Evaluation Indexes of Poplar Sawdust and Alfalfa Grass Forming Pellets

An experimental study was conducted to obtain the degree and pattern of influence of the interaction of various test factors on the evaluation indexes of biomass-forming pellets and the optimal combination of test parameters. Poplar sawdust and alfalfa grass were crushed and compressed into pellets, which were used as test samples. The particle size and moisture contents of the biomass raw materials were selected as test factors, and the quality and performance evaluation indexes, such as relaxation density, Shore hardness, water resistance, crush resistance, longitudinal dimensional stability, forming rate, and productivity, were measured for each pellet group. The results showed that for the same biomass raw material, when the particle size range is zero to 1.5 mm and the moisture content is at 15%, the relaxation density, Shore hardness, and forming rate of the formed pellets are the greatest, and the crush resistance, water resistance, and longitudinal dimensional stability are the strongest. When the particle size range is about 4 to 5.5 mm and the moisture content is at 5%, the relaxation density, Shore hardness, and forming rate of the pellets are the smallest, and the crush resistance, water resistance, and longitudinal dimensional stability are the weakest. The best moisture content of the pellets is about 15%.