Method for plasma treatment of a mixture of at least two liquid phases for the separation of the two liquid phases of the mixture

Abstract

The invention relates to a method for treating a mixture of at least two liquid phases in order to separate the two liquid phases of the mixture, in which method the mixture is treated with plasma.

Description

Description Title of the invention: METHOD FOR TREATING WITH PLASMA A MIXTURE OF AT LEAST TWO LIQUID PHASES WITH A VIEW TO SEPARATING THE TWO LIQUID PHASES OF THE MIXTURE Technical field

[0001] The present invention relates to a method for treating a mixture of at least two liquid phases with a view to separating the two liquid phases of the mixture, a method for treating waste water containing at least said mixture of at least two liquid phases, a method for treating an oil containing at least said mixture of at least two liquid phases and an installation for treating a mixture of at least two liquid phases. Technological background

[0002] Oil production is almost always accompanied by water production, so a mixture of crude oil and water is recovered at the oil well outlet. This mixture can contain stable emulsions, particularly water-in-oil (W / O), which cause various problems from a production point of view but also during the refining stages. It is therefore necessary to treat these mixtures of crude oil and water in order to break these emulsions.

[0003] It is known to treat these mixtures of crude oil and water by adding at least one chemical demulsifying agent so as to break these emulsions and thus obtain a separation of the crude oil and water phases. The mixture is then generally decanted and then physically separated using a separator.

[0004] In the field of treatment of domestic or industrial wastewater (also called industrial effluents), it is known to treat this water by direct decantation or by flocculation, generally preceded by coagulation, then decantation.

[0005] Coagulation consists of injecting at least one coagulating chemical agent into the water to be treated in order to reduce or cancel the electrical charges carried by the polluting materials present in the water in the form of colloidal particles in suspension, in order to promote their subsequent agglomeration in the form of flocs.

[0006] Flocculation consists of injecting at least one flocculating chemical agent into the water, to which at least one coagulating chemical agent has preferably been added beforehand, so as to form large, easily separable particles or flocs, by agglomeration of the colloidal particles suspended in the water. Flocculation is facilitated by the prior implementation of coagulation. Flocculation can also be facilitated by adding, to the water to be treated upstream or during flocculation, a granular material denser than water or ballast, such as sand, so as to ballast the flocs and thus promote and accelerate their settling. Such flocculation is commonly called ballasted flocculation.

[0007] Purified water is then obtained by separating the flocs suspended in it by decantation.

[0008] To increase the efficiency of wastewater treatment, these coagulation, flocculation, and settling techniques can be used in combination with advanced oxidation techniques. These advanced oxidation techniques include those requiring the addition of Fenton's reagent to the wastewater to be treated, which generates OH* free radicals from hydrogen peroxide in the presence of a transition metal such as iron. The OH* free radicals thus generated react with a wide range of organic pollutants to oxidize them.

[0009] These treatments, which require the addition of varying amounts of demulsifying, coagulating, flocculating or advanced oxidation chemical agents to the wastewater to be treated, may involve relatively long treatment times, particularly due to the reaction speed of these chemical agents. These treatments may, for example, require static treatment steps in basins or tanks.

[0010] Furthermore, current demulsifying, coagulating, flocculating or advanced oxidation chemical agents can pose risks to human health and constitute sources of environmental pollution.

[0011] WO2014 / 172504 discloses a method for separating liquid phases from a water / oil emulsion in which the emulsion is treated by a flow of ions formed by corona discharge in a low current regime (or "glow"), between a grounded collector electrode immersed in the emulsion, and an emitting electrode necessarily kept at a distance from the emulsion and with a potential difference with the emitting electrode equal to or greater than a threshold value and capable of producing such a corona discharge.

[0012] Throughout the text, the term "plasma" designates, in a manner known per se, a state of matter or fourth state of matter (solid, liquid, gas and plasma). The plasma state is distinguished from the gaseous state by the presence of neutral particles (of density no) and charged particles (ions and electrons, of respective densities m and n e ). A gas is transformed into plasma when the kinetic energy of at least some of the particles that compose it becomes greater than the ionization energy of these particles. Unlike a gas which is an electrical insulator, a plasma includes free charges and is an electrical conductor, while remaining electrically neutral from a macroscopic point of view (n, = n e ). This characteristic gives plasmas the property of interacting with electric and / or magnetic fields. There are different classes of plasmas, characterized by the proportion of charged particles they contain, called the degree of ionization (δ). We distinguish between highly ionized plasmas (called hot plasmas, which make up more than 99% of the known matter in the universe) whose degree of ionization approaches unity (6 = 0.1 - 1), and weakly ionized or cold plasmas (5 = 10 7 - 10' 4) which constitute laboratory plasmas. Among cold plasmas, we classically distinguish between thermal plasmas, in which all the particles have the same temperature (thermodynamic equilibrium), and non-equilibrium plasmas, in which the electrons have an average kinetic energy much higher than that of the heavy particles (ions and neutrals). This difference is in most cases generated by the action of an electromagnetic field which accelerates the charged particles, and by the difference in mass between the electrons and the ions. The methods of generating cold plasmas - also called discharge plasmas - vary according to the pressure regime in which they operate, the geometry and the dielectric character of the electrodes on which the difference is applied potential at the origin of the electric field or the frequency of variation of this potential, for example. At atmospheric pressure, a simple way to generate discharges is to adjust the geometry of the electrodes to make them asymmetrical (tip-plane, wire-cylinder, in particular). In the case of a positive discharge, a high voltage is applied to the electrode with a small radius of curvature, inducing a high field in its vicinity. Electron avalanches occur in this region and, under certain conditions, generate a plasma in the form of a luminous crown (hence the name corona discharge). For the same tip-plane electrode geometry, several operating modes of a corona discharge can be observed depending on the voltage applied between these electrodes and characterized by an average current (quantity of electrons circulating between the two electrodes), including: - a “glow” or “onset streamer” mode, characterized by a low average current appearing at low voltage levels, corresponding to the operating mode described in WO2014 / 172504. From a temporal point of view, the current pulses are weak and erratic (no defined frequency of occurrence). We observe a weak luminescence, a sign of the existence of a plasma, only localized in the vicinity of the tip electrode; - a "streamer" mode characterized by, beyond a voltage higher than the voltage leading to the "glow" mode and depending in particular on the radius of curvature of the tip electrode and the tip-plane distance, a net increase in the average current measured. The current pulses are of higher amplitude than in the "glow" mode and appear at a regular frequency. Even if they remain limited in time since their duration is of the order of a hundred nanoseconds (ns), these pulses correspond to the establishment of a non-permanent conduction channel in the interelectrode zone. The "streamer" mode obtained with tip-plane type electrodes is characterized by a luminous zone corresponding to the discharge and extending from the tip of the tip electrode to a point on the plane electrode; - beyond a voltage value applied in "streamer" mode, a rapid transition to an electric arc regime is observed, in which the duration establishment of the discharge in the tip-plane space becomes continuous (permanent short circuit), and which corresponds to very strong heating of the gas. Summary of the invention

[0013] First object of the invention

[0014] A first subject of the invention is a method for treating a mixture of at least two liquid phases with a view to separating the two liquid phases of the mixture, in which the mixture is treated with a plasma.

[0015] The two liquid phases are preferably immiscible.

[0016] One of the two liquid phases may be continuous and the other may be dispersed in the continuous phase.

[0017] One of the two liquid phases can be aqueous and the other can be oily.

[0018] For example, the mixture to be treated comprises a continuous aqueous phase in which an oily phase is dispersed or a continuous oily phase in which an aqueous phase is dispersed.

[0019] The aqueous phase may be water, possibly containing one or more salts in solution, such as for example sodium, magnesium, calcium chlorides.

[0020] The oil phase may be a crude oil; a lubricating oil, including engine oil, transmission oil, hydraulic oil, two-stroke oil, or cutting oil; a vegetable oil, including olive or sunflower oil; or a mixture thereof.

[0021] For example, the mixture to be treated is a mixture of crude oil and water possibly containing one or more salts in solution, such as for example sodium, magnesium and calcium chlorides.

[0022] The volume ratio of the oil phase to the aqueous phase may be between 1:999 and 999:1, preferably between 1:99 and 99:1.

[0023] The mixture to be treated may be an emulsion. In this case, the process is a method of treating an emulsion with a view to breaking it, in which the emulsion is treated with a plasma. The process then makes it possible to destabilize the emulsion and therefore break it so as to obtain a separation of the phases of the emulsion.

[0024] The process can be applied to any industry that has to prepare and / or process mixtures, and in particular emulsions. Examples include the pharmaceutical industry, the fertilizer, plant protection agent and plant protection agent industry, the plastics industry, the construction industry, the paint, varnish and wax industry, the paper and packaging industry, the tannery and leather industry, mining, the nuclear industry, the electrolysis bath and polishing industry, the petroleum and petrochemical industry, the mineral oil additive industry, the adhesive industry, the chemical industry, the photographic industry, industrial laundry and the detergent and washing agent industry.

[0025] In particular, we can cite: - agri-food industries such as, for example, oilseed and fat processing units, industrial delicatessens and curing plants, slaughterhouses or rendering plants, - metallurgical industries such as, for example, industrial manufacturers of cutting tools, which produce grinding sludge, - the mechanical and metalworking industries, which generate oil-rich discharges from machine tools, in particular filtration residues from cutting fluids or from paint booths, - the textile industries, particularly those involved in washing and de-staining wool.

[0026] The emulsion may be a simple emulsion, in particular of the oil-in-water (O / W), water-in-oil (W / O) or oil-in-oil (I.e., a mixture of at least two different immiscible oily phases in which one of the oily phases is continuous and the other is dispersed in the continuous phase) type; a multiple emulsion, in particular of the oil-in-water-in-oil (O / W / O) or water-in-oil-in-water (W / O / W) type; or a mixture thereof.

[0027] The mixture to be treated may further comprise a solid phase dispersed in at least one of the two liquid phases, in particular in the two liquid phases.

[0028] The solid phase may be a plurality of dispersed solid particles, particularly of colloidal size.

[0029] In the case where the mixture to be treated also includes a solid phase, the treatment of the mixture by plasma can allow not only the separation of the two liquid phases of the mixture but also the separation of the solid phase of the mixture.

[0030] The plasma can be generated between at least two electrodes, in particular between at least one ground electrode and at least one high voltage electrode, between which a constant or periodic voltage is applied, in particular having a sinusoidal, Gaussian, triangular, sawtooth, square, rectangular or pulsed shape.

[0031] When a pulsed voltage is applied, the pulse has a width of 1 ns to 10 ps, ​​for example, a width of 50 ns to 600 ns, and / or the pulse has a square, triangular, or Gaussian shape. For example, a periodic pulsed voltage can be used with pulses having a width of 500 ns and a duration of 10 ms between two pulses. It is also possible to use a pulsed voltage with trains of pulses (also called "burst" mode).

[0032] Preferably, a high voltage, positive or negative, is applied to the high voltage electrode(s).

[0033] The constant or periodic voltage can have an amplitude between 10 V and 100 kV, preferably between 1 kV and 10 kV.

[0034] The periodic voltage may have a frequency between 1 Hz and 1 MHz, preferably between 100 Hz and 100 kHz.

[0035] Preferably, the electrodes are arranged so as to expose the mixture to be treated to the plasma.

[0036] More specifically, the electrodes are arranged so as to generate the plasma in contact with or in the mixture to be treated.

[0037] At least one of the electrodes, in particular both electrodes, may not be in contact with the mixture to be treated. For example, the electrode or electrodes may be located in a gas phase located close to the mixture to be treated, in particular a gas phase located above the surface of the mixture. Such a configuration of the electrodes may make it possible to generate the plasma in contact with the mixture to be treated, for example in a gaseous phase located near the mixture, in particular above the surface of the mixture.

[0038] For example, one of the electrodes is not in contact with the mixture to be treated, in particular located in a gaseous phase located close to the mixture, for example a gaseous phase located above the surface of the mixture, and the other electrode is in contact with the mixture to be treated, in particular immersed in the mixture.

[0039] Alternatively, both electrodes are in contact with the mixture to be treated. Such a configuration of the electrodes can make it possible to generate the plasma in the mixture to be treated.

[0040] In one example, both electrodes are immersed in the mixture to be treated.

[0041] In another example, the mixture to be treated is contained in a container formed by walls. In the case where only one of the two electrodes is in contact with the mixture, the latter may be formed by at least one of the walls of the container. In the case where both electrodes are in contact with the mixture, the latter may each be formed by a wall of the container.

[0042] In a particular configuration, the plasma is generated by an array of electrodes, said array of electrodes comprising at least three, four, five, six or more electrodes, including at least one ground electrode and at least one high voltage electrode.

[0043] The electrode array may comprise multiple high-voltage electrodes and / or multiple ground electrodes. For example, the electrode array comprises multiple high-voltage electrodes and one ground electrode; multiple ground electrodes and one high-voltage electrode; or multiple high-voltage electrodes and multiple ground electrodes.

[0044] When the electrode array comprises several high-voltage electrodes, the latter may be powered by a single voltage generator. Alternatively, the high-voltage electrodes are each powered by a voltage generator, these voltage generators being identical or not. Thus, the high-voltage electrodes may each be powered by a voltage, these voltages being identical or not.

[0045] By "identical voltages" we mean voltages having identical characteristics, in particular in terms of voltage type (direct or periodic voltage), amplitude, frequency, signal shape, etc.

[0046] The plasma can be chosen from dielectric barrier discharge (DBD) plasma, corona plasma, and cold plasma jet plasma.

[0047] In the case where the plasma is a dielectric barrier discharge type plasma, either only one of the electrodes is covered with a dielectric material (e.g. the ground electrode or the high voltage electrode), or both electrodes are covered with a dielectric material.

[0048] In the case where the plasma is a corona type plasma, the two electrodes have asymmetric geometries, for example tip / plane, wire / cylinder, etc., so as to allow the creation of a strong electric field in the vicinity of the electrode with a small radius of curvature.

[0049] Cold plasma jet type plasma can be corona type cold plasma jet, dielectric barrier discharge type cold plasma jet, microwave plasma jet or any other type of cold plasma jet.

[0050] In the case where the plasma is a cold corona-type plasma jet, the high-voltage electrode is placed in the center of a tube, such as a capillary tube, for example, this tube being made of quartz. A gas, such as helium for example, circulates in the tube. The plasma is then generated in the tube between the ground electrode and the high-voltage electrode and propagates out of the tube into the surrounding gas, which may or may not be identical to the gas circulating in the tube.

[0051] In a particular configuration, the ground electrode has an annular shape and encloses the tube. This particular configuration of cold plasma jet is then not classified as corona type.

[0052] In the case where the plasma is a cold plasma jet of the dielectric barrier discharge type, the high voltage electrode and the ground electrode have an annular shape and enclose a tube formed of a dielectric wall, such as a capillary formed of a dielectric wall for example, the dielectric wall of the tube being notably made of quartz. A gas, such as helium for example, circulates in the tube. The plasma is then generated in the tube between the ground electrode and the high voltage electrode and propagates out of the tube into the surrounding gas, which may or may not be identical to the gas circulating in the tube.

[0053] The gas used for plasma production may be chosen from a molecular gas, in particular ambient air; a rare gas, in particular argon or helium; and one of their mixtures.

[0054] The method can be applied to a mixture flow. For example, a flow of the mixture is circulated in a treatment zone formed between at least two electrodes between which a constant or periodic voltage is applied, in particular having a sinusoidal, Gaussian, triangular, sawtooth, square, rectangular or pulsed shape. This is particularly advantageous insofar as the method can thus allow a flow of the mixture to be continuously treated with a view to separating the two liquid phases of the mixture. This can also simplify the process by eliminating the need to use treatment basins or tanks.

[0055] The circulation of the mixture flow can be achieved by gravity or using a motorized system, in particular a pump driven by an electric motor, for example a peristaltic pump.

[0056] Alternatively, the mixture to be treated can be sprayed as droplets into the plasma. Treating the droplets of the mixture with the plasma separates the two phases of the droplets and, when the treated droplets are reunited, the two phases remain separate.

[0057] The duration of treatment of the mixture, in particular the emulsion, by the plasma may be between 1 second and 10 hours, preferably between 5 seconds and 60 minutes. Such a duration depends on the mixture to be treated, in particular the type of mixture to be treated, its volume and whether it circulates in flow or not; the type of plasma used; and the configuration of the electrodes, in particular their positioning, their number, and the characteristics of the voltage supplying them (for example type of voltage (direct or periodic voltage), amplitude, frequency, signal shape, etc.).

[0058] The mixture can be heated so as to bring it to a temperature greater than or equal to room temperature, in particular to a temperature ranging from 20°C to 90°C, preferably ranging from 60°C to 90°C, simultaneously with its plasma treatment. This can indeed improve the separation of the two liquid phases of the mixture.

[0059] The mixture can be stirred simultaneously with its plasma treatment. This is particularly advantageous when the process is not applied to a mixed stream. This can improve the separation of the two liquid phases of the mixture.

[0060] The separation of the two liquid phases of the mixture, and possibly of the solid phase of the mixture, is preferably irreversible. This means that if the treated mixture (in particular the treated emulsion) is provided with the same energy as that used to form the initial mixture (in particular the initial emulsion), for example the same stirring, it is not possible to form the initial mixture (in particular the initial emulsion) again. The separation of the two liquid phases, and possibly of the solid phase of the mixture, observed within the plasma-treated mixture is therefore stable.

[0061] The duration of the separation of the two liquid phases of the mixture, in particular the emulsion, and possibly the solid phase of the mixture, can be between 1 second and 10 hours, and is preferably a few seconds. Such a duration depends on the mixture to be treated, in particular the type of mixture to be treated, its volume and whether it circulates in flow or not; the type of plasma used; and the configuration of the electrodes, in particular their positioning, their number, and the characteristics of the voltage supplying them (for example type of voltage (direct or periodic voltage), amplitude, frequency, signal shape, etc.). This is particularly advantageous insofar as the method can thus make it possible to treat large quantities of mixture in short times.

[0062] Preferably, no chemical phase separation agents are added to the mixture, such as demulsifying, coagulating, flocculating, advanced oxidation chemical agents, including bases, acids, salts, especially sodium chloride or metal salts, for example iron or aluminum, hydrogen peroxide, extruded cyclodextrins, etc. Thus, exposure to the plasma alone can separate the two liquid phases of the mixture.

[0063] At least one of the two liquid phases of the mixture, better each of the two liquid phases of the mixture, can be recovered after the separation of the two liquid phases of the mixture.

[0064] The mixture may be a fluid from the petroleum industry, such as a fluid recovered from an oil well or a drilling fluid; a cutting fluid, for example for metalworking; domestic, agricultural or industrial wastewater, such as washing or rinsing water from a stripping, sizing or painting process, wool washing or draining water.

[0065] The process may have characteristics that may vary according to certain parameters, in particular depending on the mixture to be treated, in particular the type of mixture to be treated, its volume and whether it circulates in flow or not; the type of plasma used; and the configuration of the electrodes, in particular their positioning, their number, and the characteristics of the voltage supplying them (for example type of voltage (direct or periodic voltage), amplitude, frequency, signal shape, etc.).

[0066] Second object of the invention

[0067] A second subject of the invention is a method for treating wastewater containing at least one mixture of at least two liquid phases as described above, in which said wastewater is treated by implementing the method as described above.

[0068] The wastewater to be treated may be domestic, agricultural or industrial wastewater, such as wash or rinse water from a stripping, sizing or painting process or wool wash or drain water.

[0069] Preferably, the wastewater to be treated contains at least one aqueous phase and at least one oily phase.

[0070] Preferably, after the treatment of the wastewater by plasma, the aqueous phase is recovered. The aqueous phase then recovered corresponds to purified water.

[0071] Third object of the invention

[0072] A third subject of the invention is a method for treating an oil containing at least one mixture of at least two liquid phases such as described above, wherein said oil is treated by carrying out the process as described above.

[0073] The oil to be treated may be a lubricating oil, including engine oil, transmission oil, hydraulic oil, two-stroke oil or cutting oil; a vegetable oil, including olive or sunflower oil; or a mixture thereof.

[0074] Preferably, the oil to be treated contains at least one aqueous phase and at least one oily phase.

[0075] Fourth object of the invention

[0076] A fourth object of the invention, independently or in combination with the above, is an installation for treating a mixture of at least two liquid phases, in particular for implementing the method as described above, comprising: - a reactor intended to contain or containing the mixture to be treated, the mixture to be treated being able in particular to circulate through the reactor in a continuous flow; - at least two electrodes, in particular at least one ground electrode and at least one high voltage electrode, arranged so as to generate a plasma in contact with or in the mixture to be treated with a view to separating the two liquid phases of the mixture; - at least one voltage generator to power the electrodes.

[0077] The mixture to be treated may be an emulsion. For example, it may be a simple emulsion, in particular of the oil-in-water (O / W), water-in-oil (W / O) or oil-in-oil type; or a multiple emulsion, in particular of the oil-in-water-in-oil (O / W / O) or water-in-oil-in-water (W / O / W) type.

[0078] The reactor can be a tank.

[0079] The reactor can be fed with the mixture to be treated, for example by actuating a valve.

[0080] At least one of the electrodes, in particular both electrodes, may not be in contact with the mixture to be treated. Such a configuration of the electrodes may allow the plasma to be generated in contact with the mixture to be treated.

[0081] Alternatively, both electrodes are in contact with the mixture to be treated. Such a configuration of the electrodes can make it possible to generate the plasma in the mixture to be treated.

[0082] Preferably, the voltage generator is a high voltage generator. In particular, the voltage generator is a continuous or periodic high voltage generator, having in particular a sinusoidal, Gaussian, triangular, sawtooth, square, rectangular or pulse shape.

[0083] According to the first, second, third and fourth objects of the invention, the plasma production mode is a “streamer” type mode in which the current intensity measured between plasma formation electrodes is greater than the current intensity generated by a discharge in “glow” mode.

[0084] According to the first, second, third and fourth objects of the invention, the plasma production mode is a “streamer” type mode in which the current measured between the electrodes is a pulsed current of substantially regular frequency, in particular of regular frequency.

[0085] According to the first, second, third and fourth objects of the invention, the plasma production mode is a “streamer” type mode in which the pulses of the pulsed current have a duration of the order of a hundred nanoseconds.

[0086] According to the first, second, third and fourth objects of the invention, the plasma production mode is a “streamer” type mode in which a non-permanent conduction channel is established in the interelectrode zone.

[0087] According to certain embodiments of the first, second, third and fourth objects of the invention, in which the plasma production mode is a "streamer" type mode obtained with tip-plane type electrodes, a luminous zone corresponding to the discharge extends from the tip of the tip electrode to at least one point of the plane electrode.

[0088] According to the first, second, third and fourth objects of the invention, the production method is of the "streamer" type in which a plasma is generated independently of the polarity of the electrodes. The high voltage electrode may be in contact with said mixture of at least two liquid phases to be separated. The ground electrode may be in contact with said mixture of at least two liquid phases to be separated. The high voltage electrode and the ground electrode may be in contact with said mixture of at least two liquid phases to be separated.

[0089] According to certain embodiments of the invention, the plasma production method is of the "streamer" type in which one of the electrodes is a pointed electrode. Such a "streamer" type production method allows the pointed electrode to be placed (and maintained) in contact with said mixture of at least two liquid phases to be separated during the treatment of said mixture, in particular without harming the efficiency of the process. Brief description of the figures

[0090] The following description with reference to the attached drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented. In the attached figures:

[0091] [fig. 1] Figure 1 is a schematic view representing an example of a method according to the invention in which the mixture is treated with a dielectric barrier discharge type plasma,

[0092] [fig. 2] Figure 2 represents a variant of figure 1,

[0093] [fig. 3] Figure 3 represents a variant of figure 1,

[0094] [fig. 4] Figure 4 represents a variant of figure 3,

[0095] [fig. 5] Figure 5 represents a variant of figure 1,

[0096] [fig. 6] Figure 6 represents a variant of figure 5,

[0097] [fig. 7] Figure 7 represents a variant of figure 1,

[0098] [fig. 8] Figure 8 represents a variant of figure 7,

[0099] [fig. 9] Figure 9 represents a variant of figure 7, [000100] [fig. 10] Figure 10 represents a variant of figure 9, [000101] [fig. 11] Figure 11 represents a variant of figure 7, [000102] [fig. 12] Figure 12 represents a variant of figure 11, [000103] [fig. 13] Figure 13 represents a variant of figure 1, [000104] [fig. 14] Figure 14 represents a variant of figure 2, [000105] [fig. 15] Figure 15 represents a variant of figure 3, [000106] [fig. 16] Figure 16 represents a variant of figure 4, [000107] [fig. 17] Figure 17 represents a variant of figure 5, [000108] [fig. 18] Figure 18 represents a variant of figure 6, [000109] [fig. 19] Figure 19 represents a variant of figure 7, [000110] [fig. 20] Figure 20 represents a variant of figure 8, [000111] [fig. 21] Figure 21 represents a variant of figure 9, [000112] [fig. 22] Figure 22 represents a variant of figure 10, [000113] [fig. 23] Figure 23 represents a variant of figure 11, [000114] [fig. 24] Figure 24 represents a variant of figure 12, [000115] [fig. 25] Figure 25 is a schematic view showing an example of a method according to the invention in which the mixture is treated with a corona-type plasma, [000116] [fig. 26] Figure 26 represents a variant of figure 25, [000117] [fig. 27] Figure 27 represents a variant of figure 25, [000118] [fig. 28] Figure 28 represents a variant of figure 27, [000119] [fig. 29] Figure 29 represents a variant of figure 27, [000120] [fig. 30] Figure 30 represents a variant of figure 29, [000121] [fig. 31] Figure 31 represents a variant of figure 29, [000122] [fig. 32] Figure 32 represents a variant of figure 30, [000123] [fig. 33] Figure 33 is a schematic view showing an example of a method according to the invention in which the mixture is treated with a corona-type cold plasma jet, [000124] [fig. 34] Figure 34 represents a variant of figure 33, [000125] [fig. 35] Figure 35 represents a variant of figure 33, [000126] [fig. 36] Figure 36 represents a variant of figure 33, [000127] [fig. 37] Figure 37 represents a variant of figure 36, [000128] [fig. 38] Figure 38 represents a variant of figure 36, [000129] [fig. 39] Figure 39 is a schematic view showing an example of a method according to the invention in which the mixture is treated by a jet of cold plasma of the dielectric barrier discharge type, [000130] [fig. 40] Figure 40 represents a variant of figure 39, [000131] [fig. 41] Figure 41 represents a variant of figure 39, [000132] [fig. 42] Figure 42 is a schematic view showing an example of a method according to the invention in which a mixture flow is treated, [000133] [fig. 43] Figure 43 represents a variant of figure 42, [000134] [fig. 44] Figure 44 is a schematic view showing another example of a method according to the invention in which a mixture flow is treated, and [000135] [fig. 45] Figure 45 represents a variant of figure 44. Description of embodiment(s) [000136] In the figures, and unless otherwise provided, identical elements will bear the same reference signs. [000137] Figures 1 to 24: Examples of methods according to the invention in which the mixture is treated with a dielectric barrier discharge type plasma. [000138] Figure 1 represents an example of a method according to the invention. In this example, a mixture 1 to be treated comprising at least two liquid phases is contained in a container 2 formed by walls. The mixture 1 to be treated may be an emulsion. In this example, the plasma used to treat the mixture 1 is a dielectric barrier discharge type plasma. In this example, the latter is generated between a high-voltage electrode 3 which is covered with a dielectric material 5 and a ground electrode 4 which is not covered with dielectric material. The high-voltage electrode 3 is not in contact with the mixture 1 to be treated. It is in a gaseous phase located near the mixture 1 to be treated, and in particular in a gaseous phase located above the surface 7 of the mixture 1 to be treated, as illustrated in Figure 1.The ground electrode 4 is in contact with the mixture 1 to be treated, and in particular immersed in the mixture 1 to be treated, as illustrated in figure 1. [000139] Figure 2 represents a variant of Figure 1, in which the ground electrode 4 is formed by at least one wall of the container 2. [000140] Figure 3 represents a variant of Figure 1, in which the ground electrode 4 is covered with a dielectric material 6. [000141] Figure 4 represents a variant of Figure 3, in which the ground electrode 4 is formed by at least one wall of the container 2. The latter is covered with a dielectric material 6. [000142] Figure 5 shows a variant of Figure 1, in which the electrode 3 high voltage is not covered with dielectric material and in which the ground electrode 4 is covered with a dielectric material 6. [000143] Figure 6 shows a variant of Figure 5, in which the electrode 4 of mass is formed by at least one wall of the container 2. The latter is covered with a dielectric material 6. [000144] Figure 7 represents a variant of Figure 1, in which the high voltage electrode 3 covered with a dielectric material 5 is immersed in the mixture 1 to be treated. [000145] Figure 8 represents a variant of Figure 7, in which the ground electrode 4 is formed by at least one wall of the container 2. [000146] Figure 9 represents a variant of Figure 7, in which the ground electrode 4 is covered with a dielectric material 6. [000147] Figure 10 represents a variant of Figure 9, in which the ground electrode 4 is formed by at least one wall of the container 2. The latter is covered with a dielectric material 6. [000148] Figure 11 represents a variant of Figure 7, in which the high voltage electrode 3 is not covered with dielectric material and in which the ground electrode 4 is covered with a dielectric material 6. [000149] Figure 12 represents a variant of figure 11, in which the ground electrode 4 is formed by at least one wall of the container 2. The latter is covered with a dielectric material 6. [000150] Figures 13 to 24 show variants of Figures 1 to 12 respectively, in which the polarities of the electrodes are reversed. [000151] Thus, in Figures 1 to 6, the high-voltage electrode 3 is not in contact with the mixture 1 to be treated and the ground electrode 4 is in contact with the mixture 1 to be treated, whereas in Figures 7 to 12, the high-voltage electrode 3 and the ground electrode 4 are in contact with the mixture 1 to be treated. In Figures 13 to 18, the ground electrode 4 is not in contact with the mixture 1 to be treated and the high-voltage electrode 3 is in contact with the mixture 1 to be treated, whereas in Figures 19 to 24, the ground electrode 4 and the high-voltage electrode 3 are in contact with the mixture 1 to be treated. [000152] Figures 25 to 32: Examples of methods according to the invention in which the mixture is treated with a corona-type plasma [000153] Figure 25 shows another example of a method according to the invention. In this example, a mixture 1 to be treated comprising at least two liquid phases is contained in a container 2 formed by walls. The mixture 1 to be treated may be an emulsion. In this example, the plasma used to treat the mixture 1 is a corona-type plasma. In this example, the latter is generated between a high-voltage electrode 3 having a small radius of curvature, and in particular a tip shape, as illustrated in Figure 25, and a ground electrode 4 having a large radius of curvature, and in particular a plane shape, as illustrated in Figure 25. The high-voltage electrode 3 is not not in contact with the mixture 1 to be treated. It is in a gaseous phase located near the mixture 1 to be treated, and in particular in a gaseous phase located above the surface 7 of the mixture 1 to be treated, as illustrated in Figure 25. The ground electrode 4 is in contact with the mixture 1 to be treated, and in particular immersed in the mixture 1 to be treated, as illustrated in Figure 25. [000154] Figure 26 represents a variant of Figure 25, in which the ground electrode 4 is formed by at least one wall of the container 2. [000155] Figure 27 represents a variant of Figure 25, in which the high voltage electrode 3 is immersed in the mixture 1 to be treated. [000156] Figure 28 represents a variant of Figure 27, in which the ground electrode 4 is formed by at least one wall of the container 2. [000157] Figure 29 represents a variant of Figure 27, in which the ground electrode 4 has a small radius of curvature, and in particular a point shape, while the high voltage electrode 3 has a large radius of curvature, and in particular a plane shape. [000158] Figure 30 represents a variant of Figure 29, in which the high voltage electrode 3 is formed by at least one wall of the container 2. [000159] Figure 31 represents a variant of Figure 29, in which the ground electrode 4 is not in contact with the mixture 1 to be treated. It is in a gaseous phase located close to the mixture 1 to be treated, and in particular in a gaseous phase located above the surface 7 of the mixture 1 to be treated, as illustrated in Figure 31. [000160] Figure 32 represents a variant of Figure 30, in which the ground electrode 4 is not in contact with the mixture 1 to be treated. It is in a gaseous phase located close to the mixture 1 to be treated, and in particular in a gaseous phase located above the surface 7 of the mixture 1 to be treated, as illustrated in Figure 32. [000161] Thus, in Figures 25 and 26, the high voltage electrode 3 is not in contact with the mixture 1 to be treated and the ground electrode 4 is in contact with the mixture 1 to be treated, whereas in Figures 27 to 30, the high voltage electrode 3 and the ground electrode 4 are in contact with the mixture 1 to be treated. In Figures 31 and 32, the ground electrode 4 is not in contact with the mixture 1 to be treated and high voltage electrode 3 is in contact with mixture 1 to be treated. [000162] Figures 33 to 38: Examples of methods according to the invention in which the mixture is treated by a corona-type cold plasma jet [000163] Figure 33 shows another example of a method according to the invention. In this example, a mixture 1 to be treated comprising at least two liquid phases is contained in a container 2 formed by walls. The mixture 1 to be treated may be an emulsion. In this example, the plasma used to treat the mixture 1 is a corona-type cold plasma jet. In this example, the high-voltage electrode 3 is placed in the center of a tube 8, such as a capillary for example, this tube 8 being made in particular of quartz. A gas, such as helium for example, circulates in the tube 8. The high-voltage electrode 3 is not in contact with the mixture 1 to be treated. It is in a gaseous phase located close to the mixture 1 to be treated, and in particular in a gaseous phase located above the surface 7 of the mixture 1 to be treated, as illustrated in Figure 33.The ground electrode 4 is in contact with the mixture 1 to be treated, and in particular immersed in the mixture 1 to be treated, as illustrated in figure 33. The plasma is then generated in the tube 8 between the ground electrode 4 and the high voltage electrode 3 and propagates at the outlet of the tube 8 in the surrounding gas, which may or may not be identical to the gas circulating in the tube 8. [000164] Figure 34 represents a variant of figure 33, in which the ground electrode 4 is formed by at least one wall of the container 2. [000165] Figure 35 represents a variant of figure 33, in which the ground electrode 4 has an annular shape and encloses the tube 8. This variant of cold plasma jet illustrated in figure 35 is then not qualified as corona type. [000166] Figure 36 represents a variant of Figure 33, in which the high voltage electrode 3 placed in the center of the tube 8 is immersed in the mixture 1 to be treated. [000167] Figure 37 represents a variant of figure 36, in which the ground electrode 4 is formed by at least one wall of the container 2. [000168] Figure 38 represents a variant of Figure 36, in which the ground electrode 4 has an annular shape and encloses the tube 8. This cold plasma jet variant illustrated in Figure 38 is then not qualified as corona type. [000169] Figures 39 to 41: Examples of methods according to the invention in which the mixture is treated by a jet of cold plasma of the dielectric barrier discharge type [000170] Figure 39 shows another example of a method according to the invention. In this example, a mixture 1 to be treated comprising at least two liquid phases is contained in a container 2 formed by walls. The mixture 1 to be treated may be an emulsion. In this example, the plasma used to treat the mixture 1 is a cold plasma jet of the dielectric barrier discharge type. In this example, the high-voltage electrode 3 has an annular shape and encloses a tube 8 formed of a dielectric wall, such as a capillary formed of a dielectric wall for example, the dielectric wall of the tube 8 being in particular made of quartz. A gas, such as helium for example, circulates in the tube 8. The high-voltage electrode 3 is not in contact with the mixture 1 to be treated. It is in a gaseous phase located near the mixture 1 to be treated, and in particular in a gaseous phase located above the surface 7 of the mixture 1 to be treated, as illustrated in Figure 39. The ground electrode 4 has an annular shape and encloses the tube 8. It is also in a gaseous phase located near the mixture 1 to be treated, and in particular in a gaseous phase located above the surface 7 of the mixture 1 to be treated, as illustrated in Figure 39. The plasma is then generated in the tube 8 between the ground electrode 4 and the high-voltage electrode 3 and propagates at the outlet of the tube 8 into the surrounding gas, which may or may not be identical to the gas circulating in the tube 8. [000171] Figure 40 represents a variant of figure 39, in which the ground electrode 4 is immersed in the mixture 1 to be treated. [000172] Figure 41 represents a variant of figure 39, in which the high voltage electrode 3 and the ground electrode 4 are immersed in the mixture 1 to be treated. [000173] Figures 42 to 45: Examples of methods according to the invention in which a mixture flow is treated [000174] Figure 42 represents an example of a method according to the invention in which a flow of a mixture 1 comprising at least two liquid phases is treated, and being in particular an emulsion. The latter is introduced into a tank 2 formed by walls via a feed 10 of mixture 1 opening into the tank 2. A corona-type plasma is generated between a high-voltage electrode 3 having a small radius of curvature, and in particular a point shape, as illustrated in Figure 42, and a ground electrode 4 having a large radius of curvature, and in particular a plane shape, as illustrated in Figure 42. The high-voltage electrode 3 is immersed in the mixture 1 to be treated and the ground electrode 4 is formed by at least one wall of the tank 2. The mixture 1 is treated by the generated corona plasma and obtains a separation of the two liquid phases of the mixture. The phase with the lowest density is recovered by an outlet 11 provided in the upper part of the tank 2 and the phase with the highest density is recovered by an outlet 12 provided in the lower part of the tank 2. [000175] Figure 43 represents a variant of Figure 42 in which several high-voltage electrodes 3 are present, in particular three high-voltage electrodes 3, as illustrated in Figure 43. The number of high-voltage electrodes 3 may be greater than three. We then speak here of an electrode network comprising three high-voltage electrodes 3 and a ground electrode 4. [000176] Figure 44 represents a variant of Figure 42 in which the tank 2 is inclined so as to be able to treat a film of mixture 1 which flows within the tank 2. This variant illustrated in Figure 44 thus makes it possible to treat a lower height of mixture 1 compared to Figures 42 and 43. [000177] Figure 45 represents a variant of Figure 44 in which several high-voltage electrodes 3 are present, in particular three high-voltage electrodes 3, as illustrated in Figure 45. The number of high-voltage electrodes 3 may be greater than three. We then speak here of an electrode network comprising three high-voltage electrodes 3 and a ground electrode 4. [000178] In figures 42 to 45, the high voltage electrodes 3 may not be in contact with the flow of the mixture 1 to be treated. They may be in a gaseous phase located close to the flow of the mixture 1 to be treated, and in particular in a gaseous phase located above the surface 7 of the flow of the mixture 1 to be treated. [000179] In Figures 43 and 45, the high voltage electrodes 3 of the electrode network can be powered by a single voltage generator. alternatively, the high-voltage electrodes 3 are each powered by a voltage generator, these voltage generators being identical or not. Thus, the high-voltage electrodes 3 can each be powered by a voltage, these voltages being able to be identical or not.

Claims

Claims

1. A method of treating a mixture of at least two liquid phases with a view to separating the two liquid phases of the mixture, in which the mixture is treated with a plasma.

2. A method according to claim 1, wherein the two liquid phases are immiscible.

3. A method according to claim 1 or 2, wherein one of the two liquid phases is continuous and the other is dispersed in the continuous phase.

4. A method according to any preceding claim, wherein one of the two liquid phases is aqueous and the other is oily.

5. A method according to any preceding claim, wherein the mixture is an emulsion.

6. A method according to claim 5, wherein the emulsion is a simple emulsion, in particular of the oil-in-water (O / W), water-in-oil (W / O) or oil-in-oil type; a multiple emulsion, in particular of the oil-in-water-in-oil (O / W / O) or water-in-oil-in-water (W / O / W) type; or a mixture thereof.

7. A method according to any one of the preceding claims, wherein the mixture comprises a solid phase dispersed in at least one of the two liquid phases, in particular in both liquid phases.

8. The method of claim 7, wherein the treatment of the mixture with plasma allows not only the separation of the two liquid phases of the mixture but also the separation of the solid phase of the mixture.

9. A method according to any preceding claim, wherein a stream of the mixture is treated.

10. A method according to any preceding claim, wherein the plasma treatment time is between 1 second and 10 hours, preferably between 5 seconds and 60 minutes.

11. Method according to any one of the preceding claims, in which the mixture is heated so as to bring it to a temperature ranging from 20°C to 90°C, preferably ranging from 60°C to 90°C, simultaneously with its treatment by the plasma.

12. A method according to any preceding claim, wherein the mixture is stirred simultaneously with its plasma treatment.

13. Method according to any one of the preceding claims, in which the plasma is generated between at least two electrodes, in particular between at least one ground electrode and at least one high voltage electrode, between which a constant or periodic voltage is applied, in particular having a sinusoidal, Gaussian, triangular, sawtooth, square, rectangular or pulsed shape.

14. Method according to claim 13, wherein the constant or periodic voltage has an amplitude between 10 V and 100 kV, preferably between 1 kV and 10 kV.

15. A method according to claim 13 or 14, wherein the periodic voltage has a frequency between 1 Hz and 1 MHz, preferably between 100 Hz and 100 kHz.

16. Method according to any one of claims 13 to 15, in which at least one of the electrodes, in particular the two electrodes, are not in contact with the mixture to be treated.

17. A method according to any one of claims 13 to 15, wherein both electrodes are in contact with the mixture to be treated.

18. A method according to any preceding claim, wherein the plasma is selected from dielectric barrier discharge type plasma, corona type plasma and cold plasma jet type plasma.

19. A method according to any one of the preceding claims, wherein the gas used for the production of the plasma is chosen from a molecular gas, in particular ambient air; a rare gas, in particular argon or helium; and one of their mixtures.

20. A method according to any preceding claim, wherein the separation of the two liquid phases of the mixture, and optionally of the solid phase of the mixture, is irreversible.

21. A method according to any one of the preceding claims, wherein the duration of the separation of the two liquid phases of the mixture, and optionally of the solid phase of the mixture, is between 1 second and 10 hours.

22. A method according to any preceding claim, wherein no demulsifying, coagulating, flocculating or advanced oxidation chemical agent is added to the mixture.

23. Method according to any one of the preceding claims, in which at least one of the two liquid phases of the mixture is recovered, better each of the two liquid phases of the mixture, after the separation of the two liquid phases of the mixture.

24. A method according to any preceding claim, wherein the mixture is a fluid from the petroleum industry, such as a fluid recovered from an oil well or a drilling fluid; a cutting fluid, for example for metalworking; domestic, agricultural or industrial wastewater, such as washing or rinsing water from a stripping, sizing or painting process, wool washing or draining water.

25. A method of treating wastewater containing at least one mixture of at least two liquid phases, in which said wastewater is treated by implementing the method according to any one of claims 1 to 24.

26. A method according to claim 25, wherein the wastewater to be treated is domestic, agricultural or industrial wastewater, such as wash or rinse water from a stripping, sizing or painting process or wool wash or drain water.

27. ​​A method of treating an oil containing at least one mixture of at least two liquid phases, in which said oil is treated by implementing the method according to any one of claims 1 to Tl

28. A method according to claim 27, wherein the oil to be treated is a lubricating oil, in particular an engine oil, a transmission oil, a hydraulic oil, a two-stroke oil or a cutting oil; a vegetable oil, in particular an olive or sunflower oil; or a mixture thereof.

29. Installation for treating a mixture of at least two liquid phases for implementing the method according to any one of claims 1 to 24, waste water for implementing the method according to claim 25 or 26, or an oil for implementing the method according to claim 27 or 28, comprising: - a reactor intended to contain or containing the mixture, wastewater or oil to be treated, the mixture, wastewater or oil to be treated being able in particular to circulate through the reactor in a continuous flow; - at least two electrodes, in particular at least one ground electrode and at least one high-voltage electrode, arranged so as to generate a plasma in contact with or in the mixture, wastewater or oil to be treated with a view to separating the two liquid phases of the mixture, wastewater or oil; - at least one voltage generator to power the electrodes.

Images