Vacuum distillation

Vacuum distillation separates liquid mixtures at pressures below atmospheric pressure. Lower pressure reduces boiling temperatures, allowing high-boiling or heat-sensitive substances to be distilled with less thermal damage.

Vapor–liquid equilibrium: The balance of component concentrations between a liquid mixture and its vapor at equilibrium. It determines vapor composition and separation at the reduced pressures used in the column.
Crude oil vacuum distillation: The refinery process that separates atmospheric residue into lower-boiling heavy petroleum fractions under reduced pressure. It recovers useful heavy fractions without exposing residue to temperatures that cause extensive cracking.
Vapor pressure: The pressure exerted by a vapor in equilibrium with its condensed phase at a given temperature. A liquid boils when its vapor pressure reaches the pressure maintained in the apparatus.
Atmospheric distillation: Distillation carried out at approximately atmospheric pressure. It requires higher temperatures than vacuum operation for high-boiling mixtures.
Raoult's law: A relation that estimates a component’s partial vapor pressure from its liquid mole fraction and pure-component vapor pressure. It helps predict how mixture composition affects vapor formation under vacuum.
Molecular distillation: A high-vacuum separation method in which molecules travel short distances from an evaporating surface to a condenser. Its very low pressures and short exposure times suit especially heat-sensitive, high-molecular-weight substances.
Distillation: A separation process that uses differences in volatility to vaporize and then condense components of a mixture. Vacuum distillation is a pressure-modified form of this broader separation method.
Steam distillation: A method that co-distills water vapor with a water-immiscible substance to lower its effective boiling temperature. It lowers the temperature through a second vapor rather than by reducing system pressure.
Boiling point: The temperature at which a liquid’s vapor pressure equals the surrounding pressure. Reducing surrounding pressure lowers the temperature needed to boil each component.
Short-path distillation: A vacuum distillation arrangement with a short vapor path between an evaporator and a nearby condenser. The compact path limits residence time and pressure drop for sensitive or viscous materials.

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