Eddy current capturing separation net for spiral-wound membrane element

Abstract

The invention relates to an eddy current capturing separation net for a spiral-wound membrane element, the separation net comprises first separation net filaments and second separation net filaments, and the first separation net filaments and the second separation net filaments are arranged in an interwoven manner; the cross section of each separation net filament is of a fish-like structure; in the tiled state, the first partition net filaments and the second partition net filaments are located on different planes. The vortex capture separation net can delay boundary layer separation when fluid flows through the separation net filaments, vortex capture and utilization efficiency is improved, mass transfer is enhanced, and meanwhile energy loss caused by vortex dissipation is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation, in particular to an eddy current capturing screen for a rolled membrane element. Background Art

[0002] Membrane separation technology can use the selective permeability of the membrane to achieve solute screening. It is simple to operate, green and efficient, and is widely used in many fields such as water treatment, food processing, and biomedicine. Rolled membrane elements have the advantage of high packing density and are the main structural form of commercial separation membrane elements. Rolled membrane elements are mainly composed of structures such as water inlet screens, water production screens, separation membranes, and central tubes. The water inlet screen not only separates and supports adjacent membranes and provides a water inlet channel, but also can destroy flow stability, generate non-steady-state vortices, and thus enhance mass transfer.

[0003] CN119158415A discloses a water inlet spacer for a roll-type membrane element, comprising a plurality of transverse mesh wires (1), a plurality of longitudinal mesh wires (2) and a support portion (3), wherein the transverse mesh wires (1) and the longitudinal mesh wires (2) are arranged in a staggered manner to form a unit cell, wherein the water inlet spacer comprises a plurality of units arranged in a matrix, wherein the height of the support portion (3) is greater than the thickness of the transverse mesh wires (1) and the longitudinal mesh wires (2) of the unit cell, and the support portion (3) is used to contact the membrane sheet of the roll-type membrane element. By setting the support portion, the transverse mesh wires and the longitudinal mesh wires do not contact the membrane surface, thereby reducing the resistance to water flow.

[0004] CN213253843U discloses an enhanced roll-tube membrane water inlet screen, including a screen body, the screen body having a wavy structure, including wave crests and wave troughs, the wavy structure horizontally extending from one end to the other end, and a flow hole of the same shape and size is provided between the wave crests and the wave trough. The wavy screen can enhance the anti-scouring strength of the screen itself and is not easy to be damaged, and the flow hole can increase the turbulence of sewage in the water inlet screen and reduce the degree of membrane contamination.

[0005] However, the existing water inlet screen has a complex structure, many dead zones in the flow, and a significant attenuation of the mass transfer driving force, which easily leads to concentration differences between the membrane surface solution and the main solution, namely, concentration polarization, which reduces membrane performance. At the same time, the vortex utilization efficiency in the water inlet channel is low, and the structural resistance and vortex dissipation of the screen will significantly increase the pressure drop in the flow channel, resulting in increased production energy consumption and reduced membrane element life. Therefore, there is an urgent need for a new vortex capture screen for rolled membrane elements as a water inlet screen to improve the vortex capture utilization efficiency, improve the flow field distribution and reduce the dead zone in the flow. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a vortex capture screen for a rolled membrane element. In the present invention, the vortex capture screen is structurally designed to improve the vortex capture utilization efficiency, thereby improving the flow field distribution and reducing the flow dead zone, ultimately reducing production energy consumption while enhancing mass transfer and extending the service life of the membrane element.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides an eddy current capture spacer for a rolled membrane element, the spacer comprising first spacer filaments and second spacer filaments, the first spacer filaments and the second spacer filaments being interwoven and arranged; the cross-section of the spacer filaments is a fish-like structure; in a flat state, the first spacer filaments and the second spacer filaments are located in different planes.

[0009] Preferably, in a flattened state, the first spacer mesh filaments and the second spacer mesh filaments are located in different planes, and the planes where the spacer mesh filaments are located are perpendicular to the normal direction of the spacer mesh plane.

[0010] The present invention optimizes the internal channels of membrane elements by designing the structure of the spacer mesh and setting the cross-section of the spacer mesh filaments to a fish-like structure, thereby improving the capture and utilization efficiency of the spacer mesh filaments on the upstream side vortex, inhibiting invalid vortex dissipation, enhancing mass transfer while reducing flow resistance, inhibiting the formation of flow dead zones, and ultimately improving the separation selectivity and anti-pollution performance of the membrane component and reducing production energy consumption.

[0011] As a preferred technical solution of the present invention, the fish-imitation structure includes a head structure and a tail structure; the head structure faces the upstream direction, and the tail structure faces the downstream direction.

[0012] It should be noted that the spacer mesh of the present invention can be used as a water inlet spacer mesh of a rolled membrane element, the upstream side is the water inlet direction, and the downstream side is the water outlet direction. The present invention does not specifically limit the specific material and size of the spacer mesh filaments, and those skilled in the art can make adaptive adjustments according to actual conditions.

[0013] As a preferred technical solution of the present invention, the head structure is a semi-cylindrical structure, and the tail structure is a fishtail-like structure.

[0014] The tail structure provided in the present invention can delay the boundary layer separation generated by the fluid flowing through the spacer filaments, thereby reducing the pressure difference between the upstream side and the downstream side of the spacer filaments and reducing the pressure drop in the flow channel.

[0015] As a preferred technical solution of the present invention, the spacing between the head structure and the tail structure is 0.3mm-0.8mm, for example, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm or 0.8mm, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0016] It should be noted that the distance between the head structure and the tail structure refers to the distance between the farthest point of the head structure and the farthest point of the tail structure ( Figure 1 The distance marked on the cross section 3 of the septum mesh filament).

[0017] As a preferred technical solution of the present invention, the cross-sectional diameter of the head structure is 0.2mm-0.6mm, for example 0.2mm, 0.3mm, 0.4mm, 0.5mm or 0.6mm, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0018] The cross-sectional diameter of the tail structure is 0.1 mm-0.3 mm, such as 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm or 0.3 mm, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0019] As a preferred technical solution of the present invention, the angle of the tail structure is 45°-70°, for example 45°, 50°, 55°, 60°, 65° or 70°, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0020] The angle of the tail structure designed in the present invention can reduce the vortex shedding frequency while ensuring the enhancement of mass transfer, thereby reducing the mechanical energy loss caused by the vortex.

[0021] It should be noted that the angle of the tail structure refers to the angle of the extended connecting line between the head structure and the tail structure.

[0022] As a preferred technical solution of the present invention, the spacing between adjacent first spacer filaments and adjacent second spacer filaments is equal, which is 4 times to 10 times the spacing between the head structure and the tail structure, for example 4 times, 5 times, 6 times, 7 times, 8 times, 9 times or 10 times, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0023] In the present invention, the spacing between adjacent first spacer filaments and adjacent second spacer filaments is equal, which is 4 to 10 times the spacing between the head structure and the tail structure, which can improve the mass transfer effect while reducing the energy consumption caused by the flow channel pressure drop.

[0024] As a preferred technical solution of the present invention, the angle between the spacer filaments and the water inlet direction of the flow channel is 10°-60°, for example, 10°, 20°, 30°, 40°, 50° or 60°, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0025] As a preferred technical solution of the present invention, the first spacer mesh filaments and the second spacer mesh filaments are interwoven to form a quadrilateral grid unit; the four vertices of the grid unit are the interweaving points of the first spacer mesh filaments and the second spacer mesh filaments, which protrude upward or downward respectively, serving as fulcrums to separate and support the membranes on both sides of the spacer mesh.

[0026] In a second aspect, the present invention provides a rolled membrane element, wherein the water inlet spacer of the rolled membrane element is the spacer described in the first aspect.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] The present invention optimizes the internal flow channel of the membrane element through fish-like structure design, improves the capture and utilization efficiency of the upstream side vortex by the spacer filaments, inhibits the invalid vortex dissipation, strengthens the mass transfer while reducing the flow resistance, inhibits the formation of flow dead zones, and ultimately improves the separation selectivity and anti-pollution performance of the membrane component and reduces production energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a plan view of the water inlet screen structure of Example 1 of the present invention, and a cross-sectional view of the water inlet screen filament structure.

[0030] Figure 2 It is a plan view of the water inlet screen structure of Example 2 of the present invention, and a cross-sectional view of the water inlet screen filament structure.

[0031] Figure 3 It is a plan view of the water inlet screen structure of comparative example 1 of the present invention, and a cross-sectional view of the water inlet screen filament structure of comparative example 1.

[0032] Figure 4 1 is a graph showing the test results of the separation factors of the water inlet screens provided in Examples 1-6 of the present invention and Comparative Example 1.

[0033] Figure 5 It is a graph of the flow channel pressure drop test results of the water inlet screens provided in Examples 1-6 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0035] Example 1

[0036] This embodiment provides a vortex capture screen for a rolled membrane element, such as Figure 1 As shown, the spacer net includes a first spacer net filament 1 and a second spacer net filament 2, and the first spacer net filament 1 and the second spacer net filament 2 are interlaced and arranged; the cross section 3 of the spacer net filament is a fish-like structure; in a flattened state, the first spacer net filament 1 and the second spacer net filament 2 are located in different planes, and the planes where the spacer net filaments are located are perpendicular to the normal direction of the spacer net plane;

[0037] The fish-like structure includes a head structure and a tail structure; the head structure faces the upstream direction, and the tail structure faces the downstream direction;

[0038] The head structure is a semi-cylindrical structure, and the tail structure is a fishtail-like structure;

[0039] The distance between the head structure and the tail structure is 0.45 mm ( Figure 1 The distance marked on the cross section 3 of the filaments of the septum mesh);

[0040] The cross-sectional diameter of the head structure is 0.34 mm; the cross-sectional diameter of the tail structure is 0.15 mm;

[0041] The included angle of the tail structure is 53°; the spacing between adjacent first spacer filaments 1 and adjacent second spacer filaments 2 is equal, both 3 mm (6.7 times the spacing between the head structure and the tail structure); the included angle between the spacer filaments and the water inlet direction of the flow channel is 45°;

[0042] The first spacer mesh filaments 1 and the second spacer mesh filaments 2 are interwoven to form a quadrilateral grid unit; the four vertices of the grid unit are the interweaving points of the first spacer mesh filaments 1 and the second spacer mesh filaments 2, which protrude upward or downward respectively, serving as fulcrums to separate and support the membranes on both sides of the spacer mesh.

[0043] Example 2

[0044] This embodiment provides a vortex capture spacer for a rolled membrane element. The only difference from Embodiment 1 is that the spacing between adjacent first spacer filaments 1 and adjacent second spacer filaments 2 is equal, both are 1.35 mm (3 times the spacing between the head structure and the tail structure), and the rest is the same as Embodiment 1.

[0045] Example 3

[0046] This embodiment provides a vortex capture spacer for a rolled membrane element. The only difference from Embodiment 1 is that the spacing between adjacent first spacer filaments 1 and adjacent second spacer filaments 2 is equal, both being 4.95 mm (11 times the spacing between the head structure and the tail structure), and the rest is the same as Embodiment 1.

[0047] Example 4

[0048] This embodiment provides a vortex capture screen for a rolled membrane element, such as Figure 2 As shown, the only difference from Example 1 is that the angle between the spacer filaments and the water inlet direction of the flow channel is 30°, and the rest is the same as Example 1.

[0049] Example 5

[0050] This embodiment provides a vortex capture screen for a rolled membrane element, which is different from Embodiment 1 only in that the angle between the screen filaments and the water inlet direction of the flow channel is 5°, and the rest is the same as Embodiment 1.

[0051] Example 6

[0052] This embodiment provides a vortex capture screen for a rolled membrane element, which is different from Embodiment 1 only in that the angle between the screen filaments and the water inlet direction of the flow channel is 70°, and the rest is the same as Embodiment 1.

[0053] Comparative Example 1

[0054] This comparative example provides a vortex capture screen for a spiral membrane element, such as Figure 3 As shown, the spacer net includes a first spacer net filament 4 and a second spacer net filament 5, and the first spacer net filament 4 and the second spacer net filament 5 are interlaced and arranged; the cross section 6 of the spacer net filament is circular; in a flattened state, the longitudinal spacer net filament 4 and the transverse spacer net filament 5 are located in different planes, and the planes where the spacer net filaments are located are perpendicular to the normal direction of the spacer net plane;

[0055] The diameter of the cross section 6 of the spacer wire is 0.34 mm;

[0056] The spacing between adjacent first spacer filaments 4 and adjacent second spacer filaments 5 is equal, both of which are 3 mm; the angle between the spacer filaments and the water inlet direction of the flow channel is 45°;

[0057] The first spacer mesh filaments 4 and the second spacer mesh filaments 5 are interwoven to form a quadrilateral grid unit; the four vertices of the grid unit are the interweaving points of the first spacer mesh filaments 4 and the second spacer mesh filaments 5, which protrude upward or downward respectively, serving as fulcrums to separate and support the membranes on both sides of the spacer mesh.

[0058] Performance Testing

[0059] The membrane performance evaluation test and drag reduction performance test were carried out on the water inlet screens in Examples 1-6 and Comparative Example 1. The specific operations are as follows:

[0060] A Polydimethylsiloxane (PDMS) membrane was placed in a cross-flow filtration test device, and the water inlet screens of Examples 1-6 and Comparative Example 1 were respectively installed for comparative testing. A 5% ethanol aqueous solution was used as the feed liquid, the water inlet flow rate was adjusted between 0.05 m / s and 0.4 m / s, the feed temperature was 50°C, and the vacuum degree was 2000 Pa to perform a pervaporation separation test. The permeate side product was collected by a cold trap cooled by liquid nitrogen, and the ethanol concentration of the product was measured by gas chromatography. The ethanol / water separation factor was calculated, and the results are shown in FIG. Figure 4 A differential pressure transmitter is connected at the inlet and outlet of the cross-flow filtration test device to measure the inlet and outlet pressure difference of the device. The result is shown in Figure 5 shown.

[0061] By comparing Example 1 with Examples 2-3, it can be seen that when the spacing between the spacer filaments is not within the range of 4 to 10 times the spacing between the head structure and the tail structure, the performance of the membrane module decreases and the energy consumption increases. Figure 4 and Figure 5 As shown, when the feed flow rate is in the range of 0.05 m / s to 0.4 m / s, the pressure drop increase in Example 2 is between 139.6% and 161.5%; and although Example 3 has a lower pressure drop, its separation factor decreases by 2.6% to 3.0%.

[0062] By comparing Example 1 with Example 4, it can be seen that Example 4 optimizes the screen angle on the basis of Example 1, strengthens the vortex capture effect, and thus further suppresses the energy loss caused by vortex dissipation. Figure 4 and Figure 5 It can be seen that when the flow velocity is 0.4 m / s, compared with Example 1, Example 4 can reduce the flow channel pressure drop by 29.0%.

[0063] By comparing Example 4 with Examples 5-6, it can be seen that when the angle of the spacer filaments is not within the range of 10-60°, the separation selectivity of the membrane module will be reduced and the energy consumption will be increased. Figure 4 and Figure 5 As shown, although Example 5 can reduce energy consumption, it also causes the separation factor to drop by 4.3%; while Example 6 increases energy consumption by 144.3% while enhancing mass transfer.

[0064] By comparing Example 1 with Comparative Example 1, it can be seen that in Example 1, setting the cross-section of the separator filaments to a fish-like structure can effectively enhance mass transfer and reduce flow resistance. Figure 4 and Figure 5It can be seen that compared with the comparative example 1 in which the cross-section of the spacer filaments is set to be circular, Example 1 can suppress the concentration polarization inside the flow channel at a low flow rate (0.05 m / s), and increase the separation factor from 9.5 to 9.7, an increase of 2.1%; as the flow rate increases to 0.4 m / s, Example 1 can also effectively reduce the flow channel pressure drop by 16.3%.

[0065] In summary, the present invention provides a vortex capture screen for a rolled membrane element. Through the structural design of the screen, the cross-section of the screen filaments is set to a fish-like structure, which optimizes the internal flow channel of the membrane element, improves the capture and utilization efficiency of the screen filaments for the upstream side vortex, inhibits invalid vortex dissipation, strengthens mass transfer while reducing flow resistance, inhibits the formation of flow dead zones, and ultimately improves the separation selectivity and anti-pollution performance of the membrane component, and reduces production energy consumption.

[0066] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A vortex capture screen for a rolled membrane element, characterized in that: The spacer net includes a first spacer net filament and a second spacer net filament, and the first spacer net filament and the second spacer net filament are arranged in an interlaced manner; the cross-section of the spacer net filament is a fish-like structure; in a flat state, the first spacer net filament and the second spacer net filament are located in different planes.

2. The screen according to claim 1, characterized in that: The fish-like structure comprises a head structure and a tail structure; the head structure faces the upstream direction, and the tail structure faces the downstream direction.

3. The screen according to claim 1 or 2, characterized in that: The head structure is a semi-cylindrical structure, and the tail structure is a fishtail-like structure.

4. The screen according to any one of claims 1 to 3, characterized in that: The distance between the head structure and the tail structure is 0.3mm-0.8mm.

5. The screen according to any one of claims 1 to 4, characterized in that: The cross-sectional diameter of the head structure is 0.2mm-0.6mm; the cross-sectional diameter of the tail structure is 0.1mm-0.3mm.

6. The screen according to any one of claims 1 to 5, characterized in that: The included angle of the tail structure is 45°-70°.

7. The screen according to any one of claims 1 to 6, characterized in that: The spacing between adjacent first spacer filaments and adjacent second spacer filaments is equal, which is 4 to 10 times the spacing between the head structure and the tail structure.

8. The screen according to any one of claims 1 to 7, characterized in that: The angle between the spacer filaments and the water inlet direction of the flow channel is 10°-60°.

9. The screen according to any one of claims 1 to 8, characterized in that: The first spacer mesh filaments and the second spacer mesh filaments are interwoven to form a quadrilateral grid unit; the four vertices of the grid unit are the interweaving points of the first spacer mesh filaments and the second spacer mesh filaments, which protrude upward or downward respectively and serve as fulcrums to separate and support the membranes on both sides of the spacer mesh.

10. A wound membrane element, characterized in that: The water inlet spacer of the rolled membrane element is the spacer described in any one of claims 1-9.

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