Ponchon-Savarit binary mixture graphical method

The method of Ponchon and Savarit [2.61] is a graphical determination of the number of theoretical separation stages in counterflow columns. It is particularly applicable to binary mixtures in rectification processes. Exact results are obtained when the enthalpy-concentration diagram of Pon-... 

An alternative graphical method for handling binary mixtures is that of Ponchon and Savarit, and while more cumbersome to use than McCabe-Thiele, it dlows for variations in the molar latent heat of vaporization and thus removes the principal assumption of the McCabe-Thiele method. As basic information it requires not only a y -x equilibrium relationship but also data on enthalpy of vaporization as a function of composition, and, except for a few mixtures, such data are not readily available. 

Two common graphical procedures used to calculate the number of theoretical plates for a separation system involving binary mixtures are the McCabe-Thiele and the Ponchon-Savarit methods. The former method is based on the assumptions of constant vapor and liquid flow rates, or constant molal overflow, throughout the column and negligible heat losses, whereas the latter method does not assume constant molal overflow. Before developing the appropriate material balances for either procedure, some standard notation and definitions are necessary. 

Another graphical design method for binary systems is that of Ponchon" and Savarit. This method includes an energy balance on each stage and is totally rigorous for binary systems. However, it requires mixture enthalpy data, often unavailable, and is cumbersome in application. 

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