JPH0627283B2 - Method of charging raw material into blast furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to a raw material charging method capable of contributing to stabilization and efficiency of blast furnace operation, and more specifically, a so-called coke shaft core device developed by the applicant. This is related to the improvement of the insertion (or central charging) technology.

[Prior Art] Many factors have various influences on the operation of a blast furnace, which are complicatedly intertwined from various directions. Therefore, for the diagnosis of the furnace condition regarding the blast furnace in operation, item-wise evaluation by individual approaches from various angles and their weighting,
Furthermore, evaluations from a comprehensive perspective are being conducted.

The Applicant has been conducting research on stabilization and efficiency improvement of blast furnace operation for a long time, and in particular, a method for increasing the coke ratio in the blast furnace shaft center part, or a shaft center charging coke and / or shaft center charging. The technology of weakening the gas flow resistance of the blast furnace shaft center by the method of selecting and inputting high-grade ore as the ore, and improving the so-called central flow operation stabilization or reliability, that is, the above-mentioned coke shaft core charging technology It has been established (see, for example, JP-A 64-65207 to 65213 and 65215 to 65219).

On the other hand, in the blast furnace operation, various studies have been conducted in the direction of so-called low coke operation in which the coke ratio in the blast furnace charging raw material is reduced from the viewpoint of economy. However, when low coke ratio operation is performed, the ore ratio is relatively improved, and the ore layer generally has high gas flow resistance,
As the pressure loss in the blast furnace operation increases, the solution loss reaction of coke in the blast furnace shaft increases, and the coke deteriorated by the solution loss reaction enters the core (bottom of the blast furnace) and lowers the air permeability of the blast furnace. There was a problem that was very unstable.

What was proposed here is the coke shaft core charging technology, in which the solution loss reaction in the shaft center portion is suppressed, and the above problems are greatly improved, and the realization of low coke ratio operation is promoted at once. Became.

[Problems to be Solved by the Invention] However, the above-mentioned coke shaft center charging technique is merely a technique for improving the charging profile in the blast furnace shaft center part, and the furnace is used from the middle part in the blast furnace radial direction other than the shaft center part. It does not improve the charging profile over the wall. Although some research results have been published so far regarding the charging profile in the middle to furnace wall, the above-mentioned coke shaft center charging technology is completed and low coke ratio operation is carried out. Then, it has been found that the above-mentioned charge profile in the middle to the furnace wall has a considerably important role in the operation of the blast furnace.

That is, as the ratio of coke to ore decreases, the ore layer becomes thicker and the coke layer becomes thinner as a whole in the raw material deposition situation in the blast furnace. As a result, the pressure loss in the middle to furnace wall increases more than expected, or as a result, a slight change in the layer thickness ratio between the ore layer and the coke layer in the middle to furnace wall causes a rising gas flow in the blast furnace. However, there was a possibility that the furnace condition was unstable, or the upflow on the furnace wall side increased and the amount of heat loss from the furnace wall increased.

Therefore, as shown in FIG. 2, the inventors of the present invention configure the shaft center portion with the shaft center charging coke 1 by charging the coke shaft core, and when forming the coke layer, the coke layer thickness 3a in the vicinity of the furnace wall portion is used. A coke layer 3 having a particularly thin thickness was formed, and a charging profile for forming an ore layer 4 thereon was devised. As a means to make such a profile,
For example, in the case of the bell system, a method of controlling the falling position of the coke by changing the advancing amount and / or the angle of the armor blade, or in the case of the bellless system, adjusting the turning schedule of the turning chute is exemplified. In any case, with such a profile, the ore layer 4a on the furnace wall side
Becomes thicker, and the ore / coke ratio (hereinafter O /
As a result, the pressure loss with respect to the ascending gas flow increases and the concentration of the ascending gas flow on the furnace wall is suppressed, so that the amount of heat dissipation from the furnace wall is reduced.

However, the coke layer 3 in the above-mentioned profile inevitably has a mountain-like shape having the peak 2, and the O / C at the peak 2 portion becomes very small, where the pressure loss of the ascending gas is low and the ascending gas blows through. Increase the risk of causing. That is, there is a problem that instability of the furnace condition due to gas blow-through and instability of the shape of the softened cohesive zone due to insufficient reduction reaction in the blow-through portion occur.
In addition, allowing such blow-through at a position close to the furnace wall side has a negative effect on the central flow due to the coke shaft center charging, so that the effect of the coke shaft center charging operation is nullified. There is even a case.

Further, since the angle of repose of coke is larger than that of ore, it is inevitable that the coke layer 3b in the vicinity of the axial charging course 1 becomes thin as shown in FIG. When low coke operation is carried out in such a situation, the coke layer in this portion becomes thinner, and the ratio between the coke thickness of the axially charged coke 1 and the coke thickness of the coke layer 3b in the vicinity thereof becomes sharp. Changing, coke layer 3
There is a case where the pressure loss in the portion b increases to a maximum value and the gas that has risen to that portion is distributed to the axial center side and the centrifugal side, and the effect of the coke shaft core charging technology cannot be stably exhibited. . Therefore, there is a problem that the amount of coke charged in the shaft center must be increased, or the range of the shaft center must be widened to devise the charging profile.

The present invention has been made by paying attention to such a situation, and surely exhibits the effect of performing the coke shaft center charging operation to form a stable central flow, and at the same time, improves the O / C of the furnace wall. It is possible to continue the low coke ratio operation while maintaining a stable furnace condition by preventing gas blow-through at a position closer to the center than the furnace wall side while suppressing the increase of the gas flow to the furnace wall side by increasing it. The purpose is to establish such raw material charging technology.

[Means for Solving the Problems] The method of the present invention which has been able to solve the above-mentioned problems includes coke shaft center charging means for intensively charging coke into the shaft center part of a blast furnace, and coke and ore of the blast furnace. In a method of charging coke and ore into a blast furnace having a peripheral charging means for charging to the peripheral side, in the method of increasing the coke ratio of the blast furnace axial center by the coke axial center charging means, the peripheral charging is performed. 0.02 R to 0.6 R from the furnace wall by means of injection
(Where R is the radius of the blast furnace), for a coke layer charged in a mountain shape so as to have a peak height, the position of the ore charged at least at the initial stage of the ore charging is set to the peripheral charging. By setting it to the centrifugal side from the peak position by means, it is a gist that it is configured to collapse the highland portion including at least the peak portion of the mountain-like charging coke layer and to flow toward the blast furnace shaft side. is there.

[Operation] FIGS. 1 (A) and 1 (B) are explanatory views showing the main part of the raw material charging procedure according to the present invention. At the stage of FIG. 1 (A), the shaft center part is the same as in FIG. Is formed by the axially charged coke 1 and a coke layer 3 having a thin coke layer thickness 3a in the vicinity of the furnace wall is formed. Therefore, the coke layer 3 at this point has a mountain-like shape having the peak 2 as described in the case of FIG. 2 (hereinafter also referred to as the mountain-shaped coke layer 3), and the axially charged coke 1
The outer coke layer 3b adjacent to is also minimally thinned to cause the above-mentioned various inconveniences.

Therefore, in the present invention, as shown by the arrow in FIG. 1 (A), the ore drop position of the next charge, more accurately, the ore charged at least at the initial stage of the next charge ore (for example, Bell type The first if the ore is charged in two or more times by charging.
In the case of double-charging ore and bellless type charging, when the charging is started from the furnace wall side using a swirling chute, the dropping position of the charging start ore) is set to the centrifugal side with respect to the peak 2 position. The coke filling portion Q is formed by breaking down the coke in the P portion (the highland portion including at least the mountain peak portion, hereinafter simply referred to as the highland portion) shown in FIG. 1 (B) and pouring it into the surface layer portion of the coke layer 3b. .

According to this structure, since the peak 2 disappears in the plateau part T after the highland part P is removed, the ore layer above it becomes sufficiently thick, and the gas escape at this part In addition, the coke layer thickness of the coke filling portion Q is increased, the coke layer thickness of the coke layer 3 is made uniform, and the axially charged coke 1 maintains the profile as designed in advance. Exert its action. That is, the gas rising in the blast furnace is concentrated in the axial center portion without being blown from the peripheral portion while suppressing the inflow to the furnace wall portion side, and a very stable central flow operation is performed.

The coke charging according to the present invention is carried out by properly using two means of the coke shaft center charging means and the coke peripheral charging means as understood from the above description, but there is no limitation on the mechanical constitution of each means itself. There is no. However, to exemplify a typical one, the former uses a chute for loading the shaft center portion, the latter uses a bell or a swing chute, and further independently of the bell and the swing chute. In particular, the one using a special chute for carrying out the present invention, which is directed in the direction of the arrow in FIG. 1 (A), is exemplified.

The amount of the axially charged coke and the charging radius are not particularly limited, but in general, they may be as disclosed in the above-mentioned publication.

The peak position of the mountain-shaped coke layer charged by the coke peripheral charging means is 0.02 R to 0.6 R from the furnace wall.
(However, R is the radius of the blast furnace) is recommended. 0.02R
When the length is shorter, the coke layer 3a on the furnace wall side shown in FIG.
Is relatively thick, the ore layer 4a on the furnace wall side becomes relatively thin, the gas resistance on the furnace wall side becomes small, and a part of the rising gas flow is unevenly distributed to the furnace wall side, and the heat dissipation amount is increased. growing.
On the other hand, if it is longer than 0.6 R, the intention of the present invention that the coke in the highland portion P is destroyed to form the coke filling portion Q and the layer thickness of the coke layer 3 is made as uniform as possible is not sufficiently exerted. When the coke layer 3 is formed by the level charging means, for example, the charging means is divided into two or more, and the control means for adjusting the peak position by operating the armor plate is adopted.

The present invention is carried out by setting the ore charging position, which is charged at least in the initial stage, in the mountain-shaped coke layer thus formed, to the centrifugal side from the peak position. This position influences the amount of coke flowing in the axial direction of the blast furnace by breaking up the highland portion P including the peak, in other words, the amount of coke in the coke filling portion Q.

Then, various studies were conducted on the relationship between the set position and the amount of course, and the following results were obtained. FIG. 3 shows the profile of the mountain-like coke layer 3, where L is the distance from the furnace wall at the peak position (corresponding to 0.02R to 0.6R above),
Indicates the distance from the peak position of the ore input point. FIG. 4 is a graph showing the amount of coke flowed in when variously changed, the experimental equipment is a blast furnace top simulation device (L = 1000 mm) that can be observed from the outside, and the coke amount is equivalent to 15 t as the experimental condition ( It means that if it is the entire circumference, it corresponds to 15t, and the same shall apply hereinafter). Experiments show that the amount of coke flowed in is determined by the energy given in the initial stage of charging regardless of the amount of ore charged, and if the charging position is set between = 0 and 500 mm, the flow of coke will be substantial. Was approved. A range of 50 to 450 mm is preferable, and a range of 100 to 400 mm is more preferable. If the thickness is 0 mm or less, the coke does not collapse easily, and if it exceeds 500 mm, the ore begins to be stored from the valley portion on the furnace wall side and fills it, so it is impossible to break the peak even if the ore is added after that. There was a strong tendency for the charging profile to be as shown in Fig. 2.

[Examples] FIG. 5 is a diagram of simulation results showing the effect of the present invention, in order from the left, Case (1) without shaft core insertion (comparative example) Case (2) with shaft core insertion (comparative example) (Corresponding to FIG. 2) Case (3) The shaft center charging and the ore charging control of the present invention (the present invention example: corresponding to FIG. 1) are shown. The upper side of each figure shows the O / C distribution seen on the radius side of the blast furnace, and the lower side shows the temperature distribution inside the furnace (the blackened part is the softening cohesive zone). Case (1) shows an example before the coke shaft core charging operation was carried out, and the O / C shows a charging profile in which the shaft center is high and decreases toward the furnace wall side. Very badly W-shaped. In case (2), coke shaft center charging is performed, so the softening cohesive zone has an inverted V shape (more correctly, an inverted U shape). However, the O / C is only low on the shaft center side and high on the furnace wall side, and changes greatly in a wave shape between them, and the O / C on the peripheral side in contact with the shaft center charging coke is increased.
Since C is extremely high, the gas flow, which was expected to concentrate in the axial center part, splits into the surrounding area and the central flow becomes insufficient, and the softening cohesive zone obtained in case (3) becomes Reverse V
Compared to the letter type, it is inferior to autumn. O / in case (3)
C changes gently from the axis center to the furnace wall side, and rises sharply only on the furnace wall side. Therefore, the ascending gas is concentrated in the axial center portion, and as a result of the stable central flow operation being continued, a very remarkable inverted V-shaped softening cohesive zone is formed.

Fig. 6 shows an example of actual operation in the blast furnace, and the horizontal axis shows the progress of the period in units of 10 days. At first, the operation is performed with the profile of the charge equivalent to that in Fig. 2, and the arrow S
At time ₁ , the operation of the present invention was started. As a result about 4 months stability because operation lasted discontinued the application of the present invention at the time of the arrow S _2, it was returned to the operation of Figure 2 corresponds, furnace situation also worsened again. In addition, the vertical axis shows each evaluation item in operation, and when the effect of carrying out the operation of the present invention is described in order from the top, the tap ratio becomes stable at a high position, and the fuel ratio and the coke ratio are very low. Therefore, the number of slips is extremely small despite the decrease in the coke ratio. The pressure loss did not increase so much despite the increase in C / O, and the hot metal temperature was high and stable.

[Advantages of the Invention] Since the present invention is configured as described above, O /
As C decreases, O / C increases on the furnace wall side, and O / C is smoothed in the middle part of the furnace, and the change is gentle, and O / C rapidly increases or decreases along the way. Since there is no such thing, the rising gas in the furnace is concentrated in the axial center part, and stable central flow operation can be continued. As a result, the blast furnace operation became economical with stable furnace conditions.

[Brief description of drawings]

FIGS. 1 (A) and 1 (B) are views for explaining the procedure for carrying out the present invention, and FIG.
The figure is an explanatory view when a mountain-shaped coke layer is formed without applying the present invention, FIG. 3 is an explanatory view showing a main part of the mountain-shaped coke layer, and FIG. 4 is an ore charging position and a coke layer highland part. Fig. 5 is a graph showing the relationship of the collapse amount of Fig. 5, Fig. 5 is a simulation diagram, and Fig. 6 is a diagram showing changes in furnace conditions in actual operation. 1 ... Shaft-loaded coke, 2 ... Peak, 3 ... Mountain coke layer

Claims (1)

[Claims] Claim: What is claimed is: 1. A blast furnace comprising: a coke shaft center charging means for intensively charging coke into the blast furnace shaft center portion; and a peripheral charging means for charging coke and ore to the peripheral portion side of the blast furnace, In the method of charging coke and ore, while increasing the coke ratio of the blast furnace shaft center portion by the coke shaft center charging means, the peripheral wall charging means removes the coke from the furnace wall.
For the coke layer charged in a mountain shape so as to have a peak height at a position of 0.02R to 0.6R (where R is the radius of the blast furnace), set the ore charging position at least at the initial stage of ore charging. The peripheral charging means is set to the centrifugal side with respect to the peak position so that the high-altitude portion including at least the peak portion of the mountain-like charging coke layer is destroyed to flow toward the shaft side of the blast furnace. A method for charging a raw material into a blast furnace, which is characterized in that