Very basic school level science and environmental studies have taught us about water cycle. In the process we learn about - evaporation, condensation and precipitation - chronologically. That is fundamental to the understanding of distillation as a process .
To put it very simply, distillation is a process by which solid components dissolved in a liquid is separated. This very basic process, with investment in heavy-duty technology is being widely used in Middle East to manufacture desalinated potable water.
In the laboratory, the process is heat induced, while industries use high pressure. And the cost involved in it is very high, which only wealthy nations facing water shortage like those of the Gulf Region can take recourse to.
However some industries, like the rose water industries rely on heat, given the nature of product they manufacture. The process is very simple -
Fresh rose petals are first boiled in water in huge copper containers.
Then the steam is allowed to flow throw a pipe and collected in cylinders.
Then they are cooled in a water bath and the condensed perfumed liquid is collected in metal jars.
Copper is highly preferred in this particular industry since it is strong, good conductor, durable and does not tamper with the final product. Companies take great care in the quality of the metal as adulteration can have adverse effects.
Pharmaceutical Industries also depend on distillation. Since it is necessary to see through the equipment how the potions are reacting, instead of opaque materials like metals, glass is preferred.
Now the glass that is generally used for regular purposes is not very heat resistant, special grade glasses, borosilicate glasses are used. They are hard, heat resistant, transparent. Hence suited for lab purposes.
Special apparatus consisting of - bulbous bottomed jars, condensation chambers with cavities to allow air to flow in, and a collector jar - is the most commonly seen arrangement, with variations that do not fundamentally deviate from this design.