JP7393636B2 - How to operate a blast furnace - Google Patents

Description

The present invention relates to a method of operating a blast furnace.

Inside the blast furnace, ore layers and coke layers are alternately stacked, and the stacked shape of the blast furnace charge has a very large effect on the operation of the blast furnace. The stacked shape of blast furnace charge is controlled by measuring the layer thickness ratio distribution in the radial direction of the furnace. Here, the layer thickness ratio is the ratio of the thickness of the ore layer in the furnace height direction to the total layer thickness of the ore layer and the coke layer, and is hereinafter also expressed as Lo/(Lo+Lc).

Conventionally, in actual furnaces, only the layer thickness ratio distribution in the predetermined furnace radial direction was detected using a two-dimensional profile meter, so while the layer thickness ratio distribution in the predetermined furnace radial direction satisfied the target deposition shape, In some cases, the layer thickness ratio distribution in the other radial direction of the furnace did not satisfy the target deposition shape.

Therefore, in recent years, a three-dimensional profile meter, that is, a profile meter that can measure the layer thickness ratio distribution in the furnace radial direction at multiple locations in the furnace circumferential direction has been proposed (for example, Patent Document 1). According to the 3D profile meter, it is possible to measure the layer thickness ratio distribution in the radial direction of the furnace at multiple positions in the circumferential direction of the furnace. , has not been sufficiently investigated.

Patent No. 5391458

Specifically, the average layer thickness ratio distribution in the circumferential direction is calculated using multiple calculated layer thickness ratio distributions, and the method is similar to that of a single layer thickness ratio distribution calculated by a two-dimensional profile meter. Sufficient consideration had not been given as to whether to consider changing the charging method of blast furnace raw materials by using a different method or by using some other method. An object of the present invention is to provide a blast furnace operating method for appropriately reflecting and utilizing the layer thickness ratio distribution calculated at a plurality of positions in the furnace circumferential direction when considering a charging method.

In order to solve the above problems, the method of operating a blast furnace according to the present invention provides a layer showing a distribution in the furnace radial direction of a layer thickness ratio, which is the ratio of the thickness of the ore layer to the total layer thickness of the ore layer and the coke layer. A first step of measuring the thickness ratio distribution at each predetermined angle in the furnace circumferential direction using a three-dimensional profile meter, and a second step of calculating a predetermined parameter for each of the layer thickness ratio distributions calculated in the first step. and a third step of determining whether or not a predetermined percentage or more of the plurality of predetermined parameters calculated in the second step falls within a predetermined target range; The present invention is characterized by comprising a fourth step of changing the charging method of the blast furnace raw material when the ratio is less than the predetermined ratio.

According to the present invention, predetermined parameters are calculated for each of the layer thickness ratio distributions in the furnace radial direction calculated in plurality in the furnace circumferential direction, and a predetermined target range is set among the plurality of parameters calculated in the furnace circumferential direction. Using the proportion of items that can be accommodated, it is possible to consider whether or not the charging method needs to be changed. Thereby, it is possible to appropriately manage the tendency of the piled shape of the blast furnace charge throughout the furnace. For example, the layer thickness ratio distribution in a certain circumferential direction may be significantly different from that in other circumferential directions due to problems with the three-dimensional profile meter, small-scale blow-throughs, abnormalities in the charging equipment, etc. Even if shown, it is possible to consider whether or not to change the charging method without being influenced by the measurement results of the layer thickness ratio distribution in the circumferential direction. At this time, if the average layer thickness ratio distribution of the entire furnace was calculated and managed from the layer thickness ratio distributions calculated multiple times, the tendency of the pile shape of the blast furnace charge over the entire furnace could be appropriately determined. Difficult to manage.

It is a schematic diagram of the furnace upper part of a bellless type blast furnace. It is a distribution map which shows an example of favorable layer thickness ratio distribution. FIG. 2 is a distribution diagram showing an example of an unfavorable layer thickness ratio distribution. It is a graph which shows the relationship between coke ratio CR and a 1st parameter. It is a graph which shows the relationship between coke ratio CR and a 2nd parameter. It is a flow chart showing an embodiment using a first parameter. It is a flowchart which shows an embodiment using a 2nd parameter. It is a graph showing the change in the first parameter before and after adjusting the ore charging position (measured with a 1/3 bellless test device). It is a graph showing the change in the second parameter before and after adjusting the ore charging position (measured by a 1/3 bellless test device).

(First embodiment)
Hereinafter, a method of operating a blast furnace according to the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic diagram of the upper part of a bellless blast furnace, which is an example of a blast furnace targeted in this embodiment. The belt conveyor 3 carries the blast furnace raw materials (coke and ore) toward the top of the furnace. The blast furnace raw material that has reached the terminal end of the belt conveyor 3 is alternately charged into the fixed hoppers 4a and 4b at regular intervals via a switching chute (not shown). For example, coke can be charged into the fixed hopper 4a and ore can be charged into the fixed hopper 4b.

The coke and ore charged into the fixed hoppers 4a and 4b are alternately charged into the storage hopper 7 at regular intervals according to the opening degree of the flow control gate (not shown) located at the lower end of the fixed hoppers 4a and 4b. be done. The blast furnace raw material charged into the storage hopper 7 is discharged from a flow control gate 8 at the lower end of the storage hopper 7 toward the rotating chute 5 . By rotating the rotating chute 5 around a rotation axis RA extending in the direction of the furnace height, ore and coke can be alternately charged into the furnace. Thereby, a blast furnace packed bed in which ore layers and coke layers are alternately stacked can be formed in the furnace. Note that ore refers to a raw material containing an iron source, and includes lump ore, carbon-containing agglomerate, etc. in addition to sintered ore. Furthermore, the ore layer may contain something other than ore (for example, small coke), and the coke layer may also contain something other than coke. In addition, blast furnace raw materials refer to all raw materials charged from the top of a blast furnace, including ore and coke.

The tilting angle θ of the rotating chute 5 is variable, and in this embodiment, the blast furnace raw material is charged by a charging method called forward tilting, in which the rotating chute 5 is rotated while gradually decreasing the tilting angle θ. Ru. In this case, the blast furnace raw material is charged from the furnace wall side toward the furnace center side. In FIG. 1, the surface profile of the ore layer and the coke layer decreases from the furnace wall side toward the furnace center, forming a so-called mortar-shaped pile shape.

A favorable layer thickness ratio distribution will be explained with reference to FIG. 2. In FIG. 2, the vertical axis indicates the ratio of the thickness of the ore layer to the total thickness of the ore layer and the coke layer, that is, the layer thickness ratio. If the thickness of the ore layer is Lo and the thickness of the coke layer is Lc, The layer thickness ratio is expressed as Lo/(Lo+Lc). In FIG. 2, the horizontal axis indicates the distance from the furnace center, expressed as a dimensionless distance (hereinafter referred to as the dimensionless radius of the furnace mouth) with the furnace center position as 0 and the furnace wall position as 1.

The layer thickness ratio distribution is calculated by a known method from the surface profiles of the ore layer and the coke layer, which are measured by various proposed known profile meters. In Figure 2 (and Figure 3, which will be described later), the layer thickness ratio distribution is calculated using the surface profile immediately after the charging of each layer is completed, and the influence of collapse due to the blast furnace raw material charged next to that layer is taken into account. However, the method for calculating the layer thickness ratio distribution is not particularly limited.

In the operation of a blast furnace, there is an ideal layer thickness ratio distribution in the furnace radial direction, and a target layer thickness ratio distribution (hereinafter also referred to as target layer thickness ratio distribution) is determined for each blast furnace depending on the raw material properties and other operational parameters. ) has been established. FIG. 2 is an example of the target layer thickness ratio distribution.

In the lower part of the blast furnace, the furnace gas preferentially passes through the coke layer and rises to the upper part of the furnace. Therefore, the furnace gas tends to flow to areas where the layer thickness ratio is small.

By the way, the furnace wall of a blast furnace is cooled to protect the equipment. In order to quickly reduce and melt the ore existing in the furnace wall, it is necessary to flow more gas in the furnace than in the middle part of the furnace, and the layer thickness ratio of the furnace wall part is smaller than that of the middle part of the furnace. It is also preferable to make it smaller. On the other hand, if the layer thickness ratio of the furnace wall is made too small, excessive gas will flow to the furnace wall, reducing the reduction efficiency and thus increasing the reducing agent ratio, which is not preferable. Therefore, it is considered that there is an appropriate relationship between the layer thickness ratio between the furnace wall portion and the furnace middle portion.

Whether or not the layer thickness ratio distribution in the furnace radial direction is an ideal distribution can be determined based on a predetermined parameter calculated from the layer thickness ratio distribution. This predetermined parameter can be rephrased as a predetermined evaluation parameter for evaluating the deposition shape. For example, the difference (hereinafter also referred to as the first parameter) between the maximum value of the layer thickness ratio in the middle part of the furnace (point P1 in Figure 2) and the minimum value of the layer thickness ratio in the furnace wall part (point P2 in Figure 2) is , can be used as a predetermined parameter. When this first parameter is 0.40 or less, it is possible to form the above-mentioned preferable flow of gas in the furnace, and it can be considered that a favorable layer thickness ratio distribution is obtained. Hereinafter, the maximum value of the layer thickness ratio in the furnace middle part will be referred to as the furnace middle part maximum layer thickness ratio, and the minimum value of the layer thickness ratio in the furnace wall part will be referred to as the furnace wall part minimum layer thickness ratio. The reason why the target range of the first parameter (hereinafter also referred to as the first target range) is set to 0.40 or less will be described later. Note that the first target range being 0.40 or less means that the upper limit of the first target range is 0.40.

Further, for example, the ratio of the average value of the layer thickness ratio in the furnace wall portion to the average value of the layer thickness ratio in the furnace middle portion (hereinafter also referred to as the second parameter) can be used as the predetermined parameter. When this second parameter is 0.77 or more, it is possible to form the above-mentioned preferable flow of gas in the furnace, and it can be considered that a favorable layer thickness ratio distribution is obtained. Hereinafter, the average value of the layer thickness ratio in the furnace middle part will be referred to as the furnace middle part average layer thickness ratio, and the average value of the layer thickness ratio in the furnace wall part will be referred to as the furnace wall part average layer thickness ratio. Note that the furnace middle portion average layer thickness ratio and the furnace wall portion average layer thickness ratio can each be an arithmetic mean value. The reason why the target range of the second parameter (hereinafter also referred to as second target range) is set to 0.77 or more will be described later. Note that the second target range being 0.77 or more means that the lower limit of the second target range is 0.77.

FIG. 3 shows an example of an unfavorable layer thickness ratio distribution. As shown in FIG. 3, when the amount of ore charged into the furnace wall is small, the minimum layer thickness ratio of the furnace wall decreases, and the average layer thickness ratio of the furnace wall decreases. Therefore, the first parameter may exceed the first target range (0.40 or less), or the second parameter may fall below the second target range (0.77 or more).

Incidentally, the boundary between the furnace wall portion and the furnace middle portion can be appropriately selected within the range of the dimensionless radius of the furnace mouth: 0.6 to 0.9. The boundary between the furnace center and the furnace middle can be appropriately selected within the range of the dimensionless radius of the furnace mouth: 0.1 to 0.35. The boundary between the furnace wall portion and the furnace middle portion, and the boundary between the furnace center portion and the furnace middle portion can be determined according to the target layer thickness ratio distribution. In this embodiment, the range of 0.3 or more and less than 0.7 in the dimensionless radius of the furnace mouth is defined as the furnace middle part, and the range of 0.7 or more and 1.0 or less in the furnace mouth dimensionless radius is defined as the furnace wall part. Define.

FIG. 4 shows the relationship between the coke ratio (CR) and the first parameter. The plot in FIG. 4 shows the coke ratio (CR) and the first parameter, which were determined from two weeks of operation results of a class ³ blast furnace with a furnace capacity of 4000 m. In FIG. 4, the first parameter is a value calculated from the measurement results of a profile meter installed in a certain circumferential direction of the furnace. According to FIG. 4, it can be seen that the coke ratio tends to increase as the first parameter increases, and when the first parameter exceeds 0.40, the coke ratio exceeds 300 kg/t. Therefore, by controlling the layer thickness ratio distribution so that the first parameter is 0.40 or less, that is, so that the first parameter is within the first target range, the operation can be stabilized and the coke ratio can be maintained at a low level. It is thought that it is possible to do so.

FIG. 5 shows the relationship between the coke ratio (CR) and the second parameter. The plots in FIG. 5 are the coke ratio (CR) and the second parameter, which were determined from two weeks of operation results of a class ³ blast furnace with a furnace capacity of 4000 m. In FIG. 5, the second parameter is a value calculated from the measurement results of a profile meter installed in a certain circumferential direction of the furnace. According to FIG. 5, it can be seen that the coke ratio tends to increase as the second parameter becomes smaller, and when the second parameter becomes less than 0.77, the coke ratio exceeds 300 kg/t. Therefore, by controlling the layer thickness ratio distribution so that the second parameter is 0.77 or more, that is, so that the second parameter is within the second target range, the operation can be stabilized and the coke ratio can be maintained at a low level. It is thought that it is possible to do so.

As described above, the present inventors determined the appropriate ranges of the first and second parameters for the stable operation period when the coke ratio was low and stable based on the operating results of a certain blast furnace, and determined the first target range and the second parameter. Two target ranges were set.
We also thought that by using the predetermined parameters and predetermined target ranges of the measurement results obtained by the three-dimensional profile meter, the measurement results could be appropriately reflected and used in the examination of the charging method.

Specifically, predetermined parameters are calculated for each of the layer thickness ratio distributions calculated at multiple positions in the circumferential direction, and the number of directions that fall within a predetermined target range among these multiple predetermined parameters is equal to or greater than a predetermined ratio. As in, operating a blast furnace.
As a result, the measurement results obtained by the three-dimensional profile meter can be appropriately reflected and used in the examination of the charging method, realizing the ideal layer thickness ratio distribution throughout the furnace, and achieving the ideal gas distribution in the furnace. It becomes possible to realize the flow. By managing and controlling the layer thickness ratio distribution throughout the furnace, it is possible to increase the efficiency of the entire furnace, achieving stable operation, and enabling operation with even lower coke ratios and lower reducing agent ratios.

Here, the layer thickness ratio distribution is measured at a plurality of positions in the circumferential direction of the furnace, preferably at least eight or more positions in the circumferential direction of the furnace. Further, preferably, the measurement is performed at predetermined angular intervals in the circumferential direction of the furnace. The predetermined angular interval for calculating the layer thickness ratio distribution is preferably 45° or less, and can be set to 10°, for example. The smaller the angular interval, the more accurately the layer thickness ratio distribution in the furnace radial direction can be grasped. However, if the angular interval is made too small, the amount of data becomes enormous and processing becomes complicated.

The "predetermined percentage" which is a threshold value of the percentage of the predetermined parameter falling within the predetermined target range is preferably 50%, more preferably 80%. When the predetermined ratio is less than 50%, the number of orientations in which an ideal layer thickness ratio distribution is not formed increases, which may lead to operational fluctuations.

When the percentage of the predetermined parameter falling within the predetermined target range is less than the predetermined percentage, it is necessary to change the charging method of the blast furnace raw material. When changing the charging method of blast furnace raw materials, for example, the ore charging method may be changed to adjust the ore charging position, or the coke charging method may be changed to adjust the coke charging position. Either method can adjust the layer thickness ratio distribution. Note that the charging positions of both ore and coke may be adjusted.

When the blast furnace to which the present invention is applied is equipped with a bellless charging device as shown in Fig. 1, the blast furnace raw material can be The charging method can be changed. For example, when adjusting the ore charging position, the number of turns of a certain notch in the ore dump can be changed. More specifically, as shown in Fig. 3, when the amount of ore charged into the furnace wall is small and the ratio of the predetermined parameters falling within the predetermined target range is less than the predetermined ratio, the ore charging position is changed. Change to outside swing. For example, when the notch pattern of an ore dump is "2 turns from 2 notches to 8 notches", by changing the notch pattern to "2 turns from 1 notch to 7 notches", charging into the furnace wall is possible. It is possible to increase the amount of ore to be used and improve the first parameter and the second parameter. Further, the coke charging position may be changed to an internal direction.

In this invention, blast furnace raw materials are alternately cut out from the bottom bell (large bell) hopper, and the strokes of movable armors provided in large numbers in the circumferential direction of the wall around the furnace mouth are adjusted to collide and reflect against the armor plate. By doing so, it can also be applied to a bell-type blast furnace in which the furnace is filled with blast furnace raw material.
When the blast furnace targeted by the present invention is equipped with a bell-type charging device, by changing at least one of the opening degree of the large bell, the opening speed of the large bell, and the stroke of the movable armor, and/or coke) charging method can be changed. For example, by reducing the stroke of the movable armor, the ore charging position can be changed to the outside.

In addition, regardless of whether it is a bell-less blast furnace or a bell-type blast furnace, it is possible to change the charging method of blast furnace raw materials by adjusting the control line that controls the height of the blast furnace raw materials accumulated in the furnace. can.
Blast furnace raw materials charged into the blast furnace form a packed bed, and when the control position of this packed bed (for example, a position several tens of cm from the furnace wall) is unloaded to a predetermined control line, new blast furnace raw materials are added into the furnace. is charged into the Adjusting this control line, specifically, lowering the control line before charging ore so that the charging position of the ore layer is outside, and/or the control line before charging coke The first parameter and the second parameter can be improved by increasing the coke charging position to the inside.

The control line can be set, for example, several tens of cm to several meters below the stock line (SL). In the case of a bellless blast furnace, the strain line (SL) can be defined, for example, as a position several tens of centimeters below the lower end of a rotating chute in which the tilting angle θ is set to the minimum value (θ≈0). Alternatively, the stock line (SL) may be defined as several tens of cm to several meters above the upper end of the ore receiving hardware. Further, in the case of a bell-type blast furnace, the stock line (SL) can be defined as, for example, several tens of centimeters to several meters below the lower end of the movable armor that has been retreated to the retracted position.

In either method, the charging method of the blast furnace raw material can be changed as appropriate so as to obtain an ideal layer thickness ratio distribution (target layer thickness ratio distribution) determined for the target blast furnace. That is, if the proportion of directions in which the first parameter falls within the first target range is less than a predetermined proportion, or if the proportion of directions in which the second parameter falls within the second target range is less than a predetermined proportion, the ore and /Or the charging method is changed to one that allows the coke charging position to be returned to the appropriate position and an appropriate amount of ore to be placed on the furnace wall.

Note that the predetermined parameter calculated from the layer thickness ratio distribution may be any parameter for evaluating the deposition shape, and is not limited to the first parameter and the second parameter.

For example, when the target layer thickness ratio distribution is set in advance, a parameter indicating the degree of deviation or coincidence with the target layer thickness ratio distribution may be used as the predetermined parameter.
Specifically, the value at each non-dimensional radial position at the furnace mouth in the target layer thickness ratio distribution (target layer thickness ratio) and the value at the corresponding non-dimensional radial position at the furnace mouth in the measured layer thickness ratio distribution ( The absolute value of the difference (hereinafter referred to as the third parameter) when the absolute value of the difference with respect to the layer thickness ratio becomes the maximum may be used as the predetermined parameter. The target range of the third parameter (hereinafter referred to as third target range) can be, for example, 0.02 or less. If the measured layer thickness ratio is 0.02 larger than the target layer thickness ratio in the entire furnace (that is, in all the furnace radial directions and in the furnace circumferential direction), and the third parameter is 0.02, then the ore This is because the charging amount per charge will increase by about 20%, which will have a non-negligible effect on blast furnace operation.

For example, the dimensionless radial position that takes the maximum layer thickness ratio in the middle part of the furnace (point P1 in Figure 2) in the target layer thickness ratio distribution, and the dimensionless radial position that takes the maximum layer thickness ratio in the middle part of the furnace in the measured layer thickness ratio distribution. The distance to the radial position (fourth parameter) may be used as the predetermined parameter. The target range of the fourth parameter (hereinafter referred to as the fourth target range) can be, for example, 0.04 or less.
For example, the dimensionless radial position that takes the minimum layer thickness ratio of the furnace wall in the target layer thickness ratio distribution (point P2 in Figure 2) and the dimensionless radial position that takes the minimum layer thickness ratio of the furnace wall in the measured layer thickness ratio distribution. The distance to the radial position (fifth parameter) may be used as the predetermined parameter. The target range of the fifth parameter (hereinafter referred to as the fifth target range) can be, for example, 0.04 or less. This is because when the fourth parameter or the fifth parameter is 0.04, the number of notches in the rotating chute changes by about one notch, which has a non-negligible effect on blast furnace operation.

A method of changing the charging method to improve the first parameter will be described with reference to the flowchart of FIG. 6.

(Regarding step S101)
Using the measurement results obtained by the three-dimensional profile meter, the layer thickness ratio distribution in the furnace radial direction is calculated at predetermined angular intervals in the furnace circumferential direction. The three-dimensional profile meter uses a measuring device that can measure the surface profile of the blast furnace charge in the radial direction of the blast furnace, and uses the measurement results to measure the surface profile of the blast furnace charge in the radial direction of the blast furnace. A thickness ratio distribution is calculated. As mentioned above, the predetermined angular interval for calculating the layer thickness ratio distribution is preferably 45° or less, and can be set to 10°, for example. Note that the above information measured by the three-dimensional profile meter is referred to as three-dimensional deposition information.

The three-dimensional profile meter may be of a microwave type or a laser type. As a microwave type three-dimensional profile meter, for example, an antenna connected to a microwave transmitting/receiving means and a reflector plate with a variable reflection angle are housed in a container, and the container is airtightly inserted into an opening provided at an appropriate location in the upper part of a blast furnace. Installed, the microwave beam emitted from the antenna is reflected by a reflector to scan the surface of the charge in a planar manner, and the microwave reflected from the surface is detected by the microwave transmitting/receiving means to correspond to the scanning position. It is possible to use a charge profile meter that obtains and maps distance data (for example, see Patent Document 1). In this specification, a measuring device that measures the surface profile only at a specific furnace radial position is referred to as a two-dimensional profile meter to distinguish it from a three-dimensional profile meter.

A specific method for calculating the layer thickness ratio distribution in the furnace radial direction is as follows. That is, after charging coke, three-dimensional deposition information of the coke layer is measured using a three-dimensional profile meter. Here, the obtained three-dimensional deposition information is extracted for each of the predetermined angles described above to obtain deposition information of the coke layer in the furnace radial direction. That is, the deposition shape (two-dimensional deposition information) of the coke layer in the furnace radial direction is acquired at each of the predetermined angles.
Thereafter, three-dimensional deposition information of the ore layer stacked on the coke layer is measured using a three-dimensional profile meter. Here, the obtained three-dimensional deposition information is extracted for each of the predetermined angles described above to obtain deposition information of the ore layer in the furnace radial direction. That is, the deposition shape (two-dimensional deposition information) of the ore layer in the furnace radial direction is acquired for each predetermined angle. Finally, the layer thickness ratio distribution in the furnace radial direction is determined for each of the above-mentioned predetermined angles.

(Regarding step S102)
A first parameter for each predetermined angle is calculated based on the layer thickness ratio distribution for each predetermined angle obtained in step S101. As mentioned above, the first parameter is the difference between the maximum layer thickness ratio at the middle of the furnace and the minimum layer thickness ratio at the furnace wall.

(Regarding step S103)
It is determined whether 50% or more of the first parameters obtained in step S102 are 0.40 or less (within the first target range), and if more than 50% are outside the first target range (step S103 No) , the process proceeds to step S104. That is, when the proportion of the first parameter falling within the first target range is less than 50% (No in step S103), the process proceeds to step S104. If 50% or more is within the first target range (step S103 Yes), the process advances to step S105.

(Regarding step S104)
In step S104, the ore charging position is moved toward the furnace wall. The ore charging position can be adjusted by the method described above. The method of determining the ore charging position after the change is not particularly limited, but for example, calculate the arithmetic mean value of the first parameter in each direction, and calculate the arithmetic mean value and 0.40, which is the upper limit of the first target range. can be determined by comparing. In other words, when the difference between the arithmetic mean value of the first parameter and 0.40 is large, the ore charging position is moved largely toward the furnace wall, and the difference between the arithmetic mean value of the first parameter and 0.40 is not large. In such cases, it is best to make fine adjustments by shifting the ore charging position little by little toward the furnace wall.

By lowering the control line before charging the ore, the ore charging position can be changed to the furnace wall side, but whether or not the control line has lowered can be determined by a known sounding device. can. Sounding devices include mechanical sounding devices that measure the height by hanging a weight connected to a wire into the furnace and making it contact the top of the packed bed of the blast furnace, and micro-sounding devices that are attached to the top of the blast furnace. A wave distance meter can be used. By performing the process in step S104, the ore charging position can be changed to a position pointing to the first parameter: 0.40. In other words, the ore charging position can be appropriately shifted to the furnace wall side, and the layer thickness ratio distribution can be optimized. In other words, the layer thickness ratio distribution in the furnace radial direction is improved over the entire furnace circumferential direction so that 50% or more of the first parameter falls within the first target range.

(Regarding step S105)
Since 50% or more of the first parameters are within the first target range, no process is performed to adjust the ore charging position.

(Second embodiment)
A method of changing the charging method to improve the second parameter will be described with reference to the flowchart of FIG. 7. However, detailed description of steps that are common to those in FIG. 6 will be omitted.

In step S102A, a second parameter for each predetermined angle is calculated based on the layer thickness ratio distribution for each predetermined angle obtained in step S101. As described above, the second parameter is the ratio of the average layer thickness ratio of the furnace wall portion to the average layer thickness ratio of the furnace middle portion.
In step S103A, it is determined whether 50% or more of the second parameters obtained in step S102A are 0.77 or more (within the second target range), and if more than 50% are outside the second target range ( Step S103A No), the process proceeds to step S104. That is, when the proportion of the second parameter falling within the second target range is less than 50% (No in step S103A), the process proceeds to step S104. If 50% or more is within the second target range (step S103A Yes), the process advances to step S105.
The process of adjusting the ore charging position in step S104 is the same as in the example of FIG. 6 . At this time, for example, the arithmetic mean value of the second parameter for each direction is calculated, and this arithmetic mean value is compared with 0.77, which is the lower limit value of the second target range, to determine the ore charging position after the change. can be determined.

The present invention will be described in detail with reference to examples. Using a 1/3 bellless test device, blast furnace raw materials were charged under the same conditions as in an actual blast furnace, and the relationship between the first parameter, the second parameter, and the ore charging method was investigated. The 1/3 bellless test device is a model experimental device (with a radius of about 1800 mm) that is 1/3 the size of an actual furnace and imitates a bellless furnace top charging device. The average particle size was about 1/3 of that of an actual furnace, and the charging amount was about 1/27 of that of an actual furnace. The amount of coke charged per charge was approximately 1.3 t, and the amount of ore charged per one charge was approximately 7.3 t.

The three-dimensional deposition shape of the ore layer and the coke layer was measured with a three-dimensional profile meter, and the measured three-dimensional deposition shape was cut out at intervals of 10° in the furnace circumferential direction to obtain the deposition shape in each direction. After acquiring the deposition shape in each direction, the layer thickness ratio distribution in each direction was determined, and the first parameter and the second parameter were calculated for each direction.

The graph of FIG. 8 shows the value of the first parameter in each direction. The white plot (○) in FIG. 8 is the value of the first parameter calculated from the layer thickness ratio distribution before adjusting the ore charging method, and the broken line in FIG. shows the upper limit value (0.40). Before adjusting the ore charging method, the proportion of the first parameter falling within the first target range was 0%.

Therefore, in order to increase the amount of ore charged to the furnace wall side, all the notches in the ore dump were shifted by one notch toward the furnace wall side, and the ore dump was changed to an outward swing. The black circle plot (●) in FIG. 8 is the value of the first parameter calculated from the layer thickness ratio distribution after adjusting the ore charging method. As a result of adjusting the ore charging method, the proportion of the first parameter falling within the first target range was improved to 80%.

The graph of FIG. 9 shows the values of the second parameter in each direction.
The white plot (○) in FIG. 9 is the value of the second parameter calculated from the layer thickness ratio distribution before adjusting the ore charging method, and the dashed line in FIG. The lower limit value (0.77) is shown. Before adjusting the ore charging method, the proportion of the second parameter falling within the second target range was 0%.

The black circle plot (●) in FIG. 9 is the value of the second parameter calculated from the layer thickness ratio distribution after adjusting the ore charging method. As a result of adjusting the ore charging method, the proportion of the second parameter falling within the second target range was improved to 80%.

3 Belt conveyor 4a, 4b Fixed hopper 5 Rotating chute 7 Storage hopper 8 Flow control gate

Claims (11)

The layer thickness ratio distribution, which indicates the distribution in the furnace radial direction of the layer thickness ratio, which is the ratio of the thickness of the ore layer to the total layer thickness of the ore layer and the coke layer, was measured at multiple positions in the furnace circumferential direction using a three-dimensional profile meter. The first step of measuring;
a second step of calculating a predetermined parameter based on the layer thickness ratio distribution of the furnace middle portion and the layer thickness ratio distribution of the furnace wall portion in each of the layer thickness ratio distributions calculated in the first step;
a third step of determining whether a predetermined percentage or more of the plurality of predetermined parameters calculated in the second step falls within a predetermined target range;
a fourth step of changing the charging method of the blast furnace raw material when the proportion of the predetermined parameter falling within the predetermined target range is less than the predetermined proportion ;
The range of the furnace middle part is 0.3 or more and less than 0.7 in the dimensionless radius of the furnace mouth, and the range of the furnace wall part is 0.7 or more and 1.0 or less in the dimensionless radius of the furnace mouth.
A method of operating a blast furnace characterized by the following. 2. The blast furnace operating method according to claim 1, wherein the first step is a step of measuring the layer thickness ratio distribution at every predetermined angle in the furnace circumferential direction. The blast furnace according to claim 1 or 2, wherein the predetermined parameter is a difference between the maximum value of the layer thickness ratio in the furnace middle part and the minimum value of the layer thickness ratio in the furnace wall part. operating methods. The blast furnace operating method according to claim 3, wherein the predetermined target range is 0.40 or less. The blast furnace according to claim 1 or 2, wherein the predetermined parameter is a ratio of the average value of the layer thickness ratio in the furnace wall portion to the average value of the layer thickness ratio in the furnace intermediate portion. Operating method. The blast furnace operating method according to claim 5, wherein the predetermined target range is 0.77 or more. The blast furnace is equipped with a bellless charging device, and the fourth step is to adjust the charging position of the ore and/or coke by changing at least one of the tilting angle, the number of turns, and the turning speed of the turning chute. The method of operating a blast furnace according to any one of claims 1 to 6 , characterized in that the method is a step. The blast furnace is equipped with a bell-type charging device, and the fourth step includes charging ore and/or coke by changing at least one of the opening degree of the large bell, the opening speed of the large bell, and the stroke of the movable armor. The method for operating a blast furnace according to any one of claims 1 to 6 , characterized in that the step is adjusting the insertion position. 10. The fourth step is a step of adjusting a control line for controlling the height of the blast furnace raw material deposited in the furnace to adjust the charging position of ore and/or coke. 6. The method of operating a blast furnace according to any one of 6 . The method of operating a blast furnace according to claim 1, wherein the predetermined ratio is 50 %. The method for operating a blast furnace according to any one of claims 1 to 9 , wherein the predetermined ratio is 80%.

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