How does fractional distillation of crude oil work?
The distillation tower is arranged with a stack of chambers at different temperatures, each chamber cooler than the one below. Vapor can rise, and condensate can drain down. Vaporized oil is fed into the bottom chamber. The vapors will tend to rise until they reach the chamber where they condense, and collect there. If they drain down, they re-vaporize and rise again. The different fractions are drawn from the fluid collected in their respective chambers. A diagram could make it clearer, sorry, not possible here. A lot of engineering goes into keeping each of the chambers at the correct temperature for the fraction desired.
