Concentrated water separation net for spiral-wound membrane element and spiral-wound membrane element

Abstract

The invention provides a spiral-wound membrane element with a concentrated water separation net, and the concentrated water separation net comprises a plurality of longitudinal ribs (1), the longitudinal ribs (1) are hollow columnar, the peripheral walls of the longitudinal ribs (1) are hollow, and the plurality of longitudinal ribs (1) are arranged in parallel and extend along the axial direction of the spiral-wound membrane element; the transverse ribs (2) are in a hollow column shape, the peripheral wall of each transverse rib (2) is hollowed out, the two ends of each transverse rib (2) are connected to the adjacent longitudinal ribs (1), and the longitudinal ribs (1) and the transverse ribs (2) form a net-shaped structure; the longitudinal ribs (1) and the transverse ribs (2) are wrapped by the film, and the longitudinal ribs (1) and the transverse ribs (2) support the film.

Description

Technical Field

[0001] The present application belongs to the field of water purification, and in particular relates to a concentrated water separator for a rolled membrane element and a rolled membrane element. Background Art

[0002] Rolled membrane elements are one of the most widely used membrane application forms at present. They occupy most of the market share due to their high packing density, easy installation and operation, compact structure, large effective membrane area per unit volume and low price.

[0003] At present, the rolled membrane element is made by rolling a flat membrane. The rolled membrane element includes a central water production pipe, an end cover, an adhesive, and at least one group of separation membranes, pure water screens, and concentrate water screens wrapped around the central water production pipe. Among them, the structure of the concentrate water screen has a significant impact on the state of the fluid in the rolled membrane element. In the rolled membrane element, the concentrate water screen not only supports the flow channel and guides the liquid, but also acts as a turbulence promoter, which can effectively enhance turbulence while reducing the concentration polarization phenomenon on the membrane surface. However, while the concentrate water screen improves the mass transfer efficiency, it also increases the flow resistance of the fluid and the pressure loss, thereby increasing energy consumption, and also brings about problems such as local channeling and dead zones.

[0004] A concentrate screen in the prior art includes a diamond-shaped grid composed of transverse and longitudinal mesh wires. Pollutants are easily accumulated at the intersection of the mesh wires, which leads to serious biological contamination, resulting in loss of feed side pressure and transmembrane pressure difference, reducing the flux of the membrane element, and in severe cases, irreversible contamination damage may occur.

[0005] Utility model patent CN202725044U discloses a wide flow channel guide net, which includes a plurality of longitudinal ribs arranged in parallel, adjacent longitudinal ribs are connected by a plurality of transverse ribs, and a longitudinal flow channel is formed between adjacent longitudinal ribs, and the cross section of the longitudinal ribs is a triangle or an isosceles trapezoid. The transverse ribs are connected to the middle of the triangle or isosceles trapezoid and do not contact the membrane, so as to increase the effective utilization area of ​​the membrane and make the water flow turbulent.

[0006] However, the contact position between the longitudinal ribs with a triangular cross section and the membrane surface is sharp, which can easily cause serious wear to the membrane due to friction during operation. The contact between the longitudinal ribs with an isosceles trapezoidal cross section and the membrane is surface contact, and the contact area is larger, which can easily cause the accumulation of suspended matter and colloids near the contact surface.

[0007] CN106039999A discloses a one-way grid device for a reverse osmosis membrane element and a preparation method thereof, wherein a dividing line is provided along the direction of water flow, the dividing line replaces the traditional grid structure, and water can flow rapidly between the two dividing lines.

[0008] However, although this type of separator reduces the flow resistance, it also lacks the disturbance effect of the transverse ribs. Under the same flow conditions, the turbulence effect of the fluid is poor, which can easily cause concentration polarization on the membrane surface, and accelerate membrane pollution.

[0009] CN113041841A discloses a method for preparing and using an anti-pollution concentrated water screen, wherein the concentrated water screen is immersed in a mixed solution and treated to obtain the anti-pollution concentrated water screen. The selected polynitrogen heterocyclic polycarboxylic acid structure has reactive amino groups and carboxyl groups, which can be fixed on the surface of the concentrated water screen by a cross-linking agent to introduce hydrophilic anti-pollution carboxyl groups, and the unique three-dimensional cage structure of the polynitrogen heterocyclic polycarboxylic acid itself forms a stable hydration layer on the surface of the concentrated water screen, thereby improving the anti-pollution property of the concentrated water screen.

[0010] However, the disclosed method can only inhibit the adsorption of hydrophobic pollutants, and has poor anti-pollution performance for biological pollutants such as bacteria. Summary of the invention

[0011] The present application aims to provide a concentrate separator for a rolled membrane element and a rolled membrane element, so as to solve or alleviate at least one disadvantage in the prior art.

[0012] The embodiment of the present application provides a concentrated water screen for a spiral membrane element, comprising:

[0013] A longitudinal rib, wherein the longitudinal rib is in a hollow columnar shape, the peripheral wall of the longitudinal rib is hollow, a plurality of the longitudinal ribs are provided, and the plurality of longitudinal ribs are arranged in parallel and extend along the axial direction of the rolled membrane element;

[0014] Transverse ribs, wherein the transverse ribs are hollow columnar, the peripheral wall of the transverse ribs is hollow, the two ends of the transverse ribs are connected to the adjacent longitudinal ribs, and the longitudinal ribs and the transverse ribs form a mesh structure; and

[0015] A membrane covers the longitudinal ribs and the transverse ribs, and the longitudinal ribs and the transverse ribs support the membrane.

[0016] In at least one possible embodiment, the diameter of the transverse rib is smaller than the diameter of the longitudinal rib, the membrane contacts the longitudinal rib, the membrane does not contact the transverse rib, and the contact surface between the membrane and the same longitudinal rib is disconnected and discontinuous.

[0017] In at least one possible implementation manner, the longitudinal ribs and / or the transverse ribs are in a spiral shape formed by winding mesh wire.

[0018] In at least one possible embodiment, the spiral directions of the mesh wires of adjacent longitudinal ribs are opposite.

[0019] In at least one possible implementation manner, the number of threads of the mesh wires of the transverse ribs is greater than or equal to the number of threads of the mesh wires of the longitudinal ribs.

[0020] In at least one possible implementation manner, the transverse ribs are bent to form a V-shape, and the tip of the V-shape points to the downstream direction of the concentrated water separator.

[0021] In at least one possible implementation, the plurality of transverse ribs located on opposite sides of the same longitudinal rib are located at different axial positions on the longitudinal rib.

[0022] In at least one possible embodiment, on at least one side of the concentrated water separator in the thickness direction, the outer peripheral surface of the longitudinal ribs includes a flat portion, and the flat portion enables the membrane and the longitudinal ribs to form a surface contact.

[0023] In at least one possible implementation, the longitudinal ribs and the transverse ribs are both made of elastomer.

[0024] The embodiment of the present application further proposes a rolled membrane element, which includes a concentrated water separator as described in any one of the above technical solutions.

[0025] By adopting the above technical solution, the concentrated water screen and the rolled membrane element of the present application can obtain at least one of the following beneficial effects.

[0026] (1) The hollow longitudinal ribs reduce the flow resistance, enhance the flushing force of the feed fluid, and prevent pollutants from depositing on the membrane surface, making the spiral membrane element have a higher permeability flux and better anti-pollution performance.

[0027] (2) The contact area between the membrane and the longitudinal ribs is small and the contact surface is disconnected, so there are fewer "dead zones" where pollutants may accumulate, preventing pollutants from being deposited on the membrane surface, making the permeation flux of the spiral membrane element higher and the anti-pollution performance better. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic structural diagram of a concentrated water separator according to an embodiment of the present application is shown.

[0029] Figure 2 A front view of a concentrate screen according to an embodiment of the present application is shown.

[0030] Figure 3 A partial front view of a concentrate separator according to an embodiment of the present application is shown.

[0031] Figure 4 A top view of a concentrate separator according to an embodiment of the present application is shown.

[0032] Figure 5A schematic structural diagram of a concentrated water separator according to another embodiment of the present application is shown. DETAILED DESCRIPTION

[0033] In order to more clearly explain the above-mentioned purposes, features and advantages of the present application, the specific implementation methods of the present application are described in detail in this section in conjunction with the accompanying drawings. In addition to the various implementation methods described in this section, the present application can also be implemented in other different ways. Without violating the spirit of the present application, those skilled in the art can make corresponding improvements, deformations and substitutions, so the present application is not limited by the specific embodiments disclosed in this section. The scope of protection of the present application shall be subject to the claims.

[0034] like Figures 1 to 4 As shown, an embodiment of the present application proposes a rolled membrane element, which includes a central tube, a concentrated water separator and a pure water separator, and the concentrated water separator and the pure water separator are wound together on the central tube.

[0035] The concentrated water separator includes longitudinal ribs 1, transverse ribs 2 and membranes. The transverse ribs 2 and longitudinal ribs 1 are perpendicular as a whole. Of course, this does not mean that the transverse ribs 2 are limited to be straight. Multiple longitudinal ribs 1 and transverse ribs 2 can be provided. Multiple longitudinal ribs 1 are parallel to each other and extend along the axial direction of the rolled membrane element (i.e., the direction in which the fluid passes through the concentrated water separator). The two ends of the transverse ribs 2 can be connected between two adjacent longitudinal ribs 1 to form a mesh structure. The membrane can cover the longitudinal ribs 1 and the transverse ribs 2, and the longitudinal ribs 1 and the transverse ribs 2 can support the membrane. In order to show the longitudinal ribs 1 and the transverse ribs 2, Figures 1 to 4 Neither membrane is shown.

[0036] Figure 1 and Figure 2 The one-way arrow in the figure indicates the direction in which the fluid passes through the concentrate screen.

[0037] The longitudinal ribs 1 may be hollow columns, and the peripheral wall of the longitudinal ribs 1 may be hollow. For example, the longitudinal ribs 1 may be hollow columns formed by spirally winding mesh wires. The spiral directions of the mesh wires of the plurality of longitudinal ribs 1 of the concentrated water separator may be the same or opposite, such as Figure 2 As shown, the spiral directions of the mesh wires of adjacent longitudinal ribs 1 can be opposite, which can increase the disturbance degree of the incoming liquid turbulence, thereby increasing the flushing force and avoiding the accumulation of pollutants (for example, suspended solids and colloids in the fluid).

[0038] In other possible implementations, the longitudinal ribs 1 may include a plurality of annular meshes and a plurality of linear meshes, the linear meshes are connected to the annular meshes, and the plurality of annular meshes are arranged parallel to each other and spaced apart, so as to form a hollow column with a hollow peripheral wall.

[0039] The cross section of the mesh of the longitudinal rib 1 can be circular. The spiral mesh can make the contact area between the membrane and the longitudinal rib 1 smaller and the contact surface is disconnected and discontinuous. The contact between the membrane and the same longitudinal rib 1 can be understood as multiple discontinuous point contacts, so there are fewer "dead zones" where pollutants may accumulate. The mesh with a circular cross section causes less wear on the membrane, which makes the rolled membrane element have a longer service life. The fluid can pass through the longitudinal rib 1 of the hollow structure along the axial direction of the rolled membrane element. The hollow longitudinal rib 1 increases the porosity of the feed channel and has less resistance to the fluid, which helps to reduce the net driving pressure and pressure drop and reduce energy consumption. The fluid generates high shear force on the membrane surface, which prevents pollutants from being deposited on the membrane surface, so that the permeation flux of the rolled membrane element is higher and the anti-pollution performance is better.

[0040] The transverse rib 2 may be in the shape of a hollow column, and the peripheral wall of the transverse rib 2 may be hollowed out. For example, the transverse rib 2 may be in the shape of a hollow column formed by spirally winding a mesh wire. The two ends of the transverse rib 2 may be respectively connected to the adjacent longitudinal ribs 1. A plurality of transverse ribs 2 may be provided, and the plurality of transverse ribs 2 may be arranged at intervals, so that the longitudinal ribs 1 and the transverse ribs 2 form a mesh structure with good support.

[0041] The diameter of the transverse rib 2 can be smaller than the diameter of the longitudinal rib 1, and the transverse rib 2 can be located in the middle of the longitudinal rib 1 in the thickness direction of the concentrated water separator, so the longitudinal rib 1 contacts the membrane, and the transverse rib 2 does not contact the membrane. It can be understood that the transverse rib 2 is not in contact with the membrane. It is not absolute. Since the membrane is soft, if the membrane is loose when installed or becomes loose after use, the transverse rib 2 may also contact the membrane, but this contact is accidental and the contact area is small. The membrane is mainly in contact with the longitudinal rib 1 and supported by the longitudinal rib 1. The longitudinal rib 1 and the transverse rib 2 do not cross, and the connection between the longitudinal rib 1 and the transverse rib 2 will not contact the membrane. The fluid can flush the connection from multiple directions, so pollutants are not easy to accumulate. For example, the diameter E of the transverse rib 2 can be 0.3-0.6 mm, and the diameter F of the longitudinal rib 1 can be 0.7-1.5 mm, and the diameter E of the transverse rib 2 is at least greater than twice the diameter D2 of the mesh of the transverse rib 2, and the diameter F of the longitudinal rib 1 is at least greater than twice the diameter D1 of the mesh of the longitudinal rib 1.

[0042] Optionally, the mesh diameter D1 of the longitudinal ribs 1 is greater than the mesh diameter D2 of the transverse ribs 2. For example, the mesh diameter D1 of the longitudinal ribs 1 may be 0.2-0.4 mm, and the mesh diameter D2 of the transverse ribs 2 may be 0.05-0.2 mm.

[0043] When the fluid contacts the transverse ribs 2, the fluid can fully flush multiple surfaces of the mesh of the transverse ribs 2 (for example, the front and back surfaces of the transverse ribs 2 in the thickness direction of the concentrated water separator). The mesh spiral of the transverse ribs 2 has at least three spirals, and the pitch B can be 0.2-0.6 mm. The mesh spiral of the transverse ribs 2 can cause disturbances, forming a recirculation zone around the transverse ribs 2, so that the feed shear strength of the fluid is greater and the accumulation of pollutants is avoided.

[0044] Optionally, the pitch of the longitudinal ribs 1 may be greater than the pitch of the transverse ribs 2. For example, the pitch H of the longitudinal ribs 1 may be 0.6-1.5 mm, and the pitch B of the transverse ribs 2 may be 0.2-0.6 mm. The center distance A between two adjacent longitudinal ribs 1 may be 2-10 mm, and the center distance C between two adjacent transverse ribs 2 may be 1.8-9 mm.

[0045] Optionally, the transverse rib 2 may be a V-shape formed by bending a spiral structure, with the tip of the V-shape pointing to the downstream direction of the fluid, which is conducive to the formation of turbulence in the fluid. The angle α of the V-shape may be, for example, 120 degrees.

[0046] like Figure 2 As shown, each transverse rib 2 located in the opposite direction of the longitudinal rib 1 is located at a different axial position on the longitudinal rib 1, so that each transverse rib 2 is staggered in the axial direction of the longitudinal rib 1 to reduce the accumulation of pollutants.

[0047] The number of threads of the mesh of the transverse ribs 2 may be greater than or equal to the number of threads of the mesh of the longitudinal ribs 1 , for example, the ratio of the number of threads of the mesh of the transverse ribs 2 to the number of threads of the mesh of the longitudinal ribs 1 may be 5:1 to 1:1.

[0048] The longitudinal ribs 1 and the transverse ribs 2 can be made of elastomers, for example, the elastomers can be polymer elastomers, and the polymer elastomers include thermoplastic elastomers (TPE), triblock copolymers (SBS) with styrene and butadiene as monomers, POE plastics, and thermoplastic polyurethane (TPU), etc. The longitudinal ribs 1 made of elastomer can make the longitudinal ribs 1 contact the membrane flexibly, and it is not easy to form indentations on the membrane surface, and the surface of the desalination layer is less damaged, so that the performance of the rolled membrane element is not affected.

[0049] like Figure 5 As shown, in at least one possible embodiment, on at least one side in the thickness direction of the concentrated water separator, the outer peripheral surface of the longitudinal rib 1 may include a flat portion, for example, the flat portion may be formed by cutting or grinding a mesh wire with a circular cross section. The flat portion enables the membrane and the longitudinal rib 1 to form a surface contact, and the flat portion increases the contact area between the membrane and the longitudinal rib 1, thereby reducing the indentation of the mesh wire of the longitudinal rib 1 on the membrane, so that the membrane concentrated water separator has better pressure resistance and support.

[0050] The concentrated water separator and rolled membrane element of the present application have the following beneficial effects.

[0051] (1) The hollow longitudinal ribs 1 reduce the flow resistance, enhance the flushing force of the feed fluid, and prevent pollutants from being deposited on the membrane surface, so that the permeation flux of the spiral membrane element is higher and the anti-pollution performance is better.

[0052] (2) The contact area between the membrane and the longitudinal ribs 1 is small and the contact surface is disconnected, so there are fewer "dead zones" where pollutants may accumulate, which prevents pollutants from being deposited on the membrane surface, making the permeation flux of the spiral membrane element higher and the anti-pollution performance better.

[0053] (3) The circular cross-section of the longitudinal ribs causes less wear on the membrane, which prolongs the service life of the rolled membrane element.

[0054] It should be understood that at least some aspects or features of the above-mentioned implementation modes, embodiments or examples may be appropriately combined.

[0055] It is understood that in the present application, when the number of parts or components is not particularly limited, the number may be one or more, and the multiple here means two or more. For the case where the number of parts or components shown in the drawings and / or described in the specification is a specific number such as two, three, four, etc., the specific number is usually exemplary and not restrictive, and it can be understood as multiple, that is, two or more, but this does not mean that the present application excludes the case of one.

[0056] In the present application, unless otherwise clearly stated or limited, the terms such as "install", "assemble", "assemble", "connect", "connect", "couple", "link", "abut", "connect", "interconnect", "intercommunication", "conduction", "fixation", "fastening" and the like should be understood in a broad sense, for example, they can be direct or indirect. For example, regarding connection, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly stated or limited. For example, regarding connectivity / conduction, it can be direct connectivity / conduction, or it can be indirect connectivity / conduction via an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0057] In the present application, unless otherwise clearly stated or limited, a component disposed on / installed on / located on / accommodated on / placed in, within, inside, etc. another component may be any of the following two situations: a part or most of the one component is located in the other component; and the one component is completely accommodated in the other component.

[0058] Although the present application is described in detail using the above-mentioned embodiments, it is obvious to those skilled in the art that the present application is not limited to the embodiments described in this specification. The present application can be modified and implemented as a modified embodiment without departing from the subject matter and scope of the present application as determined by the claims. Therefore, the description in this specification is for the purpose of illustration and does not have any restrictive meaning for the present application.

Claims

1. A concentrated water screen for a wound membrane element, characterized in that: include: A longitudinal rib (1), wherein the longitudinal rib (1) is in the shape of a hollow column, the peripheral wall of the longitudinal rib (1) is hollow, a plurality of the longitudinal ribs (1) are provided, and the plurality of longitudinal ribs (1) are arranged in parallel and extend along the axial direction of the rolled membrane element; transverse ribs (2), the transverse ribs (2) are hollow columnar, the peripheral wall of the transverse ribs (2) is hollow, the two ends of the transverse ribs (2) are connected to the adjacent longitudinal ribs (1), and the longitudinal ribs (1) and the transverse ribs (2) form a mesh structure; as well as A membrane, wherein the membrane covers the longitudinal ribs (1) and the transverse ribs (2), and the longitudinal ribs (1) and the transverse ribs (2) support the membrane.

2. The concentrated water screen according to claim 1, characterized in that: The diameter of the transverse rib (2) is smaller than the diameter of the longitudinal rib (1), the membrane contacts the longitudinal rib (1), the membrane does not contact the transverse rib (2), and the contact surface between the membrane and the same longitudinal rib (1) is disconnected and discontinuous.

3. The concentrated water screen according to claim 1, characterized in that: The longitudinal ribs (1) and / or the transverse ribs (2) are spirally wound from mesh wire.

4. The concentrated water screen according to claim 3, characterized in that: The spiral directions of the mesh wires of adjacent longitudinal ribs (1) are opposite.

5. The concentrated water screen according to claim 3, characterized in that: The number of threads of the mesh wire of the transverse rib (2) is greater than or equal to the number of threads of the mesh wire of the longitudinal rib (1).

6. The concentrated water screen according to claim 1, characterized in that: The transverse ribs (2) are bent to form a V-shape, with the tip of the V-shape pointing to the downstream direction of the concentrated water separator.

7. The concentrated water screen according to claim 1, characterized in that: The plurality of transverse ribs (2) located on the opposite sides of the same longitudinal rib (1) are located at different axial positions on the longitudinal rib (1).

8. The concentrated water screen according to claim 1, characterized in that: On at least one side in the thickness direction of the concentrated water separator, the outer peripheral surface of the longitudinal rib (1) includes a flat surface portion, and the flat surface portion enables the membrane and the longitudinal rib (1) to form a surface contact.

9. The concentrated water screen according to claim 1, characterized in that: The longitudinal ribs (1) and the transverse ribs (2) are both made of elastomer.

10. A wound membrane element, characterized in that: It comprises the concentrated water separator according to any one of claims 1 to 9.

Images