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Title: A study of the characteristics of a novel cocurrent downflow bubble column contactor for use as a three-phase reactor
Author: Xiao-Xiong, Lu
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 1988
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A cocurrent downflow contactor (CDC) has been constructed in and potential as a reactions. Prior to studying the CDC as a reactor its performance order reactor to investigate its for use with behaviour gas-liquid-solid was investigated with respect to its hydrodynamic behaviour with liquids of varying viscosity and surface tension. Liquid systems employed were water based, containing various concentrations of sodium alginate, glycerol, and I-propanol. Parameters such as minimum inlet liquid velocity, column liquid velocity, pressure drop, bubble size, gas holdup, and gas liquid interfacial area were determined. Empirical relationships were derived enabling minimum inlet velocity, maximum column velocity, pressure drop and gas holdup to be calculated. It was observed that gas holdup values in the range of 0.5-0.6 could be obtained and these are much greater than those attainable with conventional stirred or bubble column systems. The gaS-liquid mass transfer characteristics of the CDC were studied by the absorption of oxygen into water and a dimensional analysis of data allowed the overall mass transfer coefficient to be determined and correlated with experimental data. The hydrogenation of itaconic acid (CSHS04) using a 5% and 10%w/w Pd/Charcoal catalyst was studied at 15-50oC and 1 bar absolute in a stirred reactor and at 200C and 1-3 bars absolute in the CDC reactor using the following solvents: water, methanol, 2-propanol and aqueous glycerol. It was found that gas-liquid mass transfer rate control could be eliminated, due to the efficient agitation and high gasliquid interfacial areas generated. The rate controlling steps were found to be those of liquid-solid mass transfer and surface reaction, both steps being almost equally important in the CDC reactor. In the case of the stirred reactor, the liquid-solid mass transfer contribution depended upon the solvent and ranged from 5% (methanol) to 40% (water). Finally it was observed that on a laboratory scale the stirred and CDC reactor can give similar performances. However, in industrial or pilot plant scale, the CDC could retain its efficiency, giving high values of overall mass transfer coefficients and overcome the inefficient mixing of large scale stirred reactors.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available