Effects of fragmentation and particle size on the fuel properties of hazelnut shells

Fragmentation of biomass leading to the formation of very fine particles is a serious concern particularly in biomass burning systems because of their enormous thermal reactivity. Some types of biomass species have a considerable tendency to form such problematic dusts. For this purpose, the extent of size fragmentation during breaking, storage, and transportation was investigated on hazelnut shell that is a promising woody biomass. The particle size distribution of this biomass showed that the fragmentation that is an undesirable feature for solid fuels in general is quite limited, and nearly 50% of the particles are coarser than 8 mm, while the particles which are finer than 0.5 mm account for only 3%. Then, the sample was sorted into the size fractions of +10 mm, 5-10 mm, 2-5 mm, and 0.25-0.5 mm, and each fraction was tested from various aspects. Burning tests were conducted using a thermal analyzer. It was concluded that the content of extractives may predict the fragmentation phenomenon, and some certain parts of biomass where the extractives are concentrated tend to form more fragile structure, leading fragmentation. Also, the particle size of biomass mainly affects the devolatilization characteristics during combustion. Besides, burning characteristics of the size fractions indicated that except the finest fraction (0.25-0.50 mm), the burning reactivities of all the fractions are not seriously different from each other, and the differentiations can be ignored.