distilling

Alcohol distillation’s environmental impacts may not be as well known as those associated with gasoline production, yet both share many of the same environmental concerns, including flammability, biodegradation and the production of hazardous substances.

At an alcohol plant, the first distillation column works to extract alcohol from water by boiling. The amount of alcohol vapor condensed depends on its reflux ratio – as more is produced, but also energy costs increase due to more space being taken up by ethanol vapor than water vapor.

The second column recombines alcohol and water vapors into an approximately 90 to 95% pure alcohol mixture called heads or tails, which also contains small quantities of methanol which has an extremely lower boiling point than ethanol, yet its molecules cling together tightly within the still and are difficult to separate – Methanol is highly toxic to humans, and must be separated and discarded as soon as possible since prolonged exposure could result in blindness.

Bottoms is a liquid product resulting from distilling of the rest of the methanol-water vapor, collected in the third distillation column and condensed as bottoms. This material may then be burned to generate electricity or mixed with gasoline to make ethanol fuel, although for this latter option an extra energy-consuming blending tank must be installed as this adds further costs associated with distillation system operation.

Distillation’s History and Evolution Distillation is the chemical process of isolating components from a mixture by changing their phases (liquid to gas) and then altering their relative concentrations. Distillation processes can be applied to virtually all liquids, from water and petroleum to organic compounds like essential oils. Distillation has its origins in Mesopotamia where archaeological excavations revealed crude methods of distillation through terracotta objects found there. The alembic was likely invented around AD 200 – 300 by Egyptian alchemists Maria the Jewess or Zosimo of Panopolis to produce finer essences for perfumes and convert base metals to gold. The Greek term for an alembic was initially translated into Arabic as al-anbiq and then into English as alembic.

First bench stills were thick blown glass retorts coated with clay to moderate the heat of vaporization and prevent cracking or bleeding of glass. They were placed into a boiler of sand, ashes or water bath to maintain optimal conditions for distillation; eventually passing their contents through a condenser separated those with lower boiling points from those with higher ones – collected into fresh collection vessels after which repeated for the remaining fractions.

After the American Civil War, commercial distillation began to emerge at an industrial scale. Rail transportation of grain made distilling more cost-efficient; Aeneas Coffey even created his still in 1830 as an early version of a column still, which allowed distillers to reach higher proof levels more easily than with pot stills.