Woody biomass waste has been recognised as a renewable and promising source for future transport fuels via different conversion processes. Throughout New Zealand there are 1.7 million hectares of pine plantation forests and total annual residue of 12 million cubic meters produced from forest harvesting, wood processing plants and pulp and paper mills. Utilization of these resources is the target of both New Zealand government and industry to achieve goals placed by Kyoto and Montreal Protocols. Torrefaction is a mild pyrolysis treatment for biomass in the temperature range 200-350 degrees C. When applied to woody biomass, this process removes water and volatiles through the partial decomposition of hemicellulose. The resultant solid fuel has a higher energy density, improved storage and handling properties, and is more easily ground into a pulverised fuel. Pyrolysis (carbonisation) is a thermal process to convert the biomass to bio-oil, combustible gas and solid char at a temperature ranging from 400 to 600 degrees C. The liquid product of the process may be used as fuel or converted into bio-products used in local industries. The solid products of the process may be used in fuel or carbon sequestration in agricultural or forestry industries. A pilot-scale test unit has been built at CRL Energy Ltd. for continuous slow pyrolysis (carbonisation) and torrefaction of biomass. It is designed to carry out drying, torrefaction and slow pyrolysis operations on a wide range of biomass feedstock, including bagasse, bio-solids, dried seaweed and woody biomass. Vapours and gases can be drawn out at various points along the reactor for analysis and to identify the stage(s) where target specific product species are obtained. Torrefaction experiments were carried out on the pilot scale test unit on feedstocks of Eucalyptus nitens and Pinus radiata knife milled chips. Effects of temperature and residence time on the properties of solid and liquid products were investigated. The pine (softwood) was found to decompose at a lower temperature than the eucalypt (hardwood). A separate laboratory-scale nitrogen-blown fluidised bed pyrolyzer has been constructed at CRL Energy Ltd. This fast pyrolysis rig can process 1-1.5 kg/h of woody biomass in a temperature range of 450-550 degrees C. The purpose of this unit is to determine the impact of operating conditions on bio-oil yields and the down-stream processing of bio-oil into industrial materials. Pyrolysis experiments were carried out on Pinus radiata residues from sawmills, including sawdust, bark and their mixtures as feedstock. Yields and properties of pyrolysis oil (bio-oil), gas and solid char products were measured under different operational conditions. Some analysis was completed on pH, volatile content, chemical composition and calorific values of the products.
