Heuristics zeotropic mixtures

For sequencing the separation of liquid mixtures, there are general heuristics, as shown in Table 3.11. More specific rules for the separations of zeotropic mixtures by distillation will be discussed later in this chapter. 

The procedure known as the list-processing method allows the designer to identify feasible sequences for separating ideal or slightly nonideal zeotropic mixtures by means of simple distillation columns. Table 3.13 presents a list of more specific heuristics for sequencing, supplementary to those in Table 3.7. The first one shows... 

Table 3.13 Heuristics for separation sequencing of zeotropic mixture.

The rest of heuristic rules are less obvious. The fourth rule sequences with minimum number of columns are preferable. Hence, it follows that splits with distributed components have to be excluded if there are ones without them. Capital costs at minimum number of columns are the smallest. However, energy expenditures in this case are not always the smallest. For zeotropic mixtures, the situation is the same as for azeotropic flowsheets with prefractionator are more profitable sometimes than without it (see Section 8.2). Therefore, the designer has to decide him- or herself if he or she should use this rule at the stage of automatic sequences. 

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