Hydrodynamics and mass transfer in a rotating disk supercritical extraction column

A novel rotating disk column (RDC) designed for high-pressure extraction was tested by extracting ethanol from aqueous solutions using supercritical carbon dioxide at 10 MPa and 313 K as a solvent. Mass-transfer efficiencies and hydraulic characteristics were measured as functions of a specific power input group ((NRH-1D-2)-R-3-H-5) and solvent-to-feed ratio. Agitation generally increased the value of the overall mass-transfer coefficient (K(od)alpha) and decreased the value of the height equivalent to a theoretical stage (HETS). The K(od)alpha values ranged from 0.006 to 0.015 s(-1), and the HETS values ranged from 0.37 to 0.8 m. The dispersed-phase drop size decreased with the agitator rotor speed. The measured values were between 1.3 and 1.8 mm. Agitation and increasing solvent flow rate increased the dispersed-phase holdup from 0.04 to 0.2. The measured slip velocities ranged from 0.08 to 0.14 m s(-1). The highest total throughput of the RDC column was approximately 74 m(3) h(-1) m(-2).