TW201920692A - Top-blowing lance for converter blowing and molten iron refining method - Google Patents

Abstract

The present invention satisfies 0.19 ≤ L/L0 ≤ 0.82, where L0, given a cross section including the center axis of a lance and bisecting a boundary plane between a flow path of a lance inner tube and a nozzle hole, is the length of a line segment which passes through the most downstream point of the lance on the boundary plane and traverses the nozzle hole on a straight line perpendicular to the lance center axis, and L is the length of said traversing line segment when projected within the range of the flow path of the lance inner tube on a horizontal cross section taken perpendicular to the lance center axis.

Description

Top-blowing spray gun for converter blowing and refining method of molten iron

FIELD OF THE INVENTION The present invention relates to a top-blowing spray gun for converter blowing used for spraying refining gas and powder onto a molten iron bath surface in a steel-making converter, and to use the converter for blowing Refining method of molten iron for top-blowing lances.

BACKGROUND OF THE INVENTION For example, in the preliminary dephosphorization refining in an oxygen top-blown converter steelmaking method, a method in which powder of quicklime or the like is sprayed on the surface of molten iron together with an oxygen jet is used. At this time, the powder is sprayed into the collision surface of the oxygen jet and the molten iron, the so-called fire point, to promote slagging and improve the reaction efficiency. Therefore, in this method, it is necessary to inject the powder at a high speed as much as possible to reach the fire point reliably.

However, when the powder injection speed is increased, abrasion of the nozzle by the powder becomes a problem. Nozzle abrasion continues, and openings in the flow path of the cooling water used to cool the nozzles cause leakage of the cooling water, which will become a major operational obstacle, resulting in a reduction in productivity. Moreover, when the abrasion of a nozzle becomes remarkable, there exists a problem that a refining behavior changes and a blowing control becomes difficult. Not only for preliminary dephosphorization refining, but also for decarburization refining of molten iron that has not been subjected to preliminary dephosphorization refining or molten iron that has been subjected to preliminary dephosphorization refining, the same applies when spraying powder of quicklime or minerals from a top-blowing lance. Subject.

Therefore, in order to solve this problem, for example, in Patent Document 1, a method has been disclosed in which hard chromium plating by electroplating is performed on the inner surface of the nozzle hole to suppress wear. However, although the method disclosed herein can improve the abrasion resistance of the nozzle, it cannot prevent the powder from colliding with the inner surface of the nozzle hole. In addition, it is difficult to say that it is easy to apply hard chromium plating to the nozzle holes.

Furthermore, from the viewpoint of suppressing slag blasting in actual operation, since the dynamic pressure of the jet flow is dispersed, an inclination angle is generally given to the nozzle to make it porous. Therefore, it is thought that the wear of the nozzle caused by the powder is also closely related to the arrangement of the nozzle or the tilt angle of the nozzle. For example, if a single-hole nozzle is used, most of the powder passing through the nozzle with oxygen can be estimated to prevent the powder from colliding with the inner wall of the nozzle even if it does not follow the air flow, making it difficult to wear. On the other hand, in the case of a porous nozzle, the inner wall of the nozzle is angled with respect to the axial direction of the inner tube of the spray gun. Therefore, if the powder does not follow the air flow, it will definitely collide with the inner wall of the nozzle, which is easy to wear. Therefore, regardless of the material of the nozzle, a technology based on a porous spray gun structure to suppress nozzle wear caused by powder is required.

The technology premised on the structure of a porous spray gun, for example, describes in Patent Document 2 that when spraying powder from a top-blown spray gun, the sum of the cross-sectional area of the throat of the nozzle and the cross-section of the inner tube flow path of the spray gun are adjusted. Area ratio to change the distribution of powder as it passes through the nozzle. However, this method is for the purpose of suppressing slag blasting, and the relationship with suppressing nozzle wear is not described. In addition, since the inner wall of the nozzle has an angle with respect to the axial direction of the inner tube of the spray gun, even if the distribution of the powder passing through the nozzle portion can be changed, as described above, the possibility of the powder colliding with the inner wall of the nozzle is high and it is difficult Suppress wear of nozzle holes. Prior technical literature Patent literature

[Patent Document 1] JP 2003-213318 [Patent Document 2] JP 2012-251199

SUMMARY OF THE INVENTION Problems to be Solved by the Invention The present invention has been made in view of the foregoing problems, and an object thereof is to provide a converter blower having an inner wall of a nozzle having an angle with respect to the axial direction of the inner tube of the spray gun and having a porous nozzle, which can suppress the wear of these nozzle holes Refining top-blowing lance and method for refining molten iron using the converter-blowing top-blowing lance. Means to solve the problem

When the powder sub-material is top-blown with an oxygen-containing gas from a top-blowing lance, usually, an oxygen-containing gas pipe and a powder sub-material piping are connected to the upper end of the top-blowing lance. The ingredients are mixed. In addition, the mixture of the oxygen-containing gas and the powder auxiliary material passes through one of the inner tubes of the spray gun, and is sprayed from one or more nozzle holes (nozzle holes) connected to the front end of the nozzle inner tube.

The present inventors reviewed as follows: the use of a porous nozzle having a porous nozzle as described later, that is, an inner wall of the nozzle having an angle with respect to the axial direction of the inner tube of the spray gun, that is, a central axis of the nozzle hole with respect to the oxygen-containing gas and In the case of a top-blowing spray gun with a porous nozzle inclined by the central axis of the flow path of the powder auxiliary material, the powder behavior is controlled by the joint position of the nozzle hole and the flow path of the inner tube of the spray gun to suppress nozzle wear. In the following, the inner wall surface of the imaginary spray gun inner tube flow path which separates the spray gun inner tube flow path from the boundary portion of the nozzle hole in the inner wall surface of the spray gun inner tube flow path will be referred to as a "boundary surface".

FIG. 1 shows a cross section that includes the center axis of the spray gun and bisects the above-mentioned boundary surface with respect to one nozzle. In FIG. 1, a straight line passing through a point on the boundary surface of the spray gun at the most downstream side and perpendicular to the central axis of the spray gun is defined as a straight line A. Further, a line segment that crosses the nozzle hole on the straight line A is defined as a cross-section line segment B. Further, a line segment projected on the cross-section when the cross-section line segment B is projected on a cross-section perpendicular to the center axis of the spray gun within the range of the flow path of the inner pipe of the spray gun is defined as a line segment C. The inventors have found that nozzle wear can be suppressed by the ratio L / L ₀ of the length L _{0 of the} cross-sectional line segment B and the length L of the line segment C satisfying the expression (1). In the case of a top-blowing spray gun having a perforated nozzle, all the nozzles inclined from the center axis of the spray gun satisfy the following formula (1). 0.19 ≦ L / L ₀ ≦ 0.82 ・ ・ ・ (1)

The present invention is as follows. [1] A top-blowing spray gun for converter blowing is performed when the molten iron is charged into the top-bottom blowing converter, and the powdery raw materials are sprayed together with the oxygen-containing gas from the top-blowing spray gun to the molten iron for blowing. The top-blowing spray gun used for converter blowing is characterized by comprising: an inner tube of the spray gun, which has a flow path for the oxygen-containing gas and the powder auxiliary material; and a nozzle section, which communicates with the aforementioned flow path for the inner tube of the spray gun. It is extended and has two or more nozzle holes. The nozzle central axis of the nozzle hole is inclined with respect to the central axis of the spray gun of the flow path, and the nozzle holes respectively satisfy the following formula (1): 0.19 ≦ L / L ₀ ≦ 0.82 ... (1) Here, L ₀ : A cross section including the central axis of the spray gun and bisecting the flow path of the inner tube of the spray gun and the boundary surface of the nozzle hole is passed on the boundary surface The point of the most downstream side of the spray gun, and the length of the line segment crossing the nozzle hole on a straight line perpendicular to the center axis of the spray gun, L: within the range of the flow path of the inner pipe of the spray gun, Projected into a cross section perpendicular to the central axis of the aforementioned spray gun , The projected length of the segment of the cross section. [2] A method for refining molten iron, which is a method for refining molten iron using a top-blowing spray gun for converter blowing described in the above [1], characterized in that: the molten iron is charged into a top-bottom blowing converter, Then, the powdery raw material and the oxygen-containing gas are sprayed onto the molten iron from the top-blowing spray gun for converter blowing, and the blowing is performed. Invention effect

According to the present invention, it is possible to suppress the abrasion of the nozzle caused by the oxygen-containing gas and the powder auxiliary material being subjected to top blowing, and to extend the wear life of the refining spray gun.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The top-blowing lance for converter blowing of the present invention is used when spraying an oxygen-containing gas together with a powder auxiliary material to molten iron which is charged into the converter for blowing.

Fig. 2 is a schematic cross-sectional view of a front end portion of the porous spray gun. Example 202 is a schematic cross-sectional view of the front end portion of the top-blowing lance 1 of the present invention, and corresponds to Example 102 of FIG. 1. That is, the cross section shown in Example 202 is a cross section including the center axis 2d of the spray gun and dividing the boundary surface 4 in half. On the other hand, the example 201 of FIG. 2 is a schematic cross-sectional view of the front end portion of the top blowing spray gun 5 as the first comparative example, and corresponds to the example 101 of FIG. 1. That is, the cross section shown in the example 201 of FIG. 2 is a cross section including the spray gun central axis 6d and dividing the boundary surface 8 in half. Furthermore, the example 203 of FIG. 2 is a schematic cross-sectional view of the front end portion of the top-blowing lance 9 as the second comparative example, and corresponds to the example 103 of FIG. 1. That is, the cross section shown in Example 203 of FIG. 2 is a cross section including the center axis 10d of the spray gun and dividing the boundary surface 12 in half. In addition, in the example shown in FIG. 2, for ease of explanation, a two-hole multi-hole spray gun is omitted for illustration. In addition, the examples 204 to 206 in FIG. 2 are A-A cross-sectional views showing the ranges of the flow paths of the inner tubes of the spray guns in the examples 201 to 203 in FIG. 2, respectively. In the example shown in FIG. 2, for the sake of simplicity, the inclination angle θ of the nozzle central axis 3c of the example 202 of FIG. 2, the nozzle central axis 7c of the example 201 of FIG. 2, and the nozzle central axis 11c of the example 203 of FIG. 2. Are the same. In the example shown in FIG. 2, although not shown, a flow path for cooling water for cooling the top-blowing lance is provided between the inner wall surface and the outer wall surface of the top-blowing lance (inner tube and nozzle portion of the lance). .

As shown in Example 202 of FIG. 2, the top-blowing spray gun 1 includes a spray gun inner tube 2 and a nozzle portion 3. The inner tube 2 of the spray gun is mainly made of iron, and has an oxygen-containing gas (hereinafter, sometimes simply referred to as "gas") sprayed into molten iron contained in a converter-type refining container, and a powder auxiliary material (hereinafter, sometimes It is simply referred to as "powder".) Of the mixed flow path 2a. The flow path 2a to the nozzle portion 3 has a tubular shape having a substantially uniform inner diameter, and has a shape in which the cross-sectional area of the flow path 2a does not change rapidly with respect to the direction of the gas and powder.

Furthermore, as shown in Example 202 of FIG. 2, the boundary surface 4 is the flow of a hypothetical inner tube 2 of the inner wall surface 2 b of the flow path 2 a separated by the boundary portion 2 c of the flow path 2 a and the nozzle hole 3 a. The inner wall surface of the road 2a. As shown in Example 205 of FIG. 2, when the boundary surface 4 is projected onto the cross section 13 perpendicular to the central axis 2d of the spray gun within the range of the flow path 2a of the inner pipe 2 of the spray gun, a boundary surrounded by a boundary line 2c ′ is formed. Projection surface 14. The boundary line 2c 'is a line that projects the boundary portion 2c onto the cross section 13.

The nozzle portion 3 is mainly made of copper and has a nozzle hole 3a. The shape of the nozzle hole 3a may be a cylindrical shape (straight tube nozzle) or a so-called laval nozzle (Laval nozzle). The nozzle hole 3a is shown in Example 202 in FIG. The end of the flow path 2a of the tube 2 is extended to communicate with the flow path 2a through the boundary portion 2c. The position where the flow path 2a and the nozzle hole 3a are joined is the length L and the cross-section of the line segment C shown in FIG. The relationship of the length L ₀ of B satisfies the position of the aforementioned formula (1). This is a view based on the following concept.

The powder that passes through the flow path of the inner tube of the gun with the gas and is ejected from the nozzle hole is roughly divided into "powder that collided with the inner wall surface of the flow path before entering the nozzle hole" and "not in the flow path." The powder that collides with the inner wall surface and directly penetrates into the nozzle hole. " The present inventors compared the actual results of the abrasion of the spray gun during a 2.5t-scale converter top-blown experiment with the behavior of the gas and powder obtained by flow analysis. "It does not directly collide with the inner wall surface of the flow path. The behavior of the powder intruding into the nozzle hole is similar to that of abrasion. Based on the above, the present inventors believe that by changing the shape of the nozzle portion, the proportion of "powder that directly penetrates into the nozzle hole without colliding with the inner wall surface of the flow path" can be reduced, and the inner wall surface of the nozzle caused by the powder can be suppressed. Abrasion.

First, it is assumed that the gas and powder flow uniformly in the flow path of the inner tube of the spray gun with respect to the center axis direction of the flow path. In this case, when the boundary surface of the flow path of the inner tube of the spray gun and the nozzle hole of the nozzle section is projected to the cross section of the flow path of the inner tube of the spray gun, if the length L of the line segment C on the projection surface is reduced, The proportion of "powder that directly penetrates into the nozzle hole without colliding with the inner wall surface of the flow path" in the entire powder body of the nozzle hole will decrease, and the amount of powder that hits the inner wall surface of the nozzle hole will decrease. Suppresses nozzle wear.

On the other hand, when the length L of the line segment C on the projection plane is 0 or too small, the length L of the line segment C becomes much smaller than the length L ₀ of the cross-sectional line segment B in the nozzle hole 3a. As a result, a biased flow may occur in the flow of gas and powder. "Powder that directly invades into the nozzle hole without colliding with the inner wall surface of the flow path" collides with the inner wall surface of the nozzle hole, causing wear.

For example, in the top-blowing lance 5 shown in Example 201 in FIG. 2, the boundary surface 8 between the nozzle hole 7 a and the flow path 6 a is located on the side of the flow path 6 a. Therefore, as shown in Example 204 of FIG. 2, when the boundary surface 8 is projected to the cross section 15 perpendicular to the central axis 6d of the spray gun, the area of the projection surface is almost zero. That is, as shown in Example 101 of FIG. 1, since the line segment C itself does not exist, L = 0. In this case, although the proportion of "powder that directly penetrates into the nozzle hole without colliding with the inner wall surface of the flow path" is reduced, a biased flow as shown in Example 201 of Fig. 2 is caused, The mechanism different from the example 203 in FIG. 2 causes the inner wall surface 7b on the upper side of the nozzle hole to wear. That is, by generating a bias flow, the velocity of the gas and the powder is accelerated in the nozzle hole 7a, and particularly, the inner wall surface 7b is easily worn away near the exit of the nozzle hole 7a.

In the top-blowing lance 9 shown in Example 203 in FIG. 2, the boundary surface 12 defined by the boundary portion 10 c between the flow path 10 a and the nozzle hole 11 a is an inner wall surface 10 b located on the most downstream side of the flow path 10 a. Therefore, when the boundary surface 12 is projected onto the cross-section 16 perpendicular to the central axis 10d of the spray gun, the projection surface 17 surrounded by the boundary line 10c 'is rounded. The boundary line 10c 'is a line that projects the boundary portion 10c to the cross section 16. Therefore, "the powder that directly penetrates into the nozzle hole without colliding with the inner wall surface of the flow path of the inner pipe of the spray gun" enters into the nozzle hole 11a in large quantities. Since the entered powder collides with the inner wall surface 11b of the nozzle hole 11a, the inner wall surface 11b is easy to wear.

Thus, in the case of the top-blowing lance 1 of this embodiment, the area of the projection surface 14 is smaller than the area of the projection surface 17 of the top-blowing lance 9 shown in Example 203 in FIG. 2, and the length L of the line segment C is short. Therefore, in the top-blowing lance 1 shown in Example 202 of FIG. 2, when the nozzle hole 3a communicates with the flow path 2a, the ratio of "powder that directly penetrates into the nozzle hole without colliding with the inner wall surface of the flow path" is greater than There are few top-blowing lances 9 shown in Example 203 of FIG. 2.

The nozzle hole 3a shown in the example 202 in FIG. 2 communicates with the flow path 2a of the inner tube 2 of the spray gun so that the nozzle center axis 3c is inclined with respect to the spray gun center axis 2d of the flow path 2a. When the inclination angle θ is less than 10 °, the jets from the spray gun become easy to fit and increase the slag blasting. When the inclination angle θ exceeds 30 °, the distance between the fire point and the furnace wall is too short, which promotes the furnace wall fire resistance Corrosion of materials, so the inclination angle θ should be 10 ~ 30 °. In addition, in the XYZ orthogonal coordinate system of the center axis 2d of the spray gun set as the inner tube 2 of the spray gun on the Z axis and the exit position of the nozzle hole 3a on the X axis, a torque equivalent to the torque of the nozzle hole 3a may be set. The angle formed by the projection of the nozzle axis to the YZ plane and the Z axis, and the angle of the nozzle axis corresponding to the inclination of the outer direction of the nozzle to the angle formed by the ZZ plane, the nozzle central axis 3c of the nozzle hole 3a faces the center of the spray gun. The direction in which the shaft 2d is twisted is inclined.

Next, the present inventors conducted an abrasion resistance test in accordance with the foregoing hypothesis to find a preferable range of L / L ₀ by using a nozzle shape with a requirement for suppressing powder wear.

(1) Common survey conditions The inventors set the diameter of the inner tube of the spray gun to 20 mm, the number of nozzle holes to 4, the throat diameter to 5.1 mm, and the inclination angle of the nozzle to 20 °. In the bisected section of the boundary surface, the length L _{0 of the} cross-section line segment B is set to a fixed value. The aforementioned cross-section line segment B is a point that passes through the most downstream side of the spray gun on the boundary plane and is a straight line perpendicular to the central axis of the spray gun. The upper cross section of the nozzle hole. On the other hand, the length L of the line segment C was changed to evaluate the abrasion of the inner wall surface of the nozzle hole caused by the powder. The line segment C is a cross-section projected on the cross-section perpendicular to the center axis of the spray gun within the range of the flow path of the inner tube of the spray gun. Line B projected on the cross section. The so-called throat diameter is the diameter when the cross-sectional area of the nozzle hole of the nozzle portion is the smallest, and oxygen is used as the oxygen-containing gas, and quicklime powder is used as the powder raw material. A test was performed in which the quicklime powder having a particle size of 5 to 200 μm was intermittently supplied at a rate of 3.0 Nm ³ / min at a rate of 5.5 kg / min for a total of 20 hours to pass the gas and powder through the nozzle holes.

(2) L / L ₀ and the relationship between the amount of wear of the abrasion test shows the relationship of the nozzle in each nozzle of L / L ₀ and the amount of wear of the nozzle after the abrasion test in FIG. The smaller the L / L _{0 is, the} smaller the nozzle wear is, but especially in the area of L / L ₀ <0.2, the smaller the L / L _{0 is, the} larger the wear of the inner wall surface of the nozzle hole in the opposite direction is. When it is about 0.19 ≦ L / L ₀ ≦ 0.82, compared with the case where L / L ₀ = 1.0, the wear amount of the nozzle is less than half. Based on the above review, the preferred range for implementing the present invention is as shown in formula (1), which is 0.19 ≦ L / L ₀ ≦ 0.82. In addition, in order to more surely suppress abrasion, 0.35 ≦ L / L ₀ ≦ 0.70 is preferable.

Next, a method for refining molten iron will be described. The method for refining molten iron according to the present invention is mainly carried out by using the converter of the present invention for refining when the powder auxiliary material is sprayed together with pure oxygen, that is, an oxygen-containing gas, into the molten iron loaded into the converter to perform molten iron refining. Use a top blow spray gun. In the method for refining molten iron according to the present invention, the molten iron charged into the converter is prepared whether or not it has been prepared. In addition, regardless of the components of the molten iron after the refining is performed, the refining may be a so-called molten iron pre-dephosphorization treatment, or molten steel may be manufactured by the refining. Furthermore, the powder by-products are not limited to dephosphorizing agents such as quicklime, limestone, and calcium ferrite, and may be slag-promoting materials such as bauxite or rutile minerals, and iron. Minerals, minerals such as Mn minerals, or mixtures of these.

The spraying flow rate of the oxygen-containing gas, the particle size and the addition amount of the powder auxiliary raw materials may be carried and stably carried out and sprayed according to the purpose of refining the molten iron. The top-blowing spray gun for converter blowing in the present invention can suppress the problem of nozzle wear associated with the supply of powder more than the conventional top-blowing spray gun in any condition, which helps stabilize the operation and reduces the frequency of spray gun replacement. And contribute to the improvement of productivity. [Example]

Next, although the embodiment of the present invention is described, the conditions in the embodiment are an example of a condition adopted for confirming the feasibility and effect of the present invention, and the present invention is not limited to the example of the condition. As long as the present invention is not deviated from the gist of the present invention, various conditions can be adopted while achieving the purpose of the present invention.

A 300t top-to-bottom blowing converter was used for preliminary dephosphorization melting of molten iron. At this time, the main raw materials used about 260 tons of molten iron containing C: 4.4 to 4.5%, Si: 0.2 to 0.5%, Mn: 0.2 to 0.4%, and P: 0.100 to 0.130%, and about 20 tons of waste materials were used. . Let the top-blown oxygen flow rate be 3.0Nm ³ / min per 1t of molten iron. The powder raw material is to make a quick lime powder with a particle size of 5 ~ 200μm as the top-blown speed of 900kg / min, and the bottom-blown CO ₂ flow rate is 0.25Nm. ³ / min. By this dephosphorization blowing, molten iron having a mass concentration of C: 3.6 to 3.8%, Si ≦ 0.01%, Mn: 0.1 to 0.2%, and P: 0.015 to 0.025% was produced. In this test, the relationship between the number of blows and the L / L ₀ that caused the leakage of the cooling water flow path inside the spray gun due to nozzle wear was investigated.

Top-blowing lance condition is to make the diameter within the barrel of of 180mm, so that the throat diameter of 45mm, so that the number of holes of the nozzle 4, the nozzle inclination angle is fixed at 20 °, making change L / L _top-0-blown lance, using Yu Bing. Table 1 below shows L / L ₀ and abrasion index. Here, the abrasion index is an indexed value when the top-blowing lance of Comparative Example 1 is used for blowing until the number of blows for which the aforementioned water leakage occurs is 1.

[Table 1]

First, Comparative Examples 1 and 2 will be described. Compared with Comparative Example 1, the wear index of Comparative Example 2 is smaller. This is because the L / L ₀ of the top-blowing lance of Comparative Example 2 is small. Next, Examples 1 to 4 will be described. The wear index of Examples 1 to 4 was less than half as compared with Comparative Example 1. This is because L / L ₀ ≦ 0.82 is satisfied, and the proportion of “powder that directly penetrates into the nozzle hole without colliding with the wall of the inner tube of the spray gun” has been reduced. In addition, the L / L ₀ of Example 2 is smaller than that of Example 1, but no significant difference from the abrasion index of Example 1 is observed. In addition, Examples 1 and 2 suppress wear more than Examples 3 and 4, respectively.

On the other hand, the wear index of Comparative Example 3 is larger than that of Examples 1 to 4. This is because by making L / L ₀ smaller than 0.19, the flow of gas and powder in the nozzle hole is deviated. From the above, it can be confirmed that by setting 0.19 ≦ L / L ₀ ≦ 0.82, the abrasion of the inner wall surface of the nozzle hole caused by powder can be suppressed, and further by setting 0.35 ≦ L / L ₀ ≦ 0.70, it can be more suppressed Wear of the inner wall surface. Industrial availability

According to the present invention, it is possible to suppress abrasion of the nozzle caused by the top blowing of the oxygen-containing gas and the powder auxiliary material, and to lengthen the wear-resistant life of the refining spray gun. Therefore, the value of industry is great.

1‧‧‧Top Blow Gun

2‧‧‧Inner tube of spray gun

2a‧‧‧flow

2b‧‧‧Inner wall surface

2c‧‧‧Border

2c’‧‧‧ boundary

2d‧‧‧ spray gun central axis

3‧‧‧ Nozzle section

3a‧‧‧Nozzle hole

3c‧‧‧Nozzle central axis

4‧‧‧ boundary surface

5‧‧‧Top blowing spray gun

6a‧‧‧flow

6d‧‧‧ spray gun central axis

7a‧‧‧Nozzle hole

7b‧‧‧Inner wall surface

7c‧‧‧Nozzle central axis

8‧‧‧ boundary surface

9‧‧‧Top Blow Gun

10a‧‧‧flow

10b‧‧‧Inner wall surface

10c‧‧‧Border

10c’‧‧‧ boundary

10d‧‧‧ spray gun central axis

11a‧‧‧Nozzle hole

11b‧‧‧Inner wall surface

11c‧‧‧Nozzle central axis

13‧‧‧ cross section

14‧‧‧ projection surface

15‧‧‧ cross section

16‧‧‧ cross section

17‧‧‧ projection surface

A‧‧‧Straight

B‧‧‧ cross section

C‧‧‧Segment

L‧‧‧ length

L ₀ ‧‧‧ length

FIG. 1 is a diagram for explaining the length L _{0 of the} cross-sectional line segment B and the length L of the line segment C. FIG. Fig. 2 is a schematic cross-sectional view of a front end portion of the porous spray gun. FIG. 3 is a graph showing changes in abrasion coefficients due to differences in L / L ₀ .

Claims (2)

A top-blowing spray gun for converter blowing is used when a molten iron is charged into a top-bottom blowing converter, and a powder auxiliary material is sprayed together with an oxygen-containing gas from the top-blowing spray gun to the molten iron for blowing. The top-blowing spray gun for converter blowing is characterized in that: the inner tube of the spray gun has the flow path of the oxygen-containing gas and the powder auxiliary raw material; and a nozzle portion is extended to communicate with the flow path of the inner tube of the spray gun, And there are nozzle holes with more than 2 holes, the nozzle central axis of the nozzle hole is inclined with respect to the central axis of the spray path of the flow path, and the nozzle holes respectively satisfy the following formula (1): 0.19 ≦ L / L ₀ ≦ 0.82. .. (1) Here, L ₀ : In a cross section that includes the central axis of the spray gun and bisects the boundary surface of the spray gun inner tube and the boundary surface of the nozzle hole, passes the most of the spray gun on the boundary surface. The point of the downstream side and the length of the line segment of the nozzle hole on a straight line perpendicular to the central axis of the spray gun, L: within the range of the flow path of the inner pipe of the spray gun, the line segment of the cross section is perpendicular to When the cross section of the central axis of the spray gun is projected, The length of the line segment shadowed to the aforementioned cross section. A method for refining molten iron is a method for refining molten iron that is blown with a top-blowing lance using a top-blowing lance for converter blowing according to claim 1, characterized in that: the molten iron is charged into a top-bottom blowing converter, and from the foregoing converter The top-blowing lance for blowing sprays powder auxiliary materials together with oxygen-containing gas onto the molten iron to perform blowing.