Continuous casting sheet billet on-line rapid cooling production control method

Abstract

The invention belongs to the technical field of steelmaking, and relates to an on-line rapid cooling production control method for a continuous casting slab, which is characterized in that the water quantity, namely cooling strength, of different cooling section areas is precisely designed to match different steel types, section sizes and pulling speeds, so that the surface temperature of the casting slab is precisely controlled. In the preparation stage, stable operation of the cooling system is ensured through measures such as nozzle inspection, water quantity test and closing of part of nozzles. And in the rapid cooling implementation process, the opening and closing time of the rapid cooling system is dynamically adjusted according to the production condition, and the actual water volume condition is monitored. Meanwhile, aiming at abnormal production conditions, a perfect emergency disposal scheme is designed, such as rapid cooling test stopping when the water quantity is insufficient and water quantity adjustment when the casting blank deforms. According to the implementation of the method, the quality risk is remarkably reduced, the continuous casting production efficiency is improved, the production continuity and stability are ensured, and powerful support is provided for energy conservation, consumption reduction and efficient production in the ferrous metallurgy industry.

Description

Technical Field

[0001] The invention belongs to the technical field of steelmaking and relates to an online rapid cooling production control method for continuous casting slabs. Background Art

[0002] In the continuous casting process of the steel metallurgical industry, the hot charging and hot delivery technology of continuous casting 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 terms of ensuring product quality. How to effectively avoid the occurrence of hot delivery cracks during the hot delivery process has become a key problem in the hot charging and hot delivery technology of continuous casting billets.

[0003] Research shows that temperature control of the surface layer of the ingot is the key to suppressing the generation of hot-sending cracks. Specifically, the temperature of the surface layer of the ingot within the range of 8 to 10 mm must be strictly controlled below 660°C to achieve sufficient ferritization, thereby effectively suppressing the generation of cracks. In order to achieve this temperature control goal, the industry has continuously developed and innovated, and developed a variety of continuous casting ingot surface rapid cooling technologies.

[0004] Taking Chinese patent CN109593933A as an example, the patent proposes a method of spraying water through a rapid cooling box to achieve rapid cooling of the surface of the ingot. This technology can effectively reduce the temperature of the surface of the ingot in a short time by accurately controlling the timing and amount of water spraying, thereby achieving the purpose of suppressing the generation of cracks. In addition, there is also a segmented rapid cooling device, which combines the spraying and steam removal functions, which not only improves the cooling uniformity of the moving slab, but also further improves the cooling efficiency.

[0005] However, although the existing technology has solved the problem of rapid cooling of the continuous casting surface to a certain extent, there are still some key limitations and challenges. Among them, the lack of dynamic control is a prominent problem. In the traditional rapid cooling scheme, the matching of the drawing speed and the cooling intensity often lacks dynamics, especially under high drawing speed conditions, it is difficult to find a balance between the surface cooling efficiency and the temperature gradient inside the casting. This imbalance can easily lead to uneven cooling or excessive thermal stress, which in turn affects the quality and production efficiency of the casting.

[0006] In addition to the lack of dynamic control, the lack of emergency mechanism is also an important problem in the existing technology. During the production process, it is inevitable to encounter various abnormal situations, such as fluctuations in pulling speed, insufficient water or deformation of the ingot. However, the existing technology often lacks a systematic disposal method and cannot respond to these abnormal situations in a timely and effective manner. For example, when the pulling speed is lower than 0.7m / min, continuous operation may increase the risk of excessive cooling, but the existing technology does not clearly give the corresponding operating thresholds and countermeasures. In addition, some rapid cooling devices are unable to adjust the water volume online to deal with deformation problems such as warping and arching of the ingot, which also brings 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, the pursuit of efficient production often means the need to increase the casting speed and cooling efficiency, but this may sacrifice the quality of the ingot; on the other hand, over-emphasizing quality control may lead to a decrease in production efficiency and an increase in costs. Therefore, it is urgent 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 according to the changes in these parameters. At the same time, it should also have a complete emergency mechanism to respond quickly when encountering abnormal situations to ensure the continuity of production and the precise control of the surface quality of the ingot. Through such technological innovation and optimization, it is expected to further improve the production efficiency and product quality of the continuous casting process, and inject new vitality into the sustainable development of the steel and metallurgical industry. Summary of the invention

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

[0010] To achieve the above object, the present invention provides the following technical solution: a continuous casting slab online rapid cooling production control method, comprising the following steps:

[0011] S1, cooling intensity setting: based on the steel type, slab section and drawing speed parameters, match the corresponding inner arc and outer arc cooling water volume, where:

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

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

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

[0015] S2, rapid cooling preparation stage:

[0016] S21, check the blockage of nozzles in each cooling section and test the actual water volume through the quick cooling interface to ensure that it is consistent with the preset value;

[0017] S22, close the manual valves of the 1st to 3rd rows of nozzles in the inner and outer arcs of SEG15;

[0018] S23, use an infrared temperature measuring gun to monitor the temperature of the wide surface center line, 1 / 4, corner and narrow surface of the quick cooling inlet and outlet;

[0019] S3, fast cooling implementation control:

[0020] S31, call the quick cooling water meter and start the quick cooling system, and perform the quick cooling operation after the head and tail billets are out of the 15th rack;

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

[0022] S33, turn on the quick cooling when the first furnace is poured at 32m, and turn off the quick cooling when the next furnace is poured at 36m;

[0023] S4, emergency response:

[0024] S41, if the water volume of the second cooling section of zones 1 to 4 is lower than the preset minimum threshold, the rapid cooling is terminated;

[0025] S42, when the casting billet shows warping at the head and tail or arching deformation in the middle, adjust the outer arc water volume to reduce 9% to 17% or the inner arc water volume to reduce 9% to 17% as needed, and adjust alternately until recovery.

[0026] Optionally, the quick cooling water meter is dynamically called by the L1-level computer system of the casting machine, and the operation steps include:

[0027] a. Execute "Instrument" → "Quick Cooling Water Meter" → "Z300-S" → "Water Meter Call" in sequence;

[0028] b. To turn on quick cooling, click "Secondary cooling water PID adjustment" → "Quick cooling on", and to turn off, execute "Secondary cooling water PID adjustment" → "Quick cooling off".

[0029] Optionally, the quick cooling is kept closed before the head billet and the tail billet come out of the 15-stage rack, and the head and tail billets are not subjected to quick cooling treatment when the first furnace is poured or the ladle is changed.

[0030] Optionally, when the head and tail of the ingot are warped, it is preferred to reduce the water volume of the outer arc by 9% to 17%, or restore the spray rack that has been closed in the inner arc.

[0031] Optionally, when the middle part of the ingot is arched, it is preferred to reduce the water volume in the inner arc by 9% to 17%. If this is ineffective, gradually increase the water volume in the outer arc by 10% to 17% until the deformation is improved.

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

[0033] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. DETAILED DESCRIPTION

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

[0035] The online rapid cooling production control method of the continuous casting slab of the present invention comprises the following steps:

[0036] 1. Preparation

[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 spray out smoothly.

[0039] Use the quick cooling interface to test the actual water delivery of each meter at different pulling speeds to ensure that the actual water delivery is consistent with the preset value.

[0040] To close some nozzles:

[0041] Before the rapid cooling begins, close the machine-side manual valves of the 1st, 2nd and 3rd rows of nozzles in the inner and outer arcs of the SEG15 segment to reduce unnecessary cooling water and avoid overcooling of the ingot.

[0042] Prepare temperature measurement tools:

[0043] Prepare an infrared temperature measuring gun to measure the temperature of the wide surface center line, wide surface 1 / 4, corner and narrow surface at the rapid cooling inlet and outlet, so as to monitor the cooling effect of the ingot in real time.

[0044] 2. Rapid cooling implementation process

[0045] Call the quick cooling water meter:

[0046] On the casting machine L1 computer, operate "Instrument" - "Quick Cooling Water Meter" - "Z300-S" - "Water Meter Call" in sequence to call the preset quick cooling water meter parameters.

[0047] Turn on fast cooling:

[0048] The first and last billets of the machine startup and package change are not subjected to rapid cooling. After the first billet leaves the 15-stage rack, turn on the rapid cooling water meter. Operate "Secondary cooling water PID adjustment" - "Rapid cooling start" on the L1-level computer of the casting machine in sequence, and check whether the rapid cooling water meter is in normal use and the actual water volume of the 15-stage on the main screen.

[0049] Pulling speed and rapid cooling control:

[0050] When the pulling speed is lower than 0.7m / min and lasts for more than 5 minutes, turn off the quick cooling water meter to avoid overcooling.

[0051] When the first rapid cooling furnace is pouring 32m, the rapid cooling water meter is turned on; when the last billet comes out of the 15th frame (the next furnace is pouring 36m), the rapid cooling water meter is turned off.

[0052] End of quick cooling:

[0053] When the rapid cooling is finished, operate "Secondary cooling water PID adjustment" - "Rapid cooling off" on the L1 computer of the casting machine in sequence to turn off the rapid cooling system.

[0054] III. Emergency Response

[0055] Abnormal water volume treatment:

[0056] During the production process, pay close attention to the water volume in zones 1 to 4. If the minimum water volume is lower than the preset requirement (260L / min for inner and outer arcs in zone 1, 100L / min for left and right sides, 135L / min for zone 2, 180L / min for zone 3, and 210L / min for zone 4), stop the rapid cooling test immediately to avoid adverse effects on the ingot.

[0057] Deformation treatment of casting billet:

[0058] If obvious warping of the head and tail of the casting is found, reduce the water volume of the outer arc by 9% to 17%, or observe the deformation and gradually restore the inner arc row by row, and close the spray rack to adjust the cooling intensity.

[0059] If obvious arching deformation is found in the middle of the billet, reduce the water volume of the inner arc by 9%-17%. Observe the next billet. If the billet arching is not improved, increase the water volume of the outer arc by 10%-17%. Adjust alternately and test in sequence to find the best cooling method.

[0060] Through the above specific implementation methods, the online rapid cooling production control method for continuous casting slabs can achieve precise control of the surface temperature of the casting slabs to ensure product quality; at the same time, it is compatible with high-speed production to improve 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 solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for controlling online rapid cooling of continuous casting slabs, characterized in that: The following steps are involved: S1, cooling intensity setting: matching the corresponding inner arc and outer arc cooling water volume based on steel type, slab section and drawing speed parameters; S2, rapid cooling preparation stage: S21, check the blockage of nozzles in each cooling section and test the actual water volume through the quick cooling interface to ensure that it is consistent with the preset value; S22, close the manual valves of the 1st to 3rd rows of nozzles in the inner and outer arcs of SEG15; S23, use an infrared temperature measuring gun to monitor the temperature of the wide surface center line, 1 / 4, corner and narrow surface of the quick cooling inlet and outlet; S3, fast cooling implementation control: S31, call the quick cooling water meter and start the quick cooling system, and perform the quick cooling operation after the head and tail billets are out of the 15th rack; S32, when the pulling speed is less than 0.7m / min and the duration is greater than 5min, the rapid cooling system is turned off; S33, turn on the quick cooling when the first furnace is poured at 32m, and turn off the quick cooling when the next furnace is poured at 36m; S4, emergency response: S41, if the water volume of the second cooling section of zones 1 to 4 is lower than the preset minimum threshold, the rapid cooling is terminated; S42, when the casting billet shows warping at the head and tail or arching deformation in the middle, adjust the outer arc water volume to reduce 9% to 17% or the inner arc water volume to reduce 9% to 17% as needed, and adjust alternately until recovery.

2. The method for controlling online rapid cooling of continuous casting slab according to claim 1, characterized in that: The quick cooling water meter is dynamically called by the L1 level computer system of the casting machine, and the operation steps include: a. Execute "Instrument" → "Quick Cooling Water Meter" → "Z300-S" → "Water Meter Call" in sequence; b. To turn on quick cooling, click "Secondary cooling water PID adjustment" → "Quick cooling on", and to turn off, execute "Secondary cooling water PID adjustment" → "Quick cooling off".

3. The method for controlling online rapid cooling of continuous casting slab according to claim 1, characterized in that: The quick cooling is kept closed before the head and tail billets come out of the 15-stage rack, and the head and tail billets are not subjected to quick cooling when the first furnace is poured or the ladle is changed.

4. The method for controlling online rapid cooling of continuous casting slab according to claim 1, characterized in that: When the head and tail of the ingot are warped, it is preferred to reduce the water volume in the outer arc by 9% to 17%, or restore the spray rack that has been closed in the inner arc.

5. The method for controlling online rapid cooling of continuous casting slab according to claim 1, characterized in that: When the middle part of the ingot is arched, it is preferred to reduce the water volume in the inner arc by 9% to 17%. If this is ineffective, gradually increase the water volume in the outer arc by 10% to 17% until the deformation is improved.