Flow performance of ground biomass in a commercial auger

• Volumetric flow rates of biomass handling are not low in comparison to corn.
• Low bulk density limits biomass handling efficiency rather than machine mechanism.
• No significant relationships were found between biomass AOR and flowability in an auger.
• More physical property variables are needed for power predictions of biomass handling.

The flow performance of preprocessed biomass plays an important role in biomass transportation and handling. The research as presented here investigated how the Angle of Repose (AOR) of miscanthus and switchgrass is related to flow performance of biomass particles in an auger that was originally designed to convey corn and soybeans. The flow performance metrics were the specific energy consumption (SEC), energy efficiency (EE), volumetric efficiency (VE), volumetric flow rate (VFR) and mass flow rate (MFR).The results showed that the EE and MFR while conveying miscanthus and switchgrass particles ground through 6.35-, 9.53-, 12.7- and 25.4-mm milling screens were much lower than those of corn. However, the differences in VFR between corn and biomass were much smaller than that in SEC and mass flow rate (MFR). This result implies that the low bulk density of biomass feedstock is a more pronounced limiting factor in biomass handling than the conveying mechanism used.The AOR of miscanthus and switchgrass particles was found proportional to particle size and moisture content. While AOR is an indicator of the material's internal friction, in this study, the AOR of miscanthus and switchgrass was not significantly related to the energy/volumetric efficiency of the auger. By comparing the measured auger power consumption to predictions from empirical equations developed for corn and soybean, it became evident that these equations do not perform well for biomass feedstock.

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