Membrane distillation apparatus and membrane exchange unit thereof

Abstract

The application discloses a membrane distillation device and a membrane exchange unit thereof, the membrane exchange unit is used for being placed in a shell of the membrane distillation device, water vapor is introduced into the shell, and the membrane exchange unit comprises a mounting frame and two hydrophobic membranes. The two hydrophobic membranes are arranged on the two sides of the mounting frame respectively, the two hydrophobic membranes and the mounting frame form an exchange cavity, a cold end inlet and a cold end outlet which are communicated with the exchange cavity are arranged on the mounting frame, and the cold end inlet and the cold end outlet are respectively located at the two ends of the mounting frame and are located at the top of the exchange cavity. In this way, when the cold end inlet is introduced into cold air, the characteristics of the cold air and the water vapor can be fully utilized, that is, the density of the cold air is large, and the density of the water vapor is small, so that the cold air entering the exchange cavity has a movement trend of sinking first and floating later, the flow path of the cold air is prolonged, the water vapor has sufficient exchange time, and therefore the membrane flux and the purification efficiency of waste liquid can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of membrane distillation technology, and in particular to a membrane distillation apparatus and its membrane exchange unit. Background Technology

[0002] Membrane distillation is a membrane separation process that uses a hydrophobic microporous membrane and relies on the pressure difference across the membrane as the driving force for mass transfer. Because membrane distillation operates under mild conditions, can utilize low-grade heat sources, and has high purification efficiency, it is widely used in fields such as urban wastewater treatment and chemical wastewater treatment.

[0003] To avoid direct contact between high-temperature waste liquid and the hydrophobic microporous membrane inside the membrane module, which could lead to fouling and clogging and thus affect its lifespan, membrane distillation technology currently converts the high-temperature waste liquid into wet hot water vapor before introducing it into the membrane module. However, while this method reduces membrane fouling and extends membrane lifespan, it results in a lower flux of the hydrophobic microporous membrane, limiting the purification efficiency of membrane distillation technology. Summary of the Invention

[0004] Therefore, it is necessary to provide a membrane distillation device and its membrane exchange unit to address the above problems. The membrane exchange unit has a high membrane flux, which is beneficial to improving the purification efficiency of the membrane distillation device.

[0005] A membrane exchange unit is provided, which is placed inside the housing of a membrane distillation apparatus, and water vapor is introduced into the housing. The membrane exchange unit includes a mounting frame and two hydrophobic membranes. The two hydrophobic membranes are respectively disposed on both sides of the mounting frame, and the two hydrophobic membranes and the mounting frame enclose an exchange cavity. The mounting frame is provided with a cold end inlet and a cold end outlet that are both connected to the exchange cavity. The cold end inlet and the cold end outlet are respectively located at both ends of the mounting frame and at the top of the exchange cavity. The cold end inlet is used to introduce cold air into the exchange cavity, and the cold end outlet is used to discharge the water vapor that has entered the exchange cavity from the exchange cavity.

[0006] In the aforementioned membrane exchange unit, the mounting frame is equipped with a cold-end inlet and a cold-end outlet connected to the exchange chamber. Cold air can be introduced into the exchange chamber through the cold-end inlet. When the membrane exchange unit is placed inside the membrane distillation apparatus, a temperature difference is formed on both sides of each hydrophobic membrane. Under the action of this pressure difference, water vapor passes through the micropores on the hydrophobic membrane and enters the exchange chamber, ultimately exiting from the cold-end outlet to purify the waste liquid. Furthermore, since the cold-end inlet and outlet are located at opposite ends of the mounting frame and both at the top of the exchange chamber, when the membrane exchange unit is placed inside the membrane distillation apparatus and cold air is introduced through the cold-end inlet, the characteristics of cold air and water vapor—namely, the high density of cold air and the low density of water vapor—can be fully utilized. This causes the cold air entering the exchange chamber to first sink and then rise, extending the airflow path and allowing sufficient exchange time for the water vapor, thereby effectively improving membrane flux and waste liquid purification efficiency.

[0007] The technical solution will be further explained below:

[0008] In one embodiment, the mounting frame includes a first crossbeam, a first column, a second crossbeam, and a second column, which are sequentially connected to form a ring frame structure. The first column has an air intake channel communicating with the exchange chamber, and the top of the first column has a cold end inlet communicating with the air intake channel. The second column has an exhaust channel communicating with the exchange chamber, and the top of the second column has a cold end outlet communicating with the exhaust channel.

[0009] In one embodiment, the side wall of the first column is provided with a first perforation group, and the air intake channel is connected to the exchange chamber through the first perforation group; the side wall of the second column is provided with a second perforation group, and the exhaust channel is connected to the exchange chamber through the second perforation group.

[0010] In one embodiment, the orifice area of ​​the first perforated group is smaller than the area of ​​the cold end inlet, and the orifice area of ​​the second perforated group is greater than or equal to the orifice area of ​​the first perforated group.

[0011] In one embodiment, the first perforation group includes a plurality of first perforations, and the plurality of first perforations are spaced apart along the length direction of the first column; the second perforation group includes a plurality of second perforations, and the plurality of second perforations are spaced apart along the length direction of the second column.

[0012] In one embodiment, the hydrophobic membrane includes a rough surface and a smooth surface disposed opposite to each other, with the rough surfaces of both hydrophobic membranes facing the mounting frame, and the two rough surfaces and the mounting frame enclosing each other to form the exchange cavity.

[0013] In one embodiment, the membrane exchange unit further includes a sealing gasket and a pressure strip. The sealing gasket is disposed between the hydrophobic membrane and the mounting frame, and the pressure strip is pressed onto the hydrophobic membrane and the hydrophobic membrane and the sealing gasket are fixed to the mounting frame by a connector.

[0014] And / or, the sealing gasket is disposed between the hydrophobic membrane and the pressure strip.

[0015] This application also provides a membrane distillation apparatus, comprising: a shell and a membrane exchange unit as described above, wherein the shell is provided with a receiving cavity, the membrane exchange unit is disposed in the receiving cavity, the shell wall of the shell is provided with a hot end inlet and a hot end outlet, and both the hot end inlet and the hot end outlet are connected to the receiving cavity.

[0016] In one embodiment, the direction in which cold air flows from the cold end inlet to the cold end outlet in the exchange chamber is a first direction, and the direction in which water vapor flows from the hot end inlet to the hot end outlet in the accommodating chamber is a second direction, the first direction being opposite to the second direction.

[0017] In one embodiment, multiple membrane exchange units are provided, and the multiple membrane exchange units are arranged side by side in the accommodating cavity. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Furthermore, the accompanying drawings are not drawn to a 1:1 scale, and the relative dimensions of the various components are shown as examples only and not necessarily to scale. In the accompanying drawings:

[0021] Figure 1 This is a schematic diagram of the membrane distillation apparatus in one embodiment of the present invention;

[0022] Figure 2 for Figure 1 Sectional view of line AA in the middle;

[0023] Figure 3 for Figure 2 Enlarged schematic diagram of the structure at point B in the middle circle;

[0024] Figure 4 This is a schematic diagram of the structure of a membrane exchange unit in one embodiment of the present invention;

[0025] Figure 5 for Figure 4 A cross-sectional view of the CC line;

[0026] Figure 6 for Figure 5 Enlarged schematic diagram of the structure at point D in the middle circle;

[0027] Figure 7 This is a schematic diagram of the membrane exchange unit from another perspective in one embodiment of the present invention;

[0028] Figure 8 This is a schematic diagram of the membrane exchange unit from another perspective in one embodiment of the present invention;

[0029] Figure 9 for Figure 8 Enlarged schematic diagram of the structure at point E in the middle circle;

[0030] Figure 10 This is a schematic diagram of the mounting frame in one embodiment of the present invention;

[0031] Figure 11 This is a schematic diagram of the mounting frame from another perspective in one embodiment of the present invention.

[0032] The components in the diagram are labeled as follows:

[0033] 10. Membrane distillation apparatus; 100. Membrane exchange unit; 110. Mounting frame; 111. First crossbeam; 112. First column; 1121. Cold end inlet; 1122. First perforation; 113. Second crossbeam; 114. Second column; 1141. Cold end outlet; 120. Hydrophobic membrane; 130. Sealing gasket; 140. Pressure strip; 200. Housing; 210. Receptacle; 211. Hot end inlet; 212. Hot end outlet; 220. Gas duct assembly; 221. Main pipe; 222. Branch pipe; 223. Gas pipe. Detailed Implementation

[0034] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0035] Please see Figure 1 and Figure 2 One embodiment of this application provides a membrane exchange unit 100, which is placed inside the housing 200 of a membrane distillation apparatus 10, and water vapor is introduced into the housing 200.

[0036] It should be noted that, because the waste liquid to be purified contains a large number of pollutant ions or molecules, when the waste liquid passes through an evaporation device, such as a distillation tank, and forms water vapor, a large number of pollutant ions or molecules will flow along with the water vapor. Therefore, in this embodiment, the water vapor introduced into the shell 200 does not only contain gaseous water molecules, but also contains a large number of other pollutant ions or molecules.

[0037] Specifically, please refer to Figures 2 to 4 , Figure 7 , Figure 8 as well as Figure 10 The membrane exchange unit 100 includes a mounting frame 110 and two hydrophobic membranes 120. Two hydrophobic membranes 120 are provided, respectively disposed on both sides of the mounting frame 110. The two hydrophobic membranes 120 and the mounting frame 110 enclose an exchange chamber. The mounting frame 110 is provided with a cold-end inlet 1121 and a cold-end outlet 1141, both communicating with the exchange chamber. The cold-end inlet 1121 and the cold-end outlet 1141 are located at opposite ends of the mounting frame 110 and at the top of the exchange chamber. The cold-end inlet 1121 is used to introduce cold air into the exchange chamber, and the cold-end outlet 1141 is used to discharge water vapor entering the exchange chamber.

[0038] In the membrane exchange unit 100 described above, since the mounting frame 110 is provided with a cold end inlet 1121 and a cold end outlet 1141 that are connected to the exchange chamber, cold air can be introduced into the exchange chamber through the cold end inlet 1121. When the membrane exchange unit 100 is placed in the housing 200 of the membrane distillation device 10, a temperature difference is formed on both sides of each hydrophobic membrane 120. Under the action of the pressure difference, water vapor passes through the micropores on the hydrophobic membrane 120 and enters the exchange chamber, and is finally discharged from the cold end outlet 1141 to achieve waste liquid purification. Furthermore, since the cold end inlet 1121 and the cold end outlet 1141 are located at both ends of the mounting frame 110 and at the top of the exchange chamber, when the membrane exchange unit 100 is placed inside the housing 200 of the membrane distillation device 10 and cold air is introduced into the cold end inlet 1121, the characteristics of cold air and water vapor can be fully utilized, namely, the high density of cold air and the low density of water vapor. This causes the cold air entering the exchange chamber to have a tendency to sink first and then rise, which prolongs the flow path of the cold air and allows the water vapor sufficient exchange time, thereby effectively improving the membrane flux and the purification efficiency of the waste liquid.

[0039] It should be noted that the water vapor entering the housing 200 has high humidity and temperature, while the cold air entering the exchange chamber is dry cold air. This increases the pressure difference across the hydrophobic membrane 120, thereby improving the membrane flux of the hydrophobic membrane 120. It should also be noted that due to the inherent characteristics of the hydrophobic membrane 120, when the hydrophobic membrane 120 is inside the housing 200, the micropores on the hydrophobic membrane 120 only allow gaseous water molecules from the water vapor inside the housing 200 to pass through and enter the exchange chamber. Therefore, in this embodiment, "the cold end outlet 1141 is used to discharge the water vapor entering the exchange chamber" means that the cold end outlet 1141 is used to discharge the gaseous water molecules entering the exchange chamber. Therefore, the water vapor in the exchange chamber is different from the water vapor inside the housing; the water vapor in the exchange chamber only contains gaseous water molecules.

[0040] It should be noted that the type of hydrophobic membrane 120 can be selected according to the type of waste liquid to be treated.

[0041] Please see Figure 4 , Figure 7 , Figure 8 , Figure 10 and Figure 11In one embodiment, the mounting frame 110 includes a first crossbeam 111, a first column 112, a second crossbeam 113, and a second column 114. The first crossbeam 111, first column 112, second crossbeam 113, and second column 114 are sequentially connected to form a ring-shaped frame structure. The first column 112 has an air intake channel communicating with the exchange chamber. The top of the first column 112 has a cold end inlet 1121, which communicates with the air intake channel. The second column 114 has an exhaust channel communicating with the exchange chamber. The top of the second column 114 has a cold end outlet 1141, which communicates with the exhaust channel.

[0042] Specifically, by sequentially connecting the first crossbeam 111, the first column 112, the second crossbeam 113, and the second column 114, the mounting frame 110 forms a ring structure, thereby increasing the stability of the hydrophobic membrane 120 mounted on the mounting frame 110. By placing the cold end inlet 1121 at the top of the first column 112 and the cold end outlet 1141 at the top of the second column 114, when cold air enters the exchange chamber, its flow path is generally downward in an oblique direction. During the flow, the cold air undergoes heat and mass transfer with the water vapor outside the hydrophobic membrane 120. The water vapor enters the exchange chamber and mixes with the cold air, and then the cold air carries the water vapor out of the cold end outlet 1141 on the second column 114.

[0043] It should be noted that the "outer side" of the hydrophobic membrane 120 refers to the side of the hydrophobic membrane 120 that faces away from the exchange chamber.

[0044] Specifically, in this embodiment, both the cold end inlet 1121 and the cold end outlet 1141 are arranged facing upwards.

[0045] Alternatively, in other embodiments, the cold end inlet 1121 may be positioned to the right, and the cold end outlet 1141 may be positioned to the left.

[0046] In one embodiment, the mounting frame 110 also includes a support rod (not shown in the figure). The support rod is located inside the exchange chamber and connects between the first column 112 and the second column 114, or between the first crossbeam 111 and the second crossbeam 113. This prevents the two hydrophobic membranes 120 from coming into close contact with each other, which would reduce the volume of the exchange chamber and affect the membrane flux.

[0047] Please see Figure 3 , Figures 5 to 7 as well as Figure 11In one embodiment, the sidewall of the first column 112 is provided with a first perforation group 1122. The air intake channel is connected to the exchange chamber through the first perforation group 1122. The sidewall of the second column 114 is provided with a second perforation group. The exhaust channel is connected to the exchange chamber through the second perforation group. Cold air enters the air intake channel through the cold end inlet 1121, and then enters the exchange chamber through the first perforation group 1122. Water vapor on the outside of the hydrophobic membrane 120 passes through the hydrophobic membrane 120, enters the exhaust channel with the cold air, and is discharged from the cold end outlet 1141.

[0048] To ensure a high flow rate of cold air entering the exchange chamber, please refer to [link / reference needed]. Figure 3 , Figure 5 and Figure 7 In one embodiment, the orifice area of ​​the first perforation group 1122 is smaller than the area of ​​the cold end inlet 1121. In this way, the kinetic energy loss caused by water vapor exchange on both sides of the hydrophobic membrane 120 can be balanced, so that the flow rate of the cold air entering the cold end inlet 1121 and the mixed gas discharged from the cold end outlet 1141 is consistent.

[0049] To improve the stability of exhaust at the cold end outlet 1141, in one embodiment, the orifice area of ​​the second perforation group is greater than or equal to the orifice area of ​​the first perforation group 1122.

[0050] Please see Figure 3 , Figure 5 and Figure 11 In one embodiment, the first perforation 1122 group includes a plurality of first perforations 1122, and the plurality of first perforations 1122 are spaced apart along the length direction of the first column 112. Thus, by spaced apart the plurality of first perforations 1122 along the length direction of the first column 112, the jet expansion of cold air within the exchange chamber can be made more stable, the cold air discharged from each of the second perforations can form a parallel flow, resulting in a uniform velocity field of the cold air at the end face of the exchange chamber and fewer eddies formed within the exchange chamber.

[0051] To further improve the stability of the cold air jet expansion within the exchange chamber, in one embodiment, such as Figure 5 and Figure 11 As shown, multiple first perforations 1122 are arranged opposite each other and at equal intervals along the length direction of the first column 112.

[0052] In one embodiment, the second perforation group includes a plurality of second perforations, and the plurality of second perforations are spaced apart along the length direction of the second column 114.

[0053] Specifically, in this embodiment, multiple second perforations are arranged opposite each other and at equal intervals along the length direction of the second column 114.

[0054] Optionally, in other embodiments, both the first perforation group 1122 and the second perforation group are oblong holes, and the oblong holes extend along the length of the first column 112 or the second column 114. In this way, the exchange chamber can be filled with cold air along the length of the first column 112, allowing water vapor to pass through each area of ​​the hydrophobic membrane 120, thereby improving the membrane flux of the hydrophobic membrane 120.

[0055] In one embodiment, the hydrophobic membrane 120 includes a rough surface and a smooth surface arranged opposite to each other. The rough surfaces of both hydrophobic membranes 120 face the mounting frame 110, and the two rough surfaces and the mounting frame 110 enclose an exchange cavity. Thus, water vapor condenses on the smooth surface to form water droplets. Because the water droplets form on the smooth surface, and flow and drip easily on the smooth surface, it effectively prevents water droplets from clogging the micropores on the hydrophobic membrane 120.

[0056] Alternatively, in other embodiments, the smooth surfaces of the two hydrophobic membranes 120 face the mounting frame 110, and the two smooth surfaces and the mounting frame 110 enclose an exchange cavity.

[0057] Please see Figure 4 , Figure 6 and Figure 9 In one embodiment, the membrane exchange unit 100 further includes a sealing gasket 130 and a pressure strip 140. The sealing gasket 130 is disposed between the hydrophobic membrane 120 and the mounting frame 110, and the pressure strip 140 is pressed onto the hydrophobic membrane 120 and the hydrophobic membrane 120 and the sealing gasket 130 are fixed to the mounting frame 110 by a connector. In this way, the sealing performance of the exchange chamber can be improved, preventing cold air from escaping from the exchange chamber outside the cold end outlet 1141.

[0058] It should be noted that the connecting components in this embodiment include, but are not limited to, screws, bolts, and clips.

[0059] Alternatively, in other embodiments, the sealing gasket 130 is disposed between the hydrophobic membrane 120 and the pressure strip 140. This can also enhance the sealing performance of the exchange chamber.

[0060] Specifically, in this embodiment, sealing gaskets 130 are provided between the hydrophobic membrane 120 and the pressure strip 140, and between the mounting frame 110 and the hydrophobic membrane 120.

[0061] Please see Figures 1 to 3An embodiment of this application also provides a membrane distillation apparatus 10, including: a housing 200 and a membrane exchange unit 100 as described above. The housing 200 has a receiving cavity 210, and the membrane exchange unit 100 is housed within the receiving cavity 210. The shell wall of the housing 200 has a hot-end inlet 211 and a hot-end outlet 212, and both the hot-end inlet 211 and the hot-end outlet 212 are connected to the receiving cavity 210. Water vapor generated by heating the waste liquid can enter the receiving cavity 210 through the hot-end inlet 211, placing the hydrophobic membrane 120 in a humid and hot water vapor environment. Some water vapor passes through the hydrophobic membrane 120 and is discharged from the exchange cavity with cold air, completing the purification of the waste liquid. Water vapor that does not pass through the hydrophobic membrane 120 can be discharged from the receiving cavity 210 through the hot-end outlet 212.

[0062] It should be noted that, due to the characteristics of the hydrophobic membrane 120 itself and the pressure difference on both sides of the hydrophobic membrane 120, only some gaseous water molecules in the water vapor inside the shell 200 can pass through the hydrophobic membrane 120 and enter the exchange chamber, while pollutant ions, pollutant molecules and some gaseous water molecules that have not passed through the hydrophobic membrane 120 will be discharged from the accommodating chamber 210 through the hot end outlet 212.

[0063] In order to further increase membrane flux and improve purification efficiency, in one embodiment, the direction in which cold air flows from the cold end inlet 1121 to the cold end outlet 1141 in the exchange chamber is the first direction, and the direction in which water vapor flows from the hot end inlet 211 to the hot end outlet 212 in the containment chamber 210 is the second direction, and the first direction is opposite to the second direction.

[0064] Specifically, please refer to Figure 2 and Figure 7 Cold air first enters the intake channel through the cold end inlet 1121, then enters the exchange chamber through the first perforation group, and subsequently carries water vapor through the second perforation group into the exhaust channel, finally exiting from the cold end outlet 1141. It can be seen that the flow path of the cold air within the exchange chamber is from right to left. Water vapor enters the receiving chamber 210 through the hot end inlet 211, and water vapor that has not passed through the hydrophobic membrane 120 exits from the hot end outlet 212. It can be seen that the flow path of the water vapor within the receiving chamber 210 is from left to right.

[0065] To improve the purification efficiency of the membrane distillation apparatus 10, in this embodiment, such as Figure 1 , Figure 2 and Figure 7 As shown, multiple membrane exchange units 100 are provided. Multiple membrane exchange units 100 are arranged side by side in the accommodating cavity 210, and the cold end inlets 1121 of each membrane exchange unit 100 are arranged side by side, and the cold end outlets 1141 of each membrane exchange unit 100 are arranged side by side.

[0066] Please see Figures 1 to 3 as well as Figure 7 In one embodiment, the membrane distillation apparatus 10 further includes a gas guide tube assembly 220, and there are two gas guide tube assemblies 220, one of which is used to simultaneously introduce cold air into each cold end inlet 1121, and the other is used to simultaneously discharge the mixed gas (water vapor and cold air) discharged from each cold end outlet 1141.

[0067] Specifically, such as Figures 1 to 3 as well as Figure 7 As shown, the air duct assembly 220 includes a main pipe 221 and multiple branch pipes 222, all of which are connected to the main pipe 221. The number of branch pipes 222 is the same as the number of cold end inlets 1121 or cold end outlets 1141, and they are connected one-to-one. Taking the air duct assembly 220 connected to the cold end inlet 1121 as an example, cold air is usually directly introduced into the main pipe 221, and then flows to each branch pipe 222 to enter the corresponding cold end inlet 1121.

[0068] Furthermore, the air duct assembly 220 also includes an air duct 223 connected to the main pipe 221, and at least one air duct 223 is provided.

[0069] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0070] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0071] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0072] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A membrane exchange unit for placement within a housing of a membrane distillation device, and into which housing water vapor is admitted, characterized by, The membrane exchange unit comprises a mounting frame and two hydrophobic membranes, the two hydrophobic membranes are arranged on two sides of the mounting frame respectively, and the two hydrophobic membranes and the mounting frame form an exchange cavity. The mounting frame comprises a first cross beam frame, a first vertical column, a second cross beam frame and a second vertical column, and the first cross beam frame, the first vertical column, the second cross beam frame and the second vertical column are sequentially connected to form a ring-shaped frame structure, the first vertical column is internally provided with an air inlet channel connected with the exchange cavity, and the top end of the first vertical column is provided with a cold end inlet, and the cold end inlet is in communication with the air inlet channel; the second vertical column is internally provided with an air outlet channel connected with the exchange cavity, and the top end of the second vertical column is provided with a cold end outlet, and the cold end outlet is in communication with the air outlet channel, the cold end inlet is used for introducing cold air into the exchange cavity, and the cold end outlet is used for discharging water vapor in the exchange cavity.

2. The membrane exchange unit of claim 1, wherein, The side wall of the first vertical column is provided with a first perforated group, and the air inlet channel is in communication with the exchange cavity through the first perforated group; the side wall of the second vertical column is provided with a second perforated group, and the air outlet channel is in communication with the exchange cavity through the second perforated group.

3. The membrane exchange unit of claim 2, wherein, The orifice area of the first perforated group is smaller than the area of the cold end inlet, and the orifice area of the second perforated group is greater than or equal to the orifice area of the first perforated group.

4. The membrane exchange unit of claim 3, wherein, The first perforated group comprises a plurality of first perforations, and the plurality of first perforations are arranged at intervals along the length direction of the first vertical column; the second perforated group comprises a plurality of second perforations, and the plurality of second perforations are arranged at intervals along the length direction of the second vertical column.

5. The membrane exchange unit according to any one of claims 1-4, characterized in that, The hydrophobic membrane comprises a rough surface and a smooth surface arranged oppositely, and the rough surfaces of the two hydrophobic membranes are both directed to the mounting frame, and the rough surfaces and the mounting frame form the exchange cavity.

6. The membrane exchange unit of any one of claims 1-4, wherein, The membrane exchange unit further comprises a sealing gasket and a pressing strip, the sealing gasket is arranged between the hydrophobic membrane and the mounting frame, and the pressing strip is arranged on the hydrophobic membrane and fixes the hydrophobic membrane and the sealing gasket on the mounting frame through a connecting piece; And / or, the sealing gasket is arranged between the hydrophobic membrane and the pressing strip.

7. The membrane exchange unit of claim 6, wherein, The connecting piece comprises a screw, a bolt and a buckle.

8. A membrane distillation device, characterized in that, Comprise: A housing and the membrane exchange unit of any one of claims 1-7, the housing is internally provided with a containing cavity, the membrane exchange unit is contained in the containing cavity, and the shell wall of the housing is provided with a hot end inlet and a hot end outlet, and the hot end inlet and the hot end outlet are both in communication with the containing cavity.

9. The membrane distillation device of claim 8, wherein, The direction of the cold air flowing from the cold end inlet to the cold end outlet in the exchange cavity is a first direction, the direction of the water vapor flowing from the hot end inlet to the hot end outlet in the containing cavity is a second direction, and the first direction is opposite to the second direction.

10. The membrane distillation device of claim 8, wherein, The membrane exchange unit is provided with a plurality of membrane exchange units, and the plurality of membrane exchange units are arranged side by side in the containing cavity.

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