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Shearing Characteristics of Biomass for Size Reduction

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  056058,  2005 ASAE Annual Meeting . (doi: 10.13031/2013.19563) @2005
Authors:   A.R. Womac, M. Yu, C. Igathinathine P. Ye, and D. Hayes, S. Narayan, S. Sokhansanj & L. Wright
Keywords:   Biomass grinding, bioprocessing, size reduction, biomass properties, switchgrass, hickory, corn stover, cutting energy

Warner-Bratzler shearing device in a universal test machine evaluated the cutting response characteristics of single stems of hickory, switchgrass, and corn stover. Different knife bevel angles (30 and 45 ) at a fixed cutting speed of 254 mm/min were evaluated. Biomass cutting energy was determined on a stem cross-sectional area basis (specific cutting energy, kN/m). Biomass shear strength was based on peak load and actual cross-sectional area. Biomass variety significantly (p < 0.001) affected cutting energy for both knife bevel angles. Mean specific cutting energies for hickory, switchgrass, and corn stover were 41.1, 6.3, 53.1 kN/m, and 75.4, 10.1, 27.7 kN/m for 30 and 45 knife bevel angles, respectively. Thus, the shallower 30 bevel angle required less cutting energy when cutting hickory and switchgrass. Corn stover unexpectedly required less cutting energy for the increased bevel angle of 45 , and may reflect different composition. Statistical differences between mean specific cutting energies for 30 and 45 knife bevel angles varied with biomass. Shear strengths were statistically different (p < 0.001) for biomass varieties at a given knife bevel angles. Mean shear strength due to cutting of hickory, switchgrass, and corn stover by 30 and 45 knife bevel angles were 10.5, 12.2, 3.0 MPa, and 14.9, 15.3, 2.6 MPa, respectively. In conclusion, magnitude of specific cutting energy and shear strength varied with biomass selection and sometimes varied with knife bevel angle. Optimum biomass cutting and equipment design may need to be tailored to the specific biomass application and conditions.

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