Web dryer with fully integrated regenerative heat source and control thereof

• US 20020092198A1
• Filed: 01/12/2001
• Published: 07/18/2002
• Est. Priority Date: 01/12/2001
• Status: Active Grant

• Current Assignee: Babcock & Wilcox Megtec LLC (Durr AG)
• Original Assignee: Megtec Systems Incorporated (Durr AG)
• Inventors: Bria, Michael P., Fiers, Alan D., Ruhl, Andreas C.H.
• Granted Patent: US 6,651,357 B2
• Time in Patent Office: Days
• US Class Current: 34/444
• CPC Class Codes: F23G 7/068 using regenerative heat recovery means
• CPC Class Codes: F26B 13/104 supported by fluid jets only; Fluid blowing arrangements for flotation dryers, e.g. coanda nozzles
• CPC Class Codes: F26B 23/022 incinerating volatiles in the dryer exhaust gases, the produced hot gases being wholly, partly or not recycled into the drying enclosure

Abstract

Integrated web dryer and regenerative heat exchanger, as well as a method of drying a web of material using the same. The apparatus and method of the present invention provides for the heating of air and the converting of VOCs to harmless gases in a fully integrated manner via the inclusion of a regenerative combustion device as an integral element of the drying apparatus.

Claims

1. A dryer for a web of material and having an integrated regenerative heat source, comprising:

a housing enclosure comprising;

a web inlet and a web outlet spaced from said web inlet;

a plurality of nozzles for drying said web;

a regenerative heat source comprising at least one heat exchange column, said at least one column having a gas inlet and a gas outlet, said at least one column being in communication with a combustion zone, and containing heat exchange material;

valve means for alternatingly directing gas from said dryer into said inlet of said at least one heat exchange column; and

a mixing chamber in communication with said combustion zone and said housing enclosure, said mixing chamber receiving make-up air from outside said dryer enclosure and mixing said make-up air with air from said combustion zone.

2. The dryer of claim 1, wherein there are at least two heat exchange columns.

3. The dryer of claim 1 or 2, wherein at least some of said plurality of nozzles are flotation nozzles for floatingly supporting said web in said housing enclosure

4. The dryer of claim 1 or 2, wherein said heat exchange material is a combination of randomly packed media and structured media.

5. The dryer of claim 1 or 2, wherein said heat exchange material is a monolith.

6. The dryer of claim 1 or 2, further comprising an entrapment chamber having an inlet in communication with said valve means.

7. The dryer of claim 1 or 2, further comprising means for introducing a combustible fuel into said at least one heat exchange column.

8. The dryer of claim 1 or 2, wherein said heat exchange material comprises a catalyst.

9. The dryer of claim 1 or 2, wherein said heat exchange column has a first end and a second end spaced from said first end, said second end being nearer to said combustion zone than said first end;

and said heat exchange material in said heat exchange column is arranged in said heat exchange column such that at least a portion of said material nearer said second end is inclined with respect to horizontal.

10. The dryer of claim 9, wherein said portion of said heat exchange material nearer said second end is inclined at an angle greater than the angle at which said heat exchange material nearer said first end is inclined.

11. The dryer of claim 9, wherein said angle at which said heat exchange material nearer said first end is inclined is 0°

, and said angle at which said heat exchange material nearer said second end is inclined is 1 to 10°

.

12. The dryer of claim 9, wherein said angle at which said heat exchange material nearer said second end is inclined is 1.6°

.

13. The dryer of claim 1, further comprising temperature sensing means in said regenerative heat source, and bypass means responsive thereto for extracting a portion of gases from said regenerative heat source when said temperature sensing means senses a predetermined temperature.

14. The dryer of claim 1, further comprising a sensor for sensing the concentration of volatile organic solvent of said gas directed into said inlet.

15. The dryer of claim 7, further comprising a sensor for sensing the concentration of volatile organic solvent of said gas directed into said inlet, and wherein the amount of said combustible fuel introduced is responsive to the sensed concentration.

16. The dryer of claim 1, wherein said heat exchange material comprises plurality of plates positioned between a first stack of monolithic blocks at a first end of said heat exchange column and a second stack of monolithic blocks at a second end of said heat exchange column.

17. The dryer of claim 1, further comprising damper means associated with said combustion zone and said mixing chamber for controlling the amount of gas that flows from said combustion zone to said mixing chamber.

18. The dryer of claim 17, wherein said damper means comprises a housing, a blade and a shaft.

19. The dryer of claim 17, wherein said damper means is made of superalloy materials.

20. A method of drying a running web of material, comprising:

transporting said web into a dryer enclosure having a dryer atmosphere;

impinging heated air onto said web with a plurality of nozzles;

drawing a portion of said dryer atmosphere into an integrated regenerative heat exchanger comprising at least one heat exchange column containing heat exchange material and in communication with a combustion zone in order to heat said portion of said dryer atmosphere;

combusting in said integrated regenerative heat exchanger volatile contaminants present in said dryer atmosphere; and

directing a portion of the combusted gas from said combustion zone to a mixing chamber in communication with said dryer enclosure;

introducing make-up air from outside said dryer enclosure into said mixing chamber;

mixing said make-up air with said portion of the combusted gas in said mixing chamber; and

directing said mixture to one or more of said plurality of nozzles.