Mechanical separation equipment from liquids

The nature and sizing of equipment depends on the economic values and proportions of the phases as well as certain physical properties that influence relative movements of liquids and particles. Pressure often is the main operating variable so its effect on physical properties should be known. Table 11.1 is a broad classification of mechanical processes of solid-liquid separation. Clarification is the removal of small contents of worthless solids from a valuable liquid. Filtration is applied to the recovery of valuable solids from slurries. Expression is the removal of relatively small contents of liquids from compressible sludges by mechanical means. 

Filtration separates cells from a fluid by forcing the fluid through a porous filter medium, which deposits solids as liquids pass through. Vacuum or positive-pressure equipment is used to create the driving force for filtration. The main advantages of filtration include high rates of separation, low cost, mechanical simplicity, and relative ease of maintenance. However, it can have a low retention or poor containment, and can require the addition of a filter aid to ensure good filtration when solids accumulate on the membrane. 

Centrifugation is a mechanical separation technique, which accelerates the phenomenon of sedimentation through the imposition of rotational motion in a liquid/particle suspension. In the centrifugation equipment, the centrifugal force causes the particles to move radially away from the axis of rotation, as shown in Figure 2.6. 

N - Nitrosomethylaniline (methylphenylnitrosamine). Place 53-5 g. of pure commercial monomethylaniline, 72-5 ml. of concentrated hydrochloric acid and 200 g. of crushed ice in a 500 ml. beaker equipped with a mechanical stirrer. Support a separatory funnel with a long bent stem (as in Fig. Ill, 35,1) containing a solution of 36 g. of sodium nitrite in 125 ml. of water over the beaker. Stir the solution and run in the sodium nitrite solution during 10 minutes do not allow the temperature to rise above 10° and add more ice if necessary. Continue the stirring for a further hour. Separate the oily layer, wash it once with 50 ml. of water, and dry it with anhydrous magnesium or calcium sulphate. Distil under reduced pressure from a 100 ml. Claisen flask. Collect the iV-nitrosomethylaniline (a pale yellow liquid) at 120°/13 mm. The yield is about 65 g. 

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