US3899628A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric arc furnace with auxiliary burners
Assignee: Southern California Gas Co
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Filing: 1973-09-04
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Granted: 1975-08-12
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Expires: 1993-09-04
Abstract
Abstract In a furnace having a hearth, a side wall surrounding the hearth, and a roof over the side wall to define a generally cylindrical enclosure with a vertical central axis, a plurality of electrodes extending vertically through the roof into the center of the enclosure, and an exhaust at the top of the enclosure, one or more auxiliary burners along the side wall are oriented in a downward and radially inward direction that intersects the central axis. The burners, which are preferably recessed outwardly from the surface of the furnace side wall, each comprise an elongated, conical passage having an outlet opening into the furnace enclosure and a smaller inlet to which a combustible mixture is supplied; a pilot unit is located near the inlet. A single source of oxygen, such as an air blower, is employed for a plurality of burners and a carbonaceous fuel supplied to each burner is individually regulated responsive to the flow of oxygen to maintain a fuel rich combustible mixture with a constant fuel-oxygen ratio.
Inventors
- 👤 John H Hirt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:49
CPC Classifications
F; F27; F27D; F27D11/00; F27D11/08; F27B; F27B3/00; F27B3/08
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
160 words
An electric arc furnace comprising: a furnace having a hearth, a side wall surrounding the hearth, and a roof over the side wall to define a generally cylindrical enclosure with a vertical central axis; a plurality of electrodes extending vertically through the roof into the center of the enclosure; a source of carbonaceous fluid fuel; a source of oxygen; means for mixing the fuel and the oxygen to form a combustible mixture; means for igniting the combustible mixture; and a burner for directing the ignited combustible mixture into the enclosure in a downward and radially inward direction that intersects the central axis, the burner having an elongated passage outwardly disposed from the side wall of the furnace, the passage having an inlet coupled to the mixing means, an outlet opening into the enclosure at the side wall, and a longitudinal axis extending downwardly from the inlet through the outlet to intersect the central axis of the furnace in the hearth.
Claim 2
Dependent Claim
160 words
An electric arc furnace comprising: a furnace having a hearth, a side wall surrounding the hearth, and a roof over the side wall to define a generally cylindrical enclosure with a vertical central axis; a plurality of electrodes extending vertically through the roof into the center of the enclosure; a source of carbonaceous fluid fuel; a source of oxygen; means for mixing the fuel and the oxygen to form a combustible mixture; means for igniting the combustible mixture; and a burner for directing the ignited combustible mixture into the enclosure in a downward and radially inward direction that intersects the central axis, the burner having an elongated passage outwardly disposed from the side wall of the furnace, the passage having an inlet coupled to the mixing means, an outlet opening into the enclosure at the side wall, and a longitudinal axis extending downwardly from the inlet through the outlet to intersect the central axis of the furnace in the hearth.
Claim 3
Dependent Claim
16 words
The furnace of claim 1, in which the mixing means maintains a fuel rich combustible mixture.
Claim 4
Dependent Claim
83 words
The furnace of claim 1, in which the mixing means comprises a first conduit for coupling the source of oxygen to the igniting means, a second conduit for coupling the source of fuel to the igniting means, and a ratio regulator disposed in the second conduit to control the flow rate through the second conduit responsive to the pressure in the first conduit to maintain a constant pressure ratio between the fuel and the oxygen such that the combustible mixture is fuel rich.
Claim 5
Dependent Claim
37 words
The furnace of claim 1, in which the directing means directs the ignited combustible mixture into the enclosure in a downward and radially inward direction from a plurality of points at the side wall of the furnace.
Claim 6
Dependent Claim
19 words
The furnace of claim 1, in which the passage is conical and the outlet is larger than the inlet.
Claim 7
Dependent Claim
27 words
The furnace of claim 5, in which the passage has a cylindrical section and a diverging conical section connected in series from the inlet to the outlet.
Claim 8
Dependent Claim
20 words
The furnace of claim 1, additionally comprising an exhaust conduit connected to the enclosure in the vicinity of the roof.
Claim 9
Dependent Claim
146 words
An electric arc furnace comprising: a furnace having a hearth, a side wall surrounding the hearth, and a roof over the side wall to define an enclosure for a charge of metal to be melted and refined; a plurality of electrodes extending vertically through the roof into the enclosure; at least one burner recessed from the surface of the side wall, each burner having an elongated passage with an inlet spaced outwardly from the surface of the side wall and an outlet lying in the plane of the surface of the side wall, the passage of each burner being oriented in a downward direction toward the hearth; a source of carbonaceous fluid fuel; a source of oxygen; means for coupling the fuel and thE oxygen to the inlet of the passage; and means for igniting the fuel and the oxygen near the inlet of the passage.
Claim 10
Dependent Claim
146 words
An electric arc furnace comprising: a furnace having a hearth, a side wall surrounding the hearth, and a roof over the side wall to define an enclosure for a charge of metal to be melted and refined; a plurality of electrodes extending vertically through the roof into the enclosure; at least one burner recessed from the surface of the side wall, each burner having an elongated passage with an inlet spaced outwardly from the surface of the side wall and an outlet lying in the plane of the surface of the side wall, the passage of each burner being oriented in a downward direction toward the hearth; a source of carbonaceous fluid fuel; a source of oxygen; means for coupling the fuel and thE oxygen to the inlet of the passage; and means for igniting the fuel and the oxygen near the inlet of the passage.
Claim 11
Dependent Claim
27 words
The furnace of claim 8, in which the burners are at least three in number and their passages are oriented toward a common point in the hearth.
Claim 12
Dependent Claim
24 words
The furnace of claim 9, in which the passages are formed in blocks of refractory material that fit into openings in the side wall.
Claim 13
Dependent Claim
29 words
The furnace of claim 10, in which the side wall has a metal frame and the blocks of refractory material are supported in metal housings attached to the frame.
Claim 14
Dependent Claim
174 words
An electric arc furnace comprising; a furnace having a hearth, a side wall surrounding the hearth, and a roof over the side wall to define an enclosure for metal to be melted and refined; a plurality of electrodes extending vertically through the roof into the enclosure; a plurality of burners each having an outlet opening into the enclosure and an inlet; a source of carbonaceous fluid fuel; a source of oxygen; an oxygen conduit individual to each burner and connected between the source of oxygen and the inlet of such burner; a fuel conduit individual to each burner and connected between the source of fuel and the inlet of such burner to supply with the oxygen a combustible mixture to the inlet; and means responsive to the flow through each oxygen conduit for controlling the flow through the fuel conduit of the corresponding burner to maintain a constant fuel-oxygen ratio in the combustible mixture supplied to the inlet of each burner despite variations in the flow of the combustible mixture through the individual passages.
Claim 15
Dependent Claim
174 words
An electric arc furnace comprising; a furnace having a hearth, a side wall surrounding the hearth, and a roof over the side wall to define an enclosure for metal to be melted and refined; a plurality of electrodes extending vertically through the roof into the enclosure; a plurality of burners each having an outlet opening into the enclosure and an inlet; a source of carbonaceous fluid fuel; a source of oxygen; an oxygen conduit individual to each burner and connected between the source of oxygen and the inlet of such burner; a fuel conduit individual to each burner and connected between the source of fuel and the inlet of such burner to supply with the oxygen a combustible mixture to the inlet; and means responsive to the flow through each oxygen conduit for controlling the flow through the fuel conduit of the corresponding burner to maintain a constant fuel-oxygen ratio in the combustible mixture supplied to the inlet of each burner despite variations in the flow of the combustible mixture through the individual passages.
Claim 16
Dependent Claim
41 words
The furnace of claim 12, in which the source of oxygen is an air blower, the source of fuel is a natural gas main, and the controlling means are each ratio regulators responsive to the pressure in the corresponding oxygen conduits.
Claim 17
Dependent Claim
180 words
In an electric arc furnace having a hearth, a side wall surrounding the hearth, and a roof over the side wall to define a generally cylindrical enclosure with a vertical central axis in which a scrap heap is disposed; a plurality of electrodes extending vertically through the roof into the center of the enclosure; and means for withdrawing products of combustion from the top of the enclosure, the improvement comprising: a source of natural gas; a source of air; means for mixing the natural gas and the air to form a combustible mixture; a plurality of burners distributed along the side wall of the furnace and opening into the furnace at the bottom of the enclosure, to draw heat from the burners up through the spaces in the scrap heap and uniformly heat the scrap, each burner comprising an elongated downward and radially inwardly oriented passage having a longitudinal axis that intersects the central axis of the furnace within the hearth; means for coupling the combustible mixture to the burners; and means for igniting the combustible mixture in the burners.
Claim 18
Dependent Claim
180 words
In an electric arc furnace having a hearth, a side wall surrounding the hearth, and a roof over the side wall to define a generally cylindrical enclosure with a vertical central axis in which a scrap heap is disposed; a plurality of electrodes extending vertically through the roof into the center of the enclosure; and means for withdrawing products of combustion from the top of the enclosure, the improvement comprising: a source of natural gas; a source of air; means for mixing the natural gas and the air to form a combustible mixture; a plurality of burners distributed along the side wall of the furnace and opening into the furnace at the bottom of the enclosure, to draw heat from the burners up through the spaces in the scrap heap and uniformly heat the scrap, each burner comprising an elongated downward and radially inwardly oriented passage having a longitudinal axis that intersects the central axis of the furnace within the hearth; means for coupling the combustible mixture to the burners; and means for igniting the combustible mixture in the burners.
Claim 19
Dependent Claim
43 words
The improvement of claim 14, in which the passage is conical and has an outlet larger than its inlet, the outlet opening into the furnace, the coupling means supplying the combustible mixture to the inlet, and the igniting means being near the inlet.
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) | 1978-08-11 | 1979-02-10 | 1979-08-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-11 | 1983-02-10 | 1983-08-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-11 | 1987-02-10 | 1987-08-12 | $7700.00 | Window Closed / Lapsed |