JPS60177119A - Operating method of melting furnace for iron and steel - Google Patents

Abstract

PURPOSE:To operate melting with stable and high efficiency while eliminating the consumption at the side face of an electrode by inserting the electrode through the hole of a water cooling jacket in the operation in which the molten metal, under electromagnetic stirring, of the raw material for steel making formed with a shaft furnace and a blowing gas is further heated hermetically by an electrode arc. CONSTITUTION:The raw material for steel making entering a shaft furnace 1 through a raw material charging port 6 is melted 16 by a main combustion burner 14 and accumulates on a hearth 15 where the molten metal is fluidized by electromagnetic stirring 4. An electrode 3 is inserted through the hole of a water cooling jacket 19 in the hermetic part on the lateral side of the hearth and the molten metal is heated to a high temp. by the arc thereof. The side face of the electrode 3 is protected by the jacket 19 so as to have no consumption at the side face. Generation of a flicker is thus obviated, the need for a regulator is eliminated and the high-temp. heating is made highly efficient by the stable arc heating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a steel melting furnace that indirectly and continuously melts metal materials such as steel or parts by combining the characteristics of an arc furnace and a combustion furnace.

In general, an arc furnace that uses electric heat as a heat source uses an arc to blow an arc between the electrodes or between the electrodes and the object to be heated or steel parts, and uses the generated heat to heat the object directly or indirectly.
It performs melting and is not only easy to operate, but can also reach extremely high temperatures in a short period of time if necessary. In addition, in a combustion furnace using burner combustion, the initial temperature of the object to be heated or the steel parts is low, so the heat absorption or thermal efficiency during the heating process is good, and after the furnace top gas reaches a certain temperature, there is no heat exchange. It can be recovered and used as primary air for combustion burners.

Therefore, as a new and useful method for operating a steel melting furnace that combines the characteristics of high-temperature heating due to arc generation in an arc furnace and the characteristics of low-temperature heating due to burner combustion in a combustion furnace, the applicant has proposed a method for operating a steel melting furnace that uses a material charging port in the upper part. When melting raw material for steel making in the furnace body of an arc furnace, which is connected to the lower part of the combustion furnace shaft having 9 Next.

Arc discharge is performed between an electrode provided in the arc furnace and the raw material, the raw material is heated and melted in a high temperature zone, and the molten metal is stored in the hearth, and then the arc discharge is performed only on the molten metal, and Patent No. 1138086 (% Kosho 57-273 A3') is characterized in that the molten metal in the hearth is uniformly stirred and mixed by rotation of an induction stirrer using an electromagnet installed at the lower part of the hearth. In order to carry out this method, a steel melting furnace as shown in FIG. 1 was disclosed.

That is, in Figure 9, l is the shaft of the combustion furnace, 2 is the furnace body of the arc furnace formed integrally with the lower part of the shaft, 3 is the electrode that can be raised and lowered, 4 is the induction stirrer using an electromagnet, and 5 is the chimney. Each of them is to be shown.

A damper 8 and a heat exchanger 9 for passing the furnace top gas are provided at the raw material charging port 6 and the exhaust gas lower at the top of the shaft, and at the raw material charging port, a material hoisting machine or a supply conveyor 10 is provided. One end is faced, and the furnace top gas that has passed through the heat exchanger is sent into the chimney 5 by the blower 11 and discharged into the atmosphere. An auxiliary combustion burner 12 is installed below the shaft 1 to adjust the temperature difference when a glue phenomenon occurs during the melting process, and a top gas conduit 13 is installed on the outer peripheral side of the furnace body 2 of the arc furnace. A main combustion burner 14 is installed, which is connected to a heat exchanger 9 via a heat exchanger 9 .

However, in the original patent as mentioned above, the latter of the two types of electrode wear, i.e. tip wear due to sublimation due to the action of the arc and wear due to slag, and side oxidation wear due to long stays in the high-temperature furnace atmosphere. The disadvantage is that it consumes a lot of water.

In contrast, the present invention proposes a method for operating a steel melting furnace that can eliminate the above-mentioned drawbacks, and its gist is that the lower part of the combustion furnace shaft, which has the raw material charging port at the upper part, When melting steelmaking raw materials in the furnace body of an arc furnace.

The raw material is heated in a low temperature zone by a main combustion burner provided close to the outer periphery of the furnace body, and then arc discharge is performed between an electrode provided in the arc furnace and the raw material to heat the raw material in a high temperature zone. After heating and melting and storing the molten metal in the hearth,
Continuous melting is made possible by performing the arc discharge only on the molten metal and uniformly stirring and mixing the molten metal in the hearth by rotating an induction stirrer using an electromagnet installed at the bottom of the hearth. In this case, the electrode is provided with a water cooling jacket to reduce side oxidation wear.

Thus, according to the present invention, low temperature (0
~1loo0c) The heating in the zone is done by burner combustion, and the heating and melting in the high temperature (1100°C or higher) zone is done by arc generation, and the subsequent melting is always done with the molten metal stored in the hearth. In this case, the appropriate melting temperature can be maintained constant by blowing the arc only to the molten metal, so the arc is relatively stable, almost no regulator performance is required, and there is no flicker, making it possible to perform extremely high-quality work. Not only can it improve efficiency and is highly economical and capable of continuous operation, it is also excellent in terms of thermal efficiency and reduction of heat loss in the top gas by minimizing oxidation wear on the side of the electrode. It is something.

Next, the present invention will be explained in more detail with reference to an embodiment shown in FIGS. 2 and 3, in which the same parts as in FIG. 1 are denoted by the same reference numerals.

In Figure 2, there is a bushing 17 below the combustion furnace shaft 1 along the circumference of the shaft to prevent the phenomenon of glue amount.
is rotatably installed, and the furnace lid 18 of the arc furnace furnace body 2
A water-cooled jacket 19 is installed at the side surface of the electrode 3 to prevent oxidation and consumption. In this case, the water-cooled jacket is covered with a sleeve-shaped refractory 20 and the flange portion is covered with a sleeve-shaped refractory material 20, as shown in FIG. 21 is placed on a donut-shaped insulator 23 which is not installed on the water-cooled ceiling 22 above the furnace cover 18. When a phenomenon of glue amount occurs in the shaft, the Bousocharonde 24 is inserted to remove the object to be heated. It is something that destroys.

Therefore, in the steel melting furnace having the above-mentioned configuration, it takes nine steps to melt metal materials such as steel or parts to obtain the molten metal 16.
For example, scraps from machine tools, industrial machinery, logistics machinery, etc. are transported from a supply conveyor 10 (Fig. 1) at the top of the furnace body 2 connected to the furnace body 2 under control by a damper 8. . It is also possible to shorten the burner combustion time and form the molten metal 16 by blowing an arc between the electrode 3 and the steel scrap, which is equipped with a water-cooled jacket 19.

In any case, the molten metal 16 is stored at the bottom of the hearth. Subsequently, the main combustion burner 1 is used to maintain the temperature atmosphere inside the furnace body 2 at an appropriate melting temperature and preheat the steel scrap.
4, the furnace condition is stabilized by blowing an arc between the molten metal 16 stored in the hearth 15 and the electrode 3 attached with the water-cooled jacket 19, and at the same time melting the steel scrap with the molten metal. This process involves chemical processing and indirect continuous melting.

The molten metal 16 is uniformly stirred and mixed by rotation of the induction stirrer 4 using an electromagnet, which is installed close to the bottom of the furnace body 2, thereby increasing the melting speed (shortening the melting time).
Depending on the amount used, the slag is pumped from the tap to the slag car as appropriate, and the slag is pumped from the tap to the slag car and transported to the destination.

From the above, according to the present invention, in the melting process of metal materials such as steel or parts, the low-temperature heating zone is burner combustion, and the high-temperature (0) heat zone is due to the generation of arc, which makes it impossible to operate the furnace. Compared to the power consumption required for consistent arc generation as in the case of electric arc furnaces, most of the power consumption is replaced by burner combustion, so power consumption is also reduced, and in particular, melting is always performed using molten metal stored in the hearth. At the same time, since the arc only blows against the molten metal, it is possible to perform indirect continuous melting as a whole, without the need for a regulator (because the arc can be stabilized, no flickering occurs). It is possible to stabilize the furnace condition and carry out highly efficient furnace operation or melting work.

4. Additional related original patent No. 1138086 (Japanese Patent Publication No. 5'7-2738.
No. 3) includes a main combustion burner which is installed close to the outer periphery of the furnace body when melting steelmaking raw materials in the furnace body of the arc furnace, which is connected to the lower part of the combustion furnace shaft having a raw material charging port at the upper part. The raw material is heated in a low temperature zone, and then arc discharge is performed between an electrode provided in the arc furnace and the raw material to heat and melt the raw material in a high temperature zone, and the molten metal is stored in the hearth.

Continuous melting is possible by performing the arc discharge only on the molten metal and uniformly stirring and mixing the molten metal in the hearth by rotating an induction stirrer using an electromagnet installed at the bottom of the hearth. A method of operating a steel melting furnace is described.

However, in the original patent, there is a drawback that the lateral oxidation consumption of the electrode is large, whereas in the present invention, in order to minimize the lateral oxidation consumption, the intended purpose is achieved by attaching a water cooling jacket to the electrode. This has been improved so that it can be achieved.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing a steel melting furnace for implementing the original patent, Figure 2 is a similar front view of the furnace for implementing the method of the present invention, and Figure 3 is an enlarged detailed view of the vicinity of the electrodes. The correspondence between the main parts shown in the figure and the symbols is as follows: 1... Combustion furnace shaft, 2... Arc furnace furnace body, 3...
...Electrode, 4...Induction stirrer using electromagnet, 6...
Raw material charging port, 14... Main combustion burner, 15... Hearth, 16... Molten metal, 19... Water cooling jacket, 22...
・Water-cooled ceiling. Figure i Figure 2

Claims (1)

[Claims] (1) When melting the steelmaking raw material in the furnace body of an arc furnace, which is connected to the lower part of the combustion furnace shaft having the raw material charging port at the upper part, the main combustion burner, which is installed close to the outer periphery of the furnace body, The raw material is heated in a low-temperature zone, and then arc discharge is performed between an electrode provided in the arc furnace and the raw material to heat and melt the raw material in a high-temperature zone, and the molten metal is stored in the hearth. When electric discharge is performed only on the molten metal, continuous melting is possible by uniformly stirring and mixing the molten metal in the hearth with the rotation of an induction stirrer using an electromagnet installed at the bottom of the hearth. In this case, a method for operating a steel melting furnace, characterized in that side oxidation consumption is reduced by attaching a water cooling jacket to the electrode. (2. A method for operating a steel blast furnace according to claim (1), in which a water-cooled ceiling is attached to the upper surface of the furnace body to reduce side oxidation consumption of the electrodes.