Process For Recovering Solvent From Ashphaltene Containing Tailings Resulting From A Separation Process

Abstract

A process for recovering paraffinic solvent from tailings produced in the treatment of bitumen froth comprising introducing the tailings into a tailings solvent recovery unit (TSRU), the TSRU having internals, and distributing the tailings over the internals. An inert gas or steam is then introduced below the internals and above the liquid pool for enhancing the vaporization of the contained solvent. Solvent is vaporized from asphaltene agglomerates. In one embodiment, the process is affected in the absence of mechanical means used to substantially break up asphaltene agglomerates or to prevent the agglomeration of asphaltene. In another aspect, the process comprises introducing the tailings into a first TSRU as described above and then into a second TSRU operated at a lower pressure. In another aspect, internals are optionally present and steam or inert gas is injected in the liquid pool.

1 . A process for recovering paraffinic solvent from froth treatment tailings produced in the treatment of bitumen froth comprising:
 introducing the froth treatment tailings into a tailings solvent recovery unit (TSRU), the TSRU having internals, and distributing the froth treatment tailings over the internals to increase the surface area of the froth treatment tailings;   introducing inert gas or steam below the internals so that it flows counter currently to the froth treatment tailings and heats the froth treatment tailings to vaporize at least a portion of the paraffinic solvent; and   removing the vaporized solvent from the TSRU;   wherein:
 the froth treatment tailings contain asphaltenes; and 
 the at least a portion of the solvent is vaporized from asphaltene agglomerates. 
   
     
     
         2 . The process of  claim 1 , wherein the process is affected in the absence of mechanical means used to substantially break up asphaltene agglomerates or to prevent the agglomeration of asphaltene. 
     
     
         3 . The process of  claim 1 , wherein the TSRU has an absolute pressure of about 100 and about 200 kPa. 
     
     
         4 . The process of  claim 1 , wherein the internals comprise a plurality of interior, vertically spaced shed decks. 
     
     
         5 . The process of  claim 1 , wherein the internals are coated with an asphaltene fouling resistant coating to mitigate fouling or plugging in the TSRU. 
     
     
         6 . The process of  claim 1 , wherein the froth treatment tailings contain at least 1.0 wt % asphaltenes. 
     
     
         7 . The process of  claim 1 , wherein the froth treatment tailings contain at least 5.0 wt % asphaltenes. 
     
     
         8 . The process of  claim 1 , wherein the inert gas or steam introduced below the internals is introduced above a liquid level that forms in the bottom of the TSRU. 
     
     
         9 . The process of  claim 1 , wherein the paraffinic solvent is a C 4  to C 6  paraffinic hydrocarbon solvent. 
     
     
         10 . The process of  claim 1 , wherein the paraffinic solvent is pentane, iso-pentane, or a combination thereof. 
     
     
         11 . The process of  claim 1 , wherein the temperature of the TSRU is about 75 to about 100° C. 
     
     
         12 . The process of  claim 1 , wherein the TSRU has an absolute pressure of about 120 to about 170 kPa. 
     
     
         13 . The process of  claim 1 , wherein the inert gas is nitrogen, methane, carbon dioxide, argon, steam or any other inert gas that is not reactive under process conditions. 
     
     
         14 . The process of  claim 1 , wherein the inert gas or steam to froth treatment tailings mass ratio is about 1:1 to about 10:1. 
     
     
         15 . The process of  claim 1 , further comprising feeding tailings from the TSRU into a second TSRU maintained at an absolute pressure that is lower than the pressure of the TSRU recited in  claim 1 , the second TSRU having internals, and distributing the tailings from the TSRU over the internals to increase the surface area of the tailings from the TSRU; introducing inert gas or steam below the internals of the second TSRU so that it flows counter currently to the tailings from the TSRU and heats the tailings from the TSRU to vaporize at least a portion of the paraffinic solvent; and removing the vaporized solvent from the second TSRU. 
     
     
         16 . The process of  claim 15 , wherein the second TSRU has an absolute pressure of about 20 to about 200 kPa. 
     
     
         17 . A process for recovering paraffinic solvent from froth treatment tailings produced in the treatment of bitumen froth comprising:
 introducing the froth treatment tailings into a first tailings solvent recovery unit (TSRU), the first TSRU having internals;   distributing the froth treatment tailings over the internals to increase the surface area of the froth treatment tailings;   introducing inert gas or steam below the internals so that it flows counter currently to the froth   
       treatment tailings and heats the froth treatment tailings to vaporize at least a portion of the paraffinic solvent;
 removing the vaporized solvent from the first TSRU; 
 feeding tailings from the first TSRU into a second TSRU maintained at an absolute pressure that is lower than the pressure of the first TSRU, the second TSRU having internals; 
 distributing the tailings from the first TSRU over the internals of the second TSRU to increase the surface area of the tailings from the first TSRU; 
 introducing inert gas or steam below the internals of the second TSRU so that it flows counter currently to the tailings from the first TSRU and heats the tailings from the first TSRU to vaporize at least a portion of the paraffinic solvent; and 
 removing the vaporized solvent from the second TSRU. 
 
     
     
         18 . The process of any one of  claims 22  to  25 , wherein the froth treatment tailings contain asphaltenes; wherein the at least a portion of the solvent is vaporized from asphaltene agglomerates; and wherein the process is effected in the absence of mechanical means used to substantially break up asphaltene agglomerates or to prevent the agglomeration of asphaltene. 
     
     
         19 . A process for recovering paraffinic solvent from froth treatment tailings produced in the treatment of bitumen froth comprising:
 introducing the froth treatment tailings into a tailings solvent recovery unit (TSRU);   introducing inert gas or steam into a liquid pool formed in the bottom of the TSRU to vaporize at least a portion of the paraffinic solvent; and   removing the vaporized solvent from the TSRU;   wherein:   the froth treatment tailings contain asphaltenes; and   the at least a portion of the solvent is vaporized from asphaltene agglomerates.   
     
     
         20 . The process of  claim 19 , wherein the TSRU is substantially free of internals. 
     
     
         21 . The process of  claim 19 , wherein the process is effected in the absence of mechanical means used to substantially break up asphaltene agglomerates or to prevent the agglomeration of asphaltene. 
     
     
         22 . The process of  claim 19 , wherein the froth treatment tailings contain at least 1.0 wt % asphaltenes. 
     
     
         23 . The process of  claim 19 , wherein the froth treatment tailings contain at least 5.0 wt % asphaltenes. 
     
     
         24 . The process of  claim 19 , wherein the TSRU has an absolute pressure of about 20 and about 200 kPa. 
     
     
         25 . The process of  claim 19 , wherein the paraffinic solvent is a C 4  to C 6  paraffinic hydrocarbon solvent. 
     
     
         26 . The process of  claim 19 , wherein the paraffinic solvent is pentane, iso-pentane, or a combination thereof. 
     
     
         27 . The process of  claim 19 , wherein the temperature of the TSRU is about 75 to about 100° C. 
     
     
         28 . The process of  claim 19 , further comprising feeding tailings from the TSRU into a second TSRU maintained at an absolute pressure that is lower than the pressure of the TSRU recited in  claim 19 .