The Podbielniak Contactor, popularly known as the "Pod," is a liquid-liquid centrifugal extractor and separator providing differential countercurrent extraction in a compact hermetic rotor.
The Podbielniak contactor is a horizontally mounted centrifuge. The Podbielniak has perforated, concentric cylindrical bands that fit into grooves on the rotor at one end and the endplate at the other.
The rigid inner shaft supports the rotor, and also provides the ports that serve as process liquid inlets and outlets. The shaft is drilled almost to the center from each side, but not through.
There is a central channel and an annular channel on both the sides. This provides the four channels needed for process liquid flow.
The heavy liquid (HLI) is introduced near the shaft, and the light liquid (LLI) is introduced near the rim of the rotor. As a result of the centrifugal force and density difference, the heavy liquid is forced out to the rim.
As the heavy liquid propagates through the perforations, it displaces an equal volume of light liquid towards the shaft. The two liquids flowing countercurrently are forced to pass each other through the perforations on each band, leading to intense contact.
The light liquid is collected at the shaft (LLO), and the heavy liquid is collected at the rim (HLO). This countercurrent series of dispersion and coalescence allows multi-stage extraction.