Rheometry of coarse biomass at high temperature and pressure

We designed, constructed, and tested a new device that can measure the rheological properties of lignocellulosic biomass slurries with high solids concentrations (>25%) containing large particles (>10 mm), and that can operate at high temperatures (>230 °C), high pressures (>2.8 MPa), and low pH (<1.0). Rheological properties measured with this Lignocellulosic Biomass Rheometer (LCBR) are consistent with those measured with another instrument. Biomass samples investigated are yield stress materials, consistent with previous reports. For modest temperatures, the viscosity decreases reversibly with increasing temperature. When the biomass is exposed to sufficiently high temperature and low pH, we observe an irreversible decrease in apparent viscosity, consistent with that expected as hydrolysis reactions reduce the concentration of insoluble solids.