JPS62177109A - Method for charging starting material into bell-less blast furnace - Google Patents

Abstract

PURPOSE:To freely control the distribution of O/C in a blast furnace in the radial direction by charging starting materials into the furnace from the central part toward the wall and regulating the accumulation angle of the surface of the charged starting materials to a specified value or below. CONSTITUTION:Starting materials 3 conveyed to the top of a blast furnace 1 through a belt conveyor 2 are stored once in a top bunker 6 through upper gate valves 4 and upper seal valves 5 and re charged into the furnace 10 through a distribution chute 10. At this time, the tilt angle of the chute 10 is controlled and at least one among the tilt angle of the chute 10, the number of revolutions of the chute 10 at each tilt angle and the degree of opening of lower gate valves 8 is also controlled so that the accumulation angle of the surface of the charged starting materials does not exceed 20 deg..

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for charging raw materials into a bellless blast furnace, and more specifically, the present invention relates to a method for charging raw materials into a bellless blast furnace, and more specifically, a method for charging raw materials in a bellless blast furnace,
The tilting angle of the distribution chute is designed to improve the controllability of the so-called charge distribution, such as the radial ore to coke weight ratio (hereinafter abbreviated as RO/CJ) distribution and the radial particle size distribution. The present invention relates to a setting method and control of the deposition angle on the surface of raw materials after charging.

(Prior art) In blast furnace operation, the charge at the top of the blast furnace is
It is necessary to appropriately control the radial distribution of C1 grain size, etc., maintain the radial gas flow distribution and heat flow ratio distribution within the furnace within a predetermined range, and stably reduce and melt the ore.

A conventional method for charging raw materials into a bellless blast furnace will be explained using FIG. 6. FIG. 6 shows a schematic diagram of a raw material charging device at the top of the furnace of a bellless type blast furnace. Once the charge in the blast furnace is unloaded and reaches a predetermined stock level 7 to be replenished, the lower gate valve 8 for adjusting the charge flow rate and the lower seal The valve 9 is opened and the raw material in the furnace top bunker 6 is charged into the furnace through the distribution chute 10.

(Problem to be solved by the invention) However, in the conventional raw material charging method, the O/C in the radial direction
Control of the distribution and radial particle size distribution was insufficient.

First of all, there are drawbacks to the controllability of O/C distribution in the radial direction, such as: ■ Fluctuations in the amount of mixed layer formed during ore charging, ■ Fluctuations in the stacking angle of raw materials, and ■ Fluctuations in the time required for charging into the furnace. One example of this is that the O/C distribution in the radial direction is likely to fluctuate.

Each of them will be explained in detail below.

■ Regarding fluctuations in the amount of mixed layer formed during ore charging In the conventional material charging method, the tilting angle of the distribution chute (θ in Figure 6: the angle between the distribution chute and the axis of the blast furnace) The raw materials were charged from the wall of the furnace to the center of the furnace by gradually reducing the amount from a predetermined angle. Therefore, in most cases, the surface shape of the raw material after charging was M-shaped as shown in FIG. 6, or an M-shaped shape, both of which formed slopes. Therefore, when ore is charged on top of the coke layer, part of the surface layer of the coke layer near the ore falling position is scraped off by the impact energy of the ore and moves toward the center of the furnace, causing a wide area in the center of the furnace. A mixed layer of ore and coke is formed and deposited.

Regarding the formation of a mixed layer in the bellless charging method, two of the present inventors have reported a study using a full-scale model ("Tetsu to Hagane" Vol. 71, 1985, p. 175). An example of this mixed layer measurement is shown in FIG. In the figure, the broken line shows the surface shape of the coke layer before ore charging, and the solid line shows the coke layer surface shape after ore charging. The coke that was present near the ore fall position on the furnace wall has been moved to the vicinity of the center.
A monolayer of coke and a mixed layer of ore and coke are formed over a wide area. In this way, if the coke layer forms a slope, the surface shape of the coke layer changes during ore charging, and the radial O/C distribution is calculated from the surface shape of the raw material before and after ore charging. This is significantly different from the 0/C distribution. Furthermore, the amount of mixed layer formed is influenced by not only controllable factors such as the distribution chute tilt angle schedule and charging amount, but also disturbance factors such as changes in the particle size composition of the raw material and changes in the surface shape of the coke layer due to changes in the gas flow distribution in the furnace. receive. Therefore, the controllability of the 0/C distribution in the radial direction was insufficient in the conventional bellless charging method of forming an inclined surface.

■Regarding fluctuations in the stacking angle of raw materials The second problem with the radial O/C distribution due to the formation of slopes is that the fluctuations in the stacking angle of the charged raw materials cause the radial O
/C distribution is likely to fluctuate.

In other words, the shape of the surface layer of the raw material changes due to variations in the gas flow distribution in the furnace, so even if the raw material is charged into the furnace with the same distribution chute tilting angle schedule, the same charging amount, or the same charging conditions, , the 070 distribution in the radial direction varies.

■Regarding variation in furnace charging time The third problem arises in the conventional charging method in which the distribution chute tilt angle is gradually decreased from large to small, regardless of whether or not a slope is formed. That is, in the conventional charging method,
The raw material is charged from the part where the raw material layer thickness increases per unit time is small, ie, the furnace wall, to the part where the raw material layer thickness increases per unit time, ie, the center part. For this reason, due to changes in the particle size composition of the raw materials and fluctuations in the moisture content of the raw materials,
If the outflow characteristics at the lower gate valve change and the total charging time into the furnace changes, the variation in the layer thickness of the material at the center, where the material enters the furnace at the end of charging, becomes extremely noticeable. .

Next, two drawbacks regarding the controllability of the radial Φ particle size distribution will be described.

The first drawback is that in the conventional charging method, the tilting angle of the distribution chute is gradually reduced from large to small to form a slope, so the raw material charged into the furnace is reclassified on this slope. As a result, fine particles are segregated and deposited on the upstream side of the slope, that is, on the furnace wall, and coarse particles are segregated and deposited on the downstream side of the slope, that is, in the center. That is, in the conventional charging method, the final radial particle size distribution is determined by reclassification on the slope. Therefore, when the shape of the slope changes due to changes in the radial gas flow distribution or changes in the radial unloading speed distribution, the radial particle size distribution also changes significantly. Furthermore, if the particle size structure of the charged raw material fluctuates, it also has the disadvantage that the fluctuation is exacerbated by reclassification on the slope.

In addition, in recent years, in order to improve the controllability of particle size distribution in the radial direction,
A method has been developed in which the same raw material with different average grain sizes is charged at different radial positions in the furnace, the so-called "grain size charging method". In the conventional charging method of forming a slope, even in the charging method according to particle size, the effect could not be sufficiently exhibited. That is, for example, if the ore is charged in two parts and the fine grains are deposited on the furnace wall, and the fine grain ore is charged the first time, part of the fine grain ore is charged during the second coarse grain ore charge. This is because the particles are moved toward the center by the impact energy of the falling coarse ore, and the proportion of the particles remaining on the furnace wall is small. what if,
Even if fine-grained ore is charged a second time to increase the ratio of fine-grained particles remaining on the furnace wall, coarse-grained ore is charged closer to the center to form an M-shaped surface shape, It is necessary to charge the fine ore into the recess between the surface layer of the coarse ore and the grain size distribution in the radial direction and the O/C distribution at the same time.

In this way, the conventional material charging method for bellless blast furnaces in which the tilting angle of the distribution chute is gradually decreased from large to small has insufficient controllability of the radial O/C distribution and particle size distribution. .

The present invention solves the above-mentioned problems and provides a material charging method for a bellless blast furnace that can improve the controllability of so-called charge distribution such as radial O/C distribution and particle size distribution in the furnace. This is what I am trying to do.

(Means for Solving the Problems) When charging raw materials into a bell-less blast furnace, the present invention controls the tilting angle of a distribution chute so that the raw materials are charged from the center of the furnace toward the side wall of the furnace. , the gist is to control at least one of the tilting angle of the distribution chute, the number of turns at each tilting angle, and the opening degree of the lower gate valve so that the deposition angle on the surface of the raw material after charging does not exceed 20 degrees. This is a material charging method for a bellless blast furnace.

That is, the features of the present invention are: (1) charging the raw material from the center of the furnace toward the furnace wall; (2) setting the deposition angle on the surface of the raw material after charging to be 20 degrees or less; The aim is to freely control the 0/C distribution in the direction and the particle size distribution in the radial direction.

First, in order to achieve the first condition, a schedule is set in which the tilting angle of the distribution chute is gradually increased from small to large. The arrows shown in FIG. 1 indicate the movement of the distribution chute tilt angle. Note that the same numbers in FIG. 1 as in FIG. 6 indicate the same or corresponding parts, and their explanation will be omitted.

Next, in order to achieve the second condition, at least one of the tilting angle of the distribution chute, the number of turns at each tilting angle, and the opening degree of the lower gate valve can be arbitrarily set.

By making such equipment improvements, the radial zero
/C distribution can be freely controlled, and controllability of radial particle size distribution is also improved.

In addition, in order to more freely control the particle size distribution in the radial direction, the number of furnace top bunkers 6 may be increased as necessary, and the average particle size of each of these furnace top bunkers 6 may be changed for storage.
In order to control grain size segregation during charging into the top bunker 6, distribution control mechanisms such as a rotating chute 11 and a repulsion plate 12 are installed in the top bunker 6, and a It is also optional to install various inserts such as a cone 13 or a rectangular parallelepiped 14 in the furnace top bunker 6 for the purpose of controlling changes in particle size over time.

In this way, it becomes possible to control the radial particle size distribution independently of the radial O/C distribution control. FIG. 1 shows an example of charging coarse material to the furnace wall and charging fine material to the center, which could not be achieved with the conventional bellless charging method.

Next, the reason why the deposition angle on the surface of the raw material after charging is set to 20 degrees or less will be described. The present inventors manufactured a full-scale model outside the furnace, changed the deposition angle of the coke layer variously, charged ore, and measured the amount of mixed layer formed and the particle size distribution in the radial direction. Examples of the results are shown in FIGS. 2 and 3.

Figure 2 is a diagram showing the relationship between the deposition angle of the coke layer and the increase in the thickness of the coke layer in the center (increase in the thickness of the single coke layer + 172 x increase in the thickness of the mixed layer). It has been found that the coke deposition angle is approximately 20 degrees, and when this angle is exceeded, the thickness of the coke layer in the center increases significantly due to ore charging, but below this angle, it is practically negligible. That is, in order to improve the controllability of O/C distribution in the radial direction, it is necessary to set the stacking angle of the raw material after charging to 20 degrees or less.

FIG. 3 is a diagram showing the relationship between the deposition angle of the coke layer and the grain size of the ore in the center (the test was carried out using all sintered ore). The coke deposition angle has a boundary of 20 degrees, and when this is exceeded, the ore grain size in the center increases significantly due to reclassification on the slope, but below this, the ore grain size does not increase in practical terms. It is clear that it is so small that it can be ignored. The reason is,
This is thought to be because the stacking angle of the slope is sufficiently small, and even if a pile of charge material corresponding to the swirl is formed during charging, the raw material does not move along the slope. That is, in order to improve the controllability of the particle size distribution in the radial direction, it is necessary to set the stacking angle of the raw material after charging to 20 degrees or less.

As described above, in order to significantly improve the control of the radial O/C distribution and the radial particle size distribution, the deposition angle on the surface of the raw material after charging needs to be 20 degrees or less.

Incidentally, the deposition angle of the raw material is actually measured, and whether or not the deposition angle is 20 degrees or less can be confirmed using a profile meter normally installed at the top of the blast furnace. Profile meters can be of the contact type, in which a heavy cone attached to the tip of a wire is lowered onto the surface of the deposited raw material, or the profile meter can be a contact type, in which a heavy cone attached to the tip of a wire is lowered to the surface of the deposited material. A non-contact method may also be used in which the wave oscillated from an oscillator is received and measured by the reflected wave reflected from the surface on which the raw material is deposited.

If the stacking angle of the raw material after charging is likely to exceed 20 degrees, control at least one of the tilting angle of the distribution chute, the number of turns at each tilting angle, and the opening degree of the lower gate valve, The deposition angle is controlled to be maintained at 20 degrees or less while measuring the profile using the profile meter and confirming its effectiveness.

Further, in the method of the present invention, the tilting angle of the distribution chute is gradually increased, but this cannot be easily invented even by a person skilled in the art.

That is, by gradually decreasing the tilting angle of the distribution chute (in the conventional method, the direction of the moment caused by the distribution chute load and the material load on the distribution chute,
Since the distribution chutes are tilted in the same direction, the shaft torque applied to the tilting motor is small and therefore within the allowable rated torque range of the motor. On the other hand, in the present method of increasing the tilting angle of the distribution chute, the direction of the moment generated by the distribution chute load and the load of the raw material on the distribution chute is opposite to the direction of the tilting of the distribution chute. Therefore, since the shaft torque applied to the tilting motor is large and expected to exceed the rated torque of the motor, an invention such as the present invention in which the tilting angle of the distribution chute is gradually increased has not been made.

However, when implementing the present invention, we actually measured the required torque of the motor shaft when the tilting angle of the distribution chute was gradually increased. It has been found that the tilting angle of the distribution chute can be gradually increased within the commonly used distribution chute tilting angle range.

Therefore, the present invention in which the tilting angle of the distribution chute is gradually increased can be implemented with a small investment.

(Function) When charging raw materials into a bellless blast furnace, the present invention controls the tilting angle of the distribution chute so that the raw materials are charged from the center of the furnace toward the furnace side wall, and The method controls at least one of the tilting angle of the distribution chute, the number of turns at each tilting angle, and the opening degree of the lower gate valve so that the deposition angle on the surface of the raw material does not exceed 20 degrees. The O/C distribution and particle size distribution can be controlled independently and accurately.

(Example) In order to confirm the effects of the present invention, a full-scale model was manufactured outside the furnace and a charge distribution test was conducted.

The charging material used in the test was the material used in an actual blast furnace. In addition, the charging conditions for the raw material in the test were the same as those in an actual blast furnace, except that there was no unloading and no air blowing, and the 070 distribution and particle size distribution in the radial direction were It was solidified with epoxy resin, taken out of the device, and measured.

By applying the present invention, the radial O/C distribution and the radial particle size distribution can be independently and freely controlled.

For example, the conventional charging method was changed to C (11223344556677
), O(11223344556677).

The numbers in parentheses indicate the magnitude and order of the tilting angle of the distribution chute, and the smaller the number, the larger the tilting angle of the distribution chute is set.

The number of turns was 14. The 070 distribution and particle size distribution in the radial direction within the furnace under these charging conditions are shown in (A) in FIG. When the furnace wall gas flow is slightly strengthened, the conventional invention does not have a means to control the particle size distribution in the radial direction, and the tilting angle of the ore distribution chute is reduced to 0 (223344
55667788). For this reason, as shown in FIG. 5 (B), it is not possible to reduce only the 070 distribution in the furnace wall portion, resulting in an increase in O/C in the middle portion. Furthermore, due to changes in the ore charging schedule, the particle size distribution in the radial direction has a minimum point in the middle of the furnace.

On the other hand, in the method of the present invention, the 070 distribution in the radial direction is (
Charging schedule C (1099876
54322111)O(10988776655432
If 1) is adopted and coarse particles are charged only when charging the furnace wall (distribution chute tilt angles 1 and 2), the gas flow distribution in the furnace can be controlled only by controlling the particle size distribution in the radial direction. . (C) in FIG. 5 shows the radial O/C distribution and radial particle size distribution according to the present invention.

(Effects of the Invention) As explained above, when charging raw materials into a bell-less blast furnace, the present invention allows the raw materials to be charged from the center of the furnace toward the side wall of the furnace (while controlling the tilt angle of the distribution chute). , at least one of the tilting angle of the distribution chute, the number of turns at each tilting angle, and the opening degree of the lower gate valve is controlled so that the deposition angle on the surface of the raw material after charging does not exceed 20 degrees. Therefore, 070 in the radial direction inside the blast furnace
The distribution and particle size distribution can be controlled independently and with high precision, which is extremely effective in blast furnace operation.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the method of the present invention, Figure 2 is a relationship between the coke layer deposition angle and the coke layer thickness at the center of the furnace, and Figure 3 is a relationship between the coke layer deposition angle and the ore grain size at the center of the furnace. Figure 4 is a diagram showing the relationship between the tilting angle of the distribution chute and the motor shaft torque, and Figure 5 is a comparative illustration of the conventional charging method and the method of the present invention aimed at strengthening the furnace wall gas flow. , FIG. 6 is an explanatory diagram of the conventional method, and FIG. 7 is an explanatory diagram of the state of formation of a mixed layer in the conventional method. ■ is the blast furnace, 3 is the raw material, 6 is the furnace top bunker, 7 is the struthole, 8 is the lower gate valve, and 10 is the distribution chute. Figure 5

Claims (1)

[Claims] (1) When charging raw materials into a bell-less blast furnace, the tilting angle of the distribution chute is controlled so that the raw materials are charged from the center of the furnace toward the side wall of the furnace, and the deposition angle on the surface of the raw materials after charging is controlled. A method for charging materials into a bellless blast furnace, characterized in that at least one of the tilting angle of the distribution chute, the number of turns at each tilting angle, and the opening degree of the lower gate valve is controlled so that the distribution chute does not exceed 20 degrees.