Hydraulic performance and mass transfer efficiency of engineering scale centrifugal contactors

Annular centrifugal contactors (ACCs) are being evaluated for process scale solvent extraction operations in support of Advanced Fuel Cycle Initiative (AFCI) separations goals. Process scale annular centrifugal contactors have the potential for high stage efficiency if properly employed and optimized for the application. Hydraulic performance issues related to flow instability and classical flooding in mini-contactors are likely less prevalent, especially for units with high throughputs. However, annular mixing increases rapidly with increasing rotor diameter under similar operating regimes. For large contactors, elevated rotor speeds and/or throughput rates, can lead to organic phase foaming at the rotor discharge collector area. Foam buildup can aspirate vapor from the contactor housing resulting in a complete loss of separation equilibrium. Proper venting of larger contactors is required to balance pressures across individual stages and prevent vapor lock due to foam aspiration. Testing of commercial 5 and 12.5 cm contactors to determine two phase hydraulics and operating ranges on several solvent pairs was completed. Evaluation of performance on the extraction, scrub, and strip sections of a Transuranic Extraction (TRUEX) process demonstrated good phase separation within the operating range. Mass transfer testing using stable cerium and europium was completed providing single stage extraction efficiencies above 95%.