Method of drying lumber

• US 5,852,880 A
• Filed: 05/07/1997
• Issued: 12/29/1998
• Est. Priority Date: 08/01/1996
• Status: Expired due to Fees

• Current Assignee: Jack B. Harrison
• Original Assignee: Jack B. Harrison
• Inventors: Harrison, Jack B.
• Primary Examiner(s): Bennett, Henry A.
• Assistant Examiner(s): WILSON, PAMELA ANNE
• Application Number:
  US08/852,330
• Time in Patent Office: 601 Days
• Field of Search: 34/92, 34/77, 34/212, 34/242, 34/284
• US Class Current: 34/92
• CPC Class Codes: F26B 21/06 Controlling, e.g. regulating, parameters of gas supply F26B21/14 takes precedence; control in general G05
• CPC Class Codes: F26B 2210/16 Wood, e.g. lumber, timber
• CPC Class Codes: F26B 5/00 Drying solid materials or objects by processes not involving the application of heat separating liquids from solids by straining B01D; replacing liquids in wet solids by other liquids, e.g. water by spirit, B01D12/00; drying by electrophoresis B01J
• CPC Class Codes: F26B 5/06 the process involving freezing
• CPC Class Codes: F26B 7/00 Drying solid materials or objects by processes using a combination of processes not covered by a single one of groups F26B3/00 and F26B5/00 F26B1/005, F26B5/04, F26B23/026 take precedence

Abstract

A method for drying wood by placing the wood in a dehydration chamber in which the temperature, humidity and pressure are controlled. Air and or gasses are circulated in the chamber to wick away moisture while the wood remains frozen. Both the internal temperature and the circulating air are kept below freezing during the drying process. Atmospheric pressure is manipulated to enhance drying and may be either increased or reduced. Exposure to the volume of dry air (air with zero percent humidity) varies with the drying process and depends on the species, the quantity of wood to be dried and the initial moisture content of the material.

Claims

1. A method of drying wood, having a moisture content comprising the steps of:

a) placing a plurality of lengths of frozen wood into a drying chamber, having an air pressure therein;

b) sealing the drying chamber;

c) reducing the air pressure within the drying chamber to a partial vacuum;

d) extracting moist air from the drying chamber; and

e) repeating step (d) until the moisture content of the plurality of lengths of wood reaches a desired level.

2. The method of drying wood of claim 1 further comprising the steps of:

applying formaldehyde and sulfur dioxide gasses into the drying chamber, after the plurality of lengths of frozen wood have reached a desired moisture content, to enable cross linking wood fiber molecules within the plurality of lengths of frozen wood.

3. The method of drying wood of claim 1 wherein the partial vacuum is kept at about -16 mm of mercury.

4. The method of drying wood of claim 1 wherein the plurality of lengths of frozen wood are kept at a temperature Of about 30°

F.

5. The method of drying wood of claim 1 wherein the plurality of lengths of frozen wood are kept at a temperature of between 0°

F. and -300°

F.

6. The method of claim 5 wherein after the temperature of the plurality of lengths of frozen wood is brought down from 0°

F. to -300°

F. over a twenty hour period following a linear rate of decent.

7. The method of claim 5 wherein after the temperature of the plurality of lengths of frozen wood is brought down from 0°

F. to -300°

F. over a twenty hour period following a linear rate of decent, the temperature of the plurality of lengths of frozen wood is brought up from -300°

F. to 0°

F. over a twenty hour period following a linear rate of ascent.

8. The method of claim 1 wherein the plurality of lengths of frozen wood are hard wood.