Single-Solvent Fractional Extraction with Extract Reflux

Bruce S. Hoiden, M.S. Process Research Leader, The Dow Chemical Company Member, American Institute of Chemical Engineers [Process Fundamentals and Basic Calculation Methods, Calculation Procedures, Computer-Aided Calculations (Simulations), Single-Solvent Fractional Extraction with Extract Reflux, Liquid-Liquid Phase Separation Equipment]... 

Single-Solvent Fractional Extraction with Extract Reflux. 15-56... 

In a special case referred to as single-solvent fractional extraction with extract reflux, the wash solvent is comprised of components that... 

A potential fourth type of fractional extraction operation involves the use of reflux at both ends of a dual-solvent process, i.e., reflux to the raffinate end of the process (the stripping section) as well as reflux to the extract end of the process (the washing section). The authors are not aware of a commercial apphcation of this kind however, Scheibel [Chem. Eng. Prog., 62(9), pp. 76-81 (1966)] discusses such a process scheme in light of several potential flow sheets. In the special case of single-solvent fractional extraction with extract reflux, Skelland [Ind. Eng. Chem., 53(10), pp. 799-800 (1961)] has pointed out that addition of raffinate reflux is not effective from a strictly thermodynamic point of view as it cannot reduce the required number of theoretical stages in this special case. 

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