Alcohol distillation is a core process in the creation of spirits such as gin, vodka, rum and whiskey. Distillation differentiates spirits from other fermented beverages like beer and wine.
Distillation apparatus, more commonly referred to as stills, comprises three main parts. They include the following: (reboiler), condenser and receiver for extracting distillate from hot vapors cooled back down by condenser cooling, receiver from which concentrated or purified liquid can be extracted, air/moisture control/safety issues with vent connection; in sealed versions vacuum pump is often required in order to keep atmosphere pressure within acceptable levels).
Under negative pressure distillation conditions, in order to achieve the same concentration in the vapor state as would be achieved through normal pressure distillation methods, the boiling point must be decreased in order to achieve equal concentration in both states – an increased temperature difference will also be needed between the coolant and vapor phase requiring additional equipment and energy resources to make this possible.
Alcohol concentration in vapor does not remain static; rather it varies. At first, alcohol content peaks with the initial wash vapors but gradually diminishes through subsequent distillation fractions due to repeated evaporations and condensation processes, producing increasingly less-concentrated bottoms fractions as the process goes forward.