Hot air baking method and system for continuous casting tundish

Abstract

The invention relates to a hot air baking method and system for a continuous casting tundish. The method comprises the steps that a baking temperature curve is established according to hot air temperature and baking time; fuel combustion heat is stored in a hot blast stove, non-oxidizing gas is introduced into the hot blast stove, the non-oxidizing gas forms hot air through heat exchange, and the hot air temperature is controlled according to a baking temperature curve; hot air enters the tundish through the pipeline and bakes tundish refractory materials, waste low-temperature hot air obtained after tundish baking can be recycled to the hot air furnace after dust removal and then recycled, one hot air furnace can be adopted for baking a plurality of tundishes, flame baking can be replaced, and the hot air furnace is energy-saving and environment-friendly. Baking, curing and shaping of the liquid metal continuous casting tundish refractory are achieved through a safe and open-fire-free baking method, real-time accurate control over the tundish baking temperature is facilitated, noise can be reduced, energy can be saved, the production safety can be improved, the service life of a tundish can be prolonged, and then the purity of molten steel, the number of continuous casting furnaces and the yield are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of continuous casting tundish baking, and in particular relates to a continuous casting tundish hot air baking method and system. Background Art

[0002] During the continuous casting of liquid metal, the tundish serves as a buffer container for the molten steel, stabilizing the liquid level and flow rate, and providing a continuous and stable supply of molten steel to the crystallizer. The refractory material in the continuous casting tundish is a key material used to contain and protect the molten steel during the continuous casting process. Since the tundish baking process heats the phenolic resin, a curing agent in the dry material or coating lining refractory, so that the tundish lining is solidified and formed under the action of the phenolic resin and has a certain mechanical strength, it is generally necessary to bake the refractory material to above 900°C, and to ensure that the tundish lining refractory material does not collapse and absorbs as little heat as possible, so as to ensure that the refractory material can maintain a stable shape and performance under the high temperature of the liquid metal, ensuring the successful start of continuous casting. Therefore, the baking system and method directly affect the service life, production safety, and production energy consumption of the continuous casting tundish.

[0003] like Figure 1 As shown, the conventional continuous casting tundish 11 baking system generally adopts a gas baking device, including a tundish body 1, a tundish cover 3, a gas pipeline 4 provided on the tundish cover 3, a compressed air pipeline 5, and one or more baking burners 6. The bottom of the tundish body 1 is provided with a plurality of dust exhaust ports 8. After the tundish cover 3 is placed on the top of the tundish body 1, natural gas, coke oven gas, converter gas or blast furnace gas is introduced into the gas pipeline 4, and compressed air is introduced into the compressed air pipeline 5. After the baking burner 6 is ignited, the mixed compressed air can be burned in the tundish body 1, and the lining 2 of the tundish 11 refractory material 2 is baked by the burning flame 7, that is, the "open flame" baking method. The residual heat of baking is discharged through the dust exhaust port 8. There are the following problems:

[0004] (1) Failure risk: Due to the use of flame baking, the flame temperature may reach 800-2500℃, which is relatively unstable and prone to overheating. At the same time, the oxygen O2 in the exhaust gas during full combustion will oxidize and damage the organic phenolic resin, causing the phenolic resin that acts as the "skeleton" on the inner surface and surface of the working layer of the tundish to fail, resulting in the refractory material being resistant to corrosion during use. The corrosion of the refractory material in the tundish will cause contamination and denaturation of the covering agent, as well as contamination of the molten steel and affect the purity of the molten steel. When the refractory temperature exceeds 1200℃, it is easy to cause the refractory material to collapse or even peel off, which significantly reduces the service life of the tundish and may even cause production accidents.

[0005] (2) Uneven baking: According to the size, baking temperature requirements, etc., the tundish has one or more baking burners, which are set on the ladle cover. The temperature of the area farther away from the burner will be relatively lower, resulting in an uneven temperature field inside the entire tundish, and then causing uneven baking, leading to a decline in baking quality and refractory performance, and shortening the service life of the continuous casting tundish.

[0006] (3) Difficult baking control: Affected by the instability of the flame baking temperature, the temperature control of flame baking generally uses empirical judgment. At the same time, the temperature curve formulated for general flame baking describes the baking curve in terms of gas flow or the valve opening of the gas pipeline + time. Until the end of baking, an infrared thermometer gun is used to measure the temperature to determine whether it meets the process requirements. Therefore, the temperature control during baking is inaccurate, and the baking temperature needs to be measured offline manually with an infrared thermometer gun and then adjusted, resulting in cumbersome work, measurement errors, being not conducive to timely temperature adjustment and being unsafe.

[0007] (4) Noise problem: The baking burner of flame baking generates heat through the combustion of the mixture of gas and compressed air. In this process, the injection of gas, the inhalation of compressed air, and the combustion reaction itself will all generate relatively large noise, resulting in a poor on-site working environment.

[0008] (5) Safety hazards: Flame baking involves the long-distance on-site transportation of gas, and there are safety hazards such as gas leakage, fire explosion, poisoning and asphyxiation.

[0009] (6) Energy waste: Due to the limitations of the working environment, the baking waste heat is only directly extracted and discharged through the dust exhaust port without heat recovery, resulting in energy waste. Summary of the Invention

[0010] The present invention aims to solve at least one of the above technical problems to some extent. The present invention provides a hot air baking method and system for a continuous casting tundish, which can replace flame baking, and uses a safe and open-fire-free baking method to realize the baking and curing of the refractory of the liquid metal continuous casting tundish, facilitating the real-time and accurate control of the baking temperature of the tundish, and being able to reduce noise, save energy, improve production safety and the service life of the tundish.

[0011] The technical solution adopted by the present invention to solve its technical problems is:

[0012] One aspect of the present invention lies in providing a hot air baking method for a continuous casting tundish, and the method includes:

[0013] Establish a baking temperature curve according to the hot air temperature and the baking time;

[0014] The heat generated by fuel combustion is stored in the hot blast stove, and a non-oxidizing gas is introduced into the hot blast stove. The non-oxidizing gas forms hot air through heat exchange, and the hot air temperature is controlled according to the baking temperature curve.

[0015] The hot air enters the tundish through a pipeline and bakes the refractory of the tundish.

[0016] In a preferred technical solution, gas is used as the fuel.

[0017] In a preferred technical solution, the baking temperature curve includes: the first stage: the hot air temperature rises from room temperature to 120 - 170 °C at a rate of 3 - 5 °C / min and is maintained for 20 - 30 min, with a total time of not less than 60 min;

[0018] The second stage: the hot air temperature rises from 120 - 170 °C to 750 - 850 °C at a rate of 15 - 20 °C / min and is maintained for 20 - 30 min, with a total time of not less than 60 min;

[0019] The third stage: the hot air temperature rises from 750 - 850 °C to 1150 - 1200 °C at a rate of 10 - 15 °C / min and is maintained for not less than 150 min, with a total time of not less than 200 min.

[0020] In a preferred technical solution, a movable cover that can cooperate with the tundish is used during baking. The hot air inlet of the cover avoids the tundish nozzle and extends to the middle of the tundish for air intake.

[0021] In a preferred technical solution, multiple hot air inlets facing the side wall and bottom of the tundish are used for air intake during baking.

[0022] In a preferred technical solution, the hot air outlet in the tundish is circulated back to the hot blast stove during baking.

[0023] In a preferred technical solution, the method for controlling the hot air temperature according to the baking temperature curve includes:

[0024] Taking the data including the heat storage of the hot blast stove at the current moment, the hot blast stove temperature, the hot air temperature and flow rate entering the tundish, and the circulating hot air temperature and circulating hot air heat exiting the tundish as input data, and taking the hot air temperature at the future t moment as output data, a hot air temperature prediction model is established;

[0025] Based on the baking temperature curve, the target hot air temperature is determined. The input data is collected in real time, and the predicted value of the hot air temperature at the future t moment is determined based on the hot air temperature prediction model. A control strategy is formulated according to the difference between the target hot air temperature and the predicted value of the hot air temperature at the future t moment.

[0026] In a preferred technical solution, after the hot air in the tundish exits and is dust-removed, it is recycled to the hot blast stove.

[0027] In a preferred technical solution, the air outlet at the positive pressure under the tundish nozzle is used for air extraction. According to the temperature difference between the hot air temperature entering the tundish and the recycled hot air temperature exiting the tundish, the air extraction speed of the air extraction fan at the air extraction port is controlled.

[0028] In a preferred technical solution, one hot blast stove is used to bake multiple tundishes.

[0029] Another aspect of the present invention is to provide a hot air baking system for a continuous casting tundish, including a hot blast stove, a pipeline, a tundish, and a control system;

[0030] The hot blast stove is used to heat non-oxidizing gas to form hot air;

[0031] The hot air outlet of the hot blast stove is connected to the hot air inlet of the tundish through a pipeline;

[0032] The control system is used to control the operation of the hot blast stove and the pipeline, establish a baking temperature curve based on the hot air temperature and the baking time, and control the hot air temperature according to the baking temperature curve.

[0033] In a preferred technical solution, a circulation pipe is provided between the hot air outlet of the tundish and the hot blast stove. A suction fan is provided on the circulation pipe, and the control system is used to control the operation of the suction fan.

[0034] In a preferred technical solution, a dust removal device is provided on the circulation pipe.

[0035] In a preferred technical solution, the control system includes several data acquisition devices, and the control system operates based on the hot air baking method for a continuous casting tundish described in any one of the above.

[0036] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0037] (1) It can avoid the risk of failure: By heating non-oxidizing gas with a hot blast stove to form hot air for baking the tundish refractories, it can replace flame baking. A safe and open-flame-free baking method is used to bake and solidify the tundish refractories for continuous casting of liquid metal, eliminating the oxidation of phenolic resin that plays a skeletal role in the refractories by open-flame baking, avoiding the refractories from being eroded or even spalling due to oxidation, being beneficial to improving the service life of the tundish, reducing the pollution and denaturation of the tundish refractories to the covering agent and the pollution of the refractories to the molten steel, and thus improving the purity, continuous casting furnace number, and yield of the molten steel.

[0038] (2) More uniform baking: By baking the tundish refractories more uniformly with hot air, it is beneficial to improve the baking quality and maintain the refractory properties. The baking uniformity can be further improved by optimizing the position and orientation of the hot air inlet.

[0039] (3) Easy baking control: Establish a baking temperature curve based on the hot air temperature and baking time, and control the hot air temperature according to the baking temperature curve to make the baking easy to control. The intelligent control of the hot air temperature can be carried out by establishing a hot air temperature prediction model, real-time prediction and control, improving the foresight, preventive ability, response speed and dynamic adaptability, and further improving the accuracy of the hot air temperature control, ensuring sufficient heat exchange between the hot air and the refractories, facilitating the control of the superheat during pouring, and improving the quality stability of the continuous casting billets.

[0040] (4) Baking noise reduction: There is no noise from the flameless baking, which "quiets" the on-site working environment.

[0041] (5) Safer production: There is no gas such as coal gas on site, which improves the production safety.

[0042] (6) Energy saving: The waste low-temperature hot air after baking the tundish can be recycled to the hot blast stove for reuse after dust removal. One hot blast stove can be used to bake multiple tundishes, saving energy. Description of the Drawings

[0043] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, wherein:

[0044] Figure 1 is the continuous casting tundish baking system in the prior art;

[0045] Figure 2 is a schematic use diagram of an embodiment of the present invention;

[0046] Figure 3 is a schematic diagram of the air inlet and outlet of the tundish in an embodiment of the present invention.

[0047] Markings in the figure: tundish body 1, refractory 2, ladle cover 3, gas pipeline 4, compressed air pipeline 5, baking burner 6, flame 7, dust exhaust port 8, hot blast stove 9, pipeline 10, tundish 11, first pipeline 12, second pipeline 13, third pipeline 14, air inlet pipe 15, hot air inlet 16, hot air outlet 17, circulation pipe 18, suction port 19, suction fan 20, dust removal device 21, control terminal 22, first flowmeter 23, second flowmeter 24, third flowmeter 25, fourth flowmeter 26, first thermometer 27, second thermometer 28, fifth flowmeter 29, third thermometer 30, and the unmarked arrows indicate the flow direction. Detailed Embodiments

[0048] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0049] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality" and "several" is two or more, unless otherwise specifically defined.

[0050] In the present invention, unless otherwise clearly specified and defined, terms such as "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] Regarding the "open fire" baking method using a gas baking furnace for baking the continuous casting tundish 11 in the prior art, problems such as failure risk, uneven baking, difficult baking control, noise problems, and safety hazards are generated. The present invention considers using a hot air baking method and system without open fire to replace the flame 7 baking for baking and curing the refractory 2 of the liquid metal continuous casting tundish 11, so as to accurately control the baking temperature of the tundish 11, reduce noise, improve production safety, and extend the service life of the tundish 11. As Figure 2 shown, it is a preferred embodiment of the continuous casting tundish hot air baking system of the present invention, which includes a hot blast stove 9, a pipeline 10, a tundish 11, and a control system;

[0052] The hot blast stove 9 is used to heat non-oxidizing gas to form hot air;

[0053] The hot air outlet 17 of the hot blast stove 9 is connected to the hot air inlet 16 of the tundish 11 through the pipeline 10;

[0054] The described control system is used to control the operation of the hot blast stove 9 and the pipeline 10, establish a baking temperature curve based on the hot air temperature and the baking time, and control the hot air temperature according to the baking temperature curve.

[0055] Then the hot air baking method for the continuous casting tundish may include:

[0056] Establish a baking temperature curve based on the hot air temperature and the baking time;

[0057] Use the heat of fuel combustion to store heat in the hot blast stove 9, introduce a non-oxidizing gas into the hot blast stove 9, the non-oxidizing gas forms hot air through heat exchange, and control the hot air temperature according to the baking temperature curve;

[0058] The hot air enters the tundish 11 through the pipeline 10 and bakes the refractory 2 of the tundish 11.

[0059] The above system and method can use the heat of fuel combustion to store heat in the hot blast stove 9, introduce a non-oxidizing gas into the hot blast stove 9, for example: nitrogen, which is relatively inexpensive, non-toxic and also used in smelting in steel mills, to form hot air, establish a baking temperature curve based on the hot air temperature and the baking time, control the hot air temperature, form hot air at different temperatures, enter the tundish 11 to bake the refractory 2, and has the following advantages compared with the flame 7 baking:

[0060] First, avoid the risk of failure: On the one hand, the baking method of non-open-flame hot air can control the hot air heating rate and the maximum hot air temperature, and better avoid over-baking. On the other hand, the hot air takes advantage of the characteristics of the non-oxidizing gas that is chemically inert and not easily oxidized with other substances, eliminating the oxidation of the phenolic resin that plays a "skeleton" role in the dry material or coating refractory 2 by open-flame baking, avoiding the erosion resistance and even spalling of the refractory 2 due to oxidation, and effectively avoiding the risk of failure. The service life of the tundish 11 can be increased by more than 20%, which is beneficial to reducing the pollution and denaturation of the refractory 2 of the tundish 11 to the covering agent, reducing the pollution of the refractory 2 to the molten steel, improving the purity of the molten steel, and thus increasing the number of continuous casting heats of the molten steel. Depending on the billet specifications, ladle capacity, and quality requirements, the molten steel yield of the steel mill can be increased by more than 0.5%.

[0061] Second, more uniform baking: Compared with the heat of the open flame concentrated near the baking burner 6, the flow of hot air in the tundish 11 is relatively uniform, which can more comprehensively cover the inner surface of the tundish 11, reducing local overheating or overcooling, so the baking is more uniform, which is beneficial to improving the baking quality and maintaining the performance of the refractory 2.

[0062] III. Easy baking control: By establishing a baking temperature curve based on the hot air temperature and baking time, and controlling the hot air temperature according to the baking temperature curve. The hot air temperature is more stable, easier to obtain and control compared to the flame temperature. During the process, the hot air temperature can be adjusted in a timely manner according to the baking temperature curve, replacing the description of the baking curve with the gas flow rate or the valve opening degree of the gas pipeline 4 + time, avoiding the errors and cumbersome problems of manual off-line measurement and adjustment with an infrared thermometer gun. It can improve the accuracy and convenience of the baking temperature control of the tundish 11, which is beneficial to the control of the superheat during the pouring of the tundish 11 in the continuous casting process and improves the quality stability of the continuous casting billet.

[0063] IV. Baking noise reduction: There is no need to set a baking burner 6 for ignition and combustion inside the ladle cover 3, and there is no baking noise from the flame 7, which "quiets" the on-site working environment.

[0064] V. Safer production: Compared with the in-body heat storage of the flame 7 baking that requires on-site gas transportation, since the hot blast stove 9 stores heat outside the tundish 11, the hot blast stove 9 can be set outside the production plant, without occupying the on-site area. There is no gas such as coal gas and open fire on-site, which can avoid safety hazards such as on-site gas leakage, fire explosion, poisoning and asphyxiation, and improve the safety of production operations.

[0065] Furthermore, gas is used as fuel. For example: as Figure 2 shown, the hot blast stove 9 adopts a regenerative hot blast stove 9, which has a first pipeline 12, a second pipeline 13 and a third pipeline 14. The first pipeline 12 is used to transport gas such as natural gas, coke oven gas, converter gas or blast furnace gas to the hot blast stove 9. The second pipeline 13 is used to transport compressed air to the hot blast stove 9. After ignition, the mixed compressed air burns inside the hot blast stove 9. The third pipeline 14 is used to transport non-oxidizing gases such as nitrogen and low-cost inert gases to the hot blast stove 9, and the heat is used to heat the non-oxidizing gases to form hot air at different temperatures.

[0066] Furthermore, the baking temperature curve includes:

[0067] In the first stage, low-temperature baking is adopted. In this stage, the crystal water in the dry material and the physical water mixed in the air during pouring are mainly evaporated sufficiently. It is necessary to avoid too fast heating rate or too little holding time, resulting in insufficient or too fast water volatilization, which is prone to stress cracking during the rapid baking in the next stage. Therefore, in the first stage: the hot air temperature rises from room temperature to 120 - 170 °C at a rate of 3 - 5 °C / min and is held for 20 - 30 min, and the total time is not less than 60 min.

[0068] The second stage adopts medium temperature baking, which is mainly used to solidify the dry material. The solidification temperature of the binder phenolic resin is generally between 50 and 200°C, but the thermal insulation performance of the refractory material 2 is good, that is, the heat transfer performance is poor. A higher temperature is required to strengthen the temperature difference between the intermediate ladle 11 and the refractory material 2, solidify the phenolic resin, and sinter the magnesium dry material. Therefore, in the second stage: the hot air temperature is increased from 120 to 170°C at a rate of 15 to 20°C / min to 750 to 850°C, and maintained for 20 to 30 minutes, and the total time is not less than 60 minutes.

[0069] The third stage adopts high-temperature baking, which accelerates the sintering speed and makes the refractory material 2 more stable. Practice has shown that baking above 1200℃ under flame 7 state will cause the working layer of the ladle 11 or the slag retaining wall structure to collapse or even pulverize due to mineral phase changes under oxygen conditions. Hot air baking avoids the temperature unevenness of flame 7 baking, and there is no local overheating. The non-oxidizing atmosphere prevents the oxidation of the solidified phenolic resin on the surface of the working layer, ensuring the stability of the working layer. High-temperature baking fully sinters the refractory material 2, and the refractory material 2 fully absorbs heat to a saturated heat capacity state, further ensuring that the tundish 11 will not absorb too much heat from the liquid metal during the initial use stage, avoiding large fluctuations in the molten steel temperature and affecting the fluidity and solidification characteristics of the continuous casting molten steel, protecting the lining 2 and extending its service life. Therefore, in the third stage: the hot air temperature is increased from 750~850℃ to 1150~1200℃ at a rate of 10~15℃ / min, and maintained for not less than 150min, with a total time of not less than 200min.

[0070] Furthermore, during the baking, a movable cover 3 is used which can cooperate with the tundish 11, and the hot air inlet 16 of the cover 3 avoids the water inlet of the tundish 11 and extends to the middle of the tundish 11 for air intake; for example: Figure 3 As shown, the ladle cover 3 can be separated from the tundish body 1. When baking, after the tundish body 1 is in place, the ladle cover 3 is installed on the top of the tundish body 1. The center of the ladle cover 3 is provided with an air inlet pipe 15 whose length extends to 1 / 2 of the depth of the tundish body 1. The end opening of the air inlet pipe 15 serves as a hot air inlet 16. The hot air inlet 16 can be set according to the size of the tundish 11. The uniformity of the hot air flow and the temperature field in the tundish 11 during baking can be further improved by optimizing the air inlet position, thereby improving the baking uniformity.

[0071] Furthermore, during the baking, multiple hot air inlets 16 are used to supply air toward the side walls and bottom of the tundish 11; for example: Figure 3 As shown, the ends of the air inlet pipe 15 are provided with openings in the front, rear, left, right and bottom directions, and the hot air inlet 16 adopts a "five-hole" mode. By optimizing the direction of the hot air inlet 16, the uniformity of the hot air flow and temperature field in the intermediate ladle 11 can be further improved, thereby improving the baking uniformity.

[0072] Further, during baking, the hot air discharged from the tundish 11 is circulated back to the hot blast stove 9. For example: as Figure 2 shown, a circulation pipe 18 is provided between the hot air outlet of the tundish 11 and the hot blast stove 9 to extract the waste hot air that has undergone heat exchange in the tundish 11 and return it to the hot blast stove 9 for recycling, which can further recover waste heat, save energy and production costs, and reduce emissions.

[0073] Further, after the hot air discharged from the tundish 11 is dust-removed, it is then circulated back to the hot blast stove 9. For example: as Figure 2 shown, a dust removal device 21 is provided on the circulation pipe 18. The dust removal device 21 uses methods such as filtration or gravity dust removal to remove dust from the waste hot air, which can further prevent affecting the stable operation of the hot blast stove 9.

[0074] Further, the method for controlling the hot air temperature according to the baking temperature curve includes:

[0075] Taking the data including the heat storage capacity of the hot blast stove 9 at the current moment, the temperature of the hot blast stove 9, the hot air temperature and hot air flow rate entering the tundish 11, and the circulating hot air temperature and circulating hot air heat quantity exiting the tundish 11 as input data, and taking the hot air temperature at the future t moment as output data, to establish a hot air temperature prediction model; determining the target hot air temperature based on the baking temperature curve, collecting the input data in real time and determining the predicted value of the hot air temperature at the future t moment based on the hot air temperature prediction model, and formulating a control strategy according to the difference between the target hot air temperature and the predicted value of the hot air temperature at the future t moment; specifically, it may include the following steps:

[0076] Step 1. Data collection: The control system includes a control terminal 22 and several data collection devices connected to the control terminal 22. The several data collection devices may include a first flowmeter on the first pipeline 12, a second flowmeter on the second pipeline 13, a third flowmeter on the third pipeline 14, a fourth flowmeter and a first thermometer on the pipeline 10, a second thermometer, a fifth flowmeter and a third thermometer on the circulation pipe 18;

[0077] The first flowmeter 23 is used to measure and feedback the gas flow rate; the second flowmeter 24 is used to measure and feedback the compressed air flow rate; the third flowmeter 25 is used to measure and feedback the non-oxidizing gas flow rate; the fourth flowmeter 26 is arranged near the hot blast stove 9 and is used to measure and feedback the hot air flow rate into the tundish 11; the first thermometer 27 is arranged near the tundish 11 and is used to measure and feedback the hot air temperature into the tundish 11; the second thermometer 28 is arranged near the tundish 11 and is used to measure and feedback the circulating hot air temperature out of the tundish 11; the fifth flowmeter 29 is used to measure and feedback the circulating hot air flow rate out of the tundish 11; the third thermometer 30 is arranged near the hot blast stove 9 and is used to measure and feedback the circulating hot air temperature into the hot blast stove 9; the control terminal 22 is electrically connected to the control end of the hot blast stove 9 to obtain the heat storage capacity of the hot blast stove 9 and the temperature of the hot blast stove 9; the data acquisition device continuously collects various data and records the hot air temperature at the future t moment corresponding to the current moment according to the second thermometer 28, for example, the hot air temperature several minutes later.

[0078] Step two: Data preprocessing: Clean the data collected by the data acquisition device, remove the outliers and incorrect data in the data, such as the obviously unreasonable data points caused by the failure of the data acquisition device, to ensure the accuracy and reliability of the data. At the same time, normalize the data to convert the physical quantities of flow rates at different temperatures into a unified numerical range, which is convenient for subsequent model training and calculation.

[0079] Step three: Establish a hot air temperature prediction model: Use deep learning or machine learning algorithms, such as neural network ANN, long short-term memory network LSTM, etc., to establish a hot air temperature prediction model. These models can process time series data and capture the time-dependent relationship between the input variables and the hot air temperature at the future t moment. The input data of the model is the various data collected by the data acquisition device at the current moment. Determine the number of nodes in the input layer according to the number of input data. The output data of the model is the hot air temperature at the future t moment corresponding to the current moment. Divide the preprocessed data into a training set, a validation set, and a test set including multiple groups of corresponding input data and output data.

[0080] Define the loss function and optimizer. For example: Select the mean squared error (MSE) as the loss function to measure the difference between the model's predicted value and the actual value. Input the training set data into the hot air temperature prediction model, and adjust the weights and biases of the model through the backpropagation algorithm. Calculate the hidden layer to minimize the loss function. Set the evaluation metrics. Use the test set to evaluate the trained model, that is, input the input data of the test set into the trained hot air temperature prediction model to obtain the predicted value of the hot air temperature at the future time t, and compare it with the output data, which is the true value of the hot air temperature at the future time t. Calculate metrics such as the mean squared error, mean absolute error, root mean squared error, and coefficient of determination to evaluate the model. Taking the mean absolute error and root mean squared error as examples of evaluation metrics, the smaller the value, the higher the prediction accuracy of the model. Taking the coefficient of determination as an example of the evaluation metric, the closer the coefficient of determination is to 1, the better the model's fitting degree to the data. Regularly evaluate the performance of the model on the validation set, and adjust the hyperparameters of the model, such as the number of nodes in the hidden layer, according to the loss value on the validation set. When the loss on the validation set no longer decreases significantly, stop training. Use a large amount of data to train and optimize the model, adjust the model's parameters, and improve the prediction accuracy and generalization ability of the model by continuously optimizing the model structure and parameters, so that the model can better adapt to various changes during the operation of the hot blast stove 9, such as changes in raw material characteristics and equipment wear, thereby improving the control accuracy and stability. Finally, obtain the trained hot air temperature prediction model and save it in the control terminal 22.

[0081] Step Four: Real-time Prediction: During the actual operation of baking the tundish 11, based on several data acquisition devices, collect various data in real time and feedback it to the control terminal 22. The control terminal 22 inputs the data of the data acquisition devices into the trained hot air temperature prediction model in Step Three, outputs the predicted value of the hot air temperature at the future time t, and conducts real-time prediction.

[0082] Step 5. Real-time control: During the actual operation of baking the tundish 11, the control terminal 22 determines the target hot air temperature based on the baking temperature curve, and formulates a control strategy according to the difference between the target hot air temperature and the predicted value of the hot air temperature at the future time t obtained in Steps 3 and 4. For example, the control strategy is formulated as follows: If the predicted value of the hot air temperature is lower than the target hot air temperature, the gas and compressed air flow rates can be increased to increase the temperature of the hot blast stove 9, and at the same time, the flow rates of the hot air and the recycled hot air can be appropriately adjusted to increase the hot air temperature; conversely, if the predicted value of the hot air temperature is higher than the target hot air temperature, the opposite measures can be taken, and factors such as the temperature error and the change rate of the control quantity can be considered to balance the control effect and the stability of the system; the control terminal 22 sets a control model according to the control strategy, calculates the control actions that should be taken at the current moment, that is: the adjustment of the combustion heating flow rate, the flow rate adjustment of the non-zinc oxide gas at room temperature, and the flow rate adjustment of the recycled hot air. Based on the hot air temperature entering the tundish 11 minus the recycled hot air temperature exiting the tundish 11, the hot air temperature drop before and after baking is calculated, and the hot air temperature drop control before and after baking and the automatic combustion control of the hot blast stove 9 are carried out.

[0083] The method of controlling the hot air temperature according to the baking temperature curve has a certain delay in temperature detection, signal transmission and processing compared with formulating a control strategy by comparing the actually measured hot air temperature entering the tundish 11 with the first thermometer 27 and the target hot air temperature, resulting in a relatively slow response speed of the control system. By establishing a hot air temperature prediction model, real-time prediction and real-time control are carried out so that the current adjustment actions can make the hot air temperature at the future time t as close as possible to the target hot air temperature. Temperature deviations that may occur can be predicted in advance at the current moment and adjustment actions can be taken in advance, rather than reacting after the actually measured temperature shows a deviation, so as to have better foresight and preventive ability. The control system can respond faster, shorten the adjustment time. At the same time, considering that in the actual production process, the hot air temperature is affected by various factors such as the hot blast stove 9, transportation, dust removal and recycling, and these factors are often dynamically changing. The hot air temperature prediction model can consider the interaction between these complex dynamic factors, more accurately capture the change trend of the hot air temperature, and update the prediction results in real time according to the latest input data through real-time prediction and real-time control, making the control strategy more accurate, improving the adaptability to dynamic changes, and further improving the accuracy, stability and intelligence of temperature control, reducing temperature fluctuations, which is beneficial to improving the uniformity of tundish 11 baking and product quality. It can also provide information about future temperature changes for operators to make more reasonable decisions. For example, according to the prediction results, operators can adjust the production plan in advance or take corresponding measures to deal with possible temperature anomalies.

[0084] Furthermore, the air outlet 19 under the nozzle of the tundish 11 is used for positive-pressure air extraction, and the air extraction speed of the air extractor 20 at the air outlet 19 is controlled according to the temperature difference between the hot air temperature entering the tundish 11 and the circulating hot air temperature exiting the tundish 11. For example, as Figure 3 shown, there are multiple air outlets 19, the air outlets 19 are connected to the circulation pipe 18, and the circulation pipe 18 is provided with an air extractor 20. The control system is used to control the operation of the air extractor 20. Under the air extraction action of the air extractor 20, the hot air in the tundish 11 passes through the air outlet 19 with slightly positive pressure under the nozzle, and the low-temperature hot air after heat exchange in the tundish 11 is extracted. While baking the pouring nozzle, the extracted low-temperature hot air is filtered and then returned to the hot blast stove 9 for reuse. According to the temperature difference between the hot air temperature entering the tundish 11 and the circulating hot air temperature exiting the tundish 11, that is, the temperature drop value △T of the hot air before and after baking, for example, △T = 10 - 100 °C, the air extraction speed of the air extractor 20, that is, the circulating hot air flow rate exiting the tundish 11, is adjusted and controlled to further ensure sufficient heat exchange between the hot air and the refractory 2.

[0085] Furthermore, one hot blast stove 9 is used to bake multiple tundishes 11. For example, the hot air outlet 17 of the hot blast stove 9 is connected to the hot air inlets 16 of multiple tundishes 11, and the circulation pipes 18 of multiple tundishes 11 are connected to the hot blast stove 9, so as to further save energy, reduce emissions, and improve the baking efficiency.

[0086] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A hot air baking method for a continuous casting tundish, characterized in that, The method includes: Establishing a baking temperature curve based on the hot air temperature and baking time; Using the heat generated by fuel combustion to store heat in the hot blast stove (9), introducing a non-oxidizing gas into the hot blast stove (9), and the non-oxidizing gas forms hot air through heat exchange, and controlling the hot air temperature according to the baking temperature curve; The hot air enters the tundish (11) through the pipeline (10) and bakes the refractory material (2) of the tundish (11).

2. The hot air baking method for the continuous casting tundish according to claim 1, wherein The baking temperature curve includes: The first stage: The hot air temperature rises from room temperature to 120 - 170 °C at a rate of 3 - 5 °C / min and is maintained for 20 - 30 min, and the total time is not less than 60 min; The second stage: The hot air temperature rises from 120 - 170 °C to 750 - 850 °C at a rate of 15 - 20 °C / min and is maintained for 20 - 30 min, and the total time is not less than 60 min; The third stage: The hot air temperature rises from 750 - 850 °C to 1150 - 1200 °C at a rate of 10 - 15 °C / min and is maintained for not less than 150 min, and the total time is not less than 200 min.

3. The hot air baking method for the continuous casting tundish according to claim 1, characterized in that During baking, a movable cover (3) that can cooperate with the tundish (11) is used, and the hot air inlet (16) of the cover (3) avoids the nozzle of the tundish (11) and extends to the middle of the tundish (11) for air intake.

4. The hot air baking method for the continuous casting tundish according to claim 1, characterized in that, During baking, multiple hot air inlets (16) facing the side wall and bottom of the tundish (11) are used for air intake.

5. The hot air baking method for continuous casting tundish according to claim 1, characterized in that, During baking, the hot air outlet in the tundish (11) is circulated to the hot blast stove (9).

6. The hot air baking method for continuous casting tundish according to claim 5, characterized in that, The method for controlling the hot air temperature according to the baking temperature curve includes: Taking the data including the heat storage amount of the hot blast stove (9) at the current moment, the temperature of the hot blast stove (9), the hot air temperature and flow rate entering the tundish (11), and the circulating hot air temperature and heat of the circulating hot air leaving the tundish (11) as input data, and taking the hot air temperature at the future t moment as output data, to establish a hot air temperature prediction model; Based on the baking temperature curve, determining the target hot air temperature, real-time collecting the input data and determining the predicted value of the hot air temperature at the future t moment based on the hot air temperature prediction model, and formulating a control strategy according to the difference between the target hot air temperature and the predicted value of the hot air temperature at the future t moment.

7. The hot air baking method for the continuous casting tundish according to claim 5, characterized in that, After the hot air outlet in the tundish (11) is dust-removed, it is recycled to the hot blast stove (9).

8. The hot air baking method for the continuous casting tundish according to claim 5, characterized in that, Using the air extraction port (19) with positive pressure under the nozzle of the tundish (11) for air outlet, and controlling the air extraction speed of the air extraction fan (20) at the air extraction port (19) according to the temperature difference between the hot air temperature entering the tundish (11) and the circulating hot air temperature leaving the tundish (11).

9. The hot air baking method for the continuous casting tundish according to any one of claims 1 to 8, characterized in that Using one hot blast stove (9) to bake multiple tundishes (11).

10. A hot air baking system for continuous casting tundish, characterized in that, Including a hot blast stove (9), a pipeline (10), a tundish (11) and a control system; The hot blast stove (9) is used to heat the non-oxidizing gas to form hot air; The hot air outlet (17) of the hot blast stove (9) is connected to the hot air inlet (16) of the tundish (11) through the pipeline (10); The control system is used to control the operation of the hot blast stove (9) and the pipeline (10), establish a baking temperature curve according to the hot air temperature and baking time, and control the hot air temperature according to the baking temperature curve.

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