Process Equipment and Plant Design
Ponchon Savarit method is based on the use of enthalpy concentration diagram, which contains the bubble point curve (saturated liquid curve), dew point curve (saturated vapour curve) and equilibrium tie lines. As compared to McCabe-Thiele's method, this method

Is more accurate in finding the number of equilibrium stages
All of these
Accounts for the enthalpy changes in the process
Facilitates direct calculation of heat load on reboiler & condenser from, the diagram used in this method