Mixture composition

Rate equations 28 and 30 combine the advantages of concentration-independent mass transfer coefficients, even in situations of multicomponent diffusion, and a familiar mathematical form involving concentration driving forces. The main inconvenience is the use of an effective diffusivity which may itself depend somewhat on the mixture composition and in certain cases even on the diffusion rates. This advantage can be eliminated by working with a different form of the MaxweU-Stefan equation (30—32). One thus obtains a set of rate equations of an unconventional form having concentration-independent mass transfer coefficients that are defined for each binary pair directiy based on the MaxweU-Stefan diffusivities. 

An important use of the triangular equiHbrium diagram is the graphical solution of material balance problems, such as the calculation of the relative amounts of equiHbrium phases obtained from a given overall mixture composition. As an example, consider a mixture where the overall composition is represented by point M on Figure 2a. If the A-rich phase is denoted by point R (raffinate) and the B-rich phase is denoted by point E (extract), it can be shown that points R, M, and E are coUinear, and also... 

Samples can be removed for analysis, phase volumes can be measured to determine mixture composition and molar volumes (70), and phase boundaries can be measured. Many different configurations of view cells have been proposed. Some are capable of pressures ia excess of 100 MPa (14,500 psi). The cell coateats may be viewed safely through the sapphire wiadow by use of a mirror, video camera, or borescope. 

Numerous other reactions of this type, including a sequence involving HO2, exist and the relative importance of each reaction depends on the mixture composition. The rates of these termolecular processes increase with increasing pressure but have Httle or no temperature dependence. 

For example, in a laminar or PoiseuiEe flow in a round tube of radius for a given initial mixture composition, flashback (or blowoff)... 

Operational Considerations. The performance of catalytic incinerators (28) is affected by catalyst inlet temperature, space velocity, superficial gas velocity (at the catalyst inlet), bed geometry, species present and concentration, mixture composition, and waste contaminants. Catalyst inlet temperatures strongly affect destmction efficiency. Mixture compositions, air-to-gas (fuel) ratio, space velocity, and inlet concentration all show marginal or statistically insignificant effects (30). 

A mixing rule developed by Kendall and Monroe" is useful for determining the liquid viscosity of defined Iiydi ocai bon mixtiai es. Equation (2-119) depends only on the pure component viscosities at the given temperature and pressure and the mixture composition. 

In the case of mixtures of raw materials, the mrecd-material-usage variance can be further subdivided into (I) a direcd-material-mixture variance and (2) a direcd-material-yield variance. The former is due to the difference between the acdual and standard mixture compositions, and the latter to the difference between the actual and standard yields. Here, the standard yield is the output expected from the standard input of material. The yield variance denotes the extent of loss of material. The direc t-material-mixture variance can be illustrated by Example 22. 

FIG. 13-17 Effect of mixture composition upon K value for n-pentane at 104 C (220 F). K values are shown for various values of VP, weight fraction propane on a methane-free basis for the methane-propane-pentane system. [Hadden, Chem. Eng. Prog. Symp. Sec. 7, 49, 5S (1953).]... 

A range of concentrations of the two substances were inserted in equation (6) and a curve constructed relating retention time of the composite peak (calculated by means of a computer) to mixture composition. The results are shown in Figure 7. 

The ranges of mixture composition pins operating temperature and pressure are important. Unless a detonation flame arrester is used, it is essential to ensure that DDT will not occur after a flame enters the system. Even if a detonation flame arrester is used, it is important to use the correct type of arrester for the service. For example, if it is possible for a flame to approach from either direction, a bidirectional flame arrester must be selected. 

Detonations can only take place within the detonable limits, which fall inside the flammable limits. Mixture composition may vary widely in some systems, and this can further depend on the number of connections feeding a manifolded header. There are few cases where it can be assumed that a nondetonating flammable mixture will be produced hence, most in-line flame arrester applications involve the use of detonation flame arresters. 

Cell size depends strongly on the fuel and mixture composition more reactive mixtures result in smaller cell sizes. Table 3.2 shows that a stoichiometric mixture of methane and air has an exceptionally low susceptibility to detonation compared to other hydrocarbon-air mixtures. 

Calculate the stoichiometric air-fuel mass ratio, r, from the stoichiometric mixture composition, <(> and air and fuel molecular weights ... 

Calculate w from the actual mixture composition , the stoichiometric mixture composition <()s, and the expansion ratio for stoichiometric combustion a ... 

Calculate the air-fuel mass ratio r from the stoichiometric mixture composition < >j, and the densities of air and fuel ... 

If hot water and W ater vapor at 175°F are used to flush mixture A from the tank, the mixture composition can only shift along AC to E. Mixtures between A and E are flushed from the tank, mixed with air to give a mixture between parts AE and B. After examining several other... 

K-factors for vapor-liquid equilibrium ratios are usually associated with various hydrocarbons and some common impurities as nitrogen, carbon dioxide, and hydrogen sulfide [48]. The K-factor is the equilibrium ratio of the mole fraction of a component in the vapor phase divided by the mole fraction of the same component in the liquid phase. K is generally considered a function of the mixture composition in which a specific component occurs, plus the temperature and pressure of the system at equilibrium. 

Complex fluorotantalates of all other alkali metals can be prepared successfully using the same method, and appropriate adjustment of the initial mixture composition enables to obtain hexa-, hepta- and octafluorotantalates [117,118]. 

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