Shunt type flow stabilizer

Abstract

The present invention discloses a long and large flow stabilizer for strengthening inclusion collision, which solves the problem that the flow stabilization performance of the existing flow stabilizer needs to be further improved and the inclusion removal effect is not good. The technical solution includes a main body with a cavity, and the main body is provided with a special-shaped through-flow guide hole inclined upward by 30 degrees on the symmetrical side, the top surface opening of the main body is connected to the cavity, and the bottom surface of the cavity is annularly arrayed with eight triangular prism-shaped blocks of the same height. The present invention has a simple structure, low cost, buffers the injection of molten steel, reduces secondary oxidation, effectively captures and removes inclusions in the pouring, and is particularly effective in reducing large and medium-sized inclusions in the molten steel.

Description

Technical Field

[0001] The invention relates to the field of smelting, in particular to a flow stabilizer for a continuous casting tundish. Background Art

[0002] In recent years, my country's high-quality steel has developed rapidly, and the total output has reached 230 million tons by 2019. High-quality steel is widely used in various industries. Due to the traction of demand, the cleanliness requirements for high-quality steel are getting higher and higher. The key to improving and stabilizing the quality of steel is to further reduce the level of non-metallic inclusions in steel.

[0003] As a unique link in the continuous casting process, the tundish exposes the molten steel to the atmosphere and slag environment for a long time to ensure the continuous operation of the continuous casting production, which increases the probability of molten steel being contaminated and deteriorates the quality of the molten steel. In order to increase the output and yield of the ingot in modern continuous casting production, most of the production methods with high billet drawing speed and high crystallizer cooling intensity are adopted. Small-sized inclusions do not have enough time to collide, grow, float and be removed, and are discretely distributed on the ingot crystal interface and cannot be removed by rolling.

[0004] In order to remove fine inclusions, various flow control devices are designed in the continuous casting tundish to promote the floating removal of inclusions. However, inclusions with a diameter of less than 20μm are difficult to float and remove in the continuous casting tundish. Therefore, removing inclusions below 20μm has become a difficulty that limits the cleanliness of steel. Therefore, how to efficiently control the number of inclusions in the tundish during the continuous casting start-up phase is a technical key to further improving the quality of high-quality steel. Summary of the invention

[0005] The purpose of the present invention is to solve the above technical problems and provide a long and large flow stabilizer with a simple structure, low cost, buffering the injection of molten steel, reducing secondary oxidation, effectively capturing and removing inclusions in the pouring, especially reducing the number of large inclusions in the molten steel.

[0006] The technical solution of the present invention includes a main body with a cavity, wherein the opening on the top surface of the main body is connected to the cavity, and 4-10 triangular prism-shaped blocks are evenly arranged in a circular array with the center of the bottom surface of the cavity as the center of a circle. The multiple triangular prism-shaped blocks have the same height, and the distances and angles are equally divided.

[0007] The horizontal cross section of the triangular prism block is a triangle, the upper vertices of the multiple triangles are located on an inner circle with the center of the cavity bottom surface as the center, and the two lower vertices of the multiple triangles are located on an outer circle with the center of the cavity bottom surface as the center. The inner circle diameter is 1.1 to 1.2 times the diameter of the long nozzle, and the outer circle diameter is 2 to 2.1 times the inner circle diameter.

[0008] The height of the stopper is 1 / 9 to 4 / 9 of the height of the cavity.

[0009] The triangle is an isosceles triangle, the vertex angle is 74° to 80°, and the base angle is 50° to 53°.

[0010] The waist length of the isosceles triangle is 0.5 to 0.6 times the radius of the inner circle, and the base length is 0.7 to 0.8 times the radius of the inner circle.

[0011] The cavity has a spherical wall surface and a top surface and a bottom surface that are parallel to each other. The maximum diameter of the cavity in the horizontal direction is 1.1 to 1.2 times the minimum diameter.

[0012] Each side edge of the triangular prism stopper needs to be rounded with a radius of 2-5 mm.

[0013] The opening diameter of the body is 3 to 5 times the inner diameter of the long shroud.

[0014] Two guide holes are symmetrically arranged at the junction of the bottom surface of the body cavity and the side wall, tilted upward and penetrating the side wall.

[0015] The upward inclination angle of the hole guide hole is 30°-45°.

[0016] In order to solve the problems existing in the background technology, the present invention has made the following improvements:

[0017] (1) A plurality of triangular prism-shaped blocks are arranged in a ring at the bottom of the cavity, so that the pouring steel flow will make a violent turn in the cavity after impacting the flow stabilizer, disrupting the initial flow field in the tundish, increasing the residence time of the molten steel and the movement distance and collision probability of the inclusions. The height of the block is 1 / 9 to 4 / 9 of the height of the cavity. If the height of the block is too high, while reducing the volume of the cavity inside the flow stabilizer, the accumulation of molten steel between the blocks will be too large, and the high-speed injection flow will be difficult to penetrate the accumulated molten steel layer to reach the bottom of the cavity, thus forming a dead zone. If the height of the block is too low, it is difficult to form molten steel accumulation and bottom tumbling flow between the blocks, and the purpose of reducing the injection speed of the molten steel cannot be achieved.

[0018] (2) In the inner circle formed by the side edges of the triangular prism block, a high-pressure area is formed in this area due to the high speed of the molten steel flowing out of the long water outlet; when the molten steel flows out from the inner circle to the outside, it will flow into the channel between the adjacent triangular prism blocks. Since the upper vertex of the triangle is on the inner circle and the two bottom surface endpoints (two lower vertices) are on the outer circle, the channel from the inner circle to the outer circle gradually narrows, and part of the molten steel is accelerated to flow out of the outer circle area through the channel, but most of the flow is hindered to form an upward vortex and the secondary vortex formed accordingly; the central pressure of this strong vortex is relatively low, and fine inclusions with a diameter of less than 20μm in the flow will gather towards the low-pressure center, where they will collide and grow. When the clustered inclusion particles reach a certain size, they will float to the slag liquid surface under the action of Stokes buoyancy and be removed. The pressure change formed in the outer circle area can effectively break the fluid and prevent fine inclusion particles from entering the ingot with the flow at the bottom of the tundish and affecting the product quality; preferably, the inner circle diameter is 1.1 to 1.2 times the diameter of the long nozzle, and the outer circle diameter is 2 to 2.1 times the inner circle diameter. The inner circle diameter range is mainly set to allow more molten steel to flow out through the guide holes on both sides of the cavity bottom, so as to replace the overflow mode to flow out of the flow stabilizer. A too small inner circle diameter will reduce the volume of the flow stabilizer cavity and make it difficult to increase the residence time of the molten steel in the cavity. However, a too large inner circle diameter will cause the front injection flow to reduce the speed of the subsequent high-speed flow stream too much, so that the speed of the molten steel flow stream out of the guide hole is slowed down, and the guide hole is difficult to reach the slag-steel interface. The outer circle diameter range is required to be able to bear the static pressure of the molten steel and the impact of the high-speed jet. A too large outer circle diameter will increase the contact area between the flow stabilizer and the molten steel fluid and increase the probability of molten steel being contaminated, while increasing the use of refractory materials and increasing costs.

[0019] (3) The inclusions flowing through the passage between the triangular prism blocks will turn again and merge into the guide holes on the side wall of the flow stabilizer. The use of the oblique upward opening method can change the fluid movement state while providing an upward channel for the bottom inclusion particles, reducing the resistance of the upper fluid to the floating inclusion particle clusters, so that some particle clusters that do not meet the floating conditions can also reach the slag interface and be removed. Preferably, the upward inclination angle of the guide hole is 30°-45°. The control of the guide hole angle is mainly to enable more bottom molten steel streams to reach the slag interface to achieve the purpose of removing bottom inclusions. Therefore, the opening angle of the guide hole cannot be too small. A too small guide hole angle prolongs the length of the rising channel. When the speed of the molten steel stream flowing out of the stabilizer is too small, there is not enough power to reach the slag interface. A too large opening angle of the guide hole will also increase the difficulty of the bottom molten steel climbing. In addition, the wrong opening method makes the refractory material at the outlet of the guide hole too thin. When it is subjected to the impact of molten steel from the front, the stress is highly concentrated, which is easy to cause damage, increase endogenous inclusions, pollute the molten steel, reduce the service life of the stabilizer, and increase the cost.

[0020] The above method will greatly improve the removal efficiency of inclusions in the tundish, which will help improve the cleanliness of the molten steel and further improve the cleanliness of the steel.

[0021] Compared with the prior art, the present invention has the following positive effects:

[0022] 1. The structure of the present invention is extremely simple, all components are made of refractory materials, and the cost is low.

[0023] 2. The channel from the inner circle to the outer circle gradually narrows, and part of the molten steel accelerates to flow out of the outer circle area through the channel, but most of the flow is blocked to form an upward vortex and a secondary vortex. The central pressure of this strong vortex is relatively low, and fine inclusions with a diameter of less than 20μm in the flow will gather towards the low-pressure center, where they collide and grow, which is conducive to the formation of large-sized inclusion clusters for floating and removal.

[0024] 3. After the pouring steel flow hits the flow stabilizer, it will turn violently. The downward impacting liquid flow is blocked by the triangular prism block during the turning, which can effectively reduce the impact of subsequent molten steel injection, making the surface wave decay rapidly during the oscillation, thereby effectively reducing the liquid level fluctuation, while reducing the scouring of the injection flow on the refractory material and reducing the generation of foreign inclusions.

[0025] 4. Round the corners of the side edges of the triangular prism block to prevent the refractory material from breaking and contaminating the molten steel due to stress concentration.

[0026] Therefore, the flow stabilizer of the present invention not only has the characteristics of simple structure and low cost, but also can improve the flow field state of the injection area of ​​the tundish. The low-pressure vortex area formed by the triangular prism block can effectively capture fine inclusions with a diameter of less than 20 μm. The symmetrical guide holes of the flow stabilizer body provide an ascending channel for the bottom inclusions, so that the tundish can improve the cleanliness of the steel by improving the cleanliness of the molten steel during the smelting process, thereby improving the cleanliness of the steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a top view of the structure of the present invention;

[0028] Figure 2 It is a longitudinal cross-sectional view of the structure of the present invention;

[0029] Figure 3.1 , 3.2 This is a structural dimension diagram of the present invention;

[0030] Figure 4 Installation state diagram for the present invention;

[0031] Figure 5 To enhance the collision of inclusions, the fluid tracer in the large flow stabilizer is displayed;

[0032] Figure 6 This is a diagram showing the fluid tracing in a traditional flow stabilizer;

[0033] Figure 7 Fluid velocity diagram in the injection area of ​​a long and large flow stabilizer with enhanced inclusion collision.

[0034] Among them, 1-opening, 2-cavity, 2.1-top surface, 2.2-bottom surface, 2.3-side wall, 3-triangular prism-shaped stopper, 4-guide hole, 5-body, 6-inner circle, 7-outer circle, 8-long water outlet, 9-middle bag bottom. DETAILED DESCRIPTION

[0035] The present invention will be further explained below in conjunction with the accompanying drawings:

[0036] See also Figure 1 and Figure 2 The body 5 has a cavity 2 therein, the cavity 2 has a spherical wall 2.3 and a top surface 2.1 and a bottom surface 2.2 that are parallel to each other, the top surface opening 1 of the body is connected to the cavity 2, the bottom surface 2.2 of the cavity 2 is provided with a plurality of triangular prism-shaped blocks 3 (eight in this embodiment) arranged in a circular array, the upper vertex of the triangular prism block horizontal cross section is located on the inner circle 6, and the two end points (lower vertices) of the bottom are located on the outer circle 7, the inner circle 6 and the outer circle 7 are both centered on the center of the bottom surface 2.2 of the cavity 2, and two guide holes 4 penetrating the side wall are symmetrically arranged at the junction of the bottom surface 2.2 of the cavity 2 and the side wall 2.3. The upward inclination angle of the guide hole 4 is 30°-45°.

[0037] Specifically, the height h3 of the stopper is 1 / 9 to 4 / 9 of the height h1 of the cavity, the horizontal cross section of the triangle is an isosceles triangle, the vertex angle θ1 is 74° to 80°, the base angle θ2 is 50° to 53°, the waist length l1 of the triangle is 0.5 to 0.6 times the inner radius, and the base length l2 is 0.7 to 0.8 times the inner radius. The inner radius R1 is 1.1 to 1.2 times the radius of the long shroud, and the outer radius R2 is 2 to 2.1 times the inner radius R1; the opening diameter d2 of the body is 3 to 5 times the inner diameter of the long shroud.

[0038] The bottom surface 2.2 of the cavity 2 and the triangular prism block 3 are integrally formed and made of refractory material; the block 3 is a CaO-MgO refractory material column, which will be transformed into a plastic material after being heated by molten steel;

[0039] Reference Figure 4 The present invention is installed just below the long shroud 8 of the continuous casting tundish, with its axis coinciding with the axis coinciding with the long shroud 8 of the continuous casting tundish, and the body 4 of the flow stabilizer is embedded in the bottom 9 of the continuous casting tundish.

[0040] The following takes an application of the device of the present invention as an example to evaluate its technical effect:

[0041] The depth of the molten steel pool in the tundish of a steel plant is 1200mm, the inner diameter of the shroud is 120mm, the insertion depth of the shroud is 500mm, and the height from the shroud outlet to the bottom of the tundish is 700mm.

[0042] The height h3 of the triangular prism block is 30mm, the vertical angle θ1 of the horizontal cross-section triangle of the triangular prism block is 74°, the bottom angle θ2 is 53°, the inner radius R1 is 85mm, the outer radius R2 is 172mm, the triangle waist length l1 is 100mm, and the triangle bottom length l2 is 120mm. The body 5 is embedded in the bottom 9 of the continuous casting tundish, located directly below the long shroud 8 of the tundish, and its axis coincides with the axis of the long shroud 8.

[0043] The height h1 of the cavity in the body 5 is 200 mm, and the diameter d2 of the top opening 1 is 550 mm; the top surface 2.1 and the bottom surface 2.2 of the cavity are parallel and have a diameter of 550 mm, and the outer diameter d1 of the body 5 is 720 mm.

[0044] According to the simulation results of the large commercial software ANSYS, compared with the traditional tundish flow stabilizer without baffles, the large flow stabilizer with enhanced inclusion collision has increased the removal rate of fine inclusions with a diameter less than 20μm from 35.34% to 44.04%, effectively alleviating the problem of fine inclusions at the bottom of the flow being difficult to remove, and achieving the purpose of purifying the molten steel. Figure 5By comparison with Figure 6, it can be seen that the flow field movement form of the molten steel flow has changed after it reaches the bottom of the flow stabilizer. Due to the obstruction of the triangular prism-shaped baffle, the initial flow is accumulated in the channel between the shrinking baffles to form a liquid wall, which blocks the subsequent molten steel flow to form a surge and reduce the kinetic energy of the molten steel. The combined effect of the gradually narrowing fluid channel and the large contact area of ​​the side slope of the triangular prism baffle makes more fine inclusions reach the adhesion threshold and adhere to the surface of the refractory material of the flow stabilizer for removal.

[0045] like Figure 7 As shown in the figure, after the front end of the molten steel stream reaches the steel-slag interface, a horizontal divergent flow is formed at the top of the flow field. According to the flow field calculation results, the time for the front end of the stream to reach the steel-slag interface after the molten steel is injected through the blockless flow stabilizer is 11s, while the time for the stream to reach the working interface is increased to 20s after the large flow stabilizer with enhanced inclusion collision optimizes the molten steel flow field. This shows that the optimized flow stabilizer structure greatly prolongs the average residence time of the molten steel in the tundish, which is beneficial to the uniformity of the molten steel temperature, composition and velocity.

Claims

1. A long and large flow stabilizer for strengthening inclusion collision, comprising a body with a cavity, wherein an opening on the top surface of the body is connected to the cavity, characterized in that: With the center of the cavity bottom surface as the center of the circle, 4-10 triangular prism-shaped blocks are evenly arranged in a circular array, and the heights of the multiple triangular prism-shaped blocks are the same, and the distances and angles are equally divided; the horizontal cross-section of the triangular prism-shaped blocks is a triangle, and the upper vertices of the multiple triangles are located on an inner circle with the center of the cavity bottom surface as the center of the circle, and the two lower vertices of the multiple triangles are located on an outer circle with the center of the cavity bottom surface as the center of the circle.

2. The long flow stabilizer for strengthening inclusion collision as claimed in claim 1, characterized in that: The inner diameter is 1.1 to 1.2 times the diameter of the long shroud, and the outer diameter is 2 to 2.1 times the inner diameter.

3. The long flow stabilizer for strengthening inclusion collision as claimed in claim 1, characterized in that: The height of the stopper is 1 / 9 to 4 / 9 of the height of the cavity.

4. The long flow stabilizer for strengthening inclusion collision as claimed in claim 2, characterized in that: The triangle is an isosceles triangle, the vertex angle is 74° to 80°, and the base angle is 50° to 53°.

5. The long flow stabilizer for strengthening inclusion collision as claimed in claim 4, characterized in that: The waist length of the isosceles triangle is 0.5 to 0.6 times the radius of the inner circle, and the base length is 0.7 to 0.8 times the radius of the inner circle.

6. The long flow stabilizer for strengthening inclusion collision according to any one of claims 1 to 5, characterized in that: The cavity has a spherical wall surface and a top surface and a bottom surface that are parallel to each other. The maximum diameter of the cavity in the horizontal direction is 1.1 to 1.2 times the minimum diameter.

7. The long flow stabilizer for strengthening inclusion collision according to any one of claims 1 to 5, characterized in that: Each side edge of the triangular prism-shaped stopper needs to be rounded with a radius of 2-5 mm.

8. The long flow stabilizer for strengthening inclusion collision according to any one of claims 1 to 5, characterized in that: The opening diameter of the body is 3 to 5 times the inner diameter of the long shroud.

9. The long flow stabilizer for strengthening inclusion collision according to any one of claims 1 to 5, characterized in that: Two flow guide holes that are inclined upward and penetrate the side wall are symmetrically arranged at the junction of the bottom surface of the body cavity and the side wall.

10. The long flow stabilizer for strengthening inclusion collision as claimed in claim 9, characterized in that: The guide hole is inclined upward at an angle of 30°-45°.

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