Scaling Factors for Liquid Phase Stirred Tanks

4 SCALING FACTORS FOR LIQUID PHASE STIRRED TANKS 

The most common problem in scaling up stirred tank reactors is the difficulty in maintaining the desired operating temperature. The current section assumes this is possible. Techniques for maintaining a desired energy balance are deferred to Chapter 5. 

When scaling with geometric similarity, all linear dimensions—for example, the impeller diameter and blade width, the tank diameter, the distance that the impeller is off the bottom, the height of the liquid in the reactor, and the width of the baffles—scale as The scaleup relations are comparatively simple when scaling with geometric similarity and when the small-scale vessel is fully turbulent. The Reynolds number for a mechanically agitated vessel is defined as 

Taking ratios of Equation 4.12 for large and small vessels gives 

The mixing time scales as Sn the pumping capacity of the impellor scales as SnS and the power to the impeller scales as Sjj. As discussed in Section 1.5, it is impractical 

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Scaling Factors for Liquid Phase Stirred Tanks 143... 

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