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Low temperature fluidized wood chip drying with monoterpene analysis

Monoterpenanalyse bei Niedertemperatur-Wirbelschichttrocknung von Holzspänen


This paper describes the drying of ponderosa pine wood chips at low (20°C and 50°C) temperatures using a bench-scale batch pulsed fluidizer to evaluate both volatile pine oils (monoterpenes) and moisture losses during drying. Ten monoterpenes were measured; anecdotal information on inter-tree differences in monoterpene composition indicate that while overall total monoterpene composition is similar for each tree, the ratios of α-pinene, β-pinene, δ-3-carene and limonene differ between individual trees. Results of the drying studies show normal drying curves at 20°C and 50°C; at the air flow rates used, a 20% final moisture content resulted after approximately 45 and 25 min for the two temperatures, respectively. Oil content data were highly variable but indicated that at 50°C, oils start to volatize by approximately 10 min of drying. At 20°C, oil content does not appear to change over drying time.


Beschrieben wird die Trocknung von Gelbkiefer-Holzspänen bei niedrigen Temperaturen (20°C und 50°C) in einer Labor-Versuchseinrichtung mit pulsierender Wirbelschicht um die flüchtigen Pinienöle (Monoterpene) und den Feuchteverlauf beim Trocknen zu bestimmen. Es wurden zehn Monoterpene gemessen. Im Einzelnen zeigte sich, dass zwar die Monoterpenzusammensetzung der einzelnen Bäume im Großen und Ganzen ähnlich ist, sich jedoch die Verhältnisse von α-Pinen, β-Pinen, δ-3-Caren und Limonen von Baum zu Baum unterscheiden. Die Ergebnisse der Trocknungsversuche weisen normale Trocknungsverläufe bei 20°C und 50°C auf. Bei den verwendeten Luftdurchsätzen wurde bei den beiden Temperaturen eine Endfeuchte von 20 % nach ungefähr 45 bzw. 25 Min. erreicht. Der Ölgehalt variierte stark und es zeigte sich, dass sich die Öle bei 50°C nach ca. 10-minütiger Trocknung zu verflüchtigen begannen, wogegen sich der Ölgehalt bei der Trocknung bei 20°C nicht zu verändern scheint.

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The authors thank Dr. Armando McDonald of the University of Idaho Forest Products Laboratory for his assistance with the analytical portion of this work. This research was supported in part by funds provided by the Rocky Mountain Research Station, Forest Service, U.S. Department of Agriculture in Flagstaff, Arizona. The authors also acknowledge Forest Energy Corporation of Show Low, Arizona, which has provided impetus for further drying-related work with this technology.

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Correspondence to Bridget N. Bero.

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Bero, B.N., Reiboldt, A., Davis, W. et al. Low temperature fluidized wood chip drying with monoterpene analysis. Eur. J. Wood Prod. 69, 545–552 (2011).

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  • Moisture Content
  • Terpene
  • Monoterpene
  • Wood Chip
  • Bornyl Acetate