Liquid-Gas Mixtures

Bubbly mixture (gas-liquid, two-component system) Most of the earlier work on acoustic velocity, such as that of Hsieh and Plesset (1961), was based on the following assumptions. 

Henry, R. E., M. A. Grolmes, and H. K. Fauske, 1968, Propagation Velocity of Pressure Waves in Gas-Liquid Mixtures, Gas-Liquid Flow Symp., Waterloo University, Waterloo, Canada. (3)... 

Mass spectra can be recorded by using any one of several different systems of instrumentation. The inlet system can be either a hot reservoir inlet, a direct-probe inlet, or a gas-liquid chromatography (g.l.c.) inlet. The type of instrumentation and, especially, the inlet system may cause differences in the spectra recorded. However, with modern commercial instruments, these differences are generally small. Combined gas-liquid chromatography-mass spectrometry (g.l.c.-m.s.) has become increasingly important, and is particularly valuable for investigating complex mixtures. Gas-liquid chromatography of carbohydrates and their derivatives is the subject of articles in this Series. "... 

The activity coefficient is the most important and fundamental property in the thermodynamic study of liquid mixtures. It is a measure of the deviation of the behaviour of a component in a mixture from ideality and it has been interpreted by various theories of liquid mixtures. Gas-liquid elution chromatography offers a rapid method of determining this property at infinite dilution. Conder and Purnell have developed a method of determining activity coefiicients at finite concentrations and this has recently been used by other workers. " To do this, the elution technique must be supplemented by... 

When the mixture formed is an ideal mixture (gas, liquid, or solid), and the pure constituents have the same physical state as the mixture, the expressions for various molar mixing quantities are particularly simple. An ideal molar mixing quantity will be indicated... 

Lt liquid phase at terminal velocity condition mix mixture = gas + liquid + solid mf at minimum fluidization condition pmf particle at minimum fluidization condition... 

Gas-liquid mixtures are sometimes reacted in packed beds. The gas and the liquid usually flow cocurrently. Such trickle-bed reactors have the advantage that residence times of the liquid are shorter than in countercurrent operation. This can be useful in avoiding unwanted side reactions. 

When the two components are mixed together (say in a mixture of 10% ethane, 90% n-heptane) the bubble point curve and the dew point curve no longer coincide, and a two-phase envelope appears. Within this two-phase region, a mixture of liquid and gas exist, with both components being present in each phase in proportions dictated by the exact temperature and pressure, i.e. the composition of the liquid and gas phases within the two-phase envelope are not constant. The mixture has its own critical point C g. 

Solution calorimetry covers the measurement of the energy changes that occur when a compound or a mixture (solid, liquid or gas) is mixed, dissolved or adsorbed in a solvent or a solution. In addition it includes the measurement of the heat capacity of the resultant solution. Solution calorimeters are usually subdivided by the method in which the components are mixed, namely, batch, titration and flow. 

A second case to be considered is that of mixtures witli a small size ratio, <0.2. For a long time it was believed tliat such mixtures would not show any instability in tire fluid phase, but such an instability was predicted by Biben and Flansen [109]. This can be understood to be as a result of depletion interactions, exerted on the large spheres by tire small spheres (see section C2.6.4.3). Experimentally, such mixtures were indeed found to display an instability [110]. The gas-liquid transition does, however, seem to be metastable witli respect to tire fluid-crystal transition [111, 112]. This was confinned by computer simulations [113]. 

Gas-liquid chromatography has been widely used for the identification of reaction mixtures and for the separation of heterocycles. Some typical conditions are shown in Table 34. 

Gas-Liquid Mixtures An empirical equation was developed by Murdock [J. Basic Eng., 84, 419 33 (1962)] for the measurement of gas-liquid mixtures using sharp-edged orifice plates with either radius, flange, or pipe taps. 

Gases and liquids may be intentionally contacted as in absorption and distillation, or a mixture of phases may occur unintentionally as in vapor condensation from inadvertent cooling or liquid entrainment from a film. Regardless of the origin, it is usually desirable or necessary ultimately to separate gas-liquid dispersions. While separation will usually occur naturally, the rate is often economically intolerable and separation processes are employed to accelerate the step. 

The preferred catalyst is one which contains 5% of chromium oxides, mainly Cr03, on a finely divided silica-alumina catalyst (75-90% silica) which has been activated by heating to about 250°C. After reaction the mixture is passed to a gas-liquid separator where the ethylene is flashed off, catalyst is then removed from the liquid product of the separator and the polymer separated from the solvent by either flashing off the solvent or precipitating the polymer by cooling. 

A substance or any mixture of substances, which is flammable in air, when held above its boiling point (measured at 1 bar absolute) as a liquid or as a mixture of liquid and gas at a pressure >1.4 bar absolute. 

In heterogeneous systems AP must be critically reviewed, especially if the reaction involves a two-phase mixture of liquid and gas, or if the gas flows through a deep bed of catalyst particles as in the FCC systems. AP should be checked early in the design process to assess its influence on the overall plant integrity. 

Chlorooctane (14 9 g, 0 I mol), potassium fluoride dihydrate (47 g, 0 5 mol), hexadecyltributylphosphonium bromide (5 1 g, 0 01 mol), and water (30 mL) are mixed in an autoclave equipped with a magnetic stirrer and heated to 160 °C (bath temperature) for 7 h After this time gas-liquid chromatographic analysis (10% Carbowax 20M on Chromosorb) shows a 95% conversion to a mixture of 1-fluorooctane (82%), octenes (6%), and 1-octanol (7%) The organic layer is separated, washed with water, washed with concentrated sulfuric acid, washed once again with water, dried over calcium chloride, and distilled to give 10 g (77%) of ] -fluorooctane... 

The modern electronic industry has played a very important role in the development of instrumentation based on physical-analytical methods As a result, a rapid boom in the fields of infrared, nuclear magnetic resonance (NMR), Raman, and mass spectroscopy and vapor-phase (or gas-liquid) chromatography has been observed. Instruments for these methods have become indispensable tools in the analytical treatment of fluonnated mixtures, complexes, and compounds The detailed applications of the instrumentation are covered later in this chapter. 

The separation of mixtures involving N-methyl-JLtetrahydropyridines into their pure components by means of gas-liquid chromatography was discussed in a report by Holik et al. (87). They found that, using tris(/3-cyanoethoxymethyl)-y-picoline as the stationary phase, the primary factors involved in the specific retention volumes of these enamines is the electronic effect of a methyl substituent and the nitrogen atom on the carbon-carbon double bond. It was observed that 1,3-dimethyl-Zl -tetrahydropyridine (141) has a smaller specific retention volume and, hence, is eluted before... 

There are many mixtures of liquids that do not follow Raoult s Law, which represents the performance of ideal mixtures. For those systems following the ideal gas law and Raoult s Law for the liquid, for each component. 

Propane is a more reactive paraffin than ethane and methane. This is due to the presence of two secondary hydrogens that could be easily substituted (Chapter 6). Propane is obtained from natural gas liquids or from refinery gas streams. Liquefied petroleum gas (LPG) is a mixture of propane and butane and is mainly used as a fuel. The heating value of propane is 2,300 Btu/ft. LPG is currently an important feedstock for the production of olefins for petrochemical use. 

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