Refining Oil

If you take crude oil and you heat it, you can easily separate and sort the different sized chains. The reason you can do this is because each different length of carbon chain has a different boiling point. For example, a chain with just one carbon atom in it (CH4) is the lightest chain, known as methane. Methane is a gas so light that it floats like helium. As the chains get longer, they get heavier.

So you boil the crude oil, and then you have a column that cools the vapor back down at different temperatures. You tap off the different products at different temperatures, and voila, you have separated all the chains.

Image courtesy © BP p.l.c. Oil refinery

The short chains are gases used in butane lighters and propane grills. The chains with five, six or seven carbons are called Naphtha. These are thin, clear liquids. Dry cleaners use Naphtha to clean clothes. Gasoline uses chains between seven and 11 carbons long. Kerosene (jet fuel) is 12 to 15 carbons long. Diesel fuel is next, then heating oil. When the chains get longer than about 20 carbons, they become solids at room temperature. It goes from paraffin wax to tar to asphalt in this range, depending on the length.

All of these different substances come from crude oil. The only difference is the length of the carbon chains! The refinery simply sorts out the different chain lengths.

Supertankers The biggest ships in the world are the supertankers that carry oil. The United States imports millions of barrels of oil every day. Most of it arrives on these huge ships. A supertanker normally holds about 2 million barrels of oil. The biggest supertankers weigh more than a billion pounds once they are loaded. The biggest supertanker today is named the Knock Nevis. It's more than 1,500 feet long and holds 4 million barrels of oil (about 170 million gallons). Loading a ship this big takes time. A loading platform for a normal supertanker might have three flexible pipes to fill the ship. The pipes are 16 inches in diameter, and each one pumps 75,000 barrels of oil per hour. Even with all that, it takes nine or 10 hours to load the ship.