Simplified architecture for desalination via electrodialysis

Patent metadata

Field	Value
Publication number	US-12397263-B2
Application number	US-202118021000-A
Country	US
Kind code	B2
Filing date	Aug 13, 2021
Priority date	Aug 14, 2020
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

An electrodialysis desalination device includes a first electrode including a first-stage side; a second electrode including a first-stage side; and a first stage between the first-stage side of the first electrode and the first-stage side of the second electrode. The first stage includes at least one first-stage cell pair positioned between the first-stage side of the first electrode and the first-stage side of the second electrode, and each cell pair includes a pair of first-stage selectively permeable ion-exchange membranes with alternating selectivity that define first-stage channels on opposite sides of each first-stage membrane for respective flows of a first-stage diluate stream and a first-stage concentrate stream. A single pump is configured to pump the diluate streams and the concentrate streams through the first stage.

First claim

What is claimed is:

1. An electrodialysis desalination device, comprising:
a first electrode including a first-stage side;
a second electrode including a first-stage side;
a first stage between the first-stage side of the first electrode and the first-stage side of the second electrode, the first stage including at least one first-stage cell pair positioned between the first-stage side of the first electrode and the first-stage side of the second electrode, each cell pair including a pair of first-stage selectively permeable ion-exchange membranes with alternating selectivity that define first-stage channels on opposite sides of each first-stage membrane for respective flows of a first-stage diluate stream and a first-stage concentrate stream between the first electrode and the second electrode, wherein each of the first-stage channels includes an inlet and an outlet;
a second stage including at least one second-stage cell pair including a plurality of second-stage selectively permeable ion-exchange membranes with alternating selectivity that define second-stage channels on opposite sides of each second-stage membrane for respective flows of a second-stage diluate stream and a second-stage concentrate stream, wherein the outlet for the first-stage channel through which the first-stage diluate stream flows is in fluid communication with the inlet of the second-stage channel through which the second-stage diluate stream flows, and wherein the outlet for the first-stage channel through which the first-stage concentrate stream flows is in fluid communication with the inlet of the second-stage channel through which the second-stage concentrate stream flows;
a single pump configured to pump the diluate streams and the concentrate streams through the first stage and through the second stage, wherein, in each stage, the concentrate stream has an increased ion content that is greater than the ion content of the diluate stream; and
a plurality of flow restrictors in or in communication with a plurality of the channels selected from the first-stage channels and the second-stage channels through which the first-stage and second-stage diluate and concentrate streams respectively flow, wherein each of the flow restrictors is configured to receive at least one of the diluate or concentrate streams in one of the selected channels of the first stage or the second stage, and wherein the flow restrictors are configured in combination with the single pump to generate a flow rate of the diluate stream that is independent and distinct from a flow rate of the concentrate stream through the first-stage and second-stage channels.

2. The electrodialysis desalination device of claim 1 , wherein the second electrode further comprises a second-stage side facing oppositely away from the first-stage side of the second electrode, the device further comprising a third electrode including a second-stage side, wherein the second stage is between the second-stage side of the second electrode and the second-stage side of the third electrode.

3. The electrodialysis desalination device of claim 2 , further comprising a third stage including at least one third-stage cell pair including a plurality of third-stage selectively permeable ion-exchange membranes with alternating selectivity that define third-stage channels on opposite sides of each third-stage membrane for respective flows of a third-stage diluate stream and a third-stage concentrate stream, wherein the outlet for the second-stage channel through which the second-stage diluate stream flows is in fluid communication with the inlet of the third-stage channel through which the third-stage diluate stream flows, and wherein the outlet for the second-stage channel through which the second-stage concentrate stream flows is in fluid communication with the inlet of the third-stage channel through which the third-stage concentrate stream flows, and wherein the single pump is further configured to pump the diluate stream and the concentrate stream through the third stage, and wherein the third electrode further comprises a third-stage side facing oppositely away from the second-stage side of the third electrode, the device further comprising a fourth electrode including a third-stage side, wherein the third stage is between the third-stage side of the third electrode and the third-stage side of the fourth electrode.

4. The electrodialysis desalination device of claim 1 , wherein the first stage and the second stage are adjacent to one another without an electrode therebetween.

5. The electrodialysis desalination device of claim 1 , wherein the electrodialysis desalination device is configured for the diluate and concentrate streams to flow through the second stage in a direction opposite to the flow of the diluate and concentrate streams through the first stage.

6. The electrodialysis desalination device of claim 1 , further comprising a voltage source in electrical communication with the electrodes and configured to apply respective charges to the first electrode, to the second electrode, and to the third electrode, wherein the charge applied to the second electrode is opposite to the charges applied to the first and third electrodes.

7. The electrodialysis desalination device of claim 1 , wherein the inlets to the first-stage channels are in fluid communication with an aqueous saline source.

8. The electrodialysis desalination device of claim 1 , further comprising a voltage source in electrical communication with the electrodes and configured to apply a charge to the second electrode and a charge to the first electrode, wherein the charge applied to the second electrode is opposite to the charge applied to the first electrode.

9. The electrodialysis desalination device of claim 1 , wherein the flow restrictors, the pump, and the channels are configured to flow the diluate stream through the channels at a rate at least twice as great as the rate at which the concentrate stream flows through the channels.

10. The electrodialysis desalination device of claim 1 , wherein the flow restrictors, the pump, and the channels are configured to flow the diluate stream through the channels at a rate at least 10 times as great as the rate at which the concentrate stream flows through the channels.

11. The electrodialysis desalination device of claim 1 , wherein the channels for the diluate streams and for the concentrate streams are configured for a continuous single pass of the diluate and concentrate streams.

12. The electrodialysis desalination device of claim 1 , further comprising a sensor configured to measure the salinity of a saline feed stream as it enters the channels, wherein the device is configured to adjust the voltage charge applied to the electrodes in response to the measured salinity to establish a desired current density for ions passing through the membranes.

13. The electrodialysis desalination device of claim 12 , wherein the device is configured to adjust the voltage charge to establish a desired current density that is set at a limiting current density minus a safety factor, and wherein the desired current density is about 50-95% of the limiting current density.

14. The electrodialysis desalination device of claim 1 , wherein each of the flow restrictors is in a flow path between at least one of the outlets of the first-stage channels and at least one of the inlets of the second-stage channels and is configured to control the flow of at least one of the diluate stream and the concentrate stream between the first and second stages, and wherein the single pump is outside of this flow path.

15. The electrodialysis

Assignees

• Massachusetts Inst Technology

Inventors

• Varner Hannah M
• Winter Amos G
• Shah Sahil Rajesh
• Honarparvar Soraya

Classifications

• B01D61/423

  comprising multiple electrodialysis steps · CPC title

• B01D2313/365

  Electrical sources · CPC title

• B01D2313/19

  Specific flow restrictors · CPC title

• B01D2311/16

  Flow or flux control · CPC title

• C02F2209/40

  Liquid flow rate · CPC title