Desalination using positively buoyant or negatively buoyant/assisted buoyancy hydrate

• US 20030024803A1
• Filed: 10/08/2002
• Published: 02/06/2003
• Est. Priority Date: 07/12/1999
• Status: Active Grant

• Current Assignee: Marine Desalination Systems LLC
• Original Assignee: Marine Desalination Systems LLC
• Inventors: Max, Michael David
• Granted Patent: US 6,733,667 B2
• Time in Patent Office: Days
• US Class Current: 203/10
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: C02F 1/20 by degassing, i.e. liberation of dissolved gases degasification of liquids in general B01D19/00; arrangement of degassing apparatus in boiler feed supply F22D
• CPC Class Codes: C02F 1/22 by freezing
• CPC Class Codes: C02F 1/26 by extraction
• CPC Class Codes: C02F 1/265 Desalination
• CPC Class Codes: C02F 1/5236 using inorganic agents
• CPC Class Codes: C02F 2103/08 Seawater, e.g. for desalination
• CPC Class Codes: C02F 2103/18 from the purification of gaseous effluents
• CPC Class Codes: Y02A 20/124 Water desalination
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y10S 203/11 Batch distillation

Abstract

Methods and apparatus for desalination of salt water (and purification of polluted water) are disclosed. Saline (or otherwise polluted) water is pumped to a desalination installation and down to the base of a desalination fractionation column, where it is mixed with hydrate-forming gas or liquid to form either positively buoyant (also assisted buoyancy) or negatively buoyant hydrate. The hydrate rises or sinks or is carried into a lower pressure area and dissociates (melts) into the gas and pure water. In preferred embodiments, residual salt water which is heated by heat given off during formation of the hydrate is removed from the system to create a bias towards overall cooling as the hydrate dissociates endothermically at shallower depths, and input water is passed through regions of dissociation in heat-exchanging relationship therewith so as to be cooled sufficiently for hydrate to form at pressure-depth. The fresh water produced by the system is cold enough that it can be used to provide refrigeration, air conditioning, or other cooling; heat removed from the system with the heated residual water can be used for heating or other applications. In other embodiments, desalination or other purification is carried out in “artificially” or mechanically pressurized vessels, which embodiments may be comparatively mobile.

Claims

1. A method of desalinating or purifying saline or polluted input water, respectively, said method comprising:

providing said input water to a hydrate formation region of a desalination fractionation installation that is located inland and causing said input water to be mixed with a hydrate-forming substance under pressure conditions and temperature conditions conducive to formation of hydrate such that hydrate spontaneously forms;

providing said hydrate to a hydrate dissociation region of said installation;

removing heat from said desalination fractionation installation by removing residual saline or polluted water that has been warmed by heat of endothermic formation of said hydrate;

allowing said hydrate to dissociate into fresh water and the hydrate-forming substance in a dissociation region of said desalination fractionation installation; and

collecting said fresh water;

said method further comprising at least partially cooling said input water toward said temperature conditions conducive to formation of hydrate before said input water is mixed with said hydrate-forming substance.

2. The method of claim 1, wherein the input water is at least partially cooled toward said temperature conditions conducive to formation of hydrate by being passed through said dissociation region in heat exchanging relationship with said hydrate, whereby heat is absorbed from said input water by said hydrate as said hydrate dissociates endothermically.

3. The method of claim 1, wherein said hydrate-forming substance produces positively buoyant hydrate and wherein said hydrate is provided to said hydrate dissociation region by being permitted to rise into said hydrate dissociation region.

4. The method of claim 1, wherein said hydrate-forming substance is less dense than said input water and produces hydrate which, per se, is negatively buoyant;

said hydrate-forming substance is mixed with said input water in a manner such that hydrate formation is incomplete and traps pockets of said hydrate-forming substance within a shell or meshwork of said hydrate to produce assisted buoyancy hydrate masses; and

said hydrate is provided to said hydrate dissociation region by virtue of said assisted buoyancy hydrate masses being permitted to rise into said hydrate dissociation region.

5. The method of claim 4, further comprising diverting said assisted buoyancy hydrate masses laterally as they rise into said hydrate dissociation region such that as said assisted buoyancy hydrate masses dissociate, negatively buoyant hydrate which sinks settles within said hydrate dissociation region, thereby substantially minimizing the amount of negatively buoyant hydrate which settles within said hydrate formation region of said desalination fractionation installation.

6. The method of claim 1, wherein said hydrate-forming substance comprises a gas or gas mixture.

7. The method of claim 6, wherein said gas or gas mixture produces positively buoyant hydrate.

8. The method of claim 6, wherein said gas or gas mixture produces hydrate which, per se, is negatively buoyant;

and wherein said gas or gas mixture is mixed with said input water in a manner such that hydrate formation is incomplete and traps pockets of said gas or gas mixture within a shell or meshwork of said hydrate to produce assisted buoyancy hydrate masses.

9. The method of claim 1, wherein said hydrate-forming substance comprises a liquid.

10. The method of claim 1, wherein said hydrate-forming substance comprises gaseous or liquid carbon dioxide.

11. The method of claim 1, further comprising rinsing said hydrate of residual fluid before said hydrate dissociates.

12. The method of claim 1, wherein said residual saline or polluted water that has been warmed by heat of endothermic formation of said hydrate is removed via a screened water trap.

13. The method of claim 1, wherein said residual saline or polluted water that has been warmed by heat of endothermic formation of said hydrate is removed centrifugally.

14. The method of claim 1, further comprising controlling provision of said hydrate to said hydrate dissociation region of said installation such that said hydrate dissociates while remaining under elevated pressure substantially greater than atmospheric pressure.

15. The method of claim 14, further comprising capturing said hydrate-forming substance while said hydrate-forming substance is under said elevated pressure and recycling said hydrate-forming substance for re-use while maintained substantially at said elevated pressure.

16. The method of claim 1, wherein said hydrate formation region is located at or near the bottom of a fractionation column that is long enough for the weight of a column of water within said fractionation column to generate said pressure conditions conducive to the formation of hydrate, said method comprising pumping said input water and said hydrate-forming substance down to said hydrate formation region.

17. The method of claim 1, comprising mechanically pressurizing said hydrate formation region to generate said pressure conditions conducive to formation of hydrate.

18. The method of claim 17, further comprising mechanically pressurizing said hydrate dissociation region.

19. The method of claim 18, wherein provision of said hydrate to said hydrate dissociation region is controlled by controlling relative pressure within said hydrate formation region and said hydrate dissociation region.

32. Water produced according to the method of claim 1 using seawater as said input water.

33. Water produced according to the method of claim 2 using seawater as said input water.

34. Water produced according to the method of claim 3 using seawater as said input water.

35. Water produced according to the method of claim 4 using seawater as said input water.

36. Water produced according to the method of claim 5 using seawater as said input water.

37. Water produced according to the method of claim 6 using seawater as said input water.

38. Water produced according to the method of claim 7 using seawater as said input water.

39. Water produced according to the method of claim 8 using seawater as said input water.

40. Water produced according to the method of claim 9 using seawater as said input water.

41. Water produced according to the method of claim 10 using seawater as said input water.

42. Water produced according to the method of claim 11 using seawater as said input water.

43. Water produced according to the method of claim 12 using seawater as said input water.

44. Water produced according to the method of claim 13 using seawater as said input water.

45. Water produced according to the method of claim 14 using seawater as said input water.

46. Water produced according to the method of claim 15 using seawater as said input water.

47. Water produced according to the method of claim 16 using seawater as said input water.

48. Water produced according to the method of claim 17 using seawater as said input water.

49. Water produced according to the method of claim 18 using seawater as said input water.

50. Water produced according to the method of claim 19 using seawater as said input water.

20. A method of desalinating or purifying saline or polluted input water, respectively, said method comprising:

providing said input water to a hydrate formation region of a desalination fractionation installation and causing said input water to be mixed with a liquid hydrate-forming substance under pressure conditions and temperature conditions conducive to formation of hydrate such that hydrate spontaneously forms;

providing said hydrate to a hydrate dissociation region of said installation;

allowing said hydrate to dissociate into fresh water and the hydrate-forming substance in a dissociation region of said desalination fractionation installation; and

collecting said fresh water.

21. The method of claim 20, further comprising removing heat from said desalination fractionation installation by removing residual saline or polluted water that has been warmed by heat of endothermic formation of said hydrate.

22. The method of claim 21, further comprising at least partially cooling said input water toward said temperature conditions conducive to formation of hydrate before said input water is mixed with said hydrate-forming substance.

23. The method of claim 22, wherein the input water is at least partially cooled toward said temperature conditions conducive to formation of hydrate by being passed through said dissociation region in heat exchanging relationship with said hydrate, whereby heat is absorbed from said input water by said hydrate as said hydrate dissociates endothermically.

51. Water produced according to the method of claim 20 using seawater as said input water.

52. Water produced according to the method of claim 21 using seawater as said input water.

53. Water produced according to the method of claim 22 using seawater as said input water.

54. Water produced according to the method of claim 23 using seawater as said input water.

24. An apparatus for desalinating or purifying saline or polluted input water, respectively, said apparatus comprising:

a mechanically pressurized hydrate formation vessel in fluid communication with a hydrate dissociation vessel;

an input water supply conduit configured to provide said input water to said hydrate formation vessel;

a hydrate-forming substance supply conduit configured to provide a hydrate-forming substance to said hydrate formation vessel;

a fresh water output conduit configured and disposed for removal from said hydrate formation vessel of fresh water released by hydrate dissociating therein; and

a saline water output conduit configured and disposed for removal from said hydrate formation vessel of interstitial residual saline water or gray water.

25. The apparatus of claim 24, wherein said hydrate dissociation vessel is mechanically pressurized.

26. The apparatus of claim 24, further comprising an interchamber disposed between said hydrate formation vessel and said hydrate dissociation vessel and in fluid communication therewith, said interchamber configured for receiving of fresh water, washing of hydrate disposed therein of interstitial residual saline fluid, and replacement of said interstitial residual saline fluid with said fresh water received within said interchamber.

27. The apparatus of claim 24, wherein said hydrate formation vessel and said hydrate dissociation vessel are configured and disposed relative to each other to permit operation of said apparatus with a hydrate-forming substance that produces positively buoyant hydrate.

28. The apparatus of claim 24, wherein said hydrate formation vessel and said hydrate dissociation vessel are configured and disposed relative to each other to permit operation of said apparatus with a hydrate-forming substance that produces negatively buoyant hydrate.

29. The apparatus of claim 24, wherein said hydrate formation vessel and said hydrate dissociation vessel are configured and disposed relative to each other to permit operation of said apparatus with a hydrate-forming substance that produces positively buoyant hydrate as well as with a hydrate-forming substance that produces negatively buoyant hydrate.

30. The apparatus of claim 24, wherein said apparatus is mobile or transportable.

31. The apparatus of claim 30, wherein said apparatus is located aboard a ship.