Water inlet separation net for spiral-wound membrane element and spiral-wound membrane element

Abstract

The water inlet separation net comprises a plurality of transverse net wires (1), a plurality of longitudinal net wires (2) and a supporting part (3), the transverse net wires (1) and the longitudinal net wires (2) are arranged in a staggered mode to form cells, the water inlet separation net comprises a plurality of cells arranged in a matrix mode, and the supporting part (3) is arranged between the transverse net wires (1) and the longitudinal net wires (2). The supporting part (3) is arranged at the crossed position of the transverse net wires (1) and the longitudinal net wires (2), the transverse net wires (1) and the longitudinal net wires (2) are connected to the supporting part (3), the height of the supporting part (3) is larger than the thickness of the transverse net wires (1) and the thickness of the longitudinal net wires (2) of the cells, and the supporting part (3) is used for being in contact with a membrane of a spiral-wound membrane element. In the thickness direction of the water inlet partition net, the transverse net wires (1) and the longitudinal net wires (2) are located on different planes.

Description

Technical Field

[0001] The present application belongs to the field of membrane separation technology, and in particular relates to a water inlet spacer for a rolled membrane element and a rolled membrane element. Background Art

[0002] High-pressure membrane separation technology (such as nanofiltration and reverse osmosis) plays a key role in seawater and brackish water desalination, industrial wastewater treatment, high-quality reuse of urban sewage and other scenarios. The membrane element type of high-pressure membrane separation technology can be a rolled membrane element, which includes a diaphragm, an inlet screen, a production screen, a central production pipe, etc. Among them, the inlet screen is generally made of a polymer (such as polypropylene), and the inlet screen is a diamond grid with periodic repetition formed by interweaving double-layer mesh wire. The inlet screen is an important component that separates adjacent diaphragms, and plays the role of supporting the diaphragm, creating flow channels, and enhancing mass transfer.

[0003] However, the water inlet screen in the prior art has two defects:

[0004] (1) There are local dead zones, which aggravate membrane fouling. For example, dead zones are easily formed at the nodes where the mesh wires cross, causing pollutants to accumulate easily. Microorganisms are easy to attach and reproduce in the dead zones, further blocking the flow channel, resulting in a decrease in flow field uniformity and an increase in membrane fouling rate.

[0005] (2) Due to the obstruction of the water flow caused by the configuration of the spacer, the flow channel pressure drop difference (pressure loss from the water inlet side to the concentrated water side of the flow channel) is large, and the system energy consumption is high. The flow channel pressure drop difference of the water inlet spacer in the prior art is generally 150 to 400 Pa / cm (when the inlet flow rate is 0.12 m / s). Especially after the diaphragm is contaminated, the flow resistance is higher, and the flow channel pressure drop difference can reach more than 4 times that before contamination, resulting in higher energy consumption. In long-term operation, excessively high flow channel pressure drop difference will damage the membrane element and cause seepage. The above two defects seriously affect the working efficiency of the membrane element and reduce the service life of the membrane element. Summary of the invention

[0006] The present application aims to provide a water inlet spacer for a rolled membrane element and a rolled membrane element, so as to solve or alleviate at least one problem existing in the background technology.

[0007] The embodiment of the present application proposes a water inlet spacer for a rolled membrane element, comprising a plurality of transverse mesh wires, a plurality of longitudinal mesh wires and a support portion, wherein the transverse mesh wires and the longitudinal mesh wires are arranged in an interlaced manner to form a unit cell, the water inlet spacer comprises a plurality of units arranged in a matrix, the support portion is arranged at the intersection of the transverse mesh wires and the longitudinal mesh wires, the transverse mesh wires and the longitudinal mesh wires are both connected to the support portion, the height of the support portion is greater than the thickness of the transverse mesh wires and the longitudinal mesh wires of the unit cell, and the support portion is used to contact the membrane sheet of the rolled membrane element,

[0008] In the thickness direction of the water inlet spacer, the transverse mesh wires and the longitudinal mesh wires are in different planes.

[0009] In at least one possible implementation, the cross-sectional shape of the support portion is a triangle, a quadrilateral, a pentagon, a hexagon, a circle, an ellipse, or an irregular shape.

[0010] In at least one possible implementation manner, the support portion is prism-shaped, and a cross-sectional shape of the support portion is rhombus-shaped.

[0011] In at least one possible implementation, a ratio of a diameter of a circumscribed circle of the support portion to a height of the support portion is less than or equal to 0.8 and greater than or equal to 0.5.

[0012] In at least one possible embodiment, the cross-sectional shape of the transverse mesh wire and / or the longitudinal mesh wire is circular, elliptical, triangular, quadrilateral, pentagonal, hexagonal or irregular.

[0013] In at least one possible implementation, the cross-section of the transverse mesh wire and / or the longitudinal mesh wire is in a rhombus shape.

[0014] In at least one possible embodiment, in the thickness direction of the water inlet spacer, a pair of edges of the rhombus are located in the middle of the transverse mesh wires or the longitudinal mesh wires.

[0015] In at least one possible embodiment, the cross-sectional shape and size of the transverse mesh wires are the same as those of the longitudinal mesh wires.

[0016] The circumscribed circle diameter of the transverse mesh wire or the longitudinal mesh wire / the circumscribed circle diameter of the support portion is less than or equal to 0.7 and greater than or equal to 0.5.

[0017] In at least one possible implementation, for each of the cells, the lengths of the transverse mesh wires and the longitudinal mesh wires are both 1 mm to 4 mm.

[0018] The embodiment of the present application further proposes a rolled membrane element, wherein the rolled membrane element comprises a water inlet spacer as described in any one of the above technical solutions.

[0019] By adopting the above technical solution, the height of the support part is greater than the thickness of the transverse mesh and the longitudinal mesh of the unit cell, so that the membrane surface can be supported by the support part, so that the transverse mesh and the longitudinal mesh do not contact the membrane surface, thereby reducing the resistance to water flow, reducing the pressure drop difference in the flow channel, and extending the service life of the membrane element. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic structural diagram of a water inlet screen of a rolled membrane element according to an embodiment of the present application is shown.

[0021] Figure 2 A schematic structural diagram of a cell of a water inlet screen of a rolled membrane element according to an embodiment of the present application is shown.

[0022] Figure 3 A comparison chart of the pressure drop difference per unit length of the flow channel of the water inlet screen according to the embodiment of the present application and the water inlet screen of the comparative example is shown.

[0023] Figure 4 A comparison chart showing the attenuation of membrane flux over time in a membrane fouling test of a water inlet screen according to an embodiment of the present application and a water inlet screen of a comparative example.

[0024] Description of Reference Numerals

[0025] 100 Water inlet screen

[0026] 1 Horizontal mesh

[0027] 2 Vertical mesh

[0028] 3 Support DETAILED DESCRIPTION

[0029] 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.

[0030] like Figures 1 to 4 As shown, the embodiment of the present application proposes a rolled membrane element, which includes a water inlet spacer 100 and a membrane. The water inlet spacer can be rolled into a cylindrical shape, and the membrane can be rolled on the water inlet spacer.

[0031] The water inlet screen 100 includes a transverse mesh 1, a longitudinal mesh 2 and a support portion 3. The transverse mesh 1 and the longitudinal mesh 2 are arranged in an interlaced manner to form, for example, a rhombus-shaped unit cell, and the support portion 3 can be arranged at the intersection of the transverse mesh 1 and the longitudinal mesh 2. The water inlet screen includes a plurality of units arranged in a matrix. The transverse mesh 1 and the longitudinal mesh 2 can both be connected to the support portion 3, so that the transverse mesh 1 and the longitudinal mesh 2 are fixed by the support portion 3.

[0032] The transverse mesh wires 1 and the longitudinal mesh wires 2 are staggered up and down in the thickness direction of the membrane element. That is to say, in the thickness direction of the water inlet spacer, the transverse mesh wires 1 and the longitudinal mesh wires 2 are in different planes. The rolled membrane element formed in this way can promote turbulence, reduce flow dead zones, increase the shear force on the membrane surface, and enhance anti-pollution ability.

[0033] Optionally, in the same unit cell, the transverse mesh wire 1 may be located radially outside the rolled membrane element of the longitudinal mesh wire 2 .

[0034] The height h of the support part 3 can be greater than the thickness of the transverse mesh 1 and the longitudinal mesh 2 of the cell, that is, both ends of the support part 3 protrude from the surface of the cell, so that the support part 3 can contact the upper and lower membrane surfaces of the diaphragm, and the support part 3 plays a supporting role.

[0035] Reference Figure 2 , the transverse mesh 1 can be located on the upper side of the longitudinal mesh 2. Through the support of the support part 3, the transverse mesh 1 can be close to the upper membrane surface but not in contact with the upper membrane surface. The longitudinal mesh 2 can be close to the lower membrane surface but not in contact with the lower membrane surface. The upper membrane surface and the lower membrane surface are supported and separated by the support part 3, thereby forming a flow channel between the upper membrane surface and the lower membrane surface.

[0036] In the same unit cell, the angle between the transverse mesh wire 1 and the longitudinal mesh wire 2 is 90 degrees to 150 degrees. The diagonal line of the unit cell can extend along the axial direction of the rolled membrane element.

[0037] The lateral mesh wires 1 of adjacent cells may be separated and discontinuous by the support portion 3 , and the longitudinal mesh wires 2 of adjacent cells may be separated and discontinuous by the support portion 3 .

[0038] The support portion 3 may be columnar. The cross-sectional shape of the support portion 3 may be triangular, quadrilateral, pentagonal, hexagonal, circular, elliptical or irregular. Optionally, the support portion 3 is prism-shaped, and the cross-sectional shape of the support portion 3 may be rhombus-shaped. In the thickness direction of the water inlet screen, a pair of edges of the rhombus are located in the middle of the transverse mesh 1 or the longitudinal mesh 2, so that the water flow has less resistance when passing through the edges of the transverse mesh 1 or the longitudinal mesh 2. The diagonal of the cross section of the support portion 3 may extend along the axial direction of the rolled membrane element.

[0039] Further, the support portion 3 may be prism-shaped, and the height h of the prism may be 26 mils to 34 mils. Optionally, the height h of the prism may be 26 mils, 28 mils, 31 mils, 34 mils, etc.

[0040] For each cell, the length of the transverse mesh wires 1 and the longitudinal mesh wires 2 of the water inlet screen can be 1 mm to 4 mm. The cell size formed by the transverse mesh wires 1 and the longitudinal mesh wires 2 of such sizes is moderate, and the anti-pollution effect is better.

[0041] Furthermore, the diameter d1 of the circumscribed circle of the support portion 3 and the height h of the support portion 3 satisfy the following relationship: 0.5≤d1 / h≤0.8.

[0042] The cross-sectional shape and size of the transverse mesh 1 and the longitudinal mesh 2 may be the same. The circumscribed circle diameter d2 of the transverse mesh 1 or the longitudinal mesh 2 and the circumscribed circle diameter d1 of the support 3 satisfy the following relationship: 0.5≤d2 / d1≤0.7.

[0043] Below, taking the water inlet spacer of the rolled membrane element of the embodiment of this implementation as an example, and taking the diamond mesh water inlet spacer with the same height, the same grid unit size but without columnar support parts as a comparative example, hydraulic tests and membrane pollution tests are carried out to test and compare the unit length flow channel pressure drop difference and anti-pollution effect of the present invention and the comparative example.

[0044] First, deionized water was used as the influent solution, and the same commercial reverse osmosis membrane was placed in two parallel membrane pools of the cross-flow filtration device. The embodiment and comparative example of the influent screen of the present application were placed on the two membrane sheets, respectively. The influent flow rate was adjusted to 0.12 m / s, and a hydraulic test was carried out to measure the pressure drop difference of the flow channel, and the pressure drop difference per unit length of the flow channel was calculated by dividing it by the flow channel length. Subsequently, the deionized water was replaced with a mixed solution of 50 mmol per liter of Na2SO4 and 50 mmol per liter of CaCl2, and a membrane fouling (scaling) test was carried out at a constant pressure of 1 MPa, and the filtration time was 300 minutes.

[0045] Reference Figure 3 , the pressure drop difference of the flow channel can be compared in the hydraulic test. The pressure drop difference of the flow channel per unit length of the water inlet screen of the embodiment of the present invention is 140Pa / cm, while the pressure drop difference of the flow channel per unit length of the comparative example is 172Pa / cm. The pressure drop difference of the flow channel per unit length of the water inlet screen of the present application is reduced by 18.6% compared with the comparative example.

[0046] Reference Figure 4 In the membrane fouling (scaling) test, the relative membrane flux decay over time can be compared. Figure 4The dots in the figure represent the relative membrane flux of the examples of the present application, and the squares represent the relative membrane flux of the comparative example. The relative membrane flux refers to the ratio of the membrane flux to the initial membrane flux at a certain time point. In the membrane pollution test, the slower the relative membrane flux decays, the lighter the membrane pollution is, and under the same other conditions, the better the anti-pollution effect of the water inlet screen. The membrane flux decay rate of the water inlet screen example of the present invention is significantly lower than that of the comparative example. When the filtration time reaches 300 minutes, the membrane flux of the example only decays by about 40%, while the membrane flux of the comparative example decays by 67%, indicating that the water inlet screen of the present invention has a better anti-pollution effect.

[0047] The water inlet spacer and rolled membrane element of the present application can achieve the following beneficial effects.

[0048] (1) The support portion 3 supports the membrane surface so that the transverse mesh 1 and the longitudinal mesh 2 do not contact the membrane surface, thereby reducing the resistance to water flow and the pressure drop difference in the flow channel.

[0049] (2) By placing the transverse mesh 1 and the longitudinal mesh 2 in different planes, the flow dead zone can be reduced, the shear force on the membrane surface can be increased, and the anti-pollution ability can be enhanced.

[0050] It should be understood that at least some aspects or features of the above-mentioned implementation modes, embodiments or examples may be appropriately combined.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 water inlet screen for a rolled membrane element, characterized in that: The invention comprises a plurality of transverse meshes (1), a plurality of longitudinal meshes (2) and a support portion (3), wherein the transverse meshes (1) and the longitudinal meshes (2) are arranged in an interlaced manner to form a unit cell, the water inlet spacer comprises a plurality of units arranged in a matrix, the support portion (3) is arranged at the intersection of the transverse meshes (1) and the longitudinal meshes (2), the transverse meshes (1) and the longitudinal meshes (2) are both connected to the support portion (3), the height of the support portion (3) is greater than the thickness of the transverse meshes (1) and the longitudinal meshes (2) of the unit cell, and the support portion (3) is used to contact the membrane sheet of the roll-type membrane element. In the thickness direction of the water inlet screen, the transverse mesh wires (1) and the longitudinal mesh wires (2) are located in different planes.

2. The water inlet screen for a rolled membrane element according to claim 1, characterized in that: The cross-sectional shape of the support portion (3) is a triangle, a quadrilateral, a pentagon, a hexagon, a circle, an ellipse or an irregular shape.

3. The water inlet screen for a rolled membrane element according to claim 1, characterized in that: The support portion (3) is prism-shaped, and the cross-sectional shape of the support portion (3) is rhombus-shaped.

4. The water inlet screen for a rolled membrane element according to claim 3, characterized in that: The ratio of the diameter of the circumscribed circle of the support portion (3) to the height (h) of the support portion (3) is less than or equal to 0.8 and greater than or equal to 0.

5.

5. The water inlet spacer for a rolled membrane element according to claim 1, characterized in that: The cross-sectional shape of the transverse mesh wire (1) and / or the longitudinal mesh wire (2) is circular, elliptical, triangular, quadrilateral, pentagonal, hexagonal or irregular.

6. The water inlet spacer for a rolled membrane element according to claim 3, characterized in that: The cross-sectional shape of the transverse mesh wire (1) and / or the longitudinal mesh wire (2) is a rhombus.

7. The water inlet spacer for a rolled membrane element according to claim 6, characterized in that: In the thickness direction of the water inlet screen, a pair of edges of the rhombus are located in the middle of the transverse mesh wire (1) or the longitudinal mesh wire (2).

8. The water inlet spacer for a rolled membrane element according to claim 6, characterized in that: The cross-sectional shape and size of the transverse mesh wire (1) and the longitudinal mesh wire (2) are the same, The circumscribed circle diameter of the transverse mesh (1) or the longitudinal mesh (2) / the circumscribed circle diameter of the support portion (3) is less than or equal to 0.7 and greater than or equal to 0.

5.

9. The water inlet spacer for a spiral membrane element according to claim 1, characterized in that: For each of the cells, the lengths of the transverse mesh wires (1) and the longitudinal mesh wires (2) are both 1 mm to 4 mm.

10. A wound membrane element, characterized in that: The rolled membrane element comprises the water inlet spacer according to any one of claims 1 to 9.

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