Identification method for reverse final pouring by thermocouple installation in slab mold breakout prediction system

Abstract

A method for identifying thermocouples installed in reverse order during final casting in a slab mold breakout prediction system is described. The method employs a matrix arrangement of multiple rows and columns of thermocouples on the mold copper plate. During the final casting phase of a slab continuous casting machine, the method identifies anomalies, collects information, and performs actual sequencing on each thermocouple. The actual sequence table is used to determine whether the thermocouples were installed in reverse order. The present invention is applicable to slab continuous casting machines.

Description

Technical Field

[0001] The present invention relates to the field of continuous casting technology in the metallurgical industry, namely, to perform final casting online during the period from the completion of casting in the tundish of a continuous casting machine to the delivery of the continuous casting billet to the lower mouth of the crystallizer to identify whether the crystallizer thermocouple is installed in reverse order. Background Art

[0002] In continuous casting, especially slab casting, mold breakout is a serious safety hazard, endangering operators and severely damaging equipment. Repairs can take a long time, disrupt production, and significantly increase maintenance and production costs. To mitigate these incidents, colleagues both domestically and internationally have developed various mold breakout prediction systems to ensure safe production and minimize losses.

[0003] Existing mold breakout prediction systems primarily rely on embedding armored thermocouples in a matrix arrangement on the mold copper plate. These thermocouples then detect whether the billet shell is sticking within the mold based on temperature changes in the thermocouple feedback. Therefore, the quality of the thermocouple installation directly impacts the accuracy of the breakout prediction system. Only when the thermocouple at each measurement point accurately corresponds to the corresponding point in the data acquisition system can the true thermal distribution of the billet on the mold copper plate be accurately reflected.

[0004] During offline installation of the mold, thermocouples are strictly installed in separate rows within the same column. This effectively prevents incorrect installation of thermocouples in different rows. However, when installing thermocouples within the same column, errors can still occur, such as installing the thermocouples in reverse order. This means that a thermocouple originally installed in the first row may be mistakenly installed in the second or third row. This error directly causes the temperature feedback from the thermocouples to be inconsistent with the actual heat distribution on the copper plate. If one thermocouple is installed in reverse order, two or more thermocouples will also be installed in reverse order, directly causing the temperature feedback from the thermocouples in that column to be abnormal, leading to false alarms or omissions in the steel breakout prediction system.

[0005] To address the above issues, there is currently no solution that has high recognition rate, simple method, fast and effective, and low cost. Summary of the Invention

[0006] The final pouring recognition method is to identify the tail billet at the stage of being output from the upper mouth of the crystallizer to the lower mouth of the crystallizer before the continuous casting tundish stops casting. This method can be used either manually or through a developed program.

[0007] Identification method (this case is based on a 1600*250 cross-section mold (wide copper plate thermocouples are distributed in 3 rows and 11 columns, such as Figure 1 ) for specific explanation:

[0008] Step S1: Abnormal identification: Before the final pouring of the tundish of the continuous casting machine, the casting speed is reduced to the minimum (such as 0.27m / min), and the molten steel level in the crystallizer is still at the normal pouring height (such as Figure 2 ), the feedback temperature of the mold thermocouple decreases as the casting speed decreases. At this time, two temperature values, "abnormally high temperature" and "abnormally low temperature", are set to perform preliminary discrimination on all thermocouples. In this case, thermocouples with a temperature higher than 86°C ("abnormally high temperature"), lower than 55°C ("abnormally low temperature"), and "abnormal temperature fluctuation" are all marked as "abnormal" and do not participate in the calculation. The remaining thermocouples continue to participate in the calculation;

[0009] Step S2: Information collection: After the tundish of the continuous casting machine is finally poured, the tail billet begins to be discharged from the upper mouth of the crystallizer to the lower mouth according to the set billet drawing speed (such as Figure 3 、 4 , 5). The tail billet is discharged downwards and leaves the copper plate where the first row of thermocouples is located first. No heat from the billet is transferred to the copper plate where the thermocouples are located. The copper plate is affected by the cooling water of the crystallizer, which quickly takes away the residual heat on the copper plate. The temperature of the thermocouples in this row drops rapidly (such as Figure 6 ). Set the "tail billet separation temperature" (set below 50℃ in this case). When all thermocouples participating in the operation in the thermocouple matrix are below 50℃, sample and record the "row" and "column" position information of each thermocouple and the time to reach this temperature. According to the copper plate surface (arc width surface, outer arc width surface, left narrow surface, right narrow surface), form an "Information Collection Table" (such as Figure 7 、 8 );

[0010] Step S3: actual sorting: perform thermocouple "column-by-column" sorting on the "Information Collection Table" and form an "actual sequence table" (such as Figure 9 、 10 ). Follow the steps below to complete the following operations:

[0011] Operation 1: If the thermocouple in the column does not have any abnormality, in this case, you only need to sort the rows in the order of acquisition time. The earliest row is in the first row, the second row is in the second row, and so on. For normal columns, the rows should be sorted first. The result records correspond to the copper plate "Actual Sequence Table".

[0012] Operation 2: Calculate the "average acquisition time" of each row of thermocouples on each copper plate, and record the result in the "actual sequence table" of the corresponding copper plate;

[0013] Operation 3: Perform operations on thermocouples not marked as "abnormal" in the "column" with "abnormal" thermocouples. The "column" may have one or N "abnormal" thermocouples. In this case, the operation method is different. First, the "average acquisition time" of the copper plate should be used as the basis for time comparison. The thermocouple with the closest "average acquisition time" will be placed in the same "row" sequence (actually, thermocouples in the same row have very similar acquisition information times). The results are recorded in the corresponding copper plate "Actual Sequence Table";

[0014] Operation 4: The remaining points not involved in the operation are still marked as "abnormal", and the result records correspond to the copper plate "Actual Sequence Table";

[0015] Step S4: Screen out the reversed sequence thermocouples from the completed "actual sequence table".

[0016] Identification accuracy control: The three temperatures of "abnormally high temperature," "abnormally low temperature," and "tail slab separation temperature" must be adjusted based on factors that may affect the copper plate temperature, such as different steel grades, mold slag properties, and the size of the casting machine cross-section. For example, the larger the cross-section, the higher the set temperature, while the smaller the cross-section, the lower the set temperature.

Claims

1. A method for identifying thermocouple installation reverse order final pouring in a slab crystallizer breakout prediction system, characterized in that: The mold breakout prediction system has multiple rows and columns of thermocouples arranged in a matrix on the mold copper plate. The identification method performs abnormality identification, information collection, and actual sorting on each thermocouple during the final pouring operation of the slab continuous casting machine. Abnormal identification: Before the final pouring of the tundish of the continuous casting machine, the casting speed is reduced to the minimum, and the molten steel level in the crystallizer is still at the normal casting height. The feedback temperature of the crystallizer thermocouple decreases as the casting speed decreases. At this time, all thermocouples are preliminarily identified. Thermocouples with "abnormally high temperature", "abnormally low temperature", or "abnormal temperature fluctuation" are marked as "abnormal" and excluded from the calculation. The remaining thermocouples continue to participate in the calculation. Information collection: After the final pouring of the tundish of the continuous casting machine, the tail billet begins to be discharged from the upper end to the lower end of the crystallizer at the set billet drawing speed. As the tail billet is discharged downward, it first leaves the copper plate position where the first row of thermocouples is located. No heat from the billet is transferred to the copper plate position where the thermocouples in this row are located. The copper plate is affected by the crystallizer cooling water, which quickly removes the residual heat on the copper plate. The temperature of the thermocouples in this row then drops rapidly. When all the thermocouples participating in the calculation in the set "tail billet separation temperature" thermocouple matrix are lower than the tail billet separation temperature, sampling is performed to record the "row" and "column" position information of each thermocouple and the time to reach this temperature. An "Information Collection Table" is generated based on the copper plate surface. Actual sorting: perform thermocouple "column-by-column" and "row-by-row" sorting on the "Information Collection Table" and form an "Actual Sequence Table" according to the copper plate surface; The actual sorting features perform the following operations in order: Operation 1: For the "columns" of thermocouples without abnormalities, sort the "rows" in chronological order, with the earliest row being the first, the second the second, and so on; the results are recorded in the "Actual Sequence Table"; Operation 2: After completing step 1, calculate the "average acquisition time" of the thermocouples in each "row" on the copper plate surface and record the result in the "Actual Sequence Table"; Operation 3: Perform an operation on the thermocouples not marked as "abnormal" in the "column" with the abnormal thermocouple. Compare the thermocouple acquisition time with the "average acquisition time" of each row of the copper plate, and group them into the "row" sequence with similar time. The results are recorded in the "Actual Sequence Table"; Operation 4: The remaining points not involved in the operation are still marked as "abnormal", and the result is recorded in the corresponding copper plate "Actual Sequence Table".

2. The method for identifying thermocouple installation reverse order final pouring in a slab mold breakout prediction system according to claim 1, characterized in that: Abnormal identification features: "Abnormally high temperature", "abnormally low temperature" and "abnormal temperature fluctuation" are used to determine whether the thermocouple is "abnormal".

3. The method for identifying thermocouple installation reverse order final pouring in a slab mold breakout prediction system according to claim 1, characterized in that: Information collection features: record the time when each sequence of thermocouples reaches the "tail billet separation temperature", summarize the information, and form an "Information Collection Table".

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