JPS63145704A - Charging method for raw material in blast furnace - Google Patents

Abstract

PURPOSE:To suitably maintain the permeability distribution of charging material and the temp. distribution in a furnace to be desirable to the furnace condition, etc., by adjusting layer thickness distribution and grain size distribution of ore and coke (charging material) in the dividing charging method only by changing the position of movable armor. CONSTITUTION:In the case of two divided charging of the ore, by changing the position of movable armor, the top position of the first charging ore O1 is charged from RO1 to R'O1 and in accordance with this, the layer thickness is changed, but the layer thickness as the total ore layer 1 is not changed, in case the sum of charging ore quantities O1 and O3 at first and second times is fixed. And, the layer thickness of ore layer 1 is fixed only by the surface shape of coke layer 2 at the lower stage and the surface shape of ore O2 layer, and therefore, the layer thickness distribution of charging material is adjusted by adjusting the above arm position at the time of charging the coke in accordance with the shape of the upper face of ore layer 1. Further, by changing the surface shape of ore O1 layer just before charging of ore O2 mixing fine grain, the grain distribution of charging material is adjusted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention maintains the permeability distribution of the charge and the temperature distribution within the furnace that are desirable for the furnace conditions and the furnace body in bell-movable-armor blast furnace operation. The purpose of this invention is to adjust the layer thickness distribution and particle size distribution of a charge.

[Conventional technology]

1-: Controlling the layer thickness 4i and particle size distribution (hereinafter collectively referred to as charge IH5) of ore/coke at the top of the furnace to an appropriate II: during I furnace operation is the Controls the waste flow, the furnace temperature IHj and the five-dimensional reaction progress,
Furthermore, it is important to appropriately control the shape of the melt 71''+L'.

In the bell/movable armor type blast furnace, unlike the bellless rotary chute type blast furnace, the charge cannot be deposited in small amounts at the position 91, so the charge amount/14
has been considered difficult to control.

In 2015, in order to increase the degree of freedom in controlling the burden distribution using the bell/movable armor type, the charge, especially the ore, was divided into two or more times, and the charging + and H damage rates for each charge were adjusted. A method has been developed to control the charge distribution by varying the stratification in the furnace.

For example, in JP-A-57-134502, by adjusting the ore t of 1-1 at a time, the coke j11 that is swept toward the center of the furnace is controlled, and the thickness of the mixed layer with good air permeability formed near the center of the furnace is controlled. is under control. In addition, in Japanese Patent Publication No. 59-10403, the ore particle size charged in I was changed twice [1 time to reduce the particle size to be smaller than that in 1. We have developed a new loading method to improve ventilation throughout the furnace.

However, in the split charging method described above, the permeability of the charge distribution near the furnace wall, which most strongly controls the gas flow in the furnace, is determined by
1- could not be controlled.

[Problem that the invention seeks to solve]

For this reason, for example, when a large amount of fine-grain raw material is used, there has been no effective quantitative method for controlling the air permeability of the entire furnace, including the vicinity of the furnace wall, to an appropriate level of +IE.

An object of the present invention is to provide a method for accurately controlling the distribution of contents in the furnace including the vicinity of the furnace wall in the split charging method, which was not possible with the conventional methods described above. This method is carried out only by the most convenient means of movable armor, which is easy to operate in blast furnace operation.

[Failure to solve the problem]

The present invention provides a blast furnace raw material charging method in which ore is divided into two layers with different particle sizes and /li and stratified in a furnace, and MII grain ore is layered in layers other than the bottom layer. (1) Coke charging By adjusting the movable armor position at the time of loading according to the shape of the ore layer 14 surface, the layer thickness distribution of the charge is adjusted, By changing the shape, the particle size of the charge can be reduced by 1
He is a person who charges raw materials into a blast furnace, whose characteristic technical means is to adjust 1j.

(f'I II+) There are several means to control the charge distribution, such as adjusting the ore splitting ratio, bell opening degree, bell opening speed, or raw material particle size, but the most constant method with the greatest degree of freedom is movable armor. This is a change in position.

First, we will discuss the results of various studies on the case of two-part ore charging. 2 minutes in an operating blast furnace; l1
The movable armor position in the 1st ore charging and coke charging during the second ore charging is as follows: The layer thickness distribution of ore and coke was determined using an electrode type layer thickness meter when the movable armor position index NO was varied from 2 to 6. Its layer thickness fraction 20/
(sentence o+9.c) is shown in Table 1, and the resulting N
(or Not and no/(Jlo +lc) are shown in FIGS. 3 and 4.

From these results, it was found that the charge layer thickness distribution depends only on the movable armor position index Nc at the time of coke charging, and does not depend on the movable armor position index Not at the time of ore charging. . Therefore, it has become clear that by changing only the movable armor position index Nc during coke charging, it is possible to improve the charge layer thickness distribution.

Table 1 (liυ at Z, - bubble armor (when the q-position index is large,
The charge is charged closer to the center of the furnace.

Each measurement image 1 is obtained by averaging 6 to 8 measurement results 1 by f.

The above-mentioned phenomenon is based on Ito's charge distribution control mechanism.

Movable armor position index (No+, NO2, Nc)
= When changing from (502) to (302), the position of the top of the first ore layer changes from Rot to R'01 as shown in Figure 1, and the layer thickness also changes accordingly. , the thickness of the ore layer as a whole does not change if the sum of the first saw and the second ore amount is constant, and the surface shape of the lower coke layer (i.e., the ore on top of it) It is determined only by the bottom surface shape of the layer) and the surface shape of the ore layer charged the second time. If the movable armor position NO2 at the time of second ore charging is fixed to the furnace wall, it can be seen from FIG. 1 that the ore layer thickness is determined only by the movable armor position index NO at the time of coke charging.

As shown in FIG. 2, the ore layer thickness distribution was almost the same at movable armor positions (302) and (502) even when layer thickness was measured in an actual furnace. On the other hand, when the movable armor position was changed from (302) to (304), the ore layer thickness fraction decreased from the furnace center to the middle of the furnace, and conversely increased near the furnace wall.

By the way, in Fig. 2, in both cases where Nc is 2.4, furnace 1;? In the vicinity, the thickness of the ore layer increases rapidly. Such a layer thickness 41 suppresses heat loss from the furnace wall and protects the furnace wall.
: Convenient when going to However, as the ore layer Jj increases near the furnace wall, the so-called furnace wall becomes inert.
Slips may occur frequently. To prevent this, the air permeability of the furnace wall is usually ensured by controlling the particle size distribution as described below, but even with this effect, the air permeability of the furnace wall may not be maintained at a high level. In this case, it is preferable to increase the movable armor position 'jIINo2 at the time of second ore charging.

(Assuming the semi-movable armor position is (302),
Figure 5 shows the changes in the ore layer thickness 4i when NO2 is varied from O to O. When NO2 is larger than NO, 20/(AC0+vertical C) at the furnace wall decreases, and the air permeability decreases. becomes much better. With such a charge distribution, the heat load on the furnace wall becomes high, and the gas flow rate near the center of the furnace decreases, resulting in a decrease in temperature. An appropriate NO2 value may be determined from normal operation results.

Next is the movable armor position at the time of first ore charging, index N.
The influence of ot on the charge distribution was investigated. As mentioned above, PJot has little effect on the charge layer thickness distribution, but as can be seen from Fig. 1, it controls the radial distribution of the ore layer charged in 1 and 2 [1]. For this reason,
If the ore charged for the second time is mixed with fine raw materials, the more Not increases, the more ore is charged near the furnace wall, and the ore particle size near the furnace wall decreases. do.

To confirm this, first, in an operating blast furnace, the radial distribution of particle size on the surface of each charge was measured using an optical fiber granulometer. The results are shown in FIG.

It can be seen that the grain size of the ore charged the second time is smaller than that of the ore layer charged the first time. However, since the amount of ore charged for the second time is smaller than that for the first time, less amount of ore flows to the center of the furnace, resulting in a greater degree of grain size segregation.
Near the center of the furnace, the grain size of the ore layer charged the second time became thicker.

Based on this result, L −/< pull armor position is (302
) and (502), the particle size distribution of the entire ore layer was determined by considering the thickness molecule 1+ of the ore layer charged once in 11 and 211I 11. The results are shown in Figure 7*
It was found that when Not was increased to 3 to 5, the difference in grain size of the ore layer in the vicinity of the furnace wall was reduced by about 2 to 3 mm, and the air permeability was reduced.

As mentioned above, minute; l; 21r + l in the 1 person method 11
When the movable armor position NO2 at the time of charging the ore layer is fixed, the grain size 4j of the ore layer can be controlled by the movable armor position Not at the time of the first ore charging.

We have previously clarified the effects of movable armor positions Not, NO2, and Nc on the charge distribution, but to summarize this, (1) Movable armor position 11/
By adjusting 1 according to the shape of the surface of the ore layer, the layer thickness 41 of the charge can be adjusted, and (2) I
By changing the surface shape of the ore layer immediately before the ore layer in which 11-grain ore is mixed, the particle size of the charge 1 (i) can be adjusted.

゛In actual furnace operation, first select an appropriate combination of NO2 and NO based on past operating results. In this state, Not is changed to finely control the air permeability distribution.

If it cannot be controlled with Not, change NC. If it still cannot be controlled, select a new combination of NO2 and NQ.

However, in the charging shed II control method described above, the top surface of the ore layer is determined only by the movable armor position at the time of final ore charging, and does not change depending on the movable armor position at the time of other ore charging. It is a premise.

For this, the final ore layer must completely cover the previous ore layer. For example, if Not is excessively increased, a situation occurs in which the ore layer of twice [1 is deposited only in the pocket between the surface of the ore charged the first time and the furnace wall, and does not reach the center of the furnace. In this case, in the region between the furnace center and the middle of the furnace, the first ore surface becomes the ore top surface, and the ore top surface also changes due to NOI. This logic also applies to the case of dividing ore into three parts, which will be described later.

Then divide the ore into 1-3 times or more; 1. As shown in FIG. 1O, as six examples of controlling the charge layer 1'/and the grain size 71 when ore is charged as 0, . 0
2.034.13 divided, twice 1.1 (7) Ore layer 0
2, consider the case where I11 grain original $1 is used. In order to charge the fine raw materials as close to the furnace wall as possible, the position of the movable armor during the second ore charging is as close to the furnace wall as possible.

The thickness distribution of both the ore and coke layers depends on the coke surface shape,
Since it is determined by the surface shape (coke back surface shape) of the ore 03 charged last, the layer thickness distribution can be controlled by adjusting the position of each movable armor.

On the other hand, the distribution of the 1,411-grain raw material 02 is determined by the surface shape of the ore 01 layer immediately before it, so the distribution of the 1-1 ('
) It is possible to control the particle size distribution of the charge by adjusting the position of the movable armor when charging stone 01.

〔Example〕

Conventionally, in the method of dividing and charging raw materials for blast furnaces as described below, once [1] Regarding the movable armor position index Not at the time of ore charging, ? ' Based on the idea that the ore layer near the furnace wall decreases as Jot increases,
Although we have been controlling the ore layer thickness using ot, NO in Figure 8
As seen in the changing period, that is, from time point A to time point B, the furnace wall heat load did not change much even if the NOI was changed, and the direction of change was also in the opposite direction.

Therefore, from point B, layer thickness was controlled by changing the coke mover position index NC based on the concept of the present invention. In the NQ variation change (from time point B to time point B), when Nc is gradually changed from 2 to 5, the furnace heat load decreases. However, when Nc is 4 or more, the number of slips increases.

Therefore, by fixing Nc to 4 and lowering Not to 5 to 2 from point B, it was possible to reduce the number of slips without significantly increasing the furnace wall heat load (No from point C to point D! Change period ). Is this Furnace 1~? M+1 grain b in the vicinity
This is because the mouth ratio was lower and the air permeability was reduced by a few yen.

During these periods, the temperature distribution near the furnace wall was measured using a 1111 temperature sonde using a thermocouple.

The results are shown in FIG. Curves A, B, C in Figure 9,
D corresponds to time points A, B, C, and D in FIG. 8, respectively. Even when NO was changed, the temperature inside the furnace hardly changed as seen in curves 1 and 8, but when NO was increased, the temperature inside the furnace decreased as shown in curve C and became inactive. After that, when the particle size distribution was controlled using NOI, the heat load was slightly recovered as shown by the 0 curve.

〔Effect of the invention〕

When charging raw materials into a blast furnace in parts, the control of the charge layer thickness and grain size IHi, which was not clear in the past, can be achieved by simply changing the position of the movable armor; the purpose is to control the viscosity well. In addition, the particle size fraction 4j and the layer thickness fraction 4j can be changed independently, and the effects of both on the blast furnace furnace conditions can now be clearly seen.

As described above, the present invention provides control of the charge amount in the split charging method, as well as temperature distribution and fusion within the furnace. It is extremely useful for fine-grained shape control, and has greatly contributed to the advancement of split charging technology.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of the top of the blast furnace showing the charge accumulation situation in split charging, Figure 2 is a graph showing the calculation results of ore layer thickness distribution in split charging, and Figure 3 is during coke charging. Figure 4 is a graph showing the influence of the movable armor index position on the ore layer thickness distribution during the first ore charging, Figure 5 is a graph showing the influence of the movable armor index position on the ore layer thickness distribution during the first ore charging. A graph showing the influence of the movable armor position index on the ore charging surface of [I] on the ore layer thickness distribution, Figure 6 shows the measurement results of the burden particle size distribution (based on surface observation)
Figure 7 is a graph showing the influence of the movable armor position index on the ore particle size distribution during the first ore charging, Figure 8 is a chart showing the operational trend during split charging, and Figure 9 is a graph showing the influence of the movable armor position index on the ore particle size distribution during the first ore charging. Furnace Will temperature results full result graph, 10th
The figure shows ore 3 minutes; charge amount 1 (i
It is a schematic sectional view of the charge of the blast furnace furnace lq part explaining control II. l...Ore layer 2...Coke layer 01...11i■l 11 charging ore 02...21
11111 charged ore 03...3 times 11 charged ore discharged, applicant Kawasaki Steel Corporation

Claims (1)

[Claims] 1 In a blast furnace raw material charging method in which ore is divided into two or more layers with different particle size distributions and stratified in a furnace, and fine-grained ore is stacked in layers other than the bottom layer, the movable armor position during coke charging is set to the top surface of the ore layer. The layer thickness distribution of the charge is adjusted by adjusting it according to the shape of the charge, and the particle size distribution of the charge is adjusted by changing the surface shape of the ore layer immediately before the ore layer in which fine-grained ore is mixed. A method for charging raw materials into a blast furnace characterized by the following.