The Pulsed Column Extractor or reciprocating columns extractor uses a reciprocating pump to create pulses of short amplitude that are superimposed on the usual flow of the liquid phases.
The column itself may contain packing or perforated plates. An increase efficiency of sieve-plate a packed extraction columns is obtained by applying a sinusoidal pulsation to the contents of the column.
The unique features of pulsed column extractor are low axial mixing and a relatively small increase in axial mixing with increase in column diameter.
The pulsation causes the light liquid to be dispersed into the heavy phase on the upward stroke and the heavy phase to jet into the light phase on the downward stroke.
The light and dense liquids passing counter currently through the columns are acted on by pulsations transmitted hydraulically from a dispersion of drops. The pulsation device is connected to the side of the column usually at the base though a pulse leg.
Pulsed Column Extractor is a more energy efficient way to obtain a phase dispersion. Reciprocating of plates requires less energy and has the same effect in terms of mixing patterns and uniform dispersion.
The difference between the different Pulsed column lies in the plate design. The open type Karr Column is the best known. Such columns have no moving parts, and found almost exclusive use in the processing of highly corrosive radioactive liquids.