Method for controlling on-line rapid cooling of continuous casting slab

Abstract

The present application belongs to the technical field of steelmaking, and relates to an online fast cooling production control method for continuous casting slabs. By accurately designing the water quantity, i.e. the cooling intensity, of different cooling section regions, the method matches different steel grades, section sizes and pulling speeds, and realizes precise control of the surface temperature of the cast slab. In the preparation stage, measures such as nozzle inspection, water quantity testing and closing of part of the nozzles are taken to ensure the stable operation of the cooling system. In the fast cooling implementation process, the opening and closing timing of the fast cooling system is dynamically adjusted according to the production situation, and the actual water quantity situation is monitored. At the same time, a perfect emergency disposal scheme is designed for abnormal production situations, such as stopping the fast cooling test when the water quantity is insufficient and adjusting the water quantity when the cast slab is deformed. The implementation of the method significantly reduces the quality risk, improves the continuous casting production efficiency, and ensures the continuity and stability of the production, thereby providing strong support for energy saving and consumption reduction and efficient production of the steel metallurgy industry.

Description

Technical Field

[0001] This invention belongs to the field of steelmaking technology and relates to a method for controlling the online rapid cooling production of continuously cast slabs. Background Technology

[0002] In the continuous casting process of the iron and steel metallurgical industry, hot charging and hot delivery technology for continuously cast billets is an important energy-saving and consumption-reducing measure, which is of great significance for improving steel production efficiency and reducing energy consumption. However, the implementation of this technology is not without challenges, especially in ensuring product quality. How to effectively avoid the generation of hot delivery cracks during the hot delivery process has become a key problem in the hot charging and hot delivery technology for continuously cast billets.

[0003] Studies have shown that temperature control of the surface layer of the billet is crucial for suppressing the formation of hot-dip ferrite cracks. Specifically, the temperature within the 8-10 mm range of the billet surface layer needs to be strictly controlled below 660℃ to achieve sufficient ferritization, thereby effectively suppressing crack formation. To achieve this temperature control target, the industry has continuously researched and innovated, developing various rapid cooling technologies for the surface of continuously cast billets.

[0004] Taking Chinese patent CN109593933A as an example, this patent proposes a method for rapid cooling of the billet surface by retaining water spray in a rapid cooling box. This technology, through precise control of the timing and volume of water spray, can effectively reduce the temperature of the billet surface in a short time, thereby inhibiting crack formation. In addition, there is a segmented rapid cooling device that combines spraying and steam removal functions, which not only improves the cooling uniformity of moving slabs but also further enhances cooling efficiency.

[0005] However, although existing technologies have solved the problem of rapid surface cooling of continuously cast billets to some extent, some key limitations and challenges remain. Among them, the lack of dynamic control is a prominent issue. In traditional rapid cooling schemes, the matching between casting speed and cooling intensity often lacks dynamism, especially under high casting speed conditions, making it difficult to find a balance between surface cooling efficiency and the internal temperature gradient of the billet. This imbalance can easily lead to uneven cooling or excessive thermal stress, thereby affecting the quality of the billet and production efficiency.

[0006] Besides the lack of dynamic control, the inadequacy of emergency response mechanisms is also a significant problem in existing technologies. During production, various abnormal situations are inevitable, such as fluctuations in casting speed, insufficient water supply, or billet deformation. However, existing technologies often lack systematic handling methods, failing to address these abnormal situations promptly and effectively. For example, when the casting speed is below 0.7 m / min, continuous operation may exacerbate the risk of overcooling, but existing technologies do not clearly specify corresponding operating thresholds and countermeasures. Furthermore, some rapid cooling devices cannot adjust the water supply online to address billet warping, arching, and other deformation problems, which also poses considerable hidden dangers to production.

[0007] These limitations and challenges make it difficult to strike a balance between efficient production and quality control in continuous casting. On the one hand, pursuing efficient production often means increasing casting speed and cooling efficiency, but this may sacrifice the quality of the cast billet; on the other hand, overemphasizing quality control may lead to a decrease in production efficiency and an increase in costs. Therefore, there is an urgent need to develop an online rapid cooling control method that is compatible with high casting speeds and has dynamic regulation and emergency response capabilities.

[0008] This new online rapid cooling control method should be able to monitor key parameters such as casting speed and water volume in real time, and dynamically adjust the cooling intensity and method based on changes in these parameters. Simultaneously, it should possess a robust emergency response mechanism to react quickly to abnormal situations, ensuring production continuity and precise control over the surface quality of the cast billets. Through such technological innovation and optimization, it is expected to further improve the production efficiency and product quality of continuous casting processes, injecting new vitality into the sustainable development of the iron and steel metallurgical industry. Summary of the Invention

[0009] In view of this, the purpose of this invention is to provide an online rapid cooling production control method for continuous casting slabs, so as to ensure product quality, improve continuous casting production efficiency, and ensure stable and smooth production.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a method for controlling the online rapid cooling production of continuously cast slabs, comprising the following steps:

[0011] S1, Cooling Intensity Setting: Based on steel grade, slab cross-section, and casting speed parameters, the corresponding inner and outer arc cooling water volumes are matched, where:

[0012] a. When the pulling speed is 0.1~0.3 m / min, the water flow rate of the inner arc is 150 L / min and the water flow rate of the outer arc is 700 L / min;

[0013] b. When the pulling speed is 0.4 to 0.6 m / min, the water flow rate of the inner arc is 300 to 640 L / min, and the water flow rate of the outer arc is 1050 to 1975 L / min;

[0014] c. When the pulling speed is 0.7 to 1.1 m / min, the water volume of the inner arc is 765 to 1170 L / min, and the water volume of the outer arc is 2335 to 3420 L / min;

[0015] S2, rapid cooling preparation stage:

[0016] S21, check the nozzle blockage of each cooling section and test the actual water output through the fast cooling interface to ensure it is consistent with the preset value;

[0017] S22, close the manual valves of the first to third rows of nozzles on the inner and outer arcs of SEG15 section;

[0018] S23, using an infrared thermometer to monitor the temperature of the wide center line, 1 / 4 point, corner and narrow face of the fast cooling inlet and outlet;

[0019] S3, rapid cooling control:

[0020] S31, call the rapid cooling water meter and start the rapid cooling system. After the first and last billets have exited 15 sections of the frame, perform the rapid cooling operation.

[0021] S32, when the pulling speed is <0.7 m / min and the duration is >5 min, the rapid cooling system is turned off;

[0022] S33, rapid cooling is turned on when the first furnace is poured to 32 m, and rapid cooling is turned off when the next furnace is poured to 36 m;

[0023] S4, Emergency Response:

[0024] S41, if the water volume in the second cooling section of zones one to four is lower than the preset minimum threshold, then the rapid cooling will be terminated;

[0025] S42. When the billet warps at the head and tail or arches in the middle, adjust the water flow of the outer arc by 9% to 17% or the water flow of the inner arc by 9% to 17% as needed, and adjust alternately until it is restored.

[0026] Optionally, the fast-cooling water meter is dynamically invoked through the casting machine's L1-level computer system, and the operation steps include:

[0027] a. Execute the following steps in sequence: “Instruments” → “Quick Cooling Water Meter” → “Water Meter Recall”;

[0028] b. When turning on rapid cooling, click "Secondary Cooling Water PID Adjustment" → "Rapid Cooling On"; when turning off, execute "Secondary Cooling Water PID Adjustment" → "Rapid Cooling Off".

[0029] Optionally, the head and tail billets are kept in rapid cooling mode before exiting the 15th stand, and rapid cooling is not performed on the head and tail billets during the first furnace pouring and ladle changing.

[0030] Optionally, when the head and tail of the billet warp and deform, the water volume of the outer arc should be reduced by 9% to 17%, or the spray frame that has been closed in the inner arc should be restored.

[0031] Optionally, when the middle of the billet arches, the inner arc water volume should be reduced by 9% to 17% first. If this is ineffective, the outer arc water volume should be gradually increased by 10% to 17% until the deformation is improved.

[0032] The beneficial effects of this invention are as follows: By precisely controlling the cooling process, being compatible with high-speed production, and possessing a comprehensive emergency response mechanism, this invention significantly reduces quality risks, improves production efficiency, and promotes stable and smooth production. The implementation of this method is of great significance to the sustainable development of the iron and steel metallurgy industry.

[0033] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] The present invention provides a method for controlling the online rapid cooling production of continuously cast slabs, comprising the following steps:

[0036] I. Preparation Stage

[0037] Inspection and Testing:

[0038] Before pouring, carefully check whether the nozzles of each section of the frame are blocked to ensure that the cooling water can be sprayed out smoothly.

[0039] The rapid cooling interface was used to test the actual water delivery volume of each meter at different pull speeds to ensure that the actual water delivery volume matched the preset value.

[0040] Close some nozzles:

[0041] Before rapid cooling begins, close the machine-side manual valves of the first, second, and third rows of nozzles on the inner and outer arcs of the SEG15 section to reduce unnecessary cooling water volume and avoid overcooling of the billet.

[0042] Prepare temperature measuring tools:

[0043] Prepare an infrared thermometer to measure the temperature of the center line, quarter-width, corners, and narrow face of the fast cooling inlet and outlet, so as to monitor the cooling effect of the billet in real time.

[0044] II. Rapid Cooling Implementation Process

[0045] Call the fast-cooling water meter:

[0046] On the L1 level computer of the casting machine, operate in sequence "Instrument" - "Quick Cooling Water Meter" - "Water Meter Call" to call the preset quick cooling water meter parameters.

[0047] Turn on fast cooling:

[0048] The first and last billets are not subjected to rapid cooling during startup and ladle changes. After the first billet exits the 15th stand, turn on the rapid cooling water meter. On the L1 level computer of the casting machine, operate "Second Cooling Water PID Adjustment" - "Rapid Cooling On", and check whether the rapid cooling water meter is working properly and the actual water volume of the 15th stand on the main screen.

[0049] Pulling speed and rapid cooling control:

[0050] When the pulling speed is below 0.7 m / min and the duration exceeds 5 minutes, turn off the rapid cooling water meter to avoid overcooling.

[0051] When the first heat of rapid cooling is poured to 32m, the rapid cooling water meter is turned on; when the last steel billet comes out of the 15th stand (the next heat is poured to 36m), the rapid cooling water meter is turned off.

[0052] End of rapid cooling:

[0053] When the rapid cooling ends, operate "Secondary Cooling Water PID Adjustment" - "Rapid Cooling Off" sequentially on the L1 level computer of the casting machine to shut down the rapid cooling system.

[0054] III. Emergency Response

[0055] Handling abnormal water volume:

[0056] During production, closely monitor the water flow in zones one through four. If the minimum water flow is lower than the preset requirements (zone one inner and outer arcs 260 L / min, left and right sides 100 L / min, zone two 135 L / min, zone three 180 L / min, zone four 210 L / min), immediately stop the rapid cooling test to avoid adverse effects on the billet.

[0057] Treatment of billet deformation:

[0058] If obvious warping or deformation of the billet is found at the head and tail, reduce the water volume of the outer arc by 9% to 17%, or observe the deformation and gradually restore the inner arc spray frame after it has been closed to adjust the cooling intensity.

[0059] If a noticeable arched deformation is found in the middle of the billet, reduce the inner arc water volume by 9% to 17%. Observe the lower support billet; if the arching does not improve, increase the outer arc water volume by 10% to 17%. Alternate adjustments and test sequentially to find the optimal cooling method.

[0060] Through the above specific implementation methods, the online rapid cooling production control method for continuous casting slabs can achieve precise control over the surface temperature of the slab, ensuring product quality; it is also compatible with high-speed casting production, improving production efficiency; and it has a complete emergency mechanism to ensure the continuity and stability of production.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling the online rapid cooling production of continuously cast slabs, characterized in that, Includes the following steps: S1, Cooling intensity setting: Based on the steel grade, slab cross-section and drawing speed parameters, match the corresponding inner and outer arc cooling water volume; S2, rapid cooling preparation stage: S21, check the nozzle blockage of each cooling section and test the actual water output through the fast cooling interface to ensure it is consistent with the preset value; S22, close the manual valves of the first to third rows of nozzles on the inner and outer arcs of SEG15 section; S23, using an infrared thermometer to monitor the temperature of the wide center line, 1 / 4 point, corner and narrow face of the fast cooling inlet and outlet; S3, rapid cooling control: S31, call the rapid cooling water meter and start the rapid cooling system. After the first and last billets have exited 15 sections of the frame, perform the rapid cooling operation. S32, when the pulling speed is <0.7 m / min and the duration is >5 min, the rapid cooling system is turned off; S33, rapid cooling is turned on when the first furnace is poured to 32 m, and rapid cooling is turned off when the next furnace is poured to 36 m; S4, Emergency Response: S41, if the water volume in the second cooling section of zones one to four is lower than the preset minimum threshold, then the rapid cooling will be terminated; S42. When the billet warps at the head and tail or arches in the middle, adjust the outer arc water volume by 9% to 17% or the inner arc water volume by 9% to 17% as needed, and alternate adjustments until it is restored.

2. The method for controlling online rapid cooling production of continuously cast slabs according to claim 1, characterized in that: The rapid cooling water meter is dynamically invoked through the casting machine's L1-level computer system. The operation steps include: a. Execute the following steps in sequence: "Instruments" → "Quick Cooling Water Meter" → "Water Meter Recall"; b. When turning on rapid cooling, click "Secondary Cooling Water PID Adjustment" → "Rapid Cooling On"; when turning off, execute "Secondary Cooling Water PID Adjustment" → "Rapid Cooling Off".

3. The method for controlling online rapid cooling production of continuously cast slabs according to claim 1, characterized in that: The head and tail billets are kept in rapid cooling mode before exiting the 15th section of the machine frame, and no rapid cooling treatment is performed on the head and tail billets during the first furnace pouring and ladle changing.

4. The method for controlling online rapid cooling production of continuously cast slabs according to claim 1, characterized in that: When the head and tail of the billet warp and deform, prioritize reducing the water volume of the outer arc by 9% to 17%, or restore the spray frame that has been closed on the inner arc.

5. The method for controlling online rapid cooling production of continuously cast slabs according to claim 1, characterized in that: When the middle of the billet arches, prioritize reducing the water volume of the inner arc by 9% to 17%. If this is ineffective, gradually increase the water volume of the outer arc by 10% to 17% until the deformation is improved.