Desalination Method For Producing Freshwater By Reverse Osmosis Of Seawater

• US 20170355624A1
• Filed: 03/07/2017
• Published: 12/14/2017
• Est. Priority Date: 06/10/2016
• Status: Active Grant

• Current Assignee: Baski Water Instruments
• Original Assignee: Henry A. Baski
• Inventors: Baski, Henry A.
• Granted Patent: US 9,850,144 B1
• Time in Patent Office: Days
• CPC Class Codes: B01D 2317/04 Elements in parallel
• CPC Class Codes: B01D 29/39 with hollow discs side by side on, or around, one or more tubes, e.g. of the leaf type
• CPC Class Codes: B01D 61/025 Reverse osmosis; Hyperfiltration
• CPC Class Codes: B01D 61/08 Apparatus therefor
• CPC Class Codes: B01D 63/0821 Membrane plate arrangements for submerged operation
• CPC Class Codes: C02F 1/441 by reverse osmosis
• CPC Class Codes: C02F 2103/08 Seawater, e.g. for desalination
• CPC Class Codes: Y02A 20/131 Reverse-osmosis

Abstract

A desalination method includes the steps of: providing a plurality of reverse osmosis membrane discs at a depth in an ocean selected to provide a hydrostatic pressure; directing seawater through the membrane discs using the hydrostatic pressure; collecting the freshwater directed through the membrane discs; pumping the freshwater to a surface of the ocean; and then transporting the freshwater to land.

Claims

1. A desalination method comprising:

providing a plurality of reverse osmosis membrane discs at a depth (D) in an ocean selected to provide a hydrostatic pressure and a high-pressure (HP) side for the membrane discs;

providing a pumping system having a casing with an interior configured to provide a low-pressure (LP) side for the membrane discs and a plurality of bowl assemblies configured to pump the freshwater to a surface of the ocean;

directing the seawater through the membrane discs from the high-pressure (HP) side to the low-pressure (LP) side thereof using the hydrostatic pressure to produce the freshwater and a concentrate C;

collecting the freshwater directed through the membrane discs;

diffusing the concentrate C into the ocean at the depth (D);

pumping the freshwater to a surface of the ocean using the pumping system; and

transporting the freshwater to land.

2. The method of claim 1 wherein each pump comprises a pair of inflatable packers attached to the casing, a rotatable impeller attached to the shaft, and a stationary diffuser in flow communication with the conduit configured to form a fluid passageway with the impeller for pumping the freshwater.

3. The method of claim 1 further comprising storing the freshwater.

4. A desalination method comprising:

providing a membrane system configured to perform a reverse osmosis of seawater, the membrane system submerged in an ocean at a depth selected to provide a hydrostatic pressure for generating the reverse osmosis, the membrane system comprising a plurality of membrane discs mounted to a freshwater collection conduit in a spaced array, each membrane disc comprising a membrane substrate coated with a membrane film in flow communication with the seawater at the depth, the freshwater collection conduit comprising a tubular having a plurality of orifices therethrough in flow communication with the membrane discs at a low-pressure side thereof, the freshwater collection conduit configured to receive freshwater produced by the reverse osmosis (RO) of the seawater by the membrane discs, the membrane system is included in a perforated casing in flow communication with the seawater at the depth;

providing a pumping system comprising a casing in flow communication with the freshwater collection conduit configured to receive the freshwater, a shaft rotatably mounted in the casing and a plurality of impellers attached to the shaft configured to pump the freshwater through the casing to a surface of the ocean, the casing configured to provide the low-pressure side for the membrane discs by pumping of the freshwater by the impellers;

directing the seawater through the membrane discs from the high-pressure side to the low-pressure side thereof using the hydrostatic pressure to produce the freshwater and a concentrate;

collecting the freshwater directed through the membrane discs;

diffusing the concentrate into the ocean at the depth;

pumping the freshwater to a surface of the ocean using the pumping system; and

transporting the freshwater to land.

5. The method of claim 4 further comprising storing the freshwater.

6. A membrane system for producing freshwater by reverse osmosis (RO) of seawater comprising:

a perforated casing configured for submerging in seawater and having a plurality of openings configured for flow communication with the seawater at a high pressure side;

a freshwater collection conduit mounted within the perforated casing having a plurality of orifices and an interior configured for flow communication with a low pressure side; and

a plurality of membrane discs mounted to the freshwater collection conduit within the perforated casing, each membrane disc comprising a permeable membrane film on a permeable membrane substrate in flow communication with the openings in the perforated casing, and a drain substrate in flow communication with the orifices in the freshwater collection conduit configured to support the membrane film and the membrane substrate.

7. The membrane system of claim 6 wherein each membrane disc comprises a circular disc having a center opening through the drain substrate for mounting to the freshwater collection conduit.

8. The membrane system of claim 6 wherein the drain substrate comprises porous ceramic.

9. The membrane system of claim 6 wherein each membrane disc comprises a generally circular disc having a thickness that increases from an outside peripheral edge to a center thereof, with a center portion of the membrane disc being thickest and a peripheral edge of the membrane disc being thinnest.

10. The membrane system of claim 6 wherein the membrane discs are mounted to a membrane module within a protective cover tube.