Physical and Flow Properties of Fractionated Loblolly Pine Grinds

Abstract

<abstract> <b><sc>Abstract.</sc></b> Biomass feedstocks have to be ground before they are fed into biorefinery plants. However, the grinds from the grinding process have non-uniform particle size. Biomass also exchanges moisture with the environment. The overall goal of this study was to understand the contributions of moisture content and particle size to the physical properties (particle density, tap density, and bulk density) and flow properties (flowability, cohesion, internal friction, and wall friction) of loblolly pine grinds. The samples were fractionated into sizes using the following screen apertures: 1.40 mm, 1.00 mm, 0.71Â mm, 0.50 mm, 0.25 mm, and pan. Each fraction was adjusted to the following moisture levels: 4.78%, 8.68%, 16.53%, 22.21%, and 25.53% (wet basis). The heating values (18 to 19 MJ kg^-1) and volatile matter (84.9% to 87.5% dry basis) were not significantly affected by fraction size, while ash content (0.22% to 2.64% dry basis) increased with decrease in fraction size. The densities increased with decrease in moisture content and fraction size. Flow index values (i.e., flowability) decreased with increase in moisture content and decrease in fraction size. Except for the fraction retained on the 1.40 mm screen and at 4.78% to 16.53% moisture levels, all of the remaining fractions were cohesive. TIVAR 88 wall surface had the lowest angles of wall friction (10.88° to 15.54°) compared to stainless steel and mild steel. The results obtained from this study will be useful in the design and sizing of equipment and facilities for handling, storing, and transporting loblolly pine grinds.