Pulsed extraction tower

Pulsed extraction towers have been used throughout the industry for many years. Pulsation is generated at the sump of the column using special piston pumps or compressed air. Extensions for phase settling are installed at the bottom and head of the column. The design of the column is rather difficult since back-mixing will occur with increasing diameters. 

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). 

Stagewise contact with controlled coalescence redispersion cycles Tray column Pulsed sieve column. Pulsed Mixer-Settler-cascade, Extraction tower with controlled cycle Scheibel column, ARD-Extractor, Leisibach column, Mixer-Settler cascade ... 

FIG. 15 53 Effect of pulsing on extraction in a packed column methyl isobutyl ketone-acetic acid-water (continuous). Tower diameter = 1.58 in, 27-in depth of V4-in Raschig rings. = Vc = 7.5 to 10. To convert inches to centimeters, multiply by 2.54. [Data of Chanhy, von Berg, and Wiegandt, Ind. Eng. Chem., 47, 1153 (1.9.55), with permission. ... 

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. 

Extraction equipment, 476-490 centrifugal, 484,487,490 comparison of types, 477 mixer-settlers, 477, 479 packed towers, 478,480,482,485 87 performance comparison, 478 pulsed towers, 481,483,487 REX2 (rotating disk contactor), 482, 487... 

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