JP7140991B2 - Bottom-blown tuyere plugs and plug fittings - Google Patents

Description

The present invention relates to a bottom-blowing tuyere plug and a plug fitting that can be used for the bottom-blowing tuyere plug.

A multi-hole plug having a structure in which a large number of thin metal tubes are embedded in a refractory is widely used as a plug for blowing an inert gas into the bottom of a smelting furnace or the like. For example, International Publication No. 2017/060937 (Patent Document 1) discloses a bottom-blown plug that is characterized by the ratio of the area of the opening group to the area of the top surface of the plug, the density of the openings, and the like. In addition, Japanese Patent No. 6640461 (Patent Document 2) describes the reciprocal of the number density of the gas blowing pipes in the gas blowing pipe existence region, and the relationship between the gas blowing pipes located on the outer periphery of the gas blowing pipe existence region and the outer edge of the plug body. A multi-hole plug characterized by the average value of the shortest distance of .

WO2017/060937 Japanese Patent No. 6640461

Multi-hole plugs are directed to improving the density of metal capillaries per horizontal cross-sectional area. This is because if the metal capillary density in the multi-hole plug can be improved, the flow rate of the inert gas blown into the refining furnace through the multi-hole plug can be increased, which can be expected to improve the refining efficiency. For example, Patent Document 2 discloses a multi-hole plug in which the reciprocal number S (mm ² /line) of the number density is set to 100 or less. However, if you try to increase the number density, it becomes difficult to weld the metal tubules to the gas pool, and gas leaks may occur due to poor welding. .

Therefore, in multi-hole plugs, there is a demand for realization of a technique that can improve the density of metal capillaries per horizontal cross-sectional area compared to conventional techniques.

A bottom-blowing tuyere plug according to the present invention comprises a plurality of thin tubes, a gas pool in fluid communication with the plurality of thin tubes, and an introduction pipe capable of supplying gas to the gas pool, The size of the fillet formed at the welded portion between the narrow tube and the gas pool inside the gas pool is 5.0 mm or less.

A metal fitting for a plug according to the present invention includes a plurality of thin tubes, a gas pool in fluid communication with the plurality of thin tubes, and an introduction pipe capable of supplying gas to the gas pool, wherein the gas is The size of the fillet formed at the welded portion between the narrow tube and the gas pool inside the pool is 5.0 mm or less.

According to these configurations, in the multi-hole plug, it is possible to narrow the distance between the capillaries as compared with the conventional technology. As a result, the density of metal capillaries per horizontal cross-sectional area of the multi-hole plug can be increased.

Preferred embodiments of the present invention are described below. However, the scope of the present invention is not limited by the preferred embodiments described below.

As one aspect of the bottom-blown tuyere plug according to the present invention, in the welded portion, the plurality of capillaries are independently in fluid communication with the gas pool, and two adjacent gas pools in the welded portion are in fluid communication. The shortest distance between the surfaces of the capillaries is preferably 8.0 mm or less.

With this configuration, it is possible to further increase the density of metal capillaries per horizontal cross-sectional area of the multi-hole plug.

As one aspect of the bottom-blowing tuyere plug according to the present invention, the maximum value Ls (mm) of the distance between the centers of the thin tubes, the number N of the thin tubes, and the inner diameter Lp of the introduction tube Lp (mm) ) is preferably selected such that the parameter Q represented by equation (1) is 100 or more and 3000 or less.

According to this configuration, it is possible to particularly increase the density of the capillaries as long as the pressure loss in the capillaries does not easily increase.

In one aspect of the bottom-blowing tuyere plug according to the present invention, it is preferable that the outer diameter of the thin tube is 6.0 mm or less.

With this configuration, it is possible to further increase the density of metal capillaries per horizontal cross-sectional area of the multi-hole plug.

Further features and advantages of the invention will become clearer from the following description of exemplary and non-limiting embodiments described with reference to the drawings.

1 is a longitudinal sectional view of a bottom-blowing tuyere plug according to an embodiment; FIG. 1 is a top view of a bottom blowing tuyere plug according to an embodiment. FIG. 1 is a vertical cross-sectional view of a metal fitting for a plug according to an embodiment; FIG. FIG. 4 is a vertical cross-sectional view (enlarged view of a portion indicated by symbol IV in FIG. 3) showing a joint portion between a thin tube and a gas pool in the metal fitting for plug according to the embodiment;

An embodiment of a bottom-blown tuyere plug and a metal fitting for a plug according to the present invention will be described with reference to the drawings. An example in which the bottom-blowing tuyere plug according to the present invention is applied to a bottom-blowing tuyere plug 1 for blowing gas into a refining furnace will be described below. The plug fitting 2 included in the bottom-blowing tuyere plug 1 is an example of the plug fitting according to the present invention.

[Configuration of bottom-blown tuyere plug]
A bottom-blown tuyere plug 1 according to this embodiment has a structure in which a plug fitting 2 is embedded in a refractory 3 (FIG. 1). A plurality of capillaries 21 are opened in the upper surface 11 of the bottom blowing tuyere plug 1 (Fig. 2). The gas introduced from the introduction pipe 23 is distributed to the plurality of thin tubes 21 through the gas pool 22 and eventually discharged from the openings of the plurality of thin tubes 21 provided on the upper surface 11 of the bottom-blowing tuyere plug 1 . Thus, the bottom-blowing tuyere plug 1 is a plug capable of supplying gas to the upper surface 11 side through a plurality of narrow tubes 21 . In addition, when referring to the vertical direction in the following description, it means the vertical direction defined according to the postures shown in FIGS. 1 and 2 . That is, in the bottom-blowing tuyere plug 1 (plug hardware 2), the side on which the thin tube 21 is provided is called the top, and the side on which the introduction pipe 23 is provided is called the bottom.

The bottom-blowing tuyere plug 1 generally has the shape of a truncated quadrangular pyramid. That is, the cross section of the bottom-blowing tuyere plug 1 in the horizontal direction (the direction perpendicular to the page of FIG. 1) is a quadrilateral, and the cross-sectional area gradually decreases from the bottom side to the top side of the bottom-blowing tuyere plug 1 . . FIG. 2 shows an example in which the top surface 11 of the bottom-blowing tuyere plug 1 has a rectangular shape. However, in the case where the bottom-blowing tuyere plug 1 is formed in a substantially truncated pyramid shape, the shape of the cross section in the horizontal direction may be a quadrilateral, for example, a trapezoid other than the rectangle illustrated in FIG. . Moreover, a truncated pyramid other than the truncated quadrangular pyramid may be used, or a truncated cone may be used. Further, the central part having the narrow tube and the peripheral refractory may be integrally molded, or the central part having the narrow tube may be removed and inserted.

[Structure of metal fittings for plugs]
The plug fitting 2 has respective parts of a narrow tube 21, a gas pool 22, and an introduction tube 23 (FIGS. 1 to 3). Each part of the plug fitting 2 is made of metal, and the connection between the narrow tube 21 and the gas pool 22 and the connection between the gas pool 22 and the introduction pipe 23 are both made by welding. The metal forming each part of the plug fitting 2 may be, for example, a stainless steel pipe for piping specified in JIS G3459. As a specific example, stainless steel (SUS304, SUS316, SUS316L, SUS310S, etc.) can be suitably used, but the material is not limited to these. The thin tube 21, the gas pool 22, and the introduction pipe 23 may all be made of the same metal material, or may be made of different metal materials for each member. For example, the introduction pipe 23 may be a carbon steel pipe for pressure piping such as STPG specified in JIS G3454, or may be SS400.

The gas pool 22 is a hollow member having a disk-like shape. The gas pool 22 is defined by an upper plate 22a to which the plurality of capillaries 21 are welded, a lower plate 22b to which the inlet pipes 23 are welded, and side plates 22c. The side plate 22c extends from the lower plate 22b to the upper plate 22a and further extends upward beyond the upper plate 22a.

In this embodiment, each thin tube 21 is a straight tube with an outer diameter of 2.0 mm and an inner diameter of 1.0 mm. A plurality of thin tubes 21 are welded to a gas pool 22 (upper plate 22a) so as to extend parallel to each other. Therefore, the arrangement of the capillaries 21 on the top plate 22a is the same as the arrangement of the capillaries 21 on the top surface 11 of the bottom-blown tuyere plug 1 (FIG. 2). In this embodiment, as shown in FIG. 2, a plurality of capillaries 21 are arranged in a regular hexagonal array. The number of thin tubes 21 per side is 10, and the number of thin tubes 21 is 271. The dimensions of the thin tubes 21, the shape in which the thin tubes 21 are arranged, and the number of thin tubes 21 are not particularly limited, and are appropriately selected in line with the design concept of the bottom-blown tuyere plug 1. However, when the outer diameter of the thin tube 21 is 6.0 mm or less, it is easy to increase the thin tube density.

Here, the structure and dimensions of the junction between the narrow tube 21 and the upper plate 22a will be described in more detail with reference to FIG. The thin tube 21 is inserted through a through hole 22d provided in the upper plate 22a, and then welded to the upper plate 22a on the lower side of the upper plate 22a (inside the gas pool 22). A fillet 21a formed at the time of welding is present at the lower end of the thin tube 21, and the size S of the fillet is 5.0 mm or less. Since the fillet 21a must always be provided when each thin tube 21 is welded to the upper plate 22a, the separation distance D between the surfaces of the adjacent thin tubes 21 is more than twice the size S of the fillet. Therefore, in this embodiment, the separation distance D can be set to 10 mm or less. As described above, in the present embodiment, by setting the fillet size S to a relatively small value (5.0 mm or less), the small tubes can be arranged more easily than the hardware used in the conventional bottom-blown tuyere plug. We have successfully reduced the separation distance, which allows higher capillary density than conventional bottom-blown tuyere plugs.

The pitch P, which is the distance between the centers of adjacent thin tubes 21, is obtained as a value obtained by adding the outer diameter of the thin tubes 21 to the spacing distance D. In the present embodiment, the thin tube 21 has an outer diameter of 2.0 mm, and the separation distance D can be set to 10 mm or less, so the pitch P can be set to 12 mm or less.

Referring to FIG. 2 again, in the regular hexagonal capillary arrangement of the capillaries 21 according to the present embodiment, when the distance between the centers of two arbitrarily selected capillaries 21 is the maximum, the regular hexagonal opposing This is a case where two capillaries 21 located at two vertices are selected, and the distance between them coincides with the length of the diagonal line E of the regular hexagon. Since 19 thin tubes 21 are arranged at equal intervals on the diagonal line E, the length of the diagonal line E is 18 times the pitch P of the thin tubes 21 .

In this embodiment, one introduction pipe 23 is provided, and the introduction pipe 23 is a straight pipe having a nominal diameter of 32A and a nominal thickness of Sch/40 defined in JIS G3454.

According to the study of the present inventors, between the maximum value Ls (mm) of the separation distance between the thin tubes 21, the number N (number) of the thin tubes 21, and the inner diameter Lp (mm) of the introduction tube 23, the formula (1) It has been found that the gas flow rate can be particularly increased when the relationship in which the expressed parameter Q is 100 or more and 3000 or less is established.

In this embodiment, the number N (number) of the thin tubes 21 is 271, and the inner diameter Lp (mm) of the introduction tube 23 is 35.5 mm. Further, the maximum value Ls (mm) of the separation distance between the thin tubes 21 is 18 times the pitch P of the thin tubes 21 as described above. And the pitch P may be 12 mm or less. Based on the above numerical conditions, the maximum value of the parameter Q is 4800 (pitch P: 12 mm, fillet size S: 5.0 mm). Here, reducing the pitch P and the fillet size S reduces the value of the parameter Q. When the parameter Q is 3000, the pitch P is 9.5 mm and the fillet size S is 3.7 mm. When the parameter Q is 100, the pitch P is 3.0 mm and the fillet size S is 0.50 mm.

As described above with reference to the example, the parameter Q and the pitch P are in such a relationship that the value of the parameter Q decreases as the pitch P decreases. When the parameter Q exceeds 3000, it is when the pitch P is in the large category within the range that satisfies the fillet size regulation (5 mm or less) in the present invention, so compared to the case where the parameter Q is 3000 or less , the effect of increasing the capillary density is limited. On the other hand, when the parameter Q is less than 100, the inner diameter of the introduction tube 23 becomes too small relative to the density of the thin tubes, and the pressure loss in the thin tubes 21 may increase.

[Method for manufacturing metal fittings for plugs]
The metal plug 2 having the structure described above can be manufactured, for example, by the following method. In order to form the joining portion between the thin tube 21 and the upper plate 22a, first, the upper plate 22a provided with a plurality of through holes 22d and the required number of thin tubes 21 (271 in this embodiment) or more are prepared. do. At this time, the upper plate 22a is provided with a plurality of through-holes 22d in the same number (271 in this embodiment) and arrangement (regular hexagon shape in this embodiment) as the capillaries 21 to be provided. Next, the thin tube 21 is inserted into each of the plurality of through holes 22d, and the lower surface of the upper plate 22a and the end of the thin tube 21 are aligned so that they are substantially flush with each other. After that, the lower surface of the upper plate 22a and the end of the thin tube 21 are welded by fiber laser welding. Finally, finishing work (deburring, etc.) of welding that is normally performed is performed to complete the joining of the thin tube 21 and the upper plate 22a.

As described above, by employing fiber laser welding, the size of the fillets formed during welding can be made smaller than when conventional welding methods are employed. In this embodiment, the size S of the fillet 21a can be reduced to 5.0 mm or less by welding the thin tube 21 and the gas pool 22 by fiber laser welding. Examples of welding methods that can be used in this embodiment include tungsten inert gas arc welding (TIG welding), yttrium-aluminum-garnet laser welding (YAG welding), and the like, in addition to fiber laser welding.

Subsequently, a joint portion between the lower plate 22b and the introduction pipe 23 is formed by welding. Further, the upper plate 22a, the lower plate 22b, and the side plate 22c are welded and joined to complete the plug fitting 2. As shown in FIG. In the welding between the lower plate 22b and the introduction pipe 23, the welding between the upper plate 22a and the side plate 22c, and the welding between the lower plate 22b and the side plate 22c, there is little need to reduce the fillet size (the fillet size may exceed 5 mm), other than the fiber laser welding exemplified above, a welding method such as TIG welding may be used.

[Composition of refractory]
The refractory 3 is mainly composed of a refractory raw material containing an oxide as a main component. Here, the main component means the substance contained in the refractory raw material in the largest amount in terms of mass ratio. In addition, the refractory 3 may contain carbon raw materials, non-oxide additives, etc., in addition to the refractory raw materials. The combination and content ratio of the raw materials constituting the refractory 3 are not particularly limited, and are appropriately selected in line with the design concept of the bottom-blown tuyere plug 1 .

Examples of oxides contained in the refractory raw material in the refractory 3 include alumina, silica, spinel, magnesia, zirconia, zircon, and calcium zirconate. The oxide may be a single substance or a mixture of two or more substances. The refractory raw material in the refractory 3 preferably contains at least one of magnesia and spinel as an oxide, more preferably magnesia. The substance used as the oxide contained in the refractory raw material in the refractory 3 is appropriately selected according to the application of the bottom-blown tuyere plug 1 .

When the refractory 3 contains a carbon raw material, examples of the carbon raw material include graphite, carbon black, pitch, and carbon fiber. The carbon raw material may be one kind of substance, or may be a mixture of two or more kinds of substances. The carbon raw material in the refractory 3 preferably contains at least one of graphite and carbon fiber, and more preferably contains graphite. The substance used as the carbon raw material in the refractory 3 is appropriately selected according to the application of the bottom-blown tuyere plug 1 . For example, when the bottom-blowing tuyere plug 1 is used in applications where it is exposed to particularly large thermal changes, it is preferable that the refractory 3 contains pulverized expanded graphite pulverized after the expansion treatment as the carbon raw material.

When the refractory 3 contains a carbon raw material, the content of the carbon raw material is preferably 10 to 50% of the refractory raw material. Here, "outer coating" refers to the mass ratio of the additive (here, carbon raw material) when the mass of the base material (here, refractory raw material) is taken as 100%. In the following description, "outer coating" represents the outer coating mass ratio based on the refractory raw material unless otherwise specified. More preferably, the content of the carbon raw material is 15% or more in terms of external weight. In addition, the content of the carbon raw material is preferably 35% or less, more preferably 25% or less.

When the refractory 3 contains a non-oxide additive, examples of the non-oxide additive include silicon carbide, boron carbide, zirconium boride, aluminum, and silicon nitride. The non-oxide additive may be a single substance or a mixture of two or more substances. The non-oxide additive in the refractory 3 preferably contains at least one selected from aluminum, silicon carbide, and boron carbide, more preferably at least one of aluminum and silicon carbide. The substance used as the non-oxide additive in the refractory 3 is appropriately selected according to the application of the bottom-blown tuyere plug 1 . For example, it is preferred to include aluminum as a non-oxide additive in the refractory 3 if the bottom-blowing tuyere plug 1 is intended for use in applications that are subject to particularly severe oxidizing conditions.

When the refractory 3 contains a non-oxide additive, the content of the non-oxide additive is preferably 0.01% or more in the outer coating, more preferably 0.1% or more in the outer coating. preferable. Also, the content of the non-oxide additive is preferably 5% or less, more preferably 2% or less.

[Other embodiments]
Finally, another embodiment of the bottom-blown tuyere plug and plug hardware according to the present invention will be described. It should be noted that the configurations disclosed in the respective embodiments below can also be applied in combination with configurations disclosed in other embodiments unless there is a contradiction.

In the above-described embodiment, the configuration in which the thin tubes 21 are arranged in a regular hexagonal array with ten tubes per side has been described as an example. However, in the bottom-blown tuyere plug and plug hardware according to the present invention, the arrangement of the capillaries is not particularly limited.

In the above embodiment, the configuration in which each of the thin tubes 21 is independently welded to the gas pool 22 (upper plate 22a) has been described as an example. However, in the bottom-blowing tuyere plug and plug fitting according to the present invention, a single pipe joined to the gas pool may be provided in such a manner that it branches into a plurality of narrow pipes.

In the above-described embodiment, the configuration in which the distance D between the surfaces of the adjacent capillaries 21 is 10 mm or less has been described as an example. In the bottom-blown tuyere plug and plug hardware according to the present invention, it is preferable that the shortest distance between the surfaces of adjacent capillaries is 8.0 mm or less.

本発明に係る底吹き羽口用プラグおよびプラグ用金物において、パラメータＱは、１５０以上であることがより好ましく、１８０以上であることがさらに好ましい。また、パラメータＱは、２５００以下であることがより好ましく、１５００以下であることがさらに好ましい。 Regarding the above embodiment, it has been explained that the gas flow rate can be particularly increased when the parameter Q represented by the formula (1) satisfies the relationship of 100 or more and 3000 or less.

In the bottom-blown tuyere plug and plug hardware according to the present invention, the parameter Q is more preferably 150 or more, and even more preferably 180 or more. Also, the parameter Q is more preferably 2500 or less, and even more preferably 1500 or less.

In the above embodiment, the fine tube 21 is a straight tube having an outer diameter of 2.0 mm and an inner diameter of 1.0 mm. did. In the bottom-blown tuyere plug and plug hardware according to the present invention, the outer diameter of the thin tube is more preferably 4.0 mm or less, more preferably 2.0 mm or less.

Regarding other configurations, it should be understood that the embodiments disclosed in this specification are examples in all respects, and that the scope of the present invention is not limited by them. Those skilled in the art will easily understand that modifications can be made as appropriate without departing from the scope of the present invention. Therefore, other embodiments modified without departing from the gist of the present invention are naturally included in the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be used, for example, as a bottom-blowing tuyere plug for blowing gas into a smelting furnace.

REFERENCE SIGNS LIST 1: bottom-blowing tuyere plug 11: upper surface 2: plug hardware 21: thin tube 21a: fillet 22: gas pool 22a: upper plate 22b: lower plate 22c: side plate 22d: through hole 23: introduction pipe 3: refractory S: Size of fillet D: Spacing distance P: Pitch Lp: Inner diameter of introduction tube 23 Ls: Maximum value of spacing distance of narrow tube 21

Claims (5)

a plurality of capillaries, a gas pool in fluid communication with the plurality of capillaries, and an introduction pipe capable of supplying gas to the gas pool;
inside the gas pool between the tubule and the gas poolweldingA plug for a bottom-blown tuyere, wherein the fillet size formed on the part is 5.0 mm or less. at the welded portion, the plurality of capillaries are each independently in fluid communication with the gas pool;
2. The bottom-blown tuyere plug according to claim 1, wherein the shortest distance between the surfaces of the two adjacent capillaries in the welded portion is 8.0 mm or less. The maximum value Ls (mm) of the distance between the centers of the capillaries, the number N (number) of the capillaries, and the inner diameter Lp (mm) of the introduction tube are 100 or more as the parameter Q represented by formula (1). A bottom-blown tuyere plug according to claim 1 or 2, selected to be 3000 or less.

The bottom-blown tuyere plug according to any one of claims 1 to 3, wherein the outer diameter of said thin tube is 6.0 mm or less. a plurality of capillaries, a gas pool in fluid communication with the plurality of capillaries, and an introduction pipe capable of supplying gas to the gas pool;
inside the gas pool between the tubule and the gas poolweldingA plug fitting in which the size of the fillet formed on the part is 5.0 mm or less.

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