UBC Theses and Dissertations
Physical properties of leached and pelletized agricultural and woody biomass residues Hu, Zhaohong
In Canada, the agricultural sector produces 50 million dry tonnes of residues every year. These residues have a large potential for bioenergy application to replace fossil fuels. However, the disadvantages of using agricultural residues are its high ash content and low bulk density. Pelletization increases the bulk density of agricultural biomass and allows the agri pellets to be transported economically. Two types of methods were used for the preprocess of the feedstock, which were water leaching and pressing. Washing was applied with a water-to-biomass weight ratio of 25:1. The pressing process was done using 2 MPa pressure and 30 s residence time. The results show that washing and pressing (W&P) process led to a decrease in the angle of repose. After washing and pressing, the wt% of finer fraction of the particles (< 0.3 mm) of all biomass samples decreased while the wt% of the coarser fraction increased. W&P process also decreased the bulk density of dry materials. It can be concluded that W&P is better than washing only for non-woody samples since it led to higher ash removal efficiency and lower energy consumption (< 30 kJ/kg) than woody samples. However, washing without pressing (W) is sufficient for woody samples since it provided similar ash removal efficiency as W&P and lower extrusion and total energy consumptions during pelletization (~90 kJ/kg) than non-woody samples.
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