Oil

The refining process is fractional distillation, which separates the oil into its component parts or fractions. The crude oil is heated, which turns the semi-solid crude oil into vapour. It is then piped into a tall tower divided by a series of perforated horizontal trays. The heavier fractions condense first and settle out on the lower trays. The perforations are fitted bubble caps that force the vapour to bubble through a previously liquefied fraction on the tray.

This bubbling cools the vapour slightly, which causes that fraction to condense in the tray. That section is vapourized while it continues to move upward in the distillation tower. The process is repeated at each tray, with each fraction condensing at the tray where the temperature is slightly below that fraction’s boiling point. Several trays collect each fraction, and the fractions piped out for processing into diesel, furnace fuels, stove oil, gasoline, and petrochemicals.