DISK CENTRIFUGES

These concepts are used to analyze separations in the botde centrifuge, the imperforate bowl centrifuge, and the disk centrifuge. Separation by density difference in other types of centrifuges can be analyzed by analogy. 

Fig. 3. Sepaiation in a disk centrifuge, where X is the initial position of the particle. Other terms are defined in the text.

Excessive volume of soHds may be retained in the bowl of conveyor centrifuges if (/) the conveyor volumetric displacement is not sufficient to handle the sedimentation rate of soHds (2) the sedimented soHds cannot be successfully conveyed and discharged over the soHds port until a sufficient layer has been built up inside the bowl and (3) soHds do not easily sHde outwardly on the underside of the disk of a disk centrifuge. 

In the case of the nozzle disk centrifuge, the flow of the soHds phase through the discharge nozzles may be so restricted that an excessive layer can accumulate inside the bowl sheU. When this layer reaches the zone utilized by the fresh feed stream entering the disk stack, reentrainment of the sedimented soHds by the fresh feed may lead to poor sedimentation performance. 

Other Sedimentation Seale-Up Equations. Some centrifuge supphers use an area-equivalent, description instead of S others use KQ or values. All of these ate in urhts of area. For a disk centrifuge,... 

Because clay tends to pack hard, only the continuous nozzle discharge bowl would be satisfactory. Intermittently dischargiag disk centrifuges could not be used. 

In general, soHds-retaining batch and batch automatic machines are limited to low feed concentrations to minimize the time required to unload the soHds. Continuous disk centrifuges can have higher feed concentration. The limit is the underflow concentration. Conveyor discharge centrifuges can handle high feed concentration and are limited only by the volume of soHds displacement, or torque capacity. 

ScroU centrifuges discharge soHds continuously and usuaUy drier than disk and imperforate batch types. GeneraUy disk centrifuges have the highest values of Z or for a given size and therefore the best abUity to coUect fine particles at a high rate. 

Fig. 14. Disk centrifuge bowls, where bowl diameters range from 10—90 cm feed flow rates from 0.06 x 10 to 38 x 10 m /s (1—600 gpm) and...

FIG. 18-142 Disk-centrifuge bowls (a) separator, solid wall (b) recycle clarifier, nozzle discharge. 

Decanter centrifuges with mechanical shaft-to-casing seals are available for pressure containment up to 1,1 VIPa (150 p.sig), similar to the nozzle-disk centrifuge. They can be built to operate at temperatures from -87 to -t-2fi0°(i (-125 to -t-500°F),... 

Disinfection processes, as advanced wastewater treatment, 25 909-910 Disjoining pressure, 12 6-7 Disk agglomeration, 19 8 Disk atomizer spray dryer, 9 127 Disk bowl centrifuge, theory of performance, 5 518 Disk centrifuges, 18 144... 

NO control, diesel engine, 10 61. See also Nitrogen oxide (NO ) exhaust control NO emissions, 10 32, 35, 36, 46, 137 NO production, 13 855, 856-857 NO reduction catalysts, 12 430 NO reduction technology, post regenerator, 11 719-720 NOXSO process, 22 779 Nozzle disk centrifuge... 

There are various methods for the determination of the size distribution of organic pigment particles, the most common are sedimentation techniques in ultracentrifuges and specialized disk centrifuges as well as electron microscopy. These methods require considerable experimental skill, since the results depend largely on sample preparation and especially on the quality of the dispersion. 

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