Devices and methods for preventing nitrogen accumulation in molten steel during LF furnace refining process

Abstract

This invention discloses a device for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace. The device includes an LF furnace body, a furnace cover, an argon gas filling pipe, and an argon gas distribution mechanism for injecting argon gas from the filling pipe into multiple locations within the LF furnace body. A baffle is installed inside the furnace cover, and the argon gas distribution mechanism is located below the baffle. The argon gas filling pipe passes through the furnace cover and the baffle. This device prevents nitrogen accumulation in molten steel during the LF furnace refining process by installing the furnace cover at the upper end of the LF furnace body. During steel refining, argon gas is introduced into the filling pipe by connecting it to an argon gas pipeline. The argon gas is then transported from the filling pipe to a circular pipe via a connecting pipe. Finally, the argon gas is evenly injected into the LF furnace body through jet nozzles, forming an argon gas protective layer on the uppermost surface of the molten steel. This effectively isolates the molten steel from contact with nitrogen in the air, thus preventing nitrogen accumulation. This invention also discloses a method for preventing nitrogen accumulation in molten steel during the LF furnace refining process.

Description

Technical Field

[0001] This invention belongs to the technical field of steel metallurgical refining furnace equipment. Specifically, this invention relates to a device and method for preventing nitrogen accumulation in molten steel during the LF furnace refining process. Background Technology

[0002] Nitrogen is a harmful element in most steels, affecting their impact resistance and cold bending properties. With increasingly stringent material performance requirements, the demand for low-nitrogen steel (nitrogen content <50 ppm) is constantly rising. Nitrogen increase in molten steel has become a technical challenge in steelmaking control. One major factor contributing to nitrogen increase in molten steel is the exposure of the molten steel to air during the LF furnace refining process, as well as the ionization of air by the electric arc.

[0003] For example, patent document CN116445804A discloses a smelting method for 600MPa grade rebar to complete nitrogen alloying by gas nitrogen enrichment, including the following steps: (1) Converter smelting: ① Alloying is completed by using a nitrogen-free alloy, and the converter outlet [N] is (40-50)×10 -6 ② Control the molten iron [S] entering the converter to be ≤50×10 -6 Low-sulfur scrap steel [S] ≤ 200 × 10⁻⁶ is used in the converter. -6 Converter outlet [S] ≤ 130 × 10 -6 ③ Converter deoxidation reduces the oxygen activity of molten steel; [O] ≤ 60 × 10⁻⁶ at the converter exit. -6 (2) LF refining: ① LF deoxidation, reducing the [O] of the molten steel to ≤20×10 before adding nitrogen to the LF gas. -6 ② After the alloy element content of the molten steel is qualified, raise the temperature to 1570-1590℃ and stop the power supply. Switch the bottom blowing gas of the ladle from argon to nitrogen, and seal all openings / perforations of the ladle with nitrogen. ③ Use high arc voltage power supply and spray high-pressure nitrogen in the electrode impact area to complete the nitrogen enrichment of the molten steel gas (130-150)×10. -6 .

[0004] In the existing technology, the controlled nitrogen increase technology used in the LF furnace refining process is the foam slag submerged arc operation technology, but the nitrogen control effect of this technology is unstable. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides a device for preventing nitrogen accumulation in molten steel during the LF furnace refining process, with the purpose of improving nitrogen control.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a device for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace, comprising an LF furnace body, a furnace cover, an argon gas filling pipe, and an argon gas distribution mechanism for injecting argon gas from the argon gas filling pipe into multiple locations inside the LF furnace body. A partition is provided inside the furnace cover, the argon gas distribution mechanism is located below the partition, and the argon gas filling pipe passes through the furnace cover and the partition.

[0007] One end of the argon gas filling pipe extends to the outside of the furnace cover, and the argon gas distribution mechanism is connected to the other end of the argon gas filling pipe.

[0008] The argon gas distribution mechanism includes an argon gas distribution pipe and a connecting pipe connected to the argon gas distribution pipe and the argon gas filling pipe. The argon gas distribution pipe is provided with multiple air jet holes, and all air jet holes are evenly distributed along the circumference. Argon gas from the argon gas filling pipe enters the argon gas distribution pipe through the connecting pipe.

[0009] Multiple connecting pipes are provided.

[0010] The furnace cover is provided with an exhaust hole, and an exhaust chamber is formed between the partition and the furnace cover. The exhaust hole is connected to the exhaust chamber, and the exhaust chamber is located above the partition.

[0011] The partition plate is provided with a one-way exhaust port that communicates with the exhaust chamber. An air-blocking valve is provided in the one-way exhaust port, and the air-blocking valve controls the opening and closing of the one-way exhaust port.

[0012] The air-blocking valve is connected to the limiting rod, which is located below the one-way exhaust port.

[0013] The air-blocking valve is provided with a sealing surface for contacting the edge of the one-way exhaust port, and the sealing surface is a conical surface.

[0014] The furnace cover is connected to the LF furnace body via a snap-fit ​​structure. The snap-fit ​​structure includes an installation ring, a sealing ring, and an installation block disposed on the sealing ring and snap-fitted with the installation ring. The installation ring has a mating groove, which is adapted to the installation block.

[0015] The present invention also provides a method for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace. The method employs the aforementioned device for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace, and includes: during the refining of molten steel, argon gas is introduced into the interior of the argon gas filling pipe, and then the argon gas is sprayed out and introduced into multiple locations inside the LF furnace body through the argon gas distribution mechanism, forming an argon gas protective layer on the uppermost surface of the molten steel inside the LF furnace body, thereby isolating the molten steel from nitrogen in the air by the argon gas protective layer.

[0016] The device for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace of the present invention involves installing a furnace cover on the upper part of the LF furnace body. During the refining of molten steel, argon gas is introduced into the argon gas filling pipe by connecting the argon gas filling pipe to the argon gas pipeline. Then, the argon gas inside the argon gas filling pipe is transported to the inside of the circular pipe through a connecting pipe. Finally, the argon gas is evenly sprayed out through the jet hole and introduced into the inside of the LF furnace body, forming an argon gas protective layer on the uppermost surface of the molten steel. This effectively isolates the molten steel from contact with nitrogen in the air, thereby preventing nitrogen accumulation in the molten steel and achieving stable nitrogen control. Attached Figure Description

[0017] This manual includes the following figures, which illustrate the following:

[0018] Figure 1 This is a schematic diagram of the device for preventing nitrogen accumulation in molten steel during the LF furnace refining process according to the present invention.

[0019] Figure 2 This is a structural schematic diagram of the LF furnace body;

[0020] Figure 3 This is a schematic diagram of the furnace lid structure;

[0021] Figure 4 This is a cross-sectional view of the argon gas filling pipe structure;

[0022] The following are marked in the diagram: 1. LF furnace body; 11. Outer edge; 12. Mounting ring; 2. Furnace cover; 21. Exhaust port; 22. Argon gas filling pipe; 23. Argon gas distribution pipe; 24. Baffle plate; 25. One-way exhaust port; 26. Gas blocking valve; 27. Exhaust chamber; 28. Connecting pipe; 29. ​​Jet nozzle; 3. Sealing ring; 31. Mounting block; 32. Limiting rod. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and to facilitate its implementation.

[0024] like Figures 1 to 4 As shown, the present invention provides a device for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace, comprising an LF furnace body 1, a furnace cover 2, an argon gas filling pipe 22, and an argon gas distribution mechanism for injecting argon gas from the argon gas filling pipe 22 into multiple locations inside the LF furnace body 1. The furnace cover 2 is detachably installed on the upper end of the LF furnace body 1, and a partition 24 is provided inside the furnace cover 2. The argon gas distribution mechanism is located below the partition 24, and the argon gas filling pipe 22 passes through the furnace cover 2 and the partition 24.

[0025] Specifically, such as Figures 1 to 4As shown, one end of the argon gas filling pipe 22 extends to the outside of the furnace cover 2. This end of the argon gas filling pipe 22 is used to connect to a gas source. The argon gas distribution mechanism is fixedly connected to the other end of the argon gas filling pipe 22. By installing the furnace cover 2 on the upper part of the LF furnace body 1, during steel refining, argon gas is filled into the argon gas filling pipe 22. Then, the argon gas distribution mechanism sprays the argon gas into multiple locations inside the LF furnace body 1, forming an argon gas protective layer on the uppermost surface of the molten steel inside the LF furnace body 1. This argon gas protective layer isolates the molten steel from nitrogen in the air.

[0026] like Figure 3 and Figure 4 As shown, the argon gas distribution mechanism includes an argon gas distribution pipe 23 and connecting pipes 28 connected to the argon gas distribution pipe 23 and the argon gas filling pipe 22. The argon gas distribution pipe 23 is provided with jet holes 29, which penetrate the surface of the argon gas distribution pipe 23. Multiple jet holes 29 are provided, and all jet holes 29 are evenly distributed circumferentially with the axis of the argon gas distribution pipe 23 as the center line. Argon gas from the argon gas filling pipe 22 enters the argon gas distribution pipe 23 through the connecting pipes 28. The argon gas distribution pipe 23 has a hollow annular structure. Multiple connecting pipes 28 are provided, and all connecting pipes 28 are evenly distributed circumferentially with the axis of the argon gas distribution pipe 23 as the center line. One end of the connecting pipe 28 is fixedly connected to the argon gas filling pipe 22, and the other end of the connecting pipe 28 is fixedly connected to the argon gas distribution pipe 23. The argon gas distribution pipe 23 is coaxially arranged with the furnace cover 2 and the LF furnace body 1.

[0027] During steel refining, argon gas is introduced into the argon gas filling pipe 22 by connecting it to an external argon gas pipeline. Then, the argon gas inside the argon gas filling pipe 22 is transported to the argon gas distribution pipe 23 through the connecting pipe 28. Finally, the argon gas is evenly sprayed out through the jet hole 29 and introduced into the LF furnace body 1, forming an argon gas protective layer on the uppermost surface of the molten steel. This effectively isolates the molten steel from contact with nitrogen in the air, thereby preventing nitrogen accumulation in the molten steel.

[0028] Several jet holes 29 are evenly distributed at the lower end of the argon gas filling pipe 22; the even distribution of several jet holes 29 at the lower end of the argon gas filling pipe 22 enables the argon gas to be more evenly distributed on the surface of the molten steel when it enters the LF furnace body 1, thereby improving the argon gas isolation effect.

[0029] like Figures 1 to 4As shown, the furnace cover 2 is connected to the LF furnace body 1 via a snap-fit ​​structure. The snap-fit ​​structure includes an mounting ring 12, a sealing ring 3, and a mounting block 31 set on the sealing ring 3 and snap-fitted with the mounting ring 12. The mounting ring 12 has a mating groove, which is adapted to the mounting block 31. Both the mounting ring 12 and the mounting block 31 are L-shaped structures. An outer edge 11 is fixedly installed at the upper end of the LF furnace body 1, and the mounting ring 12 is fixedly installed at the upper end of the outer edge 11. A sealing ring 3 is fixedly installed at the bottom edge of the furnace cover 2. Multiple mounting blocks 31 are fixedly installed on the surface of the sealing ring 3. All mounting blocks 31 are evenly distributed circumferentially. The bottom of the sealing ring 3 is attached to the upper end of the outer edge 11. The mounting blocks 31 are movably snapped together with the mounting ring 12. The upper end of the mounting ring 12 has a mating groove, which is adapted to the mounting block 31.

[0030] By aligning the mounting block 31 with the mating groove of the mounting ring 12, and then placing the sealing ring 3 on the surface of the outer edge 11, the furnace cover 2 is rotated so that the horizontal end of the mounting block 31 slides into the lower end of the horizontal end of the mounting ring 12, thereby fixing the furnace cover 2 to the upper end of the LF furnace body 1. This allows the installation of the furnace cover 2 on the upper end of the LF furnace body 1 to be completed more quickly, and the furnace cover 2 can be quickly disassembled and assembled during operations such as adding materials to the LF furnace body 1, which can effectively improve processing efficiency.

[0031] like Figure 3 and Figure 4 As shown, an exhaust hole 21 is provided through the top of the furnace cover 2. An exhaust chamber 27 is formed between the partition plate 24 and the furnace cover 2. The exhaust hole 21 communicates with the exhaust chamber 27, which is located above the partition plate 24. The exhaust hole 21 allows the exhaust chamber 27 to communicate with the external environment. A one-way exhaust port 25 communicating with the exhaust chamber 27 is provided on the partition plate 24. The one-way exhaust port 25 is provided through the partition plate 24. A blocking valve 26 is provided in the one-way exhaust port 25, which controls the opening and closing of the one-way exhaust port 25. The blocking valve 26 has a T-shaped structure. Multiple one-way exhaust ports 25 are provided, and one blocking valve 26 is provided in each one-way exhaust port 25. The blocking valve 26 is provided with a sealing surface for contacting the edge of the one-way exhaust port 25. The sealing surface is a conical surface, and the one-way exhaust port 25 is a circular hole. The sealing surface and the one-way exhaust port 25 are coaxially arranged. After the sealing surface separates from the edge of the one-way exhaust port 25, the one-way exhaust port 25 opens, and the exhaust chamber 27 can communicate with the inner cavity of the LF furnace body 1. After the sealing surface contacts the edge of the one-way exhaust port 25, the one-way exhaust port 25 closes, and the exhaust chamber 27 cannot communicate with the inner cavity of the LF furnace body 1. This structure allows for timely and effective gas discharge, and the closure of the one-way exhaust port 25 improves the sealing performance.

[0032] like Figure 4As shown, the air-blocking valve 26 is connected to the limiting rod 32, which is located below the one-way exhaust port 25. The limiting rod 32 is used to limit the axial movement of the air-blocking valve 26. The size of the limiting rod 32 is larger than the diameter of the one-way exhaust port 25, and the limiting rod 32 has a cross-shaped structure. During the opening of the one-way exhaust port 25, after the limiting rod 32 contacts the upper partition 24, the air-blocking valve 26 moves into position, and the one-way exhaust port 25 is at its maximum opening. This structure can effectively reset the air-blocking valve 26, avoid over-opening, and improve operational reliability.

[0033] After argon gas is introduced into the LF furnace body 1 through the argon gas filling pipe 22, the original air inside the LF furnace body 1 is compressed upwards. The upward-moving air pushes the gas-blocking valve 26 upwards, thereby causing the sealing surface of the gas-blocking valve 26 to disengage from the one-way exhaust port 25. The limiting rod 32 prevents the gas-blocking valve 26 from being completely pushed out of the upper part of the one-way exhaust port 25 and thus unable to fall back down. This allows the interior of the LF furnace body 1 to connect with the exhaust chamber 27 through the one-way exhaust port 25, thereby allowing the upward-moving air to pass through... The gas is transferred through the one-way exhaust port 25 to the interior of the exhaust chamber 27 and discharged through the exhaust hole 21, thereby reducing the air content inside the LF furnace body 1 and making the argon content more sufficient. This further reduces the possibility of the molten steel mixing with air, improves the isolation effect of the argon protective layer on nitrogen, and after the argon filling pipe 22 stops filling with argon, the gas blocking valve 26 loses the gas thrust and falls freely under the influence of gravity, thereby re-closing the one-way exhaust port 25 and preventing external air from re-entering the interior of the LF furnace body 1 and causing nitrogen increase in the molten steel.

[0034] The present invention also provides a method for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace. The device for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace employs the above-described structure and includes: during the refining of molten steel, argon gas is introduced into the argon gas filling pipe 22, and then the argon gas is sprayed out and introduced into multiple locations inside the LF furnace body 1 through an argon gas distribution mechanism, forming an argon gas protective layer on the uppermost surface of the molten steel inside the LF furnace body 1, and isolating the molten steel from nitrogen in the air by the argon gas protective layer.

[0035] The above-mentioned device and method for preventing nitrogen accumulation in molten steel during the LF furnace refining process have the following advantages:

[0036] By installing the furnace cover 2 on the upper end of the LF furnace body 1, during the refining of molten steel, argon gas is introduced into the argon gas filling pipe 22 by connecting the argon gas filling pipe 22 to the argon gas distribution pipe 23 through the connecting pipe 28. Finally, argon gas is evenly sprayed out through the jet hole 29 and introduced into the LF furnace body 1, forming an argon gas protective layer on the uppermost surface of the molten steel, thereby effectively isolating the molten steel from contact with nitrogen in the air and preventing nitrogen accumulation in the molten steel.

[0037] Argon gas is introduced into the LF furnace body 1 through the argon gas filling pipe 22, thereby compressing the original air inside the LF furnace body 1 upwards. The upward-moving air pushes the gas-blocking valve 26 upwards, causing the inclined side end of the gas-blocking valve 26 to disengage from the one-way exhaust port 25. The limiting rod 32 prevents the gas-blocking valve 26 from being completely pushed out of the upper end of the one-way exhaust port 25 and unable to fall back down. This allows the interior of the LF furnace body 1 to connect with the exhaust chamber 27 through the one-way exhaust port 25, thereby enabling the upward-moving air to... The air is transferred to the interior of the exhaust chamber 27 through the one-way exhaust port 25 and discharged through the exhaust hole 21, thereby reducing the air content inside the LF furnace body 1 and making the argon content more sufficient. This further reduces the possibility of molten steel mixing with air, improves the isolation effect of the argon protective layer on nitrogen, and after the argon filling pipe 22 stops filling with argon, the gas blocking valve 26 loses the gas thrust and falls freely under the influence of gravity, thereby re-closing the one-way exhaust port 25 and preventing external air from re-entering the interior of the LF furnace body 1 and causing nitrogen increase in the molten steel.

[0038] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A device for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace, comprising an LF furnace body and a furnace cover, characterized in that, It also includes an argon gas filling pipe and an argon gas distribution mechanism for injecting argon gas from the argon gas filling pipe into multiple locations inside the LF furnace body. A partition is provided inside the furnace cover, and the argon gas distribution mechanism is located below the partition. The argon gas filling pipe passes through the furnace cover and the partition. An exhaust hole is provided through the top of the furnace cover. An exhaust chamber is formed between the partition and the furnace cover. The exhaust hole is connected to the exhaust chamber. The exhaust chamber is located above the partition and the exhaust hole allows the exhaust chamber to communicate with the external environment. A one-way exhaust port communicating with the exhaust chamber is provided on the partition. The one-way exhaust port is installed through the partition and a blocking valve is installed in the one-way exhaust port to control the opening and closing of the one-way exhaust port. The venting valve has a T-shaped structure with multiple one-way exhaust ports, each containing a venting valve. The venting valve has a sealing surface that contacts the edge of the one-way exhaust port. The sealing surface is conical, and the one-way exhaust port is a circular hole. The sealing surface and the one-way exhaust port are coaxial. When the sealing surface separates from the edge of the one-way exhaust port, the one-way exhaust port opens, allowing the exhaust chamber to communicate with the inner cavity of the LF furnace body. When the sealing surface contacts the edge of the one-way exhaust port, the one-way exhaust port closes, preventing communication between the exhaust chamber and the inner cavity of the LF furnace body. The air-blocking valve is connected to the limiting rod, which is located below the one-way exhaust port. The limiting rod is used to limit the axial movement of the air-blocking valve, and its size is larger than the diameter of the one-way exhaust port. During the opening of the one-way exhaust port, after the limit rod contacts the upper partition, the air-blocking valve moves into place, and the one-way exhaust port is at its maximum opening. After argon is introduced into the LF furnace body through the argon filling pipe, the air inside the LF furnace body is compressed upwards. The upward-moving air pushes the gas-blocking valve upwards, causing the sealing surface of the gas-blocking valve to disengage from the one-way exhaust port. The limiting rod prevents the gas-blocking valve from being completely pushed out of the upper end of the one-way exhaust port and unable to fall back down. This allows the inside of the LF furnace body to connect with the exhaust chamber through the one-way exhaust port, thereby allowing the upward-moving air to be transferred to the exhaust chamber through the one-way exhaust port and discharged through the exhaust hole, reducing the air content inside the LF furnace body. After the argon filling pipe stops introducing argon, the gas-blocking valve loses the gas thrust and falls freely under the influence of gravity, resealing the one-way exhaust port.

2. The device for preventing nitrogen accumulation in molten steel during the LF furnace refining process according to claim 1, characterized in that, One end of the argon gas filling pipe extends to the outside of the furnace cover, and the argon gas distribution mechanism is connected to the other end of the argon gas filling pipe.

3. The device for preventing nitrogen accumulation in molten steel during the LF furnace refining process according to claim 1, characterized in that, The argon gas distribution mechanism includes an argon gas distribution pipe and a connecting pipe connected to the argon gas distribution pipe and the argon gas filling pipe. The argon gas distribution pipe is provided with multiple air jet holes, and all air jet holes are evenly distributed along the circumference. Argon gas from the argon gas filling pipe enters the argon gas distribution pipe through the connecting pipe.

4. The device for preventing nitrogen accumulation in molten steel during the LF furnace refining process according to claim 3, characterized in that, Multiple connecting pipes are provided.

5. The device for preventing nitrogen accumulation in molten steel during the LF furnace refining process according to any one of claims 1 to 4, characterized in that, The limiting rod has a cross-shaped structure.

6. The device for preventing nitrogen accumulation in molten steel during the LF furnace refining process according to any one of claims 1 to 4, characterized in that, The furnace cover is connected to the LF furnace body via a snap-fit ​​structure. The snap-fit ​​structure includes an installation ring, a sealing ring, and an installation block disposed on the sealing ring and snap-fitted with the installation ring. The installation ring has a mating groove, which is adapted to the installation block.

7. A method for preventing nitrogen accumulation in molten steel during the LF furnace refining process, characterized in that, The device for preventing nitrogen accumulation in molten steel during the refining process of an LF furnace, as described in any one of claims 1 to 6, comprises: during the refining of molten steel, argon gas is introduced into the argon gas filling pipe, and then the argon gas is sprayed out through the argon gas distribution mechanism and introduced into multiple locations inside the LF furnace body, forming an argon gas protective layer on the uppermost surface of the molten steel inside the LF furnace body, thereby isolating the molten steel from nitrogen in the air by the argon gas protective layer.

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