Water extraction using a directional solvent
Purified water can be obtained via a continuous or semi-continuous process by mixing a liquid composition (e.g., sea water or produced frac water) including water with a directional solvent to selectively dissolve water from the liquid composition into the directional solvent. The concentrated remainder of the liquid composition (e.g., brine) is removed, and the water is precipitated from the directional solvent and removed in a purified form. The solvent is then reused as the process is repeated in a continuous or semi-continuous operation.
1. A method for continuous water extraction, comprising:
(a) flowing a directional solvent in a continuous and substantially closed circuit;
(b) introducing a liquid composition including water and at least one dissolved component into the circuit where the liquid composition mixes with the directional solvent;
(c) heating the directional solvent before or after the introduction of the liquid composition;
(d) dissolving water from the liquid composition into the directional solvent to form a water-solvent solution, while substantially excluding from the directional solvent a concentrated remainder including the component that was dissolved in the liquid composition;
(e) separating the concentrated remainder from the water-solvent solution with a first physical partition positioned to split a majority of the water-solvent solution from the concentrated remainder orthogonally to an incoming flow direction of the water-solvent solution and the concentrated remainder and removing the concentrated remainder from the circuit with the first physical partition;
(f) cooling the water-solvent solution to precipitate the water from the directional solvent;
(g) separating the water in a purified form from the directional solvent by electro-coalescence or dielectrophoresis and removing a majority of the purified water with a second physical partition orthogonally to an incoming flow direction of the purified water and the directional solvent following the electro-coalescence or dielectrophoresis; and
(h) recirculating the directional solvent in the circuit and repeating steps (b)-(g).
2. The method of claim 1 , wherein heating the directional solvent includes heating by a heater selected from a furnace, a boiler, an electric heater, a gas heater, a solar heater, and a geothermal heater.
3. The method of claim 1 , wherein cooling the water-solvent solution includes cooling by a chiller or a heat exchanger or by ambient cooling or evaporative cooling.
4. The method of claim 1 , wherein heat from the water-solvent solution is transferred to the directional solvent via a heat exchanger.
5. The method of claim 1 , wherein the directional solvent is a fatty acid.
6. The method of claim 5 , wherein the fatty acid has a chain length of 6-14 carbon atoms.
7. The method of claim 1 , wherein the concentrated remainder includes water, the method further comprising:
(i) flowing directional solvent through a second continuous and substantially closed circuit;
(j) introducing a combined feed including additional liquid composition and the concentrated remainder that was removed from the circuit in claim 1 , which is referenced in this claim as the first continuous and substantially closed circuit, in step (e) into the second continuous and substantially closed circuit where the combined feed mixes with the directional solvent, wherein the combined feed is added to the directional solvent at a ratio that is substantially the same as a ratio of the liquid composition added to directional solvent in the first continuous and substantially closed circuit;
(k) heating the directional solvent before or after the introduction of the concentrated remainder;
(l) dissolving water from the concentrated remainder into the directional solvent to form a water-solvent solution, while substantially excluding from the directional solvent the dissolved component of the concentrated remainder;
(m) separating the dissolved component from the water-solvent solution and removing the dissolved component from the second continuous and substantially closed circuit;
(n) cooling the water-solvent solution to precipitate the water from the directional solvent;
(o) separating the water from the directional solvent, wherein the water separated from the directional solvent is purified water, and removing the purified water from the second continuous and substantially closed circuit; and
(p) recirculating the directional solvent in the second continuous and substantially closed circuit and repeating steps (j)-(o).
8. The method of claim 7 , wherein the directional solvent and concentrated remainder are mixed in the second continuous and substantially closed circuit at a ratio that is substantially the same as a ratio at which directional solvent and liquid composition are mixed in the first continuous and substantially closed circuit.
9. The method of claim 1 , wherein the liquid composition is a product of oil or gas extraction.
10. The method of claim 1 , wherein the water is separated from the directional solvent by electro-coalescence.
11. The method of claim 1 , wherein the water is separated from the directional solvent by dielectrophoresis.
12. The method of claim 1 , further comprising using electrocoalescence or dielectrophoresis upstream from the first physical partition to assist with the separation of the concentrated remainder from the water-solvent solution.