US4242532A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of controlling exhaust gas emissions from an electric arc furnace
Assignee: Ford Motor Co
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Filing: 1979-12-21
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Granted: 1980-12-30
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Expires: 1999-12-21
Abstract
Abstract A method for controlling exhaust gases emitted from a direct arc furnace melting furnace. Prior to cleaning the temperature of the gases is sensed and the arc power is regulated in response to the sensed exhaust gas temperature. Also, the cleaning process of the gases is changed depending upon the sensed gas temperature.
Inventors
- 👤 John D. Squibbs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:26
CPC Classifications
F; F27; F27D; F27D17/00; F27D17/20; F27D17/28; F27D17/30; F27D17/304; F27D19/00; F27D2019/0006; F27D2019/0018; F27D2019/0021; F27D2019/0028; F27D2019/0034; F27D2019/0037
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
320 words
A method for controlling exhaust gases from a direct arc electric furnace having (A) an electrode suspension control system effective to raise and lower furnace electrodes in relation to a metal charge within the furnace thereby to regulate the arc gap between said electrodes and said metal, (B) an exhaust conditioning system effective to collect gases generated by operation of said furnace and deliver said gases to a treatment station for removal of air pollutants from said gases, and (C) bypass means effective for diverting said gases away from said treatment station when the temperature of said gases exceeds a predetermined temperature, said method comprising: (1) at a sensing location in said exhaust conditioning system positioned upstream from the entrance to said treating station, continuously sensing the temperature of said gases and generating a control signal having a strength directly proportional to the temperature sensed, (2) dividing said continuous control signal into three categories based on the strength of said continuous control signal, said three categories including (a) a first category comprising strength levels below a first actuation level, (b) a second category comprising strength levels at and above said first actuation level, but below a second actuation level, and (c) a third category comprising strength levels at or above said second actuation level, said second actuation level indicating a measurably higher gas temperature at said sensing location than the gas temperature at said sensing location at said first actuation level, (3) directing said gases in said exhaust conditioning system into said treatment station when said control signal is in said first category or said second category, (4) actuating said electrode suspension control system to alter the arc gap to regulate the current to said metal when said control signal is in said second category, and (5) actuating said bypass means whereby said gases are diverted away from said treatment station when said control signal is in said third category.
Claim 2
Independent Claim
320 words
A method for controlling exhaust gases from a direct arc electric furnace having (A) an electrode suspension control system effective to raise and lower furnace electrodes in relation to a metal charge within the furnace thereby to regulate the arc gap between said electrodes and said metal, (B) an exhaust conditioning system effective to collect gases generated by operation of said furnace and deliver said gases to a treatment station for removal of air pollutants from said gases, and (C) bypass means effective for diverting said gases away from said treatment station when the temperature of said gases exceeds a predetermined temperature, said method comprising: (1) at a sensing location in said exhaust conditioning system positioned upstream from the entrance to said treating station, continuously sensing the temperature of said gases and generating a control signal having a strength directly proportional to the temperature sensed, (2) dividing said continuous control signal into three categories based on the strength of said continuous control signal, said three categories including (a) a first category comprising strength levels below a first actuation level, (b) a second category comprising strength levels at and above said first actuation level, but below a second actuation level, and (c) a third category comprising strength levels at or above said second actuation level, said second actuation level indicating a measurably higher gas temperature at said sensing location than the gas temperature at said sensing location at said first actuation level, (3) directing said gases in said exhaust conditioning system into said treatment station when said control signal is in said first category or said second category, (4) actuating said electrode suspension control system to alter the arc gap to regulate the current to said metal when said control signal is in said second category, and (5) actuating said bypass means whereby said gases are diverted away from said treatment station when said control signal is in said third category.
Claim 3
Dependent Claim
35 words
The method as in claim 1, in which said first actuation level for the control signal is set below said second actuation level for the control signal by a differential of at least 25° F.
Claim 4
Dependent Claim
49 words
The method as in claim 1, in which in step (c) the arc gap is first increased and later decreased and said decrease of the arc gap takes place in response to a delay of at least 90 seconds after said control signal descends below the first actuation level.
Claim 5
Dependent Claim
32 words
The method as in claim 1, in which said arc gap is increased to provide a spacing between said electrodes and said metal of at least six inches thereby extinguishing the arc.
Claim 6
Dependent Claim
41 words
The method as in claim 1, in which a sensed temperature of 275° F. generates a control signal strength of said first actuation level and the sensed temperature of 300° F. generates a control signal strength of said second actuation level.
Claim 7
Dependent Claim
53 words
The method as in claim 1, in which said electrode suspension system is actuated and controlled by means effective to proportion the spacing between said electrodes and said metal in relation to the excess temperature of said gases over the sensed temperature that generates a control signal strength of said first actuation level.
Claim 8
Dependent Claim
50 words
The method as in claim 1, in which the control for actuating said electrode suspension control system in response to said control signal includes a closed loop computer programmed to cycle the actuation of said suspension system on a continuous basis and thereby achieve a relatively constant exhaust gas temperature.
Claim 9
Independent Claim
278 words
A method for controlling exhaust gases from a direct arc electric furnace having (A) an electrode suspension control system effective to raise and lower furnace electrodes in relation to a metal charge within the furnace thereby to regulate the arc gap between said electrodes and said metal, (B) an exhaust conditioning system effective to collect gases generated by operation of said furnace and deliver said gases to a treatment station for removal of air pollutants from said gases, and (C) bypass means effective for diverting said gases away from said treatment station when the temperature of said gases exceeds a predetermined temperature, said method comprising: (1) at a sensing location in said exhaust conditioning system positioned upstream from the entrance to said treating station, continuously sensing the temperature of said gases and generating a control signal having a strength proportional to the temperature sensed, (2) dividing said continuous control signal into three categories based on the strength of said continuous control signal, said three categories including (a) a first category comprising a first range of strength levels, (b) a second category comprising a second range of strength levels, (c) a third category comprising a third range of strength levels, (3) directing said gases in said exhaust conditioning system into said treatment station when said control signal is in said first category or said second category, (4) actuating said electrode suspension control system to alter the arc gap to regulate the current to said metal when said control signal is in said second category, and (5) actuating said bypass means whereby said gases are diverted away from said treatment station when said control signal is in said third category.
Claim 10
Independent Claim
278 words
A method for controlling exhaust gases from a direct arc electric furnace having (A) an electrode suspension control system effective to raise and lower furnace electrodes in relation to a metal charge within the furnace thereby to regulate the arc gap between said electrodes and said metal, (B) an exhaust conditioning system effective to collect gases generated by operation of said furnace and deliver said gases to a treatment station for removal of air pollutants from said gases, and (C) bypass means effective for diverting said gases away from said treatment station when the temperature of said gases exceeds a predetermined temperature, said method comprising: (1) at a sensing location in said exhaust conditioning system positioned upstream from the entrance to said treating station, continuously sensing the temperature of said gases and generating a control signal having a strength proportional to the temperature sensed, (2) dividing said continuous control signal into three categories based on the strength of said continuous control signal, said three categories including (a) a first category comprising a first range of strength levels, (b) a second category comprising a second range of strength levels, (c) a third category comprising a third range of strength levels, (3) directing said gases in said exhaust conditioning system into said treatment station when said control signal is in said first category or said second category, (4) actuating said electrode suspension control system to alter the arc gap to regulate the current to said metal when said control signal is in said second category, and (5) actuating said bypass means whereby said gases are diverted away from said treatment station when said control signal is in said third category.
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) | 1983-12-30 | 1984-06-30 | 1984-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-30 | 1988-06-30 | 1988-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-30 | 1992-06-30 | 1992-12-30 | $7700.00 | Window Closed / Lapsed |