Hydrate desalination or water purification

• US 6,767,471 B2
• Filed: 08/30/2001
• Issued: 07/27/2004
• Est. Priority Date: 07/12/1999
• 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): Barry, Chester T.
• Application Number:
  US09/941,545
• Publication Number:
  US 20020003111A1
• Time in Patent Office: 1,062 Days
• Field of Search: 210/702, 210/737, 210/767, 210/97, 210/98, 210/150, 210/151, 210/177, 210/188
• US Class Current: 210/702
• 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: H04L 1/1642 Formats specially adapted for sequence numbers
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers
• CPC Class Codes: Y02A 20/124 Water desalination
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

An apparatus is disclosed which allows the hydrate formed in the hydrate formation region of a desalination fractionation apparatus to be cooled as it rises in the apparatus. This has the beneficial effect of increasing its stability at lower pressures and reducing the depth at which the hydrate will begin to dissociate. The present invention provides for more efficient management of the distribution of thermal energy within the apparatus as a whole by controlling the flow of water through the system—particularly residual fluids remaining after hydrate forms—such that it is substantially downward through the fractionation column and out through a lower portion thereof. Hydrate thus separates from the residual fluid at or nearly at the point of formation, which helps keep the hydrate formation region of the apparatus at a temperature suitable for the formation of hydrate and improves efficiency. Hydrate formation may be enhanced, thereby further improving efficiency, by pre-treating the water-to-be-treated so as to dissolve hydrate-forming gas in it, before further hydrate-forming gas is injected into the water-to-be-treated under conditions conducive to the formation of gas hydrate.

Claims

1. A method of desalinating or purifying saltwater or otherwise polluted water-to-be-treated via hydrate fractionation, said method comprising:

introducing said water-to-be-treated into a hydrate fractionation column;

injecting a hydrate-forming gas or mixture of gases into said water-to-be-treated under temperature and pressure conditions conducive to the formation of gas hydrate, whereupon said gas or mixture of gases reacts with said water-to-be-treated at a point of hydrate formation to yield gas hydrate and residual fluid while liberating heat of hydrate formation which tends to warm said residual fluid; and

allowing said gas hydrate to rise through said hydrate fractionation column and to enter a hydrate dissociation region in which said gas hydrate dissociates and releases fresh water and said hydrate-forming gas or mixture of gasses;

wherein said hydrate fractionation column is configured so that fluid is removed from said hydrate fractionation column from a position below said point of hydrate formation, said method comprising controlling flow rates of fluid through said hydrate fractionation column such that substantially all of said residual fluid flows downward from said point of hydrate formation and out of said hydrate fractionation column at said position below said point of hydrate fractionation and such that said gas hydrate separates from said residual fluid at or near said point of hydrate formation, whereby heat of hydrate formation is substantially carried away from said gas hydrate and out of said hydrate fractionation column by means of said residual fluid flowing out of said hydrate fractionation column via said portion below said point of hydrate formation.

2. The method of claim 1, wherein said gas hydrate collects and condenses in a collection and condensation zone of said hydrate fractionation column that is located above said point of formation and below said hydrate dissociation region.

3. The method of claim 1, wherein said flow rates are controlled such that a region of essentially static fluid exists above said point of hydrate formation and wherein the fluid that is removed from said hydrate fractionation column via said portion below said point of hydrate formation comprises a mixture of residual fluid and water-to-be-treated.

4. The method of claim 1, further comprising allowing interstitial residual water carried upward with said gas hydrate to flow out of said hydrate fractionation column through vents or other exit means located above said point of hydrate formation and below said dissociation region.

5. The method of claim 4, further comprising flushing said gas hydrate with fresh water or gray water introduced into said hydrate fractionation column at a point above said vents or other exit means.

6. The method of claim 1, further comprising cooling said water-to-be-treated before introducing it into said hydrate fractionation column.

7. The method of claim 6, wherein said water-to-be-treated is cooled by being passed through said dissociation region in heat-exchanging relation with gas hydrate that is dissociating therein.

8. The method of claim 1, further comprising pre-treating said water-to-be-treated before it is introduced into said hydrate fractionation column by causing said hydrate-forming gas or mixture of gases to be dissolved in said water-to-be-treated under conditions under which hydrate does not form.

9. A method of desalinating or purifying saltwater or otherwise polluted water-to-be-treated via hydrate fractionation, said method comprising:

introducing said water-to-be-treated into a hydrate fractionation column;

injecting a hydrate-forming gas or mixture of gases into said water-to-be-treated under temperature and pressure conditions conducive to the formation of gas hydrate, whereupon said gas or mixture of gases reacts with said water-to-be-treated to yield gas hydrate; and

allowing said gas hydrate to rise through said hydrate fractionation column and to enter a hydrate dissociation region in which said gas hydrate dissociates and releases fresh water and said hydrate-forming gas or mixture of gasses;

said method further comprising pre-treating said water-to-be-treated before it is introduced into said hydrate fractionation column by causing said hydrate-forming gas or mixture of gases to be dissolved in said water-to-be-treated under conditions under which hydrate does not form.

10. The method of claim 9, wherein said hydrate-forming gas or mixture of gases is caused to be dissolved in said water-to-be-treated to saturation.