Open access publications in the SLU publication database

Abstract

Forestry and the forest industry plays an important role in the Swedish economy. From forest operations and at sawmills and pulp and paper mills several by-product assortments are generated and these are providing the basis for the highly developed Swedish bioenergy sector. Logging residues constitute a major resource and is utilized as fuel in heat and power plants. However, due to a relatively low heating value and high management costs, this resource is still underutilized. Logging residue chips have irregular particle size, high moisture content (30-60%) and high ash content (8-15 %) and these features cause most of the problems encountered during the operation of feeding systems and combustion processes. Ash, present both in endogen plant tissues and as extrinsic matter such as sand and clay minerals, is of especially big concern for small-size plants. In this on-going work screening of logging residue chips was performed. Different mechanical screening methods was applied with the aim to provide a homogenous fuel with a higher quality for combustion purposes. Through screening, the chemical fuel composition is also altered and this affects combustion behavior and ash chemistry. The objective of the present study is to, from a combustion process perspective with emphasis on ash chemistry, evaluate the overall effects of different screening procedures when applied on stored logging residue chips.