Centrifuge Based Separations

The use of centrifuges for isotope enrichment was suggested by Lindemann and Aston as early as 1919, but success required the development of vacuum centrifuges in the late 1930s. The rotors in such devices are suspended in vacuum chambers and gas is introduced and withdrawn through metal capillaries. Introductory discussions have been given by London (1961) and Benedict et al. (1981). 

In a centrifugal field the energy per mole at a distance r from the axis is M(cor2)/2. M is molecular weight and go angular velocity. The ratio of partial pressures for two isotopomers (primed and unprimed) at the wall, rw, and on the axis, ro, yields the elementary separation factor. 

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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 most common method to recover the spent beer from the yeast slurry is centrifugation. In this process, beer is separated from the yeast using a centrifuge, based on the difference in specific gravity between beer and yeast. The dry matter content of the centrifugally separated yeast is usually 22%-25%. An alternative method to recover the beer used by some breweries consists of mechanically pressing the yeast between sheets of cloth. 

When extremely small droplets are present in the gas, we can use separators with a glass-fiber coagulator that promotes droplet integration (Fig. 2.8). The final separation of enlarged drops occurs in the base separation section that can be made in form of a mesh stack (Fig. 2.8, a, d), a centrifugal construction (Fig. 2.8,... 

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