US3909953A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Paint drying method and apparatus
Assignee: Surface Combustion Corp
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Filing: 1974-02-28
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Granted: 1975-10-07
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Expires: 1994-02-28
Abstract
Abstract A high-efficiency system for drying solvent-based paint coatings on articles, with minimum fuel requirements and pollution-free emissions, comprises a paint drying oven in which the painted article is dried in a heated atmosphere which is maintained substantially oxygen-free or inert so as to be above the upper explosion limit at all times during the drying process. The combustible solvent vapors which evaporate from the paint coating during the drying process and are contained in the flue gases exhausted from the oven are conveyed into and incinerated under stoichiometric conditions in a rich fume incinerator, containing auxiliary gas-air pilot burners also operating under stoichiometric conditions, to produce substantially oxygen-free nonpolluting inert gaseous combustion products at least a part of which, after cooling in a heat exchanger for heat recovery purposes, is recycled back into the drying oven to supply thereto all or part of the heat required for the paint drying process as well as the essentially inert gas atmosphere required therein. The unused portion of the incinerator combustion products may be vented directly to the atmosphere as nonpolluting emissions.
Inventors
- 👤 Klaus H Hemsath
- 👤 Arvind C Thekdi
- 👤 Frank J Vereecke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:57
CPC Classifications
F; F26; F26B; F26B13/00; F26B13/10; F23; F23G; F23G7/00; F23G7/06; F23G7/061; F23G7/065; F26B23/00; F26B23/02; F26B23/022; Y; Y02; Y02P; Y02P70/00; Y02P70/10
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
464 words
A method for drying solvent-based coatings on articles moving through a drying chamber by means of exhaust gases coming from a combustion apparatus having an intake in fluid communication with a gaseous exhaust duct in said drying chamber whereby a furnace atmosphere generated within said drying chamber is drawn into said combustion apparatus, said method comprising the steps of: injecting combustion air into said combustion apparatus at a fixed rate sufficient to mix stoichiometrically with said furnace atmosphere drawn from said exhaust duct when said drying chamber is operating under constant load; initially mixing, during startup, a gaseous fuel from an auxiliary burner in stoichiometric proportions with said combustion air; igniting said gaseous fuel and said combustion air in said combustion apparatus by means of at least one pilot burner to produce an inert type gas mixture possessing not more than five percent oxygen by content; circulating at least a portion of said inert gas mixture leaving said combustion apparatus through a heat exchange mechanism to cool same to a predetermined value; piping at least a portion of said inert gas mixture leaving said cooling mechanism into said drying chamber to purge same; introducing said articles through an article inlet end into said drying chamber to produce a furnace atmosphere containing solvent emissions and removing said articles through an article outlet end of said chamber; continuously removing a first portion of said furnace atmosphere through said exhaust duct and burning said removed solvents in said combustion apparatus to continuously produce an inert type off-gas; sensing the temperature of said off-gas to regulate the flow of fuel to said auxiliary burner to insure that said off-gas possesses no more than five percent oxygen by content; circulating a portion of said off-gas through said heat exchange mechanism to cool same to a predetermined temperature; introducing a portion of said cooled off-gas to said drying chamber to insure that said furnace atmosphere is outside the explosive range; exhausting a second portion of said furnace atmosphere from said drying chamber through a vent; recirculating said second portion of said furnace atmosphere into said drying chamber after mixing same with said portion of inert type off-gas being circulated into said drying chamber; controlling the flow of said off-gas to produce a slight overpressure in said drying chamber; circulating a portion of said inert type off-gas downstream from said heat exchange mechanism into a plenum arrangement at said article inlet end and said article outlet end; and ejecting said inert type gas mixture from said plenum arrangement in a plurality of gaseous streams directed generally normal to the flow of said articles at a pressure sufficient to establish gas flow patterns through said article inlet and outlet ends whereby said overpressure is maintained and said furnace atmosphere is substantially sealed.
Claim 2
Independent Claim
464 words
A method for drying solvent-based coatings on articles moving through a drying chamber by means of exhaust gases coming from a combustion apparatus having an intake in fluid communication with a gaseous exhaust duct in said drying chamber whereby a furnace atmosphere generated within said drying chamber is drawn into said combustion apparatus, said method comprising the steps of: injecting combustion air into said combustion apparatus at a fixed rate sufficient to mix stoichiometrically with said furnace atmosphere drawn from said exhaust duct when said drying chamber is operating under constant load; initially mixing, during startup, a gaseous fuel from an auxiliary burner in stoichiometric proportions with said combustion air; igniting said gaseous fuel and said combustion air in said combustion apparatus by means of at least one pilot burner to produce an inert type gas mixture possessing not more than five percent oxygen by content; circulating at least a portion of said inert gas mixture leaving said combustion apparatus through a heat exchange mechanism to cool same to a predetermined value; piping at least a portion of said inert gas mixture leaving said cooling mechanism into said drying chamber to purge same; introducing said articles through an article inlet end into said drying chamber to produce a furnace atmosphere containing solvent emissions and removing said articles through an article outlet end of said chamber; continuously removing a first portion of said furnace atmosphere through said exhaust duct and burning said removed solvents in said combustion apparatus to continuously produce an inert type off-gas; sensing the temperature of said off-gas to regulate the flow of fuel to said auxiliary burner to insure that said off-gas possesses no more than five percent oxygen by content; circulating a portion of said off-gas through said heat exchange mechanism to cool same to a predetermined temperature; introducing a portion of said cooled off-gas to said drying chamber to insure that said furnace atmosphere is outside the explosive range; exhausting a second portion of said furnace atmosphere from said drying chamber through a vent; recirculating said second portion of said furnace atmosphere into said drying chamber after mixing same with said portion of inert type off-gas being circulated into said drying chamber; controlling the flow of said off-gas to produce a slight overpressure in said drying chamber; circulating a portion of said inert type off-gas downstream from said heat exchange mechanism into a plenum arrangement at said article inlet end and said article outlet end; and ejecting said inert type gas mixture from said plenum arrangement in a plurality of gaseous streams directed generally normal to the flow of said articles at a pressure sufficient to establish gas flow patterns through said article inlet and outlet ends whereby said overpressure is maintained and said furnace atmosphere is substantially sealed.
Claim 3
Dependent Claim
494 words
Apparatus for drying solvent-based coatings on articles, said apparatus comprising: a drying oven having a drying chamber, an article inlet opening, an article outlet opening, a gaseous inlet opening for injecting a furnace type gaseous atmosphere into said oven, an exhaust outlet opening for removing a first portion of the furnace atmosphere, and a vent for removing a second portion of the furnace atmosphere; combustion means in fluid communication with said gaseous exhaust outlet for burning furnace fumes exiting therefrom to produce an inert type off-gas mixture which contains not more than five percent oxygen by content; said combustion means including combustion air supply means preset to deliver a fixed quantity of combustion air to said combustion means to achieve approximately stoichiometric combustion when said apparatus is operated under constant load, pilot burner means to ignite said combustion air with said exhaust furnace fumes to produce said inert type off-gas mixture, auxiliary fuel means effective during startup of said apparatus to mix with said combustion air in said combustion means to produce an inert type off-gas suitable for purging said drying chamber and effective during normal operation of said apparatus to control said oxygen content within said five percent limit in said inert off-gas mixture, and temperature control means associated with said combustion means for controlling the fuel quantity supplied said combustion means by said auxiliary fuel means; recycle conduit means for recycling at least a portion of said inert gas mixture from said combustioN means to said gaseous inlet opening in said drying chamber; said recycling means including a heat transfer mechanism for reducing the temperature of said inert off-gas mixture to a predetermined value, first conduit means upstream of said heat transfer mechanism for venting a portion of said inert off-gas mixture directly to the atmosphere as nonpolluting emissions, second conduit means in fluid communication with said gaseous inlet of said drying chamber for conveying and mixing a second portion of said inert type off-gas mixture with the solvents emitted from said coatings to produce a furnace gas atmosphere which is above the upper explosive limits of said atmosphere at all times during the drying the said coatings; recirculating means including a third conduit in fluid communication with said vent for circulating a second portion of said furnace atmosphere with said inert type gaseous mixture whereby the heat sensibility of the furnace mixture is conserved and temperature uniformity of the furnace atmosphere is promoted; pressure means for maintaining said drying chamber at a slight overpressure; aerodynamic sealing means at said article inlet opening and said article outlet opening directing a plurality of streams of said inert type off-gas mixture in a direction generally normal to all surfaces of said articles at a flow rate sufficient to establish gas flow into said drying chamber to maintain said drying chamber substantially sealed from the outside atmosphere; and said recycling means including a fourth conduit supplying said inert gas mixture to said aerodynamic seal means.
Claim 4
Dependent Claim
494 words
Apparatus for drying solvent-based coatings on articles, said apparatus comprising: a drying oven having a drying chamber, an article inlet opening, an article outlet opening, a gaseous inlet opening for injecting a furnace type gaseous atmosphere into said oven, an exhaust outlet opening for removing a first portion of the furnace atmosphere, and a vent for removing a second portion of the furnace atmosphere; combustion means in fluid communication with said gaseous exhaust outlet for burning furnace fumes exiting therefrom to produce an inert type off-gas mixture which contains not more than five percent oxygen by content; said combustion means including combustion air supply means preset to deliver a fixed quantity of combustion air to said combustion means to achieve approximately stoichiometric combustion when said apparatus is operated under constant load, pilot burner means to ignite said combustion air with said exhaust furnace fumes to produce said inert type off-gas mixture, auxiliary fuel means effective during startup of said apparatus to mix with said combustion air in said combustion means to produce an inert type off-gas suitable for purging said drying chamber and effective during normal operation of said apparatus to control said oxygen content within said five percent limit in said inert off-gas mixture, and temperature control means associated with said combustion means for controlling the fuel quantity supplied said combustion means by said auxiliary fuel means; recycle conduit means for recycling at least a portion of said inert gas mixture from said combustioN means to said gaseous inlet opening in said drying chamber; said recycling means including a heat transfer mechanism for reducing the temperature of said inert off-gas mixture to a predetermined value, first conduit means upstream of said heat transfer mechanism for venting a portion of said inert off-gas mixture directly to the atmosphere as nonpolluting emissions, second conduit means in fluid communication with said gaseous inlet of said drying chamber for conveying and mixing a second portion of said inert type off-gas mixture with the solvents emitted from said coatings to produce a furnace gas atmosphere which is above the upper explosive limits of said atmosphere at all times during the drying the said coatings; recirculating means including a third conduit in fluid communication with said vent for circulating a second portion of said furnace atmosphere with said inert type gaseous mixture whereby the heat sensibility of the furnace mixture is conserved and temperature uniformity of the furnace atmosphere is promoted; pressure means for maintaining said drying chamber at a slight overpressure; aerodynamic sealing means at said article inlet opening and said article outlet opening directing a plurality of streams of said inert type off-gas mixture in a direction generally normal to all surfaces of said articles at a flow rate sufficient to establish gas flow into said drying chamber to maintain said drying chamber substantially sealed from the outside atmosphere; and said recycling means including a fourth conduit supplying said inert gas mixture to said aerodynamic seal means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-06 | 1979-04-07 | 1979-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-06 | 1983-04-07 | 1983-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-06 | 1987-04-07 | 1987-10-07 | $7700.00 | Window Closed / Lapsed |