Physical Property Relationships of Bulk Corn Stover Particles

Abstract

Corn stover is currently one of the major candidate lignocellulosic biomass feedstock for conversion to fuel ethanol. In this study, the effects of two important process factors (particle size and moisture content) on the bulk physical properties of corn stover particles were investigated for stover of two corn hybrids (conventional and staygreen). Bulk physical properties (particle density, loose and tapped bulk density, compressibility index, Hausner ratio, and porosity) of dry (<10% MC) and wet (>20% MC) were determined for corn stover that was chopped using a stationary forage harvester and ground to three hammermill screen sizes (6.4, 3.2, and 1.6 mm). Our results showed that there was no hybrid difference in all the physical properties measured, even though the chemical compositions were different. The geometric mean diameter of stover particles was significantly larger for the chopped material and decreased with particles from 6.4 to 1.6 mm screen size. The wet stover particles were significantly smaller than the dry particles for the staygreen corn hybrid, but not for the conventional corn hybrid. Loose and tapped bulk density decreased with a decrease in moisture content and increase in particle size. Particle density increased with a decrease in stover particle size, but a similar trend was not observed for moisture content. The compressibility index, Hausner ratio, and porosity reflected the very low bulk density and poor flow behavior of ground stover bulk.