Fractionators with Ponchon-Savarit method

The major difference between the McCabe-Thiele method and the Ponchon-Savarit method is that the liquid and vapor flow rates in the latter method are not assumed constant throughout the column. Because of this, the Ponchon-Savarit method is a more general and accurate method. Since the method is based on enthalpy values of fluid mixtures throughout the column, an enthalpy-concentration diagram is used in conjunction with a vapor-liquid equilibrium plot to determine the number of theoretical plates required for a specific separation. Units based on either moles (and mole fractions) or mass (and mass fractions) are acceptable as long as they are consistent. 

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