JP7151228B2 - Blast furnace operation method - Google Patents

Description

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

In blast furnace operation, sintered ore as an iron source, reducing agent, and coke as a heat source are charged and deposited in layers in the furnace, and hot air is blown from the bottom of the furnace as a heat source to produce hot metal.
Since the gas flow changes depending on the shape of the deposit formed by sintered ore and coke, it is very important to manage and control the shape of the deposit for stable blast furnace operation.

Blast furnaces need to stably produce the planned amount of tapped iron. We are trying to produce.
In particular, in recent years, operations with high iron output and low coke ratio have been promoted, and the amount of gas in the blast furnace is increasing with the increase in the amount of oxygen introduced into the furnace. is required.

In Patent Document 1, in order to enable stable blast furnace operation at a low coke ratio, the deposition shape of the coke deposit layer is such that the ratio of coke terrace length / furnace throat radius is 0.3 or less, and the coke inclination angle is 10. A method of operating a blast furnace to ∼20° is described.

Patent Document 2 describes that as a raw material charging method for controlling the gas flow distribution of a bell-type blast furnace, the ratio of fine particles to fine particles is set to 1.0 to 2.5% in the middle region from the center region of the furnace. It is

Patent Document 3 discloses a charge distribution control method that enables stable blast furnace operation even under high PCI operation. It is described to minimize the difference from the in-furnace radial gas composition distribution measured at the top.

In Patent Document 4, in order to obtain a desired sediment surface profile, the acceleration of the falling charge is calculated for each minute section divided into a plurality of sections from the tip of the large bell to the blast furnace wall, and the position is calculated. It states that the falling trajectory is obtained from the position, the deposition surface profile in the furnace is estimated from the falling trajectory, the difference is obtained by comparing the estimated profile and the target profile, and the distribution of the burden is adjusted based on the difference. there is

JP 2008-208463 A JP-A-2006-70353 JP-A-2000-8105 JP-A-5-222416

However, the techniques described in Patent Documents 1 to 4 have room for improvement in the following points.
In the technique described in Patent Literature 1, the surface shape of the deposit is a curved line having local unevenness, so the deposition angle is obtained by linear approximation. Therefore, even if the deposition angle satisfies the range specified in Patent Document 1, the influence of the local irregularities on the gas flow could not be considered.
The techniques described in Patent Documents 2 and 4 are effective in the case of a bell-type blast furnace, but could not be applied to a bell-less blast furnace.
The technique described in Patent Document 3 is effective as a method for controlling the gas flow distribution of a blast furnace, but the only specific action to improve operation is to change the deposition angle, and similar to Patent Document 1, local The influence of the uneven shape on the gas flow could not be considered.

The present invention has been made in view of the above problems, and provides a blast furnace operating method that can be applied regardless of the blast furnace structure and that can optimally control the gas flow in consideration of the local surface shape of deposits. The purpose is to

The blast furnace operating method of the present invention is a blast furnace operating method in which iron ore and coke are alternately charged from the top of the furnace. A measurement process for obtaining a measurement graph showing the relationship between the rate and the rate, a target operation graph showing the relationship between the position in the furnace radial direction and the gas utilization rate in % units in the target blast furnace operation, and the measurement graph. is compared, and a specific step of identifying a furnace radial position where the difference in gas utilization rate is 20% or more as a problem position, and the charging amount of iron ore or coke at the problem position in the next charge is determined as the gas utilization rate. and a charging step of adjusting and charging so that the difference is less than 20%.
According to the present invention, the problem location affecting the gas flow is identified from the difference between the measured graph and the target operating graph.
Therefore, it can be applied regardless of the blast furnace structure.
In addition, from the difference between the measurement graph and the target operation graph, it is possible to easily identify the location of the furnace radial direction where there is local unevenness that affects the gas flow as the problem location. action is possible.

In the present invention, the target operation graph is such that when the radius of the furnace is R, the radial position in the furnace radial direction is r, and the center is 0, the gas utilization rate at r/R = 0 is 0%, and 0.4 ≤ The gas utilization rate at r/R ≤ 0.9 is constant in the range of 45% to 60%, and the gas utilization rate at 0 ≤ r/R ≤ 0.4 is from 0% to 45% to 60%. is preferably a graph that monotonically increases up to a certain range.
According to the present invention, since a simple graph combining a monotonically increasing function and a straight line is used as the target operation graph, it is possible to reduce man-hours and costs required to obtain the target operation graph.

In the present invention, the measuring step is a step of determining the gas utilization rate on one horizontal straight line connecting the center to the furnace wall at a height of 3000 mm or more and 5000 mm or less vertically downward from the upper surface of the charged material. is preferred.
According to the present invention, it is only necessary to obtain the gas utilization rate on one horizontal straight line connecting the center to the furnace wall, so the man-hours and cost required to obtain the target operation graph can be reduced.

In the present invention, the charging step includes a pile shape measurement step of measuring the pile shape in the radial direction of the charge, and referring to the measured pile shape, the iron ore or coke at the problem position in the next charge It is preferable that the charging amount is adjusted so that the difference in gas utilization rate is less than 20%.
According to the present invention, since the charging amount of iron ore or coke to be charged to a position where local unevenness affecting the gas flow is adjusted, it is possible to accurately control the gas flow due to the local uneven shape. .

In the present invention, in the charging step, if the gas utilization rate at the problem position is higher than the gas utilization rate of the target operation graph, the iron ore charging amount to the problem position in the next charge is relatively increased to the target It is a step of reducing 0.5 to 5% by mass per 1% difference from the operation graph, or relatively increasing the coke charging amount by 0.5 to 5% by mass per 1% difference from the target operation graph. is preferred.
According to the present invention, the charging amount of iron ore or coke charged to a position where local unevenness affecting the gas flow is adjusted in units of 1% difference from the ideal state, so that local The uneven gas flow can be controlled more accurately.

In the present invention, in the charging step, if the gas utilization rate at the problem position is lower than the gas utilization rate of the ideal operation graph, the iron ore charging amount to the problem position in the next charge is relatively increased to the target Increase by 0.5 to 5% by mass per 1% difference from the operation graph, or relatively reduce the coke charging amount by 0.5 to 5% by mass per 1% difference from the target operation graph. is preferred.
According to the present invention, the charging amount of iron ore or coke charged to a position where local unevenness affecting the gas flow is adjusted in units of 1% difference from the ideal state, so that local The uneven gas flow can be controlled more accurately.

BRIEF DESCRIPTION OF THE DRAWINGS The flowchart which shows the outline|summary of the blast-furnace operating method which concerns on embodiment of this invention. The example which shows the state which overlapped the measurement graph and the target operation graph in the said embodiment and Example 1. FIG. In Example 1, it is a diagram comparing the profile of the surface of the charge before and after the operation improvement action, and "before adjustment" in the figure is the profile before the operation improvement action, and "after adjustment" is the operation improvement. Post-action profile. In the figure, the profile is shown as the ratio of the ore layer thickness to the charge layer thickness .

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.
First, a blast furnace operating method according to an embodiment of the present invention will be described.

First, with reference to FIG. 1, the outline of the blast furnace operating method will be described.
First, a measurement graph showing the relationship between the position in the furnace radial direction and the gas utilization rate is obtained in the blast furnace and below the charge (S1 in FIG. 1, measurement step).

Next, the measurement graph is compared with the target operation graph showing the relationship between the position in the furnace radial direction and the gas utilization rate in the target blast furnace operation, and the furnace radial position where the difference in the gas utilization rate is 20% or more is specified as the problem position (S2 in FIG. 1, specifying step).

Next, the charging amount of iron ore or coke at the problem location in the next charge is adjusted and charged so that the difference in gas utilization rate is less than 20% (S3 in FIG. 1, charging step).
The above is the outline of the blast furnace operating method. In the following description, it is assumed that the measurement graph is obtained using the gas utilization rate.

Next, with reference to FIGS. 1 and 2, the details of the blast furnace operating method according to the embodiment of the present invention will be described.
<Target blast furnace>
The blast furnace targeted by the present embodiment is not limited in structure or volume as long as iron ore and coke are alternately charged from the top of the furnace. The raw material charging means may be bell-type or bell-less.
The raw material is also not particularly limited. Various iron sources such as sintered ore, pellets and reduced iron can be used as iron ore.

<S1: Measurement step>
In S1, a measurement graph showing the relationship between the position in the furnace radial direction and the gas utilization rate η is obtained.
The gas utilization rate η is obtained, for example, by the following formula (1).
η(%)=[% _CO2 ]/([%CO]+[% _CO2 ])×100 (1)
[% CO ₂ ] in equation (1) is the volume % of CO ₂ in the gas. [%CO] is the volume % of CO in the gas.

The gas composition can be measured using a plurality of sondes provided in the radial direction of the furnace.
The measurement position is a height of 3000 mm or more and 5000 mm or less vertically downward from the upper surface of the charge, and the gas utilization rate η is obtained on one horizontal straight line connecting the center to the furnace wall.
The composition distribution of the post-reduction gas can be measured and the gas utilization rate in the furnace can be obtained by setting the vertical downward direction from the upper surface of the charge to 3000 mm or more and 5000 mm or less.
By obtaining the gas utilization rate η on one horizontal straight line, it becomes unnecessary to perform measurement over the entire circumference of the blast furnace. However, the gas utilization rate η may be obtained on a plurality of horizontal straight lines.
An example of a measurement graph 100 is shown in FIG.

<S2: Specific step>
In S2, the measurement graph 100 is compared with the target operation graph showing the relationship between the position in the furnace radial direction and the gas utilization rate η in the target blast furnace operation, and furnaces with a difference in the gas utilization rate η of 20% or more are compared. Identify the radial location as the problem location.

The target operation graph is a graph showing the relationship between the position in the furnace radial direction and the gas utilization rate η when the target gas flow is achieved.

The target operation graph differs depending on the structure of the blast furnace, the tapping ratio, the coke ratio, etc., and thus differs for each operating condition, but it is preferable that the graph satisfies the following conditions.
First, in order to ensure air permeability in the center of the furnace, it is preferable that reactions in the furnace such as reduction of ore do not progress as compared to other regions. Therefore, it is preferable that the gas utilization rate η is low. At the furnace center, ideally η=0.

In a region other than the center of the furnace, it is preferable that the reaction in the furnace proceeds uniformly. This is because if the reaction in the furnace does not proceed uniformly, the gas flow will be uneven, and local fluctuations in operation may make it impossible to obtain a desired tapping ratio or the like.

Such graphs include the graph indicated by reference numeral 200 in FIG.
Specifically, in the graph of FIG. 2, when the radius of the furnace is R, the radial position in the furnace radial direction is r, and the center is 0, the gas utilization rate η at r/R=0 is 0%, 0 . The gas utilization rate η at 4≦r/R≦0.9 is constant in the range of 45% to 60%. Further, the gas utilization rate η at 0≦r/R≦0.4 monotonously increases from 0% to a certain range of 45% to 60%. In the vicinity of the furnace wall (R > 0.9), the preferred gas utilization rate η varies depending on the raw material charging method (how many batches per charge, etc.), so it is not specified, but 0.4 ≤ r / R ≤ It is desirable that the gas utilization rate η is about the same as 0.9.

The target operation graph 200 is not limited to the shape shown in FIG. In an actual furnace, the target operation graph 200 may be obtained by actually measuring the relationship between the position in the furnace radial direction and the gas utilization rate η when stable operation is achieved.

The measurement graph 100 and the target operation graph 200 can be compared by superimposing the two graphs and obtaining the difference in the furnace radial direction, as shown in FIG. For example, in FIG. 2, the measurement graph 100 has a smaller gas utilization rate η than the target operation graph 200 until the relative distance is around 0.0 to 0.45, and the measurement graph 100 has a smaller gas utilization rate η than the target operation graph 200. , the gas utilization rate η is large.

The problematic position is the furnace radial position where the difference in the gas utilization rate η is 20% or more. For example, in FIG. 2, since the difference between the target operation graph 200 and the measurement graph 100 in the gas utilization rate η at the relative distance of 0.1 is 20% or more, the relative distance of 0.1 is the problem position.

<S3: charging step>
In the charging process, the charging amount of iron ore or coke at the problem location in the next charge is adjusted so that the difference in gas utilization η is less than 20%. At this time, it is preferable to measure the deposition shape in the radial direction of the charged material (deposition shape measuring step) and refer to the measured deposition shape to adjust the charging amount in the next charge.

Specifically, when the gas utilization rate η at the problem position is higher than the gas utilization rate η in the target operation graph 200, the iron ore charging amount to the problem position in the next charge is relatively set to the target operation graph 200 Reduce by 0.5 to 5% by mass per 1% difference from. Alternatively, the coke charging amount is relatively increased by 0.5 to 5% by mass per 1% difference from the target operation graph 200.

If the gas utilization rate η at the problem position is lower than the gas utilization rate η of the ideal operation graph, the iron ore charging amount to the problem position in the next charge is relatively per 1% difference from the target operation graph 200 , increase by 0.5-5%. Alternatively, the coke charging amount is relatively reduced by 0.5 to 5% by mass per 1% difference from the target operation graph 200. FIG. 3 shows examples of deposition shapes before and after adjustment.
The above is the detailed description of the blast furnace operating method.

As described above, according to the present embodiment, from the difference in the gas utilization rate η between the measurement graph 100 and the target operation graph 200, the furnace radial position of the local unevenness that affects the gas flow is identified as the problem position. , it is possible to take action to improve operations considering the effects of local unevenness.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to the examples.
(Example 1)
The target blast furnace was a large blast furnace with a volume of 4000 to 5000 ^m3 class, and was producing hot metal at a tapping ratio of 1.8 or higher.

A graph shown in FIG. 2 was prepared as a target operation graph 200 for this blast furnace. This graph shows that the gas utilization rate η is 0% at r/R=0, the gas utilization rate η is 50% at 0.4≦r/R≦0.9, and 0≦r/R≦0.9. 4 is a graph in which the gas utilization rate η at 4 monotonically increases from 0% to 50%.

Next, the gas utilization rate η on one horizontal straight line connecting the center and the furnace wall at a height of 3000 mm or more and 5000 mm or less vertically downward from the upper surface of the charge of this blast furnace is measured using a sonde. was obtained by measuring the CO gas and CO ₂ gas concentrations.

Next, the relationship between the obtained gas utilization rate η and the furnace radial direction was obtained as a measurement graph 100, and the measurement graph 100 and the target operation graph 200 were superimposed.
As a result, at r/R=0.1, the difference in the gas utilization rate η was 20% or more, so this position was detected as a problem position.

Next, the shape of the charge surface on the horizontal line from which the gas utilization rate η was determined was determined using a profile meter. The results are shown in FIG.
Also, the pressure loss at the furnace top at this time was 1500 to 1550 hPa.

In addition, the surface profile of the charge was adjusted as shown in FIG. Specifically, by adjusting the tilting angle of the charging device, the amount of iron ore charged to the problem position in the next charge was relatively reduced by 10% from the target operation graph 200, and an operation improvement action was taken. .

After charging the next charge, a measurement graph 100 was obtained under the same conditions. Finally, the measurement graph 100 was superimposed on the target operation graph 200. FIG. As a result, the difference in the gas utilization rate η between the measurement graph 100 and the target operation graph 200 at the problem location during the previous charging was 10% or less, and the difference was 20% or less.
The pressure loss at the furnace top at this time was 1400-1450 hPa.

From this result, it was found that it is possible to identify the local position that deteriorates the gas flow from the relationship between the gas utilization rate η and the furnace radial direction, and to take improvement action.

10 0... Measurement graph, 20 0... Target operation graph.

Claims (8)

In a blast furnace operation method in which iron ore and coke are alternately charged from the top of the furnace,
a measurement step of obtaining a measurement graph showing the relationship between the position in the furnace radial direction and the gas utilization rate in % in the blast furnace and below the charge;
The target operation graph showing the relationship between the position in the furnace radial direction and the gas utilization rate in % units in the target blast furnace operation is compared with the measurement graph, and the difference in the gas utilization rate is 20% or more in the furnace radial direction. an identifying step of identifying the location as the problem location;
A charging step of adjusting and charging the charging amount of iron ore or coke at the problem location in the next charging so that the difference in gas utilization rate is less than 20%;
A method of operating a blast furnace, characterized by performing When the radius of the furnace is R, the radial position in the furnace radial direction is r, and the center is 0, the target operation graph is:
The gas utilization rate at r/R = 0 is 0%, the gas utilization rate at 0.4 ≤ r/R ≤ 0.9 is constant in the range of 45% to 60%, and 0 ≤ r/R ≤ 0 The method of operating a blast furnace according to claim 1, characterized in that the gas utilization rate at .4 is a graph that monotonically increases from 0% to a certain range from 45% to 60%. The measuring step is a step of determining the gas utilization rate on a horizontal straight line connecting the center and the furnace wall at a height of 3000 mm or more and 5000 mm or less vertically downward from the upper surface of the charge. A method for operating a blast furnace according to claim 1 or 2, characterized by the above. The charging step is
a pile shape measuring step of measuring the pile shape in the radial direction of the charge;
With reference to the measured deposit shape, the charging amount of iron ore or coke at the problem position in the next charge is adjusted so that the difference in gas utilization rate is less than 20%. The method for operating a blast furnace according to any one of claims 1 to 3, characterized by: The charging step is
If the gas utilization rate at the problem position is higher than the gas utilization rate of the target operation graph, the iron ore charging amount to the problem position in the next charge is relatively per 1% difference from the target operation graph, Claim 1, characterized in that it is a step of decreasing by 0.5 to 5% by mass or relatively increasing the coke charging amount by 0.5 to 5% by mass per 1% of the difference from the target operation graph. The method for operating a blast furnace according to any one of claims 1 to 4. The charging step is
If the gas utilization rate at the problem position is lower than the gas utilization rate in the target operation graph, the iron ore charging amount to the problem position in the next charge is relatively per 1% difference from the target operation graph, Claim 1, characterized in that it is a step of increasing 0.5 to 5% by mass or relatively reducing the coke charging amount by 0.5 to 5% by mass per 1% of the difference from the target operation graph. The method for operating a blast furnace according to any one of claims 1 to 4. The charging step is
If the temperature at the problem position is higher than the temperature in the target operation graph, the iron ore charging amount to the problem position in the next charge is relatively set to 0.5 to 0.5 per 1% difference from the target operation graph. Claims 1 to 4, characterized in that it is a step of increasing 5% by mass or relatively reducing the coke charging amount by 0.5 to 5% by mass per 1% of the difference from the target operation graph. The method for operating a blast furnace according to any one of . The charging step is
If the temperature at the problem position is lower than the temperature in the target operation graph, the iron ore charging amount to the problem position in the next charge is relatively set to 0.5 to 0.5 per 1% difference from the target operation graph. Claims 1 to 4, characterized in that it is a step of decreasing by 5% by mass or relatively increasing the coke charging amount by 0.5 to 5% by mass per 1% of the difference from the target operation graph. The method for operating a blast furnace according to any one of .

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