Device and method for adjusting liquid level of molten steel in continuous casting tundish

Abstract

The invention relates to a continuous casting tundish molten steel liquid level adjusting device and method. The continuous casting tundish molten steel liquid level adjusting device comprises a lifting device, a lifting rod and an immersion block. The immersion block is connected with a lifting device through a lifting rod, a gas injection channel is arranged in the middle of the lifting rod and the immersion block in the height direction, and the upper end of the gas injection channel is connected with an injection device. When the liquid level of molten steel in the tundish is adjusted, the immersion block is partially or completely immersed in the molten steel in the tundish under the driving of the lifting device. The molten steel liquid level adjusting device is simple in structure and convenient to use, it can be guaranteed that the molten steel liquid level of a tundish has the constant height under the condition that large-tank molten steel is not supplemented in time, and smooth casting and stable casting blank quality are guaranteed by combining pulling speed adjustment.

Description

Technical Field

[0001] This invention relates to the field of continuous casting technology, and in particular to a device and method for adjusting the level of molten steel in a continuous casting tundish. Background Technology

[0002] The tundish is a vessel used in continuous casting to hold molten steel and divert it for continuous casting. It is the last vessel in the continuous casting system to come into contact with refractory materials before the steel is finished. It is a crucial part of the continuous casting process and significantly impacts steel quality. With advancements in smelting technology, especially the development of secondary refining technology for ladles, the tundish has taken on many important functions, such as providing stable static pressure in the molten steel, maintaining stable flow rate and stream to reduce turbulence, removing non-metallic inclusions to purify the molten steel, and maintaining a relatively constant temperature. It has gradually become a refining vessel before the steel is finished.

[0003] Currently, most researchers focus their studies on tundish metallurgy (improving purity, removing inclusions, and improving flow field). However, in actual production, due to the slow production pace, the molten steel in the large ladle cannot be replenished in time, causing the tundish steel level to drop continuously. This can easily lead to interrupted casting and unstable billet quality. Therefore, it is essential to study methods to ensure a stable tundish steel level.

[0004] Currently, most methods for controlling the liquid level in continuous casting tundishes employ automated control systems. Examples include Chinese patent applications CN119159049A ("An Automatic Control Method for Liquid Level in Continuous Casting Tundishes"), CN107790665A ("An Automatic Control Method and System for Liquid Level in Tundishes"), CN101508019A ("A Method and Device for Controlling Molten Steel Level in Tundishes"), and CN102009150A ("A Method and Device for Controlling Liquid Level in Casting Tundishes"). These control systems are complex in structure and have high investment and operating costs.

[0005] Chinese patent application CN109158567A discloses a "constant liquid level control method for continuous casting tundish casting process." The tundish is T-shaped and has two or more tundish inlets (ladle pouring positions). Multiple ladles can be cast simultaneously. Utilizing the principle that the flow rates of the multiple inlets and outlets of the tundish are the same, the liquid level in the tundish is kept constant during continuous casting. This avoids the problems of slag entrapment and unstable tundish metallurgical effects caused by the need to supply molten steel stored in the tundish during ladle changes in single-ladle continuous casting, as well as the problems of interrupted molten steel casting and casting stoppage during single-ladle continuous casting. While this technical solution can ensure continuous casting, it occupies a large space and is complex to operate. Summary of the Invention

[0006] This invention provides a molten steel level regulating device and method for continuous casting tundish. The molten steel level regulating device has a simple structure and is easy to use. It can ensure that the molten steel level in the tundish remains constant when the molten steel in the ladle is not replenished in time. Combined with the casting speed adjustment, it can ensure smooth casting and stable billet quality.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] A continuous casting tundish molten steel level adjustment device includes a lifting device, a lifting rod, and an immersion block; the immersion block is connected to the lifting device via the lifting rod, and a gas injection channel is provided along the height of the middle of the lifting rod and the immersion block, with the upper end of the gas injection channel connected to a blowing device; when adjusting the molten steel level in the tundish, the immersion block is partially or completely immersed in the molten steel in the tundish under the action of the lifting device.

[0009] The lifting device is a movable lifting device or a lifting device with a rotating arm.

[0010] The immersion block has a frustum structure, and the taper of the frustum is consistent with the taper of the intermediate package wall.

[0011] A method for adjusting the molten steel level in a continuous casting tundish includes the following steps:

[0012] 1) Determine the molten steel level in the tundish;

[0013] The steady-state molten steel level in the tundish is set as H2, the lower limit of the molten steel level in the tundish is H1, and the actual molten steel level in the tundish is H. When the molten steel level in the tundish is between H2 and H1, the volume of molten steel in the tundish is Vt; the volume of the immersion block is Vk, and Vk≥Vt. During continuous casting, when H2>H≥H1 is measured, the molten steel level adjustment device in the continuous casting tundish is prepared to be activated.

[0014] 2) Adjustment of molten steel level in the tundish;

[0015] When the difference between the actual molten steel level in the tundish and the lower limit of the molten steel level in the tundish, H-H1, is ≤ 200mm, the lifting device is activated, and the immersion block is moved down by the lifting rod; when the bottom of the immersion block is submerged below the molten steel surface, the blowing device is activated, and inert gas is injected into the molten steel through the gas injection channel; the blowing flow rate is 5-10L / min; the immersion depth of the immersion block is adjusted to keep H2≥H>H1;

[0016] 3) Adjustment of casting machine speed;

[0017] When the immersion block is immersed in the molten steel in the tundish, and the actual molten steel level H in the tundish is maintained between H2 and H1, the casting speed is not adjusted; when the actual molten steel level H in the tundish is less than H1, the casting speed is reduced by 0.1 to 0.2 m / min, and the immersion block is lowered continuously until the actual molten steel level H in the tundish is greater than or equal to H1.

[0018] 4) Discontinue the molten steel level adjustment device in the tundish;

[0019] When molten steel is added to the tundish, the tundish molten steel level adjustment device is deactivated; the immersion block is slowly raised using the lifting device to ensure that the actual molten steel level in the tundish is always maintained at a stable height until the immersion block is completely withdrawn from the molten steel, and the blowing of gas and powder is stopped at the same time; the tundish molten steel level adjustment device returns to its initial position.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1) It can extend the tundish steel pouring time and ensure smooth production;

[0022] 2) It helps stabilize the molten steel level in the tundish and reduce abnormal fluctuations in molten steel in the tundish; at the same time, it reduces slag entrapment in the tundish and improves the purity of the billet.

[0023] 3) Compared with existing automated control systems and multiple ladles supplying molten steel to the tundish, the continuous casting tundish molten steel level regulating device of the present invention has a simple structure, is easy to use, occupies little space, and has low investment cost, making it more suitable for widespread application. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the operating principle of a continuous casting tundish molten steel level regulating device as described in this invention.

[0025] In the diagram: 1. Lifting rod 2. Gas injection channel 3. Immersion block 4. Tundish slag 5. Molten steel level after immersion of the immersion block 5'. Molten steel level before immersion of the immersion block 6. Molten steel 7. Tundish wall 8. Argon gas 9. Turbulence generator Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0027] like Figure 1 As shown, the continuous casting tundish molten steel level adjustment device of the present invention includes a lifting device (not shown in the figure), a lifting rod 1, and an immersion block 3; the immersion block 3 is connected to the lifting device through the lifting rod 2, and a gas injection channel 2 is provided along the height of the middle of the lifting rod 2 and the immersion block 3, and the upper end of the gas injection channel 2 is connected to a blowing device; when adjusting the molten steel level in the tundish, the immersion block 3 is partially or completely immersed in the molten steel 6 in the tundish under the action of the lifting device.

[0028] The molten steel level regulating device for continuous casting tundish described in this invention can be installed in various chambers of the tundish as needed, preferably in the chamber with a turbulence generator 9.

[0029] The lifting device described in this invention is a movable lifting device or a lifting device with a rotating arm. When there is a large amount of molten steel in the tundish and there is no need to engage the molten steel level adjustment device in the continuous casting tundish, the molten steel level adjustment device in the continuous casting tundish is in its initial position. When the actual molten steel level H in the tundish is about to approach the lower limit H1 of the molten steel level in the tundish, the immersion block 3 is moved above the tundish using the lifting device.

[0030] The immersion block 3 of this invention has a frustum structure, and the taper of the frustum is consistent with the taper of the tundish wall 7. This not only facilitates smooth passage through the tundish slag 4 into the molten steel 6, but also helps the molten steel 6 in the tundish to rise steadily. Let the volume of the molten steel in the tundish be Vt, then the volume of the immersion block 3, Vk ≥ Vt; Figure 1 In the process, after the immersion block 3 is completely immersed in the molten steel 6 in the tundish, the molten steel level in the tundish rises from the molten steel level 5 before the immersion block is immersed to the molten steel level 5' after the immersion block is immersed, and the molten steel level height increases from the lower limit H1 of the molten steel level in the tundish to the steady-state casting molten steel level H2 in the tundish.

[0031] When molten steel from the ladle cannot be replenished to the tundish in time, and the molten steel level in the tundish drops to around H1, slag entrapment can easily occur, causing defects in the cast billet quality. If the level drops below H1, there is a risk of interrupted casting. At this time, by inserting the immersion block 3 (one or more can be set as needed) into the molten steel 6 in the tundish, the molten steel level in the tundish can be raised to the steady-state casting molten steel level H2 in the tundish, thereby ensuring the smooth operation of continuous casting and the stability of the cast billet quality.

[0032] After the immersion block 3 enters the molten steel, an inert gas (such as argon 8) is injected into the molten steel through a spraying device to promote the floating of inclusions and slag in the molten steel.

[0033] The present invention provides a method for adjusting the molten steel level in a continuous casting tundish, comprising the following steps:

[0034] 1) Determine the molten steel level in the tundish;

[0035] The steady-state molten steel level in the tundish is set as H2, the lower limit of the molten steel level in the tundish is H1, and the actual molten steel level in the tundish is H. When the molten steel level in the tundish is between H2 and H1, the volume of molten steel in the tundish is Vt; the volume of the immersion block is Vk, and Vk≥Vt. During continuous casting, when H2>H≥H1 is measured, the molten steel level adjustment device in the continuous casting tundish is prepared to be activated.

[0036] 2) Adjustment of molten steel level in the tundish;

[0037] When the difference between the actual molten steel level in the tundish and the lower limit of the molten steel level in the tundish, H-H1, is ≤ 200mm, the lifting device is activated, and the immersion block is moved down by the lifting rod; when the bottom of the immersion block is submerged below the molten steel surface, the blowing device is activated, and inert gas is injected into the molten steel through the gas injection channel; the blowing flow rate is 5-10L / min; the immersion depth of the immersion block is adjusted to keep H2≥H>H1;

[0038] 3) Adjustment of casting machine speed;

[0039] When the immersion block is immersed in the molten steel in the tundish, and the actual molten steel level H in the tundish is maintained between H2 and H1, the casting speed is not adjusted; when the actual molten steel level H in the tundish is less than H1, the casting speed is reduced by 0.1 to 0.2 m / min, and the immersion block is lowered continuously until the actual molten steel level H in the tundish is greater than or equal to H1.

[0040] 4) Discontinue the molten steel level adjustment device in the tundish;

[0041] When molten steel is added to the tundish, the tundish molten steel level adjustment device is deactivated; the immersion block is slowly raised using the lifting device to ensure that the actual molten steel level in the tundish is always maintained at a stable height until the immersion block is completely withdrawn from the molten steel, and the blowing of gas and powder is stopped at the same time; the tundish molten steel level adjustment device returns to its initial position.

[0042] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0043]

Example

[0044] A steel plant uses the molten steel level regulating device for the tundish described in this invention to regulate the molten steel level in continuous casting production. The specific process is as follows:

[0045] 1. Determine the molten steel level in the tundish;

[0046] The tundish has a volume of 60 tons. The steady-state molten steel level in the tundish is H2 = 1300 mm, and the lower limit of the molten steel level in the tundish is H1 = 600 mm. If H1 is lower than 600 mm, the casting speed needs to be reduced, the tail end of the billet needs to be sealed, and the casting process needs to be stopped.

[0047] The molten steel level in the tundish rises from H1 to H2, requiring a replenishment volume of Vt = 20m³. 3 Therefore, in this embodiment, Vk = 30m is selected. 3The immersion block. When H2 > H ≥ H1 is measured, prepare to activate the molten steel level adjustment device in the continuous casting tundish;

[0048] 2. Adjustment of molten steel level in the tundish;

[0049] In this embodiment, after the third ladle of molten steel is poured in the second casting, due to the production rhythm, the fourth ladle of molten steel cannot be replenished to the tundish in time, and the molten steel level in the tundish drops from 1300mm to 800mm; at this time, the molten steel level adjustment device in the tundish is activated, and the lifting device moves the immersion block down while the blowing device is turned on, with the blowing argon flow rate being 6L / min, and the immersion block is immersed in the molten steel until the molten steel level in the tundish rises to 1300mm;

[0050] 3. Adjustment of casting machine speed;

[0051] In this embodiment, after 10 minutes of constant casting speed, the fourth ladle of molten steel still failed to arrive, while the molten steel level in the tundish had dropped to 700 mm. At this point, the casting speed was reduced by 0.1 m / min, and the immersion block was further lowered into the molten steel, causing the molten steel level to rise to 1200 mm. After 5 minutes of steady-state casting, the fourth ladle of molten steel arrived and casting began, replenishing the molten steel in the tundish.

[0052] 4. Discontinue the intermediate steel liquid level adjustment device;

[0053] In this embodiment, when the molten steel level in the tundish rises to 1300mm after the molten steel is replenished, the immersion block is gradually moved upward. During the upward movement, the molten steel level in the tundish is kept at around 1300mm until the immersion block is completely removed from the molten steel, at which point the argon gas is shut off; the molten steel level adjustment device in the tundish returns to its initial position.

[0054] This embodiment statistically analyzes actual production data from 100 castings. The comparison is 50 castings without the method described in this invention, and 50 castings using the method described in this invention. The specific comparison is shown in the table below:

[0055] Table 1 Comparison of the effects of molten steel level regulation in continuous casting tundish

[0056] project Average number of intermediate tundishes Unsteady casting time slab defect rate Comparative Example 10 times 100min 3.78％ Example 12 times 60min 1.56％

[0057] As can be seen from the statistical results in Table 1, after adopting the continuous casting tundish molten steel level adjustment method described in this invention, the average life of the tundish has been extended, the unsteady casting time has been significantly reduced, and the slab defect rate has been significantly decreased, providing a guarantee for smooth production, cost reduction and efficiency improvement for enterprises.

[0058] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A device for regulating the level of molten steel in a continuous casting tundish, characterized in that, It includes a lifting device, a lifting rod, and an immersion block; the immersion block is connected to the lifting device through the lifting rod, and a gas injection channel is set along the height of the middle of the lifting rod and the immersion block, and the upper end of the gas injection channel is connected to a blowing device; when adjusting the molten steel level in the tundish, the immersion block is partially or completely immersed in the molten steel in the tundish under the action of the lifting device.

2. The continuous casting tundish molten steel level regulating device according to claim 1, characterized in that, The lifting device is a movable lifting device or a lifting device with a rotating arm.

3. The continuous casting tundish molten steel level regulating device according to claim 1, characterized in that, The immersion block has a frustum structure, and the taper of the frustum is consistent with the taper of the intermediate package wall.

4. A method for adjusting the molten steel level in a continuous casting tundish, based on the molten steel level adjusting device for a continuous casting tundish as described in claim 1, 2, or 3; characterized in that, The process includes the following: 1) Determine the molten steel level in the tundish; The steady-state molten steel level in the tundish is set as H2, the lower limit of the molten steel level in the tundish is H1, and the actual molten steel level in the tundish is H. When the molten steel level in the tundish is between H2 and H1, the volume of molten steel in the tundish is Vt; the volume of the immersion block is Vk, and Vk≥Vt. During continuous casting, when H2>H≥H1 is measured, the molten steel level adjustment device in the continuous casting tundish is prepared to be activated. 2) Adjustment of molten steel level in the tundish; When the difference between the actual molten steel level in the tundish and the lower limit of the molten steel level in the tundish, H-H1, is ≤ 200mm, the lifting device is activated, and the immersion block is moved down by the lifting rod; when the bottom of the immersion block is submerged below the molten steel surface, the blowing device is activated, and inert gas is injected into the molten steel through the gas injection channel; the blowing flow rate is 5-10L / min; the immersion depth of the immersion block is adjusted to keep H2≥H>H1; 3) Adjustment of casting machine speed; When the immersion block is immersed in the molten steel in the tundish, and the actual molten steel level H in the tundish is maintained between H2 and H1, the casting speed is not adjusted; when the actual molten steel level H in the tundish is less than H1, the casting speed is reduced by 0.1 to 0.2 m / min, and the immersion block is lowered continuously until the actual molten steel level H in the tundish is greater than or equal to H1. 4) Discontinue the molten steel level adjustment device in the tundish; When molten steel is added to the tundish, the tundish molten steel level adjustment device is deactivated; the immersion block is slowly raised using the lifting device to ensure that the actual molten steel level in the tundish is always maintained at a stable height until the immersion block is completely withdrawn from the molten steel, and the blowing of gas and powder is stopped at the same time; the tundish molten steel level adjustment device returns to its initial position.

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