Furnace condition determination method for blast furnace, furnace condition determination device for blast furnace, and program for furnace condition determination method for blast furnace

Abstract

To determine whether a furnace condition is unstable or not.SOLUTION: In a method for determining a furnace condition of a blast furnace, a calculated tapping amount of a blast furnace is calculated in a predetermined cycle, and each time the calculated tapping amount is calculated, a coefficient of variation of the calculated tapping amount is calculated based on a plurality of calculated tapping amounts calculated in a predetermined period up to the present. When the increase in the coefficient of variation per unit time is equal to or greater than a predetermined threshold value, it is determined that the furnace condition is unstable. The threshold value may be N times (N is a positive integer) the standard deviation of the increase amount within the predetermined period, where the integer N may be 2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a furnace condition determination method, a furnace condition determination device, and a program for the furnace condition determination method for determining whether or not the furnace condition in a blast furnace is unstable. [Background technology]

[0002] In Patent Document 1, the calculated iron productivity of a blast furnace is calculated, and the amount of iron productivity adjustment action is determined based on the calculated iron productivity and the target iron productivity range. Here, the calculated iron productivity is an estimated iron productivity calculated from the material balance charged from the blast furnace top and the furnace top gas components. In addition, the amount of hot air blown from the blast tuyere or the amount of oxygen enrichment of the hot air blown from the blast tuyere is adjusted to adjust the iron productivity.

[0003] In Patent Document 2, the calculated amount of molten iron produced is calculated based on the type and weight of the raw material of the charge each time the smallest unit for management is charged into the blast furnace. When the difference between the theoretical volume value and the actual volume value of the charge in the blast furnace is negative, the calculated amount of molten iron produced is summed up to calculate the theoretical amount of iron produced, and when the difference between the theoretical volume value and the actual volume value is positive, the theoretical amount of iron produced is set to 0. The difference between the theoretical amount of iron produced and the actual amount of iron produced is then calculated as the amount of residual iron. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-048698 [Patent Document 2] JP 2002-302709 A Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the focus is on the calculated pig iron production rate in order to determine the amount of pig iron production rate adjustment action, and in Patent Document 2, the focus is on the theoretical pig iron production rate (calculated amount of molten iron produced) in order to calculate the amount of residual pig iron. On the other hand, the present inventors have found that by focusing on the calculated pig iron production rate, it is possible to determine whether the condition of a blast furnace is unstable or not, and have completed the present invention. [Means for solving the problem]

[0006] In the method for determining the furnace condition of a blast furnace according to the first invention of the present application, the calculated pig iron production rate of the blast furnace is calculated at a predetermined cycle. Then, each time the calculated pig iron production rate is calculated, a coefficient of variation of the calculated pig iron production rate is calculated based on a plurality of calculated pig iron production rates calculated within a predetermined period up to the present. When the increase in the coefficient of variation per unit time is equal to or greater than a predetermined threshold value, it is determined that the furnace condition is unstable.

[0007] The threshold value may be set to N times (N is a positive integer) the standard deviation of the increase amount within a predetermined period, where the integer N may be set to 2.

[0008] The predetermined period used for calculating the coefficient of variation may not include the blast furnace shutdown period. In addition to the blast furnace shutdown period, the predetermined period may not include at least one of the pre-blast shutdown period during which operation is performed toward the blast furnace shutdown and the post-blast shutdown period during which operation is performed to start up the blast furnace from the blast shutdown period.

[0009] The blast furnace condition determining device according to the second invention of the present application has a calculated pig iron production amount calculation unit, a variation coefficient calculation unit, and a furnace condition determining unit. The calculated pig iron production amount calculation unit calculates the calculated pig iron production amount of the blast furnace at a predetermined cycle. The variation coefficient calculation unit calculates a variation coefficient of the calculated pig iron production amount each time the calculated pig iron production amount is calculated based on a plurality of calculated pig iron production amounts calculated within a predetermined period up to the present. The furnace condition determining unit determines that the furnace condition is unstable when the increase in the variation coefficient per unit time is equal to or greater than a predetermined threshold value.

[0010] The program for the method for determining the furnace condition of a blast furnace, which is the third invention of the present application, is a program for causing a computer to execute the following steps. In a first step, the calculated iron productivity of the blast furnace is calculated at a predetermined cycle. In a second step, each time the calculated iron productivity is calculated, a coefficient of variation of the calculated iron productivity is calculated based on a plurality of calculated iron productivity calculated within a predetermined period up to the present. In a third step, when the increase in the coefficient of variation per unit time is equal to or greater than a predetermined threshold value, it is determined that the furnace condition is unstable. Effect of the Invention

[0011] According to the present invention, by comparing the increase in the coefficient of variation of the calculated pig iron production rate with a threshold value, it is possible to determine whether the furnace condition is unstable. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a block diagram showing the configuration of a reactor condition determination device. [Diagram 2] 10 is a flowchart showing a process for determining whether or not a furnace condition is unstable. [Diagram 3] FIG. 1 is a diagram showing the behavior of calculated iron production (one example). [Figure 4] FIG. 13 is a diagram showing an example of the behavior of the coefficient of variation. [Diagram 5] FIG. 13 is a diagram showing an example of the behavior of the difference in coefficient of variation. [Figure 6] FIG. 13 is a diagram showing the proportion of time during which the difference was equal to or greater than a threshold value when an operation was performed without taking the difference in the coefficient of variation into account and when an operation was performed with the difference in the coefficient of variation into account. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (furnace status judgment device) The configuration of a reactor condition determination device for determining whether the reactor condition is unstable will be described with reference to FIG.

[0014] The furnace condition determining device 1 has a processing unit 10 and a memory 20 , and the processing unit 10 has a calculated pig iron production amount calculation unit 11 , a variation coefficient calculation unit 12 , and a furnace condition determining unit 13 .

[0015] The calculated iron production amount calculation unit 11 calculates the calculated iron production amount TA based on the operating conditions of the blast furnace. cal The variation coefficient calculation unit 12 calculates the calculated pig iron production amount TA cal The furnace condition judgment unit 13 calculates an increase amount (a difference ΔCV described later) of the coefficient of variation CV per unit time based on the coefficient of variation CV calculated by the coefficient of variation calculation unit 12, and judges whether the furnace condition is unstable based on this increase amount. Detailed processing in the calculated pig iron production amount calculation unit 11, the coefficient of variation calculation unit 12, and the furnace condition judgment unit 13 will be described later.

[0016] (How to judge furnace condition) A method for determining whether the reactor condition is unstable will be described with reference to the flowchart shown in FIG.

[0017] In step S101, the calculated iron production amount calculation unit 11 calculates the calculated iron production amount TA based on the operating conditions of the blast furnace. cal Calculate the calculated iron production amount TA cal is the estimated iron production amount calculated from the material balance of the charge from the top of the blast furnace, the top gas composition, etc. cal is calculated at a predetermined period Δt1, which may be, for example, one hour.

[0018] Calculated pig iron output TA cal Although the calculation method is not particularly limited, it is necessary to standardize the calculation method when calculating the coefficient of variation CV and the difference ΔCV described later. cal Examples of a method for calculating the amount of pig iron tapped include a method for calculating the amount of pig iron tapped based on the oxygen balance and a method for calculating the amount of pig iron tapped based on the amount of pig iron charged into the furnace.

[0019] In the method of calculating the pig iron production rate based on the oxygen balance, the oxygen brought in by the ore is reduced and removed by the CO generated at the tuyere, and the pig iron production rate TA is calculated based on the gas composition at the furnace top. calOn the other hand, in the method of calculating the amount of iron produced based on the amount of ore charged into the furnace, the amount of iron produced (TA cal The weighted average of the calculated iron production amount calculated based on the oxygen balance and the calculated iron production amount calculated based on the amount of iron charged into the furnace is calculated as the iron production amount TA cal It may be adopted as.

[0020] The following is the calculated iron production amount TA based on the oxygen balance. cal The method for calculating the calculated iron production amount TA cal can be calculated based on the following formula (1).

[0021]

number

[0022]

number

[0023] In the above formula (2), O dr is the amount of directly reduced oxygen, C g is the amount of carbon consumed by the gasification reaction, and C b is the amount of carbon consumed by combustion before the tuyere, C mcis the amount of carbon consumed by the tuyere blast moisture, which is the amount of carbon used to consume the moisture in the blast supplied from the tuyere.

[0024] In the above formula (3), O ir is the amount of indirectly reduced oxygen, C g is the amount of carbon consumed by the gasification reaction, and ηCO is the utilization rate of CO gas. In the above formula (4), О hr is the amount of hydrogen-reduced oxygen, H in is the amount of hydrogen input per ton of pig iron, ηH 2 is the utilization rate of hydrogen gas. In the above formula (5), O r is the amount of reduced oxygen, O iо is the oxygen content of the ore, O m is the oxygen content of the reduced metals other than iron ore.

[0025] The calculated iron production amount TA calculated in the process of step S101 cal is stored in the memory 20 in association with the calculation time. cal Since is calculated at a predetermined cycle Δt1, the calculated iron production amount TA cal Each time it is calculated, it is stored in the memory 20.

[0026] In step S102, the variation coefficient calculation unit 12 calculates the calculated pig iron production amount TA cal Based on this, the calculated iron production amount TA cal The coefficient of variation CV is calculated based on the following formula (6). The coefficient of variation CV is stored in the memory 20 every time it is calculated.

[0027]

number

[0028] In the above formula (6), CV is the coefficient of variation, σ is the calculated iron production rate TA calculated within a predetermined period Δt2. cal Standard deviation of,TA cal_ave is the calculated amount of iron produced within a given period Δt2. calThe coefficient of variation CV is a value of 0% or more, and the closer the coefficient of variation CV is to 0%, the more stable the furnace condition is. The specified period Δt2 is the latest calculated pig iron production amount TA cal This is a past period based on the time when the calculation was performed, and can be determined appropriately.

[0029] The predetermined period Δt2 is the calculated amount of iron produced TA for which the standard deviation σ can be calculated. cal For example, the calculated iron production amount TA cal When the predetermined cycle Δt1 for calculating the amount of hot metal produced is set to 1 hour, the predetermined period Δt2 can be set to 8 to 24 hours. In this case, the latest calculated amount of hot metal produced TA cal The calculated iron production rate TA calculated between the time when the iron production rate was calculated and the time 8 to 24 hours before the calculated iron production rate TA cal Based on this, the coefficient of variation CV is calculated.

[0030] The coefficient of variation CV is calculated based on the calculated iron production amount TA cal This can be done every time the amount of variation TA is calculated, and the coefficient of variation CV can be calculated at a predetermined cycle Δt1. cal Each time the calculation is performed, the predetermined period Δt2 shifts on the time axis, and the calculated iron production amount TA cal The coefficient of variation CV is calculated based on

[0031] When calculating the coefficient of variation CV, the calculated iron production amount TA calculated within a given period Δt2 during which the blast furnace continues to operate is used. cal In other words, the calculated iron production amount TA cal In the case where the predetermined period Δt2 for calculating the coefficient of variation CV includes a period during which the blast furnace was shut down (operation was suspended) (hereinafter referred to as the “shut down period”), the coefficient of variation CV may not be calculated.

[0032] When a blast shutdown is performed, the calculated iron production amount TA is calculated for a certain period of time regardless of the operating state of the blast furnace before the shutdown (transition period from normal operation to blast shutdown) and after the shutdown (transition period from blast shutdown to normal operation). calSuch a calculated iron production amount TA cal If the coefficient of variation CV is calculated based on the behavior of the blast furnace, it may not be possible to obtain a coefficient of variation CV that reflects the operating status of the blast furnace. Therefore, the coefficient of variation TA cal It is preferable to calculate the coefficient of variation CV based on the above.

[0033] In addition, a period during which the calculation of the coefficient of variation CV is prohibited (hereinafter referred to as a "calculation prohibition period") can be determined, including not only the shutdown period but also the time period before the shutdown period begins (hereinafter referred to as a "pre-shutdown period") and the time period after the shutdown period ends (hereinafter referred to as a "post-shutdown period"). The pre-shutdown period includes operations leading up to the shutdown period, and the post-shutdown period includes operations to start up the blast furnace from the shutdown period. Therefore, the calculated iron production amount TA due to the shutdown period can be calculated during the pre-shutdown period and the post-shutdown period. cal Fluctuations in the

[0034] Since the operations leading up to the shutdown and the operations for starting up the blast furnace from the shutdown differ depending on the blast furnace, the pre-shutdown time period and the post-shutdown time period can be determined for each blast furnace. For example, the pre-shutdown time period can be 8 hours, and the post-shutdown time period can be 24 to 36 hours.

[0035] Examples of the calculation prohibition period include only the blast stop period, the combined period of the blast stop period and the time period before the blast stop period, the combined period of the blast stop period and the time period after the blast stop period, and the combined period of the blast stop period, the time period before the blast stop period, and the time period after the blast stop period. cal In other words, only if the predetermined period Δt2 does not include a calculation prohibition period, the calculated iron production amount TA calculated within the predetermined period Δt2 can be excluded from the calculation of the coefficient of variation CV. cal The coefficient of variation CV can be calculated based on the above. cal If the above-mentioned value is stored in the memory 20 together with the above-mentioned value, it can be excluded from the calculation of the coefficient of variation CV.

[0036] In step S103, the reactor condition judgment unit 13 calculates a difference ΔCV of the coefficient of variation CV based on the coefficient of variation CV calculated in the process of step S102. As described above, since the coefficient of variation CV is calculated at a predetermined period Δt1, the difference ΔCV can be set to the difference between the latest coefficient of variation CV_cur and the coefficient of variation CV_pre one period before (ΔCV=CV_cur-CV_pre).

[0037] Since the difference ΔCV is a value obtained by subtracting the coefficient of variation CV_pre from the coefficient of variation CV_cur, it can be a negative or positive value depending on the magnitude relationship between the coefficients of variation CV_cur and CV_pre. Here, when the difference ΔCV is a negative value, the coefficient of variation CV_cur is smaller than the coefficient of variation CV_pre. As described above, the closer the coefficient of variation CV is to 0%, the more stable the furnace conditions are. Therefore, when the difference ΔCV is a negative value, the furnace conditions are moving toward stability. On the other hand, when the difference ΔCV is a positive value, the furnace conditions are moving toward instability.

[0038] The difference ΔCV may be a value obtained by subtracting the coefficient of variation CV_cur from the coefficient of variation CV_pre, instead of a value obtained by subtracting the coefficient of variation CV_cur from the coefficient of variation CV_pre. In this case, when the difference ΔCV is a negative value, the reactor condition is moving toward instability, and when the difference ΔCV is a positive value, the reactor condition is moving toward stability.

[0039] In step S104, the reactor condition determination unit 13 determines whether the reactor condition is unstable based on the difference ΔCV calculated in the process of step S103. Specifically, a threshold value ΔCVth for determining whether the reactor condition is unstable is determined in advance, and it is determined whether the difference ΔCV (ΔCV=CV_cur-CV_pre) is equal to or greater than the threshold value ΔCVth. Information regarding the threshold value ΔCVth can be stored in the memory 20.

[0040] When the difference ΔCV is equal to or greater than the threshold ΔCVth, the reactor condition determining unit 13 determines in step S105 that the reactor condition is unstable. On the other hand, when the difference ΔCV is less than the threshold ΔCVth, the reactor condition determining unit 13 determines in step S106 that the reactor condition is not unstable.

[0041] For example, the threshold value ΔCVth can be determined in consideration of the standard deviation σ of the difference ΔCV within a predetermined period Δt3, and specifically, "N×σ" can be set as the threshold value ΔCVth. Here, N is a positive integer and can be determined in advance. For example, N can be set to 2. The standard deviation σ can be calculated based on a plurality of differences ΔCV calculated within a predetermined period Δt3 in which the furnace condition is stable. In this embodiment, since it is only necessary to pay attention to the increase in the coefficient of variation CV as described later, the standard deviation σ of the difference ΔCV can be calculated based only on differences ΔCV of 0% or more.

[0042] When it is determined that the furnace condition is unstable when the difference ΔCV is equal to or greater than the threshold value ΔCVth, the increase in the coefficient of variation CV can be grasped as the difference ΔCV. Therefore, the value obtained by subtracting the coefficient of variation CV_pre from the coefficient of variation CV_cur can be used as the difference ΔCV. In addition, since the coefficients of variation CV_cur and CV_pre are the coefficients of variation CV calculated before and after the predetermined period Δt1 has elapsed, the difference ΔCV indicates the increase in the coefficient of variation CV per unit time.

[0043] It is difficult to determine whether the reactor condition is unstable by only focusing on the variation of the coefficient of variation CV. In other words, since the absolute value of the coefficient of variation CV may differ depending on the calculation time of the coefficient of variation CV, it may be difficult to determine whether the reactor condition is unstable by focusing on the coefficient of variation CV itself. On the other hand, since the difference ΔCV indicates the increase in the coefficient of variation CV per unit time as described above, it becomes easier to determine whether the reactor condition is unstable by comparing the difference ΔCV with the threshold value ΔCVth.

[0044] When it is determined that the furnace condition is unstable, the furnace condition can be stabilized by taking operational actions to appropriately adjust the operational factors of the blast furnace operation. Here, the operational factors of the blast furnace operation include, for example, the blowing conditions from the tuyere, the charging conditions of the raw materials (coke and ore) from the furnace top, and the properties of the raw materials.

[0045] By outputting the judgment result that the furnace condition is unstable by voice or display, the blast furnace operator can recognize that the furnace condition is unstable and can adjust the operation factors of the blast furnace operation. Also, in a system that can automatically adjust the operation factors of the blast furnace operation, the operation factors can be automatically adjusted by setting a flag indicating that the furnace condition is unstable. This makes it possible to automate blast furnace operation according to the furnace condition.

[0046] The processes (so-called functions) described in Fig. 2 can be realized by a program. Specifically, a computer program prepared in advance to realize each function is stored in an auxiliary storage device, and a control unit such as a CPU reads the program stored in the auxiliary storage device into a main storage device, and the control unit executes the program read into the main storage device, thereby operating each function. Each function can be operated by one control device, or by multiple control devices connected to each other.

[0047] The above program can also be provided to a computer in a state in which it is recorded on a computer-readable recording medium. Examples of recording media include optical disks such as CD-ROMs, phase-change optical disks such as DVD-ROMs, magneto-optical disks such as MO (Magnet Optical) and MD (Mini Disk), magnetic disks such as floppy (registered trademark) disks and removable hard disks, and memory cards such as Compact Flash (registered trademark), Smart Media, SD memory cards, and memory sticks. In addition, hardware devices such as integrated circuits (IC chips, etc.) specially designed and configured for the purpose of the present invention are also included as recording media. EXAMPLES

[0048] Furnace volume is 5000m 3 For a blast furnace of the same class, operation was performed based on the difference ΔCV in the coefficient of variation CV. Specifically, in period A, the blast furnace was operated without considering the difference ΔCV in the coefficient of variation CV, and in period B, the blast furnace was operated with the difference ΔCV in the coefficient of variation CV in mind.

[0049] Here, each period A and B is one month, and the threshold value ΔCVth is 0.5. In addition, the predetermined cycle Δt1 is set to 1 hour, and the calculated amount of hot metal TA cal The coefficient of variation CV was calculated by setting the predetermined period Δt2 to 24 hours. As the difference ΔCV, the difference between the latest coefficient of variation CV_cur and the coefficient of variation CV_pre one cycle before (one hour before) (ΔCV=CV_cur-CV_pre) was used.

[0050] Figure 3 shows the calculated iron production rate TA cal Figure 4 shows the transition of the calculated iron production amount TA cal 3 shows an example of the change in the coefficient of variation CV calculated from the coefficient of variation CV shown in Fig. 4, and Fig. 5 shows an example of the change in the difference ΔCV calculated from the coefficient of variation CV shown in Fig. 4. A wind-off period occurs during the elapsed time shown in Fig. 3 to Fig. 5. In this example, since attention is focused on the increase in the coefficient of variation CV, Fig. 5 shows only differences ΔCV of 0% or more, and ignores differences ΔCV that indicate negative values.

[0051] Figure 6 shows the time percentage during each of periods A and B during which the difference ΔCV was equal to or greater than the threshold value ΔCVth. The time percentage here refers to the percentage of time during which the difference ΔCV was equal to or greater than the threshold value ΔCVth relative to the total time (one month) of each of periods A and B. During period A, when operation was performed without considering the difference ΔCV, relatively stable operation was possible, but the time percentage rose to nearly 2.5%. During period B, when operation was performed with the difference ΔCV considered, the time percentage was approximately 1.25%, roughly half of the time percentage during period A.

[0052] According to the results shown in Fig. 6, by performing operations taking into account the difference ΔCV, the proportion of time during which the difference ΔCV was equal to or greater than the threshold ΔCVth could be reduced, and the operation of the blast furnace could be stabilized. This clarified the significance of determining that the furnace condition is unstable when the difference ΔCV is equal to or greater than the threshold ΔCVth. [Explanation of symbols]

[0053] 1: furnace condition judgment device, 10: processing unit, 11: calculated pig iron production amount calculation unit, 12: variation coefficient calculation unit, 13: Reactor status judgment unit, 20: Memory

Claims

1. Calculate the calculated iron production rate of the blast furnace at a specified interval. Each time the calculated pig iron production rate is calculated, a coefficient of variation of the calculated pig iron production rate is calculated based on a plurality of calculated pig iron production rates calculated within a predetermined period up to the present; A method for determining a furnace condition of a blast furnace, comprising determining that the furnace condition is unstable when an increase in the coefficient of variation per unit time is equal to or greater than a predetermined threshold value.

2. The method for determining the furnace condition of a blast furnace according to claim 1, characterized in that the threshold value is N times (N is a positive integer) the standard deviation of the increase amount within a predetermined period.

3. The method for determining the furnace status of a blast furnace according to claim 2, characterized in that the integer N is 2.

4. The method for determining the furnace status of a blast furnace according to claim 1, characterized in that the predetermined period used for calculating the coefficient of variation does not include a period during which the blast furnace is shut down.

5. The method for determining the furnace status of a blast furnace as described in claim 4, characterized in that the specified period used to calculate the coefficient of variation does not include, in addition to the blast shutdown period, at least one of the pre-blast shutdown period in which operations are carried out in preparation for the blast shutdown and the post-blast shutdown period in which operations are carried out to start up the blast furnace from the blast shutdown.

6. a calculated iron production amount calculation unit that calculates a calculated iron production amount of a blast furnace at a predetermined cycle; a variation coefficient calculation unit that calculates a variation coefficient of the calculated pig iron production rate based on a plurality of calculated pig iron production rates calculated within a predetermined period up to the present, each time the calculated pig iron production rate is calculated; a reactor condition determining unit that determines that the reactor condition is unstable when an increase in the coefficient of variation per unit time is equal to or greater than a predetermined threshold value; A blast furnace condition judgment device comprising:

7. A program for causing a computer to execute the following steps: calculating a calculated iron production rate of the blast furnace at a predetermined interval; calculating a coefficient of variation of the calculated pig iron productivity based on a plurality of calculated pig iron productivity calculated within a predetermined period up to the present each time the calculated pig iron productivity is calculated; determining that the furnace condition is unstable when the increase in the coefficient of variation per unit time is equal to or greater than a predetermined threshold value; A program for a method for determining the condition of a blast furnace, comprising:

Images