Binary distillation McCabe-Thiele diagram

Figure 10.1.5. (a) Distillation column with a reboiler and a total condenser for a binary mixture separation, (b) Separation of a binary mixture into two pure compounds by binary distillation McCabe-Thiele diagram. (After Humphrey and Keller (1997).)... 

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. 

Calculations for the policy of constant distillate composition can also be made with the McCabe-Thiele diagram for binary mixtures. An overall material balance for the light-key component at any time, t, is given by rearrangement of equation (6-108) at constant xD for W as a function of... 

McCabe-Thiele Method - This MathCAD document creates a McCabe-Thiele Diagram for a binary distillation. Data are from Example 6-5. 

McCabe-Thiele diagrams for adsorption, 320 for binary distillation, 326, 329, 330, 332, 334 for countercurrent multistage separator, 309 for extraction, 317 for ion exchange, 322 for rectifying column, 314 McCabe-Thiele method for distillation, 310-315, 322-340... 

We know enough now about the McCabe-Thiele diagram to make several observations, which can be applied to any distillation system, not just a binary separation. 

Figure 2-8. McCabe-Thiele diagram for binary flash distillation illustrated for Exanyle 2-1...

Although binary distillation problems can be done conveniently on a McCabe-Thiele diagram. Chapter 6 will show that multicomponent distillation problems are easiest to solve as matrix solutions for simulation problems (the number of stages and feed locations are known). Commercial simulators typically solve all problems this way. Lab 3 in this appendix provides an opportunity to use a process simulator for binary distillation. Although the instructions discuss Aspen Plus, other simulators will be similar. 

Figure 8-4. Binary heterogeneous azeotrope (A) two-column distillation system, (B) McCabe-Thiele diagram for column 1. (C) McCabe-Thiele diagram for column 2 with expanded coordinates.

Fig. 2-56. McCabe-Thiele-diagram for calculating the number of theoretical stages for the batch distillation of a binary mixture.

For the reversible distillation, the operation fine should coincide with the equilibrium line for the binary mixture in the McCabe-Thiele diagram. 

Binary Systems. The methods used to distill beyond azeotropes in binary systems are illustrated using McCabe-Thiele diagrams. Four of the more popular methods are discussed here. A more conplete discussion is available in any standard separations textbook [151. 

The equations describing a binary distillation column can be solved graphically using the famous McCabe-Thiele diagrams. These techniques are very useful in gaining an appreciation of the effects of various design and operatir parameters. 

The design of a distillation column is based on information derived from the VLE diagram describing the mixtures to be separated. The vapor-liquid equilibrium characteristics are indicated by the characteristic shapes of the equilibrium curves. This is what determines the number of stages, and hence the number of trays needed for a separation. Although column designs are often proprietary, the classical method of McCabe-Thiele for binary columns is instructive on the principles of design. 

Figure 13.9. Combined McCabe-Thiele and Merkel enthalpy-concentration diagrams for binary distillation with heat balances, (a) Showing key lines and location of representative points on the operating lines, (b) Completed construction showing determination of the number of trays by stepping off between the equilibrium and operating lines.

---