JP7698200B2 - Monitoring device, monitoring method, and monitoring program - Google Patents

Description

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

One of the important objectives of blast furnace operation is to achieve tapping in accordance with the production plan. In addition to tapping in accordance with the production plan, other important issues in blast furnace operation include stabilizing the heat distribution within the blast furnace, reducing tapping costs, reducing energy consumption, stabilizing the quality of the molten iron tapped, and reducing the content of impurities such as silicon in the molten iron. In order to solve these issues, it is desirable to operate the blast furnace stably.

In order to operate a blast furnace stably, a technique is known that uses the standard deviation from the amount of change in stave temperature over a given time in a two-dimensional plane defined by the circumferential and vertical directions of the blast furnace wall to determine the stability of the blast furnace (see, for example, Patent Document 1). The technique described in Patent Document 1 determines the presence or absence of an operational abnormality in the blast furnace based on the amount of change in stave temperature over a given time interval, so that even if the temperature of the cooling water flowing through the cooling pipes of the stave cooler changes due to a change in air temperature, it is possible to accurately determine the presence or absence of an operational abnormality in the blast furnace.

JP 2020-7611 A

In the technology described in Patent Document 1, the first and second thresholds, which are the upper and lower thresholds used to determine whether or not there is an abnormality in the operation of the blast furnace, are set by an operator based on his or her own experience with reference to past blast furnace operation data. In the technology described in Patent Document 1, the first and second thresholds are set based on the operator's experience, so there is a risk that they will be set to values that are higher or lower than the appropriate values, rather than the appropriate values.

For example, when the second threshold value, which is the lower limit threshold, is set to a relatively high value, excessive reducing material may be added to the blast furnace in response to the standard deviation falling below the second threshold value, increasing the coke rate, i.e., the reducing agent rate, and causing the blast furnace operation to become unstable. Also, when the second threshold value, which is the lower limit threshold, is set to a relatively low value, there is a risk that detection of furnace wall inactivity may be delayed. If detection of the formation and growth of deposits adhering to the wall surface of the blast furnace is delayed, the deposits that have grown large may peel off from the wall surface of the blast furnace, disrupting the filling structure within the blast furnace, and causing fluctuations in the gas flow within the blast furnace. If the gas flow within the blast furnace fluctuates, this may cause the shaft pressure to fluctuate, causing the blast furnace operation to become unstable, significantly increasing the reducing agent rate, and increasing the cost of tapping iron.

The present invention aims to provide a monitoring device, a monitoring method, and a monitoring program that can suppress an increase in the reducing agent ratio.

The present invention, which solves the above problems, is summarized as follows: a monitoring device, a monitoring method, and a monitoring program.
(1) A stave temperature acquisition unit that acquires a plurality of stave temperatures for a plurality of stave coolers arranged on the wall of a blast furnace at regular time intervals, including a blast furnace rest period;
A temperature change amount calculation unit that calculates a plurality of temperature change amounts, which are change amounts of temperature at a predetermined position of the furnace wall of the blast furnace at a predetermined time interval, from a plurality of stave temperatures;
A stave temperature fluctuation index calculation unit that calculates a stave temperature fluctuation index which is the standard deviation of a plurality of temperature change amounts;
A determination unit that determines whether the stave temperature fluctuation index is equal to or lower than a predetermined lower limit threshold value,
A monitoring device characterized in that the initial value of the lower threshold value is extracted from the stave temperature fluctuation index during the wind stop period.
(2) The initial value of the lower limit threshold is a value estimated to be the maximum value of the stave temperature fluctuation index during a period when the multiple stave coolers are estimated to be not affected by the blowing of air during a period of no-air-flow. The monitoring device described in (1).
(3) The initial value of the lower threshold value is a stave temperature fluctuation index corresponding to the minimum value between a first maximum value having a maximum relative frequency of the stave temperature fluctuation index calculated during a period including the wind stop period, and a second maximum value having a relative frequency second largest after the first maximum value. This is a monitoring device described in (2).
(4) Based on the stave temperature fluctuation index, it is determined whether or not furnace wall inactivation has occurred;
When it is determined that the furnace wall portion is inactivated, a lower limit threshold value change unit changes the maximum value of the stave temperature fluctuation index in a period including at least a halt period in the furnace wall portion inactivation region to a lower limit threshold value. The monitoring device described in any one of (1) to (3).
(5) The monitoring device described in (4), wherein the lower limit threshold value change unit sets the maximum value of the stave temperature fluctuation index during a period of no-air-stop in the furnace wall inactive region as the lower limit threshold value.
(6) A plurality of stave temperatures for a plurality of stave coolers arranged on the furnace wall of a blast furnace are obtained at regular time intervals, including the blast furnace's refueling period;
Calculating a plurality of temperature change amounts, which are change amounts of temperature at a predetermined position of the blast furnace wall at a predetermined time interval, from the plurality of stave temperatures;
Calculate a stave temperature fluctuation index, which is the standard deviation of multiple temperature changes;
determining whether the stave temperature fluctuation index is equal to or less than a predetermined lower threshold;
A monitoring method characterized in that an initial value of the lower threshold value is extracted from the stave temperature fluctuation index during the non-winding period.
(7) acquiring a plurality of stave temperatures for a plurality of stave coolers arranged on the furnace wall of the blast furnace at regular time intervals, including during the blast furnace refueling period;
Calculating a plurality of temperature change amounts, which are change amounts of temperature at a predetermined position of the blast furnace wall at a predetermined time interval, from the plurality of stave temperatures;
Calculate a stave temperature fluctuation index, which is the standard deviation of multiple temperature changes;
A process is performed by a computer to determine whether or not the stave temperature fluctuation index is equal to or less than a predetermined lower threshold value;
A monitoring program characterized in that an initial value of the lower limit threshold is extracted from the stave temperature fluctuation index during the non-winding period.

The monitoring device, monitoring method, and monitoring program of the present invention can suppress an increase in the reducing agent ratio.

1 is a diagram showing a blast furnace operation system including a monitoring device according to a first embodiment. FIG. 2 is a flowchart of a monitoring process in which the monitoring device shown in FIG. 1 monitors the operation of a blast furnace while monitoring for the presence or absence of an operational abnormality. 2A is a diagram showing an example of contour lines of temperature change amount in a two-dimensional plane defined by the circumferential and height directions for a furnace wall of a blast furnace calculated by the temperature change amount calculation unit shown in FIG. 1 , and FIG. 2B is a diagram showing an example of a temperature estimation point at which a temperature change amount is estimated by the temperature change amount calculation unit shown in FIG. 1 . 3 is a flowchart of an initial value determination process in which the monitoring device shown in FIG. 1 determines an initial value of a lower limit threshold value used in the process of S106 shown in FIG. 2; 1A is a diagram showing a first example of an initial value extraction period, FIG. 1B is a diagram showing a second example of an initial value extraction period, and FIG. 1C is a diagram showing a third example of an initial value extraction period. FIG. 11 is a diagram for explaining the process of determining an initial value of the lower limit threshold shown in S106. 3 is a flowchart of a lower limit threshold changing process in which the monitoring device shown in FIG. 1 changes a lower limit threshold used in the process of S106 shown in FIG. 2; FIG. 11 is a diagram for explaining the processing of S307. FIG. 1 is a diagram showing a ratio of a charging amount of a reducing material in the technology described in Patent Document 1 to a charging amount of a reducing material in the technology according to the present invention.

The monitoring device, monitoring method, and monitoring program will be described below with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments.

(Overview of monitoring device according to embodiment)
The monitoring device of the embodiment uses a value determined from the standard deviation during the blast furnace's blast shutdown period as the lower threshold value for determining whether or not there is an operational abnormality in the blast furnace, thereby making it possible to set the lower threshold value at a more appropriate value than if the lower threshold value were set based on the operator's experience.

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

The blast furnace operation system 100 has a monitoring device 1 and multiple stave temperature sensors 101 that detect the stave temperatures of multiple stave coolers arranged throughout the furnace wall of the blast furnace 110. The multiple 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 per stave cooler, or multiple stave temperature sensors 101 may be arranged per stave cooler.

The monitoring device 1 according to the embodiment has a communication unit 11, a memory unit 12, an input unit 13, an output unit 14, and a processing unit 20. The communication unit 11, the memory 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 threshold value used when determining whether or not there is an operational abnormality in a blast furnace, and determines whether or not the calculated stave temperature fluctuation index is equal to or lower than the lower threshold value.

The communication unit 11 has a wired communication interface circuit such as Ethernet (registered trademark). The communication unit 11 communicates with multiple stave temperature sensors 101 and a higher-level control device (not shown) via the LAN 102.

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

The storage unit 12 also stores various data used in the monitoring process. Furthermore, the storage unit 12 may temporarily store temporary data related to a specific process.

The input unit 13 may be any device capable of inputting data, such as a touch panel or a keyboard. An operator (not shown) can use the input unit 13 to input letters, numbers, symbols, etc. When operated by the operator, the input unit 13 generates a signal corresponding to the operation. The generated signal is then supplied to the processing unit 20 as an instruction from the operator.

The output unit 14 may be any device capable of displaying video, images, etc., such as a liquid crystal display or an organic EL (Electro-Luminescence) display. The output unit 14 displays video corresponding to video data supplied from the processing unit 20, images corresponding to image data, etc. The output unit 14 may also be an output device that prints video, images, text, etc. on a display medium such as paper.

The processing unit 20 has one or more processors and their peripheral circuits. The processing unit 20 centrally 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 memory unit 12. The processing unit 20 can also execute multiple programs (application programs, etc.) in parallel.

The processing unit 20 has a stave temperature acquisition unit 21, a temperature change amount calculation unit 22, a stave 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 threshold change unit 27. Each of these units is a functional module realized by a program executed by a processor provided in the processing unit 20. Alternatively, each of these units may be implemented in the monitoring device 1 as firmware.

(Monitoring process by monitoring device according to embodiment)
2 is a flowchart of a monitoring process in which the monitoring device 1 operates the blast furnace 110 while monitoring whether or not there is an operational abnormality in the blast furnace 110. The monitoring process shown in FIG. 2 is executed mainly by the processing unit 20 in cooperation with each element of the monitoring device 1 based on a program stored in advance in the storage unit 12.

First, the stave temperature acquisition unit 21 acquires multiple stave temperatures from the stave temperature sensor 101 via the LAN 102 for multiple stave coolers arranged on the furnace wall of the blast furnace 110 (S101). There may be stave coolers with multiple stave temperature sensors 101 arranged therein and stave coolers without stave temperature sensors 101 arranged therein. The stave coolers and the stave temperature sensors 101, and the stave coolers and the stave temperatures do not necessarily correspond one-to-one to each other. However, when one stave temperature sensor is arranged for one stave cooler and one stave temperature is acquired, the multiple stave temperatures can be associated with the identification number of the corresponding stave cooler and stored in the memory unit 12. The stave temperature acquisition unit 21 associates each of the acquired multiple stave temperatures with the arrangement position of the stave temperature sensor 101 or the identification number of the corresponding stave cooler and stores them in the memory unit 12. The stave temperature acquisition unit 21 acquires the stave temperature at regular time intervals, and the time intervals may be, for example, 1 second, 1 minute, or 5 minutes.

Next, the temperature change amount calculation unit 22 calculates a plurality of temperature change amounts indicating the change amount at a predetermined time interval for each of the plurality of stave temperatures acquired in the processing of S101 (S102). First, for each of the plurality of stave temperatures acquired in the processing 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 processing before the predetermined time interval and the stave temperature acquired in the current monitoring processing. The temperature change amount calculation unit 22 associates each of the calculated temperature change amounts with the arrangement position of the stave temperature sensor 101 or the identification number of the corresponding stave cooler and stores it in the memory unit 12. Note that the predetermined time interval can be constant and may or may not be the same as the time interval at which the stave temperature is acquired, and may be, for example, 1 minute or 5 minutes. In addition, when calculating the amount of temperature change, a weighting coefficient that takes into account the influence of the stave temperature can be set arbitrarily, for example, as disclosed in JP 2002-317217 A, and can be set using, for example, a forgetting coefficient that defines the strength of forgetting.

Next, the temperature change amount calculation unit 22 calculates isolines of the temperature change amount in a two-dimensional plane defined by the circumferential and height directions for the furnace wall of the blast furnace 110. The temperature change amount calculation unit 22 calculates isolines of the temperature change amount in the two-dimensional plane from the stave temperature change amount calculated in the processing of S201 and the arrangement positions of the stave temperature sensors 101 corresponding to each of the calculated stave temperature change amounts. The temperature change amount calculation unit 22 can calculate the isolines by an isoline search method described in, for example, JP 2002-194405 A and JP 2002-317217 A.

Figure 3(a) is a diagram showing an example of contour lines of temperature change in a two-dimensional plane defined by the circumferential and height directions for the furnace wall of the blast furnace 110 calculated by the temperature change calculation unit 22. In Figure 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.

Then, the temperature change amount calculation unit 22 estimates the temperature change amount at a plurality of temperature estimation points arranged in a grid pattern in a two-dimensional plane defined by the circumferential and height directions of the furnace wall of the blast furnace 110. The temperature change amount is the amount of change in temperature over a predetermined period of time, such as five 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 isoline 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.

Figure 3(b) is a diagram showing an example of a temperature estimation point at which a temperature change is estimated by the temperature change calculation unit 22. In Figure 3(b), 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. In Figure 3(b), the temperature estimation points are indicated by white circles located at the intersections of dashed lines extending in the circumferential and height directions of the blast furnace. In Figure 3(b), the temperature estimation points are arranged in a 12 x 7 grid pattern.

Next, the stave temperature fluctuation index calculation unit 23 calculates a stave temperature fluctuation index, which is the standard deviation of the multiple 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 memory unit 12. The stave temperature fluctuation index calculation unit 23 may store the calculated stave temperature fluctuation index in the memory unit 12 each time it calculates a stave temperature fluctuation index. In addition, the stave temperature fluctuation index calculation unit 23 may store the average value of the stave temperature fluctuation index calculated over a certain period of time in the memory unit 12. For example, the stave temperature fluctuation index calculation unit 23 may store the average value of the stave temperature fluctuation index calculated every 5 minutes over a period of 60 minutes as the stave temperature fluctuation index in the memory unit 12.

Next, the operation abnormality determination unit 24 determines whether the stave temperature fluctuation index stored in the memory unit 12 is equal to or less than the lower threshold value (S104). The lower threshold value is determined and changed by executing the initial value determination process and the lower threshold value change process described with reference to Figures 4 to 6, and is stored in the memory unit 12. When the operation abnormality determination unit 24 determines that the stave temperature fluctuation index stored in the memory unit 12 is equal to or less than the lower threshold value (S104-YES), it stores an operation abnormality flag indicating that the lower furnace portion has become inactive in the memory unit 12 (S105).

Then, the alarm signal output unit 25 determines whether or not an operation abnormality flag is stored in the memory unit 12 (S106). If the alarm signal output unit 25 determines that a second operation abnormality flag is stored in the memory unit 12 (S106-YES), it outputs an alarm signal indicating that the thickness of the deposits on the furnace wall of the blast furnace 110 has increased (S107).

(Initial Value Determination Process by Monitoring Device According to the Embodiment)
Fig. 4 is a flowchart of an initial value determination process in which the monitoring device 1 determines an initial value of the lower limit threshold used in the process of S106 shown in Fig. 2. The initial value determination process shown in Fig. 4 is executed mainly by the processing unit 20 in cooperation with each element of the monitoring device 1, based on a program previously stored in the storage unit 12. The processes of S201 to S203 are similar to the processes of S101 to S103, and therefore detailed description thereof will be omitted here.

Following the process of S203, the initial value determination unit 26 determines whether or not an initial value determination instruction indicating that an initial value of the lower limit threshold value is to be determined has been input (S204). The initial value determination unit 26 determines whether or not 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 the initial value determination unit 26 determines that an initial value determination instruction has been input (S204-YES). By repeating the processes of S201 to S204, the stave temperature fluctuation index is repeatedly calculated, and the calculated stave temperature fluctuation index is stored in the memory unit 12.

When the initial value determination unit 26 determines that an initial value determination command has been input (S204-YES), it acquires the stave temperature fluctuation index calculated during the initial value extraction period that includes at least one blast stop period during which the blast furnace 110 is blast stopped (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 blast furnace 110 blast stop period is the period from when blasting from the tuyere is stopped to when blasting from the tuyere is started.

Next, the initial value determination unit 26 determines the initial value of the lower threshold value used when determining whether or not there is an operational abnormality in 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 the initial value of the lower threshold value to be the estimated maximum value of the stave temperature fluctuation index during the period during which it is estimated that the multiple stave coolers are not affected by the blowing of air during the blowing stop period. The period estimated to be not affected by the blowing of air is, for example, a period during which the fluctuation index is 0.0005 or less.

Figure 5(a) is a diagram showing a first example of an initial value extraction period, Figure 5(b) is a diagram showing a second example of an initial value extraction period, and Figure 5(c) is a diagram showing a third example of an initial value extraction period. In Figures 5(a) to 5(c), the horizontal axis indicates time, and the vertical axis indicates the stave temperature fluctuation index. Also, in Figures 5(a) to 5(c), the bidirectional arrow A indicates a period of no airflow, and the bidirectional arrow B indicates a period during which multiple stave coolers are estimated to be unaffected by airflow.

In the first example shown in FIG. 5(a), the off-air period is 21 hours from 3:00 to 24:00, and the period during which the multiple stave coolers are estimated to be unaffected by the airflow is 20 hours from 4:00 to 24:00. In the first example, the multiple stave coolers are not affected by the airflow from a relatively early time, about 2 hours after the start of the off-air period. The maximum value of the stave temperature fluctuation index during the period during which the multiple stave coolers are estimated to be unaffected by the airflow is about 0.0005.

In the second example shown in FIG. 5(b), the off-air period is 21 hours from 3:00 to 24:00, and the period during which the multiple stave coolers are estimated to be unaffected by the airflow is 15 hours from 9:00 to 24:00. In the second example, the multiple stave coolers are no longer affected by the airflow from a relatively late time, about 9 hours after the start of the off-air period. The maximum value of the stave temperature fluctuation index during the period during which the multiple stave coolers are estimated to be unaffected by the airflow is about 0.0004.

In the third example shown in FIG. 5(c), the off-air period is 27 hours from 6:00 to 9:00 the following day, and the period during which the multiple stave coolers are estimated to be unaffected by the airflow is 24 hours from 9:00 to 9:00 the following day. In the third example, the multiple stave coolers are no longer affected by the airflow from a relatively early time, about 3 hours after the start of the off-air period. The maximum value of the stave temperature fluctuation index during the period during which the multiple stave coolers are estimated to be unaffected by the airflow is about 0.0003.

The length of time from the start of the rest period until the multiple stave coolers are no longer affected by the blast air varies depending on the furnace conditions of the blast furnace 110, the position of the stave coolers, etc., so it is not easy to estimate the period during which the multiple stave coolers are not affected by the blast air. Below, we will explain how the initial value determination unit 26 estimates the maximum value of the stave temperature fluctuation index during the period during which the multiple stave coolers are estimated to be no longer affected by the blast air.

The initial value determination unit 26 extracts a stave temperature fluctuation index corresponding to the minimum value between a first maximum value, which is the maximum relative frequency of the calculated stave temperature fluctuation index, and a second maximum value, which is the second largest 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 a period when the multiple stave coolers are not affected by the air blowing, and determines it as the initial value of the lower threshold value.

Figure 6 is a diagram for explaining the process of determining the initial value of the lower threshold shown in S206. In Figure 6, the horizontal axis shows the stave temperature fluctuation index in logarithmic display, and the vertical axis shows the relative frequency normalized for the number of stave temperature fluctuation indices calculated from the stave temperatures detected during the initial value extraction period.

First, the initial value determination unit 26 extracts the stave temperature fluctuation index corresponding to the first maximum value, which is the maximum relative frequency of the stave temperature fluctuation index. In the example shown in FIG. 4, "0.0002" is extracted, which corresponds to the relative frequency of "1.0" indicated by the arrow C in FIG. 6, and the extracted stave temperature fluctuation index is stored in the memory unit 12 as the stave temperature fluctuation index corresponding to the first maximum value.

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

Then, the initial value determination unit 26 determines 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 threshold value. The initial value determination unit 26 extracts the stave temperature fluctuation index "0.0035" with the smallest relative frequency between the stave temperature fluctuation index "0.0002" corresponding to the first maximum value and the stave temperature fluctuation index "0.001" corresponding to the second maximum value. The initial value determination unit 26 stores the extracted stave temperature fluctuation index "0.0035" with the smallest relative frequency in the memory unit 12 as the initial value of the lower threshold value.

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, which has the highest relative frequency, and the second maximum value, which has the second largest relative frequency after the first maximum value, as the initial value of the lower threshold value. One of the first maximum value and the second maximum value is the stave temperature fluctuation index in the no-air-stop period, and the other of the first maximum value and the second maximum value is the stave temperature fluctuation index in the no-air-stop period. When transitioning to the no-air-stop period, the stave temperature fluctuation index drops sharply, so that the relative frequency of the stave temperature fluctuation index during the transition to the no-air-stop period is smaller than the relative frequency of the stave temperature fluctuation index before and after transition to the no-air-stop period. When transitioning to the no-air-stop period, the flow of gas around the stave cooler suddenly stagnates, and the temperature change amount of the cooling water flowing through the stave cooler becomes smaller, so that the stave temperature fluctuation index drops sharply when transitioning to the no-air-stop 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 threshold, the stave temperature fluctuation index close to the maximum value of the stave temperature fluctuation index during the period not affected by the air blowing can be determined as the initial value of the lower threshold.

(Lower Threshold Change Process by Monitoring Device According to the Embodiment)
Fig. 7 is a flowchart of a lower threshold value changing process in which the monitoring device 1 changes the lower threshold value used in the process of S106 shown in Fig. 2. The lower threshold value changing process shown in Fig. 7 is executed mainly by the processing unit 20 in cooperation with each element of the monitoring device 1, based on a program previously stored in the storage unit 12.

The monitoring device 1 changes the lower threshold value based on the correlation between the stave temperature fluctuation index and furnace wall inactivation. Furnace wall inactivation is a state in which gas does not come into contact with the stave cooler arranged near the furnace wall of the blast furnace 110. Causes of furnace wall inactivation include the phenomenon in which powdered raw materials get between the stave cooler and the charge located in front of it, or the phenomenon in which raw materials that have softened and then resolidified adhere to the front of the stave cooler. In addition, a combination of phenomena that cause furnace wall inactivation can occur, causing strong adhesion to form on the front of the stave cooler, resulting in furnace wall inactivation.

When furnace wall inactivation occurs, the stave temperature drops and the heat load drops. The heat load is the amount of heat removed by the cooling water flowing through the cooling piping of the stave cooler, and is calculated from the temperature rise of the cooling water flowing through the cooling piping of the stave cooler. As furnace wall inactivation occurs and the stave temperature drops, the amount of stave temperature change drops and the stave temperature fluctuation index drops. By accurately detecting the drop in the stave temperature fluctuation index, the occurrence of furnace wall inactivation can be accurately detected.

The processes of S301 to S303 are similar to those of S101 to S103, and therefore detailed description thereof will be omitted here. Following the process of S303, the lower threshold change unit 27 determines whether or not a lower threshold change instruction indicating that the lower threshold is to be changed has been input (S304). The lower threshold change unit 27 determines whether or not a lower threshold change instruction has been input by the operator via the input unit 13. The processes of S301 to S304 are repeated until the lower threshold change unit 27 determines that a lower 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 memory unit 12.

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 deactivation determination period that includes at least one blast stop 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 deactivation determination period in response to the furnace wall deactivation determination period being input by the operator via the input unit 13.

Next, the lower limit threshold change unit 27 determines whether or not furnace wall deactivation has occurred based on the stave temperature fluctuation index obtained in the processing of S305 (S306).

The lower threshold value change unit 27 compares the stave temperature fluctuation index during the blasting rest period with the stave temperature fluctuation index outside the blasting rest period to determine whether or not furnace wall inactivation has occurred. For example, the lower threshold value change unit 27 determines that furnace wall inactivation has occurred when, in any region of the blast furnace 110, the order of the maximum value of the stave temperature fluctuation index outside the blasting rest period is the same as the order of the maximum value of the stave temperature fluctuation index during the blasting rest period. The lower threshold value change unit 27 may also determine that furnace wall inactivation has occurred based on information input via the input unit 13 by an operator who has confirmed that furnace wall inactivation has occurred.

When the lower threshold change unit 27 determines that furnace wall deactivation has not occurred (S306-NO), the lower threshold change process ends.

When the lower threshold change unit 27 determines that furnace wall inactivation has occurred (S306-YES), it extracts the maximum value of the stave temperature fluctuation index during the maximum value extraction period that includes at least the wind stop period in the furnace wall inactive region where the furnace wall inactivation has occurred (S307).

Figure 8 is a diagram for explaining the processing of S307. In Figure 8, the horizontal axis indicates time, and the vertical axis indicates the stave temperature fluctuation index. Also, in Figure 8, the bidirectional arrow A indicates the wind-off period, and the bidirectional arrow E indicates the maximum value extraction period.

In the example shown in FIG. 8, the wind-off period is 27 hours from 6:00 to 9:00 the following day, and the maximum value extraction period is 51 hours from 18:00 the previous day to 21:00 the following day. In the example shown in FIG. 8, the maximum value extraction period is the wind-off period, as well as 12 hours before the start of the wind-off period and 12 hours after the end of the wind-off period. In this embodiment, it is sufficient to include at least the wind-off period, and it may also include a period that is not a wind-off period (for example, 12 hours before the start of the wind-off period and 12 hours after the end of the wind-off period). In addition, the period that is not a wind-off period is set to 12 hours before the start of the wind-off period and 12 hours after the end of the wind-off period, but is not limited to 12 hours and may be set as appropriate.

Next, the lower threshold change unit 27 changes the lower threshold stored in the memory unit 12 so that the maximum value of the stave temperature fluctuation index extracted in the process of S307 becomes the lower threshold (S308), and the lower threshold change process ends.

(Functions and Effects of the Monitoring Device According to the Embodiment)
The monitoring device 1 determines the initial value of the lower limit threshold from the stave temperature fluctuation index during the blast furnace 110's blast stop period, and can detect the inactivation of the lower furnace part at an early stage by the appropriate lower limit threshold, and can determine the presence or absence of an operation abnormality in the blast furnace 110. If the inactivation of the lower furnace part cannot be detected at an early stage, 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 reducing agent ratio increases significantly, and the tapping cost increases. In contrast, the blast furnace operation device 1 can detect the inactivation of the furnace wall part at an early stage, so that the fluctuation of the gas flow in the blast furnace 101 is suppressed, and the fluctuation of the shaft pressure is suppressed. This stabilizes the operation of the blast furnace. Therefore, in the monitoring device 1, there is no need to increase the amount of coke used, and the increase in the reducing agent ratio and the tapping cost are suppressed.

During the time when the blast furnace 110 is shut down, gas from the blowing is not blown into the blast furnace 110, so the temperature inside the blast furnace 110 basically does not change, the amount of change in the stave temperature is small, and the stave temperature fluctuation index approaches zero. During the time when the blast furnace 110 is shut down, the stave temperature fluctuation index fluctuates slightly not due to temperature changes inside the blast furnace 110, but due to the effects of temperature changes in the cooling water flowing through the cooling pipes of the stave cooler and slight movement of the charges charged into the blast furnace 110. The monitoring device 1 can determine an appropriate lower threshold value by determining an initial value of the lower threshold value from the stave temperature fluctuation index during the shut down period of the blast furnace 110.

More specifically, during the air suspension period, the monitoring device 1 uses the estimated maximum value of the stave temperature fluctuation index during the period when the multiple stave coolers of the blast furnace 110 are estimated to be not affected by the air blown from the tuyere as the initial value of the lower threshold. By using the maximum value of the stave temperature fluctuation index during the period when the multiple stave coolers are estimated to be not affected by the air blown from the tuyere as the initial value of the lower threshold, the maximum value during the period when the coolers are not affected by the air blow can be set as the initial value of the lower threshold.

In addition, the monitoring device 1 can change the maximum value of the stave temperature fluctuation index during the period including the wind stop period in the furnace wall inactivation area to the lower threshold value, thereby allowing the stave temperature fluctuation index corresponding to the actual measurement value at which the furnace wall inactivation occurs to be used as the lower threshold value.

By setting the maximum value of the period not affected by the air blowing as the initial value of the lower threshold, the monitoring device 1 can achieve stable operation while pursuing stricter operating conditions, such as reducing the reducing agent ratio.

Figure 9 shows the ratio of the amount of reducing material charged in the technology described in Patent Document 1 to the amount of reducing material charged in the technology according to the present invention.

The technology according to the present invention can reduce the amount of reducing material charged into the blast furnace 110 by about 5% compared to the amount of reducing material charged into the blast furnace 110 in the technology described in Patent Document 1.

Reference Signs List 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 (7)

A stave temperature acquisition unit that acquires a plurality of stave temperatures for a plurality of stave coolers arranged on the furnace wall of the blast furnace at regular time intervals, including the blast furnace rest period;
A temperature change amount calculation unit that calculates a plurality of temperature change amounts, which are change amounts of temperature at a predetermined position of 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 the stave temperature fluctuation index is equal to or lower than a predetermined lower limit threshold value,
The initial value of the lower limit threshold is extracted from the stave temperature fluctuation index during the halt period , and the lower limit threshold is changed when it is determined that furnace wall inactivation has occurred. A monitoring device. The monitoring device according to claim 1, wherein the initial value of the lower limit threshold is a value estimated to be the maximum value of the stave temperature fluctuation index during the period during which the plurality of stave coolers are estimated to be unaffected by the blowing of air during the wind-off period. The monitoring device according to claim 2, wherein the initial value of the lower limit threshold 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 wind stop period is the maximum, and a second maximum value at which the relative frequency is the second largest after the first maximum value. Based on the stave temperature fluctuation index, it is determined whether or not furnace wall inactivation has occurred,
When it is determined that the furnace wall portion is inactivated, a lower limit threshold value change unit changes the maximum value of the stave temperature fluctuation index in a period including at least the wind stop period in the furnace wall portion inactivation region to the lower limit threshold value. The monitoring device according to any one of claims 1 to 3, further comprising: a lower limit threshold value change unit. The monitoring device according to claim 4, wherein the lower threshold value change unit sets the maximum value of the stave temperature fluctuation index during the wind-stop period in the furnace wall inactive region as the lower threshold value. A plurality of stave temperatures for a plurality of stave coolers arranged on the furnace wall of a blast furnace are obtained at regular time intervals, including a blast stop period of the blast furnace;
From the plurality of stave temperatures, a plurality of temperature change amounts, which are change amounts of temperature at a predetermined position of the furnace wall of the blast furnace at a predetermined time interval, are calculated;
Calculate a stave temperature fluctuation index, which is the standard deviation of the plurality of temperature changes;
Determining whether the stave temperature fluctuation index is equal to or less than a predetermined lower threshold value;
The initial value of the lower limit threshold is extracted from the stave temperature fluctuation index during the halt period , and the lower limit threshold is changed when it is determined that furnace wall inactivation has occurred. A monitoring method. A plurality of stave temperatures for a plurality of stave coolers arranged on the furnace wall of a blast furnace are obtained at regular time intervals, including a blast stop period of the blast furnace;
From the plurality of stave temperatures, a plurality of temperature change amounts, which are change amounts of temperature at a predetermined position of the furnace wall of the blast furnace at a predetermined time interval, are calculated;
Calculate a stave temperature fluctuation index, which is the standard deviation of the plurality of temperature changes;
A process is performed on a computer to determine whether the stave temperature fluctuation index is equal to or lower than a predetermined lower threshold value;
The initial value of the lower limit threshold is extracted from the stave temperature fluctuation index during the halt period , and the lower limit threshold is changed when it is determined that furnace wall inactivation has occurred. A monitoring program.

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