JP2004223602A - Method and system for managing temperature of molten steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a prescribed cast temperature in a continuous casting process even when an errors occurs between the planning time and actual operation time of a steel making schedule. <P>SOLUTION: The cast end time of a present charge is estimated based on the temperature in a ladle of the molten steel after the end of secondary refining treatment of the present charge, the temperature in a tundish of the molten steel under continuous casting and/or the cast speed of continuous casting and the cast start time of the next charge is estimated based on the estimated cast end time of the present charge. The molten steel temperature of the next charge is then managed based on the estimated cast start time of the next charge. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for controlling molten steel temperature, specifically, in a steelmaking process, the temperature of molten steel produced in a steelmaking furnace such as a converter and an electric furnace and discharged to a ladle is appropriately adjusted until the subsequent continuous casting process. The present invention relates to a method and apparatus for controlling the temperature of molten steel in order to obtain a predetermined casting temperature during continuous casting.
[0002]
[Prior art]
In a general steelmaking process using continuous casting, as shown in a schematic diagram of FIG. 1, molten steel subjected to refining processing (primary refining processing) in a steelmaking furnace (converter, electric furnace, etc.) 1 is discharged to a ladle 2. After performing secondary refining treatments such as vacuum degassing and component temperature adjustment in the ladle 2, it is transported and temporarily stored in the tundish 3, and the outside of the mold 4 located below is covered with a solidified shell. Continuous casting is performed by continuously drawing the cast slab 5 in the state of the solid-liquid two-phase body.
[0003]
In such a steelmaking process by continuous casting, in order to minimize the variation of the molten steel temperature for each charge and to ensure stable operation, each process, specifically, the steelmaking furnace 1 shown in FIG. In the primary refining process, the process of transport from the steelmaking furnace 1 to the tundish 3, the process of secondary refining in the ladle 2 during this transport, the process of pouring into the tundish 3 and the process of casting with the mold 4. It is important that the molten steel temperature is a predetermined temperature. In particular, the temperature of the molten steel during casting from the tundish 3 to the mold 4 is important for improving the quality of the slab 5 manufactured by continuous casting.
[0004]
However, in the steelmaking process by continuous casting as described above, the secondary refining process in the ladle 2 is the final process in which the molten steel temperature can be adjusted. Only dissipates heat naturally and descends over time. Therefore, it is necessary to determine the molten steel temperature at the end of the secondary refining process in consideration of the time required in each of the subsequent processes, in other words, the amount of temperature drop during that time.
[0005]
Under the circumstances described above, techniques for controlling the temperature of molten steel are disclosed in, for example, Patent Documents 1 and 2 and the like. Patent Literature 1 discloses a technique for correcting a target temperature of molten steel at the start of a secondary refining process in consideration of a temperature drop amount and a process required time in each of a secondary refining process, a molten steel transportation process, and a casting process in a steelmaking process. Is disclosed.
[0006]
Patent Document 2 also predicts the amount of molten steel temperature drop from the end of processing in a steelmaking furnace to the start of casting using the past charge performance data and various operation fluctuation factors, and obtains from this predicted value. A technique is disclosed in which the molten steel temperature at the end of the treatment in the steelmaking furnace is set as a target temperature in the steelmaking furnace to automatically control the blowing of the steelmaking furnace.
[0007]
Patent Document 3 discloses a technique for creating an operation schedule of a steelmaking process.
[0008]
[Patent Document 1]
JP-A-4-251648
[Patent Document 2]
Japanese Patent No. 2751800
[Patent Document 3]
Japanese Patent No. 3166822
[0009]
[Problems to be solved by the invention]
By the way, the technique disclosed in Patent Literature 2 focuses on managing the molten steel temperature at the end of processing in a steelmaking furnace. Specifically, at the start of the steelmaking process, by estimating the amount of temperature drop of the molten steel from the end of the steelmaking furnace process to the casting time, and calculating the target temperature back from this result to set the target temperature at the end of the steelmaking process. It is intended to ensure a target casting temperature during the casting process. The target pouring temperature is set in advance in relation to the type of steel, quality, and the like.
[0010]
However, in the technology disclosed in Patent Document 2, the time required from the end of the treatment in the steelmaking furnace to the casting greatly affects the amount of temperature drop of the molten steel. Specifically, if a long time is required, It is natural that the temperature of the molten steel drops naturally due to heat radiation.
[0011]
In the technique disclosed in Patent Document 2, the transfer time between the steelmaking furnace and the ladle for the secondary refining process from the end of the process in the steelmaking furnace to the casting process, the secondary refining process The planned time (scheduled time) is used for the time required for the refining, the transfer time from the end of the secondary refining process to the tundish, the casting time, and the like. As the planned time, for example, a planned time created by a known steelmaking schedule creating system or the like as disclosed in Reference 3 can be used.
[0012]
In the technology disclosed in Patent Document 1, at the start of the secondary refining process, the amount of temperature drop of the molten steel from the end of the secondary refining process to the casting is estimated, and the result is back-calculated to obtain the value at the end of the secondary refining process. By setting the target temperature, the target casting temperature during the casting process is to be ensured. It is to be noted that the target pouring temperature is set in advance in relation to the type of steel, quality, and the like, as in the technique disclosed in Patent Document 2.
[0013]
However, in the technique disclosed in Patent Document 1, the time required from the end of the secondary refining process to the time of casting significantly affects the amount of temperature drop of the molten steel. It is also the same as the technique disclosed in Patent Document 2 in that it is natural that the molten steel temperature naturally drops due to this.
[0014]
In the technology disclosed in Patent Document 1, a transfer time from the end of the secondary refining process to the tundish, a casting time, and the like, between the end of the secondary refining process and the casting process, include a planned time (planned). This is similar to the technique disclosed in Patent Document 2.
[0015]
As described above, in any of the techniques disclosed in Patent Documents 1 and 2, since the estimated value of the amount of drop in the molten steel temperature in each process is used, accurate prediction of the planned time of the steelmaking schedule is indispensable. Needless to say, the actual operation needs to proceed according to the planned schedule. However, when an error occurs between the planned time and the actual operation time, a large error occurs in the accuracy of estimating the drop amount of the molten steel temperature, so that there is a problem that a predetermined casting temperature cannot be obtained. Was.
[0016]
In addition, when the error of the casting temperature occurs in the continuous casting in a lower direction, the casting speed may be increased and the casting may need to be interrupted, and the slab quality is deteriorated. Conversely, if the error in the casting temperature occurs to the higher side, the casting speed may be reduced and breakout may occur, and the slab quality also deteriorates.
[0017]
FIG. 8 is a timing chart for specifically explaining the above-described problem.
[0018]
The top row shows the planned time of the charge (hereinafter referred to as the current charge) during the execution of the steelmaking process, and the next row shows the actual operation time of the current charge. Here, for example, the time required for the continuous casting process in the actual operation time of the current charge becomes longer than the planned time by the time T due to an error in the casting temperature from the target casting temperature. Let's say that. Along with this, the transfer time to the tundish in the actual operation time of the charge (hereinafter, referred to as the next charge) in which the steelmaking process is executed after the current charge, that is, the continuous casting start time is delayed by the time T. The need has arisen.
[0019]
At this time, regarding the next charge planning time, in the technology disclosed in Patent Document 1, at the end of the secondary refining process, the molten steel temperature is considered in consideration of the estimated temperature drop amount (first estimated temperature drop amount). In the technology disclosed in Patent Document 2, the temperature of the molten steel is managed in consideration of the estimated temperature drop amount (second estimated temperature drop amount) at the end of the steelmaking furnace process.
[0020]
However, in practice, due to the above-described delay time T, the actual pouring temperature causes an error from the target pouring temperature during the actual operation of the next charge, and specifically drops.
[0021]
Conventionally, in order to eliminate the error between the planned time of the steelmaking schedule and the actual operation time as described above, for example, rescheduling (resetting the planned time) by the steelmaking schedule creation system itself or an operator Countermeasures such as manual adjustment based on experience and intuition are possible. However, in the former case, there is a possibility that the processing of the charge has already been completed at the time when rescheduling is performed, and in the latter case, there is a problem that the difference depends on the personal ability difference of the worker.
[0022]
The present invention has been made in view of the above circumstances, and when an error occurs between the planned time of the steelmaking schedule and the actual operation time, conventionally, it has been impossible to properly manage the molten steel temperature. It is an object of the present invention to provide a method for controlling molten steel temperature, which can solve the problem that a predetermined casting temperature cannot be obtained. Another object is to provide an apparatus for realizing such a method.
[0023]
[Means for Solving the Problems]
The method for controlling the temperature of molten steel according to the present invention is to perform a secondary refining process while transporting the molten steel after the primary refining process to the tundish with a ladle, and to continuously inject the tundish into the tundish and cool it from the mold as a slab. In the temperature control method of molten steel for obtaining a predetermined pouring temperature of the steelmaking process of continuously drawing and continuously casting, regarding the charge during the execution of the steelmaking process, the temperature in the ladle of the molten steel after the secondary refining process, the continuous casting Estimating the pouring end time based on the temperature of the molten steel in the tundish and / or the pouring speed of the continuous casting, and, based on the estimated pouring end time, the next charge of the charge during the execution of the steelmaking process Estimating the casting start time of the steel, and, based on the estimated casting start time, the molten steel temperature of the next charge after the charge during the execution of the steelmaking process. Characterized in that it comprises a step of management.
[0024]
In the method for controlling the temperature of molten steel according to the present invention, the temperature in the ladle of the molten steel after the secondary refining of the charge (current charge) during the execution of the steelmaking process, and the temperature in the tundish of the molten steel during the continuous casting. The casting end time of the current charge is estimated based on the temperature and / or the casting speed of the continuous casting. Based on the estimated casting end time of the current charge, the charge (the next charge) at which the next steelmaking process is executed is performed. ) Is estimated, and the molten steel temperature of the next charge is managed based on the estimated casting start time of the next charge.
[0025]
Further, the method for managing molten steel temperature according to the present invention, in the above-described invention, is based on the estimated casting end time, from the secondary refining process end time of the charge next to the charge in execution of the steelmaking process to the casting end time. Estimating the amount of drop in the molten steel temperature, and determining the target temperature of the molten steel at the end of the secondary refining process of the charge next to the charge during the execution of the steelmaking process, based on the estimated amount of drop in the molten steel temperature. And further comprising:
[0026]
In such a molten steel temperature management method of the present invention, the drop amount of the molten steel temperature from the end time of the secondary refining process of the next charge to the end time of the casting is estimated based on the estimated casting end time of the current charge. The target temperature of the molten steel at the end of the secondary refining process of the next charge is determined based on the estimated amount of the drop in the molten steel temperature.
[0027]
In addition, the molten steel temperature management device according to the present invention performs the secondary refining process while transporting the molten steel after the primary refining process to the tundish with a ladle according to the operation schedule of the steelmaking process created by the schedule creation means. In a temperature control device for obtaining a predetermined pouring temperature of a steelmaking process of continuously drawing and continuously casting as a slab while cooling from a mold while cooling from a mold, a first temperature detecting device detects a temperature of molten steel in the ladle. A sensor, a second sensor for detecting a temperature of molten steel in the tundish, a third sensor for detecting a drawing speed of a slab to be drawn from the mold as a casting speed, and a charge during a steelmaking process. The temperature in the ladle of the molten steel after the completion of the secondary refining process detected by the first sensor and the temperature during continuous casting detected by the second sensor. Means for estimating the casting end time based on the temperature in the tundish and / or the casting speed of the continuous casting detected by the third sensor, and executing the steelmaking process based on the casting end time estimated by the means. Means for estimating the casting start time of the charge next to the middle charge, and means for reviewing the operation schedule of the charge next to the charge during the execution of the steelmaking process created by the schedule creation means based on the estimated casting start time. And means for managing the molten steel temperature of the charge next to the charge during the execution of the steel making process in accordance with the operation schedule reviewed by the means.
[0028]
In the apparatus for managing molten steel temperature of the present invention, a first sensor for detecting the temperature of molten steel in a ladle, a second sensor for detecting the temperature of molten steel in a tundish, and a slab drawn from a mold are provided. Of the temperature of the molten steel in the ladle after completion of the secondary refining of the charge (current charge) during the steel making process, by inputting the detection result of the third sensor for detecting the drawing speed (casting speed) of the steel. Estimate the casting end time of the current charge based on the temperature in the molten steel in the tundish, all or one or two of the casting speed of continuous casting, and based on the estimated casting end time of the current charge. Then, the casting start time of the charge (the next charge) at which the steelmaking process is to be executed next is estimated, and the schedule creation means is made based on the estimated casting start time of the next charge. Review the operations schedule for the next charge, according to this review was operating schedule, to manage the molten steel temperature of the next charge.
[0029]
Further, the molten steel temperature management device according to the present invention, in the above-described invention, based on the estimated casting end time, from the secondary refining process end time of the next charge of the charge during the steelmaking process execution to the casting end time. Means for estimating the amount of drop in molten steel temperature during the period, and the target temperature of the molten steel at the end of the secondary refining process of the charge next to the charge during the execution of the steelmaking process is determined based on the estimated amount of drop in molten steel temperature. Means is further provided.
[0030]
In such a molten steel temperature management device of the present invention, the drop amount of the molten steel temperature from the end time of the secondary refining process of the next charge to the end time of the casting is estimated based on the estimated casting end time of the current charge. The target temperature of the molten steel at the end of the secondary refining process of the next charge is determined based on the estimated drop amount of the molten steel temperature.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments.
[0032]
FIG. 2 is a timing chart showing the principle of the method for controlling molten steel temperature according to the present invention. Hereinafter, the principle of the present invention will be described first with reference to the timing chart of FIG.
[0033]
The top row shows the planned time of the charge (hereinafter referred to as the current charge) during the execution of the steelmaking process, and the next row shows the actual operation time of the current charge. In the present invention, the steelmaking process is performed next to the current charge based on the molten steel temperature after the secondary refining process, the temperature in the tundish during casting, and the casting speed in the actual operation time of the current charge with respect to the planned time of the current charge. Is scheduled (hereinafter, referred to as the next charge) is reviewed. However, any one or two of the molten steel temperature after the secondary refining process, the temperature in the tundish during casting, and the casting speed within the actual operation time of the current charge with respect to the planned time of the current charge described above. You may use only.
[0034]
Specifically, at time t01 when the secondary refining process of the current charge is completed, first, the casting time (actually, the end time) of the current charge is estimated based on the molten steel temperature after the secondary refining process of the current charge, The end time is extended by the time T1. Then, the time required for the secondary refining process (and / or the transport process) is extended so that the start time of the continuous casting process of the next charge coincides with the time extended by the time T1, as indicated by a broken line. A new review time for the new next charge plan is determined.
[0035]
Next, when the current charge is transferred to the continuous casting process, in other words, when the molten steel is transferred to the tundish, the planned time for the next charge is reviewed again based on the temperature of the molten steel in the tundish. Specifically, when the molten steel is transferred from the ladle to the tundish in the current charge, the casting time of the current charge is estimated again based on the temperature of the molten steel in the tundish, and the end time is further extended by the time T2. . Then, the time required for the secondary refining process (and / or the transport process) is extended so that the start time of the continuous casting process of the next charge coincides with the time extended by the time T2. A new next charge plan secondary review time is determined at time t02.
[0036]
In addition, after the current charge is transferred to the continuous casting process, the scheduled time for the next charge is reviewed once more based on the casting speed. Specifically, in the current charge, when the molten steel is transferred to the tundish and continuous casting is started, the casting time of the current charge is estimated once more based on the casting speed, and the end time is further increased by the time T3. Will be extended. Then, the time required for the secondary refining process (and / or the transport process) is extended so that the start time of the continuous casting process of the next charge coincides with the time extended by this time T3. The next charge plan tertiary review time, which is the final plan, is determined at time t03.
[0037]
Then, according to the third review time of the next charge plan, which is the final review time, the amount of temperature drop of the molten steel from the end of the secondary refining process of the next charge to the end of the casting is estimated. A target temperature of the molten steel at the end of the secondary refining process is determined, and temperature management during the secondary refining process is performed to maintain the target temperature.
[0038]
In addition, temperature control in the secondary refining process of the next charge is not performed only according to the final review time of the next charge plan, but the primary review time of the next charge plan and the secondary review time of the next charge plan are calculated separately. It is performed each time it is done.
[0039]
Here, a configuration example of an apparatus for realizing the molten steel temperature management method of the present invention will be described with reference to FIG.
[0040]
As shown in FIG. 1, the ladle 2 has a sensor SN1 for measuring the temperature of the molten steel inside, the tundish 3 has a sensor SN2 for measuring the temperature of the molten steel inside, and the ladle 2 has a sensor SN2 for measuring the temperature of the molten steel inside. Sensors SN3 for measuring the casting speed (drawing speed of the slab 5) are provided on the lower side, and the detection results of these sensors SN1, SN2, and SN3 are used as a computer as a molten steel temperature management device of the present invention. 10 has been entered. In addition, these sensors SN1, SN2, and SN3 themselves can use a known technique.
[0041]
3 and 4 are flowcharts showing processing executed by the computer 10 based on the detection results of the sensors SN1, SN2 and SN3, in other words, the execution procedure of the method of the present invention.
[0042]
First, the computer 10 is on standby until the secondary refining process of the current charge is completed (NO in step S1). When the secondary refining process of the current charge is completed (YES in step S1), the molten steel temperature at that time is measured by a sensor. It is obtained from SN1 and the casting end time of the current charge is estimated based on the result (step S2).
[0043]
FIG. 5 is a flowchart showing a procedure for estimating the casting end time of the current charge performed based on the molten steel temperature at the end of the secondary refining process of the current charge in step S2 described above.
[0044]
First, the computer 10 resets the pouring time (total time required for pouring) to the initial value “0” (Step S21), and then estimates the molten steel temperature during casting (° C.) (Step S22). Specifically, the temperature of the molten steel during casting is obtained by subtracting the “falling amount of the molten steel temperature” from the “actually measured value of the molten steel temperature at the end of the secondary refining process” by the sensor SN1. However, the molten steel temperature drop is an estimated value, and the method of obtaining the temperature drop is performed by a conventionally known method.
[0045]
Next, the calculator 10 calculates the degree of heating of the molten steel (Step S23). Specifically, the molten steel heating degree is obtained by subtracting the “liquidus temperature (solidification temperature)” from the “molten steel temperature during casting” estimated in step S22.
[0046]
Next, the calculator 10 calculates a casting speed (m / min) (Step S24). Specifically, the pouring speed is determined in advance by the molten steel heating degree and the steel type calculated in step S23. However, a specific pouring speed may be set in the initial stage of the pouring of the first cast of the consecutive cast.
[0047]
Next, the calculator 10 calculates the casting weight per unit time (ton / min) (Step S25). Specifically, the casting weight per unit time is obtained from the casting speed, the mold size, and the steel type (specific gravity) calculated in step S24.
[0048]
Next, the computer 10 integrates the casting weight (step S26). Specifically, the integrated value of the cast weight is obtained by adding the “cast weight per unit time” calculated in step S25 to the “cast weight integrated value at the previous calculation”.
[0049]
Here, the calculator 10 determines whether or not the casting of the current charge has been completed in the calculation (step S27). Specifically, if the “integrated casting weight value” integrated in step S26 and the “weight of molten steel at the end of the secondary refining process” match, it means that the casting of the current charge has been completed (step S27). YES). If the pouring is not finished (NO in step S27), the computer 10 extends the pouring time by a unit time (for convenience of calculation, for example, 1 minute, 10 minutes, etc. can be appropriately set) (step S28), and proceeds to step S22. Back.
[0050]
By repeating the above processing, if it is determined that the pouring is completed in step S27 (YES in step S27), the pouring end time of the current charge is set based on the pouring time obtained at that time. It is estimated at time t01.
[0051]
Next, the computer 10 reviews the next charge plan based on the casting end time of the current charge estimated in step S2 (step S3). Specifically, the computer 10 corrects the casting end time of the current charge estimated in step S2 as the continuous casting start time of the next charge, thereby determining the next charge plan primary review time shown in FIG. .
[0052]
When the time for the primary review of the next charge plan is determined in this manner, the time from the end time of the secondary refining process to the casting end time is known, and the computer 10 calculates the temperature drop amount estimation value corresponding to this time. Based on this, the target temperature of the molten steel in the ladle 2 at the end of the secondary refining process of the next charge is determined (step S4).
[0053]
Next, when the casting of the current charge is started (YES in step S5), the computer 10 acquires the temperature of the molten steel at that time, that is, the temperature of the molten steel in the tundish 3 from the sensor SN2, and based on the result, obtains the current temperature. The charge pouring end time is estimated (step S6).
[0054]
FIG. 6 is a flowchart showing a procedure for estimating the casting end time of the current charge performed based on the molten steel temperature during the casting of the current charge in step S6 described above.
[0055]
First, the computer 10 sets the pouring time (total time required for pouring) to be the time that has already passed by the time the molten steel temperature in the tundish 3 is measured by the sensor SN2 (step S61). This is because the processing of step S2 and the like described above have already been performed before the processing of step S6 is started, so that the processing of step S6 is started using the time as an initial value.
[0056]
Next, the computer 10 estimates the temperature (° C.) of the molten steel during casting (step S62). Specifically, the temperature of the molten steel during casting is obtained by subtracting “the amount of temperature drop of the molten steel” from “the actually measured value of the temperature of the molten steel in the tundish 3” by the sensor SN2. However, the molten steel temperature drop is an estimated value, and the method of obtaining the temperature drop is performed by a conventionally known method.
[0057]
Next, the calculator 10 calculates the degree of heating of the molten steel (step S63). Specifically, the degree of heating of the molten steel is obtained by subtracting the “liquidus temperature (solidification temperature)” from the “molten steel temperature during casting” estimated in step S62.
[0058]
Next, the computer 10 calculates a casting speed (m / min) (Step S64). Specifically, the pouring speed is predetermined by the molten steel heating degree and the steel type calculated in step S63. However, a specific pouring speed may be set in the initial stage of the pouring of the first cast of the consecutive cast.
[0059]
Next, the calculator 10 calculates the casting weight per unit time (ton / min) (Step S65). Specifically, the casting weight per unit time is obtained from the casting speed, the mold size, and the steel type (specific gravity) calculated in step S64.
[0060]
Next, the computer 10 integrates the casting weight (step S66). Specifically, the integrated value of the cast weight is obtained by adding the "cast weight per unit time" calculated in step S65 to the "cast weight integrated value at the previous calculation".
[0061]
Here, the computer 10 determines whether or not the casting of the current charge has been completed in the calculation (step S67). Specifically, if the “integrated casting weight value” integrated in step S66 described above matches the “remaining steel amount at the time when the molten steel temperature in the tundish 3 is measured”, the casting of the current charge has been completed. (YES in step S67). If the pouring is not completed (NO in step S67), the computer 10 extends the pouring time by a unit time (step S68), and returns the process to step S62.
[0062]
By repeating the above processing, if it is determined in step S67 that the casting is completed (YES in step S67), the casting end time of the current charge is set based on the casting time obtained at that time. It is estimated at time t02. The computer 10 reviews the next charge plan based on the estimation result (step S7), and determines the target temperature of the molten steel at the end of the secondary refining process of the next charge (step S8).
[0063]
Next, the computer 10 determines whether or not the casting speed of the current charge has been changed (step S9). If the casting speed has been changed (YES in step S9), the computer 10 estimates the casting time required to cast all the steel remaining in the tundish 3 at that time at the changed casting speed (step S9). S10). Based on the casting time estimated in step S10, the casting end time of the current charge is estimated at time t03 described above.
[0064]
Next, the computer 10 reviews the next charge plan again based on the casting end time of the current charge estimated in step S10 (step S11). Specifically, the computer 10 corrects the casting end time of the current charge estimated in step S10 again as the continuous casting start time of the next charge, and thereby determines the next charge plan tertiary review time shown in FIG. I do.
[0065]
When the tertiary review time for the next charge plan is determined in this way, the time from the end time of the tertiary refining process to the casting end time is known, and the computer 10 determines the time based on the estimated temperature drop amount corresponding to this time. Then, the target temperature of the molten steel in the ladle 2 at the end of the secondary refining process of the next charge is determined (step S12).
[0066]
As described above, the computer 10 estimates the pouring end time of the current charge, and determines the primary, secondary, and tertiary next charge plan review times using the estimated pouring end time of the current charge as the pouring start time of the next charge. I do. Note that a conventionally known technique, for example, a technique disclosed in Patent Document 3 as “a steelmaking process operation schedule creation system” can be used for creating a plan including a review.
[0067]
Each time the primary, secondary, and tertiary next charge plan review time is determined, the computer 10 manages the temperature of the molten steel at the end of the secondary refining process of the next charge to be the target temperature. It should be noted that a conventionally known technique can be used for managing the molten steel temperature at the end of the secondary refining process, more specifically, for adjusting the temperature of the molten steel itself.
[0068]
FIG. 7 shows a comparison between the target casting temperature of molten steel and the actual casting temperature (final casting final temperature) between the case according to the method of the present invention as described above and the case according to the conventional techniques disclosed in Patent Documents 1 and 2. It is a graph which shows a result. In FIG. 7, the hatched bar graph shows the case according to the method of the present invention, and the white bar graph shows the case according to the prior art.
[0069]
It should be understood from the results shown in FIG. 7 that the casting temperature of the molten steel can be more accurately controlled with respect to the target value in the case of the present invention than before. Therefore, according to the method of the present invention, continuous casting can be stably performed at a predetermined pouring temperature in continuous casting, and the quality of a continuously cast slab can be improved.
[0070]
【The invention's effect】
As described in detail above, according to the molten steel temperature management method and apparatus of the present invention, even when an error occurs between the planned time and the actual operation time, it is possible to appropriately manage the molten steel temperature. In addition, since continuous casting can be performed at a predetermined casting temperature, it is possible to improve the quality of a slab produced by continuous casting.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration example of a molten steel temperature management device according to the present invention.
FIG. 2 is a timing chart showing the principle of the method for managing molten steel temperature according to the present invention.
FIG. 3 is a part of a flowchart showing a process executed by a computer as a molten steel temperature management device according to the present invention, in other words, an execution procedure of the method of the present invention.
FIG. 4 is the remainder of the flowchart showing the processing executed by the computer as the molten steel temperature management device according to the present invention, in other words, the execution procedure of the method of the present invention.
FIG. 5 is a flowchart showing a procedure for estimating a casting end time of a current charge to be performed based on a molten steel temperature at the end of a secondary refining process of the current charge in the molten steel temperature management device according to the present invention.
FIG. 6 is a flowchart showing a procedure for estimating a casting end time of a current charge performed based on a molten steel temperature during the casting of the current charge in the molten steel temperature management device according to the present invention.
FIG. 7 is a graph showing the results of comparison between a target casting temperature of molten steel and an actual casting temperature (final casting temperature) in the case of the method of the present invention and the case of the conventional technique.
FIG. 8 is a timing chart for specifically explaining a problem of the related art.
[Explanation of symbols]
1 Steelmaking furnace
2 Ladle
3 Tundish
4 mold
5 Cast slabs
10 Computer
SN1 Sensor for measuring molten steel temperature inside ladle
SN2 Sensor for measuring the temperature of molten steel inside a tundish
SN3 Sensor for measuring casting speed

Claims (4)

The secondary refining process is performed while the molten steel after the primary refining process is conveyed to the tundish with a ladle, and is poured into the tundish and continuously drawn from the mold as a slab while being cooled from the mold. In the temperature control method of molten steel for obtaining the casting temperature,
With respect to the charge during the execution of the steelmaking process, the casting end time based on the temperature in the ladle of the molten steel after the secondary refining process, the temperature in the tundish of the molten steel during the continuous casting, and / or the casting speed of the continuous casting. Estimating
Based on the estimated casting end time, estimating the casting start time of the next charge of the charge during the steelmaking process,
Managing the molten steel temperature of the charge next to the charge during the execution of the steel making process based on the estimated casting start time. Based on the estimated casting end time, a step of estimating the amount of decrease in molten steel temperature between the secondary refining process end time of the next charge of the charge during the steelmaking process execution and the casting end time,
Determining a target temperature of the molten steel at the end of the secondary refining process of the charge next to the charge during the execution of the steelmaking process, based on the estimated drop in the molten steel temperature. The method for controlling the temperature of molten steel according to the above. According to the operation schedule of the steelmaking process created by the schedule creation means, the secondary refining process is performed while the molten steel after the primary refining process is transported to the tundish with a ladle, poured into the tundish and cooled from the mold as a slab. In a temperature control device of molten steel for obtaining a predetermined pouring temperature of a steelmaking process of continuously drawing and continuously casting,
A first sensor for detecting a temperature of molten steel in the ladle;
A second sensor for detecting a temperature of molten steel in the tundish;
A third sensor for detecting a drawing speed of a slab to be drawn from the mold as a casting speed,
Regarding the charge during the execution of the steelmaking process, the temperature in the ladle of the molten steel after the completion of the secondary refining process detected by the first sensor, the temperature in the tundish of the molten steel during continuous casting detected by the second sensor. Means for estimating the casting end time based on the temperature of the casting and / or the casting speed of the continuous casting detected by the third sensor;
Based on the casting end time estimated by the means, means for estimating the casting start time of the next charge of the charge during the steelmaking process,
Based on the estimated casting start time, means for reviewing the operation schedule of the charge next to the charge during the execution of the steelmaking process created by the schedule creation means,
Means for managing the molten steel temperature of the charge next to the charge during the execution of the steelmaking process in accordance with the operation schedule reviewed by the means. Based on the estimated casting end time, means for estimating the amount of molten steel temperature drop between the secondary refining process end time of the next charge of the charge during the steelmaking process execution and the casting end time,
And means for determining a target temperature of the molten steel at the end of the secondary refining process of the charge next to the charge during the execution of the steelmaking process, based on the estimated drop in the molten steel temperature. The molten steel temperature control device according to 1.

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