Present-day challenges, such as sustainability and energy demands, have pushed toward developing new separation technologies, including the application of centrifugal fields. In solvent extraction (SX), numerous centrifugal extractors have been commercialized, among which the family of annular centrifugal extractors (ACCs) is currently the most applied, covering essential fields like rare earth and biotechnology1. ACCs consist of two coaxial cylinders, an outer stationary housing and an inner rotor, which confine in-between an annulus chamber. Inside the annulus, two phases are vigorously mixed upon contact with the spinning surface of the rotor, which then separates the dispersion under centrifugation. Offering fast efficient processes, compactness and flexibility, ACCs not only intensify SX but also represent promising candidates for the modern modular plants.
Despite that, ACCs industrial implementation is not up to their potential2. Major reasons to blame are their complex operation and the interconnected influences of operational variables that are difficult to resolve. Additionally, the literature lacks versatile models that allow practical handling of ACCs3. To bridge this gap, this contribution introduces a procedure to define the operation window of ACCs that specifies the feasible ranges of operational variables to accomplish an SX task. The procedure is intended to be general to apply to any ACC, and practical to enable informed operation of ACCs even without full comprehension of their complexities.
The concept of the procedure is based on two independent studies. The first focuses on the rotor, where separation occurs, and defines its operable region via hydraulic tests. The second addresses the annulus, where mass transfer happens, and defines its operable region via stage efficiency modeling. By intersecting both regions, the operation window results ensuring successful execution of the task in terms of mass transfer and phase separation. It also shows the maximum achievable throughput and how to realize it, enabling the full potential of ACCs. The entire concept is converted into an interactive user-interface software that will be shared and explained in this contribution.
[1] Hamamah ZA, Grützner T. Liquid–Liquid Centrifugal Extractors: Types and Recent Applications – a Review. ChemBioEng Reviews. 2022;9(3):286-318. doi:10.1002/cben.202100035
[2] Leonard RA. Design Principles and Applications of Centrifugal Contactors for Solvent Extraction. In: Moyer BA, ed. Ion Exchange and Solvent Extraction. Vol 19. Ion exchange and solvent extraction series. CRC Press; 2010:584-637.
[3] Hamamah ZA, Grützner T. Development of a procedure for defining the operation window of annular centrifugal contactors. AIChE Journal. Published online August 21, 2024:e18580. doi:10.1002/aic.18580