Section 5.22 Hydrocyclones

Hydrocydone, c/s cydone only excluding piping, instrumentation and pumps. 

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Cyclones can be used for the classification of solids, as well as for liquid-solid, and liquid-liquid separations. The design and application of liquid cyclones (hydrocyclones) is discussed in Section 10.4.4. A typical unit is shown in Figure 10.3. 

Solids handling features have been enhanced by elimination of dead legs use of hydrocyclones to manage solids in the feed preparation steps and in the streams passing to anolyte and catholyte sections of each cell for both agent and energetics... 

The grade efficiency reflects the properties of the particles exploited in the separation. It is influenced by the nature of the fluid/solid system, and by the operating conditions which determine the magnitude of the separating effect, and the period during which particles are subjected to it. Such details should, therefore, accompany any experimental data on G(d). The concept is widely applied to separations using hydrocyclones as discussed in Section 1.5.4. 

In this section, the general design of the hydrocyclone and its application in the grading of solid particles, or their separation from a liquid, is considered and then the special features required in hydrocyclones required for the separation of immiscible liquids will be addressed. The use of cyclones for separating suspended particles from gases is discussed in Section 1.6.2. 

Figure 14 ERT tomographic image of the hydrocyclone cross section and the comparison with UST (Cullivan and Williams, 2003).

Figure 15 Axial velocity contours in hydrocyclone (Cullivan et al, 2004) (see Plate 14 in Color Plate Section at the end of this book).

Monitoring the separation efficiency is an important way to evaluate the performance of a given separator. The efficiency concepts described in this section apply not only to animal cell separation, but also to the separation of any particles and bioparticles, such as microorganisms, cellular debris, nuclei, etc. These concepts apply to any separation device whose performance remains constant if the operational conditions do not change. This happens, for instance, in gravity settlers, centrifuges, and hydrocyclones. 

Hydrocyclones are similar to centrifuges in that they use cell settling in a centrifugal field as the principle of separation. A hydrocyclone (.Figure 11.9) consists of a conical section joined to a cylindrical portion,... 

Hydrocyclones, also called hydroclones, employ self-generated mild centrifugal forces to separate the particles into groups of predominantly small and predominantly large ones. Because of bypassing, the split of sizes is not sharp. The characteristic diameter of the product is taken as rfso, the diameter than which 50 wt % of the material is greater or less. The key elements of a hydrocyclone are identified on Figure 12.3(h). A typical commercial unit has an inlet area about 1% of the cross-sectional area between the vessel wall and the vortex finder, a vortex finder with diameter 35 40% that of the vessel, and an apex diameter not less than 25% that of the vortex finder. For such a unit, the equation for the cut point is... 

Design nsing the same principles as liquid-solid hydrocyclone. Section 16.11.5.8. For flooded underflow, the pressure drop is about two to seven times greater than for air core operation. 

Hydraulic cone classifier V°W (M-F) Open cylindrical upper section with conical lower section containing slowly rotating mechanism. 0.6 to 1.6 400 )J,m to 100 )J,m (6 mm) 10 to 120 Not critical 2 to 15 30 to 50 3 to 7.5 Used primarily in closed circuit grinding to reclassify hydrocyclone underflow. 

The idea of utilizing the centrifugal force for separation of liquid from gas also finds application in gas-oil hydrocyclone separators (Fig. 2.9). In order to create a centrifugal stream inside these separators, an attached unit - a hydrocyclone - is installed on their lateral surface (Fig. 2.9, a, b, c). A hydrocyclone is usually a vertical device with a fiat tangential input and directing branch pipe for gas flow reversal in the top part, and a liquid cross-flow section in the bottom part. The technological reservoir is made in the form of a horizontal separator with various devices for additional separation of liquid from gas that are typical for oil-gas separators. 

Although there are several ways in which solid/liquid separation may be achieved (e.g. settling, flotation, hydrocyclones, evaporation, magnetic, electrostatic, gravity, centrifuge, vacuum, and pressure), the mechanisms that consume the largest volume of textile filter media, and on which this section will concentrate, are those of pressure and vacuum. 

To recover liquid in order of preference of settlers, Section 5.8, thickeners. Section 5.10 and sedimentation centrifuges. Section 5.12 clarifier, settler, washing tray thickener, reactortubular bowl centrifuge, batch automatic (horizontal or vertical bowl, disc with intermittent nozzle discharge) continuous disc bowl centrifuge with nozzle discharge. 

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