Recovery of Hydrocarbon From Aqueous Streams

Abstract

A process is described for pre-treating an aqueous bituminous feed for downstream bitumen extraction. The process involves removing water from an aqueous bituminous feed having a water content of 60% or more by weight. After water is removed, an effluent comprising 40% water or less is formed, and is ready for downstream extraction. In the downstream extraction process, a dual solvent extraction process may be employed, incorporating agglomeration of fines to simplify subsequent solid-liquid separation. The process permits recovery of hydrocarbon that has conventionally remained in waste streams from oil sands processing, and thus has conventionally been lost. In one embodiment, removing water comprises subjecting the aqueous bituminous feed to a primary water separation system to reduce the water content of the feed, followed by subsequent water removal, thereby producing an effluent having a water content of 40% or less, which can then go on to further processing.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from Canadian patent application number 2,704,927 filed on May 21, 2010 entitled Recovery of Hydrocarbon from Aqueous Streams, the entirety of which is incorporated by reference herein.[0002]This application contains subject matter related to PCT patent application number PCT / US2010 / 062312, entitled “Process and System for Recovery of Bitumen From Oil Sands,” filed on Dec. 29, 2010 and PCT patent application number PCT / US2010 / 056727, entitled “Process and System for Recovery of Bitumen From Oil Sands,” filed on Nov. 15, 2010.FIELD OF THE INVENTION[0003]The present invention relates generally to a process for hydrocarbon extraction from mineable deposits, such as bitumen from oil sands, and to a system for implementing such a process. Processes and systems are described for recovery of hydrocarbon associated with waste streams produced in conventional water-based bitumen extraction processes.BACKGROUND OF T...

AI Technical Summary

Benefits of technology

[0023]It is an object of the present invention to obviate or mitigate at least one disadvantage of previous processes and systems for hydrocarbon extraction from mineable deposits such as oil sands.

[0026]The use of low boiling point solvents advantageously permits recovery of solvent with a lower energy requirement than would be expended for recovery of high boiling point solvents. By conducting solvent extraction and agglomeration steps independently, shorter residence times in the agglomeration unit can be achieved.

[0027]The sequential nature of the process allows for flexible design of a slurry feed system which permits high throughput from a smaller sized agglomeration unit, as well as faster bitumen production.

[0028]When the optional step of steam pre-conditioning is employed in the process, this realizes the further advantage that steam not only heats the slurry or oil sands, but adds the water necessary for the later agglomeration process.

[0029]Advantageously, the inventive process permits formation of bitumen products with an acceptable composition for sale or processing at a remote refinery, and thus these products need not be processed by an onsite upgrader.

[0030]As a result of the process, a high quality (or high grade) bitumen product is formed which is able to meet and / or exceed quality specifications of low water content and low solids content required for pipeline transport and downstream processing. The process permits premium, dry and clean bitumen to be obtained as well as a lower grade bitumen product to be obtained (which in certain cases may comprise primarily of asphaltenes) for various commercial uses. By using the process described herein, it is possible to achieve a high grade bitumen product, as well as lower grades of bitumen products. For example, a high grade bitumen product is considered to be one containing less than about 0.04 wt % solids (400 ppm), which may be obtained according to the instant process. Further, such a product formed by the process described herein may contain about 0.5 wt % or less of water+solids of the dry bitumen product. Water content may be less than or equal to 200 ppm in the final high grade bitumen product. This is an improved result compared with the 0.2-0.5 wt % of solids in dry bitumen that can be achieved according to the previously described Govier and Sparks process. Low grade bitumen products having more than 400 ppm solids, and more than 200 ppm water may additionally be obtained.

Problems solved by technology

Solvent recovery from the solids produced in previously described processes would be difficult, due to the nature of the solvent proposed for use in the extraction process.

With such high boiling point solvents, the recovery would be energy intensive as significant energy is required to vaporize the residual hydrocarbon and to release hydrocarbon trapped within the agglomerates.

While this may have resulted in a high recovery of bitumen, the energy intensity required for solvent recovery would be too high to be adopted in a commercial application.

Although the method achieved low solids content in the resulting bitumen product with this approach, the solids content in the bitumen product fell short of optimal product quality of less than 400 ppm solids on a dry bitumen basis, especially for settling times less than 1 hour.

However, it is not described or suggested that a second solvent could be effectively applied to a solvent extraction process with simultaneous solids agglomeration without upsetting the agglomeration process.

The previously proposed process for agglomeration, as described by Govier and Sparks in “The SESA Process for the Recovery of Bitumen from Mined Oil Sands” (Proceedings of AOSTRA Oils Sands 2000 Symposium, Edmonton 1990, Paper 5), was of limited practicality partly due to the nature of the solvent which, when combined with tailings, made solvent recovery difficult.

However, the energy intensity required for the solvent recovery was also high.

Further, there was no suggestion in the Govier and Sparks process of how the process would have been adapted to employ a different solvent to more efficiently recover solvent, or of how appropriate feed slurry characteristics may have been achieved if a different solvent was employed.

However, occasionally solids agglomeration would cycle unpredictably and the fines content of the agglomerator discharge stream would rise dramatically.

Bitumen products with this composition are not fungible and can only be processed at a site coking facility or at an onsite upgrader.

This would provide limited flexibility for sale or processing in a remote refinery.

The above-described agglomeration processes integrated solvent extraction and agglomeration within the same mixing vessel, which is inefficient because means of pre-conditioning and conveyance of the bituminous feed into the extraction / agglomerating unit is thus complicated.

Conventional agglomeration units are large drums designed to integrate both the extraction and agglomeration aspects of the process, and are bulky and inefficient.

Residence time in such agglomeration units would be lengthy, and process kinetics imposed restrictions on residence time.

Dissolution time, the slow agitation required, limited slurry density, and the high containment volume required for extraction required the residence time in the agglomeration unit to be lengthy, and the process slow.

Further, solvent recovery was not of concern in many previous processes, and is not addressed in most previously described processes.

The processing problems associated with recovery of water and bitumen from aqueous sources, such as from conventional water-based hydrocarbon or bitumen extraction processes, are largely due to the presence of fines in the streams.

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