Temperature swing solvent extraction for descaling of feedstreams
Systems and methods of performing temperature swing solvent extraction (TSSE) descaling of produced water and desalination of high-salinity brines, e.g., those having a total dissolved solids (TDS) greater than about 250,000 ppm are capable of producing descaled water products including less than about 5% weight percent TDS. The brine/produced water feedstreams and combined with a solvent having temperature-dependent water solubility at a temperature T L . Water is extracted from the feedstream into the solvent to form a water-in-solvent extract component and a raffinate component, from which a solid phase can be precipitated as more water is portioned in the solvent and basicity increases. Heating of the water-in-solvent extract component reduces the solubility of the water therein, producing a biphasic mixture of dewatered solvent and descaled water that can be separated. Because these systems and methods do not require a phase change of water, these products are achieved with significantly higher energy efficiencies when compared to evaporation-based thermal methods.
1. A method of performing temperature swing solvent extraction (TSSE) desalination of brines, comprising:
providing a feedstream;
combining the feedstream with a solvent, wherein the solvent has temperature-dependent water solubility;
bringing the combined feedstream and solvent to a temperature T L ;
extracting a liquid from the feedstream into the solvent to form a water-in-solvent extract component and a raffinate component at temperature T L , wherein the raffinate component includes an aqueous phase and a solid phase;
separating the water-in-solvent extract component from the raffinate component;
heating the water-in-solvent extract component to a temperature T H to produce a biphasic mixture of dewatered solvent and descaled water; and
separating the dewatered solvent and the descaled water,
wherein the descaled water includes less than 5% weight percent total dissolved solids.
2. The method according to claim 1 , wherein the feedstream includes brine, produced water, or combinations thereof.
3. The method according to claim 1 , further comprising:
cooling the dewatered solvent component from temperature T H ; and
combining the dewatered solvent component with the feedstream.
4. The method according to claim 1 , further comprising:
precipitating the solid phase; and
sieving the solid phase from a liquid phase, the solid phase including one or more scalants from the feedstream.
5. The method according to claim 4 , wherein the one or more scalants includes an alkali metal salts, Ca(OH) 2 , CaCO 3 , FeCO 3 , Mg(OH) 2 , MgCO 3 , MnCO 3 , SrCO 3 , BaSO 4 , CaSO 4 , MgSO 4 , SrSO 4 , or combinations thereof.
6. The method according to claim 1 , wherein the solvent includes diisopropylamine (DIPA), N-ethylcyclohexylamine (ECHA), and N,N-dimethylcyclohexylamine (DMCHA), triethylamine (TEA), N-methylcyclohexylamine (nMCHA), N,N-dimethylisopropylamine (DMIPA), or combinations thereof.
7. The method according to claim 1 , wherein T L is below 20° C.
8. The method according to claim 7 , wherein T L is 16° C.
9. The method according to claim 7 , wherein T L is 5° C.
10. The method according to claim 1 , wherein T H is between 40° C. and 80° C.
11. The method according to claim 10 , wherein T H is 70° C.
12. The method according to claim 1 , further comprising less than −15 mL/mol feedstream to solvent when combining the feedstream with the solvent.
13. The method according to claim 1 , wherein the feedstream has a total dissolved solids greater than 100,000 ppm.
14. The method according to claim 13 , wherein the feedstream has a total dissolved solids greater than 250,000 ppm.
15. The method according to claim 14 , wherein the feedstream has a total dissolved solids greater than 290,000 ppm.
16. The method according to claim 15 , wherein the temperature swing from T L to T H is a continuous temperature gradient.
17. The method according to claim 1 , wherein heating the water-in-solvent extract component to a temperature T H to produce a biphasic mixture of dewatered solvent and descaled water includes:
bringing a previous water-in-solvent component produced via a previous separation step to at least one new temperature T N to produce a biphasic mixture of a subsequent water-in-solvent component and a subsequent raffinate component at temperature T N ;
separating the subsequent water-in-solvent component from the subsequent raffinate component; and
bringing a subsequent water-in-solvent component to a temperature T F to produce a biphasic mixture of dewatered solvent and descaled water,
wherein T F is T H .
18. The method according to claim 17 , wherein the steps of
bringing a previous water-in-solvent component produced via a previous separation step to at least one new temperature T N to produce a biphasic mixture of a subsequent water-in-solvent component and a subsequent raffinate component at temperature T N , and
separating the subsequent water-in-solvent component from the subsequent raffinate component,
is repeated 2 or more times.
19. The method according to claim 18 , wherein the steps of
bringing a previous water-in-solvent component produced via a previous separation step to at least one new temperature T N to produce a biphasic mixture of a subsequent water-in-solvent component and a subsequent raffinate component at temperature T N , and
separating the subsequent water-in-solvent component from the subsequent raffinate component,
is repeated 3 or more times.
20. The method according to claim 1 , wherein neither of the water-in-solvent extract component nor the raffinate component pass through a membrane separation system or an evaporative phase-change system.