#2 Crude/Vacuum Distillation Unit (#2 CDU/VDU)

The #2 Crude & Vacuum unit, Unit 21, separates the crude oil feedstock into its various boiling range fractions, producing both saleable products and feedstocks for secondary units. The unit has been upgraded to a design processing capacity of 50,000 BPSD on predominantly sweet crudes. The integrated vacuum unit section has a design capacity of 16,500 BPSD. It produces light oils and vacuum gas oil feeds for the nearby Mississauga Lube plant. The #2 CDU/VDU consists of a preheat exchanger train, desalter, atmospheric column, vacuum column, 3 side strippers, a splitter, a stabilizer, and 3 fired heaters.

The raw crude is heated in the preheat exchangers, recovering energy from the exiting products and unit internal circulating reflux streams. It is then mixed with fresh water and fed into the desalter, where the salt, water and sediment are removed to prevent corrosion, plugging of exchangers, and potential catalyst poisoning in downstream units. After further heating in the preheat train and fired heaters, the desalted crude is charged to the primary atmospheric distillation column.

The overhead full range naphtha stream is sent to a splitter, where heavy naphtha is recovered for feed to the Iso-Ref Unit. The splitter overhead is fed to a stabilizer where light ends (butanes and lighter components) are removed and stabilized light straight run naphtha is produced. The primary column also separates light and heavy distillate, virgin light gas oil (VLGO) and atmospheric gas oil (AGO). The distillates and VLGO flow into side strippers where they are steam stripped to meet flash point specifications. The AGO is used as hot FCCU feed. The bottoms (reduced crude) from the primary column are pumped through the Vacuum heater to the Vacuum column. This column is operated under vacuum so that distillation can be carried out at temperatures below the thermal cracking temperature. Light and Heavy Vacuum Gas Oils are recovered as side cuts. These two side cuts (LVGO & HVGO) are sent to Mississauga as Lube feed or could be combined and used as FCCU feedstock. The Vacuum Tower bottoms product is blended with cutterstock (primarily Light Cycle Stock) and sent to HFO Storage.