Blast furnace operating methods, control devices, and programs

Abstract

To appropriately control a position where ores are charged.SOLUTION: An operation method of a blast furnace 11 includes an ore charging process in which ores are charged into the blast furnace 11 to form an ore layer 21, and a coke charging process in which coke is charged into the blast furnace 11 to form a coke layer 22, where the blast furnace 11 is operated by alternately forming the ore layer 21 and the coke layer 22. In the ore charging step, by adjusting the radial position of the blast furnace 11 with respect to the ores charged on the coke layer 22, the central coke layer 22 located at the center of the blast furnace 11 is exposed from the ore layer 21 to the upper part. In the ore charging step, the radial position of the blast furnace 11 with respect to the ores is adjusted so that the flowing position E of the ore layer 21 falls within a target range determined on the basis of an index indicating the operational stability of the blast furnace 11.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] In the operation of a blast furnace, it is important to appropriately manage the distribution of charged materials and control the distribution of reducing gas flow in the furnace. Conventionally, a method of stabilizing the blast furnace operation by concentrating a part of the gas flow in the central part of the furnace to obtain a stable central gas flow has been known. For example, as disclosed in Patent Document 1 below, the coke layer in the central part located at the center of the blast furnace is exposed from the surface of the charged materials, or as disclosed in Patent Document 2 below, the coke layer in the central part penetrates the central part of the furnace, and there are methods such as reliably securing a gas flow path. Further, as disclosed in Patent Document 3 below, there is a method of securing a central gas flow by adjusting the charging order so that fine-grained sinter does not flow into the center.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a blast furnace operation method that exposes the central coke layer from the ore layer, the inventors found, based on the following findings, that it is important to appropriately manage the position where the ore is charged. Specifically, if too much ore flows into the center of the blast furnace, the gas will circulate to the periphery, making the gas flow unstable. Conversely, if the ore flow is insufficient and the area of ​​coke alone in the center becomes too large, the central gas flow will become too strong, worsening the reduction of the ore, and the unreduced ore will descend inside the furnace, making the operation unstable. The area of ​​coke alone in the center refers to the central coke layer located at the center of the blast furnace. The area of ​​coke alone in the center is a part of the coke layer, a coke layer located in the center of the blast furnace, and is the part above which the ore layer has not formed.

[0005] This invention has been made in view of the circumstances described above, and aims to appropriately control the location in which ores are charged. [Means for solving the problem]

[0006] <1> A blast furnace operation method according to one aspect of the present invention includes an ore charging step of charging ores into the blast furnace to form an ore layer, and a coke charging step of charging coke into the blast furnace to form a coke layer, wherein the blast furnace is operated by alternately forming the ore layer and the coke layer, wherein in the ore charging step, the radial position of the blast furnace with respect to the ores charged onto the coke layer is adjusted so that the central part of the coke layer located at the center of the blast furnace is exposed above the ore layer, and in the ore charging step, the radial position of the blast furnace with respect to the ores is adjusted so that the inflow position of the ore layer falls within a target range determined based on an indicator of the stability of the operation of the blast furnace. Furthermore, adjusting the radial position of the blast furnace with respect to the ore being charged onto the coke layer means adjusting the radial position of the charged ore after it falls onto the coke layer. Also, the inflow position of the ore layer is the radial position of the innermost part of the ore layer deposited on the coke layer (the inner edge of the ore layer).

[0007] In the ore charging process, the radial position of the ore in the blast furnace is adjusted so that the inflow location of the ore layer falls within a predetermined target range based on indicators of the stability of the blast furnace operation. Therefore, the location where the ore is charged can be appropriately controlled based on the target range.

[0008] <2> the above <1> In the blast furnace operation method relating to the above, the ore charging process may employ a configuration that adjusts the radial position of the ore relative to the ore based on the shape of the ore layer formed by the ore charging process carried out prior to the ore charging process in question.

[0009] In the ore charging process, the radial position of the blast furnace relative to the ore is adjusted based on the shape of the ore layer formed by an ore charging process carried out prior to the target ore charging process. Therefore, for example, the radial position of the blast furnace relative to the ore is adjusted according to errors that occur during actual operation. This makes it possible to more appropriately control the position in which the ore is charged.

[0010] <3> the above <2> In the blast furnace operation method relating to the above, in the ore charging process, the shape of the ore layer may be obtained as the shape of the ore layer over the entire circumference of the blast furnace, and the radial position of the ore in the blast furnace may be adjusted over the entire circumference of the blast furnace.

[0011] In the ore charging process, the shape of the ore layer is obtained as the shape of the ore layer around the entire circumference of the blast furnace, and the radial position of the ore in the blast furnace is adjusted around the entire circumference of the furnace. This allows for appropriate control of the position in which the ore is charged around the entire circumference.

[0012] <4> the above <1> from <3> In a blast furnace operation method according to any one of the embodiments, when the radial position of the blast furnace on the coke layer is represented by a dimensionless value where the distance from the central axis of the blast furnace to the furnace wall of the blast furnace is set to 1, the target range may be set to a range of 0.02 or more and 0.25 or less.

[0013] By setting the target range to the aforementioned range, the central coke layer is positioned within a range appropriate for stable operation of the blast furnace, and the distribution of reducing gas flow within the furnace can be controlled.

[0014] <5> the above <1> from <4> In the blast furnace operation method according to any one of the embodiments, the ore charging process may employ a configuration in which a bellless charging device charges the ore into the blast furnace, and the charging device adjusts the radial position of the ore in the blast furnace by adjusting at least one of the notch and rotation number when the ore is charged to the innermost radial position of the blast furnace in each dump of the ore.

[0015] The charging device adjusts the radial position of the ore in the blast furnace by adjusting the notch and rotation count when charging the ore to the innermost radial point of the blast furnace in each ore dump. Therefore, the accuracy of the ore layer inflow position, that is, the position of the radial inner edge of the ore layer, can be improved.

[0016] <6> A control device according to one aspect of the present invention is a control device for controlling a charging device that alternately stacks ore layers and coke layers in a blast furnace, and by controlling the charging device, the radial position of the blast furnace with respect to the ore charged onto the coke layer is adjusted so that the central part of the coke layer located at the center of the blast furnace is exposed above the ore layer, and the radial position of the blast furnace with respect to the ore is adjusted so that the inflow position of the ore layer falls within a target range determined based on an indicator of the stability of the operation of the blast furnace. <7> the above <6> In the control device relating to the present invention, the blast furnace may be provided with a shape acquisition unit that acquires the shape of the ore layer inside the blast furnace, and the control device may adopt a configuration that controls the charging device based on the acquisition results of the shape acquisition unit. <8> A program according to one aspect of the present invention provides a computer with the above <6> or <7> It will function as a control device related to that. [Effects of the Invention]

[0017] According to the present invention, the position where ore is charged can be appropriately managed.

Brief Description of the Drawings

[0018] [Figure 1] It is a block diagram showing a blast furnace system according to an embodiment of the present invention. [Figure 2] It is a longitudinal sectional view showing the inside of the blast furnace constituting the blast furnace system shown in FIG. 1. [Figure 3] It is a graph showing the relationship between the coke ratio CR and the standard deviation σ of the blast pressure in the blast furnace. [Figure 4] It is a graph showing the relationship between the flow-in position of the ore layer and the standard deviation σ of the blast pressure in the blast furnace. [Figure 5] It is a diagram showing the change in the charging position before and after adjusting the charging position of the ores.

Embodiments for Carrying Out the Invention

[0019] (Blast Furnace System) Hereinafter, referring to FIGS. 1 to 4, a blast furnace system 10 according to an embodiment of the present invention will be described. As shown in FIG. 1, the blast furnace system 10 is a system including a blast furnace 11 and devices necessary for operating the blast furnace 11. In addition to the blast furnace 11, the blast furnace system 10 includes a charging device 12 and a control device 13.

[0020] As shown in FIG. 2, in the blast furnace 11, an ore layer 21 and a coke layer 22 are alternately laminated. The ore layer 21 and the coke layer 22 form a laminate in the blast furnace 11. The ore layer 21 is a layer of ores. As the ores, not only ore but also, for example, pellet sintered ore, reduced iron, etc. can be mentioned. The coke layer 22 is a layer of coke. Hereinafter, the ores and coke are collectively referred to as blast furnace raw materials.

[0021] As shown in Figure 1, the blast furnace 11 is equipped with a shape acquisition unit 14 and a charging depth gauge 15. The shape acquisition unit 14 acquires the shape of the ore layer 21 inside the blast furnace 11. Examples of the shape acquisition unit 14 include a profile meter. Examples of profile meters include a two-dimensional profile meter and a three-dimensional profile meter. A two-dimensional profile meter can acquire the shape of the ore layer 21 at a specific position (orientation) in the circumferential direction of the blast furnace 11. A three-dimensional profile meter can acquire the shape of the ore layer 21 over the entire circumference of the blast furnace 11. When acquiring the shape of the ore layer 21 at multiple positions (orientations) in the circumferential direction of the blast furnace 11, multiple two-dimensional profile meters may be provided, or one three-dimensional profile meter may be provided. The shape of the ore layer 21 may, for example, include information showing the relationship between the height information of the ore layer 21 acquired by a profile meter or the like and the position from which that height information was acquired (the radial position of the blast furnace). In this case, the radial position of the blast furnace 11 may be a dimensionless value when the distance from the central axis L of the blast furnace 11 to the furnace wall 11a of the blast furnace 11 is set to 1.

[0022] The charging depth gauge 15 measures the stock line (SL). The stock line is the height position of the stacked material inside the blast furnace 11. Any known configuration can be appropriately used for the charging depth gauge 15. The stock line can be adjusted, for example, by tapping molten iron from the blast furnace 11.

[0023] As shown in Figure 2, the charging device 12 alternately stacks ore layers 21 and coke layers 22 inside the blast furnace 11. As the charging device 12, for example, a bell-type device or a bell-less device can be used. In this embodiment, the charging device 12 is a bell-less device. The charging device 12 is equipped with a chute (not shown) for charging ore and coke into the blast furnace 11. The radial position of the charging device 12 within the blast furnace 11 into which the blast furnace raw materials are charged can be changed, for example, based on a notch (the tilt angle of the chute with respect to the vertical axis).

[0024] The charging device 12 does not continuously charge blast furnace materials into the blast furnace 11, but charges them at intervals. One charge is a unit in which the ore layer 21 and the coke layer 22 are alternately stacked in the blast furnace 11. One charge is carried out by multiple dumps. One dump is a unit in which the same type of blast furnace material is charged. In this embodiment, in some of the multiple dumps in one charge, coke is charged, and in the remaining dumps, ore is charged.

[0025] In a single dump, the chute is rotated multiple times while the blast furnace material is charged into the blast furnace 11 from the chute. At this time, the tilt angle (notch) of the chute differs with each rotation, so that the blast furnace material is charged over a wide radial area within the blast furnace 11. The notch may be made larger or smaller with each rotation. In other words, the blast furnace material may be charged from the radial outside to the inside, or from the radial inside to the outside.

[0026] The control device 13 is configured, for example, by a computer. The control device 13 includes, for example, a processor such as a CPU (Central Processing Unit) connected by a bus, and memory, and executes programs. The computer functions as the control device 13 by executing programs. Furthermore, all or part of the functions of the control device 13 may be implemented using hardware such as an ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), or FPGA (Field Programmable Gate Array). The program may be recorded on a computer-readable recording medium. Computer-readable recording media include, for example, portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. The program may also be transmitted via a telecommunications line.

[0027] The control device 13 controls the charging device 12. The control device 13 adjusts the radial position of the blast furnace 11 with respect to the ore being charged onto the coke layer 22 (the coke layer 22 formed by the previous coke charging (dumping)). The control device 13 adjusts the position of the charged ore after it has fallen onto the coke layer 22. The control device 13 adjusts the position of the ore by, for example, (1) adjusting the notch of the charging device 12, (2) adjusting the start timing of charging of ore from the charging device 12 according to the stock line, or (3) adjusting the amount of ore charged from the charging device 12.

[0028] Regarding (1) above, by adjusting the notch of the charging device 12, the charging direction (falling direction) of the ore being charged from the chute into the blast furnace 11 changes. As a result, the position of the ore changes. Regarding (2) above, the stock line is related to the landing position of the ore charged by the charging device 12. That is, the position of the ore changes depending on the position of the stock line (height of the coke layer 22), even if the charging direction is the same. Therefore, the position of the ore can be changed by adjusting the start timing of the charging of the ore from the charging device 12 according to the stock line. Regarding (3) above, for example, if the amount of ore charged is large, the charged ore will be piled up high, and the pile of ore will collapse (at this time, for example, the ore will flow radially inward). As a result, the ore will move radially on the coke layer 22, and the position of the ore will change. The amount of ore charged can be adjusted, for example, according to the number of turns.

[0029] The relationship between each of the adjustment amounts (1) to (3) above and the position of the ore can be obtained in advance, for example, through verification tests conducted beforehand. This information about the relationship is stored in the control device 13. As a result, the control device 13 can set each adjustment amount according to the desired position of the ore. Here, the verification tests include not only verification tests using actual machines or test machines, but also computer simulations. Although the objects in (1) to (3) above are ores, the radial position of coke in the blast furnace 11 can also be adjusted using a similar method. Furthermore, the method for adjusting the position of ores and coke (blast furnace raw materials) is not limited to the methods for adjusting the objects in (1) to (3) above.

[0030] The control device 13 adjusts the position of the ore so that, as shown in Figure 2, the central coke layer 22 (also called the central coke 23) located at the center of the blast furnace 11 is exposed above the ore layer 21. At this time, the control device 13 adjusts the radial position of the blast furnace 11 with respect to the ore so that the inflow position E of the ore layer 21 falls within a predetermined target range. The target range of the inflow position E of the ore layer 21 (hereinafter simply referred to as the target range) is stored in the control device 13. The specific details of the target range will be described later. Here, the inflow position E of the ore layer 21 is the radial position of the innermost part of the ore layer 21 that is deposited on the coke layer 22 (the inner edge of the ore layer 21).

[0031] Furthermore, the upper surface of the central coke 23 is exposed above the ore layer 21 throughout its entire length. However, there may be some ore present on the upper surface of the central coke 23 in an amount that does not substantially affect operations. Furthermore, the ore layer 21 completely covers the coke layer 22 from above, except for the central coke layer 23. When viewed from above, the ore layer 21 has a ring shape.

[0032] The control device 13 controls the charging device 12 and adjusts the position of the ore so that the inflow position E of the ore layer 21 falls within the target range. In other words, the control device 13 controls the charging device 12 so that the innermost ore being charged is charged at a predetermined position within the target range, and ore is charged over the entire area radially outside this predetermined position. The control device 13 may adjust the position of the ore by, for example, adjusting at least one of the notch and the number of rotations when the charging device 12 charges the innermost ore radially into the blast furnace 11 in each ore dump. The control device 13 may adjust only the notch, only the number of rotations, or both the notch and the number of rotations.

[0033] As shown in Figure 1, the control device 13 is connected to a shape acquisition unit 14 and an insertion depth meter 15. The control device 13 can receive results from the shape acquisition unit 14 and the insertion depth meter 15. The control device 13 controls the insertion device 12 based on the acquisition results from the shape acquisition unit 14 and the measurement results from the insertion depth meter 15. The control device 13 determines the inflow position E of the ore layer 21 based on the results obtained by the shape acquisition unit 14, and controls the charging device 12 based on the inflow position E of the ore layer 21.

[0034] (Operation method of blast furnace 11) Next, the operating method of the blast furnace 11 in the blast furnace system 10 described above (hereinafter also simply referred to as the operating method) will be explained. This operating method includes an ore charging process and a coke charging process. In the ore charging process, the charging device 12 charges ore into the blast furnace 11 to form an ore layer 21. In the coke charging process, the charging device 12 charges coke into the blast furnace 11 to form a coke layer 22. In this operating method, the charging device 12 operates the blast furnace 11 by alternately forming the ore layer 21 and the coke layer 22.

[0035] For example, the ore charging process is equivalent to dumping the ore during one charge. The coke charging process is equivalent to dumping the coke during one charge. Alternating between the ore charging process and the coke charging process is equivalent to performing multiple charges.

[0036] In this embodiment, during the ore charging process (dumping of ore), the control device 13 adjusts the radial position of the blast furnace 11 with respect to the ore being charged onto the coke layer 22 (the coke layer 22 formed by the preceding coke charging process (dumping of coke)). This exposes the central coke 23 above the ore layer 21. At this time, the control device 13 adjusts the position of the ore so that the radial position of the blast furnace 11 with respect to the inflow position E of the ore layer 21 falls within the aforementioned target range.

[0037] In this case, the position of the ore may be adjusted based on the shape of the ore layer 21 formed by an ore charging process carried out prior to the target ore charging process (for example, the ore layer 21 formed by a previous charge). In this case, the shape of the ore layer 21 may be acquired as the shape of the ore layer 21 over the entire circumference of the blast furnace 11, and the radial position of the ore in the blast furnace 11 may be adjusted over the entire circumference of the blast furnace 11. Here, the control device 13 can acquire the shape of the ore layer 21 as the result of the shape acquisition unit 14.

[0038] In other words, if the target location of the ore is set in advance, the operator and the control device 13 can consider the operation beforehand and set the control values ​​for the charging device 12 related to the location of the ore in the control device 13, for example, before the operation of the blast furnace 11. However, actual operations may differ from prior planning, and the location of the ore may not be in the intended location. Therefore, the control device 13 adjusts the position of the ore based on the shape acquisition results (inflow position E of the ore layer 21) obtained by the shape acquisition unit 14, thereby improving the accuracy of the ore position. In this case, if the inflow position E of the ore layer 21 is located radially outside the target range, the ore charging position (position after the ore falls) is moved radially inside. The specific adjustment of the ore charging position can be carried out as needed, for example, based on the test results obtained by conducting offline tests in advance. Also, if the inflow position E of the ore layer 21 is located radially inside the target range, the ore charging position is moved radially outside. In this way, the control device 13 may adjust the error in the ore position based on the inflow position E of the ore layer 21. The error is thought to be caused by, for example, the influence of deposits on the furnace body, deviations in the circumferential position of pulverized coal injection, and variations in raw material properties.

[0039] The shape of the ore layer 21 may include, for example, a cross-sectional shape along the central axis of the blast furnace 11. The cross-sectional shape of the ore layer 21 may be obtained as a single cross-section or as multiple cross-sections. The control device 13 can obtain the inflow position E of the ore layer 21 based on the cross-sectional shape of the ore layer 21. However, the shape of the ore layer 21 to be obtained is not limited to the cross-sectional shape. For example, if the shape of the ore layer 21 (inflow position E of the ore layer 21) is obtained at multiple locations in the circumferential direction, the control device 13 may use representative values ​​for the inflow position E of the ore layer 21 at multiple locations to adjust the position of the ore. Representative values ​​may include, for example, the average, minimum, maximum, median, and mode of multiple values.

[0040] Furthermore, adjusting the position of ores over the entire circumference includes not only continuously adjusting the position of ores over the entire circumference, but also intermittently adjusting the position of ores over the entire circumference. For example, adjusting the position of ores at equal intervals (equal angles around the central axis L) over the entire circumference is also included in adjusting the position of ores over the entire circumference.

[0041] Furthermore, when the control device 13 adjusts the position of the ore over the entire circumference, the inflow position E of the ore layer 21 may not fall within the target range at all positions (orientations) over the entire circumference due to the effects of the aforementioned errors. In this case, it is desirable that the inflow position E of the ore layer 21 falls within the target range at least 50% of the positions (orientations), more preferably at least 80% of the positions (orientations), and even more preferably at least 90% of the positions (orientations).

[0042] (Target range) The target range is set, for example, by verification tests conducted in advance. Verification tests include not only verification tests using actual equipment or test machines, but also computer simulations. The target range is set in advance based on indicators (operational management indicators) that show the operational stability of the blast furnace 11. Examples of indicators include fluctuations in blower pressure, furnace body heat load, and permeability indicators. If fluctuations in blower pressure are used as an indicator, a smaller fluctuation indicates more stable operation of the blast furnace 11. The target range is the range in which the blast furnace 11 has been confirmed to operate stably through verification tests conducted in advance.

[0043] In this embodiment, as shown in Figure 2, the target range is explained assuming that the radial position of the blast furnace 11 on the coke layer 22 is represented by a dimensionless value where the distance from the central axis L of the blast furnace 11 to the furnace wall 11a of the blast furnace 11 is set to 1. In this dimensionless value, the central axis L is 0, the furnace wall 11a is 1, and the value increases as you move from the central axis L towards the furnace wall 11a (from the inside to the outside in the radial direction). For example, the target range is preferably 0.02 or more and 0.25 or less in the above dimensionless value. Furthermore, the target range is more preferably 0.04 or more and 0.2 or less in the above dimensionless value. However, the target range is not limited to these values. For example, verification tests can be conducted for each operating assumption, and the target range can be set appropriately according to the operating assumption.

[0044] In this embodiment, the reason for determining the target range as described above is explained below. In this embodiment, as an indicator for setting the target range, we focused on the fluctuation of the airflow pressure, specifically the standard deviation σ in the time-series change of the airflow pressure (hereinafter sometimes referred to as airflow pressure σ). First, the relationship between blowing pressure σ and operational stability will be explained using Figure 3. Figure 3 is a graph (scatter plot) showing the relationship between the coke ratio CR and the standard deviation σ of the blowing pressure in blast furnace 11. The horizontal axis of Figure 3 represents the coke ratio CR (kg / t), and the vertical axis represents the blowing pressure σ (hPa). The plots in the graph of Figure 3 represent one case of past operational performance. The coke ratio CR represents the amount of coke required to produce 1 ton of molten iron. A lower coke ratio CR indicates more stable operation. As an example, if the coke ratio CR is less than 320 kg / t, the operation can be said to be generally good. Figure 3 shows that when CR < 320 kg / t, the blowing pressure σ was 50 hPa or less. Therefore, a blowing pressure σ of 50 hPa or less indicates stable operation.

[0045] Next, the relationship between the inflow position E of the ore layer 21 and the blowing pressure σ will be explained using Figure 4. Figure 4 is a graph (scatter plot) showing the relationship between the inflow position E of the ore layer 21 in the blast furnace 11 and the standard deviation σ of the blowing pressure. The horizontal axis of Figure 4 represents the inflow position E of the ore layer 21, which is represented by the dimensionless value mentioned above, and the vertical axis represents the blowing pressure σ (hPa). The plots in the graph of Figure 4 represent one case from past operational performance. From Figure 4, when the blowing pressure σ is 50 hPa or less, the inflow position E of the ore layer 21 is at least within the range of 0.02 to 0.25, and preferably within the range of 0.04 to 0.2. When the inflow position E of the ore layer 21 is 0.02 to 0.25, the blowing pressure σ is 50 hPa for at least some of the plots among the multiple plots located at each inflow position E. When the inflow position E of the ore layer 21 is 0.04 to 0.2, the blowing pressure σ is 50 hPa for all of the multiple plots located at each inflow position E.

[0046] From the above, it is considered that a stable central gas flow can be secured by controlling the inflow position E of the ore layer 21 to 0.02 or more, 0.25 or less, and more preferably 0.04 or more, 0.2 or less. As a result of appropriately forming the gas flow inside the furnace, it is considered that stable operation can be continued. Furthermore, if the inflow position E of the ore layer 21 exceeds the upper limit, that is, if the central coke 23 expands, the furnace gas may excessively flow towards the center of the furnace, potentially reducing the gas utilization rate (it may escape without being used for reduction or heating). On the other hand, if the inflow position E of the ore layer 21 falls below the lower limit, the furnace gas may excessively flow near the furnace wall 11a, potentially increasing the amount of heat removed from the furnace body and leading to an increase in the input heat (reducing agent ratio).

[0047] The method for setting the target range, as described above, is summarized below. (1) Based on past operating results, create a scatter plot graph G1 showing the relationship between the coke ratio CR and an indicator (e.g., blowing pressure σ). (2) For the graph G1 created above, identify the range R1 that indicates stable operation (for example, CR < 320 kg / t), and identify the threshold T1 of the indicator within that range R1 (for example, the blowing pressure σ is 50 hPa or less). (3) Based on past operational records, etc., data on the relationship between the indicator and the inflow location E of the ore layer 21 is plotted, and graph G2 (scatter plot) is created. (4) Draw a straight line with respect to the threshold T1 of the indicator that indicates stable operation (gas flow) (for example, when the blowing pressure σ is 50 hPa), and check the data plotted in graph G2 within the range R2 on the side of this line that indicates more stable operation. (4-1) Among the multiple plots showing the inflow position E of the ore layer 21, the upper and lower limits UL1 and LL1 (for example, 0.02 or more and 0.25 or less) when at least a portion of them satisfy the conditions of (4) above shall be set as the upper and lower limits of the preferred target range. (4-2) Among the multiple plots showing the inflow position E of the ore layer 21, the upper and lower limits UL2 and LL2 (for example, 0.04 or more and 0.2 or less) when all of them satisfy the conditions of (4) above are set as the upper and lower limits of the more preferable target range. Regarding (1) above, instead of the coke ratio CR, operational indicators such as the reducing agent ratio (RAR) or pulverized coal ratio (PCR) can be used. Also, regarding (1) above, instead of the blowing pressure σ, outcome indicators such as the permeability index or furnace body heat load may be used.

[0048] As described above, according to the system and operating method of the blast furnace 11 of this embodiment, in the ore charging process, the radial position of the blast furnace 11 with respect to the ore is adjusted so that the inflow position of the ore layer 21, which is the sole area of ​​the central coke 23, falls within a target range predetermined based on an indicator of the stability of the operation of the blast furnace 11. Therefore, the position in which the ore is charged can be appropriately controlled based on the target range.

[0049] In the ore charging process, the radial position of the blast furnace 11 relative to the ore is adjusted based on the shape of the ore layer 21 formed by an ore charging process carried out prior to the target ore charging process. Therefore, for example, the radial position of the blast furnace 11 relative to the ore is adjusted according to errors that occur during actual operation. This makes it possible to more appropriately control the position in which the ore is charged. Furthermore, in the ore charging process, if the shape of the ore layer 21 is obtained as the shape of the ore layer 21 extending around the entire circumference of the blast furnace 11, and the radial position of the ore relative to the blast furnace 11 is adjusted around the entire circumference of the blast furnace 11, the position in which the ore is charged can be appropriately controlled around the entire circumference. [Examples]

[0050] (Example 1) In Example 1, it was verified that the charging device 12 is capable of charging ore so that the inflow position E of the ore layer 21 falls within a predetermined target range. In Example 1, a 1 / 3 bellless test apparatus was used as the charging apparatus 12. Blast furnace raw materials were charged into this test apparatus, and the relationship between the ore charging method and the position of the ore was investigated.

[0051] The 1 / 3 bellless test apparatus is a model experimental apparatus (approximately 1800 mm in radius) that is 1 / 3 the size of an actual furnace and is modeled after a bellless top charging apparatus. The average particle size was set to approximately 1 / 3 of that of an actual furnace, and the charge volume was set to approximately 1 / 27 of that of an actual furnace. The amount of coke charged per charge was set to approximately 1.3 tons, and the amount of ore charged per charge was set to approximately 7.3 tons.

[0052] The three-dimensional sedimentary shape of ore layer 21 was measured using a three-dimensional profile meter. This measured three-dimensional sedimentary shape was then cut out at 36 locations at 10° intervals around the furnace circumference, and the sedimentary shape in each direction was obtained. After obtaining the sedimentary shape in each direction, the inflow position E of the ore layer 21 in each direction was calculated. The calculated inflow position E of the ore layer 21 was non-dimensionalized by dividing it by the furnace opening radius.

[0053] The results are shown in Figure 5. Figure 5 is a diagram showing the inflow position E of the ore layer 21 when the test apparatus is viewed from above. The center position of the circle shown in Figure 5 is the position directly below the test apparatus (chute) (the position of the central axis L of the blast furnace 11). Dividing lines are drawn around the entire circumference of this circle, dividing it into 36 equal parts at 10° intervals in the circumferential direction of the furnace, as described above. The dividing lines indicate each position (direction) in the circumferential direction of the blast furnace 11. In this circle, as the distance from the center position along the dividing lines increases, it means moving radially outward from the central axis L of the blast furnace 11. The numerical values ​​written along the dividing lines are dimensionless radial positions of the blast furnace 11.

[0054] The two circles shown by the dashed lines in Figure 5 represent the upper and lower limits UL1 and LL1 of the preferred target range (hereinafter also referred to as the first target range), which are 0.02 and 0.25. The two circles shown by the dashed lines in Figure 5 represent the upper and lower limits UL2 and LL2 of the more preferred appropriate range (hereinafter also referred to as the second target range), which are 0.04 and 0.2. The open-circle plots (○) and black-circle plots (●) located on each dividing line indicate the inner edge position of the ore layer 21, respectively. The open-circle plots represent the data before adjustment, while the black-circle plots (●) represent the data after adjustment.

[0055] The outlined plots (○) represent the inner edge positions of the ore layer 21, calculated from the ore deposit shape (shape of the ore layer 21) when the test apparatus is used without any adjustments and with the test apparatus at its initial settings. In this state, zero orientations fall within the second target range of 0.04 to 0.2, and only 2 / 36 orientations (0.5%) fall within the first target range of 0.02 to 0.25.

[0056] Therefore, in order to position the inner edge of the ore layer 21 closer to the furnace wall 11a, we investigated methods for adjusting the ore dump. The position of the inner edge of the ore layer 21 is thought to be largely influenced by the ore charged into the notch closest to the furnace center of the ore dump. In order to adjust the position of that ore, we thought it was necessary to adjust at least the notch closest to the furnace center. Therefore, various methods were considered to adjust the notch closest to the furnace center of the ore dump, and it was decided to shift all the notches by one notch towards the furnace wall 11a and change the notch closest to the furnace center to an outward orientation, thereby allowing the ore to be charged closer to the furnace wall 11a.

[0057] The black circles (●) in Figure 5 represent the inner edge positions of the ore layer 21 after adjusting the ore charging method. As a result of adjusting the ore charging method, it was confirmed that all directions fell within the first target range of 0.02 to 0.25, and 32 out of 36 directions (90%) fell more within the second target range of 0.04 to 0.2. Furthermore, it was confirmed that if the inflow position E of the ore layer 21 is outside the target range, it is effective to change at least the notch closest to the center of the furnace.

[0058] (Example 2) In Example 2, we verified whether operations would be stable if the inflow position E of the ore layer 21 fell within the target range. In Example 2, based on the results obtained in Example 1, we conducted operations in an actual blast furnace with a modified ore dump to investigate whether the operation could be stabilized.

[0059] The target blast furnace 11 is 5000m 3 This is a Class blast furnace 11. This blast furnace 11 was operated under the same charging conditions as in Example 1 (the state in which the result of the white plot (○) was obtained). At this time, the inflow position E of the ore layer 21, calculated from the measurement results of a profile meter (shape acquisition unit 14) installed in a specific furnace diameter direction, was 0.01. This position was below the lower limit of the second target range.

[0060] Therefore, the operation was carried out under the same charging conditions as after adjusting the ore charging method in Example 1 (the state in which the result of the black circle plot (●) was obtained). As a result, the inner edge position of the ore layer 21 improved to 0.15, bringing it within the second target range. Furthermore, it was confirmed that the blowing pressure σ decreased by 33% compared to before the change in conditions, resulting in more uniform gas flow within the furnace and enabling stable operation.

[0061] It should be noted that the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. Within the scope without departing from the spirit of the invention, the components in the embodiments described above can be replaced with well-known components, and the above-described modifications can be combined as appropriate. [Explanation of symbols]

[0062] 11 Blast Furnace 11a Furnace wall 12 Charging device 13 Control device 14 Shape acquisition section 21 Ore layer 22 Coke layer L center axis E Inflow point

Claims

1. The process involves charging ore into the blast furnace to form an ore layer, The process includes a coke charging step in which coke is charged into the blast furnace to form a coke layer, A method for operating a blast furnace, comprising alternately forming the ore layer and the coke layer, In the ore charging process, the radial position of the blast furnace with respect to the ore being charged onto the coke layer is adjusted so that the central part of the coke layer located at the center of the blast furnace is exposed above the ore layer. A method for operating a blast furnace, wherein in the ore charging process, the radial position of the blast furnace with respect to the ore is adjusted so that the inflow position of the ore layer falls within a target range in which the blast furnace can be operated stably, as confirmed by verification tests conducted in advance.

2. The method for operating a blast furnace according to claim 1, wherein in the ore charging process, the radial position of the ore in the blast furnace is adjusted based on the cross-sectional shape of the ore layer along the central axis direction of the blast furnace, which was formed by the ore charging process carried out prior to the ore charging process in question.

3. The method for operating a blast furnace according to claim 2, wherein in the ore charging step, the shape of the ore layer is obtained as the shape of the ore layer over the entire circumference of the blast furnace, and the radial position of the ore in the blast furnace is adjusted over the entire circumference of the blast furnace.

4. When the radial position of the blast furnace on the coke layer is represented by a dimensionless value where the distance from the central axis of the blast furnace to the furnace wall is set to 1, The method for operating a blast furnace according to any one of claims 1 to 3, wherein the target range is in the range of 0.02 or more and 0.25 or less.

5. In the aforementioned ore charging process, A bellless charging device charges the ore into the blast furnace. A method for operating a blast furnace according to any one of claims 1 to 3, wherein the charging device adjusts the radial position of the ore in the blast furnace with respect to the ore by adjusting at least one of the notch and rotation number when the ore is charged to the innermost radial position of the blast furnace in each dump of the ore.

6. A control device for controlling a charging device that alternately stacks ore layers and coke layers inside a blast furnace, By controlling the aforementioned loading device, By adjusting the radial position of the blast furnace with respect to the ore charged onto the coke layer, the central part of the coke layer located at the center of the blast furnace is exposed above the ore layer. A control device that adjusts the radial position of the blast furnace with respect to the ore so that the inflow position of the ore layer falls within a target range in which the blast furnace has been confirmed to operate stably through verification tests conducted in advance.

7. The blast furnace is provided with a shape acquisition unit that acquires the cross-sectional shape of the ore layer along the central axis direction of the blast furnace within the blast furnace, The control device according to claim 6, wherein the control device controls the loading device based on the acquisition result of the shape acquisition unit.

8. A program that causes a computer to function as the control device described in claim 6 or 7.

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