Sinor, 1960 (2) Conti, 1960 (3) Pratt, 1947 (4) Scatchard, 1952 (5) Steinhauser, 1949 (6) Abbott, 1975 (7) Severns, 1955 (8) Nagata, 1962.  [c.54]

Liquid-liquid equilibria are much more sensitive than vapor-liquid equilibria to small changes in the effect of composition on activity coefficients. Therefore, calculations for liquid-liquid equilibria should be based, whenever possible, at least in part, on experimental liquid-liquid data.  [c.63]

Pratt, H. R. C., Trans. Inst. Chem. Engrs. (London), 25, 43 (1947). —  [c.80]

In modern separation design, a significant part of many phase-equilibrium calculations is the mathematical representation of pure-component and mixture enthalpies. Enthalpy estimates are important not only for determination of heat loads, but also for adiabatic flash and distillation computations. Further, mixture enthalpy data, when available, are useful for extending vapor-liquid equilibria to higher (or lower) temperatures, through the Gibbs-Helmholtz equation.  [c.82]

ACETON ITRILE VL 9 330-353 -176.3B 261.53 39.81 PRATT,1947  [c.189]

C. The next four data cards contain pure-component data for component two. The same format as used in part B is repeated here.  [c.225]

Multiple sets of binary VLE data may be correlated by continuing with another set of cards starting at part B. The last set of cards must be followed with a blank card to end the program.  [c.227]


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]

This text concentrates on developing an understanding of the concepts required at each stage of the chemical process design. Such understanding is a vital part of process design, whichever approach is followed.  [c.13]

This termination step stops the subsequent growth of the polymer chain. The period during which the chain length grows, i.e., before termination, is known as the active life of the polymer. Other termination steps are possible.  [c.22]

In describing reactor performance, selectivity is usually a more meaningful parameter than reactor yield. Reactor yield is based on the reactant fed to the reactor rather than on that which is consumed. Clearly, part of the reactant fed might be material that has been recycled rather than fresh feed. Because of this, reactor yield takes no account of the ability to separate and recycle unconverted raw materials. Reactor yield is only a meaningful parameter when it is not possible for one reason or another to recycle unconverted raw material to the reactor inlet. By constrast, the yield of the overall process is an extremely important parameter when describing the performance of the overall plant, as will be discussed later.  [c.25]

Three idealized models are used for the design of reactors. " In the first (Fig. 2.1a), the ideal batch model, the reactants are charged at the beginning of the operation. The contents are subjected to perfect mixing for a certain period, after which the products are discharged. Concentration changes with time, but the perfect mixing ensures that at any instant the composition and temperature throughout the reactor are both uniform.  [c.28]

In the second model (Fig. 2.16) the continuous well-stirred model, feed and product takeoff are continuous, and the reactor contents are assumed to he perfectly mixed. This leads to uniform composition and temperature throughout. Because of the perfect mixing, a fluid element can leave at the instant it enters the reactor or stay for an extended period. The residence time of individual fluid elements in the reactor varies.  [c.29]

Multiple reactions in series producing byproducts. Consider the series reaction system from Eq. (2.18). For a certain reactor conversion, the FEED should have a corresponding residence time in the reactor. In the continuous well-mixed reactor, FEED can leave the instant it enters or remains for an extended period. Similarly, PRODUCT can remain for an extended period or leave immediately. Substantial fractions of both FEED and PRODUCT leave before and after what should be the specific residence time for a given conversion. Thus the continuous well-mixed model would be expected to give a poorer selectivity than a batch or plug-flow reactor for a given conversion. A batch or plug-flow reactor should be used for multiple reactions in series.  [c.31]

When more than one reactant is used, it is often desirable to use an excess of one of the reactants. It is sometimes desirable to feed an inert material to the reactor or to separate the product partway through the reaction before carrying out further reaction. Sometimes it is desirable to recycle unwanted byproducts to the reactor. Let us now examine these cases.  [c.34]

Solution We wish to avoid as much as possible the production of di- and triethanolamine, which are formed by series reactions with respect to monoethanolamine. In a continuous well-mixed reactor, part of the monoethanolamine formed in the primary reaction could stay for extended periods, thus increasing its chances of being converted to di- and triethanolamine. The ideal batch or plug-flow arrangement is preferred, to carefully control the residence time in the reactor.  [c.50]

Further consideration of the reaction system reveals that the ammonia feed takes part only in the primary reaction and in neither of the secondary reactions. Consider the rate equation for the primary reaction  [c.50]

The process is shown in Fig. 4.11 as a Gantt or time-event chart. The first two steps, pumping for reactor filling and feed preheat, are both semicontinuous. The heating inside the reactor, the reaction itself, and the cooling using the reactor jacket are all batch. The pumping to empty the reactor and the product cooling steps are again semicontinuous.  [c.117]

Reactor Filling Feed Preheat  [c.117]

Reactor Filling Feed Preheat  [c.117]

Clearly, the time chart shown in Fig. 4.14 indicates that individual items of equipment have a poor utilization i.e., they are in use for only a small fraction of the batch cycle time. To improve the equipment utilization, overlap batches as shown in the time-event chart in Fig. 4.15. Here, more than one batch, at difierent processing stages, resides in the process at any given time. Clearly, it is not possible to recycle directly from the separators to the reactor, since the reactor is fed at a time different from that at which the separation is carried out. A storage tank is needed to hold the recycle material. This material is then used to provide part of the feed for the next batch. The final flowsheet for batch operation is shown in Fig. 4.16. Equipment utilization might be improved further by various methods which are considered in Chap. 8 when economic tradeoffs are discussed.  [c.121]

Figure 5.12 Composition profiles for the middle product in the columns of the direct sequence show remixing effects. (From Triantafyllou and Smith, Trans. IChemE, part A, 70 118, 1992 reproduced by permission of the Institution of Chemical Engineers.) Figure 5.12 Composition profiles for the middle product in the columns of the direct sequence show remixing effects. (From Triantafyllou and Smith, Trans. IChemE, part A, 70 118, 1992 reproduced by permission of the Institution of Chemical Engineers.)
Triantafyllou, C., and Smith, R., The Design and Optimization of Fully Thermally Coupled Distillation Columns, Trans. IChemE, Part A, 70 118, 1992.  [c.157]

Figure 6.27 shows a grand composite curve with a flue gas matched against it to provide a hot utility. The flue gas starts at its theoretical flame temperature (shifted for AT ,m on the grand composite curve) and presents a sloping profile because it is giving up sensible heat. Theoretical flame temperature is the temperature attained when a fuel is burnt in air or oxygen without loss or gain of heat. Methods are presented elsewhere for its calculation. It should be emphasized that the theoretical and real flame temperatures will be quite different. The real flame temperature will be lower than the theoretical flame temperature because, in practice, heat is lost from the flame and because part of the heat released provides heat for a variety of endothermic dissociation reactions that occur at high temperatures, such as  [c.188]

Figure 6.28 Increasing the theoretical flame temperature by reducing excess air or combustion air preheat reduces the stack loss. Figure 6.28 Increasing the theoretical flame temperature by reducing excess air or combustion air preheat reduces the stack loss.

There are many facets to the evaluation of performance. Good economic performance is an obvious first criterion, but it is certainly not the only one. Chemical processes should be designed as part of a sustainable industrial development which retains the capacity of ecosystems to support both industried activity and life. In practical terms this means that waste should be minimized and that any waste byproducts which are produced must not be environmentally harmful. Sustsiinable development also demands that the process should use as little energy as practicable. The process also must meet required health and safety criteria. Start-up, emergency shutdown, and ease of control are other important factors. Flexibility, i.e., the ability to operate under different conditions such as differences in feedstock and product specification, etc., may be important. Availability, i.e., the number of operating hours per year, also may be important. Some of these factors, such as economic performance, can be readily quantified others, such as safety, often cannot. Evaluation of the factors which are not readily quantifiable, the intangibles, requires the judgment of the designer.  [c.2]

Smith, R., and Petela, E. A., Waste Minimisation in the Process Industries Part 2—Reactors, The Chemical Engineer, 12 509/510, Dec. 17, 1992.  [c.65]

Figure 5.13 Compasition profiles for the middle product in the prefractionator arrangement show that there are no remixing effects. (From Triantafyllou and Smith, Trans. IChemE, part A, 70 118, 1992 repr uced by permission of the Institution of Chemical Engineers.) Figure 5.13 Compasition profiles for the middle product in the prefractionator arrangement show that there are no remixing effects. (From Triantafyllou and Smith, Trans. IChemE, part A, 70 118, 1992 repr uced by permission of the Institution of Chemical Engineers.)
Analogous effects are caused by the inappropriate use of utilities. Utilities are appropriate if they are necessary to satisfy the enthalpy imbalance in that part of the process. Above the pinch in Fig. 6.7a, steam is needed to satisfy the enthalpy imbalance. Figure 6.86 illustrates what happens if inappropriate use of utilities is made and some cooling water is used to cool hot streams above the pinch, say, XP. To satisfy the enthalpy imbalance above the pinch, an import of (Q mjj,+XP) is needed from steam. Overall, (Qcmin+AP) of cooling water is used.  [c.168]

Figure 6.316 shows the heat engine integrated entirely above the pinch. In rejecting heat above the pinch it is rejecting heat into the part of the process which is overall a heat sink. In so doing, it is exploiting the temperature diflFerence that exists between the utility source and the process sink, producing work at high efficiency. The net effect in Fig. 6.316 is the import of extra energy W from heat sources to produce 17 shaftwork. Because the process and heat engine are acting as one system, apparently conversion of heat to work at 100 percent efficiency is achieved.  [c.194]

Gas turbine integration. Figure 6.34 shows a simple gas turbine matched against a process. The machine is essentially a rotary compressor mounted on the same shaft as a turbine. Air enters the compressor, where it is compressed before entering a combustion chamber. Here the combustion of fuel increases its temperature. The mixture of air and combustion gases is expanded in the turbine. The input of energy to the combustion chamber allows enough shaftwork to be developed in the turbine to both drive the compressor and provide useful work. The expanded gas may be discharged to the atmosphere directly or may first be used to preheat the air to the  [c.196]

Again, there are two fundamental ways in which a heat pump can be integrated with the process across and not across the pinch. Integration not across (above) the pinch is illustrated in Fig. 6.38a. This arrangement imports W shaftwork and saves IV hot utility. In other words, the system converts power into heat, which is normally never economically worthwhile. Another integration not across (below) the pinch is shown in Fig. 6.386. The result is worse economically. Power is turned into waste heat. Integration across the pinch is illustrated in Fig. 6.38c. This arrangement brings about a genuine saving. It also makes overall sense because heat is pumped from the part of the process which is overall a heat source to the part which is overall a heat sink.  [c.204]

See pages that mention the term Preheat : [c.10]    [c.76]    [c.202]    [c.206]    [c.266]    [c.267]    [c.267]    [c.267]    [c.267]    [c.267]    [c.90]    [c.160]    [c.201]    [c.201]    [c.202]    [c.208]   
Turboexpanders and Process Applications (0) -- [ c.472 ]