JPH0648142B2 - Wall electrodes of DC arc furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to a furnace wall electrode of a DC arc furnace used for melting a metal material, refining a molten metal, and the like.

[Conventional technology]

As a refining arc furnace, a direct current is used to smelt molten metal by passing an electric current between the electrode placed above the molten metal charged in the furnace and the electrodes attached to the furnace wall such as the bottom and side walls of the furnace. The arc furnace is known. The bottom electrode in this type of DC arc furnace is exposed to an extremely harsh atmosphere due to heat received from the high-temperature molten metal in the furnace, Joule heat generated when a supply current passes, and the like.

Therefore, various proposals have been made to withstand this atmosphere and improve the durability of the bottom electrode. For example,
In the furnace wall electrode of Japanese Patent No. 63-43675, a cooling sleeve for a refrigerant passage is attached around the portion of the electrode protruding from the furnace wall (hereinafter, referred to as a rear end portion), and water or the like is attached to the refrigerant passage. It is disclosed that the electrode is forcibly cooled by circulating the refrigerant.

[Problems to be Solved by the Invention]

However, even if the rear end portion is cooled with a coolant, if the thermal conductivity inside the electrode is low, the front end portion of the electrode in contact with the molten metal remains at a high temperature. Moreover, since the electrode is indirectly cooled via the cooling sleeve, the amount of heat transferred from the electrode to the refrigerant is low. On the other hand, wear is likely to occur at the electrode tip portion, and if the tip portion is at a high temperature, wear such as melting loss is actively performed. Therefore, in the above-mentioned method, the cooling capacity is often insufficient, and the electrode wear cannot be effectively suppressed.

Furthermore, when water is used as the coolant, if the supply of the cooling water is interrupted for some reason, the electrodes and the cooling sleeve are heated to a high temperature, and leakage of water easily occurs. At this time, the cooling water remaining in the sleeve comes into contact with the hot molten metal, which is dangerous.

Therefore, in the present invention, by blowing gas into the furnace through a sleeve provided around the rod-shaped electrode, the 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 is efficient and has no danger and is excellent in durability. Further, another object of the present invention is to provide a furnace wall electrode with improved cooling performance and excellent durability by directly spraying a cooling medium from the injection nozzle onto the rear end of the rod-shaped electrode.

[Means for Solving the Problems]

In order to achieve the object, the furnace wall electrode of the present invention is provided with a rod-shaped electrode whose tip penetrates the furnace wall of a DC arc furnace and faces the furnace, and between the periphery of the rod-shaped electrode and the furnace wall. And 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.

Also, a rod-shaped electrode whose tip penetrates the furnace wall and faces the furnace,
An injection nozzle for spraying a cooling medium is provided on the rear end portion of the rod-shaped electrode protruding from the furnace wall to the outside.

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

[Action]

In the present invention, gas is blown into the furnace from the outside of the furnace through the gas passage provided in the sleeve fitted into the rod-shaped electrode. When this gas passes through the gas passage of the sleeve,
It carries away the heat transferred from the rod electrodes to the sleeve. Therefore, the rod-shaped electrode is efficiently cooled even at the tip end facing the inside of the furnace. Further, the gas after passing through the gas passage also has the action of accelerating the melting and refining reaction by strongly stirring the molten metal during melting or refining by being blown into the furnace. Further, the cooling medium is directly sprayed from the injection nozzle to the rear end of the rod electrode. Therefore, the rod-shaped electrode is efficiently and strongly cooled.

〔Example〕

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

At the bottom of the DC arc furnace, an amorphous refractory 2 is lined inside the perm brick 1, and the outside is supported by a steel shell 3. A rod-shaped electrode 4 is attached to the bottom of the furnace by penetrating a furnace wall composed of the iron shell 3, the perm brick 1 and the amorphous refractory 2.

A sleeve 5 is inserted 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 concentrically embedding a plurality of thin tubes 6a inside the sleeve 5, as shown in FIG. Alternatively, the gas passage 6 may be bored in the brick itself forming the sleeve 5. A wind box 7 communicating with the gas passage 6 is provided at the lower end of the sleeve 5, and a gas pipe 8 is connected to the wind box 7.

The gas 9 sent from the gas pipe 8 removes the heat transferred from the rod-shaped electrode 4 to the sleeve 5 while passing through the gas passage 6, and then is blown into the furnace. Therefore, the tip portion of the rod-shaped electrode 4 and the sleeve 5 are cooled over the entire length, so that the furnace inner portion exposed to a particularly severe atmosphere can be protected.
In addition, by branching the gas pipe 8, gas is blown out between the sleeve 5 and the rod-shaped electrode 4 from a separately provided wind box 10,
It can also be 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 the conductive arm 12. In addition, a water cooling mechanism can be built into the rod-shaped electrode 4 to which the conductive arm 12 is connected, by supplying cooling water from the water supply pipe 13 to cool the connection portion and then draining the water through the drain pipe 14.

Further, in the example of FIG. 1, a push-up mechanism 15 is arranged at the rear end of the rod-shaped electrode 4 in order to move the rod-shaped electrode 4 forward in the furnace. The push-up mechanism 15 is attached to a support arm 16 fixed to the furnace wall, and its pressing surface faces the rear end of the rod-shaped electrode 4 via an insulator 17. When the tip portion of the rod-shaped electrode 4 is worn by the molten metal in the furnace and the length thereof becomes short, the pushing-up mechanism 15 is driven to drive the rod-shaped electrode 4
Is advanced toward the inside of the furnace, and the amount of wear is complemented by the amount of indentation.
As a result, the replacement frequency of 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 to cool it. That is, a plurality of injection nozzles 18 are arranged concentrically and in multiple stages on the peripheral surface of the rear end of the rod-shaped electrode 4 protruding from the furnace wall. Then, the cooling medium 20 supplied through the supply pipe 19 is sprayed from the injection nozzle 18 onto the peripheral surface of the rod-shaped electrode 4 to cool the rod-shaped electrode 4. When cooling water is used as the cooling medium 20 in this system, even if the water supply is stopped for some reason, there is no place where the cooling water accumulates around the rod electrode 4, so there is no danger of steam explosion or the like.

The periphery of the lower end of the rod-shaped electrode 4 is surrounded by a casing 21 to form a closed space so that the cooling medium 20 sprayed from the spray nozzle 18 does not scatter around. A discharge pipe 22 is opened on the bottom surface of the casing 21, and the cooling medium 20 jetted from the jet nozzle 18 is forcibly discharged by the discharge pump 23 through the discharge pipe 22.

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 the power supply cable 24. Further, an insulator 25 is provided in the outlet of the gas pipe 8 from the iron shell 3 and in the middle of the gas pipe 8 to prevent electric leakage through the gas pipe 8. This insulator 25
Although omitted in FIG. 1, it is actually provided in the same manner as in FIG. For the same purpose, the supply pipe 19
Also, the insulator 26 is interposed in the middle of the discharge pipe 22.

The gas 9 is sent to the wind box 7 from a gas supply source (not shown) through the gas pipe 8. In consideration of cooling the rod-shaped electrode 4 and the sleeve 5, it is preferable to use a low-temperature gas having an atmospheric temperature as the gas used at this time. The introduced gas 9 is once expanded in the wind box 7 and then sent into the gas passage 6. Therefore, the flow rate does not change between the gases 9 passing through the individual gas passages 6, and the gas 9 passes through the gas passages 6 with a uniform flow rate distribution over the entire circumference of the sleeve 5 and is fed into the furnace. .

The gas 5 flowing through the gas passage 6 cools the sleeve 5, and thus the tip of the rod-shaped electrode 4. That is, while conducting heat from the front end to the rear end as in the conventional case, the rod-shaped electrode 4
Since the rear end portion is not cooled, the entire rod-shaped electrode 4 is cooled uniformly regardless of the thermal conductivity of the rod-shaped electrode 4. Therefore, especially the tip portion of the rod-shaped electrode 4 which is severely melted by the molten metal can be maintained at a low temperature, and the durability is significantly improved. In addition to the cooling by the gas 9, when the cooling medium 20 is sprayed on the rear end of the rod-shaped electrode 4, the cooling action becomes more reliable.

The gas 9 blown into the furnace passes through a mushroom-shaped multi-layer metal structure having fine holes formed by gas cooling near the tip of the rod-shaped electrode 4, and then diffuses into the molten metal in the furnace. It is considered to be a thing. That is, the blowing of the gas 9 reduces the direct contact between the tip of the rod-shaped electrode 4 and the molten metal, or the static pressure of the molten metal applied to the tip of the rod-shaped electrode 4 and the sleeve 5, which is also reduced.
It is presumed that the life of the

〔The invention's effect〕

As described above, in the furnace wall electrode of the present invention,
Gas is sent into the furnace through the sleeve fitted in the rod electrode, and the gas cools the rod electrode and the sleeve. 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 significantly extended. In particular, melting damage of the sleeve or the tip of the rod-shaped electrode facing the inside of the furnace is suppressed, so that no corners are formed in the surrounding irregular-shaped refractory, and chipping of the corners is also eliminated. Further, since the blown gas has a function of stirring the material which is being melted or refined, the gas which has been melted or refined can be rapidly dissolved.

Also, for example, even when cooling water is used as the cooling medium, the electrode is efficiently cooled strongly and the life of the electrode is dramatically extended. In addition, since circulating water is not used and it is sprayed on the peripheral surface of the rear end of the rod-shaped electrode by spraying, no stagnation occurs at the periphery of the rod-shaped electrode, and there is no risk of steam explosion, etc. Is done. Further, when the rod-shaped electrode is advanced toward the inside of the furnace in accordance with the wear, the frequency of replacement of the rod-shaped electrode is greatly reduced, so that the operability is also improved.

[Brief description of drawings]

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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuki Makinosaku 59, Nakahara 46, Tobata-ku, Kitakyushu, Kitakyushu, Fukuoka 59 Machinery & Plant Division, Nippon Steel Corporation (72) Inventor Isao Arimitsu Kitakyushu, Fukuoka 59, Nippon Steel Co., Ltd., Machinery & Plant Business Department, 46 Nakahara, Tobata-ku, Tochiku-ku, Japan (72) Inventor, Katsuhiro Morio 59, 46, Nakahara, Tobata-ku, Kitakyushu, Kitakyushu, Japan 59, Machinery & Plant Business Department, Nippon Steel Co., Ltd. (72) Inventor Kiyosuke Mori 59, 46 Nakahara, Tobata-ku, Kitakyushu, Fukuoka 59 59 Nippon Steel Co., Ltd. Machinery & Plant Division

Claims (4)

[Claims] 1. A rod-shaped electrode having a tip portion penetrating the furnace wall and facing the inside of the furnace, a sleeve provided between the periphery of the rod-shaped electrode and the furnace wall, and a sleeve formed axially through the sleeve. And a gas pipe for blowing gas into the furnace through the gas passage, and a furnace wall electrode of a DC arc furnace. 2. A rod-shaped electrode having a tip portion penetrating the furnace wall and facing the inside of the furnace, and an injection nozzle for spraying a cooling medium to a rear end portion of the rod-shaped electrode protruding outside from the furnace wall. Characteristic wall electrode of DC arc furnace. 3. A rod-shaped electrode having a tip portion penetrating the furnace wall to face the inside of the furnace, a sleeve provided between the periphery of the rod-shaped electrode and the furnace wall, and the rod-shaped electrode protruding from the furnace wall to the outside. An injection nozzle for blowing a cooling medium to the rear end portion, a gas passage formed by axially penetrating the sleeve, and a gas pipe for blowing gas into the furnace via the gas passage. Characteristic wall electrode of DC arc furnace. 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 furnace.