JPS6148511A - Vacuum degassing device - Google Patents

Abstract

PURPOSE:To provide a titled device which melts away efficiently the base metal sticking to the wall surface of the lining refractory wall thereof with a simple construction by providing a panel heating element consisting of conductive ceramics to the surface of said refractory wall and conducting electricity thereto through plural ceramic electrodes. CONSTITUTION:The heating element panel 22 consisting of the conductive ceramics is provided to the surface of the lining refractory wall 11 of the vacuum vessel 15 which sucks the molten steel 13 in a ladle 14 by the gaseous Ar blown through an Ar supply pipe 10 and degasses the molten steel by the evacuation while forming circulating flow through a riser pipe 12. The plural ceramic electrodes 20-1, 2 and current conducting circuit 25 are provided thereto. The electrodes 20-1, 2 are constituted of the material having good electrical conductivity and high-temp. strength and the heating part 21 of the panel 22 is formed of the material having high corrosion resistance and heat resistance as well as high electric resistance. Electricity is conducted to the panel 22 by the above-mentioned circuit 25 to generate heat in the heating part 21 by the resistance by which the metal 16 sticking to the wall surface is easily melted away at good electrical efficiency.

Description

[Detailed description of the invention] (Industrial application field) This invention relates to a vacuum degassing device.

(Prior art) It is well known that in recent years, the steel industry has been moving towards higher grade steel.In order to produce this high grade steel, RH
Since refining of molten steel using a vacuum degassing device such as the above is essential, the usage ratio of vacuum degassing devices is rapidly increasing.

By the way, in a molten metal container such as an RH, a large amount of base metal adheres to the inner wall surface of the container, forcing the container to be shut down early.The reason for this will be explained below with reference to FIG.

In the vacuum degassing device (RH), a large amount of Ar gas is blown into the molten steel 13 in the riser pipe 12 through the Ar supply pipe 10 . The injected Ar gas sucks up the molten steel 13 in the ladle 14 into the riser pipe 12 and discharges it into the vacuum chamber 15 according to the principle of a gas lift pump. This creates a circular flow like this. At this time, the molten steel 13 undergoes degassing reactions such as decarburization and dehydrogenation at the interface within the vacuum chamber 15, and Ar bubbles within the molten steel 13 cause
It also participates in the bubble degassing reaction and promotes the effective degassing reaction of the molten steel 13.

In this way, the Ar gas blown into the riser pipe 12 acts as a working fluid for the molten steel 13, and the molten steel 1 in the vacuum chamber 15
It has two functions: constantly renewing the degassing reaction interface of No. 3, and promoting bubble degassing.

However, when a large amount of Ar gas is blown into the vacuum chamber 15, the Ar gas expands significantly at the interface due to the rapid heating by the molten steel 13 and the reduced pressure in the vacuum chamber 15, generating a large amount of splash. This generated splash is transferred to the vacuum chamber 1.
It scatters over a wide area within the interior of the refractory 5 and adheres to the surface of the lining refractory, which has a relatively low temperature, to form an adhered metal 16.

This deposited metal increases as the number of times the degassing device is used increases, and for example, deposited metal deposited around the alloy addition hole 170 blocks the alloy addition hole, or even becomes left behind. Alloy addition becomes impossible. Furthermore, the enlarged adhered metal flakes off from the refractory during the degassing process, and the molten steel 13
As a result, the composition and temperature of the molten steel 13 are disturbed, causing trouble in the refining process.

To solve the problems caused by the adhered metal mentioned above!
Conventionally, a method has been used to prevent the growth of the deposited metal by installing a graphite electrode 18 in the vacuum chamber 15 and heating the electrode.

However, although the method of heating the inside of the vacuum chamber 15 using the graphite electrode 18 is an effective means of suppressing the growth of deposited metal locally, it requires a large amount of heat in order to heat the deposited metal over a wide range within the vacuum chamber 15. There was a problem in that it consumes a lot of electricity and increases equipment costs.

In order to solve these problems, the present applicant previously proposed a method for preventing base metal adhesion within an RH vacuum degassing tank in Japanese Patent Application Laid-Open No. 52-105516.

(Problems to be Solved by the Invention) The present invention uses ceramics with good electrical conductivity and high-temperature strength for electrodes in a steelmaking furnace to melt and remove bare metal adhering to the furnace equipment. The section provides a panel-shaped ingot melting device with two types of structure made of ceramics with high electrical resistance.

(Means and effects for solving the problem) The present invention forms a heat generating part made of conductive ceramics into a panel shape, and uses the heat generating body panel provided with a plurality of ceramic electrodes as a fireproof lining for a vacuum degassing tank. This vacuum degassing device is characterized in that it is provided on a wall surface of a wall, and an energizing circuit is formed between the electrodes.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is an overall explanatory diagram of the present invention, FIG. 2 is a detailed explanatory diagram of the present invention, FIG. 3 is a perspective view of a heating element panel of the present invention, and FIG.
Figures (a) and (b) are partially enlarged views of Figure 3.

The vacuum degassing device 15 of the present invention has a heating element panel 22 disposed on the wall surface of the lining fireproof wall 11 of the vacuum degassing tank, but the description of other components that are the same as the conventional device will be omitted.

That is, the heat generating panel 22 of the present invention includes a heat generating part 21 made of conductive ceramics and a plurality of ceramic electrodes (hereinafter referred to as current carrying parts) 20-1 and 20-2.

According to actual sales, it is preferable that the combination of the heat generating part and the current carrying part be in accordance with Table 1.

Table 1 Accordingly, it is preferable that the heat generating part is made of a material having an electrical resistance of 100 times or more that of the current carrying part.

The heating element panel 22 of the present invention is fixed to the wall surface of the lining fireproof wall of the vacuum degassing tank, and the current-carrying section 20 is provided with a current-carrying circuit 25. The current-carrying part 20 is mechanically connected to the heat-generating part 21 by, for example, a tapered screw 25 or a taper 26.

Adhesion using mortar such as graphite or carbon is also effective for this connection, but the mechanical connection has low connection resistance and has caused fewer troubles.

The present invention has high corrosion resistance, heat resistance, and a panel-shaped ceramic heating element with high electrical resistance is installed in the tank.
The so-called two-structure panel-shaped metal melting device that supplies electricity is made of ceramics that have good electrical conductivity. Generates heat and easily melts adhered metal.

(Effects of the Invention) The present invention utilizes the resistance heating of the panel-shaped heating element by disposing the panel-shaped heating element made of ceramics having resistance heating characteristics on the fireproof wall lining the vacuum degassing tank. So,
The metal can be easily dissolved and removed, and its industrial effects are significant.

[Brief explanation of drawings]

Fig. 1 is an overall explanatory diagram of the present invention, Fig. 2 is a detailed explanatory diagram of the present invention, Fig. 3 is a perspective view of main parts of the invention, and Fig. 4 (a).
, Tb) are partially enlarged views of the present invention, and FIG. 5 is an explanatory view of a conventional example. 21...Heating part 22...Panel heating element 2
0... Current-carrying part Fig. 1 Noah Fig. 4 Fig. 5

Claims (1)

[Scope of Claims] 1 A heating element made of conductive ceramic is formed into a panel shape, and a heating element panel provided with a plurality of ceramic electrodes is provided on the wall surface of a fireproof wall lining a vacuum degassing tank, A vacuum degassing device characterized in that a current-carrying circuit is formed between the two. 2. The vacuum degassing device according to claim 1, further comprising a heating element panel in which the electrical resistance of the heating element is greater than the electrical resistance of the electrodes.