Effect of two-liquid phases

Effect of two liquid phases on relief sizing equations... 

This example illustrates the effectiveness of two liquid-phase reactions in protecting unstable reactants and/or products from a reactive aqueous phase. In this case the protecting solvent was present in the feed stream from a previous step. In some cases, the protecting solvent is added for that purpose. 

Aromatic steroids are virtually insoluble in liquid ammonia and a cosolvent must be added to solubilize them or reduction will not occur. Ether, ethylene glycol dimethyl ether, dioxane and tetrahydrofuran have been used and, of these, tetrahydrofuran is the preferred solvent. Although dioxane is often a better solvent for steroids at room temperature, it freezes at 12° and its solvent effectiveness in ammonia is diminished. Tetrahydrofuran is infinitely miscible with liquid ammonia, but the addition of lithium to a 1 1 mixture causes the separation of two liquid phases, one blue and one colorless, together with the separation of a lithium-ammonia bronze phase. Thus tetrahydrofuran and lithium depress the solubilities of each other in ammonia. A tetrahydrofuran-ammonia mixture containing much over 50 % of tetrahydrofuran does not become blue when lithium is added. In general, a 1 1 ratio of ammonia to organic solvents represents a reasonable compromise between maximum solubility of steroid and dissolution of the metal with ionization. 

Two-phase electrolysis — Electrolysis of two-phase systems, esp. of two liquid phases. The usual case is that an organic compound is dissolved in a nonaqueous solvent and that solution, together with an aqueous electrolyte solution is forced to impinge on an electrode. The electrolysis reaction of the dissolved organic compound can proceed via a small equilibrium concentration in the aqueous phase, or it can proceed as a reaction at the three-phase boundary formed by the aqueous, the nonaqueous phase, and the electrode metal. A very effective way of delivering a two-phase mixture to an electrode is the use of a - bubble electrode. 

Extractor equipment considerations are discussed here in the context of their effect on the process performance and not for the purpose of describing detailed design. The main parameter of interest at this point is the number of equilibrium stages that represent the process. Liquid-liquid extraction requires thorough mixing of two liquid phases to achieve thermodynamic equilibrium, followed by complete separation of the phases. The particular equipment selected for a given process is determined, in part, by the mixing and separation characteristics of the phases. 

The selected solvent should have suitable physical and chemical properties (be immiscible, non-volatile, etc.), and be inexpensive and readily available (Deziel et al. 1999 Marcoux et al. 2000 MacLeod and Daugulis 2003). Furthermore, the possible interaction between the solvent and the enzyme has to be considered. It is important that the presence of the solvent does not interfere with the degradation of the target substrate (MacLeod and Daugulis 2003) and its effect on the enzyme activity be as low as possible (Ross et al. 2000). The development of solvent-resistant enzymes will facilitate the application of two-liquid phase biocatalysis. 

An attempt to consider the effect of small amounts of carbon on the C-Cu-Fe liquid phase using the thermodynamic analysis was made in [1976Wag]. When the dependence of liquidus temperature on concentration is small it indicates considerable positive deviations from ideal solution in case of the C-Cu-Fe system somewhat larger amounts of carbon result in the formation of two liquid phases. 

In the case of S/L interfaces, two different types can be postulated. The first interface is between a solid and its own liquid phase, such as that between ice and water. This type of interface is relatively easy to handle, and provides an insight into the fundamental features of S/L interfaces. The second interface is between a solid and a liquid of different composition. In many practical situations, the S/L interfaces belonging to the latter type are particularly important Note that the liquid phase sintering is carried out clearly below the melting point of the major solid phase. Here, the initial discussions relate to some of the essential features of S/L interfaces, derivable from the former type of S/L interface. The discussion can then easily be extended to the effect of a liquid phase of a different chemistry on the stmctures and energies of crystal surfaces. 

Considering the difficulty of observing the shape of the moving interface in the very vicinity of the contact line, the flow conditions on both sides of the interface, which demonstrate the effect of the contact line motion in visible dimensions, were investigated. The flow of two liquid phases contacting each other along one fluid interface in a capillary tube was carried out at a constant velocity. Velocity fields of both liquids were determined simultaneously at the moving interface in order to obtain some information about the effect of the motion of a meniscus on tube flow, its extension and the flow behaviour of the fluid interface itself. 

It was pointed out in Section XIII-4A that if the contact angle between a solid particle and two liquid phases is finite, a stable position for the particle is at the liquid-liquid interface. Coalescence is inhibited because it takes work to displace the particle from the interface. In addition, one can account for the type of emulsion that is formed, 0/W or W/O, simply in terms of the contact angle value. As illustrated in Fig. XIV-7, the bulk of the particle will lie in that liquid that most nearly wets it, and by what seems to be a correct application of the early oriented wedge" principle (see Ref. 48), this liquid should then constitute the outer phase. Furthermore, the action of surfactants should be predictable in terms of their effect on the contact angle. This was, indeed, found to be the case in a study by Schulman and Leja [49] on the stabilization of emulsions by barium sulfate. 

Effects of Two-Phase Vapor-Liquid Mixture on Relief Valve Capacity... 

Sizing, safety relief, 436, 437-441 API liquid valve, 444 Balanced valves, 441 Conventional valves, 438 Critical back pressure, 440 Effects of two-phase flow, 437 Hydraulic expansion, 441 Rupture disks, 434 Sub-critical flow, 449 Slurry flow, process pipe, 142-147 Regimes, 143... 

---