KR101712160B1 - Electric furnaces and method for preheating scrap in electric furnaces - Google Patents

Abstract

The present invention provides a scrap preheating apparatus. The scrap preheater of the present invention includes a preheating chamber having a plurality of preheating zones for storing scrap and for preheating scrap by hot exhaust gas discharged from the furnace body; And a moving unit installed in the preheating chamber and moving the scrap so that the scrap is sequentially moved along the plurality of preheating zones.

Description

ELECTRIC FURNACES AND METHOD FOR PREHEATING SCRAP IN ELECTRIC FURNACES FIELD OF THE INVENTION [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric arc furnace, and more particularly to an electric furnace for reusing hot exhaust gas discharged from a furnace body for scrap preheating and a scrap preheating method for an electric furnace.

The steelmaking process includes blast furnace steelmaking, which uses iron ore as a raw material, and electric arc furnace steelmaking, which recycles iron scrap as a raw material. The energy consumption of the electric arc furnace is 40% compared with the blast furnace and the carbon dioxide emission is 30%. In other words, the electric arc furnace has advantages such as simple steelmaking process, total energy (electricity + fuel) consumption and carbon emission, because it has no coke process and sintering process compared to blast furnace, Consuming a huge amount of power.

In such an electric furnace, a technique for preheating scrap used for electric furnace operation using waste heat of flue gas has been developed. However, in the case of existing preheating apparatus, since the residence time of scrap is short, it is not possible to efficiently perform preheating or to increase the residence time The size of the facility is increased and the installation cost is excessively generated.

In addition, existing preheating devices have problems such as leakage of exhaust gas or introduction of outside air into the melting furnace / preheating device.

An object of the present invention is to provide an electric furnace capable of maximizing the utilization of exhaust gas sensible heat and a scrap preheating method of an electric furnace.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electric furnace capable of preventing exhaust gas from flowing out to the outside during scrap charging and a scrap preheating method for an electric furnace.

It is an object of the present invention to provide an electric furnace capable of continuous residence time of continuous scrap and continuous preheating, and a scrap preheating method of electric furnace.

The problems to be solved by the present invention are not limited thereto, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a preheating chamber having a plurality of preheating zones in which scrap is stored and scrap is preheated by hot exhaust gas discharged from the furnace body; And a moving unit installed in the preheating chamber and moving the scrap so that the scrap is sequentially moved along the plurality of preheating zones.

In addition, the preheating chamber may provide a gas movement path such that the exhaust gas is sequentially passed through the plurality of preheat zones and the scrap stored in each preheat zone is preheated.

In addition, the plurality of preheating zones may be connected to an inlet formed on the upper surface of the preheating chamber. A discharge preheating zone connected to a discharge port formed on a bottom surface of the preheating chamber; And an intermediate preheating zone disposed between the input preheating zone and the exhaust preheating zone.

In addition, the mobile unit may include a rotating shaft installed vertically in the center of the preheating chamber; And partition plates disposed radially about the rotation axis, wherein the plurality of preheat zones may be provided by the partition plates.

Further, the partition plates may further include a gas flow passage through which exhaust gas passes; The gas flow passages of neighboring partition plates may have different heights so that exhaust gases pass zigzag through the plurality of preheat zones.

Further, the partition plate may include a gas flow passage through which hot exhaust gas passes.

Further, the gas flow passages may be provided at the upper end and the lower end of the partition plate, respectively.

Further, the partition plate may further include a gate valve for opening and closing the gas flow passage.

In addition, the scrap preheater further includes a duct portion through which the exhaust gas flowing into the preheating chamber escapes; Wherein the duct portion includes a first exhaust duct through which exhaust gas flowing into the input preheating zone escapes; A second exhaust duct through which the exhaust gas flowing into the intermediate preheating zone adjacent to the input preheating zone escapes; And a main duct connected to the first exhaust duct and the second exhaust duct.

The duct unit may include a first opening / closing valve installed in the first exhaust duct; And a second on-off valve installed in the second exhaust duct; The exhaust gas may be exhausted through the second exhaust duct when the scrap is introduced into the input preheating zone.

The scrap preheater may further include an auxiliary burner installed in the preheating chamber.

According to an aspect of the present invention, there is provided a furnace comprising: a furnace body having a cylindrical container for accommodating scrap to be melted and a container cover covering the top of the container; And a plurality of preheating units installed in the upper portion of the furnace body for storing scrap to be supplied to the furnace body and for preheating scrap before the hot exhaust gas discharged from the furnace body flows into the furnace body, A preheating chamber in which the zones are provided radially; And a moving unit installed in the preheating chamber and moving the scrap so that the scrap is sequentially moved along the plurality of preheating zones; The plurality of preheating zones may include an input preheating zone connected to an inlet through which the scrap is injected, a discharge preheating zone connected to an outlet through which the scrap preheated into the furnace body is discharged, and a discharge preheating zone disposed between the input preheating zone and the discharge preheating zone. It is desirable to provide an electric furnace including at least one intermediate preheating zone.

In addition, the mobile unit may include a rotating shaft installed vertically in the center of the preheating chamber; And partition plates which are radially arranged and rotated about the rotation axis.

Further, the partition plates include upper gas flow passages and lower gas flow passages through which exhaust gas passes; And a gate valve for selectively opening and closing the upper gas flow passage and the lower gas flow passage so that exhaust gas passes through the plurality of preheating zones in a staggered manner.

In addition, the scrap preheater further includes a duct portion through which the exhaust gas flowing into the preheating chamber escapes; Wherein the duct portion includes a first exhaust duct through which exhaust gas flowing into the input preheating zone escapes; A second exhaust duct through which the exhaust gas flowing into the intermediate preheating zone adjacent to the input preheating zone escapes; And a main duct connected to the first exhaust duct and the second exhaust duct.

According to an aspect of the present invention, there is provided a method of manufacturing a screed; Providing exhaust gas generated in the process of melting scrap in the furnace body to a preheating chamber in which scrap to be supplied to the furnace body is stored to preheat the scrap; The scrap preheating step preheats the scrap while sequentially passing through a plurality of preheating zones provided in the preheating chamber, and the scrap preheated in the plurality of preheating zones is supplied to the stepping step by the moving unit installed in the preheating chamber, and a method for preheating scrap of an electric furnace which is supplied to the furnace body by moving a plurality of preheating zones in a step-by-step manner.

In addition, the plurality of preheating zones may include an input preheating zone in which the scrap provided in the preheating chamber is connected, a discharge preheating zone connected to an outlet through which the scrap preheated into the furnace body is discharged, And at least one intermediate preheat zone disposed between the exhaust preheat zone, wherein exhaust gas passes through the exhaust preheat zone, the at least one intermediate preheat zone, and the input preheat zone in a staggered manner while preheating the scrap stored in each preheat zone can do.

In the scrap preheating step, the gas flow passage to the input preheating zone is cut off when the scrap is introduced into the input preheating zone through the inlet, and from the intermediate preheating zone adjacent to the input preheating zone The exhaust gas can be exhausted.

According to the embodiment of the present invention, the scrap is supplied and preheated by a step-by-step method, so that the residence time of the scrap is long, so that the utilization of the exhaust gas sensible heat can be maximized.

According to the embodiment of the present invention, it is possible to prevent the exhaust gas from flowing out to the outside during the scrap injection, and have a special effect that the scrap can be preheated in the preheating zone other than the preheating zone into which the scrap is injected.

1 is a perspective view illustrating an electric arc furnace according to the present invention.
2 is a plan view of the electric arc shown in Fig.
3 is a side view of the electric arc shown in Fig.
4 is an exploded perspective view illustrating the scrap preheater shown in FIG.
5 is a side cross-sectional view of the scrap preheater.
6 is a plan sectional view taken along the line AA shown in Fig.
Fig. 7 is a plan sectional view taken along the BB line shown in Fig. 5; Fig.
8 and 9 are views for explaining an exhaust gas flow in the scrap preheater.
10 is a plan sectional view of the partition plate shown in Fig.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout the specification and claims. The description will be omitted.

(Example)

FIG. 1 is a perspective view for explaining an electric arc according to the present invention, FIG. 2 is a plan view of the electric arc shown in FIG. 1, and FIG. 3 is a side view of the electric arc shown in FIG.

An electric arc furnace according to an embodiment of the present invention is an apparatus for manufacturing steel by dissolving and refining scrap by arc (ARC) heat generated between an electrode and an iron scrap (hereinafter referred to as " scrap " to be.

1 to 3, an electric arc furnace 10 includes a furnace body 100, a scrap preheater 20, and an exhaust unit 500.

The body 100 includes a cylindrical container 110 for receiving the scrap S to be melted and a container cover 120 for closing the open top of the container 110. [

The container cover 120 may be provided in a water-cooled manner, and three electrodes 130 are installed vertically through the center of the container cover 120 for a melting process. The electrode 130 may move up and down in the furnace body 10 and the electrode 130 may be connected to a three phase AC power source.

Although not shown, a sealing material is attached to the periphery of the container cover and the periphery of the electrode to eliminate the clearance and prevent the air from intruding into the main body from the outside. Although not shown, the vessel 110 may be provided with a slag discharge port for discharging the slag and a molten steel discharge port for discharging the molten steel.

The main body 100 is provided with an exhaust port 140 through which exhaust gas is exhausted to a position displaced from the center of the container cover 120 and scrap preheated by the scrap preheater is introduced. The outlet port of the scrap preheater is connected to the exhaust port.

The exhaust gas generated in the main body 100 passes through the scrap preheater connected to the exhaust port 140 by the suction force provided by the exhaust unit 500 and preheats the scrap and is supplied to the exhaust unit 500, Exhausted. The exhaust unit 500 may include a suction fan 510, a dust collector 520, and the like.

4 and 5 are an exploded perspective view and side sectional view for explaining the scrap preheater shown in Fig. 1, Fig. 6 is a plan sectional view taken along the line AA shown in Fig. 5, Fig. 7 is a cross- It is a flat section taken along the line.

4 to 7, the scrap preheater 20 includes a preheating chamber 200, a moving unit 300, and a duct unit 400.

The preheating chamber 200 may be provided with an internal space in which the scrap is stored in a cylindrical shape whose overall shape is vertical. The preheating chamber 200 may include a plurality of preheating zones for preheating scrap using hot exhaust gas discharged from the furnace body 100. The plurality of preheat zones may include an input preheat zone, an exhaust preheat zone, and at least one intermediate preheat zone. For example, if five entire preheat zones are provided at 75 degree equidistant intervals, three intermediate preheat zones are provided.

The scrap preheater 20 may further include an auxiliary burner 800. The auxiliary burner 800 may be installed at the bottom of the preheating chamber 200 as shown in FIG. 5 toward the preheating zone. The auxiliary burner 800 is provided for ensuring chemical thermal energy by burning Co, H, etc. of the exhaust gas when scrap preheating is insufficient only by sensible heat of the exhaust gas.

In this embodiment, the preheating chamber 200 having four preheating zones 212, 214, 216, and 218 will be described as an example.

The preheating zone 212 is connected to the inlet 202 formed in the upper surface of the preheating chamber 200. The exhaust preheating zone 218 is connected to the exhaust port 204 formed on the bottom surface of the preheating chamber 200 and the exhaust port 204 is connected to the exhaust port 140 of the furnace body 100. The first intermediate preheating zone 214 and the second intermediate preheating zone 216 are disposed between the input preheating zone 212 and the exhaust preheating zone 218. That is, two intermediate preheating zones 214 and 216 and an exhaust preheating zone 218 are arranged on the concentric circle along the clockwise direction on the basis of the input preheating zone 212.

An inlet cover (290) for opening and closing the inlet (202) is installed in the upper part of the preheating chamber (200). The preheating chamber 200 includes a first exhaust port 206 and a second exhaust port 208 through which exhaust gas having passed through the preheating zones is exhausted. The first exhaust port 206 is provided at the lower side of the preheating chamber side corresponding to the input preheating zone 212 and the second exhaust port 208 is provided at the upper end of the corresponding side of the preheating chamber 214 in the first intermediate preheat zone 214 have. A duct portion is connected to the first exhaust port 206 and the second exhaust port 208. [

The exhaust gas flowing into the preheating chamber is exhausted to the duct unit 400 through the selected one of the first exhaust port 206 and the second exhaust port 208.

The duct section 400 includes a first exhaust duct 410, a second exhaust duct 420, and a main duct 430. The main duct 430 is connected to the exhaust part 500.

The first exhaust duct 410 is connected to the first exhaust port 206 and includes a first opening / closing valve 412 installed at a position adjacent to the first exhaust port 206. The first exhaust duct 410 guides the exhaust gas flowing into the input preheating zone 212 to the main duct 430.

The second exhaust duct 420 includes a second open / close valve 422 connected to the second exhaust opening 208 and disposed adjacent to the second exhaust opening 208. The second exhaust duct 410 guides the exhaust gas flowing into the first intermediate preheating zone 214 to the main duct 430.

The mobile unit 300 is installed in the preheating chamber 100. The mobile unit 300 sequentially moves the scrap S along the four preheating zones 212, 214, 216, and 218.

The mobile unit 300 may include a rotation axis 310 and a plurality of partition plates 320. The number of the partition plates 320 can be changed according to the number of the preheating zones provided in the preheating chamber 100. In this embodiment, four preheating zones are provided, so that four partition plates can be provided.

The rotation axis 310 is installed perpendicular to the center of the preheating chamber 100. The rotary shaft 310 may be rotated by a driving unit (not shown) installed outside the preheating chamber 100. The partition plates 320 may be radially disposed at intervals of 90 degrees about the rotation axis 310. [

The partition plates 320 sequentially move the scrap S in a step-by-step manner through a rotating operation. That is, the scrap introduced into the input preheating zone 212 is moved to the first intermediate preheat zone 214 by one rotation operation of the mobile unit 300. Here, the single rotation operation of the mobile unit 300 may be 90 degrees.

The partition plates 320 may provide gas flow passages 330 through which the exhaust gas passes. The partition plates 320 may be provided at different heights so that the gas flow passages 330 of the neighboring partition plates 320 pass through the four preheating zones 212, 214, 216, and 218 in an zigzag manner. In one example, the gas flow passages 330 may be provided at the upper and lower ends of the partition plate 320, respectively. The partition plate 320 may include a gate valve 340 that opens and closes the gas flow passage 330. The partition plate 320 positioned between the discharge preheating zone 218 and the second intermediate preheating zone 216 is opened only in the upper gas flow passage and the second intermediate preheating zone 216 and the first intermediate preheating zone 216 The partition plate 320 located between the first intermediate preheating zone 214 and the input preheating zone 212 is opened only in the lower gas flow passage, Only the gas flow passage is opened. And the partition plate 320 positioned between the input preheating zone 212 and the exhaust preheating zone 218 is controlled so that the two gas flow passages are closed. When the four partition plates 320 are rotated by 90 degrees and their positions are changed, the gate valve 340 is controlled so that only the gas flow passage 330 set at the corresponding position is opened.

In one example, the gas flow passages 330 may be provided in a lattice form so that scrap stored in the preheat zone is not introduced. For example, the gate valve 340 may be provided in an inner space of the partition plate 320, as shown in FIG. 10, to prevent collision and interference with the scrap S in advance during opening and closing operations.

8 and 9 are views for explaining an exhaust gas flow in the scrap preheater. FIGS. 8 and 9 are diagrams showing four preheating zones 212, 214, 216, and 218 laid out in a row for convenience of explanation.

8 shows a scrap preheating process in a state where the scrap is completely put into the input preheating zone 212. The exhaust gas is discharged from the discharge preheating zone 218 through the discharge port 204 in a state where the inlet port 202 is closed by the opening / The second intermediate preheating zone 216 to the first intermediate preheating zone 214 to the input preheating zone 212 and the two intermediate preheating zones 216 and the first intermediate preheating zone 214, The scrap filled in the preheating zone 212 is preheated by the exhaust gas. The exhaust gas moved to the preheating zone 212 is guided to the main duct 430 through the first exhaust duct 410 connected to the first exhaust port 206. The second opening and closing valve 422 of the second exhaust duct 420 is closed and the first opening and closing valve 412 of the first exhaust duct 410 is controlled to be opened.

9 shows the scrap preheating process in a state that the scrap is introduced into the input preheating zone 212. The exhaust gas is discharged through the discharge port 204 in the discharge preheating zone 218 ) -> the second intermediate preheating zone 216 -> the first intermediate preheating zone 214. Both the gas flow passages 330 of the partition plate 320 located between the first intermediate preheating zone 214 and the preheating zone 212 are closed by the gate valve 340. The scrap filled in the second intermediate preheating zone 216 and the first intermediate preheating zone 214 is preheated by the exhaust gas even while the scrap is being introduced into the input preheating zone 212. [ The exhaust gas moved to the first intermediate preheating zone 214 is guided to the main duct 430 through the second exhaust duct 420 connected to the second exhaust port 208. The second on-off valve 422 of the second exhaust duct 420 is opened and the first on-off valve 412 of the first exhaust duct 410 is shut off. Therefore, when the scrap is introduced into the input preheating zone 212, the flow of exhaust gas into the input preheating zone 212 is blocked.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: the main body 20: scrap preheating device
200: preheating chamber 300: mobile unit
400: Duct part

Claims (8)

In the electric furnace:
A furnace body having a cylindrical container for receiving scrap to be melted and a container cover covering the top of the container; And
A plurality of preheating zones installed in the upper portion of the furnace body for storing scrap to be supplied to the furnace body and for preheating scrap before the hot exhaust gas discharged from the furnace body flows into the furnace body, A preheating chamber provided radially; And
A moving unit installed in the preheating chamber and moving the scrap so that the scrap is sequentially moved along the plurality of preheating zones;
The mobile unit
A rotating shaft installed vertically in the center of the preheating chamber; And
And partition plates which are arranged radially and rotated about the rotation axis. delete delete The method according to claim 1,
The partition plates
An upper gas flow passage and a lower gas flow passage through which the exhaust gas flows;
And a gate valve for selectively opening and closing the upper gas flow passage and the lower gas flow passage so that exhaust gas passes through the plurality of preheating zones in a zigzag manner. In the electric furnace:
A furnace body having a cylindrical container for receiving scrap to be melted and a container cover covering the top of the container; And
A plurality of preheating zones installed in the upper portion of the furnace body for storing scrap to be supplied to the furnace body and for preheating scrap before the hot exhaust gas discharged from the furnace body flows into the furnace body, A preheating chamber provided radially;
A moving unit installed in the preheating chamber and moving the scrap so that the scrap is sequentially moved along the plurality of preheating zones; And
And a duct part through which the exhaust gas flowing into the preheating chamber escapes;
The plurality of preheat zones
A discharge preheating zone connected to a discharge port through which the scrap preheated into the furnace body is discharged, and at least one intermediate preheating zone disposed between the discharge preheating zone and the discharge preheating zone, Including,
The duct portion
A first exhaust duct through which the exhaust gas flowing into the input preheating zone escapes;
A second exhaust duct through which the exhaust gas flowing into the intermediate preheating zone adjacent to the input preheating zone escapes; And
And a main duct connected to the first exhaust duct and the second exhaust duct. delete delete delete

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