Development centrifugal

The simplest type of centrifugal device is the cyclone separator (Fig. 3.4), which consists of a vertical cylinder with a conical bottom. The centrifugal force is generated by the fluid motion. The mixture enters in a tangential inlet near the top, and the rotating motion so created develops centrifugal force which throws the particles radially toward the wall. 

Solid-Bowl Centrifuge The Bird solid-bowl centrifuge uses powder instead of gravity and can develop centrifugal forces up to 1800 times the force of gravity. It is therefore a unique type in classification practice. 

Highly developed centrifuges are used to enrich uranium for nuclear application (see Nuclear. REACTORS Uraniumand uranium compounds). Gaseous uranium hexafluoride, UF, is introduced into a very high speed tubular rotor, causing the lighter 235U-fraction to separate from that of the heavier 2 5U. 

As illustrated in Figure 10.7, a cyclone consists of a vertical cylinder with a conical bottom, a tangential inlet near the top, and outlets at the top and the bottom, respectively. The top outlet pipe protrudes into the conical part of the cyclone in order to produce a vortex when a dust-laden gas (normally air) is pumped tangentially into the cyclone body. Such a vortex develops centrifugal force and, because the particles are much denser than the gas, they are projected outward to the wall flowing downward in a thin layer along this in a helical path. They are eventually collected at the bottom of the cyclone and separated. The inlet gas stream flows downward in an annular vortex, reverses itself as it finds a reduction in the rotation space due to the conical shape, creates an upward inner vortex in the center of the cyclone, and then exits through the top of the cyclone. In an ideal operation in the upward flow... 

The US. Enrichment Corp. (USEC) is planning on using its own newly developed centrifuges for a pilot plant at Pikeston, OH, with the full-scale plant to be built at the existing Portsmouth, OH, site of the shutdown diffusion plant. 

Dinitrophenylhydrazine-Thiourea-Copper Sulfate Reagent. Dissolve 2 g. of 2,4-dinitrophenylhydrazine, 0.25 g. of thiourea, and 0.03 g. of CuS04.5HjO in 100 ml. of 9 JV HjSO, (3 volumes of distilled water to 1 volume of concentrated HjSOO. If a precipitate develops, centrifuge or filter through sintered glass. Store in a refrigerator and make up weekly. 

Flow injection analysis (FIA) was developed in the mid-1970s as a highly efficient technique for the automated analyses of samples. °> Unlike the centrifugal analyzer described earlier in this chapter, in which samples are simultaneously analyzed in batches of limited size, FIA allows for the rapid, sequential analysis of an unlimited number of samples. FIA is one member of a class of techniques called continuous-flow analyzers, in which samples are introduced sequentially at regular intervals into a liquid carrier stream that transports the samples to the detector. ... 

A new countercurrent continuous centrifugal extractor developed in the former USSR (214) has the feature that mechanical seals are replaced by Hquid seals with the result that operation and maintenance are simplified the mechanical seals are an operating weak point in most centrifugal extractors. The operating units range between 400 and 1200 mm in diameter, and a capacity of 70 m /h has been reported in service. The extractors have been appHed in coke-oven refining (see Coal conversion processes), erythromycin production, lube oil refining, etc. 

The Vepex process developed in Hungary (Table 9) involves disintegration of plant materials followed by double screw pressing to maximize juice production. Green chloroplastic protein is removed by direct steam-injection heat treatment at 82°C with the addition of flocculents and centrifugation. The white protein fraction is separated from the chlorophyU-free process juice by direct steam injection at 80°C, followed by centrifugation and drying (94). 

Booster Pump. Use of a centrifugal booster pump avoids a low intake pressure, particularly for large, high volume units. A low pressure (>26.6 kPa (200 mm Hg)) on the iatake of a timing pump can cause vaporization of the product. The booster pump is ia the circuit ahead of the timing pump and operates only when the FDV is ia forward flow, the metering pump is ia operation, and the pasteurized product is at least 7 kPa (1 psi) above the maximum pressure developed by the booster pump (Fig. 8). 

R. A. Leonard and co-workers. Development of a 25cmA.nnular Centrifugal Contactor, ANL-80-15, Argonne National Laboratory, Chicago, lU., June 1980. 

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