MULTI COMPONENT

The calculation of vapor and liquid fugacities in multi-component systems has been implemented by a set of computer programs in the form of FORTRAN IV subroutines. These are applicable to systems of up to twenty components, and operate on a thermodynamic data base including parameters for 92 compounds. The set includes subroutines for evaluation of vapor-phase fugacity... 

Equation (4) is the )cey equation for calculation of multi-component vapor-liquid equilibria. 

Figure 4-20. Quarternary examples of three types of multi-component liquid-liquid mixtures.

When oil and gas are produced simultaneously into a separator a certain amount (mass fraction) of each component (e.g. butane) will be in the vapour phase and the rest in the liquid phase. This can be described using phase diagrams (such as those described in section 4.2) which describe the behaviour of multi-component mixtures at various temperatures and pressures. However to determine how much of each component goes into the gas or liquid phase the equilibrium constants (or equilibrium vapour liquid ratios) K must be known. 

The saturation coverage during chemisorption on a clean transition-metal surface is controlled by the fonnation of a chemical bond at a specific site [5] and not necessarily by the area of the molecule. In addition, in this case, the heat of chemisorption of the first monolayer is substantially higher than for the second and subsequent layers where adsorption is via weaker van der Waals interactions. Chemisorption is often usefLil for measuring the area of a specific component of a multi-component surface, for example, the area of small metal particles adsorbed onto a high-surface-area support [6], but not for measuring the total area of the sample. Surface areas measured using this method are specific to the molecule that chemisorbs on the surface. Carbon monoxide titration is therefore often used to define the number of sites available on a supported metal catalyst. In order to measure the total surface area, adsorbates must be selected that interact relatively weakly with the substrate so that the area occupied by each adsorbent is dominated by intennolecular interactions and the area occupied by each molecule is approximately defined by van der Waals radii. This... 

The type of treatment described here was originally introduced by Scott and Dullien [4], who confined attention to isothermal isobaric diffusion in binary mixtures. Similar equations were independently published shortly after by Rothfeld [5], and the method was later extended to multi-component mixtures by Silveston [6], Perhaps the most complete exposition is given by Mason and Evans [7],... 

G. J. Janz, C. B. AHen, N. P. Bansal, R. M. Murphy, and R. P. T. Tomkins, PhjsicalProperties Data Compilations Kelevantto Energy Storage. II Molten Salts Data on Single and Multi-Component Salt Systems, U.S. Department of Commerce, National Bureau of Standards, Washington, D.C., Apr. 1979, pp. 142-154. 

Low-PressureAlulticomponent Mixtures These methods are outlined in Table 5-17. Stefan-MaxweU equations were discussed earlier. Smith-Taylor compared various methods for predicting multi-component diffusion rates and found that Eq. (5-204) was superior among the effective diffusivity approaches, though none is very good. They so found that hnearized and exact solutions are roughly equivalent and accurate. 

Thermodynamic and Mass-Transfer Considerations Multi-component vapor mixture includes several different cases all the components may be hquids at the lowest temperature reached in the condensing side, or there may be components which dissolve substantially in the condensate even though their boiling points are below the exit temperature, or one or more components may be both noncondensable and nearly insoluble. 

Constant overhead composition, vaiying reflux. If it is desired to maintain a constant overhead composition in the case of a binaiy, the amount of reflux returned to the column must be constantly increased throughout the run. As time proceeds, the pot is gradually depleted of the hghter component. Finally, a point is reached at which the reflux ratio has attained a veiy high value. The receivers are then changed, the reflux is reduced, and an intermediate cut is taken as before. This technique can also be extended to a multi-component mixture. 

Simultaneous Absorption of Two Reacting Gases In multi-component physical absorption the presence of one gas often does not affect the rates of absorption of the other gases. When chemical reactions in which two or more gases are competing for the same hquid-phase reagent are involved, selectivity of absorption can be affected by... 

Determine theoretical stages for the separation binaiy or multi-component. 

Direct multi-element or multi-component simultaneous determination of ultra-trace matter in samples of environmental concern. 

Pd(II) was shown to be separated from Ni(II), Cr(III) and Co(III) by ACs completely, and only up to 3 % of Cu(II) and Fe(II) evaluate from solution together with Pd(II), this way practically pure palladium may be obtained by it s sorption from multi-component solutions. The selectivity of Pd(II) evaluation by ACs was explained by soi ption mechanism, the main part of which consists in direct interaction of Pd(II) with 7t-conjugate electron system of carbon matrix and electrons transfer from carbon to Pd(II), last one can be reduced right up to Pd in dependence on reducing capability of AC. 

The X-ray microanalysis is the basic method of study of rare-metal and rare-earth minerals of micron size. The multi-component composition, instability of minerals under the electron beam, overlap of X-ray characteristic lines, absence of reference samples of adequate composition present difficulties in the research of mineral composition. 

The effect of electrochemical sample treatment on the signal selectivity in multi-component mixtures is discussed. 

The many problems with correlation and good shop tests discussed in this chapter would seem to lead to the conclusion that one should field test. It is still better, however, if at all possible, to test in the shop. The new compressor field tests should be limited to only those units where performance is in doubt and shop test correlation is just too difficult. A four sidestream multi-component hydrocarbon gas would probably qualify as difficult to shop test. 

The relationship between what is recorded in a SSIMS spectrum and the chemical state of the surface is not as straightforward as in XPS and AES (Chap. 2). Because of the large number of molecular ions that occur in any SSIMS spectrum from a multi-component surface (e. g. during the study of a surface reaction), much chemical information is obviously available in SSIMS, potentially more than in XPS. The problem in using the information from a molecular ion lies in the uncertainty of knowing whether or not the molecule represents the surface composition. For some materials. 

Equation (3.19) is valid for any species X. If, however, a multi-component material emits only atomic SN after attaining sputter equilibrium, X stands for elements and atoms only, and the total sputter yield Yean be written as ... 

Multilayer coatings of different composition and thickness are widely used in materials science and in the production of high-technology materials. The single- or multi-component thin layers significantly improve important characteristics of the materials with, e.g., specific properties. 

The curves show that the peak capacity increases with the column efficiency, which is much as one would expect, however the major factor that influences peak capacity is clearly the capacity ratio of the last eluted peak. It follows that any aspect of the chromatographic system that might limit the value of (k ) for the last peak will also limit the peak capacity. Davis and Giddings [15] have pointed out that the theoretical peak capacity is an exaggerated value of the true peak capacity. They claim that the individual (k ) values for each solute in a realistic multi-component mixture will have a statistically irregular distribution. As they very adroitly point out, the solutes in a real sample do not array themselves conveniently along the chromatogram four standard deviations apart to provide the maximum peak capacity. 

Note that this equation holds for any component in a multi-component mixture. The integral on the right-hand side can only be evaluated if the vapor mole fraction y is known as a function of the mole fraction Xr in the still. Assuming phase equilibrium between liquid and vapor in the still, the vapor mole fraction y x ) is defined by the equilibrium curve. Agitation of the liquid in tire still and low boilup rates tend to improve the validity of this assumption. 

CHEMCALC 1, Separations Calculations Gulf Publishing Company, Book Division P.O. Box 2608 Houston, TX 77252 Programs for use with multi-component mixtures to determine the conditions and compositions at the dew point and at the bubble point. 

HGSystem offers the most rigorous treatments of HF source-term and dispersion analysis a ailable for a public domain code. It provides modeling capabilities to other chemical species with complex thermodynamic behavior. It treats aerosols and multi-component mixtures, spillage of a liquid non-reactive compound from a pressurized vessel, efficient simulations of time-dependent... 

Crystallization-based separation of multi-component mixtures has widespread application. The technique consists of sequences of heating, cooling, evaporation, dilution, diluent addition and solid-liquid separation. Berry and Ng (1996, 1997), Cisternas and Rudd (1993), Dye and Ng (1995), Ng (1991) and Oyander etal. (1997) proposed various schemes based on the phase diagram. Cisternas (1999) presented an alternate network flow model for synthesizing crystallization-based separations for multi-component systems. The construction... 

Yu, A.B. and Standish, N., 1987. Porosity calculations of multi-component mixtures of spherical particles. Powder Technology, 52, 233-241. 

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