Membrane device

Abstract

The invention relates to a membrane exchanger comprising: - a membrane strip folded on itself along a fold (3), the fold separating the strip into a first flap (1) and a second flap (4), wherein a first rod (2) is arranged between the first flap (1) and the second flap (4), wherein the first flap (1) and the second flap (4) are fixed flat on the first rod (2); - a device for distributing a fluid located between the first flap (1) and the second flap (4); - a second rod positioned at the fold of the membrane device and a tensioning system connected to the second rod, the tensioning system being configured to apply a tension at the fold in a direction opposite to the first rod.

Description

Description Title of the invention: Membrane device TECHNICAL FIELD OF THE INVENTION

[0001] This application relates to the general field of membrane heat exchangers. In particular, the invention relates to membrane heat exchangers comprising at least one pair of membranes arranged opposite each other. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] A membrane exchanger is a device that allows for the selective transfer of matter between two media through a membrane.

[0003] Membrane heat exchangers can be used, for example, to dehumidify air or to purify a liquid (such as desalinating water). For this purpose, membrane heat exchangers can comprise two membranes arranged opposite each other, thus defining a fluid circulation zone. This fluid circulation zone is separated, by the two membranes, from two other zones—for example, air zones. Patents EP 2 094 376 B1 and EP 3 827 211 B1, as well as application WO 2024 / 200108 A1, disclose examples of such membrane heat exchangers.

[0004] To avoid deformation of a membrane in such membrane exchangers, each of the membranes is conventionally mounted on a four-sided frame, considered mechanically necessary, and stretched over this frame.

[0005] The membrane is stretched to be free of surface creases and to compensate for deformations caused by variations in membrane temperature and pressure on either side of the membrane, preventing the membrane from relaxing and contaminating a purified distillate through contact. For example, a porous membrane in contact with a distillate, which contains in its pores possibly partially purified retainat or permeate, and which comes into contact with a distillate present on a condenser, will contaminate the distillate with the contents of its pores.

[0006] A membrane suitable for a membrane exchanger must therefore be free of surface folds or creases or undulations and it must be sufficiently taut, i.e. stretched flat, so as not to deform enough to touch the elements of the exchanger that are adjacent to it.

[0007] This pollution problem is all the more significant when the membranes are flexible and thin, because they are also, therefore, deformable in the absence of tension or when they are poorly stretched or relaxed.

[0008] The more membranes there are on a frame, the more pronounced the problem becomes. To keep two membranes flat and parallel, it is possible either to stretch the membranes on either side of the frame, or to stack two frames on top of each other, each with a single membrane, without, however, reducing the risk of creases in the membranes and the associated risk of contamination.

[0009] Moreover, for industrial heat exchangers possibly including many plastic parts, especially frames, these are more easily deformed, particularly during temperature variations, and putting membranes under tension without deforming these frames is a difficult problem.

[0010] This problem is further exacerbated in the prior art by the need to increase membrane dimensions to improve heat exchanger efficiency through increased exchange surface area. For large membranes, typically exceeding one meter in height, the risk of surface folds developing during operation, rendering them unsuitable for applications such as the production of ultrapure liquids, is very high.

[0011] Therefore, there is a need for a solution to limit or prevent the appearance of folds and undulations on the surface of membranes in a membrane device. SUMMARY OF THE INVENTION

[0012] The invention improves the situation by proposing to replace the two membrane sheets of a membrane exchanger with a single membrane device comprising two flaps of the same membrane strip folded back on itself. The two flaps are fixed on one side to a first rod, and a second rod positioned at the fold allows the two flaps to be tensioned.

[0013] One aspect of the invention relates to a membrane exchanger comprising:

[0014] - a first membrane panel and a second membrane panel delimiting an area;

[0015] - a fluid distribution device located between the first membrane flap and the second membrane flap to distribute the fluid in the area;

[0016] characterized in that the first membrane flap and the second membrane flap correspond respectively to a first flap and a second flap of a membrane device, the membrane device comprising:

[0017] - a first stem (2) and a membrane strip, in which the membrane strip extends widthwise between a first edge and a second edge, in which the membrane strip is folded back on itself along a fold (3) separating the strip into the first flap (1) and the second flap (4), in which the first stem (2) is arranged between the first flap (1) and the second flap (4), in which the first flap (1) is fixed flat on the first stem (2) and in which the second flap (4) is fixed flat on the first stem (2), the first stem being separated from the fold;

[0018] and in that the membrane exchanger further comprises a second rod positioned at the fold of the membrane device and a tensioning system connected to the second rod, the tensioning system being configured to apply tension at the fold in an opposite direction to the first rod.

[0019] It is therefore understood that the tension is applied in a direction substantially perpendicular to the fold.

[0020] In one or more embodiments, the fold is parallel to the first stem.

[0021] In one or more embodiments, the fold is perpendicular to the first edge.

[0022] In one or more embodiments, the fluid is seawater.

[0023] In one or more embodiments, the first stem is in the form of a parallelepiped extending in thickness between a first face fixed to the first flap and a second face fixed to the second flap.

[0024] In one or more embodiments, the membrane exchanger is intended to purify the fluid in liquid phase or to dehumidify air.

[0025] In particular, the membrane exchanger may be intended to purify the fluid in the liquid phase; the membrane may be made of a material semi-permeable to the liquid phase of the fluid and permeable to the vapor phase of the fluid; and the fluid distribution device may be a nozzle (30) configured to distribute the fluid as droplets into an atmosphere. The membrane exchanger may further include a wall (90a, 90b) of a condenser (90), wherein the wall of the condenser (90) and a flap between the first and second flaps of the membrane device (50) delimit a first space (130), and wherein the condenser (90) includes a circulation circuit for a cooling fluid, the wall of the condenser (90) separating the cooling fluid circulation circuit from said first space (130), the wall of the condenser (90) being impermeable to the fluid in both the liquid and gaseous phases and being configured to condense the gaseous fluid that has passed through a flap of the membrane device into a purified liquid fluid phase.

[0026] The term "cooling fluid" refers to any fluid used to cool (i.e., lower the temperature of) an atmosphere or another fluid. For example, water at room temperature can be a cooling fluid.

[0027] Another aspect of the invention relates to a method for obtaining a membrane exchanger as defined above, comprising:

[0028] - to obtain a membrane device comprising a first rod (2) and a membrane strip, in which the membrane strip extends in width between a first edge and a second edge, in which the membrane strip is folded over itself along a fold (3) separating the strip into the first flap (1) and the second flap (4), in which the first rod (2) is arranged between the first flap (1) and the second flap (4), in which the first flap (1) is fixed flat on the first rod (2) and in which the second flap (4) is fixed flat on the first rod (2), the first rod being separated from the fold;

[0029] - insert the membrane device into the membrane exchanger, so that the fluid distribution device is positioned between the first flap and the second flap of the membrane device;

[0030] - apply tension at the fold in the opposite direction to the first rod.

[0031] In one or more embodiments, the membrane device is obtained by:

[0032] - folding the membrane strip over itself to form the first flap, the fold and the second flap;

[0033] - inserting the stem between the first flap and the second flap;

[0034] - fixing the first flap flat onto the first stem; and

[0035] - fixing the second flap flat onto the first rod.

[0036] The invention is likely to have industrial application in heat and material exchangers, particularly large ones, requiring several flexible membranes that must remain parallel to each other.

[0037] For example, the invention is particularly suited to the realization of a compact, lightweight, large-dimension membrane exchanger for each membrane as well as using several membranes, for the industrial production of ultrapure liquids. BRIEF DESCRIPTION OF THE FIGURES

[0038] Figure 1 represents a membrane device used to form two membranes of a membrane exchanger according to the invention.

[0039] Figure 2 illustrates an assembly of the two flaps in a membrane exchanger according to an embodiment of the invention.

[0040] Figure 3 represents a system for leveling the different elements of the membrane exchanger according to an embodiment of the invention.

[0041] Figure 4 represents a fluid purification device according to one embodiment of the invention.

[0042] Figure 5a and Figure 5b represent a membrane device according to another embodiment of the invention.

[0043] Figure 6 represents a method for obtaining a membrane exchanger according to an embodiment of the invention. DETAILED DESCRIPTION

[0044] One aspect of the invention relates to a membrane exchanger, for example a heat and mass exchanger or a fluid purification system, comprising two membranes arranged opposite each other. In the context of the invention, the two membranes belong to a membrane device comprising a single strip of membrane folded back on itself, the two folds of the membrane strip thus formed corresponding to the two membranes arranged opposite each other.

[0045] Such a membrane device is detailed with reference to Figure 1. This membrane device 50 is made from a membrane strip.

[0046] The membrane strip can be obtained by cutting a length from a roll of the membrane. This membrane strip can thus comprise two parallel edges of the membrane. The parallel strip is then folded back on itself (for example, by folding each edge back on itself) so as to form a first flap 1 and a second flap 4 separated by a fold 3.

[0047] Throughout this application, a fold is defined as a deformed area of ​​a surface resulting from folding the surface. Throughout this application, a fold separating two flaps is defined as parallel to a straight element, such as a rod, if the line furthest from the rod drawn on the fold is parallel to the straight element. The fold physically reduces to this line or fold axis when forces, such as pinching, are symmetrically applied to the flaps to bring them together and into contact. "Parallel" is always understood to mean "Virtually parallel", meaning that a few degrees of difference between the directions (for example less than 5° or less than 10°) are tolerated.

[0048] Equivalently, it is understood that a straight element in length conforming to the shape of the fold, in mechanical contact with it, materializes a direction parallel to the straight fold and that this direction tends towards the straight fold when the section of the straight element perpendicular to its length decreases.

[0049] It is noted that the membrane strip can, in advantageous embodiments, have parallel edges to facilitate its rolling into a roll. However, the invention also applies to a strip with non-parallel edges mounted flat on a rod.

[0050] Referring again to Figure 1, a straight rod 2 is inserted between the two flaps 1 and 4. The term "rod" means any element having a dimension, along a principal direction, that is significantly larger (for example, at least 10 times larger) than its dimensions in other directions. "Straight" means that the rod has a straight shape along its principal direction. For example, the rod 2 can be positioned between the two flaps so that its principal direction is substantially perpendicular to the edges of the membrane strip. "Substantially perpendicular" means that the angle formed between the edges and the principal direction is between 80° and 100°. In some embodiments, the rod may be made of a material sufficiently rigid so as not to deform (in particular, not to bend or curve) when a force is applied at the fold 3 to tension the two flaps of the membrane device 50.For example, the stem could be a parallelepiped-shaped plastic plate.

[0051] In some embodiments, the rod 2 can have a thickness e of between 5 and 20 mm (see Figure 1). These dimensions are not limiting to the invention.

[0052] The stem 2 is advantageously positioned at a distance from the fold 3, the edges (folded down), the stem 2 and the fold 3 forming a substantially rectangular space which defines an area, called the "exchange zone", in which exchanges can take place within the membrane exchanger.

[0053] By "positioned at a distance", it is understood that the rod 2 is not in contact with the fold 3. In general, the greater the space left between the rod 2 and the fold 3, the greater the exchange surface via the two flaps of the membrane.

[0054] Once positioned between the two flaps 1 and 4, the rod 2 is glued to the first The first flap 1 is glued so that it is bonded without any surface creases relative to the stem (i.e., there are no creases along the bond). The stem is also glued to the second flap 4 in the same way. For example, the stem can be glued to the first flap 1 and the second flap 4 "flat," that is, by placing the membrane strip and the stem 2 on a flat surface substantially parallel to the ground, so as to minimize bond creases. Any other method of attachment besides gluing is suitable for the invention.

[0055] A flat fixing on a material element such as a membrane stem means that the fixing is carried out without surface folds for the membrane or with a smooth surface of that membrane.

[0056] This gives us a membrane device 50 with parallel edges comprising two flaps (therefore two membrane flaps) fixed to the rod 2.

[0057] It is noted that rod 2 can be obtained by fixing two pieces of rod, as shown in figures 5a and 5b. In figure 5a, two pieces of rod 2a, 2b are fixed to the two opposite edges of strip 1, 4. In this example, the two pieces of rod 2a, 2b have a length similar to that of rod 2. Strip 1, 4 is then folded over itself, so as to overlap the two pieces of rod 2a, 2b, which can then be fixed to each other to form rod 2 (see figure 5b).

[0058] Thus, it is understood that the rod 2 according to the invention can be formed from several elements fixed to one another. Furthermore, it is noted that, even if the dimensions of the rod pieces 2a and 2b in Figures 5a and 5b are identical, this is not mandatory.

[0059] As mentioned previously, the membrane device 50 is placed in a membrane exchanger, such as a heat and / or mass exchanger, to replace two "simple" membranes (i.e., each consisting of a single flap) positioned opposite each other, for example, between two condensers. The space between the two flaps defines a heat exchange zone, in which a fluid distribution device can be positioned. The fluid distribution device can be, for example, a spray nozzle or an outlet connected to a liquid dispenser.

[0060] In such heat exchangers, obtaining a sufficiently taut membrane without any undulations, folds, or waves on its surface can be challenging. This problem is overcome by membrane device 50.

[0061] The membrane device 50 is thus used to replace two membranes of the system. For this, a second rod can be inserted at the fold to "stretch" the two flaps 1, 4 of the membrane device 50, so as to remove as much as possible the folds and undulations of the flaps of the membrane device 50 and to form two substantially parallel sheets of membrane positioned opposite each other.

[0062] The membrane device can, for example, be inserted between two condensers, so as to pass through the condenser zone.

[0063] Then a second rod can be inserted between the flaps of the membrane device at the fold. Depending on the embodiment, a stress can be applied to the second rod outwards (i.e., in a direction opposite to the first rod 2, perpendicular to the fold 3). In other embodiments, equal and opposite tensile stresses can be applied to the two rods to tension the two flaps of the membrane device.

[0064] The second rod is a straight rod, which may or may not be identical to the first rod. The second rod may have the same thickness as the first rod, to keep the two flaps parallel or nearly parallel.

[0065] Since the shape of the fold is materialized by the second rod, the adjustment of the fold is equivalent to that of this second rod pressed on the fold, as soon as the second rod puts tension on the flaps of the membrane device.

[0066] This observation can be used in an embodiment of the fold adjustment during the mounting of the membrane device onto the first rod. In this setup, a second rod of the same thickness as the first rod is inserted between the flaps, secured, and used as a mechanical reference by pressing the fold against this second rod. The first flap is then fixed flat onto the first rod without tension on the membrane device, and tension is applied to the membrane, which forces it onto the second rod. Next, the surface folds of the membrane device are smoothed out by adjustments, and the second flap is then fixed, which is necessarily fixed flat and without surface folds on the rod since the membrane device is completely free of folds across its entire surface. The applied tension can be chosen as the minimum tension allowing for the absence of folds on the membrane, given the chosen adjustments.

[0067] To apply the equal and opposite or symmetrical constraints in the plane of the flaps, mentioned above, a tensioning system can be used, for example, a system comprising springs arranged between a frame that is more rigid than the existing rods and these rods. Advantageously, these springs They can be adjusted to maintain the tension of the flaps.

[0068] To apply these equal and opposite or symmetrical constraints outside the plane of the membrane, it is possible to use shims which can have the shape of combs that can accommodate the rods to immobilize them in a direction perpendicular to the flaps, as shown in Figure 3 described in detail below.

[0069] It is noted that folding a membrane by creasing it is also a way to create a straight fold, but with the risk of weakening the membrane strip at the fold. Supporting a second rod on the fold area allows the fold to be oriented relative to the first rod, without weakening the membrane strip at the fold.

[0070] It is understood that any means of fixing a rod to the membrane other than gluing, such as screwing, is usable for this application.

[0071] As mentioned above, the membrane device in Figure 1 can be used in a membrane exchanger requiring two facing membranes. In such membrane exchangers, a fluid distribution device (for example, for a liquid or droplets) is generally placed between the two membranes. The membrane device described above can advantageously be used to replace the two membranes, with each flap of the membrane strip corresponding to one of the membranes.

[0072] An example of a membrane heat exchanger according to the invention is shown in Figure 4. The membrane heat exchanger in Figure 4 is intended for purifying a fluid in the liquid phase. Of course, the invention is not limited to the example of a membrane heat exchanger in Figure 4, nor to a membrane heat exchanger intended for purifying a fluid in the liquid phase. For example, the invention can be used for membrane heat exchangers intended for dehumidifying air.

[0073] The membrane exchanger of Figure 4 comprises a plurality of membrane devices 50 that are permeable to the fluid in the gaseous phase (i.e., permeable to the vapor of this fluid) and semi-permeable to the fluid in the liquid phase. More precisely, the membrane devices 50 are impermeable to the fluid in the liquid phase when the latter is, for example, projected against the membrane devices 50 in the form of droplets, the aim being that, in the context of the invention, only gaseous particles of the liquid can pass through the membrane devices 50. The membrane devices 50 are membrane devices similar to those in Figure 1.

[0074] The term "semi-permeable to fluid in the liquid phase" refers, in the context of the invention, to a property of the membrane whereby liquid droplets do not pass through the membrane when they come into contact with it as it extends in a substantially vertical direction, for example, when it is positioned substantially perpendicular to the ground (assuming that the ground is not sloped and thus extends in a horizontal plane). However, the membrane can become permeable to liquid when subjected to significant liquid pressure (for example, when a jet of liquid is directed against the membrane). For example, a non-absorbent membrane for liquid droplets, a membrane made of a water-repellent material, or a membrane coated with a water-repellent material, which do not allow liquid droplets to pass through, falls within the scope of the present invention.

[0075] The system also includes a plurality of condensers (or cold traps) 90. A condenser is defined as a device configured to condense (or liquefy) vapor. For example, each condenser may be a flat-plate condenser comprising two walls 90a, 90b between which is a cooling fluid circulation circuit. The walls 90a, 90b of the condenser 90 are advantageously impermeable to fluids (in both liquid and gaseous phases).

[0076] The system further includes nozzles 30 for distributing a fluid in the form of droplets between the two flaps 1, 4 of the membrane devices 50. Thus, each membrane device 50 receives, between its two flaps 1, 4, droplets distributed by a respective nozzle.

[0077] The flaps 1 and 4 of the membrane devices 50 do not allow droplets of the liquid dispensed by the nozzles 30 to pass through. For example, the membrane devices 50 can be impermeable to liquid droplets. The membrane devices 50 can be made, for example, from membranes of one or more of the following materials: Teflon or PTFE, Polyvinyldiene Fluoride or PVDF, Polypropylene or PP, and Polyethylene or PE. The pore thickness of the membrane devices 50 can be determined by routine testing by a person skilled in the art, and in particular, pore sizes ranging from 60 micrometers to 60 nanometers can be used. In some embodiments, the membrane devices 50 can be made of a fabric coated with a treatment to make it impermeable.

[0078] The material used to make the wall of a condenser or cold trap can be a metal or a heat-conducting material. Stainless steel, for example, or plastic, can be used, especially if the cold liquid circulating in the condenser is salt water or corrosive water.

[0079] Referring again to Figure 4, membrane devices 50 and condensers 90 are arranged alternately, so that exactly one membrane device 50 is arranged between two condensers 90.

[0080] A membrane device 50 arranged between two consecutive condensers 90 defines a space 40 between its two flaps 1, 4. This space is surmounted by a nozzle 30 configured to distribute a fluid in the liquid phase as drops or droplets. This space constitutes a "first fluidic channel" 40 through which the fluid distributed by the nozzle 30 flows. A "fluidic channel" is understood to be a volume through which a fluid can flow or circulate, in liquid or gaseous phase. A fluidic channel can advantageously be delimited by two separators (for example, flaps of a membrane device 50 and / or the walls of condensers 90), which maximizes the surface area for heat exchange or mass exchange, such as for vapor flow.

[0081] The space 130 between a condenser 90 and the flap of the membrane device 50 closest to the condenser 90 is called the "second fluidic channel" 130. Each second fluidic channel 130 may include a gutter 110 or any other means of recovering a liquid formed by condensation on the condenser 90. The gutter 110 may be connected to a purified or pure water collector 120.

[0082] Thus, in Figure 4, the channel 40 and the condenser 90 are separated by a small tank or gutter 110 allowing to collect water droplets in liquid water from the surface of the wall 90a, 90b of the condenser 90. The first channel 40, the nozzle 30, the gutter 110 and the condenser 90 form a periodic pattern repeated in Figure 4, between a hot water distributor 20 and a hot water collector 60 connected via the channel 40 containing the nozzle 30 and between a cold water distributor 80 and a cold water collector 100 connected via the condenser 90.

[0083] One aspect of the invention can be implemented provided that the device comprises a nozzle 30, a membrane device 50, and a condenser 90, the membrane device 50 being located between the nozzle 30 and the condenser 90. Thus, the invention is not limited to a plurality of nozzles 30, condensers 90, and membrane devices 50. When the device includes a plurality of these elements, the volume of purified liquid collected is greater, since purified liquid can be collected in parallel in several channels each lined by a membrane device 50 and a condenser wall 90a, 90b 90, for example via several gutters like the gutter 110.

[0084] Figure 4 thus shows a hot water supply 10 connected, in the fluid sense, via a hot water distributor 20 to the nozzle 30 disposed internally to the membrane of the channel 40 and a hot water collector 60 extending the channel 40.

[0085] Figure 4 also shows a cold water supply 70 connected to the condenser 90 via a cold water distributor 80 which is connected, in the fluidic direction, to a cold water collector 100 via the condenser 90.

[0086] In Figure 4, the membrane devices 50 and the walls 90a, 90b of the condensers 90 are vertical and parallel surfaces. It is understood that the degree of parallelism of these elements may, without departing from the scope of this application, be imperfect. In particular, it is essential that a fluid in the vapor phase can reach a wall of the condenser 90 via the channel 40. The verticality of the membrane devices 50 and the walls 90a, 90b of the condensers 90 is therefore to be understood in this application as a characteristic enabling the maximization of vapor-to-liquid conversion between the interior of the membrane device 50 of the first channel 40 and the surface of the wall 90a, 90b of the condenser 90, while facilitating the collection of condensate by the gutter and minimizing the overall size of the device.From this point of view, the "vertical" characteristic, in the geometric sense, can be understood in the sense of the present invention and in all its embodiments as forming an angle, for example, between 70° and 110° with respect to the ground.

[0087] According to one aspect of the invention, a hot, unpurified liquid (the liquid may be a mixture, for example, of water and minerals or water and salt or solutes) is introduced by a feed 10, then distributed by a hot liquid distributor 20 to nozzles 30 which disperse it vertically in the form of droplets inside the channels 40. For example, the hot, unpurified liquid may be water from a water reservoir, for example a sea or a lake or a wastewater reservoir, possibly heated to a first temperature referred to as "hot".

[0088] A second liquid, called refrigerant, which is colder than the liquid hot, is introduced by a supply 70, then distributed by a cold liquid distributor 80 which distributes it into the condensers 90 arranged in parallel on figure 4.

[0089] The term "hot liquid" refers to a liquid with a temperature higher than the maximum temperature of the refrigerant circulating in the condenser 90. For example, the difference between the temperature of the hot liquid (when dispensed as droplets from the nozzles 30) and the maximum temperature of the refrigerant circulating in the condenser 90 can be greater than 30°C. For instance, the hot liquid can be dispensed as droplets at a temperature between 60°C and 90°C, and the refrigerant can have a temperature between 10°C and 30°C. Of course, the preceding temperatures are given as examples, and other temperatures or temperature differences may be used.

[0090] After being dispensed as droplets by the nozzle 30, the hot, unpurified liquid flows through the channel 40, delimited by two flaps 1 and 4 of a membrane device 50. A portion of this hot, unpurified liquid passes through the flaps of the membrane device 50 as purified fluid vapor. For example, if the hot, unpurified liquid is salt water, some of this liquid passes through the flaps of the membrane device 50 as pure water vapor. What remains in the channel 40, delimited by the two membrane devices 50, is even less purified liquid (i.e., more concentrated in at least one of its components, for example, water with an even higher salt content, since some of the pure water has evaporated) and cooler liquid than at the nozzle 30 outlet. This saltier and cooler liquid can then be collected in a collector 60.

[0091] Indeed, the role of the membrane device 50 is to prevent the liquid distributed as droplets in the channel 40 from partially or totally passing into the zone 130 delimited by a condenser 90 and a flap of the membrane device 50. Only vapor from the liquid can pass through, thus preventing any contact between the hot liquid in the channel 40 and the vapor condensates formed in zone 130 on the wall of the condenser 90. When a temperature difference is created between the two sides of the membrane device 50, a partial pressure difference of vapor appears, which drives the process. This causes the liquid on the surface of the hot liquid to evaporate, generating vapor that passes through the membrane device 50 and... condenses on the colder side where the condenser 90 is located.

[0092] The space between a condenser 90 and a flap of the membrane device 50 forms a channel through which the vapor from the hot liquid exiting the nozzle 30 and passing through the flap of the membrane device 50 diffuses. The role of the condensers 90 is to condense this vapor on one of their walls 90a, 90b to form purified liquid. This purified liquid is cooler than the vapor from which it originates, while conversely, the refrigerant liquid heats up through contact—via the wall 90a, 90b of the condenser 90—with the warmer vapor.

[0093] The refrigerant liquid can be collected at the outlet of the condenser circulation circuit 90 in a cold liquid collector 100, at a temperature higher than that which it had at the inlet of the condenser circulation circuit 90.

[0094] The condensate (purified water, for example) slides down the wall of the condenser 90 and can be collected in the gutter 110, which is placed, for example, on the wall (several gutters can also be installed along the height of the condenser 90). The condensate can then be conveyed laterally to be collected in a pure water tank or collector 120.

[0095] According to alternative methods, the gutter or gutters 110 can either be attached to the condensers by mechanical fixing of the material composing this gutter or these gutters, or delimited by the external shape of the condenser or condensers by molding, that is to say delimited by the wall of a condenser, i.e. by the shape of its external surface on which condensation is obtained.

[0096] It is noted that in the example of Figure 4, the elements of the device are arranged in the following order, parallel to the membrane devices 50 and oriented from the cold water manifold 100 and the refrigerant distributor 80: the cold water manifold 100, the hot water distributor 20, the hot water manifold 60, and the refrigerant distributor 80. This arrangement allows for reverse or counter-current circulation of the liquids in the channel 40 and the refrigerant circulation circuit in the condenser 90. This counter-current circulation advantageously enables particularly efficient heat exchange between the hot droplets produced by the nozzle 30 and the cold liquid via the membrane device 50 and the wall 90a, 90b of the condenser 90.

[0097] Other configurations are possible, and according to an alternative embodiment of the invention, the elements of the device can be arranged in the following order, along the direction parallel to the membrane devices 50 and oriented from the cold water manifold 100 and the refrigerant distributor 80: the cold water manifold 100, the hot water manifold 60, the hot water distributor 20 and the refrigerant distributor 80. In this case, the circulation of the liquids in the channel 40 and the circulation circuit of the cooling fluid in the condenser 90 is carried out in the same direction, and the invention is still functional, even if the heat exchanges are less efficient than in embodiments where the circulation of the liquids is in the opposite direction.

[0098] As mentioned above, the invention can be implemented by means of a hot water or hot fluid supply 10, distributed as droplets by a nozzle 30, creating vapor of the (purified) fluid and droplets of the fluid (even less pure than the hot fluid distributed by the nozzle 30). The fluid vapor passes through the vapor-permeable, droplet-impermeable membrane device 50 to reach a fluid-impermeable wall 90a, 90b. The wall 90a, 90b is supplied with a cooling fluid via a cold water supply 70. The cooling fluid is injected between the walls of the condenser 90 at a second temperature lower than the first temperature. Thus, condensation of the fluid into purified water droplets occurs on a surface of the wall 90a, 90b, against which cold water or a purified cold fluid flows at a temperature lower than the first temperature.

[0099] As mentioned above, the invention is not limited to the example of a membrane exchanger in Figure 4, and extends to any membrane exchanger using at least one pair of membranes arranged opposite each other and substantially parallel.

[0100] For example, in some embodiments, the spray nozzle 30 of the system in Figure 4 can be replaced by a liquid-forming fluid distribution device configured to inject a liquid into the area 40, so that a part of this liquid passes through the semi-permeable membrane 10 as pure liquid vapor.

[0101] Purifying a fluid is not the only possible application of a membrane exchanger according to the invention. The membrane exchanger can also be used as a system for dehumidifying air, such as the system described in patent EP 3 827 211 B1.

[0102] In other embodiments, the membranes of a membrane exchanger According to the invention, they can be subjected to hydraulic pressure imposed by a pump on one side and to atmospheric pressure on the other; part of the overpressure applied to the membrane via the devices of the invention to keep it flat can also be used to compensate for deformations of the membranes caused by the pressure difference on either side of the membrane, in order to prevent contact between the membranes or between the membranes and other elements such as a condenser or cold wall.

[0103] In general, the invention makes it possible to achieve, by adjusting the assembly of the exchanger, a configuration of the membrane device in which all the flaps are taut without surface folds and are therefore flat, as when the membrane device is assembled.

[0104] Advantageously, the first stem and the fold can extend in parallel (or substantially parallel) directions, to allow simplified adjustments to remove folds on the flaps of the membrane device during its assembly.

[0105] Advantageously, the first stem or fold can extend in directions perpendicular to the edges of the parallel-edged strip used to form the membrane device, to simplify adjustments.

[0106] It is noted that the dismantling of torn or worn membranes is made possible by the invention by performing the reverse operations of those performed for assembly in an exchanger, which facilitates maintenance of exchangers using the invention.

[0107] Many embodiments using straight rods of any given invariant section along an axis or using different materials of variable rigidity are conceivable for the invention without departing from its teaching.

[0108] The invention is particularly suited to the production of exchangers using larger membranes exceeding one meter, such as two meters, and ensuring their operation with flat membranes in all circumstances provided for in a specification.

[0109] In all embodiments of the invention, plastic rods can be used to minimize the weight of the membrane device.

[0110] The invention thus makes it easy to obtain a taut membrane surface free of folds or undulations, and also makes it possible to obtain a plurality of membrane surfaces arranged opposite each other without any folds. of surface on one or the other of these surfaces.

[0111] In some embodiments, the first rod may be made of a deformable material. Indeed, adjusting the bend and the first rod to its shape during assembly ensures that restoring the same shape to this first rod and the bend in an industrial environment will achieve this result. For example, inserting a second rod, even a deformable one, between the first rod and the bend, in contact with the bend, and applying first mechanical means for adjusting the shape of the first rod and second means for adjusting the shape of the second rod relative to the first rod or to a common reference with the first rod, can be implemented to obtain the result of the invention.

[0112] It is observed that the element according to the invention can be inserted between two condensers of a membrane exchanger, by sliding the membrane between the condensers without passing the first rod between the condensers, which facilitates and secures the assembly and possible disassembly of the element according to the invention in the membrane exchanger.

[0113] Any membrane, particularly a flexible one, possessing the properties required for the intended application can be used to obtain a membrane device according to the invention. Depending on the rigidity of the membrane, the thickness between the flaps at the fold may vary without being reduced to a folding axis; the fold will then be taken, for the purposes of adjusting the stem, as the line drawn on the fold that is furthest from the flaps.

[0114] Another aspect of the invention relates to a method for obtaining a membrane exchanger as described above. The membrane exchanger thus comprises two substantially parallel membrane sheets arranged opposite each other. The two flaps of the membrane device form the two membrane sheets.

[0115] One such method of obtaining it is shown in Figure 6.

[0116] In step 610, a strip of membrane is obtained. This strip is then folded over itself to form a first flap 1 and a second flap 4 separated by a fold 3, as described above, in step 615.

[0117] A rod 2 is inserted between the two flaps 1, 4, at a distance from the fold 3 during a step 620.

[0118] The rod 2 is then fixed flat onto the first flap 1 in step 625 and fixed flat onto the second flap 4 in step 630. At the end of step 630, the membrane device of Figure 1 is thus obtained. It is understood that, according the embodiments, the manufacture of the membrane device is carried out upstream, and is not part of the process of obtaining a membrane exchanger according to the invention.

[0119] The membrane device can then be inserted, in a step 635, into a membrane exchanger comprising a fluid distribution device, so that the fluid distribution device is positioned between the first flap and the second flap of the membrane device.

[0120] Finally, in step 640, tension is applied to the fold, in the opposite direction to the first stem. This step 640 allows the two flaps 1, 4 of the membrane device to be stretched and eliminates any fold or undulation on the surface of either of these flaps 1, 4.

[0121] To achieve this, a second rod can be attached to one end of the membrane exchanger frame. The first rod can then be positioned on the opposite end of the frame.

[0122] To ensure that the flaps are sufficiently taut without subjecting them to excessive stress during membrane device positioning that could damage them, an adjustable tensioning system can be used. This system allows the first and second rods to be moved further apart to restore the membrane device to its initial shape after assembly (i.e., in which both flaps are taut and flat, without creases or ripples). This tension can be applied at several points along the vertical axis. The adjustable tensioning system could be, for example, a spring / threaded rod assembly that allows for spring tension adjustment.

[0123] Figure 2 illustrates an example of implementing a power-up of the device so as to eliminate surface folds and undulations on the two flaps of the membrane device when installing it in the membrane exchanger.

[0124] As shown in Figure 2, the membrane device is first inserted into the membrane exchanger, so that the first rod 2 and the second rod 22 are brought close together (a). Then, the first rod 2 is moved away from the second rod 22 by unfolding the flaps 1, 4 of the membrane device to a second position (b). Finally, the first rod 2 and the second rod 22 are pulled by a tensioning system (here, at least one spring 23) to bring the membrane device into a flat position (c).

[0125] Longitudinal tension is associated with lateral physical separation (under comb shape) to maintain the planned geometric spacings between elements of the membrane exchanger (e.g., condensers) and the frames, or between the different frames of the membrane exchanger.

[0126] Such a lateral physical separation is shown in Figure 3, in the case of the membrane exchanger in Figure 4. In this example, the lateral physical separation is used to separate the frames of the membrane devices 50 from the condensers 90.

[0127] Figure 3 thus represents condensers 90 and membrane frames receiving membrane devices 50 lying flat in a plane. These condensers 90 and these membrane frames are held at a distance by a comb 33 which alternately receives and locks these condensers and frames in a plane perpendicular to the condensers and the membrane frames.

[0128] Of course, the invention is not limited to the examples provided above, it extends to other variants.

Claims

DEMANDS

1. Membrane exchanger comprising: - a first membrane panel and a second membrane panel delimiting an area; - a fluid distribution device located between the first membrane flap and the second membrane flap for distributing the fluid in the area; characterized in that the first membrane flap and the second membrane flap correspond respectively to a first flap and a second flap of a membrane device, the membrane device comprising: - a first rod (2) and a membrane strip, wherein the membrane strip extends widthwise between a first edge and a second edge, wherein the membrane strip is folded back on itself along a fold (3) separating the strip into the first flap (1) and the second flap (4), wherein the first rod (2) is disposed between the first flap (1) and the second flap (4), wherein the first flap (1) is fixed flat on the first rod (2) and wherein the second flap (4) is fixed flat on the first rod (2), the first rod being separated from the fold; and wherein the membrane exchanger further comprises a second rod positioned at the fold of the membrane device and a tensioning system connected to the second rod, the tensioning system being configured to apply tension at the fold in a direction opposite to that of the first rod.

2. Membrane exchanger according to claim 1, wherein the fold (3) is parallel to the first rod (2).

3. Membrane exchanger according to any one of claims 1 to 2, wherein the fold is perpendicular to the first edge.

4. Membrane exchanger according to any one of claims 1 to 3, wherein the first rod is in the form of a parallelepiped extending in thickness between a first face fixed to the first flap and a second face fixed to the second flap.

5. Membrane exchanger according to any one of claims 1 to 4, intended for purifying fluid in liquid phase or for dehumidifying air.

6. Membrane exchanger according to the preceding claim, wherein the membrane exchanger is intended to purify the fluid in liquid phase, wherein the band is made of a material semi-permeable to a liquid phase of a fluid and permeable to a vapor phase of the fluid, wherein the fluid distribution device is a nozzle (30) configured to distribute the fluid in the form of droplets in an atmosphere, wherein the membrane exchanger further comprises a wall (90a, 90b) of a condenser (90);in which the condenser wall (90) and a flap between the first flap and the second flap of the membrane device (50) delimit a first space (130), and in which the condenser (90) comprises a circulation circuit for a cooling fluid, the condenser wall (90) separating the cooling fluid circulation circuit and said first space (130), the condenser wall (90) being impermeable to the fluid in liquid and gaseous phases and being configured to condense the gaseous phase fluid passing through a flap of the membrane device into a liquid phase of purified fluid.

7. A method for obtaining a membrane heat exchanger comprising a fluid distribution device, the method comprising: - to obtain a membrane device comprising a first rod (2) and a membrane strip, in which the membrane strip extends in width between a first edge and a second edge, in which the membrane strip is folded over itself along a fold (3) separating the strip into the first flap (1) and the second flap (4), in which the first rod (2) is arranged between the first flap (1) and the second flap (4), in which the first flap (1) is fixed flat on the first rod (2) and in which the second flap (4) is fixed flat on the first rod (2), the first rod being separated from the fold; - insert the membrane device into the membrane exchanger, so that the fluid distribution device is positioned between the first flap and the second flap of the membrane device; - apply tension at the fold in the opposite direction to the first rod.

8. A method according to the preceding claim, wherein the membrane device is obtained by: - folding the membrane strip over itself to form the first flap, the fold and the second flap; - inserting the stem between the first flap and the second flap; - fixing the first flap flat onto the first stem; and - fixing the second flap flat onto the first rod.

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