Vaporization equilibrium ratio

K values. Equilibrium vaporization ratios or K values are widely used, particularly in the petroleum industry. 

Equilibrium vaporization ratio for component i on stagej Specific rate constant Variance-covariance matrix of measurement adjustments Heat transfer Variance of adjustment to measurementj... 

It should also be noted that the symbol Ki is utilized for the mol fraction ratio y, /x, in comparing the permeate composition to the reject or raffinate composition, as will be developed in Example 19.4. This is the usual symbolism as used in phase equilibria, say that of the X-value or equilibrium vaporization ratio for correlating the behavior of vapor/liquid systems—and, ideally, reflects Raoult s law. The foregoing illustrates the general problem... 

Jacoby, R. H., and M. J. Rzasa. 1952. Equilibrium vaporization ratios for nitrogen, methane, carbon dioxide, ethane and hydrogen sulfide in absorber oil-natural gas and crude oil-natural gas systems. Trans. AIME, Petrol. 195 99. 

Evans, R. B. Harris, D. Equilibrium Vaporization Ratios—Hydrocarbon... 

Vapor-liquid equilibria pose a similar problem that is, the behavior of the equilibrium vaporization ratio K as experimentally determined for a mid-range of temperature, pressure, and composition does not apply for the pure component nor at supercritical or near-supercritical conditions, such as for the light hydrocarbons, as per Katz et al. As an approximation, however, the equilibrium vaporization ratio may be defined by Raoult s law, that K - vp/P that is, the vapor pressure of the pure component divided by the total pressure. In turn, the mixture obeys Dalton s law of partial pressures. By these accommodations, the boundary condition for the pure component can be met K = 1.)... 

Note that a bubble-point type calculation on the feedstream composition is used to arrive at a value for K, (or K. Albeit this value, in principle, varies from cell to cell as the composition changes, it nevertheless furnishes a means for determining a value. Whereas in vapor-liquid operations such as absorption, the operating temperature and pressure are used to assign a constant value for the liquid-vapor equilibrium vaporization ratio K for a particular component namely, the key component or components. (And, in general, the equilibrium vaporization ratio is also a function of composition, especially near the critical point of the mixture, and even in absorption, the temperature varies somewhat up and down the column due to enthalpic effects.)... 

Gmehhng and Onken (Vapor-Liquid Equilibrium Data Collection, DECHEMA, Frankfurt, Germany, 1979) have reported a large collection of vapor-liqnid equilibrium data along with correlations of the resulting activity coefficients. This can be used to predict liqnid-hqnid equilibrium partition ratios as shown in Example 1. 

Toxic Volatile Ratio of Equilibrium Vapor Concentration over the Acute Substances Toxic Concentration (in ppm) is greater than 1000... 

Nucleation is the growth of clusters of molecules that become a thermodynamically stable nucleus. This process is dependent on the vapor pressure of the condensable species. The molecular clusters undergo growth when the saturation ratio, S, is greater than 1, where saturation ratio is defined as the actual pressure of the gas divided by its equilibrium vapor pressure. S > 1 is referred to as a supersaturated condition (14). 

It is important to realize that so long as both liquid and vapor are present the pressure exerted by the vapor is independent of the volume of the container. Ifa small amount ofliquid is introduced into a closed container, some of it will vaporize, establishing its equilibrium vapor pressure. The greater the volume of the container, the greater will be the amount ofliquid that vaporizes to establish that pressure. The ratio nIV stays constant, so P = nRTIV does not change. Only if all the liquid vaporizes will the pressure drop below the equilibrium value. 

As an example, the ratio of the equilibrium vapor pressures for water, Pi6 and water. Pig, depends on temperature and is expressed by the following equation, derived from Faure (1977) (temperature is in kelvins) ... 

The trapping efficiency of polymeric, microporous adsorbents [e.g., polystyrene, polyurethane foam (PUF), Tenax] for compound vapors will be affected by compound vapor density (i. e., equilibrium vapor pressure). The free energy change required in the transition from the vapor state to the condensed state (e.g., on an adsorbent) is known as the adsorption potential (calories per mole), and this potential is proportional to the ratio of saturation to equilibrium vapor pressure. This means that changes in vapor density (equilibrium vapor pressure) for very volatile compounds, or for compounds that are gases under ambient conditions, can have a dramatic effect on the trapping efficiency for polymeric microporous adsorbents. 

CAI s that were once molten (type B and compact type A) apparently crystallized under conditions where both partial pressures and total pressures were low because they exhibit marked fractionation of Mg isotopes relative to chondritic isotope ratios. But much remains to be learned from the distribution of this fractionation. Models and laboratory experiments indicate that Mg, O, and Si should fractionate to different degrees in a CAI (Davis et al. 1990 Richter et al. 2002) commensurate with the different equilibrium vapor pressures of Mg, SiO and other O-bearing species. Only now, with the advent of more precise mass spectrometry and sampling techniques, is it possible to search for these differences. Also, models prediet that there should be variations in isotope ratios with growth direction and Mg/Al content in minerals like melilite. Identification of such trends would verify the validity of the theory. Conversely, if no correlations between position, mineral composition, and Mg, Si, and O isotopic composition are found in once molten CAIs, it implies that the objects acquired their isotopic signals prior to final crystallization. Evidence of this nature could be used to determine which objects were melted more than once. 

Toxic Volatile Ratio of Equilibrium Vapor Concentration over the Acute... 

In the growth of crystals from the vapor phase, the degree of the driving force is expressed by the ratio S, i.e. the ratio between the equilibrium vapor pressure and the pressure p at growth ... 

A rough guideline was used in this program for determining if a substance exists as a vapor or particulate (or both) at levels near the OSHA standard. If the ratio of the equilibrium vapor concentration at 25°C to the standard was between Q.05 and 50, then contribution from both vapor and particulate was considered. A ratio below 0.05 indicated it would probably be vapor. Frequently,... 

Use the linear form of the Langmuir equation to evaluate (n/w)sat and K for the adsorption of pentane on carbon black from the higher pressure values in the following data. Use the ratio p/p0 rather than p only to normalize pressures relative to the equilibrium vapor pressure of pentane at different temperatures. (All pressures are in torr.)... 

The original equation for salt effect in vapor-liquid equilibrium, proposed by Furter (7) and employed subsequently by Johnson and Furter (8), described the effect of salt concentration on equilibrium vapor composition under the condition of a fixed ratio of the two volatile components in the liquid phase. The equation, derived from the difference in effects of the salt on the chemical potentials of the two volatile components, with simplifying approximations reduces to the form... 

Equation 13 reduces to the Rayeigh equation (3) when the ratio of the gas-phase diffusivities, , is unity. Since gas-phase diffusivity is inversely proportional to the square root of the reduced mass, in the case of fission product-sodium systems where sodium has the smallest molecular weight, the above diffusivity ratio is less than unity. Therefore, the Rayleigh equation, which was derived on the basis of equilibrium vaporization, in fact represents an upper limit for the fractional fission-... 

Fig. 1. Relative change of conductance G of a 0.36-/im-thick a-Si H film due to exposure to three different adsorbates at room temperature. The p/p0 is the ratio of the partial pressure of the gas admitted to its equilibrium vapor pressure at 250°C. (From Tanielian et al. (1978).]...

Relative to similar ratios of HCOO to CH COQj in the aqueous phase, differences in precipitation pH result in large regional differences in calculated equilibrium vapor-phase concentrations. 

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