Distillation is a widely-used separation technique which uses heat to vaporise liquid mixtures before condensing them back down, isolating their individual components by applying heat. Volatile components are separated from non-volatile ones through this process; typically the volatile fraction is known as heads and the rest hearts and tails (head being highest volume component and tail as lowest). Distillate runs can contain one or both heads or hearts or tails containing low boiling point compounds with undesirable impurities which must be eliminated prior to creating their final spirit product.
Distillation operates under the assumption that all components in a liquid at a given temperature have their own individual boiling point, and can therefore be separated based on these. Unfortunately, however, liquid mixtures often comprise different azeotropes with differing boiling points which form bands overlapping one another; to create ultra-pure products more chemical separation processes must be used in addition to distillation to remove impurities from distillate.
There are various techniques for breaking an azeotrope and producing pure distillates, including increasing or decreasing pressure, adding or subtracting components from its composition, or physically separating it.
Hybrid processes that use solvent extraction and absorption require considerable amounts of energy to reach high temperatures necessary for volatiles to vaporise from compounds, as well as maintaining suitable pressure in these processes. Achieveing this may present additional challenges for plants.
