Membrane element and filter comprising same

Abstract

The membrane element comprises a water collecting pipe, water collecting holes are formed in the pipe wall of the water collecting pipe to collect purified water, and a first membrane unit and a second membrane unit which are wound side by side are arranged on the water collecting pipe; the adjacent end faces of the first diaphragm unit and the second diaphragm unit are partially sealed through a sealant to form a first opening, the adjacent end faces of the second diaphragm unit and the first diaphragm unit are partially sealed through the sealant to form a second opening, and the first opening is aligned with the second opening and communicated with the second opening in a sealed mode. According to the technical scheme I or the technical scheme II, internal raw water is accelerated by arranging the second membrane unit, and the raw water is integrally in a side flow state in the membrane element, so that the width of a raw water flow channel of the membrane element is reduced, the flow speed of the raw water on the surface of the membrane is increased, the deposition speed and the deposition amount of pollutants can be reduced, and the pollution to the environment is reduced. The filtering performance and the service life of the membrane element are improved.

Description

Technical Field

[0001] The present invention relates to the field of water purification equipment, and particularly to a membrane element and a filter including the same. Background Art

[0002] At present, spiral wound membrane elements are widely used in the fields of industrial water treatment and household water purification. Conventional spiral wound membrane elements basically adopt an "end-to-end" flow mode. However, due to the wide flow channel and short flow path of this flow mode, the fluid velocity is low, and the concentration polarization phenomenon on the membrane surface is serious. The serious concentration polarization phenomenon will lead to three problems: First, the salt concentration on the membrane surface increases, resulting in a decrease in the desalination rate and a reduction in the flow rate of the membrane element; Second, the concentration of pollutants on the membrane surface increases, making the membrane surface more easily contaminated, thereby reducing the flow rate and service life of the membrane element; Third, the decrease in fluid velocity makes it difficult for the pollutants deposited on the membrane surface to be washed away, resulting in the enrichment of pollutants, thus further shortening the service life of the membrane element.

[0003] In order to alleviate the concentration polarization phenomenon on the membrane surface and improve the performance and service life of the membrane element, side-flow membrane elements are often used at present. In the existing double "L"-type membrane element, the double "L"-type fluids flow towards each other and change the flow direction after meeting, so there are problems of energy loss and fluid dead zones at the meeting point; in the single "L"-type membrane element, the fluid flows from the inlet to the other side and changes the flow direction after encountering the side, so there are problems of energy loss and dead zones at the turning point; the single "L"-type membrane element with a water collecting pipe uses multiple water collecting pipes for diversion, resulting in an increase in material cost and process complexity, and a significant increase in the cost of the membrane element; the membrane element with an "S"-type flow channel has a complex process, the performance improvement is not significant, and there is a risk of damaging the membrane surface and causing performance degradation; the "gyro" type membrane element has a complex process and there is a risk of damaging the membrane surface and causing performance degradation; the cut "U"-type membrane element has a complex process and the water path is too long, and the flow velocity at the end drops significantly. In the above membrane element structures, the membrane sheets all adopt an average folding scheme. After all, the side-flow membrane has a long flow path. The flow velocity at the end of the membrane sheet is not only low but also the concentration is high. If the fluid velocity cannot be further increased, the improvement of performance and service life will be limited. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defect that in the existing membrane element, the membrane sheets all adopt an average folding method, which makes the flow channel longer, and the water flow at the end of the membrane sheet is not only low in velocity but also high in concentration, resulting in limited improvement in the performance and service life of the membrane element, and to provide a membrane element and a filter including the same.

[0005] The present invention solves the above technical problem through the following technical solutions:

[0006] The present invention provides a membrane element, which includes a water collecting pipe. Water collecting holes are formed in the pipe wall of the water collecting pipe to collect purified water. It is characterized in that a first membrane unit and a second membrane unit are arranged in parallel and wound around the water collecting pipe. The end faces of the first membrane unit and the second membrane unit adjacent to each other are partially sealed with sealant to form a first opening, and the end faces of the second membrane unit and the first membrane unit adjacent to each other are partially sealed with sealant to form a second opening. The first opening is aligned with the second opening and is hermetically connected to the second opening; there are two technical solutions for the winding body formed by the first membrane unit and the second membrane unit:

[0007] Technical solution 1: The first membrane unit is arranged above the water collecting pipe, and the second membrane unit is arranged below the water collecting pipe; a water inlet is formed on the bottom end face of the second membrane unit near the outer wall surface of the water collecting pipe, and a water outlet is arranged on the top end face of the first membrane unit near the outer wall surface of the water collecting pipe. The water inlet is connected to the first opening and the second opening and then connected to the water outlet. The first opening and the second opening are arranged away from the outer wall surface of the water collecting pipe;

[0008] Technical solution 2: The first membrane unit is arranged below the water collecting pipe, and the second membrane unit is arranged above the water collecting pipe; a water inlet is formed on the bottom end face of the second membrane unit away from the outer wall surface of the water collecting pipe, and a water outlet is arranged on the top end face of the first membrane unit away from the outer wall surface of the water collecting pipe. The water inlet is connected to the first opening and the second opening and then connected to the water outlet. The first opening and the second opening are arranged close to the outer wall surface of the water collecting pipe;

[0009] Among them, the first membrane unit includes a plurality of first membranes stacked in parallel in sequence, and each of the first membranes is equally divided and folded; a first raw water flow channel is formed between the inner surfaces of the first membranes, and the sides of adjacent first membranes away from the water collecting pipe and parallel to the water collecting pipe are hermetically connected to form a first purified water channel between the outer surfaces of adjacent first membranes;

[0010] The second membrane unit includes a plurality of membrane groups stacked in parallel in sequence. Each membrane group includes two second membranes. The second membrane is bent to form a first part and a second part connected in sequence, and the length of the first part is greater than that of the second part; a second raw water flow channel is formed between the inner surfaces of the first part and the second part; the sides of adjacent second membranes away from the water collecting pipe and parallel to the water collecting pipe are hermetically connected to form a second purified water channel between the outer surfaces of each first part and the second part.

[0011] In this solution, whether it is Technical Solution 1 or Technical Solution 2, the second diaphragm unit is set to accelerate the raw water inside, which can compensate for the velocity loss generated during the turning of the "L"-shaped flow channel and avoid too low velocity at the end of the raw water; and the winding body enters water from the lower end face and discharges water from the upper end face, enabling the raw water to present a "U"-shaped flow pattern in the first diaphragm unit and the second diaphragm unit. The raw water is in a side-flow state as a whole in the membrane element, reducing the width of the raw water flow channel of the membrane element and increasing the fluid flow velocity on the surface of the diaphragm. Thereby, it can alleviate the concentration polarization phenomenon on the surface of the diaphragm, slow down the deposition rate and deposition amount of pollutants, and improve the filtration performance and service life of the membrane element.

[0012] Preferably, a first grid is provided between the inner surfaces of the diaphragms in the first diaphragm unit, and a second grid is provided between the inner surfaces of the first part and the second part in the second diaphragm unit. The thickness of the first grid is greater than the thickness of the second grid.

[0013] In this solution, by adopting the above method, the water in the second diaphragm unit of the raw water in Technical Solution 1 is accelerated again after entering the first diaphragm unit, and the water in the first diaphragm unit of the raw water in Technical Solution 2 is accelerated again after entering the second diaphragm unit, further increasing the water flow velocity in the raw water channel, avoiding too low water flow velocity at the end of the raw water channel leading to the deposition of pollutants, and avoiding the increase in pollutant concentration resulting in an insignificant improvement in the filtration performance and service life of the membrane element.

[0014] Preferably, the collecting pipe includes a first collecting pipe and a second collecting pipe with the same diameter. The first collecting pipe and the second collecting pipe are sealed and connected. The first diaphragm unit is arranged on the first collecting pipe, and the second diaphragm unit is arranged on the second collecting pipe.

[0015] In this solution, it is convenient for the first diaphragm unit and the second diaphragm unit to be spliced to form a complete membrane element.

[0016] Preferably, guide cloths are respectively provided between the outer surfaces of the first diaphragms in the first diaphragm unit;

[0017] Guide cloths are respectively provided between the outer surfaces of the first part and the second part of the second diaphragms in the second diaphragm unit.

[0018] Preferably, the length of the first diaphragm unit on the collecting pipe is 0.5 to 2 times the length of the second diaphragm unit on the collecting pipe.

[0019] Preferably, the flat-laying length of the winding body is denoted as L1, and the flat-laying length of the water inlet is denoted as L2. The ratio range of L2 / L1 is 0.1 to 0.35;

[0020] And / or, the laying length of the winding body is denoted as L1, the laying length of the water outlet is denoted as L3, and the ratio range of L3 / L1 is 0.1 to 0.25.

[0021] Preferably, the laying length of the first part is denoted as L4, the laying length of the second part is denoted as L5, and the ratio range of L5 / L4 is 0.1 to 0.5.

[0022] In this solution, adopting the above structure can not only use the combination of the second part and the first part to converge 2 strands of raw water into 1 strand of raw water, greatly improving the flow rate of the raw water, but also balance the overall utilization rate of the membrane sheets.

[0023] Preferably, the first membrane sheet in the first membrane sheet unit is one or a combination of two of a nanofiltration membrane and a reverse osmosis membrane;

[0024] And / or, the second membrane sheet in the second membrane sheet unit is one or a combination of two of a nanofiltration membrane and a reverse osmosis membrane.

[0025] The present invention also provides a filter, and this filter includes the membrane element as described above.

[0026] The positive and progressive effects of the present invention are as follows: Whether it is Technical Solution 1 or Technical Solution 2, the second membrane sheet unit is provided to accelerate the raw water inside, which can compensate for the speed loss generated when the raw water turns and avoid the too low speed at the end of the raw water; and the winding body enters water from the lower end surface and discharges water from the upper end surface, enabling the raw water to present a "U"-shaped flow pattern in the first membrane sheet unit and the second membrane sheet unit. The raw water is in a side-flow state as a whole in the membrane element, reducing the width of the raw water flow channel in the membrane element and increasing the raw water flow rate on the surface of the membrane sheet. Furthermore, it can alleviate the concentration polarization phenomenon on the surface of the membrane sheet, slow down the deposition speed and deposition amount of pollutants, and improve the filtration performance and service life of the membrane element. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the winding body before winding in Technical Solution 1 of the embodiment of the present invention. Figure 2 It is a schematic structural diagram of the winding body before winding in Technical Solution 2 of the embodiment of the present invention

[0028] Figure 3 It is a schematic structural diagram of the first membrane sheet in the embodiment of the present invention.

[0029] Figure 4 It is a schematic structural diagram of the second membrane sheet in the embodiment of the present invention.

[0030] Figure 5 It is a schematic structural diagram of the first membrane sheet unit in the embodiment of the present invention.

[0031] Figure 6Structural schematic diagram of the second diaphragm unit of the embodiment of the present invention.

[0032] Figure 7 Structural schematic diagram of the wound body after winding according to the first technical solution of the embodiment of the present invention.

[0033] Figure 8 Structural schematic diagram of the wound body after winding according to the second technical solution of the embodiment of the present invention.

[0034] Figure 9 Structural schematic of the membrane element in the comparative example of the present invention Figure 1 。

[0035] Figure 10 Structural schematic of the membrane element in the comparative example of the present invention Figure 2 。

[0036] Explanation of reference numerals:

[0037] Water collecting pipe 100

[0038] First water collecting pipe 110

[0039] Second water collecting pipe 120

[0040] Water collecting hole 130

[0041] First diaphragm unit 200

[0042] First diaphragm 210

[0043] First grid 220

[0044] First opening 230

[0045] Second diaphragm unit 300

[0046] Second diaphragm 310

[0047] First part 311

[0048] Second part 312

[0049] Second grid 320

[0050] Second opening 330

[0051] Water inlet 400

[0052] Water outlet 500

[0053] Flow guiding cloth 600

[0054] Sealant 700 Detailed implementation manners

[0055] The present invention will be further described below by way of embodiments, but the present invention is not limited to the scope of the embodiments described herein.

[0056] As Figure 1 - 8 shown, this embodiment provides a membrane element, which includes a water collecting pipe 100. Water collecting holes 130 are formed on the pipe wall of the water collecting pipe 100 to collect purified water. A first membrane sheet 210 unit 200 and a second membrane sheet 310 unit 300 are arranged side by side and wound around the water collecting pipe 100. The end faces of the first membrane sheet 210 unit 200 and the second membrane sheet 310 unit 300 adjacent to each other are partially sealed by a sealant 700 to form a first opening 230. The end faces of the second membrane sheet 310 unit 300 and the first membrane sheet 210 unit 200 adjacent to each other are partially sealed by a sealant 700 to form a second opening 330. The first opening 230 is aligned with the second opening 330 and is in sealed communication with the second opening 330. The first membrane sheet 210 unit 200 is arranged on a first water collecting pipe 110, and the second membrane sheet 310 unit 300 is arranged on a second water collecting pipe 120. There are two technical solutions for the winding body formed by the first membrane sheet 210 unit 200 and the second membrane sheet 310 unit 300.

[0057] As Figure 1 shown, Technical Solution 1: The first membrane sheet 210 unit 200 is arranged above the second membrane sheet 310 unit 300. An inlet 400 is formed on the bottom end face of the second membrane sheet 310 unit 300 near the outer wall surface of the water collecting pipe 100. An outlet 500 is arranged on the top end face of the first membrane sheet 210 unit 200 near the outer wall surface of the water collecting pipe 100. The inlet 400 is communicated with the first opening 230 and the second opening 330 and then is communicated with the outlet 500. The first opening 230 and the second opening 330 are arranged away from the outer wall surface of the water collecting pipe 100. The upper side of the first membrane sheet 210 adjacent to the water collecting pipe 100 is partially sealed by a sealant 700 and the outlet 500 is reserved. The part of the lower side away from the water collecting pipe 100 is sealed and the first opening 230 is reserved. The side flush with the water collecting pipe 100 is completely sealed with a tape. The upper side of the second membrane sheet 310 adjacent to the water collecting pipe 100 is partially sealed by a sealant 700 and the second opening 330 is reserved. The part of the lower side close to the water collecting pipe 100 is sealed and the inlet 400 is reserved. The side flush with the water collecting pipe 100 is completely sealed with a tape.

[0058] Among them, as Figure 3 - 4 shown, the first membrane sheet 210 unit 200 includes a plurality of first membrane sheets 210 stacked in parallel in sequence, and each first membrane sheet 210 is equally divided and folded. A first raw water flow channel is formed between the inner surfaces of the first membrane sheets 210. The side edges of adjacent first membrane sheets 210 away from the water collecting pipe 100 and parallel to the water collecting pipe 100 are sealed and connected to each other to form a first purified water channel between the outer surfaces of adjacent first membrane sheets 210.

[0059] As Figure 5 - 6 shown, the second diaphragm 310 unit 300 includes a plurality of membrane groups stacked in parallel in sequence. Each membrane group includes two second diaphragms 310. The second diaphragm 310 is bent to form a first part 311 and a second part 312 connected in sequence. The length of the first part 311 is greater than that of the second part 312. A second raw water channel is formed between the inner surfaces of the first part 311 and the second part 312. The side edges of adjacent second diaphragms 310 away from the water collecting pipe 100 and parallel to the water collecting pipe 100 are hermetically connected to form a second purified water channel between the outer surfaces of the first parts 311 and the second parts 312 respectively.

[0060] The total number of the second diaphragms 310 in each membrane group in the second diaphragm 310 unit 300 can be any number of pages from 2 to 20, and there is no requirement for odd or even numbers. Among them, 2 pages of the second diaphragms 310 can form 1 step acceleration, 3 pages as a unit is 2 step accelerations, and so on. Figure 5 In each membrane group, there are 2 diaphragms and 1 step acceleration. By means of the form of long and short diaphragms, the fluid flow velocity on the surface of the second diaphragm 310 is further increased. In some embodiments, by designing the number of steps in combination with the performance and attenuation of the diaphragm, the utilization rate of each part of the second diaphragm 310 can be made more uniform. At the same time, the problem that the flow velocity in the latter section is severely reduced due to the "U"-shaped water channel structure is also alleviated. Further, the concentration polarization phenomenon on the surface of the diaphragm is alleviated, the deposition speed and deposition amount of pollutants are slowed down, and the filtration performance and service life of the membrane element are improved.

[0061] As Figure 2 shown, the difference between the second technical solution and the first technical solution is that: the first diaphragm 210 unit 200 is arranged below the second diaphragm 310 unit 300. An inlet 400 is opened on the bottom end surface of the second diaphragm 310 unit 300 at the outer wall surface away from the water collecting pipe 100. An outlet 500 is arranged on the top end surface of the first diaphragm 210 unit 200 at the outer wall surface away from the water collecting pipe 100. The inlet 400 is communicated with the first opening 230 and the second opening 330 and then communicated with the outlet 500. The first opening 230 and the second opening 330 are arranged close to the outer wall surface of the water collecting pipe 100. The lower side edge of the first diaphragm 210 adjacent to the water collecting pipe 100 is partially sealed by a sealant 700 to reserve the inlet 400. Among them, the part of the upper side edge close to the water collecting pipe 100 is sealed to reserve the first opening 230, and the side edge flush with the water collecting pipe 100 is completely sealed with a tape. The lower side edge of the second diaphragm 310 adjacent to the water collecting pipe 100 is partially sealed by a sealant 700 to reserve the second opening 330. Among them, the part of the lower side edge away from the water collecting pipe 100 is sealed to reserve the outlet 500, and the side edge flush with the water collecting pipe 100 is completely sealed with a tape.

[0062] In this embodiment, the lengths of the first part 311 and the second part 312 formed by folding the second diaphragm 310 of the second diaphragm 310 unit 300 are different, which can gradually form an accelerating flow channel for the raw water in the direction away from the second part 312, avoid the velocity loss generated when the raw water turns, and prevent the velocity of the end of the raw water from being too low, thus avoiding the serious problem of pollutant deposition. On the one hand, the second diaphragm 310 unit 300 can converge two strands of raw water into one strand of raw water, doubling the fluid flow velocity. Each time the raw water passes through a step, it can obtain a double speed increase, and finally obtain a multi-fold accelerated outflow, that is, it improves the surface flow velocity and balances the overall utilization rate of the diaphragm. After the raw water enters the raw water channel from the water inlet 400 near the outer wall surface of the water collecting pipe 100, it flows along the inner surfaces of the first diaphragm 210 and the second diaphragm 310. The purified water passes through the first diaphragm 210 and the second diaphragm 310 and then flows along the outer surface to the outer surface of the water collecting pipe 100, and finally enters the water collecting pipe 100 through the water collecting holes 130 and is collected.

[0063] The first diaphragm 210 unit 200 and the second diaphragm 310 unit 300 and the water collecting pipe 100 form a winding body. The raw water enters the raw water flow channel from the water inlet 400 at one end of the winding body, passes through the first opening 230 and the second opening 330, and finally forms concentrated water and flows out at the water outlet 500. Whether it is Technical Solution 1 or Technical Solution 2, a second diaphragm 310 unit 300 capable of accelerating the raw water is provided to accelerate the internal raw water, and a "U"-shaped water path can be formed in the first diaphragm 210 unit 200 and the second diaphragm 310 unit 300. The winding body enters water from the lower end surface and discharges water from the upper end surface, enabling the fluid to present an "L"-shaped water inlet mode. The overall raw water is in a side flow state, reducing the width of the raw water flow channel of the membrane element and increasing the surface fluid flow velocity of the diaphragm. Thereby, the concentration polarization phenomenon on the diaphragm surface can be alleviated, the deposition rate and deposition amount of pollutants can be slowed down, and the filtration performance and service life of the membrane element can be improved.

[0064] The number of diaphragm pages in the first diaphragm 210 unit 200 and the second diaphragm 310 unit 300 does not have to be the same, but the final diameters need to be the same.

[0065] A first grid 220 is provided between the inner surfaces of the diaphragms in the first diaphragm 210 unit 200, and a second grid 320 is provided between the inner surfaces of the first part 311 and the second part 312 in the second diaphragm 310 unit 300. The thickness of the first grid 220 is greater than that of the second grid 320, such that the raw water from the second diaphragm 310 unit 300 in Technical Solution 1 is accelerated again after entering the first diaphragm 210 unit 200, and the raw water from the first diaphragm 210 unit 200 in Technical Solution 2 is accelerated again after entering the second diaphragm 310 unit 300, further increasing the water flow velocity in the raw water channel, avoiding the deposition of pollutants due to too low water flow velocity at the end of the raw water channel, and avoiding the obvious improvement of the filtration performance and service life of the membrane element due to the increase in the concentration of pollutants. Specifically, the thickness of the first grid 220 is 0.43 mm, and the thickness of the second grid 320 is 0.33 mm.

[0066] The collecting pipe 100 is a first collecting pipe 110 and a second collecting pipe 120 with the same diameter. The first collecting pipe 110 and the second collecting pipe 120 are hermetically connected. The first diaphragm 210 unit 200 is arranged on the first collecting pipe 110, and the second diaphragm 310 unit 300 is arranged on the second collecting pipe 120, facilitating the first diaphragm 210 unit 200 and the second diaphragm 310 unit 300 to be spliced to form a complete membrane element. During assembly, first wind the first diaphragm 210 unit 200 around the first collecting pipe 110, wind the second diaphragm 310 unit 300 around the second collecting pipe 120, and then dock the first collecting pipe 110 and the second collecting pipe 120 to facilitate the splicing of the first diaphragm 210 unit 200 and the second diaphragm 310 unit 300. In particular, the first diaphragm 210 unit 200 and the second diaphragm 310 unit 300 are partially sealed by a sealant 700, and by applying a preset glue at a set position, it is convenient to align and position the first inlet and the second inlet.

[0067] In some embodiments, the collecting pipe 100 can be formed by snap-fitting two identical collecting pipe 100 components, which is convenient for industrial application.

[0068] Flow guiding cloths 600 are respectively provided between the outer surfaces of the first diaphragms 210 in the first diaphragm 210 units 200. Flow guiding cloths 600 are respectively provided between the outer surfaces of the first part 311 and the second part 312 of the second diaphragms 310 in the second diaphragm 310 units 300. By arranging the flow guiding cloths 600 on the outer surfaces of the first diaphragm 210 and the second diaphragm 310 to guide the purified water passing through the diaphragms, glue is coated on the outer surfaces of the first diaphragm 210 and the second diaphragm 310 to fix the flow guiding cloths 600 on the diaphragms.

[0069] In this embodiment, the length of the first diaphragm unit 210 on the water collecting pipe 100 is 1 times the length of the second diaphragm unit 310 on the water collecting pipe 100.

[0070] In other embodiments, the length of the first diaphragm unit 210 on the water collecting pipe 100 is any value in the range of 0.5 to 2 times the length of the second diaphragm unit 310 on the water collecting pipe 100.

[0071] In this embodiment, as Figure 1 - 2 shown, the laying length of the winding body is denoted as L1, and the laying length of the water inlet 400 is denoted as L2. The ratio of L2 / L1 is 0.2. On the one hand, it can ensure that the size of the water inlet 400 is large enough to ensure a small water inlet resistance and avoid risks such as blockage of the water inlet 400 by pollutants. On the other hand, it can ensure that most of the fluid on the surface of the diaphragm in the water inlet flow channel is in a side flow state, enabling most of the raw water to flow at a high speed. In addition, the size of the water inlet 400 must be smaller than the length of the second part 312 of the second diaphragm 310 so that the raw water can obtain an acceleration effect.

[0072] In other embodiments, the laying length of the winding body is denoted as L1, and the laying length of the water inlet 400 is denoted as L2. The ratio of L2 / L1 can also be any value in the range of 0.1 to 0.35.

[0073] In this embodiment, as Figure 1 - 2 shown, the laying length of the winding body is denoted as L1, and the laying length of the water outlet 500 is denoted as L3. The ratio of L3 / L1 is 0.15. On the one hand, it can ensure that the size of the water outlet 500 is large enough to ensure a small water outlet resistance and avoid risks such as blockage of the water outlet 500 by pollutants. On the other hand, it ensures that the raw water is in a side flow state on the surface of the diaphragm, enabling most of the raw water to flow at a high speed.

[0074] In other embodiments, the laying length of the winding body is denoted as L1, and the laying length of the water outlet 500 is denoted as L3. The ratio of L3 / L1 can also be any value in the range of 0.1 to 0.25.

[0075] In this embodiment, as Figure 5 shown, the laying length of the first part 311 is denoted as L4, and the laying length of the second part 312 is denoted as L5. The ratio range of L5 / L4 is 0.3. It can not only use the second part 312 in combination with the first part 311 to converge two streams of raw water into one stream of raw water, greatly increasing the flow rate of the raw water, but also balance the overall utilization rate of the diaphragm.

[0076] In other embodiments, the laying length of the first part 311 is denoted as L4, and the laying length of the second part 312 is denoted as L5. The ratio of L5 / L4 can also be any value in the range of 0.1 to 0.5.

[0077] By sharing a raw water inlet channel for the nanofiltration membrane sheet and the reverse osmosis membrane sheet, the attenuation of the service life of the reverse osmosis membrane sheet can be slowed down, so that the service lives of the nanofiltration membrane sheet and the reverse osmosis membrane sheet tend to be the same, thereby extending the service life of the entire membrane element. In this embodiment, the first membrane sheet 210 in the first membrane sheet unit 200 is a combination of a nanofiltration membrane and a nanofiltration membrane, or a combination of a nanofiltration membrane and a reverse osmosis membrane, or a combination of a reverse osmosis membrane and a reverse osmosis membrane. The second membrane sheet 310 in the second membrane sheet unit 300 is a combination of a nanofiltration membrane and a nanofiltration membrane, or a combination of a nanofiltration membrane and a reverse osmosis membrane, or a combination of a reverse osmosis membrane and a reverse osmosis membrane. By adjusting the ratio of the nanofiltration and reverse osmosis membrane sheets, the desalination rate of the nanofiltration membrane element can be adjusted. Opposing the nanofiltration membrane and the reverse osmosis membrane sheet can effectively alleviate the pollution on the surface of the reverse osmosis membrane sheet, greatly increase the range of mineral retention, and improve the performance and service life of the reverse osmosis membrane sheet.

[0078] This embodiment also provides a filter, which includes the membrane element as described above.

[0079] Comparative example

[0080] The membrane element assembly of this comparative example includes a water collecting pipe and a filter membrane group. A water collecting hole 130 is formed on the side wall of the water collecting pipe, and a purified water outlet communicating with the inner cavity of the water collecting pipe is provided at the upper end of the water collecting pipe.

[0081] As Figure 9 shown, the filter membrane group includes a plurality of membrane sheets stacked in parallel; the opening directions of each membrane sheet after folding are the same, and a raw water channel is formed between two opposite smooth surfaces formed after each membrane sheet is folded. The side edges of two adjacent membrane sheets are hermetically connected to form a purified water channel between the outer surfaces of two adjacent membrane sheets. The folded membrane sheet is fixedly connected to the outer wall surface of the water collecting pipe at the folding position, and a plurality of membrane sheets are sequentially arranged at intervals along the circumferential winding direction of the water collecting pipe to form a winding body.

[0082] The filter membrane group further includes a plurality of guide cloths 600. Each guide cloth 600 is arranged in the purified water channel and is inserted between the outer surfaces of two adjacent and adhered membrane sheets one by one. The first guide cloth 600 is attached to the outer side surface of the first membrane sheet.

[0083] The filter membrane group further includes a plurality of grids. Each grid is arranged in the raw water channel and is inserted between two opposite inner surfaces formed after each membrane sheet is folded one by one.

[0084] The membrane element assembly further includes a tape arranged circumferentially along the outer peripheral surface of the winding body.

[0085] No water passing holes are formed on the surface of the tape on the outer surface of the winding body, that is, the outer peripheral surface of the winding body is closed; as Figure 10As shown in the figure, raw water enters from the raw water inlet at one end of the wound body, flows through the raw water channels between the inner surfaces of two adjacent single diaphragms, forms concentrated water at the other end of the wound body and flows out. Its specific flow path is short, only the width of the wound body. The purified water is generated from the purified water channels between the outer surfaces of two adjacent single diaphragms and flows into the collecting pipe. Then it flows into the inner cavity of the collecting pipe through the water collecting holes 130 on the side wall of the collecting pipe, and finally flows out through the purified water outlet at the upper end of the collecting pipe.

[0086] The following table shows the comparison of the effect data of the membrane elements in this embodiment and the comparative example:

[0087] Initial flux Flux after 8000L This embodiment: Technical solution 1 2.48L / min 2.29L / min This embodiment: Technical solution 2 2.44L / min 2.15L / min Comparative example 2.35L / min 1.98L / min

[0088] Under the same flow rate, compared with the membrane element of the comparative example, the membrane element of this embodiment has a higher initial flux, a higher flux after 8000L, and a longer service life. Further, compared with the second technical solution of Embodiment 1, the first technical solution of this embodiment has a higher initial flux and a higher flux after 8000L.

[0089] For the membrane element of the first technical solution of this embodiment, the flux decay after the treatment volume reaches 8000L is 0.19L / min, and the decay rate is 7.7%. The specific calculation process is 0.19 / 2.48*100% = 7.7%. For the membrane element of the second technical solution of this embodiment, the flux decay after the treatment volume reaches 8000L is 0.29L / min, and the decay rate is 11.9%. The specific calculation process is 0.29 / 2.44*100% = 11.9%. For the membrane element of the comparative example, the flux decay after the treatment volume reaches 8000L is 0.37L / min, and the decay rate is 15.7%. The specific calculation process is 0.37 / 2.35*100% = 15.7%. Therefore, compared with the membrane element of the second technical solution of this embodiment, the decay of the membrane element of the first technical solution of this embodiment is reduced by 4.2%. The specific calculation process is 11.9% - 7.7% = 4.2%. Compared with the membrane element of the comparative example, the decay of the membrane element of the first technical solution of this embodiment is reduced by 4%. The specific calculation process is 15.7% - 7.7% = 8%.

[0090] The above comparative test analysis shows that the earlier the increase in the raw water flow rate inside the membrane element, the better, because the flow rate is continuously decaying. Therefore, setting the water inlet 400 on the second diaphragm 310 unit 300 will give the raw water a higher starting point, thereby increasing the average flow rate of the raw water.

[0091] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A membrane element, the membrane element includes a water collecting pipe, and water collecting holes are formed on the pipe wall of the water collecting pipe to collect purified water, and it is characterized in that, The water collecting pipe is provided with a first diaphragm unit and a second diaphragm unit which are wound side by side. The end faces of the first diaphragm unit and the second diaphragm unit adjacent to each other are partially sealed with sealant to form a first opening. The end faces of the second diaphragm unit and the first diaphragm unit adjacent to each other are partially sealed with sealant to form a second opening. The first opening is aligned with the second opening and is hermetically connected to the second opening. There are two technical solutions for the winding body formed by the first diaphragm unit and the second diaphragm unit: Technical solution 1: The first diaphragm unit is arranged above the water collecting pipe, and the second diaphragm unit is arranged below the water collecting pipe. An inlet is formed on the bottom end face of the second diaphragm unit near the outer wall surface of the water collecting pipe. An outlet is arranged on the top end face of the first diaphragm unit near the outer wall surface of the water collecting pipe. The inlet is connected to the outlet after connecting the first opening and the second opening, and the first opening and the second opening are arranged away from the outer wall surface of the water collecting pipe. Technical solution 2: The first diaphragm unit is arranged below the water collecting pipe, and the second diaphragm unit is arranged above the water collecting pipe. An inlet is formed on the bottom end face of the second diaphragm unit away from the outer wall surface of the water collecting pipe. An outlet is arranged on the top end face of the first diaphragm unit away from the outer wall surface of the water collecting pipe. The inlet is connected to the outlet after connecting the first opening and the second opening, and the first opening and the second opening are arranged near the outer wall surface of the water collecting pipe. Among them, the first diaphragm unit includes a plurality of first diaphragms stacked in parallel in sequence, and each of the first diaphragms is equally divided and folded. A first raw water flow channel is formed between the inner surfaces of the first diaphragms. The sides of adjacent first diaphragms away from the water collecting pipe and parallel to the water collecting pipe are hermetically connected to form a first purified water channel between the outer surfaces of adjacent first diaphragms. The second diaphragm unit includes a plurality of membrane groups stacked in parallel in sequence. Each membrane group includes two second diaphragms. The second diaphragm is bent to form a first part and a second part connected in sequence, and the length of the first part is greater than the length of the second part. A second raw water channel is formed between the inner surfaces of the first part and the second part. The sides of adjacent second diaphragms away from the water collecting pipe and parallel to the water collecting pipe are hermetically connected to form a second purified water channel between the outer surfaces of each first part and the second part.

2. The membrane element according to claim 1, characterized in that, A first grid is arranged between the inner surfaces of the diaphragms in the first diaphragm unit, and a second grid is arranged between the inner surfaces of the first part and the second part in the second diaphragm unit. The thickness of the first grid is greater than the thickness of the second grid.

3. The membrane element according to claim 1, wherein The water collecting pipe includes a first water collecting pipe and a second water collecting pipe with the same diameter. The first water collecting pipe and the second water collecting pipe are hermetically connected. The first diaphragm unit is arranged on the first water collecting pipe, and the second diaphragm unit is arranged on the second water collecting pipe.

4. The membrane element according to claim 1, characterized in that, A flow guiding cloth is provided one by one between the outer surfaces of the first diaphragms of the first diaphragm unit. A flow guiding cloth is provided one by one between the outer surfaces of the first part and the second part of the second diaphragm of the second diaphragm unit.

5. The membrane element according to claim 1, characterized in that, The length of the first diaphragm unit on the water collecting pipe is 0.5 to 2 times the length of the second diaphragm unit on the water collecting pipe.

6. The membrane element according to claim 1, characterized in that, The laying length of the winding body is denoted as L1, the laying length of the water inlet is denoted as L2, and the ratio range of L2 / L1 is 0.1 to 0.35; And / or, the laying length of the winding body is denoted as L1, the laying length of the water outlet is denoted as L3, and the ratio range of L3 / L1 is 0.1 to 0.

25.

7. The membrane element according to claim 1, wherein The laying length of the first part is denoted as L4, the laying length of the second part is denoted as L5, and the ratio range of L5 / L4 is 0.1 to 0.

5.

8. The membrane element according to claim 1, characterized in that, The first diaphragm in the first diaphragm unit is one or a combination of two of a nanofiltration membrane and a reverse osmosis membrane; And / or, the second diaphragm in the second diaphragm unit is one or a combination of two of a nanofiltration membrane and a reverse osmosis membrane.

9. A filter, characterized in that, It includes the membrane element according to any one of claims 1-8.

Images