OTHER EQUIPMENT FOR GAS ABSORPTION

The interfacial area, a, was the subject of an investigation by Westerterp et al.(60 though the correlations proposed are complex. Maximum values of a are about 1000 m2/m3. Further work on the interfacial area in agitated vessels has been reviewed and summarised by Sridar and potter 61 who found that the correlation of Calderbank(62) was applicable for most situations. Calderbank proposed that, for pure 

When the surface aeration is significant, then the interfacial area is  

In these equations, a is the specific interfacial area for a significant degree of surface aeration (m2/m3), I is the agitator power per unit volume of vessel (W/m3), pL is the liquid density, o is the surface tension (N/m), us is the superficial gas velocity (m/s), u0 is the terminal bubble-rise velocity (m/s), N is the impeller speed (Hz), d, is the impeller diameter (m), dt is the tank diameter (m), pi is the liquid viscosity (Ns/m2) and d0 is the Sauter mean bubble diameter defined in Chapter 1, Section 1.2.4. 

The effects of gas hold-up and bubble diameter have also been studied by Sridhar and Potter and, again, the correlations obtained by Calderbank are recommended. 

Pl = density and viscosity of the liquid, and Sc = Schmidt number for transport in the liquid. 

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