JPH0953110A - Immersion tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an immersion tube improving the durability of the whole immersion tube by efficiently cooling a lower core metal part arranged at the lower part of the immersion tube while securing safety of the immersion tube. SOLUTION: In the immersion tube including a cooling core metal part 15 fitted to the lower part of a vacuum refining furnace and cooled with coolant and the lower core metal 16 arranged at the lower end of the cooling core metal 15 in a refractory, the lower core metal 16 is complexed with a high thermal conductive metal 28 and a low thermal conductive metal 29, and the high thermal conductive metal 28 is fitted so as to contact with the cooling core metal 15.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dip tube used in a vacuum refining furnace such as DH or RH for degassing molten steel or adjusting the composition thereof.

[0002]

2. Description of the Related Art In a vacuum refining furnace such as DH or RH for performing vacuum refining of molten steel, a vacuum refining furnace is arranged above a ladle holding molten steel, and a dip attached to the lower part of the vacuum refining furnace. The process of sucking the molten steel in a ladle into a vacuum refining furnace by a pipe, degassing the molten steel in a vacuum atmosphere, or adjusting the molten steel composition is performed. This is shown in FIG.
In the following description, the vacuum refining furnace 11 is arranged above the ladle 13 holding the molten steel 14, and the dip pipe 12 is attached to the lower part of the vacuum refining furnace 11. And the immersion pipe 1
2 is a cooling core 15 cooled by a refrigerant (cooling medium),
It consists of an uncooled iron lower core 16 fixed to the lower part of the cooling core 15, and refractories 18, 19 surrounding and protecting the cooling core 15 and the lower core 16.
In the vacuum refining process, the lower end of the dip tube 12 is lowered to lower the lower part of the dip tube 12 into the molten steel 14 of the ladle 13.
Soak in. At this time, the refractories 19 and 18 on the lower and outer circumferences of the dip tube 12 are directly subjected to mechanical shock and locally heated by the contact with the molten steel 14, resulting in a sudden and uneven temperature. Receive thermal shock from changes. Further, when the immersion pipe 12 is pulled up from the molten steel 14 after the vacuum treatment is completed, the lower part of the immersion pipe 12 is rapidly cooled and damaged by thermal shock. Due to such wear of the refractory material, creep deformation of the iron lower core metal 16 at high temperature, and the like, the immersion pipe 12 is deformed by inserting the metal into the refractory material or the joint of the refractory material, and finally the lower core metal 16 Is melted and the life of the immersion pipe itself is shortened, and the cooling core metal 15
Alternatively, the lower core metal 16 cannot be reused.

Therefore, by cooling the portion of the lower iron core 16 made of iron with a cooling medium such as water or air, creep deformation of the lower iron core 16 is suppressed, the strength as a structural material is maintained, and a refractory material is used. A method of preventing wear of itself under high temperature is known. As a structure showing a cored bar having such a cooling mechanism, for example, Japanese Patent Publication No. 3-5080.
No. 4 publication discloses a cooling core metal 15 for an immersion pipe as shown in FIG.
Is disclosed. This will be described below. In the cooling core metal 15, in the cooling core metal 15, the refrigerant supply header 22 arranged above the cooling core metal 15 is supplied with the refrigerant composed of a mixture of air and water from the refrigerant supply port 21, and the refrigerant is It moves from top to bottom through the refrigerant supply branch pipe 24 arranged between the inner cylindrical iron plate 26 and the outer cylindrical iron plate 25. Then, the refrigerant discharged from the lower end of the refrigerant supply branch pipe 24 collides with the core metal bottom plate 27 and inverts and rises, during which the heated heat is taken away and the heated refrigerant is discharged from the refrigerant discharge port 23 above the outer cylindrical iron plate 25. It is supposed to be done. However, as described above, the lower part of the dip pipe, which is easily subjected to mechanical and thermal shocks, has a coolant inside the molten steel 14 when the refractory wears or falls off and the molten steel 14 enters the cooling core 15. When it is blown into the tank, troubles such as steam explosion or fluctuation of molten steel composition occur. Therefore, for safety and quality reasons, a lower core metal 16a made of an uncooled steel cylinder that is not cooled by a refrigerant is fixed to the lower part of the cooling core metal 15 by welding or bolts and nuts.

[0004]

However, in the method of using the cooling core metal 15 and the non-cooling type lower core metal 16a in combination as described above, the durability of the immersion pipe in the portion corresponding to the cooling core metal 15 is improved. Is improved by its cooling effect, but since the amount of heat transfer moving from the lower core metal 16a to the cooling core metal 15 is small, the lower core metal 16 of the non-cooling type is used.
The temperature of a becomes higher by about 200 to 300 ° C. than that of the cooling core 15, and thermal expansion of the lower core 16a and creep deformation due to load occur, which causes a problem that the life of the entire immersion pipe is reduced.

The present invention has been made in view of the above circumstances, and while ensuring the safety of the dip tube, the lower part of the core metal arranged in the lower part of the dip tube is efficiently cooled to make the whole dip tube. It is an object of the present invention to provide a dip tube having improved durability.

[0006]

According to the present invention, there is provided a semiconductor device comprising:
The immersion tube described is a submerged tube which is attached to a lower portion of a vacuum refining furnace and includes a cooling core bar cooled by a cooling medium and a lower core bar arranged at a lower end of the cooling core bar in a refractory material, The lower core metal is a composite of a high thermal conductivity metal and a low thermal conductivity metal, and the high thermal conductivity metal is attached so as to contact the cooling core metal. The immersion pipe according to a second aspect is the immersion pipe according to the first aspect, in which the high thermal conductive metal of the lower core metal is provided so as to protrude from the cooling core metal.

Here, the cooling medium means a fluid heat medium composed of gas such as air and water and / or liquid. The lower core metal is a core metal for maintaining the structural strength as an immersion pipe, which is not directly cooled by a cooling medium. The high thermal conductivity metal is a metal or alloy having a thermal conductivity at least twice as high as that of a low thermal conductivity metal such as steel or stainless steel which is generally used as a material for the core metal, such as copper, silver or brass. Say. The thermal conductivity is 2
If a metal smaller than double the size is used in combination with a metal with low thermal conductivity such as steel or stainless steel, the required temperature gradient cannot be obtained between them and the heat transfer amount will be insufficient, so contact with the cooling core will occur. The cooling effect due to can not be fully exerted. Also,
The low thermal conductive metal refers to a metal or alloy such as steel or stainless steel that is generally used as a material for a cooling core metal.

[0008]

In the immersion pipe according to the present invention, the lower core metal is made of a composite of a high thermal conductivity metal and a low thermal conductivity metal, and the high thermal conductivity metal is attached in contact with the cooling core metal. Therefore, the amount of heat flowing from the refractory material in the lower part of the immersion pipe to the lower core metal is efficiently conducted to the upper cooling core metal via the high thermal conductive metal. Particularly, in the immersion pipe according to the second aspect, since the highly heat-conductive metal of the lower core metal is provided so as to protrude from the cooling core metal, the effective heat transfer surface area can be increased.

[0009]

Therefore, in the immersion pipe according to the first and second aspects, the durability of the immersion pipe in the portion corresponding to the lower core metal is maintained, and even if the core metal in the lower part of the immersion pipe is damaged, it is cooled. The medium does not leak into the molten steel, while ensuring safety, it efficiently cools the lower core metal that is not directly cooled by the fluid cooling medium, Also, it is possible to prevent the thermal expansion and the creep deformation due to the load against the whole core metal as a control, and improve the entire life of the immersion pipe. Particularly, in the immersion pipe according to the second aspect, the effective heat transfer area is increased, and the cooling effect of the lower part of the immersion pipe can be further improved.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, referring to the attached drawings, an embodiment in which the present invention is embodied will be described to provide an understanding of the present invention. 1 is an explanatory view of the vacuum refining equipment, FIG. 2 is a side sectional view of a cored bar portion of the immersion pipe according to the first embodiment of the present invention, and FIG. 3 is a perspective view of a lower cored bar of the immersion pipe. FIG. 4 is a perspective view of a lower core metal of an immersion pipe according to a second embodiment of the present invention, FIG. 5 is a view showing a relationship between the number of immersion pipe treatments and a lower core metal temperature, and FIG. 6 is a second view. It is a comparison figure of the immersion pipe life in an embodiment and a conventional example.

Immersion tube 1 according to the first embodiment of the present invention
As shown in FIG. 1, the vacuum refining equipment 10 to which No. 2 is applied is a ladle 13 for holding molten steel 14, a vacuum refining furnace 11 arranged above the ladle 13, and a dip attached to the lower part of the vacuum refining furnace 11. It consists of a tube 12.

The ladle 13 is a steel container having a refractory lining and a molten steel capacity of about 300 tons, and holds the molten steel 14 that has been smelted in a converter or an electric furnace. For convenience of explanation, FIG. 1 shows an outline of the arrangement of the ladle 13 and the vacuum refining furnace 11, and does not reflect the actual size and the magnitude relation of the ratio. In the vacuum refining furnace 11, the molten steel 14 in the ladle 13 is inserted through the dip pipe 12 by exhausting the inside of the furnace by a vacuum pump (not shown).
Is a device for sucking into the furnace and degassing the molten steel 14 and adjusting the components in a vacuum atmosphere.

The immersion pipe 12 includes a cooling core metal 15 cooled by a refrigerant (cooling medium), a lower core metal 16 fixed to a lower portion of the cooling core metal 15, and a cooling core metal 15 and a lower core metal 1.
6 is a substantially cylindrical tube made of refractory materials 18 and 19 that surrounds 6 and 6. Further, the cooling mandrel 15 has an upper part of the cooling mandrel 15 fixed to a lower part of the vacuum refining furnace 11 via a flange 20 by a fastener such as a bolt and a nut. As shown in FIG. 2, the cooling core metal 15 includes a coolant supply header 22, a coolant supply port 21, an inner cylindrical iron plate 26, an outer cylindrical iron plate 25, a coolant supply branch pipe 24, and a core metal bottom plate 27. here,
The refrigerant supply header 22 above the cooling core 15 is supplied with a refrigerant composed of a mixture of air and water from the refrigerant supply port 21, and the refrigerant is supplied between the inner cylindrical iron plate 26 and the outer cylindrical iron plate 25. It can be moved from top to bottom through the branch pipe 24. And the refrigerant supply branch pipe 24
The refrigerant discharged from the lower end of the cylinder collides with the core metal bottom plate 27, rises along the outer surface of the refrigerant supply branch pipe 24, and the refrigerant heated by the heat from the outer cylindrical iron plate 25 becomes the outer cylindrical iron plate 25.
The structure is such that the refrigerant is discharged from the refrigerant discharge port 23 above.

The lower mandrel 16 is fixed in contact with the lower part of the cooling mandrel 15 by mechanical fastening means such as bolts and nuts, or welding means. Then, as shown in FIGS. 2 and 3, the lower core metal 16 is made of copper (heat conductivity: 0.94 cal / cm · sec · de), which is an example of a high thermal conductive metal.
The rod 28 of g) is steel (thermal conductivity: 0.12 cal / cm · sec · deg), which is an example of a low thermal conductive metal.
It is formed by being embedded in a number of cylinders 29 in parallel with the central axis thereof. The upper end of the copper rod 28 serves as a protrusion 30 and protrudes outward from the steel cylinder 29. The protrusion 30 penetrates the cored bar bottom plate 27 of the cooling cored bar 15 for cooling. The heat transfer between the core metal 15 and the protrusion 30 can be efficiently performed. In addition, the cooling core 15
At the contact portion with the cooling rod 15 from the copper rod 28
When it is possible to secure a necessary amount of heat transfer to, the protrusion 30 need not be provided.

The refractory material 18 disposed inside the cooling core metal 15 and the lower core metal 16 is a refractory brick such as a magnesia chrome material, which is required along the inner side of each core metal 15, 16. Correspondingly, the refractory lining of the inner portion of the dip pipe 12 is applied by laminating the mortar through the mortar. On the other hand, the refractory material 19 arranged on the outer side of each core metal 15 and 16 is an amorphous refractory material composed of alumina, magnesia castable, etc., and is mixed with water or the like to form a slurry or kneaded clay. The mixture is poured into a cylindrical form frame arranged around the cooling core metal 15 and the lower core metal 16 while applying vibration as needed, and the mixture is cured to cool the core metal 15 and the lower core metal 16. A refractory lining on the outer portion of the cored bar 16 is formed.

The results of the actual vacuum refining process using the vacuum refining equipment 10 in which the lower core metal 16 as described above is incorporated will be described below. FIG. 5 shows a lower core metal 16 (symbol: ●) of the immersion pipe 12 according to the first embodiment, and a lower metal core 16a (symbol: steel cylinder of a conventional example).
It is a graph in which the temperatures in () and () are measured and compared for each number of vacuum refining treatments. Particularly, in the vacuum refining treatment after about 100 times, the temperature of the lower core metal 16 is about 150 compared to the conventional example.
It shows that the temperature can be reduced by ° C. Further, in addition to the above-described cooling effect, since the cooling medium does not exist even when the lower core metal 16 at the lower end of the immersion pipe 12 is damaged, the leaked cooling medium is blown into the molten steel 14,
There is no risk of causing an accident such as a steam explosion, the psychological burden on the operator in the vacuum refining process is reduced, and the refractories 18 and 19 can be safely used up to the use limit. In addition, in the present embodiment, not only the cooling core metal 15 but also the lower core metal 16 itself is maintained in mechanical strength so that the refractory materials 18 and 19 are securely restrained and supported by the lower core metal 16. As shown in FIG. 6, the life of the immersion pipe 12 was 750 times, which was about 550 times in the conventional example.
It was possible to obtain a remarkable effect of extending the time. The symbol (⊚) indicates each average value of the life of the immersion tube, and the length of the line segment indicates the range of the life. Further, during the vacuum refining process, excessive stress is generated in the lower core metal 16 supporting the refractories 18 and 19 each time due to mechanical shock, damage to the refractories 18 and 19, and heat load. The mechanical strength of the lower core metal 16 against the stress sharply decreases as the core metal temperature rises. Therefore, it is possible to cool the lower core metal 16 to maintain the required mechanical strength. The above results show that it is effective.

Next, the dip tube 12 according to the second embodiment of the present invention will be described. Here, FIG. 4 is a perspective view of the lower core metal 17 having a cylindrical shape, and a steel cylinder 29 is provided on the outer side and the inner side of the copper cylinder 28a which is a high thermal conductive metal.
a is closely attached. And the copper cylinder 28a
The upper end of the cored bar bottom plate 27, which is the lower end of the cooling cored bar 15.
It is fixed so that it comes into contact with. At this time, the upper end of the steel cylinder 29a is joined to the lower end of the cooling mandrel 15 by means such as welding to maintain the structural strength of the mandrel itself. Therefore, in the dip tube in which such a lower core metal 17 is incorporated, while having the necessary structural strength, heat moves from the steel cylinder 29a to the copper cylinder 28a,
Further, this heat is passed through the portion of the copper cylinder 28a exposed at the upper end of the lower core metal 17 and the cooling core metal 15 arranged on the upper part.
Move to Therefore, a large effective heat transfer area for the amount of heat flowing into the lower core metal 17 from the periphery of the immersion pipe can be obtained, and the steel cylinder 29a can be efficiently cooled. It is also possible to further increase the heat transfer area by forming irregularities on the heat transfer surface, which is the side surface of the copper cylinder 28a in FIG. 4, and in this case as well, the first embodiment described above is used. Similarly to the above, the effect of extending the life of the immersion tube is obtained, and the adhesion strength between the high thermal conductivity metal and the low thermal conductivity metal is improved.

The embodiment of the present invention has been described above.
The present invention is not limited to these embodiments, and changes in conditions and the like without departing from the spirit are all within the scope of application of the present invention. For example, in the present embodiment, the shape of the high thermal conductive metal is a rod (rod shape) or a cylindrical shape, and this is placed in the low thermal conductive metal to form the lower core metal. The conductive metal may have a prismatic shape, a plate shape, or the like, or the high heat conductive metal forming a cylinder may be divided into a plurality of pieces in the circumferential direction of the cylinder and embedded in the low heat conductive metal.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a vacuum refining facility.

FIG. 2 is a side cross-sectional view of a cored bar portion of the immersion pipe according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a lower cored bar of the immersion tube.

FIG. 4 is a perspective view of a lower core metal of an immersion pipe according to a second embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the number of immersion pipe treatments and the lower core metal temperature.

FIG. 6 is a comparison diagram of the immersion pipe life in the second embodiment and the conventional example.

FIG. 7 is an explanatory diagram of a cored bar in a conventional example.

[Explanation of symbols]

10 Vacuum Refining Equipment 11 Vacuum Refining Furnace 12 Immersion Pipe 13 Ladle 13a Refractory Material 14 Molten Steel 15 Cooling Core Bar 16 Lower Core Bar 17 Lower Core Bar 18 Refractory 18a Refractory 19 Refractory 20 Flange 21 Refrigerant Supply Header 22 Refrigerant Supply Header 23 Refrigerant Discharge Port 24 Refrigerant Supply Branch Pipe 25 External Cylindrical Iron Plate 26 Internal Cylindrical Iron Plate 27 Core Bar Bottom Plate 28 Copper Rod 28a Copper Cylinder 29 Steel Cylinder 29a Steel Cylinder 30 Projection

Claims (2)

[Claims] 1. A dip tube, which is attached to a lower portion of a vacuum refining furnace and has a refrigerating core bar cooled by a cooling medium and a lower core bar disposed at a lower end of the refrigerating core bar in a refractory, An immersion pipe, wherein the lower core metal is made of a composite of a high thermal conductivity metal and a low thermal conductivity metal, and the high thermal conductivity metal is attached in contact with the cooling core metal. 2. The immersion pipe according to claim 1, wherein the high thermal conductive metal of the lower core metal is provided so as to protrude from the cooling core metal.