Desalination system and method

Patent metadata

Field	Value
Publication number	US-9475711-B2
Application number	US-201314384721-A
Country	US
Kind code	B2
Filing date	Feb 14, 2013
Priority date	Mar 12, 2012
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

A desalination system comprises a silica removal unit. The silica removal unit comprises first and second electrodes, a plurality of ion exchange membranes disposed between the first and second electrodes and a plurality of spacers disposed between adjacent ion exchange membranes and between the first and second electrodes and the respective ion exchange membranes. The plurality of the ion exchange membranes comprises a pair of cation exchange membranes and a pair of anion exchange membranes disposed between the pair of cation exchange membranes. A first channel is defined between the anion exchange membranes and second and third channels are defined between each anion exchange membrane and an adjacent cation exchange membrane. A silica removal apparatus and a desalination method are also presented.

First claim

What is claimed is:

1. A desalination system, comprising:
a silica removal unit configured to receive a first feed stream for silica removal and comprising:
first and second electrodes;
a plurality of ion exchange membranes disposed between the first and second electrodes and comprising a pair of cation exchange membranes and a pair of anion exchange membranes disposed between the pair of cation exchange membranes, a first channel being defined between the anion exchange membranes and second and third channels being defined between each anion exchange membrane and an adjacent cation exchange membrane, wherein the second channel is configured to receive output of the third channel; and
a plurality of spacers disposed between adjacent ion exchange membranes and between the first and second electrodes and the respective ion exchange membranes.

2. The desalination system of claim 1 , wherein the second channel is defined between the anion exchange membrane and the cation exchange membrane adjacent to the first electrode, and wherein the third channel is defined between the anion exchange membrane and the cation exchange membrane adjacent to the second electrode.

3. The desalination system of claim 1 , wherein the first channel is configured to receive the first feed stream for silica removal, and wherein the second and third channels are configured to receive respective second and third feed streams cooperating to remove silica from the first feed stream.

4. The desalination system of claim 3 , wherein the second channel is configured to receive the silica removed from the first channel.

5. The desalination system of claim 1 , further comprising a pH adjustment unit in fluid communication with the silica removal unit and configured to adjust pH of the first feed stream.

6. The desalination system of claim 1 , further comprising a pretreatment unit in fluid communication with the silica removal unit and configured to at least partially remove polyvalent cations in a liquid to produce the first feed stream prior to introduction of the first feed stream into the silica removal unit.

7. A desalination system, comprising:
a silica removal apparatus configured to receive a first feed stream for silica removal and comprising:
first and second electrodes;
a plurality of ion exchange membranes disposed between the first and second electrodes and comprising at least three cation exchange membranes and at least two pairs of anion exchange membranes, each pair disposed between two cation exchange membranes so as to define a first channel between each pair of anion exchange membranes and second and third channels between each anion exchange membranes of each pair and an adjacent cation exchange membrane, wherein each second channel is configured to receive output of corresponding third channel; and
a plurality of spacers disposed between adjacent ion exchange membranes and between the first and second electrodes and the respective ion exchange membranes.

8. The desalination system of claim 7 , wherein the second channel is defined between each anion exchange membrane and the respective cation exchange membrane adjacent to the first channel and towards the first electrode, and wherein the third channel is defined between each anion exchange membrane and the respective cation exchange membrane adjacent to the first channel and towards the second electrode.

9. The desalination system of claim 7 , wherein the first channel is configured to receive the first feed stream for silica removal, wherein the second and third channels are configured to receive respective second and third feed streams cooperating to remove silica from the first feed stream, and wherein the second channel is configured to receive the silica removed from the corresponding first channel.

10. The desalination system of claim 7 , wherein the plurality of ion exchange membranes further comprises an additional anion exchange membrane disposed between the first electrode and the cation exchange membrane adjacent to the first electrode.

11. The desalination system of claim 7 , further comprising a pH adjustment unit in fluid communication with the silica removal apparatus and configured to adjust pH of the first feed stream.

12. A desalination method for removing silica from an aqueous stream, comprising:
passing a first feed stream through a first channel defined between at least one pair of anion exchange membranes disposed between first and second electrodes of a silica removal apparatus to produce a first output stream for silica removal;
passing a second feed stream through a second channel defined between the anion exchange membrane of the at least one pair of anion exchange membranes and an adjacent cation exchange membrane disposed between the at least one pair of anion exchange membranes and the first electrode to carry away silica removed from the first feed stream and to produce a second output stream;
passing a third feed stream through a third channel defined between the anion exchange membrane of the at least one pair of anion exchange membranes and an adjacent cation exchange membrane disposed between the at least one pair of anion exchange membranes and the second electrode to facilitate silica removal from the first channel to the adjacent second channel and to produce a third output stream; and
redirecting the third output stream into the second channel to act as the second feed stream.

13. The desalination method of claim 12 , wherein an additional anion exchange membrane is disposed between the first electrode and the cation exchange membrane adjacent to the first electrode.

14. The desalination method of claim 12 , wherein the third feed stream comprises active anions, and wherein the third output stream comprises a lower concentration of the active anions than the concentration of the active anions in the third feed stream.

15. The desalination method of claim 12 , wherein the second and third feed streams comprise different or the same materials.

16. The desalination method of claim 15 , wherein the second feed steam comprises water, and wherein the third feed stream comprises sodium chloride solution.

17. The desalination method of claim 12 , further comprising adjusting pH of the first feed stream prior to introduction of the first feed stream into the first channel.

18. The desalination method of claim 17 , wherein the pH of the first feed stream is adjusted to a range from about 9.5 to about 11.5.

19. The desalination method of claim 12 , further comprising at least partially removing polyvalent cations in a liquid to produce the first feed stream prior to introduction of the first feed stream into the first channel.

Assignees

• Gen Electric

Inventors

• Zhang Chengqian
• Yang Hai
• Xiong Rihua

Classifications

• C02F1/52

  by flocculation or precipitation of suspended impurities {(C02F1/463 takes precedence)} · CPC title

• B01D2311/18

  pH control · CPC title

• C02F2101/10

  Inorganic compounds · CPC title

• B01D61/46

  Apparatus therefor · CPC title

• C02F2303/22

  Eliminating or preventing deposits, scale removal, scale prevention (C02F1/042, C02F1/4602, C02F5/00 take precedence) · CPC title