Physical characterisation of biomass-based pyrolysis liquids: Application of standard fuel oil analyses

The main purpose of the study was to test the applicability of standard fuel oil methods developed for petroleum-based fuels to pyrolysis liquids. In addition, research on sampling, homogeneity, stability, miscibility and corrosivity was carried out. The standard methods have been tested for several different pyrolysis liquids. Recommendations on sampling, sample size and small modifications of standard methods are presented. In general, most of the methods can be used as such but the accuracy of the analysis can be improved by minor modifications. Fuel oil analyses not suitable for pyrolysis liquids have been identified. Homogeneity of the liquids is the most critical factor in accurate analysis. The presence of air bubbles may disturb in several analyses. Sample preheating and prefiltration should be avoided when possible. The former may cause changes in the composition and structure of the pyrolysis liquid. The latter may remove part of organic material with particles. The size of the sample should be determined on the basis of the homogeneity and the water content of the liquid. The basic analyses of the Technical Research Centre of Finland (VTT) include water, pH, solids, ash, Conradson carbon residue, heating value, CHN, density, viscosity, pour point, flash point, and stability. Additional analyses are carried out when needed.