Karin Granström Emissions of volatile organic compounds from wood

The central aim of this thesis is to support the efforts to counteract certain environmental problems caused by emissions of volatile organic compounds. The purpose of this work was (1) to develop a method to measure emissions from dryers, (2) to determine the effect of drying medium temperature and end moisture content of the processed material on emissions of monoterpenes and other hydrocarbons, (3) to examine the emissions of monoterpenes during production of pellets, and (4) to examine the natural terpene emissions from forests with an eye to implications for modelling. The measurement method (1) resolves difficulties caused by diffuse emissions and high moisture content of the drying medium. The method as used here has an uncertainty of 13% using a 95% confidence interval. Emissions from a continuous spouted bed (2) drying sawdust at 140°C, 170°C or 200°C were analysed. When the sawdust end moisture content was reduced below 10%wb, emissions of terpenes and VOC per oven dry weight increased rapidly. Higher drying medium temperature also increased emissions. Examination of sawdust and wood pellets from different pellets producers (3) revealed that most of the terpene emissions happened during the drying step. Using sawdust with higher moisture content in the pellets press increased terpene emissions. Factors affecting terpene emissions from tree species in Sweden were reviewed (4). Implications for models of atmospheric chemistry and carbon budgets are discussed.