Monitoring Device, Monitoring Method, and Monitoring Program

Abstract

To provide a monitoring device, a monitoring method and a monitoring program that can suppress an increase in the ratio of reducing materials.SOLUTION: A monitoring device 1 has: a stave temperature acquisition unit 21 that acquires a plurality of stave temperatures for a plurality of stave coolers arranged on a furnace wall of a blast furnace at regular time intervals including the period of suspension of the blast furnace; a temperature variation calculation unit 22 that calculates a plurality of temperature variations, which are the variations of temperatures at predetermined positions on the furnace wall of the blast furnace, at the predetermined time intervals, from the plurality of stave temperatures; a stave temperature variation index calculation unit 23 that calculates the stave temperature variation index, which is the standard deviation of the plurality of temperature variations; and an operation abnormality determination unit 24 that determines whether the stave temperature variation index is below a predetermined lower threshold. An initial value of the lower threshold is extracted from the stave temperature variation index during a wind resting period.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a monitoring device, a monitoring method, and a monitoring program for monitoring the operation of a blast furnace.

Background Art

[0002] Achievement of tapping in accordance with the production plan is one of the important objectives of blast furnace operation. In addition to tapping in accordance with the production plan, stabilization of the heat distribution in the blast furnace, reduction of tapping costs, reduction of energy consumption, stabilization of the quality of the hot metal tapped, and reduction of the content rate of impurities such as silicon contained in the hot metal are also important issues in blast furnace operation. In order to solve these problems, it is desirable to operate the blast furnace stably.

[0003] In order to operate the blast furnace stably, a technique for determining the stability of the blast furnace using the standard deviation from the amount of change in the stave temperature over a predetermined time in a two-dimensional plane defined by the circumferential direction and the height direction of the furnace wall of the blast furnace is known (see, for example, Patent Document 1). In the technique described in Patent Document 1, since the presence or absence of an abnormal operation of the blast furnace is determined based on the amount of change in the stave temperature at predetermined time intervals, even when the temperature of the cooling water flowing through the cooling pipes of the stave cooler changes due to a change in the air temperature, it is possible to accurately determine the presence or absence of an abnormal operation of the blast furnace.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technique described in Patent Document 1, the first threshold value and the second threshold value, which are the upper and lower threshold values used to determine the presence or absence of abnormal operation of the blast furnace, are set by an operator referring to past blast furnace operation data based on his or her own experience. In the technique described in Patent Document 1, since the first threshold value and the second threshold value are set based on the operator's experience, they may not be appropriate values and may be set to values higher or lower than the appropriate values.

[0006] For example, when the second threshold value, which is the lower threshold value, is set to a higher value, the reducing agent may be excessively charged into the blast furnace in response to the standard deviation falling below the second threshold value, and the coke ratio, that is, the reducing agent ratio, may increase, leading to unstable operation of the blast furnace. Also, when the second threshold value, which is the lower threshold value, is set to a lower value, there is a risk of delay in detecting the inactivity of the furnace wall section. If the detection of the generation and growth of the deposits adhering to the wall surface of the blast furnace is delayed, the large-grown deposits may peel off from the wall surface of the blast furnace, disturbing the filling structure inside the blast furnace and causing fluctuations in the gas flow inside the blast furnace. When the gas flow inside the blast furnace fluctuates, the blast furnace operation becomes unstable, such as fluctuations in the shaft pressure, and there is a risk of significantly increasing the reducing agent ratio and increasing the tapping cost.

[0007] Therefore, an object of the present invention is to provide a monitoring device, a monitoring method, and a monitoring program capable of suppressing an increase in the reducing agent ratio.

Means for Solving the Problems

[0008] The present invention for solving such problems mainly includes the following monitoring device, monitoring method, and monitoring program. (1) A stave temperature acquisition unit that acquires a plurality of stave temperatures at regular time intervals for a plurality of stave coolers arranged on the furnace wall of the blast furnace, including the period of blast furnace shutdown; A temperature change amount calculation unit that calculates a plurality of temperature change amounts, which are the amounts of change in temperature at a predetermined position on the furnace wall of the blast furnace at a predetermined time interval, from the plurality of stave temperatures; A stave temperature fluctuation index calculation unit that calculates a stave temperature fluctuation index, which is the standard deviation of the plurality of temperature change amounts; a determination unit that determines whether or not the stave temperature fluctuation index is equal to or less than a predetermined lower limit threshold value; The initial value of the lower limit threshold value is extracted from the stave temperature fluctuation index during the blast furnace shutdown period, and the monitoring device is characterized by this. (2) The monitoring device according to (1), wherein the initial value of the lower limit threshold value is a value estimated to be the maximum value of the stave temperature fluctuation index during a period when it is estimated that a plurality of stave coolers are not affected by the blast during the blast furnace shutdown period. (3) The monitoring device according to (2), wherein the initial value of the lower limit threshold value is the stave temperature fluctuation index corresponding to the minimum value between the first maximum value at which the relative frequency of the stave temperature fluctuation index calculated during a period including the blast furnace shutdown period is the maximum, and the second maximum value at which the relative frequency is the next largest after the first maximum value. (4) Based on the stave temperature fluctuation index, it is determined whether or not furnace wall part inactivity has occurred, When it is determined that furnace wall part inactivity has occurred, the monitoring device according to any one of (1) to (3) further includes a lower limit threshold value changing unit that changes the maximum value of the stave temperature fluctuation index in a period including at least the blast furnace shutdown period in the furnace wall part inactivity region to the lower limit threshold value. (5) The monitoring device according to (4), wherein the lower limit threshold value changing unit sets the maximum value of the stave temperature fluctuation index during the blast furnace shutdown period in the furnace wall part inactivity region as the lower limit threshold value. (6) For a plurality of stave coolers arranged on the furnace wall of the blast furnace, a plurality of stave temperatures are acquired at regular time intervals including the blast furnace shutdown period of the blast furnace, From the plurality of stave temperatures, a plurality of temperature change amounts, which are the amounts of change in temperature at a predetermined position on the furnace wall of the blast furnace at a predetermined time interval, are calculated, A stave temperature fluctuation index, which is the standard deviation of the plurality of temperature change amounts, is calculated, It includes determining whether or not the stave temperature fluctuation index is equal to or less than a predetermined lower limit threshold value, The initial value of the lower limit threshold value is extracted from the stave temperature fluctuation index during the blast furnace shutdown period, and the monitoring method is characterized by this. (7) Obtain the temperatures of a plurality of stave coolers arranged on the furnace wall of the blast furnace at regular time intervals, including the period when the blast furnace is shut down. Calculate a plurality of temperature change amounts, which are the amounts of change in temperature at a predetermined position on the furnace wall of the blast furnace at a predetermined time interval, from the plurality of stave temperatures. Calculate a stave temperature fluctuation index, which is the standard deviation of the plurality of temperature change amounts. Cause a computer to execute a process of determining whether the stave temperature fluctuation index is less than or equal to a predetermined lower limit threshold. A monitoring program, characterized in that an initial value of the lower limit threshold is extracted from the stave temperature fluctuation index during the shutdown period.

Advantages of the Invention

[0009] The monitoring device, monitoring method, and monitoring program according to the present invention can suppress an increase in the reducing agent ratio.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0011] Hereinafter, a monitoring device, a monitoring method, and a monitoring program will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments.

[0012] (Overview of the Monitoring Device According to the Embodiment) The monitoring device according to the embodiment uses, as a lower threshold for determining the presence or absence of abnormal operation of the blast furnace, a value determined from the standard deviation during the blast furnace shutdown period, so that the lower threshold can be set with a more appropriate value than setting the lower threshold based on the experience of the operator.

[0013] (Configuration and Function of the Monitoring Device According to the Embodiment) FIG. 1 is a diagram showing a blast furnace operation system including the monitoring device according to the first embodiment.

[0014] The blast furnace operation system 100 includes a monitoring device 1 and a plurality of stave temperature sensors 101 that detect the stave temperatures of a plurality of stave coolers arranged over the entire furnace wall of the blast furnace 110. The plurality of stave temperature sensors 101 are connected to the monitoring device 1 via a LAN (Local Area Network) 102. The stave temperature sensors 101 may be arranged one by one for each stave cooler, or a plurality of them may be arranged for each stave cooler.

[0015] The monitoring device 1 according to the embodiment includes a communication unit 11, a storage unit 12, an input unit 13, an output unit 14, and a processing unit 20. The communication unit 11, the storage unit 12, the input unit 13, the output unit 14, and the processing unit 20 are connected to each other via a bus 15. The monitoring device 1 is a monitoring control device that determines and changes a lower limit threshold value used when determining the presence or absence of an abnormal operation of a blast furnace, and determines whether or not the calculated stave temperature fluctuation index is less than or equal to the lower limit threshold value.

[0016] The communication unit 11 has a wired communication interface circuit such as Ethernet (registered trademark). The communication unit 11 communicates with a plurality of stave temperature sensors 101 and a host control device (not shown) via a LAN 102.

[0017] The storage unit 12 includes, for example, at least one of a semiconductor storage device, a magnetic tape device, a magnetic disk device, or an optical disk device. The storage unit 12 stores an operating system program, a driver program, an application program, data, etc. used in the processing by the processing unit 20. For example, the storage unit 12 stores, as an application program, a monitoring program for causing the processing unit 20 to execute a monitoring process for monitoring the operation of the blast furnace. Further, the storage unit 12 stores an initial value determination program for causing the processing unit 20 to execute an initial value determination process for determining an initial value of the lower limit threshold value used in the monitoring process. Further, the storage unit 12 stores a lower limit threshold value change program for causing the processing unit 20 to execute a lower limit threshold value change process for changing the lower limit threshold value used in the monitoring process. The monitoring program, the initial value determination program, and the lower limit threshold value change program may be installed in the storage unit 12 from a computer-readable portable recording medium such as a CD-ROM or a DVD-ROM using a known setup program or the like.

[0018] Also, the storage unit 12 stores various data used in the monitoring process. Furthermore, the storage unit 12 may temporarily store temporary data related to a predetermined process.

[0019] The input unit 13 can be any device as long as it can input data. For example, it can be a touch panel, a keyboard, etc. An operator (not shown) can use the input unit 13 to input characters, numbers, symbols, etc. When the input unit 13 is operated by the operator, it generates a signal corresponding to the operation. Then, the generated signal is supplied to the processing unit 20 as an instruction from the operator.

[0020] The output unit 14 can be any device as long as it can display videos, images, etc. For example, it can be a liquid crystal display or an organic EL (Electro-Luminescence) display, etc. The output unit 14 displays a video corresponding to the video data supplied from the processing unit 20, an image corresponding to the image data, etc. Also, the output unit 14 may be an output device that prints videos, images, characters, etc. on a display medium such as paper.

[0021] The processing unit 20 has one or a plurality of processors and their peripheral circuits. The processing unit 20 comprehensively controls the overall operation of the monitoring device 1 and is, for example, a CPU. The processing unit 20 executes processing based on programs (driver programs, operating system programs, application programs, etc.) stored in the storage unit 12. Also, the processing unit 20 can execute a plurality of programs (application programs, etc.) in parallel.

[0022] The processing unit 20 has a stable temperature acquisition unit 21, a temperature change amount calculation unit 22, a stable temperature fluctuation index calculation unit 23, an operation abnormality determination unit 24, an alarm signal output unit 25, an initial value determination unit 26, and a lower limit threshold change unit 27. Each of these units is a functional module realized by a program executed by a processor included in the processing unit 20. Alternatively, each of these units may be implemented in the monitoring device 1 as firmware.

[0023] (Monitoring Process by the Monitoring Device According to the Embodiment) FIG. 2 is a flowchart of a monitoring process for operating the blast furnace while the monitoring device 1 monitors the presence or absence of an abnormal operation of the blast furnace 110. The monitoring process shown in FIG. 2 is mainly executed by the processing unit 20 in cooperation with each element of the monitoring device 1 based on a program stored in the storage unit 12 in advance.

[0024] First, the stave temperature acquisition unit 21 acquires a plurality of stave temperatures from the plurality of stave coolers arranged on the furnace wall of the blast furnace 110 via the LAN 102 from the stave temperature sensors 101 (S101). There may be stave coolers where a plurality of stave temperature sensors 101 are arranged and stave coolers where no stave temperature sensors 101 are arranged. The stave coolers, the stave temperature sensors 101, and the stave temperatures do not necessarily have a one-to-one correspondence. However, when one stave temperature sensor is arranged for one stave cooler and one stave temperature is acquired, the plurality of stave temperatures can be stored in the storage unit 12 in association with the identification numbers of the corresponding stave coolers. The stave temperature acquisition unit 21 stores each of the acquired plurality of stave temperatures in the storage unit 12 in association with the arrangement position of the stave temperature sensor 101 or the identification number of the corresponding stave cooler. The stave temperature acquisition unit 21 acquires the stave temperature at regular time intervals, and the time interval may be, for example, 1 second, 1 minute, or 5 minutes, etc.

[0025] Next, the temperature change amount calculation unit 22 calculates a plurality of temperature change amounts indicating the change amounts at predetermined time intervals for each of the plurality of stave temperatures acquired in the process of S101 (S102). First, for each of the plurality of stave temperatures acquired in the process of S101, the temperature change amount calculation unit 22 calculates the temperature change amount at a predetermined time interval from the difference between the stave temperature acquired in the monitoring process before the predetermined time interval and the stave temperature acquired in the current monitoring process. The temperature change amount calculation unit 22 stores each of the calculated temperature change amounts in the storage unit 12 in association with the arrangement position of the stave temperature sensor 101 or the identification number of the corresponding stave cooler. Note that the predetermined time interval can be constant, and may or may not be the same as the time interval for acquiring the stave temperature. For example, it may be 1 minute or 5 minutes. Further, in calculating the temperature change amount, a weighting coefficient for considering the influence degree of the stave temperature can be arbitrarily set as disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-317217, and can be set using, for example, a forgetting coefficient for defining the strength of forgetting.

[0026] Next, the temperature change amount calculation unit 22 calculates an isothermal line of the temperature change amount in a two-dimensional plane defined by the circumferential direction and the height direction for the furnace wall of the blast furnace 110. The temperature change amount calculation unit 22 calculates an isothermal line of the temperature change amount in the two-dimensional plane from the stave temperature change amount calculated in the process of S201 and the arrangement position of the stave temperature sensor 101 corresponding to each of the calculated stave temperature change amounts. The temperature change amount calculation unit 22 can calculate an isothermal line by an isothermal line search method described in, for example, Japanese Patent Application Laid-Open No. 2002-194405 and Japanese Patent Application Laid-Open No. 2002-317217.

[0027] FIG. 3(a) is a diagram showing an example of an isothermal line of the temperature change amount in a two-dimensional plane defined by the circumferential direction and the height direction for the furnace wall of the blast furnace 110 calculated by the temperature change amount calculation unit 22. In FIG. 3(a), the horizontal axis indicates the circumferential direction of the blast furnace 110, and the vertical axis indicates the height direction of the blast furnace 110.

[0028] Next, the temperature change amount calculation unit 22 estimates the temperature change amounts at a plurality of temperature estimation points arranged in a grid pattern within a two-dimensional plane defined by the circumferential direction and the height direction of the furnace wall of the blast furnace 110. The temperature change amount is, for example, the change amount of the temperature that has changed over a predetermined time such as 5 minutes. The temperature change amount calculation unit 22 estimates the temperature change amount at the temperature estimation point from the positional relationship between the calculated isothermal line and the temperature estimation point. The temperature change amount calculation unit 22 estimates the temperature change amount at the temperature estimation point by a known interpolation method such as polynomial interpolation or spline interpolation, for example.

[0029] FIG. 3(b) is a diagram showing an example of temperature estimation points at which the temperature change amount is estimated by the temperature change amount calculation unit 22. In FIG. 3(b), the horizontal axis represents the circumferential direction of the blast furnace 110, and the vertical axis represents the height direction of the blast furnace 110. In FIG. 3(b), the temperature estimation points are indicated by white circles arranged at the intersections of the broken lines extending in the circumferential direction and the height direction of the blast furnace. In FIG. 3(b), the temperature estimation points are arranged in a 12×7 grid pattern.

[0030] Next, the stave temperature fluctuation index calculation unit 23 calculates a stave temperature fluctuation index, which is the standard deviation of the plurality of temperature change amounts calculated in the process of S102 (S103). The stave temperature fluctuation index calculation unit 23 stores the calculated stave temperature fluctuation index in the storage unit 12. The stave temperature fluctuation index calculation unit 23 may store the calculated stave temperature fluctuation index in the storage unit 12 every time the stave temperature fluctuation index is calculated. Further, the stave temperature fluctuation index calculation unit 23 may store the average value of the stave temperature fluctuation indexes calculated over a certain period in the storage unit 12. For example, the stave temperature fluctuation index calculation unit 23 may store the average value of the stave temperature fluctuation indexes calculated every 5 minutes over 60 minutes in the storage unit 12 as the stave temperature fluctuation index.

[0031] Next, the operation abnormality determination unit 24 determines whether the stab temperature fluctuation index stored in the storage unit 12 is less than or equal to the lower limit threshold value (S104). The lower limit threshold value is determined and changed by executing the initial value determination process and the lower limit threshold value change process described with reference to FIGS. 4 to 6, and is stored in the storage unit 12. When the operation abnormality determination unit 24 determines that the stab temperature fluctuation index stored in the storage unit 12 is less than or equal to the lower limit threshold value (S104 - YES), it stores an operation abnormality flag indicating that the lower part of the furnace has become inert in the storage unit 12 (S105).

[0032] Next, the alarm signal output unit 25 determines whether an operation abnormality flag is stored in the storage unit 12 (S106). When the alarm signal output unit 25 determines that a second operation abnormality flag is stored in the storage unit 12 (S106 - YES), it outputs an alarm signal indicating that the thickness of the deposit attached to the furnace wall of the blast furnace 110 has increased (S107).

[0033] (Initial value determination process by the monitoring device according to the embodiment) FIG. 4 is a flowchart of an initial value determination process in which the monitoring device 1 determines the initial value of the lower limit threshold value used in the process of S106 shown in FIG. 2. The initial value determination process shown in FIG. 4 is mainly executed by the processing unit 20 in cooperation with each element of the monitoring device 1 based on a program stored in the storage unit 12 in advance. Since the processes of S201 to S203 are the same as the processes of S101 to S103, detailed description thereof is omitted here.

[0034] Subsequent to the process of S203, the initial value determination unit 26 determines whether an initial value determination instruction indicating that the initial value of the lower limit threshold value is to be determined has been input (S204). The initial value determination unit 26 determines whether an initial value determination instruction has been input by the operator via the input unit 13. The processes of S201 to S204 are repeated until it is determined by the initial value determination unit 26 that the initial value determination instruction has been input (S204 - YES). By repeating the processes of S201 to S204, the stab temperature fluctuation index is repeatedly calculated, and the calculated stab temperature fluctuation index is stored in the storage unit 12.

[0035] When the initial value determination unit 26 determines that an initial value determination instruction has been input (S204 - YES), it acquires the stave temperature fluctuation index calculated during an initial value extraction period that includes at least one tuyere - stoppage period, which is the period during which the blast furnace 110 is on tuyere - stoppage (S205). The initial value determination unit 26 acquires the stave temperature fluctuation index calculated during the initial value extraction period in response to the initial value extraction period being input by the operator via the input unit 13. The tuyere - stoppage period of the blast furnace 110 is the period from when the blast from the tuyere stops to when the blast from the tuyere starts.

[0036] Next, the initial value determination unit 26 determines an initial value of a lower limit threshold value used when determining the presence or absence of abnormal operation of the blast furnace 110 based on the stave temperature fluctuation index calculated during the initial value extraction period (S206). The initial value determination unit 26 determines, as the initial value of the lower limit threshold value, the maximum value and the estimated value of the stave temperature fluctuation index during a period in the tuyere - stoppage period when it is estimated that a plurality of stave coolers are not affected by the blast. The period estimated to be not affected by the blast is, for example, a period when the fluctuation index is 0.0005 or less.

[0037] FIG. 5(a) is a diagram showing a first example of the initial value extraction period, FIG. 5(b) is a diagram showing a second example of the initial value extraction period, and FIG. 5(c) is a diagram showing a third example of the initial value extraction period. In FIGS. 5(a) - 5(c), the horizontal axis represents time, and the vertical axis represents the stave temperature fluctuation index. Also, in FIGS. 5(a) - 5(c), the double - headed arrow A indicates the tuyere - stoppage period, and the double - headed arrow B indicates the period when it is estimated that a plurality of stave coolers are not affected by the blast.

[0038] In the first example shown in FIG. 5(a), the tuyere - stoppage period is 21 hours from 3:00 to 24:00, and the period when it is estimated that a plurality of stave coolers are not affected by the blast is 20 hours from 4:00 to 24:00. In the first example, a plurality of stave coolers are not affected by the blast relatively early, about 2 hours after the start of the tuyere - stoppage period. The maximum value of the stave temperature fluctuation index during the period when it is estimated that a plurality of stave coolers are not affected by the blast is about 0.0005.

[0039] In the second example shown in FIG. 5(b), the blast-off period is 21 hours from 3:00 to 24:00, and the period during which it is estimated that a plurality of stave coolers are not affected by the blast is 15 hours from 9:00 to 24:00. In the second example, the plurality of stave coolers stop being affected by the blast at a relatively late time, about 9 hours after the start of the blast-off period. The maximum value of the stave temperature fluctuation index during the period when it is estimated that the plurality of stave coolers are not affected by the blast is about 0.0004.

[0040] In the third example shown in FIG. 5(c), the blast-off period is 27 hours from 6:00 to 9:00 the next day, and the period during which it is estimated that a plurality of stave coolers are not affected by the blast is 24 hours from 9:00 to 9:00 the next day. In the third example, the plurality of stave coolers stop being affected by the blast at a relatively fast time, about 3 hours after the start of the blast-off period. The maximum value of the stave temperature fluctuation index during the period when it is estimated that the plurality of stave coolers are not affected by the blast is about 0.0003.

[0041] The length of time from the start of the blast-off period until a plurality of stave coolers stop being affected by the blast varies depending on the furnace condition of the blast furnace 110, the position of the stave coolers, etc. Therefore, it is not easy to estimate the period during which a plurality of stave coolers are not affected by the blast. Hereinafter, a method for the initial value determination unit 26 to estimate the maximum value of the stave temperature fluctuation index during the period when it is estimated that a plurality of stave coolers are not affected by the blast will be described.

[0042] The initial value determination unit 26 extracts the stave temperature fluctuation index corresponding to the minimum value between the first maximum value with the highest relative frequency of the calculated stave temperature fluctuation index and the second maximum value with the next highest relative frequency after the first maximum value. The initial value determination unit 26 estimates the extracted stave temperature fluctuation index as the maximum value of the stave temperature fluctuation index during the period when a plurality of stave coolers are not affected by the blast and determines it as the initial value of the lower limit threshold.

[0043] FIG. 6 is a diagram for explaining the process of determining the initial value of the lower limit threshold shown in S206. In FIG. 6, the horizontal axis shows the stable temperature fluctuation index in logarithmic display, and the vertical axis shows the relative frequency obtained by normalizing the number of stable temperature fluctuation indices calculated from the stable temperature detected during the initial value extraction period.

[0044] First, the initial value determination unit 26 extracts the stable temperature fluctuation index corresponding to the first maximum value with the highest relative frequency of the stable temperature fluctuation index. In the example shown in FIG. 4, "0.0002" corresponding to the relative frequency of "1.0" indicated by arrow C in FIG. 6 is extracted, and the extracted stable temperature fluctuation index is stored in the storage unit 12 as the stable temperature fluctuation index corresponding to the first maximum value.

[0045] Next, the initial value determination unit 26 extracts the stable temperature fluctuation index corresponding to the second maximum value whose relative frequency of the stable temperature fluctuation index is the next largest after the first maximum value. In the example shown in FIG. 4, "0.001" corresponding to the relative frequency of "0.8" indicated by arrow D in FIG. 6 is extracted, and the extracted stable temperature fluctuation index is stored in the storage unit 12 as the stable temperature fluctuation index corresponding to the minimum value.

[0046] Then, the initial value determination unit 26 determines the stable temperature fluctuation index corresponding to the minimum value between the first maximum value and the second maximum value as the initial value of the lower limit threshold. The initial value determination unit 26 extracts the stable temperature fluctuation index "0.0035" with the minimum relative frequency between the stable temperature fluctuation index "0.0002" corresponding to the first maximum value and the stable temperature fluctuation index "0.001" corresponding to the second maximum value. The initial value determination unit 26 stores the extracted stable temperature fluctuation index "0.0035" with the minimum relative frequency in the storage unit 12 as the initial value of the lower limit threshold.

[0047] As described with reference to FIG. 6, the monitoring device 1 determines the stave temperature fluctuation index corresponding to the minimum value between the first maximum value with the maximum relative frequency and the second maximum value with the magnitude next to the first maximum value as the initial value of the lower limit threshold. One of the first maximum value and the second maximum value is the stave temperature fluctuation index during the blow-off period, and the other of the first maximum value and the second maximum value is presumed to be the stave temperature fluctuation index during the blow-off period. When shifting to the blow-off period, since the stave temperature fluctuation index rapidly decreases, the relative frequency of the stave temperature fluctuation index during the shift to the blow-off period is smaller than the relative frequencies of the stave temperature fluctuation index before the shift to the blow-off period and after the shift to the blow-off period. When shifting to the blow-off period, the gas flow around the stave cooler suddenly stagnates, and the amount of temperature change of the cooling water flowing through the stave cooler becomes small, so the stave temperature fluctuation index rapidly decreases when shifting to the blow-off period. By determining the stave temperature fluctuation index corresponding to the minimum value between the first maximum value and the second maximum value as the initial value of the lower limit threshold, it is possible to determine the stave temperature fluctuation index close to the maximum value of the stave temperature fluctuation index during the period not affected by the blowing as the initial value of the lower limit threshold.

[0048] (Lower limit threshold change process by the monitoring device according to the embodiment) FIG. 7 is a flowchart of a lower limit threshold change process in which the monitoring device 1 changes the lower limit threshold used in the process of S106 shown in FIG. 2. The lower limit threshold change process shown in FIG. 7 is mainly executed by the processing unit 20 in cooperation with each element of the monitoring device 1 based on a program stored in the storage unit 12 in advance.

[0049] The monitoring device 1 changes the lower limit threshold based on the correlation between the stave temperature fluctuation index and the furnace wall part inactivity. The furnace wall part inactivity is a state in which gas does not come into contact with the stave cooler disposed near the furnace wall of the blast furnace 110. The causes of the furnace wall part inactivity include the phenomenon that powder raw materials penetrate between the stave cooler and the charge located in the front, or the phenomenon that the raw materials that have been softened and then re-solidified adhere to the front of the stave cooler. In addition, the phenomena that cause the furnace wall part inactivity may occur in combination, and a strong deposit may be generated on the front of the stave cooler, resulting in the occurrence of the furnace wall part inactivity.

[0050] When the furnace wall part inactivity occurs, the stave temperature decreases and the heat load decreases. The heat load is the amount of heat removed from the cooling water flowing through the cooling pipes of the stave cooler, and is calculated from the temperature rise of the cooling water flowing through the cooling pipes of the stave cooler. As the furnace wall part inactivity occurs and the stave temperature decreases, the amount of change in the stave temperature decreases and the stave temperature fluctuation index decreases. By accurately detecting the decrease in the stave temperature fluctuation index, the occurrence of the furnace wall part inactivity can be accurately detected.

[0051] The processes of S301 to S303 are the same as those of S101 to S103, so detailed descriptions are omitted here. After the process of S303, the lower limit threshold change unit 27 determines whether a lower limit threshold change instruction indicating that the lower limit threshold is to be changed has been input (S304). The lower limit threshold change unit 27 determines whether a lower limit threshold change instruction has been input by the operator via the input unit 13. The processes of S301 to S304 are repeated until it is determined by the lower limit threshold change unit 27 that a lower limit threshold change instruction has been input (S304 - YES). By repeating the processes of S301 to S304, the stave temperature fluctuation index is repeatedly calculated, and the calculated stave temperature fluctuation index is stored in the storage unit 12.

[0052] When the lower limit threshold change unit 27 determines that a lower limit threshold change instruction has been input (S304 - YES), it acquires the stave temperature fluctuation index calculated during the furnace wall inactive determination period including at least one blow - out period of the blast furnace 110 (S305). The lower limit threshold change unit 27 acquires the stave temperature fluctuation index calculated during the furnace wall inactive determination period in response to the furnace wall inactive determination period being input by the operator via the input unit 13.

[0053] Next, the lower limit threshold change unit 27 determines whether furnace wall inactivity has occurred based on the stave temperature fluctuation index acquired in the process of S305 (S306).

[0054] The lower limit threshold change unit 27 compares the stave temperature fluctuation index during the blow - out period with the stave temperature fluctuation index outside the blow - out period to determine whether furnace wall inactivity has occurred. For example, in the lower limit threshold change unit 27, when in any region of the blast furnace 110, the order of the maximum value of the stave temperature fluctuation index outside the blow - out period is the same as the order of the maximum value of the stave temperature fluctuation index during the blow - out period, in this case, it is determined that furnace wall inactivity has occurred. Also, the lower limit threshold change unit 27 may determine that furnace wall inactivity has occurred based on the information input via the input unit 13 by the operator who has confirmed that furnace wall inactivity has occurred.

[0055] When it is determined by the lower limit threshold change unit 27 that furnace wall inactivity has not occurred (S306 - NO), the lower limit threshold change process ends.

[0056] When the lower limit threshold change unit 27 determines that furnace wall inactivity has occurred (S306 - YES), it extracts the maximum value of the stave temperature fluctuation index in the maximum value extraction period including at least the blow - out period in the furnace wall inactive region where furnace wall inactivity has occurred (S307).

[0057] FIG. 8 is a diagram for explaining the process of S307. In FIG. 8, the horizontal axis represents time, and the vertical axis represents the stave temperature fluctuation index. Also, in FIG. 8, the double-headed arrow A indicates the blowing stop period, and the double-headed arrow E indicates the maximum value extraction period.

[0058] In the example shown in FIG. 8, the blowing stop period is 27 hours from 6:00 to 9:00 the next day, and the maximum value extraction period is 51 hours from 18:00 the previous day to 21:00 the next day. In the example shown in FIG. 8, the maximum value extraction period is the blowing stop period, as well as 12 hours before the start of the blowing stop period and 12 hours after the end of the blowing stop period. In the present embodiment, it is sufficient to include at least the blowing stop period, and it may include a period that is not the blowing stop period (for example, 12 hours before the start of the blowing stop period and 12 hours after the end of the blowing stop period). Also, as the period that is not the blowing stop period, 12 hours before the start of the blowing stop period and 12 hours after the end of the blowing stop period are used, but it is not limited to 12 hours and may be set as appropriate.

[0059] Next, the lower limit threshold changing unit 27 changes the lower limit threshold stored in the storage unit 12 so that the maximum value of the stave temperature fluctuation index extracted in the process of S307 becomes the lower limit threshold (S308), and the lower limit threshold changing process ends.

[0060] (Function and Effect of the Monitoring Device According to the Embodiment) The monitoring device 1 can determine the initial value of the lower limit threshold from the stave temperature fluctuation index during the blowing stop period of the blast furnace 110, detect the lower part inactivity of the furnace at an appropriate lower limit threshold, and determine the presence or absence of an operation abnormality in the blast furnace 110. If the lower part inactivity of the furnace cannot be detected early, the gas flow in the blast furnace 101 fluctuates, the shaft pressure fluctuates, and the operation of the blast furnace becomes unstable. When the operation of the blast furnace becomes unstable, the amount of coke used increases, the reduction material ratio increases significantly, and the tapping cost increases. On the other hand, in the blast furnace operation device 1, the inactivity of the furnace wall part can be detected early, so the fluctuation of the gas flow in the blast furnace 101 is suppressed, and the fluctuation of the shaft pressure is suppressed. As a result, the operation of the blast furnace is stabilized. Therefore, in the monitoring device 1, it is not necessary to increase the amount of coke used, and the increase in the reduction material ratio and the increase in the tapping cost are suppressed.

[0061] While the blast furnace 110 is on standby, since the gas by blowing is not blown into the furnace of the blast furnace 110, the temperature inside the furnace of the blast furnace 110 basically does not change, the change amount of the stave temperature is small, and the stave temperature fluctuation index approaches zero infinitely. While the blast furnace 110 is on standby, the stave temperature fluctuation index does not change due to the temperature change inside the furnace of the blast furnace 110, but fluctuates slightly due to the temperature change of the cooling water flowing through the cooling pipes of the stave cooler and the slight movement of the charged materials charged into the furnace of the blast furnace 110. The monitoring device 1 can determine an appropriate lower limit threshold value by determining the initial value of the lower limit threshold value from the stave temperature fluctuation index during the standby period of the blast furnace 110.

[0062] More specifically, the monitoring device 1 uses, as the initial value of the lower limit threshold value, the maximum value and the estimated value of the stave temperature fluctuation index during the period when it is estimated that the plurality of stave coolers of the blast furnace 110 are not affected by the blowing from the tuyere during the standby period. By using the maximum value of the stave temperature fluctuation index during the period when it is estimated that the plurality of stave coolers are not affected by the blowing from the tuyere as the initial value of the lower limit threshold value, the maximum value during the period not affected by the blowing can be set as the initial value of the lower limit threshold value.

[0063] Further, the monitoring device 1 can use, as the lower limit threshold value, the stave temperature fluctuation index corresponding to the measured value in which the inactivity of the furnace wall part has occurred by changing the maximum value of the stave temperature fluctuation index during the period including the standby period in the inactivity region of the furnace wall part to the lower limit threshold value.

[0064] By setting the maximum value during the period not affected by the blowing as the initial value of the lower limit threshold value, the monitoring device 1 can achieve operation stability while pursuing more severe operation conditions such as reduction of the reducing agent ratio.

[0065] FIG. 9 is a diagram showing the ratio of the charged amount of the reducing agent in the technology described in Patent Document 1 to the charged amount of the reducing agent in the technology according to the present invention.

[0066] In the technology according to the present invention, the amount of reducing material charged into the blast furnace 110 can be reduced by about 5% compared to the amount of reducing material charged into the blast furnace 110 in the technology described in Patent Document 1.

Explanation of Signs

[0067] 1 Monitoring device 21 Stave temperature acquisition unit 22 Temperature change amount calculation unit 23 Stave temperature fluctuation index calculation unit 24 Operation abnormality determination unit 25 Alarm signal output unit 26 Initial value determination unit 27 Lower limit threshold change unit

Claims

1. A stave temperature acquisition unit that acquires a plurality of stave temperatures for a plurality of stave coolers arranged on the furnace wall of a blast furnace at regular time intervals including the period of blast furnace shutdown; A temperature change amount calculation unit that calculates a plurality of temperature change amounts, which are the amounts of change in temperature at a predetermined position on the furnace wall of the blast furnace at a predetermined time interval, from the plurality of stave temperatures; A stave temperature fluctuation index calculation unit that calculates a stave temperature fluctuation index, which is the standard deviation of the plurality of temperature change amounts; An operation abnormality determination unit that determines whether or not the stave temperature fluctuation index is less than or equal to a predetermined lower limit threshold value, and has: The initial value of the lower limit threshold value is extracted from the stave temperature fluctuation index during the period of blast furnace shutdown, and the lower limit threshold value is changed when it is determined that furnace wall part inactivity has occurred. A monitoring device characterized by this.

2. The initial value of the lower limit threshold value is a value estimated to be the maximum value of the stave temperature fluctuation index during a period in which it is estimated that the plurality of stave coolers are not affected by blowing during the period of blast furnace shutdown. The monitoring device according to claim 1.

3. The initial value of the lower limit threshold value is the stave temperature fluctuation index corresponding to the minimum value between a first maximum value at which the relative frequency of the stave temperature fluctuation index calculated during a period including the period of blast furnace shutdown is the maximum, and a second maximum value at which the relative frequency is the next largest after the first maximum value. The monitoring device according to claim 2.

4. Based on the stave temperature fluctuation index, it is determined whether or not furnace wall part inactivity has occurred, and When it is determined that furnace wall part inactivity has occurred, it further has a lower limit threshold value change unit that changes the maximum value of the stave temperature fluctuation index in a period including at least the period of blast furnace shutdown in the furnace wall part inactivity region to the lower limit threshold value. The monitoring device according to any one of claims 1 to 3.

5. The lower limit threshold value change unit sets the maximum value of the stave temperature fluctuation index during the period of blast furnace shutdown in the furnace wall part inactivity region as the lower limit threshold value. The monitoring device according to claim 4.

6. A plurality of stave temperatures for a plurality of stave coolers arranged on the furnace wall of a blast furnace are acquired at regular time intervals including the period of blast furnace shutdown, and From the plurality of stave temperatures, a plurality of temperature change amounts, which are the amounts of change in temperature at a predetermined position on the furnace wall of the blast furnace at a predetermined time interval, are calculated. Calculating a stave temperature fluctuation index which is the standard deviation of the plurality of temperature change amounts; Determining whether or not the stave temperature fluctuation index is less than or equal to a predetermined lower limit threshold value, and including this; The initial value of the lower limit threshold value is extracted from the stave temperature fluctuation index during the blast furnace shutdown period, and the lower limit threshold value is changed when it is determined that furnace wall part inactivity has occurred. A monitoring method characterized by this.

7. For a plurality of stave coolers arranged on the furnace wall of a blast furnace, acquiring a plurality of stave temperatures at regular time intervals including the blast furnace shutdown period; Calculating a plurality of temperature change amounts which are the amounts of change at a predetermined time interval of the temperature at a predetermined position on the furnace wall of the blast furnace from the plurality of stave temperatures; Calculating a stave temperature fluctuation index which is the standard deviation of the plurality of temperature change amounts; Causing a computer to execute a process of determining whether or not the stave temperature fluctuation index is less than or equal to a predetermined lower limit threshold value; The initial value of the lower limit threshold value is extracted from the stave temperature fluctuation index during the blast furnace shutdown period, and the lower limit threshold value is changed when it is determined that furnace wall part inactivity has occurred. A monitoring program characterized by this.

Images