Distillation in the petroleum refinery is different from most distillation operations in two principal ways:
* Thousands of molecular species are present. The separations are roughly by molecular weight, thus yielding a differentiation of physical properties.
* In many cases, the distillation feed contains species of high molecular weight, which cannot be readily boiled in shell-and-tube heat exchangers such as those used in most distillation processes.
Keywords: Distillation; Refining; Vacuum columns; Petroleum; Gasoline; Fuel oil; Cracking; Crude oil; Lubricating oil