Flow and Transport Properties In High-Solids Biomass Slurries

Economic biochemical conversion of cellulose to sugars necessitates minimal addition of water to biomass slurries during conversion, resulting in high-solids systems. The resulting slurries are effectively wet-granular materials. These materials presents difficulties for reactor engineering, as their flow and transport properties, along with the mechanical properties that govern them, are poorly understood. This work examines the nature of high-solids flow, along with the heat and mass transfer properties of biomass and related model materials. Methods were developed to measure the volume fraction of solid, liquid and gaseous phases of high-solids slurries. The effect of phase composition on flow was systematically examined in a rotating vessel. Qualitative observations, as well as accessible quantitative information about size distribution of aggregates, were made. Further, a model for measuring bed diffusion in biomass was developed, and experiments were performed to measure the bed diffusion coefficient in model materials and biomass. Finally, heat transfer in a packed bed of biomass was examined, and conductivity coefficients were calculated and related to phase composition.