JPH02263095A - Dc arc furnace wall electrode - Google Patents

Abstract

PURPOSE:To cool efficiently the tip of an electrode inside a furnace which is subjected to marked melting loss and improve its durability by providing a gas passage which is formed, penetrating a sleeve axially and a gas pipeline which blows gas into the furnace by way of said gas passage. CONSTITUTION:A sleeve 5 is fitted into an electrode 4 so that a gas passage 6 is provided, penetrating the sleeve axially 5. The gas 9 which is introduced from a gas supply source by way of a gas pipeline 8 is expanded once at a wind box 7, then transferred to the gas passage 6 so that the sleeve 5 or the tip of a rod-shaped electrode 4 may be cooled by the gas flowing through the gas passage 6. It is, therefore, possible to maintain the tip of the rod-shaped electrode 4 heat-damaged to a remarkable extent, especially by molten metal, at a low temperature and hence improve its durability. If an attempt is made to spray a cooling medium 20 to the rear end of the rod-shaped electrode 4 in addition to the gas cooling, more definite cooling action will be available.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a furnace wall electrode for a DC arc furnace used for melting metal materials, refining molten metal, and the like.

[Conventional technology]

As an arc furnace for refining, a direct current is used to refine the molten metal by passing an electric current between an electrode placed above the molten metal charged into the furnace and an electrode attached to the furnace bottom, side wall, etc. Arc furnaces are known. The bottom electrode in this type of DC arc furnace is exposed to an extremely harsh operating atmosphere due to heat received from the high-temperature molten metal in the furnace, Joule heat generation generated when a supplied current passes through the furnace, and the like.

Therefore, various proposals have been made to improve the durability of hearth bottom electrodes that can withstand this atmosphere. For example, in the furnace wall electrode disclosed in Japanese Patent Publication No. 63-43675, a cooling sleeve for the refrigerant passage is attached around the part of the electrode protruding from the furnace wall (hereinafter referred to as the rear end), and the refrigerant It has been disclosed that the electrodes are forcibly cooled by circulating a coolant such as water through the passage.

[Problem to be solved by the invention]

However, even if the rear end is cooled with a refrigerant, if the internal thermal conductivity of the electrode is low, the tip of the electrode in contact with the molten metal will still remain at a high temperature. Furthermore, since the electrodes are indirectly cooled through the cooling sleeve, the amount of heat transferred from the electrodes to the coolant is also low.

On the other hand, it is the tip of the electrode that is prone to wear and tear, and when the tip is at a high temperature, wear such as melting damage occurs frequently. Therefore, in the above-mentioned method, the cooling capacity is often insufficient, and wear and tear on the electrodes cannot be effectively suppressed.

Furthermore, when water is used as a refrigerant, if the supply of cooling water is interrupted for some reason, the electrodes and cooling sleeve will be heated to a high temperature, making it easy for hot water to leak. At this time, the cooling water remaining in the sleeve comes into contact with the hot molten metal, which is dangerous.

Therefore, in this defense, gas is blown into the furnace through a sleeve provided around the rod-shaped electrode, and this gas is used to cool the rod-shaped electrode and the sleeve over the entire length. It is an object of the present invention to provide a furnace wall electrode that can be efficiently performed, is not dangerous, and has excellent durability.

Another object of the present invention is to provide a furnace wall electrode with improved cooling capacity and excellent durability by directly spraying a cooling medium from an injection nozzle onto the rear end of a rod-shaped electrode.

[Means to solve the problem]

In order to achieve the purpose, the furnace wall electrode of the present invention has a rod-shaped electrode whose tip part penetrates the furnace wall of a DC arc furnace and faces into the furnace, and a space between one surround of the rod-shaped electrode and the furnace wall. It is characterized by comprising a sleeve provided, a gas passage formed by penetrating the sleeve in the axial direction, and a gas pipe for blowing gas into the furnace through the gas passage.

In addition, a rod-shaped electrode whose tip penetrates the furnace wall and faces into the furnace,
The apparatus is characterized in that it includes an injection nozzle that sprays a cooling medium onto the rear end of the rod-shaped electrode protruding from the furnace wall.

Here, a push-up mechanism for advancing the rod-shaped electrode toward the inside of the furnace may be provided, for example, at the rear end of the rod-shaped electrode.

[Effect]

In the present invention, gas is blown into the furnace from outside the furnace through a gas passage provided in a sleeve inserted into the rod-shaped electrode. As this gas passes through the gas passageway of the sleeve, it carries away the heat transferred from the rod electrode to the sleeve. Therefore, even the tip of the rod-shaped electrode facing into the furnace is efficiently cooled. Further, the gas after passing through the gas passage is blown into the furnace to strongly stir the molten metal that is being melted or refined, thereby promoting the melting and refining reactions. Further, the cooling medium is directly sprayed from the spray nozzle onto the rear end of the rod-shaped electrode. Therefore, the rod-shaped electrode is efficiently and strongly cooled.

〔Example〕

Although FIG. 1 shows the case where electrodes are attached to the bottom of a DC arc furnace, it goes without saying that the present invention can be similarly applied to the side walls.

The bottom of the DC arc furnace has a permanent brick 1 lined with a monolithic refractory 2 on the inside and supported on the outside with an iron shell 3. These iron skins 3. A rod-shaped electrode 4 is attached to the bottom of the furnace by penetrating the furnace wall composed of permanent bricks 1 and monolithic refractories 2.

A sleeve 5 is fitted into the rod-shaped electrode 4, and a gas passage 6 is bored through the sleeve 5 in the axial direction. The gas passage 6 is formed by embedding a plurality of thin tubes 6a concentrically inside the sleeve 5, as shown in FIG. Alternatively, the gas passage 6 may be formed in the brick itself constituting the sleeve 5. A wind box 7 communicating with the gas passage 6 is provided at the lower end of the sleeve 5.
A gas pipe 8 is connected to.

The gas 9 sent from the gas pipe 8 removes the heat transmitted from the rod-shaped electrode 4 to the sleeve 5 while passing through the gas passage 6, and is then blown into the furnace. Therefore, the tip of the rod-shaped electrode 4 and the sleeve 5 are cooled over their entire length, and the inner part of the furnace, which is exposed to a particularly harsh atmosphere, is protected.

In addition, the gas pipe 8 is branched to form a separately provided wind box 10.
Gas can also be blown out between the sleeve 5 and the rod-shaped electrode 4 and used as the sealing gas 11.

A conductive arm 12 is connected to the rear end of the rod-shaped electrode 4, and power is supplied to the rod-shaped electrode 4 via this conductive arm 12. It is also possible to incorporate a water cooling mechanism into the rod-shaped electrode 4 to which the conductive arm 12 is connected, which feeds cooling water from the water supply pipe 13, cools the connection part with water, and then drains the water through the drain pipe 14.

Furthermore, in the example shown in FIG. 1, a push-up mechanism 15 is disposed at the rear end of the rod-shaped electrode 4 in order to advance the rod-shaped electrode 4 toward the inside of the furnace. The push-up mechanism 15 is attached to a support arm 16 fixed to the furnace wall, and its pushing surface faces the rear end of the rod-shaped electrode 4 with an insulator 17 in between. When the tip of the rod-shaped electrode 4 is worn out by molten metal in the furnace and its length becomes short, the push-up mechanism 15 is driven to advance the rod-shaped electrode 4 in the direction of the furnace, and the amount of wear is replaced by the pushing amount. Complete with. Thereby, the frequency of replacing the rod-shaped electrode 4 can be significantly reduced.

FIG. 3 shows an example in which a cooling medium is sprayed onto the rear end of the rod-shaped electrode 4 for cooling. That is, a plurality of injection nozzles 18 are arranged concentrically and in multiple stages around the peripheral surface of the rear end of the rod-shaped electrode 4 protruding from the furnace wall. The cooling medium 20 supplied via the supply pipe 19 is sprayed onto the circumferential surface of the rod-shaped electrode 4 from the injection nozzle 18 to cool the rod-shaped electrode 4 . When cooling water is used as the cooling medium 20 in this method, even if the water supply is stopped for some reason, there is no place for cooling water to accumulate around the rod-shaped electrode 4, so there is no danger of a steam explosion or the like.

In order to prevent the cooling medium 20 injected from the injection nozzle 18 from scattering around, the periphery of the lower end of the rod-shaped electrode 4 is surrounded by a casing 21 to form a closed space. A discharge pipe 22 is opened at the bottom of the casing 21 , and the cooling medium 20 injected from the injection nozzle 18 is forcibly discharged through the discharge pipe 22 by a discharge pump 23 .

Note that a power supply cable 24 is connected to the rear end of the rod-shaped electrode 4, and electricity is supplied to the rod-shaped electrode 4 via this power supply cable 24. Further, an insulator 25 is provided at the outlet of the gas pipe 8 from the iron shell 3 and in the middle of the gas pipe 8 to prevent electrical leakage through the gas pipe 8. Although this insulator 25 is omitted in FIG.
It is provided in the same manner as shown in the figure. Also, for the same purpose,
An insulator 26 is also interposed between the supply pipe 19 and the discharge pipe 22.

Gas 9 is fed into wind box 7 via gas piping 8 from a gas supply source (not shown). As the gas used at this time, in consideration of cooling the rod-shaped electrode 4 and sleeve 5, it is preferable to use a low-temperature gas at about atmospheric temperature. The introduced gas 9 is once expanded in the wind box 7 and then sent into the gas passage 6.

Therefore, there is no change in the flow rate between the gases 9 passing through the individual gas passages 6, and the gases 9 pass through the gas passages 6 and into the furnace with a uniform flow rate distribution over the entire circumference of the sleeve 5. .

The gas 9 flowing through the gas passage 6 cools the sleeve 5 and, in turn, the tip of the rod-shaped electrode 4 . In other words, the rod-shaped electrode 4 is connected while the heat from the tip is conducted to the rear end as in the conventional case.
Since this method does not cool the rear end of the rod-shaped electrode 4, the entire rod-shaped electrode 4 is uniformly cooled regardless of the thermal conductivity of the rod-shaped electrode 4. Therefore, the tip of the rod-shaped electrode 4, which is subject to particularly severe erosion due to molten metal, can be maintained at a low temperature, and its durability is greatly improved. In addition to the cooling by the gas 9, when the cooling medium 20 is sprayed onto the rear end of the rod-shaped electrode 4, the cooling effect becomes even more reliable.

The gas 9 blown into the furnace passes through a pine mushroom-shaped multilayer metal structure with fine holes formed by gas cooling near the tip of the rod-shaped electrode 4, and then diffuses into the molten metal inside the furnace. considered to be a thing. That is, direct contact between the tip of the rod-shaped electrode 4 and the molten metal or static pressure of the molten metal applied to the tip of the rod-shaped electrode 4 and the sleeve 5 is reduced by blowing the gas 9;
It is assumed that this increases the lifespan of the

〔Effect of the invention〕

As explained above, in the furnace wall electrode of the present invention,
Gas is sent into the furnace through a sleeve fitted over the rod-shaped electrode, and the rod-shaped electrode and sleeve are cooled by this gas. Therefore, the entire length of the sleeve and the tip of the rod-shaped electrode are efficiently cooled, and the life of the electrode is greatly extended. In particular, melting damage of the tip of the sleeve and rod-shaped electrode facing the inside of the furnace is suppressed, so no corners are formed in the surrounding monolithic refractories, and no corner chips are removed. In addition, the blown gas has the effect of stirring the material being melted or refined, so that the melting or refining can be performed quickly.

Furthermore, even when cooling water is used as a cooling medium, for example, the electrodes are efficiently and strongly cooled, and the life of the electrodes is dramatically extended. In addition, since circulating water is not used and the water is sprayed onto the peripheral surface of the rear end of the rod-shaped electrode, there is no accumulation around the rod-shaped electrode, and the furnace wall electrode is cooled without the risk of steam explosion. will be held. Furthermore, when the rod-shaped electrode is advanced toward the inside of the furnace in accordance with wear and tear, the frequency of replacing the rod-shaped electrode is significantly reduced, so that operability is also improved.

[Brief explanation of drawings]

Figure 1 shows an example in which the furnace wall electrode of the present invention is applied to the bottom of a DC arc furnace, Figure 2 shows details of the gas passage provided in the sleeve, and Figure 3 shows the rear end of the rod-shaped electrode being sprayed. An example of cooling is shown. 4: Rod-shaped electrode 5 Ni sleeve 6: Gas passage 8: Gas piping 15: Push-up mechanism 18: Injection nozzle 20: Cooling medium

Claims (1)

[Claims] 1. A rod-shaped electrode whose tip passes through the furnace wall and faces into the furnace, and a sleeve provided between the periphery of the rod-shaped electrode and the furnace wall;
a gas passage formed axially through the sleeve;
A furnace wall electrode for a DC arc furnace, comprising a gas pipe for blowing gas into the furnace through the gas passage. 2. It is characterized by comprising a rod-shaped electrode whose tip penetrates the furnace wall and faces into the furnace, and an injection nozzle that sprays a cooling medium onto the rear end of the rod-shaped electrode that protrudes from the furnace wall to the outside. Furnace wall electrode of DC arc furnace. 3. A rod-shaped electrode whose tip passes through the furnace wall and faces into the furnace, and a sleeve provided between the periphery of the rod-shaped electrode and the furnace wall;
an injection nozzle for spraying a cooling medium onto the rear end of the rod-shaped electrode protruding from the furnace wall; a gas passage formed by passing through the sleeve in the axial direction; and a gas passageway for introducing gas into the furnace. A furnace wall electrode for a DC arc furnace, characterized in that it is equipped with a blowing gas pipe. 4. A furnace wall electrode for a DC arc furnace, comprising a push-up mechanism for advancing the rod-shaped electrode according to any one of claims 1 to 3 in the direction of the furnace.