Abstract
Conditioning is an effective method to release drying stresses and improve final moisture content (MC) distribution for spruce-pine-subalpine fir (SPF) lumber during drying. There are currently two methods used in the industry to add moisture to lumber during conditioning, namely low-pressure steam spray and cold water spray. Sixteen kiln drying runs were carried out in a laboratory kiln. Two types of conditioning treatment were investigated: cold water spray and steam spray. Temperature profiles, final MC distribution and drying stresses obtained for lumber conditioned by the two methods were evaluated and then compared. Results indicated that there were no significant differences on drying temperature profiles and lumber quality between the two humidification systems. Therefore, both humidification systems can be used for controlling humidity during kiln drying and for conditioning treatments.
Zusammenfassung
Konditionieren stellt eine effektive Methode dar, um Trocknungsspannungen abzubauen, und um die endgültige Verteilung der Holzfeuchte in Fichten- Kiefern- Tannen-Holz während der Trocknung zu verbessern. Gegenwärtig werden in der holzverarbeitenden Industrie zum Konditionieren zwei Verfahren zum Befeuchten des Holzes verwendet: Sprühen mit Dampf bei niedrigem Druck, oder Sprühen mit Kaltwasser. Sechzehn Trocknungsläufe in einem Labortrockner wurden durchgeführt. Zwei Konditionierungsverfahren wurden untersucht: Kaltwasser- und Dampfsprühverfahren. Temperaturverläufe, Endfeuchteverteilung und Trocknungsspannungen bei Schnittholz das nach den genannten zwei Methoden konditioniert wurde, wurden untersucht und miteinander verglichen. Es zeigten sich keine signifikanten Unterschiede bezüglich der Auswirkung der Temperaturverteilung und der Schnittholzqualität zwischen beiden Verfahren. Deshalb lassen sich beide Verfahren zur Regelung der Feuchte während der Labortrocknung und zum Konditionieren anwenden.
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Acknowledgements
Forintek Canada Corp. would like to thank its industry and goverment members for their guidance and financial support for this research. Special thanks to Mr. T.H. Briggs, Mr. Ross Johnson and Mr. Gerry Vandergaag from West Fraser Mills Ltd. and to André Friolet from Slocan Group-Mackenzie Division for providing the SPF lumber, and Mr. Darryl Klassen from MEC Systems Inc. for providing the cold water spray system used during the tests.
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Cai, L., Oliveira, L.C. A comparison between cold water and steam for SPF lumber conditioning. Holz Roh Werkst 62, 465–469 (2004). https://doi.org/10.1007/s00107-004-0521-y
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DOI: https://doi.org/10.1007/s00107-004-0521-y