Side-flow water purification membrane structure and filter element

Abstract

The present invention provides a side-flow water purification membrane structure. The side-flow water purification membrane structure includes a central tube and a membrane module. The central tube includes at least one pure water pipe assembly. Each pure water pipe assembly includes two pure water pipes, and the two pure water pipes include a first pure water pipe and a second pure water pipe. The membrane module covers the outer wall of the central tube. The membrane module includes a first membrane module and a second membrane module. The first membrane module is connected to the first pure water pipe. The first membrane module includes a first functional layer, a filtration layer, and a second functional layer arranged in sequence. The second membrane module is connected to the second pure water pipe. The second membrane module includes the first functional layer and the filtration layer arranged in sequence. The second functional layer of the first membrane module is adjacent to the filtration layer of the second membrane module. The present invention also provides a filter element. The two sides of the second functional layer at any position must be adjacent to the filtration layer, having higher filtration efficiency.

Description

Technical Field

[0001] The present invention relates to the field of water purification, and particularly to a side-flow water purification membrane structure and a filter element. Background Art

[0002] With the development of society, water purification equipment has gradually entered thousands of households. In water purification equipment based on reverse osmosis technology, the structure of the reverse osmosis membrane filter element plays a crucial role. Different manufacturers adopt different reverse osmosis membrane filter element technologies and manufacture reverse osmosis membrane filter elements with different structures.

[0003] In a reverse osmosis membrane filter element, using a side-flow water purification membrane structure can significantly extend the life and recovery rate of the reverse osmosis membrane. The current side-flow water purification membrane structure uses a central tube, which is divided into two halves. One half is a pure water tube, and the other half is a waste water tube. However, since there is only half a pure water tube, only a single-page membrane can be wound, and the flow rate of a single component cannot be increased when winding a single-page membrane.

[0004] There is also a side-flow water purification membrane structure that uses multiple pure water tubes connected to membrane components to form a central tube. In this solution, each pure water tube is in a centrally symmetric form, and there is a large gap in the middle of the formed central tube, which cannot stably support the membrane. At the same time, all the membrane components are exactly the same. Since the membrane component includes multiple functional layers, during the winding process, the outer functional layers of two adjacent membrane components are adjacent to each other, rather than adjacent to the filter membrane, which makes the diameter of the entire product larger and the filtration efficiency lower. Summary of the Invention

[0005] The purpose of the present invention is to provide at least a new side-flow water purification membrane structure.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A side-flow water purification membrane structure, the side-flow water purification membrane structure includes a central tube and a membrane component,

[0008] The central tube includes at least one pure water tube component, each pure water tube component includes two pure water tubes, and the two pure water tubes include a first pure water tube and a second pure water tube;

[0009] The membrane component wraps the outer wall of the central tube, the membrane component includes a first membrane component and a second membrane component, and each membrane component contains at least any one of a first functional layer, a second functional layer, and a filtration layer,

[0010] The first membrane component is connected to the first pure water tube, and the first membrane component includes the first functional layer, the filtration layer, and the second functional layer arranged in sequence;

[0011] The second membrane module is connected to the second pure water pipe, and the second membrane module includes the first functional layer and the filtration layer arranged in sequence;

[0012] The second functional layer of the first membrane module is adjacent to the filtration layer of the second membrane module.

[0013] In the present invention, the main functions of the first functional layer and the second functional layer are to transport and guide the water at the corresponding positions, and they can be the same or different. The first functional layer and the second functional layer can be an inlet grid layer and a pure water guide cloth respectively. The membrane module can be made by means of, for example, 3D printing technology. Between the layers of the membrane module, they can be fastened to each other by means including but not limited to mechanical stacking, physical compounding, chemical crosslinking, etc. In the structure of the central pipe, whether it is between the membrane modules in the same pure water pipe assembly or between the membrane modules in adjacent pure water pipe assemblies, it is always the second functional layer that is adjacent to the filtration layer, overcoming the disadvantageous setting in the prior art where the second functional layer such as the inlet grid layer is adjacent between different membrane modules. Under certain thickness and usage amount of the membrane module, higher filtration efficiency can be ensured.

[0014] In some embodiments, the first functional layer is a pure water guide cloth, and the second functional layer is an inlet grid layer.

[0015] In this solution, two different membrane modules are connected in each pure water pipe assembly, so that during the process of winding the membrane module onto the outer wall of the central pipe, it is ensured that the inlet grid layer is adjacent to the filtration layer, and the raw water in the inlet grid layer can be directly filtered by the adjacent filtration layer, achieving higher filtration efficiency under the same diameter.

[0016] In some embodiments, at least a part of the first functional layer of the first membrane module is in close contact with the first pure water pipe; at least a part of the first functional layer of the second membrane module is in close contact with the second pure water pipe.

[0017] In some embodiments, the first functional layer is an inlet grid layer, the second functional layer is a pure water guide cloth, at least a part of the first functional layer of the first membrane module is in close contact with the first pure water pipe; at least a part of the first functional layer of the second membrane module is in close contact with the second pure water pipe.

[0018] In some embodiments, the filtration layer includes a substrate layer and a filtration functional layer provided on the substrate layer, and the filtration functional layer is adjacent to the second functional layer.

[0019] In some embodiments, the filtration layer includes a substrate layer and a filtration functional layer provided on the substrate layer, and the substrate layer is adjacent to the second functional layer.

[0020] In some embodiments, the pure water pipe includes an outer wall of the pure water pipe, a front wall of the pure water pipe, a rear wall of the pure water pipe, and an inner wall of the pure water pipe; the outer wall of the pure water pipe forms a part of the outer wall of the central pipe, and the inner wall of the pure water pipe forms a part of the inner wall of the central pipe; among two adjacent pure water pipes, the front wall of the pure water pipe of one of them is fitted with the rear wall of the pure water pipe of the other.

[0021] Whether it is two pure water pipes in the same pure water pipe assembly or two pure water pipes belonging to different pure water pipe assemblies, as long as they are adjacent, the front wall of the pure water pipe of one of them is fitted with the rear wall of the pure water pipe of the other, which can ensure that there are almost no gaps in the overall outer wall of the central pipe, can provide stable support for the wrapped membrane assembly, and ensure the tightness of each waterway.

[0022] In some embodiments, the front wall of the pure water pipe faces forward and downward and is recessed inward in an arc shape.

[0023] In some embodiments, the rear wall of the pure water pipe faces backward and downward and protrudes outward in an arc shape. Through the above settings, the cross-section of the pure water pipe is in the shape of ",", each pure water pipe is standardized, which is convenient for processing, and can be used as the first pure water pipe or the second pure water pipe.

[0024] In some embodiments, among two adjacent pure water pipes, the outer walls of the two pure water pipes are adjacent to each other, and the outer wall of the central pipe is substantially cylindrical.

[0025] In some embodiments, each membrane assembly winds around the pure water pipe, the middle part of the membrane assembly fits with the inner wall of the pure water pipe at the corresponding position, and the two side parts of the membrane assembly wind from the rear wall of the pure water pipe at the corresponding position to the front wall of the pure water pipe.

[0026] In some embodiments, a water guide groove is provided on the outer wall of the pure water pipe. The water guide groove is arranged along the water flow direction, and there can be multiple water guide grooves.

[0027] The central pipe can include any number (1, 2, 3, 4...) of pure water pipe assemblies. In some embodiments, the central pipe includes two pure water pipe assemblies, the first pure water pipe and the second pure water pipe are arranged alternately, and the first membrane assembly and the second membrane assembly wind around the outer wall of the central pipe in the same direction.

[0028] In some embodiments, the filter layer includes a substrate layer and a filter functional layer provided on the substrate layer. The filter functional layer can be a separation membrane with selective permeability. The filter layer includes, but is not limited to, one of a reverse osmosis membrane, a nanofiltration membrane, and an ultrafiltration membrane.

[0029] The present invention also provides a filter element having the aforementioned side-flow type water purification membrane structure. The filter element includes a central tube, a secondary central tube, a first end cap, a second end cap, and a membrane assembly wound around the central tube. The central tube includes a plurality of pure water pipes fixedly connected to each other. The first end cap and the second end cap are respectively disposed at two ends of the central tube. The first end cap is provided with a first water flow inlet and a second water flow inlet;

[0030] Inside each of the pure water pipes forms a first water flow channel, and the first water flow channel communicates with the first water flow inlet on the first end cap;

[0031] A cavity is formed between the plurality of pure water pipes. The secondary central tube is disposed in the cavity. Inside the secondary central tube with through holes on its outer wall forms a second water flow channel, and the second water flow channel communicates with the second water flow inlet;

[0032] A third water flow inlet and outlet is formed on the outer surface of the membrane assembly,

[0033] The central tube includes at least one pure water pipe assembly. Each pure water pipe assembly includes two pure water pipes, and the two pure water pipes include a first pure water pipe and a second pure water pipe;

[0034] The membrane assembly contains at least any one of a first functional layer, a second functional layer, and a filtration layer. The membrane assembly includes a first membrane assembly and a second membrane assembly,

[0035] The first membrane assembly is connected to the first pure water pipe. The first membrane assembly includes the first functional layer, the filtration layer, and the second functional layer arranged in sequence;

[0036] The second membrane assembly is connected to the second pure water pipe. The second membrane assembly includes the first functional layer and the filtration layer arranged in sequence;

[0037] The second filtration layer of the first membrane assembly is adjacent to the filtration layer of the second membrane assembly.

[0038] The first water flow inlet, the second water flow inlet, and the third water flow inlet and outlet can respectively serve as the raw water inlet, the pure water outlet, and the waste water outlet. The first water flow inlet and the second water flow inlet can be concentrically arranged. For better sealing effect, a sealing ring is sleeved on the outer periphery of the first water flow inlet and / or the outer periphery of the second water flow inlet.

[0039] In some embodiments, the first functional layer is a pure water guiding cloth, and the second functional layer is an inlet grid layer.

[0040] In some embodiments, at least a portion of the first functional layer of the first membrane module is in close contact with the first pure water pipe; at least a portion of the first functional layer of the second membrane module is in close contact with the second pure water pipe.

[0041] In some embodiments, the first functional layer is an inlet grid layer, the second functional layer is a pure water guide cloth, at least a portion of the first functional layer of the first membrane module is in close contact with the first pure water pipe; at least a portion of the first functional layer of the second membrane module is in close contact with the second pure water pipe.

[0042] In some embodiments, the filter layer includes a substrate layer and a filter functional layer provided on the substrate layer, and the filter functional layer is adjacent to the second functional layer.

[0043] In some embodiments, the filter layer includes a substrate layer and a filter functional layer provided on the substrate layer, and the substrate layer is adjacent to the second functional layer.

[0044] Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art:

[0045] As described above, in the side-flow type water purification membrane structure provided by the present invention, both sides of any inlet grid layer must be adjacent to the filter membrane, overcoming the disadvantageous setting in the prior art where the inlet grid layers between different membrane modules are adjacent. Under certain thickness and usage amount of the membrane module, a higher filtration efficiency can be ensured.

[0046] In addition, for any two adjacent pure water pipes, the front wall of the pure water pipe of one is fitted with the rear wall of the pure water pipe of the other, which can ensure that there are almost no gaps on the outer wall of the central pipe, provide stable support for the wrapped membrane module, and ensure the sealing of each water path. Since the structure of the side-flow membrane itself changes the flow direction of the inlet water, making the inlet water flow channel narrower, accelerating the flushing speed on the surface of the membrane sheet, reducing the concentration polarization phenomenon, and improving the removal rate performance and service life of the membrane module. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic structural diagram of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0048] Figure 2 It is a schematic cross-sectional structure diagram of a first section of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0049] Figure 3 It is a schematic structural diagram of a first end cap of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0050] Figure 4Schematic diagram of the second cross-sectional structure of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0051] Figure 5 Schematic diagram of the second end cap structure of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0052] Figure 6 Schematic diagram of the cross-sectional structure before winding of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0053] Figure 7 Schematic diagram of the cross-sectional structure of a first pure water pipe of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0054] Figure 8 Schematic diagram of the cross-sectional structure of a second pure water pipe of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0055] Figure 9 Schematic diagram of the structure of the secondary central pipe of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0056] Figure 10 Schematic diagram of the structure of the pure water pipe of a filter element containing the side-flow type water purification membrane structure provided in the present invention;

[0057] Figure 11 Schematic diagram of the first end cap structure of another filter element containing the side-flow type water purification membrane structure provided in the present invention. Detailed implementation manners

[0058] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0059] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0060] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] As Figures 1-10 shown, the present invention provides a filter element with a side-flow water purification membrane structure. The filter element includes a central tube, a secondary central tube 5, a first end cap 21, a second end cap 22, and a membrane module 1 wound around the central tube. The central tube includes a plurality of pure water pipes 3 fixedly connected. The first end cap 21 and the second end cap 22 are respectively arranged at both ends of the central tube. The first end cap 21 is provided with a first water inlet / outlet 212 and a second water inlet / outlet 211 and is communicated with an external device through a protruding portion 210.

[0062] A water guide groove is arranged on the outer wall of the pure water pipe 3. A first water flow channel 30 is formed inside each pure water pipe 3, and the first water flow channel 30 is communicated with the first water inlet / outlet 212 on the first end cap 21; a cavity is formed between the plurality of pure water pipes 3. The secondary central tube 5 is arranged in the cavity. A second water flow channel 51 is formed inside the secondary central tube 5 with through holes 52 on its outer wall, and the second water flow channel 51 is communicated with the second water inlet / outlet 211; as Figure 1 shown, a third water inlet / outlet is formed on the outer surface of the membrane module 1. The second end cap 22 closes the other end of the filter element through a connecting portion 220 inserted into the secondary central tube 5.

[0063] The central tube includes at least one pure water pipe assembly. In some embodiments, as Figure 2 , Figure 4 and Figure 6 shown, the number of pure water pipe assemblies is 2; in other embodiments, as Figure 11 shown, the number of pure water pipe assemblies is 3. Each pure water pipe assembly includes two pure water pipes 3, and the two pure water pipes include a first pure water pipe 301 and a second pure water pipe 302; each pure water pipe 3 includes a pure water pipe outer wall 34, a pure water pipe front wall 31, a pure water pipe rear wall 33, and a pure water pipe inner wall 32; the pure water pipe outer wall 34 constitutes a part of the outer wall of the central tube, and the pure water pipe inner wall 32 constitutes a part of the inner wall of the central tube; among two adjacent pure water pipes 3, the pure water pipe front wall 31 of one pure water pipe 3 is fitted with the pure water pipe rear wall 33 of the other pure water pipe 3.

[0064] The membrane module 1 contains at least any one of the first functional layer 11, the filtration layer 12, and the second functional layer 13. The first functional layer 11 and the second functional layer 13 can be pure water conducting cloth or an inlet water grid layer respectively; the filtration layer 12 includes a substrate layer and a filtration functional layer provided on the substrate layer. The filtration functional layer can be a separation membrane with selective permeability, and the filtration layer 12 is selected from one of a reverse osmosis membrane, a nanofiltration membrane, and an ultrafiltration membrane. The membrane module 1 includes a first membrane module 101 connected to the first pure water pipe 301 and a second membrane module 102 connected to the second pure water pipe 302. The first membrane module includes the first functional layer 11, the filtration layer 12, and the second functional layer 13 arranged in sequence; the second membrane module 102 includes the first functional layer 11 and the filtration layer 12 arranged in sequence; the second functional layer 13 of the first membrane module 301 is adjacent to the filtration layer 12 of the second membrane module 302.

[0065] As Figure 6 shown, among two adjacent pure water pipes 3, the outer walls 34 of the two pure water pipes 3 are adjacent to each other, and the outer wall of the central pipe is substantially cylindrical. Each membrane module 1 winds around the pure water pipe 3. The membrane module 1 includes a middle part and two side parts. In each membrane module 1, the structures of the middle part and the two side parts are the same; the inner side of the middle part is the first functional layer 11, and the first functional layer 11 is attached to the inner wall 32 of the pure water pipe at the corresponding position. In the first membrane module 101, the outside of the membrane module 1 is the second functional layer 13. At this time, the second functional layer 13 is adjacent to the secondary central pipe 5 in the cavity formed by the central pipe. The second membrane module 102 does not contain the second functional layer 13. Among them, the outside of the membrane module 1 is the filtration layer 12. At this time, the filtration layer 12 is adjacent to the secondary central pipe 5 in the cavity formed by the central pipe. The two side parts of the membrane module 1 wind from the rear wall 33 of the pure water pipe at the corresponding position to the front wall 31 of the pure water pipe. As Figure 7 , 10 shown, the front wall 31 of the pure water pipe faces forward and downward and is recessed inward in an arc shape. The rear wall 33 of the pure water pipe faces backward and downward and protrudes outward in an arc shape. Through the above settings, the cross-section of the pure water pipe 3 is in the shape of ",", and each pure water pipe 3 is standardized, which is convenient for processing and can be used as the first pure water pipe 301 or the second pure water pipe 302. The outer wall 34 of the pure water pipe is provided with a water guide groove 35, and the water guide groove 35 is communicated with the first water flow channel 30 inside the pure water pipe 3. The water guide groove 35 is arranged along the water flow direction, and the water guide groove 35 can be multiple.

[0066] The first water flow inlet and outlet, the second water flow inlet and outlet, and the third water flow inlet and outlet can all be used as the raw water inlet, the pure water outlet, and the wastewater outlet respectively. The following will be described in conjunction with the attached Figures 6-8 drawings and several embodiments.

[0067] Embodiment 1

[0068] The first water flow inlet and outlet is the pure water outlet, the second water flow inlet and outlet is the wastewater outlet, and the third water flow inlet and outlet is the raw water inlet

[0069] In this embodiment, the first functional layer 11 is a pure water guiding cloth, and the second functional layer 13 is an inlet water grid layer. At this time, the outer surface of the membrane module 1 of the filter element is the inlet water grid layer, and the filtering functional layer of the filtering layer 12 faces the second functional layer 13.

[0070] Raw water enters the membrane module 1 through the third water flow inlet and outlet on the side. The pure water filtered by the filtering layer 12 is guided by the pure water guiding cloth 11 and enters the first water flow channel 30 inside the pure water pipe 3 through the water guiding groove on the outer wall of the pure water pipe 3, and then is discharged through the first water flow inlet and outlet 212. The wastewater on the other side of the filtering layer 12 enters the second water flow channel 51 in the secondary central pipe 5 and is then discharged through the second water flow inlet and outlet 211.

[0071] Embodiment Two

[0072] The first water flow inlet and outlet is a wastewater outlet, the second water flow inlet and outlet is a pure water outlet, and the third water flow inlet and outlet is a raw water inlet

[0073] The difference between this embodiment and Embodiment One is that the filtering functional layer of the filtering layer 12 faces the first functional layer 11.

[0074] Raw water enters the membrane module 1 through the third water flow inlet and outlet on the side. The wastewater that has not been filtered by the filtering layer 12 is guided by the pure water guiding cloth 11 and enters the first water flow channel 30 inside the pure water pipe 3 through the water guiding groove on the outer wall of the pure water pipe 3, and then is discharged through the first water flow inlet and outlet 212. The pure water on the other side of the filtering layer 12 enters the second water flow channel 51 in the secondary central pipe 5 and is then discharged through the second water flow inlet and outlet 211.

[0075] Embodiment Three

[0076] The first water flow inlet and outlet is a raw water inlet, the second water flow inlet and outlet is a pure water outlet, and the third water flow inlet and outlet is a wastewater outlet

[0077] In this embodiment, the first functional layer 11 is an inlet water grid layer, and the second functional layer 13 is a pure water guiding cloth. At this time, the outer surface of the membrane module 1 of the filter element is the pure water guiding cloth, and the filtering functional layer of the filtering layer 12 faces the first functional layer 11.

[0078] Raw water flows into the first water flow channel 30 through the first water flow inlet and outlet 212, and enters the first functional layer 11 through the water guiding groove. The wastewater that has not been filtered by the filtering layer 12 is guided by the inlet water grid of the first functional layer 11 and flows out of the membrane module 1 through the third water flow inlet and outlet on the side; the pure water filtered by the filtering layer 12 is guided by the pure water guiding cloth of the second functional layer 13 and then enters the second water flow channel 51 in the secondary central pipe 5 and is then discharged through the second water flow inlet and outlet 211.

[0079] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. It should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A side-flow water purification membrane structure, the side-flow water purification membrane structure comprising a central tube and a membrane module, Characterized in that, The central tube includes at least one pure water pipe assembly, each pure water pipe assembly including two pure water pipes, the two pure water pipes including a first pure water pipe and a second pure water pipe; The membrane module coats the outer wall of the central tube, the membrane module including a first membrane module and a second membrane module, each membrane module containing at least any one of a first functional layer, a second functional layer and a filtration layer, The first membrane module is connected to the first pure water pipe, the first membrane module including the first functional layer, the filtration layer and the second functional layer arranged in sequence; The second membrane module is connected to the second pure water pipe, the second membrane module including the first functional layer and the filtration layer arranged in sequence; The second functional layer of the first membrane module is adjacent to the filtration layer of the second membrane module; The pure water pipe includes a pure water pipe outer wall, a pure water pipe front wall, a pure water pipe rear wall and a pure water pipe inner wall; The pure water pipe outer wall constitutes a part of the outer wall of the central tube, and the pure water pipe inner wall constitutes a part of the inner wall of the central tube; Among two adjacent pure water pipes, the pure water pipe front wall of one of the pure water pipes is fitted with the pure water pipe rear wall of the other pure water pipe; The pure water pipe front wall faces forward and downward and is recessed inward in an arc shape; The pure water pipe rear wall faces backward and downward and protrudes outward in an arc shape.

2. The side-flow water purification membrane structure according to claim 1, Characterized in that: The first functional layer is a pure water guiding cloth, and the second functional layer is a water inlet grid layer.

3. The side-flow water purification membrane structure according to claim 2, Characterized in that: At least a part of the first functional layer of the first membrane module is in close contact with the first pure water pipe; at least a part of the first functional layer of the second membrane module is in close contact with the second pure water pipe.

4. The side-flow water purification membrane structure according to claim 1, Characterized in that: The first functional layer is a water inlet grid layer, the second functional layer is a pure water guiding cloth, at least a part of the first functional layer of the first membrane module is in close contact with the first pure water pipe; at least a part of the first functional layer of the second membrane module is in close contact with the second pure water pipe.

5. The side-flow water purification membrane structure according to claim 2, Characterized in that: The filtration layer includes a substrate layer and a filtration functional layer provided on the substrate layer, and the filtration functional layer is adjacent to the second functional layer.

6. The side-flow water purification membrane structure according to claim 2, Characterized in that: The filtration layer includes a substrate layer and a filtration functional layer provided on the substrate layer, and the substrate layer is adjacent to the second functional layer.

7. The side-flow water purification membrane structure according to claim 1, Characterized in that: Among two adjacent pure water pipes, the pure water pipe outer walls of the two pure water pipes are adjacent to each other, and the outer wall of the central tube is substantially cylindrical.

8. The side-flow water purification membrane structure according to claim 1, Characterized in that: Each of the membrane modules winds around the pure water pipe, the middle part of the membrane module is attached to the inner wall of the pure water pipe at the corresponding position, and both side parts of the membrane module wind from the rear wall of the pure water pipe at the corresponding position to the front wall of the pure water pipe.

9. The side-flow type water purification membrane structure according to any one of claims 1-6, characterized in that: The central pipe includes two pure water pipe assemblies, the first pure water pipe and the second pure water pipe are arranged alternately, and the first membrane module and the second membrane module wind around the outer wall of the central pipe in the same direction.

10. The side-flow type water purification membrane structure according to any one of claims 5 or 6, characterized in that: The filtration functional layer is a separation membrane with selective permeability.

11. A filter element, which includes a central pipe, a secondary central pipe, a first end cap, a second end cap, and a membrane module wound around the central pipe. The central pipe includes a plurality of fixedly connected pure water pipes. The first end cap and the second end cap are respectively arranged at both ends of the central pipe. The first end cap is provided with a first water flow inlet and outlet and a second water flow inlet and outlet; The inside of each pure water pipe forms a first water flow channel, and the first water flow channel communicates with the first water flow inlet and outlet on the first end cap; A cavity is formed between the plurality of pure water pipes, the secondary central pipe is arranged in the cavity, and a second water flow channel is formed inside the secondary central pipe with through holes on the outer wall, and the second water flow channel communicates with the second water flow inlet and outlet; A third water flow inlet and outlet is formed on the outer surface of the membrane module, characterized in that, The central pipe includes at least one pure water pipe assembly, each pure water pipe assembly includes two pure water pipes, and the two pure water pipes include a first pure water pipe and a second pure water pipe; The membrane module includes a first membrane module and a second membrane module, and each membrane module contains at least any one of a first functional layer, a second functional layer, and a filtration layer, The first membrane module is connected to the first pure water pipe, and the first membrane module includes the first functional layer, the filtration layer, and the second functional layer arranged in sequence; The second membrane module is connected to the second pure water pipe, and the second membrane module includes the first functional layer and the filtration layer arranged in sequence; The second functional layer of the first membrane module is adjacent to the filtration layer of the second membrane module; The pure water pipe includes a pure water pipe outer wall, a pure water pipe front wall, a pure water pipe rear wall, and a pure water pipe inner wall; The pure water pipe outer wall constitutes a part of the outer wall of the central pipe, and the pure water pipe inner wall constitutes a part of the inner wall of the central pipe; Among two adjacent pure water pipes, the pure water pipe front wall of one of them is fitted with the pure water pipe rear wall of the other pure water pipe; The pure water pipe front wall faces forward and downward and is recessed inward in an arc shape; The pure water pipe rear wall faces backward and downward and protrudes outward in an arc shape.

12. The filter element according to claim 11, characterized in that: The first functional layer is a pure water guiding cloth, and the second functional layer is a water inlet grid layer.

13. The filter element according to claim 12, characterized in that: At least part of the first functional layer of the first membrane module is in close contact with the first pure water pipe; at least part of the first functional layer of the second membrane module is in close contact with the second pure water pipe.

14. The filter element according to claim 11, characterized in that: The first functional layer is an inlet grid layer, the second functional layer is a pure water guide cloth, and at least part of the first functional layer of the first membrane module is in close contact with the first pure water pipe; at least part of the first functional layer of the second membrane module is in close contact with the second pure water pipe.

15. The filter element according to claim 12, characterized in that: The filter layer includes a substrate layer and a filtering functional layer provided on the substrate layer, and the filtering functional layer is adjacent to the second functional layer.

16. The filter element according to claim 12, characterized in that: The filter layer includes a substrate layer and a filtering functional layer provided on the substrate layer, and the substrate layer is adjacent to the second functional layer.

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