Hydrocyclone selection and scale-up

The approach used in this chapter is based on families of geometrically similar cyclones so that all design variables are omitted from the scale-up correlations (except the size of the underflow orifice which should be variable and is considered here to be an operating variable). 

The significance of the dimensionless groups and constants in Table 6.1 will be explained in the following section. When faced with the problem of selecting the most suitable hydrocyclone or set of hydrocyclones for a particular task, one can consult manufacturers Uterature and consider one size from their range. A preliminary selection is usually based on capacity and the separation performance is then checked using additional information 

The simple theories or simplified charts from manufacturers are usually satisfactory for a preliminary selection when more detailed and reliable predictions of performance are required a model or theory must be used which includes the effects of feed solids concentration and of the underflow orifice setting. The choice is then narrowed to the empirical models or the semi-empirical scale-up using dimensionless groups because the other theories reviewed in section 6.6 are not yet useful for this. 

therefore, considered more appropriate in this book to use the chemical engineering approach of dimensionless groups and their semi-empirical relationships, as given in section 6.6.6. 

As a very preliminary step in the process of hydrocyclone selection, the low concentration performance data is often used even when the actual feed concentrations are higher than 1 % v/v. In clarification duties, however, this data would be correct for final design providing that high flow ratios are to be used. 

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