Theoretical estimation of silo design parameters for fractionated loblolly pine grinds - Moisture content and particle size effects

Bulk material handling operations are key operations in process industries such as biorefineries, chemicals and pharmaceuticals. To ensure a successful production operation, a consistent and reliable flow of the materials from storage vessels without dust generation and flow obstruction are required. The objective of this study was to investigate the effect of particle size and moisture content on the theoretical estimation of silo design parameters for fractionated loblolly pine grinds. Loblolly pine grinds were fractionated into sizes using screen apertures: 1.40, 1.00, 0.71, 0.50, 0.25 mm and pan. The fractionated loblolly pine grinds were adjusted to the moisture level of 4.78%, 8.68%, 16.53%, 22.21% and 25.53% (w.b). There was a reduction in the hopper half angle with increase in moisture content and reduction in the fraction size. The hopper half angle also decreased with increase in angle of wall friction. The adjusted hopper outlet sizes varied between 1.20 and 28.56 mm. The wall normal and vertical pressure acting on the cylindrical section of the silo increased from 9.35 to 45.42 kPa and 15.34 to 48.91 kPa, respectively, with increase in fraction size and decrease in moisture content. The initial fill and flow induced pressures acting on the hopper section of the silo increased from 15.34 to 48.91 kPa and 24.71 to 78.79 kPa, respectively, with increase in fraction size and decrease in moisture content. Results of this study will be helpful in designing effective storage vessels and understanding the pressures exerted by stored biomass in the storage vessel.