Method for prolonging service life of refractory material of water gap slag line by using pulsed electric field

Abstract

According to the method for prolonging the service life of the nozzle slag line refractory material through the pulsed electric field, the additional pulsed electric field is applied in the continuous casting process, the uniformity, the stability, the compactness and the adhesion of a casting powder film are improved, the newly-generated casting powder film is moderately extended towards the periphery of the casting powder film, scouring and permeating of casting powder to the slag line material are effectively resisted and inhibited, and the service life of the nozzle slag line refractory material is prolonged. The slag line erosion is inhibited, the Marangnei problem and the necking phenomenon are avoided, the single continuous casting time is greatly prolonged, and the continuous casting efficiency is greatly improved. And meanwhile, inclusions in the molten steel can be more uniform, and the quality of casting blanks is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of continuous casting, and in particular to a method for improving the service life of refractory materials at a nozzle slag line by utilizing a pulse electric field. Background Art

[0002] High-efficiency, low-cost clean steel production technology is a key development direction for my country's steel manufacturing industry. High-efficiency continuous casting has become the key to achieving a more efficient steel production process. With continuous progress and development in recent years, high-efficiency continuous casting production technology and equipment have achieved numerous breakthroughs and remarkable results, demonstrating higher casting speeds, better quality, and higher levels of control.

[0003] Unfortunately, the problem of severe erosion at the slag line of both long and submerged nozzles has not been effectively addressed. Severe erosion of the slag line not only significantly reduces the service life of the nozzle, but also introduces inclusions through the dissolution and flaking of the nozzle refractory, directly impacting steel quality. For example, the submerged nozzle, connecting the tundish and mold, is a crucial functional refractory material that comes into contact with the molten steel during continuous casting, playing a critical role in the quality of the final ingot and continuous casting efficiency. Severe erosion at the slag line of a submerged nozzle directly impacts casting efficiency and safety.

[0004] Chinese patent 202011454052.8 discloses a method for preventing decarburization and reaction behavior of rare earth steel nozzles by applying an interfacial electric field. The patent mentions a method of burying wires in the nozzle to apply an electric field. The buried wire part of the patent is Al2O3-C refractory material, and the electric field acts on the molten steel. However, the patent buries the wires to solve the problem of nozzle blockage, not to solve the problem of nozzle slag line erosion.

[0005] Currently, research on addressing slag line erosion has largely focused on improving nozzle refractory materials, adjusting nozzle structure, optimizing mold powder composition, and reducing liquid level fluctuations. While these approaches have achieved some success in field applications and have improved the slag line erosion rate, the problem of continuous mold powder erosion at the nozzle slag line remains unresolved. Furthermore, these technical approaches are relatively unsuitable for other steel grades and production platforms, resulting in significant limitations in their application.

[0006] Therefore, developing a technical method that has wide applicability and can effectively solve or inhibit nozzle slag line erosion has become the key to promoting and breaking through the bottleneck of existing continuous casting processes and improving the single continuous casting time and continuous casting production efficiency. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for increasing the service life of the refractory material of the nozzle slag line by using a pulsed electric field. This method can effectively protect the nozzle slag line, inhibit and reduce the erosion speed and erosion rate of the nozzle slag line by the protective slag; thereby effectively solving the technical problem of the excessively fast erosion rate of the slag line in the traditional continuous casting process, and improving the continuous pouring time and continuous casting efficiency of the molten steel. The erosion rate of the slag line in the continuous casting process is more than 65% lower than that of the traditional nozzle slag line without electric field treatment, and the single continuous casting time can be increased by more than 30%; and the distribution of inclusions in the steel will be more uniform, and the quality of the casting will be improved.

[0008] To achieve the above objectives, the technical solutions of the present invention are as follows:

[0009] A method for increasing the service life of slag line refractory materials using a pulsed electric field comprises the following steps:

[0010] 1) Nozzle embedding and pressing

[0011] During the nozzle manufacturing process, the wire is spirally wound inside the nozzle slag line and extended from the nozzle body, and then pressed into shape to obtain a formed nozzle;

[0012] 2) Graphite rod slotting, wire binding and fixing

[0013] The graphite rod is slotted and the wire is evenly wound inside the slot; the graphite rod is connected to a lifting device and placed above the crystallizer so that the insertion position and depth of the graphite rod can be replaced or adjusted in real time during the casting process;

[0014] 3) Anti-oxidation treatment of the thread embedding area

[0015] Use insulating high-temperature refractory mud to seal the wires extending from the nozzle body and the wires installed on the graphite rods;

[0016] 4) Nozzle placement and preheating

[0017] Place the treated nozzle and preheat it before normal casting;

[0018] 5) Constructing a pulsed electric field

[0019] The wire extending from the nozzle body is connected to the negative electrode of the pulse power supply by using an epitaxial wire, and the graphite rod is connected to the positive electrode of the pulse power supply to form a complete pulse electric field circuit. During the casting process, the graphite rod is stably inserted into the crystallizer to protect the molten slag layer, and then a stable pulse electric field is applied.

[0020] Preferably, the nozzle includes a long nozzle and an immersed nozzle, and the nozzle material is a carbon-containing material.

[0021] Preferably, in step 1), the wire is wound around the center of the nozzle slag line wall.

[0022] Preferably, in step 1), the spacing of the spiral winding of the wire is 2 to 3 cm.

[0023] Preferably, in step 1), the wire extends 30 to 40 cm above the slag line.

[0024] Preferably, the wire is made of metal iron, metal molybdenum, metal platinum or metal tungsten, and the diameter of the wire is 3 to 5 mm, preferably metal molybdenum, metal platinum and metal iron.

[0025] Preferably, in step 2), the graphite rod is a high-density graphite rod with a diameter of 4 to 8 cm and a length of 1 to 2 m. The slot position is 3 to 5 cm from the top of the graphite rod, the slot width is 1 to 4 cm, and the slot depth is 0.5 to 1.5 cm.

[0026] Preferably, in step 5), the epitaxial wire is made of metallic iron, metallic copper or metallic platinum, and the diameter of the epitaxial wire is 5 to 30 mm, preferably metallic copper.

[0027] Preferably, in step 5), the insertion position of the graphite rod needs to be adjusted accordingly according to the erosion and dissolution rate of the graphite rod, so that the bottom of the graphite rod can always remain inserted into the protective slag molten layer and does not contact the molten steel below the protective slag.

[0028] Preferably, in step 5), the pulse electric field output voltage is 3 to 30 V, the output current is 30 to 150 A, the pulse output frequency is 3000 Hz to 100,000 Hz, and the pulse output waveform is a rectangular wave or a sine wave.

[0029] During the continuous casting process, the molten mold slag acts as a high-temperature electrolyte, allowing the nozzle slag line, mold slag, and graphite rod to form a stable electrolytic cell under the action of an electric field. According to the electrochemical reaction mechanism, the graphite in the positive electrode mainly undergoes oxidation, accompanied by severe erosion and large-scale dissolution of the graphite. The nozzle slag line, on the other hand, mainly undergoes a reduction reaction, that is, some metal oxides in the mold slag are gradually reduced outside the slag line. Under the influence of an external electric field, a stable, high-viscosity mold slag film gradually forms on the outer wall of the negative electrode nozzle during the reduction process. The barrier effect of the mold slag film prevents direct contact between the slag line and the mold slag, thereby reducing and inhibiting the erosion rate of the slag line itself.

[0030] The present invention applies a pulsed electric field, and the pulsed electric field has a certain frequency, which can generate instantaneous high energy in the electrolytic cell. Under the action of the pulsed electric field, the new protective slag film formed by the slag line interface reaction will be more uniform, stable, dense and have higher adhesion, which can effectively resist and inhibit the scouring and penetration of the protective slag into the slag line material. In addition, affected by the oscillation effect and skin effect generated by the pulsed electric field, the protective slag film formed by in-situ reduction at the slag line will also extend moderately to its surroundings. This will not only form a protective slag film on the slag line surface that is in direct contact with the molten protective slag, but this protective slag film will also gradually extend to the surface of the nozzle material immersed in the molten steel liquid and the powder slag layer on the top that has not yet been completely melted. These new gain effects are conducive to solving the Marangoni problem caused by the fluctuation of the protective slag liquid level at the three-phase interface of the protective slag-molten steel-and the nozzle slag line, and avoiding the gradual decarburization of the nozzle material immersed in the molten steel, resulting in the exposure of the nozzle material's own refractory material to the molten steel and protective slag, etc., which causes the erosion rate near the nozzle slag line to accelerate and the "necking" phenomenon to occur. This will greatly improve the single continuous casting time and continuous casting efficiency while protecting the nozzle slag line refractory material from being eroded.

[0031] In addition, the technology shown in the present invention forms a stable pulsed electric field at the slag line of the nozzle. The free energy of the inclusions in the steel flowing through the slag line inside the nozzle will be affected to a certain extent by the pulsed electric field. As a result, the movement state of the inclusions inside the nozzle will also be affected to a certain extent, and the movement trajectory of the originally stable flowing inclusions will be slightly offset. Although this partial offset will not cause nodules to form in the nozzle, the inclusions in this moving state will be amplified when flowing out of the nozzle. This gain effect helps to make the distribution state of the inclusions in the steel more uniform, ultimately improving the quality of the molten steel and the quality of the casting.

[0032] During the nozzle manufacturing process of the present invention, the wire is directly buried in the nozzle slag line, which can avoid the damage to the original nozzle structure caused by the nozzle wire burying process in the existing technical solution. In the traditional transformation process, it will be affected by human operation and pose a threat to the nozzle and continuous casting production safety.

[0033] The wire embedding method adopts spiral embedding, followed by pressing and forming and sealing the wire part with high-temperature refractory clay, which can effectively ensure the effect of applying the electric field during the continuous casting process and prevent problems such as oxidation in the electric field circuit during high-temperature operation; and the spiral wire embedding method can also make the electric field distribution in the slag line more uniform, ensuring that the technical effects produced by the application of the above-mentioned pulse electric field can be effectively achieved; at the same time, under the premise of effectively improving the efficiency of electric field application, it can not only reduce the amount of electricity used in the process of applying the pulse electric field, but also help to ensure that the heat distribution of the slag line part of the nozzle after the pulse electric field is applied is uniform, and prevent the occurrence of problems such as poor thermal shock and nozzle fracture due to excessive temperature difference caused by local overheating.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention applies an external pulse electric field during the continuous casting process, so that the nozzle slag line, protective slag and graphite rod form a stable electrolytic cell under the action of the external pulse electric field. Instantaneous high energy is generated in the electrolytic cell, and a more uniform, stable, dense and highly adhesive protective slag film is formed on the outer wall of the nozzle, which effectively resists and inhibits the scouring and penetration of the protective slag on the slag line material. At the same time, the generated protective slag film will moderately extend to its surroundings, which is beneficial to solving the Marangoni problem caused by the fluctuation of the protective slag liquid level at the three-phase interface of the protective slag, molten steel and nozzle slag line, and avoiding the gradual decarburization of the nozzle material immersed in the molten steel, resulting in the accelerated erosion rate near the nozzle slag line and the generation of "necking" caused by factors such as the exposure of the nozzle material's own refractory material to the molten steel and the protective slag. This will greatly improve the single continuous casting time and continuous casting efficiency under the premise of protecting the nozzle slag line refractory material from being eroded. However, conventional power supply methods such as the use of DC electric fields cannot solve the Marangoni problem generated at the three-phase interface of the protective slag-molten steel-and the nozzle slag line, as well as the accelerated erosion rate and "necking" phenomenon near the nozzle slag line.

[0036] At the same time, the free energy of inclusions in the steel flowing through the slag line inside the nozzle will be affected to a certain extent by the stable pulse electric field, causing the inclusions to be amplified when flowing out of the nozzle, which is conducive to making the distribution of inclusions in the steel more uniform, thereby improving the quality of the molten steel and the quality of the ingot.

[0037] The present invention directly embeds the wire into the slag line part of the nozzle during the nozzle manufacturing process, and the wire embedding method adopts spiral embedding, which is subsequently pressed and formed and sealed with high-temperature refractory mud at the wire part. This can effectively ensure the effect of applying the electric field during the continuous casting process, and make the electric field distribution at the slag line part more uniform. On the premise of effectively improving the efficiency of electric field application, it can not only reduce the amount of electricity used in the process of applying the pulse electric field, but also help to ensure that the heat distribution of the slag line part of the nozzle after the pulse electric field is applied is uniform, and prevent the occurrence of problems such as thermal shock deterioration and nozzle breakage caused by excessive temperature difference due to local overheating.

[0038] The method of suppressing nozzle slag line erosion by a pulse electric field described in the present invention has a slag line erosion rate during continuous casting that is more than 65% lower than the erosion rate of the traditional nozzle slag line without electric field treatment. The single continuous casting time can be increased by more than 30%, and production efficiency is effectively improved and enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the position of the wire in the nozzle of the present invention.

[0040] Figure 2 This is a schematic diagram of the conductor at the nozzle slag line of the present invention.

[0041] Figure 3 This is a schematic diagram of the pulse electric field application method and corresponding equipment installation described in the present invention. DETAILED DESCRIPTION

[0042] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0043] See also Figures 1 to 3 The method of suppressing nozzle slag line erosion by using a pulse electric field according to the present invention comprises the following steps:

[0044] (1) Nozzle embedding and pressing:

[0045] During the nozzle manufacturing process, the conductor 1 is spirally wound inside the nozzle slag line and extended from the nozzle body, and then pressed into shape to obtain a shaped nozzle 2; the conductor at the nozzle slag line is located at the center of the slag line wall; the buried height of the conductor 1 is equal to the height of the slag line, the spiral winding spacing is 2 to 3 cm, and the conductor 1 extends 30 to 40 cm above the slag line;

[0046] (2) Graphite rod slotting, binding and placement:

[0047] The graphite rod 3 is slotted, and then the wire 1 is evenly wound inside the slot; the graphite rod 3 is connected to a lifting device 4, and the graphite rod 3 is placed above the crystallizer 5 so that the insertion position and depth of the graphite rod can be replaced or adjusted in real time during the casting process;

[0048] (3) Anti-oxidation treatment of buried wire parts: Use insulating high-temperature refractory mud to seal the external wires of the nozzle and the wire installation parts of the graphite rod to prevent the wires from oxidation;

[0049] (4) Nozzle placement and preheating: Place the treated nozzle and preheat it before normal casting;

[0050] (5) Constructing a pulsed electric field:

[0051] The wire extending from the main body of the nozzle 2 is connected to the negative pole of the pulse power supply 7 by using the extension wire 6, and the graphite rod 3 is connected to the positive pole of the pulse power supply 7, thereby forming a complete pulse electric field circuit. During the casting process, the graphite rod 3 is stably inserted into the protective slag molten layer in the crystallizer 5, and then a stable pulse electric field is applied.

[0052] Preferably, the wire 1 is made of metal iron, metal molybdenum, metal platinum or metal tungsten, and the diameter of the wire is 3 to 5 mm, preferably metal molybdenum, metal platinum and metal iron.

[0053] Preferably, in step 2), the graphite rod 3 is a high-density graphite rod with a diameter of 4 to 8 cm and a length of 1 to 2 m. The slot position is 3 to 5 cm from the top of the graphite rod, the slot width is 1 to 4 cm, and the slot depth is 0.5 to 1.5 cm.

[0054] Preferably, in step 5), the epitaxial wire 6 is made of metal iron, metal copper or metal platinum, and the diameter of the epitaxial wire is 5 to 30 mm, preferably metal copper.

[0055] Preferably, in step 5), the insertion position of the graphite rod 3 needs to be adjusted accordingly according to the erosion and dissolution rate of the graphite rod, so that the bottom of the graphite rod can always remain inserted into the protective slag molten layer and does not contact the molten steel below the protective slag.

[0056] Preferably, in step 5), the pulse electric field output voltage is 3 to 30 V, the output current is 30 to 150 A, the pulse output frequency is 3000 Hz to 100,000 Hz, and the pulse output waveform is a rectangular wave or a sine wave.

[0057] Example 1

[0058] This example uses a submerged nozzle for continuous casting of a double-stream low-carbon alloy steel slab as the experimental object. During the experiment, one nozzle was a normal casting nozzle without applying an electric field as control group 1, and the other nozzle was cast using the nozzle casting and electric field application method of the present invention as experimental group 1.

[0059] During the nozzle production process of the experimental group, the wire was spirally wrapped inside the nozzle slag line and extended from the nozzle body, and then pressed into shape to obtain a formed nozzle. The wire at the nozzle slag line was located at the center of the slag line wall; the nozzle material was aluminum carbon, and the slag line was zirconium carbon. The buried wire height was equal to the slag line height, the spiral winding spacing was 2 cm, and the wire extended 35 cm above the slag line. The wire was a high-temperature resistant metal wire made of molybdenum and had a wire diameter of 4 mm.

[0060] Before casting, the upper end of the graphite rod is slotted and wire-tied, and then the graphite rod is placed in an automatic lifting device, and then the lifting device is fixed above the crystallizer so that the insertion position and depth of the graphite rod can be adjusted in real time during the casting process; wherein, the wire is a high-temperature resistant metal wire metal iron with a wire diameter of 4mm, and the graphite rod is a high-density graphite rod with a diameter of 5cm and a length of 1.5m. The slot is located 5cm from the top of the graphite rod, the slot width is 2cm, and the slot depth is 0.5cm.

[0061] High-temperature refractory mud is used to seal the external wires of the test water outlet and the wire installation parts of the graphite rod to prevent the wires from oxidation.

[0062] The treated nozzle will be placed and preheated before normal casting.

[0063] At the beginning of continuous casting, the nozzle buried wire is connected to the negative electrode of the pulse power supply by using an epitaxial wire, and the graphite rod is connected to the positive electrode of the pulse power supply, thereby forming a complete pulse electric field circuit. During the casting process, the negative electrode graphite rod is stably inserted into the protective slag melting layer, and then a stable pulse electric field is applied to suppress the erosion of the slag line by the protective slag; wherein the epitaxial wire is a high-temperature resistant or high-melting-point metal wire metal copper, the wire diameter is 6mm, and the insertion position of the graphite rod needs to be adjusted accordingly according to the erosion and dissolution rate of the graphite rod, so that the bottom of the graphite rod can always be kept inserted into the protective slag melting layer; the output voltage of the pulse electric field is about 10V, the output current is about 50A, the pulse output frequency is generally 3000Hz, and the pulse type is a rectangular positive pulse.

[0064] During the casting process, compared with the nozzle of the control group 1 in normal casting, the liquid level near the nozzle of the experimental group remained stable without obvious fluctuations.

[0065] After 6 hours of continuous casting, the slag line of the nozzle of the control group 1, which was cast normally without applying an electric field, had formed serious necking and erosion, while the slag line of the nozzle of the experimental group 1 did not change significantly. After the nozzle was cut open, it was found that the inside of the nozzle slag line still maintained its original appearance, the overall erosion of the slag line was very small, and there was a uniform slag film on the outer wall of the nozzle.

[0066] Measurements showed that the slag line erosion depth at the nozzle in experimental group 1 was only 3.6 mm, 82.1% lower than that in control group 1. Sampling of the ingots cast under these two conditions after 1, 3, and 5 hours of casting revealed a more uniform distribution of inclusions within the ingots in the experimental group, with the overall number of inclusions being approximately 30% less than that in the experimental group.

[0067] Example 2

[0068] This embodiment still takes the submerged nozzle for continuous casting of a double-stream low-carbon alloy steel ingot described in Example 1 as the object. During the experiment, both nozzles adopt the nozzle casting and electric field application method described in the present invention as experimental groups 2 and 3. During the casting process, all operating processes remain unchanged, and only the original casting time is increased from 6 hours to 8 hours, and a comparative experiment is carried out with the control group comparison flow in Example 1.

[0069] During the casting process, compared with the control group's water outlet, the liquid level near the water outlet of experimental groups 2 and 3 remained stable without obvious fluctuations.

[0070] After 8 hours of continuous casting, the slag line at the nozzles of Experimental Groups 2 and 3 showed no significant changes. After sectioning, the interior of the nozzle slag line remained relatively intact, with minimal erosion overall and a uniform slag film on the outer wall. Measurements showed that, despite a 33.3% increase in continuous casting time compared to normal casting, the erosion depth of the nozzle slag line in Experimental Groups 2 and 3 was 6.8 mm, still 65.7% lower than normal casting.

[0071] Example 3

[0072] This embodiment takes the submerged nozzle of a double-stream ultra-low carbon automobile plate continuous casting as the object. During the experiment, one of the nozzles adopts a normal casting nozzle without applying an electric field as the control group 2, and the other nozzle adopts the nozzle casting and electric field application method described in the present invention as the experimental group 4.

[0073] During the nozzle production process of the experimental group, the wire was spirally wound inside the nozzle slag line and extended from the nozzle body, and then pressed into shape to obtain a formed nozzle. The wire at the nozzle slag line was located at the center of the slag line wall; the nozzle material was aluminum-carbon material, and the slag line was zirconium-carbon material; the wire embedding method was spiral embedding, the wire embedding height was equal to the slag line, the spiral winding spacing was 2 cm, the wire extension position was 35 cm above the slag line, the wire was a high-temperature resistant metal wire of molybdenum, and the wire diameter was 4 mm.

[0074] Before casting, the upper end of the graphite rod is slotted and wire-tied. The rod is then placed in an automatic lifting mechanism, which is then fixed above the mold to allow real-time adjustment of the rod's insertion position and depth during the casting process. The wire is made of high-temperature resistant iron and has a diameter of 4 mm. The graphite rod is a high-density 7 cm diameter, 1.5 m long, and slotted 5 cm from the rod's top. The slot is 2 cm wide and 1.2 cm deep.

[0075] Then, high-temperature refractory mud is used to seal the external wires of the test water outlet and the wire binding parts of the graphite rod to prevent the wires from oxidation.

[0076] The treated nozzle will be placed and preheated before normal casting.

[0077] At the beginning of continuous casting, the nozzle buried wire is connected to the negative electrode of the pulse power supply by using an epitaxial wire, and the graphite rod is connected to the positive electrode of the pulse power supply, thereby forming a complete pulse electric field circuit. During the casting process, the negative electrode graphite rod is stably inserted into the protective slag melting layer, and then a stable pulse electric field is applied to suppress the erosion of the protective slag on the slag line part; wherein the epitaxial wire is a high-temperature resistant or high-melting-point metal wire metal copper, the wire diameter is 20mm, and the insertion position of the graphite rod needs to be adjusted accordingly according to the erosion and dissolution rate of the graphite rod, so that the bottom of the graphite rod can always be kept inserted into the protective slag melting layer. The output voltage of the pulse electric field is about 25V, the output current is about 120A, the pulse output frequency is generally 40000Hz, and the pulse type is a rectangular positive pulse.

[0078] During the casting process, compared with the control group 2 nozzle, the liquid level near the nozzle of the experimental group 4 remained stable without obvious fluctuations.

[0079] After 6.5 hours of continuous casting, the slag line at the nozzle of control group 2 had already formed severe necking and erosion. However, the slag line of the nozzle of experimental group 4 did not change significantly. After cutting the nozzle, it was found that the interior of the nozzle slag line remained the same, with minimal overall erosion of the slag line and a uniform slag film on the outer wall of the nozzle. Measurements showed that the slag line erosion depth of the nozzle in experimental group 4 was 5.1 mm, 74.4% lower than that of control group 2. Sampling of the ingots under the two conditions was carried out at 1 hour, 3 hours, and 5 hours of casting. The results showed that the distribution of inclusions inside the ingots of the experimental group was more uniform, and the overall number of inclusions was about 25% less than that of the control group 2.

Claims

1. A method for increasing the service life of nozzle slag line refractory using a pulsed electric field, characterized in that: The steps include: 1) Nozzle embedding and pressing During the nozzle manufacturing process, the wire is spirally wound inside the nozzle slag line and extended from the nozzle body, and then pressed into shape to obtain a formed nozzle; 2) Graphite rod slotting, wire binding and fixing The graphite rod is slotted and the wire is evenly wound inside the slot; the graphite rod is connected to a lifting device and placed above the crystallizer so that the insertion position and depth of the graphite rod can be replaced or adjusted in real time during the casting process; 3) Anti-oxidation treatment of the thread embedding area Use insulating high-temperature refractory mud to seal the wires extending from the nozzle body and the wires installed on the graphite rods; 4) Nozzle placement and preheating Place the treated nozzle and preheat it before normal casting; 5) Constructing a pulsed electric field The wire extending from the nozzle body is connected to the negative pole of the pulse power supply by using an epitaxial wire, and the graphite rod is connected to the positive pole of the pulse power supply to form a complete pulse electric field circuit; during the casting process, the graphite rod is stably inserted into the protective slag molten layer in the crystallizer, and then a stable pulse electric field is applied.

2. The method for increasing the service life of nozzle slag line refractory using a pulsed electric field as claimed in claim 1, characterized in that: The nozzles include long nozzles and submerged nozzles, and the nozzle material is carbon-containing material.

3. The method for increasing the service life of nozzle slag line refractory using a pulsed electric field as claimed in claim 1, characterized in that: In step 1), the wire is wound around the center of the nozzle slag line wall.

4. The method for increasing the service life of nozzle slag line refractory using a pulsed electric field according to claim 1 or 3, characterized in that: In step 1), the spacing of the spiral winding of the wire is 2 to 3 cm.

5. The method for increasing the service life of nozzle slag line refractory by using a pulsed electric field as claimed in claim 1, 3 or 4, characterized in that: In step 1), the conductor extends 30 to 40 cm above the slag line.

6. The method for increasing the service life of nozzle slag line refractory using a pulsed electric field as claimed in claim 1, 3, 4 or 5, characterized in that: The wire is made of metal iron, metal molybdenum, metal platinum or metal tungsten, and has a diameter of 3 to 5 mm, preferably metal molybdenum, metal platinum and metal iron.

7. The method for increasing the service life of nozzle slag line refractory using a pulsed electric field as claimed in claim 1, characterized in that: In step 2), the diameter of the graphite rod is 4 to 8 cm, the length of the graphite rod is 1 to 2 m, the slot position is 3 to 5 cm from the top of the graphite rod, the slot width is 1 to 4 cm, and the slot depth is 0.5 to 1.5 cm.

8. The method for increasing the service life of nozzle slag line refractory using a pulsed electric field as claimed in claim 1, characterized in that: In step 5), the epitaxial wire is made of metal iron, metal copper or metal platinum, and the diameter of the epitaxial wire is 5 to 30 mm, preferably metal copper.

9. The method for increasing the service life of nozzle slag line refractory using a pulsed electric field according to claim 1 or 8, characterized in that: In step 5), the insertion position of the graphite rod needs to be adjusted accordingly according to the erosion and dissolution rate of the graphite rod, so that the bottom of the graphite rod can always be inserted into the mold slag molten layer and does not contact the molten steel below the mold slag.

10. The method for increasing the service life of nozzle slag line refractory using a pulsed electric field according to claim 1, 8 or 9, characterized in that: In step 5), the pulse electric field output voltage is 3 to 30 V, the output current is 30 to 150 A, the pulse output frequency is 3000 Hz to 100000 Hz, and the pulse output waveform is a rectangular wave or a sine wave.

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