Design of Stirred Tank Reactors with Internal Cooling Coils

8 DESIGN OF STIRRED TANK REACTORS WITH INTERNAL COOLING COILS 

On the other hand, the presence of coils has a positive effect on e. The coils break up the bubbles, thereby generating smaller bubbles and increasing e. Based on the work in a 0.57 m diameter stirred tank reactor fitted with three different coils and various impellers, correlations were derived for these important parameters as discussed in Section 7A.8.1. 

Nikhade (2006) has determined the gas holdup in 0.57 m diameter stirred tank reactors equipped with different impellers and internal coils. The investigation covered three impellers (PTD, DT, and PTU) and three internal coils with different surface areas. He could successfully obtain a unique correlation for the gas holdup data for three different impellers and coils using the approach proposed by Yawalkar et al. (2002a). The correlation obtained was 

If Equation 7A.27 is compared with the correlation for e, without coils (Table 7A.1), it is evident that the gas holdup is a relatively strong function of but a relatively weak function of when internal coils are present. The coils tend to break the bubbles. The resulting smaller bubbles are easily dragged down below the impeller, and hence, is higher in the presence of internal coils. 

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