Upgrading Process
Most operating refineries are configured to process light and medium grades of low-sulphur crude oil and not the bitumen that is produced from oil sands. Intermediate processing in the form of "upgrading" transforms the bitumen into suitable refinery feedstock.
Upgrading combines the use of temperature, pressure and chemical reactions to break up the large carbon chains found in heavy oils and bitumen and reorganizes them into more readily processed molecules.
Current upgrading technology can be grouped into two categories: carbon rejection and hydrogen addition. The Voyageur Upgrader uses a carbon rejection based technology known as delayed coking, which was selected as the processing technology after an extensive screening process.
Process Overview
Simplified block flow diagram of the upgrading process
(click for larger view)
Raw bitumen is too viscous (thick) to be transported by pipeline at ambient temperature and therefore is transported as hot bitumen. This bitumen forms the feed for the delayed coker unit.
The coking vessels are specifically designed to convert the heavier hydrocarbon molecules into lighter hydrocarbon fractions. The naphtha, kerosene (diesel) and gas oil fractions from the coker unit are sent to the hydrotreating units to remove sulfur, which itself is recovered in the sulfur units. The hydrogen required for this hydro-treatment is produced onsite using conventional technology out of natural gas.
The resulting low sulphur naphtha, diesel and gas oil streams are then mixed together in specific ratios to produce synthetic crude oil or defined finished products.
The hydrocarbons remaining in the coking vessels are in the form of solid carbon, known as petroleum coke. Coke and sulfur—byproducts of the proposed upgrading process—will be stored on project lands and possibly transported to customers in domestic and offshore markets after evaluating the different options.
Learn about Total and Suncor's joint development of the Voyageur Upgrader in Fort McMurray, Alberta.