Low temperature fluidized wood chip drying with monoterpene analysis

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.