Air gap membrane distillation assembly and method for controlling assembly

Abstract

The present invention relates to an air-gap membrane distillation assembly (1) for providing purified water, the air-gap membrane distillation assembly (1) comprising an air-gap membrane distiller (2) configured for producing purified water, a water supply unit (3), and a reservoir (4) connected to the air-gap membrane distiller (2) wherein the air-gap membrane distiller (2) comprises: an evaporation chamber (7); a condensation chamber (8); a membrane (9) separating the evaporation chamber (7) from the condensation chamber (8) wherein the membrane has a pore size equal to or less than 1000 nanometers; a cooling chamber (30) located in the vicinity of the condensation chamber (8); and a film (31) separating the cooling chamber (30) and the condensing chamber (8) from each other. The air gap membrane distillation assembly (1) comprises a pressure control device configured to maintain the pressure in the evaporation chamber (7) equal to or greater than 0.1 bar (e) and equal to or less than 1 bar (e) and configured to control the pressure difference between the evaporation chamber (7) and the condensation chamber (8) equal to or less than 1 bar.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to a gas gap membrane distillation assembly configured for removing particles / pollutants from water, i.e. producing purified / clean water to be used in industrial applications. More specifically, the present invention relates to a gas gap membrane distillation assembly capable of producing nano / ultra-purified water that does not contain any particles larger than 10 nanometers. Such a gas gap membrane distillation assembly according to the present invention is based on a thermally driven process, i.e. the raw water side is at a higher temperature than the purified water side, thus, the vapor pressure gradient between the raw water side and the purified water side is the driving force for the liquid to evaporate and the vapor to be transported through the membrane from the raw water side to the purified water side, the vapor thus condensing back to liquid at the purified water side.

[0002] The present invention relates in particular to a gas gap membrane distillation assembly for providing purified water, the gas gap membrane distillation assembly comprising:

[0003] - a gas gap membrane distiller configured for producing purified water;

[0004] - a water supply unit connected with the gas gap membrane distiller and configured for supplying water to the gas gap membrane distiller; and

[0005] - a reservoir connected with the gas gap membrane distiller, the reservoir being configured for intermediate storage of purified water,

[0006] wherein the gas gap membrane distiller comprises an evaporation chamber, a condensation chamber, a membrane separating the evaporation chamber and the condensation chamber from each other, wherein the membrane has a pore size equal to or smaller than 1000 nanometers, a cooling chamber located in the vicinity of the condensation chamber, and a thin film separating the cooling chamber and the condensation chamber from each other.

[0007] The present invention also relates to a method for controlling such a gas gap membrane distillation assembly.

[0008] The gas gap membrane distillation assembly is particularly useful in the semiconductor manufacturing industry, where semiconductor wafers along a production line are subjected to several washing steps using purified water. BACKGROUND

[0009] The present invention is based on the fact that semiconductors are becoming smaller and smaller in order to meet the demand for faster and cheaper electronic devices that consume less energy. Thus, the semiconductors / structures on a silicon wafer are becoming smaller and the distance between them is becoming smaller in order to have the wafer comprise more semiconductors / structures.

[0010] Therefore, to prevent short circuits and malfunctions of semiconductors, the need to wash wafers more efficiently to prevent very small contaminants also increases, and therefore the water used must be ultra-purified water, so that the water does not contaminate the wafers. To obtain the required washing results, the washing of the wafers consumes a large amount of ultra-purified water, however, the production of ultra-purified water is time-consuming and energy- requiring, and the service life of the produced ultra-purified water is short, i.e. less than 30 minutes. In addition, the transport of the purified water in tanks or pipes causes contamination, i.e. based on the current increase in contamination and based on the contamination of additional materials from the tanks / pipes. The known air gap membrane distillation assemblies cannot manage to produce the required volume of purified water, because the known technology is too slow.

[0011] The known solutions, such as direct contact membrane distillation, try to maximize the production of water by having a pressure difference across the membrane in addition to the temperature difference between the evaporation chamber and the condensation chamber, or by having an increased temperature difference.

[0012] However, when there is a higher or increased temperature difference between the evaporation chamber and the condensation chamber, the system becomes more sensitive to temperature fluctuations in the evaporation chamber and the condensation chamber. Temperature fluctuations in the system are normal in this method, in particular due to the varying output / use of the purified water. When there is a large output / use of purified water, new raw water must be added, the added raw water has a much lower temperature than the optimal temperature in the evaporation chamber, and during the heating of the raw water, the temperature will fluctuate, which is very difficult or impossible to predict. According to the known solutions, the raw water is heated in the condensation chamber, causing a large temperature change. According to the known solutions, the only way is to ensure the correct temperature before allowing the water purification process to continue, i.e. by forcibly interrupting the process. This has a great negative impact on the production line using purified water due to the inefficiency and interrupted purification process.

[0013] Temperature fluctuations have direct technical disadvantages and effects, i.e. the pressure difference between the evaporation chamber and the condensation chamber also increases and fluctuates uncontrollably, resulting in insufficient purification of the water. Sometimes the vapor pressure gradient is too low, and sometimes it forces the water through the membrane.

[0014] Therefore, there is a need for a device configured to produce a large amount of ultra-purified water efficiently close to the point of use, i.e. at the washing station in the clean room, when in use. In addition to using purified water as a washing agent, it can also be used as a solvent in different industrial applications.

[0015] Object of the invention

[0016] The object of the present invention is to eliminate the disadvantages and shortcomings of the previously known air gap membrane distillation assemblies and to provide an improved air gap membrane distillation assembly.

[0017] The main object of the present invention is to provide an improved gap membrane distillation assembly of the initially defined type, which always provides the required volume of purified water and which can be used in a clean room of a semiconductor / wafer manufacturing plant. Another object of the present invention is to provide a gap membrane distillation assembly which always provides the required purity of purified water. Another object of the present invention is to provide a gap membrane distillation assembly in which the degree of purification of the purified water is increased. Another object of the present invention is to provide a gap membrane distillation assembly which consumes less tap water. SUMMARY

[0018] According to the invention, at least the main object is achieved by a gap membrane distillation assembly and a method of the initially defined type having the features defined in the independent claims. Preferred embodiments of the invention are also defined in the dependent claims.

[0019] According to a first aspect of the present invention, there is provided a gap membrane distillation assembly of the initially defined type, characterized in that the gap membrane distillation assembly comprises a pressure control device configured to maintain a pressure in the evaporation chamber equal to or greater than 0.1 bar (e) and equal to or less than 1 bar (e), and configured to control a pressure difference between the evaporation chamber and the condensation chamber equal to or less than 1 bar.

[0020] According to a second aspect of the present invention, there is provided a method for controlling such a gap membrane distillation assembly, wherein the method is characterized by the following steps:

[0021] - providing a pressure in the evaporation chamber equal to or greater than 0.1 bar (e) and equal to or less than 1 bar (e), and

[0022] - controlling a pressure difference between the evaporation chamber and the condensation chamber equal to or less than 1 bar.

[0023] Accordingly, the present invention is based on the insight / finding that it is of great importance to be able to continuously guarantee that water is never forced through the membrane from the evaporation chamber to the condensation chamber, and that the vapor pressure gradient is at an optimal level in order to maximize the continuous output. Thus, the inventors have realized that the purification process is delicate and that the essential action to guarantee said requirement and to provide an efficient purification process is to have a moderate pressure level in the condensation chamber, and to have as little or no pressure difference between the condensation chamber and the evaporation chamber.

[0024] According to the invention, the gap membrane distillation comprises a cooling chamber located adjacent to the condensation chamber, wherein the membrane distillation comprises a membrane / foil separating the cooling chamber and the condensation chamber from each other. Due to the adjacent location of the cooling chamber, a suitable and efficient cooling of the condensation chamber is achieved, and due to the separating membrane / foil, the pressure in the cooling chamber and the condensation chamber is the same.

[0025] According to various embodiments of the present application, the pressure control device of the air gap membrane distillation assembly comprises a pressure regulating device configured to control the water pressure at the inlet of the condensation chamber and at the inlet of the cooling chamber. Thus, the pressure limitation of the present application is efficiently achieved.

[0026] According to various embodiments of the present application, the main water supply conduit comprises a first buffer tank and the auxiliary water supply conduit comprises a second buffer tank, wherein the pressure regulating device of the pressure control device is configured to control the water pressure downstream of the first buffer tank and downstream of the second buffer tank in order to control the water pressure at the inlet of the condensation chamber and at the inlet of the cooling chamber. Thus, it is ensured that water is present at the inlet of the condensation chamber and at the inlet of the cooling chamber and the pressure limitation of the present application is efficiently achieved.

[0027] According to various embodiments of the present application, in order to control the water pressure at the inlet of the condensation chamber and at the inlet of the cooling chamber, the pressure regulating device comprises a source of pressurized gas, wherein the source of pressurized gas is connected to the main water supply conduit and to the auxiliary water supply conduit. Thus, the pressure limitation of the present application is efficiently achieved.

[0028] According to various embodiments of the present application, wherein the main water supply conduit comprises a heater. Thus, the water to be treated / purified has a suitable / correct temperature when it reaches the evaporation chamber.

[0029] According to various embodiments of the present application, wherein the auxiliary water supply conduit comprises a cooler. Thus, the water used to cool the condensation chamber has a suitable / correct temperature when it reaches the cooling chamber.

[0030] Further advantages and features of the present application will become clear from the other dependent claims as well as from the detailed description of preferred embodiments given below. BRIEF DESCRIPTION OF DRAWINGS

[0031] The above and other features and advantages of the present application will become more apparent from the following detailed description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0032] Figure 1 is a schematic view of the main components of an air gap membrane distillation assembly,

[0033] Figure 2 is a schematic view of the reservoir of an air gap membrane distillation assembly according to a first embodiment,

[0034] Figure 3 is a schematic view of the reservoir of an air gap membrane distillation assembly according to a first embodiment of the alternative, Figure 2

[0035] Figure 4 is a schematic view of the reservoir of an air gap membrane distillation assembly according to a second embodiment, ​

[0036] Figure 5 is a schematic view of a water supply unit of a gas gap membrane distillation assembly according to a first embodiment,

[0037] Figure 6 is a schematic view of a water supply unit of a gas gap membrane distillation assembly according to a first embodiment, Figure 5 is a schematic view of a water supply unit of a gas gap membrane distillation assembly according to a first embodiment,

[0038] Figure 7 is a schematic view of a water supply unit of a gas gap membrane distillation assembly according to a second embodiment,

[0039] Figure 8 is a schematic view of a water supply unit of a gas gap membrane distillation assembly according to a second embodiment, Figure 7 is a schematic view of a water supply unit of a gas gap membrane distillation assembly according to a second embodiment,

[0040] Figure 9 is a schematic exploded side view of a gas gap membrane distiller according to a schematic embodiment,

[0041] Figure 10 is a schematic side view of a gas gap membrane distiller according to a schematic embodiment, and Figure 9

[0042] Figure 11 is a schematic side view of another schematic embodiment of a gas gap membrane distiller. DETAILED DESCRIPTION

[0043] Reference is first made to Figure 1 , Figure 1 A schematic view of the main components of a gas gap membrane distillation assembly (generally designated 1) is disclosed.

[0044] The gas gap membrane distillation assembly 1 comprises a gas gap membrane distiller 2 configured for producing purified water, i.e. ultra-clean water, a water supply unit 3 connected with the gas gap membrane distiller 2 and configured for supplying water to be treated to the gas gap membrane distiller 2, a reservoir 4 connected with the gas gap membrane distiller 2 and configured for receiving purified water from the gas gap membrane distiller 2, and a purified water dispenser means 5 connected with the reservoir 4. The reservoir 4 is configured for intermediate / interim storage of purified water.

[0045] The water supply unit 3 is connected with at least one source of raw water 6, e.g. a water supply main, i.e. tap water. The purified water dispenser means 5 can be a manually operated nozzle / handle or an automatically controlled nozzle.

[0046] ​The air gap membrane distiller 2 comprises a sealed evaporation chamber 7 and a sealed condensation chamber 8, wherein the evaporation chamber 7 and the condensation chamber 8 are separated from each other by a membrane 9. The condensation chamber 8 is also referred to as gas chamber. According to various embodiments, the air gap membrane distiller 2 comprises a plurality of sets of evaporation chamber 7 and condensation chamber 8, wherein the sets are arranged in parallel to each other. Preferably, each evaporation chamber 7 is connected with two condensation chambers 8, wherein the condensation chambers 8 are arranged opposite to each other with respect to the evaporation chamber 7, i.e. one condensation chamber 8 is arranged on each side of the evaporation chamber 7. The membrane 9 has a pore size equal to or smaller than 1000 nanometer, preferably equal to or smaller than 750 nanometer, most preferably equal to or smaller than 500 nanometer. The membrane 9 has a pore size equal to or larger than 100 nanometer. Smaller pore sizes usually provide cleaner water, but at the same time the production of purified water becomes slower. The pores must be small enough in order to prevent liquid penetration.

[0047] The water supply unit 3 supplies raw water to the evaporation chamber 7, i.e. the evaporation chamber 7 is filled with warm water, e.g. equal to or larger than 80 degrees Celsius and equal to or smaller than 90 degrees Celsius. The water cannot therefore penetrate the membrane 9, but the steam at the interface between the water and the membrane 9 will penetrate the membrane 9 into the condensation chamber 8 and leave the contaminants / particles in the evaporation chamber 7. The temperature in the condensation chamber 8 is lower than in the evaporation chamber 7, i.e. the evaporation chamber 8 is cooled, and the steam that has been drawn through the membrane 9 will accumulate / condense into droplets in the condensation chamber 8. The condensation chamber 8 comprises a cold surface 10 against which a more efficient condensation of the steam will take place. The droplets will accumulate and eventually flow to the bottom of the condensation chamber 8, and the purified water will exit the air gap membrane distiller 2 from the bottom and into the reservoir 4.

[0048] The membrane 9 should be manufactured from a thermally and chemically stable material, preferably from a hydrophobic material, e.g. polytetrafluoroethylene (PTFE), polypropylene (PP), polyvinylidene fluoride (PVDF), etc.

[0049] The reservoir 4 comprises at least one tank 11a for intermediate / interim storage of purified water. Purified water that has been used, e.g. during the washing of a wafer, can be collected in a tank / drain 12 and then recycled back to the water source 6. The tank / drain 12 can comprise a suitable filter in order to prevent contaminants / substances added to the water during the washing step from reaching the water source 6. The air gap membrane distillation assembly 1 can also comprise a pre-filter between the water source 6 and the water supply unit 3.

[0050] Reference is also made below to Figures 2-4 , Figures 2-4 Different schematic embodiments and variations of the reservoir 4 of the air gap membrane distillation assembly 1 are disclosed.

[0051] Reference is first made to Figure 2 , Figure 2A schematic diagram of a reservoir 4 of an air gap membrane distillation assembly 1 according to a first schematic embodiment is disclosed, the reservoir 4 including a tank 11a for intermediate / temporary storage of purified water.

[0052] According to various embodiments, the first storage tank 11a includes: an intermediate conduit 13 connected to the air gap membrane distiller 2, and preferably having a controllable intermediate valve 14; and an outlet conduit 15 connected to the purified water distributor 5, and preferably having a controllable outlet valve 16. The first storage tank 11a is oriented such that purified water will automatically flow to the outlet conduit 15, which is connected to the storage tank at its lowest point.

[0053] If the purified water in the first storage tank 11a is not fully utilized in a timely manner, i.e., before the end of the service life of the purified water in the first storage tank 11a, the remaining contents of the first storage tank 11a shall be discharged / discarded before the first storage tank 11a is refilled. The discharge / discarding may be a manual operation that guides the dispenser tool 5 directly into the tank / drain pipe 12. It should be noted that the first storage tank 11a does not need to be completely filled before utilizing the purified water from it. Preferably, the first storage tank 11a is filled to a level equal to the demand for purified water at the dispenser tool 5 during the period when the purified water is considered clean / usable.

[0054] The following also refers to Figure 3 , Figure 3 According to Figure 2 A schematic diagram of the reservoir 4 of a variation of the first illustrative embodiment of the air gap membrane distillation assembly 1.

[0055] According to various embodiments, the first storage tank 11a includes a discharge / waste conduit 17 with a controllable discharge valve 18, wherein the discharge conduit 17 bypasses the distributor tool 5. Using this solution, the discharge / waste of the remaining contents of the first storage tank 11a can be performed automatically without the risk of contaminating the distributor tool 5 with old / unsuitable water. The discharge conduit 17 is preferably connected to the water source 6 directly or indirectly via a tank / drain pipe 12.

[0056] When the first storage tank 11a is emptied, it is important that no residue remains in the tank, as such residue could contaminate the next batch of purified water. According to various embodiments, the membrane distillation assembly 1 includes a pressurized gas source 19, preferably comprising nitrogen or a similar gas. The first storage tank 11a includes a gas supply conduit 20 connected to the gas source 19 and has a controllable gas valve 21. Pressurized gas from the gas source 19 is used to empty the first storage tank 11a through an outlet valve 16 and / or a discharge valve 18. The gas supply conduit 20 is preferably connected to the first storage tank 11a near an intermediate conduit 13 or downstream of an intermediate valve 14 via the intermediate conduit 13.

[0057] Reference is made below to Figure 4 , Figure 4 A second schematic embodiment of the reservoir 4 of the air gap membrane distillation assembly 1 is disclosed.

[0058] The reservoir 4 comprises at least two tanks 11a, 11b for intermediate / temporary storage of purified water. The tanks 11a, 11b are connected in parallel to each other between the air gap membrane distiller 2 and the purified water dispenser means 5. During operation of the air gap membrane distillation assembly 1, the first tank 11a is filled with purified water from the membrane distiller 2, and the second tank 11b supplies purified water to the dispenser means 5, and vice versa. Thus, production and utilization of purified water can be performed simultaneously and continuously. Preferably, the first tank 11a is filled to such an extent that it equals the demand for purified water at the dispenser means 5 in the time spent for filling the second tank 11b, etc.

[0059] According to various embodiments, each tank 11a, 11b comprises an intermediate conduit 13 connected with the air gap membrane distiller 2 and having a controllable intermediate valve 14, and an outlet conduit 15 connected with the purified water dispenser means 5 and having a controllable outlet valve 16. Thus, the individual tanks of the reservoir 4 can be filled and emptied individually. The tanks 11a, 11b are oriented such that purified water will automatically flow towards the outlet conduit 15, which is connected with the tank at its lowest point.

[0060] In case the purified water in the first tank 11a is not fully utilized in time, i.e. before the end of the useful life of the purified water in the first tank 11a and / or when the second tank 11b is full, the remaining content of the first tank 11a is drained / wasted before the purified water of the second tank 11b is utilized. Said draining / wasting can be a manual operation directing the dispenser means 5 directly into the sink / drain 12.

[0061] According to various embodiments, each tank 11a, 11b comprises a draining / wasting conduit 17 having a controllable draining valve 18, wherein the draining conduit 17 bypasses the dispenser means 5. With this solution, draining / wasting of the remaining content of one tank 11a, 11b can be performed automatically, and / or simultaneously with utilizing the purified water of the other tank 11a, 11b at the dispenser means 5. The draining conduit 17 is preferably connected with the water source 6, either directly or indirectly through the sink / drain 12.

[0062] According to the present application, the air gap membrane distillation assembly 1 comprises a pressure control device configured to maintain the pressure in the evaporation chamber 7 equal to or greater than 0.1 bar (e) and equal to or less than 1 bar (e), and configured to control the pressure difference between the evaporation chamber 7 and the condensation chamber 8 equal to or less than 1 bar. Thus, water does not have to be forced through the membrane 9, but will be sucked / pulled through the membrane due to the vapour pressure gradient from the temperature difference between the evaporation chamber 7 and the condensation chamber 8. It should be noted that 1 bar (e) means 1 bar overpressure.

[0063] According to various embodiments of the present application, the pressure control device is configured to maintain the pressure in the evaporation chamber 7 equal to or less than 0.6 bar (e), and / or the pressure control device is configured to control the pressure difference between the evaporation chamber 7 and the condensation chamber 8 equal to or less than 0.6 bar, preferably equal to or less than 0.3 bar. It is desirable that the control target of the process is to have no pressure difference between the evaporation chamber 7 and the condensation chamber 8.

[0064] According to various embodiments, the pressure control device comprises a sub-device configured for monitoring / controlling the pressure of the raw water loaded / directed from the water supply unit 3 to the evaporation chamber 7, and a sub-device for monitoring / controlling the gas pressure in the condensation / gas chamber 8. The condensation / gas chamber is preferably comprising nitrogen or similar gas. The gas pressure in the condensation / gas chamber 8 can be monitored / controlled directly or indirectly, as will be described below. The control unit can be in operative connection with said devices for monitoring and control, so that the control unit is configured to maintain the above-mentioned pressure limits, or the system is self-regulating.

[0065] Thus, according to the method of the present application, the method comprises the steps of providing a pressure in the evaporation chamber 7 equal to or greater than 0.1 bar (e) and equal to or less than 1 bar (e), and controlling the pressure difference between the evaporation chamber 7 and the condensation chamber 8 equal to or less than 1 bar. Preferably, the pressure in the evaporation chamber 7 is decisive, and the pressure in the condensation chamber 8 is changed / regulated.

[0066] Reference is made below to Figures 5-8 , Figures 5-8 Different schematic views of the water supply unit 3 of the air gap membrane distillation assembly 1 are disclosed, and different implementations of the pressure control device are comprised. These variants and embodiments have certain basic features in common with each other, which will be described in connection with Figure 5 the description below.

[0067] According to various embodiments, the water supply unit 3 comprises a main water supply conduit (generally indicated as 22) connected with the evaporation chamber 7 of the air gap membrane distiller 2, wherein the main water supply conduit 22 comprises a heater 23 configured to increase the temperature of the water in the main water supply conduit 22. Thus, the water supplied to the evaporation chamber 7 is pre-heated to a suitable temperature before entering the evaporation chamber 7. The temperature variation in the evaporation chamber 7 will thus be minimized / eliminated.

[0068] At the outlet (lower end) of the main water supply conduit 22, the main water supply conduit 22 preferably comprises suitable sensors, e.g. temperature, pressure, flow, etc., in order to monitor the characteristics / properties of the water flow directed to the evaporation chamber 7, i.e. downstream of the heater 23.

[0069] According to various embodiments of the water supply unit 3, the main water supply conduit 22 comprises a feed water conduit 26 connected with the heater 23 and configured to be connected with the water source 6, wherein the feed water conduit 26 comprises a controllable fill valve 27 in order to fill the main water supply conduit 22. According to various embodiments, the water supply unit 3 comprises a main water return conduit 28 extending from the evaporation chamber 7 to the heater 23, wherein the water not purified in the air gap membrane distiller 2, i.e. not passing through the membrane 9, is returned / recirculated, which is beneficial since it already has an elevated temperature. It should be noted that although the returned / recirculated non-treated water is from time to time diluted by adding new raw water via the fill valve 27, the returned / recirculated non-treated water has an increasing degree of contamination for each cycle. Thus, the main water supply conduit 22 can comprise a dump / bleed valve in order to remove the non-treated water having an elevated degree of contamination.

[0070] Preferably, the sensors located at the downstream end of the main water supply conduit 22 are also used to control the fill valve 27 and / or the heater 23. The main water supply conduit 22 preferably comprises a vent adjacent to the heater 23 in order to remove unwanted air evaporated by the water when heated in the heater 23.

[0071] The water supply unit 3 comprises a pressure regulator / pressure reducing valve 29 in order not to obtain too high pressure in the main water supply conduit 22. The pressure regulating valve 29 can be located between the water source 6 and the water supply unit 3, or in the water supply unit 3, as shown in the attached drawings.

[0072] The flow generated in the main water supply conduit 22 is in the range of 1-5 liters / minute, and the yield of purified water to the reservoir 4 is in the range of 1-4 liters / minute.

[0073] According to the present invention, see Figure 1The air gap membrane distiller 2 comprises a sealed cooling chamber 30 located in the vicinity of the condensation chamber 8. The cooling chamber 30 is thus configured to provide the cold surface 10. The air gap membrane distiller 2 comprises a membrane / separator / foil 31 separating the cooling chamber 30 and the condensation chamber 8 from each other, i.e. the cold surface 10 is part of the membrane / separator 31. The cooling chamber 30 comprises a liquid / water or a gas.

[0074] According to various embodiments, the membrane 31 has a thickness equal to or greater than 0.08 mm and equal to or less than 0.25 mm, preferably equal to or greater than 0.1 mm and equal to or less than 0.2 mm. The membrane 31 is thus able to withstand deformations and is easy to install and still has a low thermal insulation effect. The cold surface 10 should be as smooth as possible to facilitate the downward flow of purified water. Preferably, the membrane 31 is hydrophobic to facilitate the downward flow of purified water. The membrane 31 is preferably a hydrophobic material, such as polyvinylidene fluoride (PVDF).

[0075] According to various embodiments, the water supply unit 3 comprises an auxiliary water supply conduit (generally designated 32) connected to the cooling chamber 30 of the air gap membrane distiller 2, wherein the auxiliary water supply conduit 32 comprises a cooler 33 configured to lower the temperature of the water in the auxiliary water supply conduit 32. The water in the cooling chamber 30 thus has a suitable temperature to efficiently condense the steam in the condensation chamber 8 into purified water.

[0076] The cooler 33 is preferably a thermoelectric heat pump, such as a Peltier device, which uses electrical energy to transfer heat from one side of the device to the other. The heat is transferred from the liquid / water in the auxiliary water supply conduit 32 to the surrounding air. According to alternative embodiments, such a thermoelectric heat pump can be connected directly to the cooling chamber 30.

[0077] At the outlet (lower end) of the auxiliary water supply conduit 32, the auxiliary water supply conduit 32 preferably comprises suitable sensors, such as temperature, pressure, flow, etc., to monitor the characteristics / properties of the water flow directed to the cooling chamber 30, i.e. downstream of the cooler 33.

[0078] According to various embodiments of the water supply unit 3, the auxiliary water supply conduit 32 comprises a feed water conduit 36 connected to the cooler 33 and configured to be connected to the water source 6, wherein the feed water conduit 36 comprises a controllable fill valve 37 to fill the auxiliary water supply conduit 32. According to various embodiments, the water supply unit 3 comprises an auxiliary water return conduit 38 extending from the cooling chamber 30 to the auxiliary water supply conduit 32, wherein the cooling water is returned / recirculated, which is beneficial as it already has a reduced temperature and it will reduce the water consumption. Preferably, the sensors located at the downstream end of the auxiliary water supply conduit 32 are also used to control the fill valve 37 and / or the cooler 33. The auxiliary water supply conduit 32 preferably comprises a vent.

[0079] The main water supply conduit 22 and the auxiliary water supply conduit 32 can be connected to the water source 6 in parallel to each other through separate pressure reducers / regulating valves or through the same pressure reducer / regulating valve 29.

[0080] According to various embodiments, the pressure control means of the gas gap membrane distillation assembly 1 comprises pressure regulating means configured to control the water pressure at the inlet of the condensation chamber 7 and at the inlet of the cooling chamber 30. The membrane 31 between the cooling chamber 30 and the condensation chamber 8 is slightly flexible and transmits the pressure conditions in the cooling chamber 30 to the condensation chamber 8.

[0081] Figure 5 A first variant of the first embodiment of the water supply unit 3 is disclosed. The pressure regulating means comprises a source of pressurized gas 19, wherein said source of pressurized gas is preferably the same as the source of pressurized gas 19 introduced above in connection with the emptying of the reservoirs 11a, 11b of the tank 4. According to various embodiments, the pressure level of the gas provided from the source of pressurized gas 19 is preferably monitored and controlled using the control unit 77 to be more or less constant over time. The source of pressurized gas 19 is connected to the main water supply conduit 22 and to the auxiliary water supply conduit 32 in order to have substantially the same pressure level conditions in both water supply conduits and thus in the evaporation chamber 7 and the cooling chamber 30 / condensation chamber 8. Separate pressure reservoirs can be located between the source of pressurized gas 19 and the main water supply conduit 22 and between the source of pressurized gas and the auxiliary water supply conduit 32, respectively.

[0082] The main water supply conduit 22 and the auxiliary water supply conduit 32 should be arranged so that the pressurized gas does not enter the evaporation chamber 7 and / or the cooling chamber 30. By monitoring and controlling the pressure level of the gas provided by the source of pressurized gas 19, the pressure limits of the present invention described above are guaranteed / maintained.

[0083] The pressure limits of the present invention also guarantee that the pressurized gas does not dissolve in the water. When the pressure in the evaporation chamber 7 is higher than the pressure limits of the present invention, there is a substantial and imminent risk that air bubbles will be generated / occur at or in the membrane 9, resulting in inefficient or blocked treatment / purification.

[0084] The source of pressurized gas 19 is preferably connected to the main water supply conduit 22 downstream of the heater 23 and preferably connected to the auxiliary water supply conduit 32 downstream of the cooler 33.

[0085] Reference is made below to Figure 6 , Figure 6 A second variant of the first embodiment of the water supply unit 3 is disclosed. Only features and circumstances deviating from the embodiment according to Figure 5 are introduced, the remaining features being similar.

[0086] According to various embodiments, the main water supply conduit 22 comprises a first buffer tank 25. Preferably, the first buffer tank 25 is associated with the heater 23, or they can be positioned in series with each other as separate components along the main water supply conduit 22. In the example embodiment disclosed, the feed water conduit 26 is connected to the heater 23 by connection with the first buffer tank 25 comprising the heater 23, and a controllable charging valve 27 is configured to charge the first buffer tank 25, the main water return conduit 28 extending from the evaporation chamber 7 to the first buffer tank 25. Alternatively, in the example embodiment in which the heater 23 is located upstream of the first buffer tank 25 along the main water supply conduit 22, the main water return conduit 28 is connected to the heater 23.

[0087] According to various embodiments, the auxiliary water supply conduit 32 comprises a second buffer tank 35. Preferably, the second buffer tank 35 is associated with the cooler 33, or they can be positioned in series with each other as separate components along the auxiliary water supply conduit 32. In the example embodiment disclosed, the feed water conduit 26 is connected to the cooler 33 by connection with the second buffer tank 35 comprising the cooler 33, and a controllable charging valve 37 is configured to charge the second buffer tank 35, the auxiliary water return conduit 38 extending from the cooling chamber 30 to the second buffer tank 35. Alternatively, in the example embodiment in which the cooler 33 is located upstream of the second buffer tank 35 along the auxiliary water supply conduit 32, the auxiliary water return conduit 38 is connected to the cooler 33.

[0088] According to various embodiments, the pressurized gas source 19 is connected to the main water supply conduit 22 and to the auxiliary water supply conduit 32 by connection with the first buffer tank 25 and the second buffer tank 35, respectively, in order to control the water pressure downstream of the first buffer tank 25 and downstream of the second buffer tank 35.

[0089] According to various embodiments, the first buffer tank 25 and the second buffer tank 35 each comprise a water chamber 78, a gas chamber 79, and a flexible partition 80 separating the water chamber 78 and the gas chamber 79 from each other, wherein the pressurized gas source 19 is connected to said gas chamber 79. Thus, the pressurized gas cannot mix with the water in the respective tank and cannot reach the evaporation chamber 7 or the cooling chamber 30, i.e. cannot interfere with the treatment / purification.

[0090] Reference is made below to Figure 7 , Figure 7 A first variant of the second embodiment of the water supply unit 3 is disclosed. Only the features and aspects that deviate from the embodiment according to Figure 5 and 6 are described, the remaining features being similar.

[0091] According to various embodiments, the pressure regulating arrangement comprises a first water regulator 24 configured for controlling the flow and pressure of water supplied from the main water supply conduit 22 to the evaporation chamber 7, a second water regulator 34 configured for controlling the flow and pressure of water supplied from the auxiliary water supply conduit 32 to the cooling chamber 30, and a control unit 77 in operative connection with the first water regulator 24 and the second water regulator 34. The first water regulator 24 is located downstream of the heater 23 and the second water regulator 34 is located downstream of the cooler 33.

[0092] The first water regulator 24 and the second water regulator 24 are preferably each constituted by a pump. The pumps are preferably automatically primed using gravity in order to prevent excessive pressure in the evaporation chamber 7 and the cooling chamber 30, respectively.

[0093] The control unit 77 is configured to control the first water regulator 24 so that the pressure in the evaporation chamber 7 is within the pressure limits of the present invention, and in addition, the control unit 77 is configured to monitor the pressure in the cooling chamber 30 and control the second water regulator 34 so that the pressure difference is within the pressure limits of the present invention, preferably guiding the pressure difference to zero. Controlling the first water regulator 24 and then changing / adjusting the second water regulator 34 when needed is a continuous process. Thus, the first water regulator 24 can be referred to as active and the second water regulator 34 can be referred to as passive.

[0094] Reference is made below to Figure 8 , Figure 8 A second variant of the second embodiment of the water supply unit 3 is disclosed. Only features and circumstances deviating from the embodiment according to Figure 7 are presented, the rest of the features are similar.

[0095] According to various embodiments, the main water supply conduit 22 comprises a first buffer tank 25. Preferably, the first buffer tank 25 is associated with the heater 23 or they can be positioned in series with each other as separate components along the main water supply conduit 22. In the disclosed example embodiment, the feed water conduit 26 is connected to the heater 23 by connection to the first buffer tank 25 comprising the heater 23, and a controllable priming valve 27 is configured to prime the first buffer tank 25, and a main water return conduit 28 extends from the evaporation chamber 7 to the first buffer tank 25. Alternatively, in the illustrated embodiment where the heater 23 is located upstream of the first buffer tank 25 along the main water supply conduit 22, the main water return conduit 28 is connected to the heater 23.

[0096] According to various embodiments, the auxiliary water supply conduit 32 comprises a second buffer reservoir 35. Preferably, the second buffer reservoir 35 is associated with the cooler 33 or they can be positioned as separate components in series with each other along the auxiliary water supply conduit 32. In the disclosed example embodiment, the feed water conduit 26 is connected with the cooler 33 by connection with the second buffer reservoir 35 comprising the cooler 33, and the controllable charging valve 37 is configured to charge the second buffer reservoir 35, the auxiliary water return conduit 38 extending from the cooling chamber 30 to the second buffer reservoir 35. Alternatively, in the illustrated embodiment in which the cooler 33 is located upstream of the second buffer reservoir 35 along the auxiliary water supply conduit 32, the auxiliary water return conduit 38 is connected with the cooler 33.

[0097] According to various embodiments, the first water regulator 24 is located downstream of the heater 23 by being located downstream of the first buffer reservoir 25, and the second water regulator 34 is located downstream of the cooler 33 by being located downstream of the second buffer reservoir 35.

[0098] At least the reservoir 4 and the conduit extending from the condensation chamber 8 to the dispenser means 5 are preferably treated to have a hydrophobic surface facing the purified water to facilitate the flow of purified water.

[0099] Reference is made below to Figures 9-10 , Figures 9-10 A schematic diagram of the illustrated air gap membrane distiller 2 is disclosed. The air gap membrane distiller 2 comprises a stack of different components / elements in order to provide the evaporation chamber 7, the condensation chamber 8 and the cooling chamber 30. However, the stack of the air gap membrane distiller 2 can preferably comprise a plurality of such combinations arranged in parallel with each other. Preferably, the top and bottom of the stack comprise the cooling chamber 30 in order to minimize the heat dissipated to the surrounding environment / clean room.

[0100] The stack of the membrane distiller 2 according to the disclosed illustrated embodiment comprises a first end plate 39, preferably made of metal, a resilient first gasket 40, the membrane 9, a rigid first polymer frame 41, a resilient second gasket 42, a rigid second polymer frame 43, the thin film 31, a resilient third gasket 44 and a second end plate 45, preferably made of metal.

[0101] According to the disclosed embodiment, the first end plate 39 delimits the evaporation chamber 7 and the second end plate 45 delimits the cooling chamber 30, i.e. the end plates delimit the outer / adjacent chambers.

[0102] The membrane 9 is a multilayer polymer membrane comprising a non-woven first layer 46 having a pore size equal to or smaller than 1000 nanometers and a spun-bond second layer 47 laminated to the first layer 46, wherein the second layer 47 faces the condensation chamber 8. Thus, the first layer 46 faces the evaporation chamber 7. According to various embodiments, the thickness of the membrane 9 is equal to or greater than 0.1 millimeter and equal to or smaller than 0.4 millimeter, preferably equal to or greater than 0.2 millimeter and equal to or smaller than 0.3 millimeter. Thus, the first layer 46 of the membrane 9 is a filter layer. The first layer 46 of the membrane 9 preferably comprises a fluoropolymer, such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF), and the second layer 47 of the membrane 9 preferably comprises a thermoplastic polymer, such as polypropylene (PP).

[0103] The rigid polymer frames / carriers 41, 43 preferably comprise a rigid fluoropolymer, such as polyvinylidene fluoride (PVDF), and the elastic washers 40, 42, 44 preferably comprise an elastic fluoropolymer, such as polytetrafluoroethylene (PTFE). The rigid polymer frames 41, 43 will maintain their initial thickness in response to the mounting / compression of the membrane still 2. In response to the mounting / compression of the membrane still 2, the elastic washers 40, 42, 44 will obtain a smaller thickness than their initial / loaded thickness. The elastic washers preferably are compressed equal to or greater than 25% of the initial / unloaded thickness and equal to or smaller than 40% of the initial / unloaded thickness. Too small compression can result in leakage, too much compression will result in a compressed washer losing its sealing / elastic properties and can result in leakage. When the stack of the air gap membrane still 2 is mounted / compressed, the first end plate 39 and the second end plate 45 clamp each other while providing a distance element between the end plates having a suitable length in order to prevent over-clamping. Thus, the suitable length of the distance element is equal to the sum of the final / compressed thickness of the washers and the thickness of the polymer frames.

[0104] The first polymer frame 41 has a first surface 48, a second surface 49 and a central hole 50 extending between the first surface 48 and the second surface 49, and at least a portion of the condensation chamber 8 is constituted by the central hole 50. The membrane 9 is welded on the first surface 48 of the first polymer frame 41, thereby covering the central hole 50, and the second layer 47 of the membrane 9 faces the first surface 48 of the first polymer frame 41. The membrane 9 can be connected to the first polymer frame 41 in other suitable ways, such as by glue, but welding (ultrasonic welding) is preferred. The second layer 47 of the membrane 9 facilitates the connection between the membrane 9 and the first polymer frame 41.

[0105] The second polymer frame 43 has a first surface 51, a second surface 52, and a central aperture 53 extending between the first surface 51 and the second surface 52. The membrane 31 is welded to the first surface 51 of the second polymer frame 43 (thereby covering the central aperture 53) or to the second surface 52 of the second polymer frame 43 (thereby covering the central aperture 53). The membrane 31 can be connected to the second polymer frame 43 in other suitable ways, such as by glue, although welding (ultrasonic welding) is preferred. When the membrane 31 is connected to the second surface 52 of the second polymer frame 43 (see Figure 10 ), the central aperture 53 constitutes at least a portion of the condensation chamber 8. When the membrane 31 is connected to the first surface 51 of the second polymer frame 43, the central aperture 53 constitutes at least a portion of a cooling chamber 30 (not shown in the figures).

[0106] The resilient first grommet 40 has a first surface 54, a second surface 55, and a central aperture 56 extending between the first surface 54 and the second surface 55, at least a portion of the evaporation chamber 7 being constituted by the central aperture 56. An inlet 57, which is part of the main water supply conduit 22, extends into the central aperture 56 at a lower portion of the first grommet 40, and an outlet 58, which is part of the main water return conduit 28, extends from the central aperture 56 at an upper portion of the first grommet 40.

[0107] The resilient second grommet 42 has a first surface 59, a second surface 60, and a central aperture 61 extending between the first surface 59 and the second surface 60, at least a portion of the condensation chamber 8 being constituted by the central aperture 61. An outlet 62, which is part of the intermediate conduit 13, extends from the central aperture 61 at a lower portion of the second grommet 42. The second grommet 42 can also include a vent 63 in order to prevent pressure build-up in the condensation chamber 8.

[0108] The resilient third grommet 44 has a first surface 64, a second surface 65, and a central aperture 66 extending between the first surface 64 and the second surface 65, at least a portion of the cooling chamber 30 being constituted by the central aperture 66. An inlet 67, which is part of the auxiliary water supply conduit 32, extends into the central aperture 66 at an upper portion of the third grommet 44, and an outlet 68, which is part of the auxiliary water return conduit 38, extends from the central aperture 66 at a lower portion of the third grommet 44.

[0109] Reference is also made below to Figure 11 , Figure 11 Another diagrammatic view of the air gap membrane distiller 2 is disclosed. Only additions / differences with respect to the diagrammatic embodiment of Figures 9-10 will be introduced.

[0110] According to various embodiments, the air gap membrane distiller 2 comprises a main water feed manifold 69 extending between the first surface 54 and the second surface 55 of the first gasket 40 at a lower portion of the first gasket 40, wherein the inlet 57 extends from the main water feed manifold 69 to the central hole 56 of the first gasket 40. The main water feed manifold 69 is part of the main water feed conduit 22 and extends from the first gasket 40 to the outside of the air gap membrane distiller 2, for example to the outer surface 70 of the first end plate 39 through any intermediate element. The main water feed manifold 69 can extend through the whole air gap membrane distiller 2, i.e. from the outer surface 70 of the first end plate 39 to the outer surface 71 of the second end plate 45. All evaporation chambers 7 are preferably connected to the same main water feed manifold 69.

[0111] According to various embodiments, the air gap membrane distiller 2 comprises a main water return manifold 72 extending between the first surface 54 and the second surface 55 of the first gasket 40 at an upper portion of the first gasket 40, wherein the outlet 58 extends from the central hole 56 of the first gasket 40 to the main water return manifold 72. The main water return manifold 72 is part of the main water return conduit 28 and extends from the first gasket 40 to the outside of the air gap membrane distiller 2, for example to the outer surface 70 of the first end plate 39 through any intermediate element. The main water return manifold 72 can extend through the whole air gap membrane distiller 2, i.e. from the outer surface 70 of the first end plate 39 to the outer surface 71 of the second end plate 45. All evaporation chambers 7 are preferably connected to the same main water return manifold 72.

[0112] According to various embodiments, the air gap membrane distiller 2 comprises a purified water manifold 73 extending between the first surface 59 and the second surface 60 of the second gasket 42 at a lower portion of the second gasket 42, wherein the outlet 62 extends from the central hole 61 of the second gasket 42 to the purified water manifold 73. The purified water manifold 73 is part of the intermediate conduit 13 and extends from the second gasket 42 to the outside of the air gap membrane distiller 2, for example to the outer surface 70 of the first end plate 39 through any intermediate element. The purified water manifold 73 can extend through the whole membrane distiller 2, i.e. from the outer surface 70 of the first end plate 39 to the outer surface 71 of the second end plate 45. All condensation chambers 8 are preferably connected to the same purified water manifold 73.

[0113] According to various embodiments, the air gap membrane distiller 2 comprises a vent manifold 74 extending between the first surface 59 and the second surface 60 of the second gasket 42 at an upper portion of the second gasket 42, wherein the vent port 63 extends from the central hole 61 of the second gasket 42 to the vent manifold 74. The vent manifold 74 extends from the second gasket 42 to the outside of the air gap membrane distiller 2, for example to the outer surface 70 of the first end plate 39 through any intermediate element. The vent manifold 74 can extend through the whole air gap membrane distiller 2, i.e. from the outer surface 70 of the first end plate 39 to the outer surface 71 of the second end plate 45. All condensation chambers 8 are preferably connected with the same vent manifold 74. The vent manifold 74 can be used to regulate the pressure level in the condensation chambers 8.

[0114] According to various embodiments, the air gap membrane distiller 2 comprises an auxiliary water feed manifold 75 extending between the first surface 64 and the second surface 65 of the third gasket 44 at an upper portion of the third gasket 44, wherein the inlet port 67 extends from the central hole 66 of the third gasket 44 to the auxiliary water feed manifold 75. The auxiliary water feed manifold 75 is part of the auxiliary water feed conduit 32 and extends from the third gasket 44 to the outside of the membrane distiller 2, for example to the outer surface 71 of the second end plate 45 through any intermediate element. The auxiliary water feed manifold 75 can extend through the whole air gap membrane distiller 2, i.e. from the outer surface 70 of the first end plate 39 to the outer surface 71 of the second end plate 45. All cooling chambers 30 are preferably connected with the same auxiliary water feed manifold 75.

[0115] According to various embodiments, the air gap membrane distiller 2 comprises an auxiliary water return manifold 76 extending between the first surface 64 and the second surface 65 of the third gasket 44 at a lower portion of the third gasket 44, wherein the outlet port 68 extends from the central hole 66 of the third gasket 44 to the auxiliary water return manifold 76. The auxiliary water return manifold 76 is part of the auxiliary water return conduit 38 and extends from the third gasket 44 to the outside of the air gap membrane distiller 2, for example to the outer surface 71 of the second end plate 45 through any intermediate element. The auxiliary water return manifold 76 can extend through the whole air gap membrane distiller 2, i.e. from the outer surface 70 of the first end plate 39 to the outer surface 71 of the second end plate 45. All cooling chambers 30 are preferably connected with the auxiliary water return manifold 76.

[0116] Possible variants of the invention

[0117] The present invention is not limited merely to the embodiments described above and shown in the drawings, which are merely intended to be illustrative and exemplary. This patent application is intended to cover all possible variants and modifications of the preferred embodiments described herein, so the invention is determined by the wording of the appended claims, so the device can be varied in all conceivable ways within the framework of the appended claims.

[0118] It should also be noted that all information regarding terms such as above, below, upper, lower, etc. should be interpreted / read with the device oriented according to the drawings, wherein the drawings are oriented such that the reference numerals can be read in a correct manner. Thus, these terms only indicate a relative relationship in the illustrated embodiments, which relationship can change when the device according to the application is provided with another construction / design.

[0119] It should also be noted that even if it is not explicitly stated that a feature from a particular embodiment can be combined with a feature from another embodiment, such a combination should be considered obvious when the combination is feasible.

Claims

1. Air gap membrane distillation assembly (1) for providing purified water, said air gap membrane distillation assembly (1) comprising: - an air gap membrane distiller (2) configured for producing purified water; - a water supply unit (3) connected to the air gap membrane distiller (2) and configured for supplying water to the air gap membrane distiller (2); and - a reservoir (4) connected to the air gap membrane distiller (2), the reservoir (4) being configured for intermediate storage of purified water, wherein the air gap membrane distiller (2) comprises: - an evaporation chamber (7), - a condensation chamber (8), - a membrane (9) separating the evaporation chamber (7) and the condensation chamber (8) from each other, wherein the membrane (9) has a pore size of less than or equal to 1000 nanometers; - a cooling chamber (30) located in the vicinity of the condensation chamber (8); and - a thin film (31) separating the cooling chamber (30) and the condensation chamber (8) from each other, characterized in that the air gap membrane distillation assembly (1) comprises a pressure control device configured for maintaining a pressure in the evaporation chamber (7) of greater than or equal to 0.1 bar (e) and less than or equal to 1 bar (e) and for controlling a pressure difference between the evaporation chamber (7) and the condensation chamber (8) of less than or equal to 1 bar. The pressure control device is configured for maintaining a pressure in the evaporation chamber (7) of equal to or less than 0.6 bar (e).

2. The gas gap membrane distillation assembly (1) according to claim 1, wherein: The pressure control device is configured for controlling a pressure difference between the evaporation chamber (7) and the condensation chamber (8) of less than or equal to 0.6 bar, preferably less than or equal to 0.3 bar.

3. The air gap membrane distillation assembly (1) according to claim 1 or 2, wherein: The water supply unit (3) comprises a water inlet configured for being connected to a water source (6), the water supply unit (3) comprising:

4. The gas gap membrane distillation assembly (1) according to any one of the preceding claims, wherein: - a main water supply conduit (22) extending between the water inlet and the evaporation chamber (7); and - an auxiliary water supply conduit (32) extending between the water inlet and the cooling chamber (30). The pressure control device of the air gap membrane distillation assembly (1) comprises a pressure regulating device configured for controlling a water pressure at an inlet of the condensation chamber (7) and a water pressure at an inlet of the cooling chamber (30).

5. The gas-gap membrane distillation assembly (1) according to any one of the preceding claims, wherein: The main water supply conduit (22) comprises a first buffer tank (25) and the auxiliary water supply conduit (32) comprises a second buffer tank (35), the pressure regulating device of the pressure control device being configured for controlling a water pressure downstream of the first buffer tank (25) and a water pressure downstream of the second buffer tank (35).

6. The gas gap membrane distillation assembly (1) according to claim 5, wherein: The pressure regulating device comprises a source of pressurized gas (19) connected to the main water supply conduit (22) and to the auxiliary water supply conduit (32).

7. The air gap membrane distillation assembly (1) according to claim 5 or 6, wherein: The source of pressurized gas (19) of the pressure regulating device is connected to the first buffer tank (25) of the main water supply conduit (22) and to the second buffer tank (35) of the auxiliary water supply conduit (32).

8. The gas gap membrane distillation assembly (1) according to claim 7, wherein: The first buffer tank (25) and the second buffer tank (35) each comprise:

9. The gas gap membrane distillation assembly (1) according to claim 8, wherein: - a water chamber (78); - a gas chamber (79); and - a flexible partition (80) separating the water chamber (78) and the gas chamber (79) from each other, ​ The pressurized gas source (19) is connected to the gas chamber (79).

10. The gas gap membrane distillation assembly (1) according to claim 5, wherein: The pressure regulating device comprises: - a first water regulator (24) configured for controlling the flow rate and pressure of water supplied from a main water supply conduit (22) to the evaporation chamber (7); - a second water regulator (34) configured for controlling the flow rate and pressure of water supplied from an auxiliary water supply conduit (32) to the cooling chamber (30); and - a control unit (77) in operative connection with the first water regulator (24) and the second water regulator (34).

11. The air gap membrane distillation assembly (1) according to any one of claims 4-10, wherein: The main water supply conduit (22) comprises a heater (23).

12. The gas gap membrane distillation assembly (1) according to claim 6, wherein: The water supply unit (3) comprises: - a main water return conduit (28) extending from the evaporation chamber (7) to a buffer tank (25).

13. The gas-gap membrane distillation assembly (1) according to any one of claims 4-12, wherein: The auxiliary water supply conduit (32) comprises a cooler (33).

14. The gas gap membrane distillation assembly (1) according to claim 6, wherein: The water supply unit (3) comprises: - an auxiliary water return conduit (38) extending from the cooling chamber (30) to a buffer tank (35).

15. The gas-gap membrane distillation assembly (1) according to any one of the preceding claims, wherein: The air gap membrane distillation assembly (1) comprises a purified water distributor means (5) connected to the reservoir (4).

16. Method for controlling an air gap membrane distillation assembly (1) configured for providing purified water, the air gap membrane distillation assembly (1) comprising: - an air gap membrane distiller (2) configured for producing purified water; - a water supply unit (3) connected to the air gap membrane distiller (2) and configured for supplying water to the air gap membrane distiller (2); and - a reservoir (4) connected to the air gap membrane distiller (2), the reservoir (4) being configured for intermediate storage of purified water; wherein the air gap membrane distiller (2) comprises: - an evaporation chamber (7); - a condensation chamber (8); - a membrane (9) separating the evaporation chamber (7) and the condensation chamber (8) from each other, wherein the membrane (9) has a pore size of less than or equal to 1000 nanometers; - a cooling chamber (30) located in the vicinity of the condensation chamber (8); and - a membrane (31) separating the cooling chamber (30) and the condensation chamber (8) from each other, the method being characterized by the following steps: - providing a pressure in the evaporation chamber (7) of greater than or equal to 0.1 bar (e) and less than or equal to 1 bar (e), and - controlling the pressure difference between the evaporation chamber (7) and the condensation chamber (8) to be less than or equal to 1 bar. ​

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