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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 catalysts to break up the large carbon chains found in heavy crude 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. Total plans to use a carbon rejection based technology known as delayed coking. Delayed coking was selected as the processing technology after an extensive engineering screening process.
Advantages of delayed coking technology include the following:
- Well-proven, widely used and reliable.
- Produces less carbon dioxide per barrel of production.
- Assessed to be the most economic.
Process Overview
Raw bitumen is too viscous (thick) to be transported by pipeline and must be blended with light hydrocarbons to create a diluted bitumen that can be transported.
When the diluted bitumen arrives at the production site, it enters into a distillation unit which boils off the light hydrocarbons prior to upgrading. The lighter streams (mainly naphtha and gas oils) produced from the initial distillation units, will be fed directly into the hydrotreaters and desulphurization units. The heavier residue will form the feed for the cokers. These coking vessels are specifi cally designed to convert the heavier hydrocarbon molecules into lighter hydrocarbon fractions.
 The lighter naphtha and gas oils from the coker units, along with the light streams from the distillation units, will be sent to the hydrotreaters and desulphurization units to remove sulphur. The hydrogen required for hydrotreatment will be produced onsite using conventional technology and natural gas as feedstock.
The resulting hydrotreated gas oil and naphtha streams will then be mixed together in specific ratios to produce the required blend of synthetic crude oil.
The hydrocarbons remaining in the coker will be in the form of solid carbon, known as petroleum coke. Coke and sulphur, byproducts of the proposed upgrading process, will
be stored temporarily on project lands and then transported to customers in domestic and offshore markets. Total is currently evaluating a number of options for byproduct management. ** Simplified Block Flow Diagram**
Storage, Transportation and Markets
The upgrader facilities will also include storage tanks for feedstock, intermediary products and produced synthetic crude. Numerous pipelines cross the Industrial Heartland, carrying bitumen blend feedstock and synthetic crude to end use markets. During project development, commercial arrangements will be made with regional pipeline carriers to transport synthetic crude to markets. |
