MATHEMATICAL SIMULATION OF ELECTROCHEMICAL FLUIDIZED BED

إنجليزية
number: 
1832
Degree: 
Author: 
MOHANNAD JUAD KADHUM
Supervisor: 
Prof. Dr. Qasim J. M. Slaiman
year: 
2007

In this work it is attempted to find a model describes potential,current, and concentration distributions in addition to hydrodynamicstudy along an electrochemical fluidized bed reactor. Electrochemicalfluidized bed reactor consists of a bed of particles which fluidizes andexpands by an upward moving electrolyte. An electrical potentialdifference is applied between the upper and lower parts of the bed which induces the electrochemical reaction to take place on thesurfaces of the particles. Electrochemical fluidized bed reactorrepresents one of the most useful applications in electrochemicalengineering and its main uses are: electrowinning, pollution inhibition,and purification.Three cases have been considered in this work linear, Tafel, and concentration polarization models. Models have been developedstarting from Ohm s law and using Laplace transformation to solve forthe potential distribution across the bed. Tafel polarization has beentested and found that the resistivity equation suggested by Fleischmann et al (1971) is invalid since Fleischmann suggestion assumes constant metal phase resistivity along the bed while in fact this is not the case since the particles are discrete in the bottom of the bed and become closer up to the end of the reactor. So, an expression has been developed to describe the local metal phase resistivity which depends on both local position and bed expansion due to fluidization. Acorrection factor has been used and inserted to equation suggested by Fleischmann et al and it covers a wide range of particle diameter. The error has been reduced greatly by this assumption for both solution and metal phase potential profiles. Concentration profiles have also been studied in this work in addition to velocity change and pressure drop change with percentage expansion of fluidized bed.

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