High-pressure density and vapor-liquid equilibrium for the binary systems carbon dioxide-ethanol,carbon dioxide-acetone and carbon dioxide-dichloromethane

摘要

An apparatus for the measurement of vapor-liquid equilibrium (VLB,P-T-x) data and density of saturated-liquid and high-pressure liquid phase of compressed gas-organic solvent systems was designed,built and tested.A synthetic method,with recirculation of the liquid phase through a high-pressure densimeter by a magnetic driven centrifugal pump,was used.The thermodynamic equilibrium was reached in a visual cell with variable volume ranging between 30 and 60 cm~3.The compositions of the phases were evaluated by external gravimetric method.The estimated accuracy of the measured data was ±0.02 K for temperature,±0.05 MPa for pressure,±0.005 in mole fraction for liquid compositions and ±0.05 g/L for liquid density.Vapor-liquid equilibrium data and saturated-liquid density were obtained for the following systems:carbon dioxide-ethanol and carbon dioxide-acetone at 291.15,303.15,313.15 and 323.15 K and carbon dioxide-dichloromethane at 291.15,303.15 and 311.15 K.For the latter system,high-pressure liquid density data were measured up to 18 MPa.The experimental data were correlated by both Peng-Robinson and SAFT equation of state.SAFT EOS gives better correlations of vapor-liquid data and accurate predictions of high-pressure density of the liquid phase.