US3882612A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for limiting the concentration of combustible volatiles in dryer emissions
Assignee: Coe Manufacturing Co
•
Filing: 1973-07-27
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Granted: 1975-05-13
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Expires: 1993-07-27
Abstract
Abstract Method and apparatus for limiting the concentration of combustible volatiles in the stack gases of a recirculating dryer adapted for treating materials containing such volatiles. A portion of the recirculating drying gases is directed through a heater duct interposed between the drying gas inlet and outlet ports of the drying chamber, such heater duct including a high temperature heat source for heating such gas portion to the combustion temperature of the entrained volatiles to incinerate them. Another portion of the recirculating drying gases bypasses the heater duct and is mixed with the heated gases at the discharge end of the heater duct, thereby forming a gas mixture suitable for introduction into the drying chamber having a temperature substantially lower than that imposed upon the gases in the heater duct. The length of the heater duct in a direction downstream from the high temperature heat source is sufficient to maintain the gases in the duct at or above the combustion temperature of the volatiles for a dwell period sufficient to permit the complete combustion of the volatiles prior to the mixing of the two gas streams. A temperature sensor monitors the temperature of the gases in the heater duct, and power-actuated adjustable dampers located at the entrance to the duct automatically decrease the flow rate of the drying gases through the duct if the temperature drops below that necessary to support combustion of the volatiles. Another temperature sensor monitors the temperature of the gas mixture introduced into the drying chamber, and a controller automatically responsive to the latter temperature modulates the energy output from the heat source so as to maintain the temperature of the gas mixture within a predetermined operating range. The concentration of volatiles in the stack gases is dependent upon the volumetric flow rate of that portion of the recirculating gases passing through the heater duct and its relation to the volumetric flow rate of the stack gases.
Inventors
- 👤 Robert W Try
- 👤 David W Campbell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:25
CPC Classifications
F; F26; F26B; F26B21/00; F26B21/30; F26B21/35; F26B21/20; F26B23/00; F26B23/02; F26B23/022
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
314 words
A dryer for drying materials containing combustible volatiles by the recirculation of heated drying gases through a chamber containing said materials, said dryer having a system for both heating said drying gases to a predetermined operating temperature range suitable for drying said materials and simultaneously incinerating a portion of said combustible volatiles drawn from said materials during drying so as to limit the concentration of said volatiles in the stack gases emitted from said dryer, said dryer comprising: a. heater duct means for accepting a portion, less than all, of said drying gases from said drying chamber after said gases have been passed over said materials, said heater duct including means for heating said portion of said gases at least to a predetermined minimum required combustion temperature of said volatiles, said combustion temperature being substantially greater than said predetermined operating temperature range, and further including means for supplying at least the majority of the heat requirement of all of said drying gases; b. bypass duct means for accepting a separate portion of said drying gases from said drying chamber; c. means for intermixing said respective portions of said drying gases emitted from said respective duct means and for conducting the resultant mixture of said drying gases through said drying chamber for passage over said materIals; d. means automatically responsive to the temperature of said resultant mixture of drying gases for modulating the heat output from said heating means so as to maintain the temperature of said resultant mixture within said predetermined operating temperature range; and e. variable gas flow modulating means automatically responsive to the temperature of said gases within said heater duct means for decreasing the volumetric flow rate of said portion of said gases passing through said heater duct means whenever the temperature of said gases within said heater duct means falls below said predetermined minimum required combustion temperature of said volatiles.
Claim 2
Dependent Claim
314 words
A dryer for drying materials containing combustible volatiles by the recirculation of heated drying gases through a chamber containing said materials, said dryer having a system for both heating said drying gases to a predetermined operating temperature range suitable for drying said materials and simultaneously incinerating a portion of said combustible volatiles drawn from said materials during drying so as to limit the concentration of said volatiles in the stack gases emitted from said dryer, said dryer comprising: a. heater duct means for accepting a portion, less than all, of said drying gases from said drying chamber after said gases have been passed over said materials, said heater duct including means for heating said portion of said gases at least to a predetermined minimum required combustion temperature of said volatiles, said combustion temperature being substantially greater than said predetermined operating temperature range, and further including means for supplying at least the majority of the heat requirement of all of said drying gases; b. bypass duct means for accepting a separate portion of said drying gases from said drying chamber; c. means for intermixing said respective portions of said drying gases emitted from said respective duct means and for conducting the resultant mixture of said drying gases through said drying chamber for passage over said materIals; d. means automatically responsive to the temperature of said resultant mixture of drying gases for modulating the heat output from said heating means so as to maintain the temperature of said resultant mixture within said predetermined operating temperature range; and e. variable gas flow modulating means automatically responsive to the temperature of said gases within said heater duct means for decreasing the volumetric flow rate of said portion of said gases passing through said heater duct means whenever the temperature of said gases within said heater duct means falls below said predetermined minimum required combustion temperature of said volatiles.
Claim 3
Dependent Claim
40 words
The dryer of claim 1 wherein said intermixing means (c) includes baffle means located in advance of said drying chamber for inducing turbulence into said respetive joined gas portions and thereby promoting the mixing of said portions with one another.
Claim 4
Dependent Claim
27 words
The dryer of claim 2 including adjustable means for movably mounting said baffle means so as to permit variable adjustment of the position of said baffle means.
Claim 5
Dependent Claim
110 words
The dryer of claim 1 wherein said respective heater and bypass duct means comprise an open-ended heater duct mounted within and colinear with a bypass duct having a substantially larger cross-section than said heater duct, said heater duct being mounted substantially equidistant from the side walls of said bypass duct so as to define passageways along either side of said heater duct, said variable gas flow modulating means comprising a pair of power actuated movable dampers mounted on either side of the entrance of said heater duct for regulating the respective flow proportions of the drying gases through said heater duct and around the sides of said heater duct respectively.
Claim 6
Dependent Claim
42 words
The dryer of claim 4 including a second pair of movable dampers mounted upstream of said pair of power actuated dampers on either side of said bypass duct for balancing the volumetric flow of gases approaching said pair of power actuated dampers.
Claim 7
Dependent Claim
59 words
The dryer of claim 1 including back-up temperature sensor means for measuring the temperature of said gases within said heater duct means, and means automatically responsive to said back-up temperature sensing means for automatically decreasing the heat output from said heating means whenever the temperature of said gases in said heater duct means rises above a predetermined maximum temperature.
Claim 8
Dependent Claim
297 words
A dryer for drying materials containing combustible volatiles by the recirculation of heated drying gases through a chamber containing said materials, said dryer having a system for both heating said drying gases to a predetermined operating temperature range suitable for drying said materials and simultaneously incinerating a portion of said combustible volatiles drawn from said materials during drying so as to limit the concentration of said volatiles in the stack gases emitted from said dryer, said dryer comprising: a. heater duct means for accepting a portion, less than all, of said drying gases from said drying chamber after said gases have been passed over said materials, said heater duct including means for heating said portion of said gases at least to a predetermined minimum combustion temperature of said volatiles, said combustion temperature being substantially greater than said predetermined operating temperature range, and further including means for supplying at least the majority of the heat requirement of all of said drying gases; b. bypass duct means for accepting a separate portion of said drying gases from said drying chamber; c. means for intermixing said respective portions of said drying gases emitted from said respective duct means and for conducting the resultant mixture of said drying gases through said drying chamber for passage over said materials; and d. regulating means automatically responsive both to the temperature of said resultant mixture of drying gases and to the temperature of said gases within said heater duct means for Variably modulating the heat supplied from said heater duct means to said resultant mixture so as to maintain said resultant mixture within said predetermined operating temperature range while simultaneously maintaining said gases within said heater duct means at least at said predetermined minimum combustion temperature regardless of said modulation of said heat supply.
Claim 9
Dependent Claim
297 words
A dryer for drying materials containing combustible volatiles by the recirculation of heated drying gases through a chamber containing said materials, said dryer having a system for both heating said drying gases to a predetermined operating temperature range suitable for drying said materials and simultaneously incinerating a portion of said combustible volatiles drawn from said materials during drying so as to limit the concentration of said volatiles in the stack gases emitted from said dryer, said dryer comprising: a. heater duct means for accepting a portion, less than all, of said drying gases from said drying chamber after said gases have been passed over said materials, said heater duct including means for heating said portion of said gases at least to a predetermined minimum combustion temperature of said volatiles, said combustion temperature being substantially greater than said predetermined operating temperature range, and further including means for supplying at least the majority of the heat requirement of all of said drying gases; b. bypass duct means for accepting a separate portion of said drying gases from said drying chamber; c. means for intermixing said respective portions of said drying gases emitted from said respective duct means and for conducting the resultant mixture of said drying gases through said drying chamber for passage over said materials; and d. regulating means automatically responsive both to the temperature of said resultant mixture of drying gases and to the temperature of said gases within said heater duct means for Variably modulating the heat supplied from said heater duct means to said resultant mixture so as to maintain said resultant mixture within said predetermined operating temperature range while simultaneously maintaining said gases within said heater duct means at least at said predetermined minimum combustion temperature regardless of said modulation of said heat supply.
Claim 10
Dependent Claim
138 words
The dryer of claim 7 wherein said regulating means (d) comprises temperature sensor means for measuring the operating temperature of said resultant mixture of drying gases, means automatically responsive to said temperature sensor means for increasing the heat output from said heater duct means whenever said operating temperature falls below a predetermined temperature and decreasing said heat output whenever said operating temperature rises above a predetermined temperature, second temperature sensor means for measuring the temperature of said gases within said heater duct means, and variable gas flow modulating means automatically responsive to said second temperature sensor means for decreasing the volumetric flow rate of said portion of said drying gases passing through said heater duct means in response to a decrease in the temperature of said gases in said heater duct means below said predetermined minimum combustion temperature.
Claim 11
Dependent Claim
40 words
The dryer of claim 8 wherein said intermixing means (c) includes baffle means located in advance of said drying chamber for inducing turbulence into the respective joined gas portions and thereby promoting the mixture of said portions with one another.
Claim 12
Dependent Claim
27 words
The dryer of claim 9 including adjustable means for movably mounting said baffle means so as to permit variable adjustment of the position of said baffle means.
Claim 13
Dependent Claim
110 words
The dryer of claim 8 wherein said respective heater and bypass duct means comprise an open-ended heater duct mounted within and colinear with a bypass duct having a substantially larger cross-section than said heater duct, said heater duct being mounted substantially equidistant from the side walls of said bypass duct so as to define passageways along either side of said heater duct, said variable gas flow modulating means comprising a pair of power actuated movable dampers mounted on either side of the entrance of said heater duct for regulating the respective flow proportions of the drying gases through said heater duct and around the sides of said heater duct respectively.
Claim 14
Dependent Claim
42 words
The dryer of claim 11 including a second pair of movable dampers mounted upstream of said pair of power actuated dampers on either side of said larger duct for balancing the volumetric flow of gases approaching said pair of power actuated dampers.
Claim 15
Dependent Claim
59 words
The dryer of claim 8 including back-up temperature sensing means for measuring the tempertaure of said gases within said heater duct means, and means automatically responsive to said back-up temperature sensing means for automatically decreasing the heat output from said heater duct means whenever the temperature of said gases in said heater duct means rises above a predetermined temperature.
Claim 16
Independent Claim
170 words
A method of drying materials containing combustible volatiles which comprises: a. recirculating heated drying gases over said materials at a predetermined operating temperature range suitable for drying said materials; b. during siad recirculation of said drying gases heating a portion, less than all, of said recirculating drying gases to a predetermined minimum combustion temperature of said volatiles and burning at least a portion of said volatiles, thereby also supplying at least the majority of the heat requirement of all said drying gases; c. mixing a separate portion of said recirculating drying gases with said portion of gases heated pursuant to step (b) to form a gas mixture having a temperature lower than that of said heated gases alone; and d variably modulating the heat supplied to said gas mixture in step (b) so as to maintain said resultant mixture within said predetermined operatinG temperature range while simultaneously maintaining said gases heated in step (b) at least at said predetermined minimum combustion temperature regardless of said modulation of said heat supply.
Claim 17
Independent Claim
170 words
A method of drying materials containing combustible volatiles which comprises: a. recirculating heated drying gases over said materials at a predetermined operating temperature range suitable for drying said materials; b. during siad recirculation of said drying gases heating a portion, less than all, of said recirculating drying gases to a predetermined minimum combustion temperature of said volatiles and burning at least a portion of said volatiles, thereby also supplying at least the majority of the heat requirement of all said drying gases; c. mixing a separate portion of said recirculating drying gases with said portion of gases heated pursuant to step (b) to form a gas mixture having a temperature lower than that of said heated gases alone; and d variably modulating the heat supplied to said gas mixture in step (b) so as to maintain said resultant mixture within said predetermined operatinG temperature range while simultaneously maintaining said gases heated in step (b) at least at said predetermined minimum combustion temperature regardless of said modulation of said heat supply.
Claim 18
Dependent Claim
97 words
The method of claim 14 wherein said modulating step (d) comprises automatically increasing the rate at which heat is supplied in step (b) in response to the temperature of said gas mixture falling below a predetermined temperature and decreasing said rate of heat supply automatically in response to said temperature of said gas mixture rising above a predetermined temperature, and automatically decreasing the volumetric flow rate of said portion of gases heated in step (b) in response to any decrease in the temperature of said gases heated in step (b) below said combustion temperature of said volatiles.
Claim 19
Dependent Claim
57 words
The method of claim 14 wherein said step (b) includes maintaining the temperature of said portion of said recirculated drying gases heated in step (b) at least at said minimum combustion temperature for a sufficient period of time before mixing said heated gas portion with said other gas portion to insure completion of combustion of said volatiles.
Claim 20
Dependent Claim
91 words
The method of claim 14 including the further step of emitting a portion of said gas mixture into the atmosphere as stack gases after said gases have been recirculated over said materials, selecting a fraction X of the normal concentration of said volatiles in said stack gases to which said concentration of volatiles is to be reduced, and causing the volumetric flow rate of said portion of gases heated in step (b) to be substantially at least (1-X)/X times the volumetric flow rate of said stack gases emitted to the atmosphere.
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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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |