Membrane element tandem type filter element and water purification equipment

Abstract

The utility model relates to the technical field of water purification filter elements, in particular to a filter element with serially connected membrane elements and water purification equipment, which comprises a cylindrical membrane shell and a plurality of cylindrical membrane elements, and the outer diameter of each membrane element is smaller than the inner diameter of the membrane shell; the plurality of membrane elements are arranged in the membrane shell along the length extension direction of the membrane shell; the membrane element and the membrane shell are coaxially arranged; the multiple membrane elements are connected end to end, and in every two adjacent membrane elements, the first wastewater outlet of the former membrane element is communicated with the first raw water inlet of the latter membrane element; a first raw water inlet of the head-end membrane element is communicated with a second raw water inlet formed in the membrane shell; a first wastewater outlet of the tail end membrane element is communicated with a second wastewater outlet formed in the membrane shell; pure water produced by the membrane element flows out from a second pure water outlet formed in the membrane shell. The whole filter element is of a cylindrical structure, and the integration level is higher. According to the utility model, arrangement and arrangement are carried out during use and sub-packaging is carried out during transportation, and the overall arrangement is more compact, so that the space can be saved.

Description

Technical Field

[0001] The utility model relates to the technical field of water purification filter elements, in particular to a membrane element series filter element and water purification equipment. Background Art

[0002] As water safety receives more and more attention and importance, water purification equipment is no longer only found in households. In the commercial water supply field, the demand for large-flow water purification equipment is also increasing.

[0003] The Chinese utility model patent with publication number CN220413096U discloses a large-flux zero-stale water nanofiltration water purification system, including a filtration system, a reflux system, a normal temperature water system and a hot water system, wherein the filtration system is used to filter the incoming water and transport the pure water to the normal temperature water system and the reflux system. The filtration system includes a low-pressure switch, a water inlet valve, a booster pump, a PP cotton filter element, a granular activated carbon filter element, a composite activated carbon filter element, a nanofiltration filter element and a wastewater valve.

[0004] In order to achieve sufficient filtration, the water purification system in the prior art uses multiple filter mechanisms in series. In the water purification system in the prior art, the multiple filter mechanisms are all independently connected in series, such as using different PP cotton filter elements, granular activated carbon filter elements, composite activated carbon filter elements, nanofiltration filter elements, etc. The filter mechanism integration of this filtration system is low, and the scattered filter mechanisms will cause great inconvenience to users no matter how to arrange and lay them during installation or how to package them during transportation. Utility Model Content

[0005] In order to solve the above problems, the purpose of the utility model is to provide a membrane element series filter element and water purification equipment.

[0006] The technical solution provided by the utility model is:

[0007] In a first aspect, a membrane element series filter element comprises:

[0008] The membrane shell is cylindrical, and the two ends of the membrane shell are respectively provided with a second raw water inlet and a second waste water outlet, and the membrane shell is also provided with a second pure water outlet;

[0009] A plurality of membrane elements are cylindrical, and the outer diameter of the membrane elements is smaller than the inner diameter of the membrane shell; the plurality of membrane elements are arranged in the membrane shell along the length extension direction of the membrane shell;

[0010] in:

[0011] The membrane element and the membrane housing are coaxially arranged;

[0012] The plurality of membrane elements are connected end to end, and in two adjacent membrane elements, the first wastewater outlet of the preceding membrane element is connected to the first raw water inlet of the succeeding membrane element;

[0013] The first raw water inlet of the head end membrane element is connected with the second raw water inlet provided in the membrane shell;

[0014] The first wastewater outlet of the tail end membrane element is connected to the second wastewater outlet provided in the membrane shell;

[0015] The pure water produced by the membrane element flows out from the second pure water outlet provided on the membrane shell.

[0016] As an optional technical solution of the first aspect, the membrane element includes a central tube and a membrane bag wound on the central tube;

[0017] The two ends of the center tube are respectively equipped with a front cover and a rear cover;

[0018] in:

[0019] The front cover and the rear cover are both provided with an outlet for the end of the central tube to extend out;

[0020] The front end cover is sealed and connected to one end of the rolled membrane bag, and the first raw water inlet is arranged on the inner circle of the front end cover;

[0021] The rear end cover is sealed and connected to the other end of the rolled film bag;

[0022] The central tube is used to export the pure water produced by the membrane element, and the central tube is connected to the second pure water outlet.

[0023] Optionally, the first wastewater outlet is arranged on a side of the membrane element close to the membrane shell;

[0024] A wastewater flow channel for wastewater to flow is provided between the membrane element and the inner wall of the membrane shell.

[0025] The front end cover is sealedly connected to the inner wall of the membrane shell, and a channel communicating with the wastewater flow channel is provided between the rear end cover and the inner wall of the membrane shell.

[0026] Optionally, the film bag is provided with two opposite long sides and two opposite short sides;

[0027] One short side is connected to the central tube, the membrane bag is wound on the central tube along the extension direction of the long side, and the first wastewater outlet is arranged at the other short side;

[0028] The first raw water inlet is arranged at one of the long sides close to one end of the central tube;

[0029] A raw water flow channel connected to the first raw water inlet and the first waste water outlet is formed inside the membrane bag, and a pure water flow channel connected to the central tube is formed outside the membrane bag;

[0030] A guide net is provided at one end of the pure water flow channel close to the first raw water inlet.

[0031] Optionally, the first wastewater outlet is provided at one end of the membrane element close to the rear end cover;

[0032] The front cover, the rear cover and the inner wall of the membrane shell are all sealed and connected.

[0033] Further, the film bag is provided with two opposite long sides and two opposite short sides;

[0034] Among them, one short side is connected to the central tube, and the film bag is wound on the central tube along the extension direction of the long side;

[0035] The first raw water inlet is arranged at one end of one of the long sides close to the central tube; the first waste water outlet is arranged at another end of the long side away from the central tube;

[0036] A raw water flow channel connected to the first raw water inlet and the first waste water outlet is formed inside the membrane bag, and a pure water flow channel connected to the central tube is formed outside the membrane bag;

[0037] A guide net is provided at one end of the pure water flow channel close to the first raw water inlet.

[0038] Optionally, the length of the guide net is 1 / 3-4 / 5 of the length of the pure water flow channel.

[0039] Optionally, a first membrane shell cover and a second membrane shell cover are respectively provided at both ends of the membrane shell;

[0040] The second pure water outlet is arranged on the first membrane shell cover and the second membrane shell cover.

[0041] Optionally, the second raw water inlet is provided on the first membrane shell cover; the second waste water outlet is provided on the second membrane shell cover;

[0042] A first transition channel is formed between the first membrane shell cover and the front end cover of the first end membrane element, and the first transition channel is used to connect the second raw water inlet with the first raw water inlet of the first end membrane element;

[0043] A second transition channel is formed between the front cover and the rear cover of two adjacent membrane elements, and the second transition channel is used to connect the first wastewater outlet of the previous membrane element with the first raw water inlet of the next membrane element;

[0044] A third transition channel is formed between the second membrane shell cover and the rear end cover of the tail end membrane element. The third transition channel is used to connect the second wastewater outlet with the first wastewater outlet of the tail end membrane element.

[0045] Optionally, the central tubes of two adjacent membrane elements are connected via a series connection piece, and the pure water produced by the membrane elements flows out from the second pure water outlets provided on the first membrane shell cover and the second membrane shell cover.

[0046] Optionally, the central tubes of two adjacent membrane elements are connected via a series connector, one of the second pure water outlets provided on the first membrane shell cover and the second membrane shell cover is closed, and the pure water produced by the membrane element flows out from the other second pure water outlet.

[0047] In a second aspect, a water purification device comprises the membrane element series filter element in the first aspect or any one of the technical solutions in the first aspect.

[0048] Compared with the prior art, the technical solution provided by the utility model has the following beneficial effects:

[0049] The filter element of the utility model has multiple membrane elements built in, and the membrane elements are arranged along the length extension direction of the membrane shell. The filter element as a whole is a cylindrical structure with a higher degree of integration. When it is arranged and laid out during use, and when it is packaged during transportation, the overall arrangement is more compact, thereby saving space.

[0050] In addition, in the field of industrial water use, in the case of a large water flow rate, the raw water treated by the pre-membrane element can be re-treated, that is, the "waste water" discharged after treatment by the pre-membrane element can be treated by the post-membrane element, thereby improving the utilization rate of raw water. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a schematic diagram of a cross-sectional view of a filter element in one embodiment of the present application;

[0052] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0053] Figure 3 This is a schematic diagram of an embodiment of the present application in which the first wastewater outlet is arranged on the long side;

[0054] Figure 4 This is a schematic diagram of an embodiment of the present application in which the first wastewater outlet is arranged on the short side;

[0055] Figure 5 This is a schematic diagram of the flow of pure water produced by the membrane element in one embodiment of the present application.

[0056] Explanation of the symbols in the schematic diagram:

[0057] Membrane shell 101, first membrane shell cover 102, second pure water outlet 103, second raw water inlet 104, second membrane shell cover 105, second waste water outlet 106;

[0058] Membrane bag 201, central tube 202, front cover 203, rear cover 204, serial connection piece 205, second transition channel 206, first raw water inlet 207, first transition channel 208, third transition channel 209;

[0059] Guide net 301 , long side 302 , short side 303 . DETAILED DESCRIPTION

[0060] In order to further understand the content of the utility model, the utility model is described in detail in conjunction with the drawings and embodiments.

[0061] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present utility model. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and so on quoted in this specification are only for the convenience of description, and are not used to limit the scope of implementation. The change or adjustment of their relative relationship should also be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0062] In one embodiment, the utility model provides a membrane element series filter element, such as Figure 1 As shown, it includes a membrane shell 101 and a plurality of membrane elements. Preferably, there are no less than two membrane elements, namely, two membrane elements.

[0063] The membrane shell 101 is cylindrical, which means that a roughly cylindrical groove is provided inside the membrane shell 101, and the membrane element is placed in the cylindrical groove. In addition, a second raw water inlet 104 and a second waste water outlet 106 are provided at both ends of the membrane shell 101, that is, a second raw water inlet 104 is provided at one end of the membrane shell 101, and the raw water to be treated enters the membrane shell 101 from the second raw water inlet 104; a second waste water outlet 106 is provided at the other end of the membrane shell 101, and the final waste water treated in the membrane shell 101 is discharged through the second waste water outlet 106.

[0064] The membrane shell 101 is also provided with a second pure water outlet 103. In the present embodiment, the second pure water outlet 104 is also provided at the end of the membrane shell 101, so that the membrane shell 101 is provided with an interface for water inlet and outlet only at the end, and no interface on the side. The side is a smooth surface, so that the membrane shell 101 is easy to arrange and distribute during use, and is also easy to pack during transportation.

[0065] In this embodiment, the membrane element is cylindrical, that is, approximately cylindrical, and is adapted to the cylindrical groove provided in the membrane shell 101, so that the membrane element can be placed in the cylindrical groove provided in the membrane shell 101. Specifically, the outer diameter of the membrane element is smaller than the inner diameter of the membrane shell 101, so that it can be placed in the cylindrical groove provided in the membrane shell 101.

[0066] In this embodiment, the cylindrical groove provided in the membrane shell 101 can accommodate only one membrane element in radial dimension, while the cylindrical groove can accommodate multiple membrane elements in axial dimension. At this time, the multiple membrane elements are arranged in the membrane shell 101 along the length extension direction of the membrane shell 101. At this time, the multiple membrane elements are connected end to end and arranged in a straight line.

[0067] In this embodiment, the membrane element is coaxially arranged with the membrane shell 101, that is, the central axis of the columnar membrane element roughly coincides with the central axis of the cylindrical groove provided in the membrane shell 101, so that the overall center of gravity of the filter element almost falls in the middle of the filter element, so that the filter element will be more stable when placed.

[0068] In this embodiment, in two adjacent membrane elements, the first wastewater outlet of the preceding membrane element is communicated with the first raw water inlet 207 of the succeeding membrane element, and the first raw water inlet 207 of the leading membrane element is communicated with the second raw water inlet 104 provided in the membrane shell 101, and the first wastewater outlet of the trailing membrane element is communicated with the second wastewater outlet 106 provided in the membrane shell 101. After the raw water to be treated enters the membrane shell 101 from the second raw water inlet 104 provided in the membrane shell 101, it is first treated by the leading membrane element, and the first wastewater discharged after being filtered by the leading membrane element is discharged through the first wastewater outlet, and enters the first raw water inlet 207 of the succeeding membrane element, so as to be further treated by the next membrane element, and after being treated by all membrane elements, the final wastewater is discharged from the membrane shell 101 from the second wastewater outlet 106 provided in the membrane shell 101.

[0069] During the treatment process, pure water produced by all membrane elements flows out from the second pure water outlet 103 provided in the membrane housing 101 .

[0070] In this embodiment, after a large flow of raw water is processed by a plurality of membrane elements connected in series, the raw water can be fully utilized to produce pure water, thereby improving the utilization rate of the raw water.

[0071] In one embodiment, the membrane element includes a central tube 202 and a membrane bag 201 wound on the central tube 202. The membrane bag 201 here can be a reverse osmosis membrane, which is relatively mature in the prior art and will not be described in detail here.

[0072] A front cover 203 and a rear cover 204 are respectively installed at both ends of the central tube 202. The front cover 203 and the rear cover 204 are both provided with outlets extending from the ends of the central tube 202. The central tube 202 is used to guide the pure water produced by the membrane element, and the central tube 202 is connected to the second pure water outlet 103. The pure water produced by the membrane element flows out from the second pure water outlet 103 through the central tube 202.

[0073] In this embodiment, the front cover 203 is sealed and connected to one end of the rolled film bag 201, and the first raw water inlet 207 is arranged on the inner circle of the front cover 203, and the rear cover 204 is sealed and connected to the other end of the rolled film bag 201. This is relatively mature in the prior art and will not be described in detail here.

[0074] In one embodiment, if Figure 4 , 5 As shown, the first wastewater outlet is arranged on the side of the membrane element close to the membrane shell 101, that is, the first wastewater outlet is arranged at the arc-shaped side of the columnar membrane element, and accordingly, a wastewater flow channel for wastewater circulation is arranged between the membrane element and the inner wall of the membrane shell 101, and at the same time, in order to prevent the wastewater from flowing back to the front end, a sealing connection is made between the front end cover 203 and the inner wall of the membrane shell 101, and a channel connected to the wastewater flow channel is arranged between the rear end cover 204 and the inner wall of the membrane shell 101. The wastewater discharged from the membrane element first enters the wastewater flow channel, and then flows to the next membrane element from the channel arranged between the rear end cover 204 and the inner wall of the membrane shell 101.

[0075] In this embodiment, the membrane bag 201 is provided with two opposite long sides 302 and two opposite short sides 303, wherein one short side 303 is connected to the central tube 202, and the membrane bag 201 is wound on the central tube 202 along the extension direction of the long side 302, and at this time, the first waste water outlet is provided at the other short side 303. The first raw water inlet 207 is provided at one end of one of the long sides 302 close to the central tube 202.

[0076] After the membrane bag 201 is wound into a cylinder, glue is used to bond the membrane bags 201 of adjacent circles to the side of the membrane bag 201 (the bold black line part in the figure). The inner side of the membrane bag 201 forms a raw water flow channel connected to the first raw water inlet 207 and the first wastewater outlet, and the outer side of the membrane bag 201 forms a pure water flow channel connected to the central tube 202. After the raw water to be treated enters the raw water flow channel from the first raw water inlet 207, the pure water enters the pure water flow channel through the membrane bag 201 and then flows into the central tube 202. The wastewater is discharged from the raw water flow channel from the first wastewater outlet.

[0077] A guide net 301 is provided at one end of the pure water flow channel close to the first raw water inlet 207. The guide net 301 is used to separate the membrane bags on both sides of the flow channel, which is relatively mature in the prior art and will not be described in detail here.

[0078] In one embodiment, if Figure 3 , 5 As shown, the first wastewater outlet is arranged at one end of the membrane element close to the rear end cover 204, and the rear end cover 204 is provided with a channel for the wastewater discharged from the membrane element to flow. At this time, the front end cover 203, the rear end cover 204 and the inner wall of the membrane shell 101 are all sealed and connected.

[0079] The membrane bag 201 is provided with two opposite long sides 302 and two opposite short sides 303, wherein one short side 303 is connected to the central tube 202, and the membrane bag 201 is wound on the central tube 202 along the extension direction of the long side 302. The first raw water inlet 207 is provided at one end of one of the long sides 302 close to the center 202, and the first waste water outlet is provided at one end of the other long side 302 away from the central tube 202.

[0080] After the membrane bag 201 is wound into a cylinder, the side of the membrane bag 201 (the bold black line part in the figure) is glued together with the membrane bags 201 of the adjacent circles. A raw water flow channel connected to the first raw water inlet 207 and the first wastewater outlet is formed on the inner side of the membrane bag 201, and a pure water flow channel connected to the central tube 202 is formed on the outer side of the membrane bag 201. After the raw water to be treated enters the raw water flow channel from the first raw water inlet 207, the pure water enters the pure water flow channel through the membrane bag 201, and then flows into the central tube 202. The wastewater is discharged from the raw water flow channel from the first wastewater outlet.

[0081] In this embodiment, a guide net 301 is provided at one end of the pure water flow channel close to the first raw water inlet 207. The guide net 301 is used to separate the membrane bags on both sides of the flow channel, which is relatively mature in the prior art and will not be described in detail here.

[0082] In one embodiment, the length of the guide net 301 is 1 / 3-4 / 5 of the length of the pure water flow channel, for example, 1 / 3, 1 / 2, 4 / 5, etc. The pure water flow channel without the guide net 301 forms an adaptive zone, and the inner walls of the membrane bag 201 fit together. When the raw water enters the adaptive zone of the raw water flow channel, the partially fitted inner walls of the membrane bag 201 are flushed open by the raw water to form an adaptive flow channel.

[0083] In one embodiment, a first membrane shell cover 102 and a second membrane shell cover 105 are respectively disposed at both ends of the membrane shell 101 , and in this case, the second pure water outlet 103 is disposed on the first membrane shell cover 102 and the second membrane shell cover 105 .

[0084] In one embodiment, if Figure 1 , 2 As shown, the second raw water inlet 104 is arranged on the first membrane shell cover 102 , and the second waste water outlet 106 is arranged on the second membrane shell cover 105 .

[0085] In this embodiment, a first transition channel 208 is formed between the first membrane shell cover 102 and the front end cover 203 of the head end membrane element, and the first transition channel 208 is used to connect the second raw water inlet 104 with the first raw water inlet 207 of the head end membrane element. The raw water entering from the second raw water inlet 104 enters the first raw water inlet 207 through the first transition channel 208. Since the first raw water inlet 207 is arranged in an annular shape, the first transition channel 208 is provided to allow the raw water to enter the first raw water inlet 207 evenly.

[0086] In this embodiment, a second transition channel 206 is formed between the front cover 203 and the rear cover 204 of two adjacent membrane elements, and the second transition channel 206 is used to connect the first wastewater outlet of the previous membrane element with the first raw water inlet 207 of the next membrane element. Through the second transition channel 206, the wastewater produced by the previous membrane element can be uniformly introduced into the first raw water inlet 207 of the next membrane element in an annular shape.

[0087] In this embodiment, a third transition channel 209 is formed between the second membrane shell cover 105 and the rear end cover 204 of the tail membrane element, and the third transition channel 209 is used to connect the second wastewater outlet 106 with the first wastewater outlet of the tail membrane element. Wastewater flowing out of the first wastewater outlet of the tail membrane element flows out of the second wastewater outlet 106 of the membrane shell 101 through the third transition channel 209.

[0088] In one embodiment, the central tubes 202 of two adjacent membrane elements are connected by a series connector 205. At this time, the pure water produced by each membrane element can be gathered together after entering the central tube 202, and the pure water produced by the membrane element flows out from the second pure water outlets 103 provided in the first membrane shell cover 102 and the second membrane shell cover 105. That is, at this time, the second pure water outlets 103 at both ends of the membrane shell 101 can flow out pure water.

[0089] In one embodiment, the central tubes 202 of two adjacent membrane elements are connected by a series connector 205, and one of the second pure water outlets 103 provided in the first membrane shell cover 102 and the second membrane shell cover 105 is closed, and the pure water produced by the membrane element flows out from the other second pure water outlet 103, that is, at this time, pure water is only discharged from the second pure water outlet 103 at one end of the membrane shell 101.

[0090] The utility model also provides a water purification device, which comprises the above-mentioned membrane element series filter element.

[0091] The above schematically describes the present invention and its implementation methods, which are not restrictive. The drawings show only one implementation method of the present invention, and the actual structure is not limited thereto. Therefore, if ordinary technicians in this field are inspired by it and design structural methods and embodiments similar to the technical solution without creativity without departing from the purpose of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A membrane element series filter element, characterized in that: include: A membrane shell (101), wherein the membrane shell (101) is cylindrical, and a second raw water inlet (104) and a second waste water outlet (106) are respectively provided at two ends of the membrane shell (101), and the membrane shell (101) is also provided with a second pure water outlet (103); A plurality of membrane elements, each of which is cylindrical and has an outer diameter smaller than an inner diameter of the membrane shell (101); the plurality of membrane elements are arranged in the membrane shell (101) along a length extension direction of the membrane shell (101); in: The membrane element and the membrane housing (101) are coaxially arranged; The plurality of membrane elements are connected end to end, and in two adjacent membrane elements, the first wastewater outlet of the preceding membrane element is connected to the first raw water inlet (207) of the succeeding membrane element; The first raw water inlet (207) of the head-end membrane element is in communication with the second raw water inlet (104) provided in the membrane shell (101); The first wastewater outlet of the tail end membrane element is in communication with the second wastewater outlet (106) provided on the membrane housing (101); The pure water produced by the membrane element flows out from a second pure water outlet (103) provided in the membrane housing (101).

2. The membrane element series filter element according to claim 1, characterized in that: The membrane element comprises a central tube (202) and a membrane bag (201) wound on the central tube (202); A front end cover (203) and a rear end cover (204) are respectively installed at both ends of the central tube (202); in: The front end cover (203) and the rear end cover (204) are both provided with an outlet for accommodating the end of the central tube (202) to extend out; The front end cover (203) is sealed and connected to one end of the rolled membrane bag (201), and the first raw water inlet (207) is arranged on the inner circle of the front end cover (203); The rear end cover (204) is sealed and connected to the other end of the rolled film bag (201); The central tube (202) is used to export the pure water produced by the membrane element, and the central tube (202) is connected to the second pure water outlet (103).

3. The membrane element series filter element according to claim 2, characterized in that: The first wastewater outlet is arranged on a side of the membrane element close to the membrane shell (101); A wastewater flow channel for allowing wastewater to flow is provided between the membrane element and the inner wall of the membrane shell (101). The front end cover (203) is sealedly connected to the inner wall of the membrane shell (101), and a channel communicating with the wastewater flow channel is provided between the rear end cover (204) and the inner wall of the membrane shell (101).

4. The membrane element series filter element according to claim 3, characterized in that: The film bag (201) is provided with two opposite long sides (302) and two opposite short sides (303); One short side (303) is connected to the central tube (202), the membrane bag (201) is wound on the central tube (202) along the extension direction of the long side (302), and the first wastewater outlet is arranged at the other short side (303); The first raw water inlet (207) is disposed at one end of one of the long sides (302) close to the central tube (202); A raw water flow channel connected to the first raw water inlet (207) and the first waste water outlet is formed on the inner side of the membrane bag (201), and a pure water flow channel connected to the central tube (202) is formed on the outer side of the membrane bag (201); A flow guide net (301) is provided at one end of the pure water flow channel close to the first raw water inlet (207).

5. The membrane element series filter element according to claim 2, characterized in that: The first wastewater outlet is arranged at one end of the membrane element close to the rear end cover (204); The front end cover (203), the rear end cover (204) and the inner wall of the membrane shell (101) are all sealed and connected.

6. The membrane element series filter element according to claim 5, characterized in that: The film bag (201) is provided with two opposite long sides (302) and two opposite short sides (303); Wherein, a short side (303) is connected to the central tube (202), and the membrane bag (201) is wound on the central tube (202) along the extension direction of the long side (302); The first raw water inlet (207) is arranged at one end of one of the long sides (302) close to the central tube (202); the first waste water outlet is arranged at another end of the long side (302) away from the central tube (202); A raw water flow channel connected to the first raw water inlet (207) and the first waste water outlet is formed on the inner side of the membrane bag (201), and a pure water flow channel connected to the central tube (202) is formed on the outer side of the membrane bag (201); A flow guide net (301) is provided at one end of the pure water flow channel close to the first raw water inlet (207).

7. The membrane element series filter element according to claim 4 or 6, characterized in that: The length of the guide net (301) is 1 / 3-4 / 5 of the length of the pure water flow channel.

8. The membrane element series filter element according to claim 2, characterized in that: The two ends of the membrane shell (101) are respectively provided with a first membrane shell cover (102) and a second membrane shell cover (105); The second pure water outlet (103) is arranged on the first membrane shell cover (102) and the second membrane shell cover (105).

9. The membrane element series filter element according to claim 8, characterized in that: The second raw water inlet (104) is provided on the first membrane shell cover (102); the second waste water outlet (106) is provided on the second membrane shell cover (105); A first transition channel (208) is formed between the first membrane shell cover (102) and the front end cover (203) of the first end membrane element, and the first transition channel (208) is used to connect the second raw water inlet (104) and the first raw water inlet (207) of the first end membrane element; A second transition channel (206) is formed between the front end cover (203) and the rear end cover (204) of two adjacent membrane elements, and the second transition channel (206) is used to connect the first wastewater outlet of the previous membrane element with the first raw water inlet (207) of the next membrane element; A third transition channel (209) is formed between the second membrane shell cover (105) and the rear end cover (204) of the tail end membrane element. The third transition channel (209) is used to connect the second wastewater outlet (106) and the first wastewater outlet of the tail end membrane element.

10. The membrane element series filter element according to claim 8, characterized in that: The central tubes (202) of two adjacent membrane elements are connected via a series connection piece (205), and the pure water produced by the membrane elements flows out from the second pure water outlets (103) provided on the first membrane shell cover (102) and the second membrane shell cover (105).

11. The membrane element series filter element according to claim 8, characterized in that: The central tubes (202) of two adjacent membrane elements are connected via a series connector (205), one of the second pure water outlets (103) provided on the first membrane shell cover (102) and the second membrane shell cover (105) is closed, and the pure water produced by the membrane element flows out from the other second pure water outlet (103).

12. A water purification device, characterized in that: It comprises a membrane element series filter element as described in any one of claims 1 to 11.

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