Agitated vs. non-agitated extractors
by Neil Sandford
Agitated liquid-liquid extractors include KARR®, SCHEIBEL®, reciprocating plate and pulsed columns. Rotating Disc Contactors, or RDCs, are also classified as “agitated.”
Non-agitated extractors may contain random or structured packing or perforated trays.
Liquid-liquid systems having interfacial tensions greater than 15 dynes/cm can benefit from agitation. With agitation in such systems, droplet sizes are smaller and real contact stages are more efficient.
Agitation is detrimental to liquid-liquid systems that have interfacial tension less than 15 dynes/cm. Droplet sizes are made too small, backmixing is exacerbated, efficiency suffers and capacity decreases.
Extractors that remove aromatics from C6 to C8 streams and from lube oil streams do not require agitation.
Need more information?