DISTILLATION COLUMNS

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On the left is the schematic of a distillation column. The feed of our distillation column is natural gas, a mixture of many different gaseous hydrocarbons, which was mentioned before.

The two streams coming out of the distillation column are separated by the light key and the heavy key. The light and heavy keys are defined by their moleular weights and boiling points. The light key, by definition, has a lower boiling point than the heavy key.

To the right is a sketch of the inside of a distillation column. A distillation column consists of many trays inside the column, which provide a place for the liquid and vapor to interact as they flow through the column. As the two streams interact, the mass transport and separation occurs.

There can be many ways to separate out the components in a column. With as few as five components, there are 14 ways of separation, and with 6 components, there are 42 ways! This is even more impressive when you realize that a typical barrel of oil contains more than 20 components.

If you are interested in seeing the heuristics used to choose the order of separation, click here: