EP2142283A2 - Process for enriching a gaseous effluent with acid gases - Google Patents

Abstract

The present invention relates to a process for enriching a gaseous effluent with acid compounds that comprises the following steps: a feed gas and a mixture of at least two liquid phases that are immiscible with each other, including one aqueous phase, are fed into a contacter R1, wherein the feed gas contains at least some acid compounds; predetermined pressure and temperature conditions for the formation of hydrates consisting of water and the acid compounds are established in said contacter; the hydrates are transported in a dispersion in the phase that is immiscible with the aqueous phase by pumping P1 to a flask R2 for dissociation of the hydrates; conditions for dissociation of the hydrates are established in the flask; and the gas generated by the dissociation, which is enriched with acid compounds compared to the feed gas, is discharged.

Description

 PROCESS FOR ENRICHING ACIDIC GASES WITH GASEOUS EFFLUENT

The present invention relates to the field of the separation of acidic compounds such as hydrogen sulfide (H ₂ S) or carbon dioxide (CO ₂ ) contained in a gas flow, for example hydrocarbon natural gas, fumes, or other industrial effluent. The present invention proposes to use the formation of gas hydrates in order to remove the most acidic compounds from the gas stream to enrich in acidic compounds another gaseous effluent while having the possibility of increasing the delivery pressure.

A process for the deacidification of a gas which comprises a step of extracting the acidic compounds contained in the gas to be treated by contacting this gas with the regenerated solvent in an absorber operating at the pressure of the gas to be treated, is followed. a thermal regeneration step of the solvent generally operating at a pressure slightly above atmospheric pressure. This thermal regeneration is generally carried out in a column equipped with a bottom reboiler and an overhead condenser for cooling the acidic compounds released by the regeneration and to recycle the condensates at the top of the regenerator as reflux.

In the previous process, the regeneration of the absorbent solution loaded with acid compounds is expensive in terms of energy consumption, which represents a significant drawback. In addition, acid gas delivered by the regeneration is delivered at the low regeneration pressure, generally between 1 and 5 bar absolute. In case of injection of these acid gases in a tank, a very expensive energy compression is then necessary.

Document US-7128777 discloses a process for separating hydrate formation from acid gases contained in a gas stream. This patent uses water both as a hydrate component and as a transport medium from the hydrate phase to a separator and then to compressors. The dual function of water as a component and transport medium is likely to limit the conversion of water into hydrate and lead to the formation of hydrate blocks that may clog pipes.

The present invention proposes to use a water-immiscible phase as a water dispersion medium and a hydrate phase transport medium, making it possible at the same time to avoid the risks of clogging during the transport of the hydrate slurry. to improve the transfer of the acidic gas to an aqueous phase, and to increase the rate of conversion of water into hydrates. To achieve this grout, one or more amphiphilic additives optionally having the property of lowering the hydrate formation temperature and / or modifying the formation and agglomeration mechanisms are used.

Thus, the present invention relates to a process for enriching acid compounds with a gaseous effluent that comprises the following steps:

a charge gas and a mixture of at least two liquid phases which are immiscible with one another, including an aqueous phase, said feed gas containing at least acid compounds, are introduced into a contactor;

in said contactor, determined pressure and temperature conditions for the formation of hydrates composed of water and of said acidic compounds, es "

said hydrates are transported in dispersion in the immiscible phase in the aqueous phase by pumping to a hydrate dissociation tank,

the conditions for dissociation of the hydrates are established in the said flask; the gas resulting from the dissociation is discharged, the said gas being enriched in acidic compounds with respect to the charge gas,

The pressure of the hydrate dispersion can be increased by a factor between 2 and 200 times the pressure of the feed gas.

To said mixture may be added at least one nonionic, anionic, cationic, or zwitterionic amphiphilic compound having at least the anti-agglomeration property of the hydrates.

The amphiphilic compound may comprise a hydrophilic part and a part having a high affinity with the phase immiscible with the aqueous phase.

The invention will be better understood and its advantages will appear more clearly on reading the following description, in no way limiting, illustrated by the appended figures, among which:

- Figure 1 shows schematically the method according to the invention - Figure 2 shows the test device.

The present invention notably presents the advantages of:

- significant energy gain compared to a conventional process,

the delivery of acidic compounds at high pressure making it possible to avoid, in the case of reinjection of the acidic effluent, a subsequent compression which is very expensive in energy,

- increase of the conversion rate of water into hydrate,

transportability of the hydrate phase improved,

- moderate thermal regeneration levels. The acid gas enrichment process of a gaseous effluent using gas hydrates as an enriching agent comprises three main steps illustrated with the aid of FIG.

(1) a first treatment step for contacting the feed gas containing acidic compounds with a mixture of at least two immiscible liquid phases, at least one of which consists of water, and preferably of amphiphilic molecules . The gas and the liquid phases are brought into contact under conditions of pressure and temperature compatible with the formation of a hydrate phase consisting of acidic compounds and water. This formation can be aided by the addition of one or more suitable additives. This first step allows the sequestration of a large proportion of acid gas in the hydrate phase. The gas hydrate particles thus enriched in acidic compounds are dispersed in the water immiscible liquid and transported in the form of a suspension of solids. The non-hydrated gas is thus depleted of acidic compounds. If it still does not meet the required specifications, it may undergo a second stage of hydrate depletion, or possibly be treated by another gas deacidification process. In FIG. 1, the formation of hydrate is done in the contactor R1 in which the charge gas enters via the pipe 2, after compression of the inlet gas through the pipe 1 with the aid of the compressor K1. The conduit 7 supplies the fluid mixture contactor with two immiscible liquid phases, one of which is water, and preferably with at least one amphiphilic compound. The depleted gas is discharged through line 9, while the hydrate slurry exits the bottom of the contactor via line 3.

(2) a second treatment step aimed at increasing the acid gas partial pressure of the effluent from the previous step. It consists in pumping (P1) the suspension of solids, in particular comprising the hydrate phase at a pressure 2 to 100 times greater than the pressure of the feed gas, and then heating this suspension so as to dissociate the gas enriched hydrate particles. acid into a mixture of the two initial immiscible liquids, and optionally amphiphilic compound, and a gas phase enriched in acidic compounds at high pressure. The gas stream thus obtained has a content and a partial pressure of acid gas from two to one hundred times greater than that of the feed gas. In FIG. 1, the pump P1 pressurises the slurry through line 4 into the dissociation tank R2. The gas enriched in acidic compounds is evacuated via line 5, and optionally compressed by compressor K2 to be injected, for example into an underground reservoir via line 8.

(3) the mixture of liquids resulting from step (2), and comprising predominantly the two immiscible liquids, the amphiphilic compound (s), and / or possibly other additives which can help to formation of a suspension of hydrates in the form of dispersed particles, is expanded / cooled to be returned by the conduits 6 and 7 in the contactor Rl of step 1.

Hydrate formation conditions:

The process for forming / dissociating hydrates to deplete a feed gas, for example CO ₂ , and then to enrich in CO ₂ an effluent resulting from the process, is carried out in a medium comprising water -composing hydrates- and a solvent immiscible with water. To this mixture, we add

_^ Preferably at least one amphiphilic compound which has the property of lowering the formation temperature of the hydrates and / or modify the mechanisms of formation and agglomeration. These modifications can be used particularly for the transport of the hydrate dispersion.

The proportions of the water / solvent mixture may be between 0.5 / 99.5% and 60% by volume, and preferably between 10/90 and 50/50%, and more particularly between 20/80 and 40% by weight. 60% in volume.

The amphiphilic compounds are chemical compounds (monomer or polymer) having at least one hydrophilic or polar chemical group, having a high affinity with the aqueous phase and at least one chemical group having high affinity with the solvent

(commonly referred to as hydrophobic).

When a water phase is contacted with a gas that can form hydrates, a low conversion rate of water into hydrate is observed, mainly due to the low solubility of the gases in the water, and on the other hand, during the formation of these hydrates, a strong agglomeration of the particles between them leading to the formation of solid blocks, plugs or deposits which make the system non-pumpable.

With the water / solvent / amphiphilic compound systems, it is observed that by contacting the feed gas to be treated with these mixtures, the following are obtained:

with a judicious choice of the solvent, a possible preferential solubilization of the acidic compound (s) of the gas to be treated in the solvent,

under conditions of adequate pressure and temperature, a formation of hydrates enriched in acidic compounds under favorable thermodynamic conditions and with a conversion rate of water to high hydrate,

with suitable amphiphilic compounds, non-aggregated hydrate particles are obtained in the solvent. The hydrate block formation is thus avoided and the dispersion of the hydrate particles remains pumpable, the use of a water-immiscible solvent optionally makes it possible to limit the residual water content of the enriched acid compounds released during dissociation of hydrates.

These advantageous properties are found over a very wide range of temperatures and pressures. The amphiphilic compound may be added to said mixture in a proportion of between 0.1 and 10% by weight, and preferably between 0.1 and 5% by weight, relative to the immiscible phase in the aqueous phase. i.e. the solvent.

The solvent used for the process can be chosen from several families: hydrocarbon solvents, silicone type solvents, halogenated or perhalogenated solvents. In the case of hydrocarbon solvents. The solvent may be selected from

aliphatic cuts, for example isoparaffinic sections having a flash point sufficiently high to be compatible with the process according to the invention,

organic solvents such as aromatic cuts or naphthenic cuts may also be used with the same flash point conditions,

- pure products or in mixtures chosen from branched alkanes, cycloalkanes and alkylcycloalkanes, aromatic compounds, alkylaromatic compounds,

The hydrocarbon solvent for the process is characterized in that its flash point is greater than 40 ^° C., and preferably greater than 75 ° C. and more precisely greater than 100 ^° C. Its crystallization point is less than -5 ^° C.

Solvents of silicone type, alone or in mixtures, are chosen for example from:

linear polydimethylsiloxane (PDMS) of the (CH ₃ ) ₃ -SiO - [(CH ₃ ) ₂ -SiO] _n -Si (CH _g ) _{3 type} with n between 1 and 900, corresponding to viscosities at ambient temperature included between 0.1 and 10000 mPa.s,

polydiethylsiloxanes in the same viscosity range,

cyclic polydimethylsiloxanes D ₄ to D ₁₀ and preferentially D ₅ to D ₈ . The unit D represents the dimethylsiloxane monomer unit, poly (trifluoropropyl methyl siloxane).

The halogenated or perhalogenated solvents for the process are chosen from perfluorocarbons (PFCs), hydrofluoroethers (HFE) and perfluoropolyethers (PFPE). The halogenated or perhalogenated solvent for the process is characterized in that its boiling point is greater than or equal to 70 ^° C. under pressure atmospheric and that its viscosity is less than 1 Pa. s at ambient temperature and at atmospheric pressure.

The amphiphilic compounds include a hydrophilic moiety which can be either neutral, anionic, cationic, or even zwitterionic. The part having a high affinity with the solvent (designated as hydrophobic) can be either hydrocarbon-based, or silicone or fluoro-silicone, or still halogenated or perhalogenated.

The hydrocarbon amphiphilic compounds used alone, or in mixtures, to facilitate the formation and / or transport of the hydrates according to the present invention are chosen from nonionic, anionic, cationic or zwitterionic amphiphilic compounds.

The nonionic compounds are characterized in that they contain: a hydrophilic part comprising either alkylene oxide groups, hydroxyl groups or even amino alkylene groups,

a hydrophobic part comprising a hydrocarbon chain derived from an alcohol, a fatty acid, an alkylated derivative of a phenol or a polyolefin, for example derived from isobutene or butene. The bond between the hydrophilic part and the hydrophobic part may, for example be an ether, ester or amide function. This bond can also be obtained by a nitrogen or sulfur atom.

Among the nonionic amphiphilic hydrocarbon compounds, mention may be made of oxyethylated fatty alcohols, alkylphenol alkoxylates, oxyethylated and / or oxypropylated derivatives, sugar ethers, polyol esters, such as glycerol, polyethylene glycol, sorbitol and sorbitan, the mono and diethanol amides, carboxylic acid amides, sulfonic acids or amino acids.

The anionic amphiphilic hydrocarbon compounds are characterized in that they contain one or more functional groups ionizable in the aqueous phase to form negatively charged ions. These anionic groups bringing the surface activity of the molecule. Such functional group is an acidic group ionized by a metal or an amine. The acid may for example be a carboxylic, sulfonic, sulfuric or phosphoric acid.

Among the anionic amphiphilic hydrocarbon compounds, mention may be made of:

carboxylates such as metal soaps, alkaline soaps, or organic soaps (such as N-acyl amino acids, N-acyl sarcosinates, N-acyl glutamates and N-acyl polypeptides),

sulfonates such as alkylbenzenesulphonate (ie alkoxylated alkylbenzene sulphonates), paraffins and olefin sulphonates, ligosulphonates or sulphonuccinic derivatives (such as sulphosuccinates, hemisulfosuccinates, dialkylsulphosuccinates, for example dioctyl sodium sulphosuccinate).

sulphates such as alkyl sulphates, alkyl ether sulphates and phosphates.

The cationic amphiphilic hydrocarbon compounds are characterized in that they contain one or more functional groups ionizable in the aqueous phase to form positively charged ions. These cationic groups bringing the surface activity of the molecule.

Among the cationic hydrocarbon compounds, mention may be made of:

alkylamine salts such as

• alkylamine ethers,

Quaternary ammonium salts such as alkyl trimethylammonium derivatives or tetraalkylammonium derivatives or else alkyl dimethyl benzylammonium derivatives,

• alkoxylated amino alkyl derivatives

sulfonium or phosphonium derivatives, for example tetraalkylphosphonium derivatives. heterocyclic derivatives such as pyridinium, imidazolium, quinolinium, piperidinium or morpholinium derivatives. The zwitterionic hydrocarbon compounds are characterized in that they possess at least two ionizable groups, such that at least one is positively charged and at least one is negatively charged. The groups being chosen from the anionic and cationic groups described above, such as, for example, betaines, alkyl amido betaine derivatives, sulfobetaine, phosphobetaines or even carboxybetaines.

The amphiphilic compounds, comprising a neutral, anionic, cationic or zwitterionic hydrophilic part, can also have a hydrophobic part (defined as having a high affinity with the water-immiscible solvent) silicone or fluoro-silicone. These silicone, oligomeric or polymeric amphiphilic compounds may also be used for the water / organic solvent or water / halogenated or perhalogenated solvent or water / silicone solvent mixtures.

The neutral silicone amphiphilic compounds may be oligomers or copolymers of the PDMS type in which the methyl groups are partially replaced by polyalkylene oxide groups (of the polyethylene oxide, propylene polyoxide or a polyoxide-mixed polymer type). ethylene and propylene) or pyrrolidone such as PDMS / hydroxyalkyleneoxypropylmethylsiloxane derivatives or alternatively alkylmethylsiloxane / hydroxyalkyleneoxypropylmethylsiloxane derivatives. These copolyols obtained by hydrosilylation reaction have reactive hydroxyl end groups. They can therefore be used to carry out ester groups, for example by reacting a fatty acid, or else alkanolamide groups, or even glycoside groups.

Silicone polymers having lateral (hydrophobic) alkyl groups directly attached to the silicon atom can also be modified by reaction with fluoro (hydrophilic) type molecules to form amphiphilic compounds.

The surfactant properties are adjusted with the ratio hydrophilic group / hydrophobic group.

The PDMS copolymers can also be rendered amphiphilic by anionic groups such as phosphate, carboxylate, sulfate or sulphosuccinate groups. These polymers are generally obtained by reaction of acids with the final hydroxyl end groups of alkylene polyoxide side chains of polysiloxane.

The PDMS copolymers can also be rendered amphiphilic by cationic groups such as quaternary ammonium groups, quaternized alkylamido amine groups, or quaternized alkyl alkoxy amine groups or a quaternized amino imidazoline amine. It is possible to use, for example, the PDMS / benzyltrimethylammoniummethylsiloxane copolymer or the halogeno-N-alkyl-N, N-dimethyl- (3-siloxanylpropyl) ammonium derivatives.

The PDMS copolymers may also be rendered amphiphilic by betaine-type groups such as carboxybetaine, an alkyl amido betaine, a phosphobetaine or a sulfobetaine. In this case, the copolymers will comprise a hydrophobic siloxane chain and for example a hydrophilic organobetaine part of general formula: (Me ₃ SiO) (SiMe ₂ O) ₃ (SiMeRO) SiMe ₃

R = (CH _{2) 2} NMe ₃ ⁺ (CH _{2) b} COO; a = 0.10; b = 1.2

The amphiphilic compounds, comprising a neutral, anionic, cationic or zwitterionic hydrophilic part, may also have a hydrophobic part (defined as having a high affinity with the water immiscible solvent) halogenated or perhalogenated. These amphiphilic compounds halogens, oligomers or polymers, can also be used for mixtures water / organic solvent or water / halogenated or perhalogenated solvent or water / silicone solvent.

Halogenated amphiphilic compounds such as, for example, fluorinated compounds may be ionic or nonionic. In particular, we can mention:

the nonionic amphiphilic halogen or perhalogenated compounds such as the compounds corresponding to the general formula Rf (CH ₂ ) (OC ₂ H ₄ ) _n OH, in which Rf is a partially hydrogenated perfluorocarbon or fluorocarbon chain in which n is a whole number at least 1, fluorinated nonionic surfactants of polyoxyethylene-fluoroalkyl ether type,

ionizable amphiphilic compounds for forming anionic compounds, such as perfluorocarboxylic acids, and their salts, or perfluorosulphonic acids and their salts, perfluorophosphate compounds, mono and dicarboxylic acids deriving from perfluoro polyethers, and their salts, mono acids; and disulfonic compounds derived from perfluoro polyethers, and their salts, perfluoro polyether phosphate amphiphilic compounds and perfluoro polyether diphosphate amphiphilic compounds,

amphiphilic halogenated cationic or anionic perfluorinated compounds or those derived from perfluoro polyethers having 1, 2 or 3 hydrophobic side chains, ethoxylated fluoroalcohols, fluorinated sulphonamides or fluorinated carboxamides.

To test the effectiveness of the use of a water-immiscible solvent and of amphiphilic compounds used in the process of the invention, the hydrate formation phase and their transport for a gas mixture containing gas were simulated. methane and CO ₂ in the device described in FIG. 2.

The device comprises a reactor of 1.5 liters of capacity comprising an inlet 11 and an outlet for the gas, a suction 12 and a discharge 13 for the liquid. These liquid inlet and outlet are connected to a circulation loop 14 of 10 meters consisting of tubes of internal diameter equal to 7.7 mm. Tubes of diameter similar to those of the loop ensure the flow of fluids from the loop to the reactor, and vice versa, via a gear pump 15 placed between the two. A sapphire cell C integrated in the circuit allows a visualization of the circulating liquid, and therefore hydrates, if they have formed.

To determine the effectiveness of the additives according to the invention, the liquid or liquids (water or water + solvent + additive) are introduced into the reactor at a volume of 1.4 L. The plant is then pressurized to 7 MPa. using the study gas. Homogenization of the liquids is ensured by their circulation in the loop and the reactor. By following the variations of pressure drop and flow rate, a rapid temperature decrease of 17 ^° C. to 4 ° C. is imposed (temperature below the formation temperature of the hydrates). The temperature is then maintained at this value. The duration of the tests can vary from a few minutes to several hours.

The conversion rate of water to hydrate is calculated and the transportability of the hydrate slurry once formed is studied, when transport is possible. In this case, the pressure drop DP and the flow rate F in the loop are stable.

The following examples which illustrate the invention should not be considered as limiting. Example 1 is given for comparison. Example 1

We operate with a liquid composed of 100% water. The gas used comprises, molar, 90% methane, 2% nitrogen and 8% CO2. The reactor and the loop are pressurized to 7 MPa, then the gas supply is closed. Under these conditions, a pressure drop of 1.45 MPa is observed. As soon as the formation of the hydrates starts, the flow of the pump becomes unstable, the pressure drop between the inlet and the outlet of the loop increases sharply and reaches its maximum value. The mixture is not pumped properly. The complete capping by the hydrates intervenes in about twenty minutes. Hydrates form a block and the circulation of the fluid becomes impossible. The amount of water converted to hydrate is 3%.

EXAMPLE 2 The procedure is as in Comparative Example 1, but with a fluid composed, by volume, of 10% of water and 90% of solvent to which an amphiphilic compound obtained by reaction between a polyisobutenyl succinic anhydride and polyethylene is added. glycol. The amphiphilic compound is added at a concentration of 0.17% by weight relative to the volume of solvent. The weight composition of the solvent is:

for molecules having less than 11 carbon atoms: 20% of paraffins and isoparaffins, 48% of naphthenes, 10% of aromatics;

for molecules with at least 11 carbon atoms: 22% of a mixture of paraffins, isoparaffins, naphthenes and aromatics. Under these conditions, a pressure drop of 1.95 MPa is observed, the pressure in the system reaches the equilibrium curve of the methane hydrates. The flow rate and the pressure drop after hydrate formation in the loop are stable, which means that the hydrate slurry remains pumpable. The conversion rate of water to hydrate reaches 46%. The final composition of the gas mixture is 4.2% CO ₂ , 3% nitrogen and 92.8% methane. Finally, the gas that will be released by dissociation of the hydrate phase will contain 19 mol% of CO ₂ and 81 mol% of methane and no N ₂ . The process has made it possible to enrich the gas resulting from the dissociation of 8 to 19 mol% CO ₂ .

Claims

1) Process for enriching acid compounds with a gaseous effluent, characterized in that it comprises the following steps: a charge gas and a mixture of at least two immiscible liquid phases are introduced into one contactor, an aqueous phase, said feed gas containing at least acidic compounds, is established in said contactor pressure and temperature conditions determined for the formation of hydrates composed of water and said acid compounds, said hydrates are transported in dispersion in the immiscible phase in the aqueous phase by pumping to a hydrate dissociation tank, the conditions for dissociation of the hydrates are established in the said flask, the gas resulting from the dissociation is discharged, the said gas being enriched in acidic compounds with respect to the charge gas, 2) Process according to claim 1, wherein the pressure of the hydrate dispersion is increased in a factor between 2 and 200 times the pressure of the feed gas. 3) Method according to one of claims 1 or 2, wherein is added to said mixture at least one nonionic amphionic compound, anionic, cationic, or zwitterionic, having at least the anti-agglomeration property hydrates. 4) Process according to claim 3, wherein said amphiphilic compound comprises a hydrophilic part and a part having a high affinity with the phase immiscible with the aqueous phase. 5) Method according to one of the preceding claims, wherein the immiscible phase in the aqueous phase is selected from the following group: hydrocarbon solvents, silicone type solvents, halogenated or perhalogenated solvents, and mixtures thereof. 6) Process according to claim 5, wherein the hydrocarbon solvents are chosen from the following group: aliphatic cuts, and in particular isoparaffin cuts, organic solvents such as aromatic cuts or naphthenic cuts, branched alkanes, cycloalkanes and alkylcycloalkanes, aromatic and alkylaromatic compounds, and in which the hydrocarbon solvent has a flash point greater than 40 ^° C., preferably greater than 75 ° C. C, and more precisely above 100 ⁰ C, and a crystallization point below -5 ° C. 7) Process according to claim 5, wherein the silicone type solvents, alone or in mixtures, are chosen from the following group: - polydimethylsiloxane (PDMS) linear of the type (CH _{3) 3} -SiO- [(CH _{g) 2} SiO] _n -Si (CH _{g) 3} with n comprised between 1 and 900, corresponding to the viscosities at room temperature plus between 0.1 and 10000 mPa.s, polydiethylsiloxanes in the same viscosity range, cyclic polydimethylsiloxanes D ₄ to D ₁₀ and preferably D ₅ to D ₈ , unit D represents the dimethylsiloxane monomer unit, poly (trifluoropropyl methyl siloxane). The process according to claim 5, wherein the halogenated or perhalogenated solvents are selected from the following group: perfluorocarbons (PFCs), hydrofluoroethers (HFEs), perfluoropolyethers (PFPEs), and wherein the halogenated or perhalogenated solvent has a boiling point greater than or equal to 70 ⁰ C at atmospheric pressure and a viscosity of less than 1 Pa.s at room temperature and at atmospheric pressure. 9) Method according to one of claims 3 or 4, wherein said nonionic amphiphilic compound comprises: a hydrophilic part comprising alkylene oxide groups, hydroxyl groups or aminoalkylene groups, a hydrophobic part comprising a hydrocarbon chain derived from an alcohol, a fatty acid, an alkylated derivative of a phenol or a polyolefin, and preferably derived from isobutene or butene. The process according to claim 9, wherein said nonionic amphiphilic compound is selected from the following group: oxyethylated fatty alcohols, alkoxylated alkylphenols, oxyethylated and / or oxypropylated derivatives, sugar ethers, polyol esters, such as glycerol, polyethylene glycol, sorbitol and sorbitan, mono and diethanol amides, carboxylic acid amides, sulfonic acids or amino acids. 11. The process as claimed in claim 3, wherein said anionic amphiphilic compound is chosen from the following group: carboxylates, such as metal soaps, alkaline soaps, or organic soaps, such as N-acyl amino acids, N-acyl sarcosinates, N-acyl glutamates and N-acyl polypeptides; sulfonates, such as alkylbenzenesulphonates; , paraffins and olefinsulfonates, ligosulphonates or derivatives sulfonates, such as sulfosuccinates, hemisulfosuccinates, dialkylsulfosuccinates, for example sodium dioctylsulfosuccinate, sulphates, such as alkyl sulphates, alkyl ether sulphates and phosphates. 12) Method according to one of claims 3 or 4, wherein said cationic amphiphilic compound is selected from the following group: the alkylamine salts: alkylamine ethers, Quaternary ammonium salts, such as trimethylammonium alkyl derivatives or tetraalkylammonium derivatives or alkyl dimethyl benzyl ammonium derivatives, Alkoxylated aminoalkyl derivatives, sulphonium or phosphonium derivatives, for example tetraalkylphosphonium derivatives. heterocyclic derivatives, such as pyridinium, imidazolium, quinolinium, piperidinium or morpholinium derivatives. 13) Method according to one of claims 3 or 4, wherein said zwitterionic amphiphilic compound is selected from the following group: betaines, alkyl amido betaines derivatives, sulfobetaine, phosphobetaines, carboxybétaines. 14) Method according to one of claims 3 or 4, wherein said amphiphilic compound comprises a silicone or fluorosilicone portion. 15) Method according to one of claims 3 or 4, wherein said amphiphilic compound comprises a halogenated or perhalogenated part. 16) Method according to one of the preceding claims, wherein the proportions of the water / solvent mixture are respectively between 0.5 / 99.5 and 60/40% by volume, and preferably between 10/90 and 50/50. %, and more precisely between 20/80 and 40/60%. 17) Method according to one of claims 3 or 4, wherein said amphiphilic compound is added to said mixture in a proportion of between 0.1 and 10% by weight, and preferably between 0.1 and 5% by weight, by relative to the immiscible phase in the aqueous phase.