Pelletizing of Bark Residue Resulting from Debarking of Softwood Trees

摘要

Debarking is an essential part in the technology of round timber processing. The volume of bark going to waste annually is millions of cubic metres; therefore, the use of bark as an underexploited renewable source is of increasing importance. Pelletization is one of the recognized methods to increase the bulk and energy densities of plant biomass, and therefore improving its value as a fuel. Plant biomass pellets are the only solid fuel that has a global constantly growing market.In this work the bark obtained by debarking of softwood trees for pulp manufacture was studied in terms of feasibility of fuel pellet production. Fuel characteristics, including elemental composition, ash content, calorific values, and other parameters, required by fuel pellet standards were determined. The laboratory flat die pellet mill KAHL 14-175 was applied for the pelletizing study. The study showed that using floatation process for purification/fractionation of bark batch 86% of bark residue became suitable for obtaining fuel granules in quality that meets the demands of EN 14961-2B European standard for non-industrial and industrial fuel pellets.