Open access publications in the SLU publication database

Four pilot plant experiments were performed at the Biofuel Technical Center (BTC), SLU Umeå where different deciduous materials (birch, aspen, alder, salix) were added to sawdust of coniferous. One experimental design for each deciduous with three quantitative factors on three levels were used. The designs comprised the following parameters: Sawdust with moisture contents between 10-15 % based on raw weight; addition of deciduous between 0-40 % and material temperature between 20-70 °C. The response factors investigated were bulk density, mechanical durability, amount of fines, press current, pellet moisture, pellet temperature and die temperature. The statistical analysis based on multiple linear regression (MLR) showed that blends with birch decreased the pellet quality and increased the energy consumption during pelletizing, while blends with aspen and salix gave a better pellet quality and a decreased energy consumption. Blends with the alder material gave results that were difficult to analyze.
Moisture content and addition of birch were the factors that had most influence on the response factors bulk density, durability, fines and press current, while the material temperature had little impact. The same was valid for addition of salix, while also the material temperature had a significant influence when aspen was added. Addition of alder gave rather complicated models where all factors had great impact on the result.