Electric system for smelting in a submerged arc furnace based on power taking from a burner

Abstract

The utility model relates to the field of ore -heating furnace energy -conserving technology, a kind of ore -heating furnace smelting electrical system based on the electricity of burning-through device, the system includes the high voltage power supply system, substation distribution system, ore -heating furnace primary power supply system, ore -heating furnace transformer, ore -heating furnace secondary short network, water-cooled cable and electrode connected in turn, and ore -heating furnace transformer is connected with electrode to form triangle.The outlet of each-phase transformer secondary circuit leads out a parallel loop to the furnace eye and directly powers, and the short network impedance voltage division characteristic is used to realize the grading control of burning-through voltage, without additional equipment, effectively reduce the problem of large amount of steel loss caused by high voltage, and when small furnace is upgraded to large furnace, the main structure of electric furnace or distribution system does not need to be transformed, and the transformation cost is significantly saved.

Description

Technical Field

[0001] This utility model relates to the field of energy-saving technology for electric arc furnaces, and in particular to an electrical system for electric arc furnace smelting based on power drawn from a burn-through device. Background Technology

[0002] The steel and ferroalloy industry is currently undergoing significant technological upgrades, with the development of larger and more powerful electric arc furnaces being a core trend. The power of electric arc furnaces in the industry has generally reached over 25,000 kW, leading to significant changes in smelting process parameters. In the process of furnace types shifting from 12,500 kW to 45,000 kW and even 63,000 kW and above, to meet the demands of high-power smelting, the secondary output voltage of the electric arc furnace transformer, i.e., the smelting voltage, has been significantly increased from the original 120V-160V range to the 220V-350V range.

[0003] During the tapping process of an electric arc furnace, a burn-through device (usually using a steel rod or rebar as consumables) is needed to burn open the furnace bore. In existing technology, the burn-through device is generally powered by direct parallel connection from the copper busbar at the secondary side outlet of the electric arc furnace transformer. The direct consequence of this power supply method is that the operating voltage of the burn-through device is positively correlated with the smelting voltage. As the smelting voltage increases sharply, the burn-through voltage also rises accordingly. Actual production measurement data shows that the burn-through voltage of a 45000KW electric arc furnace is approximately 150V, and that of a 63000KW electric arc furnace is as high as around 170V, far exceeding the 120V burn-through voltage of the 25000KW furnace model, which has been verified as reasonable in long-term production practice.

[0004] Excessively high burn-through voltage directly caused a series of serious technical problems:

[0005] 1. Material consumption increased dramatically: Due to the excessively high burn-through power, the consumption rate of steel bars used in the burn-through operation accelerated significantly. According to on-site statistics, previously one 3-meter-long steel bar could burn through two furnace holes, but under high-voltage conditions, two 3-meter-long steel bars were required to burn through one furnace hole, increasing steel bar consumption by nearly four times.

[0006] 2. Increased energy consumption: Excessive voltage causes the electric arc to diverge and become unstable, resulting in burn-through furnace boreholes that are too large and exceed process requirements. This not only makes subsequent borehole plugging operations extremely difficult but also causes unnecessary power consumption during smelting.

[0007] To address this issue, existing technologies have proposed several solutions. One solution is to add a dedicated single-phase step-down transformer at the furnace eye for each burn-through, reducing the voltage from, for example, 173V to 113V. However, this solution requires adding several transformers to each electric furnace, resulting in a high equipment investment cost of approximately 500,000 RMB per unit. Furthermore, the transformers themselves have a large footprint, generate significant heat, and produce additional iron losses, increasing energy consumption and safety risks in the working environment. Another solution is to connect a current-limiting reactor in series on the low-voltage side of the electric furnace, reducing the voltage from 156V to 70-90V. This solution also requires additional equipment, costing approximately 300,000 RMB per unit, and the reactor itself also introduces additional energy losses.

[0008] In summary, existing technological solutions all rely on adding extra, expensive, and energy-consuming equipment, increasing system complexity and maintenance costs. Therefore, the industry urgently needs an innovative technological solution that is simple in structure, low in cost, and does not introduce additional energy consumption to effectively reduce the burn-through voltage of high-power submerged arc furnaces. Utility Model Content

[0009] In order to solve the above-mentioned technical problems in the prior art, the present invention provides a burn-through device for power supply based on the electrical system of a submerged arc furnace smelting.

[0010] To achieve the above objectives, the technical solution of this utility model is as follows:

[0011] An electric arc furnace smelting system based on burn-through power supply is disclosed. The electric arc furnace smelting system includes an electric arc furnace transformer, an electric arc furnace secondary short network connected to the secondary side of the electric arc furnace transformer, and electrodes powered by the electric arc furnace secondary short network. The electric arc furnace secondary short network further includes a burn-through power supply branch, and the power extraction point of the burn-through power supply branch is fixedly connected to the electric arc furnace secondary short network through a power extraction conductor.

[0012] Furthermore, the power-taking conductor is a bus.

[0013] Furthermore, the power-collecting conductor is a copper busbar.

[0014] Furthermore, there are at least two power extraction points, and these at least two power extraction points are located at different positions along the current direction of the secondary short network of the electric arc furnace.

[0015] Furthermore, when two power extraction points are set, the two power extraction points include a first power extraction point and a second power extraction point:

[0016] The first power take-off point is located on the first-end busbar of the secondary short network of the electric arc furnace, near the transformer of the electric arc furnace.

[0017] The second power take-off point is located on the end busbar of the secondary short network of the electric arc furnace near the electrode side.

[0018] Furthermore, the second power take-off point is located downstream of the first power take-off point along the current direction from the transformer of the electric arc furnace to the electrode.

[0019] Furthermore, the electric arc furnace transformer consists of three single-phase transformers, whose secondary windings are connected in a delta configuration to the electrodes of the three single-phase transformers.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This utility model provides an electrical system for smelting in a submerged arc furnace based on burn-through transformer power supply. It improves the power supply method by taking power from the copper busbar at the transformer outlet of the submerged arc furnace, instead drawing power from either the first or last busbar of the secondary short network of the furnace. This improvement fully utilizes the impedance voltage division characteristics of the conductors in the secondary short network, achieving an effective voltage reduction. Taking actual operating data of a 45000KW submerged arc furnace as an example, the burn-through voltage dropped from 150V to 100V, a reduction of 33%. This significantly improves the problem of excessively rapid steel bar consumption under high voltage conditions, restoring the number of burn-through holes for a single steel bar to the normal level for small furnaces. Simultaneously, it eliminates the burn-through transformer commonly used in traditional designs, thus eliminating the iron and copper losses inherent in the burn-through transformer itself, reducing equipment maintenance costs, and minimizing additional losses in the power supply circuit. By setting up tiered power take-off points (125V at the beginning and 100V at the end) on the first or last busbar of the secondary short network of the submerged arc furnace, the operating voltage can be flexibly selected according to different mud ball resistance values ​​and specific process requirements, effectively solving the problem that a single voltage cannot adapt to dynamic operating conditions. In addition, the power take-off design at the top of the first busbar optimizes the current distribution, reduces the current imbalance loss of the secondary short network of the submerged arc furnace, and improves the three-phase power balance. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic diagram of power supply to the burn-through device.

[0024] Figure 2 This is a block diagram of the electrical system for smelting in an electric arc furnace.

[0025] Figure 3 This is a schematic diagram of the electrical connections of the electrical system for smelting in a submerged arc furnace.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1-Transformer for electric arc furnace; 11-A-phase transformer; 12-B-phase transformer; 13-C-phase transformer; 2-Secondary short network for electric arc furnace; 21-First-end busbar; 22-End busbar; 23-Water-cooled cable; 24-Copper busbar; 31-First electrode; 32-Second electrode; 33-Third electrode; 34-A-end; 35-B-end; 36-C-end; 37-X-end; 38-Y-end; 39-Z-end; 41-First power take-off point; 42-Second power take-off point. Detailed Implementation

[0028] The technical solution of this utility model will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of this utility model. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0029] It should be noted that, unless otherwise specifically stated, the relative arrangement and numerical expressions of the components and steps described in these embodiments should not be construed as limiting the scope of this utility model.

[0030] The following description of exemplary embodiments is merely illustrative and is not intended to limit the present invention or its application or use in any way. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail herein, but where applicable, such techniques, methods, and apparatus should be considered part of this specification.

[0031] This embodiment provides an electrical system for smelting in a submerged arc furnace based on power drawn from a burn-through device. The system comprises, in sequence: a high-voltage power supply system, a substation power distribution system, a primary power supply system for the submerged arc furnace, a submerged arc furnace transformer 1, a secondary short network 2 for the submerged arc furnace, water-cooled cables 23, and electrodes. The submerged arc furnace transformer 1 typically consists of three single-phase transformers or one three-phase transformer, such as... Figure 2 As shown, its function is to transmit 220KV power from the high-voltage power supply system of the electric arc furnace to the substation power distribution system, which then converts the 220KV power into 110KV power and transmits it to the primary power supply system of the electric arc furnace, and then to the transformer 1 of the electric arc furnace, which finally converts it into a low-voltage, high-current suitable for smelting.

[0032] The low-voltage, high-current section of an electric arc furnace, i.e., the secondary circuit, typically uses three-phase power supply. In this embodiment, as... Figure 3As shown, the electric arc furnace has a first electrode 31, a second electrode 32, and a third electrode 33. The electric arc furnace transformer 1 consists of three single-phase transformers: A-phase transformer 11, B-phase transformer 12, and C-phase transformer 13. Each single-phase transformer has two output terminals on its secondary winding: A-phase transformer 11 has terminal a 34 and terminal x 37; B-phase transformer 12 has terminal b 35 and terminal y 38; and C-phase transformer 13 has terminal c 36 and terminal z 39. The output terminals of the secondary windings of the three single-phase transformers (A-phase transformer 11, B-phase transformer 12, and C-phase transformer 13) are connected to the first electrode 31, the second electrode 32, and the third electrode 33 in a delta configuration. The specific connection relationships are as follows: the a terminal 34 of the secondary circuit of phase A transformer 11 is connected to the first electrode 31, and the x terminal 37 is connected to the second electrode 32; the b terminal 35 of the secondary circuit of phase B transformer 12 is connected to the second electrode 32, and the y terminal 38 is connected to the third electrode 33; the c terminal 36 of the secondary circuit of phase C transformer 13 is connected to the third electrode 33, and the z terminal 39 is connected to the first electrode 31.

[0033] like Figure 1 As shown, all high-current conductors from the secondary side outlet of the submerged arc furnace transformer 1 to the electrodes are collectively referred to as the submerged arc furnace secondary short network 2. The submerged arc furnace secondary short network 2 includes components such as copper busbars 24, a head busbar 21, a tail busbar 22, water-cooled cables 23, and copper busbars 24 connecting the electrodes. Its main function is to efficiently transmit the low voltage and high current output from the submerged arc furnace transformer 1 to the electrodes, thereby generating an electric arc in the furnace charge for melting.

[0034] The core innovation of this utility model lies in its power extraction method, such as... Figure 1 As shown, in this embodiment, the power extraction method involves setting at least two power extraction points on the conductor of the secondary short network 2 of the electric arc furnace to achieve graded control of the burn-through voltage. Specifically, copper busbars 24 are welded to two locations on the secondary short network 2 of the electric arc furnace to lead out independent power branches to supply the burn-through device. When two power extraction points are set, the two power extraction points include a first power extraction point 41 and a second power extraction point 42.

[0035] The first power take-off point 41 is set on the first busbar 21 of the secondary short network 2 of the electric arc furnace near the transformer 1 of the electric arc furnace. This position is at the front end of the current path, and the cumulative voltage drop is small.

[0036] The second power take-off point 42 is located on the end busbar 22 of the secondary short network 2 of the electric arc furnace near the electrode side. This position is at the rear end of the current path. The current has already flowed through the first end busbar 21 and the water-cooled cable 23 and other conductors. Their inherent impedance has resulted in a significant voltage drop.

[0037] Since the copper busbar 24 is located at varying distances from the electric arc furnace transformer 1 on the secondary short network 2 of the electric arc furnace, the voltage obtained at the point of power extraction farther from the transformer 1 is lower, thanks to the impedance voltage drop of the conductor itself. This method allows for graded control of the burn-through voltage.

[0038] Actual measurements, taking a 45000KW submerged arc furnace as an example, show that the burn-through voltage at the original power take-off point of the 45000KW submerged arc furnace without this method was 150V. After shorting the grid and reducing circuit losses, the voltage at the burn-through point connected using this method is approximately 100V, a reduction of about 40-50V compared to the original power take-off method before shorting the grid. Simultaneously, the burn-through voltage at the burn-through point of a 25000KW submerged arc furnace without this method was approximately 120V, and the burn-through voltage of this method is also lower than the 120V burn-through voltage of the 25000KW submerged arc furnace. This demonstrates that this solution can resolve the excessive material losses caused by high voltage, achieving energy saving and consumption reduction.

[0039] The above specific embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A smelting electric system based on a burner power supply for an electric arc furnace, comprising an electric arc furnace transformer, an electric arc furnace secondary short network connected to the secondary side of the electric arc furnace transformer, and electrodes powered by the electric arc furnace secondary short network, characterized in that: The secondary short network of the electric arc furnace also includes a burn-through power supply branch, and the power take-off point of the burn-through power supply branch is fixedly connected to the secondary short network of the electric arc furnace through a power take-off conductor.

2. The electric system for smelting of a submerged-arc furnace based on the power taking from the burner, according to claim 1, characterized in that: The power-taking conductor is a bus.

3. The electric system for smelting of ore smelting furnace based on the power taking from the burner according to claim 1, characterized in that: The power-collecting conductor is a copper busbar.

4. The electric system for smelting in a submerged-arc furnace based on the power taking from the burner, according to claim 2 or 3, characterized in that: There are at least two power take-off points, and the at least two power take-off points are set at different positions along the current direction of the secondary short network of the electric arc furnace.

5. The electric system for smelting in a submerged arc furnace based on the power taking from the burner, according to claim 4, characterized in that: When two power extraction points are set, the two power extraction points include a first power extraction point and a second power extraction point: The first power take-off point is set on the first-end busbar of the secondary short network of the electric arc furnace, near the transformer of the electric arc furnace; The second power take-off point is located on the end busbar of the secondary short network of the electric arc furnace near the electrode side.

6. The electric system for smelting in a submerged arc furnace based on the power taking from the burner, according to claim 5, characterized in that: The second power take-off point is located downstream of the first power take-off point along the current direction from the transformer of the electric arc furnace to the electrode.

7. The electric system for smelting in a submerged arc furnace based on the power taking from the burner, according to claim 1, characterized in that: The transformer for the electric arc furnace consists of three single-phase transformers, and the electrodes are three in number; The specific connection method between the secondary windings of the three single-phase transformers and the three electrodes is as follows: the two ends of the secondary side of the first single-phase transformer are respectively connected to the first electrode and the second electrode; the two ends of the secondary side of the second single-phase transformer are respectively connected to the second electrode and the third electrode; and the two ends of the secondary side of the third single-phase transformer are respectively connected to the third electrode and the first electrode.

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