US3789127A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arc furnaces
Assignee: British Steel Corp
•
Filing: 1973-01-05
•
Granted: 1974-01-29
•
Expires: 1993-01-05
Abstract
Abstract An electric arc furnace adapted to be powered by direct current includes a bottom electrode of one polarity (positive) mounted in the vessel for contact with the charge and three electrodes of negative polarity depending into the vessel from above. The arcs from the electrodes migrate inwardly which is the opposite of the case with a.c. thus reducing erosion of the furnace walls by concentrating the heat source in the centre. The bottom electrode design is such as to enable the furnace to be tapped whilst maintaining a reservoir of metal for the succeeding charge.
Inventors
- 👤 B Bowman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:08
CPC Classifications
H; H05; H05B; H05B7/00; H05B7/02; H05B7/06; F; F27; F27D; F27D3/00; F27D3/18; H05B7/005
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
81 words
A direct arc furnace comprising: a refining vessel for receiving a steelmaking charge; a source of d.c.; at least one electrode mounted in the vessel for contact with the charge; a plurality of electrodes dependent into the vessel above the charge, the electrodes being symmetrically arranged around a circular path about the vertical axis of the vessel; and means for connecting the d.c. source between the vessel electrode on the one hand and the plurality of dependent electrodes on the other.
Claim 2
Dependent Claim
81 words
A direct arc furnace comprising: a refining vessel for receiving a steelmaking charge; a source of d.c.; at least one electrode mounted in the vessel for contact with the charge; a plurality of electrodes dependent into the vessel above the charge, the electrodes being symmetrically arranged around a circular path about the vertical axis of the vessel; and means for connecting the d.c. source between the vessel electrode on the one hand and the plurality of dependent electrodes on the other.
Claim 3
Dependent Claim
22 words
A furnace according to claim 1, wherein the dependent electrodes are connected as cathodes to the negative supply of the d.c. source.
Claim 4
Dependent Claim
52 words
A furnace according to claim 2, wherein the vessel electrode is constituted by a reservoir of the refined steel located in a well in the base or hearth of the vessel, and including an enclosed rod of metal extending from the reservoir for connection to the positive supply of the d.c. source.
Claim 5
Dependent Claim
29 words
A furnace according to claim 3, wherein the reservoir is bounded by a bowl-shaped depression whereby, when the vessel is tilted for tapping, the reservoir is never completely evacuated.
Claim 6
Dependent Claim
23 words
A furnace according to claim 4, wherein the rod lies in a direction parallel with the axis about which the furnace is tilted.
Claim 7
Dependent Claim
27 words
A furnace according to claim 5, wherein said d.c. source is constituted by a multi-phase rectifier bank whereby to provide a multi-phase rectified supply for each electrode.
Claim 8
Dependent Claim
129 words
A direct arc furnace comprising: a refining vessel for receiving a steelmaking charge; a source of d.c.; a plurality of massive electrodes dependent into the vessel above the charge and symmetrically arranged around a circular path about the vertical axis of the vessel; means for connecting the negative supply of the d.c. source in common to said plurality of electrodes; at least one electrode mounted in the vessel for contact with the charge; and means for connecting said one electrode to the positive supply of the d.c. source and wherein said one electrode is constituted by a reservoir of the refined steel located in a bowl-shaped depression in the wall or hearth of the vessel whereby, when the vessel is tilted for tapping, the reservoir is never completely evacuated.
Claim 9
Dependent Claim
129 words
A direct arc furnace comprising: a refining vessel for receiving a steelmaking charge; a source of d.c.; a plurality of massive electrodes dependent into the vessel above the charge and symmetrically arranged around a circular path about the vertical axis of the vessel; means for connecting the negative supply of the d.c. source in common to said plurality of electrodes; at least one electrode mounted in the vessel for contact with the charge; and means for connecting said one electrode to the positive supply of the d.c. source and wherein said one electrode is constituted by a reservoir of the refined steel located in a bowl-shaped depression in the wall or hearth of the vessel whereby, when the vessel is tilted for tapping, the reservoir is never completely evacuated.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-28 | 1977-07-30 | 1978-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-28 | 1981-07-30 | 1982-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-28 | 1985-07-30 | 1986-01-29 | $7700.00 | Window Closed / Lapsed |