WO2023210904A1

WO2023210904A1 - Powder spraying system and electric furnace including same

Info

Publication number: WO2023210904A1
Application number: PCT/KR2022/018981
Authority: WO
Inventors: 송우석; 김균태; 박영주; 신대훈; 신명철; 엄준용; 이재랑; 이재민; 조종오
Original assignee: 현대제철 주식회사
Priority date: 2022-04-29
Filing date: 2022-11-28
Publication date: 2023-11-02
Also published as: KR20230153751A

Abstract

The present invention relates to a powder spraying system capable of foaming slag during an electric furnace operation, and an electric furnace including same. The present invention may include: a powdered carbon spray nozzle which has a pipe shape open at both ends and sprays a transport fluid containing powdered carbon into the inner space of a main body of the electric furnace through a first spray flow path formed therein; and a film cooling fluid nozzle which is formed in a pipe shape, closed toward an end part through which the transport fluid is sprayed, so as to surround the powdered carbon spray nozzle, and sprays a flowing film cooling fluid toward the first spray flow path through a second spray flow path formed so as to have an annular cross-section therein.

Description

Powder injection system and electric furnace including the same

The present invention relates to a powder injection system and an electric furnace including the same, and more specifically, to a powder injection system capable of foaming slag during electric furnace operation and an electric furnace including the same.

An electric furnace refers to a furnace that heats and melts metals or alloys using electrical energy. It is a device that melts scrap by charging scrap into the furnace and then generating arc-shaped current between the electrode and the scrap to heat it. During the steelmaking process using an electric furnace, impurities in the scrap are dissolved and slag is formed on the top of the molten steel in the form of oxides. This slag floats on the surface of the molten steel, prevents the surface of the molten steel from being oxidized by air, and can play a role in preserving the surface.

At this time, in electric furnace operation, the slag layer thickness is kept large by forming the slag, thereby protecting the arc generated from the electrode from being exposed to the atmosphere, improving the heat transfer efficiency of the arc to the molten steel, and also preventing the intake of nitrogen from the atmosphere. It can be prevented.

In general, slag forming technology can be used to form slag by blowing powdered carbon and oxygen from the wall of the electric furnace body into the slag and molten steel in the inner space of the electric furnace body during operation of the electric furnace and generating CO gas. there is. In this way, the formed slag can reduce the heat dissipation of the arc by immersing the arc electrode into the molten steel and slag, and improve the power source unit of the electric furnace by suppressing the heat dissipation of the molten steel.

However, in the conventional powder injection system for slag forming, powder carbon is blown in through a tube-shaped pipe, and supersonic oxygen is blown in from a double pipe formed to surround the pipe and having a circular cross-section, and the inside of the pipe is blown in. There was a problem in that erosion occurred on the inner wall of the pipe due to powder carbon colliding with the inner wall during the flow. As such, damage to the nozzle that sprays powdered carbon frequently occurs due to erosion of the inner wall of the pipe, resulting in a shortened replacement cycle due to a decrease in the lifespan of the nozzle.

The present invention is intended to solve various problems including the problems described above, by forming a structure that prevents the powder carbon flowing inside the pipe-shaped powder carbon injection nozzle by the transport fluid from colliding with the inner wall, The purpose is to provide a powder injection system that can solve the above-mentioned problems and an electric furnace including the same. However, these tasks are illustrative and do not limit the scope of the present invention.

According to one embodiment of the present invention, a powder injection system is provided. The powder injection system is inserted into one side of the electric furnace main body where an internal space capable of producing molten steel is formed by melting the iron source, and blows powdered carbon into the slag and the molten steel in the internal space during operation to form the slag. In a powder injection system capable of promoting powder carbon, the powder carbon is formed in the shape of a pipe with both ends open, and sprays a transport fluid containing the powder carbon into the internal space of the electric furnace main body through a first injection passage inside. spray nozzle; And a film cooling fluid flowing through a second injection passage formed in the shape of a pipe with a closed end side through which the transfer fluid is sprayed to surround the powder carbon injection nozzle and having a circular cross-section on the inside. It may include a film cooling fluid nozzle that sprays toward the first injection passage.

According to one embodiment of the present invention, the powder carbon injection nozzle has an outer wall surface of the powder carbon injection nozzle so as to connect the first injection passage inside and the second injection passage of the film cooling fluid nozzle. A plurality of protective hole portions may be formed to penetrate between inner wall surfaces.

According to one embodiment of the present invention, the plurality of protection holes are configured to prevent the powder carbon passing through the first injection passage of the powder carbon injection nozzle by the transport fluid from colliding with the inner wall surface of the powder carbon injection nozzle. In order to prevent this, a plurality of powder carbon injection nozzles are formed at equal intervals along the circumferential direction and the longitudinal direction of the inner wall surface of the powder carbon injection nozzle, and are directed from the inner wall surface toward the central axis of the first injection passage. The membrane cooling fluid may be sprayed.

According to one embodiment of the present invention, the plurality of protection hole portions are configured such that the transfer fluid flowing through the first injection passage of the powder carbon injection nozzle increases from the outer wall surface of the powder carbon injection nozzle to the inner wall surface. It may be formed to be inclined toward the flow direction.

According to one embodiment of the present invention, the supersonic fluid is formed in the shape of a pipe open at both ends to surround the membrane cooling fluid nozzle, and is formed to have a circular cross-section on the inside, thereby sending supersonic fluid to the electric furnace main body. It may further include a supersonic fluid nozzle spraying into the internal space of the.

According to one embodiment of the present invention, the supersonic fluid nozzle may be formed as a Laval nozzle to increase the flow speed of the supersonic fluid passing through the third injection passage to more than the speed of sound.

According to one embodiment of the present invention, the supersonic fluid nozzle is formed so that its cross-sectional area gradually decreases along the flow direction of the supersonic fluid from the inlet into which the supersonic fluid flows, so that the supersonic fluid flowing therein is A compression unit that compresses; a neck portion formed with a minimum cross-sectional area to maximize compression of the supersonic fluid compressed in the process of flowing the compression portion; and an expansion part that is formed to gradually increase its cross-sectional area along the flow direction of the supersonic fluid from the neck to the injection part where the supersonic fluid is sprayed, and expands the supersonic fluid flowing therein.

According to one embodiment of the present invention, the compression section and the expansion section are formed along the central axis of the third injection passage so that the cross-sectional area of the annular cross-section changes to gradually become smaller or larger in a non-linear manner, thereby forming an overall streamlined shape. It may be formed by a combination of at least two or more curves, including a convex curve formed in a convex curve shape based on a reference and a concave curve formed in a concave curve shape based on the central axis of the third injection passage.

According to another embodiment of the present invention, an electric furnace is provided. The electric furnace includes an electric furnace main body in which an internal space is formed into which an iron source can be charged and dissolved; an electrode that is at least partially inserted into the interior space through the small ceiling of the loop portion on the upper side of the electric furnace main body to melt the iron source by arc heat so as to produce molten steel; and a powder injection system inserted into one side of the electric furnace main body, capable of promoting foaming of the slag by blowing powder carbon into the slag and the molten steel in the internal space during operation, wherein the powder injection system includes, a powder carbon injection nozzle that is formed in the shape of a pipe with both ends open, and sprays the transfer fluid containing the powder carbon into the internal space of the electric furnace body through a first injection passage therein; And a film cooling fluid flowing through a second injection passage formed in the shape of a pipe with a closed end side through which the transfer fluid is sprayed to surround the powder carbon injection nozzle and having a circular cross-section on the inside. It may include a film cooling fluid nozzle that sprays toward the first injection passage.

According to another embodiment of the present invention, the powder injection system is formed in the shape of a pipe with both ends open to surround the membrane cooling fluid nozzle, and is provided with a supersonic speed through a third injection passage formed to have an annular cross section inside. It may further include a supersonic fluid nozzle that sprays fluid into the internal space of the electric furnace main body.

According to another embodiment of the present invention, the electric furnace main body includes a lower cell forming a lower side of the internal space; and an upper cell that is combined with the lower cell to form an upper side of the interior space and whose upper side is closed by the loop portion.

According to another embodiment of the present invention, the powder injection system may be formed to penetrate the wall of the upper cell or the lower cell.

According to another embodiment of the present invention, the powder injection system may be formed to be inclined downward at a predetermined angle toward the lower side of the electric furnace main body.

According to one embodiment of the present invention made as described above, the film cooling fluid flows through a film cooling fluid nozzle formed to surround the powder carbon injection nozzle that sprays the transport fluid containing powder carbon into the internal space of the electric furnace main body. Then, the flowing film cooling fluid is sprayed as a high-speed jet through the inner wall of the powder carbon injection nozzle to form a cooling protective film on the inner wall, so that the powder carbon flowing inside the powder carbon injection nozzle by the transport fluid is sprayed onto the inner wall. By preventing collision with the inner wall, erosion of the inner wall is prevented, damage to the nozzle is prevented, and the replacement cycle and lifespan of the nozzle can be increased.

In addition, in the process where the film cooling fluid injected into the plurality of protective holes on the inner wall of the powder carbon injection nozzle pushes the powder carbon toward the center of the powder carbon injection nozzle, the carbon powder is formed by the momentum of the film cooling fluid injected from the inner wall. As acceleration occurs, the injection speed of the powder carbon injected into the injection nozzle can be increased, thereby smoothly inducing slag forming.

In addition, by using a streamlined shrouded annular supersonic fluid nozzle with a supersonic characteristic curve applied, supersonic fluid with high straightness and momentum is injected, so that the powder carbon blown in through the powder carbon injection nozzle formed in the center is mixed with the supersonic jet stream. It is possible to implement a powder injection system and an electric furnace including the same that can facilitate the forming of the slag by easily guiding the upper part of the molten steel to approach the upper surface of the slag without being disturbed by the surrounding environment. Of course, the scope of the present invention is not limited by this effect.

1 is a cross-sectional view schematically showing an electric furnace according to an embodiment of the present invention.

Figures 2 and 3 are perspective and cross-sectional views schematically showing the powder injection system installed in the electric furnace of Figure 1.

Figure 4 is an enlarged view showing part “A” of Figure 3.

Hereinafter, various preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the following examples may be modified into various other forms, and the scope of the present invention is as follows. It is not limited to examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete and to fully convey the spirit of the present invention to those skilled in the art. Additionally, the thickness and size of each layer in the drawings are exaggerated for convenience and clarity of explanation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described with reference to drawings that schematically show ideal embodiments of the present invention. In the drawings, variations of the depicted shape may be expected, for example, depending on manufacturing technology and/or tolerances. Accordingly, embodiments of the present invention should not be construed as being limited to the specific shape of the area shown in this specification, but should include, for example, changes in shape resulting from manufacturing.

Figure 1 is a cross-sectional view schematically showing an electric furnace 1000 according to an embodiment of the present invention, and Figures 2 and 3 are perspective views schematically showing the powder injection system 100 installed in the electric furnace 1000 of Figure 1. and a cross-sectional view, and FIG. 4 is an enlarged view showing part “A” of FIG. 3.

First, as shown in FIG. 1, the electric furnace 1000 according to an embodiment of the present invention largely includes a powder injection system 100, an electric furnace main body 200, and an electrode 300. You can.

As shown in FIG. 1, the electric furnace main body 200 may be a type of furnace in which an internal space is formed in which an iron source such as scrap or directly reduced iron can be charged and dissolved.

For example, the electric furnace main body 200 is coupled to the lower cell 210 and the upper side of the lower cell 210 forming the lower side of the inner space, forming the upper side of the inner space, and the upper side is closed by the loop portion 230. It may be composed of an upper cell 220. At this time, although not shown, a fire-resistant wall constructed with fire-resistant glazing is formed on the inner wall of the lower cell 210 to protect the outer wall, and cooling water is circulated inside the inner wall of the upper cell 220 to protect the outer wall. Panel members may be mounted. In addition, although not shown, a raw material supply port for continuously supplying the iron source is formed on one side of the electric furnace main body 200, and a molten steel tapping port for continuously tapping the produced molten steel 1 is formed on the other side. You can.

In addition, the upper cell 220 may have a slag discharge door 221 formed at the lower end adjacent to the lower cell 210 to selectively allow the slag 2 formed on the upper side of the molten steel 1 to flow.

The loop portion 230 is seated on the top of the upper cell 220 and covers the open upper part of the upper cell 220, and a small ceiling is formed in the center to form an electrode 300 to be described later that generates arc heat. Can be installed penetratingly. Additionally, although not shown, the loop portion 230 may be connected to an exhaust pipe that discharges a large amount of waste gas and dust generated during the dissolution process of the iron source.

As shown in FIG. 1, the electrode 300 is formed of a plurality of electrode bundles, and at least a portion is inserted into the internal space through the small ceiling of the loop portion 230 on the upper side of the electric furnace main body 200. , the iron source can be melted by arc heat to produce molten steel (1).

As shown in FIG. 1, the powder injection system 100 is inserted into one side of the electric furnace main body 200, and powder carbon (C) and By blowing in oxygen, the forming of the slag 2 can be promoted.

For example, the powder injection system 100 is formed to penetrate the wall of the upper cell 220 and is inclined downward at a predetermined angle toward the lower side of the electric furnace main body 200, so that the electric furnace main body 200 during operation. Powdered carbon and oxygen are blown into the molten steel 1 and slag 2 in the internal space to generate CO gas, thereby forming the slag 2.

Here, the powder injection system 100 is formed to penetrate the wall of the upper cell 220 as an example, but it is not necessarily limited to FIG. 1 and may be formed to penetrate the wall of the lower cell 210. Additionally, a plurality of powder injection systems 100 may be installed as needed during the process.

To describe the powder injection system 100 in more detail, as shown in FIGS. 2 and 3, the powder injection system 100 injects the molten steel 1 in the internal space of the electric furnace main body 200. It is a type of nozzle structure that can inject powdery carbon (C) and oxygen into the slag (2) as a supersonic fluid (F3), and is largely comprised of a powdery carbon injection nozzle 110, a film cooling fluid nozzle 120, and a supersonic fluid nozzle 110. It may include a fluid nozzle 130.

As shown in FIGS. 2 and 3, the powder carbon injection nozzle 110 is formed in the shape of a pipe with both ends open, and transfers the transfer fluid (F1) containing powder carbon (C) through the first injection passage therein. ) can be sprayed into the internal space of the electric furnace main body 200.

In addition, the film cooling fluid nozzle 120 is formed in the shape of a pipe with an end side closed at which the transport fluid F1 is sprayed so as to surround the powder carbon injection nozzle 110, and has a circular cross-section on the inside. The film cooling fluid F2 flowing through the formed second injection passage may be injected toward the first injection passage of the powder carbon injection nozzle 110.

For example, the powdery carbon injection nozzle 110 has an outer wall surface and an inner wall surface of the powdery carbon injection nozzle 110 so as to connect the internal first injection passageway and the second injection passageway of the film cooling fluid nozzle 120. A plurality of protective hole portions 111 may be formed to pass through the space.

More specifically, the plurality of protection hole portions 111 are formed at equal intervals along the circumferential direction and the longitudinal direction of the inner wall surface of the powder carbon injection nozzle 111, and are formed at equal intervals from the inner wall surface. The film cooling fluid (F2) may be injected toward the central axis of the first injection passage.

Accordingly, as shown in FIG. 4, the film cooling fluid F2 flowing through the second injection passage of the film cooling fluid nozzle 120 flows through the plurality of protection hole portions 111 to the powder carbon injection nozzle ( It is sprayed as a high-speed jet onto the inner wall of the powder carbon injection nozzle 110, thereby forming a cooling protective film along the inner wall of the powder carbon injection nozzle 110, so that the first injection passage of the powder carbon injection nozzle 110 is supplied with a transport fluid ( It is possible to prevent the body carbon (C) passing through F1) from colliding with the inner wall surface of the powder carbon injection nozzle 110. At this time, the cooling protective film may also serve to cool the powder injection system 100 including the powder carbon injection nozzle 110 to prevent it from overheating.

In addition, the plurality of protection hole portions 111 provide transport fluid F1 flowing through the first injection passage of the powder carbon injection nozzle 110 as it moves from the outer wall surface of the powder carbon injection nozzle 110 to the inner wall surface. It may be formed inclined toward the direction of flow.

Accordingly, as shown in FIG. 4, the film cooling fluid is injected from the inner wall surface of the powder carbon injection nozzle 110 into a plurality of protection hole portions 111 formed inclined toward the flow direction of the transfer fluid F1. In the process of (F2) pushing the powder carbon (C) in an inclined direction toward the center of the powder carbon injection nozzle 110, the speed of the carbon powder (C) is further increased by the moment of the film cooling fluid (F2). It can be accelerated.

In addition, as shown in FIGS. 2 and 3, the supersonic fluid nozzle 130 is formed in the shape of a pipe with both ends open to surround the membrane cooling fluid nozzle 120, and is formed to have a circular cross-section on the inside. Supersonic fluid F3 (oxygen) can be injected into the internal space of the electric furnace main body 200 at a Mach number of 1.0 or more through the third injection passage.

This supersonic fluid nozzle 130 is formed as a Laval nozzle to increase the flow speed of the supersonic fluid (F3) passing through the third injection passage to more than the speed of sound, thereby generating the supersonic fluid (F3) by the shroud effect. ) can further accelerate the flow speed beyond the speed of sound.

For example, the supersonic fluid nozzle 130 is formed so that its cross-sectional area gradually decreases along the flow direction of the supersonic fluid F3 from the inlet into which the supersonic fluid F3 flows so that it can be formed as the Laval nozzle, A compression part 131 that compresses the supersonic fluid (F3) flowing inside, and a minimum cross-sectional area are formed to maximize the compression of the supersonic fluid (F3) compressed in the process of flowing through the compression part 131. The cross-sectional area is formed to gradually increase along the flow direction of the supersonic fluid F3 from the neck portion 132 to the injection portion where the supersonic fluid F3 is sprayed, and the supersonic fluid F3 flowing inside ) may be configured to include an expansion portion 133 that expands.

At this time, the compression portion 131 and the expansion portion 133 of the supersonic fluid nozzle 130 change the cross-sectional area of the annular cross-section to gradually become smaller or larger in a non-linear manner, so that the third injection can be formed into an overall streamlined shape. It may be desirable to form a combination of at least two or more curves, including a convex curve formed in a convex curve shape based on the central axis of the flow path and a concave curve formed in a concave curve shape based on the central axis of the third injection flow path. there is.

For example, when each point of the compression part 131, the neck part 132, and the expansion part 133 of the supersonic fluid nozzle 130 are linearly connected to form a straight line, the inner wall angle at which the inclination changes rapidly inside the nozzle This is formed, and a shock wave is generated during the compression/expansion flow of the supersonic fluid (F3). As a result, the shock wave causes the flow of the supersonic fluid (F3) to become unstable, adversely affecting the flow, and ultimately, the supersonic fluid nozzle ( A problem may occur in which the supersonic fluid (F3) injected through 130) is not sufficiently accelerated and straightness and momentum are deteriorated.

However, as in the present invention, when the supersonic fluid nozzle 130 is formed in a streamlined shape with a combination of a convex curve and a concave curve, the generation of the shock wave due to the inner wall angle is suppressed and the supersonic fluid nozzle 130 is formed according to the principle of supersonic gas flow. By inducing the fluid F3 to accelerate stably, the straightness and momentum of the supersonic fluid F3 sprayed at a supersonic speed of Mach 1.0 or higher through the supersonic fluid nozzle 130 can be improved.

Therefore, according to the powder injection system 100 and the electric furnace 1000 including the same according to various embodiments of the present invention, the transport fluid F1 containing powder carbon (C) is injected into the electric furnace main body 200. The film cooling fluid (F2) flows through the film cooling fluid nozzle 120 formed to surround the powdery carbon injection nozzle 110 spraying into the internal space, and the flowed film cooling fluid (F2) is injected into the powdery carbon injection nozzle 110. ) is sprayed with a high-speed jet through a plurality of protective hole portions 111 formed on the inner wall of the inner wall to form a cooling protective film on the inner wall, thereby allowing the powder carbon injection nozzle 110 to flow inside the roll by the transport fluid F1. By preventing the powder carbon (C) from colliding with the inner wall surface, erosion of the inner wall surface is prevented, damage to the nozzle is prevented, and the replacement cycle and lifespan of the nozzle can be increased.

In addition, the process in which the film cooling fluid (F2) injected into the plurality of protective hole portions 111 on the inner wall of the powdery carbon injection nozzle 110 pushes the powdery carbon (C) to the center of the powdery carbon injection nozzle 110. In this case, acceleration of the carbon powder (C) occurs due to the momentum of the film cooling fluid (F2) injected from the inner wall surface, thereby increasing the injection speed of the powdered carbon (C) injected into the injection hole, thereby increasing the injection speed of the slag (2). Foaming can be induced smoothly.

In addition, by using a streamlined shroud annular supersonic fluid nozzle 130 to which a supersonic characteristic curve is applied, supersonic fluid (F3) with high straightness and momentum is injected through the powder carbon injection nozzle 110 formed in the center. The powdered carbon (C) is mixed with the supersonic jet stream and is easily guided to the top of the molten steel (1) without being disturbed by the surrounding environment, and approaches the upper surface of the slag (2), making the forming of the slag (2) more smooth. It can have the effect of doing so.

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the attached patent claims.

Claims

Powder injection is inserted into one side of the electric furnace main body in which an internal space for producing molten steel is formed by dissolving the iron source, and can promote forming of the slag by blowing powdered carbon into the slag and the molten steel in the internal space during operation. In the system,

a powder carbon injection nozzle that is formed in the shape of a pipe with both ends open, and sprays the transfer fluid containing the powder carbon into the internal space of the electric furnace body through a first injection passage therein; and

The film cooling fluid flowing through a second injection passage is formed in the shape of a pipe with a closed end at an end side through which the transfer fluid is sprayed to surround the powder carbon injection nozzle, and is formed to have a circular cross-section on the inside. a film cooling fluid nozzle that sprays toward the first injection passage;

Including, powder injection system.
According to claim 1,

The powder carbon injection nozzle is,

A plurality of protection holes are formed to penetrate between the outer wall surface and the inner wall surface of the powder carbon injection nozzle so as to connect the first injection flow path inside and the second injection flow path of the film cooling fluid nozzle, Powder injection system.
According to claim 2,

The plurality of protective holes,

The inner wall surface of the powder carbon injection nozzle to prevent the powder carbon passing through the first injection passage of the powder carbon injection nozzle by the transfer fluid from colliding with the inner wall surface of the powder carbon injection nozzle. A powder injection system is formed at equal intervals along the circumferential direction and the longitudinal direction of the inner wall surface, and sprays the film cooling fluid from the inner wall surface toward the central axis of the first injection passage.
According to claim 3,

The plurality of protective holes,

The powder injection system is formed to be inclined toward the flow direction of the transfer fluid flowing through the first injection passage of the powder carbon injection nozzle as it goes from the outer wall surface of the powder carbon injection nozzle to the inner wall surface.
According to claim 1,

A supersonic fluid that is formed in the shape of a pipe with both ends open to surround the membrane cooling fluid nozzle, and injects the supersonic fluid into the internal space of the electric furnace body through a third injection passage formed to have an annular cross section on the inside. Nozzle;

A powder injection system further comprising:
According to claim 5,

The supersonic fluid nozzle is,

A powder injection system formed with a Laval nozzle to increase the flow speed of the supersonic fluid passing through the third injection passage to more than the speed of sound.
According to claim 6,

The supersonic fluid nozzle is,

A compression portion formed from an inlet into which the supersonic fluid flows so that its cross-sectional area gradually decreases along the flow direction of the supersonic fluid, and compresses the supersonic fluid flowing therein;

a neck portion formed with a minimum cross-sectional area to maximize compression of the supersonic fluid compressed in the process of flowing the compression portion; and

An expansion part formed so that its cross-sectional area gradually increases along the flow direction of the supersonic fluid from the neck to the injection part where the supersonic fluid is sprayed, and expands the supersonic fluid flowing therein;

Including, powder injection system.
According to claim 7,

The compression portion and the expansion portion,

A convex curve formed in a convex curve shape with respect to the central axis of the third injection passage so that the cross-sectional area of the annular cross-section can be non-linearly changed to gradually become smaller or larger to form an overall streamlined shape, and the center of the third injection passage. A powder injection system formed by a combination of at least two curves including a concave curve formed in a concave curve shape with respect to an axis.
An electric furnace main body in which an internal space is formed into which the iron source can be charged and dissolved;

an electrode that is at least partially inserted into the interior space through the small ceiling of the loop portion on the upper side of the electric furnace main body to melt the iron source by arc heat so as to produce molten steel; and

A powder injection system is inserted into one side of the electric furnace main body and is capable of promoting foaming of the slag by blowing powder carbon into the slag and the molten steel in the internal space during operation,

The powder injection system is,

a powder carbon injection nozzle formed in a pipe shape with both ends open, and spraying a transport fluid containing the powder carbon into the internal space of the electric furnace main body through a first injection passage therein; and

The film cooling fluid flowing through a second injection passage is formed in the shape of a pipe with a closed end at an end side through which the transfer fluid is sprayed to surround the powder carbon injection nozzle, and is formed to have a circular cross-section on the inside. a film cooling fluid nozzle that sprays toward the first injection passage;

Including, electric furnace.
According to clause 9,

The powder injection system is,

A supersonic fluid that is formed in the shape of a pipe open at both ends to surround the membrane cooling fluid nozzle and injects the supersonic fluid into the internal space of the electric furnace body through a third injection passage formed to have a circular cross-section on the inside. Nozzle;

Further comprising, an electric furnace.
According to clause 9,

The electric furnace main body,

a lower cell forming the lower side of the interior space; and

an upper cell that is coupled to the lower cell to form an upper side of the interior space and whose upper side is closed by the loop portion;

Including, electric furnace.
According to claim 11,

The powder injection system is,

An electric furnace formed to penetrate the wall of the upper cell or the lower cell.
According to claim 12,

The powder injection system is,

An electric furnace formed to be inclined downward at a predetermined angle toward the lower side of the electric furnace main body.