Trajectories in Infinite Complex Columns and Complexes

This chapter extends the geometric description of the distillation process to infinite complex columns and complexes, and then on this basis to develop methods of their calculation. 

Here we understand by complex colunms a countercurrent cascade without branching of flows, without recycles and bypasses, which, in contrast to simple columns, contains more than two sections. The complex colunm is a column with several inputs and/or outputs of flows. The column of extractive distillation with two inputs of flows - feed input and entrainer input - is an example of a complex column. 

We understand by distillation complex a countercurrent cascade with branching of flows, with recycles or bypasses of flows. Columns with side stripping or side rectifier and columns with completely connected thermal flows (the so-called Petlyuk columns ) are examples of distillation complexes with branching of flows. A column of extractive distillation, together with a column of entrainer regeneration, make an example of a complex with recycle of flows. Columns of this complex work independently of each other therefore, we do not examine it in this chapter, and the questions of its usage in separation of azeotropic mixtures and questions of determination of entrainer optimal flow rate are discussed in the following chapters. 

The fundamental difference between complex columns and complexes and simple columns lies in the availability of intermediate sections (besides the top and the bottom ones). The intermediate sections exchange vapor and liquid flows with other sections or with the decanter. 

For the section between points of feed input Fi and product output Du the equation of material balance is as follows  

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Distillation Trajectories in Infinite Complex Columns and Complexes... 

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