Fluidized bed drying and modelling
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School of Chemical Engineering |
Master's thesis
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Mcode
Language
en
Pages
97
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Abstract
The study in this master's thesis focuses on the fluidization behaviour and drying kinetics of spherical catalyst support particles, 5 mm in diameter, in a fluidized bed dryer system. The primary objective was to establish a comprehensive hydrodynamic baseline that supports future studies on the shape effect. This thesis conducted a thorough study on the influence of various operating parameters affecting drying processes, including air temperature settings, superficial air velocity, and bed load weights, on drying performance. It was found that the drying processes in wet particles rely on a certain hydrodynamic limit. The lack of airflow stimulated agglomeration through the liquid bridge, which is characterized as the primary mechanical obstacle to the drying process. The effective moisture diffusivity (D_eff) values were computed and possess an Arrhenius-type temperature dependence with a low activation energy, indicating loosely bound moisture and effective drying at moderate temperatures once fluidization is achieved. The process demonstrates exceptional energy efficiency when proper fluidization conditions are met. Finally, this study establishes a precise timeframe for effective drying operations at moderate settings without triggering hydrodynamic collapse. The results provide a validated spherical-diffusion baseline and model fits for subsequent studies on non-spherical particles.Description
Supervisor
Alopaeus, VilleThesis advisor
Bernad, AndreuPokki, Juha-Pekka