Reciprocating plate extraction tower

When there is no alternative to employing multiple extractions, chemical engineering approaches may afford more efficient operations in a pilot plant or manufacturing facility [10]. Many of these extractors are countercurrent devices, such as the Karr reciprocating plate tower, in which the light phase is continually fed into the bottom of the extractor while the heavy phase is fed into the top of the extractor. 

Figure 8.1.35. Schematic of various large-scale liquid-liquid extraction devices, (a) Packed tower for solvent extraction (b) sieve-plate extraction column (c) an early Scheibel column extraction design (d) Karr column, in which the plates have reciprocating motions (e) centrifugal extractor (f) porous hollow fiber membrane solvent extraction device (see Figure 8.1.13(a) for a detailed design).

Desirable motion can be imparted to the liquids by reciprocating motion of the plates rather than by pulsing the entire liquid mass. This mode employs much less power and provides equally good extraction efficiency. A 30 in. dia tower 20 ft high is sufficiently agitated with a 1.5 HP motor. Some arrangements of such extractors are shown in Figure 14.13. 

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