Dispersed phase hold-up, effective interfacial area and Sauter mean drop diameter in annular centrifugal extractors

Abstract

Annular centrifugal extractors (ACE), based on the principle of Taylor-Couette flow, offer potential advantages over the existing conventional extraction equipments in many of the engineering applications. In the present work, dispersed phase hold-up (∈_D) and effective interfacial area (a̲) have been measured in 30, 75 and 250 mm rotor diameter annular centrifugal extractors over a wide range of power consumption (0.4 < P/V < 500, kW/m³) and physical properties (900 < ρ_C < 1300, kg/m³; 600 < ρ_D < 1600, kg/m³; 0.84 < μ_C < 10, mPa s; 0.6 < μ_D < 27, mPa s; and 2.2 < σ < 58, mN/m). From these measurements, Sauter mean drop diameter (d_3,2) has been estimated. Suitable correlations have been proposed for ∈_D, a̲, and d_3,2, which are expected to be useful for practicing engineers. Power consumption was also measured for 40, 60 and 100 mm diameter rotors and an appropriate and simple correlation for power number for ACE has been proposed.