Bed Height and Material Density Effects on Local Time-averaged Gas Holdup in Fluidized Bed Reactors

Abstract

The hydrodynamic behavior of fluidized bed reactors is complicated due to complex interaction phenomena among the phases, gas and solids. The hydrodynamic must be understood to improve fluidized bed design, scale-up, operations and process efficiencies. Gas hold-up is one of the most important parameters that characterize the fluidization quality with minimum fluidization velocity. Gas hold-up describes the volumetric fraction of gas present within the bed materials, and is also useful in estimating the interfacial area between the dense and dilute phases that would be useful in heat and mass transfer calculations. In this study the effect of material density on the hydrodynamics of gas-soli fluidized beds was investigated and the local time-averaged gas and solid holdups were determined by using a 0.14 m diameter and 1.82 m height Plexiglas cylindrical fluidized bed column, two different Geldart type-B particles were used, glass bead and copper particle with material density of 2500, 5300 Kg/m3 respectively with same mean particle size of 210 μm, Three different superficial gas velocities were investigated Ug=25 cm/s, 30 cm/s and 35 cm/s. Also the effect of bed height was determined, Three different bed height to diameter ratios were investigated H/D = 0.286, 0.64 and 1.7 at specific superficial gas velocity Ug = 25 cm/s. Gamma ray computed tomography (CT) has been used as non-invasive technique to measure the time-averaged cross-sectional gas and solid holdups distribution The results show that, local time -average gas hold-up increases by increasing (H/D) ratio, decreasing the bed density increasing the gas hold-up in the bed.

Department(s)

Chemical and Biochemical Engineering

Keywords and Phrases

Computed Tomography; Fluidized beds hydrodynamics; Gas hold-up; Optical probe

International Standard Book Number (ISBN)

978-151081252-9

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 AIChE, All rights reserved.

Publication Date

01 Jan 2014

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