Step concentration reverse osmosis device

Abstract

The utility model belongs to the technical field of membrane concentration, and particularly relates to a step concentration reverse osmosis device which comprises a water inlet tank, a first-section reverse osmosis membrane group, a second-section reverse osmosis membrane group, a water producing tank and a concentrated water tank, the water inlet tank is connected with the first-section reverse osmosis membrane group, the water production end of the first-section reverse osmosis membrane group is connected with the water production tank, the concentrated water end of the first-section reverse osmosis membrane group is connected with the second-section reverse osmosis membrane group, and the second-section reverse osmosis membrane group comprises a second-section first-stage reverse osmosis membrane group and a second-section second-stage reverse osmosis membrane group; the concentrated water end of the second-section first-stage reverse osmosis membrane group is connected with the concentrated water tank, the water producing end of the second-section first-stage reverse osmosis membrane group is connected with the second-section second-stage reverse osmosis membrane group, the water producing end of the second-section second-stage reverse osmosis membrane group is connected with the water producing tank, and the concentrated water end of the second-section second-stage reverse osmosis membrane group is connected with a concentrated water pipeline of the first-section reverse osmosis membrane group; through cooperative use of the first-stage reverse osmosis membrane group, the second-stage first-stage reverse osmosis membrane group and the second-stage second-stage reverse osmosis membrane group, cascade reverse osmosis treatment of high-salt-content wastewater can be realized, the water production recovery rate of the device can be improved, and the operation pressure, energy consumption and investment of the whole device can be reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of membrane concentration, and in particular relates to a reverse osmosis device for step concentration. Background Art

[0002] In recent years, in order to meet the needs of wastewater treatment in modern industrial production, reverse osmosis membrane concentration technology has been widely used in large-scale wastewater discharge or zero emission fields such as coal chemical industry, mine water, electroplating, seawater desalination, and lithium extraction from salt lakes due to its advantages of good effluent quality, stable operation, and simple operation.

[0003] Reverse osmosis membrane concentration technology is to make water molecules pass through the membrane to form fresh water by applying pressure or using concentration difference, thereby achieving material concentration, reducing concentrated water production, and reducing investment and operating costs for concentrated water evaporation. In this process, how to select membrane elements and processes to achieve high water recovery rate and low energy consumption is the focus of current research and development.

[0004] At present, for the brine membrane treatment system with a salt TDS of more than 20,000 mg / L, a two-stage concentration process of "one-stage reverse osmosis + two-stage reverse osmosis" is generally required for reduction treatment. The recovery rate of the first stage of reverse osmosis is generally 60-65%. The concentrated water after the first stage of reverse osmosis enters the second stage of reverse osmosis, which makes the influent salinity of the second stage reverse osmosis membrane system continue to increase. The influent TDS can reach more than 50,000-60,000 mg / L, resulting in the water recovery rate of the second stage of reverse osmosis often only reaching 50-55%. The total water recovery rate of the two stages is 82-82.5%, which shows that the total water recovery rate is low, and the operating pressure of the second stage reverse osmosis will be as high as 8MPa or above. It is usually necessary to use 9MPa or even 12MPa high-pressure membranes. The operating pressure is high, the energy consumption is high, and the pressure level requirements of the membrane shell, pipeline, valve and other equipment materials of the high-pressure equipment are also high, resulting in higher investment in equipment and materials for the high-pressure part. In order to improve the water recovery rate of the reverse osmosis system and reduce energy consumption and investment at the same time, it is extremely urgent to develop a reverse osmosis membrane concentration system with high water recovery rate and low energy consumption. Utility Model Content

[0005] In view of the above-mentioned deficiencies in the prior art, the utility model provides a reverse osmosis device for step concentration, which solves the problems of low water recovery rate, high operating pressure, high energy consumption, high operating cost and high investment in the existing two-stage reverse osmosis membrane concentration system.

[0006] To achieve the above object, the technical solution adopted by the utility model is: to provide a step-concentration reverse osmosis device, comprising a water inlet tank, a first-stage reverse osmosis membrane group, a second-stage reverse osmosis membrane group, a water production tank and a concentrated water tank arranged in sequence;

[0007] The water inlet tank is connected to a first-stage reverse osmosis membrane group, the water production end of the first-stage reverse osmosis membrane group is connected to the water production tank, the concentrated water end of the first-stage reverse osmosis membrane group is connected to the second-stage reverse osmosis membrane group, and the second-stage reverse osmosis membrane group includes a second-stage first-stage reverse osmosis membrane group and a second-stage second-stage reverse osmosis membrane group; the concentrated water end of the second-stage first-stage reverse osmosis membrane group is connected to the concentrated water tank, and its water production end is connected to the second-stage second-stage reverse osmosis membrane group, the water production end of the second-stage second-stage reverse osmosis membrane group is connected to the water production tank, and its concentrated water end is connected to the concentrated water pipeline of the first-stage reverse osmosis membrane group;

[0008] The first stage reverse osmosis membrane group includes a plurality of first high desalination rate membrane elements; the second stage primary reverse osmosis membrane group includes a plurality of low desalination rate membrane elements; the second stage secondary reverse osmosis membrane group includes a plurality of second high desalination rate membrane elements.

[0009] The beneficial effects of adopting the above technical scheme are as follows: the water inlet tank is used to store high-concentration brine, the first-stage reverse osmosis membrane group can concentrate and separate the input brine, the concentrated and separated fresh water enters the water production tank, and the first concentrated water after concentration and separation enters the second-stage first-stage reverse osmosis membrane group and the second-stage second-stage reverse osmosis membrane group, and the concentrated water is treated twice. Under the same concentration multiple, the second-stage first-stage reverse osmosis membrane group can reduce the osmotic pressure difference of high-concentration brine and reduce the operating pressure; the second-stage second-stage reverse osmosis membrane group can re-treat the second concentrated water after being treated by the second-stage first-stage reverse osmosis membrane group, which can effectively reduce the TDS content of the water produced by the second-stage first-stage reverse osmosis membrane group and ensure the water quality of the produced water; in addition, the recovery rate of the first-stage reverse osmosis membrane group is 60-65%, and the second-stage first-stage reverse osmosis membrane group is 20-30%. The recovery rate of the first-stage reverse osmosis membrane group is 65-70%, and the recovery rate of the second-stage reverse osmosis membrane group is 85-90%. By using a first-stage reverse osmosis membrane group, a second-stage first-stage reverse osmosis membrane group and a second-stage second-stage reverse osmosis membrane group to treat concentrated water, the total recovery rate of the device can reach 86.4-87.1%, which improves the water recovery rate and ensures the water quality of the device, while reducing the operating pressure of the second-stage first-stage reverse osmosis system, reducing energy consumption and operating costs; and through the coordinated use of high-density desalination membrane elements and low-density desalination membrane elements, it can meet the concentration and separation effect of the first-stage reverse osmosis module and meet the water quality requirements, without the need to use reverse osmosis membrane elements with too high a pressure level, thereby reducing operating energy consumption and operating costs.

[0010] Furthermore, a water inlet pump and a high-pressure pump are arranged in sequence between the water inlet tank and the first reverse osmosis membrane group, and a booster pump is arranged between the first reverse osmosis membrane group and the second-stage primary reverse osmosis membrane group.

[0011] The beneficial effects of adopting the above technical solution are: the water inlet pump can ensure the water inlet amount entering the first reverse osmosis membrane group from the water inlet tank, and the booster pump can provide a higher pressure to ensure that the liquid in the first reverse osmosis membrane group is smoothly transported to the second-stage primary reverse osmosis membrane group.

[0012] Furthermore, a high-pressure pump is provided between the water inlet pump and a section of the reverse osmosis membrane group, and the maximum pressure of the high-pressure pump is 9 MPa.

[0013] The beneficial effect of adopting the above technical solution is that the high-pressure pump can provide the pressure required for reverse osmosis to ensure the separation of the solvent and the solute in the concentrated brine.

[0014] Furthermore, a safety filter is arranged between the high-pressure pump and the water inlet pump.

[0015] Furthermore, the filtration accuracy of the security filter is 5-10 μm.

[0016] The beneficial effect of adopting the above technical solution is that the security filter can remove tiny impurities and particulate matter in the concentrated brine, thereby improving the efficiency and quality of the concentrated brine.

[0017] Furthermore, the low salt rejection rate membrane element is a DuPont reverse osmosis membrane.

[0018] The beneficial effects of adopting the above technical solution are: DuPont reverse osmosis membrane can effectively remove harmful substances such as dissolved salts, colloids, microorganisms and organic matter in water, and has the advantages of large flux, anti-pollution and high desalination rate. It can not only achieve a desalination rate of 70-90%, but also control the water inlet pressure within 80bar, reducing the operating pressure and operating cost of the entire concentrated water treatment.

[0019] In summary, the reverse osmosis device for step concentration provided by the utility model has the following beneficial effects:

[0020] (1) Through the coordinated use of a first-stage reverse osmosis membrane group and a second-stage reverse osmosis membrane group, the concentrated brine can be concentrated in a cascade manner, which can not only improve the water production rate of the entire reverse osmosis device, but also reduce the operating pressure, energy consumption and operating costs, and reduce investment costs.

[0021] (2) This device adopts a combination of a first high desalination rate reverse osmosis membrane element, a low desalination rate membrane element and a second high desalination rate membrane element, which can not only meet the concentration and separation effect of the reverse osmosis module and achieve the water quality requirements of the produced water, but also does not need to use a reverse osmosis membrane element with an excessively high pressure rating, thereby reducing operating energy consumption and operating costs.

[0022] (3) The two-stage first-stage reverse osmosis membrane group in this device adopts membrane elements with low desalination rate, which overcomes the problem of high pressure under the same concentration multiple (i.e. the same recovery rate) or low recovery rate under the same pressure when using traditional reverse osmosis membranes with high desalination rate. It can reduce the osmotic pressure difference on both sides of the membrane, reduce the operating pressure, and thus reduce the operating pressure and the investment cost of supporting equipment and materials.

[0023] (4) The two-stage reverse osmosis membrane group in this device is arranged in two stages. The produced water of the two-stage first-stage reverse osmosis membrane group enters the two-stage second-stage reverse osmosis membrane group for secondary treatment, which effectively avoids the problem of produced water not meeting the standards due to the use of a reverse osmosis membrane with a lower desalination rate in the two-stage first-stage reverse osmosis membrane group. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the utility model.

[0025] Among them, 1. water inlet tank; 2. first stage reverse osmosis membrane group; 21. first high desalination rate membrane element; 3. second stage reverse osmosis membrane group; 31. second stage first stage reverse osmosis membrane group; 32. low desalination rate membrane element; 33. second stage second stage reverse osmosis membrane group; 34. second high desalination rate membrane element; 4. safety filter; 5. water production tank; 6. concentrated water tank; 7. water inlet pump; 8. booster pump; 9. high pressure pump. DETAILED DESCRIPTION

[0026] The specific implementation methods of the utility model are described below to facilitate technical personnel in this technical field to understand the utility model, but it should be clear that the utility model is not limited to the scope of the specific implementation methods. For ordinary technical personnel in this technical field, as long as various changes are within the spirit and scope of the utility model defined and determined by the attached claims, these changes are obvious, and all utility model creations using the concept of the utility model are protected.

[0027] Example 1

[0028] like Figure 1 As shown, the step concentration reverse osmosis device provided by the utility model comprises a water inlet tank 1, a first-stage reverse osmosis membrane group 2, a second-stage reverse osmosis membrane group 3, a production water tank 5 and a concentrated water tank 6 which are arranged in sequence;

[0029] The water inlet tank 1 is connected to a first-stage reverse osmosis membrane group 2, the water production end of the first-stage reverse osmosis membrane group 2 is connected to a water production tank 5, the concentrated water end of the first-stage reverse osmosis membrane group 2 is connected to a second-stage reverse osmosis membrane group 3, and the second-stage reverse osmosis membrane group 3 includes a second-stage first-stage reverse osmosis membrane group 31 and a second-stage second-stage reverse osmosis membrane group 33; the concentrated water end of the second-stage first-stage reverse osmosis membrane group 31 is connected to a concentrated water tank 6, and its water production end is connected to a second-stage second-stage reverse osmosis membrane group 33, the water production end of the second-stage second-stage reverse osmosis membrane group 33 is connected to the water production tank 5, and its concentrated water end is connected to the concentrated water pipeline of the first-stage reverse osmosis membrane group 2.

[0030] When in use, the high-salinity brine stored in the water inlet tank 1 is transported to the first-stage reverse osmosis membrane group 2, and the first-stage reverse osmosis membrane group 2 performs efficient filtration and concentration to obtain the first produced water with a low TDS content, wherein TDS is the total dissolved solids, also known as the total amount of dissolved solids, and the measurement unit is milligrams per liter (mg / L), which indicates how many milligrams of solids are dissolved in 1 liter of water. The higher the TDS value, the more dissolved matter is contained in the water; at this time, the first produced water can directly enter the produced water tank 5 through the produced water end, and the first concentrated water with a higher TDS content enters the second-stage primary reverse osmosis membrane group 31, and the second-stage primary reverse osmosis membrane group 31 performs secondary treatment on the first concentrated water to obtain the second produced water and the second concentrated water. At this time, the second concentrated water can directly enter the concentrated water tank 6 through the concentrated water end to wait for subsequent treatment; in addition, when in use, the first-stage reverse osmosis The recovery rate of the membrane group 2 is 60-65%, the recovery rate of the second-stage first-stage reverse osmosis membrane group 31 is 65-70%, and the recovery rate of the second-stage second-stage reverse osmosis membrane group 33 is 85-90%. By using the first-stage reverse osmosis membrane group 2, the second-stage first-stage reverse osmosis membrane group 31 and the second-stage second-stage reverse osmosis membrane group 33 to treat concentrated water, the total recovery rate of the device can reach 86.4-87.1%, which improves the water recovery rate and ensures the water quality of the device, while reducing the operating pressure of the second-stage first-stage reverse osmosis system, reducing energy consumption and operating costs; and through the coordinated use of high-density desalination membrane elements and low-density desalination membrane elements 32, it can meet the concentration and separation effect of the first-stage reverse osmosis module and meet the water quality requirements of the produced water, and there is no need to use reverse osmosis membrane elements with too high pressure levels, so that the operating energy consumption and operating costs are reduced.

[0031] In the embodiment of the utility model, the operating pressure of the first stage reverse osmosis membrane group 2 is 4-8 MPa, the operating pressure of the second stage primary reverse osmosis membrane group 31 is 4-8 MPa, and the operating pressure of the second stage secondary reverse osmosis membrane group 33 is 4-8 MPa.

[0032] like Figure 1 As shown, a water inlet pump 7 is arranged between the water inlet tank 1 and the first stage reverse osmosis membrane group 2, and a booster pump 8 is arranged between the first stage reverse osmosis membrane group 2 and the second stage primary reverse osmosis membrane group 31; the water inlet pump 77 can increase the amount of water entering the first stage reverse osmosis membrane group 2 from the water inlet tank 1, and the booster pump 8 can provide a higher pressure to ensure that the liquid in the first stage reverse osmosis membrane group 2 is smoothly transported to the second stage primary reverse osmosis membrane group 31.

[0033] In the embodiment of the utility model, a high-pressure pump 9 is further arranged between the water inlet pump 7 and a section of the reverse osmosis membrane group 2, and the maximum pressure of the high-pressure pump 9 is 9MPa; and a security filter 4 is further arranged between the high-pressure pump 9 and the water inlet pump 7, and the filtration accuracy of the security filter 4 is 5-10μm; the high-pressure pump 9 can provide the pressure required for reverse osmosis to ensure the separation of the solvent and the solute in the concentrated brine, and the security filter 4 can remove tiny impurities and particulate matter in the concentrated brine, thereby improving the efficiency and quality of the concentrated brine.

[0034] In the embodiment of the utility model, a first-stage reverse osmosis membrane group 2 includes a plurality of first high desalination rate membrane elements 21; a second-stage first-stage reverse osmosis membrane group 31 includes a plurality of low desalination rate membrane elements 32, and the low desalination rate membrane elements 32 can be selected from DuPont reverse osmosis membrane, Veolia reverse osmosis membrane, Toray reverse osmosis membrane or Times Vonton reverse osmosis membrane, etc.; wherein, the first high desalination rate reverse osmosis membrane element 21 of the first-stage reverse osmosis membrane group 2 can efficiently filter and concentrate pollutants in concentrated brine, and its desalination rate can reach more than 97%, and can directly produce produced water that meets the water quality standard requirements, effectively ensuring the output Water quality; the low desalination rate membrane element 32 in the second-stage first-stage reverse osmosis membrane group 31 has a desalination rate of 70-90%, which can intercept most of the dissolved salts, colloids, organic matter and other substances in the high-salt concentrated water. Due to its low desalination rate, under the same concentration multiple, it can effectively reduce the concentration difference on both sides of the membrane, reduce its osmotic pressure difference, delay the occurrence of concentration polarization, and control the inlet pressure of the concentrated water within 8MPa, which is much lower than the 12MPa of the conventional ultra-high pressure membrane, reducing the operating pressure and operating cost of the entire concentrated water treatment, and improving the water recovery rate.

[0035] The membrane concentration device in this embodiment can not only achieve efficient filtration and concentration of brine, effectively reduce pollutants such as organic matter and salt in the water, and directly obtain water that meets the standards, but also control the processing operating pressure within 8MPa, thereby reducing the operating pressure, saving the investment cost of supporting equipment, and improving the water recovery rate.

[0036] Example 2

[0037] On the basis of Example 1, the two-stage primary reverse osmosis membrane group 31 in this embodiment is also connected to a two-stage secondary reverse osmosis membrane group 33, and the two-stage secondary reverse osmosis membrane group 33 includes a plurality of second high desalination rate membrane elements 34; the two-stage secondary reverse osmosis membrane group 33 can re-treat the produced water after being treated by the two-stage primary reverse osmosis membrane group 31, which can effectively reduce the TDS content of the produced water of the two-stage primary reverse osmosis membrane group 31 and improve the quality of the produced water.

[0038] In combination with Example 1, when this embodiment is in use, the concentrated brine can enter the first stage reverse osmosis membrane group 2, and the first produced water generated after concentration and filtration by the first stage reverse osmosis membrane group 2 enters the produced water tank 5 through the produced water end, and the first concentrated water generated enters the second stage first stage reverse osmosis membrane group 31 through the concentrated water end, and is further concentrated by the second stage first stage reverse osmosis membrane group 31. The second concentrated water enters the concentrated water tank 6 for subsequent treatment. By adopting a combination of the first high desalination rate reverse osmosis membrane element 21, the low desalination rate membrane element 32 and the second high desalination rate membrane element 34, it can meet the concentration and separation effect of the reverse osmosis module and achieve the produced water quality requirements, and there is no need to use reverse osmosis membrane elements with too high a pressure level, so that the operating energy consumption is reduced and the operating cost is reduced.

[0039] Example 3

[0040] Based on the examples and embodiments, this embodiment provides a concentrated brine with 100m³ of influent and a TDS content of 20000mg / L, and its specific working process is as follows:

[0041] First, the concentrated brine is transported to the first stage reverse osmosis membrane group 2 through the water inlet pump 7, and the pressure before the membrane is 5.5MPa. After being treated by the first stage reverse osmosis membrane group 2, the first produced water is 65m³, and its TDS content is about 88.7mg / L. The first produced water enters the water production tank 5 from the first stage reverse osmosis membrane group 2, and is concentrated into 35m³ of first concentrated water, and its TDS content is about 60000mg / L. The first concentrated water is mixed with the second stage reverse osmosis concentrated water to obtain 38.8m³. 3 , and is transported to the second-stage primary reverse osmosis membrane group 31 through the inter-stage booster pump 8. The pressure before the membrane of the second-stage primary reverse osmosis membrane group 31 is 7.1MPa. The first concentrated water and the second-stage secondary reverse osmosis concentrated water are further concentrated by the second-stage primary reverse osmosis membrane group 31 to obtain a second concentrated water volume of 13.6m³, and its TDS content is about 120000mg / L. The second concentrated water enters the concentrated water tank 6 for subsequent treatment, and the second produced water output of the second-stage primary reverse osmosis membrane group 31 is 25.2m³, and the TDS content is about 1100mg / L. The second produced water needs to enter the second-stage secondary reverse osmosis membrane group 33 for further treatment; the required treatment volume of this membrane group is small, and the pollutant content is low. The TDS content of the third produced water after being treated by the second-stage secondary reverse osmosis membrane group 33 is less than 20mg / L, and the second-stage secondary produced water is about 21.4m³ and the first produced water 65m3 enters the produced water tank 5, and the remaining third concentrated water flows back to the second-stage primary reverse osmosis membrane group 31 for further concentration.

[0042] After treating 100m³ of concentrated brine with a TDS of 20000mg / L in this embodiment, a total of 86.4m 3The total recovery rate of produced water and 13.6m³ of concentrated water is 86.4%, and the output of concentrated liquid is small; in addition, the maximum membrane operating pressure of this embodiment is 7.1MPa, which is greatly reduced compared with the 12MPa required by the existing ultra-high pressure membrane, and the energy consumption required for pressurization is reduced, and the cost of supporting materials such as pipes, membrane shells and high-pressure pumps 9 required for supporting equipment is reduced.

[0043] In summary, the step-concentration reverse osmosis device provided by the utility model adopts a multi-stage membrane treatment method, which can effectively reduce the concentrated water treatment pressure, reduce the operating pressure, and save the pressure resistance cost of the concentrating device. At the same time, it can also increase the concentration of the concentrated liquid, reduce the concentrated liquid output, and improve the water recovery rate and water quality.

Claims

1. A reverse osmosis device for step concentration, characterized in that: It comprises a water inlet tank (1), a first-stage reverse osmosis membrane group (2), a second-stage reverse osmosis membrane group (3), a water production tank (5) and a concentrated water tank (6) which are arranged in sequence; The water inlet tank (1) is connected to a first-stage reverse osmosis membrane group (2); the water production end of the first-stage reverse osmosis membrane group (2) is connected to a water production tank (5); the concentrated water end of the first-stage reverse osmosis membrane group (2) is connected to a second-stage reverse osmosis membrane group (3); the second-stage reverse osmosis membrane group (3) comprises a second-stage first-stage reverse osmosis membrane group (31) and a second-stage second-stage reverse osmosis membrane group (33); the concentrated water end of the second-stage first-stage reverse osmosis membrane group (31) is connected to a concentrated water tank (6); its water production end is connected to a second-stage second-stage reverse osmosis membrane group (33); the water production end of the second-stage second-stage reverse osmosis membrane group (33) is connected to the water production tank (5); and its concentrated water end is connected to the concentrated water pipeline of the first-stage reverse osmosis membrane group (2); The first stage reverse osmosis membrane group (2) comprises a plurality of first high salt rejection rate membrane elements (21); the second stage primary reverse osmosis membrane group (31) comprises a plurality of low salt rejection rate membrane elements (32); and the second stage secondary reverse osmosis membrane group (33) comprises a plurality of second high salt rejection rate membrane elements (34).

2. The reverse osmosis device for step concentration according to claim 1, characterized in that: A water inlet pump (7) is provided between the water inlet tank (1) and the first stage reverse osmosis membrane group (2), and a booster pump (8) is provided between the first stage reverse osmosis membrane group (2) and the second stage primary reverse osmosis membrane group (31).

3. The reverse osmosis device for step concentration according to claim 2, characterized in that: A high-pressure pump (9) is also provided between the water inlet pump (7) and the first reverse osmosis membrane group (2), and the maximum pressure of the high-pressure pump (9) is 9 MPa.

4. The reverse osmosis device for step concentration according to claim 3, characterized in that: A safety filter (4) is also provided between the high-pressure pump (9) and the water inlet pump (7).

5. The reverse osmosis device for step concentration according to claim 4, characterized in that: The filtration accuracy of the security filter (4) is 5-10 μm.

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