Method and device for determining parameters of continuous casting mold based on multi-index comprehensive score

Abstract

The application relates to the technical field of continuous casting crystallizers, and discloses a continuous casting crystallizer parameter determination method and device based on multi-index comprehensive scoring. In the method, a three-dimensional model containing a crystallizer body, a water gap, a molten steel area, a liquid protective slag area and an air area is established, transient flow field simulation is carried out on different water gap structure parameters and / or continuous casting process parameters, liquid surface instantaneous maximum speed, liquid surface wave height, liquid protective slag exposed area, liquid surface speed distribution data and slag entrapment amount in a preset time period are obtained, a comprehensive score is calculated based on the above results, and the continuous casting crystallizer parameters are determined according to the comprehensive score. The application is favorable for improving the objectivity of continuous casting crystallizer parameter screening under the premise of considering liquid surface activity and interface stability.

Description

Technical Field

[0001] This application relates to the technical field of continuous casting molds, and in particular to a method and apparatus for determining the parameters of continuous casting molds based on a multi-index comprehensive scoring. Background Technology

[0002] The continuous casting mold is a core piece of equipment in steel continuous casting production. Its main function is to cool and solidify the high-temperature molten steel in the ladle into a billet shell of a certain thickness, while ensuring the internal quality of the billet. Currently, defects such as slag inclusions and surface cracks frequently appear in the billets produced by continuous casting molds, affecting product quality. Therefore, how to improve the product quality of continuous casting molds has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0003] In view of this, this application provides a method and apparatus for determining continuous casting mold parameters based on a multi-index comprehensive scoring system. This method establishes a three-dimensional model including the mold body, nozzle, molten steel region, liquid protective slag region, and air region. Transient flow field simulations are performed on different nozzle structural parameters and / or continuous casting process parameters to obtain the instantaneous maximum velocity of the liquid surface, liquid surface wave height, exposed area of ​​the liquid protective slag, liquid surface velocity distribution data, and slag entrainment amount within a preset time period. A comprehensive score is calculated based on the above results, and the continuous casting mold parameters are determined according to the comprehensive score. This application helps to improve the objectivity of continuous casting mold parameter selection while taking into account both liquid surface activity and interface stability.

[0004] According to one aspect of this application, a method for determining continuous casting mold parameters based on multi-index comprehensive scoring is provided, comprising: A three-dimensional model of the continuous casting crystallizer is established, which includes the continuous casting crystallizer body, nozzle, molten steel zone, liquid protective slag zone and air zone; Multiple candidate continuous casting crystallizer parameters are determined; the candidate continuous casting crystallizer parameters include nozzle structure parameters and / or continuous casting process parameters; the nozzle structure parameters include nozzle inner diameter, side hole inclination angle, side hole size, side hole shape, and well depth; the continuous casting process parameters include billet pulling speed, insertion depth, and argon blowing flow rate; The three-dimensional model is imported into the computational fluid dynamics simulation software, and flow field simulation calculations are performed on each of the selected continuous casting crystallizer parameters to obtain the corresponding simulation results. The simulation results include the instantaneous maximum velocity of the liquid surface, the wave height of the liquid surface, the exposed area of ​​the liquid protective slag, the liquid surface velocity distribution data, and the amount of slag entrainment within a preset time period. Based on the simulation results corresponding to the parameters of the candidate continuous casting crystallizer, the index data are calculated; wherein, the index data includes the average instantaneous maximum velocity of the liquid surface, the maximum liquid surface wave height, the average liquid surface wave height, the average exposed area of ​​the liquid protective slag, the area ratio of the target velocity range, and the average amount of slag entrainment. Based on the index data corresponding to all the candidate continuous casting crystallizer parameters, the score of each index data is determined; the scores of the index data corresponding to the candidate continuous casting crystallizer parameters are weighted and summed to obtain the comprehensive score corresponding to the candidate continuous casting crystallizer parameters. The candidate continuous casting crystallizer parameters corresponding to the highest comprehensive score are determined as the final continuous casting crystallizer parameters.

[0005] In some embodiments, the step of calculating index data based on the simulation results corresponding to the parameters of the candidate continuous casting crystallizer includes: Calculate the time average of the instantaneous maximum velocity of the liquid surface at each moment within the preset time period in the simulation results, and use it as the average instantaneous maximum velocity of the liquid surface; From the liquid surface wave heights within the preset time period, the liquid surface wave height with the largest offset relative to the initial liquid surface is selected as the maximum liquid surface wave height. Calculate the time average of the absolute values ​​of the liquid surface wave height within the preset time period, and use it as the average liquid surface wave height; Calculate the time average of the exposed area of ​​the liquid protective slag within the preset time period, and use it as the average exposed area of ​​the liquid protective slag; The average time proportion of the area within the target speed range in the liquid surface velocity distribution data within the preset time period to the total liquid surface area is calculated as the liquid surface velocity distribution; wherein, the minimum value of the target speed range is a first preset speed, the maximum value is a second preset speed, and the second preset speed is a preset critical slag entrapment speed; Calculate the time average of the amount of slag carried over the preset time period as the average amount of slag carried.

[0006] In some embodiments, the step of determining the score of each index data based on the index data corresponding to all candidate continuous casting crystallizer parameters includes: Based on the index data corresponding to all candidate continuous casting crystallizer parameters, determine the optimal and worst values ​​of each index data; The score corresponding to the indicator data is determined by a linear mapping rule; wherein the optimal value of the indicator data is mapped to a first preset score, and the worst value of the indicator data is mapped to a second preset score; the first preset score is higher than the second preset score.

[0007] In some embodiments, the step of determining the optimal and worst values ​​of each index data based on the index data corresponding to all candidate continuous casting crystallizer parameters includes: The smallest of all the instantaneous maximum velocities of the average liquid surface is determined as the optimal value of the instantaneous maximum velocities of the liquid surface; the largest of all the instantaneous maximum velocities of the average liquid surface is determined as the worst value of the instantaneous maximum velocities of the liquid surface. Among all the maximum liquid surface wave heights, the smallest maximum liquid surface wave height is determined as the optimal value of the maximum liquid surface wave height; among all the maximum liquid surface wave heights, the largest maximum liquid surface wave height is determined as the worst value of the maximum liquid surface wave height. Among all the average liquid surface wave heights, the smallest average liquid surface wave height is determined as the optimal value of the average liquid surface wave height; among all the average liquid surface wave heights, the largest average liquid surface wave height is determined as the worst value of the average liquid surface wave height. The smallest average exposed area of ​​the liquid protective slag among all the average exposed areas is determined as the optimal value of the average exposed area of ​​the liquid protective slag; the largest average exposed area of ​​the liquid protective slag among all the average exposed areas of the liquid protective slag is determined as the worst value of the average exposed area of ​​the liquid protective slag. The largest target speed interval area ratio among all the target speed interval area ratios is determined as the optimal value of the target speed interval area ratio; the smallest target speed interval area ratio among all the target speed interval area ratios is determined as the worst value of the target speed interval area ratio. The minimum average slag amount among all the average slag amounts is determined as the optimal value of the average slag amount; the maximum average slag amount among all the average slag amounts is determined as the worst value of the average slag amount.

[0008] In some embodiments, the range of the nozzle inner diameter in the selected continuous casting crystallizer parameters is 50 mm - 85 mm.

[0009] In some embodiments, the side hole inclination angle in the selected continuous casting crystallizer parameters ranges from 15° to 45°.

[0010] In some embodiments, the side hole shape in the candidate continuous casting crystallizer parameters includes any one of circular, elliptical, and rectangular shapes.

[0011] In some embodiments, the range of the billet pulling speed in the selected continuous casting crystallizer parameters is 0.8 m / min to 2.2 m / min.

[0012] In some embodiments, the argon flow rate in the parameters of the continuous casting crystallizer to be selected ranges from 5 L / min to 20 L / min.

[0013] This application also provides a device for determining continuous casting crystallizer parameters based on multi-index comprehensive scoring, including: A unit is established to create a three-dimensional model of the continuous casting mold, the three-dimensional model including the continuous casting mold body, the nozzle, the molten steel area, the liquid protective slag area and the air area; The first determining unit is used to determine multiple candidate continuous casting crystallizer parameters; the candidate continuous casting crystallizer parameters include nozzle structure parameters and / or continuous casting process parameters; the nozzle structure parameters include nozzle inner diameter, side hole inclination angle, side hole size, side hole shape, and well depth; the continuous casting process parameters include billet pulling speed, insertion depth, and argon blowing flow rate; The simulation unit is used to import the three-dimensional model into the computational fluid dynamics simulation software, and to perform flow field simulation calculations on each of the selected continuous casting crystallizer parameters to obtain the corresponding simulation results. The simulation results include the instantaneous maximum velocity of the liquid surface, the wave height of the liquid surface, the exposed area of ​​the liquid protective slag, the liquid surface velocity distribution data, and the amount of slag entrainment within a preset time period. The calculation unit is used to calculate index data based on the simulation results corresponding to the parameters of the candidate continuous casting crystallizer; wherein, the index data includes the average instantaneous maximum velocity of the liquid surface, the maximum liquid surface wave height, the average liquid surface wave height, the average exposed area of ​​the liquid protective slag, the area ratio of the target velocity range, and the average amount of slag entrainment. The scoring unit is used to determine the score of each indicator data based on the indicator data corresponding to all candidate continuous casting crystallizer parameters; and to obtain the comprehensive score corresponding to the candidate continuous casting crystallizer parameter by weighted summation of the indicator data corresponding to the candidate continuous casting crystallizer parameter. The second determining unit is used to determine the candidate continuous casting crystallizer parameter corresponding to the highest comprehensive score as the final continuous casting crystallizer parameter.

[0014] By utilizing the above technical solution, this application provides a method and apparatus for determining continuous casting mold parameters based on multi-index comprehensive scoring. This method establishes a three-dimensional model including the mold body, nozzle, molten steel region, liquid protective slag region, and air region. Transient flow field simulations are performed on different nozzle structural parameters and / or continuous casting process parameters to obtain the instantaneous maximum velocity of the liquid surface, liquid surface wave height, exposed area of ​​the liquid protective slag, liquid surface velocity distribution data, and slag entrainment amount within a preset time period. A comprehensive score is calculated based on these results, and the continuous casting mold parameters are determined according to the comprehensive score. This application helps to improve the objectivity of continuous casting mold parameter selection while taking into account both liquid surface activity and interface stability.

[0015] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 An exemplary flowchart illustrates a method for determining continuous casting crystallizer parameters based on a multi-index comprehensive scoring, according to some embodiments. Figure 2 An exemplary schematic diagram of a sprue structure is shown according to some embodiments; Figure 3 A schematic diagram of a sprue side hole provided according to some embodiments is shown as an example; Figure 4 An exemplary schematic diagram of a continuous casting crystallizer parameter determination device based on multi-index comprehensive scoring is shown according to some embodiments. Detailed Implementation

[0017] The present application will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present application can be combined with each other.

[0018] The continuous casting mold is a core piece of equipment in steel continuous casting production. Its main function is to cool and solidify the high-temperature molten steel in the ladle into a billet shell of a certain thickness, while ensuring the internal quality of the billet. Currently, defects such as slag inclusions and surface cracks frequently appear in the billets produced by continuous casting molds, affecting product quality. Therefore, how to improve the product quality of continuous casting molds has become a technical problem that urgently needs to be solved by those skilled in the art.

[0019] Research has shown that the flow state of molten steel, the stability of the liquid surface, and the distribution of protective slag within the crystallizer directly affect the surface quality and internal defects of the cast billet. The tundish, as the channel through which molten steel enters the crystallizer, has structural parameters and associated continuous casting process parameters (such as billet pulling speed and argon blowing flow rate) that are key to determining these factors.

[0020] To address the aforementioned technical problems, this application provides a method and apparatus for determining continuous casting mold parameters based on a multi-index comprehensive scoring system. This method involves establishing a three-dimensional model encompassing the mold body, nozzle, molten steel region, liquid protective slag region, and air region. Transient flow field simulations are performed on different nozzle structural parameters and / or continuous casting process parameters to obtain the instantaneous maximum velocity of the liquid surface, liquid surface wave height, exposed area of ​​the liquid protective slag, liquid surface velocity distribution data, and slag entrainment amount within a preset time period. A comprehensive score is calculated based on these results, and the continuous casting mold parameters are determined according to the comprehensive score. This application helps improve the objectivity of continuous casting mold parameter selection while considering both liquid surface activity and interface stability.

[0021] Figure 1 A flowchart of a method for determining continuous casting mold parameters based on a multi-index comprehensive scoring is provided according to some embodiments. The method includes steps S100-S600.

[0022] S100. Establish a three-dimensional model of the continuous casting mold, the three-dimensional model including the continuous casting mold body, the nozzle, the molten steel area, the liquid protective slag area and the air area.

[0023] In this embodiment, the nozzle is immersed inside the continuous casting mold body, passing through the liquid protective slag region, and the nozzle side hole is located inside the molten steel region. Above the liquid protective slag region is an air region.

[0024] In this embodiment, a full-size 3D model of the continuous casting mold can be established using 3D modeling software. The model precisely includes the mold body, nozzle, molten steel zone, liquid protective slag zone, and air zone. The parameters of the mold body are determined according to the specifications of the continuous casting mold in actual production. The nozzle needs to have interfaces for adjustable parameters such as nozzle inner diameter, side hole inclination angle, side hole size, side hole shape, and well depth. The physical properties of the molten steel and liquid protective slag (such as density, viscosity, and interfacial tension) are set according to the steel grade and protective slag type.

[0025] S200. Determine multiple candidate continuous casting crystallizer parameters; the candidate continuous casting crystallizer parameters include nozzle structure parameters and / or continuous casting process parameters; the nozzle structure parameters include nozzle inner diameter, side hole inclination angle, side hole size, side hole shape, and well depth; the continuous casting process parameters include billet pulling speed, insertion depth, and argon blowing flow rate.

[0026] In this embodiment, multiple different candidate continuous casting mold parameters are preset, and then simulations are performed on the different candidate continuous casting mold parameters to obtain the corresponding simulation results. Based on all the simulation results, the optimal candidate continuous casting mold parameter is selected as the final continuous casting mold parameter.

[0027] Since both the nozzle structure parameters and the continuous casting process parameters affect the performance of the continuous casting crystallizer, the candidate continuous casting crystallizer parameters in the embodiments of this application can simultaneously include nozzle structure parameters and continuous casting process parameters.

[0028] Figure 2 An exemplary schematic diagram of a water inlet structure according to some embodiments is shown. The water inlet structure parameters 1 are parameters used to set the water inlet, and may include the water inlet inner diameter w, the side hole inclination angle β of the side hole 5, the side hole size, the side hole shape, and the well depth m. Figure 2 and Figure 3 In this design, the side hole is rectangular in shape, and its size includes the width L and height d. Figure 2 The diagram also shows liquid protective slag 2, molten steel 3, and air 4. The continuous casting process is the actual operation process when using a tundish nozzle, which may include billet pulling speed, insertion depth h, and argon blowing flow rate.

[0029] In some embodiments, the range of the nozzle inner diameter in the selected continuous casting crystallizer parameters is 50 mm - 85 mm.

[0030] In some embodiments, the side hole inclination angle in the selected continuous casting crystallizer parameters ranges from 15° to 45°.

[0031] In some embodiments, the side hole shape in the candidate continuous casting crystallizer parameters includes any one of circular, elliptical, and rectangular shapes.

[0032] In some embodiments, the width of the side hole includes 65mm, 70mm, or 75mm.

[0033] In some embodiments, the height of the side hole includes 80 mm, 85 mm, 90 mm, or 100 mm.

[0034] In some embodiments, the well depth includes 15 mm, 20 mm, or 30 mm.

[0035] In some embodiments, the range of the billet pulling speed in the selected continuous casting crystallizer parameters is 0.8 m / min to 2.2 m / min.

[0036] In some embodiments, the argon flow rate in the parameters of the continuous casting crystallizer to be selected ranges from 5 L / min to 20 L / min.

[0037] In some embodiments, the insertion depth may be 150 mm, 160 mm, or 170 mm.

[0038] In some embodiments, the ranges of the nozzle inner diameter, the side hole inclination angle, the side hole size, the side hole shape, the well depth, the billet pulling speed, the insertion depth, and the argon blowing flow rate are determined jointly based on the actual production window of the continuous casting machine, historical process experience, and the simulated feasible domain; multiple candidate continuous casting crystallizer parameter combinations are selected within the ranges to ensure that the evaluation results have engineering applicability.

[0039] S300. Import the three-dimensional model into the computational fluid dynamics simulation software, and perform flow field simulation calculations on each of the selected continuous casting crystallizer parameters to obtain the corresponding simulation results. The simulation results include the instantaneous maximum velocity of the liquid surface, the wave height of the liquid surface, the exposed area of ​​the liquid protective slag, the liquid surface velocity distribution data, and the amount of slag entrainment within a preset time period.

[0040] In this embodiment of the application, the fluid dynamics simulation software (e.g., CFD) uses computational fluid dynamics to perform flow field simulation calculations on the parameters of the selected continuous casting mold. During the simulation, the interfacial tension between molten steel and protective slag, the interfacial tension between molten steel and air, and the interfacial tension between protective slag and air need to be considered.

[0041] During the simulation, a multiphase flow model needs to be enabled to distinguish between the molten steel, the protective slag phase, and the gas phase. Appropriate boundary conditions should be set (e.g., velocity inlet boundary, free flow outlet for side holes, and no-slip boundary for the mold wall), and the effects of molten steel flow inertia, heat exchange, and interfacial tension should be considered. After the simulation, the instantaneous maximum velocity of the liquid surface, the wave height, the exposed area of ​​the liquid protective slag, the velocity distribution of the liquid surface, and the amount of slag entrainment are extracted from the parameters of the selected continuous casting mold.

[0042] In some embodiments, the flow field simulation is a transient multiphase flow simulation; a velocity inlet boundary condition is set at the inlet, a free outflow boundary condition is set at the bottom outlet, both the wide and narrow faces are no-slip walls, and a pressure outlet boundary condition is set at the top. Bubble motion is tracked and solved using a discrete phase model (DPM), with the bubbles set to be captured by liquid slag (liquid protective slag) (air phase volume fraction greater than 0.3%). To more accurately capture the surface fluctuation characteristics, mesh refinement is performed at the steel-slag interface. Molten steel, liquid slag, and air are solved using a VOF model, while argon bubble motion is tracked and solved using a DPM model, with the bubbles set to be captured by liquid slag (air phase volume fraction greater than 0.3%). Computational integration is performed using the commercial Fluent software. The time step is set to 0.0001 s, and the computational mesh is determined through mesh independence verification; after the flow field reaches statistical stability, the last 10 s is selected as the preset time period.

[0043] In this embodiment of the application, the reason for using the instantaneous maximum velocity of the liquid surface, the wave height of the liquid surface, the exposed area of ​​the liquid protective slag, the liquid surface velocity distribution data, and the amount of slag entrainment within a preset time period to subsequently select appropriate candidate continuous casting mold parameters as the final continuous casting mold parameters is as follows: The flow behavior of molten steel in the continuous casting mold significantly affects the slag-metal interface behavior, and the design of the nozzle is a key factor in optimizing the flow of molten steel in the mold.

[0044] In actual production, the occasional instantaneous maximum velocity of the liquid surface has a direct impact on the secondary oxidation of slag and molten steel. Therefore, it is necessary to keep the instantaneous maximum velocity of the liquid surface as small as possible to avoid slag entrapment and secondary oxidation.

[0045] The height of the liquid surface reflects the fluctuation of the liquid surface. A higher height of the liquid surface can easily cause the protective slag to be drawn in. Therefore, it is necessary to ensure that the height of the liquid surface is within a reasonable range, and the lower the height of the liquid surface, the better.

[0046] Liquid protective slag plays a role in isolating air, lubricating the billet, and uniformly transferring heat during continuous casting. If the exposed area of ​​liquid protective slag is too large, it will lead to secondary oxidation of the molten steel and the formation of oxide inclusions. Therefore, the exposed area of ​​liquid protective slag should be kept as small as possible.

[0047] Liquid surface velocity distribution data can reflect the velocity distribution of molten steel. If the liquid surface velocity is too low, the protective slag will not spread evenly, which is not conducive to the melting and lubrication of the protective slag. If the velocity is too high, it will aggravate the entrapment of the protective slag.

[0048] Excessive slag inclusions can lead to defects such as slag inclusions and surface cracks in the cast billet, affecting product quality.

[0049] S400. Based on the simulation results corresponding to the parameters of the candidate continuous casting crystallizer, calculate the index data; wherein, the index data includes the average instantaneous maximum velocity of the liquid surface, the maximum liquid surface wave height, the average liquid surface wave height, the average exposed area of ​​the liquid protective slag, the area ratio of the target velocity range, and the average amount of slag entrainment.

[0050] In this embodiment, the continuous casting mold parameters are not determined solely based on a single flow field index. Instead, the liquid surface activity evaluation index, interface stability evaluation index, and slag entrainment risk rating index are introduced simultaneously. These include the average instantaneous maximum liquid surface velocity, maximum liquid surface wave height, average liquid surface wave height, average exposed area of ​​liquid protective slag, liquid surface velocity distribution, and average slag entrainment amount. The continuous casting mold parameters are determined through a multi-index data joint evaluation method, thereby avoiding parameter imbalance problems caused by single index data optimization.

[0051] In some embodiments, the step of calculating index data based on the simulation results corresponding to the parameters of the candidate continuous casting crystallizer includes: Calculate the time average of the instantaneous maximum velocity of the liquid surface at each moment within the preset time period in the simulation results, and use it as the average instantaneous maximum velocity of the liquid surface.

[0052] From the liquid surface wave heights within the preset time period, the liquid surface wave height with the largest offset relative to the initial liquid surface is selected as the maximum liquid surface wave height.

[0053] The time average of the absolute values ​​of the liquid surface wave height within the preset time period is calculated as the average liquid surface wave height.

[0054] The average time-average area of ​​the exposed liquid protective slag within the preset time period is calculated as the average exposed area of ​​the liquid protective slag.

[0055] In this embodiment, the exposed area of ​​the liquid protective slag is the area of ​​the interface between the molten steel and the air. The average time ratio of the area within the target speed range in the liquid surface velocity distribution data within the preset time period to the total liquid surface area is calculated as the target speed range area ratio; wherein, the minimum value of the target speed range is a first preset speed, the maximum value is a second preset speed, and the second preset speed is a preset critical slag entrainment speed.

[0056] In this embodiment, the first preset speed can be 0.1 m / s, which is used to characterize the minimum liquid surface velocity threshold at which the protective slag can stably spread and renew; the second preset speed is a preset critical slag entrapment speed, which is calculated based on the steel liquid density, protective slag density, steel-slag interfacial tension and local interfacial morphology parameters, or calibrated based on historical production data corresponding to the target steel grade.

[0057] Calculate the time average of the amount of slag carried over the preset time period as the average amount of slag carried.

[0058] In this embodiment of the application, the amount of slag entrainment is the volume of liquid protective slag entrained in the molten steel region.

[0059] S500. Based on the index data corresponding to all candidate continuous casting crystallizer parameters, determine the score of each index data; weight and sum the scores of the index data corresponding to the candidate continuous casting crystallizer parameters to obtain the comprehensive score corresponding to the candidate continuous casting crystallizer parameters.

[0060] In some embodiments, the step of determining the score of each index data based on the index data corresponding to all candidate continuous casting crystallizer parameters includes: Based on the index data corresponding to all candidate continuous casting crystallizer parameters, determine the optimal and worst values ​​of each index data; The score corresponding to the indicator data is determined by a linear mapping rule; wherein the optimal value of the indicator data is mapped to a first preset score, and the worst value of the indicator data is mapped to a second preset score; the first preset score is higher than the second preset score.

[0061] In one example, the first preset score can be 100 points, and the second preset score can be 0 points.

[0062] In some embodiments, the linear mapping rule can be expressed by the following formula: For indicators where smaller is better, ; For indicators where larger is always better ; Where S is the score corresponding to the indicator; To be the optimal value, This is the worst value; As an indicator.

[0063] In some embodiments, if the best value and the worst value are equal, the indicator data is determined to be a preset score.

[0064] In some embodiments, the step of determining the optimal and worst values ​​of each index data based on the index data corresponding to all candidate continuous casting crystallizer parameters includes: The smallest of all the instantaneous maximum average liquid surface velocities is determined as the optimal value of the instantaneous maximum liquid surface velocity; the largest of all the instantaneous maximum average liquid surface velocities is determined as the worst value of the instantaneous maximum liquid surface velocity.

[0065] In this embodiment of the application, since a smaller instantaneous maximum velocity of the liquid surface can avoid secondary oxidation of the slag and the liquid surface, the maximum instantaneous maximum velocity of the average liquid surface is determined as the worst value, and the opposite is the optimal value.

[0066] Among all the maximum liquid surface wave heights, the smallest maximum liquid surface wave height is determined as the optimal value of the maximum liquid surface wave height; among all the maximum liquid surface wave heights, the largest maximum liquid surface wave height is determined as the worst value of the maximum liquid surface wave height.

[0067] Among all the average liquid surface wave heights, the smallest average liquid surface wave height is determined as the optimal value of the average liquid surface wave height; among all the average liquid surface wave heights, the largest average liquid surface wave height is determined as the worst value of the average liquid surface wave height.

[0068] In this embodiment of the application, since a higher liquid surface wave height can easily cause the protective slag to be entrained, the maximum liquid surface wave height and the average liquid surface wave height are determined to be the worst value, and the opposite is the optimal value.

[0069] The smallest average exposed area of ​​the liquid protective slag among all the average exposed areas is determined as the optimal value of the average exposed area of ​​the liquid protective slag; the largest average exposed area of ​​the liquid protective slag among all the average exposed areas of the liquid protective slag is determined as the worst value of the average exposed area of ​​the liquid protective slag.

[0070] In this embodiment, since an excessively large exposed area of ​​the liquid protective slag will cause secondary oxidation of the molten steel and generate oxide inclusions, the largest exposed area of ​​the liquid protective slag is determined as the worst value, and the opposite is the optimal value.

[0071] The largest target speed interval area ratio among all the target speed interval area ratios is determined as the optimal value of the target speed interval area ratio; the smallest target speed interval area ratio among all the target speed interval area ratios is determined as the worst value of the target speed interval area ratio.

[0072] In this embodiment, the liquid surface velocity distribution data reflects the liquid surface velocity distribution of the molten steel. Too low a liquid surface velocity will prevent the protective slag from spreading evenly, which is detrimental to its melting and lubrication capabilities; too high a velocity will exacerbate the entrapment of the protective slag. Therefore, the maximum liquid surface velocity distribution is determined as the optimal value, and the opposite is the worst value.

[0073] The minimum average slag amount among all the average slag amounts is determined as the optimal value of the average slag amount; the maximum average slag amount among all the average slag amounts is determined as the worst value of the average slag amount.

[0074] In this embodiment of the application, since excessive slag entrainment can lead to defects such as slag inclusions and surface cracks in the billet, affecting product quality, the maximum average slag entrainment is determined as the worst value, and vice versa as the optimal value.

[0075] In this embodiment, different parameters in the simulation results have different effects on product performance, therefore different weights are set. In this embodiment, the weights, from high to low, are average slag amount, average exposed area of ​​liquid protective slag, maximum liquid surface wave height, average instantaneous maximum liquid surface velocity, and the area ratio of the target velocity range; the maximum liquid surface wave height and the average liquid surface wave height have the same weight.

[0076] For example, the weight corresponding to the average amount of slag is 0.35, the weight corresponding to the average exposed area of ​​liquid protective slag is 0.2, the weight corresponding to the maximum liquid surface wave height is 0.15, the weight corresponding to the average liquid surface wave height is 0.15, the weight corresponding to the average instantaneous maximum speed of the liquid surface is 0.1, and the weight corresponding to the area ratio of the target speed range is 0.05.

[0077] The comprehensive score is obtained by weighting and summing all the scores: score corresponding to the amount of slag rolled up × 0.35 + score corresponding to the exposed area of ​​liquid protective slag × 0.2 + score corresponding to the maximum liquid surface wave height × 0.15 + score corresponding to the average liquid surface wave height × 0.15 + score corresponding to the instantaneous maximum liquid surface velocity × 0.1 + score corresponding to the liquid surface velocity distribution data × 0.05.

[0078] S600. The candidate continuous casting crystallizer parameter corresponding to the highest comprehensive score is determined as the final continuous casting crystallizer parameter.

[0079] In this embodiment of the application, after the final continuous casting crystallizer parameters are applied to actual continuous casting production, the liquid level velocity, protective slag distribution, liquid level wave height and slag inclusions in the billet can be monitored in real time through liquid level monitoring devices, temperature sensors and sampling analysis on the crystallizer.

[0080] In one example, the billet pulling speed is 1.8 m / min, the argon gas flow rate is 6 NL / min, the side hole width is 70 mm, the side hole height is 85 mm, the well depth is 30 mm, and the insertion depth is 170 mm. This effectively optimizes the flow field inside the crystallizer and reduces exposed protective slag and slag entrapment.

[0081] The method in this application embodiment has the following advantages: 1. A multi-parameter comprehensive evaluation criterion is adopted (including the average instantaneous maximum velocity of the liquid surface, the maximum liquid surface wave height, the average liquid surface wave height, the average exposed area of ​​the liquid protective slag, the area ratio of the target velocity range, and the average slag entrainment). By simultaneously focusing on these parameters, a comprehensive assessment of the crystallizer's operating status is achieved. The optimized scheme can simultaneously meet the requirements of a stable flow field, stable liquid surface, good protective slag coverage, and low slag entrainment, significantly reducing the defect rate of slag inclusions and surface cracks in the cast billet.

[0082] 2. The quantitative standards (scores) of each evaluation parameter have been clarified, which has improved the accuracy and operability of the optimization design, made the scheme selection more objective, and avoided the error of human judgment.

[0083] 3. The optimized nozzle structure parameters and continuous casting process parameters can effectively improve the stability of continuous casting production. By controlling the liquid surface velocity within a reasonable range, the uniform spreading of the protective slag is ensured, while avoiding liquid surface fluctuations caused by excessive velocity. At the same time, the amount of exposed protective slag and slag entrapment is reduced, the risk of secondary oxidation of molten steel is lowered, and the surface and internal quality of the billet are improved. Practical application verification shows that the billet qualification rate can be increased by 3%-5%.

[0084] 4. The method has strong versatility and the parameter thresholds can be adjusted according to different steel grades (such as low carbon steel and alloy steel) and crystallizer specifications. It is applicable to a variety of continuous casting production scenarios and has a wide range of applications.

[0085] Figure 4 An exemplary schematic diagram is shown of a continuous casting crystallizer parameter determination device based on multi-index comprehensive scoring, according to some embodiments. The device includes: Unit 401 is used to create a three-dimensional model of the continuous casting mold, the three-dimensional model including the continuous casting mold body, the nozzle, the molten steel area, the liquid protective slag area and the air area; The first determining unit 402 is used to determine multiple candidate continuous casting crystallizer parameters; the candidate continuous casting crystallizer parameters include nozzle structure parameters and / or continuous casting process parameters; the nozzle structure parameters include nozzle inner diameter, side hole inclination angle, side hole size, side hole shape, and well depth; the continuous casting process parameters include billet pulling speed, insertion depth, and argon blowing flow rate; The simulation unit 403 is used to import the three-dimensional model into the computational fluid dynamics simulation software, and to perform flow field simulation calculations on each of the selected continuous casting crystallizer parameters to obtain the corresponding simulation results. The simulation results include the instantaneous maximum velocity of the liquid surface, the wave height of the liquid surface, the exposed area of ​​the liquid protective slag, the liquid surface velocity distribution data, and the amount of slag entrainment within a preset time period. The calculation unit 404 is used to calculate index data based on the simulation results corresponding to the parameters of the candidate continuous casting crystallizer; wherein, the index data includes the average instantaneous maximum velocity of the liquid surface, the maximum liquid surface wave height, the average liquid surface wave height, the average exposed area of ​​the liquid protective slag, the area ratio of the target velocity range, and the average amount of slag entrainment. The scoring unit 405 is used to determine the score of each indicator data based on the indicator data corresponding to all the candidate continuous casting crystallizer parameters; and to add the scores of the indicator data corresponding to the candidate continuous casting crystallizer parameters in a weighted manner to obtain the comprehensive score corresponding to the candidate continuous casting crystallizer parameters. The second determining unit 406 is used to determine the candidate continuous casting crystallizer parameter corresponding to the highest comprehensive score as the final continuous casting crystallizer parameter.

[0086] By utilizing the above technical solution, this application provides a method and apparatus for determining continuous casting mold parameters based on multi-index comprehensive scoring. This method establishes a three-dimensional model including the mold body, nozzle, molten steel region, liquid protective slag region, and air region. Transient flow field simulations are performed on different nozzle structural parameters and / or continuous casting process parameters to obtain the instantaneous maximum velocity of the liquid surface, liquid surface wave height, exposed area of ​​the liquid protective slag, liquid surface velocity distribution data, and slag entrainment amount within a preset time period. A comprehensive score is calculated based on these results, and the continuous casting mold parameters are determined according to the comprehensive score. This application helps to improve the objectivity of continuous casting mold parameter selection while taking into account both liquid surface activity and interface stability.

[0087] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for determining continuous casting mold parameters based on multi-index comprehensive scoring, characterized in that, include: A three-dimensional model of the continuous casting crystallizer is established, which includes the continuous casting crystallizer body, nozzle, molten steel zone, liquid protective slag zone and air zone; Multiple candidate continuous casting crystallizer parameters are determined; the candidate continuous casting crystallizer parameters include nozzle structure parameters and / or continuous casting process parameters; the nozzle structure parameters include nozzle inner diameter, side hole inclination angle, side hole size, side hole shape, and well depth; the continuous casting process parameters include billet pulling speed, insertion depth, and argon blowing flow rate; The three-dimensional model is imported into the computational fluid dynamics simulation software, and flow field simulation calculations are performed on each of the selected continuous casting crystallizer parameters to obtain the corresponding simulation results. The simulation results include the instantaneous maximum velocity of the liquid surface, the wave height of the liquid surface, the exposed area of ​​the liquid protective slag, the liquid surface velocity distribution data, and the amount of slag entrainment within a preset time period. Based on the simulation results corresponding to the parameters of the candidate continuous casting mold, index data are calculated; wherein, the index data includes the average instantaneous maximum velocity of the liquid surface, the maximum liquid surface wave height, the average liquid surface wave height, the average exposed area of ​​the liquid protective slag, the area ratio of the target velocity range, and the average slag entrainment amount; the step of calculating the index data based on the simulation results corresponding to the parameters of the candidate continuous casting mold includes: calculating the time average of the instantaneous maximum velocity of the liquid surface at each moment within the preset time period in the simulation results, as the average instantaneous maximum velocity of the liquid surface; and selecting the liquid surface wave height with the largest offset relative to the initial liquid surface from the liquid surface wave heights within the preset time period. The maximum liquid surface wave height is calculated as follows: the time average of the absolute values ​​of the liquid surface wave heights within the preset time period is used as the average liquid surface wave height; the time average of the exposed area of ​​the liquid protective slag within the preset time period is used as the average exposed area of ​​the liquid protective slag; the time average proportion of the area within the target speed range in the liquid surface velocity distribution data within the preset time period to the total liquid surface area is calculated as the liquid surface velocity distribution; wherein, the minimum value of the target speed range is the first preset speed, the maximum value is the second preset speed, and the second preset speed is the preset critical slag entrainment speed; the time average of the slag entrainment amount within the preset time period is used as the average slag entrainment amount; Based on the index data corresponding to all the candidate continuous casting crystallizer parameters, the score of each index data is determined; the scores of the index data corresponding to the candidate continuous casting crystallizer parameters are weighted and summed to obtain the comprehensive score corresponding to the candidate continuous casting crystallizer parameters. The candidate continuous casting crystallizer parameters corresponding to the highest comprehensive score are determined as the final continuous casting crystallizer parameters.

2. The method for determining continuous casting mold parameters based on multi-index comprehensive scoring according to claim 1, characterized in that, The step of determining the score of each index data based on the index data corresponding to all candidate continuous casting crystallizer parameters includes: Based on the index data corresponding to all candidate continuous casting crystallizer parameters, determine the optimal and worst values ​​of each index data; The score corresponding to the indicator data is determined by a linear mapping rule; wherein the optimal value of the indicator data is mapped to a first preset score, and the worst value of the indicator data is mapped to a second preset score; the first preset score is higher than the second preset score.

3. The method for determining continuous casting mold parameters based on multi-index comprehensive scoring according to claim 2, characterized in that, The step of determining the optimal and worst values ​​of each index data point based on the index data corresponding to all candidate continuous casting crystallizer parameters includes: The smallest of all the instantaneous maximum velocities of the average liquid surface is determined as the optimal value of the instantaneous maximum velocities of the liquid surface; the largest of all the instantaneous maximum velocities of the average liquid surface is determined as the worst value of the instantaneous maximum velocities of the liquid surface. Among all the maximum liquid surface wave heights, the smallest maximum liquid surface wave height is determined as the optimal value of the maximum liquid surface wave height; among all the maximum liquid surface wave heights, the largest maximum liquid surface wave height is determined as the worst value of the maximum liquid surface wave height. Among all the average liquid surface wave heights, the smallest average liquid surface wave height is determined as the optimal value of the average liquid surface wave height; among all the average liquid surface wave heights, the largest average liquid surface wave height is determined as the worst value of the average liquid surface wave height. The smallest average exposed area of ​​the liquid protective slag among all the average exposed areas is determined as the optimal value of the average exposed area of ​​the liquid protective slag; the largest average exposed area of ​​the liquid protective slag among all the average exposed areas of the liquid protective slag is determined as the worst value of the average exposed area of ​​the liquid protective slag. The largest target speed interval area ratio among all the target speed interval area ratios is determined as the optimal value of the target speed interval area ratio; the smallest target speed interval area ratio among all the target speed interval area ratios is determined as the worst value of the target speed interval area ratio. The minimum average slag amount among all the average slag amounts is determined as the optimal value of the average slag amount; the maximum average slag amount among all the average slag amounts is determined as the worst value of the average slag amount.

4. The method for determining continuous casting mold parameters based on multi-index comprehensive scoring according to claim 1, characterized in that, The range of the nozzle inner diameter in the parameters of the selected continuous casting crystallizer is 50 mm - 85 mm.

5. The method for determining continuous casting mold parameters based on multi-index comprehensive scoring according to claim 1, characterized in that, The range of the side hole inclination angle in the parameters of the selected continuous casting crystallizer is 15°-45°.

6. The method for determining continuous casting mold parameters based on multi-index comprehensive scoring according to claim 1, characterized in that, The side hole shape in the parameters of the continuous casting crystallizer to be selected includes any one of circular, elliptical and rectangular shapes.

7. The method for determining continuous casting mold parameters based on multi-index comprehensive scoring according to claim 1, characterized in that, The range of billet pulling speed in the parameters of the candidate continuous casting crystallizer is 0.8 m / min - 2.2 m / min.

8. The method for determining continuous casting mold parameters based on multi-index comprehensive scoring according to claim 1, characterized in that, The range of argon flow rate in the parameters of the candidate continuous casting crystallizer is 5 L / min - 20 L / min.

9. A device for determining continuous casting mold parameters based on multi-index comprehensive scoring, characterized in that, include: A unit is established to create a three-dimensional model of the continuous casting mold, the three-dimensional model including the continuous casting mold body, the nozzle, the molten steel area, the liquid protective slag area and the air area; The first determining unit is used to determine multiple candidate continuous casting crystallizer parameters; the candidate continuous casting crystallizer parameters include nozzle structure parameters and / or continuous casting process parameters; the nozzle structure parameters include nozzle inner diameter, side hole inclination angle, side hole size, side hole shape, and well depth; the continuous casting process parameters include billet pulling speed, insertion depth, and argon blowing flow rate; The simulation unit is used to import the three-dimensional model into the computational fluid dynamics simulation software, and to perform flow field simulation calculations on each of the selected continuous casting crystallizer parameters to obtain the corresponding simulation results. The simulation results include the instantaneous maximum velocity of the liquid surface, the wave height of the liquid surface, the exposed area of ​​the liquid protective slag, the liquid surface velocity distribution data, and the amount of slag entrainment within a preset time period. The calculation unit is used to calculate index data based on the simulation results corresponding to the parameters of the candidate continuous casting crystallizer; wherein, the index data includes the average instantaneous maximum velocity of the liquid surface, the maximum liquid surface wave height, the average liquid surface wave height, the average exposed area of ​​the liquid protective slag, the area ratio of the target velocity range, and the average amount of slag entrainment; the calculation unit is specifically used to: calculate the time average of the instantaneous maximum velocity of the liquid surface at each moment within the preset time period in the simulation results, as the average instantaneous maximum velocity of the liquid surface; and select the liquid surface wave height with the largest offset relative to the initial liquid surface from the liquid surface wave height within the preset time period, as the maximum liquid surface wave height; The time average of the absolute values ​​of the liquid surface wave height within the preset time period is calculated as the average liquid surface wave height; the time average of the exposed area of ​​the liquid protective slag within the preset time period is calculated as the average exposed area of ​​the liquid protective slag; the time average proportion of the area within the target speed range in the liquid surface velocity distribution data within the preset time period to the total liquid surface area is calculated as the liquid surface velocity distribution; wherein, the minimum value of the target speed range is a first preset speed, the maximum value is a second preset speed, and the second preset speed is a preset critical slag entrainment speed; the time average of the slag entrainment amount within the preset time period is calculated as the average slag entrainment amount; The scoring unit is used to determine the score of each indicator data based on the indicator data corresponding to all candidate continuous casting crystallizer parameters; and to obtain the comprehensive score corresponding to the candidate continuous casting crystallizer parameter by weighted summation of the indicator data corresponding to the candidate continuous casting crystallizer parameter. The second determining unit is used to determine the candidate continuous casting crystallizer parameter corresponding to the highest comprehensive score as the final continuous casting crystallizer parameter.

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