Industrial electric heating furnaces – Arc furnace device – Charging or discharging
Patent
1994-11-15
1996-04-30
Hoang, Tu
Industrial electric heating furnaces
Arc furnace device
Charging or discharging
373 81, 373 87, F27D 1300
Patent
active
055132065
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an apparatus for preheating scrap or pig iron in the form of cold block (hereinafter referred to as scrap material) and continuously charging the same into a melting furnace.
BACKGROUND ART
In order to melt the scrap material, there have been used electric melting furnaces such as DC or AC arc furnaces or non-electrode type melting furnaces in which the scrap material is charged into a furnace shell preliminarily charged with molten steel and oxygen (O.sub.2) and fuel such as oil or coal are fed to the furnace shell to burn the fuel, thereby heating and melting the scrap material.
Conventionally, a furnace roof is opened when scrap material is to be charged into a melting furnace of the type described above.
FIG. 1 schematically illustrates a conventional melting furnace in the form of a DC arc furnace which comprises a furnace shell 2 with a bottom electrode 1 (anode) at its bottom, a furnace roof 3 for selectively opening and closing an upper opening of the furnace shell 2, an upper electrode 4 (cathode) vertically extending through the roof 3 coaxially of the latter, an exhaust duct 5 connected to the roof 3, a roof opening-and-closing device 6 which supports the roof 3 for vertical and pivotal movements of the latter and an electrode raising-and-lowering device 7 mounted on the roof opening-and-closing device 6 for vertically moving the upper electrode 4. The furnace shell 2 is rockably supported by a lower supporting stand 8 through a curved rocker 9. When the furnace shell 2 is tilted in a direction perpendicular to the Figure, molten steel 10 in the furnace shell 2 is poured through a spout (not shown) into a ladle 12 on a carriage 11.
A material preheating device (not shown) installed separately from the furnace shell 2 receives high-temperature exhaust gases from the shell 2 through the exhaust duct 5 to preheat the scrap material, the exhaust duct 5 being midway provided with combustion cylinder means (not shown) for complete combustion of unburned CO gas. The scrap material 13 which has been preheated by the material preheating device is charged at the top of the furnace shell 2 with the roof 3 being opened, using a bucket or the like.
More particularly, in a melting operation of the scrap material 13, the roof opening-and-closing device 6 lifts up the roof 3 and swings it outwardly to open the top of the furnace shell 2. Using a bucket or the like, the scrap material 13 which has been preheated by the preheating device is charged into the furnace shell 2. Then, the top of the furnace shell 2 is closed with the roof 3 and the gases in the furnace shell 2 is sucked by the exhaust duct 5. The upper electrode 4 is lowered gradually to a predetermined position and then the electrodes 1 and 4 are energized to generate and maintain an arc to melt the charged scrap material 13.
In this case, the substantial weight of the scrap material 13 is slight in comparison with volume thereof and a predetermined or desired quantity of molten metal cannot be obtained by only one charge. Therefore, after the completion of one charge, the electrodes 1 and 4 are de-energized and the furnace roof 3 is opened. New scrap material is charged into the furnace shell 2 and the melting operation is repeated in the manner described above. Then, the furnace shell 2 is tilted to pour the molten metal 10 through the spout into the ladle 12.
In the melting furnace of the type described above, whenever the scrap material is to be charged into the furnace shell 2, the furnace roof 3 must be opened. Such opening of the roof 3 causes various adverse problems. High-temperature exhaust gases are dispersed outside of the furnace and a considerably large quantity of heat is dissipated into the surrounding atmosphere, resulting in great heat loss; a considerably large quantity of dust is spread; the charging of the scrap material causes noise; upon charging of additional scrap material 13 the power source must be de-energized to stop the melting operation; and because of the arc time lo
REFERENCES:
patent: 3163520 (1964-12-01), Collin et al.
patent: 3441651 (1969-04-01), Viens et al.
patent: 4385918 (1983-05-01), Dunn et al.
patent: 4676742 (1987-06-01), Kozierok et al.
Iura Toru
Mori Motoharu
Ogushi Masaki
Takeuchi Osamu
Yamamura Ikuo
Hoang Tu
Ishikawajima-Harima Jukogyo Kabushiki Kaisha
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