Chapter 1 INTI DUCTION  [c.1]

The method proposed in this monograph has a firm thermodynamic basis. For vapo/-liquid equilibria, the method may be used at low or moderate pressures commonly encountered in separation operations since vapor-phase nonidealities are taken into account. For liquid-liquid equilibria the effect of pressure is usually not important unless the pressure is very large or unless conditions are near the vapor-liquid critical region.  [c.2]

A classic in its field, giving a splendid survey of solution physical chemistry from a chemist s point of view. While seriously out of date, it nevertheless provides physical insight into how molecules "behave" in mixtures.  [c.9]

When Equations (7) and (8) are substituted into Equation (9), we obtain  [c.16]

Equations (7b) and (8) into Equation (6), neglecting all third virial coefficients. We then obtain  [c.28]

In the first, both components strongly associate with themselves and with each other. In the second, only one of the components associates strongly. For both systems, representation of the data is very good. However, the interesting quality of these systems is that whereas the fugacity coefficients are significantly remote from unity, the activity coefficients show only minor deviations from ideal-solution behavior. Figures 6 and 7 in Chapter 3 indicate that the fugacity coefficients show marked departure from ideality. In these systems, the major contribution to nonideality occurs in the vapor phase. Failure to take into account these strong vapor-phase nonidealities would result in erroneous activity-coefficient parameters, a 2 21  [c.51]

The continuous line in Figure 16 shows results from fitting a single tie line in addition to the binary data. Only slight improvement is obtained in prediction of the two-phase region more important, however, prediction of solute distribution is improved. Incorporation of the single ternary tie line into the method of data reduction produces only a small loss of accuracy in the representation of VLE for the two binary systems.  [c.69]

Figure 4-16. Representation of ternary liquid-liquid equilibria using the UNIQUAC equation is improved by incorporating ternary tie-line data into binary-parameter estimation. Representation of binary VLB shows small loss of accuracy. ---- Binary Figure 4-16. Representation of ternary liquid-liquid equilibria using the UNIQUAC equation is improved by incorporating ternary tie-line data into binary-parameter estimation. Representation of binary VLB shows small loss of accuracy. ---- Binary
Figure 4-17. Representation of ternary liquid-liquid equilibria using the UNIQUAC equation is improved by incorporating ternary tie-line data into binary-parameter estimation. Representation of binary VLB shows some loss of accuracy. Figure 4-17. Representation of ternary liquid-liquid equilibria using the UNIQUAC equation is improved by incorporating ternary tie-line data into binary-parameter estimation. Representation of binary VLB shows some loss of accuracy.
Substitution of Equation (14) into Equation (12) yields  [c.86]

When the UNIQUAC equation (Chapter 4) is substituted into Equation (16), assuming all parameters and a to be inde-  [c.87]

Substitution of Equations (2) and (3) into the equilibrium relations dictated by Equation (2-l)[c.99]

At low pressures, it is often permissible to neglect nonidealities of the vapor phase. If these nonidealities are not negligible, they can have the effect of introducing a nonrandom trend into the plotted residuals similar to that introduced by systematic error. Experience here has shown that application of vapor-phase corrections for nonidealities gives a better representation of the data by the model, oven when these corrections  [c.106]

The most frequent application of phase-equilibrium calculations in chemical process design and analysis is probably in treatment of equilibrium separations. In these operations, often called flash processes, a feed stream (or several feed streams) enters a separation stage where it is split into two streams of different composition that are in equilibrium with each other.  [c.110]

In an equilibrium separation, a feed stream containing m components at given composition, pressure, and enthalpy (or temperature if in a single phase) is split into two streams in equilibrium, here taken to be a vapor and a liquid. The flow rates of the feed, vapor, and liquid streams are, respectively,  [c.111]

The same fundamental development as presented here for vapor-liquid flash calculations can be applied to liquid-liquid equilibrium separations. In this case, the feed splits into an extract at rate E and a raffinate at rate R, which are in equilibrium with each other. The compositions of these phases are  [c.115]

PARIN loads values of pure component and binary parameters from formatted card images into labeled common blocks /PURE/ and /BINARY/ for a maximum of 100 components.  [c.341]


Hgure 1.1 Synthesis is the creation of a process to transform feed streams into product streams. Simulation predicts how it would behave if it was constructed.  [c.2]

Consider the process illustrated in Fig. 1.2. The process requires a reactor to transform the FEED into PRODUCT (Fig. 1.2a). Unfortunately, not all the FEED reacts. Also, part of the FEED reacts to form BYPRODUCT instead of the desired PRODUCT. A  [c.3]

Creating and optimizing a reducible structure. In this approach, a structure known as a superstructure or hyperstructure is first created that has embedded within it all feasible process operations and all feasible interconnections that are candidates for an optimal design. Initially, redundant features are built into the structure. As an example, consider Fig. 1.7. This shows one possible structure of a process for the manufacture of benzene from the reaction between toluene and hydrogen. In Fig. 1.7, the hydrogen enters the process with a small amount of methane as an impurity. Thus in Fig. 1.7 the option is embedded of either purifying the hydrogen feed with a membrane or passing directly to the process. The hydrogen and toluene are mixed and preheated to reaction temperature. Only a furnace has been considered feasible in this case because of the high temperature required. Then two alternative reactor options, isothermal and adiabatic reactors, are embedded, and so on. Redundant features have been included in an effort to ensure that all features that could be part of an optimal solution haVe been included.  [c.9]

Before we can proceed with the choice of reactor and operating conditions, some general classifications must be made regarding the types of reaction systems likely to be encountered. We can classify reaction systems into five broad types  [c.18]

Unfortunately, despite much research into the fundamentals of catalysis, the choice of catalyst is still largely empirical. The catalytic process can be homogeneous or heterogeneous.  [c.46]

By contrast with ideal models, practical reactors must consider many factors other than variations in temperature, concentration, and residence time. Practical reactors deviate from the three idealized models but can be classified into a number of common types.  [c.52]

Having made an initial specification for the reactor, attention is turned to separation of the reactor effluent. In addition, it might be necessary to carry out separation before the reactor to purify the feed. Whether before or after the reactor, the overall separation task normally must be broken down into a number of intermediate separation tasks. The first consideration is the choice of separator for the intermediate separation tasks. Later we shall consider how these separation tasks should be connected to the reactor. As with reactors, we shall concentrate on the choice of separator and not its detailed sizing.  [c.67]

The separation of suspended solid particles from a liquid by gravity settling into a clear fiuid and a slurry of higher solids content is called sedimentation. Figure 3.2 shows a sedimentation device known as a thickener, the prime function of which is to produce a more concentrated slurry. The feed slurry in Fig. 3.2 is fed at the center of the tank below the surface of the liquid. Clear liquid overflows from the top edge of the tank. A slowly revolving rake removes the thickened slurry or sludge and serves to scrape the sludge toward the center of the base for removal. It is common in such operations to add a flocculating agent to the mixture to assist the settling process. This agent has the effect of neutralizing electric charges on the particles that cause them to repel each other and remain dispersed. The effect is to form aggregates or floes which, because they are larger in size, settle more rapidly. When the prime function of the sedimentation is to remove solids from a liquid rather than to produce a more concentrated solid-liquid mixture, the device is known as a clarifier. Clarifiers are often similar in design to thickeners.  [c.69]

Figure 3.3 shows a simple type of classifier. In this device, a large tank is subdivided into several sections. A size range of solid particles suspended in vapor or liquid enters the tank. The larger, faster-settling particles settle to the bottom close to the entrance, and the slower-settling particles settle to the bottom close to the exit. The vertical baffles in the tank allow the collection of several fractions.  [c.70]

This type of classification device can be used to carry out solid-solid separation in mixtures of different solids. The mixture of particles is first suspended in a fluid and then separated into fractions of different size or density in a device similar to that in Fig. 3.3.  [c.70]

This technique is useful not only when the mixture is impossible to separate by conventional distillation because of an azeotrope but also when the mixture is difficult to separate because of a particularly low relative volatility. Such distillation operations in which an extraneous mass-separating agent is used can be divided into two broad classes.  [c.81]

In the first class, azeotropic distillation, the extraneous mass-separating agent is relatively volatile and is known as an entrainer. This entrainer forms either a low-boiling binary azeotrope with one of the keys or, more often, a ternary azeotrope containing both keys. The latter kind of operation is feasible only if condensation of the overhead vapor results in two liquid phases, one of which contains the bulk of one of the key components and the other contains the bulk of the entrainer. A t3q)ical scheme is shown in Fig. 3.10. The mixture (A -I- B) is fed to the column, and relatively pure A is taken from the column bottoms. A ternary azeotrope distilled overhead is condensed and separated into two liquid layers in the decanter. One layer contains a mixture of A -I- entrainer which is returned as reflux. The other layer contains relatively pure B. If the B layer contains a significant amount of entrainer, then this layer may need to be fed to an additional column to separate and recycle the entrainer and produce pure B.  [c.81]

In a chemical process, the transformation of raw materials into desired products usually cannot be achieved in a single step. Instead, the overall transformation is broken down into a number of steps that provide intermediate transformations. These are carried out through reaction, separation, mixing, heating, cooling, pressure change, particle size reduction and enlargement, etc. Once individual steps have been selected, they must be interconnected to carry out the overall transformation (Fig. 1.1a). Thus the synthesis of a chemical process involves two broad activities. First, individual transformation steps are selected. Second, these individual transformations are interconnected to form a complete structure that achieves the required overall transformation. A flowsheet is the diagrammatic representation of the process steps with their interconnections.  [c.1]

Design starts at the reactor because it is likely to be the only place in the process where raw materials are converted into desired products. The reactor design dictates the separation and recycle problem. The reactor design and separation and recycle problem together dictate the heating and cooling duties for the heat exchanger network. Those duties which cannot be satisfied by heat recovery dictate the need for external utilities. This hierarchy is represented by the layers in the onion diagram (see Fig. 1.6).  [c.13]

Choosing to use a continuous rather than a batch reactor, plug-flow behavior can be approached using a series of continuous well-mixed reactors. This again sdlows concentrated sulfuric acid to be added as the reaction progresses, in a similar way as suggested for some parallel systems in Fig. 2.2. Breaking the reactor down into a series of well-mixed reactors also allows good temperature control, s we shall discuss later.  [c.52]

See pages that mention the term INDO : [c.28]    [c.67]    [c.93]    [c.111]    [c.134]    [c.136]    [c.190]    [c.212]    [c.235]    [c.241]    [c.254]    [c.336]    [c.2]    [c.3]    [c.6]    [c.11]    [c.13]    [c.42]   
See chapters in:

Computational chemistry  -> INDO

Hyperchem computation chemistry  -> INDO

Hyperchem computation chemistry  -> INDO

Molecular modelling Principles and applications (2001) -- [ c.86 ]

Computational chemistry (2001) -- [ c.35 , c.364 ]