JPH09279222A - Lining structure of vacuum molten steel treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability and heat insulation in a vacuum molten steel treating apparatus lined with monolithic refractory. SOLUTION: In the vacuum molten steel treating apparatus which can separate by dividing a vacuum vessel into plural number in the vertical direction, the lining of the monolithic refractory 8 interposing heat insulating material 6 on the inside of the iron shell 5 constituting the vacuum vessel, is arranged to at least a lower vessel in the divided vacuum vessel. Further, at the upper end part of this lining, the lining of the monolithic refractory 8 without interposing the heat insulating material, is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lining structure of a vacuum molten steel processing apparatus using an amorphous refractory having both durability and heat insulation.

[0002]

2. Description of the Related Art Secondary refining treatment of molten steel has become indispensable from the recent trend toward higher quality steel. Various vacuum molten steel processing devices are used for the secondary refining of the molten steel.

The inner lining of this vacuum molten steel processing apparatus has been made of bricks, but recently, for example, as disclosed in Japanese Patent Laid-Open No. 6-300438, for the purpose of labor saving and mechanization of the inner lining construction, an indefinite fire resistance has been proposed. A lining with objects is proposed.

[0004]

FIG. 3 shows a vertical cross section of an RH type vacuum degassing apparatus as an example of a vacuum molten steel processing apparatus. At the lower end of the vacuum tank (1), a snorkel (2) for circulating the molten steel in the ladle into the vacuum tank (1) is provided.

The vacuum chamber (1) can be divided into a plurality of parts in the vertical direction by a flange (4) so as to facilitate the construction and repair of the lining (3). For example, as shown in the figure, it is divided into a lower tank (A), an intermediate tank (B), and an upper tank (C). Although not shown in the figure, also in a vacuum molten steel processing apparatus such as a DH type vacuum degassing apparatus, the vacuum chamber can be divided into a plurality of parts in the vertical direction and separated for the same reason.

FIG. 2 is an enlarged view of a portion of the lower tank (A) surrounded by a dotted line in the overall view of the vacuum degassing apparatus of FIG. The flange (4) is provided with a sealing property through a packing or the like. However, the flange (4) is deformed by repeated expansion and contraction due to high temperature during operation or contraction due to cooling during rest, and the sealing property is deteriorated, so that invasion of air into the tank is inevitable. Also, lined with amorphous refractory (3)
In the vacuum tank (1), which is inevitably cracked by the thermal shock received during use, the lower tank (A) that is in direct contact with the molten steel undergoes preceding melting loss due to gas leak. This is because the air that has entered from the flange (4) passes through the inside of the tissue of the heat insulating material (6) provided between the lining (3) and the iron skin (5) and travels to the back surface of the lining (3). After that, it is considered that the crack leaks into the vacuum chamber (1) from the cracked portion generated in the lining (3), and the melting loss is promoted by the gas ejection pressure at that time.

The above-mentioned problems do not occur in the brick lining. It is considered that this is because the brick has a higher structural strength than the amorphous refractory, and the gas leak portion is dispersed due to the large number of brick joints, and the gas ejection pressure is small.

An object of the present invention is to solve the above-mentioned conventional problems in a vacuum molten steel processing apparatus lined with an amorphous refractory material.

[0009]

According to the present invention, in a vacuum molten steel processing apparatus in which a vacuum tank is vertically divided into a plurality of pieces which can be separated, a vacuum tank is formed in at least a lower tank of the divided vacuum tanks. Vacuum molten steel characterized in that an insulative refractory lining is provided inside a steel skin with an insulating material interposed, and an insulative refractory lining without the insulating material is provided at an upper end of this lining. This is the lining structure of the processing device. Further, in the vacuum molten steel processing apparatus capable of dividing the vacuum tank into a plurality of parts in the vertical direction and separating them, at least the lower part of the divided vacuum tanks has a heat insulating material interposed inside the iron shell forming the vacuum tank. An inner lining structure for vacuum molten steel treatment is provided, in which an inner lining of an irregular-shaped refractory is provided, and an upper end portion of the inner lining is made thinner than the heat insulating material of the other portions.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical cross-sectional view showing an embodiment of the present invention. In the vertical cross-section of the RH type vacuum degassing apparatus of FIG. 3, a portion corresponding to a portion surrounded by a dotted line of the lower tank (A) is shown. FIG. As shown in Fig. 1, inside the iron skin (5), the heat insulating material (6)
This is the same as the conventional structure in that an inner lining made of an indefinite refractory material (8) is provided via.

The heat insulating material (6) has a role of preventing red heat of the iron shell (5) and reducing heat loss of the molten steel. Having a heat insulating property, it has a porous structure.

According to the present invention, no heat insulating material (6) is provided on the upper end (7) of the lining (3). As a result, the upper end of the heat insulating material (6) is covered with the lining (3). As a result, the atmosphere that has entered from the flange (4) is prevented from entering the back surface of the inner lining of the lower tank, and the melting damage promotion due to the gas leak of the inner lining, which is seen in the conventional structure, does not occur.

In the present invention, the atmosphere that has entered from the flange (4) is prevented from entering the lower tank. As a result, for example, it enters between the inner lining of the lower tank and the inner lining of the intermediate tank or the back surface of the intermediate tank. Since molten steel does not come into direct contact with the
There is no problem of preceding melting loss due to gas leak.

In the present invention, it is preferable that no heat insulating material (6) is provided on the back surface of the upper end (7) of the lining (3) of the lower tank. However, although not shown in the figure, a heat insulating material having a smaller thickness than the heat insulating material provided on the entire back surface of the inner lining of the lower tank may be provided on the back surface of the upper end (7) of the lining (3). . If the thickness of the heat insulating material (6) on the back surface of the upper end portion (7) is reduced, it becomes difficult for the atmosphere to enter the back surface of the lining (3), and there is an effect of preventing the preceding melting loss due to the gas leak. .

In the above-mentioned present invention, the above-mentioned structure is performed at least in the lower chamber (A) of the vacuum chamber (1). This is because the preceding melting loss from the crack caused by the gas leak is limited to the lower tank (A) with which the molten steel is in direct contact. The intermediate tank (B) or the upper tank (C) located above the lower tank (A) does not necessarily have the above structure. The intermediate tank (B) or the upper tank (C) may be lined with bricks.

Further, since the flange joint portion (9) of the lower tank (A) exists at the upper and lower ends, this structure for preventing the invasion of the atmosphere into the heat insulating material (6) has a lower end as shown in FIG. It is more effective if it is provided.

The specific material of the heat insulating material used in the present invention is not limited, and examples thereof include porous boards made of silica or alumina and fiber boards. Alternatively, a porous castable refractory or the like may be used.

The specific material of the amorphous refractory material (8) is not particularly limited. For example, castable refractories such as alumina, alumina-silica, spinel, alumina-spinel, magnesia, and alumina-magnesia. As the binder, for example, alumina cement, magnesia cement, silica sol, alumina sol or the like is used. If necessary, a deflocculant, a curing accelerator, a curing retarder, an organic fiber, a metal fiber, an alumina ultrafine powder, a silica ultrafine powder, coarse particles and the like may be added.

The method of lining the irregular refractory is as follows:
As usual, it is done by pouring using a core. At the time of construction, it is preferable to use a bar-shaped vibrator in order to improve the filling rate.

[0021]

EXAMPLE An example of the present invention was applied to an RH type vacuum degassing apparatus having a vacuum chamber having an inner diameter of a steel shell of 3200 mm.

Referring to FIG. 1, the heat insulating material (6)
Was a siliceous porous board having a thickness of 25 mm. The lining (3) was made of alumina-spinel castable refractory and was applied to a thickness of 465 mm. As shown in the figure, the rear surface of the upper end portion (7) of the inner lining (3) did not include the heat insulating material (6) and was made into an irregular refractory until reaching the iron skin (5).

The thickness of the irregular refractory in the portion covering the heat insulating material (6) at the upper end of the back surface of the lining (3) is 100 mm.
And Further, at the time of construction, the irregular refractory material (8) of the lining (3) and the irregular refractory material of the flange joint part (9) were simultaneously poured into the construction, thereby forming an integrated structure.

Using the vacuum degassing apparatus of this embodiment of the present invention, the molten steel in the 340 ton ladle was degassed, and then the erosion state of the inner lining of the lower tank was observed. Irregular refractory linings inevitably crack due to thermal or structural spalling during use. The preceding melting loss due to the gas leak from the cracked portion was extremely small in the embodiment of the present invention as compared with the conventional structure of FIG.

The melt loss rate is 2.0 m in the conventional structure.
In contrast to m / charge, Example 1 of the present invention was 0.9 mm / charge. As a result, in the example of the present invention, the service life of the lower tank was improved by 2.2 times or more as compared with the conventional structure.

[0026]

INDUSTRIAL APPLICABILITY As described above, the present invention solves the problem of reducing the preceding erosion loss caused by gas leak, which is a peculiar problem when a vacuum molten steel processing apparatus is lined with an amorphous refractory. Amorphous refractory lining for vacuum steel processing equipment
It is expected that the present invention will be expanded more and more in the future due to the labor saving of the inner lining construction, and the present invention is extremely important as a part of the technique for making the amorphous refractory.

[Brief description of drawings]

1 is an enlarged view of a portion corresponding to a portion surrounded by a dotted line in a lower tank (A) of FIG. 3 in an RH type vacuum degassing apparatus of an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion surrounded by a dotted line of a lower tank (A) of FIG. 3 in a conventional RH type vacuum degassing apparatus.

FIG. 3 is a vertical cross section of an RH type vacuum degassing apparatus.

[Explanation of symbols]

 1 Vacuum tank 2 Snorkel 3 Lining 4 Flange 5 Iron skin 6 Insulation material 7 Upper end 8 Unshaped refractory A Lower tank B Intermediate tank C Upper tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuro Fujii 1-3-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Harima Ceramics Co., Ltd. (72) Tomio Mizuno 1-1-3, Niihama, Arai-cho, Takasago, Hyogo Prefecture Harima Ceramic Co., Ltd.

Claims (2)

[Claims] 1. A vacuum molten steel processing apparatus in which a vacuum tank is vertically divided into a plurality of pieces that can be separated, and at least a lower tank of the divided vacuum tanks is provided with a heat insulating material inside a steel shell forming the vacuum tank. A lining structure for a vacuum molten steel treating apparatus, characterized in that an amorphous refractory lining is provided so as to be interposed, and an amorphous refractory lining without the heat insulating material is provided at an upper end of the lining. 2. A vacuum molten steel processing apparatus in which a vacuum tank is vertically divided into a plurality of pieces that can be separated, and at least a lower tank of the divided vacuum tanks is provided with a heat insulating material inside a steel shell forming the vacuum tank. An inner lining structure for vacuum molten steel treatment, characterized in that an insular refractory lining is provided so as to intervene, and an upper end portion of this lining has a thickness of the heat insulating material smaller than that of other heat insulating materials.