Selection and Configuration of Gas-Liquid Equipment

5 Heat Transfer. Heat transfer in the turbulent regime is essentially a macromixing process. Heat transfer coefficients are controlled by the turbulence levels (hence boundary layer thickness) near the heat transfer surfaces. In many cases the process demands of suspension or dispersion and mass transfer are more than sufficient to ensure adequate heat transfer. 

6 Solid Particles. Particle suspension from the base and drawdown from the surface are often required in gas-liquid agitated vessels and are influenced in a complex manner by gassing. There are no well-established correlations for the influence of gas. Particle suspension is probably controlled by the energy and frequency of tnrbulent bursts, and drawdown by details of local flow patterns and vorticity at the surface, both of which could be expected to be affected by the presence of gas bubbles. 

Here a conflict can arise in an agitated vessel. High power input per unit mass is required to enhance mass transfer area and heat transfer coefficient, but this will result in a high degree of gas recircniation, reducing Ihe mean gas phase concentration driving force for mass transfer. Local shear rates will also increase with power inpnt. The balance will vary with scale. 

First the gas entry method can be decided. With a vessel, the gas is preferably sparged in through a dip pipe discharging (preferably via a sparge 

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