Bulk density of forest energy chips

Abstract

Bulk density and moisture content of forest chips are important elements influencing transport efficiency. The aim of the study was to determine the moisture content and bulk density of forest chips and identification if these parameters are influenced by the species making up the tree stand and sharpness of the chopper's knives. Measurements were performed in two forest sites characterised with different composition of cut down tree stand. In both places, chopping of the residues was performed with the same chopper (Bruks 805 CT) at two degrees of knife sharpening - blunt knives and sharp knives. The applied investigation procedure was in compliance with the applicable norm PN-EN15103:2010. After determination of homogenous groups, the obtained results of bulk density, falling within the range of 154-165 kg.m-3 justify the claim that bulk density of forest chips depended on the species composition of the tree stand and sharpening of the chopper's knives. The highest bulk density may be obtained by grinding the deforestation residues with a sharp knife, but in practice, chopper operators work with knives with a varying degree of blunting.