Industrial electric heating furnaces – Arc furnace device – Charging or discharging
Patent
1992-08-06
1995-02-14
Reynolds, Bruce A.
Industrial electric heating furnaces
Arc furnace device
Charging or discharging
373 80, 373 86, 75436, 222503, 432241, F27D 300
Patent
active
053902122
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to an installation for producing metal, such as steel, by melting iron material, such as scrap, in an electric arc furnace. For many years now, electric arc furnaces have been one of the most popular means of producing steel by melting down scrap or other ferrous raw materials such as prereduced ores.
BACKGROUND OF THE INVENTION
An electric arc furnace generally comprises a melting vessel made up of a refractory hearth and surrounding sidewalls, a removable roof that closes the vessel, the vessel being associated with one or more electrodes connected to a current source. Each electrode is fitted to the end of a supporting arm overhanging the vessel and penetrates vertically into the vessel through a special hole made for this purpose in the removable roof. The furnace can be supplied either from an alternating current source using three electrodes, or from a direct current source using one or more electrodes. In this case, one or more electrodes are used, each passing through the vault of the furnace and each associated with one or more electrodes mounted in the hearth and each connected to the current source by a return conductor. The furnace is of course associated with a certain number of other items of equipment such as the electrical installations, scrap and additive charging devices, devices for evacuating the molten steel and slag and fume evacuating circuits.
It is further useful in order to improve the efficiency of the furnace to provide a means of preheating the scrap charge before loading it into the furnace. A popular preheating method for doing this consists in passing hot gasses through a preheating enclosure.
This fairly complex assembly of costly, bulky apparatus is installed in a building that is normally arranged in three zones: a scrap metal reception and recovery zone, a preheating zone and a metal-making zone.
The raw scrap is brought to the reception zone in one or more transport containers or "buckets". The buckets are picked up and carried between zones by an overhead travelling crane running the whole length of the installation.
The bottom of each bucket is generally made up of two shells, each pivoted about a horizontal axis, and which, by moving away from each other, let the charge fall into the vessel, the roof of which having been opened. The roof vault and electrodes can be suspended from a gantry that can move horizontally or, preferably, suspended from arms that swing horizontally about a vertical axis on a base next to the furnace.
Because steel production generates a large volume of hot and dusty gasses during the heating and metal-making stages, the resulting fumes are collected by a hood connected to an outwardly fume evacuation circuit via a dedusting means.
The hot gases serving to preheat the scrap can be produced from these fumes in a combustion chamber which serves to burn off carbon monoxide and other unburnt residue and also to recover a part of the dust carried by the fumes. The burnt gases are directed to one or more preheating cells containing scrap waiting to be loaded into the vessel of the furnace.
The travelling crane picks up a bucket from the reception zone, each bucket containing a load of cold scrap, and carries it to the preheating cell where it is left for the necessary period of time. After preheating, the crane picks up the bucket and positions it over the vessel, the scrap then being dropped into the vessel by opening the bottom of the bucket.
During the charging operation, the roof is open, and a large quantity of fumes escape uncollected. Steel and slag may also be projected out of the furnace as the scrap falls into the vessel.
Steel producing installations are also very noisy, and so one design objective is to provide as much insulation as possible in order to reduce fume and noise pollution.
To this end, it has been suggested to combine the preheating zone and the metal-making zone in a closed chamber within which the majority of the fumes and dust produced can be collected and sucked out by a
REFERENCES:
patent: 3147107 (1964-09-01), Brooke et al.
patent: 3444304 (1969-05-01), Longenecker
patent: 4262825 (1981-04-01), Jacobson et al.
patent: 4543124 (1985-09-01), Vallomy
"Application ofstate of theart technology for compact electric arc furnace steel plants"-865 Iron & Steel Engineer-64 (1987) May, No. 5.
Barbe Jacques
Bonnet Claude
Forestier Guy
Clecim
Hoang Tu
Reynolds Bruce A.
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