JPS6345672Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is suitable for the operating conditions in an arc furnace for metal melting and refining, reduces the amount of heat removed from the furnace, and reduces the amount of dust collection air. The present invention relates to a dust collector for an arc furnace.

(Prior Art) A so-called indirect dust collection method has conventionally been adopted as a technology for collecting exhaust gas leaking from an annular gap between an electrode and an electrode penetration hole in a furnace lid of an arc furnace.

In this method, a dust collection hood is installed on the top of the furnace lid.
The gas ejected from around the three electrodes is collected outside the furnace.

On the other hand, there is a method in which an opening for exhaust gas is provided in the furnace lid and an exhaust gas pipe is connected to the hole to directly collect the powder smoke generated in the furnace, which is called a direct-drawing method.

The direct suction method has extremely excellent dust collection ability because it draws air directly from inside the furnace, and is therefore used in many factories. However, on the other hand, the amount of powder smoke generated from inside the furnace varies greatly depending on the melting process, so it is difficult to control, resulting in excessive dust collection, increasing heat removal from the furnace, and causing oxidation inside the furnace. During stainless steel melting and the reduction period, where the atmosphere is not favorable, the O ₂ concentration in the furnace becomes excessive, leading to losses of Cr, Ni, etc., and having a negative effect on reduction reactions such as desulfurization of molten steel.

On this point, the indirect dust collection hood method does not directly suck the powder smoke generated in the furnace from inside the furnace, but collects the dust after it is taken out of the furnace, so it has the advantage of making the atmosphere inside the furnace a reducing atmosphere. It also has the advantage that less heat is removed from the inside of the furnace. However, the pressure inside the electric furnace is positive, so when you open the various openings of the arc furnace, such as the work opening, auxiliary combustion burner opening, and auxiliary material input opening, the powder smoke inside the furnace blows out all at once, making it impossible to completely collect the dust. It was difficult to do so, and the structure was complicated because dust collection ducts were provided for each of these openings. In addition, the recent trend of oxygen injection operation, auxiliary combustion burner combination, carbon injection operation, etc. has been increasingly adopted, leading to an increase in the amount of dust generated, and indirect dust collection hood methods are difficult to adopt due to insufficient suction power In the indirect dust collection method, the gas ejected from inside the furnace is sucked together with the air sucked in from the outer periphery.
It also had the disadvantage that it was difficult to use for scrap preheating because the air volume was significantly large and the gas temperature after mixing was significantly lowered.

However, in recent years, with the rapid trend toward energy conservation, there has been a strong demand for improved thermal efficiency in arc furnaces, and detailed studies have been made on things such as sealing the furnace body. There is a strong desire to reduce this.

In addition, in the above-mentioned stainless steel melting and high-grade steel melting, keeping the inside of the furnace in a reducing atmosphere means that Cr,
It is highly desired to avoid oxidation loss of expensive metals such as Ni, and a dust collection method that has sufficient dust collection ability, removes less heat, and is easy to control the atmosphere inside the furnace is becoming desirable. .

(Problems to be Solved by the Invention) The present invention provides a dust collector for an arc furnace that does not have these drawbacks and can collect dust extremely elastically to suit each stage of melting. be.

(Means for solving the problem) The present invention focuses on the fact that the dust collection capacity is insufficient in indirect dust collection methods only at certain times, and has developed an arc furnace that is most suitable for power-saving operation of arc furnaces. This provides a dust collector for furnaces. That is, the gist of the present invention is to provide a dust collection hood having an electrode penetration hole above the furnace lid of an arc furnace for metal melting and refining,
In an indirect suction type dust collector in which the dust collection hood is equipped with a dust collection duct that communicates with the dust collection main pipe, an opening for direct suction is provided in the furnace lid, a direct dust collection pipe is connected to the opening, The dust collection device for an arc furnace is characterized in that the direct dust collection pipe is connected to the dust collection hood or the dust collection duct via a damper.

(Operation, Examples) Hereinafter, the operation of the present invention will be explained in detail based on the embodiments shown in the drawings.

FIGS. 1 and 2 show an embodiment of the present invention, in which a furnace lid 2 made of refractories, water-cooled panels, etc. is mounted on top of a furnace body 1 of an arc furnace.
There is an electrode opening 2a in the center of the furnace lid 2 through which the electrode 3 passes, and a dust collection hood 4 is provided above the opening 2a. A dust collection duct 5 for sucking exhaust gas is attached to the dust collection hood 4, and a dust collection main pipe 6 is provided opposite to the dust collection duct 5, and the dust collection main pipe 6 is connected to a blower 7. It passes through a dust collector 8 and is exhausted from a chimney 9.

On the other hand, another direct suction hole 2b is provided in the furnace lid 2, and a direct suction dust collection pipe 10 is connected to this direct suction hole 2b, and a dust collection duct is connected via a damper 11. It is connected to 5.

FIG. 1 shows that the various holes provided in the electric furnace, such as the working port 12, are not opened, and therefore the powder smoke in the furnace is mainly caused by the electrode hole 2a in the furnace lid and the electrode 3. This shows the stage where the water is being ejected from the annular gap 13.

On the other hand, FIG. 2 shows that the working port 12 is opened,
It shows a state in which oxygen injection, carbon injection, and combustion in the auxiliary combustion burner 14 are being performed, and in this case, the damper 11 is opened appropriately, indicating that indirect suction and direct suction are being performed at the same time. There is.

To explain the operation of an arc furnace step by step, during the initial ignition period and boring period, various holes in the furnace body 1 are closed as shown in Fig. 1, and oxygen injection and carbon injection are performed. , combustion in the auxiliary burner 14 is not performed.

In this case, the damper 11 is closed, and the dust generated from inside the furnace is mainly ejected from the annular gap 13 and collected through the dust collection hood 4 and the dust collection duct 5. Since the exhaust gas from inside the furnace is not sucked in more than necessary, operation with extremely low heat removal is possible.

Next, in the melting period, when the auxiliary combustion burner 14 is combusted, the damper 11 is opened in accordance with the increased amount of exhaust gas, resulting in the state shown in FIG. 2. When the combustion in the auxiliary burner 14 is completed, the melting process returns to the state shown in FIG. 1 again and continues melting. Next, when oxygen is blown in by the lance 15, the state shown in FIG. 2 is again achieved, the damper 11 is opened to the required degree, and direct suction is performed in parallel.

When the melting is completed, the temperature is raised and refining is carried out, but only when openings such as the working port 12 are opened, or when oxygen and carbon are injected, the state shown in Fig. 2 is reached; It is operated to return to the state shown in FIG.

In the structure shown in FIGS. 1 and 2, the direct dust collection pipe 10 is connected to the dust collection duct 5, but the same purpose can be achieved by connecting it to the dust collection hood 4, and the operation can be done similarly.

In addition, when the gas in the dust collection hood 4 is sucked, not only the powder smoke from the annular gap 13 between the electrode 3 and the electrode hole 2a is sucked, but also the gas inside the electrode penetration hole between the electrode 2 and the dust collection hood 4 is sucked. Atmospheric air is sucked through the annular gap 16 between the hole 4a and the lower end of the dust collection hood 4 and the furnace cover 2.
Atmospheric air is also sucked in from the gap 17 between the top surface and the top surface. In this case, especially if the amount of air suctioned from the gap 17 is too large, a curtain 18 can be provided to prevent the temperature of the suction gas from decreasing and to avoid increasing the amount of suction air unnecessarily. This makes it possible to maintain the dust collection exhaust gas in a scrap preheating device, etc., making it possible to further recover exhaust heat.

(Effects of the invention) This invention solves the lack of dust collection power, which was a drawback of the conventional indirect dust collection method, and also prevents the ejection of powder smoke when various holes are opened. I can do it. Particularly in the case of melted stainless steel, it is important to prevent the oxidation of expensive metals such as Cr and Ni from the viewpoint of operating costs, but with this invention, it is easy to maintain a reducing atmosphere inside the furnace, which makes the operation of the furnace easier. The direct suction method can be used only at the necessary stages, making it possible to achieve extremely rational dust collection in the arc furnace.

[Brief explanation of the drawing]

Fig. 1 and Fig. 2 are diagrams showing an embodiment of the present invention, Fig. 1 shows a state in which indirect suction is performed with the damper closed, and Fig. 2 shows a state in which indirect suction and direct suction are performed with the damper open. This shows a state in which suction and suction are being performed at the same time. DESCRIPTION OF SYMBOLS 1...Furnace body, 2...Furnace cover, 2a...Aperture for electrode, 2b...Aperture for direct suction, 3...Electrode, 4...
...Dust collection hood, 4a...Aperture for electrode penetration, 5...
Dust collection duct, 6... Dust collection main pipe, 7... Blower,
8... Dust collector, 9... Chimney, 10... Direct dust collection pipe, 11... Damper, 12... Work opening, 13
...Annular gap, 14...Auxiliary burner, 15...Lance, 16...Annular gap, 17...Gap, 18...
…curtain.

Claims (1)

[Scope of utility model registration request] In an indirect suction type dust collector in which a dust collection hood with an electrode penetration hole is provided above the furnace lid of an arc furnace for metal melting and refining, and a dust collection duct that communicates with a dust collection main pipe is attached to the dust collection hood. , a direct suction hole is provided in the furnace lid, a direct suction dust collection pipe is connected to the hole, and the direct suction dust collection pipe is connected to the dust collection hood or the dust collection duct via a damper. Characteristic dust collector for arc furnaces.