JPH08319511A - Immersion tube for vacuum degassing apparatus - Google Patents

Abstract

PURPOSE: To restrain the looseness of a lower step part, fall-down, invasion of a metal, etc., so as to improve the durability by applying a thermal deformation preventing countermeasure to a cylindrical iron core of an immersion tube for a vacuum degassing apparatus. CONSTITUTION: In the immersion tube 11 for the vacuum degassing apparatus, a metal-made rib 17 is arranged in vertical direction inside of the cylindrical iron core 14 arranged in a refractory material. This immersion tube is actually used to recognize the deformation preventing effect. As this result, the durability is improved to about 1.3 times and the damage of the lower step part is less and the repairing work is drastically reduced and these effects are remarkably confirmed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a dip tube for a vacuum degassing device, which is mainly intended to suppress lower damage and improve durability.

[0002]

2. Description of the Related Art In recent years, as the mass production of steel has become higher, vacuum refining methods mainly for degassing and C removal, especially RH degassing, D
The H 2 degassing method is generally adopted. The portion of the RH degassing device that is immersed in the molten steel is called a dip tube and generally has the structure shown in FIG. A magnesia-chromium direct bond brick, which has high resistance to hot wear, is applied to the inner lining bricks 2 through which the molten steel is refluxed, and a high alumina castable material is supported from the cylindrical iron core 4 on the outer peripheral portion 3 where the heat cycle is severe. It is fixed and arranged by metal fittings or anchors 6. Various factors such as wear of inner bricks, small residual size due to spalling, melting loss of outer castables, intrusion of metal due to cracks, or dropout of the lower part may occur depending on the operating conditions. There is. Among them, damage to the lower stage, especially falling out, invasion of bullion, etc. are causes of unexpected short life and require urgent spraying repair work, productivity decrease and major problem in terms of original cost per repair Has become. Originally, this is because the iron core existing inside the refractory material is affected by the heat of molten steel and deteriorates in strength, expands and deforms, loosening the lower-stage brick and promoting cracking (Fig. 2). As measures against this, various measures to prevent iron core deformation and improvements in the brick support structure have been taken, but they have not been used stably. It was an essential improvement item for the stable use of the immersion tube for the vacuum degassing device.

[0003]

The cylindrical iron core of the dip tube for a vacuum degassing apparatus is provided with a measure to prevent thermal deformation so as to eliminate loosening, dropping and invasion of metal in the lower part.

[0004]

A cylindrical iron core 14 according to the present invention has reinforcing ribs 17 provided vertically only on the inner side. Placing ribs on the outer side of the iron core 14 is thought to result in promoting the generation of cracks on the contrary, so the ribs are limited to the inner side only. FIG.
1. A cylindrical iron core 1 arranged in a refractory material according to the invention
4 is a vertical cross-sectional view of the vacuum degassing dip tube 11 provided with a metal rib 17 in the vertical direction inside thereof, and FIG.
-A sectional drawing is shown. Since the distance between the iron core 14 and the lining brick 12 is normally as small as 15 to 30 mm, ribs having a height higher than that cannot be arranged, but the number in the circumferential direction is not limited. However, considering the workability and the cost of the iron core, it is considered that about 6 to 12 is appropriate. Regarding the length in the vertical direction, the deformation due to heat is generally about 300 mm from below as shown in FIG. The material is the same as that of the iron core, and there is no problem.

[0005]

EXAMPLE A rib having the following size was provided on a cylindrical iron core 14 of an immersion tube of a 250 t capacity RH vacuum degassing apparatus.・ Iron core size Inner shape 950mm, Thickness 15mm, Height 7
00mm ・ Rib size 20mm height, 15mm thickness, 35 length
Twelve 0 mm main metal ribs 17 in the circumferential direction from the lower end (every 30
Degree) We prepared an iron core arranged by welding. There was no need to change the method of casting the bricks from the conventional one, and it was carried out by a general method.

[0006]

INDUSTRIAL APPLICABILITY The PH vacuum degassing apparatus dipping pipe of the present invention has two
It was mounted on the lower layer of the 50tRH degassing device and used. The operating temperature is 1630 ° C, the operating time is 15 minutes / ch, the service life of the conventional product is 165 ch, and the thermal deformation of the iron core is such that the bottom part of the iron core expands outwardly in the outer diameter direction by about 150 mm and the iron core is partially melted by heat. However, the immersion tube of the present invention is 215c under the same use condition.
It was durable and almost kept its original shape, and the effect of preventing deformation was confirmed. As a result, the service life was improved by about 1.3 times, and the damage to the lower part was small, so that the repair work was also significantly reduced, and the effect was remarkably confirmed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a conventional dip tube for a vacuum degassing apparatus.

FIG. 2 is a vertical cross-sectional view of a conventional dip tube for a vacuum degassing device when it is discarded.

FIG. 3 is a vertical sectional view of a dip tube for a vacuum degassing apparatus according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view taken along the line AA of the dip tube for the vacuum degassing device according to the embodiment of the present invention.

[Explanation of symbols]

 1 Conventional immersion tube for vacuum degassing equipment 2 Inner brick 3 Outer castable 4 Iron core 5 Flange 6 Anchor 11 Immersion tube for vacuum degassing equipment 12 of the present invention 12 Inner brick 13 Outer castable 14 Iron core 15 Flange 16 Anchor 17 Metal ribs

Claims (1)

[Claims] An immersion pipe for a vacuum degassing device, characterized in that a metal rib is provided in a vertical direction inside a cylindrical iron core arranged in a refractory material.