WO2021177101A1

WO2021177101A1 - Integrated tuyere for converter

Info

Publication number: WO2021177101A1
Application number: PCT/JP2021/006825
Authority: WO
Inventors: 竹内　和彦; 泰治枝本
Original assignee: 黒崎播磨株式会社
Priority date: 2020-03-04
Filing date: 2021-02-24
Publication date: 2021-09-10
Also published as: JP2021138997A; EP4071254A1; JP6691643B1; TWI773163B; EP4071254A4; CN114502749A; TW202202630A; BR112022011368A2

Abstract

The present invention provides an integrated tuyere for a converter, in which one double metal tube and a tuyere refractory are integrated, said integrated tuyere having a simple structure and suppressing deformation of the double metal tube upon installation in a converter and during handling and a reduction in the gas flow rate due to damage. The integrated tuyere for a converter according to the present invention is provided with: a double metal tube 3 which has an inner tube 31 and an outer tube 32, the inner tube 31 being loaded with a refractory 35; a tuyere refractory 2, in a through-hole in which 21 the double metal tube 3 is fixed with an adhesive 22 in between; and a metal case 4 which has a bottom plate 41 that covers the bottom face of the tuyere refractory 2 and a side plate 43 that covers a lower side face of the tuyere refractory 2. The metal case 4 has a thickness T of 6 to 20 mm and a length L of 3% to 50% of the total length of the tuyere refractory. The outer tube 32 of the double metal tube has an upper outer tube 321 and a lower outer tube 322. The lower outer tube 322 has a thickness of 3 mm or more and is welded/fixed to the bottom plate 41 of the metal case.

Description

Integrated tuyere for converter

The present invention is a tuyere provided at the bottom of a converter in order to blow gas into a converter for steelmaking, and a double metal pipe filled with a refractory in the inner pipe and a tuyere refractory are integrated. Regarding the integrated tuyere for converters.

A tuyere is provided on the bottom of the converter as a refractory for blowing gas. There are several types of tuyere depending on the purpose of use. For example, when the main purpose is to agitate molten steel in a converter, a tuyere in which a plurality of metal thin tubes are embedded in a refractory, or a blade using a single double-tube metal tube in which the inner tube is filled with a refractory. There is a mouth etc.
Here, the "double metal pipe in which the inner pipe is filled with a fireproof material" means that the metal pipe (inner pipe) inside the double metal pipe is filled with a fireproof material, and the inner pipe and the outer metal pipe (outer pipe) are filled. ) And the gap (slit) is the gas passage. In the present specification, this "double metal pipe in which the inner pipe is filled with a refractory material" is also simply referred to as a "double metal pipe".

As a tuyere in which multiple metal thin tubes are embedded in a refractory, an integrated tuyere in which multiple metal thin tubes and a refractory are integrally molded has been put into practical use, and since it is easy to install in a converter, it is on-site. Excellent workability in.

On the other hand, Patent Document 1 and Patent Document 2 disclose tuyere in which a double metal pipe is used, and these tuyere penetrate the tuyere refractory constructed in the converter at the time of on-site construction. This double metal tube must be inserted into the hole, and then the double metal tube must be fixed to the iron skin, which causes a problem that the mounting work requires a great deal of time and effort.
Further, since the central part (inside the inner pipe) of the double metal pipe is filled with a refractory material and gas does not flow in the inner pipe, the temperature becomes high during use and it is easy to melt. Therefore, the thickness of the metal tube is as thin as about 1 mm so that the influence is small even if it melts. This is because when a double metal tube having a large thickness is used, the metal tube on the working surface side melts during use and the width of the slit is widened, so that the working surface is quickly worn.
When such a conventional double metal tube and a tuyere refractory are integrally molded, the thickness of the metal tube is as thin as about 1 mm, so that the metal tube is easily deformed by the pressure during molding, and the inner tube and the outer tube are easily deformed. It is difficult to uniformly secure a gap (slit) with and about 1 mm, and in some cases, the slit may be crushed.

On the other hand, in the tuyere structure of Patent Document 3, the annular tuyere has a shaft core portion composed of an inner pipe and a fireproof material filling layer on the inner surface side of the inner pipe, and a ring-shaped gap on the outside of the shaft center portion. It is composed of a tubular part to be fixed, and a tuyere fireproof material is constructed around the annular tuyere in close contact with the tubular part. Further, it is described that the tuyere refractory is separated from the lining refractory, and the tuyere refractory and the annular tuyere are integrally formed.
As described above, in the tuyere structure of Cited Document 3, the tuyere refractory and the annular tuyere are integrally formed, but since the annular tuyere protrudes from the tuyere refractory, the annular tuyere is inserted into the converter. If the protruding annular tuyere is gripped and lifted or hit against an object during construction or handling, the annular tuyere may be deformed and the ring-shaped spacing (slit) may be crushed. If the slit is crushed, the required gas flow rate cannot be secured, which hinders the operation of the converter.

Japanese Patent No. 4765372 Japanese Patent No. 6011808 JP-A-2009-68099

The problem to be solved by the present invention is that in an integrated tuyere for a converter in which one double metal pipe and a tuyere refractory are integrated, the double metal pipe during construction and handling in the converter It is an object of the present invention to provide an integrated tuyere for a converter that suppresses a decrease in gas flow rate due to deformation or damage and has a simple structure.

According to the present invention, the following integrated tuyere for converter is provided.
1. 1.
A single double metal tube that has an inner tube and an outer tube arranged concentrically and the inner tube is filled with refractory.
A tuyere refractory in which a double metal tube is fixed to a through hole via an adhesive,
It is provided with a metal case fixed to the tuyere refractory having a bottom plate that covers the lower end surface of the tuyere refractory and through which a double metal tube penetrates and a side plate that covers the lower side surface of the tuyere refractory.
The metal case has a thickness of 6 mm or more and 20 mm or less, and a length of 3% or more and 50% or less of the total length of the tuyere refractory.
The outer tube of the double metal tube has an upper outer tube and a lower outer tube, and the lower outer tube has a thickness of 3 mm or more and is thicker than the upper outer tube. An integrated tuyere for converters that is welded and fixed to the bottom plate.
2.
The integrated tuyere for converter according to 1 above, wherein the upper outer pipe and the lower outer pipe are integrated.
3. 3.
The boundary between the upper outer pipe and the lower outer pipe is located at the same height as the upper surface of the bottom plate of the metal case, or at a height of up to 40% of the total length of the tuyere refractory upward from the upper surface of the bottom plate of the metal case. , The integrated tuyere for converter according to the above 2.

According to the integrated converter tuyere of the present invention, the thickness and length of the metal case covering the lower end surface and the lower side surface of the tuyere refractory are limited to a predetermined range, and the outer tube of the double metal tube is upper. It is composed of an outer pipe and a lower outer pipe that is thicker than this upper outer pipe, and by welding and fixing this lower outer pipe to the bottom plate of the metal case, a double metal pipe can be used during construction and handling inside the converter. It can prevent deformation and damage. As a result, it is possible to suppress a decrease in the gas flow rate due to deformation or damage of the double metal tube, and it is possible to discharge the gas at a stable flow rate. Moreover, it has a simple structure and is easy to install in a converter, improving work efficiency.

Schematic vertical cross-sectional view of an integrated tuyere for a converter according to an embodiment of the present invention. FIG. 1 is an enlarged cross-sectional view taken along the line AA of FIG. An enlarged vertical sectional view of a metal case portion of the integrated tuyere for converter in FIG. 1. 1 Enlarged vertical cross-sectional view of the gas supply unit in the integrated tuyere for converter of FIG. An enlarged vertical sectional view of a metal case portion in an integrated tuyere for a converter according to another embodiment of the present invention. An enlarged vertical sectional view of a metal case portion in an integrated tuyere for a converter according to still another embodiment of the present invention.

FIG. 1 schematically shows the overall configuration of an integrated tuyere 1 for a converter according to an embodiment of the present invention in a vertical cross section. 2 is an enlarged cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is an enlarged vertical cross-sectional view of the metal case 4 portion of the integrated tuyere 1 for converter.
As shown in FIGS. 1 and 2, the integrated tuyere 1 for a converter has a tuyere refractory 2 having a rectangular plan view and a square cone except for the metal case 4, and a tuyere refractory 2. It includes a metal case 4 provided at the bottom, and a double metal tube 3 that penetrates the through hole 21 of the tuyere refractory 2 and the metal case 4 and is welded and fixed to the metal case 4.

The double metal tube 3 is fixed to the through hole 21 of the tuyere refractory 2 via an adhesive 22 having a thickness of about 1 mm. The total length of the double metal tube 3 is 1500 mm. As shown in FIG. 3, the lower portion of the tuyere refractory 2 is a square pillar having a small side length due to a step for fitting with the metal case 4. The metal case 4 has a bottom plate 41 that covers the lower end surface of the tuyere refractory 2, and a side plate 43 that covers the lower side surface of the tuyere refractory 2. In the present embodiment, the side plate 43 is formed in a square tubular shape, and the square tubular side plate 43 is welded and fixed to the upper surface 44 of the rectangular bottom plate 41. Although not shown, the metal case 4 and the lower part of the tuyere refractory 2 are joined via an adhesive. Further, as shown in FIG. 3, there is a through hole 42 in the central portion of the bottom plate 41 of the metal case 4, a double metal pipe 3 penetrates through the through hole 42, and the double metal pipe 3 is welded and fixed to the bottom plate 41. ing. In the present embodiment, the thickness T of the bottom plate 41 and the side plate 43 constituting the metal case 4 is 12 mm, and the length L of the metal case 4 is 50 mm (5% with respect to the total length of the tuyere refractory 2).

Here, the double metal pipe 3 and the metal case 4 are all made of metal, and are typically SS material (rolled steel material for general structure), SC material (carbon steel material for machine structure), and STKM material (for machine structure). It is made of steel such as carbon steel pipe) or stainless steel.

The tuyere refractory 2 has a total length of 1000 mm, an upper end surface is a rectangle with a short side of 100 mm and a long side of 150 mm, and the horizontal cross section of the surface of the metal case 4 in contact with the upper end surface of the side plate 43 is 110 mm for the short side and 160 mm for the long side. The rectangular shape of the hole 21 has an inner diameter of 27 mm and a weight of 50 kg.
Although the horizontal cross section of the tuyere refractory 2 is rectangular in the present embodiment, the tuyere refractory has a trapezoidal, square, circular, fan-shaped or other cross section depending on the arrangement of the furnace bottom bricks arranged around the tuyere refractory. Can also be used. Further, the total length of the tuyere refractory 2 may be determined according to the length of the surrounding furnace bottom brick.

As shown in FIG. 2, the double metal pipe 3 is arranged concentrically in the through hole 21 of the tuyere refractory 2 so that the central axes of the inner inner pipe 31 and the outer outer pipe 32 coincide with each other. The slit 33 is evenly formed between the inner pipe 31 and the outer pipe 32. In the present embodiment, the thickness of the slit 33 is 1 mm, and the thickness of the inner tube 31 is 1.5 mm. Further, in the present embodiment, in order to align the central axes of the inner pipe 31 and the outer pipe 32, protrusions 34 are provided on the outer periphery of the inner pipe 31 at equal intervals in the circumferential direction. The protrusion 34 on the outer circumference of the inner pipe 31 is formed by welding a metal wire in the longitudinal direction (vertical direction) of the outer circumference of the inner pipe 31, or cutting the outer circumference into a groove shape using a thick inner pipe as a material. Can be provided by
The inside of the inner pipe 31 is filled with a refractory material 35. Further, the adhesive material 22 is filled between the outer pipe 32 and the tuyere refractory material 2 (through hole 21).

As shown in FIG. 3, the outer pipe 32 of the double metal pipe 3 is composed of an upper outer pipe 321 and a lower outer pipe 322, and the lower end of the upper outer pipe 321 and the upper end of the lower outer pipe 322 are joined and integrated by welding. It has become. In the present embodiment, the boundary portion 36 between the upper outer pipe 321 and the lower outer pipe 322 is located at the same height as the upper surface 44 of the bottom plate 41 of the metal case 4. Further, in the present embodiment, the thickness of the upper outer tube 321 is 1 mm, and the thickness of the lower outer tube 322 is 5.5 mm. However, the gap between the inner pipe 31 and the upper outer pipe 321 and the gap between the inner pipe 31 and the lower outer pipe 322, that is, the thickness of the slit 33 is the same.

FIG. 4 is an enlarged vertical cross-sectional view of the gas supply unit 5 that supplies gas to the double metal pipe 3 in the integrated tuyere 1 for converter in FIG. As shown in the figure, in the present embodiment, the gas supply unit 5 has an inner diameter slightly larger than the outer diameter of the double metal pipe 3 (lower outer pipe 321), and the socket connecting portion 52 with the gas pipe (not shown). A connecting pipe 51 is provided in the middle of the double metal pipe 3. The gap between the connecting pipe 51 and the lower outer pipe 321 is sealed by welding. The gas supplied to the socket connecting portion 52 passes through the connecting pipe 51 from the gas introduction port 323 provided between the lower outer pipe 322 and the connecting pipe 51 to the gap between the inner pipe 31 and the lower outer pipe 322, that is, the slit 33. Introduced in.

Next, a method for manufacturing the integrated tuyere 1 for a converter, which is an embodiment of the present invention, will be described. First, the tuyere refractory material 2 can be obtained by adding a binder such as a phenol resin to a refractory raw material mixture containing magnesia and scaly graphite as main raw materials, kneading the refractory material 2, and then pressure-molding and heat-treating the material. The through hole 21 can be provided by pulling out the mandrel embedded at the time of molding after molding or boring after heat treatment. The double metal tube 3 can be mounted and fixed in the through hole 21 by applying an adhesive 22 to the outer surface thereof and inserting the double metal tube 3 into the through hole 21. The metal case 4 can be joined to the lower part of the tuyere refractory 2 via an adhesive. After that, the lower outer pipe 322 of the double metal pipe 3 is welded and fixed to the bottom plate 41 of the metal case 4, so that the integrated tuyere 1 for converter can be manufactured.

Here, as the adhesive used between the double metal tube 3 and the tuyere refractory material 2 and between the metal case 4 and the tuyere refractory material 2, only an organic adhesive material or an inorganic adhesive material, or Those to which a refractory powder is added can be used. Specific examples include one or more types of adhesives such as acrylic resin-based, urethane resin-based, epoxy resin-based, phenol resin-based, sodium silicate-based, cement-based, and silica sol-based adhesives, or metal oxide powders and the like. It is the one to which fire-resistant powder such as metal powder is added. In the present embodiment, a phenol resin containing magnesia powder is used between the double metal tube 3 and the tuyere refractory 2, and an epoxy resin adhesive is used between the metal case 4 and the tuyere refractory 2. It was used. The adhesive between the double metal tube 3 and the tuyere refractory 2 can be made of an adhesive containing a refractory powder to further suppress wear on the working surface.

As described above, in the method for manufacturing the integrated converter tuyere 1 of the present embodiment, the double metal tube 3 is attached and fixed to the through hole 21 of the tuyere refractory after pressure molding via an adhesive material. Therefore, even if the double metal tube 3 having a thin thickness is used, the double metal tube 3 is not deformed or the slit is not crushed during the production of the integrated tuyere 1 for converter.

Here, in the metal case 4, when the integrated tuyere 1 for converter is lifted or held horizontally, the tuyere refractory 2 is displaced so as to be detached from the metal case 4, and the double metal tube 3 inside is displaced. It is provided to prevent deformation. Therefore, the thickness T of the metal case 4 is such that the tuyere refractory 2 can be held so that the tuyere refractory 2 does not shift when the converter integrated tuyere 1 is lifted or held horizontally. A thickness is required, and specifically, it can be 6 mm or more and 20 mm or less. If the thickness T of the metal case 4 is less than 6 mm, the tuyere refractory may shift and the double metal tube 3 may be deformed, and if it exceeds 20 mm, it becomes heavy and difficult to handle.

The length L of the metal case 4 can be an appropriate length according to the length of the tuyere refractory, specifically, 3% or more, preferably 5% or more of the total length of the tuyere refractory 2. Can be. If the length L of the metal case 4 is less than 3% of the total length of the tuyere refractory 2, the tuyere refractory 2 is displaced and the double metal tube 3 is deformed, or the tuyere refractory 2 is likely to fall. The upper limit of the length L of the metal case 2 does not have to be particularly limited, but if it is too long, the tuyere fire resistance will be deteriorated in consideration of the fact that the integrated tuyere 1 for converter becomes too heavy and the handleability deteriorates. It can be 50% or less of the total length of the object 2, and further, 30% or less of the total length of the tuyere refractory object 2 is sufficient.

Further, as shown in FIG. 3, since the lower outer pipe 322 of the double metal pipe 3 is thicker than the upper outer pipe 321, the double metal pipe 3 is gripped and the integrated tuyere 1 for converter is lifted in a horizontal state. However, it is possible to prevent the double metal tube 3 from being deformed. The thickness of the lower outer pipe 322 depends on the size of the tuyere refractory material 2 to be used, even if the double metal pipe 3 of the integrated tuyere 1 for converter is gripped and maintained in a horizontal state. The thickness may be set so as not to be deformed, and specifically, it can be 3 mm or more. If the thickness of the lower outer pipe 322 is less than 3 mm, it may be deformed when a force is applied to the double metal pipe 3 of the integrated tuyere 1 for converter. The upper limit of the thickness of the lower outer pipe is not particularly set, but if the thickness is too thick, the converter integrated tuyere becomes heavy, and if there is a problem in handling, it can be set to 10 mm or less.

In the present embodiment, as described above, since the upper outer pipe 321 and the lower outer pipe 322 are welded and joined to form one metal pipe, the double metal pipe 3 is combined with the tuyere refractory material 2 and the metal case 4. It can be easily attached to and the work efficiency at the time of manufacturing is improved. Moreover, since the thickness of the lower outer pipe 322 is increased by increasing the outer diameter of the lower outer pipe 322 without changing the thickness of the gap (slit 33) between the lower outer pipe 322 and the inner pipe 31, the outer diameter of the lower outer pipe 322 is increased. Is smaller than the case where it is separated without being integrated with the upper outer pipe 321 (FIG. 6 described later). Since the outer diameter of the lower outer pipe 322 is small as described above, the gas supply unit 5 provided in the lower part of the lower outer pipe 322 can also be made smaller. Therefore, it is excellent in handling at the time of furnace construction. In addition, the overall weight can be reduced.

On the other hand, the thickness of the upper outer pipe 321 of the double metal pipe 3 does not need to be thickened and can be made sufficiently thin. Therefore, when the metal pipes (inner pipe 31 and upper outer pipe 321) are melted during use and the width of the slit 33 is widened. However, it is possible to prevent the working surface from being worn out too quickly. Further, since the thickness of the metal pipe (inner pipe 31 and upper outer pipe 321) can be sufficiently reduced, the width of the slit 33 can be kept small, and the intrusion of molten steel into the slit 33 can be suppressed. ..
Specifically, the thickness of the inner pipe 31 and the upper outer pipe 321 can be 0.5 mm or more and 3 mm or less. If the thickness of the inner pipe 31 and the upper outer pipe 321 is less than 0.5 mm, workability deteriorates due to deformation during handling during manufacturing, and if it exceeds 3 mm, it tends to melt during use.

The height position of the boundary portion 36 between the upper outer pipe 321 and the lower outer pipe 322 is set to the same height position as the upper surface 44 of the bottom plate 41 of the metal case 4 as in the present embodiment, or the bottom plate 41 of the metal case 4 is set. It is preferable that the height is up to 40% of the total length of the tuyere refractory 2 upward from the upper surface 44 of the metal case 4, and more preferably the total length of the tuyere refractory 2 is upward from the upper surface 44 of the bottom plate 41 of the metal case 4. The height position can be up to 10%.
In this way, the height position of the boundary portion 36 between the upper outer pipe 321 and the lower outer pipe 322 is the same height position as the upper surface 44 of the bottom plate 41 of the metal case 4, or above the upper surface 44 of the bottom plate 41 of the metal case 4. Therefore, it is possible to further prevent the double metal tube 3 from bending when the double metal tube 3 is held and handled. The upper limit of the height position of the boundary portion 36 between the upper outer pipe 321 and the lower outer pipe 322 does not have to be particularly limited, but the total length of the tuyere refractory 2 is upward from the upper surface 44 of the bottom plate 41 of the metal case 4. If the length exceeds 40% of the total length of the tuyere refractory 2, the tuyere refractory 2 may wear out during use and come into contact with molten steel. It is preferably in the vertical position, and more preferably in the height position up to 10% of the total length of the tuyere refractory.
If the height position of the boundary portion 36 between the upper outer pipe 321 and the lower outer pipe 322 is lower than the lower surface 45 of the bottom plate 41 of the metal case 4, the double metal pipe 3 is held and handled. The heavy metal tube 3 is more likely to bend. In this respect, in the present invention, since the lower outer pipe 321 is welded and fixed to the bottom plate 41 of the metal case 4, the height position of the boundary portion 36 between the upper outer pipe 321 and the lower outer pipe 322 is the lower surface of the bottom plate 41 of the metal case 4. Never below 45,

The outer diameter of the double metal tube 3 and the thickness of the slit 33 are appropriately determined depending on the flow rate of the gas to be blown and the number of tuyere installed in the converter. The outer diameter of the double metal tube 3 can be 20 mm or more and 60 mm or less, and the thickness of the slit 33 can be 0.5 mm or more and 3 mm or less from the viewpoint of easily securing the flow rate of the double metal tube 3.
The length of the portion of the double metal pipe 3 protruding from the metal case 4 is determined by the thickness of the iron skin of the converter, the position of the gas pipe, etc., but if it is too long, it is easily deformed, so the maximum length is about 1000 mm. It is preferable, and it can be at least about 200 mm.

FIG. 5 is an enlarged vertical sectional view of a metal case portion of an integrated tuyere for a converter according to another embodiment of the present invention. In this embodiment, the height position of the boundary portion 36 between the upper outer pipe 321 and the lower outer pipe 322 is 20 mm above the upper surface 44 of the bottom plate 41 of the metal case 4 (the total length of the tuyere refractory 2). 2%). In line with this, the through hole 21 of the tuyere refractory 2 has a stepped shape in which the lower side expands. In this embodiment as well, as in the previous embodiment, the upper outer pipe 321 and the lower outer pipe 322 are joined and integrated by welding.

FIG. 6 is an enlarged vertical sectional view of a metal case portion of an integrated tuyere for a converter, which is still another embodiment of the present invention. In this embodiment, the upper outer pipe 321 and the lower outer pipe 322 of the outer pipe 32 of the double metal pipe 3 are separated without being integrated. That is, the upper end surface of the lower outer pipe 322 is welded and fixed to the lower surface 45 of the bottom plate 41 of the metal case 4, the upper outer pipe 321 penetrates into the through hole 42 of the bottom plate 41, and the upper part of the penetration portion is welded and fixed to the bottom plate 41. Has been done.

In the embodiment of the integrated tuyere for converter shown in FIGS. 1 to 4, the condition that the thickness T of the metal case 4, the length L of the metal case 4, and the thickness of the lower outer tube 322 of the double metal tube 3 are different is satisfied. Table 1 shows the results of handling tests of the integrated tuyere for converters. The material of the metal case 4 is SS400, the material of the double metal tube 3 is SUS304 for the inner tube 31 and the upper outer tube 321 and STKM for the lower outer tube 322.
In the handling test, the double metal pipe 3 protruding from the bottom plate 41 of the metal case 4 of the integrated tuyere for the converter was placed at the position of 1/3 of the total length of the protruding part from the bottom plate 41 of the metal case 4 and the rear end. The two points were held horizontally by a crane, maintained in a horizontal state, lifted by 2 m in about 1 second, and then lowered in about 2 seconds and returned to the original position, which was repeated 5 times. Then, apart from the crane, an integrated tuyere for converter was placed on a horizontal table, gas (air) was flowed through the double metal pipe 3 at a pressure of 0.1 MPa, and the gas flow rate was measured. Then, the gas flow rate of Example 1 was set as 100 and displayed as an index. The larger this index is, the larger the gas flow rate is, and when this index is 95 or more, it is regarded as passing. The large gas flow rate after the handling test means that the deformation and damage of the double metal tube 3 in the handling test were small.

In Examples 1 to 3, the thickness of the side plate 43 of the metal case 4 differs within the range of the present invention, but the gas flow rate index is 100 to 107, and the double metal tube 3 is not deformed or damaged. It was good. On the other hand, in Comparative Example 1, the thickness of the side plate 43 of the metal case 4 was 3 mm, which was lower than the lower limit (6 mm) of the present invention, and the gas flow rate index was lowered to 65. This is because the double metal tube 3 was damaged and partly crushed by the handling test.

In Example 4, the thickness of the bottom plate 41 of the metal case 4 was 6 mm, but the gas flow rate index was 97, and the double metal tube 3 was not deformed or damaged, which was good. On the other hand, in Comparative Example 2, the thickness of the bottom plate 41 of the metal case 4 was 3 mm, which was lower than the lower limit (6 mm) of the present invention, and the gas flow rate index was reduced to 84. This is because the double metal tube 3 was damaged and partly crushed by the handling test.

In Examples 5 to 8, the lengths of the metal cases 4 differ within the scope of the present invention, but the index of the gas flow rate is 95 to 110, and no significant decrease in the gas flow rate is observed, which is good. there were. On the other hand, in Comparative Example 3, the length of the metal case 4 was 1% of the total length of the tuyere refractory, which was less than the lower limit (3%) of the present invention, and the gas flow rate index decreased to 67. .. This is because the double metal tube 3 was damaged and partly crushed by the handling test.

In Example 9 and Example 10, the thickness of the lower outer pipe 322 of the double metal pipe 3 was different within the range of the present invention, but the gas flow rate indexes were 100 and 105, which were good. On the other hand, in Comparative Example 4, the thickness of the lower outer pipe 322 of the double metal pipe 3 was 1.5 mm, which was lower than the lower limit (3 mm) of the present invention, and the index of gas flow rate decreased to 88. This is because the double metal tube 3 was damaged and partly crushed by the handling test.

1 Integrated tuyere for converter 2 Tuft refractory 21 Through hole 22 Adhesive material 3 Double metal pipe 31 Inner pipe 32 Outer pipe 321 Upper outer pipe 322 Lower outer pipe 323 Gas inlet 33 Slit 34 Protrusion 35 Refractory 36 Boundary Part 4 Metal case 41 Bottom plate 42 Through hole 43 Side plate 44 Top surface of bottom plate 45 Bottom surface of bottom plate 5 Gas supply part 51 Connection pipe 52 Socket connection part

Claims

A single double metal tube that has an inner tube and an outer tube arranged concentrically and the inner tube is filled with refractory.
A tuyere refractory in which a double metal tube is fixed to a through hole via an adhesive,
It is provided with a metal case fixed to the tuyere refractory having a bottom plate that covers the lower end surface of the tuyere refractory and through which a double metal tube penetrates and a side plate that covers the lower side surface of the tuyere refractory.
The metal case has a thickness of 6 mm or more and 20 mm or less, and a length of 3% or more and 50% or less of the total length of the tuyere refractory.
The outer tube of the double metal tube has an upper outer tube and a lower outer tube, and the lower outer tube has a thickness of 3 mm or more and is thicker than the upper outer tube. An integrated tuyere for converters that is welded and fixed to the bottom plate.
The integrated tuyere for converter according to claim 1, wherein the upper outer pipe and the lower outer pipe are integrated.
The boundary between the upper outer pipe and the lower outer pipe is located at the same height as the upper surface of the bottom plate of the metal case, or at a height up to 40% of the total length of the tuyere refractory from the upper surface of the bottom plate of the metal case. , The integrated tuyere for converter according to claim 2.