Seawater desalination device and seawater desalination method

Abstract

The invention discloses a seawater desalination device and a seawater desalination method, and relates to the technical field of seawater desalination. The seawater desalination device at least comprises a first-stage desalination system and a second-stage desalination system, wherein the first-stage desalination system is used for conveying first-stage produced water to the second-stage desalination system; the secondary desalination system comprises a second pump; a secondary reverse osmosis membrane; the flow regulation module is provided with a first inlet and a first outlet and is used for receiving secondary concentrated water; the flow adjusting module changes the flow speed of the received secondary concentrated water so as to form a pressure difference between the first inlet and the first outlet, and the secondary reverse osmosis membrane can generate working pressure according to the pressure difference; the second-stage pressure regulating module is used for receiving the other part of second-stage concentrated water output from the first outlet; the second-stage pressure regulating module changes the pressure of the first-stage produced water by regulating the flow of the received second-stage concentrated water, the second-stage reverse osmosis membrane can regulate the working pressure and / or the water yield according to the change of the pressure of the first-stage produced water, and the control flow is simple and easy to realize.

Description

Technical Field

[0001] The present application relates to the technical field of seawater desalination, and in particular to a seawater desalination device and a seawater desalination method. Background Art

[0002] The two-stage reverse osmosis desalination device has many advantages and is often used for seawater desalination. However, the working pressure of the two-stage reverse osmosis membrane of the existing two-stage reverse osmosis desalination device is all provided by the two-stage high-pressure pump, that is, the water produced by the first-stage reverse osmosis membrane and the secondary concentrated water return water converge as the secondary raw water to flow into the two-stage high-pressure pump, and the secondary raw water is pressurized by the two-stage high-pressure pump and flows into the two-stage reverse osmosis membrane. The working pressure of the two-stage reverse osmosis system is controlled by controlling the two-stage high-pressure regulating valve, and the inlet pressure of the two-stage pump and the two-stage recovery rate are guaranteed by the two-stage reflux valve and the two-stage discharge valve. However, this method requires the two-stage high-pressure regulating valve, the two-stage reflux valve and the two-stage discharge valve to be reasonably configured and comprehensively regulated to achieve, and its entire control process is relatively complex and difficult to achieve. Summary of the invention

[0003] Purpose of the invention: An embodiment of the present application provides a seawater desalination device, aiming to overcome the technical problems in the prior art that the control process is relatively complex and difficult to implement; another purpose of the embodiment of the present application is to provide a seawater desalination method.

[0004] Technical solution: A seawater desalination device described in an embodiment of the present application comprises at least a primary desalination system and a secondary desalination system, wherein the primary desalination system is used to transport primary produced water to the secondary desalination system;

[0005] The secondary desalination system comprises:

[0006] a second pump connected to the primary desalination system, for receiving the primary produced water and pressurizing the primary produced water;

[0007] A secondary reverse osmosis membrane having a second input end and a second concentrated water end, wherein the second input end is connected to the second pump and is used to receive pressurized primary produced water and convert the non-permeated primary produced water into secondary concentrated water;

[0008] a flow regulating module having a first inlet and a first outlet, wherein the first inlet is connected to the second concentrated water end and is used to receive the secondary concentrated water; the flow regulating module changes the flow rate of the received secondary concentrated water to form a pressure difference between the first inlet and the first outlet, and the secondary reverse osmosis membrane can generate a working pressure according to the pressure difference; the second pump is also connected to the first outlet and is used to receive part of the secondary concentrated water outputted by the first outlet;

[0009] A secondary pressure regulating module has a second inlet, which is connected to the first outlet and is used to receive another part of the secondary concentrated water output by the first outlet; the secondary pressure regulating module adjusts the flow rate of the received secondary concentrated water to change the pressure of the primary produced water, and the secondary reverse osmosis membrane can adjust the working pressure and / or water production according to the change in the pressure of the primary produced water.

[0010] In some embodiments, the flow regulating module includes an orifice plate having at least one through hole, and the orifice plate changes the flow rate of the received secondary concentrated water through the through hole to form a pressure difference between the first inlet and the first outlet.

[0011] In some embodiments, the cross-sectional area of ​​the orifice plate is in the range of 0.5×10 -5 m 2 -10×10 -5 m 2 .

[0012] In some embodiments, the flow regulating module includes a flow regulating valve, and the flow regulating valve changes the flow rate of the received secondary concentrated water by adjusting the opening of the flow regulating valve to form a pressure difference between the first inlet and the first outlet.

[0013] In some embodiments, the pressure difference between the first inlet and the first outlet ranges from 0.3 MPa to 0.8 MPa, and the pressure variation range of the primary produced water ranges from 0.2 MPa to 0.8 MPa.

[0014] In some embodiments, the primary desalination system comprises:

[0015] A primary reverse osmosis membrane having a first input end, a first water production end and a first concentrated water end, wherein the first water production end is connected to the second pump;

[0016] A first-stage pressure regulating module has a third inlet, the third inlet is connected to the first concentrated water end, and is used to receive the first-stage concentrated water output by the first concentrated water end; the first-stage pressure regulating module changes the pressure of the first-stage produced water by adjusting the flow rate of the received first-stage concentrated water;

[0017] The first pump is connected to the first input end and is used to increase the pressure of the water entering the first input end.

[0018] In some embodiments, the primary desalination system further comprises:

[0019] A filter module connected to the first pump;

[0020] A first pressure monitoring module, disposed between the first pump and the filter module;

[0021] The second pressure monitoring module is arranged between the first pump and the first input end.

[0022] In some embodiments, the primary pressure regulating module is a primary high-pressure regulating valve, and the secondary pressure regulating module is a secondary high-pressure regulating valve.

[0023] In some embodiments, the secondary reverse osmosis membrane further has a second water production end; the secondary pressure regulating module has a second outlet; the secondary desalination system further includes:

[0024] A three-way valve having a first connection end, a second connection end and a third connection end, wherein the first connection end is connected to the second water production end, the second connection end is connected to the second outlet, and the third connection end outputs secondary water production;

[0025] A flow monitoring module, arranged between the first connection end and the second water production end;

[0026] A check valve is arranged between the second outlet and the second connecting end.

[0027] Accordingly, a method described in the embodiment of the present application

[0028] A seawater desalination method, applied to the seawater desalination device as described above, comprising:

[0029] After the primary desalination system operates normally, when the primary produced water fills the entire secondary desalination system, controlling the second pump to start;

[0030] After the second pump is started, a pressure difference is formed between the first inlet and the first outlet, so that the secondary reverse osmosis membrane can generate a working pressure according to the pressure difference;

[0031] The flow rate of the received secondary concentrated water is adjusted by the secondary pressure regulating module to change the pressure of the primary produced water, so that the secondary reverse osmosis membrane can adjust the working pressure and / or water production according to the change of the pressure of the primary produced water.

[0032] In some embodiments, before the primary desalination system operates normally, it further includes:

[0033] When the amount of the primary produced water changes, the flow rate of the received primary concentrated water is adjusted by the primary pressure regulating module to change the pressure of the primary produced water.

[0034] In some embodiments, the flow regulating module includes an orifice plate; the working pressure of the secondary reverse osmosis membrane is calculated as follows:

[0035] P1=0.5ρ((Q1-Q2) / S0) 2 +P0

[0036] Among them, P1 is the working pressure of the secondary reverse osmosis membrane; P0 is the primary water production back pressure; Q1 is the flow rate of the second pump; Q2 is the secondary water production flow rate; S0 is the cross-sectional area of ​​the orifice plate; ρ is the liquid density.

[0037] Beneficial effect: Compared with the prior art, the desalination device and desalination method of the embodiment of the present application at least include: a primary desalination system and a secondary desalination system, the primary desalination system is used to deliver primary produced water to the secondary desalination system; the secondary desalination system includes: a second pump connected to the primary desalination system, used to receive the primary produced water and pressurize the primary produced water; a secondary reverse osmosis membrane, having a second input end and a second concentrated water end, the second input end is connected to the second pump, used to receive the pressurized primary produced water and make the non-permeated primary produced water form secondary concentrated water; a flow regulating module, having a first inlet and a first outlet, the first inlet and the second concentrated water end are connected to the second pump, and the flow regulating module is connected to the second concentrated water end. The second pump is also connected to the first outlet, and is used to receive part of the secondary concentrated water outputted from the first outlet; the secondary pressure regulating module has a second inlet, and the second inlet is connected to the first outlet, and is used to receive another part of the secondary concentrated water outputted from the first outlet; the secondary pressure regulating module adjusts the flow rate of the received secondary concentrated water to change the pressure of the primary produced water, and the secondary reverse osmosis membrane can adjust the working pressure and / or the water production according to the change of the pressure of the primary produced water. It can be seen that by setting a flow regulating module and a secondary pressure regulating module, wherein the flow regulating module forms a pressure difference by changing the flow rate of the received secondary concentrated water, so that the secondary reverse osmosis membrane can generate a working pressure according to the pressure difference, and cooperates with the secondary pressure regulating module, and adjusts the flow rate of the received secondary concentrated water through the secondary pressure regulating module to change the pressure of the primary produced water, so that the secondary reverse osmosis membrane can adjust the working pressure and / or water production according to the change of the pressure of the primary produced water, so that the secondary pump and the secondary pressure regulating module can share the adjustment of the working pressure of the secondary reverse osmosis membrane, thereby reducing the load of the secondary pump. In addition, the pressure regulation of the secondary reverse osmosis membrane can be achieved by adjusting the secondary pressure regulating module, and its control process is simple, easy to implement, and the system has high reliability and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 is a structural schematic diagram of a seawater desalination device provided in an embodiment of the present application;

[0040] Figure 2 is a schematic structural diagram of another seawater desalination device provided in an embodiment of the present application;

[0041] Figure 3 It is a schematic diagram of the principle structure of a seawater desalination device provided in an embodiment of the present application;

[0042] Figure 4 is a schematic structural diagram of another seawater desalination device provided in an embodiment of the present application;

[0043] Figure 5 is a flow chart of a seawater desalination method provided in an embodiment of the present application;

[0044] Figure 6 is a flow chart of another seawater desalination method provided in an embodiment of the present application;

[0045] Reference numerals:

[0046] The second pump-21; the second reverse osmosis membrane-22; the first inlet-231; the first outlet-232; the flow regulating module-23; the second inlet-241; the second pressure regulating module-24; the second outlet-242; the three-way valve-25; the flow monitoring module-26; the check valve-27; the first reverse osmosis membrane-11; the third inlet-121; the first pressure regulating module-12; the first pump-13; the first pressure monitoring module-14; the second pressure monitoring module-15; the filtering module-16; the first motor-17; the second motor-28; the orifice plate-201; the flow regulating valve-202. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0048] It should be understood that although the terms first, second, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another component. Therefore, the first component discussed below can be referred to as the second component without departing from the teachings of the concepts of the present application. As used herein, the term "and / or" includes any one of the associated listed items and all combinations of one or more.

[0049] Those skilled in the art will appreciate that the drawings are only schematic diagrams of example embodiments and may not be to scale. The modules or processes in the drawings are not necessarily required to implement the present application and therefore cannot be used to limit the scope of protection of the present application.

[0050] The applicant has found through research that, at present, in small and medium-sized secondary reverse osmosis desalination devices, the working pressure of the secondary reverse osmosis membrane is all provided by the secondary high-pressure pump, that is, the water produced by the primary reverse osmosis membrane and the secondary concentrated water return water converge as the secondary raw water and flow into the secondary high-pressure pump, and the secondary raw water is pressurized by the secondary high-pressure pump and flows into the secondary reverse osmosis membrane. The working pressure of the secondary reverse osmosis system is controlled by controlling the secondary high-pressure regulating valve, and the inlet pressure and secondary recovery rate of the secondary pump are guaranteed by the secondary reflux valve and the secondary discharge valve. The entire control process is relatively complicated. The working pressure of the secondary system of the secondary reverse osmosis desalination device is generally around 0.8MPa, and a multi-stage centrifugal pump is generally selected. The multi-stage centrifugal pump is relatively large in size and relatively inefficient. In addition, the traditional secondary reverse osmosis desalination device has a large equipment size, high cost, complex control process, and low reliability, which to a certain extent limits the scope of application of the secondary reverse osmosis desalination device.

[0051] To this end, the embodiments of the present application provide a seawater desalination device and a seawater desalination method to simplify the control process, improve system reliability and scope of application, and solve the technical problem that the control process of the existing seawater desalination device is relatively complex and difficult to implement.

[0052] Figure 1 is a schematic diagram of the structure of a seawater desalination device provided in the embodiment of the present application. Figure 1The seawater desalination device comprises at least a primary desalination system and a secondary desalination system, wherein the primary desalination system is used to deliver primary produced water to the secondary desalination system; the secondary desalination system comprises: a second pump 21 connected to the primary desalination system, used to receive the primary produced water and pressurize the primary produced water; a secondary reverse osmosis membrane 22, having a second input end and a second concentrated water end, the second input end being connected to the second pump 21, used to receive the pressurized primary produced water and make the non-permeated primary produced water form secondary concentrated water; a flow regulating module 23, having a first inlet 231 and a first outlet 232, the first inlet 231 being connected to the second concentrated water end, used to receive the secondary concentrated water; the flow regulating module 23 receives the secondary concentrated water by changing the second input end 231; the second input end 232 is connected to the second concentrated water end; the flow regulating module 23 receives the secondary concentrated water by changing the second input end 231; the second input end 232 is connected to the second concentrated water end; the second concentrated water ... The flow rate of the concentrated water is such that a pressure difference is formed between the first inlet 231 and the first outlet 232, and the secondary reverse osmosis membrane 22 can generate a working pressure according to the pressure difference; the second pump 21 is also connected to the first outlet 232, and is used to receive a part of the secondary concentrated water output by the first outlet 232; the secondary pressure regulating module 24 has a second inlet 241, and the second inlet 241 is connected to the first outlet 232, and is used to receive another part of the secondary concentrated water output by the first outlet 232; the secondary pressure regulating module 24 adjusts the flow rate of the received secondary concentrated water to change the pressure of the primary produced water, and the secondary reverse osmosis membrane 22 can adjust the working pressure and / or the water production according to the change in the pressure of the primary produced water.

[0053] Among them, the second pump 21 can be a high-pressure pump, which is used to pressurize the primary produced water and the secondary concentrated water output from the second concentrated water end of the primary desalination system and output through the flow regulation module and reflux, and then output to the secondary reverse osmosis membrane 22 to provide working pressure for the secondary reverse osmosis membrane 22.

[0054] The greater the working pressure of the secondary reverse osmosis membrane 22 is, the greater the corresponding secondary water production is.

[0055] For example, when the flow regulation amount of the flow regulation module 23 is set, the pressure difference between the first inlet 231 and the first outlet 232 remains unchanged, and the pressure of the primary produced water can be adjusted by adjusting the flow of the received secondary concentrated water through the secondary pressure regulation module 24, thereby adjusting the working pressure of the secondary reverse osmosis membrane 22. In this way, the control process of the entire device can be simplified while meeting the desalination water production.

[0056] Among them, the specific value of the flow regulation amount of the flow regulation module 23 can be set according to the demand for secondary water production, the corresponding working pressure demand of the secondary reverse osmosis membrane 22, etc. It can be set according to actual conditions and is not specifically limited here.

[0057] It should be noted that the flow regulation of the flow regulating module 23 can be an automatic regulation method or a method in which the flow regulation amount is pre-set. Among them, the method in which the flow regulation amount is pre-set is simpler than the control process of the automatic regulation method and is easier to implement, because the automatic regulation method requires the simultaneous regulation of the flow regulating module and the secondary pressure regulating module, and its control method is relatively complex, but compared with the prior art, its control process is relatively simple and easier to implement. It can be set according to actual conditions, and no specific limitation is made here.

[0058] The flow regulating module 23 is used to regulate the flow rate of the secondary concentrated water it receives, so as to generate a pressure difference between its first inlet 231 and the first outlet 232. The pressure difference between the first inlet 231 and the first outlet 232 generates a working pressure for the secondary reverse osmosis membrane 22.

[0059] In the technical solution of this embodiment, the implementation process of the seawater desalination device is as follows: Figure 1 , the flow regulating module 23 and the secondary pressure regulating module 24 are arranged in the secondary desalination system, such as Figure 1 Corresponding position. When the primary desalination system operates normally, the primary water produced by the primary desalination system flows to the second pump 21, and the second pump 21 will pressurize the primary water produced and output the pressurized primary water produced to the secondary reverse osmosis membrane 22. After being processed by the secondary reverse osmosis membrane 22, the secondary concentrated water output by the second concentrated water end passes through the flow regulating module 23. Due to the setting of the flow regulating module 23, the flow rate of the secondary concentrated water flowing through it will be changed so that a pressure difference is generated between the first inlet and the first outlet of the flow regulating module 23. This pressure difference causes the secondary reverse osmosis membrane 22 to generate working pressure. And the secondary concentrated water output through the first outlet 232 of the flow regulating module 23 is divided into two paths, one of which flows into the secondary pressure regulating module 24 through the second inlet 241 and flows out, and the other flows back to the second pump 21 after converging with the primary water produced, and is pressurized by the second pump 21 and output to the secondary reverse osmosis membrane 22. And by adjusting the flow rate of the secondary concentrated water received by the secondary pressure regulating module 24, the pressure of the primary water produced can be changed, thereby adjusting the working pressure of the secondary pressure regulating module 24. Thus, the working pressure of the secondary pressure regulating module 24 is provided by the pressure difference of the flow regulating module 23 and the pressure (back pressure) generated by the first stage, so that the pressure load of the second pump 21 can be shared, and the working pressure of the second pump 21 can be reduced, so that the selection of the second pump is increased, such as a single-stage centrifugal pump or a smaller pump can be selected, thereby simplifying the system structure, reducing costs and complexity, and improving applicability. Moreover, in terms of control implementation, it is only necessary to control the secondary pressure regulating module to achieve the pressure regulation of the secondary reverse osmosis membrane, and its control process is simple and easy to implement, and the system has high reliability and strong applicability.

[0060] Continue reading Figure 1The secondary reverse osmosis membrane 22 also has a second water production end; the secondary pressure regulating module 24 has a second outlet 242; the secondary desalination system also includes: a three-way valve 25, having a first connection end, a second connection end and a third connection end, the first connection end is connected to the second water production end, the second connection end is connected to the second outlet 242, and the third connection end outputs the secondary water production; a flow monitoring module 26 is arranged between the first connection end and the second water production end; a check valve 27 is arranged between the second outlet 242 and the second connection end.

[0061] The flow monitoring module 26 is used to monitor the flow of the secondary produced water outputted from the second water producing end.

[0062] The three-way valve 25 may be an electric three-way valve, and the specific selection and other settings may be set according to actual conditions, and no specific limitation is made here. The flow monitoring module 26 may be a flow sensor.

[0063] In addition, continue to read Figure 1 Another flow monitoring module 18 is provided between the primary desalination system and the second pump 21 to monitor the flow of primary water produced by the primary desalination system. A conductivity sensor 29 is also provided between the first connection end of the three-way valve 25 and the secondary water production end.

[0064] Continue reading Figure 1 The primary desalination system includes: a primary reverse osmosis membrane 11, having a first input end, a first water production end and a first concentrated water end, the first water production end being connected to a second pump 21; a primary pressure regulating module 12, having a third inlet 121, the third inlet 121 being connected to the first concentrated water end, and being used to receive primary concentrated water outputted from the first concentrated water end; the primary pressure regulating module 12 changes the pressure of the primary produced water by adjusting the flow rate of the received primary concentrated water; a first pump 13, being connected to the first input end, and being used to pressurize the inlet water of the first input end.

[0065] Among them, the implementation process of the primary desalination system is as follows: seawater enters the first pump 13, and after being pressurized by the first pump 13, it flows into the primary reverse osmosis membrane 11 from the first input end, and after being processed by the primary reverse osmosis membrane 11, the generated primary produced water flows into the second pump 21, and the generated primary concentrated water is output through the primary pressure regulating module 12. As the opening of the primary pressure regulating module becomes smaller, the working pressure of the primary reverse osmosis membrane 11 continues to increase, and the corresponding primary water production also continues to increase. When the water production of the primary reverse osmosis membrane 11 reaches the rated flow rate, the entire primary desalination system enters normal operation (i.e., a stable state). After the primary desalination system operates normally, the primary produced water output by the primary desalination system flows to the second pump 21, and the second pump 21 will pressurize the primary produced water and output the pressurized primary produced water to the secondary reverse osmosis membrane 22. After being processed by the secondary reverse osmosis membrane 22, the secondary concentrated water output from the second concentrated water end passes through the flow regulating module 23. Since the setting of the flow regulating module 23 will change the flow rate of the secondary concentrated water flowing through it, so that a pressure difference is generated between the first inlet and the first outlet of the flow regulating module 23, this pressure difference causes the secondary reverse osmosis membrane 22 to generate working pressure. And the secondary concentrated water output through the first outlet 232 of the flow regulating module 23 is divided into two paths, one is to flow into the secondary pressure regulating module 24 through the second inlet 241 and flow out, and the other is to return to the second pump 21 after merging with the primary produced water, and is output to the secondary reverse osmosis membrane 22 after being pressurized by the second pump 21. And by adjusting the flow rate of the secondary concentrated water received by the secondary pressure regulating module 24, the pressure of the primary produced water can be changed, thereby adjusting the working pressure of the secondary pressure regulating module 24. Therefore, it is only necessary to adjust the secondary pressure regulating module to adjust the working pressure of the secondary reverse osmosis membrane 22, so as to meet the secondary produced water demand. Therefore, the control process of the whole device is simple and easy to implement.

[0066] Under normal circumstances, when the primary desalination system operates normally and stably, its corresponding primary water production remains unchanged. However, when the primary water production is not within the normal range, or the primary water production demand changes (such as the primary water production demand increases or decreases), the primary water production can be adjusted by adjusting the flow of the primary concentrated water of the primary pressure regulating module 12, so that the pressure of the primary water production changes, and then the working pressure of the secondary reverse osmosis membrane 22 changes. When the primary water production reaches the normal range, or reaches the required primary water production, the primary desalination system resumes normal operation. After the primary desalination system operates normally, it is only necessary to adjust the secondary pressure regulating module to adjust the working pressure of the secondary reverse osmosis membrane 22, so as to meet the secondary water production demand. Therefore, the control process of the entire device is simple and easy to implement.

[0067] Optionally, continue to Figure 1The primary desalination system further includes: a filtering module 16 connected to the first pump 13; a first pressure monitoring module 14 disposed between the first pump 13 and the filtering module 16; and a second pressure monitoring module 15 disposed between the first pump 13 and the first input end.

[0068] The filter module 16 is used to filter the seawater entering the primary desalination system to remove impurities, etc. The filter module 16 can be a filter, etc., which can be specifically configured according to actual conditions and is not specifically limited here.

[0069] The first pressure monitoring module 14 is used to monitor the pressure between the filter module and the first pump 13 in real time, and the second pressure monitoring module 15 is used to monitor the pressure between the first pump 13 and the first input end in real time. Both the first pressure monitoring module 14 and the second pressure monitoring module 15 can be pressure sensors.

[0070] Continue reading Figure 1 The first pump 13 and the second pump 21 are respectively provided with a first motor 17 and a second motor 28. The first motor 17 and the second motor 28 are respectively used to provide power to the first pump 13 and the second pump 21. The first pump 13 and the second pump 21 are high-pressure pumps, and the first motor 17 and the second motor 28 can be DC motors, etc., which can be set according to actual conditions and are not specifically limited here.

[0071] Optionally, the first-stage pressure regulating module is a first-stage high-pressure regulating valve, and the second-stage pressure regulating module is a second-stage high-pressure regulating valve.

[0072] Figure 2 is a schematic diagram of the structure of another seawater desalination device provided in the embodiment of the present application. As an implementation mode, optionally, the embodiment of the present application exemplarily shows the implementation of the flow regulating module including the orifice plate. Figure 2 The flow regulating module includes an orifice plate 201 , and at least one through hole is provided on the orifice plate 201 . The orifice plate 201 changes the flow rate of the received secondary concentrated water through the through hole to form a pressure difference between the first inlet 231 and the first outlet 232 .

[0073] Among them, the shape of the through hole can be any shape such as a circle, a triangle, a quadrilateral, etc., which can be set according to the actual situation and is not specifically limited here. Similarly, the shape of the orifice plate can also be any shape such as a circle, a triangle, a quadrilateral, etc., which can be set according to the actual situation and is not specifically limited here.

[0074] Exemplarily, the shape of the orifice plate is circular, and a through hole is provided on the orifice plate 201, and the through hole is also circular, and the center of the through hole is coaxial with the center of the orifice plate. Exemplarily, taking the through hole as a circular through hole as an example, the aperture size of the through hole ranges from 1.5 mm to 6 mm, for example, it can be any one of 1.5 mm, 2 mm, 2.5 mm, 4 mm, 4.5 mm, 5 mm, 6 mm or a range between any two values; the cross-sectional area of ​​the orifice plate ranges from 0.5×10 -5 m 2 -10×10 -5 m 2 , for example, it can be 0.5×10 -5 m 2 , 1×10 -5 m 2 , 1.2×10 -5 m 2 , 2×10 -5 m 2 , 2.5×10 -5 m 2 , 4×10 -5 m 2 , 5×10 -5 m 2 ,7×10 -5 m 2 , 7.5×10 -5 m 2 , 8×10 -5 m 2 ,9×10 -5 m 2 , 10×10 -5 m 2 Any value or range between any two values ​​in .

[0075] The number of through holes can be set according to actual conditions and is not specifically limited here.

[0076] After the structure of the orifice plate is determined, the pressure difference between the first inlet and the first outlet of the orifice plate can also be determined. For example, after the shape, size and arrangement position of the through hole are determined, the cross-sectional area of ​​the orifice plate and the pressure difference between the first inlet and the first outlet of the orifice plate can also be determined accordingly. For example, taking the through hole as a circular through hole as an example, assuming that the aperture size is 4 mm, the cross-sectional area of ​​the orifice plate is 1.256×10 -5 m 2 The pressure difference between the first inlet 231 and the first outlet 232 is 0.4 MPa.

[0077] In the technical solution of the embodiment of the present application, the implementation process of the seawater desalination device is as follows: For example, see Figure 2, the orifice plate 201 and the secondary pressure regulating module 24 are arranged in the secondary desalination system, such as Figure 2 Corresponding position. When the primary desalination system operates normally, the primary water produced by the primary desalination system flows to the second pump 21, and the second pump 21 will pressurize the primary water produced and output the pressurized primary water produced to the secondary reverse osmosis membrane 22. After being processed by the secondary reverse osmosis membrane 22, the secondary concentrated water output by the second concentrated water end passes through the orifice plate 201. Due to the setting of the orifice plate 201, the flow rate of the secondary concentrated water flowing through it will be changed so that a pressure difference is generated between the first inlet and the first outlet of the orifice plate 201. This pressure difference causes the secondary reverse osmosis membrane 22 to generate working pressure. And the secondary concentrated water output through the first outlet 232 of the orifice plate 201 is divided into two paths, one of which flows into the secondary pressure regulating module 24 through the second inlet 241 and flows out, and the other flows back to the second pump 21 after converging with the primary water produced, and is pressurized by the second pump 21 and output to the secondary reverse osmosis membrane 22. And by adjusting the flow rate of the secondary concentrated water received by the secondary pressure regulating module 24, the pressure of the primary water produced can be changed, thereby adjusting the working pressure of the secondary pressure regulating module 24. Thus, the working pressure of the secondary pressure regulating module 24 is provided by the pressure difference of the orifice plate 201 and the pressure (back pressure) generated by the first stage, so that the pressure load of the second pump 21 can be shared, and the working pressure of the second pump 21 can be reduced, so that the selection of the second pump is increased, such as a single-stage centrifugal pump or a smaller pump can be selected, thereby simplifying the system structure, reducing costs and complexity, and improving applicability. Moreover, in terms of control implementation, it is only necessary to control the secondary pressure regulating module to achieve the pressure regulation of the secondary reverse osmosis membrane, and its control process is simple and easy to implement, and the system has high reliability and strong applicability.

[0078] Figure 3 Schematic diagram of the principle structure of a seawater desalination device provided in the embodiment of the present application. For example, taking the flow regulating module as an orifice plate as an example, refer to Figure 3 The realization principle of the seawater desalination device is as follows: Figure 3, assuming that the flow rate of primary water production is Q0, the pressure of primary water production is P0, the flow rate of the second pump 21 is Q1, the pressure of the second pump 21 is P1, and the flow rate of the second water production end of the secondary reverse osmosis membrane 22 is Q2. Ignoring the influence of the flow resistance of the membrane, it can be obtained that the flow rate of the secondary concentrated water at the second concentrated water end is Q1-Q2 and the pressure is P1, the flow rate of the secondary concentrated water refluxed from the first outlet 232 is Q1-Q0 and the pressure is P0, and the flow rate of the secondary concentrated water (i.e., the secondary concentrated water discharged from the second level) from the first outlet 232 to the second inlet 241 is Q0-Q2 and the pressure is P0. The liquid flow rate of the first outlet 232 of the orifice plate, the first inlet 231 and the pressure are V0, V1 and P0 respectively, the cross-sectional area of ​​the orifice plate is S0, and the pressure of the primary water production (i.e., the back pressure) is P0. Among them, the pressure of the primary water production can be adjusted by adjusting the flow rate of the received secondary concentrated water (i.e., the flow rate of the secondary concentrated water discharged from the second level) by the secondary pressure regulating module 24. Due to the setting of the orifice plate, the flow rate of the secondary concentrated water increases from V1 to V0 under the action of the orifice plate. Due to the change in flow rate, a pressure difference is generated before and after the orifice plate, that is, a pressure difference is generated between the first inlet and the first outlet of the orifice plate, so that the secondary reverse osmosis membrane 22 generates a working pressure according to the pressure difference. The pressure difference ΔP between the first inlet and the first outlet of the orifice plate can be obtained as:

[0079] ΔP=P1-P0=0.5ρ(V0 2 -V1 2 )

[0080] Here, ρ is the density of the liquid.

[0081] Since V0 is much greater than V1, the working pressure P1 of the secondary reverse osmosis membrane 22 is:

[0082] P1=0.5ρ((Q1-Q2) / S0) 2 +P0

[0083] It can be seen that the working pressure of the secondary reverse osmosis membrane 22 is determined by the pressure difference ΔP before and after the orifice plate and the pressure P0 of the primary water production. Since the pressure difference before and after the orifice plate is determined, the working pressure of the secondary reverse osmosis membrane 22 can be adjusted by adjusting the back pressure of the primary water production, thereby adjusting the secondary water production. Therefore, the back pressure of the primary water production can be adjusted by adjusting the flow rate of the secondary concentrated water discharged by the secondary pressure regulating module 24, thereby adjusting the working pressure of the secondary reverse osmosis membrane 22.

[0084] Exemplarily, the specific implementation method of adjusting the flow rate of the secondary concentrated water discharged by the secondary pressure regulating module 24 can be: adjusting by adjusting the valve opening of the secondary pressure regulating module 24. For example, as the valve opening of the secondary pressure regulating module 24 is closed, the back pressure of the primary water production increases, and the working pressure of the secondary reverse osmosis membrane 22 increases, thereby increasing the secondary water production. Thus, the working pressure and / or flow rate of the secondary reverse osmosis membrane 22 is controlled by adjusting the back pressure of the primary water production. In addition, in terms of control implementation, since only the secondary pressure regulating module needs to be controlled to achieve the pressure regulation of the secondary reverse osmosis membrane, the control process is simple and easy to implement, and the system has high reliability and strong applicability.

[0085] As a specific implementation, optionally, the value range of the primary water production flow Q0 is: 0.2t / h-0.8t / h, for example, it can be any one of 0.2t / h, 0.4t / h, 0.8t / h or a range between any two values; the value range of the primary water production pressure P0 is: 0.2Mpa-0.8Mpa, for example, it can be any one of 0.2Mpa, 0.4Mpa, 0.8Mpa or a range between any two values; the second pump 2 The flow rate Q1 of the secondary reverse osmosis membrane 22 is 0.25 t / h, the pressure difference P1-P0 between the first inlet 231 and the first outlet 232 is 0.4 MPa, the through hole diameter of the orifice plate is 4 mm, and the cross-sectional area of ​​the orifice plate is 1.256×10 -5 m 2 .

[0086] Figure 4 is a schematic diagram of the structure of another seawater desalination device provided in the embodiment of the present application. As an implementation mode, optionally, the embodiment of the present application exemplarily shows the implementation of the flow regulating module including a flow regulating valve. Figure 4 The flow regulating module includes a flow regulating valve 202 , and the flow regulating valve 202 changes the flow rate of the received secondary concentrated water by adjusting the opening of the flow regulating valve 202 to form a pressure difference between the first inlet 231 and the first outlet 232 .

[0087] After the opening size of the flow control valve is set, the pressure difference between the first inlet and the first outlet can also be determined.

[0088] The opening of the flow control valve 202 is related to the pressure difference between the first inlet 231 and the first outlet 232 and the selection parameters of the flow control valve. For example, if the required pressure difference between the first inlet 231 and the first outlet 232 is 0.4 Mpa, the corresponding opening is further set according to the type of the specifically selected flow control valve, so that a pressure difference of 0.4 Mpa is generated when the secondary concentrated water flows through the flow control valve 202.

[0089] In the technical solution of the embodiment of the present application, the implementation process of the seawater desalination device is as follows: For example, see Figure 4 , the flow control valve 202 and the secondary pressure regulating module 24 are arranged in the secondary desalination system, such as Figure 4 Corresponding position. When the primary desalination system operates normally, the primary water produced by the primary desalination system flows to the second pump 21. The second pump 21 will pressurize the primary water produced and output the pressurized primary water produced to the secondary reverse osmosis membrane 22. After being processed by the secondary reverse osmosis membrane 22, the secondary concentrated water output by the second concentrated water end passes through the flow regulating valve 202. Since the setting of the flow regulating valve 202 will change the flow rate of the secondary concentrated water flowing through it, a pressure difference will be generated between the first inlet 231 and the first outlet 232 of the flow regulating valve 202. This pressure difference causes the secondary reverse osmosis membrane 22 to generate working pressure. And the secondary concentrated water output through the first outlet 232 of the flow regulating valve 202 is divided into two paths, one of which flows into the secondary pressure regulating module 24 through the second inlet 241 and flows out, and the other flows back to the second pump 21 after merging with the primary water produced, and is pressurized by the second pump 21 and output to the secondary reverse osmosis membrane 22. And by adjusting the flow rate of the secondary concentrated water received by the secondary pressure regulating module 24, the pressure of the primary water production can be changed, thereby adjusting the working pressure of the secondary pressure regulating module 24. Thus, the working pressure of the secondary pressure regulating module 24 is provided by the pressure difference of the flow regulating valve 202 and the pressure (back pressure) generated by the primary stage, so that the pressure load of the second pump 21 can be shared, and the working pressure of the second pump 21 can be reduced, so that the choice of the second pump is increased, such as a single-stage centrifugal pump or a smaller pump can be selected, thereby simplifying the system structure, reducing costs and complexity, and improving applicability. Moreover, in terms of control implementation, it is only necessary to control the secondary pressure regulating module 24 to achieve the pressure regulation of the secondary reverse osmosis membrane 22, and its control process is simple and easy to implement, and the system has high reliability and strong applicability.

[0090] It should be noted that, in the embodiment of the present application, the flow regulating module can also be set to: the implementation of the orifice plate 201 and the flow regulating valve 202 jointly regulating. For example, the orifice plate 201 and the flow regulating valve 202 are connected in series between the second concentrated water end and the second inlet 241. The specific parameter settings can be set according to the actual situation and are not specifically limited here.

[0091] Figure 5is a flow chart of a seawater desalination method provided in the embodiment of the present application. Accordingly, the embodiment of the present application also provides a seawater desalination method. Figure 5 , the method comprises the following steps:

[0092] Step 110: After the primary desalination system operates normally and the primary produced water fills the entire secondary desalination system, the second pump 21 is controlled to start.

[0093] Specifically, after the primary desalination system operates normally, the primary produced water is stably output and flows to the secondary desalination system, so that the primary produced water fills the entire secondary desalination system. At this time, the second pump is controlled to start.

[0094] Step 120: After the second pump 21 is started, a pressure difference is formed between the first inlet 231 and the first outlet 232, so that the secondary reverse osmosis membrane 22 can generate a working pressure according to the pressure difference.

[0095] Specifically, as the second pump 21 is started, a certain pressure difference is generated before and after the flow regulating module 23 , and the pressure difference causes the secondary reverse osmosis membrane 22 to generate working pressure.

[0096] Step 130, adjusting the flow of the received secondary concentrated water through the secondary pressure regulating module 24 to change the pressure of the primary produced water, so that the secondary reverse osmosis membrane 22 can adjust the working pressure and / or water production according to the change of the pressure of the primary produced water.

[0097] Among them, by adjusting the secondary pressure regulating module 24, the flow rate of the discharged secondary concentrated water can be adjusted so that the pressure of the primary water production changes, and then the secondary reverse osmosis membrane 22 can adjust the working pressure and / or water production according to the change of the pressure of the primary water production. And as the secondary pressure regulating module 24 reduces the flow rate of the discharged secondary concentrated water, the pressure of the primary water production continues to increase, and the working pressure of the secondary reverse osmosis membrane 22 continues to increase, thereby increasing the secondary water production, thereby achieving: only by adjusting the secondary pressure regulating module 24, the working pressure of the secondary reverse osmosis membrane 22 can be adjusted, so the entire control process is simple and easy to implement. And the working pressure of the secondary pressure regulating module 24 is provided by the pressure difference of the flow regulating module 23 and the pressure (back pressure) generated by the first stage, so that the pressure load of the second pump 21 can be shared, the working pressure of the second pump 21 can be reduced, and the choice of the second pump 21 is increased, such as a single-stage centrifugal pump or a smaller pump can be selected, thereby simplifying the system structure, reducing costs and complexity, and improving applicability.

[0098] The technical solution of the embodiment of the present application provides a seawater desalination method, which includes: after the primary desalination system operates normally, when the primary produced water fills the entire secondary desalination system, controlling the second pump 21 to start; after the second pump 21 is started, a pressure difference is formed between the first inlet 231 and the first outlet 232, so that the secondary reverse osmosis membrane 22 can generate a working pressure according to the pressure difference; adjusting the flow rate of the received secondary concentrated water through the secondary pressure regulating module 24 to change the pressure of the primary produced water, so that the secondary reverse osmosis membrane 22 can adjust the working pressure and / or water production according to the change in the pressure of the primary produced water. It can be seen that by setting the flow regulating module 23 and the secondary pressure regulating module 24, the flow regulating module 23 forms a pressure difference by changing the flow rate of the received secondary concentrated water, so that the secondary reverse osmosis membrane 22 can generate a working pressure according to the pressure difference, and cooperate with the secondary pressure regulating module 24, the flow of the received secondary concentrated water is adjusted by the secondary pressure regulating module 24 to change the pressure of the primary produced water, so that the secondary reverse osmosis membrane 22 can adjust the working pressure and / or the water production according to the change of the pressure of the primary produced water, so that the second pump 21 and the secondary pressure regulating module 24 jointly share the adjustment of the working pressure of the secondary reverse osmosis membrane 22, thereby reducing the load of the second pump 21. In addition, the pressure regulation of the secondary reverse osmosis membrane 22 can be achieved by adjusting the secondary pressure regulating module 24, and its control process is simple, easy to implement, and the system reliability is high, and the application range is wide.

[0099] Figure 6 is a flow chart of another seawater desalination method provided in the embodiment of the present application. Figure 6 , the seawater desalination method comprises the following steps:

[0100] Step 210: When the amount of primary produced water changes, the flow rate of the received primary concentrated water is adjusted by the primary pressure regulating module 12 to change the pressure of the primary produced water.

[0101] Among them, under normal circumstances, when the primary desalination system operates normally and stably, the corresponding primary water production remains unchanged. However, when the primary water production is not within the normal range, or the primary water production demand changes (such as the primary water production demand increases or decreases), the primary water production can be adjusted by adjusting the flow rate of the primary concentrated water of the primary pressure regulating module 12, so that the pressure of the primary water production changes, and then the working pressure of the secondary reverse osmosis membrane 22 changes.

[0102] Step 220: After the primary desalination system operates normally and the primary produced water fills the entire secondary desalination system, the second pump 21 is controlled to start.

[0103] Step 230: After the second pump 21 is started, a pressure difference is formed between the first inlet 231 and the first outlet 232, so that the secondary reverse osmosis membrane 22 can generate a working pressure according to the pressure difference.

[0104] Step 240, adjusting the flow of the received secondary concentrated water through the secondary pressure regulating module 24 to change the pressure of the primary produced water, so that the secondary reverse osmosis membrane can adjust the working pressure and / or water production according to the change in the pressure of the primary produced water.

[0105] Specifically, when the primary water production is not within the normal range, or the primary water production demand changes (such as the primary water production demand increases or decreases), the primary water production can be adjusted by adjusting the flow of the primary concentrated water of the primary pressure regulating module 12, so that the pressure of the primary water production changes, and then the working pressure of the secondary reverse osmosis membrane 22 changes. When the primary water production reaches the normal range, or reaches the required primary water production, the primary desalination system resumes normal operation. After the primary desalination system operates normally, it is only necessary to adjust the secondary pressure regulating module 24 to adjust the working pressure of the secondary reverse osmosis membrane 22, so as to meet the secondary water production demand. Therefore, the control process of the entire device is simple and easy to implement.

[0106] In some embodiments, the flow regulating module 23 includes an orifice plate 201; the working pressure of the secondary reverse osmosis membrane 22 is calculated as follows:

[0107] P1=0.5ρ((Q1-Q2) / S0) 2 +P0

[0108] Wherein, P1 is the working pressure of the secondary reverse osmosis membrane 22; P0 is the primary water production back pressure; Q1 is the flow rate of the second pump 21; Q2 is the secondary water production flow rate; S0 is the cross-sectional area of ​​the orifice plate 201; and ρ is the liquid density.

[0109] The seawater desalination device and seawater desalination method provided in the embodiments of the present application are introduced in detail above, and the principles and implementation methods of the present application are explained by using specific examples. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application; ordinary technicians in this field should understand that: they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims

1. A seawater desalination device, characterized in that: At least comprising a primary desalination system and a secondary desalination system, wherein the primary desalination system is used to transport primary produced water to the secondary desalination system; The secondary desalination system comprises: a second pump (21), connected to the primary desalination system, for receiving the primary produced water and pressurizing the primary produced water; A secondary reverse osmosis membrane (22) has a second input end and a second concentrated water end, wherein the second input end is connected to the second pump (21) and is used to receive pressurized primary produced water and convert the unpermeated primary produced water into secondary concentrated water; A flow regulating module (23) having a first inlet (231) and a first outlet (232), wherein the first inlet (231) is connected to the second concentrated water end and is used to receive the secondary concentrated water; the flow regulating module (23) changes the flow rate of the received secondary concentrated water so as to form a pressure difference between the first inlet (231) and the first outlet (232), and the secondary reverse osmosis membrane (22) can generate a working pressure according to the pressure difference; the second pump (21) is also connected to the first outlet (232) and is used to receive part of the secondary concentrated water outputted by the first outlet (232); A secondary pressure regulating module (24) has a second inlet, the second inlet is connected to the first outlet (232), and is used to receive another part of the secondary concentrated water output by the first outlet (232); the secondary pressure regulating module (24) adjusts the flow rate of the received secondary concentrated water to change the pressure of the primary produced water, and the secondary reverse osmosis membrane (22) can adjust the working pressure and / or water production according to the change in the pressure of the primary produced water.

2. The seawater desalination device according to claim 1, characterized in that: The flow regulating module (23) comprises an orifice plate (201), and the orifice plate (201) is provided with at least one through hole, and the orifice plate (201) changes the flow rate of the received secondary concentrated water through the through hole to form a pressure difference between the first inlet (231) and the first outlet (232).

3. The seawater desalination device according to claim 2, characterized in that: The cross-sectional area of ​​the orifice plate is in the range of 0.5×10 -5 m 2 -10×10 -5 m 2 .

4. The seawater desalination device according to claim 1, characterized in that: The flow regulating module (23) comprises a flow regulating valve (202), and the flow regulating valve (202) changes the flow rate of the received secondary concentrated water by adjusting the opening of the flow regulating valve (202) to form a pressure difference between the first inlet (231) and the first outlet (232).

5. The seawater desalination device according to claim 1, characterized in that: The pressure difference between the first inlet (231) and the first outlet (232) has a value range of 0.3Mpa-0.8Mpa, and the pressure variation range of the primary produced water is 0.2Mpa-0.8Mpa.

6. The seawater desalination device according to claim 1, characterized in that: The primary desalination system comprises: A primary reverse osmosis membrane (11) having a first input end, a first water production end and a first concentrated water end, wherein the first water production end is connected to the second pump (21); The primary pressure regulating module (12) has a third inlet (121), the third inlet (121) being connected to the first concentrated water end and being used to receive primary concentrated water outputted by the first concentrated water end; the primary pressure regulating module (12) changes the pressure of the primary produced water by adjusting the flow rate of the received primary concentrated water; A first pump (13) is connected to the first input end and is used to increase the pressure of water entering the first input end.

7. The seawater desalination device according to claim 6, characterized in that: The primary desalination system also includes: A filter module (16) connected to the first pump (13); A first pressure monitoring module (14) is arranged between the first pump (13) and the filter module (16); A second pressure monitoring module (15) is arranged between the first pump (13) and the first input end.

8. The seawater desalination device according to claim 6, characterized in that: The primary pressure regulating module (12) is a primary high-pressure regulating valve, and the secondary pressure regulating module (24) is a secondary high-pressure regulating valve.

9. The seawater desalination device according to claim 1, characterized in that: The secondary reverse osmosis membrane (22) also has a second water production end; the secondary pressure regulating module (24) has a second outlet (242); the secondary desalination system also includes: A three-way valve (25) having a first connection end, a second connection end and a third connection end, wherein the first connection end is connected to the second water production end, the second connection end is connected to the second outlet (242), and the third connection end outputs secondary water production; A flow monitoring module (26), arranged between the first connection end and the second water production end; A check valve (27) is arranged between the second outlet (242) and the second connection end.

10. A method for desalination of seawater, characterized in that: Applied to a seawater desalination device as claimed in any one of claims 1 to 9, the method comprising: After the primary desalination system operates normally, when the primary produced water fills the entire secondary desalination system, controlling the second pump (21) to start; After the second pump (21) is started, a pressure difference is formed between the first inlet (231) and the first outlet (232), so that the secondary reverse osmosis membrane (22) can generate a working pressure according to the pressure difference; The flow rate of the received secondary concentrated water is adjusted by the secondary pressure regulating module (24) to change the pressure of the primary produced water, so that the secondary reverse osmosis membrane (22) can adjust the working pressure and / or the water production according to the change in the pressure of the primary produced water.

11. The seawater desalination method according to claim 10, characterized in that: Before the primary desalination system operates normally, it also includes: When the amount of the primary produced water changes, the flow rate of the received primary concentrated water is adjusted by the primary pressure regulating module (12) so that the pressure of the primary produced water changes.

12. The seawater desalination method according to claim 10, characterized in that: The flow regulating module comprises an orifice plate (201); the calculation formula of the working pressure of the secondary reverse osmosis membrane is: P1=0.5ρ((Q1-Q2) / S0) 2 +P0; Wherein, P1 is the working pressure of the secondary reverse osmosis membrane (22); P0 is the primary water production back pressure; Q1 is the flow rate of the second pump; Q2 is the secondary water production flow rate; S0 is the cross-sectional area of ​​the orifice plate; and ρ is the liquid density.

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