Claims
- 1. A fume extraction system for containing fumes generated by a furnace, comprising:
a combustion zone including a combustion chamber and an inlet that is connectable with an exhaust outlet of the furnace so as to receive an exhaust gas stream emerging from the furnace outlet, the exhaust gas stream including explosive gases that undergo combustion reactions within the combustion zone; a duct section aligned downstream from the combustion chamber to deliver the exhaust gas stream toward a system vent outlet; a suction unit arranged within the system to establish a negative pressure within the furnace, the combustion zone, and the duct section so as to draw the exhaust gas stream from the furnace outlet and through the combustion zone and duct section during system operation; an adjustable exhaust damper disposed at a selected location within the system between the inlet of the combustion zone and the suction unit; and a control system to selectively control the negative pressure applied to the furnace, the combustion zone and the duct section, the control system comprising:
a gas sensor device disposed at a selected location within the system to measure a concentration of at least one of oxygen, carbon monoxide, hydrogen, carbon dioxide, water and nitrogen within the exhaust gas stream; and a controller in communication with the gas sensor device and the exhaust damper, wherein, during system operation, the controller effects opening and closing of the exhaust damper to selectively modify the negative pressure within the furnace, the combustion zone and the duct section based upon gas concentration measurements received from the gas sensor device.
- 2. The system of claim 1, wherein the control system includes a plurality of gas sensor devices disposed at selected locations within the system to measure concentrations of at least two different exhaust gas constituents.
- 3. The system of claim 1, wherein the gas sensor device includes an oxygen sensor to measure the concentration of oxygen in the exhaust gas stream.
- 4. The system of claim 3, wherein the oxygen sensor is disposed at a location in the system where a majority of the explosive gases within the exhaust gas stream have already undergone combustion reactions, and the controller effects opening and closing of the exhaust damper to increase or decrease the negative pressure within the furnace, the combustion zone, and the duct section so as to maintain an oxygen content within the exhaust gas stream at the location of the oxygen sensor within a selected range of concentration values.
- 5. The system of claim 4, wherein the controller effects opening of the exhaust damper to increase the negative pressure within the furnace, the combustion zone, and the duct section when the oxygen sensor measures a concentration of oxygen within the exhaust gas stream that is less than about 5% v/v.
- 6. The system of claim 4, wherein the controller effects partial closure of the exhaust damper to decrease the negative pressure within the furnace, the combustion zone, and the duct section when the oxygen sensor measures a concentration of oxygen within the exhaust gas stream that is greater than about 10% v/v.
- 7. The system of claim 4, wherein the controller effects opening and closing of the exhaust damper to increase or decrease the negative pressure within the furnace, the combustion zone, and the duct section so as to maintain the oxygen content within the exhaust gas stream at the location of the oxygen sensor at a concentration of about 8% v/v.
- 8. The system of claim 1, further comprising:
a combustion air line disposed at the combustion zone at a location proximate the furnace outlet, the combustion air line including an adjustable damper to control an amount of airflow through the combustion air line and into the combustion zone.
- 9. The system of claim 8, wherein the combustion air line includes a curved end extending from a portion of the combustion zone, the adjustable damper of the combustion air line being disposed at the curved end.
- 10. The system of claim 8, wherein the controller communicates with the combustion air line damper to effect opening and closing of the combustion air line damper during system operation.
- 11. The system of claim 1, further comprising:
a canopy duct section including a canopy configured for alignment with the furnace to capture exhaust gas emissions escaping from the furnace, and a canopy duct section coupled with the canopy and the suction unit so as to establish a negative pressure within the canopy and canopy duct section during system operation.
- 12. The system of claim 11, wherein the canopy duct section includes an adjustable damper in communication with the controller, and the controller effects opening and closing of the canopy damper during system operation.
- 13. An electric arc furnace and fume extraction system comprising:
an electric arc furnace including at least one electrode to provide arc heating within the furnace; and the fume extraction system of claim 1, wherein the inlet of the combustion zone is connected with an exhaust outlet of the electric arc furnace.
- 14. A method of extracting and processing fumes generated by a furnace utilizing a fume extraction system connected with the furnace, the method comprising:
(a) establishing a negative pressure within the furnace and portions of the fume extraction system, via a suction unit disposed within the fume extraction system, to withdraw an exhaust gas stream from an outlet of the furnace and through the fume extraction system, the exhaust gas stream including explosive gases that undergo combustion reactions within a combustion zone of the fume extraction system; (b) measuring a concentration of at least one of oxygen, carbon monoxide, hydrogen, carbon dioxide, water and nitrogen within the exhaust gas stream via a gas sensor device disposed at a selected location within the fume extraction system; and (c) automatically modifying the negative pressure within the furnace and portions of the fume extraction system, via a controller, by selectively opening and closing an exhaust damper disposed within the fume extraction system based upon the measured concentration by the gas sensor device.
- 15. The method of claim 14, wherein a plurality of gas concentrations are measured in (b), and the plurality of measured gas concentrations are utilized to selectively open and close the exhaust damper.
- 16. The system of claim 14, wherein the gas sensor device includes an oxygen sensor to measure the concentration of oxygen in the exhaust gas stream.
- 17. The system of claim 16, wherein the oxygen sensor is disposed at a location in the system where a majority of the explosive gases within the exhaust gas stream have already undergone combustion reactions, and (c) includes:
(c.1) selectively opening and closing the exhaust damper, via the controller, to increase or decrease the negative pressure within the furnace and portions of the fume extraction system so as to maintain an oxygen content within the exhaust gas stream at the location of the oxygen sensor within a selected range of concentration values.
- 18. The method of claim 17, wherein the exhaust damper is selectively opened and closed in (c.1) to increase the negative pressure within the furnace and portions of the fume extraction system when the oxygen sensor measures a concentration of oxygen within the exhaust gas stream that is less than about 5% v/v.
- 19. The method of claim 17, wherein the exhaust damper is selectively opened and closed in (c.1) to decrease the negative pressure within the furnace and portions of the fume extraction system when the oxygen sensor measures a concentration of oxygen within the exhaust gas stream that is less than about 10% v/v.
- 20. The method of claim 17, wherein the exhaust damper is selectively opened and closed in (c.1) to increase or decrease the negative pressure within the furnace and portions of the fume extraction system so as to maintain the oxygen content within the exhaust gas stream at the location of the oxygen sensor at a concentration of about 8% v/v.
- 21. The method of claim 14, further comprising:
(d) facilitating the flow of air into the fume extraction system by providing a combustion air line at a location proximate and downstream from the furnace outlet, the combustion air line including an adjustable damper to control the amount of airflow through the combustion air line and into the fume extraction system.
- 22. The method of claim 21, wherein the combustion air line includes a curved end extending from a portion of the combustion zone, the adjustable damper of the combustion air line being disposed at the curved end.
- 23. The method of claim 21, further comprising:
(e) automatically manipulating the combustion air line damper, via the controller, to effect opening and closing of the combustion air line damper.
- 24. The method of claim 14, further comprising:
(d) capturing exhaust gas emissions escaping from the furnace utilizing a canopy disposed proximate the furnace, wherein the canopy is coupled to the suction unit via a canopy duct section to establish a negative pressure within the canopy and canopy duct section.
- 25. The method of claim 24, wherein the canopy duct section includes an adjustable damper, and the method further comprises:
(e) automatically manipulating the canopy damper, via the controller, to effect opening and closing of the canopy damper.
- 26. The method of claim 14, wherein the furnace is an electric arc furnace.
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from U.S. Provisional Patent Application Serial No. 60/398,650, entitled “Methods and Apparatus for Improved Energy Efficient Control of an Electric Furnace Fume Extraction System” and filed Jul. 25, 2002. The disclosure of the above-mentioned provisional application is incorporated herein by reference in its entirety.
Provisional Applications (1)
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Number |
Date |
Country |
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60398650 |
Jul 2002 |
US |