Influence of the particle size on the release of inorganic trace elements during gasification of biomass pellets

In the present work the release of inorganic trace elements as a function of the particle size of different biomass pellets was investigated. Therefore, three different sample sizes of three kinds of biomass (wood, miscanthus and straw) were gasified in an electrical heated furnace at 800 °C. The sample sizes were: Half cylinders with a particle size of 3 mm × 6 mm, irregular fragments with a particle size of 2-4 mm, and powder with a particle size of ⩽0.54 mm. Online hot gas analysis was done by Molecular Beam Mass Spectrometry. The focus was set on the alkali metals K and Na and on the nonmetals S, Cl and P. Qualitative and quantitative analysis of the mass spectra were done. Main gaseous species were 34H2S+, 36HCl+, 74KCl+, 58NaCl+, 60COS+ and 63PO2+. The data clearly showed the correlation of the size of the biomass samples on the release behaviour. It is shown that several secondary reactions have a significant influence on the release of inorganic elements.