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.

1 . A process for pre-treating an aqueous hydrocarbon-containing feed for downstream solvent-based extraction processing for bitumen recovery, said aqueous hydrocarbon-containing feed comprising from 60 wt % to 95 wt % water, from 0.1 wt % to 10 wt % bitumen, and from 5 wt % to 40 wt % solids, wherein said solids comprise fines, the process comprising:
 removing water from the aqueous hydrocarbon-containing feed to produce an effluent comprising 40 wt % water or less; and   providing the effluent to a downstream solvent-based extraction process comprising fines agglomeration to recover bitumen.   
     
     
         2 . The process according to  claim 1  wherein removing water from the aqueous hydrocarbon-containing feed comprises:
 flowing the aqueous hydrocarbon-containing feed into a primary water separation system to remove water from the aqueous hydrocarbon-containing feed, producing a reduced-water stream of from 30 wt % to 60 wt % solids, and recycled water; and 
 removing water from the reduced-water stream using a secondary water separation system to produce an effluent comprising 40 wt % water or less. 
 
     
     
         3 . The process of  claim 2  wherein the primary water separation system comprises a clarifier, a settler, a thickener or a cyclone. 
     
     
         4 . The process of  claim 3  wherein a flocculant is added to the aqueous hydrocarbon-containing feed in the clarifier. 
     
     
         5 . The process of  claim 3  wherein a solvent or flocculant is mixed with the aqueous hydrocarbon-containing feed prior to water separation in the clarifier. 
     
     
         6 . The process of  claim 5  wherein solvent is mixed with the aqueous hydrocarbon-containing feed with a solvent:bitumen ratio of less than about 2:1. 
     
     
         7 . The process of  claim 5 , wherein a low boiling point cycloalkane solvent is mixed with the aqueous hydrocarbon-containing feed. 
     
     
         8 . The process of  claim 2 , wherein the secondary water separation system comprises a centrifuge with filtering capacity, a shale shaker, or one or more clarifiers. 
     
     
         9 . The process of  claim 1 , wherein the aqueous hydrocarbon-containing feed comprises effluent of a froth separation unit. 
     
     
         10 . The process  claim 1 , wherein the aqueous hydrocarbon-containing feed comprises tailings from a tailings solvent recovery unit. 
     
     
         11 . The process of  claim 1  additionally comprising a process for recovery of bitumen, wherein the downstream solvent-based extraction comprises:
 combining a first solvent with the effluent and a bituminous feed from oil sands to form an initial slurry; separating the initial slurry into a fine solids stream and a coarse solids stream; agglomerating solids from the fine solids stream to form an agglomerated slurry comprising agglomerates and a low solids bitumen extract; separating the low solids bitumen extract from the agglomerated slurry; mixing a second solvent with the low solids bitumen extract to form a solvent-bitumen low solids mixture, the second solvent having a similar or lower boiling point than the first solvent; subjecting the mixture to gravity separation to produce a high grade bitumen extract and a low grade bitumen extract; and recovering the first and second solvent from the high grade bitumen extract, leaving a high grade bitumen product. 
 
     
     
         12 . The process of  claim 1  additionally comprising a process for recovery of bitumen, wherein the downstream solvent-based extraction process comprises:
 combining a first solvent with the effluent and a bituminous feed from oil sands to form an initial slurry; separating the initial slurry into a fine solids stream and a coarse solids stream; agglomerating solids from the fine solids stream to form an agglomerated slurry comprising agglomerates and a low solids bitumen extract; mixing a second solvent with the agglomerated slurry to form a solvent-bitumen agglomerated slurry mixture, the second solvent having a similar or lower boiling point than the first solvent; subjecting the mixture to separation to produce a high grade bitumen extract and a low grade bitumen extract; recovering the first and second solvent from the high grade bitumen extract, leaving a high grade bitumen product; and 
 recovering the first and second solvent from the low grade bitumen extract, leaving a low grade bitumen product. 
 
     
     
         13 . The process of  claim 1  additionally comprising a process for recovery of bitumen, wherein the downstream solvent-based extraction process comprises:
 combining a first solvent with the effluent and a bituminous feed from oil sands to form an initial slurry; separating the initial slurry into a fine solids stream and a coarse solids stream; recovering the first solvent from the coarse solids stream; 
 agglomerating solids from the fine solids stream to form an agglomerated slurry comprising agglomerates and a low solids bitumen extract; separating the low solids bitumen extract from the agglomerated slurry; mixing a second solvent with the low solids bitumen extract to form a solvent-bitumen low solids mixture, the second solvent having a similar or lower boiling point than the first solvent, subjecting the mixture to gravity separation to produce a high grade bitumen extract and a low grade bitumen extract; and recovering the first and second solvent from the high grade bitumen extract, leaving a high grade bitumen product. 
 
     
     
         14 . The process of  claim 1  additionally comprising a process for recovery of bitumen, wherein the downstream solvent-based extraction process comprises:
 combining a first solvent with the effluent and a bituminous feed from oil sands to form an initial slurry; separating the initial slurry into a fine solids stream and a coarse solids stream; 
 recovering the first solvent from the coarse solids stream; agglomerating solids from the fine solids stream to form an agglomerated slurry comprising agglomerates and a low solids bitumen extract; 
 mixing a second solvent with the agglomerated slurry to form a solvent-bitumen agglomerated slurry mixture, the second solvent having a similar or lower boiling point than the first solvent; 
 subjecting the mixture to separation to produce a high grade bitumen extract and a low grade bitumen extract; recovering the first and second solvent from the high grade bitumen extract, leaving a high grade bitumen product; and recovering the first and second solvent from the low grade bitumen extract, leaving a low grade bitumen product. 
 
     
     
         15 . The process of  claim 1  additionally comprising a process for recovery of bitumen, wherein the downstream solvent-based extraction comprises:
 combining a first solvent with the effluent and a bituminous feed from oil sands to form an initial slurry; agglomerating solids from the initial slurry to form an agglomerated slurry comprising agglomerates and a low solids bitumen extract; separating the low solids bitumen extract from the agglomerated slurry; mixing a second solvent with the low solids bitumen extract to form a solvent-bitumen low solids mixture, the second solvent having a similar or lower boiling point than the first solvent, subjecting the mixture to gravity separation to produce a high grade bitumen extract and a low grade bitumen extract; and recovering the first and second solvent from the high grade bitumen extract, leaving a high grade bitumen product; 
 wherein the ratio of first solvent to bitumen in the initial slurry is selected to avoid precipitation of asphaltenes during agglomeration. 
 
     
     
         16 . The process of  claims 1  additionally comprising a process for recovery of bitumen, wherein the downstream solvent-based extraction comprises:
 combining a first solvent with the effluent and a bituminous feed from oil sands to form an initial slurry; agglomerating solids from initial slurry to form an agglomerated slurry comprising agglomerates and a low solids bitumen extract; mixing a second solvent with the agglomerated slurry to form a solvent-bitumen agglomerated slurry mixture, the second solvent having a similar or lower boiling point than the first solvent; subjecting the mixture to separation to produce a high grade bitumen extract and a low grade bitumen extract comprising substantially all solids and water; recovering the first and second solvent from the high grade bitumen extract, leaving a high grade bitumen product; and recovering the first and second solvent from the low grade bitumen extract, leaving a low grade bitumen product; 
 wherein the ratio of first solvent to bitumen in the initial slurry is selected to avoid precipitation of asphaltenes during agglomeration. 
 
     
     
         17 . A system for pre-treating an aqueous hydrocarbon-containing feed for downstream solvent-based extraction processing for bitumen recovery, said aqueous hydrocarbon-containing feed comprising from 60 wt % to 95 wt % water, from 0.1 wt % to 10 wt % bitumen, and from 5 wt % to 40 wt % solids, wherein said solids comprises fines, the system comprising:
 a dewatering unit for removing water from the aqueous hydrocarbon-containing feed to produce an effluent comprising 40 wt % water or less; and   a conduit for providing the effluent to a downstream solvent-based extraction process comprising fines agglomeration to recover bitumen.   
     
     
         18 . The system of  claim 17  wherein the dewatering unit comprises:
 a primary water separation system to remove water from the aqueous hydrocarbon-containing feed, producing a reduced-water stream and recycled; and 
 a secondary water separation system for receiving the reduced-water stream and removing water therefrom to produce an effluent comprising 40 wt % water or less. 
 
     
     
         19 . The system of  claim 17  additionally comprising the following components for recovery of bitumen in the downstream process solvent-based extraction:
 a slurry system wherein a bituminous feed is mixed with effluent from the de-watering system and a first solvent to form an initial slurry; a fine/coarse solids separator in fluid communication with the slurry system for receiving the initial slurry and separating a fine solids stream therefrom; an agglomerator for receiving a fine solids stream from the fine/coarse solids separator, for agglomerating solids and producing an agglomerated slurry; a primary solid-liquid separator for separating the agglomerated slurry into agglomerates and a low solids bitumen extract; a gravity separator for receiving the low solids bitumen extract and a second solvent; and 
 a primary solvent recovery unit for recovering the first solvent or the second solvent in a high grade bitumen extract arising from the gravity separator and for separating bitumen therefrom. 
 
     
     
         20 . The system of  claim 17  additionally comprising the following components for recovery of bitumen in the downstream process solvent-based extraction:
 a slurry system wherein a bituminous feed is mixed with a first solvent to form an initial slurry; an agglomerator for receiving the initial slurry, for agglomerating solids and producing an agglomerated slurry; a primary solid-liquid separator for separating the agglomerated slurry into agglomerates and a low solids bitumen extract; a gravity separator for receiving the low solids bitumen extract and a second solvent; and a primary solvent recovery unit for recovering the first solvent or the second solvent in a high grade bitumen extract arising from the gravity separator and for separating bitumen therefrom.