JPS6041122B2 - Blast furnace operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blast furnace operating method, and in particular, determines control values for the shape of the charge distribution in the radial direction of the furnace at the top of the furnace, and ensures that this is within a predetermined range. We propose a method suitable for long-term stable blast furnace operation by controlling the burden distribution.

Generally, when operating a blast furnace, it is necessary to always know how the charges in the furnace are distributed, or where the surface of the bagged material layer is located in the direction of the furnace height.

Recently, a weight-type profile measuring device as shown in Fig. 1 and a French wave-type profile measuring device as shown in Fig. 2 have been developed, allowing a somewhat clear understanding of the charge layer deposition state in the furnace. Now you can. However, the state of deposition of the charge layer in actual operation not only changes due to differences in the particle size composition of the raw material and the gas flow in the furnace, but also changes by adjusting the bellless chute and movalve armour, which are the furnace top distribution control devices. are also very different. However, at present, it is only possible to simply measure the surface shape of the burden, and it has not yet been quantified as to what kind of profile the distribution adjustment can be made to. I was doing it repeatedly.

Therefore, once the operating state of the furnace becomes unstable, it not only takes a long time to recover, but also makes it impossible to operate the blast furnace stably over a long period of time.
The present invention was invented in order to solve the above-mentioned drawbacks of the prior art, and the present invention accurately reflects the movement of the gas flow in the furnace that changes from time to time in the furnace, and the deposition state of the charge in the furnace changes together with the movement of the gas flow in the furnace. It is characterized by stable operation by determining a control value that quantitatively indicates the amount of material, and adjusting various cutting conditions etc. so that the deposited layer of the in-furnace material layer falls within the range of the control value. The purpose of this paper is to propose methods for operating blast furnaces.

In short, the present invention deals with the condition of the bag layer deposited layer:
By setting control values that indicate the charge distribution state to be controlled to achieve the desired gas flow distribution in the furnace and performing feedback control, it is possible to operate the blast furnace without much variation in relation to the operational target. It's a method. The gist of its configuration is that it is a method for operating a blast furnace while controlling the gas flow distribution in the furnace by changing the accumulation state of the contents in the blast furnace. The distance from the furnace inner wall to the mountain part is L.
The deposition surface of the charge layer deposition slope on the furnace center side is 0.
, and when the charge layer deposition angle on the furnace wall side is 82, these values L, 8, , 82 are L: 0.5 to 1.8 h for both ore and coke, and When the filler layer is coke, 8:250 to 350 and 82:±1
00 or less, and in the case of ore, 8,:200
~30 o 82: This is a blast furnace operating method characterized by maintaining the in-furnace deposition state in which the target gas flow distribution is achieved by controlling the gas flow within a range of ±100.

The details of the configuration will be explained below. Generally, blast furnace operation is controlled by the state of accumulation of the contents in the furnace.

In particular, if the deposition angle and shape of the charge deposition layer in the furnace are controlled to a predetermined state, it is possible to always obtain the same charge deposition layer profile in the furnace. Based on the basic knowledge that it is effective for securing security, it has the following structure. That is, the stabilization of blast furnace operation is governed by the gas flow within the furnace.

What governs this is the gas flow seen in the furnace center and the furnace wall. As shown in Figure 3, the gas flow in the furnace center depends on the charge deposition state in the center, and the gas flow in the furnace wall depends on the charge near the furnace wall. It was determined by the deposition state, and furthermore, it was found that the flow of these gases was further regulated by the distance L between the furnace inner wall and the peak in the example of M-shaped charge distribution. Therefore, we researched these 8, 82, and L and decided on the following. In Fig. 3, 1 indicates the furnace wall, 2 indicates the surface of the deposited layer of rhombuses, 3 indicates the position of the peak (distance L from the inner wall surface of the furnace), and 4 indicates the slope of the deposited layer of bagged material on the furnace wall side. The deposition angle is 82, and 5 indicates the rhombite deposition slope on the side of the furnace center, and the deposition angle is 8.

There are various methods for determining the above symbol L, 82, a, but in the present invention, it is determined as follows. As shown in Fig. 4, the distance to the surface 2 of the charge accumulation layer is measured using a profile measuring device (Enoki deep instrument) as shown in Figs. 1 and 2 at six locations in the radial direction of the furnace. The angle of the slope between the ■point and ■point that best represents the appearance of the deposition slope is determined by drawing, and this is determined as the slope deposition angle on the furnace center side, and also the deposition angle on the slope on the furnace wall side. a2 ■ Points and ■
The angle between the points was determined by drawing the same plane. On the other hand, the vicinity of the intersection of the straight lines a and b that regulate the slopes 4 and 5 of the charge deposit layer as described above was defined as the mountain part 3, and the distance from the inner wall surface of the furnace was defined as L.

In addition, the distance to this mountain part 3, the above-mentioned deposition angles 8, and 8
It cannot be set using only straight lines a and b obtained from 2. Fifth
As shown in the figure, the same a, 62 has various sizes of L, and the profile shown in the furnace radial direction is also completely different depending on the difference.Therefore, in the case of the present invention, taking these circumstances into consideration, The position of part 3 was identified by the intersection of lines a and b as described above.In addition, if the measurement method is different, statistical processing using a computer is performed by calculating the number of measurement points.For example, if the measurement method is different, the number of measurement points will be ignored and statistical processing will be performed using a computer. For single wave and laser methods, it is desirable to obtain the measured value using the least squares method and calculate 8,,82.Next, at the same time as showing the state of the charge deposit layer
This section explains how to set control values that serve as targets for blast furnace operation.

Generally, in blast furnace operation, the gas flow in the furnace changes depending on the profile of the charge deposited layer of the raw material charged from the top of the furnace, and by adjusting this, it is possible to stabilize the descent of the bags.

Therefore, the stability of the falling object, that is, the slip frequency or the wind pressure fluctuation index, and the measured values L, a, .
The correlation with the value of a2 was investigated and such a control value was determined. Figure 6 shows the relationship between the slip frequency and the pile angle 8, of the charge layer on the side of the center of the furnace, and Figure 7 shows the relationship between the number of air deflation times and the pile angle 8,
Indicates the relationship between In the figure, the ○ marks indicate the ore stacking angle of 8, and the x marks indicate the coke stacking angle of 8. From this figure, it can be seen that when the stacking angle of the ore in the ore is 0, there is little slippage at 300 or less. If the stacking angle 8 is 20 to 30 degrees or less, the number of times the air is sloughed off to suppress wind pressure fluctuations is also small. If this 8 is less than 20o, it means that a lot of ore is deposited in the center of the furnace, and as the ventilation deteriorates, the wind pressure fluctuates more and the number of times the wind is turned off increases. . In addition, when the number of ores exceeds 300, ore transfers down the slope of the charge layer and deposits in the center, creating a flow that causes instability in unloading and increases slippage. . Therefore, the preferred range for stable operation with no slip and little wind pressure fluctuation is the above-mentioned pile angle 0, 20o to 30o.
The range is . On the other hand, if the deposition angle of coke in the charge is 8.0 degrees or less, the slip frequency is high, and if it is 35 degrees or more, the number of air reductions is increased.

In short, as the coke deposition angle 8 increases, more ore, which is then charged in the upper layer, flows into the center of the furnace, resulting in poor air permeability and unstable furnace conditions. A small coke deposition angle means that a large amount of coke is deposited in the center, and the ore is shifted toward the furnace wall, resulting in center flow-oriented operation, which stabilizes the wind pressure. The growth of the wall inert zone is promoted and slips are more likely to occur. From the above explanation, the coke deposition angle a is set to 250 to 35 degrees. Now, the deposition angle 02 of the slope of the charge layer in the furnace wall example indicates that the deposition state of the charge is 8th.
As shown in the figure, the M-type a and V-type b distributions exhibit different aspects. Therefore, when the sign of the stacking angle 82 is positive, it is assumed to be M type, and when it is negative, it is assumed to be V type. In the M-type distribution, when the coke deposition angle 02 is large, a large amount of ore is charged toward the furnace wall, which causes deposits to form. Furthermore, in the V-shaped distribution, if the coke deposition angle 02 is large, the flow of ore into the center of the furnace is promoted, and the above-mentioned wind pressure becomes unstable. In the case of ore, when the deposition angle a2 is large in the M-shaped distribution, a large amount of coke is charged to the furnace wall, resulting in excessive peripheral flow direction, and when the deposition angle 82 is large in the V-shaped distribution, coke flows toward the center of the furnace. This promotes crowding and is unfavorable in terms of distribution control. FIG. 9 shows the relationship between the accumulation angle a2 and the number of wind pressure fluctuations (wind reduction number).

As is clear from this figure, when coke exceeds soil 100, wind pressure fluctuations increase, and ore also experiences more wind pressure fluctuations when it exceeds soil 100. Therefore, the proper management of the pile angle 82 is soil 1
oo, that is, it is within 1° in both the M-type and V-type distributions of the in-furnace contents deposition state. Next, regarding the position of the peak 3, that is, the distance L from the furnace inner wall surface, for example, if the distance L to the peak 3 for ore is long, the ore will be bagged toward the center of the furnace, and the wind pressure level will increase. However, this means that the ventilation in the center of the furnace deteriorates.

On the other hand, in the case of coke, the larger the distance L to the peak 3, the easier it is for coke to enter the furnace center, resulting in excessive central flow direction and promoting the growth of an inert zone on the furnace wall. . FIG. 10 of the drawings shows the relationship between the distance L to the mountain and the number of slips (times/day). As you can see from this figure, the distance from the inner surface of the furnace wall to the peak 3 is 0.5 to 1.8 h.
Since slips occur less frequently between the two, this value was set as the appropriate control value. In this way, the deposition angle 0,,
02 and the distance L to the above set values, a constant deposition state can always be obtained, and stable blast furnace operation can be achieved over a long period of time under an appropriate gas flow distribution. I can do it. In addition, as a method of controlling the deposition distribution of the contents in the furnace so that each control value L, 8, 82, which is the target for blast furnace operation, is within the set range as described above, there is a method for controlling the deposition distribution of the contents in the furnace in a bell-type blast furnace. If so, you can take appropriate measures such as adjusting the movement angle of the mover pull armor or adjusting the stock line.

On the other hand, in the case of a bellless blast furnace, this can be done by appropriately adjusting the mirror angle of the rotating chute or the stock line. In addition, the stock line referred to here refers to the distance from the zero point to the surface of the charge layer, with the zero point lm below the bottom of the bell in the case of a bell type, and the distance from the zero point to the surface of the charge layer in the case of a bellless type. The zero point is 1m below the bottom edge of the charging layer, and it refers to the preset charging line from that zero point to the surface of the charging layer.

Next, an example in which blast furnace operation was performed using the control values serving as management targets for the three blast furnace operations described above will be described below. Charging conditions are coke base 34.3/ch, ore 118/ch in that bell type blast furnace with an internal volume of 4500.
, the stock line was 1.2 hours, and the mover pull armor was operated at settings C and Q.

(C, 03 is the Na2 notch when charging coke into the furnace, and the gunwale when charging ore when the movable armor notch setting is at five points from ■ to ■ as shown in Fig. 11. This is a method of controlling the distribution of the charging material by applying the charging material to the movable armor 7.) Hereinafter, a specific example of its operation will be described based on FIG. 12. FIG. 12 shows changes over time in the above target control values during blast furnace operation.

On date 4'2, the coke deposition angle 82 on the furnace wall became large. So I changed the stock line from 1.2h to 1.3h.
By lowering the temperature to h, the coke was injected into the furnace wall side, changing the M-type distribution to the V-type distribution. As a result, a2 became smaller and fell within the control value. Thereafter, on date 4'6, the deposition angle 0 on the furnace center side decreased for both coke and ore.

Therefore, by changing the ore armor notch from ■→■ to a coke armor notch ■→■ and charging ore and coke to the furnace wall side, we attempted to recover the deposit 8.
After that, on April 10th, the distance L to the ore mountain capital decreased by 4.

Therefore, when the ore was charged into the furnace by returning the ore's armor notch from ■ to ■, the size of the distance increased. After that, on April 13th, the coke deposition angle 8, at the center of the furnace became too large, so the stock line was raised and more coke was charged into the furnace, so the deposition angle 8, became smaller. Ta. When the blast furnace was operated with the above-mentioned control values of L, 8, and 82 as targets, it became possible to operate the blast furnace stably over a long period of time.

In this example, by combining and changing the set values of the stock line and movable armor and adjusting them to the predetermined control values, it was possible to maintain an appropriate gas flow distribution and ensure long-term stability. This made it possible to operate a blast furnace that

On the other hand, even if some of the operational actions for controlling the burden distribution are appropriately combined, the profile of the burden layer in the radial direction within the furnace can be maintained appropriately. For example, by appropriately selecting and combining charging conditions other than the combination of movable armor and stock line as in the above embodiment,
The blast furnace may be operated to achieve the control value of the present invention. As explained above, according to the present invention, it is possible to maintain the accumulated state of bags in the furnace in an appropriate state with little fluctuation in the furnace conditions, so it is possible to ensure stable blast furnace operation over a long period of time. became.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the weight type profile measuring device, Figure 2 is a schematic diagram of the chopper wave type profile measuring device, Figure 3 is a schematic diagram of the profile showing the state of deposits in the furnace, and Figure 4 is a schematic diagram of the profile measuring device. is an explanatory diagram showing control value measurement standards; FIG. 5 is a schematic diagram showing the relationship between control values 8, 82, and L; FIG. 6 is a graph showing the relationship between slip frequency and accumulation angle a; The figure is a graph showing the relationship between the wind reduction number and the pile angle 8, Figure 8 a and b are schematic diagrams showing the burden distribution format, and Figure 9 shows the relationship between the wind reduction circuit and the pile angle a2. Fig. 10 is a graph showing the relationship between the number of slips and the distance L to the peak, Fig. 11 is a schematic diagram showing how the armor notch operates, and Fig. 12 is a graph showing each control value in the example operation. It is a graph of changes over time. 1... Furnace wall, 2... Surface of charge deposit layer,
3...Position of the peak indicating the distance L from the inner surface of the furnace wall, 4...Position of the bagged material accumulation slope on the furnace wall side (accumulation angle 0,
), 5...The charge deposition slope on the side of the furnace center (deposition angle 8
．． ), 6"""Bell, 7"""Armor Notch. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12

Claims (1)

[Claims] 1 By changing the deposition state of the contents in the blast furnace,
In a method of operating a blast furnace while controlling gas flow distribution in the furnace, the charge accumulation layer in the furnace radial direction of the charge in the furnace is defined as L, the distance from the furnace inner wall to the peak, and the distance from the furnace center side to the furnace center side. The deposition angle of the charge layer deposition slope is θ_1, and the deposition angle of the charge layer deposition surface on the furnace wall side is θ_2.
When these values L, θ_1, θ_2 are ore and
L: 0.5 to 1.5 m for both coke and when the charge layer is coke, θ_1: 25° to 35
The furnace achieves the target gas flow distribution by controlling the temperature so that θ_2 is within ±10°, and in the case of ores, θ_1 is within the range of 20° to 30°, θ_2 ±10°. A method of operating a blast furnace characterized by maintaining an internally deposited state.