Industrial electric heating furnaces – Arc furnace device – Furnace body detail
Patent
1993-08-10
1994-12-06
Reynolds, Bruce A.
Industrial electric heating furnaces
Arc furnace device
Furnace body detail
373108, 75 101, 266265, H05B 700
Patent
active
053717597
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a direct current arc furnace or direct current resistance smelting furnace It also relates to a hearth electrode for insertion into the hearth wall of a furnace and an electrode block having such a hearth electrode. Finally the invention also concerns a method of operating such a furnace.
DE-A1-31 06 741 discloses a contact electrode arrangement for electric arc or resistance smelting furnaces, having a base plate which is arranged outside the furnace brick lining structure and to which the outer ends of a plurality of bar-shaped electrodes are conductively connected, wherein the remaining part of the electrode extends into the furnace brick lining structure and is in contact with the molten bath in the furnace hearth. The base plate is disposed at a spacing beneath the furnace bottom. Provided between the base plate and the furnace bottom is an intermediate space into which can flow a fluid for cooling the electrode neck portions, the outside of the furnace and the base plate.
EP-B1-0 219 650 discloses a similar contact electrode arrangement which is in the form of an inter! changeable structural unit.
EP-A1-0 12 4 490 discloses a bottom electrode for a direct current arc furnace, which in the form of an electrically conducting prefabricated structural unit is connected to the metal bath and which rests by way of a layer of electrically conductive granular material on a connecting plate which has a downwardly extending fluid-cooled projection. The interchangeable electrically conducting structural unit which is in contact with the molten bath includes a plurality of metal bars, as current conductors. Also disposed therein are one or more porous bodies for the introduction of a gas, the function of which is to prevent overheating phenomena, by virtue of an increased bath movement. In addition, the structural unit is cooled by the gas which is passed through the porous bricks.
The object of the present invention is to improve the cooling of the electrodes in a direct current are furnace or resistance smelting furnace in order thereby to be able to increase the current loading of the electrodes and thus the output and capacity of the furnace. The invention also seeks to provide an electrode for a direct current arc furnace which permits an improvement in the firing conditions and stabilisation of the arc plasma. The invention also seeks to provide that, after the formation of a molten bath, bath movement for better distribution of the heat in the bath and a desired metallurgical treatment can be carried out with the cooling fluid for cooling the electrodes.
Finally, an object of the invention is to provide a hearth electrode which is distinguished by an increased cooling action and thus a higher current load-carrying capability.
In addition the invention seeks to provide an electrode block having such a hearth electrode, which block can be fitted into the hearth wall of a smelting furnace.
Finally, the invention seeks to provide a method of operating a furnace of the specified kind, which improves firing of the arc in the initial phase of the smelting procedure and promotes the formation of a stable arc plasma for rapid melting of the solid charge.
SUMMARY OF THE INVENTION
In the furnace according to the invention, direct cooling of the hearth electrode which may include one or more metal bars by way of which the current is carried is no longer restricted to the region of said metal bars, which is disposed outwardly in the hearth wall, but the cooling duct extends along the metal bar or bars as far as the inner end thereof and opens into the interior of the furnace. In that way the cooling fluid cools the metal bar over its entire length and thus permits substantially improved cooling for the inner region of the electrode, which is subjected to the greatest thermal loading. The cooling fluid is blown into the furnace in the axial direction of the metal bar and accordingly, with a suitable arrangement of the electrode and a suitable choice in respect of
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Elsner Emil
Wells William
Hoang Tu
Kortec AG
Reynolds Bruce A.
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