Determining equivalent pore diameter for rigid porous spargers

Prediction of the properties of gas dispersions (e.g., bubble size) generated by porous spargers requires a knowledge of the pore diameter. Three methodologies for determination of an equivalent pore diameter D e of a rigid SS sparger of the type used in column flotation have been developed. In the first, D e is determined by fitting the bubble diameter predicted by the Kumar/Kuloor model to that measured. In the second, an estimation of bubble diameter is substituted. Estimation was tested using drift flux analysis and Molerus' uniform bubbling model: the former gave acceptable agreement with the measured. Fitting to the estimated bubble diameter offers a simplification over using the measured bubble diameter. The third approach was a further simplification. By combining the Kumar/Kuloor model with drift flux analysis, D e is estimated by fitting predicted to measured gas holdup. The methodologies are evaluated on a set of SS spargers using water with a flotation frother, Dowforth 250C. All three methodologies give similiar estimates of D e .