Petroleum: Refining (OG-10)
The veteran unit of an oil refinery is the obsolete shell still. In some form it has been brewing petroleum products since the first American oil well was drilled. Almost anything resembling a closed vessel in which oil could be heated and vapors conducted away to be condensed has seen its day in refining. The fundamental units of a modern refinery are pipe stills, bubble towers, and condensers. There are also strippers, clay towers and gas separators.

Distillation first takes place in tall fractionating towers. Crude oil, heated to about 800o F, is largely vaporized as it enters the tower and rises through holes in horizontal trays. The rising vapors are cooled, and different fractions are condensed and withdrawn as liquids. Some fractions become asphalt, heavy fuel oil, kerosene and gasoline. Other fractions are used for plastics, fertilizers, and various chemicals.

Our Hoosier State Beneath Us: Oil and Gas