Study of wood chip sizes: searching for a method based on image analysis
Pari, L.; Febbi, P.; Assirelli, A.; Civitarese, V.; Santangelo, E.; Costa, C.; Menesatti, P.
21st European Biomass Conference and Exhibition, 3-7 June 2013, Copenhagen, Denmark.
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Via Giacomini 28, I - 50132 Florence.
ETA-Florence Renewable Energies.
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A standard method for the determination of the size distribution of wood chips is the oscillating screen method (EN 15149-1). Image analysis can give highly accurate measure of the two axial dimensions defined for each individual particle. Since the chip form influences the sieve results, the image analysis could provide a new method which is sensitive to the geometrical form for determining a more accurate measure of size integrated with form. A sample of wood chips was sieved through horizontally oscillating sieves, using five different screen hole diameters; the wood chips were sorted in decreasing size classes and the cumulative particle size distribution was determined. The true size distributions of a wood chip subsample, according to length and width, were determined by hand using a digital caliper and by weighing each of the chips. A comparison have been made between the traditional sieve result, the hand measured sizes (length and width) and the image analysis. The first results have shown that this last method has a high degree of accuracy for the characterization of wood chip size distribution. The main objective in the next future is to shift from a 2-dimensional static method to a 3-dimensional dynamic acquisition process.