Bitumen extraction and asphaltene removal from heavy crude using high shear

Abstract

Herein disclosed is a method of removing at least one component from a feed by subjecting the feed to high shear in the presence of carbon dioxide to produce a high shear-treated product and separating the at least one component from the high shear-treated product to produce a component-reduced product. Also disclosed is a method of removing asphaltenes from asphaltenic oil by subjecting the asphaltenic oil to a shear rate of at least 10,000 s −1 in the presence of carbon dioxide to produce a high shear-treated product and separating asphaltenes from the high shear-treated product to produce an asphaltene-reduced product oil. Systems are also provided for carrying out the methods.

1 . A method of removing at least one component from a feed comprising tailings, asphaltenic oil or a combination thereof, the method comprising:
 subjecting the feed to high shear in the presence of carbon dioxide to produce a high shear-treated product; and   separating the at least one component from the high shear-treated product to produce a component-reduced product.   
     
     
         2 . The method of  claim 1  wherein subjecting the feed to high shear in the presence of carbon dioxide further comprises subjecting the feed to a shear rate of at least 10,000 s −1 . 
     
     
         3 . The method of  claim 2  wherein subjecting the feed to high shear in the presence of carbon dioxide comprises a shear rate of at least 20,000 s −1 . 
     
     
         4 . The method of  claim 1  wherein subjecting the feed to high shear comprises introducing the feed and carbon dioxide into a high shear device comprising at least one rotor and at least one complementarily-shaped stator. 
     
     
         5 . The method of  claim 4  wherein high shear comprises a shear rate of at least 10,000 s −1 , wherein the shear rate is defined as the tip speed divided by the shear gap, and wherein the tip speed is defined as πDn, where D is the diameter of the at least one rotor and n is the frequency of revolution. 
     
     
         6 . The method of  claim 5  wherein high shear comprises a shear rate of at least 20,000 s −1 . 
     
     
         7 . The method of  claim 5  wherein subjecting the feed to a shear rate of at least 10,000 s −1  produces a local pressure of at least about 1034.2 MPa (150,000 psi) at a tip of the at least one rotor. 
     
     
         8 . The method of  claim 4  wherein subjecting the feed to high shear comprises providing a tip speed of the at least one rotor of at least about 23 m/sec, wherein the tip speed is defined as πDn, where D is the diameter of the at least one rotor and n is the frequency of revolution. 
     
     
         9 . The method of  claim 1  wherein the high shear-treated product comprises a dispersion of carbon dioxide bubbles. 
     
     
         10 . The method of  claim 9  wherein the carbon dioxide bubbles have an average bubble diameter of less than about 1 micron. 
     
     
         11 . The method of  claim 10  wherein the carbon dioxide bubbles have an average bubble diameter of less than about 0.5 micron. 
     
     
         12 . The method of  claim 1  wherein the feed comprises tailings from a caustic bitumen extraction process and the component-reduced product comprises water having less than 10 wt % impurities. 
     
     
         13 . The method of  claim 12  further comprising recycling at least a portion of the water to the bitumen extraction process. 
     
     
         14 . The method of  claim 12  wherein separating the at least one component comprises separating solids from the high shear-treated product to produce a solids-reduced product and separating an oil phase from the solids-reduced product to produce the component-reduced product, wherein the component-reduced product comprises water. 
     
     
         15 . The method of  claim 12  wherein the tailings are obtained from a tailings pond of a bitumen extraction process. 
     
     
         16 . The method of  claim 12  wherein at least a portion of the tailings are produced by:
 mixing tar sand and water in a tumbler or a hydrotransport line to form a froth; 
 introducing the froth into a separation cell; and 
 removing the at least a portion of the tailings from the separation cell. 
 
     
     
         17 . The method of  claim 12  wherein at least a portion of the tailings are produced by introducing a middlings portion from a separation cell of a bitumen extraction process into a secondary separation unit and extracting the at least a portion of the tailings from the secondary separation cell. 
     
     
         18 . The method of  claim 12  wherein at least a portion of the tailings are produced by introducing a bitumen froth from a separation cell of a bitumen extraction process into one or more centrifuge and extracting the at least a portion of the tailings from the one or more centrifuge. 
     
     
         19 . The method of  claim 12  wherein subjecting the feed comprising tailings to high shear in the presence of carbon dioxide reduces the pH to less than about 6. 
     
     
         20 . The method of  claim 19  wherein subjecting the feed to high shear converts the caustic in the tailings to sodium bicarbonate, enhancing the rate of separation of water from the tailings relative to conventional tailings treatment processes. 
     
     
         21 . The method of  claim 1  wherein the feed comprises asphaltenic oil, the at least one product comprises asphaltenes and the component-reduced product comprises asphaltene-reduced oil. 
     
     
         22 . The method of  claim 21  wherein the asphaltenic oil is selected from the group consisting of bitumen comprising at least some percentage of asphaltenes, heavy crude oil comprising at least some percentage of asphaltenes, and combinations thereof. 
     
     
         23 . The method of  claim 21  wherein separating the at least one component from the high shear-treated product to produce a component-reduced product comprises introducing the high shear-treated product into a centrifuge operated to separate asphaltenes from asphaltene-reduced product oil. 
     
     
         24 . The method of  claim 21  wherein the asphaltenic oil feed is subjected to high shear in the presence of water. 
     
     
         25 . The method of  claim 21  wherein the feed has an API gravity of less than about 10 and the asphaltene-reduced product oil has an API gravity of greater than about 10. 
     
     
         26 . The method of  claim 21  wherein the asphaltene-reduced product oil comprises at least about 90 wt % bitumen. 
     
     
         27 . The method of  claim 21  wherein the asphaltene-reduced product oil comprises less than about 10 wt % asphaltenes. 
     
     
         28 . The method of  claim 21  wherein the asphaltene-reduced product oil comprises less than about 5 wt % water, less than about 1 wt % solids, or both. 
     
     
         29 . A method of removing asphaltenes from asphaltenic oil, the method comprising:
 subjecting the asphaltenic oil to a shear rate of at least 10,000 s −1  in the presence of carbon dioxide to produce a high shear-treated product; and   separating asphaltenes from the high shear-treated product to produce an asphaltene-reduced product oil.   
     
     
         30 . The method of  claim 29  wherein the asphaltenic oil is selected from bitumen and heavy crude oils. 
     
     
         31 . The method of  claim 29  further comprising separating carbon dioxide from the high shear-treated product and recycling the separated carbon dioxide to the subjecting step. 
     
     
         32 . The method of  claim 29  wherein the asphaltene-reduced oil product comprises less than about 10 wt % asphaltenes. 
     
     
         33 . In an aqueous bitumen extraction process comprising forming a bitumen froth by tumbling tar sand with water and base in a tumbler or hydrotransporting tar sand with water and base in a transport pipeline; and separating the bitumen froth from tailings in a separation cell; the improvement comprising:
 subjecting the tailings to high shear in the presence of carbon dioxide to produce a high shear-treated product;   separating solids from the high shear treated product to produce a solids-reduce product;   separating water from the solids-reduced product; and   recycling the water to the froth forming step.   
     
     
         34 . The method of  claim 33  wherein the water comprises less than about 10, 5, 3, or 1 wt % impurities. 
     
     
         35 . The method of  claim 33  wherein separating solids from the high shear treated product to produce a solids-reduce product is performed with at least one centrifuge. 
     
     
         36 . The method of  claim 33  wherein separating water from the solids-reduced product is performed with at least one settling tank. 
     
     
         37 . The method of  claim 36  wherein an oil phase is removed from an upper portion of the settling tank and the water from a lower portion of the settling tank. 
     
     
         38 . The method of  claim 33  wherein subjecting the tailings to high shear in the presence of carbon dioxide produces a high shear-treated product having a pH of less than about 6. 
     
     
         39 . A system for removing at least one component from a feed comprising tailings, asphaltenic oil or a combination thereof, the system comprising:
 at least one high shear device comprising at least one rotor and at least one complementarily-shaped stator and configured to subject the feed to high shear in the presence of carbon dioxide and produce a high shear-treated product, wherein the at least one high shear device is configured to subject the contents therein to a shear rate of at least 10,000 s −1 , wherein the shear rate is defined as the tip speed divided by the shear gap, and wherein the tip speed is defined as πDn, where D is the diameter of the at least one rotor and n is the frequency of revolution; and   at least one separation unit configured to separate a component from the high shear-treated product, providing a component-reduced product.   
     
     
         40 . The system of  claim 39  wherein the at least one rotor is configured to provide a tip speed of at least about 23 m/sec. 
     
     
         41 . The system of  claim 39  wherein the at least one rotor is configured to provide a tip speed of at least about 40 m/sec. 
     
     
         42 . The system of  claim 39  wherein the at least one rotor is separated from the at least one stator by a shear gap of less than about 5 μm, wherein the shear gap is the minimum distance between the at least one rotor and the at least one stator. 
     
     
         43 . The system of  claim 39  wherein the feed comprises tailings from a bitumen extraction process, wherein the at least one component comprises solids and oil and wherein the system comprises a first separation unit configured to separate solids from the high shear-treated product producing a solids-reduced product and a second separation unit configured to separate oil from the solids-reduced product providing substantially pure water as component-reduced product. 
     
     
         44 . The system of  claim 43  further comprising a tailings pond from which the feed is obtained. 
     
     
         45 . The system of  claim 43  wherein the first separation unit is a centrifuge and the second separation unit is a settling tank. 
     
     
         46 . The system of  claim 39  wherein the feed comprises asphaltenic oil, wherein the at least one component comprises asphaltenes, and wherein the component-reduced product comprises asphaltene-reduced oil. 
     
     
         47 . The system of  claim 46  wherein the feed has an API gravity of less than 10 and wherein the asphaltene-reduced product has an API gravity of greater than 10. 
     
     
         48 . The system of  claim 46  wherein the asphaltene-reduced oil comprises less than about 10 wt % asphaltenes. 
     
     
         49 . The system of  claim 48  wherein the asphaltene-reduced oil further comprises less than about 5 wt % solids, less than 5 wt % water or both.