Extraction perforated plate towers

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). 

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). 

Perforated-plate extraction towers (a) perforations in horizontal plates (f>) cascade weir tray with mixing and settling zones. After Bushell and Fiocco. )... 

A continuous version of-this process is used in Germany (Rg. 15-27). Molten caprolactam, catalyst, and stabilizer are metered into the top of a tower heated to 25Q-260°C by a heat-exchange liquid and maintained at atmospheric pressure. The product slowly passes down through perforated plates in the column as polymerization occurs and is continubusly drawn off at the bottom and metered to spinning machines. This product contains 10 per cent monomer, and the final fiber must be extracted to remove the monomer. 

Phenol Process (4, 37A, 154, 155, 156). Phenol is used at a sufficiently high temperature (= 200 F.) to permit treatment of oils of high viscosity and wax content. Early installations used separate stage contactors, but modern plants have packed or perforated-plate countercurrent towers. The solvent is used either substantially dry or with water injection into the extract end of the extractor to reduce oil solubility and induce extract reflux. The latter is used in the newer plants, according to the flowsheet of Fig. 11.17. 

Figure 12.6-2. Extraction towers (a) perforated-plate or sieve-tray tower, b) agitated extraction tower.

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