Residue curve

A residue curve describes the change of the composition of the liquid phase of a chemical mixture during continuous evaporation at the condition of vapor–liquid equilibrium (open distillation). Multiple residue curves for a single system are called residue curves map. A residue curve describes the change of the composition of the liquid phase of a chemical mixture during continuous evaporation at the condition of vapor–liquid equilibrium (open distillation). Multiple residue curves for a single system are called residue curves map. 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. Pure components and azeotropic points are called nodes. Three different types are possible: The distillation regions and the nodes are the topology of the mixture. The calculation of residue curves is done by solving the mass balance over time by numerical integration with methods like Runge-Kutta. d x d ξ = x − y {displaystyle {frac {dx}{dxi }}=x-y}