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 is why salt water is being converted 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 energy, or hydroelectric power... 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 problems of successfully supplying the sufficient quantity of heat to evaporate the water, it is necessary to manage the brine produced. An alternative process is to reduce the pressure in the tank to achieve evaporation of the water. The results are essentially the same because the process is also energy intensive and requires management of 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, 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 the at least one nozzle.

[0014] Preferably, a pipe provided with a plurality of nozzles arranged successively along an air flow defined by the air flow generator, in which the pipe is suspended inside the pipeline.

[0015] Advantageously, the salt water desalination device by spraying comprises heating means configured to heat walls of the pipeline.

[0016] It is preferable to provide that the pipe is suspended by a plurality of metal hangers in thermal conduction with the walls of the pipeline, the hangers being swept by the air flow defined by the air flow generator.

[0017] In a preferred embodiment, the pipeline has a top portion without a recess, the top portion extending continuously on either side of the pipe from an altitude equal to an altitude of the pipe.

[0018] In an advantageous development, the salt water desalination device by spraying comprises at least one salt crystal collector arranged under the pipe and extending from one edge to the other of the pipe in a horizontal direction and perpendicular to a longitudinal direction of the pipe, the at least one salt crystal collector being mounted to move relative to the pipe.

[0019] There is also a preferred embodiment in which the airflow generator generates an airflow above the pipe which has a greater velocity than an airflow below the pipe, the velocity being measured along a horizontal component of the longitudinal axis of the pipe.

[0020] 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.

[0021] 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.

[0022] In an advantageous development, the method is implemented by means of a desalination device according to one of the preceding configurations and the salt water is projected against a wall of the pipeline to achieve evaporation of the salt water in contact with the wall, the wall being a heating wall. Summary description of the drawings

[0023] 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:

[0024] [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; [Fig.4]: a schematic view of a fourth embodiment of a desalination device; [Fig.5]: A schematic cross-sectional view of the fourth embodiment of a desalination device. Description of the embodiments

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] The smaller the droplet diameter, the easier it is to evaporate the water present in the salt water droplets. 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The desalination device 1 comprises an air flow generator 7 defining the direction of flow 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 the outlet 6a. The air flow generator 7 defines the direction of circulation of the air 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.

[0037] 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.

[0038] The air flow generator 7 pushes the air containing the salt water drops, which makes it possible to homogenize the water vapor content in order to have evaporation as the air moves along the pipe 6.

[0039] 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.

[0040] 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. In a particular embodiment, the cooling device comprises thermally conductive pipes which circulate inside the condenser 8 and which are crossed by a low-temperature fluid.For example, thermally conductive pipes are copper or stainless steel pipes. When the desalination plant is located near a sea or ocean, it is advantageous to circulate seawater through thermally conductive pipes. It is also possible to draw water from the bottom of a well. It is also possible to use water that has been cooled.

[0041] The container has an outlet 9 capable of delivering the fresh water produced by the desalination device 1.

[0042] 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 drops of small sizes, that is to say those 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.

[0043] 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 allows for a force that pushes the salt water drops and opposes the effect of gravity in order to have a maximized exchange between the gas phase and the drops to achieve the evaporation of the water. The vertical direction is represented by the ZZ direction.

[0044] 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 pipe, 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.

[0045] 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 6a. 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.

[0046] 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.

[0047] In order to have maximum evaporation, the force generated by the air flow generator 7 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.

[0048] 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.

[0049] In an advantageous embodiment, the use of a high speed allows for rapid exchange with the ambient air to promote the evaporation of water.

[0050] 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 separation between the water and the salt. For example, a bend 6b corresponds to a change of direction which transforms a displacement vertical into a horizontal displacement or which transforms a vertical displacement from bottom to top into a vertical displacement 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.

[0051] Preferably, the pipe 6 is supplied with air by means of the ambient air which is around the desalination device. It is advantageous to have 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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 8 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 8a / 8b to the pipe 6 in order to increase the temperature of the pipe 6. The increase in temperature in the pipe 6 allows for warmer air which promotes evaporation. Alternatively or in addition, the outlet heats the wall of the outlet.

[0056] In order to have the most efficient evaporation possible, it is advantageous for the air flow generator 7 to receive dry and hot air. The drier and hotter the air applied to the inlet of the air flow generator 7, the less it is necessary to heat the air in the duct 6 and / or the walls of the duct 6. The phenomenon evaporation results in an absorption of calories from the ambient environment, i.e. the air present in pipe 6. It is therefore advantageous to have a heat supply to avoid slowing down the evaporation phenomenon which seeks to capture calories from the air.

[0057] 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.

[0058] 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 6 and this reduces the overall electrical consumption.

[0059] 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.

[0060] The solar thermal collector can be connected to the power supply 2 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.

[0061] 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.

[0062] 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 6. The installation of one or more salt collectors 10 arranged at one or more strategic locations in the pipe 6 makes it possible to recover the salt crystals.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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 8. In the container 8, the water vapor present in the air flow at the outlet of the pipe 6 is condensed to recover the water devoid of salt.

[0067] In a particular embodiment illustrated in Figures 4 and 5, there are several nozzles 5 inside the pipe 6 which are arranged one behind the other according to the direction of circulation of the salt water in a pipe 11 which supplies the nozzles 5.

[0068] The pipe 11 and the nozzles 5 are suspended inside the pipe 6. Preferably, the pipe 11 and the nozzles 5 are suspended by means of hangers 12, for example wires, cables or rods which are fixed to the top of the pipe 6. It is possibly possible to have other hangers 12 which are fixed to other places on the wall of the pipe 6.

[0069] The installation of the nozzles 5 and the pipe 11 suspended in the pipe 6 makes it possible to limit the contacts between the nozzles 5 and the wall of the pipe 6 to reduce heat exchanges. This also makes it possible to limit the obstacles to the fall of the salt onto the floor of the pipe 6. The pipe 11 and the wall of the pipe 6 exchange little heat, which makes it possible to have a pipe 11 whose temperature is better controlled from one end to the other. The water is injected into the nozzles 5 with a more uniform temperature, which facilitates the control of the evaporation mechanisms.

[0070] It appears advantageous to supply heat to drops of salt water in order to evaporate them in the pipe 6 and separate the water and the salt instead of supplying the same amount of energy to a large volume of salt water to obtain its evaporation. As the evaporation phenomenon occurs in a large volume of salt water, the salt concentration increases, which accentuates the corrosion phenomena and makes evaporation more difficult. It happens that a salt crust forms on the surface of the water, which blocks evaporation.

[0071] It is therefore particularly advantageous to have a flow of salt water which is thermally disconnected from the walls of the pipe 6 in order to have better control over the conditions in the pipe 11 which delivers the salt water.

[0072] Preferably, the pipe 11 is suspended by means of a plurality of hangers 12 which are flexible, which facilitates the management of differential expansions between the wall of the pipe 6 and the pipe 11 as the day progresses.

[0073] When the wall of the pipe 6 is a heating wall, for example a heated wall which is hotter than the atmosphere in the pipe 6, it is advantageous for the pipe 11 to be suspended by means of a metal hanger 12 which is in thermal contact with the heating wall. Part of the heat from the wall is transmitted to the hanger 12 which reduces the risks of having an accumulation of salt water which can be detrimental to good performance over time.

[0074] It is particularly advantageous to heat the salt water in order to have to supply as little energy as possible in the pipe 6 to evaporate the water drops. The supply can be heated by means of solar energy. It is also possible for at least part of the salt water flow to pass through the condenser 8 in order to cool the condenser 8 to promote condensation and to capture part of the calories from the condenser 8 to heat the salt water.

[0075] It is advantageous to heat the salt water present in the pipe 11 to a temperature which does not allow the evaporation of the water. The aim is to avoid the formation of salt crystals in the pipe 11.

[0076] It is advantageous for the desalination device to be provided with a pipe thermometer configured to measure the temperature of the salt water in the pipe 11. The pipe thermometer is connected to the control circuit 13. The control circuit 13 can act on heating means configured to heat the salt water which feeds the pipe 11 so that the temperature is lower than a maximum ejection temperature and more preferably so that the temperature is higher than a minimum ejection temperature. The maximum ejection temperature and the minimum ejection temperature can be threshold temperatures which are dependent on the flow rate of water in the pipe 11.

[0077] In one embodiment, the volume of salt water injected per linear meter of pipe 6 is substantially constant along the pipe 6. Since the water vapor content increases as one approaches the outlet 6a, it is advantageous to increase the temperature in the pipe 6, for example by increasing the temperature of the walls to promote evaporation in air that is less dry than at the inlet. In addition or as an alternative, one or more dry air inlets are present along the pipe in order to limit the water vapor content in the pipe 6. The dry air inlet(s) may be connected to the air flow generator 7 or to an additional air flow generator. The additional air flow generator makes it possible to independently modulate the air flow in the dry air inlets relative to the inlet of the pipe 6.

[0078] In a preferred embodiment, dry air is injected into the pipe 6 between the first of the nozzles 5 and the outlet 6a by means of an additional air inlet. The first of the nozzles 5 is the first nozzle in operation arranged between the supply 3 and the outlet 6a in the path traveled by the evaporating salt water. It is preferable that the injected air is hot air, by hot air is meant air whose temperature is at least equal to 15°C, preferably at least equal to 25°C, more preferably at least equal to the temperature of the air 2 centimeters before the additional air inlet. Even more preferably, the temperature of the injected air is at least 5°C higher than the temperature of the air 2cm before the additional air inlet. Adding additional air helps reduce the water vapor content, which facilitates evaporation for the salt water coming from the nozzles 5 to follow.

[0079] Alternatively or in addition, it is possible to provide that the flow rates of salt water delivered by each of the nozzles 5 along the pipe 6 are not identical. The nozzles 5 being arranged one behind the other in the direction of an air flow which circulates along the pipe 6, it is advantageous for the flow rates to decrease as one approaches the outlet. Since the air becomes increasingly charged with water as one approaches the outlet 6a, it is advantageous to reduce the supply of salt water by reducing the number of nozzles 5 and / or to increase the temperature of the air in the pipe 6 as one approaches the outlet 6a.

[0080] Preferably, the interior of the wall of the pipe 6 is concave without any recesses so that the salt which is deposited on the walls of the pipe 6 falls onto the floor of the pipe 6 to be recovered.

[0081] It is advantageous for the top portion of the pipe 6 to have a width less than the bottom portion of the pipe 6. The top portion extends above the height of the pipe 11 and the bottom portion extends below the height of the pipe 11. The width is a horizontal dimension perpendicular to the longitudinal direction of the pipe 11.

[0082] It is advantageous for the top part of the pipe 6, that is to say the portion at an altitude greater than or equal to a nozzle 5, to have a surface area smaller than the surface area of ​​the bottom part of the pipe 6, that is to say the part located under the nozzle in an observation along a vertical section plane and substantially perpendicular to the direction which connects the nozzles 5. In the top part of the pipe 6, the available volume is strongly filled by the salt water mist and this mist is efficiently displaced by means of the air flow generator 7. In the bottom part of the pipe 6, the volume is greater which makes it possible to reduce the speed of the air flow to disperse the salt crystals less.

[0083] It is advantageous for the temperature in the upper half of the pipe 6 to be greater than the temperature in the lower half of the pipe 6. It is advantageous to provide more energy in the upper part than in the lower part of the pipe 6.

[0084] It is also advantageous for the pipe 11 to be arranged in the upper half of the pipe 6 and more preferably in the upper third of the pipe 6. It is also advantageous for the distance between the bottom of the pipe 6 and the nozzle 5 to be greater than the distance which separates the nozzle 5 and the top of the pipe 6 in a vertical section perpendicular to the longitudinal axis of the pipe 6.

[0085] The bottom is preferably provided with one or more salt crystal collectors 10 which may be in the form of movable receptacles which are intended to collect the salt and to facilitate the extraction of the salt from the pipe 6. The further the bottom is from the air flow defined by the air flow generator 7, the more the movement of the receptacles has a minimal effect on the movement of water drops.

[0086] It is preferable that the nozzle(s) 5 eject salt water upwards towards the top of the pipe 6 or a top portion of the pipe 6.

[0087] It is particularly advantageous that the nozzles 5 only project drops of water with a vertical component directed upwards. The effect of gravity makes it possible to increase the distance to be traveled before reaching a wall of the pipe 6. This makes it possible to increase the distance to be traveled before reaching the bottom of the pipe 6 because the aim is to avoid having water in the bottom of the pipe to avoid the formation of brine.

[0088] Preferably, the nozzle(s) 5 eject a flow of water extending over an angle at least equal to 90° and preferably less than 160°. The angle is observed in a section perpendicular to the longitudinal axis of the pipe 11. The greater the angle, the greater the volume used inside the pipe 6. [Fig. 5] illustrates a nozzle which projects a mist over less than 160°. However, the air flow causes the mist to widen, which tends to occupy almost all the available volume above the pipe. Part of the mist can extend under the pipe and the heat stored by the air tends to move the air laden with water vapor upwards to join the flow which moves towards the outlet 6a.

[0089] It is advantageous if the pipe is arranged with a slight upward slope in the direction of flow of the salt water in the pipe 11, i.e. towards the outlet 6a. It is also possible for the pipe 11 to be arranged horizontally.

[0090] It is advantageous if the top of the pipe 6 has a constant distance from the nozzles 5 or if the separation distance from the nozzles 5 increases as one approaches the outlet 6a. The distance is measured along a section plane perpendicular to the direction of arrangement of the nozzles 5. It is advantageous if the fog is not subject to any narrowing of the section of the upper part of the pipe 6 between the last nozzle 5 and the outlet 6a and preferably between each of the nozzles 5 and the outlet 6a.

[0091] In a particular embodiment, the wall of the pipe 6 is passively heated. For example, the outer wall of the pipe 6 is covered with a dark-colored coating, preferably a black-colored coating. The outer wall of the pipe 6 is subjected to solar radiation in order to heat the wall of the pipe 6. The heating of the wall of the pipe by means of solar radiation may be supplemented or replaced by heating of another type, for example by Joule heating which also uses solar energy, for example of the photovoltaic type or by a wind-powered electric generator.

[0092] One or more thermometers may be used to measure the temperature of the pipe wall. The temperature information is sent to a control circuit 13 connected to the pump and / or the air flow generator 7, which makes it possible to adapt the movement conditions in the pipe 6 to the quantity of heat available to evaporate the salt water drops.

[0093] When the reservoir 14 contains high-temperature heat transfer fluid and the control circuit 13 detects that the energy supply is weakening or will weaken, the control circuit 14 can control the heating of the salt water before its introduction into the pipe 11 in order to promote accelerated evaporation and / or the control circuit 13 can control the heating of the wall of the pipe 6.

[0094] For example, the control circuit 13 is provided with a memory that knows the sunset and sunrise times. The control circuit 13 can calculate the evolution of the caloric input from the sun's rays throughout the day. When the energy input from the sun's rays is greater than the needs of the desalination device 1, part of the energy is stored, which allows it to be used at the end of the day when the energy input is no longer sufficient. It is even possible to operate the desalination device 1 without sun for a short period. This also allows for more uniform operation when the weather is cloudy and the energy input from the sun's rays fluctuates rapidly. The sun's rays are illustrated schematically by arrows in [Fig.5].

[0095] It is also envisaged that the bottom of the pipe 6 is traversed by one or more lines receiving heated heat transfer fluid. The heated heat transfer fluid is used to heat the bottom of the pipe 6, i.e. its lowest part, which may possibly collect salt water. The latter is particularly corrosive and may damage the desalination device. It is therefore advantageous to heat the bottom of pipe 6 to keep the salt as solid as possible.

[0096] Since the bottom of the pipe 6 is not intended to be struck by the sun's rays, there may be a significant difference in temperature between the top of the pipe 6 and the bottom of the pipe 6. By capturing part of the heat present in the top of the pipe to heat the bottom of the pipe 6, it is possible to have a more uniform deformation of the pipe 6, which limits its aging.

[0097] It is advantageous to heat the bottom or to have the bottom at a temperature above a bottom threshold temperature. The heat evacuated by the bottom allows the few drops that fall on the bottom to evaporate and allows for an evaporation phenomenon that acts throughout the fall of the water drops. Heating the bottom is advantageous with respect to drops of larger diameters which are heavier and for which the air flow may be insufficiently powerful.

[0098] It is particularly advantageous for the walls of the pipe 6 to be made of metal, for example steel.

[0099] It is advantageous for the air flow generator 7 to define a higher flow velocity in the upper half of the pipe 6 than in the lower half of the pipe 6. The higher flow in the upper part of the pipe 6 allows the small diameter drops to move towards the outlet 6a so that the air loaded with water vapor reaches the condenser 8 ensuring recovery of the liquid water.

[0100] Drops with larger diameters are not directed towards the outlet because their arrangement in the lower part of the pipe 6 makes evaporation more difficult. It is preferable that the drops mainly reach the bottom wall of the pipe 6 and that they evaporate on contact with the bottom. Since the drops reaching the bottom are in small quantities, the heat loss due to the evaporation phenomenon is low.

[0101] Depending on the average volume of the water drops, the temperature inside the pipe 6, the humidity already present in the atmosphere of the pipe 6, it is possible to calculate the time required for the water drop to be completely evaporated. It is then possible to modulate the speed of ejection of the water drops from the nozzle 5 and the speed of movement of the air flow to define the operating mode of the desalination device along the pipe 6.

[0102] In a particular embodiment, the operating conditions are chosen to prevent water in liquid form from being deposited against the wall of the pipe 6, i.e. so that the entire flow of water is evaporated before reaching a wall of the pipe 6. All of the calories captured by the salt water drops from the air in duct 6. The speed of movement of the air flow is defined by the air flow generator 7.

[0103] The ejection speed of the salt water drops is insufficient to reach the top of the pipe 6 when the air flow generator 7 is in operation and possibly in the absence of operation of the air flow generator 7.

[0104] In another particular embodiment, the operating conditions are chosen so that a portion of the water flow reaches the wall of the pipe 6. Under these conditions, a portion of the water flow is evaporated by means of the ambient air and the remainder of the water flow evaporates upon contact with the wall, mainly capturing the water from the wall. It is advantageous for the diameter of the water drops to be at least halved, preferably at least divided by three, before reaching the wall.

[0105] In this case, the water droplet may be partially evaporated, that is to say that its volume has decreased before reaching the wall of the pipe 6. A portion of the calories present in the wall of the pipe 6 is captured by the water droplet to complete its evaporation. The quantity of water ejected by the nozzles 5 and / or the ejection pressure are adapted so that the quantity of water reaching the pipe wall 6 and therefore the quantity of calories captured by the salt water drops is equal to the quantity of calories provided by solar radiation.

[0106] Once the pipe 6 and the nozzles 5 are installed, by means of the same parameters, it is possible to adjust the salt water supply conditions to prevent water drops from reaching the wall of the pipe 6 or to obtain partial evaporation against the wall of the pipe 6. A decrease in the temperature in the pipe 6 can be compensated by a decrease in the pressure in the supply pipe 11 and / or by an increase in the speed of the air flow along the pipe 6.

[0107] When the wall temperature decreases, the salt water pressure applied to the inlet of the nozzles 5 can be decreased and / or the air flow generator 7 increases the displacement component towards the outlet 6a.

[0108] The desalination device 1 may be provided with a first thermometer arranged to measure a temperature of the wall of the pipe 6 intended to face a nozzle 5. The measured temperature is transmitted to a control circuit 13.

[0109] When the control circuit 13 detects a drop in the temperature measured by the first thermometer, the control circuit 13 concludes that the energy supplied to the wall of the pipe has decreased or the energy captured from the wall has increased. The control circuit 13 may decide to decrease the quantity of water to be evaporated, for example by reducing the number of nozzles 5 in operation and / or by reducing the flow rate in the pipe 11 and / or by heating the water present in the supply 2. If the drop in temperature is punctual, that is to say present on a single thermometer, the control circuit 13 can command to increase the speed of the air flow generator 7.

[0110] The control circuit 13 can be connected to a second thermometer configured to measure another part of the wall which is not intended to be in contact with the salt water mist. The second thermometer makes it possible to monitor the evolution of the temperature of the wall as a function of the heat input from the sun and the exchanges with the external environment, that is to say the environment outside the pipe 6, for example the air around the pipe 6.

[0111] If the control circuit 13 detects that the temperature difference between the first thermometer and the second thermometer reaches a threshold value, it can intervene as indicated above.

[0112] If the control circuit 13 detects that the temperature measured by the second thermometer is less than or equal to a first minimum threshold value, the control circuit 13 can reduce the flow rate in the pipe 11 and / or reduce the number of nozzles 5 in operation because the installation is no longer able to provide all the energy necessary for good evaporation of the water. If the control circuit 13 detects that the temperature measured by the second thermometer is less than or equal to a second minimum threshold value, the control circuit 13 can stop the installation. The second minimum threshold value is greater than the first minimum threshold value.

[0113] If the control circuit 13 detects that the temperature measured by the second thermometer is greater than or equal to a first maximum value, the control circuit 13 can control an increase in the flow rate in the pipe 11 and / or an increase in the number of nozzles 5 in operation. The control circuit 13 can also control heating of the salt water before its introduction into the pipe 11. The heat necessary for heating the salt water is taken from the wall of the pipe 6.

[0114] If the control circuit 13 detects that the temperature measured by the second thermometer is greater than or equal to a first maximum value or a second threshold value greater than the first threshold value, the wall of the pipe 6 can be connected to a heat transfer fluid which circulates along the wall to capture a portion of the heat from the wall in order to maintain the wall of the pipe 6 in an optimal temperature range. The heated heat transfer fluid is stored in a thermally insulated tank 14.

[0115] Preferably, the at least one nozzle 5 ejects salt water with such power that the water reaches a wall of the pipe 6. The wall is heated by any suitable means. Preferably, the wall is heated by the sun's rays. The heat input to the wall ensures the evaporation of the salt water. The salt remains stuck to the wall or can fall from the wall to the bottom of the pipe 6. The use of a vertical wall or one that extends mainly in a vertical direction is advantageous. For example, the wall defines an angle of less than 20° with respect to the vertical direction. It is preferable for the upper part of the pipeline to be on a slope. The use of a vertical or quasi-vertical wall makes it easier for the salt to fall after the water has evaporated.

[0116] The evolution of the temperature of the wall of the pipe 6 and the rate of evolution of the temperature of the wall of the pipe 6 are monitored in order to control the evaporation phenomena in the pipe 6. When the rate of evolution of the temperature of the wall is representative of a drop in temperature beyond a threshold value, the flow rate in the pipe 11 is reduced or the flow rate is stopped. The rapid downward evolution of the temperature of the wall is representative of a significant capture of calories which corresponds to a wall which is not able to sustainably evaporate the flow of salt water. It is therefore advantageous to reduce the flow rate of salt water to reach a new steady state where the energy necessary to evaporate the water leaving the nozzle 5 is provided by an equivalent energy input to the wall.

[0117] The wall may be provided with a plurality of thermometers which are arranged to measure the temperature at different locations on the wall and in particular in a direction which extends along the direction of advance of the air flow towards the outlet. The thermometers are connected to the control circuit 13. When the control circuit 13 detects that at least one of the thermometers reaches a threshold temperature close to the condensation temperature of the water, the control circuit 13 can control the stopping of one or more nozzles 5 in order to reduce the quantity of water to be vaporized and therefore the quantity of calories to be drawn from the walls or the atmosphere present in the pipe.

[0118] When the control circuit detects that the temperature of the wall is lower than an evaporation threshold temperature or that the speed of evolution of the wall of the pipe is representative of a drop beyond a threshold speed, the control circuit 13 can command the replacement of a partial evaporation of the salt water against the wall by a total evaporation in the atmosphere of the pipe.

[0119] In an advantageous embodiment, a heating blanket may be arranged against the walls of the pipe 6 in order to provide heat to the pipe 6 to maintain a wall temperature or an air temperature in the pipe 6 compatible with the evaporation of the salt water. The heating blanket is removably mounted relative to the pipe 6. When the control circuit 13 detects that the temperature of the pipe 6 is lower than a threshold value representative of a temperature incompatible with the evaporation of the water salty, the desalination device may issue an alert. The heating blanket is installed in response to this alert.

[0120] In a particular configuration, the desalination device may be provided with a thermally insulating blanket. The thermally insulating blanket is arranged against the external walls of the pipe so as to reduce as much as possible the loss of calories from the walls of the pipe 6 to the outside. The calories present in the pipe 6 are used preferentially or exclusively to evaporate the water. It is possible that the thermally insulating blanket is also a heating blanket.

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 device (8a) and / or pressure increase device (8b) configured to condense the water vapor present in the air of the container (8) to recover the water devoid of salt.;

2. A device for desalination (la) of salt water by spraying according to claim 1 in which the at least one nozzle (5) is configured to deliver drops having a diameter of less than 0.1 mm.

3. A salt water desalination device by spraying according to claim 2 wherein the at least one nozzle (5) is configured to deliver drops having a diameter of less than 0.01 mm.

4. A salt water desalination device by spraying according to claim 3 wherein the at least one nozzle (5) is configured to deliver drops having a diameter of less than 0.001 mm.

5. A spray salt water desalination device according to any one of claims 1 to 4 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.

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

7. A salt water desalination device by spraying according to any one of claims 1 to 6 comprising a pipe (11) provided with a plurality of nozzles (5) arranged successively along an air flow defined by the air flow generator, wherein the pipe (11) is suspended inside the pipeline (6).

8. A salt water desalination device by spraying according to any one of claims 1 to 7 comprising heating means configured to heat walls of the pipe (6).

9. A salt water desalination device by spraying according to claim 8 when dependent on claim 7 in which the pipe (11) is suspended by a plurality of metal hangers (12) in thermal conduction with the walls of the pipe (6), the hangers (12) being swept by the air flow defined by the air flow generator (7).

10. A salt water spray desalination device according to any one of claims 7 to 9 wherein the pipe (6) has a top portion without a recess, the top portion extending continuously on either side of the pipe (11) from an altitude equal to an altitude of the pipe (11).

11. A salt water desalination device by spraying according to any one of claims 7 to 10 comprising at least one salt crystal collector (10) arranged under the pipe (11) and extending from one edge to the other of the pipe (6) in a horizontal direction and perpendicular to a longitudinal direction of the pipe (11), the at least one salt crystal collector (10) being mounted to move relative to the pipe (6).

12. A spray salt water desalination device according to any one of claims 7 to 11 wherein the airflow generator generates an airflow above the pipe (11) which has a greater velocity than an airflow below the pipe (11), the velocity being measured along a horizontal component of the longitudinal axis of the pipe (11).

13. A method of 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.

14. Method for desalination of a volume of salt water according to claim 13 by means of a desalination device according to one of claims 7 to 12 in which the salt water is projected against a wall of the pipe to carry out evaporation of the salt water in contact with the wall, the wall being a heating wall.

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