Steel ladle refining monitoring method based on vibration measurement

Abstract

The invention discloses a steel ladle refining monitoring method based on vibration measurement, which is characterized in that at least two vibration sensors and at least one flow sensor are respectively arranged at positions symmetrical to a steel ladle distance angle to monitor the flow of blowing gas in real time, and at least one valve is arranged on a blowing pipeline and is used for controlling on and off of gas and / or controlling the flow of the gas; judging whether the steel ladle is uniformly stirred or not according to the vibration information: if the steel ladle is uniformly stirred, controlling an air blowing valve to stop supplying air, if the steel ladle is not uniformly stirred, maintaining the current situation and continuously stirring until the steel ladle is uniformly stirred, and if the stirring time exceeds the preset longest stirring time, actively stopping stirring and manually checking the stirring effect. The method is simple and easy to implement, compared with manual experience, the flow speed and experience time are more reliable, redundant stirring or insufficient stirring is avoided, the automation degree is higher, efficiency is higher, ladle refining control is facilitated, the manual workload can be reduced, dependence on field personnel experience is reduced, and the rejection rate of refined products can also be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of steel smelting and control, and particularly relates to a ladle refining monitoring method based on vibration measurement. Background Art

[0002] The ladle degassing refining method is the main method of secondary steelmaking (also known as secondary steelmaking, which is simply referred to as ladle refining in the present invention), that is, the molten steel smelted in a rough smelting furnace (electric furnace and converter) is transferred to another high-temperature container (mainly a ladle) for refining. Its main classifications are: (1) ladle treatment type: such as ladle argon blowing, ladle powder injection, and vacuum circulation degassing (RH); (2) ladle refining type, such as vacuum oxygen decarburization (VOD), argon oxygen decarburization (AOD), ladle refining (LF, ASEA-CKF, VAD, etc.). Gas stirring is used to improve the mixing effect and promote chemical reactions, and the control of gas intensity (or flow rate, flow velocity) and time has a great impact on the entire process.

[0003] Since the ladle refining process is in a high-temperature state, it is difficult for general video image detection to obtain an image that effectively reflects the stirring effect at high temperature. Of course, even if a field image can be obtained, it is very difficult to extract the stirring effect information. At present, there is still a lack of effective monitoring means and methods in the ladle refining process. Mainly based on on-site operation experience, manual judgment is used to determine whether the stirring is uniform. In fact, most of the time, the stirring effect is ensured by experiencing sufficient stirring time at the empirical stirring intensity. That is to say, there is an over-stirring state most of the time, and the refining efficiency is difficult to improve. The requirements for manual observation are high, and once unqualified products are found during post-detection, it will cause relatively large losses. All the products cast in the whole ladle (furnace) may become waste products. There is an urgent need for a convenient and effective refining monitoring method for ladle degassing refining. Summary of the Invention

[0004] By collecting and analyzing the vibration information of symmetrically installed vibration sensors, the present invention reasonably characterizes the gas stirring state during ladle refining by using vibration characteristic values, and realizes real-time control of the blowing gas flow rate and valve shut-off through effective monitoring of the ladle refining process, thereby improving the ladle refining efficiency and automation level.

[0005] To achieve the above object, the present invention designs a ladle refining monitoring method based on vibration measurement. According to at least two vibration sensors symmetrically arranged in terms of distance and angle, the ladle stirring vibration information is monitored in real time. At least one flow (also known as flow velocity or intensity) sensor monitors the blowing gas flow information in real time. At least one valve is arranged on the blowing gas pipeline for automatically controlling the shut-off and opening of the gas and / or controlling the gas flow rate. According to the vibration information, it is judged whether the ladle is stirred evenly, and then the valve operation is controlled; If the stirring is already uniform, control the blowing valve to stop supplying gas, and the ladle refining enters the next process; If the stirring is not yet uniform, maintain the current state and continue stirring until it becomes uniform; If the stirring exceeds the preset maximum stirring time, actively stop stirring and manually check the stirring effect; The method for judging whether the ladle is stirred evenly based on vibration information includes a monitoring method: The vibration amounts of vibration sensors symmetrically installed within the acquisition window duration (also known as the window time) 、 …, extract the first eigenvalue corresponding to the vibration amount 、 … and the second eigenvalue 、 …, where is the sampling serial number, the sampling period is determined according to the vibration frequency, the characteristics of the sensor, and the data acquisition instrument (data acquisition box) itself. The first subscript of the vibration amount and the eigenvalue identifies the vibration sensor number. The monitoring method includes Monitoring Method 1 or Monitoring Method 2; The Monitoring Method 1 includes that if all within the window duration, j ≠ k (such as ), then it is considered that the ladle stirring is uniform; otherwise, stirring needs to continue, where is the first threshold; The Monitoring Method 2 includes that if all within the window duration, j ≠ k (such as ), and all are satisfied (such as and etc.), then it is considered that the ladle stirring is uniform; otherwise, stirring needs to continue, where is the second threshold.

[0006] Furthermore, the monitoring method further includes: If the stirring is not yet uniform and the stirring intensity is insufficient, change the blowing gas flow rate according to the gas stirring control rule to adjust the stirring intensity; The gas stirring control rule includes: Simultaneously monitor the blowing gas flow rate (also known as the flow velocity or intensity, and the working gas is generally argon) and the vibration amount in real time, and calculate the ladle response value (LRV) within the window duration as the third eigenvalue 、 … , the ladle response value is the ratio of the area under the vibration amount - time curve to the area under the flow rate - time curve (or the ratio of the integral of the vibration amount with respect to time to the integral of the flow rate with respect to time within the window duration). The average value of the ladle response values of symmetrically installed vibration sensors can also be used as the third eigenvalue of the stirring state of the ladle within the window duration; According to the pre-calibrated ladle response value curve (i.e., the blowing intensity - vibration signal curve), obtain the nominal value of the strongest vibration signal intensity corresponding to the measured blowing gas flow rate. , if within the window duration , and any is satisfied, then it is considered that this blowing and stirring has reached the optimal state and the stirring is uniform. Among them, is the third threshold, is the fourth threshold; if any , then control the change of the blowing gas flow rate according to , where is the change amount of the blowing gas flow rate (or called increment, note that the total flow rate after the gas flow rate increases should be controlled within the allowable flow rate range), is the average value of the third eigenvalue of all symmetrically installed vibration sensors, is the proportionality coefficient.

[0007] Further, the monitoring method further includes a flow rate grading combined stirring method. The flow rate grading distinguishes at least two levels of large flow rate and small flow rate. The flow rate grading combined stirring method includes: The two-stage flow rate combined stirring method. First, use large flow rate blowing and stirring until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met; then use small flow rate blowing and stirring until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met; Or, the three-stage flow rate combined stirring method. First, use large flow rate blowing and stirring until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met; then use medium flow rate blowing and stirring until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met; finally, use small flow rate blowing and stirring until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met; Different flow rates and different monitoring methods correspond to their respective monitoring thresholds (i.e., corresponding to different first to fourth thresholds).

[0008] Further, in the two-stage flow rate combined stirring method, the two-stage flow rates can be set according to the ratio relationship of 2:1, 3:1, 4:1 or 5:1. In the three-stage flow rate combined stirring method, the three-stage flow rates can be set according to the ratio relationship of 4:2:1, 5:3:1, 6:3:1 or 8:4:1.

[0009] Further, the vibration quantity includes at least one of displacement, velocity or acceleration in at least one direction among the three directions of x, y, z (x and y are two horizontal directions, and z is the vertical direction) (such as the acceleration in the x direction). Generally, the vibration sensor measures acceleration, and the velocity is obtained after acceleration integration, and the displacement is obtained after velocity integration.

[0010] Further, the first eigenvalue includes at least one of mean, median, and norm; the second eigenvalue includes at least one of variance (RMS, root mean square value), standard deviation, maximum value, minimum value, and extreme difference, where the extreme difference is the difference between the maximum value and the minimum value.

[0011] Further, the lower limit of the window duration is not less than 3 times the longest vibration period duration, and the upper limit is not greater than the minimum lag duration.

[0012] Further, the window duration includes 10s, 21s, or 40s.

[0013] Further, the symmetry includes 180-degree symmetry (2 vibration sensors), 90-degree symmetry (4 vibration sensors), and 60-degree symmetry (6 vibration sensors) with the central axis of the ladle as the axis of symmetry, where equal-distance symmetry relative to the axis of symmetry is the default.

[0014] Further, the monitoring method includes the sliding window monitoring method, that is, the window slides once per unit time, and the unit time is the window sliding time interval. The vibration quantity and its eigenvalues within the sliding window duration are analyzed and judged according to Monitoring Method 1 or Monitoring Method 2.

[0015] Further, the window sliding time interval includes an integer number of seconds (such as every 1 second or every 2 seconds, etc.) or a unit time greater than or equal to the longest vibration period or greater than or equal to an integer multiple of the sampling period.

[0016] Further, the first threshold, the second threshold, the third threshold, and the fourth threshold all include the quasi-dynamic threshold, and the nominal value includes the quasi-dynamic nominal value. The method for determining the quasi-dynamic threshold and the quasi-dynamic nominal value is as follows: when it is determined that the stirring time with a constant blowing flow rate exceeds the maximum value of the empirical duration, and the first eigenvalue, the second eigenvalue, or the third eigenvalue cannot meet the requirements of the corresponding Judgment Method 1, Judgment Method 2, or Judgment Method 3, the measured calculated value is used as the quasi-dynamic threshold or the quasi-dynamic nominal value of the corresponding threshold.

[0017] The advantages and beneficial effects of the present invention are as follows: The ladle refining monitoring method based on vibration measurement proposed by the present invention has applied the vibration monitoring in the ladle refining process from theory to practice. Through the analysis of the vibration quantity characteristics of symmetrically arranged vibration sensors, it can timely and accurately judge whether the gas stirring in the ladle refining process is uniform, that is, whether the stirring effect is achieved, and control the blowing flow rate and / or the cut-off of the blowing valve according to the judgment result; it is more reliable than manually using empirical flow rates and empirical times, avoiding excessive stirring or insufficient stirring, with higher efficiency, and is beneficial to the control of ladle refining; the acquisition of empirical parameters is more convenient, without excessive theoretical analysis and complex experiments, and the corresponding threshold parameter empirical values can be obtained in the normal stirring state. The application of the present invention can improve the stirring efficiency and automation degree of ladle refining, reduce the manual workload, reduce the dependence on the experience of on-site personnel, and also reduce the rejection rate of refined products. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of the ladle refining monitoring method based on vibration measurement; Figure 2 is a schematic diagram of the arrangement of ladle refining monitoring sensors.

[0019] In the figure: 1, ladle; 2, hanging ear; 3, trolley; 4, sensor; 5, blowing pipeline; 6, valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following combines the drawings and embodiments to further describe the specific embodiments of the present invention. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0021] Theoretical analysis shows that the vibration signal can effectively characterize the gas stirring intensity, but due to the difficulty in finding the law between the two, it is difficult to apply in actual engineering.

[0022] Embodiment 1: To better illustrate the application scenario of the present invention, as Figure 2 shown is a ladle refining monitoring device based on vibration measurement. The ladle 1 is placed on the trolley 3, vibration sensors 4 are respectively installed on the sides of the two hanging ears 2 of the ladle, and the blowing pipeline 5 blows gas into the ladle through the bottom of the ladle, and a controllable valve 6 is arranged on the blowing pipeline.

[0023] As Figure 1As shown in the figure, the present invention designs a ladle refining monitoring method based on vibration measurement. The vibration information of the ladle stirring is monitored in real time by at least two vibration sensors symmetrically arranged in terms of distance and angle. At least one flow rate (also known as flow velocity or intensity) sensor monitors the blowing gas flow rate information in real time. At least one valve is arranged on the blowing gas pipeline to automatically control the shut-off and opening of the gas and / or control the gas flow rate. According to the vibration information, it is judged whether the ladle is stirred evenly, and then the valve operation is controlled; If the stirring is already even, control the blowing valve to stop supplying gas, and the ladle refining enters the next process; If only the stirring is not yet even, maintain the current state and continue stirring until it is even; If the stirring exceeds the preset maximum stirring time, actively stop stirring and manually check the stirring effect; The method for judging whether the ladle is stirred evenly based on the vibration information includes the monitoring method: S1. Data acquisition, collect the vibration amounts of the vibration sensors symmetrically installed within the acquisition window duration (also known as window time) 、 …, extract the first eigenvalue corresponding to the vibration amount 、 … and the second eigenvalue 、 …, where is the sampling serial number, the sampling period is determined according to the vibration frequency, the characteristics of the sensor, and the characteristics of the data acquisition instrument (data acquisition box). The first subscript of the vibration amount and the eigenvalue identifies the vibration sensor number, S2. Vibration signal preprocessing, including filtering out obvious abnormal amplitude values and / or filtering out obvious non-stirring related frequency components; S3. Feature extraction, extract the first eigenvalue 、 … and / or the second eigenvalue 、 … , the first eigenvalue describes the magnitude of the vibration amount, and the second eigenvalue describes the discreteness of the vibration sequence; S4. Judgment and analysis, carried out according to the monitoring method; The monitoring method includes monitoring method one or monitoring method two; The monitoring method one includes, if all within the window duration, j≠k (such as ), then it is considered that the ladle stirring is already even, otherwise, stirring still needs to continue, where is the first threshold. That is, when the ladle vibration transfer characteristics at symmetric positions are consistent and last for a period of time (window duration), it can be considered that the molten steel in the ladle has been stirred evenly; the first threshold is the allowable difference in the vibration quantity characteristic values in the symmetric direction under the evenly stirred state. The smaller the threshold, the more evenly stirred, but the higher the requirements for the stirring time and the control of the gas stirring flow rate.

[0024] The second monitoring method includes that if all , j≠k (such as ), and all are satisfied (such as and etc.), it is considered that the ladle stirring is even, otherwise, stirring needs to continue. Among them, is the second threshold; that is to say, in addition to judging the difference in the first characteristics of the vibration sensors installed symmetrically, the second monitoring method also judges whether the second characteristic values of the vibration sensors are within a certain range. For example, the second characteristic value takes the variance of the respective vibration quantities within the window duration. When the variance is small enough, it indicates that the local molten steel being stirred has entered a steady state. At the same time, if the different local vibration characteristics are basically the same, it can be determined that this stirring is even, which makes sense; the second monitoring method is essentially an analysis and judgment method with higher quality requirements for steelmaking products. In this embodiment, the second monitoring method is used for analysis and judgment.

[0025] The above gas stirring control method mainly uses an empirical fixed stirring flow rate and realizes uniform stirring by controlling the stirring time. Note that the characteristic values of the vibration quantities in different directions should be statistically analyzed separately and cannot be mixed.

[0026] Preferably, the vibration quantity includes at least one of displacement, velocity, or acceleration in at least one of the x, y, and z directions (x and y are two horizontal directions, and z is the vertical direction) (such as the acceleration in the x direction). Generally, the vibration sensor measures acceleration, and the velocity is obtained by integrating the acceleration, and the displacement is obtained by integrating the velocity.

[0027] Preferably, the first characteristic value includes at least one of mean value, median, and norm. For example, the mean value of the vibration quantity within the window duration is taken as the basic information for analysis and judgment; the second characteristic value includes at least one of variance (RMS, root mean square value), standard deviation, maximum value, minimum value, and extreme value difference. The extreme value difference is the difference between the maximum value and the minimum value.

[0028] The vibration sensor in this embodiment simultaneously measures the acceleration in the x, y, and z directions. By integrating the acceleration, the vibration velocity and displacement can be obtained. When calculating the eigenvalue, generally, one of displacement, velocity, and acceleration is selected to calculate simultaneously for the x, y, and z directions, that is, the judgment method is executed simultaneously for these three types of eigenvalues. Note that when performing statistical analysis on the three directions, their thresholds are generally different. This embodiment mainly performs eigenvalue statistics and analysis on the velocity in the x, y, and z directions, and the first eigenvalue takes the mean value, and the second eigenvalue takes the variance value.

[0029] When only one vibration quantity is selected, it is recommended to preferably perform statistical calculation on the vertical direction velocity. On the one hand, because the vertical direction vibration velocity can better reflect the gas stirring intensity, and it is an ideal original information as an eigenvalue. Experimental analysis shows that the root mean square (RMS) of the vertical direction velocity is the best eigenvalue for measuring the stirring intensity caused by the blowing gas flow rate in the ladle. On the other hand, relatively speaking, the vertical direction vibration velocity value is higher, the requirement for measurement accuracy is relatively lower, and the difference judgment is more accurate.

[0030] Preferably, the lower limit of the window duration is not less than 3 times the longest vibration period duration, and the upper limit is not greater than the minimum lag duration.

[0031] Setting the lower limit of the window duration is mainly to facilitate the statistical calculation of the vibration quantity. At least 3 complete vibration periods should be sampled to obtain at least 3 sets of effective amplitude values. Only in this way does the amplitude statistical calculation make sense. In fact, generally, it should be more than 10 or even 20 effective vibration periods to basically ensure the accuracy and reliability of the statistical calculation. That is, the sampling coverage duration of the vibration quantity corresponding to the calculated eigenvalue should be long enough (not less than the lower limit duration) to ensure the accuracy of the stirring characteristic judgment, and the shorter the window duration, the higher the real-time performance.

[0032] Setting the upper limit of the window duration is mainly considered that the window duration cannot be too long. Otherwise, the stirring time is too long. On the one hand, the time-varying characteristics of the stirring effect are averaged by time, which will make it difficult to judge whether the stirring effect really meets the standard, or the conclusion may not be accurate, or the conclusion loses its meaning. On the other hand, if the window duration is too long, the statistical result cannot reflect the real-time actual situation, the real-time performance is reduced, that is, the monitoring and judgment efficiency is reduced, which is also not conducive to subsequent real-time control. Third, the longer the window duration, the greater the computational workload. Fourth, taking the maximum lag duration as the reference benchmark for the window duration upper limit, more often taking the minimum lag duration as the reference benchmark, mainly considering that if the molten steel is in the lag period transition stage (obviously non-steady state stage), the statistical characteristics should have obvious reactions. If the window duration exceeds this duration and introduces too much steady-state data, it will instead have an adverse effect on the statistical characteristic judgment, that is, abnormal phenomena may be averaged out. The lag duration includes actions such as changing the stirring gas flow rate, flow velocity or adding additives, etc. Generally, it takes a certain lag time for the molten steel to enter a relatively steady state.

[0033] Accuracy and timeliness are sometimes contradictory requirements for the window duration here and need to be considered in a balanced way.

[0034] Preferably, the window duration includes 10s, 21s or 40s. In this embodiment, the window duration is set to 10s. The main consideration is that the vibration period of the molten steel transferred by the measured ladle is generally less than 1s. For sampling statistics, 10s, which is at least more than 100 vibration periods, is neither too small nor too large and is relatively appropriate. This window duration also has a certain degree of real-time performance. Compared with the traditional molten steel stirring time of several minutes or even dozens of minutes, the real-time performance of the 10s detection and judgment period is relatively obvious.

[0035] Preferably, the symmetry includes 180-degree symmetry (2 vibration sensors) with the central axis of the ladle as the axis of symmetry, 90-degree symmetry (4 vibration sensors), 60-degree symmetry (6 vibration sensors), and it is default that the symmetry is equidistant from the axis of symmetry.

[0036] Preferably, the monitoring method includes the sliding window monitoring method, that is, the window slides once per unit time, and the unit time is the window sliding time interval. The vibration quantity and its characteristic values within the sliding window duration are analyzed and judged according to Monitoring Method 1 or Monitoring Method 2.

[0037] Preferably, the window sliding time interval includes integer seconds (such as every 1 second or every 2 seconds, etc.) or a unit time greater than or equal to the longest vibration period or greater than or equal to an integer multiple of the sampling period. Using an integer second interval for the window sliding time interval conforms to the traditional sampling cognitive habit; using an interval greater than the longest vibration period is considered to ensure that at least one complete vibration period is included in one slide, and in fact, generally multiple such vibration periods are slid at a time; using an integer multiple of the sampling period is convenient for data statistics and calculation, and different choices have different advantages. In this embodiment, the sampling rate is 10kHz, and a 1s sliding time interval is adopted, which simultaneously meets the requirement of being greater than the longest vibration period (for the lowest 2Hz, 0.5s period vibration signal). Therefore, this setting essentially meets the above three conditions at the same time.

[0038] Embodiment 2: The difference from Embodiment 1 is that in this embodiment, the gas flow rate is simultaneously controlled (not shown in the figure), and the monitoring method further includes: if the stirring is not yet uniform and the stirring intensity is insufficient, the blowing gas flow rate is changed according to the gas stirring control rule to adjust the stirring intensity; the gas stirring control rule includes: Simultaneously and real-time monitor the blowing gas flow rate (also referred to as the flow velocity or intensity, and the working gas is generally argon) and the vibration quantity, and calculate the ladle response value (LRV) within the window duration as the third characteristic value 、 … The ladle response value is the ratio of the area under the vibration - time curve to the area under the flow - time curve (or the ratio of the integral of vibration with respect to time to the integral of flow with respect to time within the window duration). The average value of the ladle response values of symmetrically installed vibration sensors can also be used as the third eigenvalue of the stirring state of the ladle within the window duration; According to the pre - calibrated ladle response value curve (i.e., the gas - blowing intensity - vibration signal curve), obtain the nominal value of the strongest vibration signal intensity corresponding to the measured gas - blowing flow rate If within the window duration and satisfy any then it is considered that the gas - blowing stirring for this time has reached the optimal state and the stirring is uniform. Among them, is the third threshold, is the fourth threshold; if any then control the change of the gas - blowing gas flow rate according to where is the change amount of the gas - blowing gas flow rate (or called the increment, note that the total flow rate after the gas flow rate increases should be controlled within the allowable flow rate range), is the average value of the third eigenvalues of all symmetrically installed vibration sensors is the proportionality coefficient, which can be set and debugged with reference to to obtain the empirical coefficient. Among them, M is the mass of the melt in kg, R is the universal gas constant with the unit J / mol -1 K -1 T is the melting temperature in K, T in is the inlet temperature in K, P in is the inlet pressure in Pa, P out is the outlet pressure in Pa.

[0039] That is, if the pairwise difference of the ladle response values of all symmetrically installed vibration sensors is less than the third threshold and the deviation between the ladle response value of each symmetrically installed vibration sensor and the nominal vibration signal intensity value under the corresponding gas - blowing intensity is less than the fourth threshold it can be considered that the ladle has been stirred evenly. Otherwise, the gas - blowing gas flow rate can be adjusted to achieve uniformity as soon as possible. In fact, without adjusting the flow rate and continuing to stir can also achieve uniform stirring, but the time may be longer and the efficiency may be lower.

[0040] ​Regarding the acquisition of empirical parameters, since the gas stirring effect is judged by taking the difference, there is no need to consider the consistency of too many environmental parameters. It is only necessary to monitor the ladle actually stirred under the traditional empirical stirring intensity and time in real time, and extract the difference of characteristic values corresponding to different grades according to the final product quality, which can be used as the threshold reference for products of different grades (performance grades) when the present invention is applied. In special cases, different thresholds can also be set for different product models (including different types of additives, addition amounts and process sequences), different ladle sizes, different trolley environments, and different grades of products under different gas blowing methods. In any case, the comparison of differences can filter out the influence of various common factors, while the measurement of the absolute value of the vibration amount, the ladle response value (LRV) or the rolled ladle response value (rLRV) will be affected by dynamic factors, and the differences may be very large, and there is almost no reference between them. It is difficult to analyze and separate the effective values, and the difficulty of accurately obtaining the empirical parameters is much higher than that of obtaining the empirical parameters of the present invention. Moreover, the difference threshold of the vibration amount characteristic value of the empirical parameters of the present invention has little difference for different environments and different ladles (only the threshold requirements for steelmaking products of different models and qualities are different. Obviously, the smaller the threshold, the better the product performance, the higher the requirements for the stirring time or the air flow intensity, and of course the higher the requirements for the measurement accuracy of the sensor). The referenceability between them is strong because many uncertain influencing factors have been eliminated during the process of taking the difference, and the remaining mainly is the influence brought by uneven stirring.

[0041] Example 3: The difference from Example 1 is that the monitoring method in this example further includes a flow rate grading combined stirring method (not shown in the figure). The flow rate grading at least distinguishes two levels of large flow rate and small flow rate. The flow rate grading combined stirring method includes: The two-stage flow rate combined stirring method. First, blow gas and stir with a large flow rate until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met; then blow gas and stir with a small flow rate until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met. Compared with the single flow rate stirring control in the design of this example, the large flow rate for rough stirring can make the molten steel quickly approach the target uniform state, and the small flow rate for fine stirring can make the stirring more uniform and the final product performance higher. The flow rate grading combined stirring method is essentially a method that takes into account both stirring efficiency and stirring effect. Compared with single flow rate stirring, when the flow rate is large, it is difficult to improve the stirring effect, and when the flow rate is small, the stirring time is too long. It is not difficult to see the advantages of the flow rate grading combined stirring method. Or, the three-stage flow rate combined stirring method. First, blow gas and stir with a large flow rate until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met; then blow gas and stir with a medium flow rate until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met; finally, blow gas and stir with a small flow rate until the corresponding requirements of Monitoring Method 1 or Monitoring Method 2 are met. Different flow rates and different monitoring methods correspond to their respective monitoring thresholds (i.e., corresponding to different first to fourth thresholds).

[0042] Preferably, in the secondary flow rate combined stirring method, the secondary flow rates can be set in a ratio relationship of 2:1, 3:1, 4:1, or 5:1, and in the tertiary flow rate combined stirring method, the tertiary flow rates can be set in a ratio relationship of 4:2:1, 5:3:1, 6:3:1, or 8:4:1. In this embodiment, the tertiary flow rate combined stirring method is adopted, and the flow rate ratio is set to 5:3:1.

[0043] Example 4: The difference from Example 1 is that in this embodiment, the first threshold, the second threshold, the third threshold, and the fourth threshold all include quasi-dynamic thresholds, and the nominal value includes a quasi-dynamic nominal value. The method for determining the quasi-dynamic threshold and the quasi-dynamic nominal value is as follows: when it is determined that the stirring time of the constant blowing gas flow rate exceeds the maximum value of the empirical duration, and the first eigenvalue, the second eigenvalue, or the third eigenvalue cannot meet the requirements of the corresponding Judgment Method 1, Judgment Method 2, or Judgment Method 3, the measured calculated value is used as the quasi-dynamic threshold or the quasi-dynamic nominal value of the corresponding threshold. That is, the previously default used threshold is corrected with the measured value to obtain a dynamic threshold. Note that after changing the ladle or the stirring environment, the default threshold should still be used, unless the default prediction correction according to almost the same value occurs during multiple actual uses, and a new dynamic threshold is obtained. At this time, the system should actively modify the default threshold. The specific calculation method of the correction amount can be calculated according to the corresponding judgment method.

[0044] This embodiment mainly considers that due to the actual asymmetry of the installation position or the actual effect of the stirring air injection ports not being equivalent to the air injection at the middle of the ladle bottom, the vibration transmission and attenuation on both sides are inconsistent, and the vibration transmission and attenuation of the environmental vibration source to the target sensor are inconsistent, etc. The above reasons combined with the dynamic change factors during stirring will cause a dynamic deviation when the eigenvalues of symmetrically installed sensors are subtracted. This dynamic deviation is related to the single installation of the sensor, the type of ladle, the real-time molten steel capacity (including the liquid level height), the shape and position of the air injection port, the air injection direction, the dynamic change of the gas flow rate, the dynamic change of the additive addition direction, the change of the same additive brand and model, etc. The present invention uses the quasi-dynamic threshold and the quasi-dynamic nominal value to characterize the influence of this dynamic deviation; the method for obtaining this dynamic deviation should mainly be based on the empirical value of the difference in the corresponding sensor eigenvalues under the condition that the stirring effect is confirmed to be good by the traditional stirring method in the same environment (including the installation environment and the stirring environment, etc.) as the benchmark for setting the quasi-dynamic threshold.

[0045] The design of this embodiment actually also reflects the practicability and convenience of the present invention. Since it is difficult to obtain empirical parameters for the application of many data processing and analysis methods, which leads to difficulties in their practical applications, the method for obtaining the quasi-dynamic threshold and the quasi-dynamic nominal value given in this embodiment is essentially also a method for obtaining empirical parameters of the threshold or the nominal value.

[0046] Embodiment 5: The difference from Embodiment 1 is that in this embodiment, the vibration quantity only takes the vertical velocity for statistical calculation.

[0047] Embodiment 6: The difference from Embodiment 1 is that in this embodiment, the 2-norm of the acceleration is taken as the first eigenvalue, and the standard deviation of the acceleration within the window duration is taken as the second eigenvalue.

[0048] The window duration is set to 21 s. This is mainly considered based on the analysis of actual test data. When performing the central median smoothing filter, when choosing a window duration of 21 s, the correlation between the gas flow rate and the vibration characteristics is the strongest, and the best vibration characteristics of gas stirring can be obtained.

[0049] Embodiment 7: The difference from Embodiment 1 is that in this embodiment, the 1-norm of the displacement is taken as the first eigenvalue, and the extreme difference of the displacement within the window duration is taken as the second eigenvalue.

[0050] The window duration is set to 40 s. This is mainly considered based on empirical data that generally enters the stable state after 40 s. 40 s is the shortest time for the vibration effect lag (of course, it is related to the stirring gas flow rate. This data is the statistical data under normal large flow rates. When the flow rate decreases, this time will be longer).

[0051] The basic principle of this project is to precisely control the stirring time by monitoring the real-time stirring effect (when the effect meets the index requirements, the system automatically closes the blowing valve and sends out a prompt message indicating the completion of stirring). Further, the blowing flow rate can be adjusted according to the real-time stirring effect, and the blowing duration at different flow rates can be controlled to achieve better stirring effect and efficiency. When the ladle stirring is not yet uniform, due to the difference in the transmission path, the measurement data characteristics of the symmetrically installed vibration sensors affected by the stirring vibration will inevitably be different. The present invention is designed based on this basic principle. According to the analysis results of the magnitude of the vibration amount (the first eigenvalue) and the degree of dispersion of the vibration sequence (the second eigenvalue) detected by the symmetrically installed vibration sensors, it is judged whether the ladle stirring is uniform. If it is uniform, the stirring is stopped; otherwise, the stirring continues. The above method reasonably utilizes the vibration amount eigenvalue, taking into account both the local and the global. At the same time, the present invention also proposes a further refined monitoring method for flow control based on the ladle response value, and the flow rate grading combined stirring method can achieve the purpose of faster and more uniform stirring. The present invention is simple and easy to implement, and can achieve precise monitoring of ladle refining with different quality requirements, which can not only improve the stirring efficiency of ladle refining but also reduce the reject rate of refined products.

[0052] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and refinements can be made. For example, regarding the selection of the analysis object, including the measurement direction, the type of vibration amount (acceleration, velocity, displacement), and the selection and combination methods of eigenvalue types, there are several choices in addition to the several methods given in the embodiments. Regarding the installation position, arrangement method, window duration, window sliding time interval setting and combination of sensors, the combination of the preferred methods of Embodiment 2, Embodiment 3 and other embodiments, as well as the selection of the flow rate grading combined stirring method and the selection of flow rate ratios in Embodiment 3, etc., there are many variations. These improvements and changes should also be regarded as the protection scope of the present invention.

Claims

1. A ladle refining monitoring method based on vibration measurement, characterized in that, Vibration sensors symmetrically arranged according to at least two distance angles are used to monitor the vibration information of the ladle stirring in real time. At least one flow sensor is used to monitor the blowing gas flow information in real time. At least one valve is arranged on the blowing gas pipeline to control the shut-off and opening of the gas and / or control the gas flow. Whether the ladle is stirred evenly is judged based on the vibration information. If it has been stirred evenly, control the blowing valve to stop supplying gas. If it is only stirred but not yet evenly, maintain the current state and continue stirring until it is stirred evenly. If the stirring exceeds the preset maximum stirring time, actively stop stirring and manually check the stirring effect. The method for judging whether the ladle is stirred evenly based on the vibration information includes a monitoring method: Vibration amounts of vibration sensors symmetrically installed within the acquisition window duration , …, extract the first eigenvalue corresponding to the vibration amount , … and the second eigenvalue , …, where is the sampling serial number, and the monitoring method includes Monitoring Method 1 or Monitoring Method 2; The first monitoring method includes that if all of , where j≠k, it is considered that the ladle stirring is uniform; otherwise, stirring needs to continue, where is the first threshold value. The second monitoring method includes that if all , where j ≠ k, and all are satisfied, it is considered that the ladle stirring is uniform; otherwise, stirring needs to continue. Among them, is the second threshold value.

2. The ladle refining monitoring method based on vibration measurement according to claim 1, wherein The monitoring method further includes: if it is not yet stirred evenly and the stirring intensity is insufficient, change the blowing gas flow according to the gas stirring control rule to adjust the stirring intensity; the gas stirring control rule includes: At the same time, the blowing gas flow rate and the vibration amount are monitored in real time, and the ladle response value within the window duration is calculated as the third eigenvalue , … , and the ladle response value is the ratio of the area under the vibration amount-time curve to the area under the flow rate-time curve; According to the pre-calibrated ladle response value curve, obtain the nominal value of the strongest vibration signal intensity corresponding to the measured gas blowing flow rate , if within the window duration , and any is satisfied, then it is considered that the gas blowing stirring for this time has reached the optimal state and the stirring is uniform. Among them, is the third threshold, is the fourth threshold; if any , then control the change of the gas blowing flow rate according to , where is the change amount of the gas blowing flow rate, is the mean value of the third eigenvalue of all symmetrically installed vibration sensors, is the proportionality coefficient.

3. A ladle refining monitoring method based on vibration measurement according to claim 1, characterized in that, The monitoring method further includes a flow rate grading combined stirring method. The flow rate grading at least distinguishes two levels of large flow rate and small flow rate. The flow rate grading combined stirring method includes: The two-stage flow rate combined stirring method. First, blow and stir with a large flow rate until the requirements corresponding to Monitoring Method 1 or Monitoring Method 2 are met; then blow and stir with a small flow rate until the requirements corresponding to Monitoring Method 1 or Monitoring Method 2 are met. Or, the three-stage flow rate combined stirring method. First, blow and stir with a large flow rate until the requirements corresponding to Monitoring Method 1 or Monitoring Method 2 are met; then blow and stir with a medium flow rate until the requirements corresponding to Monitoring Method 1 or Monitoring Method 2 are met; finally, blow and stir with a small flow rate until the requirements corresponding to Monitoring Method 1 or Monitoring Method 2 are met. Different flow rates and different monitoring methods correspond to their respective monitoring thresholds.

4. The ladle refining monitoring method based on vibration measurement according to claim 3, characterized in that, In the two-stage flow rate combined stirring method, the two-stage flow rates are set according to a magnification relationship of 2:1, 3:1, 4:1, or 5:

1. In the three-stage flow rate combined stirring method, the three-stage flow rates are set according to a magnification relationship of 4:2:1, 5:3:1, 6:3:1, or 8:4:

1.

5. A ladle refining monitoring method based on vibration measurement according to any one of claims 1 to 4, characterized in that, The vibration quantity includes at least one of displacement, velocity, or acceleration in at least one of the x, y, and z directions.

6. A ladle refining monitoring method based on vibration measurement according to any one of claims 1 to 4, characterized in that, The first eigenvalue includes at least one of mean value, median value, and norm; the second eigenvalue includes at least one of variance, standard deviation, maximum value, minimum value, and extreme value difference.

7. A ladle refining monitoring method based on vibration measurement according to any one of claims 1 to 4, characterized in that, The lower limit of the window duration is not less than 3 times the longest vibration period duration, and the upper limit is not greater than the minimum lag duration.

8. A ladle refining monitoring method based on vibration measurement according to any one of claims 1 to 4, characterized in that, The window duration includes 10s, 21s, or 40s.

9. A ladle refining monitoring method based on vibration measurement according to claim 1 or 4, characterized in that, The symmetry includes 180-degree symmetry, 90-degree symmetry, and 60-degree symmetry with the ladle central axis as the symmetry axis.

10. A ladle refining monitoring method based on vibration measurement according to any one of claims 1 to 4, characterized in that The monitoring method includes a sliding window monitoring method, that is, the window slides once per unit time. The unit time is the window sliding time interval. The vibration quantity and its eigenvalues within the sliding window duration are analyzed and judged according to Monitoring Method 1 or Monitoring Method 2.

11. A ladle refining monitoring method based on vibration measurement according to claim 10, characterized in that, The window sliding time interval includes an integer second or a unit time greater than or equal to the longest vibration period or greater than or equal to an integer multiple of the sampling period.

12. A ladle refining monitoring method based on vibration measurement according to claim 2, characterized in that, The first threshold, the second threshold, the third threshold, and the fourth threshold all include a quasi-dynamic threshold, and the nominal value includes a quasi-dynamic nominal value. The method for determining the quasi-dynamic threshold from the quasi-dynamic nominal value includes that when it is determined that the stirring time at a constant blowing flow rate exceeds the maximum value of the empirical duration, and when the first eigenvalue, the second eigenvalue, or the third eigenvalue cannot meet the requirements of the corresponding determination method 1, determination method 2, or determination method 3, the measured calculated value is used as the quasi-dynamic threshold or the quasi-dynamic nominal value of the corresponding threshold.

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