Residue curve

A residue curve describes the change in the composition of the liquid phase of a chemical mixture during continuous evaporation at the condition of vapor–liquid equilibrium (open distillation).

Residue curves allow testing the feasibility of a separation of mixtures and therefore are a valuable tool in designing distillation processes.

Residue curve maps are typically used for examining ternary mixtures which can't be easily separated by distillation because of azeotropic points or too small relative volatilities.

The calculation of residue curves is done by solving the mass balance over time by numerical integration with methods like Runge-Kutta.

Two nodes are stable (pure methanol and the binary azeotrope of chloroform and acetone which have both the lowest vapor pressure (isothermal calculation) in their two regions where they are part of.