MASS-TRANSFER AND HYDRAULIC CHARACTERISTICS IN SPRAY AND PACKED EXTRACTION COLUMNS FOR SUPERCRITICAL CARBON-DIOXIDE ETHANOL-WATER SYSTEM

Mass-transfer efficiencies and hydraulic characteristics of a 3.18-cm spray and a packed column for extracting ethanol from aqueous ethanol solution with supercritical carbon dioxide were investigated. Experime nts were performed at 308.2, 313.2, and 323.2 K over a pressure range from 9.1 to 12.2 MPa. The influences of fluid properties, phase flow r ates, column internals, and phase dispersion on mass-transfer efficien cies and hydraulic characteristics are discussed. An extension of a mo del for predicting mass-transfer efficiency in conventional liquid-liq uid extraction to supercritical-fluid extraction was attempted. The mo del for mass-transfer efficiencies, developed for conventional spray a nd packed liquid-liquid extraction columns, was in good agreement with our experimental results.