Variation in the physical properties of wood pellets and emission of aldehyde/ketone under different storage conditions

Abstract

Considering self-heating and hazardous gaseous emission, the safety of wood pellets storage has become one of the important aspects for woody biomass utilization. In this study, the emissions of aldehydes/ketones were analyzed by high performance liquid chromatogram (HPLC). The properties of pellets stored in semi-closed tanks with different temperatures and relative humidity (RH) were also investigated. The emissions of aldehydes and ketones from pellets were increased with raising temperature and RH during storage, while the pellets’ physical properties (dimension, density, Meyer hardness and moisture content) were reduced, except for 70% and 90% RH runs. The fatty acids compositions were extracted from both the surface and the inner part of pellets, which were analyzed by gas chromatography–mass spectrometry (GC–MS). The interaction between pellets’ physical properties variation and unsaturated fatty acid oxidation was revealed by the investigation of differences of extracted unsaturated fatty acids concentration between the surface and the inner part of pellets, which affected the aldehydes and ketones emissions.