Device for relieving negative pressure of submersed nozzle

Abstract

The utility model relates to a submerged nozzle negative pressure retarding device which comprises an electromagnetic induction assembly, a moving assembly and a computer, and the electromagnetic induction assembly is arranged on the outer side of a submerged nozzle in a sleeving mode. The moving assembly is installed on one side of the submersed nozzle, and the electromagnetic induction assembly is installed on the moving assembly. Alternating current is introduced into the electromagnetic induction assembly to generate a magnetic field, molten steel in the submersed nozzle is extruded by electromagnetic pinch force, the internal pressure of the submersed nozzle is increased, and the difference between the internal pressure and the external pressure of the submersed nozzle is reduced. Compared with the prior art, the electromagnetic induction assembly is arranged on the outer side of the submersed nozzle in a sleeving mode, an induced magnetic field is generated, molten steel flows in the magnetic field and is extruded by electromagnetic pinch force, the pressure intensity in the submersed nozzle is increased, the negative pressure phenomenon in the submersed nozzle is effectively relieved or eliminated, and the production quality of casting blanks is improved; and a magnetic field-flow field-temperature field coupling mathematical model in the submersed nozzle is established, so that the problem of negative pressure in the submersed nozzle under different working conditions can be solved.

Description

Technical Field

[0001] The utility model relates to a continuous casting production process, in particular to an immersion type nozzle negative pressure mitigation device. Background Art

[0002] The submerged nozzle is a transitional device connecting the tundish and the crystallizer, and is an indispensable part of the continuous casting production process. The molten steel in the tundish flows into the crystallizer through the submerged nozzle. Flow control devices such as stoppers and sliding nozzles control the flow rate to achieve pouring, preventing oxidation of the molten steel in the air. However, in actual pouring, the rapid flow of molten steel in the tundish through the gap between the stopper rods into the submerged nozzle will cause a pressure drop. This will cause the internal pressure of the submerged nozzle to be lower than the external pressure, resulting in a negative pressure phenomenon. This phenomenon will eventually cause a large amount of air to be sucked into the submerged nozzle during the pouring process, causing secondary oxidation. In addition, the negative pressure will also cause an air cavity to form inside the submerged nozzle, which flows with the molten steel. While chemical reactions occur, it is also very easy for nodules to be deposited on the inner wall of the nozzle, eventually leading to flow deviation and nozzle blockage, which greatly reduces the continuous casting productivity and affects the quality of the ingot.

[0003] To address the flow deviation and nozzle blockage caused by negative pressure, commonly used methods include blowing inert gas to compensate for negative pressure and electromagnetic flow control. Introducing inert gas through a stopper or bowl-shaped argon blowing method stirs the molten steel in the nozzle, making it difficult for inclusions in the molten steel to adhere to the nozzle inner wall. Introducing inert gas can also prevent the molten steel in the nozzle from inhaling air and causing secondary oxidation. However, an unreasonable argon blowing process can aggravate slag entrainment and easily break through the slag layer to form slag holes, causing secondary oxidation and reducing the quality of the ingot production.

[0004] After searching, Authorization Announcement No. CN206083849U discloses a ladle shroud for slightly positive pressure protection casting, which compensates for the pressure differential by blowing argon to prevent oxidation of the molten steel. However, the structure is relatively complex and the airtightness requirements in the argon blowing area are relatively strict. Application Publication No. CN105195726A discloses a device and method for mitigating negative pressure in the shroud and the impact force of molten steel. This device uses a traveling wave magnetic field to apply an electromagnetic force opposite to the direction of molten steel flow to mitigate the impact force and air absorption of the molten steel. However, the high-speed flow of molten steel requires a large electromagnetic force, which ultimately results in high power consumption.

[0005] In summary, how to design an immersion nozzle negative pressure reduction device that can improve the production quality of ingots, is easy to implement and consumes less energy is a technical problem that needs to be solved. Utility Model Content

[0006] The purpose of the present invention is to provide a device for alleviating negative pressure of an immersed nozzle in order to overcome the defects of the prior art.

[0007] The purpose of the utility model can be achieved through the following technical solutions:

[0008] According to one aspect of the utility model, a device for reducing the negative pressure of an immersion nozzle is provided, which is used for an immersion nozzle in a continuous casting process, wherein one end of the immersion nozzle is connected to a tundish and the other end is connected to a crystallizer, and the mitigation device includes an electromagnetic induction component, a moving component and a computer, wherein the electromagnetic induction component is a ring coil and is sleeved on the outside of the immersion nozzle; the moving component is installed on one side of the immersion nozzle, and the electromagnetic induction component is installed on the moving component and moves with the moving component; the electromagnetic induction component is electrically connected to the computer, and alternating current is passed through the electromagnetic induction component to generate a magnetic field. The molten steel inside the immersion nozzle flows in the magnetic field and is squeezed by the electromagnetic pinching force, so that the pressure inside the immersion nozzle increases and the pressure difference with the pressure outside the immersion nozzle decreases.

[0009] As a preferred technical solution, the electromagnetic induction component is concentric with the submerged nozzle.

[0010] As a preferred technical solution, the moving component includes a base, a longitudinal servo mechanism and a transverse servo mechanism; a track is set on the base, and the transverse servo mechanism cooperates with the track; the longitudinal servo mechanism is connected to the transverse servo mechanism; and the electromagnetic induction component is installed on the longitudinal servo component.

[0011] As a preferred technical solution, the lifting height of the longitudinal servo mechanism is 0 to 500 mm.

[0012] As a preferred technical solution, the AC current has a magnitude of 0 to 2000A, a frequency of 1 to 100 Hz, and an electromagnetic induction power of 0 to 3000 kW.

[0013] As a preferred technical solution, the interior of the electromagnetic induction component is cooled by water, wind or mist.

[0014] As a preferred technical solution, the electromagnetic induction component is sleeved on the middle part of the outer side of the immersion water inlet or close to one end of the crystallizer.

[0015] As a preferred technical solution, the electromagnetic induction component is an open or closed ring.

[0016] As a preferred technical solution, the submerged nozzle type is single-hole, double-hole or four-hole.

[0017] As a preferred technical solution, the mitigation device further includes a flow control component, which is installed at the end of the tundish that is not connected to the submerged water inlet.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) The electromagnetic induction component of the utility model is sleeved on the outside of the submerged nozzle, and an alternating current is passed inside to generate an induced magnetic field. The molten steel flowing in the magnetic field is squeezed by the electromagnetic pinching force, and the internal pressure of the submerged nozzle is increased, which can effectively alleviate or eliminate the negative pressure phenomenon inside the submerged nozzle, which is beneficial to improving the production quality of the casting blank. The electromagnetic pinching effect is utilized, which has the advantages of being contactless and pollution-free. At the same time, the direction of the electromagnetic pinching force is independent of the flow direction of the molten steel, which saves more electricity.

[0020] 2) The electromagnetic induction component of the utility model is electrically connected to the computer, and the computer flexibly adjusts the electromagnetic field strength to solve the problem of negative pressure inside the submerged nozzle under different billet drawing speeds, submerged nozzle areas and shapes of the casting end face. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a front view of a device for alleviating negative pressure of an immersed nozzle according to the utility model;

[0022] Figure 2 This is a top view of a device for alleviating negative pressure of an immersed nozzle according to the present invention;

[0023] Figure 3 This is the electromagnetic force vector distribution diagram of the utility model;

[0024] Figure 4 This is a schematic diagram of the negative pressure formation principle in the conventional continuous casting process;

[0025] Figure 5 This is a schematic diagram of the principle of using electromagnetic pinch effect to alleviate the negative pressure of the submerged nozzle in the utility model;

[0026] The numbers in the figure show:

[0027] 1. Immersed nozzle, 2. Tundish, 21. Tundish upper nozzle, 3. Crystallizer, 4. Electromagnetic induction component, 5. Moving component, 51. Base, 52. Longitudinal servo mechanism, 53. Horizontal servo mechanism, 6. Computer, 7. Stopper rod, 8. Crystallizer protective slag. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0029] The purpose of this utility model is to provide a device for mitigating negative pressure in an immersion nozzle. The device uses an electromagnetic pinch effect to apply an electromagnetic pinch force to the molten steel inside the immersion nozzle 1. The molten steel in the middle of the immersion nozzle 1 is subjected to a larger pinch force, which reduces the cross-sectional area of ​​the molten steel flow. The molten steel above is subjected to a smaller pinch force, and the pressure of the molten steel below causes the molten steel to fill the upper part of the immersion nozzle 1. Ultimately, the stabilization pressure of the molten steel inside the immersion nozzle 1 is equal to or greater than the ambient atmospheric pressure. This prevents air from being inhaled due to negative pressure, reduces the risk of secondary oxidation, nodules, and even blockages, and improves the quality and efficiency of billet production.

[0030] like Figure 1 and Figure 2 As shown, the utility model provides an immersion nozzle negative pressure mitigation device for a continuous casting process, comprising an electromagnetic induction component 4, a moving component 5 and a computer 6.

[0031] The continuous casting equipment includes a tundish 2, a submerged nozzle 1, mold powder 8, and a mold 3. The tundish 2 is provided with a tundish upper nozzle 21. The submerged nozzle 1 is a hollow cylinder, connected to the tundish 2 from above via the tundish upper nozzle 21. From below, the mold powder 8 passes through the surface of the mold 3 and into the mold 3. A stopper rod 7 is provided within the tundish 2 and inserted into the tundish upper nozzle 21. The amount of molten steel discharged is controlled by adjusting the gap between the stopper rod 7 and the tundish upper nozzle 21.

[0032] The electromagnetic induction component 4 is an open or closed annular coil mounted on the mobile component 5 and sleeved on the middle or slightly lower portion of the outer side of the immersion nozzle 1. The plane in which it is located is perpendicular to the axis of the immersion nozzle 1. Alternating current flows through the coil, generating an alternating magnetic field. The molten steel flowing in the immersion nozzle 1 cuts the magnetic flux lines, generating an induced current. Under the action of the alternating magnetic field, the molten steel is squeezed by the radial electromagnetic pinch force, changing the actual cross-sectional area of ​​the molten steel flow, thereby increasing the pressure inside the immersion nozzle 1 and reducing the pressure difference between the inside and outside of the immersion nozzle 1. The excitation current of the electromagnetic induction component 4 is 0 to 2000A, the frequency is 1 to 100Hz, the number of turns is 1 to 200, and the electromagnetic induction power is 0 to 3000kW. The coil cooling can be one of internal water cooling, air cooling, or mist cooling.

[0033] The moving assembly 5 includes a base 51, a longitudinal servo mechanism 52, and a transverse servo mechanism 53. It is mounted on one side of the submerged nozzle 1. A track is provided on the base 51, and the transverse servo mechanism 53 cooperates with the track. The longitudinal servo mechanism 52 is connected to the transverse servo mechanism 53. The electromagnetic induction assembly 4 is mounted on the longitudinal servo assembly, and the moving assembly 5 can drive the electromagnetic induction assembly 4 to move. The longitudinal servo mechanism 52 can be raised and lowered to a height of 0 to 500 mm.

[0034] The submerged nozzle 1 can be of single-hole, double-hole or four-hole type, and the electromagnetic induction component 4 can act on square billets, round billets and slabs.

[0035] The working process of this utility model is as follows:

[0036] Step 1: Based on the on-site billet casting speed, the size of the submerged nozzle 1 and the shape of the casting section, a coupled mathematical model of the magnetic field, flow field and temperature field in the submerged nozzle 1 is established to calculate the molten steel flow velocity v and the internal pressure P2 of the nozzle under different electromagnetic field intensities;

[0037] Step 2: Determine the internal pressure P2 of the submerged nozzle 1. If P2 is greater than 0, output the corresponding electromagnetic induction power P and use it as the objective function.

[0038] Step 3: According to the on-site billet casting speed, the size of the submerged nozzle 1 and the shape of the casting section, the flow control component is turned on to allow the molten steel in the tundish 2 to enter the crystallizer 3 through the submerged nozzle 1. After the flow field stabilizes, the electromagnetic induction component 4 is moved to a specified height near the submerged nozzle 1 by adjusting the moving component 5;

[0039] The flow control component can be one of the stopper rod 7 and the sliding gate;

[0040] Step 4: The electromagnetic induction component 4 is turned on by the computer 6, and its electromagnetic pinching force is distributed in the molten steel inside the submerged nozzle 1 as follows: Figure 3 As shown, it can be seen that the radial position of the molten steel generates an electromagnetic pinching force to squeeze the molten steel; the computer 6 adjusts the magnetic induction intensity B to a specified value. According to the principle of electromagnetic induction, the molten steel in the submerged nozzle 1 will generate a radial electromagnetic force, which reduces the actual cross-sectional area of ​​the molten steel flow in the submerged nozzle 1 and increases the internal pressure of the submerged nozzle 1, thereby prompting the connection between the upper nozzle 21 of the tundish and the submerged nozzle 1 to be filled with molten steel, reducing or avoiding the air inhalation at the connection between the upper nozzle 21 of the tundish and the submerged nozzle 1, and achieving the purpose of increasing the internal pressure of the submerged nozzle 1.

[0041] For the above working process, the specific parameters that can be used are as follows:

[0042] The continuous casting site working conditions are as follows: the billet casting speed is 1.2 m / min, the inner diameter of the submerged nozzle 1 is 80 mm, and the cross-sectional size of the slab is 1650×230 mm; after the electromagnetic induction component 4 is turned on, the computer 6 adjusts the magnetic induction intensity to 0.5 T.

[0043] During the continuous casting production process, a comparative experiment was conducted between the conventional process and the utility model.

[0044] The principle of negative pressure formation of submerged nozzle 1 negative pressure method in conventional continuous casting is as follows Figure 4 As shown, the electromagnetic pinch effect is used to slow down the submerged nozzle 1 to reduce the negative pressure principle. Figure 5 As shown, it can be seen that when the electromagnetic pinch device is not used to reduce the negative pressure of the submerged nozzle 1, when the high-speed molten steel flows from the tundish 2 through the submerged nozzle 1 into the crystallizer 3, the pressure P2 formed by the high-speed molten steel in the submerged nozzle 1 is less than the external atmospheric pressure. This internal and external pressure difference will cause air to be sucked into the connection between the tundish upper nozzle 21 and the submerged nozzle 1. In severe cases, it may cause the internal molten steel of the submerged nozzle 1 to be cut off. At the same time, it will also cause problems such as secondary oxidation that affect product quality. When the electromagnetic pinch effect is used to reduce the negative pressure of the submerged nozzle 1, the radial electromagnetic pinch force will squeeze the molten steel, thereby affecting the actual flow cross-sectional area of ​​the molten steel inside the submerged nozzle 1. In essence, the electromagnetic induction component 4 generates an electromagnetic pinch pressure P E At the connection between the tundish upper nozzle 21 and the submerged nozzle 1, P E The sum of the hydraulic pressure P2 inside the submerged nozzle 1 is approximately equal to or greater than the external pressure, thereby preventing the intake of air and ultimately improving product quality.

[0045] This utility model utilizes the electromagnetic pinching effect to alleviate negative pressure problems, offering advantages such as being contactless and pollution-free. The direction of the pinching force is independent of the direction of molten steel flow, further conserving electricity. This utility model ensures that the molten steel is fully filled by changing the cross-sectional area of ​​the molten steel flow, alleviating negative pressure problems. This ensures that the molten steel is fully filled within the submerged nozzle 1, suppressing secondary oxidation and the occurrence of skew flow. This utility model ensures that the molten steel is fully filled within the submerged nozzle 1, minimizing fluctuations in the amount of steel flowing through and facilitating continuous pouring.

[0046] 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 person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A device for alleviating negative pressure of an immersion nozzle, used for an immersion nozzle (1) in a continuous casting process, wherein one end of the immersion nozzle (1) is connected to a tundish (2) and the other end is connected to a crystallizer (3), characterized in that: The mitigation device comprises an electromagnetic induction component (4), a moving component (5) and a computer (6), wherein the electromagnetic induction component (4) is a ring-shaped coil and is sleeved on the outside of the immersion nozzle (1); the moving component (5) is installed on one side of the immersion nozzle (1), and the electromagnetic induction component (4) is installed on the moving component (5) and moves with the moving component (5); the electromagnetic induction component (4) is electrically connected to the computer (6), and alternating current is passed through the electromagnetic induction component (4) to generate a magnetic field. The molten steel inside the immersion nozzle (1) flows in the magnetic field and is squeezed by the electromagnetic pinch force, so that the internal pressure of the immersion nozzle (1) increases and the pressure difference with the external pressure of the immersion nozzle (1) decreases.

2. The device for alleviating negative pressure of an immersion nozzle according to claim 1, characterized in that: The electromagnetic induction component (4) is concentric with the submerged nozzle (1).

3. The device for alleviating negative pressure of an immersion nozzle according to claim 1, characterized in that: The moving assembly (5) comprises a base (51), a longitudinal servo mechanism (52) and a transverse servo mechanism (53); a track is provided on the base (51), and the transverse servo mechanism (53) cooperates with the track; the longitudinal servo mechanism (52) is connected to the transverse servo mechanism (53); and the electromagnetic induction assembly (4) is mounted on the longitudinal servo assembly.

4. The device for alleviating negative pressure of an immersion nozzle according to claim 3, characterized in that: The lifting height of the longitudinal servo mechanism (52) is 0-500 mm.

5. The device for alleviating negative pressure of an immersion nozzle according to claim 1, characterized in that: The AC current has a magnitude of 0-2000A, a frequency of 1-100Hz, and an electromagnetic induction power of 0-3000kW.

6. The device for alleviating negative pressure of an immersion nozzle according to claim 1, characterized in that: The interior of the electromagnetic induction component (4) is cooled by water, wind or mist.

7. The device for alleviating negative pressure of an immersion nozzle according to claim 1, characterized in that: The electromagnetic induction component (4) is sleeved on the middle part of the outer side of the immersion water inlet (1) or close to one end of the crystallizer (3).

8. The device for alleviating negative pressure of an immersion nozzle according to claim 1, characterized in that: The electromagnetic induction component (4) is an open or closed ring.

9. The device for alleviating negative pressure of an immersion nozzle according to claim 1, characterized in that: The submerged nozzle (1) is of a single-hole, double-hole or four-hole type.

10. The device for alleviating negative pressure of an immersion nozzle according to claim 1, characterized in that: The mitigation device further comprises a flow control component, which is installed at an end of the tundish that is not connected to the submerged water inlet (1).

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