JP3273168B2 - Arc furnace scrap conveyor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scrap conveying device in an arc furnace used for melting a metal material, refining a molten metal, and the like.

[0002]

2. Description of the Related Art The charging of scrap into an arc furnace used for melting a metal material, refining a molten metal, and the like is usually performed as follows. That is, scrap is charged in a container called a bucket in advance, and transported to the vicinity of the arc furnace by an overhead crane. The arc furnace has a rotatable furnace lid. When loading scraps, the furnace lid is turned and opened, then the bucket is moved onto the furnace, the bottom of the bucket is opened, and the scrap is put into the furnace.

[0003] When charging scrap into an arc furnace, so-called batch charging is performed two to three times per heat. However, in this method, since the furnace lid is always opened when scrap is charged, there is a problem that heat dissipated from the furnace is large, and the working environment is deteriorated due to generation of dust and the like.

Therefore, various methods for continuously charging scrap have been proposed as a method for charging scrap into the furnace without opening the furnace lid. In the furnace operation in this case,
Since the next melting operation is started with an appropriate amount of molten steel left in the furnace during the previous tapping operation, the operation is in the conventional refining stage from the initial stage of melting.

[0005] In the operation in the refining period, it is important to maintain an appropriate slag thickness on molten steel in order to increase the thermal efficiency of the arc.
It does this by generating gas. For this reason, the amount of gas generated from the furnace also increases as compared with the conventional case. Therefore,
Technology for efficiently recovering the heat of exhaust gas is important. As a technique for achieving this, a technique is known in which exhaust gas is introduced into a scrap conveying device that forms a flue, and the scrap is fed into a furnace while preheating the scrap by flowing it in opposition to the movement of the scrap. ing.

However, in such a scrap conveying device, the exhaust gas passes over the scrap in the conveying device forming the flue, so that the scrap is preheated only in the surface layer portion and the lower layer scrap portion is preheated. In order to raise the preheating temperature, measures must be taken to increase the heat transfer area by increasing the width of the transfer device, or to increase the preheating time by increasing the length of the transfer device. However, there is a problem that the equipment becomes large.

In order to solve such a problem, Japanese Patent Application No. 4-72287, filed by the inventors, has provided a slit-shaped or lattice-shaped exhaust gas passage hole in the bottom plate of the transfer device, and further provided a transfer device. An exhaust gas suction duct is provided below the bottom plate of the device to allow the exhaust gas to pass also in the direction of the thickness of the scrap on the transport device, thereby increasing the preheating temperature of the scrap.

[0008]

However, since scrap materials used in an arc furnace generally include various kinds of scraps such as punched thin sheets or wire-like chips, the above-mentioned bottom plate portion has exhaust gas. In the case of the structure in which the through holes are provided, there is a concern that a portion of the scraps may be clogged with the through holes, which may hinder the smooth supply of scrap to the arc furnace. Therefore, in the present invention, even with the various types of scrap as described above, there is no problem such as clogging of the scrap into the exhaust gas passage hole, and further, the scrap conveying device having high preheating efficiency without increasing the width and length of the conveying device. The purpose is to provide.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a scrap conveying device according to the present invention is directed to an arc furnace while preheating a scrap in which exhaust gas from a furnace is introduced into a scrap conveying device having a flue. In a scrap conveyor of a vibrating conveyor system for supplying, a plurality of holes for exhaust gas suction are provided on a side plate of the scrap conveyor, a collecting pipe for merging exhaust gas passing through each exhaust gas suction hole on the back surface of the side plate of the conveyor, and An exhaust gas duct connected to the collecting pipe is provided.

[0010]

The high-temperature exhaust gas generated in the furnace is introduced into the scrap conveying device forming the flue, passes over the scrap on the conveying device, and at the same time, a part or all of the exhaust gas is in the scrap layer. And passes through an exhaust gas absorbing hole attached to the side plate of the transfer device, and is discharged to an exhaust gas duct via a collecting pipe provided on the back surface of the side plate.

Due to the flow of the exhaust gas, the surface layer of the scrap is preheated by the convection of the exhaust gas and radiant heat transfer.
Further, in the scrap layer, in addition to the conductive heat transfer between the scraps, the heat transfer due to the convection of the exhaust gas passing through the scrap layer is added, so that the lower layer scrap in the transfer device is preheated. Generally, the amount of convective heat transfer by exhaust gas is much larger than the amount of conductive heat transfer between scraps, so that the preheating effect is markedly enhanced.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is an overall plan view of the present invention, and FIG. 2 is a cross-sectional view of the transport device taken along line AA in FIG.

The high-temperature exhaust gas generated by the arc furnace 1 passes through a telescopic connecting pipe (not shown) connecting the arc furnace 1 and the scrap conveying device 2 for gas sealing.
After being introduced into the conveying device 2 forming the flue 3 and preheating the surface layer portion 4 of the scrap by convection and radiant heat transfer, an exhaust gas duct 14 provided near the scrap entrance to the conveying device, a flow control valve It is discharged through 15. Further, a device for preventing leakage of exhaust gas by an air curtain (not shown) or the like is provided at a scrap entrance to the transport device 2.

Exhaust gas passing above the scrap of the transport device partially or entirely passes through the scrap layer,
The gas passes through an exhaust gas suction hole 6 provided in a side plate 5 of the transfer device 2, and is discharged to an exhaust gas duct 10 through a collecting pipe 7 provided on the back surface of the side plate 5. The shape of the exhaust gas suction hole 6 may be circular or square, and various shapes are possible. The exhaust gas duct 10 is provided with a flow rate control valve 11 so that the flow rate of gas passing through the scrap layer can be freely adjusted.

Exhaust gas outlet 8 connected to collecting pipe 7
A connecting portion between the gas discharge duct 10 and the fixed portion on the outer side of the transfer device is a sliding surface 9, and this portion is provided with a simple gas seal material such as a gland packing or a labyrinth structure to prevent invasion of outside air. It can be reduced to a small amount, and it is possible to prevent an increase in the amount of dust collection air.

On the other hand, an exhaust gas bypass duct 12 and a flow control valve 13 are provided at the exhaust gas inlet to the transfer device. Since the preheating temperature of the scrap in the transfer device changes depending on the flow rate and temperature of the exhaust gas discharged from the arc furnace,
The scrap preheating temperature can be easily controlled by adjusting the flow rate of the exhaust gas introduced into the transfer device by the flow rate control valve. Further, by adjusting the flow rate of the exhaust gas introduced into the transfer device according to the type of scrap, it is possible to prevent fusion and oxidation of the scrap due to excessive heating of the scrap surface layer. In the figure, reference numeral 18 denotes a bottom plate, and 19 denotes a gantry.

FIG. 3 shows a second embodiment of the present invention, in which an exhaust gas suction hole is provided obliquely downward toward the inside of the scrap conveying device. FIG. 4 shows a third embodiment of the present invention, and is a view as seen from above taken along the line BB in FIG. As described above, the exhaust gas suction hole can be provided in the scrap advancing direction toward the inside of the transfer device. By providing the exhaust gas suction holes as in the second and third embodiments, it is possible to enhance the prevention of scrap from clogging the exhaust gas suction holes. FIG. 5 shows a fourth embodiment of the present invention, in which a band-shaped metal exhaust gas suction hole cover 17 is provided inside the exhaust gas suction hole 6 inside the scrap conveying device. With this structure, the prevention of the clogging of the scrap into the exhaust gas suction hole 6 can be further enhanced.

[0018]

As described above, in the scrap conveying apparatus according to the present invention, even in the case of various kinds of scraps such as thin punched chips or wire-shaped chips, problems such as the clogging of the scraps into the exhaust gas suction holes are caused. And the furnace exhaust gas not only above the scrap,
By flowing into the scrap layer, heat can be effectively transmitted to the scrap in the lower part of the transfer device, and the thermal efficiency is greatly improved. This makes it possible to improve the reliability of the equipment and increase the efficiency of scrap preheating without increasing the width of the transfer device or increasing the machine length.

Further, by adjusting the amount of exhaust gas on the inlet side to the transfer device and the amount of gas suction in the scrap layer,
The temperature control of the scrap becomes easy, and the operation can be stabilized by making the preheating temperature of the scrap uniform. Further, by suppressing the temperature of the scrap surface layer portion from excessively rising, it is possible to prevent the fusion of the surface layer portion scrap and the oxidation of the scrap.

As described above, according to the present invention, the reliability of the equipment is high, the increase in the equipment cost is suppressed, the thermal efficiency is greatly improved, and as a result, the operation is stabilized, the productivity is improved, and the energy cost is reduced. This greatly contributes to reduction and the like.

[Brief description of the drawings]

FIG. 1 is an overall plan view of the present invention.

FIG. 2 is a cross-sectional view of the transfer device taken along line AA in FIG.

FIG. 3 is a cross-sectional view of another embodiment of the transport device taken along line AA of FIG. 1;

FIG. 4 is an arrow view of FIG. 2 taken along line BB and viewed from above.

FIG. 5 is an enlarged sectional view of a portion C in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace 2 Conveyor 3 Flue 4 Scrap surface layer 5 Side plate 6 Exhaust gas suction hole 7 Collecting pipe 8 Exhaust gas outlet 9 Sliding surface 10 Exhaust gas duct 11 Flow control valve 12 Exhaust gas bypass duct 13 Flow control valve 14 Exhaust gas duct 15 Flow control Valve 16 Cover 17 Exhaust gas suction hole cover 18 Bottom plate 19 Mount

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroshige Matsumoto 46-59 Ohara Nakahara, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Corporation Machinery & Plant Business Department (56) References JP-A-8-157930 ( JP, A) Utility model registration 2568391 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F27D 13/00 F27D 17/00 101

Claims (1)

(57) [Claims] In a scrap conveyor of a vibrating conveyer system for supplying scrap to an arc furnace while preheating a scrap into which a furnace exhaust gas is introduced into a scrap conveyor having a flue, a side plate of the scrap conveyor for exhaust gas suction is provided. A plurality of holes, a collecting pipe for merging exhaust gas passing through each exhaust gas suction hole on the back of the side plate of the conveying apparatus, and an exhaust gas duct connected to the collecting pipe.