JPH05171251A - Vacuum degassing apparatus - Google Patents

Abstract

PURPOSE:To efficiency melt and remove metal locally stuck in a vacuum vessel. CONSTITUTION:Water cooling type induction coils 7 are vertically divided into a block 1 to a block 4 and wound in the interval between an iron shell 8 and a refractory 6 in the vacuum vessel 12, and respective blocks are independently controlled. By supplying AC to the induction coils 7 in the block 1 and 2 corresponding to the position sticking the metal 10, the metal 10 is melted and removed. As the induction coil to only the block sticking the metal 10 is used, power consumption can be saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum degassing apparatus suitable for removing metal locally adhered to a vacuum chamber.

[0002]

2. Description of the Related Art For example, a reflux type (RH type) vacuum degassing apparatus is designed to degas in a vacuum tank while circulating molten steel through an ascending pipe and a descending pipe provided in the vacuum tank. .. Argon gas for recirculation is blown into the rising pipe, and the molten steel rising in the vacuum degassing tank splashes and scatters, so that it is inevitable that metal is attached to the inner wall of the tank.

If the molten steel is vacuum degassed while the metal is adhered and grown in the degassing tank as described above, the metal is dropped during the vacuum degassing process, which causes contamination of the molten steel. Further, if the metal attached to the tank becomes a large mass, it will also hinder the vacuum exhaust system, so it is necessary to dissolve and remove the attached metal early. Generally, in a vacuum degassing tank, when dropping the metal, oxygen is directly blown to the metal by an oxygen burner to melt it by utilizing the heat of oxidation reaction of iron, and the electrode (carbon rod) inserted in the degassing tank is used. There is known a means for heating the inside of the tank to melt the metal. In addition, as a means using induction heating, Japanese Patent Laid-Open No. 62-124212 discloses a vacuum degassing apparatus that sucks molten steel into a vacuum tank to perform vacuum degassing, and the vacuum tank is electrically conductive and wets the molten metal. Disclosed is a vacuum degassing device which is formed of a refractory material having good properties and which is provided with an induction coil around the vacuum chamber.

[0004]

Among the means for melting the metal in the degassing tank according to the above-mentioned prior art, the one that is directly melted to the metal by using an oxygen burner or the like to remove only a part of the metal is removed. In addition to being unable to do so, it was a high heat work and inefficient. Further, in the case of using the electrode, there is a risk that the carbon rod may drop and increase the carbon content of the molten steel.
Further, in the induction heating method, the vacuum chamber is made of a conductive refractory material so that the entire degassing chamber is heated, and there is a problem in that the power cost increases and the cost increases.

The present invention solves the above problems of the prior art,
The purpose is to reliably remove the metal locally adhered to the degassing tank without increasing the cost.The induction coil is divided and wound in the vertical direction of the degassing tank. The main idea is to locally heat only the place to melt the metal with energy saving.

[0006]

The present invention for attaining the above object provides a vacuum degassing apparatus for vacuum degassing by sucking molten steel into a vacuum tank having a refractory lined inside a steel shell. Inside the iron shell of the tank, wind the water-cooled induction coil around the refractory in multiple blocks in the vertical direction.
A vacuum degassing device characterized in that the water-cooled induction coil of each block is independently controlled to inductively heat and melt and remove the metal locally adhered to the vacuum tank. Is.

[0007]

[Operation] According to the present invention, the metal adhered in the RH degassing tank can be melted with energy saving by locally applying an electric current to the induction coil only at the portion to be dropped by induction heating. .. Further, according to the present invention, labor can be saved by automating the melting of the metal.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a vacuum degassing apparatus according to the present invention,
The vacuum degassing tank 12 has a structure in which a refractory 6 is lined on a cylindrical iron shell 8, and MgO + Cr ₂ O ₃ is used as the refractory material. An ascending pipe 13 and a descending pipe 14 are provided at the lower end of the vacuum degassing tank 12, and a vacuum exhaust port 9 is provided at the upper part. The vacuum exhaust port 9 is connected to a vacuum pump (not shown). Has been done.

In the present invention, the periphery of the refractory material 6, that is, the iron skin 8
The water-cooled induction coil 7 is wound inside the refractory 6 inside, for example, the induction coil 7 wound around the middle tank 15 is divided into three blocks of block 1, block 2 and block 3 from the top, and the bottom part is also divided. The water-cooled induction coil 7 wound around the tank 16 is divided into a total of four blocks as a block 4, and each of the four blocks can be independently controlled. As shown in detail in FIG. 2, the structure of each block is such that a copper coil tube capable of flowing water through a cooling plate 5 is wound around a refractory material 6 to form a water-cooled induction coil 7. The heating of the iron shell 8 existing outside the water-cooled induction coil 7 is prevented.

In the vacuum degassing apparatus of the present invention, during the degassing process, a portion of the vacuum degassing tank 12 having a large amount of metal deposits, that is, a refractory material when the water-cooled induction coil 7 corresponding to blocks 1 and 2 is energized Induction current flows through 6 and the upper part of the middle tank 15 itself is heated, and due to the skin effect of induction heating, the adhered metal
Are dissolved and removed. In addition, block 4 of the lower tank 16
The water-cooled induction coil 7 wound around is used not only for melting the metal but also for controlling the temperature of the molten steel 11. In the induction heating corresponding to the position where the metal is adhered, heat is generated instantaneously, so that the time for melting the metal is short and the temperature of the molten steel 11 is also increased instantaneously, so that the time for degassing the molten steel is shortened.

Although the above embodiments have been described for the case of the RH type vacuum degassing apparatus, the present invention is also applicable to other types of vacuum degassing apparatus such as the DH type.

[0012]

According to the present invention, since the coil is divided and wound in the vacuum degassing tank, the metal can be locally melted, so that the power consumption can be reduced. Further, since it is easy to automate, it is easy to achieve labor saving.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a vacuum degassing tank according to the present invention.

FIG. 2 is an enlarged detailed vertical sectional view showing a portion A of FIG.

[Explanation of symbols]

 1 block 2 block 3 block 4 block 5 Cooling plate 6 Refractory 7 Water-cooled induction coil 8 Iron shell 9 Vacuum exhaust port 10 Metallurgical 11 Molten steel 12 Vacuum degassing tank 13 Rise pipe 14 Downcomer pipe 15 Middle tank 16 Lower tank

Claims (1)

[Claims] 1. A vacuum degassing apparatus for vacuum degassing by sucking molten steel into a vacuum tank having a refractory lined inside the iron shell, and a water-cooled induction coil is vertically moved to the refractory inside the iron shell of the vacuum tank. It is divided into several blocks and wound around each direction, and by independently controlling the water-cooled induction coil of each block, the metal locally adhered to the vacuum chamber is heated by induction to dissolve and remove it. Vacuum degassing device characterized in that