Petroleum distillation

Distillation is a process of separating the component or substances from a liquid mixture by selective evaporation and condensation. Distillation may result in essentially complete separation (nearly pure components), or it may be a partial separation that increases the concentration of selected components of the mixture. In either case the process exploits differences in the volatility of the mixture's components. In industrial chemistry, distillation is a unit operation of practically universal importance, but it is a physical separation process and not a chemical reaction.

Commercially, distillation has many applications. For example:

An installation for distillation, especially of alcohol, is a distillery. The distillation equipment is a still.

Distillation is a very old method of artificial desalination.

Aristotle wrote about the process in his Meteorologica and even that "ordinary wine possesses a kind of exhalation, and that is why it gives out a flame". Later evidence of distillation comes from Greek alchemists working in Alexandria in the 1st century AD.Distilled water has been known since at least c. 200, when Alexander of Aphrodisias described the process. Work on distilling other liquids continued in early Byzantine Egypt under the Greek-Egyptian Zosimus of Panopolis. Distillation in China could have begun during the Eastern Han Dynasty (1st–2nd centuries), but archaeological evidence indicates that actual distillation of beverages began in the Jin (12th–13th centuries) and Southern Song (10th–13th centuries) dynasties. A still was found in an archaeological site in Qinglong, Hebei province dating to the 12th century. Distilled beverages were more common during the Yuan dynasty (13th–14th centuries). Arabs learned the process from the Alexandrians and used it extensively in their chemical experiments.

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