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US3757427A Expired / Lapsed US ⏱️ 0.0 years remaining

Method and apparatus for drying solvents

Assignee: B&K Machinery International Ltd
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Filing: 1971-10-06
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Granted: 1973-09-11
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Expires: 1991-10-06
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Abstract

Abstract A method of drying a solvent type coating on a surface, by heating the coating within an oven by a hot gaseous medium and in which the gases within the oven are continuously exhausted, and the effluent gases leaving the oven are then separated into two streams, namely, a recycle stream and an oxidation stream, and in which the oxidation stream is then passed through an oxidizer where the solvent vapours in the oxidation stream are then oxidized by burning or by catalytic action. The recycle stream of untreated effluent gases is then recycled directly into the oven once more without passing through the oxidizer at all. The combustion gases leaving the oxidizer are then separated into two streams, and one stream is vented to atmosphere. The other stream, namely a return stream, is then passed into the oven again together with the recycle stream of unburnt effluent gases. Sufficient fresh air is drawn into the system, preferably through a heat exchanger heated by the waste combustion gases, and such additional make-up air is then passed directly into the oven, where it mixes with the incoming return stream of combustion gases, and the incoming recycle stream of unburnt effluent gases to maintain the desired process temperature. The specification also discloses apparatus suitable for the practising of the method.

Inventors

  • 👤 D Wilkinson

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-30 07:59
CPC Classifications
B; B05; B05D; B05D3/00; B05D3/04

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 83 words
The method of drying a solvent type coating as claimed in claim 1, wherein said gaseous drying medium comprises a mixture of gases consisting of between about seventy and eighty percent of said recycled effluent gases at a temperature slightly below said predetermined process range, and the balance of between 30 and 20 percent of said gaseous drying medium comprising a mixture of between about 5 and 55 percent of said oxidation products, and between about 95 and 45 percent of fresh air.
Claim 2
Dependent Claim 44 words
The method of drying a solvent type coating as claimed in claim 1, wherein said gaseous effluent withdrawn from said oven contains entrained vaporized solvent in a concentration of between 25 and 40 percent of the lower explosive limit of concentration of said solvent.
Claim 3
Dependent Claim 49 words
The method of drying a solvent type coating as claimed in claim 1, wherein said oxidation stream of effluent gases is oxidized by passing the same through a burner means to raise the temperature therein to at least the auto-ignition temperature of said vaporized solvent in said oxidation stream.
Claim 4
Dependent Claim 37 words
The method of drying a solvent type coating as claimed in claim 1 including the step of pre-heating said fresh air, by passing the same through a heat exchanger, heated by said waste stream of oxidation gases.
Claim 5
Dependent Claim 373 words
Oven drying apparatus for the continuous evaporation of a solvent type coating composition after application thereof to a workpiece, having two sides and oxidation of such solvents prior to venting the same to atmosphere and comprising; drying oven means; means for moving said coated workpiece continuously through said oven means; inlet fan means for forcing large volumes of a gaseous drying medium into said oven at an elevated temperature within a desired processing range; discharge means having a plurality of outlets spaced from one another for flowing said gaseous drying medium directly onto said workpiece from both sides thereof and procuring turbulent flow over the surfaces thereof, whereby to ensure efficient transfer of heat thereto and evaporation and entrainment of said solvent into said gaseous medium; an exhaust outlet for continuously removing a gaseous effluent, from said oven, comprising said gaseous drying medium and said entrained solvent; a recycle duct connected directly between said exhaust outlet and said inlet fan means whereby said inlet fan means continuously forces said effluent back through said oven; oxidation duct means connected to said recycle duct and said exhaust outlet for receiving a portion of said effluent gases therefrom; fan means in said oxidation duct means for forcibly withdrawing said portion of said effluent gases from said exhaust outlet; oxidation chamber means connected to said oxidation duct means, and adapted to elevate said portion of said effluent gases to a higher temperature in the presence of sufficient free oxygen to support said oxidation sufficient to oxidize said solvents entrained therein, said oxidation chamber and said recycle duct being so arranged that the temperature of the effluent gases in said recycle duct remains substantially unchanged during recycling; return duct means connected to said chamber for returning a portion of said oxidized gaseous product to said inlet fan means; waste duct means connected to said chamber for conducting the balance of said oxidized gases therefrom and venting the same to atmosphere; air intake means for conducting air to said inlet fan means, and, gas analyser means communicating with said oxidation duct means for continuously analysing said effluent gases from said oven prior to entry into said oxidation chamber whereby to determine the proportion of solvent in said effluent gases.
Claim 6
Dependent Claim 35 words
The apparatus As claimed in claim 6 including heat exchanger means connected with said air intake means, and heated by said waste oxidation gases, and adapted to elevate the temperature of said incoming fresh air.
Claim 7
Dependent Claim 36 words
The apparatus as claimed in claim 6 wherein said oxidation chamber means, is heated by natural gas burner means, and including temperature sensing means, monitoring the temperature of said oxidation gases after passing through said chamber.

References Cited (Backward Citations)

US2743529A Cited
US2795054A Cited
US3314159A Cited
US3514085A Cited
US3604824A Cited
US3675600A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1976-09-10 1977-03-12 1977-09-11 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1980-09-10 1981-03-12 1981-09-11 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1984-09-10 1985-03-12 1985-09-11 $7700.00 Window Closed / Lapsed

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