Let`s take a quick look at VB production process in refineries. After desulfurization of crude oil, it will be entered to Distillation tower and will be heated up. Then different materials exit from different tower`s height in different temperatures. Lighter materials come out of the highest point of the distillation tower, and in bottom of the tower, materials are heavier. The residue will be transferred to Vacuum Tower. As its name implies, inside of this tower is vacuumed and then it will be heated up again but in lower temperatures. The residue of Vacuum Tower named Vacuum Bottom which is feedstock for bitumen productions.