Evaluation of ashes produced from fluidized bed combustion of residues from oranges' plantations and processing

Residues from oranges' plantations and processing may play an important role as biofuels for heat and power production in Mediterranean countries. The management of ashes produced during combustion is a great issue for the energy sector. Ash quality from lab-scale fluidized bed tests of these residues was evaluated in terms of operational parameters, environmental impact and potential uses with respect to legislative restrictions. Bottom and fly ashes were characterized by mineralogical, chemical, particle size distribution and thermal analyses, at different excess air ratios, fuel feed rates and fuel mixing ratios. The results showed that fly ashes were rich in Ca, K, P and Sr minerals. Slagging/fouling potential of pruning was very low, however that of peels and leaves was significant. The effect of excess air ratio or fuel feed rate on the quality of ashes was small. In the case of blends, the composition of the ashes varied between those of the blend components. Fly ashes of orange tree residues could be utilized as soil amendment agents, secondary building materials, or for road construction. Their environmental impact upon land recycling or management strategies is expected to be very low.