Characterisation of tar thermal gasification of biomass

The goal of the project is to characterize tar compoments in order to increase the knowledge of chemistry and reaction patterns under formation of the substances by thermal processes and secondary down stream reactions when the tar is condensed in liquids, deposited on metal surfaces or adsorbed on the active surface of a catalyst. The results should help with regard to minimizing the formation of tar and optimizing downstream tar cleaning equipment. A survey of methods of collecting and characterisation of the tar components at different European companies and universities will be conducted. Tar samples from different thermal gasification plant are analysed. Course of action: Research institutions in Denmark and abroad are contacted in order to make a survey of the different used methods of collecting and characterisation of tar. Experience and knowledge of tar qualities and reactions are acquired at the same time. The methods are evaluated for making a comparison between the different methods. Tar from 4 different thermal gasification plant (updraft, downdraft, open core) are collected according to selected methods. The tar components are divided into different groups of solubility in water, boiling point, and chemical characteristics. The volatile tar components are analysed gas chromatographically with a flame ionisation detector (FID) and a mass spectrometer (MS). The heavy fraction is characterized by gel permeation (GPC) at the first dividing. The fractions are characterized by flash pyrolysis- GC/MS and mean molecular weight. The latter is determined by freezing point depression. The qualifications of the different methods af tar collecting, separation and identification are evaluated from the results of the analysis. An optimal methods is selected for obtaining a totality of the tar fractions