smelting

Abstract

The invention relates to the technical field of smelting equipment, in particular to a smelting system adopting alternating current and direct current mixed smelting, which at least comprises a furnace body, an electrode device and a power supply device, three alternating-current electrodes are arranged in a furnace body to serve as top electrodes, a direct-current electrode serves as a furnace bottom electrode for cooperation, electric arcs are generated after electrification to heat and melt furnace charge, in the smelting process, heat layer distribution can effectively reach the furnace bottom, a high-temperature area moves downwards, heat dissipation of the charge surface is reduced, and smelting power consumption is predicted to be reduced by 10%; the current path is optimized, the current from the electrode to the furnace bottom is effectively increased, and the branch current is reduced; by arranging the furnace bottom electrode, the furnace bottom temperature is increased, a molten pool develops towards the width, and dead material areas are reduced; and the distance from each electrode to the furnace bottom can be accurately judged by measuring the voltage from each top electrode to the furnace bottom electrode, so that more accurate furnace control is realized.

Description

Technical Field

[0001] This invention relates to the field of smelting equipment technology, and more specifically to a smelting system employing AC / DC hybrid smelting. Background Technology

[0002] Currently, in the metallurgical industry, submerged arc furnaces, also known as electric arc furnaces or resistance furnaces, are widely used as industrial equipment for reducing and smelting raw materials such as ores, carbonaceous reducing agents, and solvents. They are suitable for smelting various metallic and non-metallic minerals and are also important industrial raw material production equipment in the metallurgical industry, as well as for producing chemical raw materials such as calcium carbide. Submerged arc furnaces directly convert electrical energy into heat energy, exhibiting high energy conversion efficiency. Based on the power supply method, they are classified into AC power supply type, DC power supply type, and low-frequency smelting power supply type submerged arc furnaces, but each type also has its own certain problems.

[0003] Submerged arc furnaces powered by industrial frequency AC: This is currently the most widely used type of submerged arc furnace, accounting for about 90% of the total number of submerged arc furnaces, 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 industrial frequency AC input, the electrode voltage drop is large, making it difficult to input active power to the furnace bottom. Moreover, because the electric field between the electrodes is the strongest, most of the current flows through the electrode space, making it difficult to insert the electrodes deeply. The current flowing through the furnace bottom is very small, resulting in an excessively low furnace bottom temperature. This means that the heat layer distribution of the AC furnace is unreasonable, leading to a cold furnace bottom. Consequently, the furnace bottom has poor material flow, making it difficult to open the furnace hole and resulting in high power consumption. At the same time, there are also significant eddy current losses and harmonic problems.

[0004] DC-powered submerged arc furnaces: Their use has grown rapidly in recent years, accounting for about 5%-10% of the total number of submerged arc furnaces. They are usually equipped with four DC electrodes. The DC arc has no current zero-crossing point, and the arc length and input power are more stable. Compared with AC power supply, there is no electrode voltage drop and material loss, which is beneficial for conveying the furnace bottom. However, compared with AC three-electrode furnaces, the electrode spacing is smaller. The four-electrode DC furnace core has no arc, the power distribution is unreasonable, the current flowing through the furnace bottom is still too small, and the heat layer cannot effectively reach the furnace bottom. At present, there are still some DC submerged arc furnaces equipped with bottom electrodes. However, the construction of high-current bottom electrodes is extremely difficult, and it is also easy to cause the furnace bottom to burn through, which poses a higher safety hazard.

[0005] Low-frequency smelting power supply type electric arc furnace has similar advantages to DC power supply type electric arc furnace, and compared with DC power supply type electric arc furnace, it only needs three DC electrodes; however, due to the need for rectifier transformer and then IGBT inverter, its manufacturing cost is very high, and the problem of low furnace bottom current has not been significantly improved. At the same time, both it and DC power supply type electric arc furnace have the problem of high power consumption.

[0006] Therefore, it is of great significance to study a smelting system with a reasonable heat layer distribution and improved power distribution at the furnace bottom. Summary of the Invention

[0007] The purpose of this invention is to provide a smelting system employing AC / DC hybrid smelting to solve the existing technical problems described in the background section.

[0008] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: a smelting system using AC / DC hybrid smelting is provided, which includes at least a furnace body, an electrode device and a power supply device. The electrode device is installed inside the furnace body. When energized, it conducts current into the furnace charge to generate resistance heat. The electrode device includes a top electrode and a bottom electrode. At least three top electrodes are provided and arranged in parallel. At least one bottom electrode is provided and is located below the top electrode. The power supply device is electrically connected to the top electrode and the bottom electrode, providing AC power to the top electrode and DC power to the bottom electrode.

[0009] Based on the above technical solution, the power supply device includes an electric furnace transformer connected to the power grid, a DC power supply component electrically connected to the furnace bottom electrode, and an AC power supply component electrically connected to the top electrode. The DC power supply component includes an automatic converter, an external busbar, and a connection terminal connected in sequence, and the connection terminal is electrically connected to the bottom electrode of the furnace. The AC power supply component includes a short grid structure electrically connected to the top electrode.

[0010] Based on the above technical solution, the current path between the top electrode and the bottom electrode is as follows: The power supply device supplies power to the top electrode via a short grid structure through an electric furnace transformer; The power supply device consists of an electric furnace transformer that passes through an automatic converter and flows into the furnace bottom electrode via the external busbar, and then through the furnace charge and top electrode to form a DC circuit. Current flows from the anode of the bottom electrode to the top electrode, forming a main current path in the vertical direction.

[0011] Based on the above technical solution, the top electrode serves as the cathode, the bottom electrode serves as the anode, and the electric field intensity distribution is such that 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.

[0012] Based on the above technical solution, three top electrodes are arranged in a triangular pattern inside the furnace body.

[0013] Based on the above technical solution, the furnace bottom electrodes are arranged in multiple ways at the bottom of the furnace body and are evenly distributed along the circumference of the furnace body.

[0014] Based on the above technical solution, two furnace bottom electrodes are correspondingly arranged below each top electrode, and the furnace bottom electrode is provided with an included angle at the end near the top electrode.

[0015] Based on the above technical solution, the end of the furnace bottom electrode closest to the top electrode is set as the anode, and the end furthest from the top electrode is set as the cathode.

[0016] Based on the above technical solution, a cable outlet is provided on the side wall of the furnace body, the connection end of the furnace bottom electrode is located at the cable outlet, and a cooling device is provided on the furnace bottom electrode and located on the outside of the furnace body.

[0017] Based on the above technical solution, the connection end includes a conductive plate and an external busbar. The external busbar is electrically connected to the furnace bottom electrode. The conductive plate is sleeved on the outside of the furnace bottom electrode and presses the external busbar and the furnace bottom electrode together.

[0018] Based on the above technical solution, the cooling device is configured as a cooling water pipe, and a cooling groove is opened at one end of the furnace bottom electrode located on the outside of the furnace body. Multiple cooling water pipes are arranged in the cooling groove, and circulating cooling water is circulated in the cooling water pipes.

[0019] Based on the above technical solution, both the top electrode and the bottom electrode are made of graphite.

[0020] The beneficial effects of the technical solution provided by this invention are as follows: 1. This invention provides a smelting system employing a hybrid AC / DC smelting process. By using three AC electrodes as top electrodes and one DC electrode as the bottom electrode within the furnace body, an electric arc is generated upon energization to heat and melt the furnace charge. During the smelting process, the heat distribution can effectively reach the furnace bottom, the high-temperature zone shifts downward, heat dissipation from the charge surface is reduced, and smelting power consumption is expected to decrease by 10%. The current path is optimized, effectively increasing the current from the electrodes to the furnace bottom and reducing branch current. The presence of the bottom electrode increases the furnace bottom temperature, widens the molten pool, and reduces dead material areas. Furthermore, by measuring the voltage from each top electrode to the bottom electrode, the distance from each electrode to the furnace bottom can be accurately determined, enabling more precise furnace control.

[0021] 2. By setting the furnace bottom electrodes to a side-entry / exit configuration, damage to the original furnace structure can be minimized, preserving the existing temperature structure and making modifications to the current furnace structure more convenient while also considering modification costs. Furthermore, the side-exit configuration reduces potential safety risks associated with bottom-mounted electrodes, resulting in higher safety. Simultaneously, placing the cooling device at the outlet end allows for water cooling due to the side-exit design, offering convenient operation, rapid cooling, and high safety. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the circuit control principle of the present invention; Figure 3 This is a schematic diagram of the arc distribution of the top electrode and the bottom electrode in this invention; Figure 4 This is a potential distribution diagram between the top electrode and the bottom electrode inside the furnace body in this invention; Figure 5 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.

[0023] Figure 6 This is a schematic diagram of the internal cross-sectional structure of the furnace body of the present invention; Figure 7 This is a top view of the furnace bottom electrode inside the furnace body in this invention; Figure 8 This is a schematic diagram of the connection end of the furnace bottom electrode in this invention; Detailed Implementation 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.

[0024] 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.

[0025] like Figures 1 to 8 As shown, a smelting system employing AC / DC hybrid smelting includes at least a furnace body 1, an electrode device, and a power supply device. The electrode device is installed inside the furnace body 1. When energized, it conducts current into the furnace charge to generate resistance heat. The electrode device includes a top electrode 2 and a bottom electrode 3. At least three top electrodes 2 are provided and arranged in parallel. At least one bottom electrode 3 is provided and is located below the top electrode 1. The power supply device is electrically connected to the top electrode 2 and the bottom electrode 3, providing AC power to the top electrode 2 and DC power to the bottom electrode 3.

[0026] This invention provides a smelting system employing a hybrid AC / DC smelting method. Three AC electrodes (top electrodes 2) and one DC electrode (bottom electrode 3) are arranged within the furnace body 1 in a coordinated manner. The electric fields generated between the AC electrodes, between the DC electrodes, and between the AC and DC electrodes are distributed to generate an electric arc upon energization, heating and melting the furnace charge. During the smelting process, the heat layer distribution can effectively reach the furnace bottom, the high-temperature zone shifts downward, heat dissipation from the charge surface is reduced, and smelting power consumption is expected to decrease by 10%. The current path is optimized, effectively increasing the current from the electrodes to the furnace bottom and reducing branch current. The presence of the bottom electrode increases the furnace bottom temperature, widens the molten pool, and reduces dead material areas. Furthermore, by measuring the voltage from each top electrode to the bottom electrode, the distance from each electrode to the furnace bottom can be accurately determined, enabling more precise furnace control. More preferably, when the bottom electrode is not in operation, the furnace can continue to operate as before, without affecting production.

[0027] The improved smelting system described in this application exhibits superior practicality in terms of structural improvements. Based on the working principle of the smelting system, an additional bottom electrode and corresponding power supply are added to the structure of an AC-powered submerged arc furnace. This is particularly suitable for retrofitting existing furnaces, without altering the original transformer, top electrode, and short grid structure, thus saving investment. It is understood that while the fundamental invention is manifested in the addition of corresponding structures at the structural level, it also possesses more innovative improvements at the principle level. For example, the adjustable DC circuit of the bottom electrode 3, combined with the use of a high thermal resistance carbon brick bottom, not only increases the bottom temperature but also effectively protects the bottom, balancing conductivity efficiency and safety, among other performance aspects.

[0028] Based on the above technical solution, the power supply device includes an electric furnace transformer 4 connected to the power grid, a DC power supply component electrically connected to the furnace bottom electrode 3, and an AC power supply component electrically connected to the top electrode. The DC power supply assembly includes an automatic converter 5, an external busbar 6, and a connection terminal 7 connected in sequence. The connection terminal 7 is electrically connected to the furnace bottom electrode 3. The AC power supply component includes a short grid structure 8 electrically connected to the top electrode 2.

[0029] Based on the above technical solution, the current path between the top electrode 2 and the bottom electrode 3 is as follows: The power supply device flows into the top electrode 2 through the electric furnace transformer 4 and the short network structure 8; The power supply device consists of an electric furnace transformer 4, an automatic converter 5, an external busbar 6, and flows into the furnace bottom electrode 3. The power supply then passes through the furnace charge and the top electrode 2 to form a DC circuit. The current flows from the anode of the bottom electrode 3 to the top electrode 2, forming a main current path in the vertical direction.

[0030] This application utilizes a combination of AC and DC electrodes to effectively optimize the current path, reduce branch current, and increase the current from the electrodes to the furnace bottom. Simultaneously, it creates a vertical main current path and a strong electric field zone at the furnace bottom, achieving effective melting of the furnace charge at the bottom, reducing the dead material zone, and solving the long-standing industry problems of high-temperature zone shifting upwards and cold furnace bottoms in current submerged arc furnaces. Furthermore, it allows for dynamic potential control of the furnace bottom electrodes. An automatic converter 5 rectifies the AC current into DC current and can adjust the magnitude of the DC current. Applying external DC current increases the furnace bottom current and strengthens the DC electric field at the furnace bottom, expanding the bottom molten pool. This raises the furnace bottom temperature, prevents a cold furnace bottom, reduces large dead material zones, and achieves complete melting of the furnace charge. It should be noted that the aforementioned electric furnace transformer, short-network structure, and automatic converter can be obtained from existing technologies, and this application does not involve any improvement to their specific structures.

[0031] The dynamic control of the furnace bottom electrode includes: continuously adjusting the DC current of the furnace bottom electrode according to a set logic using an automatic converter 5, preferably a thyristor rectifier module; if the potential difference in a certain area is abnormal, such as an increase in resistance in the dead material area of ​​the furnace bottom, increasing the current of the bottom electrode in that direction to enhance the local electric field strength; if the overall conductivity of the furnace charge is improved, reducing the current to avoid overheating of the furnace bottom. Through current adjustment, the transmission of the vertical current main path, i.e., the current path from the furnace bottom electrode to the furnace charge to the top electrode, is strengthened, the horizontal branch current between the electrodes is suppressed, and the heat flow is driven downward by the vertical electric field, achieving the technical effect of "moving the high-temperature zone downward and reducing heat dissipation from the material surface".

[0032] The alternating current (AC) electric field is distributed around the AC electrode and within the first arc channel; the direct current (DC) electric field is distributed around the DC electrode and within the second arc channel; the mixed AC / DC electric field is distributed within the third arc channel between the AC and DC electrodes. The first arc channel includes the arc between the AC electrodes and between the AC electrode and the molten pool; the second arc channel includes the arc between the DC electrode and the molten pool; and the third arc channel includes the arc between the AC and DC electrodes. Figure 3 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.

[0033] Based on the above technical solution, the top electrode 2 serves as the cathode, the bottom electrode 3 serves as the anode, and the electric field intensity distribution is such that 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.

[0034] A bottom electrode 3 is installed at the bottom of the furnace body 1, which cooperates with an AC electrode at the top of the furnace body 1. The bottom electrode 3 is the anode, and the top electrode 2 is the cathode. The electric field distribution is as follows: Figure 4 As shown, a potential difference is formed between the anode and cathode of the DC electrode through the conductive material in the molten pool. Current is conducted through the material, forming a main current path in the vertical direction. This is different from the situation in traditional AC-powered submerged arc furnaces where the arc current between horizontal electrodes is the main current and the vertical arc is weak. This effectively reduces the dead material zone at the bottom of the furnace, realizes the main vertical current path and the strong electric field zone at the bottom of the furnace, and solves the long-standing problems of hot layer upward movement and cold slagging at the bottom of the furnace in the industry.

[0035] like Figure 5 As shown in the figure, Figure a is the electric field intensity distribution inside the furnace without bottom electrodes, and Figure b is the electric field intensity distribution inside the furnace after the addition of bottom electrodes. The comparison shows that by setting DC electrodes at the bottom, a potential difference is formed between the anode and cathode of the DC electrodes 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 bottom.

[0036] 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.

[0037] Based on the above technical solution, three top electrodes 2 are arranged in a triangular pattern inside the furnace body 1.

[0038] Based on the above technical solution, the furnace bottom electrode 3 is provided at the bottom of the furnace body 1, and multiple electrodes are arranged evenly along the circumference of the furnace body.

[0039] Based on the above technical solution, two furnace bottom electrodes 3 are provided below each top electrode 2, and the furnace bottom electrode 3 is provided with an angle at the end near the top electrode 2.

[0040] This design allows for effective heating of the furnace bottom, which is beneficial for arc distribution between the bottom and top electrodes. On the other hand, it effectively avoids the manufacturing of high-current furnace bottom electrodes, making the bottom electrodes safer.

[0041] It is understood that the furnace body 1 is provided with a furnace bottom structure, and the furnace bottom structure is provided with high thermal resistance carbon bricks and heat insulation material, and the furnace bottom electrode is provided on the high thermal resistance carbon bricks.

[0042] Preferably, the insulation layer material is a heat-insulating fiber material such as ceramic fiberboard.

[0043] Based on the above technical solution, the end of the furnace bottom electrode 3 closest to the top electrode 2 is set as the anode, and the end furthest from the top electrode 2 is set as the cathode.

[0044] In a preferred embodiment, by setting the anode of the bottom DC electrode on the side close to the top AC electrode, a situation is formed where the bottom is the anode and the top is the cathode. The anode effect makes the anode do more work than the cathode, resulting in the temperature around the anode being higher than that of the cathode. This is beneficial for raising the temperature at the bottom of the furnace and for the rational distribution of the heat layer inside the furnace.

[0045] Based on the above technical solution, a cable outlet 9 is provided on the side wall of the furnace body 1, the connection end 7 of the furnace bottom electrode 3 is provided at the cable outlet 9, and a cooling device is provided on the furnace bottom electrode 3 and located outside the furnace body 1.

[0046] Based on the above technical solution, the connection end 7 includes an external busbar 71 and a conductive plate 72. The external busbar 71 is electrically connected to the furnace bottom electrode 72. The conductive plate 72 is sleeved on the outside of the furnace bottom electrode 3 and presses the external busbar 71 and the furnace bottom electrode 3 together.

[0047] The external busbar 71 is a conductive copper busbar. In a preferred embodiment, the furnace bottom electrode 3 is typically a molded graphite electrode, which cannot be directly connected to the external conductive busbar, i.e., the external busbar. Therefore, by providing a connection end, it serves as a transition during the electrical connection between the furnace bottom electrode and the external busbar, facilitating installation, ensuring good connection stability, and providing high safety. Specifically, a conductive plate 72 is fitted around the furnace bottom electrode 3, and connection holes are provided on the conductive plate 72. The external busbar 71 and the conductive plate 72 are fixed by fasteners installed in the connection holes, thereby pressing the external busbar 71 and the furnace bottom electrode 3 together. After energization, current is input to the furnace bottom electrode 3.

[0048] Based on the above technical solution, the cooling device is configured as a cooling water pipe, and a cooling groove is opened at one end of the furnace bottom electrode located on the outside of the furnace body. Multiple cooling water pipes are arranged in the cooling groove, and circulating cooling water is circulated in the cooling water pipes.

[0049] In a preferred embodiment, the furnace bottom electrode is cooled by a water-cooling system. Specifically, a long groove is formed at the end of the furnace bottom electrode, into which a stainless steel pipe is embedded as a cooling water pipe. Heat is carried away by flowing cooling water, and the water channel interfaces are strictly sealed. More preferably, the cooling water pipes can be arranged in a spiral pattern to extend the flow path of the cooling water, improve the cooling effect, and increase safety.

[0050] In another preferred embodiment, the cooling device is configured as a cooling water jacket, which includes an outer shell, a water jacket body, an inlet, and an outlet. The outer shell is fitted onto the water jacket body, and the inlet and outlet are respectively located on the water jacket body and communicate with the cooling water channels inside the water jacket body. More preferably, the cooling water channels are arranged in a spiral shape.

[0051] More preferably, an insulating layer and a sealing layer are provided between the furnace bottom electrode 3 and the cooling water jacket. The insulating layer can effectively prevent short circuits of the electrode, and the sealing layer can effectively prevent water leakage from the cooling water jacket, thus preventing danger when the electrode is at a high temperature.

[0052] By setting a water-cooling structure on the outside of the furnace bottom electrode 3, that is, by setting circulating cooling water in the cooling water channel, the electrode can be cooled down quickly, effectively preventing the electrodes located outside the furnace, especially the graphite electrodes, from oxidizing or burning at high temperatures, thus reducing safety hazards.

[0053] By setting the furnace bottom electrode 3 to a side-entry / exit configuration, damage to the original furnace structure can be reduced, preserving the existing temperature structure and making modifications to the existing furnace structure more convenient and cost-effective. Furthermore, the side exit configuration reduces potential safety risks associated with placing the electrode at the furnace bottom, resulting in higher safety. Simultaneously, placing the cooling device at the exit end allows for water cooling due to the side exit configuration of the furnace bottom electrode, offering convenient operation, rapid cooling, and high safety. Compared to placing the furnace bottom electrode's exit end at the bottom, which could lead to an explosion due to water cooling in the event of furnace bottom burn-through, this application inherently prevents the use of a high-current DC electrode at the furnace bottom through the combination of AC and DC electrodes, reducing the risk of furnace bottom burn-through. Furthermore, placing the furnace bottom electrode's exit end on the side of the furnace body ensures that even with water cooling, there are no explosion risks, thus further enhancing safety.

[0054] Based on the above technical solution, both the top electrode 2 and the bottom electrode 3 are graphite electrodes.

[0055] Preferably, both the top electrode 2 and the bottom electrode 3 are made of graphite electrodes, which have excellent conductivity and high temperature resistance, can work at extremely high temperatures, and have low resistivity, effectively reducing energy loss.

[0056] 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.

[0057] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification 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 smelting system employing AC / DC hybrid smelting, characterized in that, It includes at least a furnace body, an electrode device, and a power supply device; The electrode device is installed inside the furnace body. When energized, it conducts current into the furnace charge to generate resistance heat. The electrode device includes a top electrode and a bottom electrode. At least three top electrodes are provided and arranged in parallel. At least one bottom electrode is provided and is located below the top electrode. The power supply device is electrically connected to the top electrode and the bottom electrode, providing AC power to the top electrode and DC power to the bottom electrode.

2. The smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, The power supply device includes an electric furnace transformer connected to the power grid, a DC power supply component electrically connected to the furnace bottom electrode, and an AC power supply component electrically connected to the top electrode. The DC power supply component includes an automatic converter, an external busbar, and a connection terminal connected in sequence, and the connection terminal is electrically connected to the bottom electrode of the furnace. The AC power supply component includes a short grid structure electrically connected to the top electrode.

3. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, The current path between the top electrode and the bottom electrode is as follows: The power supply device supplies power to the top electrode via a short grid structure through an electric furnace transformer; The power supply device consists of an electric furnace transformer that passes through an automatic converter and flows into the furnace bottom electrode via the external busbar, and then through the furnace charge and top electrode to form a DC circuit. Current flows from the anode of the bottom electrode to the top electrode, forming a main current path in the vertical direction.

4. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, The top electrode serves as the cathode, the bottom electrode serves as the anode, and the electric field intensity distribution is such that the electric field intensity is relatively constant in the central region. In the boundary region, the electric field strength increases from the central region towards both ends of the electrode.

5. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, The top electrode is arranged in a triangular pattern on the upper part of the furnace body.

6. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, The furnace bottom electrodes are arranged in multiples at the bottom of the furnace body and are evenly distributed along the circumference of the furnace body.

7. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, Two furnace bottom electrodes are provided below each top electrode, and the furnace bottom electrodes are provided with an included angle at the end near the top electrode.

8. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, The end of the furnace bottom electrode closest to the top electrode is set as the anode, and the end furthest from the top electrode is set as the cathode.

9. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, The furnace body has a cable outlet on its side wall, and the connection end of the furnace bottom electrode is located at the cable outlet. The furnace bottom electrode is equipped with a cooling device located on the outside of the furnace body.

10. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, The connection end includes a conductive plate and an external busbar. The external busbar is electrically connected to the furnace bottom electrode. The conductive plate is sleeved on the outside of the furnace bottom electrode and presses the external busbar and the furnace bottom electrode together.

11. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, The cooling device is configured as a cooling water pipe. A cooling groove is provided at one end of the furnace bottom electrode located on the outside of the furnace body. Multiple cooling water pipes are provided in the cooling groove, and circulating cooling water is circulated in the cooling water pipes.

12. A smelting system employing AC / DC hybrid smelting according to claim 1, characterized in that, Both the top electrode and the bottom electrode are made of graphite.

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