JPH09105590A - Arc furnace - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To recover heat by using high-temperature exhaust gas generated during melting of a melting raw material. It also suppresses heat loss when tapping molten steel produced by melting. SOLUTION: A melting raw material storage tank is connected to an opening for discharging exhaust gas in a furnace body for melting the melting raw material, and heat is recovered by preheating the melting raw material by the exhaust gas discharged from the opening. I do. The periphery of the opening is separated from the storage tank, and when tapping the steel, only the furnace body is tilted while the storage tank remains stationary. At this time, the immobile storage tank prevents the opening of the furnace body from being completely opened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention can save energy by heating a melting raw material to melt it and recovering the heat of exhaust gas generated at that time by preheating the melting raw material to be melted next. About the arc furnace.

[0002]

2. Description of the Related Art This type of arc furnace is constructed as follows, for example. That is, the furnace body is composed of a concave furnace body having a space for melting the melting raw material inside, and a furnace lid that closes the upper side of the furnace body, and discharges exhaust gas generated by the melting to the furnace lid. There is an opening for this. An electrode for heating the melting raw material is attached to the furnace lid, and a storage tank having a storage space for the melting raw material is attached to communicate with the opening. The furnace body is constructed so as to be tiltable for tapping (see, for example, Japanese Patent Publication No. 3-505625).

According to the arc furnace as described above, the melting raw material can be heated and melted by the arc from the electrode. Moreover, since the high temperature exhaust gas generated at that time can be passed through the storage space to preheat the molten raw material stored therein, the heat can be recovered to save energy. Further, the molten steel produced by melting can be tapped by retracting the furnace lid from above the furnace body so as not to hinder the tilting of the furnace body and tilting the furnace body.

[0004]

In this conventional arc furnace, in the case of the above-mentioned tapping, since the furnace lid and the storage tank attached thereto must be moved together, the moving means becomes large-scale. However, there was a problem that equipment costs increased. Further, in the case of tapping steel, when the furnace lid is retracted, the entire upper side of the furnace main body is opened, and a large amount of heat escapes from there. Further, in the case of the above-mentioned melting, carbon monoxide is mixed in the exhaust gas depending on the melting raw material, but if the exhaust gas containing the carbon monoxide is directly sent to, for example, an electric dust collector, an explosion or the like due to discharge in the dust collector occurs Because of the danger, the exhaust gas is sent to a combustion tower where the carbon monoxide is burned. This causes a problem that an additional equipment cost is required to install the combustion tower.

The arc furnace of the present invention is provided to solve the above-mentioned problems of the prior art. The first purpose is
That is, the melting raw material can be melted by the heat of the arc. The second purpose is to recover the heat in the case of the above melting so that energy can be saved. The third purpose is to allow steel to be tapped by simply tilting the furnace body without moving the storage tank. A fourth object is to reduce heat loss in the case of tapping. Another object of the present invention is that even if carbon monoxide is generated during the dissolution of the dissolution raw material, it can be prevented from going out, and the need for a separate device such as the above conventional one can be eliminated. To do so. Still another object of the present invention is to enable recovery of heat by utilizing the carbon monoxide. Other objects and advantages will be more readily apparent from the drawings and the following description associated therewith.

[0006]

In order to achieve the above object, the arc furnace according to the present invention discharges exhaust gas generated by melting in a melting space for melting a melting raw material and the melting space. The furnace body with the opening of
It is configured so that it can be tilted freely for tapping steel, and that the furnace body is provided with an electrode for heating the melting raw material in the melting space, and the opening is provided with a storage space for the melting raw material. In an arc furnace in which an exhaust gas discharged from the opening is made to pass through the storage space by communicating a storage tank provided therein, a peripheral edge of the opening has an arc shape centered on a central axis of tilting of the furnace body. In addition, the peripheral edge of the opening and the storage tank are separate bodies so that the furnace body can be tilted while the storage tank remains stationary.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The drawings showing the embodiments of the present invention will be described below. Although a DC arc furnace A is illustrated in FIGS. 1 and 2 as an example of the arc furnace, an AC arc furnace may be used. Reference numeral 1 denotes a furnace body in the arc furnace A. The furnace body 1 is supported by a supporting device 2 so as to be tiltable about a tilting central shaft 6 described later. The tilting device 2 has a well-known structure in which the tilting table 3 is supported by a supporting gear 5 attached to a base 4, and the tilting table 3 is located at a position indicated by reference numeral 6 by the rotation of the supporting gear 5. It can be tilted around the tilting central axis. The furnace body 1 is composed of a concave furnace body 8 installed on the tilting table 3 and a furnace lid 9 covering an opening above it. The furnace body 8 has a well-known structure, and has a melting space 10 for melting the melting raw material therein, a steel tap gutter 11 is provided on one side wall, and a tap tap 12 is provided therein. . Although not shown, the side wall on the other side indicated by reference numeral 13 is provided with a slag opening. 14 is a bottom electrode. Reference numeral 16 provided in the furnace lid 9 is an opening for discharging exhaust gas. The opening 16 also serves as a charging port for the melting raw material. Reference numeral 17 denotes a peripheral edge of the opening 16, which is formed in an arc shape centering on the tilting central axis 6 as shown in FIG. As shown in FIG. 2, the outer surface 22 around the opening 16 has an arc shape of the peripheral edge 17 in order to prevent mechanical interference with a storage tank described later when the furnace body 1 is tilted. It is formed so as to be located on the inner side (the side of the tilting central axis 6) of the extension line of.
Reference numeral 18 denotes an electrode for heating the melting raw material, which is an upper electrode, which is attached to the furnace lid 9 and is inserted into an electrode hole provided in the furnace lid 9 so as to be freely inserted and removed. The electrode 18 is supported movably up and down by a well-known support structure composed of members 19 to 21 provided on the tilting base 3. Reference numeral 19 is an electrode column, 20 is an electrode support arm, and 21 is an electrode gripper.

Next, reference numeral 23 shows a storage tank for the molten raw material. The storage tank 23 is constructed separately from the furnace lid 9 as shown in FIG.
The storage tank 23 has storage spaces 24, 25 for storing the dissolved raw material therein, and gates 26, 27 for retaining the dissolved raw material in the respective storage spaces 24, 25 under the storage spaces 24, 25. Each of the gates 26, 27 can be opened and closed in order to drop the molten raw material downward, and is formed so as to be ventilated so as to allow the high temperature gas to flow into each storage space. The details will be described later. Reference numeral 30 denotes a gas receiving port in the storage tank 23, and as shown in FIG. 2, it is in communication with the opening 16 by being opposed to the opening 16. The port 30 not only receives exhaust gas, but also serves as a discharge port for discharging the preheated melting raw material toward the melting space 10 in the furnace body 1. Reference numeral 31 denotes a peripheral edge of the receiving port 30, which does not mechanically interfere with the peripheral edge 17 of the opening 16 of the furnace body 1 and has a fixed gap between the peripheral edge 17 of the opening 16 and the central axis. It is formed so as to have an arc shape centered at 6. Reference numerals 32 and 33 denote cover members provided to cover a portion of the opening 16 which is laterally displaced from the receiving port 30 when the furnace body 1 is tilted. The covering members 32 and 33 are formed in an arc shape in which the arc shape of the peripheral edge 31 is extended. ing. 34 and 35 are combustion spaces for burning unburned gas in the exhaust gas discharged from the furnace body 1, for example, carbon monoxide described later, and the flow direction of the exhaust gas in the storage tank 23 (arrows).
(Shown by 62 and 64) is provided at a position closer to the inlet 30 than the storage spaces 24 and 25. Reference numeral 36 is a melting material charging port, which is provided with a door 37 that can be opened and closed by lateral movement.
38 is a shunt duct for diverting the high-temperature exhaust gas entering the receiving port 30 toward the combustion space 35, 39 is an exhaust gas duct for discharging the exhaust gas that is no longer needed, and one end of both storage spaces 24, 25
The other end is connected to, for example, an electric dust collector via a blower (not shown). 40 is the above storage tank
It is a trolley that supports 23 and can be moved along the rail 41 in the direction of the arrow. The movement is performed to separate the furnace body 1 and the storage tank 23 from each other when the repair is performed. Reference numeral 42 denotes a bucket for charging the molten raw material into the storage tank 23.

Next, reference numeral 45 shown in FIG. 2 denotes an air inlet for taking in air required for combustion of gas in the combustion space, which is between the peripheral edge 17 of the opening 16 and the peripheral edge 31 of the receiving port 30. It has a gap. Reference numeral 46 is an adjusting member for adjusting the intake amount of air from the air intake port 45, and the intake amount of air can be adjusted by the vertical movement of the cylinder 47.

Next, the gate 26 is constituted by a pair of gate elements 50, 50 which can be opened and closed. Each gate element
The shaft 50 is configured by attaching a plurality of fingers 52 in a cage shape to a shaft 51 that is rotatable with respect to the storage tank 23.
It can be opened and closed as indicated by the arrow by operating the operating lever 53 attached to the. Reference numeral 54 indicates the switchgear. Reference numeral 55 denotes a hydraulic cylinder in the opening / closing device 54, the main body of which is attached to the storage tank 23 using a bracket 56, and the piston rod is connected to the lever 53. The other upper gate 27 has the same structure as the above gate 26, and a duplicate description will be omitted.

The melting of the melting raw material in the arc furnace A having the above-mentioned structure is the same as in the known DC arc furnace. That is, the furnace body 1
A melting raw material is charged into the melting space 10 therein. A DC voltage is applied between the bottom electrode 14 and the upper electrode 18,
The arc is emitted from. The melting raw material is melted by the heat of the arc and becomes molten steel.

In the case of melting in the arc furnace A, preheating of the melting raw material is performed in the storage tank 23 as follows. Prior to the operation of the arc furnace A, the molten material (for example, scrap) M is previously stored in the storage spaces 24 and 25 through the charging port 36.
Is loaded as shown in FIG. 1, and the loading port 36 is closed by a door 37.
In this state, the arc furnace A is operated as described above. In the furnace body 1, high temperature exhaust gas is generated during melting of the melting raw material, and the high temperature exhaust gas is discharged from the opening 16. The discharged high-temperature exhaust gas passes through the inlet 30 and the combustion space 34 as shown by an arrow 61, and passes through the storage space 24 as shown by an arrow 62.
This exhaust gas preheats the melting raw material M in the storage space 24. Moreover, a part of the high temperature exhaust gas passing through the above-mentioned inlet 30 is indicated by an arrow.
As shown by 63, it reaches the combustion space 35 through the diversion duct 38, and then passes through the storage space 25 as shown by an arrow 64. This exhaust gas preheats the molten raw material M in the storage space 25. The exhaust gas after preheating the molten raw materials in the storage spaces 24, 25 is discharged through the discharge duct 39.

The charging of the preheated melting raw material into the furnace body 1 is performed by, as is well known, when each of the gate elements 50 in the gate 26 is required to be supplemented with the melting raw material. Figure 2
Then, the molten raw material M in the storage space 24 is charged into the furnace body 1 as shown by the chain double-dashed line. After that, the gate 26 is closed, the upper gate 27 is opened, the melting raw material in the storage space 25 is transferred to the storage space 24, the gate 27 is closed, and then a new melting raw material is stored in the storage space 25.
To charge. Then, in the same manner as described above, the molten raw material in each storage space 24, 25 is preheated by the exhaust gas.

Next, in the case of melting in the arc furnace A, unburned gas such as carbon monoxide is generated depending on the kind of the melting raw material, which is contained in the exhaust gas and is discharged together from the opening 16. There are cases. In such a case, the carbon monoxide can be burned as follows. The air from the air intake 45 is taken into the combustion space 34 from the inlet 30 together with the exhaust gas containing carbon monoxide. The intake can be performed by suction of the blower to which the exhaust duct 39 is connected. In the combustion space 34, the carbon monoxide is burned by the air taken in. Since the hot gas generated by this combustion passes through the storage space 24, the molten material M in the storage space 24 can also be heated by the hot gas. Further, the exhaust gas containing carbon monoxide and the air flowing from the receiving port 30 reach the combustion space 35 through the diversion duct 38. Therefore, the carbon monoxide can be burned also in the combustion space 35. Since the hot gas generated by the combustion passes through the storage space 25, the melting raw material M there can be heated. In the above case, it is advisable to adjust the opening degree from the air intake port 45 by the adjusting member 46 so that an appropriate amount of air can be taken in for the combustion.

Next, in the above arc furnace, molten steel is tapped from the furnace body 1 as follows. That is, while keeping the upper storage tank 23 as it is, the furnace body 1 is tilted to the left in FIG. 2 to obtain the state as shown in FIG. The tilt angle is, for example, about 15 to 25 °. Due to the tilting, the molten steel in the furnace body 1 is tapped from the tapping port 12 of the tapping gutter 11. In the case of the tilting, since the peripheral edge 17 of the opening 16 in the furnace body 1 is formed in the arc shape as described above, it does not interfere with the storage tank 23 at all. Further, the opening 30 in the storage tank 23 remains covering most of the opening 16 of the tilted furnace body 1, and the opening 16
Since the part of the opening 16 that is separated from the opening 30 is also covered by the covering member 32, the amount of heat released from the opening 16 is small. In this case, since the opening 30 still covers most of the opening 16 as described above, the heat release from the opening 16 can be suppressed to a small amount even if the member 32 is not provided. On the other hand, in the case of discharging slag, the furnace body 1 is tilted to the right in FIG. 2 (for example, about 10 °) to a state as shown in FIG. To do. Even in this case, the opening 16
The heat release from the is suppressed.

Next, in the storage tank 23, the diversion duct 38 is not provided, and the discharge duct 39 is connected to the position shown by the chain double-dashed line so that the exhaust gas used for preheating the molten raw material is stored in the storage tank 23. The melting raw material M may be preheated by the exhaust gas flowing upward in the storage space 25 so as to be discharged from the upper portion.

[0017]

As described above, in the present invention, the melting raw material M can be melted by the heat of the arc, and the high temperature exhaust gas generated in that case is passed through the storage tank 23 and stored therein. Since the melting raw material M can be preheated, heat can be recovered to save energy. Moreover, the furnace body 1
The peripheral edge 17 of the opening 16 for exhausting the exhaust gas is formed in an arc shape around the tilting central axis 6 of the furnace body 1, and even if the furnace body 1 is tilted, the peripheral edge 17 interferes with the storage tank 23. Therefore, in the case of tapping steel, there is a feature that tapping can be performed by simply tilting the furnace body 1 while leaving the storage tank 23 as it is. This is effective in solving the problem that the moving mechanism of the prior art becomes large in scale and requires a large amount of equipment cost. In the case of the above tapped steel, a storage tank
Since it suffices to tilt only the furnace body 1 while leaving 23 as it is, the opening 16 of the furnace body in the tilted state can be covered with the storage tank 23 which has not moved. Therefore, there is a feature that the opening ratio of the opening 16 to the outside can be suppressed small, and as a result, there is an effect that heat loss in the case of tapping steel can be reduced. Further, according to the invention of claim 2, even if carbon monoxide is generated during the dissolution of the dissolution raw material M, it can be burned in the combustion space 34 of the storage tank 23, so that the carbon monoxide is removed from the outside. There is a feature that can be kept out. This is effective in solving the problem that the above-mentioned prior art required facility cost for the combustion tower. Moreover, since the hot gas produced by burning the carbon monoxide passes through the storage space 24, the melting raw material M can be preheated by the heat of the hot gas,
There is also an effect that further energy saving can be achieved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an arc furnace.

2 is an enlarged sectional view taken along line II-II in FIG.

FIG. 3A is a sectional view showing a state at the time of tapping, and FIG. 3B is a sectional view showing a state at the time of tapping.

[Explanation of symbols]

 1 Reactor body 6 Tilt central axis 16 Opening 17 Edge 23 Perimeter 23 Storage tank 24 Storage space 34 Combustion space

Claims (2)

[Claims] 1. A melting space for melting a melting raw material,
A furnace body having an opening for discharging exhaust gas generated by melting in the melting space is configured to be tiltable for tapping, and the melting space is provided in the furnace body. There is an electrode attached to heat the molten raw material in
In an arc furnace in which a storage tank having a storage space for melted raw material is communicated with the opening so that exhaust gas discharged from the opening passes through the storage space, the periphery of the opening is a furnace body. In addition to having a circular arc centered around the central axis of tilting, the peripheral edge of the opening and the storage tank are separate bodies so that the furnace body can be tilted without moving the storage tank. An arc furnace characterized by the fact that there is. 2. The storage tank is provided with a combustion space, and after carbon monoxide contained in the exhaust gas is burned in the combustion space, the carbon monoxide is discharged through the storage space. The arc furnace according to claim 1.