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Effect of Temperature, Time, Particle size and Moisture content on Physical and Chemical Properties of Steam Exploded Woody Biomass

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2010 Pittsburgh, Pennsylvania, June 20 - June 23, 2010  1009796.(doi:10.13031/2013.29995)
Authors:   Pak Sui Lam, Sylvia H Larsson, Shahab Sokhansanj, Xiaotao Bi, C Jim Lim, Staffan Melin
Keywords:   Steam Explosion; Douglas Fir; Multilinear Regression; Bulk Density; Particle Size; Size Reduction

The effects of steam explosion processing conditions and feedstock parameters on physical and chemical properties of woody biomass were studied. The moisture contents of treated samples ranged between 14.5% and 32.2% and were higher than the initial moisture content of the untreated samples at 10% and 15%. The solid yield of treated samples varied between 46% and 86%. The mean value for solid yield was significantly (a=0.05) lower for samples treated at 220oC, compared to samples treated at 200oC. The pressure of steam before releasing the samples from high pressure cooking chamber to ambient (i.e. explosion pressure) ranged between 1169.83 1316.90 kPa for samples at 200oC and between 1732.86 1935.15 kPa for samples treated at 220oC, respectively. The steam pressure at pressure release point were modeled with multilinear regression with time and temperature with R2=0.85. Size reduction effect of steam explosion leading to particle fragmentation was observed. The relative geometric mean diameter of samples ground with 3.175 mm screen size were modeled with R2= 0.87 from the factors temperature, time, and moisture content. Relative bulk densities of steam treated samples ranged from 1.25 to 2.51, and relative tapped bulk densities from 1.12 to 2.23. A multilinear regression model for relative tapped bulk density with R2=0.91 was created from the factors temperature (T), time (t), particle size (p), moisture content (m), and the interaction terms Tp, Tm, and tp. The lignin content and extractives increased with temperature and time. The lignin content and extractives of samples treated at 220oC were significantly higher than that of samples treated at 200oC. The equilibrium moisture content of treated samples decreased with increasing temperature from moisture sorption test.

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