Multi-pass lumber kilns

Patent metadata

Field	Value
Publication number	US-10161678-B2
Application number	US-201815973318-A
Country	US
Kind code	B2
Filing date	May 7, 2018
Priority date	Mar 15, 2013
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

Embodiments provide a multi-pass kiln with two or more chambers, an entrance and an exit at a proximal end of the kiln, and a reciprocal flow path extending through the kiln from the entrance to the exit. Lumber charges traveling along the reciprocal flow path may travel in a first direction along one side of the heated second chamber before traveling in a substantially opposite second direction along the opposite side of the second chamber. The distal end of the kiln may be substantially sealed, and a pressure differential between the distal end and the proximal end may draw moist heated air from the heated chamber toward the exit and entry to preheat and/or condition lumber charges traveling through the first chamber.

First claim

What is claimed is:

1. A method of heat treating lumber in an elongated kiln, wherein the elongated kiln includes a first chamber, a second chamber adjoining the first chamber, a proximal end that includes the first chamber and an adjacent portion of the second chamber, a first and a second charge portal disposed at the proximal end on opposite first and second sides, respectively, of the kiln, and a reciprocal flow path that extends from the first charge portal to the second charge portal, wherein the reciprocal flow path includes a first portion disposed on the first side of the kiln, a parallel second portion disposed on the second side of the kiln, and a connector portion between the first and second portions, the method comprising:
moving a first lumber charge and one or more additional lumber charges through the kiln along said reciprocal flow path from the first charge portal to the second charge portal, such that the first lumber charge moves along the first portion in a first direction of travel, and on or along the connector portion to the second portion, and along the second portion in the second direction of travel;
heating the interior of the second chamber; and
circulating heated air received from the second chamber across one or both of the first and second portions of the reciprocal flow path in the first chamber.

2. The method as claimed in claim 1 , wherein the reciprocal flow path is defined by a guide member, the lumber charges are disposed on movable supports configured to moveably engage the guide member, and moving the lumber charges along the reciprocal flow path includes operating a first transport device to push the movable supports in the first direction of travel along the first portion and operating a second transport device to apply force against the movable supports in the second direction of travel along the second portion.

3. The method of claim 1 , wherein the reciprocal flow path is defined by a guide member, and wherein the guide member includes a first rail or track that defines the first portion and a second rail or track that defines the second portion.

4. The method of claim 3 , wherein the connector portion includes a third rail or track, and wherein moving the first lumber charge on or along the connector portion includes moving the first lumber charge along the third rail or track or moving the third rail or track.

5. The method of claim 4 , wherein the third rail or track extends from the first rail or track to the second rail or track, and moving the first lumber charge on or along the connector portion includes moving the first lumber charge along the first rail or track from the first portion to the second portion.

6. The method of claim 5 , wherein the third rail or track is operatively coupled with a switching mechanism, and moving the first lumber charge along the reciprocal flow path includes operating the switching mechanism to move the first lumber charge from the first rail or track to the connector portion or from the connector portion to the second rail or track.

7. The method of claim 4 , wherein the third rail or track is parallel to the first and second rails or tracks, and moving the first lumber charge on or along the connector portion includes moving the first lumber charge in the first direction along the first portion onto the third rail or track and moving the third rail or track into alignment with the second rail or track.

8. The method of claim 4 , wherein a distal end of the kiln is devoid of charge portals, and wherein moving the first lumber charge along the reciprocal flow path includes moving the first lumber charge on or along the connector portion within the kiln.

9. The method of claim 4 , wherein the connector portion is disposed within the second chamber, and wherein moving the first lumber charge along the reciprocal flow path includes moving the first lumber charge on or along the connector portion in the second chamber.

10. The method of claim 4 , wherein the kiln includes a third chamber, the second chamber is between the first chamber and the third chamber, and the connector portion is disposed at least partially within the third chamber, and wherein moving the first lumber charge along the reciprocal flow path includes moving the first lumber charge on or along the connector portion in the third chamber.

11. The method of claim 4 , wherein a third and a fourth charge portal are located at a distal end of the kiln, the first portion of the reciprocal flow path extends through the third charge portal, the second portion of the reciprocal flow path extends through the fourth charge portal, and the connector portion is disposed at least partially outside of the kiln, and wherein moving the first lumber charge along the reciprocal flow path includes moving the first lumber charge out of the kiln through the third charge portal, on or along the connector portion, and into the kiln through the fourth charge portal.

12. The method of claim 4 , wherein the kiln includes a door or curtain operatively coupled with at least one of the charge portals, the method further including operating the door or curtain to reduce airflow through the respective one of the charge portals.

13. The method of claim 12 , wherein the kiln includes an insulating member operatively coupled with at least one of the charge portals, the method further including operating the insulating member to reduce airflow through the respective one of the charge portals.

14. The method of claim 13 , wherein the insulating member includes a door or curtain that is selectively actuable to open and close the respective charge portal.

15. The method of claim 4 , wherein moving the first lumber charge along the reciprocal flow path includes moving the first lumber charge a first distance along the first portion of the reciprocal flow path and then pausing for an interval of time before moving the first lumber charge a second distance along first portion, such that the first lumber charge is substantially stationary during said interval of time.

16. The method of claim 15 , wherein the first distance is generally equal to a length of the first lumber charge or a multiple of said length.

17. The method of claim 4 , wherein moving the first lumber charge along the reciprocal flow path includes moving the first lumber charge continuously along the first portion to the connector portion.

18. The method of claim 1 , further including:
monitoring a moisture content of the first lumber charge within the kiln; and
adjusting a rate of travel of the first lumber charge through the kiln or an environmental condition within the kiln based at least on said moisture content.

19. The method of claim 1 , wherein the first chamber is disposed on only one of the sides of the kiln, one of the charge portals is disposed at a proximal end of the first chamber, and the other of the charge portals is disposed at a proximal end of the second chamber, and wherein circulating the heated air in the first chamber includes circulating the heated air across only one of the first portion or the second portion of the reciprocal flow path in the first chamber.

20. The method of claim 1 , wherein the kiln includes a door or a curtain operatively coupled with at least one of the charge portals, the method further including operating the door or curtain to reduce airflow through the respective charge portal.

Assignees

• Usnr Llc

Inventors

• Blomquist Christopher W

Classifications

• F26B15/04

  in a horizontal plane · CPC title

• F26B15/16

  the objects or batches of materials being carried by wheeled trucks · CPC title

• F26B2210/16

  Wood, e.g. lumber, timber · CPC title

• Y10T29/49716

  Converting · CPC title

• F26B15/10 Primary

  with movement in a path composed of one or more straight lines, e.g. compound {, the movement being in alternate horizontal and vertical directions} · CPC title