JPH09143535A - Immersion tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the long service life, to reduce the cost and to improve the productivity by fixing ceramic fibers to the lower end of a core metal and supporting a monolithic refractory around this ceramic fibers. SOLUTION: Few pieces of the heat resistant ceramic ropes 12 of the aggregate of the ceramic fibers as studs at the tip part of the core metal 2 are fixed to the core metals 2 so as to form in beard-shape and used as the substitution for a stud. To the metal-made studs 10 fitted to the core metal at the upper part of the heat resistant ceramic ropes 11, a heat-resistant ceramic rope 11 is set up in dotted state between the studs and contributed to the prevention of fall-down of the castable refractory. By this method, the tip part of the immersion tube can structurally be stabilized.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to R in molten steel refining.
The present invention relates to a submerged pipe structure of an H-type or DH-type degassing device.

[0002]

2. Description of the Related Art An RH or DH type degassing apparatus removes molten steel in a molten steel ladle by introducing it into a vacuum tank through its dipping pipe and gasifying degassing components in the molten steel. Is. Therefore, since the dipping pipe is directly dipped in the molten steel, it is generally disclosed in JP-A-5-163.
As described in Japanese Patent No. 518, a standard refractory is lined on the inner surface on the side for sucking molten steel, and an irregular refractory is applied on the outer peripheral surface on the outer side. The fixed refractory (brick) lined on the inner surface is supported by the brick receiving metal at the tip of the cored bar of the dip tube, and the irregular refractory on the outer periphery is supported by metal studs welded to the cored bar. ing.

The durability of the dip tube is greatly influenced by the stability of the amorphous refractory (castable) at the tip of the dip tube. That is, when the castables at the tip of the dipping pipe come off due to the progress of cracks generated by structural or thermal spalls, the brick support fitting supporting the brick is melted and the lining brick also comes off.

If damages such as cracks are found in the castables on the outer periphery before the refining process is started, the bricks are repaired by spraying or patching before they are damaged. However, in this case, not only the repair cost is required, but also repair time is required, which causes a production obstacle.

[0005]

However, in the immersion pipe of the conventional structure, in addition to the cracks generated by the thermal spalls of the castables, the thermal expansion of the castables on the outer periphery is supported by the metal studs. The casters are squeezed by the large metal studs
Cracks occur. Then, when the crack progresses, the castables come off, and eventually the lining brick receiving metal is melted and damaged, which causes the lining bricks to come off.

The present invention is intended to prevent the castable from dropping off at the tip of such a dipping tube.

[0007]

According to the present invention, in an immersion pipe of a degassing device in molten steel refining, ceramic fibers or ceramic fiber aggregates are fixed to at least the lower end of a cored bar, and an irregular shape is applied around the ceramic fibers or ceramic fiber aggregates. An immersion pipe having a structure supporting a refractory material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. FIG. 1 is a diagram showing details of a part of the lower tank 7 and the dip tube 8 of the RH vacuum degassing apparatus.

In this figure, the structure of the dip tube shown in the left half is a conventional structure. That is, the immersion pipe lining brick 1 is supported by the brick receiving metal fitting 3 attached to the lower end of the cored bar 2 of the immersion pipe. The castable 6 on the outer periphery is supported by metal studs 5 welded to the core metal 2.
The metal stud at the tip of the dip tube is exposed to high temperature because it is close to molten steel, and its thermal expansion causes the castable to crack. Alternatively, the cracks may be propagated by the heat spall of the castable itself. Due to the progress of the cracks, the castables at the 9th part eventually fall off. In this way, the brick receiving hardware 3 that comes into direct contact with the molten steel is melted and the lining brick 1 is also dropped and damaged.

On the other hand, the dip tube structure described in the right half of FIG. 1 is an example of the structure of the present invention. That is,
At least the stud at the tip of the core metal 2 is a heat-resistant ceramic rope 1 which is an assembly of ceramic fibers.
A few of the two are fixed to the cored bar 2 so as to form a beard, and are used as substitutes for the studs. Further, heat-resistant ceramic ropes 11 are stretched around the metal stud 10 mounted on the cored bar above the metal stud 10 to contribute to preventing castables from falling off.

Table 1 shows the properties of the heat resistant ceramic rope. The thermal expansion of the refractory ceramic rope embedded in the castable is the same level as the castable, no cracks appearing in the case of the metal studs appear, and the castable itself does not fall off due to thermal spall cracks.

[0012]

[Table 1]

[0013]

EXAMPLE The dip tube structure of the present invention was applied to the dip tube of a 300 ton RH degasser. Table 2 shows the comparison with the conventional metal stud structure. That is, conventionally, a part of the castables at the tip of the dip tube falls off, so that spray repair is performed at a rate of 1 time / 5 ch from 20 ch on, 50 kg / do, and the dip tube is replaced when 100 ch is completed. On the other hand, the initial repair is 100 by applying the structure of the present invention.
It extends to ch, and the repair frequency is 1/10 ch and the spraying amount is 20 kg / cycle, and the life is greatly extended to 200 ch, not only cost reduction but also the productivity is greatly improved due to the decrease in repair frequency.

[0014]

[Table 2]

[0015]

According to the present invention described above, the tip of the dipping pipe is structurally stable, and the life is extended, the cost is reduced, and the productivity is improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of a dip tube according to the related art and the present invention.

[Explanation of symbols]

 1 Inner Brick 2 Core Bar 3 Brick Receiving 4 Flange 5, 10 Stud 6 Outer Castable 7 Lower Tank 8 Immersion Pipe 9 Drop Castable 11, 12 Heat Resistant Ceramic Rope

Claims (1)

[Claims] 1. In a dipping tube of a degassing apparatus for refining molten steel, a ceramic fiber or a ceramic fiber aggregate is fixed to at least a lower end of a cored bar, and a structure is formed to support an amorphous material to be applied around it. A dipping tube characterized by the above.