Perforated-plate towers

Both packed and perforated plate towers are in use. The most... 

Perforated-plate towers, 651-652, 662, 681 (See also Sieve trays)... 

Countercurrent columns with additional kinetic energy input have found a broad range of industrial applications [42-48]. Examples of extraction towers with energy input are pulsed towers, pulsed packed columns and pulsed perforated-plate towers. A number of units with some form of mechanical agitation are also used (Karr column, Scheibel column, Oldshue-Rushton column, Ktihni column, RZE extractor, RDC and ARD extractor, Graesser contactor). 

In the second scheme, brine is fed to a rubber-lined steel tank packed with graphite along with caustic to ensure conversion of chlorine to H0C1 and/or OC1 . Alternately, aeration in a perforated plate tower may be employed to dechlorinate the depleted brine as shown by Yokota.35 36... 

Perforated-plate Towers. In the perforated-plate, or sieve-plate, column, the dispersed phase is repeatedly coalesced and redispersed by causing it to flow through a series of trays in which a large number of small holes have been punched or drilled. In the simplest type, the plates are similar to the side-to-side baffles described above, except that they are perforate. Hunter and Nash (42) describe a successful installation of this type for dephenolating gas liquor consisting of a 46-ft,-high shell, 5 ft. in diameter, in which the baffles each contain two hundred holes. 

Perforated-plate Towers. Flooding of these towers may occur either because of inability to maintain an interface at the end of the tower or because of thickening of the layers of dispersed phase on the plates. Tend-... 

Fig. 10.18. Hold-up in a perforated-plate tower (2). Kerosene dispersed, Ud continuous.

Figure 10.18 shows a comparison of the hold-up of dispersed phase in a small perforated-plate tower (2) with that calculated by the methods described. The measured data include the hold-up owing to dispersed phase droplets rising through the continuous phase and is consequently higher than the calculated hold-up, but the trend of the data is followed very well. The observations of several experimenters (2, 60, 70, 81) that the thickness of the layer of dispersed phase is apparently independent of dispersed phase flow rate can be shown to be due to the small numerical value of Ao for these cases. 

Fig. 10.19. Flow capacities of perforated-plate towers. G = greatest reported, F flooded.

Table 10.5. Extraction with Perforated-plate Towers... 

Almost all countercurrent extraction devices utilize dispersion of one immiscible phase as drops in another immiscible phase we will provide a brief introduction here. At the end, we will introduce porous hollow fiber membrane based nondispersive countercurrent solvent extraction devices. The dispersive devices may involve continuous agitation or no agitation at all. Dispersive devices without any agitation as such are of three types spray towers packed towers perforated plate towers. Spray towers were illustrated in Figure 8.1.2(b). 

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