Page 192 - Separation process engineering

For a more complex column the flowchart in Figure 4-30 would be modified by:
1. Including equations for intermediate operating lines.

2. Including additional tests for optimum feeds [change Eqs. (4-37a,b)].
3. Including side streams

The principles again follow McCabe-Thiele calculations step by step.

The development of digital computers has made the graphical McCabe-Thiele technique obsolete for
detailed design calculations. Engineers used to cover an entire wall with graph paper to do a McCabe-
Thiele diagram when a very large number of stages were required. The method is still useful for one or
two calculations, but its major uses are as a teaching tool and as a visualization tool. The graphical
procedure presents a very clear visual picture of the calculation that is easier to understand than the
interactions of the equations. The graphs are also extremely useful as a tool to help determine what the