Separation, multi-phase

Grolmes, M. A. and Fauske, H. K., An Evaluation of Incomplete Vapor-Phase Separation in Freon-12 Top Vented Depre-ssurization Experiments, Multi-Phase Flow and Heat Transfer III. Part A Fundamentals. Proceedings of the Third Multi-Phase Flotv and Heat Transfer Symposium-Workshop, Miami Beach, FL, April 18-20, 1983. 

The performance of the Sonogashira reaction is claimed to be the first example of a homogeneously metal-catalyzed reaction conducted in a micro reactor [120], Since the reaction involves multi-phase postprocessing which is needed for the separation of products and catalysts, continuous recycling technology is of interest for an efficient production process. Micro flow systems with micro mixers are one way to realize such processing. 

A bench-scale settler was used in an experimental study to assess continuous biodesulfurization operation to separate oil and water + biocatalyst [260], The design was based on a viton tubing settler surface placed at an angle to allow separation of the multi phase mixture. The device was reported to operate with over 95% efficiency for first 24 hours after which the performance reduced drastically. 

Panday, S. and Corapcioglu, M. Y., 1994, Theory of Phase-Separate Multi-Component Contamination in Frozen Soil Journal of Contaminant Hydrology, Vol. 16, pp. 235-269. 

Systematic solubility measurements of organometallic transition metal precatalysts were performed in our laboratories as part of the ConNeCat activities [25]. These activities focus on a multi-phase approach, in which product separation is to be achieved by a thermally or pressure-controlled phase separation, while the catalyst is completely precipitated. 

These multi-phase approaches, however, suffer from the drawback that some of the reaction media must be separated from the catalyst or the reaction products. Therefore, the conditions of catalyst separation may be very different from those of the reaction such that catalyst decomposition may still occur. Furthermore, most approaches have two or three phases during the reaction, which may cause problems in controlling the phase equilibria and in controlling the distribution of the reacting components and the catalytically active component between the phases. Most effective agitation of the reaction mixture is often required. 

Table 1 Multi-phase catalysis approaches with respect to both, reaction and separation conditions (S substrates, P products)...

Fig. 20 Reaction/separation strategies for multi-phase catalysis in SCCO2...

By multi-phase transient experiments , we mean those such as cyclic voltammetry (see Chap. 3) or current reversal chronopotentiometry [33] in which some sudden charge is made in the imposed conditions at some definite time (t = r, for example) after the experiment commences. To address such multiphase experiments, one usually treats each phase separately, the solution of the first phase providing details of the concentration profiles at t — t, which then serve as the initial conditions for the second phase. Likewise, the final conditions of the second phase provide the initial conditions for the third phase, if any, and so on. 

Nanoparticles are frequently used as a suspension in some kind of solvent. This is a two phase mixture of suspended solid and liquid solvent and is thus an example of a colloid. The solid doesn t separate out as a precipitate partially because the nanoparticles are so small and partially because they are stabilised by coating groups that prevent their aggregation into a precipitate and enhance their solubility. Colloidal gold, which has a typical red colour for particles of less than 100 nm, has been known since ancient times as a means of staining glass. Colloid science is a mature discipline that is much wider than the relatively recent field of nanoparticle research. Strictly a colloid can be defined as a stable system of small particles dispersed in a different medium. It represents a multi-phase system in which one dimension of a dispersed phase is of colloidal size. Thus, for example, a foam is a gas dispersed in a liquid or solid. A liquid aerosol is a liquid dispersed in gas, whereas a solid aerosol (or smoke) is a solid dispersed in a gas. An emulsion is a liquid dispersed in a liquid, a gel is liquid dispersed in a solid and a soils a solid dispersed in a liquid or solid. We saw in Section 14.7 the distinction between sol and gel in the sol gel process. 

Gas-liquid bubble columns and gas-liquid-solid slurry bubble columns are widely used in the chemical and petrochemical industries for processes such as methanol synthesis, coal liquefaction, Fischer-Tropsch synthesis and separation methods such as solvent extraction and particle/gas flotation. The hydrodynamic behavior of gas-liquid bubble columns and gas-liquid-solid slurry bubble columns are of great importance for the design and scale-up of reactors. Although the hydrodynamics of the bubble and slurry bubble columns has been a subject of intensive research through experiments and computations, the flow structure quantification of complex multi-phase flows are still not well understood, especially in the three-dimensional region. In bubble and slurry bubble columns, the presence of gas bubbles plays an important role to induce appreciable liquid/solids mixing as well as mass transfer. The flows within these systems are divided into two... 

A series of pyrrolidines was conveniently prepared in a microwave-assisted double alkylation of aniline derivatives with alkyl dihalides in water in the presence of K2CO3 as a base (Scheme 1) [12,13]. Although the reaction mixture could be regarded as a multi-phase system, as neither reactant was soluble in the mildly basic aqueous medium, the microwave-assisted reaction proceeded readily without the use of phase-transfer reagents. The amount of side-reactions such as hydrolysis of bromides to alcohols in an alkaline reaction medium was substantially suppressed compared to the conventional thermal conditions. The reaction conditions were sufficiently mild to tolerate a variety of functional groups in anilines such as hydroxyls, ketones and esters. Alkyl bromides and tosylates were equally efficient as alkylating agents. Notably, isolation and purification comprised simply of phase separations (filtration or decantation) of the desired product from the aqueous media. 

The aim of crystallization is to separate the observed component into higher quality crystals. The crystal size and probability density distribution of its size become very important factors for the product or the following processes. Although multi-phase mixing is fairly common in industries, there have been few investigations on the mixing performance of operations/equipment. In crystallization operation, the assumption of MSMPR has been used to design a crystallizer without a detailed discussion. Therefore, the assumption of MSMPR must be studied quantitatively. 

Characterization of the poly(macromonomers) prepared by homopolymerization has proved that they provide a useful probe for discussing the structural characteristics of the star and brush polymers. Graft copolymers have been and will be a most important area of application of the macromonomer technique since a variety of multi-phased and microphase-separated systems can easily be designed just by an appropriate combination of a macromonomer and a conventional monomer. In general, however, characterization of their absolute MW, branch/backbone composition as well as their distributions remain to be studied in more detail. 

The solution to a multi-component, multi-phase, multi-stage separation problem is found in the simultaneous or iterative solution of the material balances, the energy balance and the phase equilibrium equations (see Chapter 1). This implies that a sufficient number of design variables are specified so that the number of remaining unknown variables exactly equals the number of independent equations. When this is done, a separation process is said to be specified. 

The solution behavior of polymers has been intensively investigated in the past. Dilute solutions, where polymer-polymer interactions may be excluded, have become the basis for the characterization of the primary structure of macromolecules and their dimensions in solution. Besides this "classical" aspect of macromolecular science, interest has focussed on systems, where - due to strong polymer/polymer interactions - association of polymers causes supermolecular structures in homogeneous thermo-dynamically-stable isotropic and anisotropic solutions or in phase-separated multi-component systems. The association of polymers in solutions gives rise to unconventional properties, yielding new aspects for applications and multiple theoretical aspects. 

G. L. Steffens). A number of other scientists made major contribution to the program, as will be shown. It was a multi-phase project and each phase will be discussed separately although several phases were usually being conducted simultaneously. 

The effect of 31 stationary phases on the relative volatility of silicon tetrachloride and methylchlorosilanes has been examined398 on firebrick containing the various stationary phases. 2-Chloroethyl ether, ethyl chloroacetate and 1,1,3-trichloropropane were found suitable for separating multi-component mixtures. 

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