Process and system for recovery of asphaltene by-product in paraffinic froth treatment operations
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.
1. A process for bitumen froth treatment comprising:
in a flow-through process,
directing the froth and a first paraffinic solvent as a first influent to a first stage froth treatment separator;
directing a first underflow from the first stage froth treatment separator as a second influent to a second stage froth treatment separator;
combining a first overflow from the first stage froth treatment separator and a second overflow from the second stage froth treatment separator as a third influent to a third stage froth treatment separator;
producing a second underflow from the second stage froth treatment separator as a waste tailings;
adding at least a second paraffinic solvent to at least one of the second influent or the third influent;
producing a third overflow from the third stage froth treatment separator as a diluted bitumen product; and
producing a third underflow from the third stage froth treatment separator as an asphaltene by-product, wherein
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 flows directly through to the third stage froth treatment separator to report as either the diluted bitumen product of the asphaltene by-product.
2. The process of claim 1 wherein the adding of the at least a second paraffinic solvent comprises adding the at least a second paraffinic solvent to the second influent.
3. The process of claim 1 wherein the adding of the at least a second paraffinic solvent comprises adding the at least a second paraffinic solvent to the third influent.
4. The process of claim 1 wherein the adding of at least the second paraffinic solvent comprises
adding the at least a second paraffinic solvent to the second influent and
adding the at least a second paraffinic solvent to the third influent.
5. The process of claim 1 wherein the adding of at least the second paraffinic solvent comprises
adding the at least a second paraffinic solvent to the second influent and
adding a third paraffinic solvent to the third influent.
6. The process 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.
7. The process of claim 1 wherein the adding of at least a second paraffinic solvent comprises:
adding the at least a second paraffinic solvent to the second influent; and 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 process of claim 1 wherein the adding of the at least a second paraffinic solvent comprises:
adding the at least a second paraffinic solvent to the third influent; and 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.
9. The process of claim 1 wherein the adding of at least the second paraffinic solvent comprises
adding the at least a second paraffinic solvent to the second influent and
adding the at least a second paraffinic solvent to the third influent; and
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.
10. The process of claim 1 wherein the adding of at least the second paraffinic solvent comprises:
adding the at least a second paraffinic solvent to the second influent;
adding a third paraffinic solvent to the third influent; and
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.
11. The process of claim 1 wherein the adding of the first paraffinic solvent to the first influent comprises adding the first paraffinic solvent so as to control a first addition S/B ratio in the first stage froth treatment separator for minimizing asphaltene precipitation in the first stage froth treatment separator.
12. The process of claim 11 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.
13. The process of claim 12 wherein the first paraffinic solvent is substantially pentane and the first addition S/B ratio is non-zero and up to about 0.9.
14. The process of claim 11 wherein the adding of the at least a second paraffinic solvent to the second influent or the third influent comprises controlling an amount of the at least a second paraffinic solvent to control the fraction of asphaltene reporting at the third underflow.
15. The process of claim 1 wherein the adding of the at least a second paraffinic solvent to the second influent or the third influent comprises controlling an amount of the at least a second paraffinic solvent to control the fraction of asphaltene reporting at the third underflow.
16. The process of claim 15 wherein the adding of the at least a second paraffinic solvent to the second influent or the third influent comprises adding the at least a second paraffinic solvent to the second influent.
17. The process of claim 15 wherein the adding of the at least a second paraffinic solvent to the second influent or the third influent comprises adding the at least a second paraffinic solvent to the third influent.
18. The process of claim 15 wherein the adding of the at least a second paraffinic solvent to the second influent or the third influent comprises adding the at least a second paraffinic solvent to the second influent and adding the at least a second paraffinic solvent to the third influent.
19. The process of claim 1 wherein the first stage froth treatment separator, the second stage froth treatment separator and the third stage froth treatment separator are settlers.
20. The process of claim 1 wherein the first stage froth treatment separator is selected from the group of separators consisting of settlers, centrifuges and hydrocyclones.
21. The process of claim 1 wherein the first stage froth treatment separator, the second stage froth treatment separator and the third stage froth treatment separator are selected from the group consisting of settlers, centrifuges and hydrocyclones.