Processes and Systems For Solvent Extraction of Bitumen From Oil Sands

Abstract

Processes and systems are described for solvent extraction of bitumen from oil sands. Fines agglomeration is employed to simplify subsequent separation. A high quality bitumen product can be formed, which meets or exceeds downstream processing and pipeline requirements. An embodiment comprises combining a first solvent and a bituminous feed to form an initial slurry, which is optionally separated into fine solids and coarse solids. Slurry solids are agglomerated. A low solids bitumen extract from the agglomerated slurry is mixed with a second solvent having a similar or lower boiling point than the first. The mixture is separated, solvent recovered, and a high grade bitumen product is formed. Exemplary systems comprise a mixbox, agglomerator, separator unit with optional countercurrent washer and deep cone settler, and TSRU. Processes are provided for fractionating a hydrocarbon fluid into heavier and lighter fractions. The lighter fraction may be used in solvent extraction of bitumen.

1 . A system for recovery of bitumen from oil sands comprising:
 a slurry system in which a bituminous feed is mixed with solvent to form an initial slurry;   an agglomerator for mixing the initial slurry and a water-containing fluid to agglomerate the solids from the initial slurry, producing an agglomerated slurry;   a separator unit for separating the agglomerated slurry into agglomerates and a low solids bitumen extract, said separator unit comprising a countercurrent washer for solvent washing of agglomerates with progressively cleaner solvent;   a tailings solvent recovery unit for removing solvent from washed agglomerates; and   a solvent recovery unit for separating solvent from the low solids bitumen extract.   
     
     
         2 . The system of  claim 1 , wherein the separator unit comprises a belt filter or a multi-stage counterflow cyclone for solvent washing agglomerates using progressively cleaner solvent. 
     
     
         3 . The system of  claim 2 , wherein the separator unit additionally comprises a gravity separator, cyclone, or screen, separating a low solids extract from the agglomerated slurry prior to solvent washing agglomerates. 
     
     
         4 . The system of  claim 1 , wherein the separator unit comprises:
 a primary solid-liquid separator for receiving and separating the agglomerated slurry, and
 a secondary solid-liquid separator for receiving underflow from the primary solid-liquid separator. 
   
     
     
         5 . The system of  claim 4 , wherein the primary solid-liquid separator acts as a surge bin to smooth operating fluctuations in the composition of the agglomerated slurry for the secondary solid-liquid separator. 
     
     
         6 . The system of  claim 4 , wherein the primary solid-liquid separator comprises a deep cone settler and the secondary solid-liquid separator comprises a filtration unit for receiving underflow from the deep cone settler for solvent washing of agglomerates. 
     
     
         7 . The system of  claim 6  wherein the filtration unit comprises a belt filter for countercurrent washing of agglomerates. 
     
     
         8 . The system of  claim 1 , additionally comprising:
 a rejects dryer for recovering solvent from oversized rejects of the initial slurry; and/or   an optional steam source for pre-conditioning feed entering the slurry system.   
     
     
         9 . The system of  claim 1 , wherein:
 the solvent recovery unit for separating solvent from the low solids bitumen extract comprises a distillation unit; and/or   the slurry system comprises a mixing unit in which the mixing of the initial slurry is effected.   
     
     
         10 . The system of  claim 9 , wherein:
 the slurry system comprises a mixing unit and the mixing unit comprises a mix box, a pump, or a combination thereof; and/or   the slurry flows by gravity from the mixing unit into the agglomerator.   
     
     
         11 . The system of  claim 1 , wherein:
 the agglomerator comprises one or more rotating drums in which the initial slurry is subjected to agitation, or one or more tanks through which the initial slurry is pumped; and/or   the agglomerator has an inlet thereon for receiving the water-containing fluid to promote agglomeration of fines therein.   
     
     
         12 . A system for recovery of bitumen from oil sands comprising:
 a mix box in which a bituminous feed is mixed with solvent to form an initial slurry;   an agglomerator for mixing the initial slurry with a water-containing fluid to agglomerate the solids from the initial slurry, producing an agglomerated slurry;   a screen to separate oversized rejects;   a rejects dryer for receiving rejects and recovering solvent therefrom;   a separator unit comprising a deep cone settler for separating agglomerates and a low solids bitumen extract from the agglomerated slurry, and a belt filter for receiving agglomerates from deep cone settler underflow and for solvent washing of agglomerates using countercurrent washing with progressively cleaner solvent;   a tailings solvent recovery unit for recovering solvent from washed agglomerates; and   a solvent recovery unit for separating solvent from the low solids bitumen extract.   
     
     
         13 . The system of  claim 12 , additionally comprising:
 a filtration unit for washing oversized rejects to recover bitumen; and/or   an inlet to the agglomerator for receiving water-containing fluids to promote the agglomeration of fines therein.   
     
     
         14 . A system for recovery of bitumen from oil sands comprising:
 a slurry system in which a bituminous feed is mixed with solvent and optionally a water-containing fluid to form an initial slurry;   one or more retention tank for receiving and agitating the initial slurry to agglomerate solids from the initial slurry to produce an agglomerated slurry;   a separator unit for separating agglomerates and a low solids bitumen extract from the agglomerated slurry, said separator unit comprising a deep cone settler for separating a low solids bitumen extract, and a belt filter receiving agglomerates as underflow from the deep cone settler for solvent washing of agglomerates using countercurrent washing with progressively cleaner solvent;   a tailings solvent recovery unit for removing solvent from washed agglomerates; and   a solvent recovery unit for separating solvent from the low solids bitumen extract.   
     
     
         15 . The system of  claim 14 , wherein agitating the initial slurry in the retention tank occurs without rotating the tank. 
     
     
         16 . The system of  claim 14 , additionally comprising:
 a conduit from the retention tank to the slurry system, for recirculating a portion of the agglomerated slurry; and/or   a pump for directing the portion of the agglomerated slurry from the retention tank back to the slurry system for recirculation.   
     
     
         17 . The system of  claim 14 , additionally comprising an inlet in the retention tank for including a water-containing stream to promote agglomeration of fines therein. 
     
     
         18 . A process for extracting bitumen from a bituminous feed from oil sands, comprising:
 fractionating a hydrocarbon fluid into a lighter fraction and a heavier fraction;   effecting solvent extraction of the bituminous feed with the lighter fraction as the solvent to produce solvent diluted bitumen; and   combining the heavier fraction with solvent diluted bitumen to form a high grade bitumen product.   
     
     
         19 . The process of  claim 18 , wherein the hydrocarbon fluid is a diluent, a natural gas condensate, naphtha, a C5+ natural gas condensate, or a mixture thereof. 
     
     
         20 . The process of  claim 18 , wherein the lighter fraction:
 has a boiling point of less than 100° C.;   comprises hydrocarbons with a boiling point less than 100° C., but greater than 50° C.;   comprises one or more C5 to C8 hydrocarbons; or   comprises a C4 or lighter hydrocarbon and fractionating is conducted under pressure and temperature conditions permitting the lighter fraction to remain liquid.   
     
     
         21 . The process of  claim 18 , wherein dilbit or diluent is combined with the high grade bitumen product to form a mixed product. 
     
     
         22 . The process of  claim 21 , wherein the dilbit is from a water-based bitumen extraction operation, a paraffinic froth treatment operation, or an in situ bitumen production operation. 
     
     
         23 . The process of  claim 22 , where the dilbit is from an in situ bitumen production operation, and the in situ operation is SAGD, SA-SAGD, LASER, or CSS. 
     
     
         24 . The process of  claim 21 , wherein the dilbit has less than 300 ppm filterable solids on a bitumen basis. 
     
     
         25 . The process of  claim 21 , wherein the mixed product is fungible, and/or the mixed product has less than 300 ppm filterable solids on a bitumen basis. 
     
     
         26 . The process of  claim 18 , wherein effecting solvent extraction comprises agglomerating solids, and/or wherein effecting solvent extraction comprises recycling the solvent. 
     
     
         27 . The process of  claim 18 , wherein fractionating comprises solvent removal by vaporizing and condensing the lighter fraction, flashing to create a pressure drop and vaporize the lighter fraction, or membrane separation based on solvent molecular size. 
     
     
         28 . The process of  claim 18 , wherein effecting solvent extraction comprises: 
       combining a first solvent and the bituminous feed 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 the high grade bitumen product; 
       wherein the first solvent or the second solvent comprises the lighter fraction. 
     
     
         29 . The process of  claim 28 , wherein the first solvent and the second solvent comprise the lighter fraction. 
     
     
         30 . The process of  claim 28 , wherein the first solvent and the second solvent comprises at least 50% by weight of the lighter fraction. 
     
     
         31 . The process of  claim 28 , wherein the first solvent and the second solvent comprises at least 90% by weight of the lighter fraction. 
     
     
         32 . The process of  claim 28 , wherein the first solvent and the second solvent are the same and comprise the lighter fraction.