JPH05179320A - Raw material charging method for bell-less blast furnace - Google Patents

Abstract

PURPOSE:To control the grain size distribution of raw materials in the bell-less blast furnace without work piece in a furnace top bunker. CONSTITUTION:The discharge of the raw materials stored in the furnace top bunker (lower-stage bunker 4) is interrupted >=1 times before the discharge is completed in accordance with the previously determined change in the grain size of the raw materials discharged from the furnace top bunker 4 at the time of charging the raw materials into the furnace 10. The operation schedule of a distributing chute 9 is changed at every discharge and in succession, the raw materials are discharged from the above-mentioned bunker 4 and are charged into the furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a raw material storage tank (hereinafter referred to as "top bunker" or simply "bunker") provided at the top of a blast furnace and a distribution chute for loading the raw material into the blast furnace. A method for charging raw materials in a bellless blast furnace.

[0002]

2. Description of the Related Art In the operation of a blast furnace, it is a basic operational task to control the gas flow distribution in the inner diameter direction of the furnace to stably reduce and dissolve the ore charged in the furnace.

The main means used to control the gas flow distribution in the blast furnace is to control the distribution state of the raw material charged from the top bunker into the furnace, and therefore (a) in the inner diameter direction of the furnace. Deposition weight ratio distribution of ore and coke (hereinafter,
"O / C distribution") and (b) ore, coke, etc. particle size distribution control.

The raw material charging device (bellless charging device) in the bellless blast furnace can be roughly classified into one having a top bunker for directly supplying the raw material into the blast furnace and one having a plurality of bunkers.

FIG. 1 is a view showing the structure of an example of a bellless charging device having two-stage furnace top bunker in series. In this figure, a raw material (ore, sinter, coke, etc.) 1 is conveyed by a belt conveyor 2, first stored in an upper bunker 3 of the furnace top, and then discharged from a lower bunker 4 and then a lower bunker 4 (In the same figure, this is hereinafter referred to as a top bunker). When the charge in the furnace is unloaded and reaches the predetermined stock line 5, the gate valve 6 and the seal valve 7 for adjusting the flow rate of the charge are opened to remove the raw material 8 in the lower bunker 4. The raw material 8 is supplied to the distribution chute 9, the tilt angle θ of the distribution chute 9 is adjusted, and the raw material 8 is charged into the furnace 10.

In this bellless blast furnace, the control of the O / C distribution in the inner diameter direction of the above (a) is performed by operating the distribution chute 9 (specifically, setting the distribution chute tilt angle and turning at that tilt angle). Number allocation) and operate the distribution chute 9 accordingly. That is, when the raw material 8 in the top bunker 4 is charged into the furnace by the bellless charging device, normally, the distribution chute 9 is swung 10 times or more to charge the raw material into the furnace, and during that time. The charging form is such that the tilt angle of the distribution chute 9 is changed once or more to change the falling position of the raw material in the furnace. At this time, if the particle size of the raw material 8 supplied to the distribution chute 9 changes with time in one dump from the furnace top bunker 4, the effect appears in the particle size distribution in the inner diameter direction of the furnace.

On the other hand, the particle size distribution of the raw material in (b) is controlled by adjusting the change with time of the particle size of the raw material charged into the furnace from the furnace top bunker 4.

There have been many reports that the particle size of the raw material discharged from the furnace top bunker appears to change with time, but the main reason is that the particle size of the raw material in the furnace top bunker is not uniform. It has a particle size distribution in the inner diameter direction of the bunker and that the raw material exhibits so-called funnel flow type flow characteristics when the raw material is discharged from the bottom of the bunker (iron and steel 74 (1988) P.978). .. Among these, as a means for coping with the former factor, for example, a bunker configured by providing a rod-shaped material or a repulsion box (stone box) at the position where the raw material falls and spreading the raw material over a wide range
56-18597), a method in which the time-series particle size pattern of the raw material charged into the furnace is made into a predetermined particle size pattern by adjusting the tilt angle of the swirling chute provided in the furnace top bunker No. 1-1119612), or
In the bunker, there is a method of changing the particle size change pattern of the charge discharged from the furnace top bunker by adjusting the position of the adjusting plate, etc. in the bunker. A technique has been proposed in which the deposition state of the raw material is controlled, and thereby the particle size distribution of the raw material in the furnace is controlled. As a means to deal with the latter factor, a work is installed just above the discharge port in the bunker to prevent the flow characteristics of the raw material discharged from the bottom of the bunker from exhibiting a funnel flow type. It has been known.

[0009]

These means adjust the particle size distribution in the radial direction of the raw material in the furnace top bunker,
Alternatively, it is intended to control the particle size distribution of the raw material in the furnace by changing the flow of the raw material at the time of discharging from the bunker, but in both cases, a workpiece is provided in the bunker and it is controlled. Therefore, there is a problem in maintenance of the equipment.

Further, when it is desired to change the particle size distribution of the raw material in the furnace in order to adjust the gas flow distribution in the furnace, or the properties of the charged raw material (for example, particle size composition, sinter ore ratio, pellet ratio, etc.). When the raw material deposition behavior in the bunker changes with changes in the raw material composition of the bunker and the pattern of the temporal change in the particle size of the raw material discharged from the bunker changes, but this pattern needs to be corrected. However, it is necessary to adjust the position and angle of the work in the bunker, but in any case, it is not easy to make appropriate adjustments promptly.

As described above, the present invention provides a raw material charging method in a bellless blast furnace capable of controlling the particle size distribution of raw material in the furnace without installing a workpiece in the furnace top bunker. With the goal.

[0012]

The gist of the present invention is to be stored in a bunker top bunker of a blast furnace having a bellless charging device (the bottom bunker in a multistage bunker as shown in FIG. 1). When charging the raw material into the furnace, based on the time-dependent change of the particle size of the raw material discharged from the bunker measured in advance, interrupt the discharge once or more until the discharge of the raw material is completed, The raw material charging method in the bellless blast furnace is characterized in that the operation schedule of the distribution chute is changed each time and the raw material is continuously discharged from the bunker.

The change over time in the particle size of the raw material discharged from the bunker is determined by, for example, inserting a belt conveyor type sampler directly below the outlet of the distribution chute from the furnace mouth manhole to continuously discharge the raw material discharged from the distribution chute. The measurement can be performed by using a method such as sampling into.

[0014]

The function and effect of the method of the present invention, that is, the reason why the particle size distribution of the raw material in the radial direction of the furnace can be controlled by applying the method of the present invention will be described below.

As described above, the raw materials discharged from the furnace top bunker generally show a change in particle size over time. Figure 2
In a blast furnace (a blast furnace called A blast furnace, 5000 m ³ in volume) with an in-line two-stage top bunker type bellless charging device, the raw material (sintered ore) charged into the furnace is sampled at regular intervals,
It is a figure which shows the result of having investigated the time-dependent change of the particle size.

The horizontal axis in FIG. 2 is the relative time with 1.0 from the start to the end of charging the raw material into the furnace, and the vertical axis is the particle size of the raw material at each charging time and the average particle size of all raw materials. Relative grain size divided by, expressed as a dimensionless number. As shown in this figure, the particle size of the raw material charged into the furnace generally changes with time, but when such a raw material is charged into the furnace, the particle size in the radial direction of the furnace In order to control the diameter distribution, the tilt angle of the distribution chute may be controlled so that the raw material falls to a desired deposition position according to the particle diameter of the raw material at each charging time. However, in reality, there is an upper limit to the tilting speed of the distribution chute, and it is impossible to quickly move to the desired angle. In addition, since the tilting direction of the distribution chute is limited to one direction (that is, the direction in which the tilting angle is gradually decreased or increased), it is difficult to perform such control.

In this case, if the method of the present invention is applied and the charging of the raw material is interrupted midway, the operation mode of the distribution chute is changed during that time, and the charging is continued, if the method of charging the raw material is adopted, it depends on the particle size of the raw material. The raw material can be dropped to a desired deposition position. That is, the particle size of the raw material charged into the furnace is
For example, in the case of showing a change over time such as period 1 in FIG. 2, if coarse particles are to be concentratedly deposited in the central portion of the furnace and fine particles are concentrated on the furnace wall side, first, the tilt angle of the distribution chute (in FIG. θ) is set to a small value, and after charging coarse-grain raw material corresponding to 36% of the total raw material (range of 0 to 0.36 on the horizontal axis of FIG. 2) near the center of the furnace,
Close the outlet of the top bunker to interrupt charging, then increase the tilt angle of the distribution chute to drop the remaining raw material in the top bunker, that is, the fine-grained raw material, to the furnace wall side. Good. The charging of the raw material is not limited to once, but may be performed twice or more depending on the change over time of the particle size of the raw material discharged from the bunker, and the inclination angle of the distribution chute may be adjusted each time.

As described above, according to the method of the present invention, the bunker can be moved from the bunker to the inside of the furnace without taking measures such as installing a workpiece in the bunker at the top of the furnace to control the deposition state of the raw material in the bunker. It is possible to freely control the particle size distribution of the charged raw materials.

In the method of the present invention, one time charging of the raw material from the furnace top bunker is made into a plurality of divided chargings, and the operation schedule of the distribution chute is newly set at each divided charging, so that the radial direction in the furnace is increased. Although it is intended to control the particle size distribution, this effect cannot be obtained by a method of increasing the so-called "charge batch number", which is performed by dividing the single charge of the raw material into the furnace. The reason for this is that the change over time in the particle size shown in Fig. 2 is caused by the particle size segregation in the furnace top bunker and the funnel flow at the time of discharging the raw materials, so even if the number of charging batches is increased, The change over time in the particle size of the powder appears only as shown in FIG. 2, and the particle size distribution in the radial direction of the furnace cannot be controlled. Furthermore, in this method, since a uniform discharge pressure operation accompanying receipt and delivery of the raw material to the bunker is included in each batch, the margin of the charging time is significantly reduced, whereas in the method of the present invention, such an operation is performed. There is no need to sacrifice a lot of spare time.

The applicant of the present invention has proposed a charging method in Japanese Patent Laid-Open No. 57-207104, in which the operation of interrupting the discharge of the raw material is one of the constituent requirements. The method is as follows. The amount of deposition is controlled, and the timing of interrupting and resuming the discharge of the raw material from the furnace top bunker is determined based on the turning direction of the distribution chute. Different from the method.

[0021]

[Example] A charging experiment of raw materials was carried out using a 1/20 scale model of the blast furnace A, and the deposited raw materials after completion of the charging were sampled to obtain a particle size distribution in the inner diameter direction of the furnace, and an O / C distribution was obtained. Was measured.

Table 1 shows the dimensions of the main part of the model used and the charging conditions of the raw materials, and Table 2 shows the operation schedule of the distribution chute used in the charging experiment. In Table 2, the term "base" refers to the case where 1750 kg of sinter is charged while the distribution chute is turned 14 times without interruption after starting the charging of the raw material (sinter). 62 during 5 turns
After charging 5 kg of sinter, the operation was interrupted, the tilt angle of the distribution chute was adjusted, and then the distribution chute was rotated 8 times again.
When 25 kg of sinter is charged, Case 2 is a case where the charging is interrupted and the distribution chute is adjusted twice, and 438 kg of sinter is charged during the first four turns of the distribution chute. Then, after adjusting the tilt angle of the distribution chute, the same amount of 438 kg of sinter was charged while the distribution chute was turned 4 times, and finally 874 kg of sinter was charged while the distribution chute was turned 7 times. Is. In each case, 440 kg of coke was initially charged during 14 turns of the distribution chute, and then sinter was charged as described above. The numbers in parentheses in the table are the tilt notches (tilt angle index) of the distribution chute.
The higher the number, that is, the higher the tilt notch, the more the falling position of the charge in the furnace shifts toward the center of the furnace. In this experiment,
Fig. 2 shows the change over time in the particle size when the raw material (sintered ore) is placed inside the furnace.
In order to obtain the pattern (period 1 or period 2) shown in FIG.
2) was filled, and the raw material was charged by connecting the discharge port of this hopper to the distribution chute inlet when charging into the furnace.

The experimental results are shown in FIGS. 3 and 4. In FIG. 3, the vertical axis represents the same dimensionless granularity as the vertical axis in FIG. The symbol Δ in the figure is a conventional example, and is the case where the ore having the grain size showing the change with time in the period 1 of FIG. 2 is used and the furnace interior is filled under the base conditions of Table 2 (internal distribution method). ● indicates the example of the present invention
For the purpose of depositing coarse (large grain size) sinter in the center of the furnace, the sinter having a grain size showing a change with time in period 1 of FIG. 2 was heated under the conditions shown in Case 1 of Table 2. In the first half of discharge, the coarse-grained sinter discharged from the bunker was operated by the distribution chute with the high tilt notch to drop it into the center of the furnace, and then the charge was interrupted. In this case, the post-charge was changed to the low tilt notch and the fine charge discharged in the latter half of the charge was dropped to the furnace wall side after restarting the charge. Further, the symbol ◯ is also an example of the present invention, and for the same purpose as in the case of the symbol ●, a sinter having a particle size showing a change with time during the period 2 in FIG. 2 is installed in the furnace under the conditions shown in Case 2 of Table 2. That is the case.

From the results shown in FIG. 3, the particle size of the sintered ore deposited in the center of the furnace is
It can be seen that it has increased compared to the case of using the conventional charging method.

FIG. 4 is a diagram showing the O / C distribution in the inner diameter direction of the furnace, which is almost the same as that of the conventional example in both the present invention example and. That is, according to the method of the present invention, the particle size distribution in the furnace inner diameter direction can be controlled without changing the O / C distribution.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

When the method of the present invention is applied to charging a raw material into a blast furnace having a bellless charging device, the particle size distribution of the raw material in the furnace can be controlled without installing a workpiece in the furnace bunker. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an example of a bellless charging device having a two-stage furnace top bunker in series.

FIG. 2 is a diagram showing an example of changes over time in the particle size of the raw material (sintered ore) charged into the furnace from the furnace top bunker.

FIG. 3 is a diagram showing a particle size distribution of the raw material deposited at each position in the furnace inner diameter direction when the method of the present invention is applied.

FIG. 4 is a diagram showing the O / C distribution of the raw material deposited at each position in the furnace inner diameter direction when the method of the present invention is applied.

Claims (1)

[Claims] 1. When charging a raw material stored in a raw material storage tank of a blast furnace having a bellless charging device into the furnace, based on a temporal change in particle diameter of the raw material discharged from the storage tank, which is measured in advance, A method for charging a raw material in a bellless blast furnace, which comprises interrupting the discharge once or more until the discharge of the raw material is completed, changing the operation schedule of the distribution chute each time, and continuously discharging the raw material from the storage tank.