Submerged nozzle suitable for electromagnetic stirring of crystallizer

Abstract

The utility model belongs to the steel metallurgy technical field, specifically discloses a kind of submerged entry nozzle suitable for crystallizer electromagnetic stirring, including straight-through type's submerged entry nozzle, multiple oval guide piers are symmetrically arranged in the center of submerged entry nozzle outer wall, the oval guide pier is below the surface of molten steel, and close to the lower end of submerged entry nozzle.The utility model is simple in structure, flexible and good in adaptability, low in energy consumption, good in impurity removal effect, effectively improves submerged entry nozzle life.

Description

Technical Field

[0001] This utility model belongs to the field of iron and steel metallurgy technology, and more specifically, it is an immersion nozzle suitable for electromagnetic stirring of crystallizers. Background Technology

[0002] Grain-oriented silicon steel is a soft magnetic functional steel material used to manufacture stator cores for various transformers and large motors. Grain-oriented silicon steel contains approximately 3% silicon. Oxide inclusions are easily formed in steel after aluminum deoxidation. Sulfur and nitrogen are inhibitory elements in steel formation; the billet has a high content of sulfur and nitrogen, and M is generated during continuous casting. n S and AlN tend to form segregation bands in the center of steel billets, affecting the uniformity of the steel microstructure. Inclusions in grain-oriented silicon steel not only affect the surface quality of the steel but also deteriorate its magnetic properties. Therefore, the control of inclusions in grain-oriented silicon steel is extremely stringent.

[0003] Traditional submersible nozzles in crystallizers lack flow guidance. When electromagnetic stirring is applied within the crystallizer, the reflux area of ​​the molten steel shrinks, and the reflux speed increases, making it difficult for inclusions in the molten steel to float to the surface for removal. On the other hand, submersible nozzles are subjected to high-speed reflux scouring, resulting in a shortened lifespan.

[0004] Patent No. 99101507.X discloses an "X"-shaped immersion nozzle that enables the molten steel inside the crystallizer to rotate. It forms two smooth spiral flow channels by setting two equally intersecting semi-elliptical guide plates (2, 3) at the lower part of the inverted conical cylindrical cavity (1). This nozzle has an electromagnetic stirring function within the crystallizer, reducing equipment investment and saving energy. However, it cannot solve the problem of inclusions in the molten steel having insufficient time to float and be removed.

[0005] Therefore, those skilled in the art expect to solve the problem of removing inclusions in molten steel under electromagnetic stirring, to be applicable to molten steel rinsing at different flow rates, and to improve the service life of submerged nozzles. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned technical problems and provide an immersion nozzle suitable for electromagnetic stirring in crystallizers, which has a simple structure, good flexibility and adaptability, low energy consumption, good impurity removal effect, and effectively improves the service life of the immersion nozzle.

[0007] This utility model is applicable to the submersible nozzle of the electromagnetic stirring of the crystallizer, including a straight-through submersible nozzle, with multiple elliptical guide piers symmetrically arranged at the center of the outer wall of the submersible nozzle. The elliptical guide piers are located below the steel liquid surface and close to the lower end of the submersible nozzle.

[0008] Preferably, the major axis of the elliptical guide pier forms an angle with the central axis of the submersible nozzle.

[0009] Preferably, the included angle is 5-85°, and more preferably, the included angle is 25-35°.

[0010] Preferably, the major axis of the elliptical guide pier is 0.4-0.6 times the inner diameter of the submersible nozzle.

[0011] Preferably, the minor axis of the elliptical guide pier is 0.2-0.3 times the inner diameter of the submersible nozzle.

[0012] Preferably, the thickness of the elliptical guide pier is 0.1-0.2 times the inner diameter of the submersible nozzle.

[0013] Preferably, the plurality of elliptical guide piers are located at a distance of more than 80 mm from the molten steel surface.

[0014] Preferably, the elliptical guide pier is 10-20mm away from the lower end of the immersion nozzle.

[0015] To address the problems existing in the background technology, this application analyzes in depth the characteristics of the reflux zone of molten steel after electromagnetic stirring is applied in the crystallizer. Multiple elliptical guide piers are symmetrically arranged at the center of the outer wall of the submerged nozzle. The streamlined contour of the ellipse can conform to the natural movement trajectory of the water flow to the greatest extent, avoiding the formation of violent impacts or vortices on the surface of the pier. Compared with rectangular and square guide piers, the ellipse has no obvious edges and corners. When the water flows through, it will not generate local high pressure or negative pressure zones at the corners, greatly reducing the "flow separation" phenomenon and reducing head loss. Compared with circular guide piers, the ellipse can be more flexibly adapted to different water flow directions (such as oblique flow) through the design of the ratio of the major and minor axes and the control of the included angle, further optimizing the smoothness of the water flow, reducing the lateral impact force of the water flow on the pier, and improving the impurity removal effect.

[0016] The elliptical guide pier is located below the molten steel surface and close to the lower end of the submerged nozzle. Setting the guide pier at this location will not affect the original stirring effect of the electromagnetic stirrer. It only affects the upward flow in the crystallizer. That is, it does not occur around the submerged nozzle in the electromagnetic stirring area. The elliptical guide pier effectively slows down the upward flow, reduces the exposure of the liquid surface, and directly forms a local vortex to remove inclusions and improve the removal efficiency of inclusions. This inclusion removal process does not require external field, saving energy. Preferably, the elliptical guide pier is 10~20mm away from the lower end of the submerged nozzle.

[0017] On the other hand, the elliptical curved surface structure can more evenly transfer the force of molten steel to the foundation, avoiding stress concentration and improving the overall structure's resistance to scour and damage. The impact force of molten steel on the elliptical pier is more evenly distributed, with no obvious stress concentration points, which can reduce the local scour depth on the liquid-facing side of the pier and reduce the risk of foundation hollowing. Compared with irregularly shaped or angular piers, the molten steel flow velocity distribution on the elliptical surface is more stable, which can reduce wear on the surface of the molten steel pier and greatly extend the service life of the structure. Preferably, the major axis of the elliptical guide pier is 0.4-0.6 times the inner diameter of the submerged nozzle; the minor axis of the elliptical guide pier is 0.2-0.3 times the inner diameter of the submerged nozzle; and the thickness of the elliptical guide pier is 0.1-0.2 times the inner diameter of the submerged nozzle.

[0018] In summary, since the molten steel recirculation under electromagnetic stirring must pass through the submerged nozzle, the elliptical guide piers can collide with, adsorb, and capture inclusions in the molten steel. The eddies generated around the submerged nozzle by the elliptical guide piers reduce the scouring speed of the molten steel and improve the service life of the submerged nozzle. Attached Figure Description

[0019] Figure 1 This is a perspective view of the present utility model.

[0020] Figure 2 This is a perspective view of the installation of this utility model in a crystallizer.

[0021] Figure 3 This is a top view of the present invention in a crystallizer.

[0022] Figure 4 The diagram shows the internal flow field of the crystallizer using the immersion nozzle of this invention.

[0023] Figure 5 This is a flow field diagram inside a crystallizer using a traditional immersion nozzle.

[0024] Among them, 1-immersion inlet; 2-elliptical guide pier; 3-square crystallizer; 4-electromagnetic stirring device. Detailed Implementation

[0025] The technical solutions (including preferred technical solutions) of this application will be further described in detail below with reference to the accompanying drawings and by listing some optional embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0026] In this embodiment, the submersible nozzle 1 is a straight-through submersible nozzle, and multiple elliptical guide piers 2 (four in this embodiment) are symmetrically arranged at the center of the outer wall of the submersible nozzle 1. The elliptical guide piers 2 are located below the steel liquid surface (preferably more than 80 mm away from the steel liquid surface) and 10-20 mm away from the lower end of the submersible nozzle 1.

[0027] Furthermore, the major axis of the elliptical guide pier 2 and the central axis of the submersible nozzle form an angle α. The angle ranges from 5 to 85° and can be rationally designed according to different water flow directions (such as oblique flow). More preferably, the angle is 25-35°. If the oblique flow angle is large, the angle α should be smaller, and vice versa, to effectively slow down the upflow, reduce liquid surface exposure, and directly form local vortices to remove impurities and improve the efficiency of impurity removal. The major axis of the elliptical guide pier is 0.4-0.6 times the inner diameter of the submerged water inlet 1, the minor axis is 0.2-0.3 times the inner diameter of the submerged water inlet, and the thickness of the elliptical guide pier is 0.1-0.2 times the inner diameter of the submerged water inlet.

[0028] Under electromagnetic stirring, the molten steel flows back to the submerged entry nozzle 1 at a high speed. Through the four elliptical guide piers 2 set around the submerged entry nozzle 1, a local vortex is formed, which causes inclusions to be deposited at the submerged entry nozzle 1 by collision with the vortex, thereby effectively purifying the molten steel.

[0029] Experiment: The parameters for the comparative experiment are as follows: the billet width is 390mm, the narrow width is 320mm, the casting speed is 0.5m / min; the calculated length of the crystallizer is 2000mm, and the density of the molten steel is 7100kg / m³. 3 Viscosity is 5.50 x 10⁻⁶ -3 kg / (m·s), electrical conductivity 7.14×10 5 The copper plate has a relative permeability of 1.0, a thermal conductivity of 34 W / (m·K), a specific heat of 680 J / (kg·K), a casting temperature of 1763 K, and a liquidus temperature of 1739 K; the copper plate has an electrical conductivity of 4.7 × 10⁻⁶ W / (m·K). 7 S / m; the relative permeability of the iron core is 1000; the stirrer coil current intensity is 450A and the frequency is 1.5HZ.

[0030] See Figure 1The immersion nozzle 1 of this utility model is installed in a square crystallizer 3. An electromagnetic stirring device 4 is provided on the outer periphery of the square crystallizer 3. The elliptical guide pier 2 is located 100 mm below the steel liquid surface and 15 mm away from the lower end of the immersion nozzle 1. The major axis of the elliptical guide pier 2 and the central axis of the immersion nozzle have an angle α of 30°. The major axis of the elliptical guide pier 2 is 0.4 times the inner diameter of the immersion nozzle 1, the minor axis is 0.2 times the inner diameter of the immersion nozzle 1, and the thickness is 0.1 times the inner diameter of the immersion nozzle 1.

[0031] In the comparative experiment, the submersible nozzle was not equipped with a guide pier, while the rest were the same.

[0032] See the experimental results. Figure 4 The immersion inlet of this invention, under the action of the elliptical guide pier, significantly improves the flow field at the inlet, while the flow field around the inlet becomes more chaotic, forming local eddies. This is in contrast to the flow field around a traditional straight-through immersion inlet without the elliptical guide pier (see...). Figure 5 The maximum impact velocity was reduced from 0.98 m / s to 0.87 m / s, which significantly improved the flow field inside the crystallizer, effectively reduced the dead zone area in the flow field, reduced the impact of molten steel on the inlet, and extended the service life of the inlet.

[0033] It will be readily understood by those skilled in the art that the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, combinations, substitutions, improvements, etc., made under the spirit and principles of this application are included within the protection scope of this application.

Claims

1. A submersible nozzle suitable for electromagnetic stirring in a crystallizer, comprising a straight-through submersible nozzle, characterized in that, Multiple elliptical guide piers are symmetrically arranged along the center on the outer wall of the submerged nozzle. The elliptical guide piers are located below the steel liquid surface and close to the lower end of the submerged nozzle.

2. The immersion nozzle for electromagnetic stirring in a crystallizer as described in claim 1, characterized in that, The major axis of the elliptical guide pier forms an angle with the central axis of the submersible nozzle.

3. The immersion nozzle for electromagnetic stirring in a crystallizer as described in claim 2, characterized in that, The included angle is 5-85°.

4. The immersion nozzle for electromagnetic stirring in a crystallizer as described in claim 3, characterized in that, The included angle is 25-35°.

5. The immersion nozzle for electromagnetic stirring in a crystallizer as described in any one of claims 1-4, characterized in that, The major axis of the elliptical guide pier is 0.4-0.6 times the inner diameter of the submerged water inlet.

6. The immersion nozzle for electromagnetic stirring in a crystallizer as described in claim 5, characterized in that, The minor axis of the elliptical guide pier is 0.2-0.3 times the inner diameter of the submerged water inlet.

7. The immersion nozzle for electromagnetic stirring in a crystallizer as described in any one of claims 1-4, characterized in that, The thickness of the elliptical guide pier is 0.1-0.2 times the inner diameter of the submerged water inlet.

8. The immersion nozzle for electromagnetic stirring in a crystallizer as described in claim 1, characterized in that, The multiple elliptical guide piers are located at a distance of more than 80 mm from the molten steel surface.

9. The immersion nozzle for electromagnetic stirring in a crystallizer as described in claim 1, characterized in that, The elliptical guide pier is located 10-20 mm from the lower end of the submersible inlet.

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