Batch Distillation Multistage

Batch distillation is a discontinuous form of a distillation process. It is characterized by the couphng of a liquid vessel, into which the mixture is initially charged, with a distillation column, from which the products are continuously withdrawn. Three different configurations of batch distillation processes are shown in Fig. 5.2- 

The process configuration B in Fig. 5.2-39 allows the removal of the pure constituents as bottom fractions in a sequence of decreasing boiling temperatures (.c,b, a). This process is less important in industry. 

Multistage batch distillation (i.e., batch rectification) is governed by the Rayleigh equation 

Contrary to single stage batch distillation, the product concentration Xg, is not in equilibrium state with the bottom concentration Xg. Besides the phase equilibrimn, the relationship between product and vessel concentrations (Xg, and Xg) depends on the niunber of stages as well as on the reflux ratio colunm Two 

Operation with constant concentration of the distiller and, in turn, increasing reflux ratio 

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Figure 4.1 (a) Single-staged, and (b) multistaged batch distillation processes. 

For the production of relatively pure products by batch distillation, the stillpot is usually augmented by a multistage rectification column with reflux. Shown in Figure 12.19 is a flow diagram for a typical batch distillation process. The feed in this example contains components A, B, and... 

Stage calculations for multistage batch distillation are much more complicated than for continuous distillation, for two reasons. First, all conditions change with time. Second, the holdup in... 

Chapter 6 includes a section on multistage batch distillation. 

Equilibrium Flash Vaporization and Partial Condensation Graphical Multistage Calculations by the McCabe-Thiele Method Batch Distillation... 

The energy demand Q of multistage batch distillation can be found from the following eqnation ... 

In a multistage batch distillation, a staged or packed column is placed above the reboiler as in Figure 9-2. Reflux is returned to the column. In the usual operation, distillate is withdrawn continually (Barton and Roche. 1997 Diwekar. 1995 Luyben. 1971 Mujtaba, 2004 Pratt, 1962 Robinson and Gilliland. 19501 until the column is shut down and drained. In an alternative method (Treybal. 19701. no distillate is withdrawn instead, the conposition of liquid in the accumulator changes. When the distillate in the accumulator is of the desired conposition in the desired amount, both the accumulator and the reboiler are drained. Luyben (19711 indicated that the usual method should be superior however, the alternative method may be simpler to operate. 

Figure 9-2. Multistage batch distillation (A) schematic, (B) photograph of packaged batch...

The feed into the column is F kg moles of mole fraction Xp of the more volatile conponent. The final moles in the reboiler at the end of the batch is of mole fraction fjjjap The symbol W is used since the material left in the reboiler is often a waste. is the total kilogram moles of distillate of average concentration Xq a g. Equations (9-1) and (9-2) are applicable to sinple batch and normal multistage batch distillation. Some minor changes in variable definitions are required for inverted batch distillation. 

The minus sign comes from switching the limits of integration. Equation (9=7) is a form of the Rayleigh equation that is valid for both simple and multistage batch distillation. Of course, to use this equation we must relate Xp, to x and do the appropriate integration. This is covered in sections 9.2 and 2. ... 

Figure 9-5. McCabe-Thiele diagram for multistage batch distillation with constant IVD, Example 9-2...

Explain the operation of single and multistage batch distillation systems... 

Use the McCabe-Thiele method to analyze multistage batch distillation for ... 

Cl. For a binary, multistage batch distillation with constant prove that the mass balances over the entire batch period and the Raleigh equation give identical results. 

The book may be used for a methodical study of the subject or as a reference for solving day-to-day problems. It follows a logical flow of ideas within each chapter and from one chapter to the next yet each chapter is quite self-contained for quick reference. The discussion starts with fundamental principles, prediction of thermodynamic properties, the equilibrium stage, and moves on to the different types of multistage and complex multistage and multicolumn processes, batch distillation, and membrane separation operations. Although computer simulation is a central theme of this book, no previous experience in the use of simulation software is required. 

Batch distillation with reflux in a multistage column... 

Distillation. Distillation separates volatile components from a waste stream by taking advantage of differences in vapor pressures or boiling points among volatile fractions and water. There are two general types of distillation, batch or differential distillation and continuous fractional or multistage distillation (see also Distillation). 

As with the catalytic distillation reactor, the chromatographic reactor functions as a multistage reactor. The chromatographic reactor is essentially a batch reactor, and we need to adapt this configuration into a continuous process to develop a large-scale and economic process. 

FIGURE 16.5 The relationship of batch (simple) distillation to single and multistage continuous distillation. (Reprinted from Reuben and Burstall [43], courtesy of M.L. Burstall.)... 

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