Side stream column

The case studies were selected to reflect different separation difficulties and different contents of the intermediate component of the quaternary mixtures. The mixtures considered are displayed in Tables 1-2. The mole fraction of 0.05 was shown to be a borderline value for use of side-stream columns for ternary separations (Tedder and Rudd, 1978). The total feed flowrate for all cases was 45.5 kmol/h. Since the feed involves a hydrocarbon mixture, the Chao-Seader correlation was used for the prediction of thermodynamic properties. The design pressure for each sequence was chosen such that all condensers could be operated with cooling water. 

Another solution is the use of a flash as pre-separator of lights from heavies, while the purification of the bulk component takes place in a second side-stream column. This device offers the simultaneous removal of lights and heavies. A practical example is the purification of phtalic anhydride (Dimian, 1997). 

Simple Distillation. In this category, we include the separation of ideal or slightly non-ideal mixtures that do not form azeotropes, based on the differences in the relative volatilities of components. A simple column designates a device that separates one or several feeds in only two products top distillate and bottoms. Complex columns are can deliver more than two products. In this category we include columns with side-streams, columns equipped with auxiliary devices, as prefractionators, side-strippers and side-rectifiers, as well as thermally integrated columns. 

Table 11.4 Characteristics of prefractionator/side stream column heat integrated system...

Figure 11.21 Thermally integrated side-stream columns...

Figure 13.29 Prefractionator /side stream column with forward integration...

The liquid stream contains benzene and toluene, as well as heavy impurities, mainly diphenyl, with traces of dissolved gases. The gaseous components are removed in a stabiliser, followed by the separation of the liquid mbcture by distillation either as two-column sequence (benzene production and toluene recycling), or as single side-stream column. 

Retrofit of Side Stream Columns to Dividing Wall Columns, with Case Studies of Industrial Applications... 

Figure 9.1 Distillation arrangements (a) direct sequence, (b) indirect sequence, and (c) side stream column for separating a ternary mixture.

The purity of the side stream product is restricted by thermodynamics and the nature of the distillation process, which cause these columns to be appropriate either as prefractionators (that is, the side stream is fed to another column for further separation) or to generate recycle streams when there is no strict requirement on the recycle composition (Glinos and Malone, 1985). In addition, SSCs might be useful when the middle-boiling components are trace components or even the main product, as in a pasteurization column (Rooks et al, 1996). Note that the pasteurization column is a side stream column used to remove the light-ends in the vapor phase by using a fiill-reflux condenser. 

Retrofit of Side Stream Coiumns to Dividing Waii Coiumns 261 Side stream column Dividing wall column... 

Long, N.V.D. and Lee, M. (2013d) Optimal retrofit of a side stream column to adividing wall column for energy efficiency maximization. Chemical Engineering Research and Design, 91, 2291-2298. 

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