Water stripping and catalyst/liquid product separation system

• US 6,720,358 B2
• Filed: 12/28/2001
• Issued: 04/13/2004
• Est. Priority Date: 12/28/2001
• Status: Expired due to Fees

• Current Assignee: Conocophillips Company (ConocoPhillips)
• Original Assignee: Conocophillips Company (ConocoPhillips)
• Inventors: Mohedas, Sergio, Espinoza, Rafael L., Melquist, Vincent
• Primary Examiner(s): Parsa, J.
• Application Number:
  US10/034,452
• Publication Number:
  US 20030125396A1
• Time in Patent Office: 837 Days
• Field of Search: 518/700, 518/706, 518/728
• US Class Current: 518/700
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 53/002 by condensation
• CPC Class Codes: B01J 8/005 Separating solid material from the gas/liquid stream separation processes per se B01D
• CPC Class Codes: B01J 8/006 by filtration
• CPC Class Codes: B01J 8/228 externally, i.e. the particles leaving the vessel and subsequently re-entering it
• CPC Class Codes: C10G 2/342 with moving solid catalysts

Abstract

The present invention relates to a method and system for water removal and optionally liquid product separation in slurry reactors operating at Fischer-Tropsch conditions. More particularly, the present invention includes a water stripping system that allows the reaction water to the stripped in an external vessel, with a relatively high rate of catalyst and wax circulation. In a preferred embodiment of the present invention, a method for removing water from a slurry reactor containing a water-rich slurry includes removing a portion of water-rich slurry from the slurry reactor, stripping water from the water-rich slurry using a dry gas to form a water-reduced slurry and a water-rich gas stream, and returning the water-reduced slurry back to the reactor.

Claims

1. A method for operating a Fischer-Tropsch reactor, comprising:

a) contacting a synthesis gas comprising a mixture of hydrogen and carbon monoxide with a hydrocarbon synthesis catalyst in a slurry body comprising the catalyst and gas bubbles in a hydrocarbon slurry liquid, under reaction conditions effective to form hydrocarbons and secondary products including water from the synthesis gas, at least a portion of which are liquid at the reaction conditions, thereby forming a catalyst-containing water-rich slurry;

b) passing the catalyst-containing water-rich slurry into a stripping zone, wherein the catalyst-containing water-rich slurry is contacted with a stripping gas that at least partially removes water therefrom so as to form a water-reduced slurry; and

c) passing at least a portion of the water-reduced slurry back into the slurry body.

2. The method according to claim 1, further including the step allowing catalyst particles to settle out of the water-reduced slurry, so as to form a catalyst-containing water-reduced slurry and a catalyst-reduced water-reduced liquid between step (a) and step (c).

3. The method according to claim 2, further including the step of passing the catalyst-containing water-rich slurry through a degasser between step (a) and step (c).

7. The method according to claim 2, wherein said stripping zone includes a quiescent zone in which the catalyst particles settle out of the water-reduced slurry.

8. The method according to claim 7, therein said quiescent zone is sized to allow a desired degree of settling.

9. The method according to claim 2, wherein the water-reduced slurry of step (c) comprises the catalyst-containing water-reduced slurry.

10. The method according to claim 2, wherein said stripping zone further includes a collection area in which said catalyst particles settle and collect.

11. The method according to claim 1, wherein step b) further produces a water-rich gas stream, and wherein said water-rich gas stream is separated in a separation zone to form a dry gas phase and a water phase.

12. The method according to claim 11, wherein the separation zone employs condensation.

13. The method according to claim 11, further comprising returning at least a portion of the dry gas phase to the stripping zone.

14. The method according to claim 1, wherein at least 60% of the water in the catalyst-containing water-rich slurry is removed.

15. The method according to claim 1, wherein at least 80% of the water in the catalyst-containing water-rich slurry is removed.

16. The method according to claim 1, wherein the stripping gas comprises at least one of hydrogen, methane, nitrogen and carbon.

17. The method according to claim 16, wherein the stripping gas further comprises at least one of carbon monoxide, carbon dioxide and light hydrocarbons.

18. The method according to claim 1, wherein the stripping gas comprises a hydrogen-rich stream.

4. A method for producing hydrocarbons from synthesis gas, comprising:

a) contacting the synthesis gas with a hydrocarbon synthesis catalyst in a slurry body comprising the catalyst and gas bubbles in a hydrocarbon slurry liquid, under reaction conditions effective to form hydrocarbons and secondary products including water from the synthesis gas, at least a portion of which are liquid at the reaction conditions, thereby forming a catalyst-containing water-rich slurry;

b) passing the catalyst-containing water-rich slurry into a stripping zone, wherein the catalyst-containing water-rich slurry is contacted with a stripping gas that at least partially removes water therefrom so as to form a water-reduced slurry; and

c) passing at least a portion of the water-reduced starry back into the slurry body.

5. The method according to claim 4, further including the step of allowing catalyst panties to settle out of the water-reduced slurry, so as to form a catalyst-containing water-reduced slurry and a catalyst-reduced water-reduced liquid between step (a) and step (c).

6. The method according to claim 5 wherein step (b) is accomplished by injecting the stripping gas into the bottom of the catalyst-containing water-rich slurry and said settling occurs in a quiescent zone that is essentially free of injected gas bubbles.

19. The method according to claim 5, wherein said stripping zone includes a quiescent zone in which the catalyst particles settle out of the water-reduced slurry.

20. The method according to claim 19, wherein said quiescent zone is sized to allow a desired degree of settling.

21. The method according to claim 5, wherein the water-reduced slurry of step (c) comprises the catalyst-containing water-reduced slurry.

22. The method according to claim 5, wherein said stripping zone further includes a collection area in which said catalyst particles settle and collect.

23. The method according to claim 4, wherein step b) further produces a water-rich gas stream, and wherein said water-rich gas stream is separated in a separation zone to form a dry gas phase and a water phase.

24. The method according to claim 23, wherein the separation zone employs condensation.

25. The method according to claim 23, further comprising returning at least a portion of the dry gas phase to the stripping zone.

26. The method according to claim 4, wherein at least 60% of the water in the catalyst-containing water-rich slurry is removed.

27. The method according to claim 4, wherein at least 80% of the water in the catalyst-containing water-rich slurry is removed.

28. The method according to claim 4, wherein the stripping gas comprises at least one of hydrogen, methane, nitrogen and carbon.

29. The method according to claim 28, wherein the stripping gas further comprises at least one of carbon monoxide, carbon dioxide and light hydrocarbons.

30. The method according to claim 4, wherein the stripping gas comprises a hydrogen-rich stream.