FR3108603A1 - Device for treating a liquid by plasma and corresponding implementation method - Google Patents

Abstract

The invention relates to a device for treating a liquid by plasma comprising a reaction chamber (2) comprising at least one supply electrode (12) associated with at least one counter-electrode (13), at least one layer of dielectric material separating said electrodes. According to the invention, the chamber comprises at the level of the electrodes at least one channel (6) which is arranged on a slope in the chamber so that the liquid flows in the said channel while being subjected to a plasma generated by the supply of the feed electrode. The invention also relates to a method using such a device. FIGURE FROM THE ABRIDGE: [Fig. 1]

Description

Device for treatment of a liquid by plasma and corresponding method of implementation

BACKGROUND OF THE INVENTION

In the food industry, the water used to hydrate plants is often enriched with chemical compounds to facilitate plant growth, decontaminate them, improve their resistance, etc. Enriched water can also be used to eliminate plants. (in the case of weeds).

Thus, various industrial processes have allowed the development of aqueous phytosanitary products that can fulfill different functions such as those of fertilizing agent or pesticide.

Although this approach is still widely used in the field of agriculture and gardening, it is not very ecological due to the nature of the by-products generated as well as their persistence. In the long term, it can lead to the pollution of soils and groundwater and thus contribute to the imbalance or even the irreversible degradation of ecosystems (insects, microbiota, etc.) and food chains. As a result, this approach is becoming less and less compatible with the expectations of consumers and decision-makers whose awareness encourages them to be more demanding in terms of environmental protection.

Consequently, disruptive technological approaches are being investigated in order to treat water in a more natural way. For several years, a new type of treatment consists of activating water by plasma. By activation, we mean the mechanism by which a process makes it possible to modify the physico-chemical properties of water.

For this, the water is placed in a container and is subjected to a plasma source. This source generates the plasma thanks to a voltage applied between two electrodes. This results in an electric field which, if it is intense enough, makes it possible to partially ionize the gas located in the inter-electrode space of the plasma source. Plasma can be brought into contact with water and can modify its properties. After treatment, the water sees its chemical composition enriched in compounds such as nitrites, nitrates or hydrogen peroxide.

Thus, this treatment approach is more natural than the aforementioned industrial processes because plasma does not generate harmful by-products.

OBJECT OF THE INVENTION

An object of the invention is to propose a device for treating a liquid by plasma which is of less bulky construction.

An object of the invention is also to propose a method for treating a liquid by plasma implemented using such a device.

With a view to achieving this object, there is proposed, according to the invention, a device for treating a liquid by plasma comprising a reaction chamber comprising at least one supply electrode associated with at least one counter-electrode, at the least one layer of dielectric material separating said electrodes.

According to the invention, the chamber comprises at the level of the electrodes at least one channel arranged on a slope in the chamber so that the liquid flows in said channel while being subjected to a plasma generated by the supply of the electrode of power supply when it is in operation.

In this way, the invention cleverly takes advantage of gravity to allow the liquid to flow naturally through the chamber, while being exposed to plasma throughout the descent.

This allows continuous plasma activation of the liquid while having a small footprint chamber.

In addition, by varying the value of the slope, it is possible to modulate the residence time of the liquid in the device and therefore the duration of the interaction between the liquid and the plasma. This makes it possible to weight the increase in the concentration of chemical compounds resulting from the activation of the liquid by the plasma.

Accordingly, the invention allows effective activation of the liquid.

For the present application the terms "high", "low", "vertical" ... must be understood according to the position of the device in service and in particular of the chamber when it is positioned on a support or the ground to be able to be used. .

By “slope”, we mean that the channel is neither horizontal nor vertical.

Optionally, the channel is formed by one of the electrodes and/or the layer of dielectric material.

Optionally, the counter-electrode is intended to be formed by the layer of liquid.

Optionally the chamber comprises a body in which the channel is arranged, the layer of dielectric material being formed directly by the material of the body.

Optionally the channel has a U-section with a flat bottom.

Optionally the channel is shaped like a helix.

Optionally the channel is shaped as an inclined plate.

Optionally, the chamber comprises a body, the channel, the electrodes and the layer of dielectric material being arranged so that, in service, the liquid is treated by plasma all along its flow in said body.

Optionally, the chamber includes means for injecting at least one carrier gas into the channel.

Optionally the carrier gas is a rare gas.

Optionally, the device further comprises at least one control unit for controlling an electrical supply of the supply electrode as a function of data transmitted by at least one sensor of the device.

Optionally at least the surface of the flow channel is hydrophilic.

Optionally the channel is in communication with the ambient air.

Optionally the chamber comprises a body, the channel being formed in said body.

The invention also relates to a method for treating a liquid by plasma, the method being implemented using the device as mentioned above and comprising the steps of:

• Power the supply electrode electrically,
• Introduce the liquid into the chamber,
• Collect the liquid after plasma treatment in the chamber.

Optionally, water or an aqueous liquid is chosen as the liquid.

Other characteristics and advantages of the invention will become apparent on reading the following description of particular non-limiting embodiments of the invention.

The invention will be better understood in the light of the following description with reference to the appended figures, including:

FIG. 1 is a schematic view of a device for activating a liquid by plasma according to a first embodiment of the invention;

Figure 2 is a partial view of the device illustrated in Figure 1, showing a sectional view of a reaction chamber delimited by a body of said device;

Figure 3 is an enlarged view of Figure 2 schematically illustrating plasma liquid activation in use;

FIG. 4 is a diagram comparing the growth of plants when they are watered with water treated by the device illustrated in FIG. 1 and by treatments of the prior art;

FIG. 5 is a schematic view of part of a device for activating a liquid by plasma according to a second embodiment of the invention;

FIG. 6 is a schematic view of part of a device for activating a liquid by plasma according to a third embodiment of the invention;

FIG. 7 is a schematic view of part of a device for activating a liquid by plasma according to a fourth embodiment of the invention;

FIG. 8a is a schematic view of part of a device for activating a liquid by plasma according to a fifth embodiment of the invention;

FIG. 8b is a schematic view of part of a device for activating a liquid by plasma according to a sixth embodiment of the invention;

FIG. 8c is a schematic view of part of a plasma liquid activation device according to a seventh embodiment of the invention;

FIG. 8d is a schematic view of part of a device for activating a liquid by plasma according to an eighth embodiment of the invention;

FIG. 8e is a schematic view of part of a device for activating a liquid by plasma according to a ninth embodiment of the invention;

FIG. 8f is a schematic view of part of a device for activating a liquid by plasma according to a tenth embodiment of the invention;

Fig. 8g is a schematic view of part of a plasma liquid activation device according to an eleventh embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a device for activating a liquid by plasma, generally designated at 1, according to a first embodiment of the invention is here intended to activate water by plasma.

Furthermore, the device 1 is in the present case applied to the agri-food sector, the water treated by the device being used to water seeds or plants (either by the ground or by spraying) in order to accelerate their emergence. dormancy, increase their germination rate, promote plant growth and make them more resistant to pathogens.

The device 1 comprises in particular a reaction chamber 2 which will now be described with reference to FIGS. 2 and 3.

Chamber 2 comprises a body 3 shaped like a cylinder extending along the Z axis. In the service position of chamber 2, body 3 extends vertically.

Optionally, the body 3 comprises a through cylindrical cavity 4, which is thus coaxial with the Z axis. This cavity 4 makes it possible, for example, to insert the chamber 2 along a bar or a rod in order to stabilize the chamber 2 vertically.

The body 3 is for example manufactured by printing in three dimensions.

In particular, chamber 2 is made of PLA (for Polylactic Acid).

Preferably, a spiral passage 5 is provided in the body 3. This passage 5 extends from the ceiling of the body 3 to the floor of the body 3 by winding around the axis X to form a spiral of regular turns that is, a spiral of constant radius and inclination. Thus, the turns are regular and spaced by the same vertical distance. The passage 5 therefore forms a continuous slope between the ceiling of the body 3 and its floor.

The passage 5 is also arranged so that the turns open onto the outside of the body 3 on one of their sides (the turns do not, however, open here into the cavity 4 on the other of their side).

Consequently the turns are visible from the outside of the body 3 which is therefore generally shaped like a screw.

The body 3 also comprises a channel 6 for the flow of water arranged in the body 3 between the ceiling and the floor of the body 3.

This channel 6 thus extends from the ceiling of the body 3 to the floor of the body 3 by winding around the Z axis to form a helix. The helix here is regular and therefore has identical turns spaced the same distance apart.

The propeller emerges at a first end in the ceiling which forms an inlet interface 7 of the body 3 for the injection of water into the body 3 and at a second end in the floor which forms an outlet interface 8 of the body 3 for the recovery of water once its activation has been ensured in body 3.

Channel 6 therefore extends on a continuous slope between the ceiling of body 3 and its floor.

The slope of channel 6 has an angle between 0 and 90 degrees with respect to the horizontal plane (the values 0 and 90 being of course excluded), preferably between 10 and 85 degrees and preferably between 15 and 80 degrees (the horizontal plane being defined by the normal to this plane which is the Z axis).

Preferably, channel 6 is arranged in passage 5 and is thus shaped to follow the spiral of said passage 5. The spiral of passage 5 and the helix of channel 6 are therefore identical in terms of slope.

On the other hand, along the vertical axis X, the turns of the passage 5 are wider than those of the channel 6. Preferably, the turns of the channel 6 are arranged on those of the passage 5 so as to be centered on those of the passage 5 (the centering being considered in the radial direction of the body 3). Channel 6 is therefore not found at the outer periphery of body 3 but inside body 3.

The section of channel 6 is identical over its entire length. The section of the channel 6 is preferably U-shaped with a flat bottom (according to a section plane including the Z axis and as illustrated in FIGS. 2 and 3).

Thus the channel 6 comprises a flat base 9 from which extend two lateral flanks 10 substantially perpendicular to the base 9. The flat base 9 is horizontal and the two lateral flanks 10 substantially vertical. The two side flanks 10 are otherwise identical. The two side flanks 10 themselves have a rectangular or square section.

In the present case, the channel 6 and the passage 5 are of the same piece, moreover forming the body 3. The base 9 of the channel 6 is therefore also here a part of the upper face of the spiral formed by the passage 5.

The particular shape of the channel 6 (with a flat bottom 9 and lateral sides 10 substantially perpendicular to the flat bottom 9) makes it possible to have a layer of water whose spatial distribution in the channel 6 is relatively uniform during its flow in the body 3 which favors the treatment of water by plasma.

It is noted that the channel 6 is not partitioned here since it does not have a vertex which would extend between the two lateral flanks 10 and that the lateral flanks 10 do not extend to the underside of the turn upper part of passage 5. Channel 6 is therefore open in passage 5.

Above channel 6 thus extends a volume of gas. More particularly here the volume of gas extends in a cavity 11 delimited by the passage 5 and the channel 6.

The cavity has a generally rectangular section (to the side flanks 10 near).

Note, however, that the cavity 11 is open to the outside.

Consequently, the cavity 11 communicates with the ambient air.

Optionally, a carrier gas is also injected into the body 3 which will fill said cavity 11 and mix with the ambient air. The carrier gas is a noble gas, preferably helium or even argon or else neon. much less than the inter-turn distance.

According to a first variant, the channel 6 is partitioned (for example it has a top which extends between the two lateral flanks 10 and/or the lateral flanks 10 extend to the underside of the upper turn of the passage 5) . Channel 6 is then not open in passage 5.

This makes it possible to partition the plasma in service.

Above channel 6 there is always a volume of gas. More particularly here the volume of gas extends in a cavity 11 delimited by the passage 5 and the channel 6 (if the channel has no vertex) or by the channel 6 alone (if it has a vertex).

It is noted that the cavity 11 is then always open to the outside. Consequently, the cavity 11 communicates with the ambient air.

According to a second variant, the cavity 11 is not open to the outside, isolating the channel 6 from the ambient air by extension (the channel 6 can then also be itself partitioned or not).

Whether in the initial embodiment or in one of the two variants, a carrier gas is preferably injected into the body 3 which will fill the cavity 11. The carrier gas is a noble gas, preferably helium or even argon or neon.

The carrier gas is for example injected into a single zone of the body 3 or else into several zones of said body. In the present case, the carrier gas is injected into a single zone which is part of the inlet interface 7 of the body 3.

The channel 6 thus described allows a continuous flow of water along the channel 6 and therefore here a continuous flow of water throughout the body 3.

This optimizes the circulation of water in the body 3, in particular avoiding problems of clogging of the liquid. Plasma treatment is improved.

The water can thus only descend into body 3 by flowing along channel 6.

Indeed, as already indicated, the channel 6 forms a continuous slope in the body 3 between a high point and a low point of the body 3 (respectively the ceiling and the floor of the body 3). Channel 6 is thus globally inclined with respect to the horizontal.

In addition, channel 6 is flat-bottomed and extends only in a circular fashion. The channel 6 thus does not include any raised or recessed element apart from one or more access orifices to at least one channel downstream or upstream. Channel 6 also does not draw a sine wave. The water thus flows as evenly as possible in the body 3.

Preferably, channel 6 is chosen so that it has hydrophilic properties. The channel 6 is therefore in an intrinsically hydrophilic material and/or in a material which has undergone a treatment with a view to making it hydrophilic or more hydrophilic (for example by nebulization or deposition of a film covering the surface of the material to obtain a hydrophilic or super-hydrophilic surface).

This facilitates the flow of water in channel 6 allowing for an optimized plasma treatment.

In the present case, the channel 6 is in one piece with the rest of the body 3 which is made of PLA, a material inherently having hydrophilic properties.

Optionally, the channel 6 and/or the body 3 can be subjected to an additional treatment, as mentioned above, making it possible to improve the natural hydrophilic properties of the base material (for example by depositing a super-hydrophilic coating thereon by nebulization).

Furthermore, chamber 2 comprises at least two electrodes.

In the present case, chamber 2 comprises only two electrodes: a supply electrode 12 intended to be electrically supplied in service and a counter-electrode 13 connected to a reference potential such as earth or forming a floating potential.

Preferably, the counter-electrode 13 is here formed directly by the water flowing in the body 3 and intended to be treated by plasma.

This makes it possible to have a chamber 2 of simplified structure.

Preferably, the water layer is connected to a reference potential such as earth.

The chamber 2 comprises for example at least one wire of electrically conductive material arranged in the channel 6 so as to be in contact with the water when it circulates in the chamber 2 (for example arranged on the base of the channel), the wire electrically conductive material being grounded.

The supply electrode 12 is for its part arranged inside the body 3 and more particularly inside the turns of the passage 5. The supply electrode 12 thus extends from the ceiling of the body 3 to 'on the floor of the body 3 by winding around the Z axis to form a spiral which follows that of the passage 5 but also the helix of the channel 6 so that the supply electrode 12 is above the channel 6. Typically the supply electrode 12 is shaped like a lamella facilitating its integration into the body 3 in the form of a spiral.

Thus the spiral structure of supply electrode 12 and that of channel 6 are therefore identical in terms of thread pitch (and therefore slope).

In addition, the turns of supply electrode 12 are substantially of the same width as that of channel 6. Preferably, supply electrode 12 is arranged in body 3 so as to be centered (in a radial direction) in the turns of the passage 5. The supply electrode 12 is thus substantially at the same level (in a radial direction) as the channel 6 along the entire length of the channel 6. There is thus successively from top to bottom (for each turn considered) the supply electrode 12, the channel 6 and therefore the water therein in service, and the counter-electrode 13.

Consequently, the supply electrode 12 is not in contact with the exterior of the body 3 nor with the cavity 11. In addition, the supply electrode 12 is neither in contact with water, nor with the cavity 11. in contact with the counter-electrode 11. The distance separating the supply electrode 12 from the counter-electrode 11 is for example less than 15 millimeters.

Chamber 2 also comprises at least one layer of dielectric material separating supply electrode 12 from counter-electrode 13.

The plasma generated in chamber 2 is therefore produced by dielectric barrier discharge with or without carrier gas. The generated plasma is a cold plasma allowing to carry out a wet treatment.

Preferably, the body 3 is itself made of a dielectric material (this is the case, for example, if the body 3 is made of PLA as optionally proposed above).

In this way, since the supply electrode 12 is embedded in the turns of the passage 5, a layer of the body 3 forming one of its turns will naturally separate the supply electrode 12 from the cavity 11 in which is present the channel 6 and therefore the layer of water: said layer of the body 3 will therefore directly form the layer of dielectric material separating the two electrodes 12 and 13.

This makes it possible to simplify the structure of chamber 2.

Because the body 3 is in one piece here, the layer of dielectric material extends in the present case between the two electrodes 12 and 13 all along the channel but also frames the two electrodes 12 and 13 laterally. In particular, the two side flanks 10 of the channel 5 are also formed by the layer of dielectric material.

Chamber 2 thus described therefore has a reduced size thanks to the clever arrangement of the various elements in a helix but also in layers. Indeed, the various elements (electrodes 12, 13, dielectric layer, channel 6) all extend one above the other.

The fact that the water plays the role of the counter-electrode 13 and that the body 3 itself plays the role of the dielectric layer, contribute to reducing the volume of the chamber 2.

Bedroom 2 is also of a simple structure.

Furthermore, the helical shape of the channel and that corresponding to the supply electrode 12 makes it possible to ensure continuous treatment of the water throughout the body 3 between the inlet interface 7 and the outlet interface 8 .

The water can thus be treated for a relatively long time in chamber 2.

As visible in Figure 1, device 1 optionally includes other elements than chamber 2.

Preferably, the device 1 comprises a circuit 20 for distributing the water after it has passed through the chamber 2.

For example, the distribution circuit 20 comprises a reservoir 21 for storing water activated by plasma, the reservoir 21 being connected to the outlet interface 8 of the body 3.

Optionally, the distribution circuit 20 also comprises a pump assembly 22 sucking up the water present in the storage tank 21 to ensure distribution of the treated water to plants for example.

In the present case, the device 1 also comprises a water inlet circuit 23 connected to the inlet interface 7. Preferably, the water inlet circuit 23 comprises a valve 24 for regulating the flow of the water penetrating into the body 3. Said valve 24 has a variable opening making it possible to close the water inlet but also to modulate the water inlet flow.

Typically, device 1 also includes a system 25 for powering device 1 in general and chamber 2 in particular. The system 25 thus comprises here a high voltage generator making it possible to supply the supply electrode 12. The supply electrode 12 is therefore a high voltage electrode.

The generator is chosen here to generate an alternating voltage and/or a pulsed voltage intended for the supply electrode 12.

Device 1 can be shaped to generate a voltage at supply electrode 12 of at least one kilovolt at a frequency of at least a few hertz, but preferably of the order of kilohertz and preferentially of megahertz.

Preferably, the device 1 comprises a control unit 26 of the device 1. In particular here, the control unit 26 controls the electrical supply system 25 to supply or not supply the chamber 2 (and therefore cause the generation or not of plasma ) and whether or not to intensify the plasma treatment. Preferably, the control unit 26 also controls the water supply circuit 23 and in particular the valve 24.

It is thus possible to modulate the treatment carried out in the chamber 2 using the water inlet flow rate and the electrical characteristics of the electrical supply of the supply electrode 12 (in particular the voltage at its terminals and the frequency electrical signal).

Preferably, device 1 comprises at least one control sensor in connection with control unit 26 to control device 1.

Optionally, device 1 includes at least one electrical sensor 27 to control the electrical supply to supply electrode 12 and at least one chemical sensor 28 to estimate the characteristics of the water leaving chamber 2.

In operation, the control unit 26 opens the valve 24 to allow water to flow into the chamber 2 and then controls the system 25 to supply the supply electrode 12. Of course the control unit 26 opens the valve 24 so that the water cannot overflow from the channel 6 which is not here partitioned above.

The supply electrode 12 brought to high voltage will generate a plasma in the cavity 11 filled with gas (mixture here of ambient air and carrier gas), cavity 11 separating the layer of dielectric material from the water, the supply electrode 12 being arranged above the free surface of the water while being covered by the layer of dielectric material. The plasma will then interact with the water which will allow it to be activated.

The plasma treatment is advantageously carried out along the entire length of the channel 6, which allows continuous treatment of the water over the entire height of the body 3.

Water activation is therefore very effective.

In particular, it is not necessary to make the water make several trips in chamber 2 to treat it correctly: a single pass is sufficient.

If one wishes to treat the water longer, one can for example increase the height of the body 3, and therefore the length of the channel 6, so that the water remains in contact with the plasma longer. You can also change the slope of channel 6.

It is noted that by modifying the treatment parameters of the device 1, the control unit 26 can adapt the treatment of the water according to the intended application. For example, depending on the value of the voltage applied to the supply electrode 12, the properties of the water will be modified differently by the plasma.

The inventors have been able to observe through tests the effectiveness of the water treatment by the device 1 described above.

Coral lentils were thus watered with standard tap water, tap water treated by the aforementioned device so that the water remained 15 minutes in the chamber of said device, tap water enriched chemically with H ₂ O ₂ , tap water chemically enriched with NO ₃ ^- , tap water chemically enriched with NO ₂ ^- and heated tap water.

Figure 4 shows the average length of coral lentils after six days of watering.

It is thus visible that the device 1 described makes it possible to facilitate the growth of coral lentils, unlike untreated water or water treated by means of the prior art.

In addition, the table below makes it possible to compare the content of two chemical compounds, which are hydrogen peroxide (H ₂ O ₂ ) and nitrite ions (NO ₂ ^– ), of water treated by the device described and by plasma treatments of the prior art:

Molar concentration of H ₂ O ₂ (in micromoles per litre) H ₂ O ₂ production efficiency (nanomoles per second) Molar NO ₂ concentration (in micromoles per litre) Nitrite (NO ₂ ^– ) production efficiency (nanomoles per second) Volume of water treated (milliliters) Processing time (in seconds) Device described 120 240 20 40 10 5 “PlasmaJet” device 500 1.66 20 0.07 0.2 60 “PlasmaJet 2” device 50 0.13 - - 0.3 120 Device called "Multipoint" and described in the article https://www.sciencedirect.com/science/article/abs/pii/S0043135417310308?via%3Dihub 400 3.33 180 15 50 600 “COST Reference Microplasma Jet” device 80 0.13 - - 0.1 60

In this table, the production efficiency corresponds to the product of the molar concentration of the chemical species formed by the volume of liquid treated, then divided by the total duration of exposure of the liquid to the plasma. Efficiency can therefore be expressed in nanomoles per second.

It can thus be seen that in much less time than the other methods and for a large volume, the aforementioned device 1 makes it possible to very well enrich the water with these two components which are nitrites and H ₂ O ₂ .

A second embodiment will now be described with reference to Figure 5.

This second embodiment is identical to the first embodiment except that the body, the channel and the supply electrode are shaped differently.

The body 3 is thus shaped as a rectangular parallelepiped and no longer as a cylinder. The body 3 however always extends longitudinally along the Z axis.

Body 3 no longer has a passage 5 here. However, channel 6 is still provided in body 3.

Furthermore, whereas in the first embodiment the channel 6 was wound in a helix, in the second embodiment the channel 6 is shaped in a zig-zag.

Typically the channel 6 is provided in the body 3 so as to extend vertically, each branch of the zig-zag being arranged directly above the next branch of the zig-zag.

Each branch of the zig-zag therefore forms a continuous slope between the ceiling of body 3 and its floor so that the water can only descend along channel 6 in body 3. The slope is not entirely continuous, however. due to the sometimes vertical passage of water between two consecutive branches of the zig-zag.

The channel 6 however allows water to flow between a high point and a low point of the body 3 (respectively the ceiling and the floor of the body 3).

More precisely here, the channel 6 consists of a succession of rectilinear plates 30a, 30b (of which only a part is referenced here) arranged one below the other, each plate 30a, 30b being inclined downwards but in such a way that two successive plates 30a, 30b are oriented in opposite directions. So if a tray 30b extends from right to left, the tray 30a below it extends from left to right and vice versa. Each plate 30a, 30b thus forms one of the branches of the zig-zag defining channel 6.

Preferably, the different plates 30a and 30b are identical to each other.

Thus, the various plates 30a, 30b are inclined at the same angle θ (in absolute value) with respect to the horizontal. On the other hand, for two adjacent plates 30a, 30b, one is oriented by the angle θ and the other by the angle – θ.

Channel 6 is arranged so that the angle θ is between 0 and 90 degrees (the values 0 and 90 being of course excluded), preferably between 10 and 85 degrees and preferably between 15 and 80 degrees.

The plates here have a rectangular or square cross-section so that the layer of water circulating in channel 6 is of uniform thickness over the entire width of channel 6.

Note that here channel 6 is partitioned. Of course, the water must not then fill all of channel 6, otherwise there would be no gas in channel 6 to form plasma.

The channel 6 thus described allows a continuous flow of water along the channel 6 and therefore here a continuous flow of water throughout the body 3.

This optimizes the circulation of water in the body 3, in particular avoiding problems of clogging of the liquid. Plasma treatment is improved.

The water can thus only descend into body 3 by flowing along channel 6.

Indeed, as already indicated, channel 6 forms a slope in the body between a high point and a low point of the body (respectively the ceiling and the floor of the body).

In addition, the channel 6 has a flat bottom and extends only by a succession of inclined rectilinear plates 30a, 30b. The channel 6 thus does not include any raised or recessed element apart from one or more access orifices to at least one channel downstream or upstream. Channel 6 also does not draw a sine wave. The water thus flows relatively evenly through the body 3.

Furthermore, chamber 2 here comprises several supply electrodes.

In particular, chamber 2 has as many supply electrodes 12 (only a part is referenced here) as channel 6 has plates. Each supply electrode 12 is thus arranged inside the body 3 so as to overhang the associated plate and therefore the water located there in service and therefore the counter-electrode.

Typically each feed electrode 12 is shaped as a plate.

Consequently, each supply electrode 12 is not in contact with the cavity 11. In addition, each supply electrode 12 is not in contact with the water and therefore is not in contact with the counter- electrode. The distance separating each supply electrode 12 from the counter-electrode is for example less than 15 millimeters.

The other characteristics of the first embodiment are also applicable here, such as the fact that the body 3 directly forms the layer of dielectric material and that the water layer directly forms the counter-electrode.

It is also possible to assimilate each plate of the second embodiment to a channel, the various channels jointly form a tube which here has an overall zig-zag shape. In this case each channel forms a continuous slope between the ceiling of the body 3 and its floor so that the water can only descend along the channel 6 in the body 3. The slope is however not entirely continuous in the tubing due to the sometimes vertical passage of water between two consecutive branches of the zig-zag.

A third embodiment will now be described with reference to Figure 6.

While in the first embodiment and the second embodiment the chamber 2 had a single channel 6, in the third embodiment the chamber 2 has at least two flow channels and optionally at least three flow channels 6 , 31, 32.

Channels 6, 31, 32 are here arranged in parallel.

Channels 6, 31, 32 are here identical to each other.

As regards the supply to chamber 2, device 1 may comprise several water inlet circuits in order to associate a water inlet circuit with each channel 6, 31, 32.

Alternatively, the device 1 comprises a single water supply circuit to the chamber 2=.

In Figure 6, the chamber 2 is then equipped with a distributor for the distribution of water between the different channels 6, 31, 32, the distributor being connected on the one hand to the water supply circuit and to on the other hand to the various channels 6, 31, 32. The distributor comprises for example as many flow control valves, which can be controlled independently of that of the other valves, as there are channels 6, 31, 32.

The distributor can also be combined with several water supply circuits.

Similarly, with regard to the exit from chamber 2, device 1 may include several water distribution circuits in order to associate a water distribution circuit with each channel 6, 31, 32.

As a variant, the device 1 comprises a single circuit for distributing water to the chamber 2. The latter is then equipped with a collector for the recovery of the water leaving the various channels 6, 31, 32, the collector being connected on the one hand to the water distribution circuit and on the other hand to the various channels 6, 31, 32.

The collector can also be combined with several water distribution circuits.

The different characteristics of the first embodiment and of the second embodiment are applicable here in particular in terms of channel shapes.

A fourth embodiment will now be described with reference to Figure 7.

Whereas in the third embodiment the channels are arranged in parallel, in the fourth embodiment the channels are arranged in series.

The configuration of the fourth embodiment is here similar to that of the second embodiment except that two successive channels are not directly connected together so as to form a zig-zag but are connected together via a tunnel 34 transfer.

The tunnels 34 are simple necks which are not associated with a supply electrode. There is therefore no plasma activation of the water between two successive channels. The tunnels 34 preferably extend straight along the Z axis. The tunnels 34 therefore extend vertically. The tunnels 34 preferably have a section similar to that of the channels 6, 31, 32, 33 to facilitate a homogeneous flow of water. The tunnels 34 are preferably identical to one another.

The various channels 6, 31, 32, 33 and the tunnels 34 together form a pipe 35 which here has an overall stepped shape.

Each channel 6, 31, 32, 33 therefore forms a continuous slope between the ceiling of the body 3 and its floor so that the water can only descend along the pipe 35 in the body 3. The slope is not however, not continuous throughout the tubing 35 due to vertical passages of water at the level of the tunnels 34. The tubing 35 however allows water to flow between a high point and a low point of the body 3 (respectively the ceiling and the floor of the body 3).

Furthermore each channel 6, 31, 32, 33 is flat bottomed. No channel 6, 31, 32, 33 thus comprises any raised or recessed element apart from one or more access orifices to at least one channel downstream or upstream. No channel 6, 31, 32, 33 also draws a sine wave.

The other characteristics of the first embodiment are also applicable here, such as the fact that the body 3 directly forms the dielectric layer and that the water layer directly forms the counter-electrode 13. It is also possible to combine the first embodiment and the fourth embodiment by serializing several curved channels separated by tunnels.

The other characteristics of the second embodiment are also applicable here, in particular the fact that the body 3 comprises as many supply electrodes 12 as there are channels or even only the channels 6, 31, 32, 33 are identical to each other. It is also possible to have the various channels 6, 31, 32, 33 inclined at the same angle θ (in absolute value) with respect to the horizontal. On the other hand, for two adjacent channels 6, 31, 32, 33 one is oriented by the angle θ and the other by the angle – θ. Each channel is arranged so that the angle θ is between 0 and 90 degrees (the values 0 and 90 being of course excluded), preferably between 10 and 85 degrees and preferably between 15 and 80 degrees.

The other characteristics of the third embodiment are also applicable here, in particular the fact that the body 3 comprises several channels in parallel in addition to the succession of channels in series described.

It is noted that if in this fourth embodiment the tunnels are formed by bottlenecks, according to a variant, the tunnels may be immaterial. Thus, if the various channels are all carried by the same vertical structure, the device will be able to overcome the bottleneck between two successive channels: the water will naturally flow alone by gravity from one channel to another. With reference to the figures 8a to 8g, other embodiments will now be described.

Unlike the previously described embodiments, the counter-electrode is formed by at least one additional element added to chamber 2.

As can be seen in FIG. 8a, if we look at a cross-sectional view of the channel, it comprises successively from top to bottom a first electrode 41 (supply or a counter-electrode), a layer of dielectric material 40 ( formed or not by the body 3 carrying the electrodes 41, 42), the cavity 43 filled with gas, the water layer 44 and the second electrode 42 (respectively the counter-electrode or the supply electrode).

However, other arrangements are possible.

According to FIG. 8e, instead of being associated with the first electrode 41, the layer of dielectric material 40 is associated with the second electrode 42. It thus extends under the water layer 44 and no longer above it. 'She.

Moreover, in the fifth embodiment illustrated in FIG. 8a, the cavity 43 is open.

However, other arrangements are possible.

Thus, with reference to FIG. 8b, one of the electrodes has two side walls which extend as far as the layer of dielectric material 40 so as to partition the channel and therefore the cavity 43.

This may be the layer of dielectric material 40 which comprises two side walls which extend up to the first electrode 41 so as to partition off the channel (as illustrated in FIG. 8d) or which comprises two side walls which extend up to 'to the second electrode 42 so as to partition the channel (as illustrated in Figure 8c).

Furthermore, this may be the counter-electrode or the layer of dielectric material which directly forms the channel.

However, other arrangements are possible. Another element can thus form the flow channel.

Thus, as represented in FIG. 8e, it is a second layer of dielectric material 45 which forms the channel. Chamber 2 thus comprises a first electrode 41 associated with first layer of dielectric material 40 and a second electrode 42 arranged in the bottom of the channel formed by second layer of dielectric material 45.

Furthermore and as already indicated in the present application, the channel can extend straight (as visible in Figure 8a) or curved (as visible in Figure 8g).

Many configurations are also possible.

It should be noted, however, that the water must not be able to reach the supply electrode either by being in contact with it or by projection of droplets on said electrode. It is therefore preferable to cover the zone of the supply electrode facing the water with a layer of dielectric material. It will also be ensured that the supply electrode and the counter-electrode are separated by the layer of dielectric material and that the water is in contact with the gas of the cavity to be able to be treated by plasma.

We will also seek to have a flow in the channel as regular as possible. We will preferably seek to have a flow of the smallest possible thickness.

In the various options described in the present application, the device makes it possible to treat large volumes of liquid thanks to the continuous treatment of the liquid along the channels (avoiding a necessary recirculation of the water in the reaction chamber) and a parallel channels if necessary. The device can provide variable treated liquid flow rates.

In the various options described in this application, the device proves to be energy efficient. In addition, it is easy to manufacture and install. In particular, if the liquid to be treated is water, the device can simply be connected to the water supply network already in place in the establishment where the device is installed. In addition, the device is also easy to use.

In the various options described in this application, the device is reliable thanks to the presence of sensors which make it possible to control the production of chemical compounds in the treated liquid (and/or other parameters such as its pH and its conductivity) and adjust the device settings accordingly.

In the various options described in the present application, the device is easily adjustable to the intended application by acting in particular on the inclination of the slope and the dimensions of the channel or channels, the properties of the surfaces in contact with the liquid, the characteristics of the electric field supplying the supply electrode(s). Plasma treatment can thus be adapted to the intended application and/or the liquid used.

Of course, the invention is not limited to the embodiments described and variations can be made thereto without departing from the scope of the invention as defined by the claims.

In particular, although here the invention is applied to the treatment of water, the invention may allow the activation of another liquid whether it is non-viscous or viscous (the liquid must however be sufficiently fluid to be able to flow into the channel). Of course, the liquid may be formed from a single component (such as water for example) or be formed from a mixture of several components (for example an aqueous mixture) even when located at the inlet of the device.

Furthermore, although here the invention is implemented to facilitate the growth of plants, the invention may be implemented in other applications in the agri-food field such as, for example, facilitating the germination of seeds. The plasma-treated liquid can thus be used just as well to water the seeds as the plants (by watering the soil or directly the leaves or roots of the plants typically for hydroponics).

Furthermore, although here the invention is implemented for an agro-food purpose, the invention may be implemented in any other field such as, for example, the medical field and in particular, although not exclusively in oncology, the field of water pollution. The plasma-treated liquid can be used to reduce tumor volume and more generally provide targeted treatment. It is further noted that plasma-treated liquids are relatively stable over time, which facilitates their use in the medical field.

It is of course possible to combine the different embodiments described. The different configurations of FIGS. 8a to 8h can thus also be combined with the other embodiments.

The device may comprise several reaction chambers arranged in series and/or in parallel. In the case of a device comprising at least two chambers arranged in series one after the other, it will be possible to arrange a reservoir between these two chambers.

If the device comprises elements other than the reaction chamber, these may be different from what has been indicated. Thus, the device may not include a distribution circuit. The chamber supply system may not be part of the device. The device may not include a control unit and/or control sensors. The control unit may be different from what has been indicated and in particular control a different number of elements of the device than what has been indicated: for example the control unit can control the pumping system and/or a valve device output. The sensors may be different from what has been indicated and control, for example, the flow rate entering or leaving the chamber, the intensity of the electric field created, etc. The data generated by the sensor(s) may be used directly to control the device and/or may be stored for later analysis. The device may thus comprise at least one electric sensor for measuring the intensity of the electric current passing through the supply electrode and/or the voltage of the electric current across the terminals of the supply electrode and/or the electric power consumed by the feed electrode. As a variant or in addition, the device may comprise at least one chemical sensor for measuring the pH of the liquid, its conductivity, its concentration in particular chemical compounds (H ₂ O ₂ , nitrite, etc.). As a variant or in addition, the device may comprise a thermal sensor for measuring the temperature of the liquid or of the plasma. As a variant or in addition, the device may comprise a sensor for measuring the pH of the liquid and/or a sensor for measuring the electrical conductivity of the liquid.

The control unit can modify the operating parameters of the device to adapt the treatment of the liquid to the intended application. For example, the control unit may comprise a database integrating the operating parameters adapted to the intended application (duration of treatment, electrical power supplied, etc.), the user having only to select the application targeted (for example the type of plant to be watered) and the device will thus treat the liquid in an optimized manner.

The chamber may include one or more liquid inlets and one or more liquid outlets. It will also be possible to have intermediate inlets and/or outlets of the liquid along the channel (for example to recover liquids with concentrations of chemical compounds of different values).

Depending on the manufacturing process, the channel may be dug in the passage, extruded, manufactured together with the body (in the case of three-dimensional printing)…

The channel may be attached to the body and not be formed in said body so as to be in one piece with it. The channel may thus be in a material other than the body. Thus, if the body has a passage, the channel can be attached to the passage and not come from the same part as it.

The channel may have a different section than what has been indicated. The base may be slightly hollow and not flat.

Preferably, the cavity in which the gas intended to form the plasma flow is arranged will have a generally rectangular cross-section (within the side flanks of the channel).

The channel may not be identical over its entire length.

In particular, the channel may comprise different sections of different shapes. At least one section may for example be shaped according to an embodiment different from that associated with the other sections.

The channel may also, although it may be in one piece, have different slopes all along the body. The liquid flowing through the channel will therefore have different flow velocities depending on the slope of the channel throughout the body.

The chamber may include a different number of channels and/or supply electrodes and/or counter-electrodes and/or layers of dielectric material than indicated. In particular, the chamber may comprise a first layer of dielectric material associated with the supply electrode and a second layer of dielectric material associated with the counter-electrode. It will however be preferred to have a single layer of dielectric material separating said two electrodes to limit energy losses.

Although here the channel extends along a substantially vertical axis, said axis may be inclined as long as the channel forms a slope for the liquid.

If there are transfer tunnels, these may not all be vertical. Some or all of the transfer tunnels may thus be inclined (ie be neither vertical nor horizontal).

The transfer tunnels may be tangible (for example consist of walls forming a bottleneck) or intangible (for example be defined by the distance separating two successive channels).

As already indicated, the flow channel can be open or closed. The flow channel may possibly be hermetic in order to be able to very finely control the gas present in the flow channel.

In addition, whether the flow channel is closed or open, the space filled with gas present in the flow channel and in contact with the free surface of the liquid may be air and/or a carrier gas such as:

• a noble gas (argon, helium, neon) and/or
• a reactive gas (oxygen, nitrogen, hydrogen, etc.).

Throughout this application, the term “gas” designates an element which may consist of a single gas or of a gas mixture.

The chamber may include one or more gas injection inlet orifices and one or more gas recovery outlets. It will also be possible to have intermediate gas inlets and/or outlets along the channel. It will thus be possible to inject different gases along the channel in order to be able, for example, to promote in a targeted manner the formation of certain species while preventing the production of others. It is possible, for example, in a first portion of the channel to subject the liquid to a first gas and in a second portion of the channel, downstream of the first, to subject the liquid to a second gas different from the first. It is possible, for example, in a first channel to subject the liquid to a first gas and in a second channel, downstream of the first, to subject the liquid to a second gas different from the first. As a replacement or in addition, the device may comprise at least two chambers arranged in series (optionally separated by a reservoir for receiving the liquid), the liquid being subjected to a first gas in the first chamber and to a second gas in the second chamber. , second gas different from the first gas.

The gas may be injected through at least the same orifice as the liquid and/or through at least one other inlet orifice. Similarly, the gas can be recovered through at least the same orifice as the liquid and/or at least one other outlet orifice. The flow of gas injected into the body may also be controlled by the device and for example its control unit.

Consequently, the pressure in the reaction chamber may be equivalent to atmospheric pressure, be lower or be higher than atmospheric pressure. Similarly, the temperature in the reaction chamber may be equivalent to the atmospheric temperature or be higher than the atmospheric temperature or possibly be lower than the atmospheric temperature.

The treatment of the liquid in the reaction chamber by the plasma may be continuous or discontinuous depending on the configurations of the channel or channels jointly forming a pipe for the flow of the liquid in the body.

The inlet interface can be shaped to bring the liquid into the channel in order to ensure the smoothest flow possible and avoid the projection of the liquid. For example, the inlet interface can be shaped to bring the liquid into the channel by droplets. For example, the inlet interface may include a reservoir whose bottom is connected to the channel by micro-perforations. The inlet interface may otherwise comprise a bar extending directly above the channel and over the entire width of the channel and whose bottom is pierced with micro-perforations. The input interface may otherwise include pipettes in place of the micro-perforations.

Although the body is in PLA, the body could be in another material and for example in ceramic. If the body does not form the layer of dielectric material, the body may be in another material and for example in metallic material. The body can then, for example, form the counter-electrode.

The counter-electrode may be formed by the layer of liquid or may be formed by an additional element different from the layer of liquid. In the latter case, the layer of liquid may be directly in contact with the counter-electrode (as illustrated in FIG. 8b for example) or may be separated from the counter-electrode (as illustrated for example in FIG. 8e). The liquid layer can thus be at the same potential as the counter-electrode (either at a potential of zero volts) or be at a potential different from that of the counter-electrode and be for example at a floating potential. In all cases , and as already proposed the flow channel will be in a material having an affinity with the liquid it carries in order to facilitate the flow of the liquid along the channel (either that the material of the channel is intrinsically in a material having a affinity with the targeted liquid, or by treatment of said material to coat it with a film having an affinity with the targeted liquid). Thus, if the liquid is water, the material for the channel will preferably be a hydrophilic material or a material treated to present a hydrophilic surface.

The channel may not be made of dielectric material or may only be partially made of dielectric material. In particular, in the case of a U-shaped channel with a flat bottom as shown in Figure 1, only the bottom of the channel may be made of dielectric material, the sides being made of another material. The sidewalls may thus be made of an electrically conductive material.

Although it is not necessary, recirculation of the liquid through the body can be considered if necessary. It will however be preferred not to have any recirculation of the liquid in the chamber. Thus, the height of the chamber will preferably be increased or the slope of the channel will be adapted to prolong the duration of treatment of the liquid in the chamber.

Moreover, although here the channel is fixed in the body, the relative position of the channel in the body can be modified in particular, although not exclusively, to modify the slope of the channel in order to accentuate it or not. It will thus be possible to modify the residence time of the liquid in the chamber.

In the same way the electrodes may be different from what has been indicated. The electrodes can thus be flat, straight, curved, etc.

Claims (14)

Device for treating a liquid by plasma comprising a reaction chamber (2) comprising at least one supply electrode (12) associated with at least one counter-electrode (13), at least one layer of dielectric material separating said , the device being characterized in that the chamber comprises at the level of the electrodes at least one channel (6) arranged on a slope in the chamber so that the liquid flows in the said channel while being subjected to a plasma generated by the power supply of the feed electrode when the feed electrode is in operation. Device according to Claim 1, in which the channel (6) is formed by one of the electrodes and/or the layer of dielectric material. Device according to Claim 1 or Claim 2, in which the counter-electrode (13) is intended to be formed by the layer of liquid. Device according to at least one of Claims 1 to 3, in which the chamber comprises a body (3) in which the channel is arranged, the layer of dielectric material being formed directly by the material of the body. Device according to at least one of Claims 1 to 4, in which the channel (6) has a U-section with a flat bottom. Device according to at least one of Claims 1 to 5, in which the channel (6) is designed as a helix. Device according to at least one of Claims 1 to 5, in which the channel (6) is designed as an inclined plate. Device according to at least one of Claims 1 to 7, in which the chamber comprises a body, the channel, the electrodes and the layer of dielectric material being arranged so that in service the liquid is treated by plasma all along of its flow in the body (3). Device according to at least one of Claims 1 to 8, in which the chamber (2) includes means for injecting at least one carrier gas into the channel. Device according to at least one of Claims 1 to 9, further comprising at least one control unit (26) for controlling an electrical supply to the supply electrode as a function of data transmitted by at least one sensor of the device. Device according to at least one of Claims 1 to 10, in which at least the surface of the channel (6) is hydrophilic. Device according to at least one of Claims 1 to 11, in which the channel (6) is in communication with the ambient air. Device according to at least one of Claims 1 to 12, in which the chamber comprises a body, the channel (6) being formed in said body. Method for treating a liquid by plasma, the method being implemented using the device according to at least one of Claims 1 to 13 and comprising the steps of:
- Power supply electrode (12) electrically,
- Introduce the liquid into the chamber (2),
- Recover the liquid after plasma treatment in the chamber.