Hydrocyclone function, design and merits

There has been a lot published about the relative proportions of the cyclone dimensions and their effect on separation efficiency and pressure drop. A user need not be concerned with this aspect except for two observations. Firstly, there is a rule by which every measure which increases resistance to flow improves solids recovery, and vice versa. This applies to all proportions of the cyclone body, within certain reasonable limits, except for the length of the cyclone. Thus for example, a cyclone with relatively small inlet and outlet openings is expected to give higher mass recovery but will offer higher resistance to flow and therefore have lower capacity. Several optimum or recommended designs have been published and, as these have been well tested and enough is known about their performance, they may be adopted if needed. 

In order to make full use of the advantages of the hydrocyclone it is often best to use multiple units, connected either in series or in parallel. In clarification duties for example, the parallel connections allow the more efficient, smaller diameter units to be used to treat high flow rates. The series connections on the other hand, are used to improve overall recoveries in clarification, to produce thicker underflows and clearer overflows simultaneously, to wash solids or to sharpen the classification or sorting. 

1 they are extremely versatile in application in that they can be used to clarify liquids, concentrate slurries, classify solids, wash solids, separate two immiscible liquids, degas liquids or sort solids according to density or shape  

2 they are simple, cheap to purchase, install, and run, and require little in the way of maintenance and support structures  

3 they are small relative to other separators, thus saving space and also giving low residence times, which gives them an advantage in terms of the speed of control over the sedimentation classifiers for example  

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