Parametric approach about fluidized bed of particles of silica and cashew nut shell

Abstract

Gaseous fluidization of solid particles arises as an alternative technology to gasify the cashew nut shell (CNS) efficiently. However, still there are fluid dynamic phenomena to be known when a heterogeneous medium is fluidized and, also, little information about this kind of biomass is available. Therefore, an experimental study on fluidization of bed constituted of particles of silica and CNS was performed in order to achieve an encompassing understanding about the phenomena of the fluidization process, targeting to obtain project parameters necessary to the development of an efficient CNS gasifier. Thus, this investigation aims to learn about wall effects, flow profile, pressure variation, and CNS particle displacement velocity along the fluidized column. The experimental apparatus is constituted of three acrylic tubes with internal diameters of approximately 45, 70 and 90 mm, and 1-meter long, where pressure drops were measured by piezo-resistive sensor. Besides varying column diameters, different granulometries of silica particles (72.43 μm, 321.02 μm and 546.61 μm) were experimented on this study, utilizing different CNS particle sizes. The bubbly regime was applied to gas flow in the fluidized bed and effects of flow on the bed were studied, in order to determine the best region of the column for the biomass injection. It was possible to observe the formation tendency of "silica piston" along the fluidized column. As this phenomenon tends to interrupt the gas flow some experiments were performed to identify the limit-dimensions of column, concerning the length-diameter ratio.