Kuoren käsittely polttoaineeksi: PUUT07

The dry matter content of debarking waste from wood processing is typically low and particle size distribution is extensive. Debarking waste is also a difficult fuel to process. Nevertheless, bark is a significant source of domestic energy in the wood-processing industry. The aim of this study was to improve present methods and develop new mechanical and thermal bark processing methods, by which the fuel characteristics of bark are improved and waste water effluents from wood processing can be reduced. The work focused on experimental operations with existing bark shredders and presses. The sites of research were bark processing lines at five pulp mills and bark crushers at two sawmills. The present shredders disintegrate bark relatively well. Especially, softwood bark is totally crushed to < 60 mm, and 80-90% to < 30 mm. In shredding birch bark, the high wood content causes problems. In mechanical pressing of bark, the dry matter contents were as follows: 3.5-9.3 percentage units for pine, and 4.7-12.2 percentage units for spruce. The moisture content of softwood bark was still 50-65% after pressing. The dry matter content of birch bark grew only by 1-3.3 percentage units in pressing, primarily due to a low initial moisture content and wide particle size distribution.