Immersed reverse osmosis and nanofiltration membrane element

Abstract

The immersed reverse osmosis and nanofiltration membrane element comprises a membrane group packaged in a membrane shell, the membrane group comprises a plurality of groups of membranes, one ends of the membranes are fixed on a central pipe, the other ends of the membranes swing freely, each membrane is of a double-layer structure, only one side of each membrane is provided with an opening, the opening side is communicated with the central pipe, a water inlet channel is formed between every two adjacent groups of membranes, and a water outlet channel is formed between every two adjacent groups of membranes. One end of the isolation plate is fixed on the central pipe, and the other end of the isolation plate freely swings. Due to the structure that one end of each membrane element freely swings, a gap of a water inlet channel between two adjacent groups of membranes is large, and blockage is not easy to generate; according to the structure that one end of the isolation plate between every two adjacent groups of diaphragms freely swings, pollutants are difficult to stay on the surfaces of the diaphragms and are difficult to block between the diaphragms due to the polish-brush effect of the isolation plates and the diaphragms, so that the tendency of blocking and scaling is very low, and the structure is easy to chemically clean and can ensure that the device stably runs for a long time.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial water treatment, and in particular relates to an immersed reverse osmosis and nanofiltration membrane element. Background Art

[0002] Metallurgy, electric power, and chemical industry enterprises are major industrial water consumers. With the increasing scarcity of water resources and the improvement of national environmental protection requirements, the cost of water accounts for an increasingly larger proportion of the operating costs of production enterprises. Under limited conditions, optimizing and improving the efficiency of water resource utilization, achieving industrial water conservation and resource treatment of public wastewater, and resource utilization after deep treatment of urban sewage treatment plants after biochemical treatment have become inevitable choices.

[0003] Although wastewater can meet the discharge standards after biochemical treatment, it is still far from meeting the standards for industrial water and is difficult to reuse directly. Wastewater needs further deep treatment, and membrane separation is generally used, including reverse osmosis, nanofiltration, electrodialysis, etc., to remove pollutants such as salt, organic matter, and hardness. However, the residual COD, ammonia nitrogen, hardness, and salt content of wastewater, especially industrial wastewater, after biochemical treatment are relatively high, which cannot meet the water inlet requirements of membrane elements. After biochemical treatment, Fenton, Fenton-like, ozone, wet oxidation, evaporation and other special treatment methods currently known will greatly increase the treatment cost, and the salt content will increase after treatment, and the difficulty of membrane treatment is still not small. If the wastewater enters the membrane element directly after biochemical treatment, the biological contamination inside and outside the membrane system cannot be controlled by the action of bactericides. In addition, there is a kind of "sputum-like" adhesive pollutant in the wastewater, which will adhere tightly to the membrane surface in the narrow water passage of the membrane element and is very difficult to remove by chemical cleaning. It is basically impossible to sterilize and resist bacteria with traditional membrane element materials. Moreover, due to the high COD and ammonia nitrogen content in wastewater, the growth of microorganisms is inevitable. Even if the microorganisms are killed, the cells of the microorganisms will be dissolved and become nutrients for the microorganisms. The cell-dissolved substances will combine with adhesive substances to become "sticky" substances that adhere to the membrane surface more and more. However, the traditional membrane element structure is difficult to clean by flushing due to its narrow water flow channel.

[0004] In view of the above situation, the present invention provides a membrane element with a completely new concept to solve the above problems and achieve the effect of non-clogging and easy cleaning of the membrane element during deep treatment of wastewater. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides an immersed reverse osmosis and nanofiltration membrane element.

[0006] The object of the present invention is achieved in the following manner: An immersed reverse osmosis and nanofiltration membrane element includes a membrane group encapsulated in a membrane shell, the membrane group includes multiple groups of membranes with one end fixed to a central tube and the other end swinging freely, the membrane is a double-layer structure with only one side open, and the open side is connected to the central tube, a water inlet channel is formed between two adjacent groups of membranes, an isolation plate is arranged in the water inlet channel, one end of the isolation plate is fixed to the central tube, and the other end swings freely.

[0007] The width of the water inlet channel is 3±0.5mm.

[0008] A bottom cover plate, a lower baffle plate, a middle baffle plate, an upper baffle plate and a top cover plate are sequentially arranged in the membrane shell from bottom to top. Two adjacent plates and the membrane shell sequentially form a lower concentrated water chamber, a membrane group chamber, an upper concentrated water chamber and a fresh water chamber. The sides of the lower concentrated water chamber, the upper concentrated water chamber and the fresh water chamber are respectively provided with a lower concentrated water inlet, an upper concentrated water inlet and a fresh water inlet. A sampling port communicated with the fresh water chamber is arranged on the top cover plate. The diaphragm group is located in the membrane group chamber. The upper end of the central tube of the diaphragm group passes through the middle baffle plate and the upper baffle plate and is fixed to the two. The lower end of the central tube is closed and fixed to the lower baffle plate. The upper baffle plate is fixedly connected to the membrane shell. The lower baffle plate and the middle baffle plate are not fixed to the membrane shell. The lower baffle plate and the middle baffle plate are opened on the area outside the fixed position of the central tube, and the opening rate is greater than 30%.

[0009] The bottom cover plate, the top cover plate and the membrane shell are detachably connected.

[0010] The lower part of each diaphragm of the diaphragm group maintains a distance of 20-50mm from the lower partition.

[0011] A partition net is arranged inside the double-layer diaphragm.

[0012] The separator is a corrugated board or a corrugated board with vertical stripes.

[0013] The materials of the partition net and the isolation board are all rigid polymer organic materials.

[0014] A plurality of groups of submerged reverse osmosis and nanofiltration membrane elements are connected in series, the fresh water inlets of any two adjacent membrane elements are connected to each other, the lower concentrate water inlets of any two adjacent membrane elements are connected to each other or the upper concentrate water inlets are connected to each other, one of the upper and lower concentrate water inlets of the first membrane element is connected to water inlet and / or air inlet, and one of the upper and lower concentrate water inlets of the terminal membrane element is connected to drainage.

[0015] The membrane element series groups are connected in parallel to form reverse osmosis and nanofiltration devices with supporting pipelines, valves, instruments and frames.

[0016] Compared with the prior art, the present invention has the following advantages: 1. The water inlet channel between the membranes in the membrane group is wider and has a large pollutant holding capacity. It can operate normally when the suspended solids in the inlet water are less than 5 mg / L and the SDI is greater than 5. The applicable range is much wider than the existing membrane elements with suspended solids in the inlet water less than 1 mg / L and SDI less than 3.

[0017] 2. The membrane element uses an open diaphragm structure with one end fixed and the other end freely swinging. The isolation plate between the diaphragms is also an open structure with one end freely swinging. The abrasive effect of the isolation plate and the diaphragm makes it difficult for pollutants to stay on the surface of the diaphragm and difficult to be blocked between the diaphragms, making the tendency of clogging and scaling very low. In addition, this structure is easy to chemically clean, ensuring stable and long-term operation of the device.

[0018] 3. It is allowed to introduce pulse compressed air when the reverse osmosis and nanofiltration devices are running, flushing and cleaning, so that the turbulence of water between the membrane elements increases, the pollutants are flushed out of the device in time, and the flushing and cleaning effects are enhanced.

[0019] 4. It is suitable for deep treatment and reuse of wastewater where high organic matter, hardness and adhesion remain after biochemical and physicochemical treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural diagram of the diaphragm group.

[0021] Figure 2 It is a structural schematic diagram of the present invention.

[0022] Figure 3 It is a schematic diagram of the connection relationship between multiple groups of membrane elements.

[0023] Figure 4 This is a schematic diagram of the connection relationship between multiple groups of membrane elements. Figure 2 .

[0024] Figure 5 This is a schematic diagram of the connection relationship between multiple groups of membrane elements. Figure 3 . DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the present invention.

[0026] like Figure 1 As shown, an immersed reverse osmosis and nanofiltration membrane element includes a membrane group encapsulated in a membrane shell 1, the membrane group includes multiple groups of membranes 3 with one end fixed to a central tube 2 and the other end swinging freely, the membrane is a double-layer structure with only one side open, and the open side is connected to the central tube 2, a water inlet channel is formed between two adjacent groups of membranes, and an isolation plate 4 is arranged in the water inlet channel, one end of the isolation plate 4 is fixed to the central tube 2, and the other end swings freely.

[0027] Since one end of the diaphragm is fixed to the central tube 2 in the membrane shell and the other end swings freely, the water inlet channel of the membrane element is wider than that in the prior art. When the water inlet channel is wider, the pollution holding capacity is large and it can adapt to a wider range of water inlet conditions. It can operate normally when the suspended solids in the inlet water are less than 5 mg / L and the SDI is greater than 5.

[0028] Furthermore, the width of the water inlet channel is preferably 3±0.5 mm, which is four times the width of the 34 mil (about 0.86 mm) water inlet channel between the membranes of the reverse osmosis and nanofiltration membrane elements currently on the market. A larger water inlet channel is less likely to be clogged.

[0029] When the incoming water flows in the water inlet channel between the diaphragms 3, the free end of the isolation plate 4 and the free end of the diaphragm 3 can swing freely, and a brushing effect will be generated between the two, making it difficult for pollutants to remain on the surface of the diaphragm 3 and difficult to be blocked between the diaphragms 3, so that the tendency of clogging and scaling is very low, and this structure can more easily enhance the flushing and chemical cleaning effects.

[0030] Since the water inlet channel between the membranes is relatively wide, and considering that one end of the membrane and the isolation plate can swing freely, the diameter of the membrane element is relatively large, and three specifications of the membrane group are adopted: 8" diameter and 100" length, 10" diameter and 80" length, and 16" diameter and 40" length. In order to maintain the same design as the existing reverse osmosis and nanofiltration membrane elements on the market, the maximum recovery rate of the membrane element of the present invention and the area of ​​the membrane group are kept the same as those of the currently commonly used 8" rolled composite membrane.

[0031] like Figure 2As shown, the membrane element has the functions of desalination, concentration and separation, and is a core component. The bottom cover plate 11, the lower partition plate 5, the middle partition plate 6, the upper partition plate 7 and the top cover plate 12 are arranged in order from bottom to top in the membrane shell 1. The lower partition plate 5 and the bottom cover plate 11 form a lower concentrated water chamber 21, the lower partition plate 5 and the middle partition plate 6 form a membrane group chamber 22, the middle partition plate 6 and the upper partition plate 7 form an upper concentrated water chamber 23, and the upper partition plate 7 and the top cover plate 12 form a fresh water chamber 24. Each chamber has the functions of circulation, processing and storage. The diaphragm group is located in the membrane group chamber 22. The upper end of the central tube 2 of the diaphragm group passes through the middle partition plate 6 and the upper partition plate 7 and is fixed to the two. The lower end of the central tube 2 is closed and fixed to the lower partition plate 5. The upper partition plate 7 is fixedly connected to the membrane shell, the lower partition plate 5 and the middle partition plate 6 are not fixed to the membrane shell, and the bottom cover plate 11 and the top cover plate 12 are detachably connected to the membrane shell 1. The fixed connection method can be adhesive, hot melt, welding, etc. according to different materials. The lower partition 5 and the middle partition 6 are opened on the area outside the fixed position of the central tube, and the opening rate is greater than 30%. The holes on the lower partition 5 and the middle partition 6 are mainly for the uniform distribution of water and / or air intake to minimize the bias flow. The lower concentrated water chamber 21, the upper concentrated water chamber 23 and the fresh water chamber 24 are respectively provided with a lower concentrated water inlet 210, an upper concentrated water inlet 230, and a fresh water inlet 240 on the side, and a sampling port 241 communicating with the fresh water chamber 24 is provided on the top cover plate 12.

[0032] The lower part of each diaphragm 3 of the diaphragm group maintains a spacing of 20-50 mm from the lower partition 5. Since one end of the diaphragm 3 swings freely, the free end will sag under the action of gravity, and the lower partition 5 gives the free end of the diaphragm 3 a certain support force.

[0033] In order to prevent the double-layer membrane from sticking together, a partition is arranged inside the double-layer membrane 3. The partition is made of a high molecular organic material with good rigidity and toughness, such as high-density polyethylene, polypropylene, polystyrene, polycarbonate, polyurethane and the like.

[0034] The isolation plate 4 can be a corrugated plate or net with vertical stripes, or a corrugated plate or net with vertical stripes, preferably a corrugated plate with vertical stripes or a corrugated plate with vertical stripes. The isolation plate 4 is made of a high molecular organic material with good rigidity, such as polyamide, polypropylene, polystyrene, polycarbonate and the like.

[0035] Generally, a membrane element is provided with a lower concentrated water inlet 210, an upper concentrated water inlet 230, two fresh water inlets 240, and a fresh water sampling port 241. The orientation of the pipe connection of the lower concentrated water inlet 210 is 0°, and the orientation of the pipe connection of the upper concentrated water inlet 230 is 0°, 90°, 180°, or 270°. The two pipe connections of the fresh water inlet 240 are consistent with the lower concentrated water inlet 210 and the upper concentrated water inlet 230. In another case, the orientation of the pipe connection of the upper and lower concentrated water inlets and the fresh water inlet is the same, that is, the orientation of the pipe connection of the three water inlets is the same. In this case, a fresh water inlet is provided, or one of the two fresh water inlets with a different orientation from the upper and lower concentrated water inlets is closed, see Figure 4 The user can choose to use membrane elements with different connection orientations of the lower concentrate inlet 210 , the upper concentrate inlet 230 , and the fresh water inlet 240 according to actual conditions.

[0036] Method of using submerged reverse osmosis and nanofiltration membrane elements: multiple groups of submerged reverse osmosis and nanofiltration membrane elements are connected in series, the fresh water inlets of any two adjacent membrane elements are connected to each other, the lower concentrated water inlets of any two adjacent membrane elements are connected to each other or the upper concentrated water inlets are connected to each other, one of the upper and lower concentrated water inlets of the first membrane element is connected to water and / or air, and one of the upper and lower concentrated water inlets of the terminal membrane element is connected to drainage. Figure 3-5 As shown, taking the lower concentrated water inlet of the first membrane element as an example, the lower concentrated water inlet of the first membrane element is connected to the inlet (the upper fresh water inlet on the same side is closed), its upper concentrated water inlet is connected to the upper concentrated water inlet of the second membrane element, and its second fresh water inlet is connected to the fresh water inlet on the same side of the upper concentrated water inlet of the second membrane element; the lower concentrated water inlet of the second membrane element is connected to the lower concentrated water inlet of the third membrane element, and the other fresh water inlet of the second membrane element is connected to the fresh water inlet on the same side of the lower concentrated water inlet of the third membrane element; the upper concentrated water inlet of the third membrane element is connected to the upper concentrated water inlet of the fourth membrane element, and the second fresh water inlet of the third membrane element is connected to the fresh water inlet on the same side of the upper concentrated water inlet of the fourth membrane element; and so on. Depending on the amount of water and the space used, the membrane elements are arranged and combined in a variety of ways. Each series of membrane elements is then connected in parallel, and together with the matching pipes, valves, instruments, frames, etc., a reverse osmosis and nanofiltration device is formed.

[0037] When the lower concentrated water outlet of the first membrane element of the reverse osmosis and nanofiltration device is connected to water, it is also connected to a compressed air pipeline through a tee and a valve. The valve is an automatic valve or a solenoid valve. After the device has been running for a certain period of time, when the device is flushed or chemically cleaned, compressed air is introduced through the pulse opening and closing of the valve to increase the turbulence of the water flow between the diaphragms of the membrane elements, flushing the pollutants out of the device in time, and enhancing the flushing and cleaning effects.

[0038] The present invention can be applied to a process system for deep treatment and reuse of wastewater, and can also be applied to industrial water membrane purification, desalted water preparation, boiler feed water treatment, high-purity water preparation, etc.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, which should also be regarded as the scope of protection of the present invention.

Claims

1. An immersed reverse osmosis or nanofiltration membrane element, comprising a membrane assembly encapsulated in a membrane shell (1), characterized in that: The diaphragm group comprises a plurality of groups of diaphragms (3) with one end fixed to the central tube (2) and the other end swinging freely. The diaphragms are of a double-layer structure and have only one side open, and the open side is connected to the central tube (2). A water inlet channel is formed between two adjacent groups of diaphragms. An isolation plate (4) is arranged in the water inlet channel. One end of the isolation plate (4) is fixed to the central tube (2) and the other end swings freely.

2. The submerged reverse osmosis and nanofiltration membrane element according to claim 1, characterized in that: The width of the water inlet channel is 3±0.5mm.

3. The submerged reverse osmosis and nanofiltration membrane element according to claim 1, characterized in that: A bottom cover plate (11), a lower baffle plate (5), a middle baffle plate (6), an upper baffle plate (7) and a top cover plate (12) are sequentially arranged in the membrane shell (1) from bottom to top. Two adjacent plates and the membrane shell (1) sequentially form a lower concentrated water chamber (21), a membrane module chamber (22), an upper concentrated water chamber (23) and a fresh water chamber (24). The sides of the lower concentrated water chamber (21), the upper concentrated water chamber (23) and the fresh water chamber (24) are respectively provided with a lower concentrated water inlet (210), an upper concentrated water inlet (230) and a fresh water inlet (240). The top cover plate (12) A sampling port (241) communicating with the fresh water chamber (24) is arranged on the upper side. The membrane group is located in the membrane group chamber (22). The upper end of the central tube (2) of the membrane group passes through the middle baffle (6) and the upper baffle (7) and is fixed to the two. The lower end of the central tube (2) is closed and fixed to the lower baffle (5). The upper baffle (7) is fixedly connected to the membrane shell. The lower baffle (5) and the middle baffle (6) are not fixed to the membrane shell. The lower baffle (5) and the middle baffle (6) are opened on the area outside the fixed position of the central tube, and the opening rate is greater than 30%.

4. The submerged reverse osmosis and nanofiltration membrane element according to claim 3, characterized in that: The bottom cover plate (11) and the top cover plate (12) are detachably connected to the membrane shell (1).

5. The submerged reverse osmosis and nanofiltration membrane element according to claim 3, characterized in that: The lower part of each diaphragm (3) of the diaphragm group is kept at a distance of 20-50 mm from the lower partition (5).

6. The submerged reverse osmosis and nanofiltration membrane element according to claim 1, characterized in that: A partition net is arranged inside the double-layered diaphragm (3).

7. The submerged reverse osmosis and nanofiltration membrane element according to claim 1, characterized in that: The isolation board (4) is a corrugated board or a corrugated board with vertical stripes.

8. The submerged reverse osmosis and nanofiltration membrane element according to claim 1, characterized in that: The materials of the partition net and the isolation plate (4) are both rigid polymer organic materials.

9. The submerged reverse osmosis and nanofiltration membrane element according to claim 1, characterized in that: A plurality of groups of submerged reverse osmosis and nanofiltration membrane elements are connected in series, the fresh water inlets of any two adjacent membrane elements are connected to each other, the lower concentrate water inlets of any two adjacent membrane elements are connected to each other or the upper concentrate water inlets are connected to each other, one of the upper and lower concentrate water inlets of the first membrane element is connected to water inlet and / or air inlet, and one of the upper and lower concentrate water inlets of the terminal membrane element is connected to drainage.

10. The submerged reverse osmosis and nanofiltration membrane element according to claim 9, characterized in that: The membrane element series groups are connected in parallel to form reverse osmosis and nanofiltration devices with supporting pipelines, valves, instruments and frames.

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