JP3108901B2 - DC electric furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC electric furnace used for melting metal materials, refining molten metal, and the like.

[0002]

2. Description of the Related Art As an electric furnace for refining, a current flows between an electrode disposed above a molten metal charged in a furnace and an electrode attached to a furnace wall such as a furnace bottom and a side wall, and a metal material is formed. DC electric furnace for melting and refining molten metal, and alternating current electricity for melting metal materials and refining molten metal by passing current between three electrodes placed above the molten metal charged in the furnace. Furnaces are known. In this type of electric furnace operation, a system that uses the exhaust gas places a preheating tank between the electric furnace and the dust collection equipment, loads the metal material into the preheating tank together with the bucket, and introduces the metal material using the introduced exhaust gas. Was generally preheated.

However, the exhaust gas duct between the electric furnace and the preheating tank is water-cooled because high-temperature gas generated from the electric furnace passes therethrough, and the temperature of the exhaust gas reaching the preheating tank is reduced by the amount of water-cooling. Therefore, the heat possessed by the exhaust gas was not efficiently used for preheating the metal material, resulting in a large loss in thermal efficiency. In addition, white smoke and odor generated when the preheated metal material is transported to the electric furnace together with the bucket has been a serious problem in the working environment.

Therefore, various methods have been proposed for efficiently utilizing the heat of the exhaust gas for preheating the metal material and charging the preheated metal material to the electric furnace without transporting the metal material from the preheating tank to the electric furnace. For example, in JP-A-3-505625, a metal material is preheated in a preheating tower provided on a furnace lid and in a pre-tropical zone formed by a part of the furnace body, and the preheated metal material stored in the preheating tower is removed. An electric furnace characterized by being naturally dropped and charged is disclosed. However, in this case, in the so-called refining period after the metal material stored in the preheating tower provided on the furnace lid naturally drops and melts, the metal material does not remain in the preheating tower and the heat of the exhaust gas heats the metal material. There was no preheating, and there was still a challenge in terms of thermal efficiency.

Therefore, as a technique for solving this problem, for example, in Japanese Patent Laid-Open No. 5-500263, two electric furnaces are arranged, and the metal material stored in the preheating tower of the electric furnace that is being energized naturally is used. After dropping and melting, a method has been proposed in which the other metal material is stored in a preheating tower and exhaust gas is introduced into a standby electric furnace to preheat the metal material to improve thermal efficiency. In JP-A-4-309789, a pre-tropical zone is formed only by a preheating tower, and a door is provided in the preheating tower.
A method has been proposed in which a metal material can always be stored in a preheating tower and heat of exhaust gas in a refining period can be effectively used.

[0006]

Most of the energy for melting metal materials in an electric furnace is electric energy, and in a DC electric furnace, it is the heat of an arc generated from an upper carbon electrode. When considering the energy efficiency in melting metal materials, place an arc that is an energy source at the center of the furnace body as much as possible, that is, arrange the upper carbon electrode, and further place the charging part of the metal material to be melted in the furnace body It is preferable that the center of the metal material is formed as much as possible, and an arc is ignited from the upper carbon electrode at the center of the metal material to dissolve the circumference uniformly. This is a great advantage of a DC electric furnace that requires only one upper carbon electrode, and the energy efficiency is superior to that of an AC electric furnace that requires three upper carbon electrodes. The same is naturally true even if the material is preheated.

However, JP-A-3-505625, JP-A-5-500263, JP-A-4-309
In the case of Japanese Patent No. 789, the preheating tower is installed on the side wall of the furnace body, so that the preheated metal material is charged only on the side wall of the furnace body, and the metal material is not charged. The opposite side wall is not always used to melt the metal material unnecessarily heated by the arc heat, causing a decrease in energy efficiency. Also, since the metal material is charged only in a portion distant from the upper carbon electrode In addition, there is a problem that the dissolution rate is lower than that of a method in which an upper carbon electrode is disposed in the center of a metal material to dissolve it, leading to a decrease in energy efficiency.

Accordingly, the present invention provides a direct current (DC) that increases the thermal efficiency of a metal material due to exhaust gas and also allows the preheated metal material to be charged into the central portion of the furnace body to increase the melting electric energy efficiency of the metal material. It is intended to provide an electric furnace.

[0009]

In order to solve the above-mentioned problems, a DC electric furnace according to the present invention is a DC electric furnace having a preheating tower having a movable door therein, wherein the preheating tower is made of a metal material. An upper part for storing and preheating, and a lower part which is inclined so that a drop port of the preheated metal material is located at the center of the furnace, and wherein the lower part is formed at the center of the furnace lid. A through hole is formed in the lower part, which is located at the center of the furnace body, and a carbon electrode which can be moved up and down is provided in the through hole.

[0010]

According to the present invention, since the preheating tower having the door provided inside the furnace lid is arranged on the furnace lid, the metal material can be always stored in the preheating tower, and the preheated metal is improved while increasing the thermal efficiency by the exhaust gas. Materials can be charged into the center of the furnace body from the lower end of the preheating tower located in the center of the furnace lid, and the upper carbon electrode located in the center of the furnace body has a through hole provided in the inclined preheating tower. The metal material can be further raised and lowered to melt from the central portion of the metal material charged in the furnace.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is an overall vertical sectional view of a DC electric furnace according to the present invention. A furnace bottom electrode 2 is arranged below the furnace body 1, and an upper carbon electrode 3 is arranged above the furnace body 1 in the center of the furnace body 1. A preheating tower 5 having an inclined portion is provided on the furnace lid 4, and a through hole 6 for raising and lowering the upper carbon electrode 3 is provided in a part of the inclined portion of the preheating tower 5. A movable door 8 for holding the metal material 7 is installed inside the preheating tower 5, and a charging port 9 for charging the metal material 7 into the preheating tower 5 and a dust collecting facility (FIG. (Not shown) is provided.

The high-temperature exhaust gas generated during the melting and refining of the metal material 7 passes through the preheating tower 5 and is sent to the dust collecting facility via the exhaust gas duct 10. At this time, the metal material 7 in the preheating tower 5 is efficiently preheated by the high-temperature exhaust gas. When the heating of the metal material 7 charged in the furnace body 1 is completed and the metal material 7 in the preheating tower 5 is charged, the upper carbon electrode 3 is pulled up by an electrode lifting device (not shown), and then the door 8 Is opened and charged. At this time, since the lower end of the preheating tower 5 is located at the center of the furnace lid 4, the metal material 7 in the preheating tower 5 is charged into the center of the furnace body 1. Subsequently, after loading, the door 8 is closed and the upper metallic material 7 is received and stored. After the door 8 is closed in this manner, the upper carbon electrode 3 is lowered to cause an arc to be emitted at the center of the metal material, and melting is started. Thus, in the present invention, the preheating tower 5
It is possible to charge the metal material 7 preheated by the exhaust gas into the center of the furnace body 1, and furthermore, by tilting the lower part of the preheating tower 5, the upper carbon electrode 3 is positioned at the center of the furnace body 1. It is possible to arrange and move up and down through a through-hole 6 provided in a part of the preheating tower 5.

[0013]

As described above, in the DC electric furnace according to the present invention, while preheating the metal material effectively,
It also enables operations that increase the efficiency of use of electric energy for melting and refining metal materials, and greatly contributes to reducing energy costs and improving productivity.

[Brief description of the drawings]

FIG. 1 is an overall vertical sectional view of a DC electric furnace according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace body 2 Furnace bottom electrode 3 Upper carbon electrode 4 Furnace lid 5 Preheating tower 6 Through hole 7 Metal material 8 Door 9 Loading entrance 10 Exhaust gas duct 11 Arc

Claims (1)

(57) [Claims] 1. A DC electric furnace having a preheating tower having a movable door therein, wherein the preheating tower stores a metal material,
An upper portion to be preheated and a lower portion inclined so that a drop port of the preheated metal material is located at the center of the furnace, and the lower portion is connected to an opening formed in the center of the furnace lid. A direct current electric furnace characterized in that a through hole is formed in the lower part, which is located at the center of the furnace body, and a vertically movable carbon electrode is disposed in the through hole.