JP5974596B2 - Tuyere block - Google Patents

Description

  The present invention relates to a tuyere block that constitutes a nozzle for blowing gas into molten metal in a furnace for refining molten metal, such as an upper-bottom blowing converter.

  When refining molten metal, gas may be blown into the furnace for the purpose of promoting reaction by stirring. For example, an inert gas such as argon or nitrogen may be blown from the bottom of the container, such as when removing pig iron carbon in a converter in the steel industry. As one type of tuyere, iron and steel 68 (1982) 4, S200 discloses a tuyere block structure in which a plurality of pipes are embedded in a refractory. The tuyere of this structure is excellent in the downward elasticity of the gas flow rate, and is used in converters for commercial production.

  The tuyere block (nozzle) of the bottom-blowing converter, which constitutes the tuyere, has a structure as described in Patent Document 1 and Patent Document 2, for example. This conventional tuyere block (nozzle) is constructed by embedding a plurality of pipes constituting a gas flow path in a refractory with the axis thereof vertically oriented, and the plurality of pipes are viewed from the gas blowing direction (upward In view of this, they are arranged at regular intervals or substantially regular intervals within a predetermined gas blowing region including the center of the tuyere block. That is, many of the conventional tuyere blocks are set so that all the gas flow paths are arranged at equal intervals in one gas blowing region as viewed from the gas blowing direction.

JP 59-153818 A Japanese Utility Model Publication No. 62-17463

Here, suppression of the wear rate of the tuyere block is desired from a manufacturing cost reduction. In addition, there is a demand to increase the flow rate of bottom blowing gas due to demands such as shortening of refining time and a large amount of scrap, and reduction of the wear rate of tuyere blocks corresponding to this demand is also desired.
As a result of the study by the present inventors, in the configuration in which a plurality of gas flow paths are arranged at equal intervals in one gas blowing region as in the above-described prior art, the inside of the tuyere block increases as the gas flow rate increases. The thermal gradient generated in the tuyere block is increased due to an increase in the temperature gradient, which increases the wear rate.
An object of the present invention is to propose a tuyere block capable of further reducing the wear rate.

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention includes a plurality of metal thin tubes for injecting gas into molten metal in a furnace and is integrally press-molded with a carbon-containing refractory. A tuyere block,
In the gas blowing surface of the tuyere block in plan view, which is a plane seen from the inside of the furnace in the direction along the axial direction of the metal thin tube, the gas blowing surface of the tuyere block disposed in the furnace,
The maximum area surrounded by the line segment connecting the center positions of the plurality of metal thin tubes is defined as a tuyere existence area, the smallest circle including the whole tuyere existence area is defined as a reference circle, and the reference circle And an inner inner tuyere including the tuyere existing region on the circumference of the circle having the radius of 2/3, with the circumference of the circle having a radius of 2/3 of the radius of the reference circle as a boundary. Virtually divided into two areas, an existing area and an outer tuyere existing area outside the circumference,
The area of the inner tuyere existing area is TAi, the area of the outer tuyere existing area is TAo,
GAi is the total gas flow path cross-sectional area of the metal thin tubes included in the inner existence area at the center position, and GA gas is the cross-sectional area of the metal thin tubes included in the outer existence area at the center position. When the total gas flow path cross-sectional area is GAo, the following formula (1) is satisfied by adjusting at least the distance between the metal thin tubes among the gas flow path cross-sectional area of the metal thin tubes and the interval between the adjacent metal thin tubes. It is characterized by doing.
0.1 ≦ (GAo / TAo) / (GAi / TAi) ≦ 0.8
... (1)
Here, the “gas blowing surface of the tuyere block in plan view” is substantially the same as a cross section perpendicular to the metal tube group inside the furnace of the tuyere block (for example, within 1 cm from the gas blowing surface).

Next, the invention described in claim 2 is the configuration described in claim 1, wherein the area of the tuyere existing region is 0.15 or more of the area of the gas blowing surface of the tuyere block in the plan view. .8 or less in area.
Next, the invention described in claim 3 is characterized in that the following expressions (2) and (3) are further satisfied with respect to the configuration described in claim 1 or claim 2.
0.004 ≦ (GAo / TAo) ≦ 0.08 (2)
0.01 ≦ (GAi / TAi) ≦ 0.15 (3)

Next, the invention described in claim 4 is the structure described in any one of claims 1 to 3, wherein the plurality of metal thin tubes are inner layers arranged on the center side of the tuyere block. A metal thin tube group, and an outer layer metal thin tube group disposed on the outer peripheral side of the inner metal thin tube group so as to surround the outer periphery of the inner metal thin tube group,
The inner-layer metal thin tube group and the outer-layer metal thin tube group are separated from each other by a distance of three or more times the distance between the center positions of adjacent metal thin tubes in the metal thin tube constituting the inner-layer metal thin tube group, and the outer-layer metal thin tube group The gas channel cross-sectional area by the thin tube group is smaller than the gas channel cross-sectional area by the inner metal thin tube group.
Next, the invention according to claim 5 is characterized in that, in the configuration according to any one of claims 1 to 4, the plurality of metal thin tubes have a tube diameter of 4 mm or less in inner diameter. To do.

According to the present invention, the tuyere existence region is divided into an inner region and an outer region, and the relationship between the gas flow path cross-sectional area ratios in the respective regions is defined, and the metal capillaries are arranged. The temperature gradient in the tuyere block in the direction from the center side of the mouth block toward the outer peripheral side (cross section perpendicular to the metal thin tube group) can be made gentler than before.
As a result, the wear rate of the tuyere block can be further reduced. This makes it possible to operate with an increased gas flow rate, for example.

It is a conceptual diagram explaining a bottom blow converter. It is a figure explaining the pipe (gas flow path) in a tuyere block. It is a figure which shows the example of the conventional pipe arrangement | positioning. It is a figure which shows the example of arrangement | positioning of the pipe which concerns on embodiment based on this invention. It is a figure which shows the example of arrangement | positioning of another pipe which concerns on embodiment based on this invention. It is a figure explaining one of the effect | actions of this embodiment.

Next, an embodiment according to the present invention will be described with reference to the drawings.
In the present embodiment, an upper bottom blowing converter will be described as an example of a furnace that employs the tuyere block 1 of the present invention. However, the tuyere block 1 of the present invention is applicable to any furnace other than the top-bottom converter, as long as it is a furnace that blows gas into the molten metal.

(Constitution)
In the top-bottom blow converter, oxygen gas for decarburization and refining is blown from the top blow lance, and the molten iron 5 is stirred by blowing a stirring gas from the tuyere block 1 provided at the bottom of the furnace, as shown in FIG. While decarburizing and refining. The tuyere block 1 is attached to the furnace bottom brick 2 of the furnace bottom via the tuyere receiving brick 6. A plurality of the tuyere blocks 1 are usually installed, but in FIG. As shown in FIG. 2, the tuyere block 1 integrally forms the carbon-containing refractory 4 together with a plurality of thin metal tubes 3 into a cylindrical shape or a truncated cone shape having a diameter of about 0.2 m by a method such as isostatic pressing. The tuyere block 1 is configured by press molding, and is used to blow a stirring gas (CO ₂ , Ar, N _2, etc.) into the molten iron 5 (molten metal) in the furnace through the plurality of metal thin tubes 3. .

The plurality of thin metal tubes 3 are arranged with their axes facing up and down to form a gas flow path, and open to the upper surface (gas blowing surface) of the carbon-containing refractory 4 constituting the tuyere block 1, respectively. Configure the exit. The diameter of each of the metal thin tubes 3 may be a stainless steel tube made of stainless steel having an inner diameter of 4 mm or less, more preferably 3 mm or less. In addition, the metal thin tube 3 may be coated with an oxide-based refractory material for the purpose of preventing carburization from the carbon-containing refractory 4. In addition, the gas blowing surface which is the upper surface of the tuyere block 1 is always in contact with the molten iron 5 in the furnace during refining.
In the present embodiment, on the upstream side (lower side) of the plurality of metal thin tubes 3, a wind box 7 for distributing gas to the plurality of metal thin tubes 3 is provided for each tuyere block. And are provided as one. The wind box 7 of each tuyere block is connected to a gas supply path.

Next, the arrangement of the plurality of metal thin tubes 3 (gas flow paths) or the distribution of gas flow rates will be described.
In the conventional tuyere block 1, when viewed from the gas blowing direction (above), for example, as shown in FIG. 3, on the gas blowing surface (upper surface of the tuyere block) arranged in the furnace, on the center side One blowing area is set, and the openings of the plurality of thin metal tubes 3 are evenly arranged in the blowing area.
On the other hand, in this embodiment, the gas blowing surface disposed in the furnace is a direction along the axial direction of the metal thin tube and the plane viewed from the inside of the furnace, that is, a plane viewed from above (plane in plan view). The arrangement (distribution) of a plurality of metal thin tubes is defined on the upper surface of a tuyere block 1 as follows.

  That is, as shown in FIG. 4, on the upper surface of the tuyere block 1, the maximum region surrounded by the line segment connecting the center positions of the plurality of metal thin tubes is defined as a tuyere existing region. Here, the tuyere existence region is a region surrounded by the boundary line 10 including the boundary line 10. The minimum circle including the entire tuyere existence region is defined as a reference circle 8. The above-described tuyere existence area is virtually divided into two areas of an inner tuyere existence area and an outer tuyere existence area by a circle 9 that is concentric with the reference circle 8 and has a radius that is 2/3 of the radius of the reference circle 8. Divide into And, the inner tuyere existence area (area including the circumference within the circle 9) and the outer tuyere existence area (area including the boundary line 10 outside the circle 9 and inside the boundary line 10). The openings of the plurality of metal thin tubes 3a and 3b are arranged in the inner tuyere existing region and the outer tuyere existing region so as to change the ratio of the gas flow path cross-sectional area to the area of each region.

In this embodiment, the area of the inner tuyere existence area is TAi, the area of the outer tuyere existence area is TAo, and the gas channel cross-sectional area of the metal capillaries whose center position is included in the inner existence area is totaled. When the total gas channel cross-sectional area is GAi and the total gas channel cross-sectional area obtained by adding up the gas channel cross-sectional areas of the metal capillaries whose center positions are included in the outer region is GAo, the gas channel cross-sectional area ratio The arrangement of the plurality of metal thin tubes is determined so that (outer / inner) H (= (GAo / TAo) / (GAi / TAi)) satisfies the following expression (1).
The metal thin tube whose center position is located on the circumference of the circle 9 is a metal thin tube in the inner tuyere existence region.
0.1 ≦ H ≦ 0.8
However, H = (GAo / TAo) / (GAi / TAi)
... (1)
In the conventional example shown in FIG. 3, the gas channel cross-sectional area ratio (outside / inside) H was 1.7.

  Further, in the embodiment of the present invention shown in FIG. 4, the number of the metal thin tubes 3a arranged in the inner tuyere existing region is 61, and 61 in the central portion in the case of the conventional example shown in FIG. The arrangement is the same as that of the metal thin tube 3, and the arrangement of the 30 metal thin tubes 30 b outside the circle 9, that is, in the outer tuyere existing region is changed to the outside to reduce the outer gas channel cross-sectional area ratio. Thus, the gas channel cross-sectional area ratio (outside / inside) H is reduced from 1.7 in the case of FIG. 3 to 0.57.

  Moreover, in this embodiment, since all the metal thin tubes are connected to one wind box 7 for each tuyere block, the outer tuyere existence region (the region between the circle 9 and the boundary line 10) described above is used. ) And the inner tuyere existence area (area in the circle 9), the gas flow rate blown from each area is distributed according to the total gas flow path cross-sectional area. Therefore, as described above, in the outer tuyere existing region (the region between the circle 9 and the boundary line 10), the gas channel cross-sectional area per area is larger than that in the inner tuyere existing region (the region in the circle 9). Since the gas flow rate per area is also reduced, the outer tuyere existence area (area between the circle 9 and the boundary line 10) is the inner tuyere existence area (area within the circle 9). Smaller than that.

  In the present embodiment, the area of the tuyere existing area (area of the area surrounded by the boundary line 10) is a ratio (the tuyere existing area area ratio) to the area of the gas blowing surface (upper tuyere upper surface) in plan view. ) Is preferably in the range of 0.15 to 0.8. In the case of the conventional example shown in FIG. 3, the area ratio of the tuyere existing area is 0.16. However, in the embodiment of the present invention shown in FIG. 4, the area ratio of the tuyere existing area is shown in FIG. Compared to the conventional example, it is increased to 0.28. However, the present invention can be implemented so as to satisfy the present invention by adjusting the distribution of the metal thin tubes 3a and 3b in the region without changing the tuyere existing region.

About arrangement | positioning of a some metal thin tube, it is further preferable to satisfy the following (2) Formula and (3) Formula.
0.004 ≦ (GAo / TAo) ≦ 0.08 (2)
0.01 ≦ (GAi / TAi) ≦ 0.15 (3)
(GAo / TAo) is the outer tuyere of the total gas flow path cross-sectional area of the metal thin tube 3b whose central axis is included in the outer tuyere existing region (the region between the circle 9 and the boundary line 10). It is a ratio (outside gas flow path cross-sectional area ratio) to the area of the existing region (region between the circle 9 and the boundary line 10).
(GAi / TAi) is the inner tuyere existing region (inside circle 9) of the total gas channel cross-sectional area of the metal thin tube 3a whose central axis is included in the inner tuyere existing region (inside circle 9). Is a ratio (inner gas flow path cross-sectional area ratio) to area.

  In the embodiment of the present invention shown in FIG. 4, the outer gas channel cross-sectional area ratio (GAo / TAo) is 0.028, and the inner gas channel cross-sectional area ratio (GAi / TAi) is 0.00. It is adjusted to 049. As with the example shown in FIG. 4, the method of adjusting the arrangement of the metal thin tubes and the method of adjusting the inner diameter of the metal thin tubes according to the position of the metal thin tubes to be arranged also provide a gas flow path cross-sectional area for implementing the present invention. Can be adjusted.

  In this embodiment, the tuyere block is integrally pressed into a columnar shape or a truncated cone shape by using a uniform carbon-containing refractory material (magnesia, carbon brick, etc.) including a metal thin tube for gas blowing. An example using a molded product has been described. In some cases, the tuyere block is molded into a large brick so as to include the tuyere block. Even in such a use example, only the part that is first integrally formed including the metal thin tube is handled as the tuyere block in the present invention. Further, after coating a metal thin tube for gas blowing with an oxide-based refractory material, it may be integrally pressed with a carbon-containing refractory so as to include this, and a tuyere block may be formed. Included in the category of tuyere blocks that are press-molded together.

  Also, FIG. 5 shows between the inner metal tube group existing in the inner tuyere existing region and the outer metal tube group existing so as to surround the outer periphery of the inner metal tube group in the outer tuyere existing region. As described above, it is also preferable to set a region where no tuyere exists so as to satisfy the following relationship. That is, the shortest distance L1 between the metal thin tube 3a located in the inner tuyere existing region, that is, the inner metal thin tube group, and the metal thin tube 3b in the outer tuyere existing region, that is, the outer metal thin tube group, is the inner metal thin tube group. Is set to be at least three times the interval ΔL between the minimum center positions between adjacent metal capillaries. That is, the closest distance L1 between the metal capillaries 3a arranged in the inner tuyere existing region and the metal capillaries 3b arranged in the outer tuyere existing region is defined as the distance between adjacent metal capillaries in the inner metal tube group. Is set to a distance that is at least three times the distance ΔL between the minimum center positions. For example, the width of the region where there is no tuyere is set to be three times or more the interval between the center positions of the adjacent openings in the inner metal thin tube group. The width is a distance in the radial direction (radial direction) centered on the center of the upper surface of the tuyere block 1.

(About other functions)
The inventors considered that the wear of the bottom-blown tuyere proceeds due to crack generation, extension, and peeling due to thermal stress in the tuyere, and focused on the temperature distribution in the tuyere block.
That is, in the refractory constituting the tuyere block, the portion in contact with the metal thin tube (gas flow path) is cooled by gas blowing, while the other portion receives heat from the molten iron and transfers from the adjacent furnace bottom brick. High temperature due to heat. In the above-described conventional arrangement of metal thin tubes (see FIG. 3), the metal thin tubes 3 are arranged concentrated on the center side, so that the center side is cooled and the outer peripheral side becomes high temperature. Then, as the gas flow rate supplied to the molten iron is increased, the cooling effect in the vicinity of the thin metal tube 3 is increased, and the flow velocity of the accompanying flow of the molten iron 5 at the outer periphery of the outermost layer of the gas blowout is also as shown in FIG. As a result, the heat receiving on the outer peripheral side also increases. As a result, the temperature gradient in the direction from the center side to the outer periphery side in the tuyere block 1 increases, and the thermal stress increases. In addition, the slag coating on the brick near the tuyere block is also peeled off or thinned, and the heat receiving surface of the brick working surface (contact surface with molten iron) becomes larger.

  On the other hand, as a result of intensive studies and experiments on the method for reducing the thermal stress as described above, the inventors divided the existence region of the metal thin tube in the tuyere block into two regions, an outer side and an inner side. By arranging the metal thin tubes so that the ratio of the cross-sectional area ratio of the gas channel to the inside is within the proper range, the temperature gradient in the tuyere block is reduced to reduce the thermal stress, thereby reducing the tuyere wear rate. It has been found that it is possible to increase the gas blowing speed while suppressing the increase.

  That is, the gas flow path in the outer tuyere existence region is bounded by a circle 9 that is concentric with the smallest circle (reference circle 8) including the entire tuyere existence region (region surrounded by the boundary line 10) and has a radius 2/3. Heat transfer between the blown gas and the tuyere bricks in the outer tuyere existing area by suppressing the cross-sectional area so that it is in the range of 0.1 to 0.8 times that of the inner gas channel. By relatively reducing the area, cooling of the tuyere block in the outer tuyere existing region can be mitigated. Further, since the gas blowing speed from the outer tuyere existing region is also relatively reduced, as shown in FIG. 6B, an increase in the flow velocity of the accompanying flow of molten iron on the outer periphery of the outermost layer of the gas blowing is suppressed. As a result, the heat transfer coefficient on the upper surface of the tuyere block is reduced, and heat input to the tuyere block is reduced. These effects reduce the temperature gradient in the tuyere block and reduce the generated thermal stress.

  Here, if the ratio H of the gas channel cross-sectional area ratio between the outer side and the inner side is larger than 0.8, the effect of reducing the temperature gradient is small, and the effect of suppressing the tuyere wear cannot be sufficiently obtained. On the other hand, if it is smaller than 0.1, the heat load on the outermost metal thin tube increases, and the tuyere wear rate increases due to softening or melting of the tip. Further, from the viewpoint of increasing the gas blowing speed from the same whole tuyere existing area, it is desirable to distribute a certain amount of gas to the outer tuyere existing area. For this reason, the ratio H of the gas channel cross-sectional area ratio between the outer side and the inner side is preferably in the range of 0.1 to 0.8, and the ratio H is more preferably in the range of 0.2 to 0.6.

  In addition, the ratio of the tuyere existing area to the gas blowing surface of the tuyere block (upper surface 1 of the tuyere block) (the area ratio of the tuyere existing area) is preferably in the range of 0.15 to 0.8. The area ratio of the tuyere existing region is more preferably in the range of 0.2 to 0.6. If the ratio is larger than 0.8 times, the distance between the side surface of the tuyere block and the metal capillaries on the outer peripheral portion is too small, and there is a risk that defects will occur during molding, and the particle diameter of the raw material used may be restricted. In addition, a thermal stress is generated in the vicinity of the side surface of the tuyere block, and there is a problem that the tuyere wear rate increases because the probability that the crack does not stay inside but communicates with the side surface and leads to breakage increases. On the other hand, if it is smaller than 0.15 times, the metal thin tubes are too dense in the central portion and the effect of relaxing the cooling is small, and the effect of suppressing the tuyere wear cannot be sufficiently obtained.

  The gas channel cross-sectional area ratio (GAo / TAo) in the outer tuyere existing region is preferably in the range of 0.004 to 0.08, and more preferably in the range of 0.01 to 0.05. If the outer gas channel cross-sectional area ratio (GAo / TAo) is greater than 0.08, the effect of reducing the temperature gradient is small, and the effect of suppressing tuyere wear cannot be sufficiently obtained. On the other hand, when it is smaller than 0.004, the heat load on the outermost metal thin tube increases, and the tuyere wear rate increases due to softening or melting of the tip. In order to increase the gas blowing speed under a condition where the tuyere exists in a constant region, it is desirable to provide a certain amount of gas channel cross-sectional area within the above range also in the outer tuyere existing region. Further, the gas channel cross-sectional area ratio (GAi / TAi) in the inner tuyere existing region may be determined mainly according to the target value of the gas blowing speed per tuyere block, but is 0.01 or more and 0.15 or less. Is a preferable range, and a range of 0.02 to 0.12 is more desirable. If the inner gas channel cross-sectional area ratio (GAi / TAi) is greater than 0.15, the cooling at the center of the tuyere block is excessive and a large thermal stress is generated, so that the tuyere wear rate tends to increase. If it is smaller than 0.01, it is necessary to install a large number of tuyere blocks in order to secure a necessary gas blowing speed, which is not efficient.

As described above, by suppressing the gas flow rate from the outer tuyere existing region relatively compared to the inner tuyere existing region, it is possible to suppress an increase in the flow velocity of the hot metal accompanying flow at the outer periphery of the outer layer of the gas blowing. Even if the gas flow rate from the inner tuyere existing region is increased, the influence on the flow velocity of the accompanying flow of the molten iron is small.
At this time, by arranging the plurality of metal thin tubes 3b arranged in the outer tuyere existing region so as to surround the inner tuyere existing region, the flow velocity of the accompanying flow around the outermost circumference can be reduced. At this time, the embodiment of the present invention shown in FIG. 4 is an example in which the distribution density of the metal tubules is gently changed from the inner tuyere existing region to the outer tuyere existing region. Thus, the same effect can be obtained even if the outer metal thin tube group is arranged so as to be separated from the inner metal thin tube group.

  Here, the total number of metal thin tubes and the diameter of each metal thin tube are determined by the required bottom blowing gas flow rate, gas pressure, etc., but the metal thin tubes may be arranged on the inner layer side as necessary. The inner diameter of the metal thin tube is desirably 4 mm or less from the viewpoint of preventing molten iron from entering when the gas flow rate is reduced.

Using the N ₂ gas or Ar gas, which is an inert gas, as the gas blown from the tuyere block 1, the tuyere block of the example having the metal thin tube arrangement according to the present embodiment and the metal thin tube arrangement outside the present invention A tuyere block of a certain comparative example was installed at the bottom of an upper-bottom blow converter, and a commercial converter experiment (the amount of molten iron was 250 tons) was performed.
The case of the conventional metal thin tube arrangement shown in FIG. 3 was set as Comparative Example 1, and the average wear rate of the tuyere was measured and evaluated for Examples and Comparative Examples in which the arrangement and inner diameter of the metal thin tubes were variously changed. Table 1 shows the main conditions and evaluation results of each example and comparative example. The total gas flow path cross-sectional area ratio described in Table 1 indicates the total gas flow path cross-sectional area per tuyere block as a ratio based on the case of Comparative Example 1. The shape of the tuyere block was set equal in all examples and comparative examples.

  Examples 1 to 8 and Comparative Examples 2 and 3 are examples in which the total gas flow path cross-sectional area per tuyere block is substantially equal to that of Comparative Example 1, and the gas blowing speed per tuyere block in the converter operation is It was equal to the case of Comparative Example 1. Examples 9 to 11 and Comparative Examples 4 to 6 are examples in which the inner diameter of the metal thin tube is enlarged to make the total gas flow path cross-sectional area per tuyere block approximately twice that of Comparative Example 1, and in the converter operation The gas blowing speed per tuyere block was about twice that in Comparative Example 1 in order to improve the refining reaction characteristics. Since the influence of the gas blowing speed on the tuyere wear rate is generally large, the tuyere block according to the present invention has the effect of reducing the tuyere wear rate compared to the examples and comparative examples having the same gas blowing speed. evaluated.

Examples 6 and 7 are examples of the arrangement of metal thin tubes shown in FIGS. 4 and 5, respectively. Examples 1 to 5 and Comparative Examples 2 and 3 further expand the range in which the metal thin tubes are arranged compared to FIG. This is an example in which the area ratio is in the range of 0.51 or more and 0.55 or less, and by adjusting the distribution of the metal capillaries in the tuyere existing area, the gas channel cross-sectional area ratio and the inner area in the outer tuyere existing area are adjusted. The gas channel cross-sectional area ratio in the tuyere existence region is changed. In Examples 1 to 7 and Comparative Examples 2 and 3, the inner diameter and the total number of the tubes are made equal to those of Comparative Example 1. In Example 8, while keeping the tuyere existing area equal to that of Comparative Example 1, the inner diameter of the metal thin tube was enlarged, and the number of metal thin tubes belonging to the outer tuyere existing area was reduced, so that the total gas channel cross-sectional area was reduced. The gas channel cross-sectional area ratio in the outer tuyere existing area and the gas channel cross-sectional area ratio in the inner tuyere existing area are changed while being substantially the same as in Comparative Example 1.
Of Examples 9 to 11 and Comparative Examples 4 to 6 in which the total gas channel cross-sectional area is approximately twice that of Comparative Example 1, Comparative Example 4 is an example in which the metal thin tube arrangement shown in FIG. The other is an example in which the arrangement of the metal thin tubes is adjusted in the tuyere existence region shown in FIG.

Here, in Table 1, as shown in FIG. 3, the wear rate ratio is a relative evaluation in which the wear rate in Comparative Example 1 in which the pipe 3 is uniformly arranged with respect to one blowing region on the upper surface of the tuyere block is 1. Is described.
As can be seen from Table 1, in Examples 1 to 8 in which the gas flow channel area ratio ratio (GAo / TAo) / (GAi / TAi) is set within the scope of the present invention, the wear rate is higher than that of Comparative Examples 1 to 3. As can be seen from FIG. Also, in Examples 9 to 11 in which the gas blowing rate was increased, the tuyere wear rate was reduced by about 30 to 40% compared to Comparative Examples 4 to 6, and Comparative Example 1 with about half the gas blowing rate and Since the wear rate is comparable, it can be seen that the tuyere wear suppression effect of the tuyere block of the present invention is also effective when the gas blowing rate is increased.

  In addition, although the wear rate ratio of Example 11 is slightly higher than that of Comparative Example 1, this is due to the fact that the gas blowing rate has been doubled in order to improve the refining reaction characteristics, and the same gas When compared with the blowing speed, the effect of reducing the wear rate from the arrangement of the thin metal tubes in FIG. 3 is greater than those of Comparative Examples 2 and 3 or Comparative Examples 5 and 6. Example 11 shows that the gas blowing rate can be increased while keeping the wear rate ratio close to that of Comparative Example 1. In Comparative Examples 1 to 3, gas is blown under conditions close to the maximum pressure for improving the equipment capacity, and the gas blowing speed cannot be increased significantly with the same tuyere block. Moreover, if the gas blowing speed of Example 11 is brought close to Comparative Example 1, the wear rate ratio of Example 11 becomes a value smaller than that of Comparative Example 1.

1 Tuyere block 2 Furnace bottom bricks 3, 3a, 3b Metal capillaries 4 Carbon-containing refractories 5 Molten iron 6 Tuyere receiving bricks 7 Wind box 8 Reference circle 9 Circle concentric with reference circle and radius 2/3 10 Region border

Claims (5)

A tuyere block that includes a plurality of thin metal tubes for blowing gas into the molten metal in the furnace, and is integrally press-molded with a carbon-containing refractory,
In the gas blowing surface of the tuyere block in plan view, which is a plane seen from the inside of the furnace in the direction along the axial direction of the metal thin tube, the gas blowing surface of the tuyere block disposed in the furnace,
The maximum area surrounded by the line segment connecting the center positions of the plurality of metal thin tubes is defined as a tuyere existence area, the smallest circle including the whole tuyere existence area is defined as a reference circle, and the reference circle And an inner inner tuyere including the tuyere existing region on the circumference of the circle having the radius of 2/3, with the circumference of the circle having a radius of 2/3 of the radius of the reference circle as a boundary. Virtually divided into two areas, an existing area and an outer tuyere existing area outside the circumference,
The area of the inner tuyere existing area is TAi, the area of the outer tuyere existing area is TAo,
GAi is the total gas flow path cross-sectional area of the metal thin tubes included in the inner existence area at the center position, and GA gas is the cross-sectional area of the metal thin tubes included in the outer existence area at the center position. When the total gas flow path cross-sectional area is GAo, the following formula (1) is satisfied by adjusting at least the distance between the metal thin tubes among the gas flow path cross-sectional area of the metal thin tubes and the interval between the adjacent metal thin tubes. A tuyere block characterized by
0.1 ≦ (GAo / TAo) / (GAi / TAi) ≦ 0.8
... (1)   2. The tuyere block according to claim 1, wherein an area of the tuyere existence region is an area of 0.15 or more and 0.8 or less of a gas blowing surface area of the tuyere block in the plan view. Furthermore, the following (2) Formula and (3) Formula are satisfied, The tuyere block of Claim 1 or Claim 2 characterized by the above-mentioned.
0.004 ≦ (GAo / TAo) ≦ 0.08 (2)
0.01 ≦ (GAi / TAi) ≦ 0.15 (3) The plurality of metal capillaries include an inner layer metal tube group disposed on the center side of the tuyere block and an outer layer disposed on the outer periphery side of the inner layer metal tube group so as to surround the outer periphery of the inner layer metal tube group. A group of metal tubules,
The inner-layer metal thin tube group and the outer-layer metal thin tube group are separated from each other by a distance of three or more times the distance between the center positions of adjacent metal thin tubes in the metal thin tube constituting the inner-layer metal thin tube group, and the outer-layer metal thin tube group The tuyere block according to any one of claims 1 to 3, wherein a cross-sectional area of the gas flow path by the thin tube group is smaller than a cross-sectional area of the gas flow path by the metal thin tube group of the inner layer. The tuyere block according to any one of claims 1 to 4, wherein each of the plurality of thin metal tubes has a tube diameter of 4 mm or less.

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