McCabe-Thiele diagram, distillation

McCabe Delta-L law, ciystallization, 533 calculation example, 534 McCabe-Thiele diagram, distillation, 381 Magnesium sulfate/water diagram, 526, 529... 

Alternative approaches are to be found in the hterature. Derivations of the above equations are given in numerous texts (2,10—12), which also describe graphical or analytical solutions to the problem. Many of these have direct analogues in other separation processes such as distillation (qv) and hquid—hquid extraction, and use plots such as the McCabe-Thiele diagram or Ponchon-Savarit diagram. 

The system material balance from Treybal [129] using a heated kettle and distillation column following a McCabe-Thiele diagram, using reflux, but having only a batch (kettle) charge ... 

The catalytic esterification of ethanol and acetic acid to ethyl acetate and water has been taken as a representative example to emphasize the potential advantages of the application of membrane technology compared with conventional distillation [48], see Fig. 13.6. From the McCabe-Thiele diagram for the separation of ethanol-water mixtures it follows that pervaporation can reach high water selectivities at the azeotropic point in contrast to the distillation process. Considering the economic evaluation of membrane-assisted esterifications compared with the conventional distillation technique, a decrease of 75% in energy input and 50% lower investment and operation costs can be calculated. The characteristics of the membrane and the module design mainly determine the investment costs of membrane processes, whereas the operational costs are influenced by the hfetime of the membranes. 

The graphical construction of an extraction isotherm, an operating line, and the stepwise evaluation of the number of stages in this manner is known as a McCabe-Thiele diagram. Flistorically, it found great application in a variety of mass transfer operations, from gas adsorption through distillation to solvent extraction. Flowever, the advent of modern computational techniques has made it largely redundant, as it is often easier and certainly more accurate to calculate the cascade directly. 

The experimental and converted data are tabulated following and plotted on McCabe-Thiele diagrams. The corresponding compositions involved in this distillation are ... 

Both modes usually are conducted with constant vaporization rate at an optimum value for the particular type of column construction. Figure 13.10 represents these modes on McCabe-Thiele diagrams. Small scale distillations often are controlled... 

Figure 13 shows a McCabe-Thiele diagram, which can be used when the mixture to be distilled consists of only two components or can be represented by two components. Starting at the required overhead product composition x/), an upper-section operating line is drawn hav-... 

The graphical technique most frequently used in distillation is the x-y or McCabe-Thiele diagram (1). The H-x, or Ponchon-Savarit diagram (2,3), is herder to visualize and cannot be readily extended to multicomponent distillation. Due to their limited application, H-x diagrams were excluded from this book, and are discussed elsewhere (4-6). 

Figure S.2 Batch distillation of benzene-toluene at constant reflux ratio, Example 5,3, ia-e) McCabe-Thiele diagram for progressively reducing still concentration to 0.13 mole fraction benzene.

Hgwe 5.3 (Continued) Batch distillation of benzene-toluene with Wriable reflux ratio, Example 5.4. (o-e) McCabe-Thiele diagram fcr progressively increasing reflux ratio to 13 1. 

Until about 1930, most distillation calculations were based on Raoult s law in extreme cases, where ideal-mixture behavior was clearly incorrect, distillation calculations required experimental data coupled with graphical methods, as in the McCabe-Thiele diagram. 

FIG. 13-44 Multicomponent McCabe-Thiele diagram for the hydrocarbon distillation in Fig. 13-43. 

FIG. 13-57 McCabe-Thiele diagram for nonideal distillation column. 

Both modes usually are conducted with constant vaporization rate at an optimum value for the particular type of column construction. Figure 13.9 represents these modes on McCabe-Thiele diagrams. Small scale distillations often are controlled manually, but an automatic control scheme is shown in Figure 13.9(c). Constant overhead composition can be assured by control of temperature or directly of composition at the top of the column. Constant reflux is assured by flow control on that stream. Sometimes there is an advantage in operating at several different reflux rates at different times during the process, particularly with multicomponent mixtures as on Figure 13.10. 

Once one has proposed alternative configurations for systems of separation devices to effect a desired separation, one must then design these devices so the various alternatives may be compared. For a distillation column, the first set of design decisions is to choose the number of trays, the feed tray location, and the reflux ratio at which to operate it. For a binary separation, the McCabe-Thiele diagram (or the concepts behind it) is an indispensable aid in making these decisions. 

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