A leakage-proof furnace body structure of a DC arc furnace with bottom electrodes

Abstract

The present invention discloses a leakage-proof furnace structure for a DC arc furnace with bottom electrodes. Graphite electrodes are connected to the bottom electrodes above the slag limit of the molten pool within the furnace body to generate an arc to smelt the material within the furnace body. The bottom electrodes are connected and mounted on the furnace bottom outer shell. A conductive sheet is mounted on the upper end of the bottom electrodes, which is electrically conductive to the molten pool within the furnace body. The furnace body is constructed of refractory bricks and is also provided with an iron tapping port. Anode lead terminals are connected to the bottom electrodes via anode lead segments. A cooling circulation pipe segment is mounted at the bottom of the furnace body, embedded in an internal branch of the bottom electrodes and connected to the conductive sheet. The design of the present invention is targeted at the structural features of the DC arc furnace body, completely eliminating the harm of furnace bottom leakage and providing safety assurance for DC arc furnace production. The present invention has a reasonable structure, is resistant to electromagnetic shock, ensures a safe and leak-free furnace bottom, and can adapt to the smelting process requirements of complex materials, laying a solid foundation for the development of DC arc furnace smelting technology.

Description

Technical Field

[0001] The invention relates to the fields of nonferrous metallurgy and steelmaking, in particular to a leakage-proof furnace body structure of a DC electric arc furnace with bottom electrodes. Technical Background

[0002] A DC arc furnace is an electric arc furnace powered by direct current (DC). Similar to an AC arc furnace, it converts three-phase AC power into single-phase DC power, generating an arc between the metal charge at the bottom electrode (anode) and the graphite electrode (cathode) for smelting. The main differences between DC arc furnaces and AC arc furnaces include the addition of a rectifier, the reduction of three graphite electrodes at the top to a single cathode (cathode), and the addition of a bottom electrode (anode). The placement of the bottom electrode is the most significant feature of a DC arc furnace and a key to the success of DC smelting technology. While DC furnaces with bottom anodes are technologically advanced and feasible, they are susceptible to electromagnetic shock. Increased pressure at the bottom erodes the refractory insulation and causes cracks. The anode leads at the bottom electrode expand and contract due to the furnace temperature, causing molten metal to leak through the cracks and around the bottom electrode leads. This can significantly impact production and the DC smelting process, compromising normal operation and safety. Until now, when DC arc furnaces use a furnace structure with a bottom electrode, it has been difficult to solve the problem of leakage in the furnace bottom. Therefore, the key to adopting this technical solution is how to prevent the leakage problem of the furnace bottom.

[0003] Typically, the anode input terminal of the furnace bottom electrode is introduced through an opening outside the furnace shell. Due to the high furnace temperatures of 1800°C to 2000°C, the furnace bottom is bombarded by cathode electrons and subjected to electromagnetic stirring forces within the furnace. The impact and rising temperatures quickly cause the refractory insulation material at the bottom to begin to deteriorate, gradually forming cracks. The melted molten pool leaks through these cracks through the anode lead input terminal and out of the furnace shell. Severe leakage can damage or even pierce the entire furnace bottom. Therefore, in typical furnace structures with bottom electrodes, if the anode input terminal is not directly outside the furnace shell and effective leakage prevention and cooling measures are not implemented to mitigate the temperature rise within the furnace shell, it will be difficult to maintain the normal operation of DC smelting and achieve the desired process technology. DC furnaces with bottom electrodes without leakage prevention and cooling technology rely primarily on furnace repairs, often leading to production stoppages. The anode current is transmitted into the molten pool through the steel columns built into the refractory material at the bottom of the furnace. The tapping temperature of the iron in the furnace is 1600℃, and the tapping temperature of stainless steel is 1800℃. The temperature of the furnace bottom from the bottom to the slag limit is 250℃~500℃~1600℃~1800℃~2000℃ respectively.

[0004] How to design a leakage-proof furnace body structure for a DC arc furnace with bottom electrodes, which has the advantages of reasonable structure, strong pertinence, easy operation, simple maintenance, resistance to magnetic erosion, high temperature resistance, safety and no leakage, and long service life, is of great significance. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a leakage-proof furnace body structure of a DC arc furnace with a furnace bottom electrode, which solves the problem of furnace bottom electrode leakage, realizes the needs of the DC arc furnace smelting process technical characteristics, and achieves good economic benefits of DC arc furnace technology.

[0006] According to one aspect of the present invention, there is provided a leakage-proof furnace body structure of a DC arc furnace with a furnace bottom electrode, comprising a furnace body, a molten pool slag limit, a graphite electrode and a furnace bottom electrode, wherein the furnace bottom electrode constitutes an internal branch, and the graphite electrode is connected to the furnace bottom electrode above the molten pool slag limit in the furnace body to generate an arc to smelt the material in the furnace body. The furnace bottom shell is further provided, comprising a furnace bottom shell, refractory bricks, an iron outlet, an anode lead terminal, an anode lead segment, a conductive sheet, and a cooling circulation pipe segment. The furnace bottom shell is the bottom of the furnace body, and the furnace bottom electrode is connected and installed on the furnace bottom shell. A conductive sheet is installed on the upper end of the furnace bottom electrode, and the conductive sheet is connected to the molten pool in the furnace body; the furnace body is made of refractory bricks, and the furnace body is also provided with an iron outlet; the anode lead terminal is connected to the furnace bottom electrode through the anode lead segment; the cooling circulation pipe segment is installed at the bottom of the furnace body, and the cooling circulation pipe segment is embedded in the internal branch of the furnace bottom electrode, and the cooling circulation pipe segment is connected to the conductive sheet.

[0007] According to at least one embodiment of the present invention, the anode lead shield is further included. The anode lead shield is provided outside the anode lead segment, and the interior of the anode lead shield is filled with graphite refractory material.

[0008] According to at least one embodiment of the present invention, the contact portion between the anode lead shield and the furnace body is welded and sealed with a sealing steel plate.

[0009] According to at least one embodiment of the present invention, the height of the anode lead shield is higher than the slag limit of the molten pool in the furnace body.

[0010] The molten pool slag limit refers to the total height of the molten pool and slag in the furnace. During normal production, the total height of the molten pool slag limit in the furnace should not be higher than the height set by the anode lead segment shield.

[0011] According to at least one embodiment of the present invention, the cooling circulation pipeline section is provided with a cooling circulation pipeline inlet and a cooling circulation pipeline outlet, and the cooling circulation pipeline inlet and the cooling circulation pipeline outlet respectively pass through the furnace body and are provided on both sides of the furnace body.

[0012] According to at least one embodiment of the present invention, a cooling circulation pipe shield is provided outside the cooling circulation pipe section, and the interior of the cooling circulation pipe shield is filled with graphite refractory material.

[0013] According to at least one embodiment of the present invention, the fluid in the cooling cycle pipe section is water-cooled or air-cooled.

[0014] According to at least one embodiment of the present invention, the anode lead terminal and the furnace body form a "U"-shaped structure; the anode lead terminal and the furnace body form an "L"-shaped structure; the anode lead terminal and the furnace body form a "T"-shaped structure; the anode lead terminal and the furnace body form a "convex"-shaped structure.

[0015] All terminals, cooling circulation pipe section ports, and lead shields introduced from the bottom of the furnace shell will be firmly connected to the bottom shell of the furnace body.

[0016] The upper end of the conductive sheet forms a discharge zone with the molten pool, and the graphite electrode and the furnace bottom electrode are connected above the slag limit of the molten pool in the furnace body to generate an arc to smelt the material in the furnace body.

[0017] The essential features and advancements of the present invention are:

[0018] A DC arc furnace has a single negative electrode at the top of the furnace, and a positive electrode at the bottom. Unlike AC arc furnaces, its power supply system includes a rectifier and reactor, with contacts at the bottom of the furnace forming a current loop.

[0019] The leakage-proof furnace structure of the DC arc furnace with bottom electrodes of the present invention has a simple design, is easy to manufacture, and has low manufacturing cost. It can prevent leakage and provide safe production and operation for the DC arc furnace body. It has a reasonable structure, is resistant to electromagnetic shock, ensures the safety of the bottom electrodes without leakage, has strong adaptability to smelting materials, is resistant to high-temperature smelting, and extends the furnace life. The beneficial effects of the furnace structure of the present invention are:

[0020] (1) The arc is stable and concentrated, the molten pool is well stirred, the temperature distribution in the furnace is uniform, and the lining erosion is small;

[0021] (2) The current and voltage fluctuations are small, the impact on the power grid is reduced, and the cable life is extended;

[0022] (3) Less electrode loss, the electrode consumption per ton is more than 50% less than that of AC arc furnace;

[0023] (4) Ability to meet the technical characteristics of DC arc furnace smelting process.

[0024] According to calculations, the present invention achieves good economic benefits of DC arc furnace technology: 1. Graphite electrode consumption is reduced by more than 50%-60%; 2. Electric energy consumption is saved by 8%-15%; 3. Refractory materials are saved by 30%-35%; 4. Cable materials for short nets are saved; 5. The electrode leakage problem at the furnace bottom, which has not been solvable so far, is solved; 6. The molten pool melt is evenly stirred, which improves the power factor, reduces the voltage flicker rate, and reduces noise, with significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural diagram of an embodiment of the present invention.

[0026] Figure 2 It is a schematic diagram of a "U"-shaped structure of another embodiment of the present invention.

[0027] Figure 3 It is a schematic diagram of an "L"-shaped structure of another embodiment of the present invention.

[0028] Figure 4 It is a schematic diagram of a "T"-shaped structure of another embodiment of the present invention.

[0029] Figure 5 It is a schematic diagram of a "convex" structure of another embodiment of the present invention.

[0030] Parts numbers and names in the figure:

[0031] Graphite electrode 1, anode lead terminal 2, anode lead segment 3, anode lead shield 4, cooling circulation pipe inlet 5, sealing steel plate 6, furnace bottom electrode 7, conductive sheet 8, furnace bottom shell 9, cooling circulation pipe segment 10, cooling circulation pipe shield 11, cooling circulation pipe outlet 12, iron outlet 13, refractory bricks 14, molten pool slag limit 15. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It will be understood that the specific embodiments described herein are intended only to explain the relevant content and are not intended to limit the present invention. It should also be noted that, for ease of description, only portions relevant to the present invention are shown in the accompanying drawings.

[0033] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] In at least one embodiment of the present invention, Figure 1As shown, the present invention provides a leakage-proof furnace body structure of a DC electric arc furnace with a furnace bottom electrode 7, including a furnace body, a molten pool slag limit 15, a graphite electrode 1 and a furnace bottom electrode 7, the furnace bottom electrode 7 forming an internal branch, the graphite electrode 1 and the furnace bottom electrode 7 are connected above the molten pool slag limit 15 in the furnace body to generate an arc to smelt the material in the furnace body, and also includes a furnace bottom shell 9, refractory bricks 14, an iron outlet 13, an anode lead terminal 2, an anode lead segment 3, a conductive sheet 8, a cooling circulation pipeline segment 10, and a furnace bottom shell 9. The bottom of the furnace body is provided with a furnace bottom electrode 7 connected to and mounted on the furnace bottom outer shell 9. A conductive sheet 8 is mounted on the upper end of the furnace bottom electrode 7, and the conductive sheet 8 is in conduction with the molten pool in the furnace body. The furnace body is made of refractory bricks 14 and is also provided with an iron outlet 13. The anode lead terminal 2 is connected to the furnace bottom electrode 7 through the anode lead segment 3. The cooling circulation pipe segment 10 is installed at the bottom of the furnace body, embedded in the internal branch of the furnace bottom electrode 7, and connected to the conductive sheet 8.

[0035] The upper end of the conductive sheet 8 forms a discharge zone with the molten pool. The graphite electrode 1 is connected to the furnace bottom electrode 7 above the molten pool slag limit 15 within the furnace body, generating an arc to smelt the metal within the furnace body. The smelted metal flows out through the taphole 13. The furnace bottom electrode 7 is connected to the anode lead terminal 2 via the anode lead segment 3. The conductive sheet 8 controls the arrival of the furnace bottom electrode 7. The cooling circulation pipe segment 10 is in contact with the furnace bottom electrode 7 to cool it. Refractory bricks 14 provide thermal insulation for the furnace body.

[0036] According to another embodiment of the present invention, an anode lead shield 4 is further included. The anode lead shield 4 is provided outside the anode lead segment 3 , and the inside of the anode lead shield 4 is filled with graphite refractory material.

[0037] Anode lead shield 4 is installed outside anode lead segment 3. Graphite refractory material is filled inside shield 4 to provide thermal insulation and leak protection. If a small amount of molten metal in the furnace pool leaks out from around furnace bottom electrode 7, the pressure from shield 4 and the graphite refractory material prevent it from leaking out.

[0038] According to another embodiment of the present invention, the contact portion between the anode lead shield 4 and the furnace body is welded and sealed with a sealing steel plate 6 .

[0039] The contact point between the shield and the furnace body is sealed with a sealing steel plate 6 , so that even if the molten pool molten liquid leaks out from around the furnace bottom electrode 7 , it cannot leak out of the sealing steel plate 6 .

[0040] According to another embodiment of the present invention, the height of the anode lead shield 4 is higher than the slag limit 15 of the molten pool in the furnace body.

[0041] The molten pool slag limit 15 refers to the total height of the molten pool and slag in the furnace. During normal production, the total height of the molten pool slag limit 15 in the furnace should not be higher than the height of the anode lead segment 3 shield.

[0042] According to another embodiment of the present invention, the cooling circulation pipe section 10 is provided with a cooling circulation pipe inlet 5 and a cooling circulation pipe outlet 12, and the cooling circulation pipe inlet 5 and the cooling circulation pipe outlet 12 respectively pass through the furnace body and are provided on both sides of the furnace body.

[0043] According to another embodiment of the present invention, a cooling circulation pipe shield 11 is provided outside the cooling circulation pipe section 10 , and the interior of the cooling circulation pipe shield 11 is filled with graphite refractory material.

[0044] According to another embodiment of the present invention, the fluid in the cooling cycle pipe section 10 is water-cooled or air-cooled.

[0045] During operation, the furnace bottom electrode 7 generates a large amount of heat, which is cooled by the cooling circulation pipe. The cooling fluid, which can be water or air, enters through the cooling circulation pipe inlet 5 and exits through the cooling circulation pipe outlet 12. During this time, the fluid comes into contact with the furnace bottom electrode 7, cooling it.

[0046] A cooling pipe shield 11 is located outside the cooling pipe section 10. This shield is filled with graphite refractory material to provide thermal insulation and leak protection. If a small amount of molten metal in the furnace pool leaks out from around the bottom electrode 7, the pressure from the shield and the graphite refractory material prevent it from leaking out.

[0047] According to another embodiment of the present invention, the anode lead terminal 2 and the furnace body form a "U"-shaped structure, such as Figure 2 shown.

[0048] The anode lead terminal 2 and the furnace body form an "L"-shaped structure, such as Figure 3 shown.

[0049] The anode lead terminal 2 and the furnace body form a "T" structure, such as Figure 4 shown.

[0050] The anode lead terminal 2 and the furnace body form a "convex" structure, such as Figure 5 shown.

[0051] According to the conditions of different furnace bodies, appropriate structures can be adopted in a timely manner to achieve the purpose of leakage prevention.

[0052] The furnace bottom electrode 7 is cast from an alloy, and the anode lead terminal 2 is made of copper. The cooling circulation pipe section 10 is made from a high-temperature resistant alloy or copper. The cooling circulation pipe shield 11 is made from steel and graphite insulation.

[0053] The leakage-proof furnace body structure of a DC arc furnace with a bottom electrode of the present invention can prevent leakage from the bottom of the DC arc furnace with a bottom electrode and the lead segments of the bottom electrode 7, and can withstand electromagnetic impact smelting at higher smelting temperatures. Therefore, it is a permanent leakage-proof integral furnace structure for a DC arc furnace with a bottom electrode. In addition, the present invention has the characteristics of simple design, convenient manufacture, low manufacturing cost, and safe and reliable leakage-proof effect. During the smelting process, the operation is safe and stable, the bottom of the furnace body and the leads of the anode lead terminal 2 of the bottom electrode 7 are well sealed and leak-free, and the working state and cooling effect of the bottom electrode 7 meet the design requirements. It can fully meet the needs of DC arc furnaces with high smelting temperatures without leakage and can achieve the technical effects of DC arc furnace smelting.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that are not conceived through creative work should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined in the claims.

Claims

1. A leakage-proof furnace structure of a DC arc furnace with a furnace bottom electrode, comprising a furnace body, a molten pool slag limit (15), a graphite electrode (1) and a furnace bottom electrode (7), wherein the furnace bottom electrode (7) forms an internal branch circuit, and the graphite electrode (1) and the furnace bottom electrode (7) are connected above the molten pool slag limit (15) in the furnace body to generate an arc to smelt the material in the furnace body, characterized in that: It also includes a furnace bottom shell (9), refractory bricks (14), an iron outlet (13), an anode lead terminal (2), an anode lead segment (3), a conductive sheet (8), and a cooling circulation pipe segment (10). The furnace bottom shell (9) is the bottom of the furnace body. The furnace bottom electrode (7) is connected and installed on the furnace bottom shell (9). The upper end of the furnace bottom electrode (7) is installed with a conductive sheet (8), and the conductive sheet (8) is connected to the molten pool in the furnace body. The furnace body is made of refractory bricks (14), and the furnace body is also provided with an iron outlet (13). The anode lead terminal (2) is connected to the furnace bottom electrode (7) through the anode lead segment (3). The cooling circulation pipe segment (10) is installed at the bottom of the furnace body, the cooling circulation pipe segment (10) is embedded in the internal branch of the furnace bottom electrode (7), and the cooling circulation pipe segment (10) is connected to the conductive sheet (8). It also includes an anode lead shield (4), wherein the anode lead shield (4) is provided outside the anode lead segment (3), and the inside of the anode lead shield (4) is filled with graphite refractory material; The cooling circulation pipe section (10) is provided with a cooling circulation pipe inlet (5) and a cooling circulation pipe outlet (12), and the cooling circulation pipe inlet (5) and the cooling circulation pipe outlet (12) respectively pass through the furnace body and are provided on both sides of the furnace body.

2. The anti-leakage furnace structure of a DC arc furnace with bottom electrodes according to claim 1, characterized in that: The contact point between the anode lead shield (4) and the furnace body is welded and sealed with a sealing steel plate (6).

3. The anti-leakage furnace structure of a DC arc furnace with bottom electrodes according to claim 1, characterized in that: The height of the anode lead shield (4) is higher than the slag limit (15) of the molten pool in the furnace body.

4. The anti-leakage furnace structure of a DC arc furnace with bottom electrodes according to claim 1, characterized in that: A cooling circulation pipe shield (11) is provided outside the cooling circulation pipe section (10), and the interior of the cooling circulation pipe shield (11) is filled with graphite refractory material.

5. The anti-leakage furnace structure of a DC arc furnace with bottom electrodes according to claim 1, characterized in that: The fluid in the cooling circulation pipe section (10) is water-cooled or air-cooled.

6. The anti-leakage furnace structure of a DC arc furnace with bottom electrodes according to claim 1, characterized in that: The anode lead terminal (2) and the furnace body form a "U"-shaped structure; the anode lead terminal (2) and the furnace body form an "L"-shaped structure; the anode lead terminal (2) and the furnace body form a "T"-shaped structure; and the anode lead terminal (2) and the furnace body form a "convex"-shaped structure.

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