1. Distillation is method of separating mixture based on differences in volatilities of component in a boiling liquid mixture. In industrial chemistry, distillation is a unit operation of practically universal importance, but it is a physical separation process and not a chemical reaction.
2. Early forms of distillation were batch processes using one vaporization and one condensation. Purity was improved by further distillation of the condensate. Greater volumes were processed by simply repeating the distillation. Chemists were reported to carry out as many as 500 to 600 distillations in order to obtain a pure compound.
3. The developing petroleum industry in the early 20th century provided the drive for the development of accurate design methods such as the McCabe–Thiele method and the Fenske equation. The availability of powerful computers has also allowed direct computer simulation of distillation columns (Aspen HYSYS Software).
4. A liquid mixture feed is pumped through a heater to raise the temperature and enthalpy of the mixture. It then flows through a valve and the pressure is reduced, causing the liquid to partially vaporize. Once the mixture enters a big enough volume (the flash drum or separator), the liquid and vapor separate. Because the vapor and liquid are in such close contact up until the "flash" occurs, the product liquid and vapor phases approach equilibrium. Final products are Distillates at the top of the flash drum and Residue/bottoms at the bottom of the flash drum.
5. Flash distillation, (sometimes called "equilibrium distillation) is a single stage separation techniques the simplest method of separation.

paragraphs are different so please paraphrase each seprat and note that 0% plagiarism