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Fractional distillation in a laboratory makes use of common laboratory glassware and apparatuses, typically including a Bunsen burner, a round-bottomed flask and a condenser, as well as the single-purpose fractionating column. Fractional distillation. As an example, consider the distillation of a mixture of water and ethanol. Ethanol boils at ...
[1] [2] Fractions are collected based on differences in a specific property of the individual components. A common trait in fractionations is the need to find an optimum between the amount of fractions collected and the desired purity in each fraction. Fractionation makes it possible to isolate more than two components in a mixture in a single run.
In a typical fractional distillation, a liquid mixture is heated in the distilling flask, and the resulting vapor rises up the fractionating column (see Figure 1). The vapor condenses on glass spurs (known as theoretical trays or theoretical plates ) inside the column, and returns to the distilling flask, refluxing the rising distillate vapor.
In such a process, a mixture is separated into fractions, which have compositions that vary according to a gradient. A fraction can be defined as a group of chemicals that have similar boiling points. A common fractionating process is fractional distillation, in which separation is achieved by condensing a vapor over a range of temperatures. [1]
A simple vacuum distillation system as exemplified above can be used, whereby the vacuum is replaced with an inert gas after the distillation is complete. However, this is a less satisfactory system if one desires to collect fractions under a reduced pressure.
Distillation column in a cryogenic air separation plant The cryogenic separation process [ 4 ] [ 5 ] [ 6 ] requires a very tight integration of heat exchangers and separation columns to obtain a good efficiency and all the energy for refrigeration is provided by the compression of the air at the inlet of the unit.
For the binary distillation depicted in Figure 1, the required number of theoretical plates is 6. Constructing a McCabe–Thiele diagram is not always straightforward. In continuous distillation with a varying reflux ratio, the mole fraction of the lighter component in the top part of the distillation column will decrease as the reflux ratio ...
Key fractional distillation concepts: theoretical stages, x-y diagrams, multicomponent distillation, column composition and temperature profiles; Process design and optimization: minimum reflux and minimum stages, optimum reflux, short-cut methods, feed entry location