Phase Separation and Flow

Most polymer blends phase-separate with LCST thus the miscibility region stretches from the melting point or Tg up to the binodal while the phase-separated region exists above the spinodal temperature, Ts [1, 212]. Within the region between binodal and spinodal the system is metastable, characterized by strong interrelation between the rheology and thermodynamics [211, 213-215]. 

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The second type of mass-exchange units is the differential (or continuous) contactor. In this category, the two phases flow through the exchanger in continuous contact throughout without intermediate phase separation and recontacting. Examples of differential contactors include packed columns (Fig. 2.6), spray towers (Fig. 2.7), and mechanically agitated units (Fig. 2.8). 

Vary the backmixing flows for each phase separately and notice the effect of changes in conditions between plug flow and full backmixing on the performance of the extractor. 

Jou, D., Casas-Vazquez, /. and Criado-Sancho, Af. Thermodynamics of Polymer Solutions under Flow Phase Separation and Polymer Degradation. VoL 120, pp. 207-266. 

In these models the phases are treated as if they are separate and flow in well defined but unspecified parts of the cross section. Only the simplest case, in which the phases are allowed to have different but uniform velocities, will be considered here. An overall momentum equation will be given and it will be seen that merely allowing the gas and liquid velocities to differ leads to considerable complexity. Two empirical correlations from the pioneering work of Martinelli and co-workers will then be described. These methods can be used for the churn and annular flow regimes. 

Fig. 9.8 Sections of several stirred countercurrent columns. Horizontal stator baffles divide the column into successive sections, each fitted with a mixer, aU fixed to a central shaft. The mixers disperse one phase into droplets and mix the two phases in the section as efficiently as possible. The stator baffles must support the phase separation and the countercurrent flow of the liquids from state to stage.

R-P separation of alkaloids Quaternary mobile phase composition and flow rate 81)... 

The mixture exits the coil(s) and flows into the separation chamber where the solvent and water mixture is separated by gravity. The lighter water phase rises and flows through the upper outlet. The solvent phase is heavier and flows down through the main body of the extractor. A portion of it fills the float chamber, and the rest flows into the distillation chamber. Because they are... 

Vertical separators. Fig. 4 shows a typical configuration for a vertical three-phase separator. As flow enters the vessel, the inlet diverter separates most of the gas. A downcomer is required to transmit the liquid through the oil/gas interface so not to disturb the oil-skimming action taking place. A chimney is needed to equalize gas pressure between the lower section and the gas section. 

Reactive extraction processes involve simultaneous reaction and liquid-liquid phase separation and can be effectively utilized to obtain significant improvements in yields of desired products and selectivities to desired products in multireaction systems, thereby reducing recycle flows and waste formation. The combination of... 

G. ver Strate and W. Philippoff, Phase separation in flowing polymer solutions, Polym. Lett. Ed., 12, 267 (1974). 

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