DEVICE AND METHOD FOR DESALINATING WATER BY HIGH-PRESSURE SPRAYING

Abstract

DEVICE AND METHOD FOR DESALINATING WATER BY HIGH-PRESSURE SPRAYING A device (1) for desalination of salt water by spraying comprises a supply (2) supplying salt water to a pump (3). A nozzle (5) is connected to the pump (3) to deliver salt water drops having a diameter of less than 1 mm. A pipe (6) receives the salt water drops from the at least one nozzle (5). An air flow generator (7) pushes the salt water drops and the air in the pipe (6) of the at least one nozzle (5) towards an outlet (6a). A container (8) recovers the air having passed through the pipe (6). A cooling (8a) and / or pressure increase (8b) device is configured to condense the water vapor present in the air of the container (8) to recover the salt-free water.

Description

Title of the invention: DEVICE AND METHOD FOR DESALINATING WATER BY HIGH-PRESSURE SPRAYING Technical field

[0001] The invention relates to a device for desalinating water by spraying and to a method for desalinating water by spraying. Prior art

[0002] The supply of fresh water remains a major problem for a portion of the world's population. Salt water is more readily available but is not potable, which leads to the conversion of salt water into fresh water.

[0003] There are different types of processes for producing fresh water from salt water. The most widely used processes are based on a principle of reverse osmosis, ultrafiltration or evaporation. The reverse osmosis and ultrafiltration processes consist of filtering salt water through semi-permeable membranes that allow water to pass through but stop ions (mainly sodium, potassium and chlorine). By applying a pressure higher than the osmotic pressure, the water passes through the semi-permeable membrane, thus allowing filtration of the ions and obtaining desalinated water.

[0004] It appears that these processes are very energy-intensive, and the ultrafiltration membranes used are themselves very expensive and have limited lifespans which further increase the cost of the fresh water produced.

[0005] Alongside these ultrafiltration and osmosis processes, there are distillation processes which consist of producing steam by boiling liquid water, then condensing the water vapor to obtain pure water. These distillation processes are generally very expensive in terms of heat energy. This energy is most often provided in the form of electricity, via electrical resistances, most often produced from fossil fuels, nuclear, or hydroelectric... Here again, the costs of producing fresh water are very high.

[0006] Supplying fresh water by evaporation requires heating salt water to a temperature between 80°C and 120°C to evaporate all or part of the water. Conventionally, in a quasi-continuous operating process, water is supplied to a heated reservoir. As the water evaporates, the salt content increases. The quasi-continuous supply of salt water to the reservoir means that at the end of an evaporation cycle, the desalination device discharges a brackish solution that is highly loaded with salt and is dangerous for the environment. In addition to the energy issues of successfully supplying the sufficient quantity of heat to evaporate the water, it is necessary to manage the brine produced. An alternative process consists of reducing the pressure in the tank to obtain the evaporation of the water, the results are essentially identical because the process is also a large consumer of energy and it requires managing the brine produced. Subject of the invention

[0007] An object of the invention is to provide a device for desalination of a volume of salt water which is more efficient than the devices of the prior art, in particular in that it consumes less energy.

[0008] These problems tend to be solved by means of a salt water desalination device by spraying comprising: - a power supply intended to provide salt water; - a pump having an inlet connected to the power supply; - at least one nozzle connected to an outlet of the pump for delivering a flow of salt water, the at least one nozzle being configured to deliver drops of salt water having a diameter of less than 1 mm; - a pipe receiving the salt water drops from the at least one nozzle, the pipe defining at least one outlet; - an air flow generator pushing the salt water drops and the air into the pipe of the at least one nozzle towards the outlet; - a container connected to the outlet of the pipe to recover the air having passed through the pipe after the at least one nozzle according to the direction of air flow; - a cooling and / or pressure increase device configured to condense the water vapor present in the air of the container to recover the salt-free water.

[0009] Advantageously, the pipeline defines at least one change of direction between the at least one nozzle and the outlet.

[0010] In an advantageous development, wherein the pipeline comprises at least one portion having a vertical component. The flow in said at least one portion predominantly comprises a vertical component directed upwards. A lower part of said portion is provided with a salt crystal recovery device.

[0011] Preferably, the at least one nozzle is configured to deliver drops having a diameter of less than 0.1 mm, advantageously less than 0.01 mm, more advantageously less than 0.001 mm.

[0012] According to one embodiment, an outlet of the cooling device or the pressure increasing device delivering heat is arranged upstream of the outlet to heat the air flow.

[0013] In an advantageous development, the discharge of the cooling device or the pressure increasing device is arranged between the air flow generator and at least one nozzle.

[0014] The invention also relates to a method for desalination of a volume of salt water which is more efficient than the methods of the prior art, in particular in that it is easy to implement and consumes less energy.

[0015] This result is tended to be achieved by means of a desalination process comprising the following steps: - provide the volume of salt water and a desalination device according to any of the preceding configurations; - delivering the volume of salt water in the form of drops having a diameter of less than 1 mm, the drops being introduced into a pipe swept by an air flow, the air flow directing the water drops towards an outlet of the pipe, the water drops vaporizing in the pipe to dissociate the water and the salt; - in a container connected to the outlet of the pipe, condense the water vapor present in the air flow leaving the pipe to recover the water without salt. Summary description of the drawings

[0016] Other advantages and characteristics will emerge more clearly from the following description of particular embodiments and implementations of the invention given as non-limiting examples and represented in the appended drawings, in which:

[0017] [Fig-1]: a schematic view of a first embodiment of a device for desalination; [Fig.2]: a schematic view of a second embodiment of a desalination device; [Fig.3]: a schematic view of a third embodiment of a desalination device. Description of the embodiments

[0018] Figures 1 to 3 illustrate a desalination device 1 configured to separate water and salt from a salt water solution so as to produce fresh water. The desalination device comprises spraying the salt water. Spraying means delivering a volume of salt water in the form of salt water drops.

[0019] The desalination device 1 comprises a salt water supply 2 which is intended to deliver the volume of salt water. The salt water supply 2 may be a tank which contains salt water or a pipe connected to the sea or any other means capable of continuously or intermittently supplying salt water.

[0020] The desalination device 1 comprises a pump 3 which has an inlet connected to the power supply 2. The pump 3 can be supplied with energy by any suitable means. Preferably, the pump 3 is supplied with electrical energy and more preferably with electricity coming totally or in part from one or more photovoltaic panels 4a and / or one or more wind turbines 4b.

[0021] The pump 3 delivers salt water under pressure which is higher than atmospheric pressure. For example, the pressure is higher than 2 bar, preferably higher than 20 bar, even more preferably higher than 50 bar.

[0022] The pump 3 supplies salt water to at least one nozzle 5, preferably several nozzles. The at least one nozzle 5 is configured to deliver drops of salt water whose diameter is less than 1 mm. By drops whose size is less than 1 mm, it is meant that the average size in number of the drops produced is less than 1 mm. It is assumed that the drops have a spherical shape.

[0023] More preferably, the at least one nozzle 5 is configured to deliver drops whose diameter is less than 0.1 mm, more preferably less than 0.01 mm. Preferably, the average diameter of the drops is less than 4 microns and even more preferably less than 1 micron.

[0024] The smaller the diameter of the drops, the easier it is to evaporate the water present in the salt water drops. During evaporation, the salt and water separate. The salt crystallizes and falls under the effect of gravity while the water in its gaseous form moves to follow an air flow.

[0025] The supply of water in the form of a spray of drops makes it possible to have the vaporization of water with low electrical consumption and in particular lower electrical consumption than a reverse osmosis process.

[0026] Mist sprayers or nebulizers are known which deliver a solution in the form of a mist whose drops have a diameter of less than 1 mm to less than 1 micron.

[0027] Tests were carried out with a mist sprayer containing 20 nozzles and working with a water pressure equal to 70 bars. The flow rate of the mist sprayer is 60 L / h and the power consumed is 180W.

[0028] The desalination device comprises a pipe 6 which receives the flow from the at least one nozzle 5. The flow of salt water drops is projected into a pipe 6 in order to control the hygrometry as well as the water evaporation process. The water present in the vapor form is in the pipe 6. The pipe 6 defines at least one outlet 6a. The outlet 6a of the pipe 6 delivers a flow of air which has a significant mass content of water vapor and whose mass content of salt water is low or even zero.

[0029] The desalination device 1 comprises an air flow generator 7 defining the flow direction of the air flow having the salt water drops and the water vapor. The air flow generator 7 imposes a flow from the at least one nozzle 5 to outlet 6a. The air flow generator 7 defines the direction of air circulation inside the pipe 6. As the air circulates along the pipe 6, the diameter of the drops decreases until the water has mostly vaporized or even completely vaporized.

[0030] By predominantly vaporized, we mean a reduction in the diameter of the drops by two, or even by three, more preferably by five or by ten. Between the nozzle and the outlet 6a.

[0031] The air flow generator 7 pushes the air containing the salt water drops, which makes it possible to homogenize the water vapor content to have evaporation as the air moves along the pipe 6.

[0032] A container 8 is arranged at the outlet of the pipe 6 to recover the air having passed through the pipe 6 after the at least one nozzle 5 in the direction of air flow. The desalination device 1 has at the outlet of the pipe 6 a container 8 which receives the air which has a high water vapor content.

[0033] In order to recover the water which is in its vapor form at the outlet of the pipe 6, the desalination device 1 comprises a cooling device 8a and / or pressure increase device 8b. The cooling device 8a and / or pressure increase device 8b is configured to condense the water vapor present in the air of the container 8 in order to recover the water devoid of salt. In a known manner, the installation of a cooling device 8a makes it possible to cool the air which condenses the water contained in the air flow leaving the pipe 6. Alternatively or in addition, the pressure increase device 8b can be used to condense the fresh water.

[0034] The container has an outlet 9 capable of delivering the fresh water produced by the desalination device 1.

[0035] It is particularly advantageous that the outlet 6a is not in the extension of the direction of movement of the water drops in the pipe 6. This precaution makes it possible to avoid sending small drops, i.e. drops heavily loaded with salt, through the outlet 6a. This also makes it possible to reduce the transmission of salt crystals which are carried by the air flow to the container 8.

[0036] Preferably illustrated in Figures 1 to 3, the pipe 6 comprises one or more portions which extend with a rising vertical component according to the direction of circulation of the air flow in the pipe 6. The presence of one or more rising portions makes it possible to have a force which pushes the drops of salt water and which opposes the effect of gravity so as to have a maximized exchange between the gas phase and the drops to achieve evaporation of the water. The vertical direction is represented by the ZZ direction.

[0037] In an advantageous embodiment illustrated in Figures 1 and 3, the pipe 6 comprises one or more portions which extend predominantly with a rising vertical component according to the direction of circulation of the air flow in the duct, for example the portion or portions are completely vertical. The air flow generator 7 generates a force which prevents the salt water drops from falling and it delivers air which is drier than the fog air to maintain evaporation.

[0038] The flow rate of the air flow generator 7 is chosen so as to prevent water drops from falling into the pipe 6. The flow rate value is preferably adapted to the diameter of the drops in order to maintain a mist in the pipe near the at least one nozzle or to propagate it up to the altitude of the outlet. It is particularly advantageous for the altitude of the outlet 6a to be greater than the altitude of the at least one nozzle 5 in order to limit the transport of salt crystals.

[0039] The diameter of the drops can be adapted according to the temperature of the air flow in the pipe 6. The higher the temperature in the pipe 6, the larger the average diameter of the drops can be.

[0040] In order to have maximum evaporation, the force generated by the air flow generator on the salt water drops is adapted according to the temperature in the pipe 6, the temperature of the salt water in the at least one nozzle 5, the length of the pipe 6 between the at least one nozzle 5 and the outlet 6a. The force applied by the air flow generator 7 can be represented by the speed of the air emitted by the air flow or the flow rate of the air flow generator 7.

[0041] In a preferred embodiment, the desalination device 1 defines a portion having a temperature gradient which decreases according to the direction of movement of the air flow. Preferably, the temperature decreases from the at least one nozzle 5 to the outlet 6a of the pipe 6. Advantageously, the temperature continuously decreases from the at least one nozzle 5 to the outlet 6a of the pipe 6.

[0042] In an advantageous embodiment, the use of a high speed allows for rapid exchange with the ambient air to promote the evaporation of water.

[0043] Even more advantageously, the pipe 6 defines at least one bend 6b, preferably several successive bends 6b in order to take advantage of the centrifugal force to improve evaporation and / or the separation between the water and the salt. For example, a bend 6b corresponds to a change of direction which transforms a vertical movement into a horizontal movement or which transforms a vertical movement from bottom to top into a vertical movement from top to bottom. The radius of curvature of the bend 6b can be adapted to the speed of movement of the drops in the pipe 6 as well as to the size of the drops in the pipe 6.

[0044] Preferably, the pipe 6 is supplied with air by means of the ambient air which is around the desalination device. It is advantageous to place a filter upstream of the air flow generator 7 so as not to pollute the interior of the pipe 7 and / or not to introduce particles which will modify the evaporation kinetics.

[0045] In an advantageous embodiment, the desalination device is devoid of means for heating the water upstream of the at least one nozzle as well as means for heating the air in the pipe 6 and means for heating the walls of the pipe 6. By devoid of heating means is meant active heating means, that is to say heating means which are supplied with electrical energy, fossil energy or any other controllable energy. The heat is drawn from the air outside the desalination device.

[0046] Preferably, the desalination device is provided with a temperature sensor which is configured to heat the salt water and / or the air when the temperature of the salt water and / or the air is lower than 15°C or to stop the desalination device if the desalination device is without heating means.

[0047] It has been observed that the evaporation of 1g of water requires drawing approximately 600cal or approximately 2512 Joules. This capture of calories generally results in a lowering of the temperature of the air carrying the water drops, it is therefore advantageous to have air injected into the pipe which is higher than 15°C and preferably as hot as possible.

[0048] The cooling device 8a configured to cool the temperature in the container 8 and the pressure increasing device 8b configured to increase the pressure in the container 8b are devices that consume energy and release heat. It is also advantageous to provide that an outlet of the device 8a / 8b is configured to remove heat from the device to the pipe 6 in order to increase the temperature of the pipe 6. The increase in temperature in the pipe allows for warmer air which promotes evaporation. Alternatively or in addition, the outlet heats the wall of the outlet.

[0049] In order to have the most efficient evaporation possible, it is advantageous for the air flow generator to receive dry and hot air. The drier and hotter the air applied to the inlet of the air flow generator, the less it is necessary to heat the air in the duct and / or the walls of the duct. The evaporation phenomenon results in an absorption of calories from the ambient environment, i.e. the air present in the duct 6. It is therefore advantageous to have a heat supply to avoid slowing down the evaporation phenomenon which seeks to capture calories in the air.

[0050] It is also advantageous to pre-treat the salt water in order to eliminate particles and impurities which could modify the evaporation phenomena or even cause unwanted condensation inside the pipe 6.

[0051] In a particular embodiment, the pressure in the pipe 6 is identical or substantially identical to atmospheric pressure, i.e. the pressure outside the desalination device 1. Preferably, the pressure in the pipe 6 is between 0.8 and 1.2 bar. This makes it possible not to have to manage the pressure in the pipe and this reduces the overall electrical consumption.

[0052] Preferably, at least a portion of the desalination device 1 is heated by means of a solar collector. The solar collector may be a thermal solar collector or a photovoltaic solar collector.

[0053] The solar thermal collector can be connected to the power supply so as to heat the salt water ejected by the at least one nozzle 5. The higher the temperature of the salt water, the more efficient the evaporation of the water.

[0054] The solar thermal collector can be connected to the pipe 6 so as to heat the air present in the pipe 6. The higher the air temperature, the more efficient the evaporation.

[0055] The desalination device is particularly advantageous because it can operate continuously or almost continuously. As the water evaporates, salt crystals form and fall or stick to the wall of the pipe. The installation of one or more salt collectors 10 arranged at one or more strategic locations in the pipe makes it possible to recover the salt crystals.

[0056] For example, in the embodiments illustrated in Figures 1 and 3, a salt crystal collector 10 may be arranged at the lower end of the vertical sections. In the embodiment illustrated in [Fig.l], installing the salt crystal collector 10 below the air flow generator 7 makes it possible to recover the salt crystals without having to stop the supply of salt water drops.

[0057] In the embodiment of [Fig.2], the pipe 6 may be provided with a scraper which runs along the wall of the pipe 6 downwards in order to push the salt crystals towards the salt crystal collector. 10 Alternatively, the scraping may be carried out manually. In the event of manual intervention, it is preferable to stop the desalination device.

[0058] The desalination process can be presented as follows. The volume of salt water to be transformed into fresh water is provided and a desalination device according to any of the preceding configurations is provided.

[0059] The volume of salt water is delivered in the form of drops having a diameter of less than 1 mm. The drops are introduced into the pipe swept by an air flow. The water drops vaporize in the pipe 6 to dissociate the water and the salt. The water is in its vapor form while the salt is present in solid form. The air containing the water in vapor form passes through the pipe 6 to the outlet to reach the container. In the container, the water vapor present in the air flow at the outlet of the pipe to recover the water without salt.

Claims

Claims

1. A device (1) for desalination of salt water by spraying comprising: - a supply (2) intended to supply salt water; - a pump (3) having an inlet connected to the supply (2); - at least one nozzle (5) connected to an outlet of the pump (3) to deliver a flow of salt water, the at least one nozzle (5) being configured to deliver drops of salt water having a diameter of less than 1 mm; - a pipe (6) receiving the drops of salt water from the at least one nozzle (5), the pipe (6) defining at least one outlet (6a); - an air flow generator (7) pushing the drops of salt water and the air in the pipe (6) of the at least one nozzle (5) towards the outlet; - a container (8) connected to the outlet (6a) of the pipe (6) to recover the air having passed through the pipe (6) after the at least one nozzle (5) in the direction of air flow;- a cooling (8a) and / or pressure increasing (8b) device configured to condense the water vapor present in the air of the container (8) to recover the salt-free water.;

2. A device for desalination (la) of salt water by spraying according to claim 1 in which the pipe (6) defines at least one change of direction between the at least one nozzle (5) and the outlet (6a).

3. A salt water desalination device by spraying according to one of claims 1 and 2, in which the pipe (6) comprises at least one portion having a vertical component, in which the flow in said at least one portion comprises mainly a vertical component directed upwards and in which a lower part of said portion is provided with a salt crystal recovery device (10).

4. A salt water desalination device by spraying according to any one of claims 1 to 3 wherein the at least one nozzle (5) is configured to deliver drops having a diameter of less than 0.1 mm.

5. A salt water desalination device by spraying according to claim 4 wherein the at least one nozzle (5) is configured to deliver drops having a diameter of less than 0.01 mm.

6. A salt water desalination device by spraying according to claim dication 5 in which the at least one nozzle (5) is configured to deliver drops having a diameter of less than 0.001 mm.

7. A spray salt water desalination device according to any one of claims 1 to 6 wherein an outlet of the cooling device (8a) or the pressure increasing device (8b) delivering heat is arranged upstream of the outlet (6a) to heat the air flow.

8. A spray salt water desalination device according to claim 7 wherein the discharge of the cooling device (8a) or the pressure increasing device (8b) is arranged between the air flow generator (7) and the at least one nozzle (5).

9. A method for desalination of a volume of salt water comprising the following steps: - providing the volume of salt water and a desalination device (1) according to any one of the preceding claims; - delivering the volume of salt water in the form of drops having a diameter of less than 1 mm, the drops being introduced into a pipe (6) swept by an air flow, the air flow directing the water drops towards an outlet (6a) of the pipe (6), the water drops vaporizing in the pipe (6) to dissociate the water and the salt; - in a container (8) connected to the outlet (6a) of the pipe (6), condensing the water vapor present in the air flow at the outlet of the pipe (6) to recover the water devoid of salt.

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