Three-phase mixtures

Entrained Sohds Bubble Columns with the Sohd Fluidized by Bubble Action The three-phase mixture flows through the vessel and is separated downstream. Used in preference to fluidized beds when catalyst particles are veiy fine or subject to disintegration in process. 

The other place where the constitution is not fully defined is where there is a horizontal line on the phase diagram. The lead-tin diagram has one line like this - it runs across the diagram at 183°C and connects (Sn) of 2.5 wt% lead, L of 38.1% lead and (Pb) of 81% lead. Just above 183°C an alloy of tin -i- 38.1% lead is single-phase liquid (Fig. 3.5). Just below 183°C it is two-phase, (Sn) -i- (Pb). At 183°C we have a three-phase mixture of L -I- (Sn) -I- (Pb) but we can t of course say from the phase diagram what the relative weights of the three phases are. 

Fig. 3.5. At 1 S3°C we have a three-phase mixture of L + (Sn) + (Pb). Their relative weights can t be found from the phase diagram.

For other special cases (multiple liquid-phases and three-phase mixtures of vapour, liquid and suspended solids) advice is given in Chapter 10 on the applicability of the above methods. 

The checkers observed the separation of a heavy, white precipitate presumed to be a borate salt during the addition of hydrogen peroxide. After the three-phase mixture had been stirred at room temperature for 3 hr, the liquid layers were decanted into a separatory funnel. The solid remaining in the flask was washed with two 75-mL portions of ether and these washings were used to extract the aqueous layer. 

Displaying a grasp of chemistry remarkable even among chemical engineers, the authors ascribe the hazardous side reaction consequent upon mono-nitration of toluene in mixed acid, to a decomposition of nitric acid (science has hitherto regarded nitric acid as thermodynamically more stable than conceivable decomposition products). This is favoured by poor mixing in what they describe as a three phase mixture (m/xo-nitrotoluenes being apparently immiscible with toluene). What the calorimetric study described seems to have observed is the transition from nitration to oxidation of the substrate. 

Emulsions and suspensions are colloidal dispersions of two or more immiscible phases in which one phase (disperse or internal phase) is dispersed as droplets or particles into another phase (continuous or dispersant phase). Therefore, various types of colloidal systems can be obtained. For example, oil/water and water /oil single emulsions can be prepared, as well as so-called multiple emulsions, which involve the preliminary emulsification of two phases (e.g., w/o or o/w), followed by secondary emulsification into a third phase leading to a three-phase mixture, such as w/o/w or o/w/o. Suspensions where a solid phase is dispersed into a liquid phase can also be obtained. In this case, solid particles can be (i) microspheres, for example, spherical particles composed of various natural and synthetic materials with diameters in the micrometer range solid lipid microspheres, albumin microspheres, polymer microspheres and (ii) capsules, for example, small, coated particles loaded with a solid, a liquid, a solid-liquid dispersion or solid-gas dispersion. Aerosols, where the internal phase is constituted by a solid or a liquid phase dispersed in air as a continuous phase, represent another type of colloidal system. 

The conditions under which CO gas bubbles form and the reaction scale fractures depend on the relative permeabilities of CO and oxygen through the reaction scale, which typically consists of a three-phase mixture of mullite, alumina, and an aluminosilicate glass. If the CO permeability is greater than... 

Chloromethylated polystyrene-DVB (2.5 g) (1.23 meq/g) and 2 g of thiourea were refluxed with a mixture of THF ethanol (2 1) for 48 hr. The resin was then washed with water, followed by THF and benzene, to remove all excess soluble reagents and byproducts. The resin was then suspended in a 50 ml of benzene and 0.1 g of tetraheptylammonium chloride and 2 g of sodium hydroxyde in 10 ml of deionized and degassed water were added. The three-phase mixture was refluxed under N2 for 48 hr. After filtration, washings with THF, water, THF 6N HC1 (3 1), water, THF, acetone, methylene chloride, and finally methanol were carried out. The resulting resin was dried under vacuum. 

Consider, for example, a three-phase mixture of corundum, magnetite and zircon. Such a sample was presented as Sample 4 in the lUCr CPD round robin on quantitative phase analysis. Its components were chosen with the deliberate aim of creating a sample in which severe microabsorption occurs. Table 11.3 shows the weighed amounts of each component and the results of replicate analyses of three different sub-samples of this material. 

A Simple Three-phase Mixture. The first sample of the lUCr CPD round robin on QPA summarized the results obtained from the analysis of a... 

Formulate the equations for the determination of the dew point of a three phase mixture in terms of 2c -f 2 independent functions and 2c + 2 independent variables. 

Thus, to determine the thermodynamic properties per unit mass of a single-component, two-phase mixture, we need to specify the equivalent of one single-phase state variable (the one degree of freedom) and one variable that provides information on the mass distribution. The additional specification of one extensive property is needed to determine the total mass or size of the system. Similarly, to fix the thermodynamic properties of a single-component, three-phase mixture, we.need not specify any single state variable (since the triple point is unique), but two variables that provide information on the distribution of mass between the vapor, liquid, and solid phases and one extensive variable to determine the total mass of the three-phase system. 

The momentum balance of the three phase mixture reads, neglecting inertia terms reads (see e.g. Hutter et al. (1999))... 

Materials development for syngas and combustion is ongoing. There has been a tremendous effort in the development of both single-phase materials with multiple co-doping and different manufacturing methods, as well as efforts in the development of dual and even three-phase mixtures to overcome the substantial difficulties associated with operating ceramic membranes in the harsh conditions of a syngas device. Similarly, architecture developments continue to improve the robustness of the devices as well as to lower the cost of production. Work in both areas continues, and more developments will be made. 

Rheology is the study of material flow behaviour. The fluids referred to in the range of mixing problems discussed in section 1.1 cover an enormous variation of rheological properties. The possibilities are extended further when two- and three-phase mixtures, especially stable ones which are products of mixing operations such as emulsions, foams and dispersions are included. There are many books available which deal with this topic in some detail All that is presented here is sufficient to allow the reader to understand better those parts of later chapters which refer to rheologically-complex fluids. 

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