JPS62260009A - Charging method for pellet-compounded raw material in bell-less type blast furnace - Google Patents

Abstract

PURPOSE:To stabilize a blast furnace operation by controlling the pellet content in the raw materials to be supplied into a distributing chute and controlling the pellet content distribution in the furnace to an adequate shape by the operation of the distributing chute. CONSTITUTION:The iron source raw material compounded with pellets are charged from a sintered ore storage tank 15 and a pellet storage tank 16 via a discharging gate 17 into the bell-less type blast furnace 1 by the distributing chute 10 through a charging belt conveyor 2 and a top bunker 6. The timing for the opening operation of the above-mentioned discharging gate 17 and the opening degree thereof are controlled in the above-mentioned charging method, by which the content of the pellets in the above-mentioned raw materials supplied into the distributing chute 10 is controlled constant or with age. The angle of inclination of the distributing chute 10 is further controlled in an arrow direction to charge the raw materials into the furnace wall direction from the central part of the furnace. At least one of the angle of inclination and the number of swiveling of the distributing chute 10 and a lower gate 8 are controlled at the same instant to control the deposition angle on the raw material surface after charging into the furnace to <=20 deg., by which the reseparation of the pellets is prevented.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for charging raw materials into a blast furnace having a bellless charging device. The present invention relates to a method for charging raw materials into a bellless blast furnace, which enables accurate control of the pellet content distribution within the ore layer in the radial direction of the furnace when charging raw materials (hereinafter referred to as "ore").

(Prior art and its problems) In blast furnace operation, it is necessary to accurately control the radial distribution of the charge at the top of the blast furnace to stably reduce and melt the ore.

A conventional method for charging raw materials into a bellless blast furnace will be explained using FIG. 10. FIG. 10 schematically shows the top of the bellless blast furnace.
The raw material 3 transported by is temporarily stored in a top bunker 6 through an upper gate valve 4 and an upper seal valve 5, and the charge in the blast furnace is unloaded and reaches a predetermined stock level 7 to be replenished. When it reaches the top bunker 6, the lower gate valve 8 and the lower seal valve 9 for adjusting the charging flow rate are opened.
The raw materials in the furnace are charged into the furnace via the distribution chute 10.

Now, generally speaking, the control target for the charge distribution in the blast furnace is
Weight ratio distribution of ore and coke in the radial direction (hereinafter referred to as “070
In addition to particle size distribution, the radial distribution of these various raw materials with different properties is also important in recent blast furnace operations that use multiple types of raw materials such as sinter and pellets as ores. It is subject to control.

In other words, in recent blast furnace operations, sintered ore is mainly used as the ore, and approximately 5 to 20% by weight of pellets is mixed with this. They have quite different physical and chemical properties.

In other words, ■Since pellets are spherical, their own deposition angle is small, and if a large amount of pellets is used, the ore layer thickness at the center of the furnace will increase, and the permeability of the center of the furnace will deteriorate. Gas flow rate decreases.

■Pellets have poor reducibility compared to sintered ore, and therefore have poor high-temperature properties.Therefore, the softened and fused part of the ore layer containing a large amount of pellets has poor air permeability, leading to worsening of unloading. It will also happen.

Therefore, when pellets are mixed with sintered ore and used, it is desirable that the pellets are distributed as uniformly in the radial direction as possible without being localized in the furnace.

Next, a method for charging pelletized raw materials into a conventional bellless blast furnace will be described. That is, in the conventional method, as shown in FIG. It is being

However, there have already been some reports (for example, Tetsu to Hagane Vol. 1.
70 (1984) S43) and as confirmed by the inventor himself as described later, in such a method, when the pellets are placed in the upper stage of the furnace top bunker 6 (1st)
In case (b)), a large amount of pellets are discharged at the end of charging, and when pellets are placed in the lower stage (Fig. 1) (b)), a large amount of pellets are discharged at the beginning of charging. That is, in the conventional charging method in which raw materials are charged while gradually decreasing the tilting angle (θ in FIG. 10) of the distribution chute 10 from a position with a large tilt angle (θ in Fig. 10), in the former pellet arrangement, it is difficult to In addition, in the latter case, a large amount of pellets accumulates on the furnace wall, and the pellet content distribution in the radial direction inside the furnace becomes non-uniform.

Therefore, the pellets in the raw material discharged from the top bunker.

In order to maintain a constant change in the content over time, a method can be considered in which sintered ore and pellets are completely mixed and charged into the furnace top bunker.

However, in the conventional charging method in which the surface shape of the deposited charge is inclined toward the center of the furnace, as will be described later in the embodiments of the present invention, after the mixed raw material falls onto the surface of the deposit in the furnace, When the sintered ore flows along the slope, the sintered ore and the pellets, which have different shapes and particle sizes, separate again, making it difficult to uniformly distribute the pellets in the radial direction inside the furnace.

In other words, according to the conventional method, it is difficult to uniformly distribute pellets in the radial direction inside the furnace, and if the ratio of pellets used in the frame increases, the markedly uneven distribution of pellets will worsen the furnace condition. There is always a bottom.

Furthermore, in the conventional method, it is difficult to actively control the pellet content distribution within the furnace.

The present invention solves the above-mentioned problems, and provides a method for charging pellet-containing iron source material that controls the radial pellet content distribution in the furnace in an appropriate manner and stabilizes blast furnace operation. be.

(Means for Solving the Problems) When charging iron source raw material containing pellets into a bell-less blast furnace, the present invention maintains the pellet content in the raw material supplied to a distribution chute at a constant rate or over time. control,
In addition, the tilting angle of the distribution chute is controlled to charge the raw material from the center of the furnace toward the furnace wall, and the tilting angle of the distribution chute is controlled so that the deposition angle on the surface of the raw material after loading into the furnace does not exceed 20 degrees. This is a method for charging pellet blended raw materials into a bellless blast furnace, the gist of which is to control at least one of the angle, the number of rotations at each tilt angle, and the opening degree of the lower gate valve.

That is, the present invention provides an apparatus which is configured to control over time the pellet content in the pellet-containing raw material supplied from the furnace top bunker to the distribution chute, control the distribution chute operability, and control the surface shape of the raw material deposited in the furnace. , the detailed configuration of the present invention will be explained based on FIG.

First, the pellet content in the pellet blended raw material supplied from the furnace top bunker to the distribution chute is controlled over time, and this is done by controlling the ease of feeding the raw material into the furnace top bunker.

That is, in order to keep the pellet content of the raw material discharged from the furnace top bunker constant, the sintered ore and pellets must be completely mixed within the bunker.

For this purpose, the timing and opening degree of the opening operation of the discharge gates 17 of the sinter storage tank 5 and the pellet storage tank 16 are controlled, and the sinter and pellets are loaded on the charging belt conveyor 2 in the longitudinal direction at a constant ratio. In this way, raw materials are charged into the furnace top bunker 6. At this time, if an insert 12 or a centering chute 13 is installed in the upper part of the furnace top bunker 6, re-separation of the sintered ore and pellets during charging into the furnace top bunker 6 can be effectively suppressed. 14 in the figure is a lifting mechanism for the insert 12.

On the other hand, if you want to change the pellet content of the raw material discharged from the top bunker 6 over time, you can change the pellet content distribution in the height direction of the raw material in the top bunker 6. By controlling the opening/closing operation timing and opening degree of each discharge gate 17 for sintered ore and pellets, the pellet content distribution in the longitudinal direction of the raw material on the charging vent conveyor 2 can be changed. Furthermore, by installing a harmful object such as the insert 12 in advance in the lower part of the furnace top bunker 6, the discharge pattern of the raw material in the furnace top bunker 6 can be brought closer to a mass flow (Bragg flow). Controllability over time of the pellet content in the raw material discharged from the furnace top bunker 6 can be made more reliable.

By performing the above operations, the pellet content in the pellet blended raw material supplied from the furnace top bunker 6 to the distribution chute 10 can be controlled at a constant rate or over time.

Next is distribution chute operability control and surface shape control of the raw material deposited in the furnace.The basis of this control is the distribution chute 10.
The main points are that the pellet-containing raw material is charged from the center of the furnace toward the furnace wall by controlling the tilt angle, and that the stacking angle of the pellet-containing raw material after charging does not exceed 20 degrees.

In other words, by charging the raw material from the center of the furnace toward the furnace wall, fluctuations in the charge layer thickness due to fluctuations in the material charging time can be alleviated, and the stacking angle of the raw material after charging can exceed 20 degrees. This prevents the charged raw material from rolling down the slope and stays near the falling position, which not only prevents the re-separation of sinter and pellets after charging, but also reduces the risk of re-separation when a large amount of pellets are used. Changes in the radial O/C distribution due to changes in the ore pile angle can also be alleviated, and furthermore, so-called coke flow and the formation of a mixed layer that occur when ore is charged onto the surface of the coke layer can also be suppressed at the same time.

By the way, in order to charge the pellet blended raw material from the center of the furnace toward the furnace wall, a schedule is set in which the tilt 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 1 in the movement angle. Note that the same numbers in FIG. 1 as in FIG. 1O indicate the same or corresponding parts, and the description thereof will be omitted.

Next, the deposition angle on the surface of the pellet-containing raw material after charging was set to 20
In order to keep the distribution chute below the angle, 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.

Next, the reason why the deposition angle on the surface of the pellet-containing raw material after charging is set to 20 degrees or less will be described in more detail.

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 shows 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 + 1/2 X increase in the thickness of the mixed layer N), which is clear from the figure. It has been found that the coke deposition angle reaches a boundary of 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 that, it can be practically ignored.

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 panoramic 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.

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 confirming the descent by performing measurements using the early profile meter.

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 method of the present invention in which the tilting angle of the distribution chute is gradually increased, 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, in carrying out the present invention, we actually measured the required torque of the motor shaft when the tilting angle of the distribution chute was gradually increased, and as shown in Figure 4, it was found that if the capacity of the conventional motor was increased by about 20%, it could be used regularly. It has been found that the tilting angle of the distribution chute can be gradually increased within the distribution chute tilting angle range.

Therefore, the present invention can be implemented by gradually increasing the tilting angle of the distribution chute with a small investment.

The charging mode described above can be implemented as shown in the embodiments of the present invention described later, and the method of setting the distribution chute tilting angle and the number of turns at each tilting angle to realize this is as follows.
A burden distribution simulation model (for example, iron and steel Vo1.71 (1
985) P175) may be used. Further, the amount of raw materials charged in the radial direction within the furnace can be controlled not only by adjusting the operating method of the distribution chute described above, but also by adjusting the raw material discharge rate from the furnace top bunker.

That is, while the opening of the lower gate valve 8 of the furnace top bunker can be adjusted, a detection end 1) is provided that measures the raw material discharge time using sound or vibration, and the detection end 1) Based on this, the raw material discharge speed can be adjusted by controlling the opening degree of the gate valve during raw material discharge.

(Function) The present invention, when charging iron source raw material containing pellets into a bellless blast furnace, controls the pellet content in the raw material supplied to the distribution chute at a constant rate or over time,
In addition, the tilting angle of the distribution chute is controlled to charge the raw material from the center of the furnace toward the furnace wall, and the tilting angle of the distribution chute is controlled so that the deposition angle on the surface of the raw material after loading into the furnace does not exceed 20 degrees. Since it controls at least one of the angle, the number of rotations at each tilt angle, and the opening of the lower gate valve, it is possible to accurately control the pellet content distribution in the ore layer in the radial direction of the furnace when charging ore. Can be controlled.

(Example) In order to verify the effects of the present invention, a full-scale model of the top of a blast furnace having a bellless charging device was manufactured and an experiment was conducted.

The experiment was conducted using a coke base of 37 tons, an O/C of 4.0, and sintered ore and pellets as ores at a ratio of 9:1. Coke and ore were charged alternately, and when the last ore was charged, the charge was The stock level of the reactor was brought to a level with that of the actual reactor, and all charging was completed. Although this model does not have the effect of unloading the charge and blowing air in the actual reactor, other basic equipment is the same as that of the actual reactor.

■Conventional charging method Charge the raw material from the furnace wall toward the center of the furnace, and operate the distribution chute so that the angle of inclination of the surface of the charged material after charging is approximately 30 degrees (see Table 1 below). (a)) L, when the raw material in the furnace top bunker is shaped as shown in Figure 1) (a), and the insert and centering chute are installed in the furnace top bunker, the sinter and pellets are completely removed. The pellet content in the ore layer in the radial direction inside the furnace was measured using the mixture that was mixed and charged into the furnace top bunker. The results are shown in FIG.

When sintered ore and pellets are completely mixed and charged into the furnace top bunker, the change over time in the pellet content of the raw material discharged from the furnace top bunker is smoothed out, as shown in Figure 9. Although the pellet mixing ratio distribution in the inner radial direction is considerably uniform, the mixing ratio near the furnace center is still low. This occurred due to re-separation of sinter and pellets on the charge slope.

■Method according to the present invention (Part 1) Therefore, the operating method of the distribution chute is changed and the raw material is charged from the center of the furnace toward the furnace wall according to the method of the present invention, and the surface of the charged material after charging is The charging method is such that the angle is 20 degrees or less ((b) in Table 1 below), and the sintered ore and pellets are mixed completely and uniformly and charged into the top bunker through the insert and centering chute. After that, when the material was charged into the furnace, it became uniformly distributed all the way to the center of the furnace, as shown in FIG.

In addition, when charging raw materials into the furnace, the opening degree of the lower gate valve of the top bunker is controlled to suppress the raw material discharge rate from the bunker at the initial stage of raw material charging, and to reduce the number of revolutions at the initial tilt angle of the distribution chute. Similar results were obtained as shown in FIG. 5 even when increasing the number of charges (see Table 2 below).

■Method according to the present invention (Part 2) Next, the timing of cutting out the sintered ore and pellets onto the charging belt conveyor was changed, and raw materials with a high pellet content were loaded into the lower part of the furnace top bunker as shown in Figure 6. On the other hand, the insert position in the furnace top bunker is placed directly above the raw material with a high pellet content ratio, and the insert position in the top bunker is placed directly above the raw material with a high pellet content ratio, and the
), it was confirmed that it was possible to localize the pellets in the center of the furnace, as shown in FIG. 7, by charging the pellets into the furnace using the same distribution chute operation schedule.

Table 1 Table 2 (Effects of the Invention) As explained above, the present invention provides a method for controlling the pellet content in the raw material supplied to the distribution chute when charging the iron source raw material containing pellets into a bellless blast furnace. is controlled at a constant rate or over time, and the tilting angle of the distribution chute is controlled to charge the raw material from the center of the furnace toward the furnace wall, and the deposition angle on the surface of the raw material after charging into the furnace is 20 degrees. The system 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 ore layer in the radial direction inside the furnace is not exceeded. The pellet content distribution within the blast furnace can be accurately controlled, which has an extremely large effect on the operation of the blast furnace.

[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 increase in coke layer thickness at the center of the furnace, and Figure 3 is a diagram showing the relationship between the coke layer deposition angle and the ore thickness at the center of the furnace. 4 is a diagram showing the relationship between the tilting angle of the distribution shoe 1- and the motor shaft torque. FIG. 5 is a diagram showing the pellet content distribution in the radial direction in the furnace in the charging method according to the present invention. Figure 6 is a diagram showing an example of raw material charging in the furnace top bunker according to the present invention, Figure 7 is a diagram of the pellet content distribution in the radial direction inside the furnace in the charging method according to the present invention, and Figure 8 is a diagram showing the distribution of the pellet content in the radial direction in the furnace in the charging method according to the present invention. Figure 9 shows the distribution of pellet content in the radial direction of the furnace;
Fig. 1θ is a schematic diagram of the conventional bellless charging method, and Figs. 1) (a) and (b) are drawings showing the filling state of the conventional pellet-containing raw material in the top bunker. 1 is a blast furnace, 8 is a lower gate valve, 10 is a distribution chute, 1
5 is a sintered ore storage tank, 16 is a pellet storage tank, and 17 is a discharge gate. Patent Applicant: Sumitomo Metal Industries, Ltd. (Figure 1, Figure 6, Figure 7, Figure 7)
Furnace 4 Figure 8 Figure 5 (Outside the furnace - (Furnace 4) Figure 9' - Charging Komata Sakikaku

Claims (1)

[Claims] (1) When charging iron source raw material mixed with pellets into a bellless blast furnace, the pellet content in the raw material supplied to the distribution chute is controlled at a constant rate or over time, and the tilt angle of the distribution chute is controlled. The raw material is charged from the center of the furnace toward the furnace wall, and the tilting angle of the distribution chute and the number of turns at each tilting angle are controlled so that the deposition angle on the surface of the raw material after loading into the furnace does not exceed 20 degrees. , a method for charging a pellet blended raw material into a bellless blast furnace, the method comprising controlling at least one of the opening degree of a lower gate valve.