Centrifugal nozzle

A number of techniques have been evolved to disperse liquids in gases in the form of fine droplets. The various atomizing techniques are jet injections, fan sprays, centrifugal nozzles, twin fluid atomizers, impinging jets, and rotary... 

The centrifugal nozzle technique was developed by SwRI. It requires that, initially, both the core and the wall are pumpable liquids (or thin slurries). Both fluids are fed into a special nozzle so that a coaxial stream is formed at the nozzle. This nozzle is spun rapidly, which stretches out the liquid ligaments and breaks off individual droplets. Surface tension pull the shelf material around the core droplet to form a complete covering. The wall material must be selected so that it will solidify before fhe particle is collected. 

Centrifugal nozzle Two-fluid Three-fluid Sirens Whistles... 

I. Novikov, Atomization of liquids by centrifugal nozzles. Engineers Digest (British Edition), 10(3), 72-74 (1949). 

The density of heavy fuels is greater than 0.920 kg/1 at 15°C. The marine diesel consumers focus close attention on the fuel density because of having to centrifuge water out of the fuel. Beyond 0.991 kg/1, the density difference between the two phases —aqueous and hydrocarbon— becomes too small for correct operation of conventional centrifuges technical improvements are possible but costly. In extreme cases of fuels being too heavy, it is possible to rely on water-fuel emulsions, which can have some advantages of better atomization in the injection nozzle and a reduction of pollutant emissions such as smoke and nitrogen oxides. 

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. 

Disk machines having nozzles to discharge the soHds phase through small backward-pointing nozzles must have this power included in the calculations. Some thickening scroU centrifuges also use such nozzles, usuaUy with an intermittent flow. is the nozzle power ... 

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

Crea.m Yeast. At a 5% soHds concentration in the fermentor, the yeast occupies about 12% of the fermentor volume. It is harvested by centrifugation in nozzle centrifuges and washed several times with water. The final centrifugate is cooled and stored in refrigerated tanks. This yeast cream (so called because of its off-white color) may be sold directly in this form, since in large baking faciHties, it may be piped directly to any desired location. 

A second type of apparatus based on the pressure diffusion effect is the separation nozzle. Pressure gradients in a curved expanding jet produce an isotopic separation similar to that in a centrifuge. The separation effect obtained with a single jet is relatively small, and separation nozzle stages, similar to gaseous diffusion stages, must be used in a cascade to realize most of the desired separations. 

The thermocycle system can be operated only when condensing water is available at a temperature lower than the required chilled-water-supply temperature. Modifications for a centrifugal refrigeration unit include the installation of a small liqmd-refrigerant pump, cooler spray header nozzles, and a vapor bypass line between the cooler and the condenser. Without the compressor operating, a thermocycle capacity up to 35 percent of the refrigeration-unit rating can be produced. 

Spray dryers. Dryer feed must be copoble of otomization by either o centrifugal dish or o nozzle... 

Goldberg and Rubin [Ind. Eng. Chem. Proce.s.s Des. Dev., 6 195 (1967)] showed in tests with a disk spinning vertically to the foam layer that most mechanical procedures, whether centrifugation, mixing, or blowing through nozzles, consist basically of the application of shear stress. Subjecting foam to an air-jet impact can also provide a source... 

The first three types, including the manual-discharge disk, are batch-feed centrifuges, whereas the latter three, including the intermittent and nozzle-discharge disks, are continuous centrifuges. 

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),... 

Centrifugal pumps also rec]uire that the fluid be available to the pump s suction nozzle with sufficient energy. Centrifugal pumps cannot suck or draw the liquid into the pump housing. The principal pumping unit of a centrifugal pump is the volute and impeller. (See Figure 1-3). 

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