JP2003096510A - Method for blasting dust coal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method or blasting dust coals into a blast furnace with which an operation blowing a large amount of dust coals can stably be performed. SOLUTION: In the method for blasting the dust coals into a tuyere in the blast furnace by using a plurality of lances for blasting the dust coals arranged by penetrating a blasting pipe, this method is found out, from which very high dispersion effect of the dust coals can be obtained by blasting the dust coals from the other blasting lance for dust coals into storing turbulent range produced at the downstream side of an optional blasting lance for dust coal. Then, this method has a peculiarity, in which the dust coal from at least one piece of blasting lance for dust coal, is blasted into the strong turbulent range produced at the downstream side of the blasting lance for dust coal except this blasting lance for dust coal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for blowing pulverized coal into a blast furnace, and more particularly to a method for blowing pulverized coal which enables stable blowing of a large amount of pulverized coal into the furnace.

[0002]

2. Description of the Related Art In order to reduce the pig iron production cost and extend the life of a coke oven, a large amount of pulverized coal is blown into a blast furnace. Since it is desirable to blow as much pulverized coal into the furnace as possible in this pulverized coal large-volume blowing operation, the amount of pulverized coal has been increased in recent years. In particular, recently, "Materials and Process 11 (1998) p834" has been added. As can be seen, an ultra-high-volume injection blast furnace that has a monthly pulverized coal injection ratio of 266 kg / mol.ton is emerging.

When a large amount of pulverized coal is blown into the blast furnace, the pulverized coal-to-oxygen ratio (kg / Nm ³ ) increases, so the combustibility of the pulverized coal decreases and the amount of unburned pulverized coal increases. When the amount of unburned pulverized coal increases in this way, they are entrained in the gas flow in the blast furnace and discharged from the top of the furnace, and it is possible to replace part of the coke charged into the blast furnace with pulverized coal. The ratio, that is, the substitution rate is reduced, and the effect of blowing pulverized coal is reduced. On the other hand, it is clear that if the amount of oxygen supplied to the furnace is increased, the combustibility of the pulverized coal is improved, but since the production cost of oxygen is high, the amount of oxygen supplied to the furnace is increased. And the economic efficiency of blast furnace operation will be impaired.

Therefore, a method for effectively using the limited oxygen for combustion of pulverized coal and improving the combustibility of the pulverized coal is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 8-104909 and 9-256012. It is disclosed in Japanese Patent Laid-Open No. 6-330113 and the like. The technique disclosed in Japanese Patent Application Laid-Open No. 8-104909 uses a special pulverized coal blowing lance for improving the combustibility of pulverized coal.
This pulverized coal blowing lance has a shape in which the tip opening is cut obliquely with respect to a surface perpendicular to the lance axis direction, and the angle θ formed by this cut surface and the surface perpendicular to the lance axis direction is 1 /. It has a structure that satisfies cos θ ≧ 2, and is arranged in the blow pipe so that the cut surface faces an appropriate direction, and turbulent vortex (swirl flow) of hot air is generated at the tip of the lance. The purpose of this is to disperse the pulverized coal flow ejected from the tip of the lance to promote the mixing with oxygen in the hot air and improve the combustibility.

The technique disclosed in Japanese Unexamined Patent Publication No. 9-256012 gives a velocity difference between the carrier gas of pulverized coal and the flow velocity of hot air, and the shape of the tip of the pulverized coal blowing lance is, for example, a cone shape (a divergent shape). Or make various incisions such as making further cuts in the cone-shaped tip to increase the degree of turbulence at the tip of the pulverized coal blowing lance and promote mixing of pulverized coal and hot air to improve combustibility. Is aimed at. Although the techniques disclosed in Japanese Patent Laid-Open No. 8-104909 and Japanese Patent Laid-Open No. 9-256012 are different from each other, they have the aim of increasing the turbulence at the tip of the pulverized coal blowing lance and the effect thereof. Since they are almost the same, these technologies are collectively referred to as "Prior Art 1".
And

In the technique disclosed in Japanese Patent Laid-Open No. 6-330113, when pulverized coal is blown using a plurality of pulverized coal blowing lances, the pulverized coal flow from the plurality of pulverized coal blowing lances is in the blow pipe. Focusing on the fact that pulverized coal is involved in the flow direction and pulverized coal is entrained in the vortex, it becomes difficult to diffuse over the entire blow pipe. It is arranged so that it does not intersect with the central axis of the pipe and is axially symmetrical with respect to the central axis of the blow pipe, so that the pulverized coal flows will not collide with each other, and It diffuses, promotes the mixing of pulverized coal and oxygen, and improves the combustibility of the pulverized coal. Hereinafter, this technique is referred to as "conventional technique 2".

[0007]

According to the above-mentioned conventional techniques, the combustibility of pulverized coal is improved and a large amount of pulverized coal can be blown. For example, it became clear that each method had practical problems as described below. First, according to the method of the prior art 1, the effect of improving the combustibility of the pulverized coal due to the diffusion of the pulverized coal due to the turbulent flow generated at the tip of the lance is obtained, but this method has a problem in the durability of the lance. Cause That is, the tip of the pulverized coal blowing lance has a very large heat load due to the radiant heat from the red hot coke in the raceway or the burned pulverized coal. Therefore, a lance having a strong water cooling structure is usually used. But,
Since the tip shape of the lance used in the related art 1 is very complicated, there is a problem that it is difficult to provide a water cooling structure having a sufficient cooling capacity. Moreover, in order to improve the degree of turbulence and accelerate the ignition and combustion of pulverized coal, the closer the combustion area of pulverized coal is to the tip of the lance, the greater the heat load at the tip of the lance and the melting damage of the tip of the lance. There is also a problem that the flow rate is accelerated, and the turbulence cannot be increased due to the deformation of the tip of the lance due to the generated melting loss, and in the worst case, it becomes impossible to blow.

Further, the prior art 2 is a very effective method for improving the combustibility of pulverized coal, but since it does not utilize the influence of turbulence as in the prior art 1, its effect is limited. is there. That is, with the method according to the conventional technique 2 only, it is possible to stably blow up the pulverized coal blowing ratio up to about 200 kg / hot metal ton, but if the pulverized coal blowing ratio is higher than that, the furnace condition becomes unstable or the furnace top There is a problem that the emission of unburned pulverized coal is remarkable. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for injecting pulverized coal into a blast furnace capable of stably performing an operation for injecting an ultra-large amount of pulverized coal.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention presuppose a pulverized coal blowing method using a plurality of pulverized coal blowing lances as in the above-mentioned Prior Art 2, and turbulent flow in such a pulverized coal blowing method. The method of generating the dispersion effect of pulverized coal by the above was repeatedly studied. As a result, paying attention to the high turbulent flow field (strong turbulent flow region) generated on the downstream side of the pulverized coal injection lance itself, and blowing pulverized coal from another pulverized coal injection lance to this high turbulent flow field It has been found that a high pulverized coal dispersing effect can be obtained, and that by such a method, the durability of the pulverized coal blowing lance itself can be enhanced as compared with the prior art.

The present invention has been made based on the above findings, and its features are as follows. [1] In a method of blowing pulverized coal into the tuyere of a blast furnace by using a plurality of pulverized coal blowing lances penetrating through a blow pipe, the pulverized coal from at least one pulverized coal blowing lance is the pulverized coal. A method for injecting pulverized coal into a blast furnace, characterized in that the pulverized coal is injected into a strong turbulent flow region downstream of the pulverized coal injection lance other than the injection lance.

[2] In the blowing method of [1] above, the pulverized coal is blown into the tuyere of the blast furnace by using two pulverized coal blowing lances penetrating the blow pipe. The central axis (y ₁ ) or its extension does not intersect with the central axis of the other pulverized coal injection lance (y ₂ ) or its extension, and the central axis of the blow pipe
(x) and the central axis of both pulverized coal blowing lances
On a projection plane on a virtual plane parallel to (y ₁ ) and (y ₂ ),
The intersection point p of the center axes (y ₁ ) and (y ₂ ) of both pulverized coal blowing lances (including the extension line of the center axis) and the center axis of the blow pipe passing through the center of the tip of each pulverized coal blowing lance ( The distance L in the direction of the blow pipe central axis (x) between the straight line perpendicular to (x) satisfies the following formula (1), and the central axes (y ₁ ) and (y ₁ ) of both pulverized coal blowing lances are y ₂ ) (However,
The method for injecting pulverized coal into the blast furnace according to claim 1, wherein the shortest distance D (including an extension of the central axis) satisfies the following expression (2). -(D / 2) ・ (cos ² θ / sin θ) ≦ L ≦ d / sin θ (1) D ≦ 2d (2) where d: outer diameter of pulverized coal blowing lance (mm) θ: the above projection Center axis of blow pipe on top (x)
(°) between the central axis of the lance for blowing pulverized coal (y ₁ ) or (y ₂ ) (including the extension of the central axis)

[0012]

DETAILED DESCRIPTION OF THE INVENTION The details and preferred embodiments of the present invention will be described below. When an object is placed in a uniform flow, a vortex is generated downstream of the object. This vortex is generally called a Karman vortex and is described in detail, for example, in "Handbook of Chemical Engineering (Revised 5th Edition) P.120". By the way, when a vortex is generated, a flow component perpendicular to the initial flow direction is generated. This means that in the case of pulverized coal blowing in a blast furnace, the initial flow direction is mainly the axial direction of the blow pipe, but the Karman vortex generated by the object (pulverized coal blowing lance) placed in the blow pipe causes This means that a flow component is generated in the pipe radial direction.
Therefore, if the pulverized coal is blown in such a form that the pulverized coal particles are affected by this vortex, the dispersion of the blown pulverized coal in the blow pipe radial direction may be enhanced.

The energy of the vortex can be generally obtained by using a turbulent flow model such as a k-ε2 equation model.
The present inventors used the above turbulence model to investigate under what conditions a turbulent flow field due to a pulverized coal blowing lance is generated. Figure 2 shows the arrangement of the pulverized coal blowing lances used in the calculation. The angle formed by the central axes (y ₁ ) and (y ₂ ) of the pulverized coal blowing lances a and b and the central axis (x) of the blow pipe. Is θ, and the thickness (outer diameter) of lances a and b for blowing pulverized coal
Is defined as d, and the values of θ and d are variously changed for calculation. Further, in calculation, the flow velocity of hot air was set to 100 m / sec.

In order to quantify the strength of the turbulent flow caused by the pulverized coal blowing lance, the turbulent kinetic energy (vortex energy) was used for evaluation. In turbulent flow, the velocity greatly changes with time in both its magnitude and direction. Therefore, the instantaneous value of the velocity component is calculated as the sum of the time average value and the fluctuation component
It is decided to express it as in equation (3).

[Equation 1] The kinetic energy k of the turbulent flow is expressed by the following equation (4) using the above fluctuation component.

[Equation 2] Generally, the larger the value of turbulent kinetic energy k, the larger the time-varying energy of turbulence and the larger the energy of vortices.

The above turbulent kinetic energy can be calculated by the k-ε2 equation.
Calculated by model. The calculation result is shown in FIG. Smell in Figure 3
The vertical axis is turbulent kinetic energy, and the horizontal axis is pulverized coal injection.
Distance from lance (Pulverized coal injection lance center axis
plane containing (y) and parallel to the central axis (x) of the blow pipe
In the above, the central axis (y) of the lance for blowing pulverized coal is
And the distance in the vertical direction). In Figure 3, turbulent motion
The maximum value of energy is k ₀And, for convenience, turbulent motion energy
Rugie is k₀The region of / 5 is the region of high turbulence intensity
Defined. In the calculation result shown in Fig. 3, pulverized coal injection
Downstream of the lance (in the flow direction of hot air in the blow pipe
Of the turbulent flow with a width of 2d (d: lance outer diameter)
It became clear that a large region (strong turbulence region) was created.
It was Also, the influence of θ on the formation of this strong turbulent flow region is small.
It was good. Downstream of this pulverized coal blowing lance (hot air
Strong turbulence region that occurs in the flow direction, immediately downstream of the lance)
Is schematically shown in FIG. In addition, pulverized coal blowing lance tip
The structure of the tip of the lance affects the formation of turbulence near the edge.
However, it will be a little complicated, so this effect will be described later.
It

As described above, it has been clarified that a strong turbulent flow region is formed with a specific width on the downstream side of the pulverized coal blowing lance (the downstream side immediately adjacent to the lance in the hot air flow direction). In order for the pulverized coal flow blown from the other pulverized coal blowing lance to enjoy the effect of the turbulent flow formed by, the strong turbulent flow region formed on the downstream side of the one pulverized coal blowing lance must be It is sufficient to blow the pulverized coal from one of the pulverized coal blowing lances. Therefore, in the present invention, among the plurality of pulverized coal blowing lances, the pulverized coal from at least one pulverized coal blowing lance is in the strong turbulent flow region generated on the downstream side of the pulverized coal blowing lance other than the pulverized coal blowing lance. The pulverized coal is blown in by a plurality of pulverized coal blowing lances. Here, as shown in FIG. 4, in general, the strong turbulent flow region is 2 in the direction orthogonal to the central axis of the pulverized coal blowing lance on the downstream side immediately adjacent to the pulverized coal blowing lance.
It is formed with a width of d (d: outer diameter of lance). Therefore, generally, pulverized coal may be blown into another region having a width of 2d from another pulverized coal blowing lance.

The number of pulverized coal blowing lances is arbitrary, but normally two lances are sufficient. It is preferable that each of the plurality of pulverized coal blowing lances blows the pulverized coal into a strong turbulent flow region that occurs on the downstream side of the other pulverized coal blowing lances. Therefore, when there are two pulverized coal blowing lances, the pulverized coal blowing lance a blows the pulverized coal into the strong turbulent flow region generated on the downstream side of the pulverized coal blowing lance b, and the pulverized coal blowing lance b blows the pulverized coal. It is preferable to blow pulverized coal into the strong turbulent flow region generated on the downstream side of the lance a. In order to sufficiently diffuse the pulverized coal blown from the multiple pulverized coal blowing lances in the blow pipe, the pulverized coal flow from the multiple pulverized coal blowing lances becomes a swirling flow in the blow pipe. It is preferable to make the flow toward the mouth side, in order to generate such a swirling flow of pulverized coal, it is preferable that the central axis of a plurality of pulverized coal blowing lances or their extension lines do not intersect with each other, and Of the plurality of pulverized coal blowing lances, it is preferable that at least a part of the pulverized coal blowing lances, and preferably all of the pulverized coal blowing lances, do not intersect with the central axis of the blow pipe.

Next, a preferred embodiment of the positional relationship between the two pulverized coal blowing lances when two pulverized coal blowing lances are used in the present invention will be described. In this embodiment, the pulverized coal flow from both pulverized coal blowing lances becomes a swirling flow in the blow pipe and flows toward the tuyere side, so that the central axis (y ₁ ) of one of the pulverized coal blowing lances or Make sure that the extension line does not intersect with the central axis (y ₂ ) of the other pulverized coal blowing lance or its extension line. Further, at least one of the pulverized coal blowing lances has a central axis (y ₁ ) or (y ₂ ), preferably both of the pulverized coal blowing lances has a central axis (y ₁ ) or (y ₂ ) ). FIG. 5 shows that when two pulverized coal blowing lances a and b having substantially the same diameter (the outer diameters are substantially the same) are arranged symmetrically with respect to the central axis (x) of the blow pipe, these pulverized coal blowing lance a , B, including the central axis (x) of the blow pipe, and the central axes of both pulverized coal blowing lances a and b.
It is shown as a projection view on a virtual plane parallel to (y ₁ ) and (y ₂ ).

The pulverized coal blowing lance a, shown in FIG.
b indicates that the pulverized coal from the pulverized coal blowing lance a is blown into the strong turbulent flow region generated on the downstream side of the pulverized coal blowing lance b, and the pulverized coal from the pulverized coal blowing lance b is downstream of the pulverized coal blowing lance a. Although it is arranged so that it is blown into the strong turbulent flow region generated on the side, the central axes (y ₁ ) and (y ₂ ) of both pulverized coal injection lances a and b on this projection view
(However, including the extension line of the central axis. The same applies to the following.) And the straight line (s) that passes through the tip center of each pulverized coal blowing lance and is perpendicular to the central axis (x) of the blow pipe. If the distance L in the blow pipe central axis (x) direction between them is excessively long (that is, the intersection point p of the central axes (y ₁ ) and (y ₂ ) of both pulverized coal blowing lances a and b on this projection diagram is p. Is too close to the lance base end side), the pulverized coal from the other pulverized coal blowing lance is not blown into the strong turbulent flow region generated on the downstream side of the one pulverized coal blowing lance. Here, from the formation range of the strong turbulent flow region shown in FIG. 4, the pulverized coal from the other pulverized coal blowing lance is blown into the strong turbulent flow region generated on the downstream side of the one pulverized coal blowing lance. The upper limit of the distance L to satisfy the above condition can be expressed by the following equation (5). L ≦ d / sin θ (5) where d: outer diameter of pulverized coal injection lance (mm) θ: central axis of blow pipe (x) on the above projection
(°) between the central axis (y ₁ ) or (y ₂ ) of the lance for blowing pulverized coal

On the other hand, the distance L becomes shorter (that is,
When the intersection point p of the central axes (y ₁ ) and (y ₂ ) of both pulverized coal blowing lances a and b approaches the lance tip side on the above projection view, and finally the value of the distance L becomes negative, The pulverized coal flow from the other pulverized coal blowing lance is less likely to be affected by the strong turbulent flow region generated on the downstream side of the coal blowing lance.

FIG. 6 shows the positional relationship between the pulverized coal blowing lances a and b, which is the limit, and shows the central axis (x) of the blow pipe.
And the central axis of both pulverized coal blowing lances (y ₁ ),
It is shown as a projection view on an imaginary plane parallel to (y ₂ ). According to this figure, the tip edges of the pulverized coal blowing lances a and b in the above projection are the central axis of the blow pipe.
In the case where the arrangement relationship overlaps with (x), it is the limit that the pulverized coal flow from the pulverized coal blowing lance on the other side can be used in the strong turbulent flow region generated by the pulverized coal blowing lance on the other side. When the tip portion is located further behind the intersection point P (that is, the intersection point p and the straight line (s) passing through the tip center of the pulverized coal blowing lance and perpendicular to the central axis (x) of the blow pipe). When the negative value of the distance L increases, the strong turbulent flow region generated on the downstream side of the one pulverized coal blowing lance and the pulverized coal flow from the other pulverized coal blowing lance do not overlap each other. Therefore, the lower limit of the distance L can be expressed by the following equation (6). − (D / 2) ・ (cos ² θ / sin θ) ≦ L ... (6)

The central axis of the lance for blowing pulverized coal (y
_{If 1} ) and (y ₂ ) are too far apart from each other, the strong turbulent flow region generated on the downstream side of one pulverized coal blowing lance and the pulverized coal flow from the other pulverized coal blowing lance will not overlap. From the results of the above turbulence calculation, the spread of strong turbulence in the direction perpendicular to the plane including the central axis (y) of the pulverized coal injection lance and parallel to the central axis (x) of the blow pipe is at most lance. The range is equivalent to the outer diameter (= d). Therefore, as shown in FIG. 7, the shortest distance D between the central axes (y ₁ ) and (y ₂ ) of the pulverized coal blowing lances a and b is as follows.
It is necessary to satisfy equation (7). D ≦ 2d (7)

From the above results, the blower having almost the same diameter
Of two axisymmetrics about the central axis (x) of the ip
When blowing pulverized coal through a pulverized coal blowing lance
Quantitatively, the positional relationship between both pulverized coal blowing lances
If specified, include the central axis (x) of the blow pipe
Moreover, the central axis of both pulverized coal blowing lances (y₁) ， (Y_Two) To
Both pulverized coals are blown on the projection on a parallel virtual plane.
Center axis of the lance (y ₁) ， (Y_Two) Intersection p and each pulverized coal
Through the center of the tip of the blowing lance and in the blow pipe
Blow pipe between straight line (s) perpendicular to core axis (x)
The distance L in the direction of the central axis (x) satisfies the following formula (1),     -(D / 2) ・ (cos^Twoθ / sinθ) ≤ L ≤ d / sinθ (1) However, d: outer diameter of lance for blowing pulverized coal (mm) θ: central axis of blow pipe (x) on the above projection
And the central axis of the pulverized coal injection lance (y₁) Or (y_Two) And
Angle formed (°) In addition, the central axis of both pulverized coal injection lances (y₁) ， (Y
_TwoThe finest particles so that the shortest distance D between them satisfies the following formula (2)
It means arranging a charcoal blowing lance. D ≦ 2d (2)

Further, on the downstream side of one pulverized coal blowing lance
The influence of the strong turbulent flow region generated on the side of
You can enjoy the pulverized coal flow from the included lance more effectively
In order to do so, the distance L satisfies the following equation (1 ')
Preferably. 0 ≦ L ≦ d / sin θ (1 ') In addition, the specific conditions as described above are based on
Center axis of the lance (y ₁) Or its extension and the other fine powder
Central axis of charcoal blowing lance (y_Two) Or its extension
The premise is not to intersect. Also, inject both pulverized coal
The lance is located in at least one of the pulverized coal blowing lances.
Axis (y₁) Or (y_Two), Preferably both pulverized coal blown
Center axis of the lance (y₁) ， (Y_Two) Is the center of the blow pipe
It is preferred not to intersect the axis (x).

FIG. 1 shows an embodiment of a method for injecting pulverized coal into the blast furnace according to the present invention. FIG. 1 (A) is a vertical cross section of a blow pipe provided at the tuyere of the blast furnace. 1B is a sectional view taken along the line BB of FIG.

In FIG. 1, two pulverized coal blowing lances 3a and 3b are inserted into the blow pipe 1 connected to the tuyere 2 through the blow pipe outer shell. These two pulverized coal blowing lances 3a and 3b are such that the tips of the lances 3a and 3b face the tuyere 2 side, and the central axes (y ₁ ) and (y
₂ ) is arranged so as not to intersect the central axis (x) of the blow pipe 1 and to be axially symmetrical with respect to the central axis (x) of the blow pipe 1. These pulverized coal blowing lances 3a, 3b include the central axis (x) of the blow pipe 1 and both pulverized coal blowing lances 3a, 3b.
On a projection view (Fig. 1) on a virtual plane parallel to, the central axes (y ₁ ) and (y ₂ ) of the pulverized coal injection lances 3a and 3b are shown.
In the blow pipe central axis (x) direction between the intersection point p and the straight line (s) passing through the tip centers of the pulverized coal blowing lances 3a, 3b and perpendicular to the central axis (x) of the blow pipe 1. The distance L satisfies the formula (1) below, and − (d / 2) ・ (cos ² θ / sin θ) ≦ L ≦ d / sin θ (1) where d: outer diameter of pulverized coal blowing lance (mm ) Θ: Center axis of blow pipe (x) on the above projection
(°) between the central axis of the pulverized coal blowing lance (y ₁ ) or (y ₂ ) and the central axis of both pulverized coal blowing lances 3a, 3b.
The shortest distance D between (y ₁ ) and (y ₂ ) is arranged so as to satisfy the following expression (2). D ≦ 2d (2)

In this embodiment, the pulverized coal is blown into the blow pipe 1 together with the carrier gas from the above two pulverized coal blowing lances 3a and 3b at a flow rate of, for example, about 15 m / sec, but two pulverized coal blowing lances are used. 3a, 3b
Do not intersect their central axes (y ₁ ) and (y ₂ ) with the central axis (x) of the blow pipe (that is, the central axes (y ₁ ) and (y ₂ ) of each pulverized coal blowing lance are Central axis of
(Eccentric with respect to (x)), and the central axes of the pulverized coal blowing lances 3a and 3b or their extension lines do not intersect with each other, and are axially symmetric with respect to the central axis (x) of the blow pipe 1. The pulverized coal from both pulverized coal blowing lances 3a and 3b is blown into the blow pipe 1 without interfering with each other and quickly diffuses in the blow pipe 1. Moreover, since the pulverized coal from the two pulverized coal blowing lances 3a and 3b is blown into the strong turbulent flow region generated on the downstream side of the opposite lance, diffusion of the pulverized coal is further promoted and swirled in the blow pipe 1. While moving in the tuyere 2 direction, the contact efficiency with oxygen in the hot air is further improved, and the combustion efficiency of pulverized coal is remarkably improved.

As the carrier gas for blowing pulverized coal, at least one selected from nitrogen, air, oxygen, CO, CO ₂ gas and the like can be used. Further, both pulverized coal blowing lances 3a, 3b satisfy the condition that their central axes (y ₁ ) and (y ₂ ) do not intersect with the central axis (x) of the blow pipe 1, and at least one of the pulverized coal blowing lances. Pulverized coal from the other pulverized coal blowing lance 3 is blown into the strong turbulent flow area that occurs on the downstream side of the lance 3,
More preferably, two pulverized coal blowing lances 3a, 3b
As long as the pulverized coals from No. 1 are arranged so as to be blown into the strong turbulent flow region generated on the downstream side of the opposite lance, they do not necessarily have to be arranged symmetrically with respect to the central axis (x) of the blow pipe 1. .

[0029]

EXAMPLE FIG. 8 is a cross-sectional view of the reaction furnace used in this example. This reaction furnace is a reaction furnace for pulverized coal combustion test imitating the vicinity of tuyere of a blast furnace. In the figure, 4 is a reactor main body, 5 is a tuyere provided in the reactor main body 7, 6 is a blow pipe connected to the tuyere 5, and 7 is pulverized coal blowing in the blow pipe 7. The charging lances 8a to 8c are three pulverized coal collecting probe holes formed in the blow pipe 6, and these pulverized coal collecting probe holes 8a to 8c are formed from the tip of the pulverized coal blowing lance 7 to the tuyere direction. 2 each
It is provided at positions separated by 00 mm, 300 mm, and 400 mm. Hot air was blown into the coke layer 10 filled in the reactor body 4 from the blow pipe 6. The hot air used was one in which LPG was combusted with air on the upstream side of the blow pipe 6 and oxygen was mixed with this combustion gas to have an oxygen concentration similar to that of the hot air used in the blast furnace.

In this embodiment, (A), (B),
Pulverized coal was blown into the blow pipe 6 using three types of pulverized coal blowing lances shown as (C). The pulverized coal sampling probe is inserted into each of the three pulverized coal sampling probe holes 8a to 8c, the pulverized coal in the combustion process is sampled, and these are analyzed to determine the combustion rate of the pulverized coal by each pulverized coal injection method. I checked each time. The definition of the burning rate was calculated as the consumption rate of combustible components as shown in the following formula (8). The test conditions at this time are shown in Table 1, and the test equipment specifications are shown in Table 2. Burning rate = 100 × {1− (100− [Ash]) ・ [Ash ₀ ] / (100− [Ash ₀ ]) ・ [Ash]} (8) where [Ash ₀ ]: pulverized coal before combustion Ash content (mass%) [Ash]: Ash content at each sampling position after combustion (ma
ss%)

The pulverized coal blowing using the lance of the type shown in FIG. 9A is an example of the present invention, and the pulverized coal blowing using the lances of the types of FIGS. 9B and 9C is a comparative example. here,
The lance of the type shown in FIG. 9 (A) is similar to that shown in FIG. 1, and the lance shown in FIG. 9 (B) is obtained by processing the tip of one pulverized coal blowing lance based on the prior art 1. The lance of FIG. 9C is the same as that of the conventional technique 2. The result of the combustion test in this example is shown in FIG. The amount of pulverized coal blown under these test conditions corresponds to 200 kg / ton of hot metal in the actual operation of the blast furnace. As shown in FIG. 10, it can be seen that the combustion efficiency of the pulverized coal is higher in the examples of the present invention than in both comparative examples. Further, in the comparative example using the lance of FIG. 9B, when the pulverized coal blowing lance was taken out and examined after the combustion test, it was confirmed that the tip portion was partially melted, and the pulverized coal was pulverized for a long period of time. Was determined to be difficult to infuse.

Further, in order to investigate the influence of the brand of pulverized coal, the same combustion test was conducted using the other pulverized coal b and c shown in Table 3. FIG. 11 shows the results of examining the burning rate of pulverized coal at a position 400 mm away from the tip of the lance for blowing pulverized coal in the tuyere direction. As shown in FIG. 11, it can be seen that, in the present invention example, higher combustion efficiency was obtained compared to both comparative examples, regardless of the type of pulverized coal.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

As described above, according to the present invention, the combustion rate of the pulverized coal blown into the blast furnace can be greatly improved through the pulverized coal blowing lance, so that the blast furnace can be stably injected with a large amount of pulverized coal. Can be carried out. Further, therefore, the pig iron manufacturing cost can be significantly reduced as compared with the conventional method.

[Brief description of drawings]

FIG. 1 shows an arrangement structure of a pulverized coal blowing lance in one embodiment of the present invention, FIG. 1 (A) is a vertical cross section of a blow pipe provided at a tuyere of a blast furnace, and FIG. 1 (B) is a diagram. It is sectional drawing which follows the BB line of 1 (A).

FIG. 2 is an explanatory view showing the arrangement of the pulverized coal blowing lance used for calculation of turbulent kinetic energy on the downstream side of the pulverized coal blowing lance arranged in the blow pipe.

FIG. 3 is a graph showing turbulent kinetic energy of turbulent flow generated on the downstream side of a pulverized coal blowing lance.

FIG. 4 is an explanatory view schematically showing a strong turbulent flow region generated on the downstream side of the pulverized coal blowing lance.

FIG. 5 shows the intersection points p of the central axes (y ₁ ) and (y ₂ ) of the two pulverized coal blowing lances when the pulverized coal is blown using two pulverized coal blowing lances according to the method of the present invention. Explanatory drawing showing the distance L in the blow pipe central axis (x) direction between the straight line (s) passing through the tip center of the pulverized coal blowing lance and perpendicular to the central axis (x) of the blow pipe.

FIG. 6 shows a case where the pulverized coal is injected by using two pulverized coal blowing lances according to the method of the present invention, the intersection points p of the central axis lines (y ₁ ) and (y ₂ ) of both pulverized coal blowing lances, and The distance L in the blow pipe center axis (x) direction between the straight line (s) passing through the center of the tip of the pulverized coal blowing lance and perpendicular to the center axis (x) of the blow pipe is the lower limit value. Explanatory drawing showing the arrangement relationship of pulverized coal blowing lances

FIG. 7 shows the shortest distance D between the central axes (y ₁ ) and (y ₂ ) of both pulverized coal blowing lances when the pulverized coal is injected by using two pulverized coal blowing lances according to the method of the present invention.
Explanatory diagram showing

FIG. 8 is a schematic cross-sectional view of the reaction furnace used in the examples.

FIG. 9 shows the type of pulverized coal blowing lance used in the examples. FIG. 9 (A) is the lance type used in the example of the present invention, and FIGS. 9 (B) and 9 (C) are comparative examples. This is the lance format used.

FIG. 10 is a graph showing the burning rate of pulverized coal of brand a in the example.

FIG. 11 is a graph showing burning rates of pulverized coals of brands b and c in the example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Blow pipe, 2 ... Tuyere, 3a, 3b ... Pulverized coal injection lance, 4 ... Reactor main body, 5 ... Tuyere, 6 ... Blow pipe, 7 ... Pulverized coal injection lance, 8a-8c ... Pulverized coal sampling probe Holes, 10 ... coke layer, a, b ... pulverized coal blowing lance, s ... straight line, p ... intersection, x, y ₁ , y ₂ ... central axis

Continued front page    (72) Inventor Tatsuro Ariyama             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd. (72) Inventor Akinori Murao             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd. (72) Inventor Kazuya Goto             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd. (72) Inventor Mori Kotobuki             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd. (72) Inventor Yoshikazu Hayasaka             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd. F-term (reference) 4K012 BE01 BE08                 4K015 AD03

Claims (2)

[Claims] 1. A method for injecting pulverized coal into the tuyere of a blast furnace by using a plurality of pulverized coal blowing lances penetrating a blow pipe, wherein at least one pulverized coal blowing lance is A method for injecting pulverized coal into a blast furnace, characterized in that the pulverized coal is injected into a strong turbulent flow region downstream of the pulverized coal injection lance other than the pulverized coal injection lance. 2. A method of injecting pulverized coal into the tuyere of a blast furnace by using two pulverized coal blowing lances penetrating a blow pipe, wherein one of the pulverized coal blowing lances has a central axis (y ₁ ) or its Center line of extension line and other pulverized coal blowing lance (y ₂ )
Or, on a projected view on a virtual plane that does not intersect with the extension line and includes the central axis (x) of the blow pipe and is parallel to the central axes (y ₁ ) and (y ₂ ) of both pulverized coal blowing lances. , Central axis of both pulverized coal injection lances (y ₁ ), (y ₂ ) (however, including extension of the central axis)
The distance L in the blow pipe center axis (x) direction between the intersection point p and the straight line passing through the tip center of each pulverized coal injection lance and perpendicular to the blow pipe center axis (x) is as follows.
Satisfies the formula (1), and the central axes (y ₁ ) and (y ₂ ) of both pulverized coal blowing lances.
The method for injecting pulverized coal into a blast furnace according to claim 1, wherein the shortest distance D (including an extension line of the central axis) satisfies the following expression (2). -(D / 2) ・ (cos ² θ / sin θ) ≦ L ≦ d / sin θ (1) D ≦ 2d (2) where d: outer diameter of pulverized coal blowing lance (mm) θ: the above projection Center axis of blow pipe on top (x)
(°) between the central axis of the lance for blowing pulverized coal (y ₁ ) or (y ₂ ) (including the extension of the central axis)