Spiral-wound membrane element and manufacturing method thereof

Abstract

The invention relates to the technical field of membrane separation, in particular to a spiral-wound membrane element and a manufacturing method thereof. The spiral-wound membrane element comprises a combined membrane element and a central water production pipe, the combined membrane element is wound on the central water production pipe to form a spiral-wound membrane element; a waterproof adhesive layer is arranged at the water outlet end of the combined membrane element; the length of the waterproof glue layer is smaller than that of the water outlet end. The manufacturing method is used for manufacturing the spiral-wound membrane element. According to the spiral-wound membrane element prepared by the invention, the size of the water outlet at the water outlet end can be reduced, so that the flow rate of wastewater at the water outlet is increased, the risk that membrane holes are blocked due to deposition of crystalline substances on the membrane is reduced, and the service life of the membrane element is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation, and in particular to a rolled membrane element and a manufacturing method thereof. Background Art

[0002] At present, the traditional spiral membrane element is formed by stacking concentrated water grid, membrane and dilute mesh, and then rolling and winding them on the central water production pipe. When using this spiral membrane element to purify wastewater, if the wastewater recovery rate increases, the amount of pure water increases, the amount of wastewater decreases, and the flow rate of concentrated wastewater flowing out of the outlet end of the spiral membrane element decreases; because the concentrated wastewater has salt precipitation and crystallization, the flow rate is low, and the crystallized material is very easy to deposit on the surface of the membrane, blocking the membrane pores, causing the water flux of the spiral membrane element to gradually decrease, and eventually end its life.

[0003] In summary, it is necessary to develop a rolled membrane element and a method for manufacturing the same to solve the problem that crystalline substances are easily deposited on the membrane sheet of the existing rolled membrane element when the wastewater recovery rate increases, causing the membrane pores to be blocked. Summary of the invention

[0004] The object of the present invention is to provide a rolled membrane element and a method for manufacturing the same. The specific technical scheme is as follows:

[0005] In the first aspect, the present invention provides a rolled membrane element, comprising a combined membrane element and a central water production pipe; the combined membrane element is wound on the central water production pipe to form a rolled membrane element; a waterproof rubber layer is arranged on the water outlet end of the combined membrane element; the length of the waterproof rubber layer is less than the length of the water outlet end.

[0006] Optionally, the combined membrane element includes a diaphragm, a concentrated water separator and a fresh water separator; the diaphragm is a folding diaphragm; the concentrated water separator is stacked in the middle of the folding diaphragm; the waterproof adhesive layer is arranged on the water outlet end of the concentrated water separator; the fresh water separator is stacked on the outer side of the folding diaphragm.

[0007] Optionally, the length of the waterproof adhesive layer is 45%-55% of the length of the water outlet end.

[0008] Optionally, the waterproof adhesive layer is 15-25 mm away from the water outlet.

[0009] Optionally, the width of the waterproof adhesive layer along the water outlet direction is 2-4 mm.

[0010] Optionally, the water-proof adhesive layer includes a plurality of water-proof unit adhesive layers; a water-passing gap is arranged between each two adjacent water-proof unit adhesive layers.

[0011] Optionally, the opening end of the folded membrane is a staggered opening structure.

[0012] Optionally, a resin adhesive layer for adhering to the folded membrane is provided on the water inlet end, the water outlet end and the end corresponding to the opening end of the folded membrane of the fresh water separator.

[0013] Optionally, the rolled membrane element further includes an appearance protection film; the appearance protection film is wound on the rolled membrane element.

[0014] In a second aspect, the present invention provides a method for preparing the wound membrane element as described above, comprising:

[0015] Step S1, stacking the concentrated water separator in the middle of the folded membrane; and arranging the water-isolating adhesive layer on the water outlet end of the concentrated water separator;

[0016] Step S2, stacking the fresh water screen on the outer side of the folded membrane; and providing a resin adhesive layer for adhering to the folded membrane on the water inlet end, the water outlet end and the end corresponding to the opening end of the folded membrane of the fresh water screen;

[0017] Step S3, winding the combined membrane element on the central water production pipe in the direction from the closed end to the open end of the folded membrane sheet to form the rolled membrane element;

[0018] The rolled membrane element includes any one of a reverse osmosis rolled membrane element, a nanofiltration rolled membrane element, an ultrafiltration rolled membrane element and a forward osmosis rolled membrane element.

[0019] The application of the technical solution of the present invention has at least the following beneficial effects:

[0020] (1) The present invention provides a rolled membrane element, in which a waterproof glue layer is arranged on the water outlet end of the combined membrane element, and the length of the waterproof glue layer is less than the length of the water outlet end, which can reduce the size of the water outlet at the water outlet end, so as to increase the wastewater flow rate at the water outlet and reduce the risk of crystalline substances deposited on the membrane sheet causing the membrane pores to be blocked; even when the wastewater recovery rate increases, that is, the amount of pure water increases and the amount of wastewater decreases, when the size of the water outlet is reduced, the flow rate of the wastewater at the water outlet will not decrease, and may even increase, which helps to reduce the deposition of crystalline substances on the membrane sheet, solves the problem that crystalline substances are easily deposited on the membrane sheet when the wastewater recovery rate increases, causing the membrane pores to be blocked, and can also increase the service life of the membrane element.

[0021] (2) The present invention provides a method for manufacturing a rolled membrane element, which is simple and easy to implement and has strong practicality. The rolled membrane element manufactured by the present invention has a smaller water outlet size, which helps to reduce the deposition of crystalline substances on the membrane, has high anti-scaling and low attenuation properties, and is suitable for municipal tap water desalination and drinking water purification.

[0022] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 is a schematic structural diagram of a rolled membrane element in Example 1 during production;

[0025] Figure 2 This is a schematic diagram of the process of manufacturing a combined membrane element (the fresh water separator is not shown in the figure);

[0026] Figure 3 It is a schematic diagram of the operation when purifying wastewater after a water-proof adhesive layer is formed on the concentrated water separator;

[0027] Figure 4 This is a schematic diagram of the operation of the concentrated water screen for purifying wastewater in Example 1;

[0028] Figure 5 This is a schematic diagram of the operation of the concentrated water screen for purifying wastewater in Example 2;

[0029] Among them, Figure 3-Figure 5 The direction of the arrow in the figure indicates the direction of water flow;

[0030] 1. Combined membrane element, 1.1. Folded membrane sheet, 1.2. Concentrated water separator, 1.3. Fresh water separator, 2. Central water production pipe, 3. Water-proof adhesive layer, 3.1. Water-proof unit adhesive layer, 4. Resin adhesive layer. DETAILED DESCRIPTION

[0031] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0032] Embodiment 1:

[0033] See also Figure 1-Figure 3 A rolled membrane element comprises a combined membrane element 1 and a central water production pipe 2; the combined membrane element 1 is wound around the central water production pipe 2 to form a rolled membrane element; a waterproof adhesive layer 3 is arranged on the water outlet end of the combined membrane element 1; the length of the waterproof adhesive layer 3 is less than the length of the water outlet end.

[0034] See also Figure 2 The combined membrane element 1 comprises a membrane sheet, a concentrated water screen 1.2 and a fresh water screen 1.3; the membrane sheet is a folded membrane sheet 1.1; the concentrated water screen 1.2 is stacked in the middle of the folded membrane sheet 1.1, see Figure 2 The B1 process and the B2 process in the embodiment; the folding direction of the folding film 1.1 is shown in FIG. Figure 2 The water-proof adhesive layer 3 is provided on the outlet end of the concentrated water separator 1.2; the fresh water separator 1.3 is stacked on the outer side of the folded membrane 1.1.

[0035] See also Figure 3 The length of the waterproof adhesive layer 3 is 50% of the length of the water outlet, which is convenient for reserving a small-sized outlet to increase the wastewater flow rate and reduce the risk of clogging the membrane pores due to the deposition of crystalline substances on the membrane. The waterproof adhesive layer 3 is a polyurethane resin layer, which effectively ensures the tight adhesion of the concentrated water grid and the membrane.

[0036] See also Figure 3 The waterproof adhesive layer 3 is 20 mm away from the water outlet to avoid occupying the effective area of ​​the rolled membrane element.

[0037] See also Figure 3 The width of the waterproof adhesive layer 3 along the water outlet direction is 2 mm to ensure the waterproof effect.

[0038] See also Figure 3 The waterproof adhesive layer 3 includes a plurality of waterproof unit adhesive layers 3.1; a water gap is provided between each two adjacent waterproof unit adhesive layers 3.1 to reduce the size of the water outlet. The sum of the lengths of the waterproof unit adhesive layers 3.1 is the length of the waterproof adhesive layer 3.

[0039] The opening end of the folded membrane 1.1 is a staggered opening structure, see Figure 2 The opening structure A in the membrane is used to increase the effective area of ​​the rolled membrane element and improve the pure water production rate.

[0040] A resin adhesive layer 4 is provided on the water inlet and outlet ends of the freshwater separator 1.3 and the end corresponding to the opening end of the folded membrane 1.1. The resin adhesive layer 4 is a polyurethane resin layer, which effectively ensures the sealing of the freshwater grid and the membrane.

[0041] The rolled membrane element further comprises an appearance protection film (not shown in the figure); the appearance protection film is wound on the rolled membrane element to achieve shaping of the rolled membrane element.

[0042] The method for manufacturing the rolled membrane element comprises:

[0043] Step S1, stacking the concentrated water screen 1.2 in the middle of the folded membrane 1.1; and arranging the water-isolating adhesive layer 3 on the water outlet end of the concentrated water screen 1.2;

[0044] Step S2, stacking the fresh water screen 1.3 on the outer side of the folding membrane 1.1; and providing a resin adhesive layer 4 adhered to the folding membrane 1.1 on the water inlet end, the water outlet end and the end corresponding to the opening end of the folding membrane 1.1 of the fresh water screen 1.3;

[0045] Step S3, winding the combined membrane element 1 on the central water production pipe 2 along the direction from the closed end to the open end of the folded membrane sheet 1.1 to form the rolled membrane element; winding the appearance protection film on the rolled membrane element to achieve shaping of the rolled membrane element.

[0046] The rolled membrane element is a reverse osmosis rolled membrane element.

[0047] Comparative Example 1:

[0048] See also Figure 4 , which is different from Example 1, the water-proof adhesive layer 3 is not provided on the water outlet end of the concentrated water screen 1.2.

[0049] Comparative Example 2:

[0050] See also Figure 5 , which is different from Example 1, the waterproof adhesive layer 3 is also provided on the water inlet end of the concentrated water screen 1.2.

[0051] The spiral membrane elements prepared in Example 1 and Comparative Examples 1-2 were subjected to anti-scaling and life tests, and the test results are shown in Table 1. The specific test process is as follows:

[0052] Test conditions:

[0053] 1. Effective area of ​​the same width and membrane elements of the same size;

[0054] 2. Test water requirements (see Section 6.1.1 of GB 34914-2021):

[0055] The test water should be prepared with pure water (conductivity <10μS / cm), and the water quality requirements are as follows:

[0056] a) The total hardness should be controlled within (250 ± 20) mg / L;

[0057] b) Alkalinity should be controlled within (140 ± 10) mg / L;

[0058] c) The conductivity should be controlled within (1000±100)μS / cm;

[0059] d) pH value should be controlled between 7.0 and 7.5;

[0060] e) Turbidity should not be greater than 1NTU.

[0061] 3. Test water preparation method (see Appendix A.2 of GB 34914-2021):

[0062] Use pure water (conductivity <10μS / cm) to prepare the standard solution according to the following steps (taking the preparation of 100L test water as an example);

[0063] a) Weigh 25.1 g of calcium chloride dihydrate (CaCl2·2H2O), 21.05 g of magnesium sulfate heptahydrate (MgSO4·7H2O) and 7.90 g of sodium chloride (NaCl) and dissolve them in 200 ml of pure water; weigh 26.53 g of sodium bicarbonate (NaHCO3) and dissolve them in 350 ml of pure water;

[0064] b) Add the above solutions into 100L pure water in sequence, and stir evenly immediately after adding each solution. Stir evenly after adding all the solutions;

[0065] c) Use sodium hydroxide solution (mass concentration of 40g / L) or hydrochloric acid solution (1+1) to adjust the pH value to within the range of 7.0 to 7.5 to obtain test water;

[0066] d) The prepared test water should be stored in a light-proof, airtight container and used immediately after preparation. Test water prepared overnight should not be used.

[0067] 3.Pressure before membrane is 100Psi, recovery rate is 65%, and water production is 2500L.

[0068] Table 1 Anti-scaling and life test of various spiral membrane elements

[0069] Grouping Attenuation rate of spiral membrane element after producing 2500L of water (%) Comparative Example 1 35.1 Comparative Example 2 21.8 Example 1 17.4

[0070] From the data in Table 1, it can be seen that compared with Comparative Examples 1-2, the roll-type membrane element prepared by Example 1 of the present invention has the lowest attenuation rate. This is because a water-blocking glue layer 3 is provided on the water outlet end of the combined membrane element 1 by Example 1, and the length of the water-blocking glue layer 3 is less than the length of the water outlet end, which can reduce the size of the water outlet of the water outlet end, so as to increase the wastewater flow rate at the water outlet, reduce the risk of clogging the membrane pores due to the deposition of crystalline substances on the membrane sheet, and thus reduce the attenuation rate of the roll-type membrane element. For further information, see Figure 3The waterproof adhesive layer 3 includes a plurality of waterproof unit adhesive layers 3.1; a water gap is arranged between each two adjacent waterproof unit adhesive layers 3.1 so as to reduce the size of the water outlet, increase the wastewater flow rate at the water outlet, help reduce the deposition of crystalline substances on the membrane, and improve the service life of the membrane element.

[0071] In Comparative Example 2, a waterproof rubber layer 3 is provided on both the water inlet and outlet ends of the concentrated water screen 1.2, but this fails to effectively increase the wastewater flow rate to reduce the deposition of crystalline substances on the membrane, thereby resulting in an insignificant reduction in the attenuation rate.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A spiral membrane element, It is characterized in that The invention comprises a combined membrane element (1) and a central water production pipe (2); the combined membrane element (1) is wound on the central water production pipe (2) to form a rolled membrane element; a water-proofing rubber layer (3) is provided on the water outlet end of the combined membrane element (1); the length of the water-proofing rubber layer (3) is shorter than the length of the water outlet end.

2. The wound membrane element according to claim 1, It is characterized in that The combined membrane element (1) comprises a membrane sheet, a concentrated water separator (1.2) and a fresh water separator (1.3); the membrane sheet is a folded membrane sheet (1.1); the concentrated water separator (1.2) is stacked in the middle of the folded membrane sheet (1.1); the water-isolating glue layer (3) is arranged on the water outlet end of the concentrated water separator (1.2); and the fresh water separator (1.3) is stacked on the outer side of the folded membrane sheet (1.1).

3. The wound membrane element according to claim 2, It is characterized in that The length of the water-insulating adhesive layer (3) is 45%-55% of the length of the water outlet end.

4. The wound membrane element according to claim 2, It is characterized in that The waterproof adhesive layer (3) is 15-25 mm away from the water outlet.

5. The wound membrane element according to claim 2, It is characterized in that The width of the water-insulating adhesive layer (3) along the water outlet direction is 2-4 mm.

6. The wound membrane element according to claim 2, It is characterized in that The water-proof adhesive layer (3) comprises a plurality of water-proof unit adhesive layers (3.1); a water-passing gap is provided between each two adjacent water-proof unit adhesive layers (3.1).

7. The wound membrane element according to claim 2, It is characterized in that The opening end of the folded membrane (1.1) is a staggered opening structure.

8. The wound membrane element according to claim 2, It is characterized in that A resin adhesive layer (4) adhered to the folded membrane (1.1) is provided on the water inlet end, the water outlet end and the end corresponding to the opening end of the folded membrane (1.1) of the fresh water separator (1.3).

9. The wound membrane element according to claim 2, It is characterized in that It also includes an appearance protection film; the appearance protection film is wound on the roll-type membrane element.

10. A method for preparing a wound membrane element according to any one of claims 2 to 9, It is characterized in that include: Step S1, stacking the concentrated water separator (1.2) in the middle of the folded membrane (1.1); The water-isolating adhesive layer (3) is arranged on the water outlet end of the concentrated water isolation net (1.2); Step S2, stacking the fresh water separator (1.3) on the outer side of the folded membrane (1.1); providing a resin adhesive layer (4) adhered to the folded membrane (1.1) on the water inlet end, the water outlet end and the end corresponding to the opening end of the folded membrane (1.1) of the fresh water separator (1.3); Step S3, winding the combined membrane element (1) on the central water production pipe (2) in the direction from the closed end to the open end of the folded membrane sheet (1.1) to form the rolled membrane element; The rolled membrane element includes any one of a reverse osmosis rolled membrane element, a nanofiltration rolled membrane element, an ultrafiltration rolled membrane element and a forward osmosis rolled membrane element.

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