Industrial electric heating furnaces – Arc furnace device – Charging or discharging
Patent
1996-02-28
1998-11-10
Hoang, Tu B.
Industrial electric heating furnaces
Arc furnace device
Charging or discharging
373 80, 373 52, 373100, F27D 300
Patent
active
058355243
DESCRIPTION:
BRIEF SUMMARY
This Application is a 371 of PCT/AT95/00064 filed on Mar. 30, 1995.
The invention relates to a scrap-melting electric arc furnace, particularly for melting ferrous scrap and, if desired, sponge iron for producing steel.
Conventional direct current scrap-melting electric arc furnaces comprise a single centrically located graphite electrode perpendicularly arranged in the furnace vessel. The maximum energy input feasible, which depends on the secondary current, is limited by the maximum diameter possible of the graphite electrode.
Moreover, the energy input via a single electric arc is concentrated on a site more or less in the center of the furnace and is affected by magnetic influences acting on the electric arc at high powers.
With conventional rotary current arc furnaces, such as, e.g., those according to DE-C-29 44 269, FR-B-2 218 397 and DE-A-32 41 987, a perpendicular crater is melted into the scrap by three electrodes arranged in the center on a partial circle and the remaining scrap is dissolved thereafter. The energy of the hot offgases rises through the empty crater unutilized, thus causing excessive heating of the lid and--as also happens with conventional direct current arc furnaces--a large glowing length of the electrode, which causes intensive lateral consumption of the same. Moreover, very sturdy electrode supporting arms and lifting beams with heavy guides are necessary for the electrodes in order to control the forces and vibrations also brought about by the high currents applied. Such means constitute an essential investment cost factor, rendering the conventional rotary current arc furnace more and more expensive and its operation cumbersome.
From EP-A-0 548 041 an electric arc furnace of the initially defined type is known, which renders it feasible to achieve a particularly high energy input at high operational safety and availability, in that the graphite electrode projects laterally into a lower part of the furnace vessel, with the lower part, in the region of the graphite electrode, having an enlargement radially protruding outwardly relative to the upper part. This radial enlargement has as its purpose to protect the graphite electrode against the falling down of the charging stock. Since the laterally penetrating graphite electrodes themselves are protected from the hot gases which are sucked off upwardly through the scrap column and thus heat the scrap, short glowing lengths of the electrodes as well as a correspondingly lower electrode consumption results.
The object of the present invention is to develop further an electric arc furnace of the last-described type so as to make it feasible, in spite of an elevated melting power, to utilize a furnace vessel having a simple--and thus easily producable--shape. Likewise it is to be feasible to utilize well-proven furnace vessels, namely conventional furnace vessels provided with an upper part having a perpendicular side wall. The thermal load on the side wall of the furnace vessel and the danger of damaging the electrodes during scrap-charging are to be minimized or altogether avoided.
In a scrap-melting electric arc furnace, this task is achieved by the combination of the following characteristic features: oriented so as to be, at least in part, essentially parallel to the vertical center line of the electric arc furnace part and having a diameter which is considerably smaller than the diameter of the upper part, opening provided at the lid and obliquely into the furnace interior and project roughly towards the center of the electric arc furnace.
From DE-C-36 09 923 an electric arc furnace is known, wherein several electrodes disposed on a partial circle are arranged close to the side wall of the upper part of the electric arc furnace and perpendicularly project into the furnace interior through the lid. The electric arc furnace is provided with a shaft mounted on the lid, in which the hot furnace gas heats scrap charged into the shaft. The electrodes are perforce disposed so as to surround the shaft peripherally. One disadvantage o
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Auberger Heinrich
Auer Johann
Berger Harald
Mittag Peter
Steins Johannes
Hoang Tu B.
Voest-Alpine Industrien-lagenbau GmbH
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