alcohol distillation

Alcohol distillation is one of the most widespread human methods used to create spirits, beers and wine. Distillation mixes raw materials with water before heating it to its boiling point in order to produce ethanol vapor which condenses into three liquid components known as heads, hearts and tails which can then be collected and sold – this process dates back thousands of years as Queen Cleopatra used it herself in creating perfumes and balms using cedar, cypress, ginger and myrrh.

Under vacuum (at pressures lower than 1/10 atmospheric), distillation eliminates azeotrope, permitting full separation to 100 percent alcohol. However, due to differences in vaporizability between water and alcohol requiring an extremely high reflux ratio of more than 20 in order to achieve this result – raising this ratio increases product purity but requires more energy consumption.

Once neutral spirit, most often produced through heart cutting, has reached room temperature, distillers examine its alcohol content and purity. If too low, they may redouble distillation efforts until their desired alcohol percentage has been achieved; or add water to dilute and bring down to an acceptable percentage.

As anyone interested in designing a small fuel alcohol plant should know, understanding its basic principles and how it operates is paramount to its success. Furthermore, selecting and evaluating equipment, systems and controls required for such projects requires great care – this publication covers these topics along with safety precautions as well as general selection criteria to assist when making informed decisions about alternatives.

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.