Bell-jar-shaped sleeve for slab continuous casting ladle and using method of bell-jar-shaped sleeve

Abstract

The invention discloses a slab continuous casting ladle bell jar type sleeve and a using method thereof, and relates to the technical field of metallurgy. The long nozzle is arranged at the lower end of the sleeve body; the diameter of an inner cavity of the long nozzle is larger than that of an inner cavity of the sleeve body. The trumpet-shaped long nozzle is formed in the lower end of the sleeve body, and the enlarged volume can accommodate hot air to realize immersion casting, so that secondary pollution of molten steel and entrainment of a covering agent during ladle replacement are avoided. Compared with a straight cylinder type long nozzle, the horn-shaped long nozzle has the advantages that the outlet speed of the horn-shaped long nozzle is low, impact on a tundish molten pool and tundish liquid level fluctuation are reduced, and slag entrapment and secondary oxidation in an impact area are relieved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a bell-shaped casing for a slab continuous casting ladle and a use method thereof. Background Art

[0002] The secondary oxidation of molten steel will have an adverse effect on the production of clean steel, especially for steel with high cleanliness requirements. If it is not well controlled, it will easily cause problems such as unqualified steel flaw detection, which will seriously affect the quality improvement of steel, especially for high-end steel such as Nangang plate pipeline steel and nickel steel. The cleanliness of molten steel after refining process is relatively high, but due to the poor protection of ladle-middle ladle-crystallizer, the molten steel will be secondary oxidized, which is reflected in the increase of inclusion content in steel, and high content of [O] and [N].

[0003] During the continuous casting process, the flow behavior of molten steel in the tundish is closely related to the metallurgical effect of the tundish. Reasonable flow field control can improve the consistency of molten steel composition and temperature, promote the floating of inclusions, avoid the introduction of foreign inclusions, and thus improve the cleanliness of molten steel. Therefore, conducting research on tundish protection casting and flow field optimization has important engineering significance for the production of high-quality steel. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the disadvantages of the prior art and provide a bell-shaped casing for a slab continuous casting ladle and a use method thereof.

[0005] In order to solve the above technical problems, the technical solution of the present invention is as follows: A bell-shaped casing for a slab continuous casting ladle, comprising: Casing body; A long shroud, arranged at the lower end of the sleeve body; Wherein, the inner cavity diameter of the long water outlet is larger than the inner cavity diameter of the sleeve body.

[0006] As a preferred solution of the bell-shaped casing for slab continuous casting of the present invention, a connecting section is arranged between the casing body and the long water outlet, the connecting section is in the shape of a hollow truncated cone, the upper end of the connecting section is connected to the casing body, the lower end of the connecting section is connected to the long water outlet, the inner cavity diameter of the upper end of the connecting section is equal to the inner cavity diameter of the casing body, and the inner cavity diameter of the lower end of the connecting section is equal to the inner cavity diameter of the long water outlet.

[0007] As a preferred solution of the bell-shaped sleeve for slab continuous casting of the present invention, the inner diameter of the sleeve body gradually decreases from the upper end to the lower end.

[0008] As a preferred solution of the slab continuous casting bell-shaped casing of the present invention, the inner cavity diameter of the upper end of the casing body is 106 cm, the inner cavity diameter of the lower end of the casing body is 98 cm, and the inner cavity diameter of the long water nozzle is 135 cm.

[0009] As a preferred solution of the bell-shaped casing for slab continuous casting ladle described in the present invention, the length of the long water nozzle is 400 cm.

[0010] As a preferred solution of the bell-shaped casing for slab continuous casting ladle described in the present invention, the height of the connecting section is 100 cm.

[0011] The present invention also provides a method for using a bell-shaped casing for a slab continuous casting ladle, comprising: Clean the bowl and replace the gasket; After the ladle is rotated into place, align the long nozzle and the lower nozzle and fix them; Control the ladle to descend. When the distance between the slag layer immersed in the long shroud and the molten steel reaches the threshold, control the ladle to stop descending, and then gradually open the slide plate to the maximum opening; After the pouring is completed, continue to control the ladle to descend to the normal pouring position, and fine-tune the position of the ladle and the long nozzle to make them centered and fixed; Carry out pouring operations.

[0012] As a preferred solution of the method for using the bell-shaped casing of the slab continuous casting ladle of the present invention, after the ladle is controlled to descend, the method further comprises: Observe the position of the shroud and reduce the descent speed of the ladle when the shroud is close to the molten pool of the tundish.

[0013] The beneficial effects of the present invention are: (1) The present invention forms a trumpet-shaped shroud at the lower end of the casing body. The increased volume can accommodate hot air to achieve immersion casting, thereby avoiding secondary contamination of molten steel and the involvement of covering agents when changing ladles. Compared with the straight-cylinder shroud, the trumpet-shaped shroud has a lower outlet velocity, which reduces the impact on the tundish molten pool and the fluctuation of the tundish liquid level, and is conducive to alleviating slag entanglement and secondary oxidation in the impact zone.

[0014] (2) The present invention adopts an immersion pouring operation method. During the pouring process, the liquid level in the intermediate ladle is stable, and the splashing time of the molten steel in the immersion pouring is about 1 second, which alleviates the emulsification of steel slag and the inhalation of air caused by the splashing of molten steel in non-immersion pouring, and can effectively improve the protective pouring effect of the molten steel.

[0015] (3) In the present invention, the protective pouring from ladle to tundish is optimized during steady-state pouring. During steady-state pouring, the liquid surface in the tundish injection zone is calmer, and the size and frequency of tundish slag holes are reduced. The increase in TO from ladle to tundish is less than 2-3 ppm, and the [Al] loss is controlled within 0.003%. During unsteady-state pouring, the protective pouring from ladle to tundish is significantly improved. After optimization, the inclusion content introduced by the tundish slag roll is significantly reduced, and the [Al] loss of molten steel during the ladle change process is reduced by more than 10% from 0.005%. A high-frequency flaw detection test and evaluation method for large particle inclusions in unsteady-state casting blanks are established.

[0016] (4) The present invention designs a new long water nozzle and turbulent structure of the tundish, thereby increasing the piston flow ratio of the tundish, reducing the dead zone ratio, improving the mixing effect of the tundish molten pool, and reducing the temperature difference of the molten steel at each outlet of the four-stream tundish from 3-5°C before optimization to less than 3°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0018] Figure 1 A schematic cross-sectional view of a bell-shaped casing for a slab continuous casting ladle provided by the present invention; Among them: 1. Casing body; 2. Long water outlet; 3. Connection section. DETAILED DESCRIPTION

[0019] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific implementation modes and in combination with the accompanying drawings.

[0020] Figure 1 The cross-sectional schematic diagram of the bell-shaped casing for slab continuous casting provided in the embodiment of the present application. The device comprises a casing body 1 and a long shroud 2. The long shroud 2 is composed of Specifically, the long shroud 2 is fixedly arranged at the lower end of the casing body 1 through the connecting section 3. Figure 1 The connecting section 3 is in the shape of a hollow truncated cone. The upper end of the connecting section 3 is fixedly connected to the sleeve body 1, and the lower end of the connecting section 3 is fixedly connected to the long water nozzle 2. The inner cavity diameter of the upper end of the connecting section 3 is equal to the inner cavity diameter of the lower end of the sleeve body 1, and the inner cavity diameter of the lower end of the connecting section 3 is equal to the inner cavity diameter of the long water nozzle 2.

[0021] In this embodiment, the inner diameter of the sleeve body 1 gradually decreases from the upper end to the lower end. The inner diameter of the upper end of the sleeve body 1 is 106 cm, and the inner diameter of the lower end of the sleeve body 1 is 98 cm. The inner diameter of the long shroud 2 is 135 cm, and the length of the long shroud 2 is 400 cm. The height of the connecting section 3 is 100 cm.

[0022] Through the above arrangement, a trumpet-shaped shroud 2 is formed at the lower end of the casing body 1, and the increased volume can accommodate hot air to achieve immersion casting, thereby avoiding secondary contamination of molten steel and the involvement of covering agents when changing ladles. Compared with the straight-cylinder shroud 2, the trumpet-shaped shroud 2 has a lower outlet speed, which reduces the impact on the tundish molten pool and the fluctuation of the tundish liquid level, and is conducive to alleviating slag entanglement and secondary oxidation in the impact zone.

[0023] The present application also provides a method for using a bell-shaped casing for a slab continuous casting ladle, the method specifically comprising the following steps: Step S101: Clean the bowl mouth and replace the sealing gasket.

[0024] Specifically, when producing the target steel grade and replacing the ladle, clean the bowl mouth and replace the sealing gasket normally.

[0025] Step S102: After the ladle is rotated into position, the long shroud 2 is aligned with the lower shroud and fixed.

[0026] Step S103: Control the ladle to descend. When the distance between the immersed slag layer of the long shroud 2 and the molten steel reaches a threshold, control the ladle to stop descending, and then gradually open the slide plate to the maximum opening.

[0027] Specifically, in the process of controlling the descent of the ladle, it is necessary to observe the position of the shroud 2. When the shroud 2 is close to the tundish molten pool, the descent speed of the ladle is reduced to control its position. Then the ladle is slowly lowered. When the distance between the slag layer immersed in the shroud 2 and the molten steel is about 10 cm (assessed by visual inspection, without the need to remove the slag), the ladle stops descending, and then the slide is gradually opened to the maximum opening.

[0028] It should be noted that the slide plate is gradually opened by continuous inching.

[0029] Step S104: After the pouring is completed, the ladle is continued to be controlled to descend to the normal pouring position, and the positions of the ladle and the long shroud 2 are fine-tuned to make them centered and fixed.

[0030] Step S105: performing pouring operation.

[0031] Therefore, the technical solution of the present application uses a large ladle bell-shaped casing and adopts an immersion pouring operation method. The liquid level of the intermediate ladle is stable during the pouring process, and the splashing time of the molten steel in the immersion pouring is about 1s, which alleviates the emulsification of steel slag and the inhalation of air caused by the splashing of molten steel during non-immersion pouring, and can effectively improve the protective pouring effect of molten steel. Secondly, during the steady-state pouring process, the protective pouring from the ladle to the tundish is optimized. During steady-state pouring, the liquid level in the injection flow area of ​​the tundish is calmer, and the size and frequency of the slag eyes in the tundish are reduced. The increase in TO from the ladle to the tundish is less than 2-3 ppm, and the [Al] loss is controlled within 0.003%. During the non-steady-state pouring process, the protective pouring from the ladle to the tundish is significantly improved. After optimization, the content of inclusions introduced by the slag roll in the tundish is significantly reduced. The [Al] loss of molten steel during the ladle change process is reduced by more than 10% from 0.005%, and a high-frequency flaw detection test and evaluation method for large particle inclusions in non-steady-state casting blanks are established. In addition, the overall mixing effect of the tundish is improved. By designing a new long shroud 2 and tundish turbulent structure, the piston flow ratio of the tundish is increased, the dead zone ratio is reduced, the mixing effect of the tundish molten pool is improved, and the temperature difference of the molten steel at each outlet of the four-stream tundish is reduced from 3-5℃ before optimization to less than 3℃.

[0032] In addition to the above embodiments, the present invention may also have other implementation modes; any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A bell-shaped casing for slab continuous casting, characterized in that: include: Casing body (1); A long shroud (2) is arranged at the lower end of the sleeve body (1); Wherein, the inner diameter of the long water outlet (2) is larger than the inner diameter of the sleeve body (1).

2. The bell-shaped casing for slab continuous casting ladle according to claim 1, characterized in that: A connecting section (3) is provided between the sleeve body (1) and the long water outlet (2); the connecting section (3) is in the shape of a hollow truncated cone; the upper end of the connecting section (3) is butted against the sleeve body (1); the lower end of the connecting section (3) is connected to the long water outlet (2); the inner cavity diameter of the upper end of the connecting section (3) is equal to the inner cavity diameter of the sleeve body (1); and the inner cavity diameter of the lower end of the connecting section (3) is equal to the inner cavity diameter of the long water outlet (2).

3. The bell-shaped casing for slab continuous casting ladle according to claim 1, characterized in that: The inner cavity diameter of the sleeve body (1) gradually decreases from the upper end to the lower end.

4. The bell-shaped casing for slab continuous casting ladle according to claim 3, characterized in that: The inner diameter of the upper end of the sleeve body (1) is 106 cm, the inner diameter of the lower end of the sleeve body (1) is 98 cm, and the inner diameter of the long water outlet (2) is 135 cm.

5. The bell-shaped casing for slab continuous casting ladle according to claim 1, characterized in that: The length of the long shroud (2) is 400 cm.

6. The bell-shaped casing for slab continuous casting ladle according to claim 2, characterized in that: The height of the connecting section (3) is 100 cm.

7. A method for using the bell-shaped casing for slab continuous casting ladle according to any one of claims 1 to 6, characterized in that: include: Clean the bowl and replace the gasket; After the ladle is rotated into position, the long shroud (2) is aligned with the lower shroud and fixed; Control the ladle to descend, and when the distance between the immersed slag layer of the long shroud (2) and the molten steel reaches a threshold value, control the ladle to stop descending, and then gradually open the slide plate to the maximum opening; After the pouring is completed, the ladle is controlled to descend to the normal pouring position, and the positions of the ladle and the long shroud (2) are fine-tuned to align and fix them; Carry out pouring operations.

8. The bell-shaped casing for slab continuous casting ladle according to claim 7, characterized in that: After controlling the ladle to descend, the method further comprises: Observe the position of the shroud (2), and when the shroud (2) is close to the tundish molten pool, reduce the descending speed of the ladle.

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