Residence Time Distribution of Solids in a Multi-compartment Fluidized Bed System PDF Download

Author: Pajongwit Pongsivapai
Publisher:
ISBN:
Category : Fluidization
Languages : en
Pages : 214

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Book Description
In a conventional well-mixed fluidized bed the solids are almost completely mixed and the residence time for individual particles may vary between zero and infinity. For materials especially sensitive to the processing time, a wide distribution of residence time is extremely undesirable. A multi-compartment fluidized bed was proposed to minimize this problem. The two-compartment fluidized bed system was designed and experimentally investigated with positive results. Residence time distributions were measured with glass bead particles of 379 p.m mean diameter size. Tracer particles were colored glass beads which had exactly the same properties as the particles used for bed material. Two theoretical models were proposed to predict the flow behavior of solids through the two-compartment fluidized bed vessel. The results show the solids flow pattern can be described by the axial dispersion plug flow model and the tanks-in-series model. The parameters of both models can be determined by minimizing the sum of the squared differences between experimental data and model predictions curves. The influence of fluidization velocity, diameter of the orifice connecting the two adjacent compartments, and the height of the overflow exit orifice were investigated. The two-compartment fluidized bed can improve the residence time distribution of solids from a single fluidized bed. The residence time distribution of solids was also improved with decreasing fluidizing gas velocity. Orifice diameter and height of the overflow exit orifice did not influence significantly on particles flow in the two-compartment fluidized bed system. However, a solids mass flow through the partition orifice is predicted reasonably well, within moderate range of variance, by equation developed by de Jong (1965) [12].