A Crosscurrent Extraction Cascade in Triangular Coordinates

Illustration 7.6 A Crosscurrent Extraction Cascade in Triangular Coordinates 

Solution of this problem calls for the repeated application of the methods established for single-stage extraction in Illustration 7.2. We start by drawing a line connecting the solvent at B to the feed located at f, and follow this by locating the mixing point M, using Equation 7.4c. We obtain 

From this tabulation it emerges that three stages are too few and four stages too many to reduce acetone content in the raffinate to Xj = 0.10. There are three alternatives we can pursue  

Use three stages and slightly more solvent per stage, determining the quantity to be used by trial and error until = 0.10. 

Use four sfages and slightly less solvent, again with a trial-and-error 

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