Distillation Column

Distillation is a process used to separate a mixture of two (or more) components into its virgin state by heating the mixture to a temperaturebetween their respective boiling points. For example, at atmospheric pressure, water boils at 212ºF and ethanol boils at about 176ºF. If the mixture of water and ethanol isheated to about 195ºF, the ethanol will boil and change into vapor which is then collected and condensed. The water will separateand remain as a liquid. A fractionating distillation column is used to make this process more efficient. See the picture below to better understand howcolumns work. The distillation column is made up of a series of stacked plates. A liquid feed containing the mixture of two or more liquids entersthe column at one or more points. The liquid flows over the plates, and vapor bubbles up through the liquid via holes in the plates.As liquid travels down the column, the vapor comes in contact with it several times due to the multiple plates – a critical process indistillation columns. The liquid and vapor phases are brought into contact because as one molecule of higher boiling materialconverts from vapor to liquid phase by energy release, another molecule of the low boiling material utilizes the free energy toconvert from liquid to vapor phase. The base of the distillation column contains a large volume of liquid consisting mostly of the liquid with higher boiling point (in ourexample, this would be water). Out of the base flows some of this liquid, some of which is heated in the re boiler and returned to thecolumn. This is called the boil up.