Lumber drying apparatus

• US 3,902,253 A
• Filed: 01/16/1974
• Issued: 09/02/1975
• Est. Priority Date: 01/17/1973
• Status: Expired due to Term

• Current Assignee: Masayuki Kato, Takeshi Sabuzawa, Teruji Muraki, Toshiyuki Suzuki
• Original Assignee: Masayuki Kato, Takeshi Sabuzawa, Teruji Muraki, Toshiyuki Suzuki
• Inventors: Suzuki, Toshiyuki, Sabuzawa, Takeshi, Kato, Masayuki, Muraki, Teruji
• Primary Examiner(s): Dority, Jr., Carroll B.
• Assistant Examiner(s): Schwartz, Larry I.
• Application Number:
  US05/433,888
• Time in Patent Office: 594 Days
• Field of Search: 34/215,216,217,210,212,1,77,78,DIG.19,DIG.21,218,219,242 432/250 160/184 432/8,54 55/32
• US Class Current: 34/256
• CPC Class Codes: F26B 15/12 the lines being all horizontal or slightly inclined
• CPC Class Codes: F26B 21/02 Circulating air or gases in closed cycles, e.g. wholly within the drying enclosure F26B21/08, F26B21/14, F26B23/022 take precedence
• CPC Class Codes: F26B 21/06 Controlling, e.g. regulating, parameters of gas supply F26B21/14 takes precedence; control in general G05

Abstract

A lumber drying apparatus for drying lumber such as boards and squares to a desired final moisture content during the progressive transfer of the lumber through a drying section defined by an outer wall structure having an inlet at the green end and outlet at the dry end. The drying section is divided along the lumber transfer path into a plurality of drying compartments, with the atmospheric conditions of the drying compartments individually set according to a drying schedule predetermined by the kind and thickness of the lumber to be dried.

Claims

1. A lumber drying apparatus comprising an outer wall structure defining a drying section having at least one lumber transfer path, said outer wall structure preventing leakage of hot air from said drying section, curtain means in said drying section to divide the same along said lumber transfer path into a plurality of drying compartments, heating means for heating the interior of each said drying compartment, and means for producing circulation of hot air in each said drying compartment including a first fan located on one side of the lumber transfer path substantially at a position in a transverse central plane of the compartment, second and third fans located on the other side of the lumber transfer path substantially at positions symmetrical to each other with respect to said transverse central plane, first deflecting means disposed on opposite sides of said first fan for dividing the flow of hot air with respect to said first fan, said first deflecting means including side walls which incline inwardly into the compartment in a direction away from the center thereof towards the second and third fans, and second deflecting means disposed between said second and third fans for redirecting the flow of hot air between said second and third fans and said first fan such that two circulating paths of air traveling in opposite directions are produced in each compartment, said second deflecting means including further side walls which incline inwardly into the compartment in a direction away from the second and third fans towards the center of the compartment.

2. The lumber drying apparatus according to claim 1, wherein said drying section has a plurality of vertically spaced lumber transfer paths.

3. The lumber drying apparatus according to claim 1, which further comprises at least one high-frequency dielectric drying means in said lumber transfer path.

4. The lumber drying apparatus according to claim 1, wherein said curtain means dividing the drying section into a plurality of drying compartments each comprises a pair of upright support members on opposite sides of the lumber transfer path, a transverse shield member secured to said support members, and a flap member made of heat-resistant material and pivoted to the lower edge of said transverse shield member.

5. The lumber drying apparatus according to claim 1, comprising duct means for recirculation of part of the hot air for each of the drying compartments, said duct means partly extending to the outside of the outer wall structure and exposed to external atmosphere, and moisture removing means in the exposed portion of said duct means.

6. The lumber drying apparatus according to claim 1, wherein said outer wall structure further defines an inlet preparatory section adjacent the inlet end of the drying section, said inlet preparatory section being divided into a plurality of divisions by curtain means arranged one after another in the direction of transfer of lumber, such that a temperature gradient between external atmospheric temperature and the temperature of the drying section is established in said inlet preparatory section.

7. The lumber drying apparatus according to claim 1, wherein said outer wall structure further defines an outlet preparatory section adjacent the outlet end of the drying section, said outlet preparatory section being divided into a plurality of divisions by curtain means arranged one after another in the direction of transfer of lumber, such that a temperature gradient between the temperaturE of the drying section and external atmospheric temperature is established in said outlet preparatory section.

8. The lumber drying apparatus according to claim 5, wherein said moisture removing means comprises a number of vertical fins vertically depending from the top wall of the duct means and slanted fins between adjacent vertical fins and extending from the bottom wall of the duct means in an inclined direction such as to redirect the hot air stream.

9. The lumber drying apparatus according to claim 6, wherein said curtain means dividing the inlet preparatory section into a plurality of divisions each comprises a pair of upright support members on opposite sides of the lumber transfer path, a tranverse shield member secured to said support members, and a flap mmember made of heat-resistant material pivoted to the lower edge of said tranverse shield member.

10. The lumber drying apparatus according to claim 7, wherein said curtain means dividing the outlet preparatory section into a plurality of divisions each comprises a pair of upright support members on opposite sides of the lumber transfer path, a tranverse shield member secured to said support members, and a flap member made of heat-resistant material pivoted to the lower edge of said transverse shield member.

11. The lumber drying apparatus according to claim 1, wherein each said drying compartment is provided with moist air supply nozzles.

12. The lumber drying apparatus according to claim 1, wherein said first, second and third fans are suction fans.

13. The lumber drying apparatus according to claim 12, wherein said first deflecting means are disposed on opposite sides of said first fan and adapted to divides a stream of hot air proceeding toward said first fan into two branch streams flowing in opposite directions toward the respective second and third fans, and said second deflecting means between said second and third fans redirects hot air proceeding from said second and third fans toward said first fan, thereby producing the circulation of hot air.

14. The lumber drying apparatus according to claim 1, wherein each said drying compartment further comprises heater means disposed in the path of convection of hot air along said first and second deflecting means.

15. The lumber drying apparatus according to claim 1, wherein said second deflecting means in each said drying compartment defines a space with respect to the outer wall structure and is provided with a ventilating port communicating with said space, and also wherein duct means for recirculating part of the hot air is provided for each said drying compartment, said duct means partly extending to the outside of the outer wall structure and exposed to external atmosphere, whereby the hot air in each drying compartment is partly recirculated through said ventilating port, said space and said duct means to said first fan.

16. The lumber drying apparatus according to claim 15, wherein said duct means includes in its portion exposed to external atmosphere with a moisture removing means constituted by a number of vertical fins vertically depending from the top wall of the duct means and slanted fins between adjacent vertical fins and extending from the bottom wall of the duct means in an inclined direction such as to redirect the hot air stream.

17. The lumber drying apparatus according to claim 2, wherein each said lumber transfer path is constituted by a number of feed rollers arranged in a row.

18. The lumber drying apparatus according to claim 12, wherein said second deflecting means in each said drying compartment defines a space with repsect to the outer wall structure and is provided with a ventilating port communicating with said space, and also wherein duct means for recirculating part of the hot air is provided for each said drying compartment, said duct means partly extending to the outside of the outer wall structure and exposed to external atmosphere, whereby the hot air in each drying compartment is partly recircUlated through said ventilating port, said space and said duct means to said first fan.

19. The lumber drying apparatus according to claim 18, wherein said duct means includes in its portion exposed to external atmosphere a moisture removing means constituted by a number of vertical fins vertically depending from the top wall of the duct means and slanted fins between adjacent vertical fins and extending from the bottom wall of the duct means in an inclined direction such as to redirect the hot air stream.

20. The lumber drying apparatus according to claim 1 wherein said first deflecting means extends along said one side of the associated compartment and said second deflecting means extends along the other side of the associated compartment.

21. The lumber drying apparatus according to claim 20 wherein said side walls of the first deflecting means have end portions which gradually slope inwardly into the compartment in a direction away from said first fan.

22. The lumber drying apparatus according to claim 4 wherein said first fan and said second and third fans are on alternately opposite sides of adjacent compartments.

23. The lumber drying apparatus according to claim 22 wherein the side walls of the first deflecting means of one compartment join the side walls of the second deflecting means of an adjacent compartment at the juncture of these compartments.