Particle-fluid system contacting

The preceding consideration seem to imply that for efficient fluid-particle contacting in a reactor of a limited volume, high Jv should be chosen, while if the number of particles in a reactor is limited, the system should be operated at as high a value of Im as possible. 

Other kinds of inhomogeneity can also arise with this approach. For example, in experiments the container is placed in contact with a heat bath that regulates the temperature of the system. Shear motion tends to generate viscous heating, which is then conducted through the container wall and out to the heat bath. Hence, fluid particles closer to the wall will be colder than those farther away. If we limit ourselves to atomistic length scales, a simple hydrodynamic theory predicts that the maximum local temperature depends quadratically on the distance from the wall. The combination of these and other inhomogene-... 

Each stage of particle formation is controlled variously by the type of reactor, i.e. gas-liquid contacting apparatus. Gas-liquid mass transfer phenomena determine the level of solute supersaturation and its spatial distribution in the liquid phase the counterpart role in liquid-liquid reaction systems may be played by micromixing phenomena. The agglomeration and subsequent ageing processes are likely to be affected by the flow dynamics such as motion of the suspension of solids and the fluid shear stress distribution. Thus, the choice of reactor is of substantial importance for the tailoring of product quality as well as for production efficiency. 

Several reported chemical systems of gas-liquid precipitation are first reviewed from the viewpoints of both experimental study and industrial application. The characteristic feature of gas-liquid mass transfer in terms of its effects on the crystallization process is then discussed theoretically together with a summary of experimental results. The secondary processes of particle agglomeration and disruption are then modelled and discussed in respect of the effect of reactor fluid dynamics. Finally, different types of gas-liquid contacting reactor and their respective design considerations are overviewed for application to controlled precipitate particle formation. 

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