Spiral-wound membrane element

Abstract

The utility model relates to the technical field of membrane separation, in particular to a spiral-wound membrane element. 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. According to the spiral-wound membrane element provided by the utility model, 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 utility model relates to the field of membrane separation technology, specifically relates to a roll type membrane element. BACKGROUND

[0002] The current traditional roll type membrane element is formed by laminating a concentrated water grid, a membrane sheet and a dilute water grid and then winding on a central water production pipe to form a roll type membrane element. When the roll type membrane element is used to purify wastewater, if the wastewater recovery rate increases, the amount of pure water increases and the amount of wastewater decreases, and the flow rate of concentrated wastewater flowing out of the water outlet end of the roll type membrane element decreases. Since the concentrated wastewater has salt crystallization, the low flow rate makes the crystalline substances easily deposited on the surface of the membrane sheet, blocking the membrane holes, resulting in a gradual decrease in the water flux of the roll type membrane element and eventually leading to the end of the service life.

[0003] In view of the above, it is necessary to develop a roll type membrane element to solve the problem that the existing roll type membrane element is prone to depositing crystalline substances on the membrane sheet when the wastewater recovery rate increases, resulting in the blocking of the membrane holes. SUMMARY

[0004] The utility model aims at providing a roll type membrane element, and the specific technical scheme is as follows:

[0005] A roll type 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 roll type membrane element. A waterproof adhesive layer is arranged on the water outlet end of the combined membrane element. The length of the waterproof adhesive layer is less than the length of the water outlet end.

[0006] Optionally, the combined membrane element comprises a membrane sheet, a concentrated water separation grid and a dilute water separation grid. The membrane sheet is a folded membrane sheet. The concentrated water separation grid is arranged in the middle of the folded membrane sheet. The waterproof adhesive layer is arranged on the water outlet end of the concentrated water separation grid. The dilute water separation grid is arranged on the outside of the folded membrane sheet.

[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 end.

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

[0010] Optionally, the waterproof adhesive layer comprises a plurality of waterproof unit adhesive layers. A water passing gap is arranged between every two adjacent waterproof unit adhesive layers.

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

[0012] Optionally, a resin adhesive layer is arranged 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 and is adhered to the folded membrane.

[0013] Optionally, the roll type membrane element further comprises an appearance protection film; and the appearance protection film is wound on the roll type membrane element.

[0014] Optionally, the roll type membrane element comprises any one of a reverse osmosis roll type membrane element, a nanofiltration roll type membrane element, an ultrafiltration roll type membrane element and a forward osmosis roll type membrane element.

[0015] The technical scheme of the roll type membrane element has at least the following beneficial effects:

[0016] The roll type membrane element has the water isolation adhesive layer arranged on the water outlet end of the combined membrane element, and the length of the water isolation adhesive layer is less than the length of the water outlet end, so that the water outlet size of the water outlet end is reduced, the wastewater flow rate at the water outlet is increased, and the risk that the membrane holes are blocked by the deposition of crystalline substances on the membrane is reduced; even when the wastewater recovery rate is increased, that is, the pure water amount is increased and the wastewater amount is reduced, the wastewater flow rate at the water outlet will not be reduced, and even will be increased, which helps to reduce the deposition of crystalline substances on the membrane, solves the problem that the membrane holes are easily blocked by the deposition of crystalline substances on the membrane when the wastewater recovery rate is increased, and improves the service life of the membrane element.

[0017] In addition to the objects, features and advantages described above, the present application has other objects, features and advantages. Hereinafter, the present application will be described in detail with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated herein for purposes of illustration. The embodiments of the present application, and the specification are exemplary embodiments of the present application and are not intended to limit the present application in any way. In the drawings:

[0019] Figure 1 is a structure schematic view of a roll type membrane element in Example 1 during manufacturing;

[0020] Figure 2 is a flow schematic view of a combined membrane element during manufacturing (the fresh water screen is not shown in the figure);

[0021] Figure 3 is a working schematic view when purifying wastewater after forming the water isolation adhesive layer on the concentrated water screen;

[0022] Figure 4 is a working schematic view when purifying wastewater by the concentrated water screen in Comparative Example 1;

[0023] Figure 5 is an operation schematic diagram when the concentrated water screen purifies wastewater in Comparative Example 2;

[0024] wherein, in Figures 3-5 the arrow direction in indicates the water flow direction;

[0025] 1, combined membrane element, 1.1, folded membrane sheet, 1.2, concentrated water screen, 1.3, fresh water screen, 2, central water production pipe, 3, water isolation adhesive layer, 3.1, water isolation unit adhesive layer, 4, resin adhesive layer. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0027] Embodiment 1:

[0028] Referring to Figures 1-3 , a roll type membrane element 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 roll type membrane element; a water isolation adhesive layer 3 is arranged on a water outlet end of the combined membrane element 1; the length of the water isolation adhesive layer 3 is less than the length of the water outlet end.

[0029] Referring to 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 arranged in the middle of the folded membrane sheet 1.1 in a stacked manner, referring to Figure 2 B1 process and B2 process; the folding direction of the folded membrane sheet 1.1 refers to the direction W in Figure 2 ; the water isolation adhesive layer 3 is arranged on a water outlet end of the concentrated water screen 1.2; the fresh water screen 1.3 is arranged on the outside of the folded membrane sheet 1.1 in a stacked manner.

[0030] Referring to Figure 3 , the length of the water isolation adhesive layer 3 is 50% of the length of the water outlet end, which is convenient for reserving a small size water outlet to increase the wastewater flow rate and reduce the risk of membrane holes being blocked due to the deposition of crystalline substances on the membrane sheet. The water isolation adhesive layer 3 is a polyurethane resin layer, which effectively ensures the close adhesion of the concentrated water screen and the membrane sheet.

[0031] Referring to Figure 3 , the water isolation adhesive layer 3 is 20mm away from the water outlet end, avoiding occupying the effective area of the roll type membrane element.

[0032] Referring to Figure 3 , the water-proof glue layer 3 has a width of 2mm along the water outlet direction, which ensures the water-proof effect.

[0033] Referring to Figure 3 , the water-proof glue layer 3 comprises a plurality of water-proof unit glue layers 3.1; a water passing gap is arranged between each two adjacent water-proof unit glue layers 3.1, so as to reduce the size of the water outlet. The sum of the lengths of each water-proof unit glue layer 3.1 is the length of the water-proof glue layer 3.

[0034] The opening end of the foldable membrane 1.1 is a staggered opening structure, referring to the opening structure A in Figure 2 , so as to increase the effective area of the roll type membrane element and improve the pure water production rate.

[0035] The resin glue layer 4 is arranged on the water inlet end, the water outlet end and the end corresponding to the opening end of the foldable membrane 1.1 of the fresh water screen 1.3 and is pasted to the foldable membrane 1.1. The resin glue layer 4 is a polyurethane resin layer, which effectively ensures the sealing of the fresh water screen and the membrane.

[0036] The roll type membrane element further comprises an appearance protection film (not shown in the figure); the appearance protection film is wound on the roll type membrane element, so as to realize the shaping of the roll type membrane element.

[0037] The manufacturing method of the roll type membrane element comprises the following steps:

[0038] Step S1, the concentrated water screen 1.2 is arranged on the middle layer of the foldable membrane 1.1; the water-proof glue layer 3 is arranged on the water outlet end of the concentrated water screen 1.2;

[0039] Step S2, the fresh water screen 1.3 is arranged on the outer side of the foldable membrane 1.1; the resin glue layer 4 is arranged on the water inlet end, the water outlet end and the end corresponding to the opening end of the foldable membrane 1.1 of the fresh water screen 1.3 and is pasted to the foldable membrane 1.1;

[0040] Step S3, the combined membrane element 1 is wound on the center water production pipe 2 along the direction from the closed end to the opening end of the foldable membrane 1.1, so as to form the roll type membrane element; the appearance protection film is wound on the roll type membrane element, so as to realize the shaping of the roll type membrane element.

[0041] The roll type membrane element is a reverse osmosis roll type membrane element.

[0042] Comparative Example 1:

[0043] Referring to Figure 4 , different from Example 1, the water-proof glue layer 3 is not arranged on the water outlet end of the concentrated water screen 1.2.

[0044] Comparative Example 2:

[0045] See also Figure 5 , which is different from Example 1, is that the water-proof adhesive layer 3 is also provided on the water inlet end of the concentrated water screen 1.2.

[0046] 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:

[0047] Test conditions:

[0048] 1. Effective area of ​​the same width and membrane elements of the same size;

[0049] 2. Test water requirements (see Section 6.1.1 of GB 34914-2021):

[0050] The test water should be prepared with pure water (conductivity <10μS / cm), and the water quality requirements are as follows:

[0051] a) The total hardness should be controlled within (250 ± 20) mg / L;

[0052] b) Alkalinity should be controlled within (140 ± 10) mg / L;

[0053] c) The electrical conductivity should be controlled within (1000 ± 100) μS / cm;

[0054] d) The pH value should be controlled between 7.0 and 7.5;

[0055] e) Turbidity should not exceed 1NTU.

[0056] 3. Test water preparation method (see Appendix A.2 of GB 34914-2021):

[0057] Use pure water (conductivity <10μS / cm) to prepare the standard solution according to the following steps (taking the preparation of 100L of test water as an example);

[0058] 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 each in 200 ml of pure water; weigh 26.53 g of sodium bicarbonate (NaHCO3) and dissolve it in 350 ml of pure water;

[0059] b) Add the above solutions into 100L of pure water in sequence, stirring evenly after adding each solution. Stir thoroughly after adding all the solutions.

[0060] c) Use sodium hydroxide solution (mass concentration 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;

[0061] d) The prepared test water should be stored in a sealed container away from light and should be used immediately after preparation. Test water prepared overnight should not be used.

[0062] 3.Pressure before membrane is 100Psi, recovery rate is 65%, and water production is 2500L.

[0063] Table 1 Anti-scaling and life test of various spiral membrane elements

[0064] Grouping Attenuation rate (%) after water production 2500 L by spiral-wound membrane element Comparative Example 1 35.1 Comparative Example 2 21.8 Example 1 17.4

[0065] From the data in Table 1, it can be seen that compared with Comparative Examples 1-2, the rolled membrane element prepared using Example 1 of the present invention has the lowest attenuation rate. This is because a water-blocking adhesive layer 3 is provided on the outlet end of the composite membrane element 1 using Example 1, and the length of the water-blocking adhesive layer 3 is less than the length of the outlet end, which can reduce the size of the outlet end, thereby increasing the wastewater flow rate at the outlet and reducing the risk of clogging the membrane pores due to the deposition of crystalline substances on the membrane sheet, thereby reducing the attenuation rate of the rolled membrane element. For further information, see Figure 3 The water-proof adhesive layer 3 includes multiple water-proof unit adhesive layers 3.1; a water gap is set between each two adjacent water-proof unit adhesive layers 3.1 to reduce the size of the water outlet and increase the wastewater flow rate at the water outlet, which helps to reduce the deposition of crystalline substances on the membrane and improve the service life of the membrane element.

[0066] In comparative example 2, a waterproof adhesive 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 its attenuation rate.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A wound membrane element, 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-proof adhesive layer (3) is provided on the water outlet end of the combined membrane element (1); the length of the water-proof adhesive layer (3) is less than the length of the water outlet end; the length of the water-proof adhesive layer (3) is 45%-55% of the length of the water outlet end; the water-proof adhesive layer (3) comprises a plurality of water-proof unit adhesive layers (3.1); and a water-passing gap is provided between each two adjacent water-proof unit adhesive layers (3.1).

2. The wound membrane element according to claim 1, characterized in that The combined membrane element (1) comprises a membrane, a concentrated water separator (1.2) and a fresh water separator (1.3); the membrane is a folded membrane (1.1); the concentrated water separator (1.2) is stacked in the middle of the folded membrane (1.1); the water-isolating adhesive layer (3) is provided 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 (1.1).

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

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

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

6. The wound membrane element according to claim 2, 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 open end of the folded membrane (1.1) of the fresh water separator (1.3).

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

8. The wound membrane element according to any one of claims 2 to 7, characterized in that: 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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