Blast furnace operation method, blast furnace operation control device, and blast furnace operation control program

Abstract

To suppress a decrease in production efficiency of a blast furnace by improving estimation accuracy of an amount of fine powder in the blast furnace.SOLUTION: A blast furnace operation method includes: measuring a fine powder concentration in exhaust gas G2 discharged from a furnace top of the blast furnace 10; and changing an operating condition of the blast furnace 10 when the measured fine powder concentration is equal to or greater than a threshold value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a blast furnace operation method, a blast furnace operation control device, and a blast furnace operation control program.

Background Art

[0002] There is a method of continuously measuring the dust concentration in the gas discharged from the top of a blast furnace and detecting the peeling of deposits adhering to the furnace wall based on the measured dust concentration (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a blast furnace, when the amount of powder such as blast furnace raw materials increases, for example, the air permeability in the blast furnace deteriorates, and the production efficiency of the blast furnace may decrease.

[0005] As a countermeasure, for example, it is conceivable to measure the powder ratio of the blast furnace raw materials charged into the blast furnace from the top and estimate the amount of powder in the blast furnace based on the measured powder ratio of the blast furnace raw materials. Then, based on the estimated amount of powder in the blast furnace, the operating conditions of the blast furnace are changed so that the production efficiency of the blast furnace does not decrease.

[0006] However, the powder in the blast furnace is not limited to only the powder charged together with the blast furnace raw materials from the top. Examples of the powder in the blast furnace include powder generated by the impact when charging blast furnace raw materials into the blast furnace from the top, and powder generated during the reduction process of the blast furnace raw materials.

[0007] Therefore, as described above, it is difficult to accurately estimate the amount of powder in the blast furnace only by measuring the powder ratio of the blast furnace raw materials charged into the blast furnace from the top of the furnace, and there is a possibility that the production efficiency of the blast furnace may decrease.

[0008] In view of the above facts, an object of the present invention is to suppress a decrease in the production efficiency of a blast furnace by improving the estimation accuracy of the amount of powder in the blast furnace.

Means for Solving the Problems

[0009] The blast furnace operation method according to the first aspect measures the powder concentration of the exhaust gas discharged from the top of the blast furnace, and changes the operation conditions of the blast furnace when the measured powder concentration is equal to or higher than a threshold value.

[0010] According to the above aspect, the powder concentration of the exhaust gas discharged from the top of the blast furnace is measured, and when the measured powder concentration of the exhaust gas is equal to or higher than a threshold value, the operation conditions of the blast furnace are changed.

[0011] Here, when the amount of powder in the blast furnace increases, the powder concentration of the exhaust gas discharged from the top of the blast furnace also increases. On the other hand, when the amount of powder in the blast furnace decreases, the powder concentration of the exhaust gas discharged from the top of the blast furnace also decreases.

[0012] Therefore, in this aspect, as described above, the powder concentration of the exhaust gas discharged from the top of the blast furnace is measured. Thereby, the estimation accuracy of the amount of powder in the blast furnace is improved. And when the measured powder concentration of the exhaust gas is equal to or higher than a threshold value, by changing the operation conditions of the blast furnace, a decrease in the production efficiency of the blast furnace can be suppressed.

[0013] The blast furnace operation method according to the second aspect changes the amount of change in the operation conditions based on the difference between the measured powder concentration and the threshold value in the blast furnace operation method according to the first aspect.

[0014] According to the above aspect, by changing the amount of change in the operation conditions based on the difference between the measured powder concentration of the exhaust gas and the threshold value, a decrease in the production efficiency of the blast furnace can be efficiently suppressed.

[0015] In the blast furnace operation method according to the third aspect, in the blast furnace operation method according to the first aspect or the second aspect, after the change of the operation conditions, the powder concentration of the exhaust gas discharged from the furnace top is measured as the post-change powder concentration, and when the measured post-change powder concentration is equal to or higher than the threshold value, the operation conditions are further changed.

[0016] According to the above aspect, after the change of the operation conditions, the powder concentration of the exhaust gas discharged from the furnace top is measured as the post-change powder concentration. Then, when the measured post-change powder concentration is equal to or higher than the threshold value, the operation conditions are further changed. Thereby, a decrease in the production efficiency of the blast furnace can be efficiently suppressed.

[0017] In the blast furnace operation method according to the fourth aspect, in the blast furnace operation method according to any one of the first aspect to the third aspect, the operation conditions include at least one of the flow rate of the in-furnace gas rising in the blast furnace, the heat flow ratio in the blast furnace, and the powder ratio of the blast furnace raw materials charged into the blast furnace.

[0018] According to the above aspect, the operation conditions include at least one of the flow rate of the in-furnace gas rising in the blast furnace, the heat flow ratio in the blast furnace, and the powder ratio of the blast furnace raw materials charged into the blast furnace.

[0019] Here, the powder concentration of the exhaust gas discharged from the furnace top of the blast furnace is measured, and when the measured powder concentration of the exhaust gas is equal to or higher than the threshold value, for example, the flow rate of the in-furnace gas rising in the blast furnace is increased. Thereby, the powder of the blast furnace raw materials charged from the furnace top into the blast furnace can be discharged from the furnace top to the outside of the blast furnace. Therefore, the deterioration of the air permeability in the blast furnace due to the increase in the powder amount in the blast furnace is suppressed.

[0020] Also, when the measured powder concentration of the exhaust gas is equal to or higher than the threshold value, for example, the heat flow ratio is decreased. Thereby, the temperature drop in the blast furnace due to the increase in the powder amount in the blast furnace can be suppressed. As a result, the reduction delay of the blast furnace raw materials in the blast furnace is suppressed.

[0021] Also, when the measured powder concentration of the exhaust gas is equal to or higher than the threshold value, for example, the blast furnace raw materials charged into the blast furnace are changed to blast furnace raw materials with a lower powder ratio. Thereby, the amount of powder charged into the blast furnace from the furnace top together with the blast furnace raw materials can be reduced. Therefore, the deterioration of the air permeability in the blast furnace due to the increase in the amount of powder in the blast furnace is suppressed.

[0022] As described above, in this aspect, when the measured powder concentration of the exhaust gas is equal to or higher than the threshold value, at least one of the flow rate of the in-furnace gas rising in the blast furnace, the heat flow ratio in the blast furnace, and the powder ratio of the blast furnace raw materials charged into the blast furnace is adjusted, whereby a decrease in the production efficiency of the blast furnace can be suppressed.

[0023] The blast furnace operation control device according to the fifth aspect includes a control unit that measures the powder concentration of the exhaust gas discharged from the furnace top of the blast furnace and executes a process of changing the operation conditions of the blast furnace when the measured powder concentration is equal to or higher than the threshold value.

[0024] The blast furnace operation control program according to the sixth aspect causes a computer to execute a process of measuring the powder concentration of the exhaust gas discharged from the furnace top of the blast furnace and changing the operation conditions of the blast furnace when the measured powder concentration is equal to or higher than the threshold value.

Advantages of the Invention

[0025] As described above, according to the present invention, by improving the estimation accuracy of the amount of powder in the blast furnace, a decrease in the production efficiency of the blast furnace can be suppressed.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0027] Hereinafter, an embodiment will be described with reference to the drawings.

[0028] (Blast furnace) In FIG. 1, a blast furnace 10 to which the blast furnace operation method according to this embodiment is applied is shown. A raw material charging device 20 is provided at the top of the blast furnace 10. Iron ore and coke as blast furnace raw materials are conveyed to the raw material charging device 20 by a conveying device 22. This raw material charging device 20 charges iron ore and coke as blast furnace raw materials into the blast furnace 10. As a result, a coke layer and an iron ore layer are alternately deposited in layers in the blast furnace 10.

[0029] In the blast furnace 10, hot air, auxiliary fuel, etc. are blown in from tuyeres 12 provided at the lower part of the blast furnace 10. As a result, the auxiliary fuel and coke burn, generating in-furnace gas (reducing gas) G1 that rises in the blast furnace 10. The iron ore in the iron ore layer deposited in the blast furnace 10 is heated and reduced by this in-furnace gas G1 while descending. Then, the molten iron ore while descending is discharged as pig iron from a tapping hole (not shown) provided on the side wall at the furnace bottom.

[0030] The in-furnace gas G1 that has risen in the blast furnace 10 is discharged as exhaust gas G2 to a dust catcher 26 through an exhaust duct 24. The dust catcher 26 recovers the powder (dust) in the exhaust gas G2 discharged from the blast furnace 10. A powder concentration measuring device 30 for measuring the concentration of the powder (dust) contained in the exhaust gas G2 is provided in this dust catcher 26.

[0031] (Powder Concentration Measuring Device) The powder concentration measuring device 30 is, for example, a dust meter (dust concentration automatic measuring instrument) using a light scattering method, a light transmission method, or a triboelectric detection method. The powder concentration measuring device 30 measures, for example, the powder concentration of the exhaust gas G2 periodically or continuously, and outputs the measured powder concentration to a blast furnace operation control device 40 described later.

[0032] Note that the powder in the exhaust gas G2 is, as an example, blast furnace raw material with a diameter (particle size) of 5 mm or less, but the reference diameter of the powder is not limited to 5 mm or less and can be changed as appropriate.

[0033] (Damper) A top pressure power generation device (not shown) is connected to the dust catcher 26 through an exhaust duct 32. A damper 34 for controlling the effective cross-sectional area of the exhaust duct 32 and adjusting the discharge amount of the exhaust gas G2 discharged to the top pressure power generation device is provided in this exhaust duct 32. By controlling the effective cross-sectional area of the exhaust duct 32 with this damper 34, the flow rate of the in-furnace gas G1 is adjusted.

[0034] (Outline of Blast Furnace Operation Control Device) The blast furnace operation control device 40 (see FIG. 3) controls the overall operation of the blast furnace 10. Further, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, the blast furnace operation control device 40 changes the operation conditions of the blast furnace 10.

[0035] (Hardware Configuration of Blast Furnace Operation Control Device) Next, the hardware configuration of the blast furnace operation control device 40 will be described.

[0036] The blast furnace operation control device 40 is realized by, for example, a computer 70 shown in FIG. 2. The computer 70 includes a CPU (Central Processing Unit) 72, a memory 74 as a temporary storage area, and a non-volatile storage unit 76. Further, the computer 70 includes an input / output device 78. These CPU 72, memory 74, storage unit 76, and input / output device 78 are connected to each other via a bus 79. Note that the CPU 72 is an example of a control unit and a processor.

[0037] The storage unit 76 is realized by, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), a flash memory, or the like. In the storage unit 76 as a recording medium, a blast furnace operation control program for causing the computer 70 to function as the blast furnace operation control device 40 is stored in advance. Further, a storage area for storing various data is provided in the storage unit 76.

[0038] The input / output device 78 includes a pointing device such as a mouse, a keyboard, and a display unit, and is used for inputting various information.

[0039] The CPU 72 reads out the blast furnace operation control program from the storage unit 76 and expands it in the memory 74, and sequentially executes each step included in the blast furnace operation control program. Thereby, the computer 70 that has executed the blast furnace operation control program functions as the blast furnace operation control device 40.

[0040] (Functions of Blast Furnace Operation Control Device) Next, the functions of the blast furnace operation control device 40 will be described.

[0041] As shown in FIG. 3, when executing the above-described blast furnace operation control program, the blast furnace operation control device 40 realizes various functions by using the above hardware resources. Specifically, functionally, the blast furnace operation control device 40 includes a powder concentration determination unit 42 and a blast furnace operation condition change unit 44.

[0042] (Powder Concentration Determination Unit) The powder concentration determination unit 42 compares the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 with a predetermined threshold value. Then, the powder concentration determination unit 42 determines whether the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value.

[0043] Note that the threshold value of the powder concentration of the exhaust gas G2 is appropriately set based on the operation results of the blast furnace 10 and the like. Further, the threshold value of the powder concentration of the exhaust gas G2 is stored, for example, in a predetermined storage area of the storage unit 76.

[0044] Further, the powder concentration determination unit 42 may determine, for example, whether the average value of a plurality of powder concentrations measured by the powder concentration measuring device 30 is equal to or higher than the threshold value.

[0045] (Blast Furnace Operation Condition Change Unit) When the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, the blast furnace operation condition change unit 44 changes the flow rate of the in-furnace gas G1 rising in the blast furnace 10 as an example of the operation conditions of the blast furnace 10.

[0046] Specifically, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, the blast furnace operation condition change unit 44 first calculates the difference between the measured powder concentration of the exhaust gas G2 and the threshold value.

[0047] Next, the blast furnace operation condition changing unit 44 increases the flow velocity of the in-furnace gas G1 rising in the blast furnace 10 based on the calculated difference. That is, the blast furnace operation condition changing unit 44 increases the increase width (increase amount) of the flow velocity of the in-furnace gas G1 as the calculated difference becomes larger.

[0048] The flow velocity of the in-furnace gas G1 is adjusted by increasing or decreasing the pressure at the furnace top 10A of the blast furnace 10 by changing the opening degree of the damper 34 of the exhaust duct 32 connected to the furnace top 10A of the blast furnace 10.

[0049] Specifically, when the opening degree of the damper 34 is increased, the pressure at the furnace top 10A of the blast furnace 10 decreases, and the flow velocity of the in-furnace gas G1 rising in the blast furnace 10 increases. On the other hand, when the opening degree of the damper 34 is decreased, the pressure at the furnace top 10A of the blast furnace 10 increases, and the flow velocity of the in-furnace gas G1 rising in the blast furnace 10 decreases.

[0050] Thereby, as shown in FIG. 1, the powder (fine powder) of the blast furnace raw materials charged into the blast furnace 10 is easily discharged outside the blast furnace 10 through the exhaust duct 24 together with the in-furnace gas G1. Therefore, the decrease in the air permeability in the blast furnace 10 due to the increase in the powder amount in the blast furnace 10 is suppressed.

[0051] Further, after increasing the flow velocity of the in-furnace gas G1, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is less than the threshold value, the blast furnace operation condition changing unit 44 decreases the flow velocity of the in-furnace gas G1 rising in the blast furnace 10.

[0052] Note that the decrease width (decrease amount) of the flow velocity of the in-furnace gas G1 can be changed as appropriate. Therefore, for example, the blast furnace operation condition changing unit 44 may return the flow velocity of the in-furnace gas G1 to the flow velocity before the change, or may set it to a flow velocity different from that before the change.

[0053] Here, FIG. 4 shows an example of changing the flow velocity u of the in-furnace gas G1 based on the powder concentration C of the exhaust gas G2. In FIG. 4, the threshold value of the powder concentration C of the exhaust gas G2 is set to Cmax.

[0054] In FIG. 4, the difference between the powder concentration C of the exhaust gas G2 measured at time t1 and the threshold value Cmax is ΔC1. Based on this difference ΔC1, an increase width Δu1 of the flow velocity u of the in-furnace gas G1 is set.

[0055] Here, at time t2 after increasing the flow velocity of the in-furnace gas G1, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 (hereinafter referred to as "post-change powder concentration") is equal to or higher than the threshold value Cmax, such as Ca and Cb (Ca > Cb) (Ca, Cb ≧ Cmax), the blast furnace operation condition changing unit 44 further increases the flow velocity u of the in-furnace gas G1 by Δu2. At this time, the increase width Δu2 of the flow velocity u of the in-furnace gas G1 may be set based on the difference between the post-change powder concentrations Ca and Cb of the exhaust gas G2 at time t2 and the threshold value Cmax, or may be set to an arbitrary value. Note that time t2 is set, for example, several hours after time t1.

[0056] On the other hand, at time t2, if the post-change powder concentration of the exhaust gas G2 is less than the threshold value Cmax, such as Cc (Cc < Cmax), the blast furnace operation condition changing unit 44 decreases the flow velocity u of the in-furnace gas G1. At this time, the decrease width Δu3 of the flow velocity u of the in-furnace gas G1 may be set as Δu1 so as to return to the state before the change, or may be set to an arbitrary value.

[0057] Note that at time t2, if the measured powder concentration Cc of the exhaust gas G2 is less than the threshold value Cmax, the blast furnace operation condition changing unit 44 may maintain the flow velocity u of the in-furnace gas G1 without changing it.

[0058] (Blast Furnace Operation Method) Next, while explaining the operation of the blast furnace operation control device 40, an example of the blast furnace operation method will be described.

[0059] In the blast furnace operation control device 40, the blast furnace operation process shown in FIG. 5 is periodically executed. Note that the blast furnace operation process is an example of the blast furnace operation method.

[0060] As shown in FIG. 5, first, in step S10, the CPU 72 determines whether the dust concentration of the exhaust gas G2 measured by the dust concentration measuring device 30 is equal to or higher than a threshold value. Then, when the CPU 72 determines that the measured dust concentration of the exhaust gas G2 is equal to or higher than the threshold value, it proceeds to step S12.

[0061] Next, in step S12, the CPU 72 calculates the difference between the measured dust concentration of the exhaust gas G2 and the threshold value.

[0062] Next, in step S14, the CPU 72 increases the flow rate of the in-furnace gas G1 (see FIG. 1) rising in the blast furnace 10 based on the difference between the calculated dust concentration of the exhaust gas G2 and the threshold value. Specifically, as shown in FIG. 1, the CPU 72 increases the opening degree of the damper 34 of the exhaust duct 24 and reduces the pressure at the top 10A of the blast furnace 10.

[0063] As a result, the flow rate of the in-furnace gas G1 increases, and the powder (fine powder) of the iron ore charged into the blast furnace 10 is more likely to be discharged out of the blast furnace 10 through the exhaust duct 24 together with the in-furnace gas G1. Therefore, a decrease in the air permeability inside the blast furnace 10 is suppressed.

[0064] Next, in step S16, the CPU 72 increases the number of times of changing the operating conditions by one time. The initial value of the number of times of changing the operating conditions is set to 0 times.

[0065] Next, in step S18, after waiting for a predetermined time, the CPU 72 returns to step S10. The predetermined time (waiting time) for which the CPU 72 waits in step S18 is appropriately set based on the operating results and the like.

[0066] Next, in step S10, the CPU 72 determines again whether the dust concentration of the exhaust gas G2 measured by the dust concentration measuring device 30 is equal to or higher than the threshold value. Then, when the CPU 72 determines that the measured dust concentration of the exhaust gas G2 is equal to or higher than the threshold value, it proceeds to step S12.

[0067] In step S10, when the number of times of changing the operating conditions is 1 or more, the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 becomes the powder concentration after the change described above.

[0068] On the other hand, in step S10, when the CPU 72 determines that the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is less than the threshold value, it proceeds to step S20.

[0069] Next, in step S20, the CPU 72 determines whether the number of times of changing the operating conditions is 1 or more (the number of times of changing the operating conditions ≥ 1). When the CPU 72 determines that the number of times of changing the operating conditions is less than 1, that is, the number of times of changing the operating conditions is 0, the process ends.

[0070] On the other hand, in step S20, when the CPU 72 determines that the number of times of changing the operating conditions is 1 or more, it proceeds to step S22.

[0071] Next, in step S22, the CPU 72 decreases the flow velocity of the in-furnace gas G1 (see FIG. 1) rising in the blast furnace 10. Specifically, as shown in FIG. 1, the CPU 72 reduces the opening degree of the damper 34 of the exhaust duct 24 and increases the pressure at the top 10A of the blast furnace 10. Thereby, the flow velocity of the in-furnace gas G1 decreases.

[0072] Next, in step S24, the CPU 72 changes the number of times of changing the operating conditions to 0 and ends the process.

[0073] (Effect) Next, the effects of the present embodiment will be described.

[0074] As shown in FIG. 1, according to the present embodiment, the powder concentration of the exhaust gas G2 discharged from the top of the blast furnace 10 is measured by the powder concentration measuring device 30, and when the measured powder concentration of the exhaust gas is equal to or higher than the threshold value, as the operating condition of the blast furnace 10, the flow velocity of the in-furnace gas G1 is increased.

[0075] Here, when the amount of powder in the blast furnace 10 increases, the powder concentration of the exhaust gas G2 discharged from the top of the blast furnace 10 also increases. On the other hand, when the amount of powder in the blast furnace 10 decreases, the powder concentration of the exhaust gas G2 discharged from the top of the blast furnace 10 also decreases.

[0076] Therefore, in the present embodiment, as described above, the powder concentration of the exhaust gas G2 discharged from the top of the blast furnace 10 is measured by the powder concentration measuring device 30. Thereby, the estimation accuracy of the amount of powder in the blast furnace 10 can be improved. And when the measured powder concentration of the exhaust gas is equal to or higher than the threshold value, the flow rate of the in-furnace gas G1 is increased.

[0077] Thereby, the powder of the blast furnace raw material charged into the blast furnace 10 from the top can be discharged from the top together with the in-furnace gas G1 to the outside of the blast furnace 10. Therefore, the deterioration of the air permeability in the blast furnace 10 accompanying the increase in the amount of powder in the blast furnace 10 is suppressed, so that the decrease in the production efficiency of the blast furnace 10 can be suppressed.

[0078] Further, in the present embodiment, as shown in FIG. 4, based on the difference between the powder concentration C of the exhaust gas G2 measured by the powder concentration measuring device 30 and the threshold value Cmax, the increase width Δu1 of the flow rate u of the in-furnace gas G1 is changed. Thereby, the decrease in the production efficiency of the blast furnace 10 can be efficiently suppressed.

[0079] Furthermore, in the present embodiment, after increasing the flow rate u of the in-furnace gas G1, the changed powder concentration of the exhaust gas G2 discharged from the top is measured. And when the changed powder concentration is equal to or higher than the threshold value, the flow rate u of the in-furnace gas G1 is further increased. Thereby, the amount of powder in the blast furnace 10 can be efficiently reduced.

[0080] (Blast Furnace Operation Experiment) Next, the blast furnace operation experiment will be described.

[0081] In this experiment, as an example, the furnace volume is 4000 m 3In a blast furnace of a certain grade, the amount of powder (dust amount) in the exhaust gas discharged from the top of the furnace was measured. When the powder amount increased, as an operating condition of the blast furnace, the flow rate of the gas inside the furnace was changed, and the influence on CR (coke consumption per ton of hot metal) was verified.

[0082] Also, in this experiment, as the blast furnace operation related to the comparative example, when the amount of powder in the exhaust gas discharged from the top of the blast furnace increased, the influence on CR (coke consumption per ton of hot metal) was verified without changing the operating conditions of the blast furnace.

[0083] (Comparative Example) First, in FIGS. 6(A), 6(B), and 6(C), blast furnace operation data related to the comparative example are shown. The horizontal axis in FIGS. 6(A) to 6(C) indicates the number of operating days of the blast furnace.

[0084] Also, the vertical axis in FIG. 6(A) indicates the unit consumption (kg-dust / t-pig) per unit hot metal output by dividing the amount of powder discharged from the blast furnace per day (kg-dust / day) by the hot metal output per day (t-pig / day). The vertical axis in FIG. 6(B) indicates the flow rate of the gas inside the furnace (m / s). Further, the vertical axis in FIG. 6(C) indicates CR (coke consumption per ton of hot metal) (kg / t-pig).

[0085] As shown in FIG. 6(A), in the blast furnace operation related to the comparative example, the amount of powder in the exhaust gas increased rapidly on the 3rd day. In the blast furnace operation related to the comparative example, as shown in FIG. 6(B), the flow rate of the gas G1 inside the furnace was not forcibly changed.

[0086] As shown in FIG. 6(C), in the blast furnace operation related to the comparative example, CR increased rapidly on the 4th day. This is considered to be due to the deterioration of the air permeability inside the blast furnace with the increase in the amount of powder inside the blast furnace, resulting in a temperature drop inside the blast furnace and a delay in the reduction of the blast furnace raw materials, so the blowing rate (air + oxygen enrichment) from the tuyere was reduced.

[0087] (Example 1) In FIGS. 7(A), 7(B), and 7(C), blast furnace operation data according to Example 1 are shown. Note that the horizontal and vertical axes in FIGS. 7(A) to 7(C) are the same as the horizontal and vertical axes in FIGS. 6(A) to 6(C).

[0088] As shown in FIG. 7(A), in the blast furnace operation according to Example 1, on the third day, the amount of powder in the exhaust gas rapidly increased from about 8 to about 14 (kg-dust / t-pig).

[0089] Therefore, in the blast furnace operation according to Example 1, as shown in FIG. 7(B), on the fourth day, the flow rate of the in-furnace gas G1 was increased from about 2.8 to about 2.9 (m / s). As a result, as shown in FIG. 7(A), on the fourth day, the amount of powder in the exhaust gas did not increase and remained horizontal.

[0090] Furthermore, in the blast furnace operation according to Example 1, as shown in FIG. 7(B), on the fifth day, the flow rate of the in-furnace gas G1 was increased from about 2.9 to about 3.0 (m / s). As a result, as shown in FIG. 7(A), on the fifth day, the amount of powder in the exhaust gas decreased from about 14 to approximately 11 (kg-dust / t-pig).

[0091] Also, in the blast furnace operation according to Example 1, as shown in FIG. 7(C), CR remained approximately constant from the first day to the fifth day. From this, it can be seen that by increasing the flow rate of the in-furnace gas G1, a decrease in the production efficiency of the blast furnace was suppressed.

[0092] (Example 2) Next, in FIGS. 8(A), 8(B), and 8(C), blast furnace operation data according to Example 2 are shown. Note that the horizontal and vertical axes in FIGS. 8(A) to 8(C) are the same as the horizontal and vertical axes in FIGS. 6(A) to 6(C).

[0093] As shown in FIG. 8(A), in the blast furnace operation according to Example 2, on the third day, the amount of powder in the exhaust gas rapidly increased from about 9 to about 19 (kg-dust / t-pig).

[0094] Therefore, in the blast furnace operation according to Example 2, as shown in FIG. 8(B), on the fourth day, the flow rate of the in-furnace gas G1 was increased from about 2.8 to about 3.1 (m / s). As a result, as shown in FIG. 8(A), on the fourth day, the amount of powder in the exhaust gas decreased from about 19 to about 13 (kg-dust / t-pig).

[0095] Furthermore, in the blast furnace operation according to Example 2, since the amount of powder in the exhaust gas decreased on the fourth day, on the fifth day, the flow rate of the in-furnace gas G1 was decreased from about 3.1 to about 2.9 (m / s), which is faster than the initial flow rate (about 2.8). As a result, as shown in FIG. 8(A), on the fifth day, the amount of powder in the exhaust gas decreased from about 13 to about 10 (kg-dust / t-pig).

[0096] Also, in the blast furnace operation according to Example 2, as shown in FIG. 8(C), CR was approximately constant from the first day to the fifth day. From this, it can be seen that by increasing the flow rate of the in-furnace gas G1, a decrease in the production efficiency of the blast furnace was suppressed.

[0097] Note that on the fourth day, it is presumed that the amount of powder in the blast furnace temporarily increased. However, by setting the flow rate of the in-furnace gas G1 to about 2.9 (m / s) without returning it to the initial about 2.8 (m / s), an increase in the amount of powder in the blast furnace is considered to have been suppressed.

[0098] (Modification example) Next, a modification example of the above embodiment will be described.

[0099] In the above embodiment, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, the flow rate of the in-furnace gas G1 is changed as an operating condition of the blast furnace 10. However, the operating conditions of the blast furnace 10 are not limited to the flow rate of the in-furnace gas G1, and may be, for example, the heat flow ratio in the blast furnace 10.

[0100] Specifically, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, as the operating condition of the blast furnace 10, the heat flow ratio inside the blast furnace 10 is decreased. The heat flow ratio inside the blast furnace 10 is adjusted by increasing or decreasing the oxygen enrichment rate of the oxygen (pure oxygen) added to the air (hot air) blown into the blast furnace 10 from the tuyere 12.

[0101] The oxygen enrichment rate is an index indicating the oxygen concentration enriched from the oxygen concentration in the air (21%). When this oxygen enrichment rate is increased, the heat capacity of the furnace gas G1 becomes smaller and the heat flow ratio increases. On the other hand, when the oxygen enrichment rate is decreased, the heat capacity of the furnace gas G1 becomes larger and the heat flow ratio decreases. This oxygen enrichment rate is adjusted by the amount of oxygen (pure oxygen amount) and the amount of air added to the air (hot air) blown into the blast furnace 10 from the tuyere 12.

[0102] In this way, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, by decreasing the heat flow ratio inside the blast furnace 10, it is possible to suppress the temperature drop inside the blast furnace 10 accompanying the increase in the amount of powder inside the blast furnace 10. As a result, the reduction delay of the blast furnace raw materials inside the blast furnace 10 is suppressed. Therefore, it is possible to suppress the decrease in the production efficiency of the blast furnace 10.

[0103] Also, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, the powder ratio of the blast furnace raw materials charged into the blast furnace 10 may be changed.

[0104] Specifically, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, the blast furnace raw materials charged into the blast furnace 10 are changed to blast furnace raw materials with a small powder ratio. For example, as the blast furnace raw materials charged into the blast furnace 10 from the top of the furnace, there are coke and sinter ore stored in the yard (hereinafter referred to as "yard blast furnace raw materials"). This yard blast furnace raw material has a higher powder ratio (powder amount) compared to the coke and sinter ore directly sent from the coke oven and sintering furnace to the blast furnace (hereinafter referred to as "directly sent blast furnace raw materials").

[0105] Therefore, for example, when charging yard blast furnace raw materials into the blast furnace 10 from the furnace top, if the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, at least a part of the yard blast furnace raw materials is replaced with direct charge blast furnace raw materials. As a result, the powder ratio of the blast furnace raw materials charged into the blast furnace 10 from the furnace top becomes smaller, so the amount of powder in the blast furnace 10 is reduced. Therefore, since the deterioration of the air permeability in the blast furnace 10 accompanying the increase in the amount of powder in the blast furnace 10 is suppressed, the decrease in the production efficiency of the blast furnace 10 can be suppressed.

[0106] Also, generally, before charging blast furnace raw materials into the blast furnace 10 from the furnace top, the blast furnace raw materials are screened by a screening device. Therefore, when the powder concentration of the exhaust gas G2 measured by the powder concentration measuring device 30 is equal to or higher than the threshold value, for example, the screening device may be adjusted so that the powder ratio of the blast furnace raw materials becomes smaller. As a result, the powder ratio of the blast furnace raw materials charged into the blast furnace 10 from the furnace top becomes smaller, so the amount of powder in the blast furnace 10 is reduced. Therefore, since the deterioration of the air permeability in the blast furnace 10 accompanying the increase in the amount of powder in the blast furnace 10 is suppressed, the decrease in the production efficiency of the blast furnace 10 can be suppressed.

[0107] In the above embodiment, the powder concentration measuring device 30 measures the powder concentration of the exhaust gas G2. However, for example, within a predetermined time, the amount of powder (dust amount) collected (stored) in the dust catcher 26 may be measured, and the measured amount of powder may be used as the powder concentration.

[0108] In the above embodiment, the control unit (processor) includes a general-purpose processor (for example, CPU: Central Processing Unit, etc.) or a dedicated processor (for example, GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic device, etc.).

[0109] Also, the processing flow in the blast furnace operation control device 40 described in the above embodiment is also an example, and within the scope not departing from the gist of the technology disclosed in the present application, unnecessary steps may be deleted, new steps may be added, or the processing order may be changed.

[0110] Also, in the above embodiment, the form in which each program is installed in the ROM or storage has been described, but it is not limited thereto. Each program according to the above embodiment may be provided in a form recorded on a computer-readable storage medium. For example, each program according to the above embodiment may be provided in a form recorded on an optical disk such as a CD (Compact Disc)-ROM and a DVD (Digital Versatile Disc)-ROM, or in a form recorded on a semiconductor memory such as a USB (Universal Serial Bus) memory and a memory card. Also, each program according to the above embodiment may be acquired from an external device via a communication I / F.

[0111] As described above, one embodiment of the present invention has been described, but the present invention is not limited to such an embodiment, and one embodiment and various modifications may be used in appropriate combination, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

Explanation of Reference Numerals

[0112] 10 Blast furnace 40 Blast furnace operation control device 72 CPU (control unit) G1 In-furnace gas G2 Exhaust gas

Claims

1. Measuring the powder concentration of the exhaust gas discharged from the top of the blast furnace, When the measured powder concentration is equal to or higher than the threshold value, changing the operating conditions of the blast furnace, A blast furnace operating method.

2. Changing the amount of change in the operating conditions based on the difference between the measured powder concentration and the threshold value, The blast furnace operating method according to Claim 1.

3. After changing the operating conditions, measuring the powder concentration of the exhaust gas discharged from the top of the furnace as the powder concentration after change, When the measured powder concentration after change is equal to or higher than the threshold value, further changing the operating conditions, The blast furnace operating method according to Claim 1 or Claim 2.

4. The operating conditions include at least one of the flow rate of the gas rising in the blast furnace, the heat flow ratio in the blast furnace, and the powder ratio of the blast furnace raw materials charged into the blast furnace, The blast furnace operating method according to Claim 1.

5. Measuring the powder concentration of the exhaust gas discharged from the top of the blast furnace, When the measured powder concentration is equal to or higher than the threshold value, changing the operating conditions of the blast furnace, A blast furnace operating control device including a control unit for executing processing.

6. Measuring the powder concentration of the exhaust gas discharged from the top of the blast furnace, When the measured powder concentration is equal to or higher than the threshold value, changing the operating conditions of the blast furnace, A blast furnace operating control program for causing a computer to execute processing.

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