Multiple Feed and Refluxed Extractors

The formulation of the operating line equations and equilibrium relationships and their graphical implementation is not restricted to the basic extractor configuration but can be applied to columns with multiple feeds and reflux streams. The resulting complexity is handled by breaking up the column into sections, each with its own difference point. This is demonstrated for a column with an intermediate feed, resulting in two sections. 

A material balance on the top section of the column through any tray j above the feed gives 

FIGURE 11.6 Graphical construction for extractor with two feeds. 

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