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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. == Characteristics == # Residue curves start at the composition of a feed and then move to pure components or azeotropic points with higher temperatures (isobaric condition) or lower vapor pressures (isothermal condition). This happens because more of the light boiling substances are vaporized than of the high boiling substances and therefore the concentration of the high boilers increase in the liquid phase. A residue curve can also be constructed backwards and then moves to the azeotropic point or pure component with lower temperatures or higher vapor pressure. # Azeotropic points can create so called distillation regions separated by border lines from other regions. If the composition of a feed lies inside a specific region a residue curve cannot cross a border line and stays in its initial region. This means for a distillation tower that it is not possible to obtain pure components at the bottom and the head of the column. At least at one outlet an azeotropic mixture is obtained. # The same conclusion is valid for the pure components. If they are in different distillation regions mixtures of these pure components can't be separated by simple distillation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Residue curve」の詳細全文を読む スポンサード リンク
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