Physical and chemical characterization of particles in producer gas from wood chips

Particles in the gas from a two-stage (separate pyrolysis and gasification) down-draft biomass gasifier were collected and characterized. Their concentration, geometries and chemical compositions were investigated. Special attention was given to features suspected to harm internal combustion (IC) engines fueled by the gas. The implications of the findings on engine wear are discussed. The majority (85%) of the total particulate matter (TPM) mass was identified, using scanning electron microscopy (SEM), as mono-sized spherical primary soot particles with diameters of 70 nm. Soot agglomerates, up to 30 μm were present. 77% of the TPM was determined, by thermogravimetric analysis (TGA) to be carbon structures. The dichloromethane (DCM)-soluble fraction (11% of the TPM) was extracted, separated into fractions of varying polarities using adsorption column chromatography and analyzed using gas chromatography with a flame ionization detector (GC-FID). More than 50% of the soluble mass was relatively non-polar. A well-separated fraction containing 10% of the DCM solubles had significantly higher polarities than the other solubles and/or contained relatively large molecules. Anisole extractions of the particles showed that a 3–7% of the DCM-insoluble TPM was dissolved using this solvent.