Large-current low-internal-resistance submerged arc furnace short net
By filling light metal materials in the copper cavity of the mineral hot furnace short net to form a sealing structure, the problem of high electrical loss in the existing mineral hot furnace short net under low voltage smelting conditions is solved, and the effect of saving copper materials, reducing electrical loss and production costs is achieved.
Patent Information
- Application Number
- CN202510214238.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-26
- Publication Date
- 2025-06-03
AI Technical Summary
The existing mineral hot furnace short network has high electrical loss under low voltage smelting conditions, resulting in electricity consumption accounting for 10% to 25% of the total smelting electricity consumption, and the copper consumption is large, which increases manufacturing costs.
A cavity with copper as the matrix is used to fill light metal materials such as sodium, potassium or potassium-sodium alloys to form a sealing structure that isolates air contact, reduces resistance, and improves electrical conductivity.
It has achieved the goal of saving copper materials, reducing the weight and electricity loss of the short network, reducing production costs, reducing electricity losses, and achieving the goal of lightening the short network while meeting the current of short network use.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of submerged arc furnaces, and more specifically, to a short network of a submerged arc furnace with high current and low internal resistance. Background Art
[0002] In the steelmaking electric furnace and ferroalloy submerged arc furnace systems, the high-current short network is one of the core components of the equipment; to reduce the conductor power loss of the short network itself in the steelmaking current, the arc voltage can be increased. For example, an arc furnace transformer with a capacity of 12,500 kVA can provide a voltage of 300 V to 500 V to generate a strong arc to melt scrap steel. Generally, a short network current of 15,000 A to 25,000 A in the design can meet the use requirements; for the ferroalloy industry, for a submerged arc furnace with the same capacity of 12,500 kVA, the smelting voltage is relatively low, generally divided into multiple voltage levels, with the lowest smelting voltage of 75 - 95 V and the conventional smelting voltage of 120 - 200 V. During the initial stage of smelting, generally only the lowest voltage level can smoothly carry out submerged arc smelting. At this time, the load of the transformer, according to the design requirements, generally needs to reach 60% of the full load. Taking a 12,500 kVA submerged arc furnace as an example, when smelting at the lowest voltage, the short network current reaches 60,000 A; the power loss of the short network of the submerged arc furnace accounts for 10% - 25% of the total smelting power consumption, and the smaller the furnace type, the greater the power loss. Generally speaking, the lower the smelting voltage, the higher the power consumption of the short network of the submerged arc furnace. In fact, for a 12,500 kVA ferrosilicon furnace, during normal smelting operations, the operation time at the low voltage level generally accounts for more than 50% of the total smelting time. At this time, the actual load of the 12,500 kVA submerged arc furnace transformer is about 7,500 kVA, and the power consumption of the three short networks is more than 1,000 kVA, and these electric energies are lost in the form of heat.
[0003] The designed current density of the commonly used conductive materials for submerged arc furnaces is shown in Table 1; whether the short network of the submerged arc furnace is designed according to a current density of 3 A / mm 2 or 5 A / mm 2 The operating temperature needs to be lower than 70 °C. This is because the resistance of metal materials increases with the increase in temperature. Taking a 6-meter-long copper short network with a large current of 60,000 A as an example, at 30 °C, the loss of a single copper short network is about 90 kVA. When the temperature increases to 65 °C, due to the increase in resistance, the power loss on a single copper short network increases to more than 200 kVA; in addition, the copper short network is prone to oxidation and corrosion at relatively high temperatures above 60 °C, which will also cause an increase in the resistance of the copper short network. Especially after the end-face contact resistance increases, it is extremely likely to cause production failures.
[0004] Table 1 Designed current density of conductive materials for submerged arc furnaces
[0005]
[0006]
[0007] If a copper busbar is directly used, the maximum load of the copper busbar is only 1.5 A / mm 2 , and the material consumption is more than twice that of using a water-cooled short network. Taking a 60,000 A short network as an example, if it is a copper busbar short network, the required current-carrying cross-sectional area is more than 40,000 mm 2 above. Therefore, at present, most designs adopt a water-cooled short network, whose current-carrying cross-sectional area is only about 1 / 2 of that of the copper busbar, saving half of the copper. Taking a single 8-meter-long short network as an example, the weight of a single copper busbar is about 2.85 tons. When using a water-cooled short network, the copper consumption of a single water-cooled short network is about 1.5 tons. Therefore, using a water-cooled short network to adopt a high current density design can reduce the manufacturing cost, but the resistance of the short network itself increases, which will lead to an increase in the electrical loss of the short network. This is the direct reason why the electrical loss of the short network of a submerged arc furnace accounts for 10% - 25% of the entire smelting power consumption.
[0008] In view of the above situation, it is urgent to study a new short network for a submerged arc furnace, which can save copper materials, reduce the weight and electrical loss of the short network, and reduce costs while meeting the current of the short network. Summary of the Invention
[0009] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a short network for a submerged arc furnace with high current and low internal resistance, which can save copper materials, reduce the weight and electrical loss of the short network, reduce costs, and realize the lightweight of the short network while meeting the current of the short network.
[0010] To achieve the above purpose, the present invention adopts the following technical solutions:
[0011] The present invention provides a short network for a submerged arc furnace with high current and low internal resistance, including a short network body;
[0012] The short network body is composed of one or more cavity bodies based on copper materials;
[0013] The cavity body is filled with a light metal material;
[0014] The light metal material is selected from sodium or potassium or potassium-sodium alloy; the light metal material is filled into the cavity body after being heated into liquid metal.
[0015] Preferably, the cavity body is selected as a copper tube.
[0016] Preferably, the ratio of the cross-sectional area of the light metal material to the current-carrying cross-sectional area of the cavity body is not less than 4:1.
[0017] Preferably, when the light metal material is selected as potassium-sodium alloy, the recommended mass ratio of potassium to sodium is 3 - 5:1 - 2.
[0018] Preferably, the mass ratio of potassium to sodium is 3:1.
[0019] Preferably, the internal resistance of the short network of the submerged arc furnace is ≤5 mΩ.
[0020] The effects of the present invention are as follows:
[0021] 1. On the premise of meeting the current density, the present invention uses light metal materials with good conductivity, such as sodium, potassium, and potassium-sodium alloy, which are encapsulated in copper tubes or filled in copper short networks and sealed to isolate them from contact with air, so that the easily deteriorated active metals are isolated and play a good conductive role, thus achieving the goal of a light-type large-current short network, with low manufacturing cost, replacing copper with light metals in the field of large-current short networks, and saving social copper resources;
[0022] 2. The present invention is a cavity body with copper as the matrix, and a light metal material is encapsulated therein. The light metal material and the base material together have a good conductive effect, can save copper materials, reduce the weight of the short network, achieve the light weight of the short network, reduce the production cost, and reduce the electrical loss of the short network under the condition of meeting the current used by the short network. Specific embodiments
[0023] In order to better understand the above technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.
[0024] A large-current low-internal-resistance submerged arc furnace short network provided by the present invention includes a short network body; the short network body is composed of one or more cavity bodies with copper as the matrix; a light metal material is encapsulated in the cavity body; the light metal material is selected from sodium or potassium or potassium-sodium alloy; the light metal material is filled in the cavity body after being heated into liquid metal.
[0025] The cavity body can be selected as a copper tube; the ratio of the current-carrying cross-sectional area of the light metal material to the cavity body is not less than 4:1. Such a design can meet the current used by the short network and reduce the internal resistance. In the cavity body with copper as the matrix, liquid potassium or sodium or potassium-sodium alloy at a certain heating temperature is encapsulated to isolate air; after the cavity body is filled with the light metal material, it is used at 70 °C, and the safety is guaranteed. The light metal material and the base material together have a good conductive effect, can save copper materials, reduce the weight of the short network, and reduce the production cost under the condition of meeting the current used by the short network.
[0026] The above-mentioned cavity body mainly protects the liquid metal encapsulated therein and plays a role in supporting materials and external materials. The conductive function of the copper tube or copper cable inside the traditional short network is completed by liquid potassium-sodium alloy or metallic sodium. Taking the conductivity of sodium and copper as an example, compared with copper materials with the same area and the same length, the conductivity of sodium is 40-45% of that of copper materials; therefore, when transmitting the same current, if the cross-sectional area of the copper wire used for transmitting current is 1, the cross-sectional area of the metallic sodium used needs to be 2.5 times to meet the requirements; in addition, the density of copper is 8.92 g / cm 3, the density of metallic sodium is 0.92 g / cm 3 , thus, when using sodium as the conductive material, although the cross-sectional area increases by 2.5 times, even designed at 3.0 times, its weight is only 1 / 3 of that of copper material. In this way, the lightening of the short network can be achieved. At the same time, by using the cavity body based on copper material to isolate air, the conductivity of sodium or potassium or liquid potassium-sodium alloy can be ensured. Therefore, generally speaking, the ratio of the current-carrying cross-sectional area of the light metal material to the cavity body should not be lower than 4:1.
[0027] When the above-mentioned light metal material selects potassium-sodium alloy, the mass ratio of potassium to sodium is 3 - 5:1 - 2, preferably 3:1. The melting point of the liquid alloy under this ratio is lower than -10 °C, meeting most usage environments.
[0028] The above submerged arc furnace short network uses a composite material with low cost and large cross-section to obtain a short network with low resistance. The internal resistance of the submerged arc furnace short network of the present invention ≤ 5 mΩ.
[0029] The reason for selecting sodium or potassium or potassium-sodium alloy as the above-mentioned light metal material is as follows: Although the resistivity of these three metal materials is slightly higher than that of aluminum, their conductivity is good; in addition, the melting points of these three metal materials are relatively low, all lower than 97 °C, and they all have good thermal conductivity. The disadvantage is that they are easy to oxidize in the air; considering that the conductivity of these three metal materials all exceeds 30% of that of copper, and their densities are all small, less than 1 / 9 of that of copper; in addition, when these three metal materials change from solid state to liquid state, the volume change rate generally does not exceed 3%, and this performance is superior to that of aluminum. Although the conductivity of aluminum is close to that of copper, the chemical activity of aluminum is high, and it is extremely easy to undergo surface oxidation in the air, and the oxide layer is insulating and cannot be used in large-current short networks; if metal aluminum and metal copper are directly assembled and compounded, there will be a contact potential between the copper and aluminum interfaces, which will accelerate this oxidation. Therefore, sodium or potassium or potassium-sodium alloy is selected as the light metal material and filled in the cavity body based on copper material.
[0030] Taking an 8-meter short network designed for 60,000 A as an example, taking the current-carrying capacity as 4 A / mm 2 and the effective cross-sectional area is 15,000 mm 2 , the actual external dimension of the end face is generally a rectangle of 200 mm × 200 mm, and the actual single weight is at least 1.2 - 1.4 tons; if designed with copper bars, taking the current-carrying capacity as 1.5 A / mm 2 and the effective cross-sectional area is 40,000 mm 2, the actual external dimension of the end face is generally a rectangle of 2300mm×300mm, and the actual weight of a single root is about 3.4 tons. Since the short network of three-phase alternating current needs to consider the "skin" effect of current, it is mostly designed as a multi-tube parallel short network; when designing the short network of a submerged arc furnace with large current and low internal resistance of the present invention, taking the copper tube with a wall thickness of 2mm and an outer diameter of 50mm filled with metallic sodium or potassium-sodium alloy as an example, a copper tube matrix arranged in a 5*5 pattern is formed; the total copper consumption is 0.5 tons, and the current-carrying capacity of the copper material is calculated at 1.5A / mm 2 For the design, the current-carrying capacity of light metal materials is calculated at 0.8A / mm 2 For the design, the total current-carrying capacity of a single copper tube can reach 1700A. The theoretical resistance value of 25 parallel short networks is only 60% of that of copper material under the same conditions, and the total weight is only about 0.8 tons, which is only 25% of pure copper material, while the price is only 30% of pure copper material. The manufacturing cost is low, and the use effect is better than that of pure copper material with a pure nominal design. The short network power consumption is only 40% of that of copper material; and because it is a design with a small current density and a large contact area, air cooling can be adopted to ensure the safe operation of the short network below 70°C, without worrying about the safety problem of the short network of the submerged arc furnace after encapsulation; for the light metal encapsulated by copper material, whether it is solid sodium or liquid potassium-sodium alloy, it can be used safely.
[0031] Example
[0032] In a certain electroplating workshop, a 12V 6000A power supply is used, and the busbar is made of T2 purple copper. The specification is a busbar with 2 roots * 2 roots in parallel, with a specification of 120mm×8mm×15000mm. The designed current density value of the busbar is about 3A / mm 2 , and the weight is about 120 kg;
[0033] In this embodiment, a copper tube with an outer diameter of 40mm, a wall thickness of 2mm, and a length of 15100mm is used as the cavity body of the short network body, and the actual weight is 35kg; a copper valve is welded to each end of the copper tube. One end is an exhaust valve, which can discharge the gas or liquid light metal in the tube, and the other end is a filling valve, which is used to fill the liquid light metal material. The entire copper tube is bent into 12 circles and placed flat in a heat preservation box for preheating. The tube end corresponding to the filling valve is bent about 20 cm vertically at 90°C. After reaching 110°C, the air release valve at the other end is opened, and high-purity nitrogen is filled at the filling valve end to reduce the oxygen content in the tube until the gas in the tube is discharged. The gas at the air release valve end can suffocate the lighter flame (proving that the gas in the tube has been discharged and there is basically no residual oxygen), and keep the inflation for 3 minutes. Then, liquid sodium heated to 110-120°C is poured out at the filling valve end. When pouring, the exhaust valve slowly exhausts air, and nitrogen is used to drive away the air. After filling, the copper tube is slowly cooled at a rate of 1-2°C per minute (during which the liquid level in the tube drops and liquid sodium is filled in time). After the temperature drops to room temperature, the valves at both ends are tightened, and the outermost ends of the valves are brazed for complete sealing; about 15kg of metallic sodium is used in total, and the total installation is about 50kg.
[0034] Replace the cathode busbar in the busbar with the above-mentioned copper tube filled with sodium. After use, the measured voltage of the copper tube busbar decreased by 0.63V. After three months of on-site tracking, the use effect shows that it meets the use requirements. Under the same conditions, when the working current is 5000A, 20 degrees of electricity can be saved per shift. It is proved that the copper tube busbar has a lower resistance than the original flat copper busbar.
[0035] The total weight of the single composite copper tube busbar used in this embodiment is less than half of the original busbar. On the premise of meeting the use requirements, it can indeed reduce the consumption of copper materials and achieve the light weight of the short network. Thus, it can be seen that if the composite copper tube busbar is used on a large scale in the electrolysis industry, it can play the role of reducing the consumption of copper materials, reducing the cost of the busbar, reducing the resistance of the busbar, and reducing the electrical loss of the busbar.
[0036] Those of ordinary skill in the art in this technical field should recognize that the above embodiments are only used to illustrate the present invention and are not used to limit the present invention. As long as it is within the scope of the essential spirit of the present invention, the changes and modifications to the above embodiments will fall within the scope of the claims of the present invention.
Claims
1. A high current low internal resistance short circuit network for an electric arc furnace, characterized in that: Including short network body; The short net body is composed of one or more hollow bodies with copper material as the matrix; The cavity is filled with a light metal material; The light metal material is selected from sodium, potassium or potassium-sodium alloy; the light metal material is heated into liquid metal and then filled into the cavity.
2. The high current low internal resistance short circuit network for ore-fired furnace according to claim 1 is characterized in that: The cavity body is made of a copper tube.
3. The high current low internal resistance short circuit network for ore-fired furnace according to claim 1 is characterized in that: The current-carrying cross-sectional area ratio of the light metal material to the hollow cavity is not less than 4:
1.
4. The high current low internal resistance short circuit network for ore-fired furnace according to claim 1 is characterized in that: When the light metal material is a potassium-sodium alloy, the mass ratio of potassium to sodium is 3-5:1-2.
5. The high current low internal resistance short circuit network for ore-fired furnace according to claim 4 is characterized in that: The mass ratio of potassium to sodium is 3:
1.
6. The high current low internal resistance short circuit network for ore-fired furnace according to claim 1, characterized in that: The internal resistance of the short network of the submerged arc furnace is ≤5mΩ.