Dispersion Model for Gas Synthesis Reactors

FIGURE 7.11 Dispersed plug flow, Fluctuations due to different flow velocities, molecular diffusion, and turbulent flow. 

FIGURE 7.12 The dispersion model predicts a symmetrical distribution of tracer at any instant. From Levenspiel [9], Copyright 1972 by John Wiley Sons, Inc. Reprinted by permission of John Wiley Sons, Inc. 

For an initial population corresponding to a delta function, this differential equation (7.39) has the following solution  

Chapter 7 Powder Synthe with Gas Phase Reactants 

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This chapter discusses four methods of gas phase ceramic powder synthesis by flames, fiunaces, lasers, and plasmas. In each case, the reaction thermodynamics and kinetics are similar, but the reactor design is different. To account for the particle size distribution produced in a gas phase synthesis reactor, the population balance must account for nudeation, atomistic growth (also called vapor condensation) and particle—particle segregation. These gas phase reactors are real life examples of idealized plug flow reactors that are modeled by the dispersion model for plve flow. To obtain narrow size distribution ceramic powders by gas phase synthesis, dispersion must be minimized because it leads to a broadening of the particle size distribution. Finally the gas must be quickly quenched or cooled to freeze the ceramic particles, which are often liquid at the reaction temperature, and thus prevent further aggregation. 

The idealized flow models and axial dispersion model are used extensively to predict the performance of three-phase slurry reactors. For example, mixed flow model and axial dispersion models are used to predict the reactant conversion and product distribution for conversion of synthesis gas to liquid fuels using FT synthesis [52-57], methanol synthesis... 

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