Phase Equilibria in Fluid Mixtures at High Pressures

Abstract

The six types of phase behaviour observed in binary mixtures are described briefly. Liquid-liquid immiscibility in Type II and Type III phase behaviour is discussed in terms of pressure-temperaturecomposition diagrams. The conditions for the coexistence of two phases and the conditions for a critical point in both binary and ternary mixtures are presented. The criticality conditions are given in terms of both the Gibbs and Helmholtz functions. Methods for calculating high pressure equilibrium in fluid mixtures using these conditions together with a one fluid model are discussed. The use of empirical and theoretically based equations of state to calculate the Helmholtz function are briefly reviewed and the need for caution when using this approach is pointed out. Finally the need for a classification for the phase behaviour of ternary mixtures and for liquid-liquid equilibrium data of higher accuracy are considered.

Three-Dimensional Scheme of Supercritical Carbon Dioxide Extraction of Heavy Hydrocarbon Mixture in (Pressure; Temperature; Recovery) Coordinates

“…The experimental results of the current study were plotted in Figure 3 as pressure, P (MPa), versus recovery, R (%). They are also shown in a threedimensional scheme in Figure 4 to help to view the entire system 16 in the range of measured pressures and temperatures. Upon extraction, the samples differed by color, temperature, the character of flow, and other specific features, signifying the complex phase behavior of the system.…”

Extraction of cottonseed oil using subcritical water technology

“…Schneider suggested the extension of wet air oxidation to higher temperatures for disposal of organic materials. 5 In the early 1970s, the properties of super-critical fluids (e.g., changes in solubility and diffusivity with temperature and pressure) were discovered at Max Planck Institute. 6 Since 1982 many patents by General Atomics Company (GA) including reactor designs, solids handling, effluent quenching, reaction rate enhancers, heat transfer, and corrosion resistant materials have been developed.…”

“…12,13 The essential oil from plants has been extracted by using subcritical water. Usually the oil in these plants is traditionally extracted either using steam distillation 5,6 or solvent extraction. [12][13][14][15] These techniques present some shortcomings, namely losses of volatile compounds, low extraction efficiency, long extraction time, degradation of unsaturated compounds, and toxic solvent residue.…”

Spent Bleaching Earth Treatment in a Pilot Scale Tubular Reactor using Subcritical Water Technology

“…In 1999, HiroyukiYoshida, showed that a relatively large amount of oil, organicacids, and amino acids could be extracted from fish, squid entrails and meat wastes by sub-critical water treatment [9,10].The essential oil from plants has been extracted by usingsub-critical water. Usually the oil in these plants is traditionally extracted either using steam distillation [11,12] or solventextraction [13][14][15]. These techniques present some shortcomings,namely losses of volatile compounds, low extraction efficiency, long extraction time, degradation of unsaturated compounds, and toxic solvent residue.…”