Once the natural gas is separated by the flash column, it is then fed to the distillation operation. The same concept is applied to distillation as in the thermal flash in the oil-gas separation unit in the previous step. However, because all of the natural gas components are fairly "light," separation is trickier.

Different strategies can be used to separate ethane from the natural gas mixture. The number of distillation column needed depends on what strategy we use.

Some of the issues that engineers deal with include how many columns to build. Again, this depends on the strategy used. The conditions at which the columns are operated are also important. Energy usage is one of the more expensive items in plant operation. All in all, the main goals are to obtain ethane at a pure level while saving as much money as possible.