Water pretreatment unit using a fluorinated liquid

Abstract

A unit for pretreating water by heat and/or ion treatment. It provides a pretreatment unit including a direct contact heat and/or ion exchanger having a continuous or dispersed phase that includes a fluorinated liquid that is not miscible with water with a density of more than 1.25.

Claims

1. A process for pretreating saline water employing a pretreatment unit, the pretreatment unit comprising an ion exchanger configured to contain a continuous or dispersed fluorinated phase comprising at least one of a cationic fluorinated ion-exchange liquid and an anionic fluorinated ion-exchange liquid that is not miscible with water and has a density of more than 1.25, the process comprising: introducing the continuous or dispersed fluorinated phase to an upper end of a portion of the ion exchanger and introducing saline water to a lower end of the portion of the ion exchanger in order to carry out counter-current ion exchange between the water ascending in the portion of the ion exchanger and the fluorinated phase descending in the portion of the ion exchanger; and recovering the ascended water as pretreated water.

2. A process for pretreating saline water according to claim 1, wherein the fluorinated phase is continuous and the saline water is introduced in a dispersed form.

3. A process for pretreating saline water according to claim 1, wherein the fluorinated phase is dispersed and the saline water is introduced in a continuous form.

4. A process for pretreating saline water according to claim 1, further comprising: recovering the descended fluorinated phase from the lower end of the portion of the ion exchanger; introducing the recovered fluorinated phase to an upper end of a portion of a regeneration exchanger of the pretreatment unit; introducing regeneration water to a lower end of the portion of the regeneration exchanger in order to carry out counter-current ion exchange between the regeneration water ascending in the portion of the regeneration exchanger and the recovered fluorinated phase descending in the portion of the regeneration exchanger; recovering the descended fluorinated phase as regenerated fluorinated phase; and introducing the regenerated fluorinated phase to an upper portion of the ion exchanger.

5. A process for pretreating saline water according to claim 1, wherein introducing the saline water to the lower end of the portion of the ion exchanger includes compressing the saline water at a predetermined pressure in a range of 1 to 15 bars absolute.

6. A process for pretreating saline water according to claim 4, wherein, in the ion exchanger, ions are exchanged or extracted from the saline water to the fluorinated phase so that the pretreated water is at least one of softened and desalinated as a function of the ions exchanged or extracted from the saline water into the fluorinated phase.

7. A process for pretreating saline water according to claim 4, wherein, in the regeneration exchanger, ions are exchanged from the fluorinated phase to the regeneration water so that the fluorinated phase is depleted of ions in order to be re-used as regenerated fluorinated phase for pretreatment of additional saline water.

8. A process for treating saline water, the process comprising: the process for pretreating saline water according to claim 1; and treating the recovered pretreated water desalination.

9. A process for treating saline water according to the claim 8, further comprising: recovering the descended fluorinated phase from the lower end of the portion of the ion exchanger; introducing the recovered fluorinated phase to an upper end of a portion of a regeneration exchanger of the pretreatment unit; introducing regeneration water to a lower end of the portion of the regeneration exchanger in order to carry out counter-current ion exchange between the regeneration water ascending in the portion of the regeneration exchanger and the recovered fluorinated phase descending in the portion of the regeneration exchanger; recovering the descended fluorinated phase as regenerated fluorinated phase; and introducing the regenerated fluorinated phase to an upper portion of the ion exchanger, wherein the regeneration water comprises at least a portion of the water desalinated during the treatment step.

10. A process for pretreating saline water according to claim 1, wherein the at least one of the cationic fluorinated ion-exchange liquid and the anionic fluorinated ion-exchange liquid comprises at least one of a fluorinated ionic surfactant and a non-ionic surfactant.

11. A process for pretreating saline water according to claim 1, wherein the anionic fluorinated ion-exchange liquid comprises a cationic polar head comprising at least one heteroatom selected from the group consisting of nitrogen, phosphorous, oxygen, and sulfur.

12. A process for pretreating saline water according to claim 1, wherein the cationic fluorinated ion-exchange liquid comprises an anionic polar head comprising at least one heteroatom selected from the group consisting of boron, aluminum, oxygen, and sulfur.

13. A process for pretreating saline water according to claim 1, wherein the at least one of the cationic fluorinated ion-exchange liquid and the anionic fluorinated ion-exchange liquid that is not miscible with the water is a compound with empirical formula C.sub.nH.sub.mF.sub.pN.sub.qO.sub.xS.sub.y in which: C, H, F, N, O, S respectively represent a carbon, hydrogen, fluorine, nitrogen, oxygen and sulfur atom; n is an integer in a range 3 to 25, limits included; m is an integer in a range 0 to 27, limits included; p is an integer in a range 5 to 54, limits included; q is an integer in a range 0 to 6, limits included; and x is an integer in a range 0 to 10, limits included; and y is an integer in a range 0 to 6, limits included.

14. A process for pretreating saline water according to claim 1, wherein the at least one of the cationic fluorinated ion-exchange liquid and the anionic fluorinated ion-exchange liquid that is not miscible with the water is a hydrofluorocarbon compound.

15. A process for pretreating saline water according to claim 14, wherein the hydrofluorocarbon compound comprises at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur.

16. A process for pretreating saline water according to claim 10, wherein the at least one of the cationic fluorinated ion-exchange liquid and the anionic fluorinated ion-exchange liquid comprises in a range of 0.5% to 30% by volume of the at least one of the fluorinated ionic surfactant and the non-ionic surfactant.

17. A process for pretreating saline water according to claim 1, wherein the fluorinated phase is continuous and the ion exchanger comprises a device configured to recycle the continuous fluorinated phase.

Description

(1) The invention can be better understood from the following description given solely by way of example and made with reference to the accompanying drawings in which:

(2) FIG. 1 shows a first embodiment in which the direct contact heat exchanger operates at high temperature;

(3) FIG. 2 shows a second embodiment in which the direct contact heat exchanger operates at low temperature;

(4) FIG. 3 shows a third embodiment in which the direct contact heat exchanger operates both in heat exchange and ion exchange mode, i.e. at high temperature and with a continuous phase comprising a hydrophobic fluorinated liquid and an ionic surfactant with an ion exchange head;

(5) FIG. 4 illustrates the presence of surfactants with anionic heads around a water droplet;

(6) FIG. 5 illustrates the presence of surfactants with cationic heads around a water droplet;

(7) FIG. 6 is a diagram of cation and anion exchange between the fluorinated phase and the water to be treated; and

(8) FIG. 7 represents a fourth embodiment in which the direct contact exchanger operates both in heat exchange and in ion exchange mode i.e. at high temperature and with a continuous phase comprising a hydrophobic fluorinated liquid and cationic and anionic surfactants with ion exchange heads.

EXAMPLE 1: HEAT EXCHANGE LIQUIDS

(9) TABLE-US-00001 TABLE 1 HYDROPHOBIC FLUORINATED LIQUID Semi- developed Mw Tbp Tmp 25 C. Empirical Name formula (g/mol) ( C.) ( C.) (kg/m.sup.3) formula Water (reminder) HOH 18 100 0 997 H.sub.2O PERFLUROCARBONS PFCPerfluorooctane CF.sub.3(CF.sub.2).sub.6CF.sub.3 438 106 25 1765 C.sub.8F.sub.18 PFCPerfluorononane CF.sub.3(CF.sub.2).sub.7CF.sub.3 488 118 16 1788 C.sub.9F.sub.20 HYDROFLUOROCARBONS HFC1,1,1H- CH.sub.3(CF.sub.2).sub.6CF.sub.3 384 109* 76* 1445* C.sub.8H.sub.3F.sub.15 Perfluorooctane HFC1,1,1H- CH.sub.3(CF.sub.2).sub.7CF.sub.3 434 121* 66* 1475* C.sub.9H.sub.3F.sub.17 Perfluorononane PERFLUOROCYCLOHEXANES PFCHPerfluoro-1,3- C.sub.6F.sub.10(CF.sub.3).sub.2 400 102 55 1828 C.sub.8F.sub.16 dimethylcyclohexane PFCHPerfluoro-1,3,5- C.sub.6F.sub.9(CF.sub.3).sub.3 450 127 68 1888 C.sub.9F.sub.18 trimethylcyclohexane HYDROFLUOROCYCLOHEXANES HFCH1,1,1H- C.sub.6F.sub.11(CH.sub.3) 296 100* 88* 1540* C.sub.7H.sub.3F.sub.11 Perfluoromethylcyclo hexane HFCH1,1,1H- C.sub.6F.sub.10(CF.sub.3)(CH.sub.3) 346 127* 63* 1580* C.sub.8H.sub.3F.sub.13 Perfluoro-1,2- dimethylcyclohexane PERFLUORDECALINS PFDPerfluorodecalin C.sub.4F.sub.8 > (CF).sub.2 < C.sub.4F.sub.8 462 142 10 1930 C.sub.10F.sub.18 PFMDPerfluoro(methyl PFD-(CF.sub.3) 512 160 70 1970 C.sub.11F.sub.22 decalin) HYDROFLUORODECALINS HFMD1,1,1H- PFD-(CH.sub.3) 458 185* 77 1690* C.sub.11H.sub.3F.sub.19 Perfluoro (methyldecalin) PERFLUORODIALKYLAMINE Perfluorobutylpentyl (C.sub.4F.sub.9)(C.sub.5F.sub.11)NF 521 99* 45* 1725* C.sub.9F.sub.21N amine Perfluorodipentylamine (C.sub.5F.sub.11).sub.2NF 571 115* 35* 1755* C.sub.10F.sub.23N HYDROFLUORODIALKYLAMINES Methyl-1 perfluoro- (CH.sub.3C.sub.3F.sub.6)(C.sub.5F.sub.11)NF 467 113* 52* 1575* C.sub.9H.sub.3F.sub.18N propylpentyl amine Methyl-1 perfluoro- (CH.sub.3C.sub.4F.sub.8)(C.sub.5F.sub.11)NF 517 128* 41* 1600* C.sub.10H.sub.3F.sub.20N butylpentyl amine PERFLUOROTRIALKYLAMINES Perfluoroethyldipropyl (C.sub.2F.sub.5)(C.sub.3F.sub.7).sub.2N 471 101 65 1760 C.sub.8F.sub.19N amine PFTAPerfluoro- (C.sub.3F.sub.7).sub.3N 521 130 52 1820 C.sub.9F.sub.21N tripropylamine HYDROFLUOROTRIALKYLAMINES Methyl-1 perfluoro- (CH.sub.3CF.sub.2)(C.sub.3F.sub.7).sub.2N 417 98* 64* 1550* C.sub.8H.sub.3F.sub.16N methyldiethyl amine Methyl-1 perfluoro- (CH.sub.3C.sub.2F.sub.4)(C.sub.3F.sub.7).sub.2N 467 113* 52* 1575* C.sub.9H.sub.3F.sub.18N ethyldipropyl amine PERFLUOROAZACYCLOHEXANES Perfluoro-N- .sub.cycle(C.sub.5F.sub.10N)(CF.sub.3) 333 102* 50* 1750* C.sub.6F.sub.13N methylpiperidine PERFLUOROETHERS PFEPerfluorodibutyl (C.sub.4F.sub.9).sub.2O 454 102 48* 1860* C.sub.8F.sub.18O ether PFEPerfluorodipentyl (C.sub.5F.sub.11).sub.2O 554 129* 38* 1925* C.sub.10F.sub.22O ether HYDROFLUOROETHERS HFE - Methyl-Perfluoro- C.sub.6F.sub.13OCH.sub.3 350 98 38 1660 C.sub.7H.sub.3F.sub.13O hexyl ether HFE - 2-trifluoro- C.sub.2H.sub.5OCF(C.sub.3F.sub.7)CF(CF.sub.3).sub.2 414 128 100 1614 C.sub.9H.sub.5F.sub.15O methyl-3- ethoxydodecofluoro- hexane PERFLUOROCYCLOETHERS PFCEPerfluoro-2- C.sub.4F.sub.9FC < (C.sub.3F.sub.6O)cycle 416 102 88 1770 C.sub.8F.sub.16O butyltetrahydrofuran HYDROFLUOROCYCLOETHERS HFCE1H,1H,1H- CH.sub.3C.sub.3F.sub.6FC < (C.sub.3F.sub.6O)cycle 362 105* 92* 1650* C.sub.8H.sub.3F.sub.13O Perfluoro-2- butyltetrahydrofuran PERFLUOROPOLYETHERS PFPEPerfluoro- CF.sub.3(OC.sub.2F.sub.4).sub.3OCF.sub.3 502 106 80* 1875* C.sub.8F.sub.18O.sub.4 triglyme PFPE - HT110 CF.sub.3((OCFCF.sub.2)CF.sub.3)(OCF.sub.2).sub.4OCF.sub.3 584 110 110 1710 C.sub.9F.sub.20O.sub.6 HYDROFLUOROPOLYETHERS HFPE1H,1H,1H-Perfluoro- CF.sub.3(OC.sub.2F.sub.4).sub.3OCH.sub.3 448 138* 80* 1600* C.sub.8H.sub.3F.sub.15O.sub.4 triglyme HFPE - ZT130 HF.sub.2C(OC.sub.2F.sub.4)(OCF.sub.2).sub.4OCF.sub.2H 498 130 114 1650 C.sub.8H.sub.2F.sub.16O.sub.6 PERFLUOROSULFIDES OR PERFLUOROTHIOETHERS PFEPerfluorodipropyl (C.sub.3F.sub.7).sub.2S 370 100* 71* 1850* C.sub.6F.sub.14S thioether PFEPerfluorodibutyl (C.sub.4F.sub.9).sub.2S 470 135* 46* 1900* C.sub.8F.sub.18S thioether HYDROFLUOROSULFIDES OR HYDROFLUOROTHIOETHERS 1-Methylsulfanyl- C.sub.5F.sub.11SCH.sub.3 316 109* 82* 1530* C.sub.6H.sub.3F.sub.11S PerfluoroPentane 1-Methylsulfanyl- C.sub.6F.sub.13SCH.sub.3 366 127* 69* 1560* C.sub.7H.sub.3F.sub.13S PerfluoroHexane PERFLUOROCYCLOTHIOETHERS Perfluoro-2-methyl-1- CF.sub.3FC < (C.sub.4F.sub.8S).sub.cycle 332 104* 70* 1700* C.sub.6F.sub.12S thiacyclohexane IONIC LIQUIDS 1-Ethyl-3- 1,3-C.sub.2H.sub.5CH.sub.3.sub.cycle(C.sub.3H.sub.3N.sub.2).sup.+(CF.sub.3SO.sub.2).sub.2N.sup. 391 417 16 1520 C.sub.8H.sub.11F.sub.6N.sub.3O.sub.4S.sub.2 methylimidazolium Dec. bis(trifluoromethyl sulfonyl)imide 1-Butyl-1- 1,1-C.sub.4H.sub.9CH.sub.3.sub.cycle(C.sub.4H.sub.8N).sup.+(CF.sub.3SO.sub.2).sub.2N.sup. 422 >350 50 1400 C.sub.11H.sub.20F.sub.6N.sub.2O.sub.4S.sub.2 methylpyrrolidinium bis(trifluoromethyl sulfonyl)imide 1-Butyl-3- 1,3-C.sub.4H.sub.9CH.sub.3.sub.cycle(C.sub.5H.sub.4N).sup.+(CF.sub.3SO.sub.2).sub.2N.sup. 430 >350 16 1400 C.sub.12H.sub.16F.sub.6N.sub.2O.sub.4S.sub.2 methylpyridinium bis(trifluoromethyl sulfonyl)imide 1-Ethyl-3- 1,3-C.sub.2H.sub.5CH.sub.3.sub.cycle(C.sub.3H.sub.3N.sub.2).sup.+(CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup. 491 >350 1 1340 C.sub.10H.sub.11F.sub.10N.sub.3O.sub.4S.sub.2 methylimidazolium bis(pentafluoroethyl sulfonyl)imide *Boiling points, melting points and densities determined by a group analysis process based on more than 600 molecules with known or partially known physical properties.

EXAMPLE 2: NON-IONIC FLUORINATED SURFACTANTS

(10) TABLE-US-00002 TABLE 2 NON-IONIC FLUORINATED SURFACTANTS Semi- developed Mw Tbp 25 C. Empirical Name formula (g/mol) ( C.) HLB (kg/m.sup.3) formula PERFLUOROALDEHYDE Perfluorooctanal C.sub.7F.sub.15HCO 398 108* 1.1 1800* C.sub.8HF.sub.15O Perfluorononanal C.sub.8F.sub.17HCO 448 125* 0.2 1840* C.sub.9HF.sub.17O HYDROFLUOROALDEHYDE 2,2H-perfluoroheptanal C.sub.5F.sub.11CH.sub.2HCO 312 109* 2.4 1800* C.sub.7H.sub.3F.sub.11O 2,2H-perfluorooctanal C.sub.6F.sub.13CH.sub.2HCO 362 127* 1.5 1825* C.sub.8H.sub.3F.sub.13O HYDROFLUOROETHERALDEHYDE 2,2H-3-oxy-perfluoro- C.sub.4F.sub.9OCH.sub.2HCO 278 111* 4.5 1870* C.sub.6H.sub.3F.sub.9O.sub.2 hexanal 2,2H-3-oxy-perfluoro- C.sub.6F.sub.13OCH.sub.2HCO 378 148* 2.8 1925* C.sub.8H.sub.3F.sub.13O.sub.2 octanal HYDROFLUOROTHIOETHERALDEHYDE 2,2H-3-thio-perfluoro- C.sub.4F.sub.9SCH.sub.2HCO 294 149* 3.5 1900* C.sub.6H.sub.3F.sub.3OS hexanal PERFLUOROALKYLAMINES Perfluorohexylamine C.sub.6F.sub.13NH.sub.2 335 104* 1.0* 1730* C.sub.6H.sub.2F.sub.13N Perfluoroheptylamine C.sub.7F.sub.15NH.sub.2 385 121* 0.8* 1760* C.sub.7H.sub.2F.sub.15N HYDROFLUOROALKYLAMINES 1,1H-Perfluoro- C.sub.5F.sub.11CH.sub.2NH.sub.2 299 124* 1.1* 1550* C.sub.6H.sub.4F.sub.11N hexylamine PERFLUOROALKYLETHERAMINES Perfluorohexyloxyamine C.sub.6F.sub.13ONH.sub.2 351 102* 1.8* 1830* C.sub.6H.sub.2F.sub.13NO HYDROFLUOROEALKYLTHERAMINES 1,1H-Perfluoro- C.sub.4F.sub.9OCH.sub.2NH.sub.2 265 126* 2.4* 1620* C.sub.5H.sub.4F.sub.9NO butyloxymethylamine PERFLUOROALKYLTHIOETHERAMINES Perfluorobutyl- C.sub.4F.sub.9SNH.sub.2 267 110* 3.6* 1530* C.sub.4H.sub.2F.sub.9NS thioetheramine Perfluoropentyl- C.sub.5F.sub.11SNH.sub.2 317 128* 3.0* 1560* C.sub.5H.sub.2F.sub.11NS thioetheramine PERFLUOROALKYL ETHYLENE ALCOHOL Perfluorobutylether C.sub.4F.sub.9OCH.sub.2CH.sub.2OH 280 176* 5.8* 1685* C.sub.6H.sub.5F.sub.9O.sub.2 ethylene alcohol Perfluoropentylether C.sub.5F.sub.11OCH.sub.2CH.sub.2OH 330 195* 4.9* 1700* C.sub.7H.sub.5F.sub.11O.sub.2 ethylene alcohol CROWN PERFLUORODIALKYLETHERS Perfluoro dibutane12- / 864 / / / C.sub.16F.sub.32O.sub.4 crown-4-ether Perfluoro dipentane15- / 1080 / / / C.sub.20F.sub.40O.sub.5 crown-5-ether Perfluoro dihexane18- / 1296 / / / C.sub.24F.sub.48O.sub.6 crown-6-ether Perfluoro diheptane21- / 1512 / / / C.sub.28F.sub.56O.sub.7 crown-7-ether CROWN HYDROFLUORODIALKYLETHERS hydrofluoro dihexane18- / 1152 C.sub.16H.sub.8F.sub.40O.sub.6 crown-6-ether *Boiling points, melting points and densities determined by a group analysis process based on more than 600 molecules with known or partially known physical properties. HLB: hydrophilic/lipophilic balance.

EXAMPLE 3: IONIC FLUORINATED SURFACTANTS

(11) TABLE-US-00003 TABLE 3 IONIC FLUORINATED SURFACTANTS Semi- developed Mw Tbp Tmp 25 C. Empirical Name formula (g/mol) ( C.) ( C.) (kg/m.sup.3) formula PERFLUOROALCOHOLS Perfluoropentanol-1 C.sub.5F.sub.11OH 286 111* 46* 1765* C.sub.5HF.sub.11O Perfluorohexanol-1 C.sub.6F.sub.13OH 336 128* 33* 1800* C.sub.6HF.sub.13O Perfluorononanol-1 C.sub.9F.sub.19OH 486 174* 0* 1885* C.sub.9HF.sub.19O PERFLUORODIALCOHOLS Perfluorohexane diol-1,2 C.sub.4F.sub.9CF < (OH)(CF.sub.2OH) 334 182* 67* 1890* C.sub.6H.sub.2F.sub.12O.sub.2 Perfluorononane diol-1,2 C.sub.7F.sub.15CF < (OH)(CF.sub.2OH) 484 233* 31* 1975* C.sub.9H.sub.2F.sub.18O.sub.2 Perfluoroundecane C.sub.9F.sub.19CF < (OH)(CF.sub.2OH) 584 264* 11* 2040* C.sub.11H.sub.2F.sub.22O.sub.2 diol-1,2 PERFLUOROALKOXIDES Sodium Perfluoro- C.sub.8F.sub.17O.sup.Na.sup.+ 458 / / / C.sub.8F.sub.17ONa octanolate-1 PERFLUORODIALKOXIDES Disodium Perfluoro- C.sub.7F.sub.15CF < (O.sup.Na.sup.+)(CF.sub.2O.sup.Na.sup.+) 506 / / / C.sub.9F.sub.18O.sub.2Na.sub.2 nonanolate-1,2 PERFLUOROALKYL CARBOXYLIC ACIDS Heptafluorobutanoic acid C.sub.3F.sub.7COOH 214 121 17.5 1650 C.sub.4HF.sub.7O.sub.2 Perfluorohexanoic acid C.sub.5F.sub.11COOH 314 157 5.6 1840* C.sub.6HF.sub.11O.sub.2 Perfluorooctanoic acid C.sub.7F.sub.15COOH 414 189 30* 1895* C.sub.8HF.sub.15O.sub.2 PERFLUOROALKYLCARBOXYLATES Sodium perfluoro- C.sub.5F.sub.11COO.sup.Na.sup.+ 338 / / / C.sub.6F.sub.11O.sub.2Na hexanoate PERFLUORO ALKYL CARBOXIMIDIC ACIDS Perfluorohexanoimidic C.sub.5F.sub.11CNHOH 313 / / / C.sub.6H.sub.2F.sub.11NO acid Perfluorooctanoimidic C.sub.7F.sub.15CNHOH 413 / / / C.sub.8H.sub.2F.sub.15NO acid PERFLUOROALKYL CARBOXIMIDATES Disodium perfluoro- C.sub.6F.sub.13CN.sup.Na.sup.+O.sup.Na.sup.+ 407 / / / C.sub.7F.sub.13NONa.sub.2 hexanomidate PERFLUOROETHERALKYL CARBOXYLIC ACIDS Perfluoro-2-oxa-hexanoic C.sub.4F.sub.9OCOOH 280 150* 15* 1670* C.sub.5HF.sub.9O.sub.3 acid Perfluoro-2-oxa- C.sub.5F.sub.11OCOOH 330 170* 5* 1690* C.sub.6HF.sub.11O.sub.3 heptanoic acid PERFLUOROALKYLSULFONIC ACIDS Perfluoropentylsulfonic C.sub.5F.sub.11SO.sub.3H 350 / / / C.sub.5HF.sub.11O.sub.3S acid PERFLUOROALKYL SULFONATES Sodium perfluoropentyl C.sub.5F.sub.11SO.sub.3.sup.Na.sup.+ 372 / / / C.sub.5F.sub.11O.sub.3SNa sulfonate PERFLUOROALKYLSULFURIC ACIDS Perfluoropentanesulfuric C.sub.5F.sub.11OSO.sub.3H 366 / / / C.sub.5HF.sub.11O.sub.4S acid PERFLUOROALKYL SULFATES Sodium perfluoropentyl C.sub.5F.sub.11OSO.sub.3.sup.Na.sup.+ 388 / / / C.sub.5F.sub.11O.sub.4SNa sulfate PERFLUOROALKYLETHER SULFONIC ACIDS Perfluoro-5-oxa- C.sub.4F.sub.9OC.sub.4F.sub.8SO.sub.3H 516 / / / C.sub.8HF.sub.17O.sub.4S nonanesulfonic acid PERFLUOROALKYLETHER SULFONATES Sodium perfluoro-5-oxa- C.sub.4F.sub.9OC.sub.4F.sub.8SO.sub.3.sup.Na.sup.+ 538 / / / C.sub.8F.sub.17O.sub.4SNa nonanesulfonate HYDROFLUORODIALKYLAMMONIUM SALTS Methyl tri-(1H,1H,2H, CH.sub.3N.sup.+Cl.sup. < (((CH.sub.2).sub.2(CF.sub.2).sub.5F)).sub.3 988 / <20 / C.sub.22H.sub.15F.sub.33NCl 2H-perfluoro- heptyl)ammonium chloride Methyl tri-(1H,1H,2H, CH.sub.3N.sup.+Cl.sup. < (((CH.sub.2).sub.3(CF.sub.2).sub.4)F).sub.3 874 / <20 / C.sub.22H.sub.21F.sub.27NCl 2H,3H,3H-perfluoro- heptyl)ammonium chloride Methyl tri-(1H,1H- CH.sub.3N.sup.+Cl.sup. < ((CH.sub.2(CF.sub.2).sub.5F)).sub.3 946 / <20 / C.sub.19H.sub.9F.sub.33NCl perfluorohexyl)ammonium chloride Methyl tri-(1H,1H,2H, CH.sub.3N.sup.+Cl.sup. < (((CH.sub.2).sub.2(CF.sub.2).sub.4F)).sub.3 832 / <20 / C.sub.19H.sub.15F.sub.27NCl 2H-perfluoro- hexyl)ammonium chloride Methyl triperfluoro- CH.sub.3N.sup.+Cl.sup. < (((CF.sub.2).sub.5F)).sub.3 904 / <20 / C.sub.16H.sub.3F.sub.33NCl pentyl ammonium chloride Methyl tri-(1H,1H- CH.sub.3N.sup.+Cl.sup. < ((CH.sub.2(CF.sub.2).sub.4F)).sub.3 790 / <20 / C.sub.16H.sub.9F.sub.27NCl perfluoropentyl)ammonium chloride HYDROFLUOROALKYLIMIDAZOLIUM SALTS 1-Methyl-3-perfluoro- F(CF.sub.2).sub.6.sub.cycle(C.sub.3H.sub.3N.sub.2).sup.+Cl.sup.CH.sub.3 449 / <25 / C.sub.10H.sub.6F.sub.13N.sub.2C.sup. hexyl-imidazolium chloride Perfluoro-1-methyl-3- F(CF.sub.2).sub.5(CH.sub.2).sub.cycle(C.sub.3H.sub.5N.sub.2).sup.+Cl.sup.CH.sub.3 411 / <25 / C.sub.10H.sub.8F.sub.11N.sub.2C.sup. (1H,1H-perfluorohexyl) imidazolium chloride 1-Methyl-3-(1H,1H- F(CF.sub.2).sub.6(CH.sub.2).sub.cycle(C.sub.3H.sub.3N.sub.2).sup.+Cl.sup.CH.sub.3 463 / <25 / C.sub.11H.sub.8F.sub.13N.sub.2Cl perfluoroheptyl) imidazolium chloride 1-Methyl-3-(1H,1H,2H, F(CF.sub.2).sub.5(CH.sub.2).sub.2.sub.cycle(C.sub.3H.sub.3N.sub.2).sup.+Cl.sup.CH.sub.3 425 / <25 / C.sub.11H.sub.10F.sub.11N.sub.2Cl 2H-perfluoroheptyl) imidazolium chloride 1-Methyl-3-(1H,1H,2H, F(CF.sub.2).sub.6(CH.sub.2).sub.2.sub.cycle(C.sub.3H.sub.3N.sub.2).sup.+Cl.sup.CH.sub.3 477 / <25 / C.sub.12H.sub.10F.sub.13N.sub.2Cl 2H-perfluoroctyl) imidazolium chloride 1-Methyl-3-(1H,1H,2H, F(CF.sub.2).sub.5 439 / <25 / C.sub.12H.sub.12 2H,3H,3H-perfluoro- (CH.sub.2).sub.3.sub.cycle(C.sub.3H.sub.3N.sub.2).sup.+Cl.sup.CH.sub.3 F.sub.11N.sub.2Cl ctyl) imidazolium chloride 1-Methyl-3-[2-(2- CF.sub.3(CF.sub.2CF.sub.2O).sub.2.sub.cycle(C.sub.3H.sub.3N.sub.2).sup.+Cl.sup.CH.sub.3 429 / <25 / C.sub.9H.sub.6O.sub.2F.sub.11N.sub.2Cl perfluoromethoxyethoxy)- perfluoroethyl] imidazolium chloride HYDROFLUOROALKYLBORATE SALTS Sodium methyl tri-(1H, CH.sub.3B.sup.Na.sup.+ < (((CH.sub.2).sub.2(CF.sub.2).sub.5F)).sub.3 973 / <20 / C.sub.22H.sub.15F.sub.33BNa 1H,2H,2H-perfluoro- heptyl)borate Sodium methyl tri-(1H, CH.sub.3B.sup.Na.sup.+ < (((CH.sub.2).sub.3(CF.sub.2).sub.4F)).sub.3 859 / <20 / C.sub.22H.sub.21F.sub.27BNa 1H,2H,2H,3H,3H- perfluoroheptyl)borate Sodium methyl tri-(1H, CH.sub.3B.sup.Na.sup.+ < ((CH.sub.2(CF.sub.2).sub.5F)).sub.3 931 / <20 / C.sub.19H.sub.9F.sub.33BNa 1H-perfluorohexyl)borate Sodium methyl tri-(1H, CH.sub.3B.sup.Na.sup.+ < (((CH.sub.2).sub.2(CF.sub.2).sub.4F)).sub.3 817 / <20 / C.sub.19H.sub.15F.sub.27BNa 1H,2H,2H-perfluoro- hexyl)borate Sodium methyl CH.sub.3B.sup.Na.sup.+ < (((CF.sub.2).sub.5F)).sub.3 889 / <20 / C.sub.16H.sub.3F.sub.33BNa triperfluoropentylborate Sodium methyl tri-(1H, CH.sub.3B.sup.Na.sup.+ <((CH.sub.2(CF.sub.2).sub.4F)).sub.3 775 / <20 / C.sub.16H.sub.9F.sub.27BNa 1H-perfluoro- pentyl) borate HYDROFLUORODIALKYLCYCLOPENTADIENE DIBORATE SALTS Sodium 1-methyl-3- F(CF.sub.2).sub.6.sub.cycle(C.sub.3H.sub.3B.sub.2).sup.Na.sup.+CH.sub.3 418 / <25 / C.sub.10H.sub.6F.sub.13B.sub.2Na perfluorohexyl-1,3- dibora-2,4- cyclopentadiene Sodium 1-methyl-3-(1H, F(CF.sub.2).sub.5(CH.sub.2).sub.cycle(C.sub.3H.sub.3B.sub.2).sup.Na.sup.+CH.sub.3 382 / <25 / C.sub.10H.sub.8F.sub.11B.sub.2Na 1H-perfluorohexyl)-1,3- dibora-2,4- cyclopentadiene Sodium l-methyl-3-(1H, F(CF.sub.2).sub.6 432 / <25 / C.sub.11H.sub.8 1H-perfluoroheptyl)-1, (CH.sub.2).sub.cycle(C.sub.3H.sub.3B.sub.2).sup.Na.sup.+CH.sub.3 F.sub.13B.sub.2Na 3-dibora-2,4- cyclopentadiene Sodium 1-methyl-3-(1H, F(CF.sub.2).sub.5(CH.sub.2).sub.2.sub.cycle(C.sub.3H.sub.3B.sub.2).sup.Na.sup.+CH.sub.3 394 / <25 / C.sub.11H.sub.10F.sub.11B.sub.2Na 1H,2H,2H-perfluoro- heptyl)-1,3-dibora-2,4- cyclopentadiene Sodium 1-methyl-3-(1H, F(CF.sub.2).sub.6(CH.sub.2).sub.2.sub.cycle(C.sub.3H.sub.3B.sub.2).sup.Na.sup.+CH.sub.3 446 / <25 / C.sub.12H.sub.10F.sub.13B.sub.2Na 1H,2H,2H-perfluoro- ctyl)-1,3-dibora-2,4- cyclopentadiene Sodium 1-methyl-3-(1H, F(CF.sub.2).sub.5(CH.sub.2).sub.3.sub.cycle(C.sub.3H.sub.3B.sub.2).sup.Na.sup.+CH.sub.3 396 / <25 / C.sub.11H.sub.12F.sub.11B.sub.2Na 1H,2H,2H,3H,3H- perfluoroctyl)-1,3- dibora-2,4- cyclopentadiene Sodium 1-methyl-3-[2-(2 - CF.sub.3(CF.sub.2CF.sub.2O.sub.2.sub.cycle(C.sub.3H.sub.3B.sub.2).sup.Na.sup.+CH.sub.3 398 / <25 / C.sub.9H.sub.6O.sub.2F.sub.11B.sub.2Na perfluoromethoxyethoxy)- perfluoroethyl]-1,3- dibora-2,4- cyclopentadiene *Boiling points, melting points and densities determined by a group analysis process based on more than 600 molecules with known or partially known physical properties.

(12) Other ionic fluorinated surfactants described below may also be used with each group R1, R2, R3, R4 selected independently from the following groups: ((CH.sub.2).sub.2(CF.sub.2).sub.5F), ((CH.sub.2).sub.3 (CF.sub.2).sub.4F), ((CH.sub.2)(CF.sub.2).sub.5F), ((CH.sub.2).sub.2 (CF.sub.2).sub.4F), ((CF.sub.2).sub.5F), ((CH.sub.2(CF.sub.2).sub.4F), ((CF.sub.2).sub.6F), ((CF.sub.2).sub.4F), ((CH.sub.2)(CF.sub.2).sub.6F), ((CH.sub.2).sub.2(CF.sub.2).sub.6F), ((CH.sub.2).sub.3(CF.sub.2).sub.5F), ((CH.sub.2).sub.3(CF.sub.2).sub.6F), ((CF.sub.2CF.sub.2O).sub.2CF.sub.3), and CH.sub.3.

(13) ##STR00001##

EXAMPLE 4: DIRECT CONTACT HEAT EXCHANGER OPERATING AT HIGH TEMPERATURE

(14) FIG. 1 shows a first embodiment of the invention in which the direct contact heat exchanger 1 operates at high temperature. The water to be treated 2, here sea water, is compressed by a liquid pump 3 so that the pressure of the water 2 is higher than the barometric pressure of a column 4 at a lower distributor 5, ensuring dispersion of the water 2 into water droplets of homogenous size over the whole of a lower zone 6 of the column 4. Thus, direct contact heat exchange is carried out in the zone 6 with a counter-current zone between the ascending dispersed water 2 which heats up and a descending continuous fluorinated phase 7 which cools down.

(15) On arriving at an upper portion 8 of the lower zone 6, the water 2, which is less dense than the immiscible hydrophobic fluorinated heat exchange liquid 7, separates naturally while the gases 9 initially dissolved in the water 2 are purged. The hot water 2 is at a sufficiently high pressure for it not to boil.

(16) It is then sent to a crystallization unit 10 to allow any reverse solubility salts to crystallize and to allow them to be evacuated in the solid form. The bottom of said crystallization unit 10 comprises a fluorinated heat exchange liquid 7 on which the salt crystals will be deposited, facilitating evacuation of the precipitated solids.

(17) Said crystallization unit 10 is associated with a clarification section 11 allowing the production of clear salt water 2 returned to a second distributor 12 ensuring homogenous dispersion of the clarified salt water 2 over the whole of an upper zone 13 of the column 4. Heat exchange then occurs between the ascending dispersed phase of salt water 2 that cools down and the descending continuous fluorinated phase 7 that heats up. Thus, at the column head 14, cold clarified salt water 2 is produced to supply a desalination unit 15 with a high degree of conversion for the water.

(18) The direct contact heat exchanger 1 is also provided with a system 16 for circulating heat exchange liquid 7 in a closed loop; it is collected, cold and at maximum pressure, from the bottom of the lower zone 6 for recycling to the top of the upper zone 13 and distributed over the whole section of the column 4. Descending as a continuous phase in this column 4, this heated fluorinated heat exchange liquid 7 reaches a collector 17 located at the interface of the lower zone 6 and the upper zone 13, said collector 17 providing the heat for the column 4 and distribution of the continuous fluorinated phase over the whole section of the lower zone 6.

(19) In an example of an application, consider a direct contact exchanger as described above treating 10000 m.sup.3/day of sea water containing 36 g/liter of salt, which can change from 25 C. to 123 C. by direct contact with a liquid of a continuous fluorinated phase (heat exchange liquid, HEL) of the perfluorononane type (C.sub.9F.sub.20T.sub.bp=123 C., T.sub.mp=16 C.). A summary of the results obtained is given in the two tables below for the lower preheating zone 6 and the upper cooling zone 13 respectively:

(20) TABLE-US-00004 Height of lower zone (TTH) m 2.25 Mean diameter of column m 2.44 Diameter of water droplets mm 2 T.sub.inlet/T.sub.outlet, sea water C. 25/123 P.sub.inlet/P.sub.outlet, sea water Bar abs 2.52/2.19 T bottom/T top exchanger C. 1.0/1.04 T mean, column C. 2.49 Retention time / 17.9% Mean relative velocity cm/sec 17.1 Interface area m.sup.2/m.sup.3 533 Mean coefficient of surface heat kW/m.sup.2/ C. 3.33 exchange Mean coefficient of volume heat kW/m.sup.3/ C. 1774 exchange Relative mass flow rate of HEL / 3.217 Height of lower zone (TTH) m 3.2 Mean diameter of column m 2.46 Diameter of water droplets mm 2 T.sub.inlet/T.sub.outlet, sea water C. 120/30 P.sub.inlet/P.sub.outlet, sea water Bar abs 2/1.5 T bottom/T top exchanger C. 2.9/3.9 T mean, column C. 1.61 Retention time / 18% Mean relative velocity cm/sec 22.1 Interface area m.sup.2/m.sup.3 545 Mean coefficient of surface heat kW/m.sup.2/ C. 3.36 exchange Mean coefficient of volume heat kW/m.sup.3/ C. 1830 exchange Relative mass flow rate of HEL / 3.217 TTH (total tangential height) is the height of the direct contact exchange zones 6 and 13 respectively in FIG. 1.

(21) In this example, a thermal energy consumption of 7.3 kWh/m.sup.3 of salt water was necessary to pretreat the water. Note also that 2 to 5 tonnes per day of salts with reverse solubility had to be evacuated or at least partially re-used to potabilize and re-mineralize the desalinated water.

(22) From a general viewpoint, increasing the degree of conversion of a desalination unit has a direct impact on the desalination costs due to a reduction in the flow rates for treatment and the flow rate of brine produced. Thus, increasing the degree of conversion of water from 50% to 80% means that the flow rate of water to be treated can be reduced by 35% and the flow rate of the brine to be managed by 75%, which means that the unit cost per cubic meter of fresh water produced can be reduced by approximately 15% to 35% by combining the unit described above with current desalination technologies.

EXAMPLE 5: DIRECT CONTACT HEAT EXCHANGER OPERATING AT LOW TEMPERATURE

(23) FIG. 2 shows a second embodiment of the invention in which the direct contact heat exchanger 1 operates at low temperature. The water to be treated 2, here sea water, is compressed by a liquid pump 3 so that the pressure of the water 2 is higher than the barometric pressure of a column 4 at a lower distributor 5, ensuring dispersion of the water 2 into water droplets of homogenous size over the whole lower zone 6 of the column 4. Thus, direct contact heat exchange takes place in the counter-current zone 6 between the ascending dispersed water 2, which cools down, and the descending continuous fluorinated phase 7, which heats up.

(24) On arriving at the upper portion 8 of the lower zone 6, the water 2, being less dense than the immiscible fluorinated heat exchange liquid 7, separates out naturally.

(25) The cold water 2 is then sent to a desalination unit 15 to freeze the water where crystallization and separation of the water to be treated into fresh water and liquid brine is carried out.

(26) The brine or the molten ice crystals from 2 are then sent to a second distributor 12 to produce a homogenous dispersion thereof over the entire upper zone 13 of the column 4. A heat exchange is then carried out between the ascending dispersed phase of fresh water or brine from 2, which heats up, and the descending continuous fluorinated phase 7, which cools down.

(27) At the column head 14, fresh water or brine is recovered as is desired, at ambient temperature.

(28) The direct contact heat exchanger 1 is also provided with a system 16 for circulating the fluorinated heat exchange liquid 7 in a closed loop; it is collected at ambient temperature and at maximum pressure at the bottom of the lower zone 6 for recycling to the top of the upper zone 13 and distributing over the whole section of the column 4. Descending as a continuous phase in said column 4, this cooled fluorinated heat exchange liquid 7 reaches a collector 17 located at the interface of the lower zone 6 and the upper zone 13, said collector 17 ensuring partial thermal cooling of the column 4 and ensuring distribution of the continuous fluorinated phase over the whole section of the lower column 6.

EXAMPLE 6: DIRECT CONTACT HEAT EXCHANGER OPERATING AT HIGH TEMPERATURE WITH A CONTINUOUS FLUORINATED PHASE COMPRISING A HYDROPHOBIC FLUORINATED LIQUID AND AN IONIC SURFACTANT WITH AN ION EXCHANGE HEAD

(29) FIG. 3 illustrates a third embodiment of a unit and a process of the invention in which the direct contact heat and ion exchanger 1 operates at high temperature with a continuous fluorinated phase comprising a hydrophobic fluorinated liquid and an ionic surfactant with an ion exchange head.

(30) The operation of the heat and ion exchanger is identical to that described in Example 4 with just two differences: the continuous fluorinated heat exchange phase 7 comprises a mixture of perfluorononane with 2% of ionic fluorinated surfactant of the sodium hydrofluoroalkylcarboxylate type; and the recycling device is not only provided with a system 16 for closed loop circulation but also with a column 20 for regenerating surfactant using a counter-current of at least a portion of the brine 19 deriving from the desalination system 15.

(31) Thus, once the ion exchange reaction has been carried out in column 4, the continuous fluorinated phase comprising the fluorinated liquid with an ion exchange head is evacuated to the direct contact regeneration column 20 employing an NaCl-rich brine deriving from the desalination unit 15 in order to carry out a reverse ion exchange reaction. The regenerated continuous fluorinated phase is then sent to the top of the upper zone 13 and distributed over the whole section of the column 4.

(32) This third embodiment means that continuous extraction of multivalent cations can be carried out by cation exchange between liquid-liquid phases, which means that saline water can be softened effectively while minimizing the production of crystallized salts to be evacuated. Further, by working at a temperature of more than 80 C., the ion exchange kinetics are improved while at the same time allowing degassing of dissolved gases and thermal destruction of bio-organisms.

(33) By way of example, the table below gives the composition of standard sea water before and after pretreatment of the water, using the system described in FIG. 3.

(34) TABLE-US-00005 Un-treated Pretreated Sea water mg/L mg/L Cations Na.sup.+ 11056 13829 K.sup.+ 418 418 Ca.sup.2+ 418 0 Sr.sup.2+ 14 0 Mg.sup.2+ 1328 66 Anions HCO3.sup. 148 15 SO4.sup.2 2765 2765 Cl.sup. 19811 19811 Br.sup. 68 68 B(OH).sub.3.sup. 25 25 Salinity 36065 37012 Gas 25 C. mg/kg mg/kg O.sub.2 6.8 0 CO.sub.2 45 5 N.sub.2 11.1 0

(35) This system means that a desalination system with a degree of conversion of water much higher than 50% can be used downstream for an overall reduction in desalination costs.

EXAMPLE 7: DIRECT CONTACT HEAT EXCHANGER OPERATING AT HIGH TEMPERATURE WITH A CONTINUOUS FLUORINATED PHASE COMPRISING A HYDROPHOBIC FLUORINATED LIQUID AND A PAIR OF IONIC SURFACTANTS WITH ION EXCHANGE HEADS FOR WATER DESALINATION

(36) FIG. 7 illustrates an embodiment of the unit and process of the invention in which the pretreatment direct contact heat and ion exchanger 1 functions at high temperature with a continuous fluorinated phase comprising a hydrophobic fluorinated liquid, here a hydrofluorocarbon, and a pair of cationic and anionic surfactants, here hydrofluoroalkyl ammonium and hydrofluoroalkyl borate salts.

(37) The operation of the heat and ion exchanger of Example 7 is identical to that described in Example 6. The unit and the process of Example 7 comprise the following additional characteristics.

(38) The continuous fluorinated phase laden with ions 21 is recovered from the column bottom at the lower end 5 of the exchanger 1. The treated water 30 is recovered from the upper end 14 of the exchanger 1. A desalination unit 15 employs a step of treatment of the water 2 by desalination after the step of recovery of treated water 30.

(39) The continuous fluorinated phase recovered 21 from exchanger 1 is introduced to the upper end 22 of the regeneration exchanger 20. Regeneration water is introduced to a lower end 24 under pressure in the form of water droplets in order to carry out ion exchange or even heat exchange as a counter-current between the ascending water droplets of the regeneration water and the descending recovered continuous fluorinated phase 21. The regeneration water comprises a portion 19A of brine 19 and/or desalinated water 23 derived from the desalination unit 15 that is supplied with recovered treated water 30 to the upper end 14 of the exchanger 1. A portion 19B of the brine 19 forms a portion of the water 2 to be treated that is introduced in the region of the lower end 5 of the exchanger 1. The portion 19B is sent to the lower end 5 by means of a pump 27.

(40) The ions of the recovered continuous fluorinated phase 21 are exchanged from the recovered continuous fluorinated phase 21 to the regeneration water 19, 23. The regenerated continuous fluorinated phase 18 that is depleted in ions is collected at the lower end 24 and introduced to the upper end 14 of the pretreatment exchanger by means of a pump 25. It then constitutes the descending fluorinated continuous phase 7 of the exchanger 1. The regeneration water laden with ions 26 is recovered from the upper end 22 of the regeneration exchanger 20.

(41) As an example, the table below gives the composition of standard sea water before (water 2) and after (water 30) pretreatment of the water using the system described in FIG. 7.

(42) TABLE-US-00006 Un-treated Pretreated Sea water mg/L mg/L Cations Na.sup.+ 11056 1658 K.sup.+ 418 12 Ca.sup.2+ 418 0 Sr.sup.2+ 14 0 Mg.sup.2+ 1328 0 Anions HCO3.sup. 148 0 SO4.sup.2 2765 2765 Cl.sup. 19811 2571 Br.sup. 68 0 B(OH).sub.3.sup. 25 0 Salinity 36065 4242 Gas 25 C. mg/kg mg/kg O.sub.2 6.8 0 CO.sub.2 45 5 N.sub.2 11.1 0