Submersed nozzle capable of improving filling rate of side hole

Abstract

The invention discloses a submersed nozzle capable of improving the filling rate of a side hole, which comprises a nozzle body, the lower side part of the nozzle body is provided with the side hole, and the submersed nozzle is characterized in that the upper edge of the side hole is curve-shaped; the bottom of the outer side of the upper edge of the side hole is taken as an origin of coordinates, and the curvilinear equation is based on the inner cavity flow velocity v of the submersed nozzle: when the inner cavity flow velocity v is more than or equal to 0 and less than 1m / s, the curvilinear equation is y = 1 * 10x-4; when the flow velocity v of the inner cavity is greater than or equal to 1 and less than 2m / s, the curvilinear equation is y = 5 * 10x-4; and when the flow velocity v of the inner cavity is greater than or equal to 2 and less than 3m / s, the curvilinear equation is y = 10 * 10x-4. The nozzle promotes molten steel flow to generate a wall attachment effect in the nozzle, so that molten steel flows along a curve in the inner cavity of the nozzle and flows out from the upper edge of the nozzle, and the filling rate of a side hole of the submersed nozzle is further improved; the filling rate of the side hole of the submersed nozzle can be increased to more than 90%, the distribution nonuniformity of a flow field in a crystallizer is obviously improved, and the generation of bias current is avoided; the internal flow velocity of the crystallizer can be effectively reduced, and the impact force of steel flow on a casting blank new green shell is relieved.

Description

Technical Field

[0001] The invention relates to the technical field of continuous casting, in particular to an immersed nozzle capable of improving the filling rate of side holes. Background Art

[0002] In the continuous casting process, the submerged nozzle serves as a key flow-guiding device between the tundish and the crystallizer, and its structural design directly affects the flow pattern of molten steel and the quality of the ingot. Traditional submerged nozzles achieve symmetrical distribution of molten steel in the crystallizer through side holes, but in actual applications, there is a common technical bottleneck of insufficient side hole filling rate. When the molten steel flows out of the side hole, under the action of inertia and gravity, the mainstream of the steel flow flows out along the lower edge of the side hole, and a negative pressure zone is generated in the upper area of ​​the side hole, causing the steel flow to reflux. The side hole filling rate of the submerged nozzle is less than 50%. A low side hole filling rate may cause inclusion accumulation and nozzle nodules, and also increase the probability of flow deviation in the crystallizer. This not only reduces the uniformity of the molten steel flow field in the crystallizer, but also causes ingot defects such as slag curls, pores, and cracks.

[0003] In the prior art, researchers have often attempted to improve the fill rate of submerged nozzle side holes by adjusting their shape, inclination, or other methods. For example, Chinese patent CN110125379A proposes a submerged nozzle that can reduce nozzle blockage. While rounding the top edge of the nozzle can reduce backflow to a certain extent, its effectiveness is significantly affected by the rounding radius, making it limited in its widespread applicability. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an immersion nozzle with improved side hole filling rate, so as to effectively improve the quality of the casting.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: it includes a nozzle body, a side hole is provided on the lower side of the nozzle body, and the upper edge of the side hole is curved; the outer bottom of the upper edge of the side hole is used as the coordinate origin, and the curve equation is based on the inner cavity flow velocity v of the immersion nozzle: when the inner cavity flow velocity is less than 1m / s, the curve equation is y=1×10x -4 When the flow velocity in the inner cavity is 1≤v<2m / s, the curve equation is y=5×10x -4 When the flow velocity in the inner cavity is 2≤v<3m / s, the curve equation is y=10×10x -4 .

[0006] Furthermore, the inclination angle of the lower edge of the side hole of the submerged water outlet is 0°.

[0007] Furthermore, the bottom of the submerged nozzle adopts an arc-shaped groove structure with a radius of 20 to 50 mm, and the center of the circle is the intersection of the center line of the side hole and the center line of the nozzle inner cavity.

[0008] The beneficial effects of the above-mentioned technical solution are as follows: the present invention designs the upper edge of the side hole of the submerged nozzle into a curved shape, which promotes the wall adhesion effect of the molten steel stream inside the nozzle, causing the molten steel to flow along the curve in the nozzle cavity and out from the upper edge of the nozzle, thereby improving the filling rate of the submerged nozzle side hole. The present invention can increase the filling rate of the submerged nozzle side hole to over 90%, significantly improving the uneven distribution of the flow field inside the crystallizer, avoiding the occurrence of biased flow, and preventing the occurrence of biased flow. It can also effectively reduce the flow velocity inside the crystallizer, reducing the impact of the steel flow on the newly formed shell of the ingot, which is beneficial to improving the stability and uniformity of the growth of the primary shell in the crystallizer, and reducing surface defects such as longitudinal cracks and depressions caused by flow field distribution problems.

[0009] The present invention designs the inclination angle of the lower edge of the nozzle to be 0°, which can effectively reduce the impact depth of the steel flow and avoid the scouring effect of the jet on the narrow surface shell.

[0010] The present invention adopts a spherical round bottom structure in the bottom area of ​​the water inlet. Compared with the traditional concave and convex structures, the spherical structure can appropriately reduce the flow energy of the steel, avoid the jet scouring the newly formed shell on the narrow surface of the crystallizer, and at the same time maintain the intensity of the backflow on the crystallizer to avoid the crystallizer liquid level from becoming too low in activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0012] Figure 1 This is a schematic diagram of the cross-sectional structure of the side hole of a traditional submerged nozzle; Figure 2 Schematic diagram of the cross-sectional structure of the side hole of the submerged nozzle of the present invention; Figure 3 This is a schematic diagram of the side hole filling rate of a traditional submerged nozzle; Figure 4 This is a schematic diagram of the side hole filling rate of the submerged nozzle described in Example 1; Figure 5 This is a schematic diagram of the side hole filling rate of the submerged nozzle described in Example 2; Figure 6 This is a schematic diagram of the side hole filling rate of the submerged nozzle described in Example 3.

[0013] In the figure: 1-upper edge of the side hole, 2-bottom of the sprue, 3-lower edge of the side hole. DETAILED DESCRIPTION

[0014] When there is surface friction between the fluid and the surface of the object it flows through, as long as the curvature is not large, the fluid will flow along the surface of the object. This is the wall effect. Numerical simulation studies in recent years have shown that the rational use of the wall effect can make the steel flow close to the side hole wall to form a stable viscous boundary layer, thereby improving the filling rate of the immersed side hole. Based on this, Figure 2As shown, the submerged nozzle for improving the side hole filling rate adopts the following design structure: (1) The upper edge 1 of the side hole of the submerged nozzle is designed to be curved, and the curvature satisfies the wall attachment effect. The specific curve equation is based on the flow velocity v in the nozzle cavity, as follows: the outer bottom of the upper edge 1 of the side hole is the coordinate origin, the inward direction is the x-axis, and the upward direction is the y-axis. When the cavity flow velocity v is less than 1m / s, the curve equation is y=1×10x -4 When the inner cavity flow velocity v is 1≤v<2m / s, the curve equation is y=5×10x -4 When the inner cavity flow velocity v is 2≤v<3m / s, the curve equation is y=10×10x -4 The inner cavity flow velocity v is calculated using the formula v=b×c / a, where a is the cross-sectional area of ​​the nozzle inner cavity, b is the cross-sectional area of ​​the billet, and c is the casting speed.

[0015] (2) The lower edge of the side hole of the submerged nozzle is designed with an inclination angle of 0° to keep it horizontal to reduce the impact depth of the steel flow; (4) The bottom 2 of the immersion nozzle adopts an arc-shaped groove structure to reduce the loss of steel flow energy. The radius of the circle where the arc-shaped groove is located is 20 to 50 mm, and the center of the circle is the intersection of the center line of the side hole and the center line of the nozzle cavity.

[0016] Example 1: The submerged nozzle for improving the side hole filling rate is specifically described as follows: Casting conditions: billet cross-section 250mm×2400mm, casting speed 0.95m / min, submerged nozzle cavity area 0.005m 2 .

[0017] (1) According to the law of conservation of mass, the flow velocity in the inner cavity of the submerged nozzle can be calculated as v = 0.25 × 2.4 × 0.95 / 60 / 0.005 = 1.9 m / s, so the equation of the upper edge curve of the nozzle is selected as y = 5 × 10x -4 .

[0018] (2) The inclination angle of the lower edge of the side hole of the submerged nozzle is designed to be 0° to maintain horizontality.

[0019] (3) The bottom of the nozzle is designed as an arc structure with an internal arc bottom radius of 20 mm. The center of the circle is the intersection of the center line of the side hole and the center line of the nozzle cavity.

[0020] (4) Commercial fluid mechanics software is used to analyze the submerged nozzle and Figure 1 The mold flow field of the traditional submerged nozzle is modeled and calculated, and the comparison of the side hole filling effects of two different designs of submerged nozzles is shown in Figure 3 and Figure 4 Among them, except for the above differences, other parameters of the submerged nozzle in this example are consistent with those of the traditional submerged nozzle.

[0021] from Figure 2 It can be seen that after the traditional submerged nozzle flows out from the side hole of the nozzle, the flow stream mainly flows out from the lower edge of the nozzle. At the upper edge of the nozzle, it can be observed that the molten steel will flow back into the nozzle from the inside of the crystallizer, resulting in a side hole filling rate of only 40%. The nozzle flow stream designed in this example almost fills the entire side hole outlet, with a filling rate of 91%. At the same time, the overall speed of the steel flow is reduced.

[0022] Example 2: The submerged nozzle for improving the side hole filling rate is specifically described as follows: Casting conditions: billet cross-section 200mm×1200mm, casting speed 1.20m / min, submerged nozzle cavity area 0.005m 2 .

[0023] (1) According to the law of conservation of mass, the flow velocity in the inner cavity of the submerged nozzle can be calculated as v = 0.2 × 1.2 × 1.2 / 60 / 0.005 = 0.96 m / s, and the equation of the upper edge curve of the nozzle is selected as y = 1 × 10x -4 .

[0024] (2) The inclination angle of the lower edge of the side hole of the submerged nozzle is designed to be 0° to maintain horizontality.

[0025] (3) The bottom of the nozzle is designed as an arc structure with an internal arc bottom radius of 20 mm. The center of the circle is the intersection of the center line of the side hole and the center line of the nozzle cavity.

[0026] (4) Commercial fluid mechanics software is used to analyze the submerged nozzle and Figure 1 The mold flow field of the traditional submerged nozzle is modeled and calculated, and the comparison of the side hole filling effects of two different designs of submerged nozzles is shown in Figure 3 and Figure 5 Among them, except for the above differences, other parameters of the submerged nozzle in this example are consistent with those of the traditional submerged nozzle.

[0027] from Figure 5 It can be seen that the nozzle flow stream designed in this example almost fills the entire side hole outlet, with a filling rate of 93%, while the overall speed of the steel flow is reduced.

[0028] Example 3: The submerged nozzle for improving the side hole filling rate is specifically described as follows: Casting conditions: billet cross-section 330mm×2400mm, casting speed 0.80m / min, submerged nozzle cavity area 0.005m 2 .

[0029] (1) According to the law of conservation of mass, the flow velocity in the inner cavity of the submerged nozzle can be calculated as v = 0.33 × 2.4 × 0.8 / 60 / 0.005 = 2.11 m / s, and the equation of the upper edge curve of the nozzle is selected as y = 10 × 10x-4 .

[0030] (2) The inclination angle of the lower edge of the side hole of the submerged nozzle is designed to be 0° to maintain horizontality.

[0031] (3) The bottom of the nozzle is designed as an arc structure with an internal arc bottom radius of 20 mm. The center of the circle is the intersection of the center line of the side hole and the center line of the nozzle cavity.

[0032] (4) Commercial fluid mechanics software is used to analyze the submerged nozzle and Figure 1 The mold flow field of the traditional submerged nozzle is modeled and calculated, and the comparison of the side hole filling effects of two different designs of submerged nozzles is shown in Figure 3 and Figure 6 Among them, except for the above differences, other parameters of the submerged nozzle in this example are consistent with those of the traditional submerged nozzle.

[0033] from Figure 6 It can be seen that the nozzle flow stream designed in this example almost fills the entire side hole outlet, with a filling rate of 92%, while the overall speed of the steel flow is reduced.

[0034] From the above comparison, it can be seen that under the same working conditions, the submerged nozzle in this example can increase the side hole filling rate of the submerged nozzle to more than 90%, while also significantly reducing the flow velocity inside the crystallizer and reducing the impact of the steel flow on the newly formed shell of the ingot.

Claims

1. An immersion nozzle with improved side hole filling rate, comprising a nozzle body, with side holes provided on the lower side of the nozzle body, characterized in that: The upper edge of the side hole is curved; the outer bottom of the upper edge of the side hole is the coordinate origin, and the curve equation is based on the inner cavity flow velocity v of the immersion nozzle: when the inner cavity flow velocity is v<1m / s, the curve equation is y=1×10x -4 When the flow velocity in the inner cavity is 1≤v<2m / s, the curve equation is y=5×10x -4 When the flow velocity in the inner cavity is 2≤v<3m / s, the curve equation is y=10×10x -4 .

2. The submerged nozzle for improving the side hole filling rate according to claim 1, characterized in that: The inclination angle of the lower edge of the side hole of the submerged water outlet is 0°.

3. The submerged nozzle for improving the side hole filling rate according to claim 1 or 2, characterized in that: The bottom of the submerged nozzle adopts an arc-shaped groove structure with a radius of 20 to 50 mm, and the center of the circle is the intersection of the center line of the side hole and the center line of the nozzle inner cavity.

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