Fungible bitumen from paraffinic centrifugation

Abstract

A process for cleaning bitumen froth produced from an oil sands extraction process involves mixing a sufficient amount of paraffinic solvent with the bitumen froth; subjecting the resulting mixture to centrifugal separation in a centrifuge to yield a diluted bitumen product, a water byproduct stream, and a solids byproduct stream; and processing the diluted bitumen product to yield dry fungible bitumen product having a total water / solids content less than about 0.5 wt %, and a recyclable paraffinic diluent stream.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to a paraffinic bitumen froth treatment process using centrifugation to produce a fungible bitumen product.BACKGROUND OF THE INVENTION[0002]Oil sand generally comprises water-wet sand grains held together by a matrix of viscous heavy oil or bitumen. Bitumen is a complex and viscous mixture of large or heavy hydrocarbon molecules which contain a significant amount of sulfur, nitrogen and oxygen. Oil sands processing involves extraction and froth treatment to produce diluted bitumen which is further processed to produce synthetic crude oil and other valuable commodities. Extraction is typically conducted by mixing the oil sand in hot water and aerating the resultant slurry to promote the attachment of bitumen to air bubbles, creating a lower-density bitumen froth which floats and can be recovered in a separator such as a gravity separator or cyclonic separator. Bitumen froth may contain about 60 wt % bitumen, about 30...

AI Technical Summary

Benefits of technology

This patent describes a process for treating paraffinic bitumen froth using a decanter centrifuge. This process reduces space and cost requirements compared to traditional methods. Additionally, the process reduces the amount of solids and asphaltenic hydrocarbon that are sent to a tailings pond, which in turn reduces the amount of solvent lost and reduces the risk of environmental hazards. The recovered asphaltenic hydrocarbon is then further processed in a flotation cell to recover more hydrocarbon, reducing diluent losses and reducing the need for fresh solvent makeup. Overall, this process minimizes expenditures and risks and produces a high-quality bitumen product.

Problems solved by technology

Due to the level of contamination, which pose fouling, corrosion and erosion problems, the diluted bitumen is not suitabie for direct pipelining to conventional refineries, cannot be sold to the open market, and must be upgraded using processes such as a coker or hydroprocessing.

However, paraffinic type diluents precipitate a major proportion of asphaltenes from the bitumen froth, resulting in not only the trapping of water and solids by the asphaltenes, but also high asphaltenic hydrocarbon losses (about 8%) to froth treatment tailings.

However, treatment processes using a naphthenic type diluent may still result in bitumen often containing undesirable amounts of solids and water.

Product solids lead to increased wear of downstream equipment, higher maintenance costs, and unplanned capacity losses and outages.

In addition, hydrocarbon may also be lost to tailings due to inefficient separation.

Solvent and precipitated asphaltenes may also be lost to the tailings.

Since the rejected asphaltenes (7-8 wt % of the original bitumen in froth) can be used as fuel or feedstock for various applications, the disposal of asphaltenes in the tailings pond is wasteful.

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