Puupolttoaineiden kemialliset muutokset varastoinnissa ja kuivauksessa - PUUT29

The aims of the research were to identify the chemical and biological changes occurred in wood fuels during storing and thermal drying, to determine the emissions of this pretreatment to the environment and to estimate occupational health hazards in storage. The research was carried out in co-operation with Åbo Akademi University, Swedish University of Agricultural Sciences (SLU) and Kuopio Regional Institute of Occupational Health. The research was carried out during the years 2001-2002. The research was divided into following tasks: 1) field and laboratory storage tests, 2) laboratory drying tests, 3) estimation of occupational health hazards in storage, 4) recovery of by-chemicals in the pretreatment and 5) participation in the Swedish co-operation project. The storages of green and brown forest chips and sawdust, were built in the fuel field of a power plant, and followed over 3, 7 and 10 months. The temperature rose to 60-70 °C in the storages. The fuel properties, microbes and chemical composition of the materials were studied. All the raw materials became mouldier during storage. Dust and endotoxin concentrations were high when handling the materials. The laboratory storage tests were carried out by lysimeters at SLU. The drying tests were carried out in a fixed-bed batch dryer and by headspace-GC-AED/MS mainly at low temperatures of 90-170 °C, and the emissions were determined. The main compounds emitted were monoterpenes, sesqviterpenes, alcohols, aldehydes and carboxylic acids.