Process and system for recovery of asphaltene by-product in paraffinic froth treatment operations

Abstract

A process for treating bitumen froth with paraffinic solvent is provided which uses three stages of separation. Froth and a first solvent are directed to a first stage at a solvent/bitumen ratio for precipitating few or substantially no asphaltenes. A first stage underflow is directed to a second stage and a first stage overflow is directed to a third stage. A second stage underflow is directed to waste tailings and the second stage overflow joins the first stage overflow. A third stage underflow is recovered as an asphaltene by-product and a third stage overflow is recovered as a diluted bitumen product. At least a second solvent is added to one or both of the second or third stages for controlling a fraction of asphaltenes in the third stage underflow. Asphaltene loss to waste tailings is minimized and asphaltenes are now recovered as asphaltene by-product.

The embodiments of the invention for which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . A system for treating bitumen froth with paraffinic solvent comprising:
 in a flow-through process,   a first stage froth treatment separator for receiving the froth and a paraffinic first solvent;   a second stage froth treatment separator for receiving, as a second stage influent, at least a first underflow from the first stage separator and producing a waste tailings from a second stage underflow; and   a third stage froth treatment separator for receiving a third stage influent of at least a first overflow from the first stage froth treatment separator and a second overflow from the second stage froth treatment separator, wherein
 at least a second paraffinic solvent is combined with at least one of the second stage influent or the third stage influent, 
 the third stage froth treatment separator produces a diluted bitumen product from a third stage overflow and produces an asphaltene by-product from a third stage underflow; 
 the first underflow flows through to the second stage froth treatment separator to report as either the second overflow or the waste tailings, 
 the first overflow flows through to the third stage froth treatment separator to report as either the diluted bitumen product or the asphaltene by-product; and 
 the second overflow directly flows through to the third stage froth treatment separator to report as either the diluted bitumen product or the asphaltene by-product. 
   
     
     
         2 . The system of  claim 1 , wherein the second stage influent comprises the at least a second paraffinic solvent. 
     
     
         3 . The system of  claim 1 , wherein the third stage influent comprises the at least a second paraffinic solvent. 
     
     
         4 . The system of  claim 1 , wherein the second stage influent and the third stage influent each comprises the at least a second paraffinic solvent. 
     
     
         5 . The system of  claim 1 , wherein the second stage influent comprises the at least a second paraffinic solvent and the third stage influent comprises a third paraffinic solvent. 
     
     
         6 . The system of  claim 5 , wherein the first paraffinic solvent, the at least a second paraffinic solvent and the third paraffinic solvent are substantially pentane and wherein an overall solvent/bitumen ratio is about 1.25 or higher. 
     
     
         7 . The system of  claim 1 , wherein the first paraffinic solvent and the at least a second paraffinic solvent are substantially pentane and wherein an overall solvent/bitumen ratio is about 1.25 or higher. 
     
     
         8 . The system of  claim 1 , wherein the first paraffinic solvent is added to the first stage froth treatment separator in a first addition S/B ratio for minimizing asphaltene precipitation in the first stage froth treatment separator. 
     
     
         9 . The system of  claim 8 , wherein the first addition S/B ratio is controlled between an S/B ratio below an asphaltene precipitation threshold and an S/B ratio up to about the asphaltene precipitation threshold. 
     
     
         10 . The system of  claim 9 , wherein the first paraffinic solvent is substantially pentane and the first addition S/B ratio is non-zero and up to about 0.9. 
     
     
         11 . The system of  claim 8 , wherein the at least a second paraffinic solvent being added to the second stage froth treatment separator or the third stage froth separator is controlled in order to control the fraction of asphaltene reporting at the third underflow. 
     
     
         12 . The system of  claim 1 , wherein the at least a second paraffinic solvent being added to the second stage froth treatment separator or the third stage froth separator is controlled in order to control the fraction of asphaltene reporting at the third underflow. 
     
     
         13 . The system of  claim 1 , wherein the first stage separator, the second stage separator and the third stage separator are settlers. 
     
     
         14 . The system of  claim 1 , wherein the first stage separator is selected from the group of separators consisting of settlers, centrifuges and hydrocyclones. 
     
     
         15 . The system of  claim 1 , wherein the first stage separator, the second stage separator and the third stage separator are selected from the group consisting of settlers, centrifuges and hydrocyclones. 
     
     
         16 . The system of  claim 1 , wherein the waste tailings is substantially free of precipitated asphaltenes. 
     
     
         17 . The system of  claim 1 , wherein at least the first stage and second stage froth treatment separators are arranged in series.