More On Components

Example 15.2 Suppose we have a system that contains C, O2, CO2, and CO. This is a system with four identifiable chemical species. The balanced equations we can write among them are 

there are four relations, but they are not independent. If we add Eqs. 15.A and 15.C and cancel like terms, we obtain Eq. 15.B. Thus, if this is to be a list of independent chemical equilibria we must delete Eq. 15.C above. If it bothers you to delete one, remember that each chemical equilibrium is really a relation among the /rs and if we already have an equilibrium relation among the some subset of the /as we cannot have an additional independent one among the same 

if we reverse the direction of Eq. 15.B and add it to Eq. 15. A, we see that Eq. 15.D is also not independent. Thus, there are only two independent relations among these four species and 

Example 153 Suppose that the system we are considering has three species H2, N2, and NH3 (N = 3). From Eq. 12.A 

Now consider the possibility that we made up the system by starting with pure ammonia, and dissociating it over a catalyst. Further, assume that aU of the species are in the gas phase. In this case aU the hydrogen and all the nitrogen in the system have come from the ammonia that was dissociated. Theirmolarratio must be3 1. We can write an equation among their mol fractions, viz  

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For more on component failure rate data, see NASA s FTA Handbook (paragraph 7.2) and Kritzinger (2006, paragraph 10.6). 

In principle, extractive distillation is more useful than azeotropic distillation because the process does not depend on the accident of azeotrope formation, and thus a greater choice of mass-separating agent is, in principle, possible. In general, the solvent should have a chemical structure similar to that of the less volatile of the two components. It will then tend to form a near-ideal mixture with the less volatile component and a nonideal mixture with the more volatile component. This has the effect of increasing the volatility of the more volatile component. 

The equivalent weight distribution of natural petroleum sulfonates depends on the boiling range of the aromatic components in the feedstock, but generally consists of a broad continuum of molecular weight components (139). For many appHcations it is precisely this property of derived petroleum sulfonates that provides the unique properties, such as emulsification. Conversely, most oil-soluble synthetic sulfonates have much more limited components and molecular weight distribution. 

Separation by distillation is dependent on the fact that when a Hquid is partially vaporized the vapor and Hquid compositions differ. The vapor phase becomes enriched ia the more volatile components and depleted ia the less volatile components with respect to its equiUbrium Hquid phase. By segregating the phases and repeating the partial vaporization, it is often possible to achieve the desired degree of separation. One measure of the degree of enrichment or the ease of separation is the relative volatiHty defined as ... 

In the special case that A and B are similar in molecular weight, polarity, and so on, the self-diffusion coefficients of pure A and B will be approximately equal to the mutual diffusivity, D g. Second, when A and B are the less mobile and more mobile components, respectively, their self-diffusion coefficients can be used as rough lower and upper bounds of the mutual diffusion coefficient. That is, < D g < Dg g. Third, it is a common means for evaluating diffusion for gases at high pressure. Self-diffusion in liquids has been studied by many [Easteal AIChE]. 30, 641 (1984), Ertl and Dullien, AIChE J. 19, 1215 (1973), and Vadovic and Colver, AIChE J. 18, 1264 (1972)]. 

An important characteristic of pervaporation that distinguishes it from distillation is that it is a rate process, not an equilibrium process. The more permeable component may be the less-volatile component. Perv oration has its greatest iitihty in the resolution of azeotropes, as an acqiinct to distillation. Selecting a membrane permeable to the minor corTiponent is important, since the membrane area required is roughly proportional to the mass of permeate. Thus pervaporation devices for the purification of the ethanol-water azeotrope (95 percent ethanol) are always based on a hydrophihc membrane. 

Each product is derived from individual pieces of material, individual components and individual assembly processes. The properties of these individual elements have a probability of deviating from the ideal or target value. In turn, the designer defines allowable tolerances on component characteristics in anticipation of the manufacturing variations, but more often than not, with limited knowledge of the cost... 

The absorption, distribution, and accumulation of lead in the human body may be represented by a three-part model (6). The first part consists of red blood cells, which move the lead to the other two parts, soft tissue and bone. The blood cells and soft tissue, represented by the liver and kidney, constitute the mobile part of the lead body burden, which can fluctuate depending on the length of exposure to the pollutant. Lead accumulation over a long period of time occurs in the bones, which store up to 95% of the total body burden. However, the lead in soft tissue represents a potentially greater toxicological hazard and is the more important component of the lead body burden. Lead measured in the urine has been found to be a good index of the amount of mobile lead in the body. The majority of lead is eliminated from the body in the urine and feces, with smaller amounts removed by sweat, hair, and nails. 

The composition of the vapour in equilibrium with a miscible liquid mixture at any temperature, e.g. on heating during distillation, will be enriched by the more volatile components. The composition of the liquid phase produced on partial condensation will be enriched by the less volatile components. Such fractionation can have implications for safety in tliat tlie flammability and relative toxicity of the mixtures can change significantly. 

Since power is a substantial component of the fixed operating cost of a unit, the operating cost would run approximately seven times more on a scrubber installation. The installation costs of a hot-rolled steel precipitator to handle 100,000 cfm would be between 3.50 and 4.50/cfm as opposed to 1.40 to 1.80/cfm for a venturi scrubbing system. Although the initial capital expenditure is high for the precipitator, if the total operating and capital costs are amortized over an acceptable period of time, 8 to 10 years, the precipitator will prove to be the. lore economically feasible choice because of its low operating and maintenance costs. 

The standard creates a distinction between design verification and design validation. There are two types of verification those verification activities performed during design and on the component parts to verify conformance to specification and those verification activities performed on the completed design to verify performance but more on this later. 

The design problem of a TMB consists on setting the flow rates in each section to obtain the desired separation. Some constraints have to be met to recover the less-adsorbed component A in the raffinate and the more retained component B in the extract. These constraints are expressed in terms of the net fluxes of components in each section (see Fig. 9-1). In section I, both species must move upwards, in sections II and III the light species must move upwards, while the net flux of the more retained component must be downwards, and in section IV the net flux of both species have to be downwards, i.e.. 

The area under the curve between Xgo and is the value of the integrtil. Plot the equilibrium curve for the more volatile component on x - y diagram as shown in Figure 8-33. Then, select values of xd from the operating line hav ing the constant slope, L/V, from equation... 

In applications where the liquid is used directly by one or more system components, the contribution of these components to the total system head may be difficult to calculate. In some cases, the vendor s manual or the original design documentation will provide this information. If these data are not available, then the friction losses and back pressure need to be measured or an over-capacity pump selected for service based on a conservative estimate. 

Reactivity ratios for the copolymerization of AN with 7 in methanol at 60 °C, proved to be equal to rx AN= 3,6 0,2 and r%n = 0 0,06, i.e., AN is a much more active component in this binary system. The low reactivity of the vinyl double bond in 7 is explained by the specific effect of the sulfonyl group on its polarity26. In addition to that, the radical formed from 7 does not seem to be stabilized by the sulfonyl group and readily takes part in the chain transfer reaction and chain termination. As a result of this, the rate of copolymerization reaction and the molecular mass of the copolymers decrease with increasing content of 7 in the initial mixture. 

For dilute solutions, the technical literature contains some direct (dilato-metric) measurements of v2, the partial molar volume of the more volatile component, but the accuracy of these measurements is usually not high. A survey was made by Lyckman and Eckert (L6) and they established the rough correlation shown in Fig. 5. On the ordinate, the partial molar volume is... 

Solvents interact with reverse phases in very much the same way as they do with the surface of silica gel. However, in this case it is the more dispersive component of the mobile phase that is adsorbed on the surface as opposed to silica gel, which being a polar stationary phase, adsorbs the more polar solvent onto its surface. 

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