Switchable system for high-salinity brine desalination and fractional precipitation

Patent metadata

Field	Value
Publication number	US-11840462-B2
Application number	US-202217567809-A
Country	US
Kind code	B2
Filing date	Jan 3, 2022
Priority date	Jan 4, 2021
Publication date	Dec 12, 2023
Grant date	Dec 12, 2023

Abstract

A saline feed stream flows into a liquid-liquid extraction system; and a volatile organic solvent flows through a main compressor. The compressed volatile organic solvent then flows through a solvent regenerator, which can be a heat exchanger or a combination of a vaporization device and a condenser, to cool the volatile organic solvent. The cooled volatile organic solvent in liquid phase then flows into the liquid-liquid extraction system, where the saline feed stream contacts the volatile organic solvent to selectively extract water from the saline feed stream into the volatile organic solvent, producing a concentrated brine and an organic-rich mixture of water and the volatile organic solvent. The organic-rich mixture flows from the liquid-liquid extraction system into the solvent regenerator, where the organic-rich mixture is heated to produce an organic-rich vapor and desalinated water; and the organic-rich vapor is recycled as volatile organic solvent back into the liquid-liquid extraction system.

First claim

What is claimed is:

1. A method for desalination using a switchable volatile organic solvent, comprising:
flowing a saline feed stream into a liquid-liquid extraction system;
flowing a volatile organic solvent in a vapor phase through a main compressor;
compressing the vapor-phase volatile organic solvent in the main compressor;
flowing the volatile organic solvent through a solvent regenerator to cool and condense the vapor-phase volatile organic solvent, wherein the solvent regenerator is selected from (a) a heat exchanger providing vaporization and condensation and (b) a vaporization device and a condenser;
flowing the cooled volatile organic solvent in a liquid phase into the liquid-liquid extraction system;
contacting the saline feed stream with the liquid-phase volatile organic solvent in the liquid-liquid extraction system to selectively extract water from the saline feed stream into the volatile organic solvent to produce a concentrated brine and an organic-rich mixture of water and the volatile organic solvent in the liquid phase;
flowing the liquid-phase organic-rich mixture from the liquid-liquid extraction system into the solvent regenerator;
heating the liquid-phase organic-rich mixture in the solvent regenerator to produce an organic-rich vapor and desalinated water; and
recycling the organic-rich vapor as volatile organic solvent through the main compressor, through the solvent regenerator, and back into the liquid-liquid extraction system,
wherein, if the solvent regenerator is the vaporization device and the condenser, the volatile organic solvent flows through the condenser, and the organic-rich mixture flows through the vaporization device.

2. The method of claim 1 , wherein the volatile organic solvent comprises dimethyl ether.

3. The method of claim 1 , wherein the solvent regenerator is the heat exchanger.

4. The method of claim 1 , wherein the solvent regenerator comprises the vaporization device and the condenser.

5. The method of claim 1 , further comprising controlling the flow of the cooled volatile organic solvent into the liquid-liquid extraction system using a valve.

6. The method of claim 1 , further comprising further cooling the cooled volatile organic solvent between the solvent regenerator and the liquid-liquid extraction system.

7. The method of claim 1 , further comprising passing the volatile organic solvent through a secondary compressor to initially compress the volatile organic solvent before being further compressed in the main compressor.

8. The method of claim 7 , wherein the recycled organic-rich vapor is compressed in the main compressor but not in the secondary compressor.

9. The method of claim 1 , further comprising fractionally precipitating salt from the concentrated brine.

10. A system for desalination using a switchable volatile organic solvent, the method comprising:
a liquid-liquid extraction system, including:
(A) a volatile-organic-solvent inlet into which a volatile organic solvent can be fed;
(B) a saline-feed inlet into which a saline feed stream is fed, wherein the liquid-liquid extraction system is configured to extract water from a saline feed stream that is fed through the saline-feed inlet into volatile organic solvent that is fed through the volatile-organic-solvent inlet;
(C) a brine outlet through which a concentrated brine, produced from the saline feed stream after water is extracted from the saline feed stream, leaves the system; and
(D) an organic-rich-mixture outlet through which an organic-rich mixture containing the extracted water leaves the system;
a mechanical-vapor-compression regenerator, including:
(A) a main compressor; and
(B) a solvent regenerator selected from (i) a heat exchanger providing vaporization and condensation and (ii) a vaporization device and a condenser, the solvent regenerator including:
(a) an organic-rich-mixture inlet in fluid communication with the organic-rich-mixture outlet of the liquid-liquid extraction system, wherein the solvent regenerator is configured to vaporize dissolved organic compounds from the organic-rich mixture to produce an organic-rich vapor and to leave liquid-phase desalinated water;
(b) an organic-rich-vapor outlet in fluid communication with the main compressor to feed the organic-rich vapor as volatile organic solvent into the main compressor;
(c) a volatile-organic-solvent inlet in fluid communication with the main compressor to feed volatile organic solvent in a vapor form from the main compressor, after compression in the main compressor, into the volatile-organic-solvent inlet to transfer heat to the organic-rich mixture in a liquid form in the solvent regenerator;
(d) a volatile-organic-solvent outlet in fluid communication with the volatile-organic-solvent inlet of the liquid-liquid extraction system for recycling the volatile organic solvent in the liquid form to the liquid-liquid extraction system; and
(e) a desalinated-water outlet positioned to release the desalinated water from the solvent regenerator.

11. The switchable system of claim 10 , further comprising a valve or energy-recovery device configured to control fluid flow between the liquid-liquid extraction system and the solvent regenerator in at least one of (a) a conduit from the organic-rich-mixture outlet of the liquid-liquid extraction system to the organic-rich mixture inlet of the solvent regenerator and (b) a conduit from the volatile organic-solvent outlet of the solvent regenerator to the volatile-organic-solvent inlet of the liquid-liquid separator.

12. The switchable system of claim 10 , further comprising:
a source of the volatile organic solvent; and
a secondary compressor in fluid communication with the main compressor and with the source of volatile organic solvent and configured to initially compress volatile organic solvent from the source of volatile organic solvent before further compression in the main compressor before entering the volatile-organic solvent inlet of the solvent regenerator.

13. The switchable system of claim 10 , further comprising a cooler in a conduit from the volatile-organic-solvent outlet of the solvent regenerator to the volatile-organic-solvent inlet of the liquid-liquid extraction system and configured to cool volatile organic solvent flowing therethrough.

14. The switchable system of claim 10 , further comprising a saline solution in fluid communication with the saline-feed inlet of the liquid-liquid extraction system.

15. The switchable system of claim 10 , wherein the volatile organic solvent comprises dimethyl ether.

16. The switchable system of claim 10 , wherein the solvent regenerator is the heat exchanger.

17. The switchable system of claim 10 , wherein the solvent regenerator comprises the vaporization device and the condenser, and wherein:
the organic-rich mixture inlet, the organic-rich-vapor outlet, and the desalinated water outlet are included in the vaporization device; and
the volatile-organic-solvent inlet and the volatile-organic-solvent outlet are included in the condenser.

Assignees

• Massachusetts Inst Technology
• Battelle Energy Alliance Llc

Inventors

• Wilson Aaron D
• Lienhard John
• Deshmukh Akshay
• Foo Zi Hao

Classifications

• C02F1/265 Primary

  Desalination · CPC title

• B01D1/284

  Special features relating to the compressed vapour · CPC title

• B01D5/0003

  by using heat-exchange surfaces for indirect contact between gases or vapours and the cooling medium · CPC title

• B01D5/006

  with evaporation or distillation · CPC title

• B01D11/0488

  Flow sheets · CPC title