Effect of leaching on the ash behavior of olive residue during fluidized bed gasification

Fluidized bed gasification is considered to be the most advanced method for thermochemical conversion of various biomass fuels, e.g., wood, energy crops, agroresidues, etc., to energy offering economical and environmental benefits. Ash-related problems including sintering, agglomeration, deposition, erosion and corrosion resulting due, to the low melting point ash of agroresidues are the main obstacles for economical and viable application of this conversion method for energy exploitation of the specific residues. The effect of leaching (washing) the olive residue in order to improve its ash thermal behavior under the gasification conditions was studied. Gasification tests were performed in a tab scale fluidized bed gasifier with both leached and non-leached samples and the results concerning the ash thermal behavior of the used samples were associated with their ash elemental analysis, while the deposits produced during the gasification tests were analyzed using SEM-EDX analysis technique. The produced results clearly show that leaching could help significantly in avoiding to a great extent, the operational problems associated with the problematic ash thermal behavior in the case of olive residue. In particular, all gasification tests performed using the non-leached olive residue material as feedstock resulted in a rapid agglomeration of the reactor's bed material and consequently to the end of the gasification tests. On the contrary, gasification tests performed using the leached olive residue material ended without any agglomeration-deposition problems, while the: operation time was in all cases longer compared with the tests with the non-leached olive material. (C) 2002 Published by Elsevier Science Ltd.