Alternating current and direct current mixed arc heat structure and smelting device

Abstract

The utility model relates to the technical field of smelting equipment, in particular to an alternating-current and direct-current mixed arc thermal structure, which is characterized in that alternating-current electrodes and direct-current electrodes are matched with each other, and particularly, electric fields generated between the alternating-current electrodes and between the direct-current electrodes and electric arcs generated between the alternating-current electrodes and the direct-current electrodes are utilized. More reasonable heat layer distribution in smelting is realized, and the 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.

Description

Technical Field

[0001] This utility model relates to the field of smelting equipment technology, specifically to an AC / DC hybrid electric arc heating structure and smelting device. Background Technology

[0002] In smelting equipment, submerged arc furnaces directly convert electrical energy into heat energy, exhibiting high energy conversion efficiency. They are widely used in the smelting of various metals and non-metallic minerals and are also important industrial raw material production equipment in the metallurgical industry. Based on the power supply method, they are classified into AC-powered and DC-powered submerged arc furnaces. AC-powered submerged arc furnaces are currently the most widely used type, accounting for approximately 90% of all submerged arc furnaces, especially dominating traditional industries such as ferroalloys and calcium carbide. They feature simple structure, low initial investment, and controllable maintenance costs. However, under AC input, the electrode voltage drop is large, making it difficult to input active power to the furnace bottom. Furthermore, due to the strongest electric field between the electrodes, most of the current flows between them, making it difficult to deeply insert the electrodes. The current flowing through the furnace bottom is very small, resulting in an excessively low furnace bottom temperature. This indicates an unreasonable distribution of the heat layer in the AC furnace, leading to a cold furnace bottom problem. DC-powered submerged arc furnaces have seen rapid development in recent years, accounting for approximately 5%-10% of the total number of submerged arc furnaces. These furnaces typically have four DC electrodes. The DC arc has no current zero-crossing point, resulting in more stable arc length and input power. Compared to AC power supply, there is no electrode voltage drop or material loss, which is beneficial for conveying the furnace bottom. However, compared to AC three-electrode furnaces, the electrode spacing is smaller, and the four-electrode DC furnace lacks an arc in the furnace core, leading to an unreasonable power distribution and insufficient current flowing through the furnace bottom, preventing the heat layer from effectively reaching the bottom. Currently, some DC submerged arc furnaces with DC electrodes still exist, but constructing high-current DC electrodes is extremely difficult and prone to causing furnace bottom burn-through, posing a higher safety hazard. Therefore, researching a smelting device with a reasonable heat layer distribution and improved power distribution at the furnace bottom is of great significance. Utility Model Content

[0003] The purpose of this invention is to provide a hybrid AC / DC arc heating structure to solve the existing technical problems in the background art.

[0004] To solve the above-mentioned technical problems, the technical solution provided by this utility model is as follows:

[0005] On one hand, this application provides a hybrid AC / DC arc heating structure, including AC electrodes, DC electrodes, and a power supply assembly. Multiple AC electrodes are arranged in parallel, and DC electrodes are correspondingly arranged below the AC electrodes. The power supply assembly is electrically connected to both the AC and DC electrodes. The power supply assembly provides AC power to the AC electrodes and DC power to the DC electrodes. When the AC electrodes are energized, a first arc is generated. When the DC electrodes are energized, a second arc is generated. A third arc is generated between the AC and DC electrodes.

[0006] Based on the above technical solution, the first electric arc includes the electric arc between AC electrodes and between AC electrodes and the material; the second electric arc includes the electric arc between DC electrodes and the material; and the third electric arc includes the electric arc between DC electrodes through the material and AC electrodes.

[0007] Based on the above technical solution, the power supply component includes a transformer connected to the power grid, a short grid structure electrically connected to the AC electrode, and an automatic converter electrically connected to the DC electrode. The first ends of the short grid structure and the automatic converter are both connected to the transformer.

[0008] Based on the above technical solution, the current path between the AC electrode and the DC electrode is as follows:

[0009] The power supply component flows into the AC electrode through a transformer and a short-grid structure;

[0010] The power supply component consists of a transformer that passes through an automatic converter and an external busbar to the DC electrode, and then the furnace charge passes through the AC electrode to form a DC circuit.

[0011] Current flows from the anode of the DC electrode to the AC electrode, forming a main current path in the vertical direction.

[0012] Based on the above technical solution, the AC electrodes are provided in three and arranged in a triangular shape.

[0013] Based on the above technical solution, two DC electrodes are provided below each AC electrode, and the DC electrodes are provided with an angle at the end near the AC electrode.

[0014] Based on the above technical solution, the AC electrode serves as the cathode, the DC 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.

[0015] On the other hand, a smelting apparatus is also provided, including the above-mentioned AC / DC hybrid electric arc heating structure, characterized in that it further includes a furnace body, wherein the AC electrode is disposed at the top inside the furnace body and the DC electrode is disposed at the bottom inside the furnace body.

[0016] Based on the above technical solution, multiple DC electrodes are evenly arranged along the circumference of the furnace body.

[0017] The beneficial effects of the technical solution provided by this utility model are as follows:

[0018] This invention provides a hybrid AC / DC arc heating structure. By combining AC and DC electrodes, specifically through the electric fields generated between AC electrodes, the DC electrodes, and the arc generated between them, a more rational heat layer distribution is achieved during 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. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structural principle of this utility model;

[0020] Figure 2 This is a schematic diagram of the internal cross-sectional structure of the furnace body of this utility model;

[0021] Figure 3 This is a schematic diagram of the circuit control principle of this utility model;

[0022] Figure 4 This is a schematic diagram of the arc distribution of the AC electrode and the DC electrode in this utility model;

[0023] Figure 5 This is a potential distribution diagram between the AC and DC electrodes inside the furnace body in this utility model;

[0024] Figure 6 Figure 1 is a schematic diagram of the electric field intensity distribution inside the furnace body in this utility model; 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.

[0025] Figure 7 This is a top view of the DC electrode inside the furnace body in this utility model; Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0027] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," 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. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0028] In the description of this utility model, 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 utility model 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 utility model.

[0029] like Figures 1 to 7 As shown, an AC / DC hybrid arc heating structure includes an AC electrode 1, a DC electrode 2, and a power supply assembly. Multiple AC electrodes 1 are arranged in parallel, and the DC electrodes 2 are correspondingly arranged below the AC electrodes 1. The power supply assembly is electrically connected to both the AC electrodes 1 and the DC electrodes 2. The power supply assembly provides AC power to the AC electrodes 1 and DC power to the DC electrodes 2. When the AC electrodes 1 are energized, a first arc is generated. When the DC electrodes 2 are energized, a second arc is generated. A third arc is generated between the AC electrodes 1 and the DC electrodes 2.

[0030] This invention provides a hybrid AC / DC arc heating structure. By using AC electrode 1 and DC electrode 2 in combination, specifically, the electric fields generated between AC electrodes 1 and DC electrode 2, and the electric arc generated between AC electrodes 1 and DC electrodes 2, achieve a more rational heat layer distribution in smelting, effectively reducing power consumption by approximately 10%. It optimizes the current path, reduces branch current, effectively increases the current from the electrodes to the bottom of the smelting equipment, raises the furnace bottom temperature, avoids a cold furnace bottom, reduces large dead material zones, and achieves 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 material surface is reduced, and unit consumption is lowered; the molten pool widens, reducing dead material zones.

[0031] Based on the above technical solution, the first electric arc includes the electric arc between AC electrodes 1 and between AC electrodes 1 and the material; the second electric arc includes the electric arc between DC electrodes 2 and the material; and the third electric arc includes the electric arc between DC electrodes 2 and AC electrodes 1 through the material.

[0032] like Figure 4 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 power supply component includes a transformer 3 connected to the power grid, a short grid structure 4 electrically connected to the AC electrode 1, and an automatic converter 5 electrically connected to the DC electrode 2. The first ends of the short grid structure 4 and the automatic converter 5 are both connected to the transformer 3.

[0034] Based on the above technical solution, the current path between the AC electrode 1 and the DC electrode 2 is as follows:

[0035] The power supply component flows into the AC electrode 1 through the transformer 3 and the short network structure 4;

[0036] The power supply component consists of a transformer 3, an automatic converter 5, an external busbar 6, and a DC electrode 2, which then passes through the furnace charge and AC electrode to form a DC circuit.

[0037] Current flows from the anode of DC electrode 2 to AC electrode 1, forming a main current path in the vertical direction.

[0038] The alternating current path in this application is as follows: electricity from the power grid flows into AC electrode 1 through transformer 3 and short network structure 4; the direct current path is as follows: electricity from the power grid flows into DC electrode 2 through transformer 3, automatic converter 5, and external busbar 6, and then through furnace charge and AC electrode 1 to form a direct current circuit; the current circuit between DC electrode 2 and AC electrode 1 is as follows: current flows from the anode of DC electrode 2 to AC electrode 1, forming a main current path in the vertical direction.

[0039] This application utilizes the combined arrangement of AC electrode 2 and DC electrode 1 to effectively optimize the current path, reduce branch current, and increase the current from the electrode to the furnace bottom. Simultaneously, it forms 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. An automatic converter rectifies the AC power into DC power, and can also change the magnitude of the DC power. By applying external DC power to increase the furnace bottom current, the DC electric field at the furnace bottom is enhanced, expanding the bottom molten pool; this increases the furnace bottom temperature, avoids a cold furnace bottom, reduces large-area dead material zones, and achieves complete melting of the furnace charge. It should be noted that the aforementioned transformer, short-grid structure, and automatic converter can be obtained from existing technologies, and this application does not involve any improvement to their specific structures. 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.

[0040] Based on the above technical solution, the AC electrode 1 is provided in three parts arranged in a triangular shape.

[0041] On the vertically positioned AC electrode 1, the current density decreases and the electric field strength decreases both upwards and downwards. 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, and gradually decreases as one moves away 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.

[0042] The electric field distribution of the DC electrode 2 gradually decreases along the surface of the DC electrode towards the AC electrode, 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 a denser electric field line at the electrode edges and tips; the electric field gradually decreases in areas far 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 DC 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.

[0043] 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.

[0044] Based on the above technical solution, two DC electrodes 2 are provided below each AC electrode 1, and the DC electrode 2 is provided with an included angle at the end near the AC electrode 1.

[0045] This design has two advantages: firstly, it facilitates the distribution of the electric arc between the bottom and top electrodes, enabling effective heating of the bottom portion of the furnace; secondly, it effectively avoids the manufacturing of high-current bottom electrodes, resulting in higher safety for the bottom electrodes.

[0046] Based on the above technical solution, the AC electrode 1 serves as the cathode, the DC electrode 2 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.

[0047] like Figure 6 As shown in the figure, Figure a is the electric field intensity distribution inside the furnace without DC electrodes, and Figure b is the electric field intensity distribution inside the furnace after adding bottom DC 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 furnace bottom.

[0048] In a hybrid electric field, the electric field intensity distribution is influenced by both AC and DC electrodes. The field is weaker near the AC electrode due to the outward decay of the AC electric field, and stronger near the DC electrode due to the enhanced electric field at the boundary region of the DC electric field. The area between the two electrodes is a transition zone where the electric field intensity changes gradually and 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.

[0049] Specifically, based on the potential distribution, it can be divided into 3 regions, as follows: Figure 5 As 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.

[0050] A smelting apparatus includes the aforementioned AC / DC hybrid electric arc heating structure, and also includes a furnace body 7, wherein the AC electrode 1 is disposed at the top inside the furnace body 7, and the DC electrode 2 is disposed at the bottom inside the furnace body 7.

[0051] Based on the above technical solution, multiple DC electrodes 2 are evenly arranged along the circumference of the furnace body 7.

[0052] In a preferred embodiment, the smelting apparatus is configured as a submerged arc furnace. The AC electrodes 1 are arranged in parallel at the top of the furnace body 7, and the DC electrodes 2 are arranged at the bottom of the furnace body 7. This ensures that the heat layer distribution effectively reaches the furnace bottom, the high-temperature zone shifts downward, heat dissipation from the material 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 the branch current. By setting the DC electrodes at the bottom, the furnace bottom temperature is increased, the molten pool widens, and the dead material zone is reduced. More preferably, the distance from each AC electrode to the furnace bottom can be accurately determined by measuring the voltage of each AC electrode to the DC electrode at the furnace bottom, achieving more accurate furnace temperature control. This method is suitable for retrofitting old furnaces, without changing the original transformer, electrodes, and short grid structure, saving investment and exhibiting excellent practical performance.

[0053] The foregoing has shown and described the basic principles and main features of this utility model. It is obvious to those skilled in the art that this utility model is not limited to the details of the above exemplary embodiments. Therefore, the embodiments should be regarded as exemplary and non-limiting. The scope of this utility model is defined by the appended claims rather than the foregoing description. Therefore, it is intended to include all changes that fall within the meaning and scope of the equivalents of the claims within this utility model.

[0054] 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. An alternating current and direct current hybrid electric arc heating structure, characterized by, The application relates to an electrode assembly, which comprises alternating current electrodes, direct current electrodes and a power supply component, the alternating current electrodes are arranged in parallel, the direct current electrodes are arranged below the alternating current electrodes, the power supply component is electrically connected with the alternating current electrodes and the direct current electrodes, the power supply component provides alternating current for the alternating current electrodes and direct current for the direct current electrodes, the alternating current electrodes generate first electric arcs after being electrified, the direct current electrodes generate second electric arcs after being electrified, and third electric arcs are generated between the alternating current electrodes and the direct current electrodes.

2. The AC-DC hybrid arc heating structure according to claim 1, characterized in that, The first electric arcs include electric arcs between the alternating current electrodes and between the alternating current electrodes and materials; the second electric arcs include electric arcs between the direct current electrodes and the materials; and the third electric arcs include electric arcs between the direct current electrodes and the alternating current electrodes through the materials.

3. The AC-DC hybrid arc heating structure according to claim 1, wherein The power supply component comprises a transformer connected with a power grid, a short network structure electrically connected with the alternating current electrodes and an automatic current conversion device electrically connected with the direct current electrodes, and the short network structure and the automatic current conversion device are connected with the transformer.

4. The AC-DC hybrid arc heating structure according to claim 1, wherein The current path between the alternating current electrodes and the direct current electrodes is as follows: The power supply component flows into the alternating current electrodes through the short network structure via the transformer; The power supply component flows into the direct current electrodes through the automatic current conversion device via the transformer and the external bus, and then forms a direct current loop through the materials and the alternating current electrodes; The current flows from the anode of the direct current electrodes to the alternating current electrodes, forming a main current path in the vertical direction.

5. The AC-DC hybrid arc heating structure according to claim 1, wherein The alternating current electrodes are arranged in three and in a triangular shape.

6. The AC-DC hybrid arc heating structure according to claim 1, wherein Two direct current electrodes are arranged below each alternating current electrode, and the direct current electrodes are provided with an included angle at one end close to the alternating current electrodes.

7. The AC-DC hybrid arc heating structure according to claim 1, wherein The alternating current electrodes serve as cathodes, the direct current electrodes serve as anodes, and the electric field intensity distribution is as follows: in a central area, the electric field intensity is relatively constant; and in a boundary area, the electric field intensity increases from the central area to both ends of the electrodes.

8. A smelting apparatus comprising the hybrid AC-DC electric arc structure according to any one of claims 1 to 7, characterized in that, The application further relates to a furnace body, the alternating current electrodes are arranged at the top end of the furnace body, and the direct current electrodes are arranged at the bottom end of the furnace body.

9. A smelting apparatus as claimed in claim 8, wherein The direct current electrodes are evenly arranged in the circumferential direction of the furnace body.

Images