Hydrate formation and growth for hydrate-based desalination by means of enriching water to be treated

• US 6,890,444 B1
• Filed: 04/01/2003
• Issued: 05/10/2005
• Est. Priority Date: 04/01/2003
• Status: Expired due to Fees

• Current Assignee: Water Generating Systems I, LLC
• Original Assignee: Marine Desalination Systems LLC
• Inventors: Max, Michael D.
• Primary Examiner(s): Hruskoci, Peter A.
• Application Number:
  US10/402,940
• Time in Patent Office: 770 Days
• Field of Search: 625/32, 625/33, 621/23, 622/385, 622/39, 622/40, 203/10, 210/702, 210/737, 210/726, 210/747, 210/749, 210/752, 210/766, 210/774, 210/170, 210/177, 210/181, 210/182, 210/195.1, 210/202, 210/205, 210/738, 210/199
• US Class Current: 210/737
• CPC Class Codes: C02F 1/22 by freezing
• CPC Class Codes: C02F 1/26 by extraction
• CPC Class Codes: C02F 1/44 by dialysis, osmosis or reverse osmosis general membrane separation processes B01D61/00, membrane modules B01D63/00, electrodialysis C02F1/4693, combination of membrane modules and bioreactors C02F3/1268
• CPC Class Codes: C02F 2103/08 Seawater, e.g. for desalination
• CPC Class Codes: C02F 2301/066 Overpressure, high pressure
• CPC Class Codes: Y02A 20/124 Water desalination
• CPC Class Codes: Y02A 20/131 Reverse-osmosis

Abstract

Water to be desalinated or otherwise purified is enriched by having hydrate-forming substance dissolved into it, without causing hydrate to form. Hydrate kernels are brought into contact with the enriched water to be treated, and the hydrate kernels grow outwardly into the water to be treated by incorporating dissolved molecules of the hydrate-forming substance and water from the water to be treated. Thus, substantially solid, generally spherical hydrate masses, which are preferred for hydrate-based desalination or purification, can be formed. Hydrate-forming substances can be dissolved into the water to be treated under conditions not conducive to formation of hydrate, such that hydrate does not form, using vigorous means. Hydrate-forming substance is also preferably dissolved into the water to be treated under conditions suitable for hydrate to form, but without causing hydrate to form, e.g., by being infused into the water to be treated using infusion membranes.

Claims

1. A method for desalinating or purifying saline or otherwise polluted water to be treated using hydrate to do so, including 1) actively or directly forming hydrate of a hydrate-forming substance in a hydrate formation region of a desalination or purification installation under pressure and temperature conditions conducive to formation of said hydrate;

and then

     2) dissociating said hydrate to release and recover from said hydrate fresh water that has been extracted from said water to be treated, said method comprising;

dissolving hydrate-forming substance into said water to be treated in a manner which does not cause hydrate to form so as to form water to be treated that is enriched in hydrate-forming substance;

forming masses of hydrate of said hydrate-forming substance in said hydrate formation region;

exposing said masses of hydrate to said enriched water to be treated; and

allowing said masses of hydrate to grow outwardly into the surrounding water to be treated by incorporating into the hydrate structure, from the water to be treated, fresh water and molecules of said hydrate-forming substance that have been dissolved into said water to be treated.

2. The method of claim 1, wherein hydrate-forming substance is dissolved into said water to be treated at a substantially upstream location relative to said hydrate formation region under conditions not suitable to formation of hydrate such that hydrate does not form upon dissolution of hydrate-forming substance into said water to be treated at said substantially upstream location.

3. The method of claim 2, wherein hydrate-forming substance is dissolved into said water to be treated to the point of saturation or supersaturation at the pressure and temperature conditions extant at said substantially upstream location.

4. The method of claim 2, wherein hydrate-forming substance is caused to be dissolved into said water to be treated at said substantially upstream location by being mixed with said water to be treated in a relatively energetic manner.

5. The method of claim 4, wherein hydrate-forming substance is mixed with said water to be treated by one or more means selected from the group consisting of frits, nozzles, eductors, and venturis.

6. The method of claim 1, wherein hydrate-forming substance is dissolved into said water to be treated at a somewhat upstream location relative to said hydrate formation region under conditions that are suitable for hydrate to form, with dissolution of said hydrate-forming substance into said water to be treated being controlled such that hydrate does not form at said somewhat upstream location.

7. The method of claim 6, wherein hydrate-forming substance is dissolved into said water to be treated at said somewhat upstream location to a concentration that is less than the point of saturation at the pressure and temperature conditions extant at said somewhat upstream location.

8. The method of claim 6, wherein hydrate-forming substance is dissolved into said water to be treated at said somewhat upstream location in a relatively gentle manner so as to avoid forming hydrate.

9. The method of claim 8, wherein hydrate-forming substance is infused into said water to be treated at said somewhat upstream location on a molecular basis.

10. The method of claim 9, wherein said hydrate-forming substance is infused into said water to be treated at said somewhat upstream location using infusion membranes.

11. The method of claim 1, wherein hydrate-forming substance is dissolved into said water to be treated at a co-located location that is approximately right at the hydrate formation region or slightly below it, with dissolving of said hydrate-forming substance into said water to be treated being controlled such that said dissolving, per se, does not initiate hydrate nucleation.

12. The method of claim 11, wherein hydrate-forming substance is dissolved into said water to be treated at said co-located location to a concentration that is less than the point of saturation at the pressure and temperature conditions extant at said co-located location.

13. The method of claim 11, wherein hydrate-forming substance is dissolved into said water to be treated at said co-located location in a relatively gentle manner so as to avoid forming hydrate by said dissolving, per se.

14. The method of claim 13, wherein hydrate-forming substance is infused into said water to be treated at said co-located location on a molecular basis.

15. The method of claim 14, wherein said hydrate-forming substance is infused into said water to be treated at said co-located location using infusion membranes.

16. The method of claim 1, wherein hydrate-forming substance is dissolved into the water to be treated 1) at a substantially upstream location relative to said hydrate formation region under conditions not suitable to formation of hydrate such that hydrate does not form upon dissolution of hydrate-forming substance into said water to be treated at said substantially upstream location;

and

     2) at at least one of (a) a somewhat upstream location relative to said hydrate formation region under conditions that are suitable for hydrate to form, with dissolution of said hydrate-forming substance into said water to be treated being controlled such that hydrate does not form at said somewhat upstream location and (b) a co-located location that is approximately right at the hydrate formation region or slightly below it, with dissolving of said hydrate-forming substance into said water to be treated being controlled such that said dissolving, per se, does not initiate hydrate nucleation.

17. The method of claim 16, wherein hydrate-forming substance is dissolved into said water to be treated at each of said substantially upstream, somewhat upstream, and co-located locations.

18. The method of claim 1, wherein said method is practiced in an installation comprising an in-land shaft extending deep enough into the ground for the weight of a column of water in the shaft to generate the pressure conditions conductive to formation of hydrate.

19. The method of claim 1, wherein said method is practiced using positively buoyant hydrate.

20. The method of claim 1, wherein said masses of hydrate are positively buoyant and wherein flow through said desalination or purification installation is controlled such that residual brine is flushed generally downward and out of said installation, thereby removing heat of exothermic formation of hydrate from said installation.

21. The method of claim 1, wherein said enriched water to be treated is introduced into said hydrate formation region at a water introduction location;

wherein said hydrate masses are initially formed at a hydrate formation location; and

wherein said water introduction location is positioned relative to said hydrate formation location such that said enriched water to be treated and said hydrate masses move through said hydrate formation region in opposite, counter-flow fashion.

22. An installation for desalinating or purifying saline or otherwise polluted water to be treated using hydrate to do so by 1) actively or directly forming hydrate of a hydrate-forming substance in a hydrate formation region of said installation under pressure and temperature conditions conducive to formation of said hydrate;

and then

     2) dissociating said hydrate to release and recover from said hydrate fresh water that has been extracted from said water to be treated, said installation comprising;

a hydrate formation region configured to receive water to be treated under pressure conditions suitable for forming hydrate of said hydrate-forming substance;

a substantially upstream hydrate-forming substance dissolving device that is disposed relative to said hydrate formation region at a substantially upstream location where pressure conditions are not suitable for hydrate of said hydrate-forming substance to form; and

at least one of (a) a somewhat upstream hydrate-forming substance dissolving device that is disposed relative to said hydrate formation region at a somewhat upstream location where pressure conditions are suitable for hydrate of said hydrate-forming substance to form and (b) a co-located hydrate-forming substance dissolving device that is disposed at a co-located location approximately right at the hydrate formation region or slightly below it.

23. The installation of claim 22, wherein said installation includes hydrate-forming devices at each of said substantially upstream, somewhat upstream, and co-located locations.

24. The installation of claim 22, wherein said substantially upstream hydrate-forming substance dissolving device comprises one or more means selected from the group consisting of frits, nozzles, eductors, and venturis.

25. The installation of claim 22, wherein said somewhat upstream hydrate-forming substance dissolving device comprises infusion membranes.

26. The installation of claim 22, wherein said co-located hydrate-forming substance dissolving device comprises infusion membranes.