Low-energy consumption forward and reverse flow stage effect high multiple membrane concentration system and switching method thereof

Abstract

The application discloses a low-energy-consumption high-efficiency high-multiple membrane concentration system and a switching method thereof, and aims to solve the problems of high energy consumption and high risk of the existing concentration methods. The application comprises a plurality of reverse osmosis membrane assemblies, the reverse osmosis membrane assemblies are provided with high-pressure sides and low-pressure sides, the reverse osmosis membrane assemblies are provided with high-pressure side interfaces I, high-pressure side interfaces II, low-pressure side interfaces I and low-pressure side interfaces II, the high-pressure sides of adjacent reverse osmosis membrane assemblies are connected in series through pipelines, a liquid to be concentrated sequentially passes through the high-pressure sides of reverse osmosis membrane assemblies of each effect and generates low-salinity water at the low-pressure sides, the interfaces of adjacent low-pressure sides are connected through pipelines, and the low-salinity water sequentially passes through the low-pressure sides of the reverse osmosis membrane assemblies of each effect, wherein a plurality of switch valves are arranged on the pipelines, and the switch valves are periodically switched to make the low-salinity water pass through the reverse osmosis membrane assemblies of each effect along the forward flow or the reverse flow. The reverse osmosis membrane assemblies are connected in series, and corresponding pipelines and switch valves are arranged, so that the energy consumption is reduced, and the pressure required by the reverse osmosis is reduced.

Description

Technical Field

[0001] This invention relates to the field of reverse osmosis, and more specifically, to a low-energy-consumption, high-efficiency, forward and reverse flow membrane concentration system and its switching method. Background Technology

[0002] Reverse osmosis is a selective permeation separation technology that uses external pressure to overcome the osmotic pressure on both sides of a membrane. It utilizes the properties of a semi-permeable membrane to retain the desired solute on the outside, allowing the solvent to pass through. Currently, the most commonly used membrane technology in membrane concentration is ultra-high pressure membrane concentration, such as UHPRO and DTRO / STRO, using specialized ultra-high pressure membranes. At an operating pressure of 120 bar, the final concentrate concentration can reach 100,000-150,000 mg / L. However, due to the high pressure risks and high energy consumption associated with ultra-high pressure, the operating costs are high. Even with ultra-high pressure membrane concentration, it is difficult to achieve the same effect as thermal concentration methods, such as MVR processes. Furthermore, the volume of concentrate after membrane concentration is still relatively large, requiring high precision in subsequent thermal evaporation and crystallization processes, resulting in very high construction and operating costs. Summary of the Invention

[0003] This invention overcomes the shortcomings of existing concentration methods, such as high energy consumption and high risk, and provides a low-energy-consumption, high-efficiency membrane concentration system with both forward and countercurrent flow stages. It can reduce energy consumption and reduce the driving force required for reverse osmosis.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A variable-efficiency high-expansion membrane concentration system includes several reverse osmosis membrane modules. Each reverse osmosis membrane module has a high-pressure side and a low-pressure side. The reverse osmosis membrane module has a high-pressure side interface I, a high-pressure side interface II, a low-pressure side interface I, and a low-pressure side interface II. The high-pressure sides of adjacent reverse osmosis membrane modules are connected in series through pipes. The liquid to be concentrated passes through the high-pressure side of each reverse osmosis membrane module in sequence and generates low-pressure brine on the low-pressure side. The interfaces of adjacent low-pressure sides are connected through pipes, and the low-pressure brine passes through the low-pressure side of each reverse osmosis membrane module in sequence. The pipes are equipped with several switching valves, which periodically switch to allow the low-pressure brine generated by reverse osmosis to pass through each reverse osmosis membrane module in either a co-current or counter-current manner.

[0006] The system includes several reverse osmosis membrane modules connected in series. The liquid to be concentrated flows to each reverse osmosis membrane module in stages, and low-salt water is separated through the reverse osmosis membranes, and the concentrated water is concentrated in stages.

[0007] To reduce energy consumption and improve safety, a multi-effect reverse osmosis membrane module series connection structure is used for reverse osmosis with a smaller driving force. This reduces the osmotic pressure difference between the high-pressure and low-pressure sides within the same effect reverse osmosis membrane module, thereby reducing the corresponding reverse osmosis driving resistance.

[0008] This application adjusts the flow direction on the low-pressure side by setting a switching valve, including both co-current and counter-current flow. Co-current flow involves the flow of brine from the first-effect reverse osmosis membrane module to the terminal reverse osmosis membrane modules, while counter-current flow involves the flow from the terminal reverse osmosis membrane modules back to the first-effect reverse osmosis membrane module. For the reverse osmosis membrane modules, in co-current mode, low-pressure brine flows from low-pressure side interface I to low-pressure side interface II; in counter-current mode, low-pressure brine flows from low-pressure side interface II to low-pressure side interface I. This reduces membrane degradation, acting similarly to backwashing, using brine instead of washing, and reducing maintenance frequency and extending maintenance and cleaning cycles through alternating co-current and counter-current flow. This method also reduces the osmotic pressure differential required for reverse osmosis, thus reducing energy consumption.

[0009] Preferably, the high-pressure side interface I and high-pressure side interface II of adjacent reverse osmosis membrane modules are connected through a first pipe, and the low-pressure side interface I and low-pressure side interface II of adjacent reverse osmosis membrane modules are connected through a second pipe. The first pipe and the second pipe are connected through a third pipe. Switch valves are installed on the second and third pipes, with the third pipe connected downstream of the switch valve on the second pipe. The high-pressure side interface I of the first-effect reverse osmosis membrane module is directly connected to the water to be concentrated. In the co-current mode, the first pipe is connected to the second pipe through the third pipe. The switch valve 7 on the second pipe disconnects the low-pressure side interface I and low-pressure side interface II, allowing the concentrated water from the previous-effect reverse osmosis membrane module to simultaneously enter the high-pressure and low-pressure sides of the next-effect reverse osmosis membrane module. This structure reduces the pressure difference between the high-pressure and low-pressure sides, thereby reducing the driving pressure required for ion reverse osmosis. In countercurrent mode, the third tube is closed and the second tube is open, and the flow directions of concentrate and saline are opposite. In the reverse osmosis process, the concentrate further forward has a lower ion concentration, while the saline has a larger cumulative water volume and a lower ion concentration. This structure is also reasonable and can reduce the ion concentration difference across the reverse osmosis membrane.

[0010] Preferably, the low-pressure side interface II of the nth-effect reverse osmosis membrane module is also connected to the first pipe connected to the high-pressure side interface I of the (n-1)th-effect reverse osmosis membrane module via a fourth pipe. A switch valve is installed on the fourth pipe. For n≥2, either the low-pressure side interface I or low-pressure side interface II of the first-effect reverse osmosis membrane module is connected to the system outlet. This structure is used in co-current mode to incorporate the low-salinity water obtained from each reverse osmosis membrane module into the concentrate feed water of the previous reverse osmosis membrane module, thereby further diluting the concentrate from the previous effect, reducing the ion concentration difference across the membrane, and lowering the corresponding resistance.

[0011] Preferably, the low-pressure side interface II of the last reverse osmosis membrane module is also connected to a fifth pipe, which is connected to the first pipe of the adjacent reverse osmosis membrane module. The fifth pipe is equipped with a switch valve. This structure has the same function as the aforementioned fourth pipe, which is used to replenish concentrate in the countercurrent flow and reduce resistance.

[0012] Preferably, the system also includes a forward osmosis membrane module. The liquid to be concentrated is connected to the low-pressure side of the forward osmosis membrane module, and the high-pressure side interface II of the reverse osmosis membrane module at the end is connected to the high-pressure side of the forward osmosis membrane module. Water is removed from the liquid to be concentrated through the forward osmosis membrane, thereby increasing its concentration.

[0013] Preferably, the system also includes a supplementary reverse osmosis membrane module. The low-pressure side interface I and low-pressure side interface II of the first-effect reverse osmosis membrane module are connected to the supplementary reverse osmosis membrane module via pipes. Each pipe is equipped with a switch valve. The concentrate from the supplementary reverse osmosis membrane module is connected to the inlet pipe of the liquid to be concentrated. This structure is used to further concentrate the low-salt water obtained from the first-effect reverse osmosis membrane module, exporting the low-salt water and incorporating the concentrate into the liquid to be concentrated.

[0014] Preferably, the system also includes a pressurization assembly, which is disposed in a pre-pressurization container on the high-pressure side interface I side and a post-pressurization container on the high-pressure side interface II side of the reverse osmosis membrane module. The first pipe connecting the pre-pressurization container and the high-pressure side interface I is connected through a first switching valve, and the first pipe connecting the post-pressurization container and the high-pressure side interface II is connected through a second switching valve. The first and second switching valves are also connected to a sixth pipe. The pressurization container increases the liquid pressure through volume change. The flow direction of the concentrate of the reverse osmosis membrane module is adjusted by switching the first and second switching valves. The first and second switching valves are two-position four-way valves. The first port of the first switching valve is connected to the previous reverse osmosis membrane module, the second port of the first switching valve is connected to the pre-pressurization container, the third port of the first switching valve is connected to the high-pressure side interface I of the reverse osmosis membrane module, the fourth port of the first switching valve is connected to the sixth pipe, the first port of the second switching valve is connected to the high-pressure side interface II of the reverse osmosis membrane module, the second port of the second switching valve is connected to the post-pressurization container, the third port of the second switching valve is connected to the next reverse osmosis membrane module, and the fourth port of the second switching valve is connected to the sixth pipe.

[0015] The first switching valve has two valve positions. In the first valve position, the first port of the first switching valve is connected to the fourth port of the first switching valve, and the second port of the first switching valve is connected to the third port of the first switching valve. In the second valve position, the first port of the first switching valve is connected to the second port of the first switching valve, and the third port of the first switching valve is connected to the fourth port of the first switching valve.

[0016] The second switching valve has two valve positions. In the first valve position, the first port of the second switching valve is connected to the third port of the second switching valve, and the second port of the second switching valve is connected to the fourth port of the second switching valve. In the second valve position, the first port of the second switching valve is connected to the second port of the second switching valve, and the third port of the second switching valve is connected to the fourth port of the second switching valve.

[0017] The booster unit functions to replenish pressure and switch between co-current and counter-current flow on the high-pressure and low-pressure sides of the reverse osmosis membrane module. Replenishing pressure improves the reverse osmosis efficiency of each type of reverse osmosis membrane module. Switching between co-current and counter-current flow reduces membrane degradation.

[0018] The above structure also allows for switching between forward and reverse flow on the high-voltage side, further reducing the number of maintenance operations and extending the maintenance and cleaning cycle.

[0019] A variable-stage high-efficiency membrane concentration system and its switching method, comprising the variable-stage high-efficiency membrane concentration system described above.

[0020] The low-pressure side switching method of the system is as follows: the switching valves on the third and fourth pipes are open, and the switching valves on the second and fifth pipes are closed.

[0021] The low-pressure side switching reverse flow method of the system is as follows: the switching valves on the third and fourth pipes are closed, and the switching valves on the second and fifth pipes are open;

[0022] The switching method of the concentration system includes setting a first threshold and a second threshold:

[0023] Step 1: Monitor the outflow rate on the low-pressure side of the first-effect reverse osmosis membrane module;

[0024] Step 2: When the water flow rate falls below the first threshold, switch the system to either forward or reverse flow mode.

[0025] Step 3: When the water flow rate falls below the second threshold, clean the system.

[0026] Repeat steps one through three.

[0027] Preferably, the system also includes the supplementary reverse osmosis membrane module mentioned above. The switching valves connected to the low-pressure side interface I and the low-pressure side interface II switch mutually exclusively according to the system's co-current or counter-current flow, allowing the low-salt water to pass through the first-stage reverse osmosis membrane module.

[0028] Preferably, the device also includes the pressurization component described above, which adjusts the flow direction through the high-pressure side of the reverse osmosis membrane component by switching a two-position four-way valve. The two-position four-way valve switches periodically, and the period is set to the filling time of the pre-pressurization container or the post-pressurization container. The pre-pressurization container and the post-pressurization container pressurize according to the alternating volume changes of the liquid level.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] (1) By connecting multi-effect reverse osmosis membrane modules in series to form a low-pressure high-expansion membrane concentration system, the reverse osmosis ion osmosis pressure difference between the high-pressure side and the low-pressure side of each stage is reduced, thereby reducing the reverse osmosis operation driving pressure and concentration difficulty, realizing multi-stage high-expansion membrane concentration at a lower pressure, while reducing energy consumption and improving safety.

[0031] (2) By switching between forward and reverse flow, the number of maintenance operations can be reduced and the maintenance cycle can be extended. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the reverse osmosis membrane module of the present invention;

[0033] Figure 2 This is a schematic diagram of the present invention;

[0034] Figure 3 This is a schematic diagram of the low-pressure side downstream flow of the present invention;

[0035] Figure 4 This is a schematic diagram of the low-pressure side countercurrent of the present invention;

[0036] Figure 5 This is a schematic diagram of Embodiment 1 of the present invention;

[0037] Figure 6 This is a schematic diagram of the reverse osmosis membrane module with downstream flow on the high-pressure side in Embodiment 2 of the present invention;

[0038] Figure 7 This is a schematic diagram of the high-pressure side countercurrent of the reverse osmosis membrane module in Embodiment 2 of the present invention. Detailed Implementation

[0039] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0040] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relational terms determined for the convenience of describing the structural relationships of various components or elements of the present disclosure, and do not specifically refer to any component or element in the present disclosure, and should not be construed as a limitation to the present disclosure.

[0043] In the present disclosure, terms such as "fixed connection", "connected", "connected to" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those skilled in relevant scientific research or technology in the art, the specific meanings of the above terms in the present disclosure can be determined according to specific circumstances, and should not be construed as a limitation to the present disclosure.

[0044] A variable-stage and high-efficiency membrane concentration system, as shown in Figure 1 , Figure 2 Figure [the figure number is missing in the original, assuming it's a specific figure reference], includes several reverse osmosis membrane modules 1, and the reverse osmosis membrane module 1 has a high-pressure side and a low-pressure side. The high-salt water passes through the reverse osmosis effect under high pressure on the high-pressure side, separates the solvent to the low-pressure side, and the concentration on the high-pressure side increases.

[0045] As shown in Figure 1 Figure [the figure number is missing in the original, assuming it's a specific figure reference], the reverse osmosis membrane module 1 has a total of four interfaces, namely a high-pressure side interface I 2, a high-pressure side interface II 3, a low-pressure side interface I 4, and a low-pressure side interface II 5.

[0046] The high-pressure sides of adjacent reverse osmosis membrane modules 1 are connected in series through pipelines. The liquid to be concentrated passes through the high-pressure sides of each stage of reverse osmosis membrane modules 1 in sequence. The interfaces of adjacent low-pressure sides are connected through pipelines, and the low-salt water passes through the low-pressure sides of each stage of reverse osmosis membrane modules 1 in sequence.

[0047] The specific series connection method is as follows:

[0048] As shown in Figure 1As shown, the high-pressure side interface I2 and high-pressure side interface II3 of adjacent reverse osmosis membrane modules 1 are connected through the first pipe 9, and the low-pressure side interface I4 and low-pressure side interface II5 of adjacent reverse osmosis membrane modules 1 are connected through the second pipe 10. The first pipe 9 and the second pipe 10 are connected through the third pipe 11. Both the second pipe 10 and the third pipe 11 are equipped with a switching valve 7, and the third pipe 11 is connected downstream of the switching valve 7 of the second pipe 10. In the co-current mode, the first pipe 9 is connected to the second pipe 10 through the third pipe 11. The switching valve 7 on the second pipe 10 disconnects the low-pressure side interface I4 and the low-pressure side interface II5, so that the concentrate from the previous reverse osmosis membrane module 1 simultaneously enters the high-pressure side and the low-pressure side of the next reverse osmosis membrane module 1. This structure can reduce the pressure difference between the high-pressure side and the low-pressure side, thereby reducing the driving pressure required for ion reverse osmosis. In counter-current mode, the third pipe 11 is closed and the second pipe 10 is open, with the concentrated water and low-salt water flowing in opposite directions. During reverse osmosis, the concentrated water further forward has a lower ion concentration, while the low-salt water further forward accumulates a larger volume of water with a lower ion concentration. This structure is also reasonable, as it can reduce the ion concentration difference across the reverse osmosis membrane. The high-pressure side interface I2 of the first stage is directly connected to the water to be concentrated.

[0049] The low-pressure side interface II5 of the nth-effect reverse osmosis membrane module 1 is also connected via a fourth pipe 12 to the first pipe 9 connected to the high-pressure side interface I2 of the (n-1)th-effect reverse osmosis membrane module 1. A switching valve 7 is installed on the fourth pipe 12, where n ≥ 2. This structure is used in co-current mode to incorporate the low-grade brine obtained from each effect reverse osmosis membrane module 1 into the concentrate feedwater of the previous effect reverse osmosis membrane module 1, thereby further diluting the concentrate from the previous effect and reducing the reverse osmosis ion osmotic pressure difference across the membrane, thus reducing the corresponding reverse osmosis operating driving force. The low-pressure side interface II5 or low-pressure side interface I4 of the first-effect reverse osmosis membrane module then discharges the low-grade brine.

[0050] The low-pressure side interface II5 of the last reverse osmosis membrane module 1 is also connected to a fifth pipe 13. The fifth pipe 13 is connected to the first pipe 9 of the adjacent reverse osmosis membrane module 1, and a switch valve 7 is provided on the fifth pipe 13. This structure has the same function as the aforementioned fourth pipe 12, which is used to supplement concentrate in the countercurrent flow to reduce resistance.

[0051] The pipeline is equipped with several switching valves 7, which periodically switch to allow low-salt water to flow along the co-current or counter-current flow through each reverse osmosis membrane module 1.

[0052] The switching method of its on / off valve 7 is as follows:

[0053] The low-pressure side switching flow method of the system is as follows: the switching valves 7 on the third pipe 11 and the fourth pipe 12 are open, and the switching valves 7 on the second pipe 10 and the fifth pipe 13 are closed; its flow direction is along... Figure 3 As shown.

[0054] The low-pressure side switching reverse flow method of the system is as follows: the switching valves 7 on the third pipe 11 and the fourth pipe 12 are closed, and the switching valves 7 on the second pipe 10 and the fifth pipe 13 are open; its flow direction is along Figure 4 As shown.

[0055] The switching method of the concentration system includes setting a first threshold and a second threshold:

[0056] Step 1: Monitor the outflow rate on the low-pressure side of the first-effect reverse osmosis membrane module 1;

[0057] Step 2: When the water flow rate falls below the first threshold, switch the system to either forward or reverse flow mode.

[0058] Step 3: When the water flow rate falls below the second threshold, clean the system.

[0059] Repeat steps one through three.

[0060] It also includes a forward osmosis membrane module 6, with the liquid to be concentrated connected to the low-pressure side of the forward osmosis membrane module 6, and the high-pressure side interface II3 of the reverse osmosis membrane module 1 at the end connected to the high-pressure side of the forward osmosis membrane module 6. Water is removed from the liquid to be concentrated through the forward osmosis membrane, increasing its concentration.

[0061] It also includes a supplementary reverse osmosis membrane module 8. The low-pressure side interface I4 and low-pressure side interface II5 of the first-stage reverse osmosis membrane module 1 are connected to the supplementary reverse osmosis membrane module 8 via pipelines. Each pipeline is equipped with a switching valve 7. The concentrate from the supplementary reverse osmosis membrane module 8 is connected to the inlet pipe of the liquid to be concentrated. This structure is used to further concentrate the low-pressure brine obtained from the first-stage reverse osmosis membrane module 1, exporting the low-pressure brine and incorporating the concentrate into the liquid to be concentrated. The development valves connected to the low-pressure side interface I4 and low-pressure side interface II5 switch mutually exclusively according to the system's co-current or counter-current flow, allowing the low-pressure brine to pass through the first-stage reverse osmosis membrane module 1.

[0062] The system includes several reverse osmosis membrane modules 1 arranged in series. The liquid to be concentrated flows to each reverse osmosis membrane module 1 in stages, and low brine is separated through the reverse osmosis membranes to concentrate the concentrated water in stages.

[0063] To reduce energy consumption and improve safety, a multi-effect reverse osmosis membrane module 1 is connected in series to perform reverse osmosis at a lower pressure. This reduces the reverse osmosis pressure difference between the high-pressure and low-pressure sides within the same membrane module 1, thereby reducing the corresponding reverse osmosis operating drive force.

[0064] In this application, by setting the switching valve 7 to adjust the flow direction, the flow direction on the low-pressure side is adjusted. The flow direction includes the forward flow and the reverse flow. Among them, the forward flow is the gradual transfer from the first-stage reverse osmosis membrane module 1 to the end reverse osmosis membrane module 1, and the reverse flow is the gradual transfer from the end reverse osmosis membrane module 1 to the first-stage reverse osmosis membrane module 1.

[0065] During this transfer process, on the low-pressure side of each reverse osmosis membrane module 1, the flow directions are opposite to each other. This can reduce the deterioration of the membranes of the reverse osmosis membrane modules 1, playing a role similar to backwashing, substituting washing with this method, reducing the maintenance frequency in an alternating manner of forward and reverse flows, and extending the cleaning and maintenance cycles.

[0066] Example 1:

[0067] The number of reverse osmosis membrane modules 1 is 5.

[0068] Refer to Figure 5 As shown, taking this number as an example:

[0069] The high-salt wastewater is connected to the low-pressure side interface 621 of the forward osmosis membrane module 6 and enters the high-pressure side interface 111 of the first reverse osmosis membrane module through the low-pressure side interface 622 on the other side via a pipeline, and a valve V0 is provided on the pipeline.

[0070] The first reverse osmosis membrane module a, the second reverse osmosis membrane module b, the third reverse osmosis membrane module c, the fourth reverse osmosis membrane module d, and the fifth reverse osmosis membrane module e are connected in series through the high-pressure side interfaces. Specifically, the high-pressure side interface 112 of the first reverse osmosis membrane module a is connected to the high-pressure side interface 211 of the second reverse osmosis membrane module b, the high-pressure side interface 212 of the second reverse osmosis membrane module b is connected to the high-pressure side interface 311 of the third reverse osmosis membrane module c, the high-pressure side interface 312 of the third reverse osmosis membrane module c is connected to the high-pressure side interface 411 of the fourth reverse osmosis membrane module d, the high-pressure side interface 412 of the fourth reverse osmosis membrane module d is connected to the high-pressure side interface 511 of the fifth reverse osmosis membrane module e, the high-pressure side interface 512 of the fifth reverse osmosis membrane module e is connected to the high-pressure side interface 612 of the forward osmosis membrane module 6, and the high-pressure side interface 611 of the forward osmosis membrane module 6 discharges the final concentrated liquid.

[0071] The first reverse osmosis membrane module a, the second reverse osmosis membrane module b, the third reverse osmosis membrane module c, the fourth reverse osmosis membrane module d, and the fifth reverse osmosis membrane module e are connected in series via a low-pressure side interface. Specifically, the low-pressure side interface 122 of the first reverse osmosis membrane module a is connected to the low-pressure side interface 221 of the second reverse osmosis membrane module b via valve V14; the low-pressure side interface 222 of the second reverse osmosis membrane module b is connected to the low-pressure side interface 321 of the third reverse osmosis membrane module c via valve V13; the low-pressure side interface 322 of the third reverse osmosis membrane module c is connected to the low-pressure side interface 421 of the fourth reverse osmosis membrane module d via valve V12; and the low-pressure side interface 422 of the fourth reverse osmosis membrane module d is connected to the low-pressure side interface 521 of the fifth reverse osmosis membrane module e via valve V11.

[0072] The low-pressure side interface 522 is connected to the high-pressure side interface 511 via a pipeline, and the pipeline has a valve V10.

[0073] The low-pressure side interface 522 is connected to the high-pressure side interface 312 via a pipe, and the pipe has a valve V9.

[0074] The low-pressure side interface 422 is connected to the high-pressure side interface 212 via a pipeline, and the pipeline has a valve V7.

[0075] The low-pressure side interface 322 is connected to the high-pressure side interface 112 via a pipeline, and the pipeline has a valve V5.

[0076] The low-pressure side interface 222 is connected to the high-pressure side interface 111 via a pipeline, and the pipeline has a valve V3.

[0077] The high-pressure side interface 112 and the low-pressure side interface 221 are connected, and the pipeline has a valve V2.

[0078] The high-pressure side interface 212 is connected to the low-pressure side interface 321, and the pipeline has a valve V4.

[0079] The high-pressure side interface 312 is connected to the low-pressure side interface 421, and the pipeline has a valve V6.

[0080] The high-pressure side interface 412 is connected to the low-pressure side interface 521, and the pipeline has a valve V8.

[0081] The low-pressure side interfaces 121 and 122 of the first reverse osmosis membrane module a discharge low-salt water through pipelines, and valves V1 and V15 are installed on the two pipelines. The pipelines are respectively connected to the supplementary reverse osmosis membrane module 8. The concentrate outlet of the supplementary reverse osmosis membrane module 8 is connected to the low-pressure side interface 621, and the low-salt water outlet is connected to the low-salt water outlet to enter the next process.

[0082] When switching to downstream flow: open valves V0, V2, V4, V5, V8, V9, V7, V5, V3, and V1, and close the remaining valves.

[0083] When switching to countercurrent flow: Open valves V0, V10, V11, V12, V13, V14, and V15, and close the rest.

[0084] Example 2:

[0085] Refer Figure 6 、 Figure 7 As shown, in some embodiments, it further includes a pressurization component. The pressurization component is provided with a pre-pressurization container 15 on one side of the high-pressure side interface I2 of the reverse osmosis membrane module 1 and a post-pressurization container 16 on one side of the high-pressure side interface II3. The first pipe 9 connecting the pre-pressurization container 15 and the high-pressure side interface I2 is connected through a first switching valve 17, and the first pipe 9 connecting the post-pressurization container 16 and the high-pressure side interface II3 is connected through a second switching valve 18. The first switching valve 17 and the second switching valve 18 are also connected to a sixth pipe 14. The pressure of the liquid is increased by the volume change of the pressurization container. The flow direction of the concentrated water of the reverse osmosis membrane module 1 is adjusted by the switching of the first switching valve 17 and the second switching valve 18. The first switching valve 17 and the second switching valve 18 are two-position four-way valves. The first interface 171 of the first switching valve is connected to the previous stage reverse osmosis membrane module 1, the second interface 172 of the first switching valve is connected to the pre-pressurization container 15, the third interface 173 of the first switching valve is connected to the high-pressure side interface I2 of the reverse osmosis membrane module 1, and the fourth interface 174 of the first switching valve is connected to the sixth pipe 14. The first interface 181 of the second switching valve accesses the high-pressure side interface II3 of the reverse osmosis membrane module 1, the second interface 182 of the second switching valve accesses the post-pressurization container 16, the third interface 183 of the second switching valve accesses the next stage reverse osmosis membrane module 1, and the fourth interface 184 of the second switching valve accesses the sixth pipe 14.

[0086] The first switching valve 17 has two valve positions. In the first valve position 19, the first interface 171 of the first switching valve is connected to the fourth interface 174 of the first switching valve, and the second interface 172 of the first switching valve is connected to the third interface 173 of the first switching valve; in the second valve position 20, the first interface 171 of the first switching valve is connected to the second interface 172 of the first switching valve, and the third interface 173 of the first switching valve is connected to the fourth interface 174 of the first switching valve.

[0087] The second switching valve 18 has two valve positions. In the first valve position 19, the first interface 181 of the second switching valve is connected to the third interface 183 of the second switching valve, and the second interface 182 of the second switching valve is connected to the fourth interface 184 of the second switching valve; in the second valve position 20, the first interface 181 of the second switching valve is connected to the second interface 182 of the second switching valve, and the third interface 183 of the second switching valve is connected to the fourth interface 184 of the second switching valve.

[0088] In the forward flow mode, the liquid enters the reverse osmosis membrane module 1 from the pre-pressurization container 15, and the concentrated brine obtained from the previous effect enters the post-pressurization container 16. The first switching valve 17 is in the first valve position 19, and the second switching valve 18 is in the first valve position 19.

[0089] Conversely, in countercurrent flow, liquid enters the reverse osmosis membrane module 1 from the post-pressurization container 16, and the concentrated brine obtained from the previous effect enters the pre-pressurization container 15. The first switching valve 17 is in the second valve position 20, and the second switching valve 18 is in the second valve position 20.

[0090] Among them, the first switching valve 17 and the second switching valve 18 are solenoid valves. The valve positions are switched based on the front pressure replenishment container 15 and the rear pressure replenishment container 16.

[0091] The pressurization component is disposed outside several reverse osmosis membrane modules 1, or the pressurization component is disposed on several reverse osmosis membrane modules 1 from back to front. This application does not limit this.

[0092] The flow direction through the high-pressure side of the reverse osmosis membrane module is adjusted by switching a two-position four-way valve. The two-position four-way valve is periodically switched, and the period is set to the filling time of the pre-pressurization container 15 or the post-pressurization container 16. The pre-pressurization container 15 and the post-pressurization container 16 are pressurized according to the alternating volume changes of the liquid level.

[0093] The pressurization component functions to replenish pressure and switch between co-current and counter-current flow on the high-pressure and low-pressure sides of the reverse osmosis membrane module 1. Replenishing pressure improves the reverse osmosis efficiency of each reverse osmosis membrane module 1. Switching between co-current and counter-current flow reduces membrane degradation in the reverse osmosis membrane module 1.

[0094] The booster unit employs a dual-breathing mechanism similar to that of birds, switching between forward and reverse flow while boosting pressure.

[0095] The above structure also allows for switching between forward and reverse flow on the high-voltage side, further reducing the number of maintenance operations and extending the maintenance cycle.

[0096] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications may be made without departing from the technical solutions described in the claims.

Claims

1. A variable-stage high-efficiency membrane concentration system, characterized in that, The system includes several reverse osmosis membrane modules, each with a high-pressure side and a low-pressure side. Each reverse osmosis membrane module has a high-pressure side interface I, a high-pressure side interface II, a low-pressure side interface I, and a low-pressure side interface II. The high-pressure sides of adjacent reverse osmosis membrane modules are connected in series via pipes. The liquid to be concentrated passes sequentially through the high-pressure side of each reverse osmosis membrane module, generating low-grade brine on the low-pressure side. The interfaces of adjacent low-pressure sides are connected via pipes, allowing the low-grade brine to pass sequentially through the low-pressure side of each reverse osmosis membrane module. Several switching valves are installed on the pipes, and these valves periodically switch to allow the low-grade brine generated by reverse osmosis to flow either co-currently or counter-currently through each reverse osmosis membrane module. The system includes several reverse osmosis membrane modules arranged in series. The liquid to be concentrated flows to each reverse osmosis membrane module in stages, and low brine is separated through the reverse osmosis membranes to concentrate the concentrated water in stages. To reduce energy consumption and improve safety, a multi-effect reverse osmosis membrane module series structure is adopted to achieve reverse osmosis with a smaller driving force; the osmotic pressure difference between the high-pressure side and the low-pressure side in the same effect reverse osmosis membrane module is reduced, thereby reducing the corresponding reverse osmosis driving resistance; By setting on / off valves to adjust the flow direction, the flow direction on the low-pressure side can be adjusted, including co-current and counter-current flow. Co-current flow involves the flow of brine from the first-effect reverse osmosis membrane module to the terminal reverse osmosis membrane module, while counter-current flow involves the flow of brine from the terminal reverse osmosis membrane module back to the first-effect reverse osmosis membrane module. For the reverse osmosis membrane module, in co-current mode, low-pressure brine flows from low-pressure side interface I to low-pressure side interface II; in counter-current mode, low-pressure brine flows from low-pressure side interface II to low-pressure side interface I. This can reduce the degradation of the reverse osmosis membrane module, playing a role similar to backwashing, using brine instead of washing, and reducing the number of maintenance operations and extending the maintenance and cleaning cycle by alternating co-current and counter-current flow. This method reduces the osmotic pressure difference required for reverse osmosis and reduces energy consumption. High-pressure side interfaces I and II of adjacent reverse osmosis membrane modules are connected via a first pipe, and low-pressure side interfaces I and II of adjacent reverse osmosis membrane modules are connected via a second pipe. The first and second pipes are connected via a third pipe. Switch valves are installed on the second and third pipes, with the third pipe connected downstream of the switch on the second pipe. The high-pressure side interface I of the first-effect reverse osmosis membrane module is directly connected to the water to be concentrated. In co-current mode, the first pipe is connected to the second pipe via the third pipe, and the switch valve on the second pipe disconnects low-pressure side interfaces I and II, thus... The concentrated water from the previous reverse osmosis membrane module simultaneously enters the high-pressure and low-pressure sides of the next reverse osmosis membrane module. This structure reduces the pressure difference between the high-pressure and low-pressure sides, thereby reducing the driving pressure required for ion reverse osmosis. In countercurrent mode, the third tube is closed and the second tube is open, and the flow directions of the concentrated water and the low-salt water are opposite. During the reverse osmosis process, the concentrated water further forward has a lower ion concentration, while the low-salt water further forward has a larger cumulative water volume and a lower ion concentration. This structure is also reasonable and can reduce the ion concentration difference across the reverse osmosis membrane. The low-pressure side interface II of the nth-effect reverse osmosis membrane module is also connected to the first pipe connected to the high-pressure side interface I of the (n-1)th-effect reverse osmosis membrane module via a fourth pipe. The fourth pipe is equipped with a switch valve. When n≥2, the low-pressure side interface I or low-pressure side interface II of the first-effect reverse osmosis membrane module is connected to the system outlet. This structure is used in the co-current mode to incorporate the low-salt water obtained by each effect reverse osmosis membrane module into the concentrate inlet of the previous effect reverse osmosis membrane module, thereby further diluting the concentrate of the previous effect, thereby reducing the ion concentration difference across the membrane and reducing the corresponding resistance. The low-pressure side interface II of the last reverse osmosis membrane module is also connected to a fifth pipe, which is connected to the first pipe of the adjacent reverse osmosis membrane module. The fifth pipe is equipped with a switch valve. This structure has the same function as the aforementioned fourth pipe, which is used to supplement concentrate in the countercurrent flow and reduce resistance. It also includes a forward osmosis membrane module, with the liquid to be concentrated connected to the low-pressure side of the forward osmosis membrane module, and the high-pressure side interface II of the reverse osmosis membrane module at the end connected to the high-pressure side of the forward osmosis membrane module; the water in the liquid to be concentrated is removed through the forward osmosis membrane to increase its concentration. It also includes a supplementary reverse osmosis membrane module. The low-pressure side interface I and low-pressure side interface II of the first-effect reverse osmosis membrane module are respectively connected to the supplementary reverse osmosis membrane module through pipelines. Each pipeline is equipped with a switch valve. The concentrate of the supplementary reverse osmosis membrane module is connected to the inlet pipe of the liquid to be concentrated. The structure is used to further concentrate the low-salt water obtained from the first-effect reverse osmosis membrane module, export the low-salt water, and combine the concentrate into the liquid to be concentrated. It also includes a pressurization assembly, which is set in a pre-pressurization container on the high-pressure side interface I side and a post-pressurization container on the high-pressure side interface II side of the reverse osmosis membrane module. The first pipe connecting the pre-pressurization container and the high-pressure side interface I is connected through a first switching valve, and the first pipe connecting the post-pressurization container and the high-pressure side interface II is connected through a second switching valve. The first and second switching valves are also connected to a sixth pipe. The pressurization container increases the liquid pressure by changing its volume. The flow direction of the concentrate of the reverse osmosis membrane module is adjusted by switching the first and second switching valves. The first and second switching valves are two-position four-way valves. The first port of the first switching valve is connected to the previous effect reverse osmosis membrane module, the second port of the first switching valve is connected to the pre-pressurization container, the third port of the first switching valve is connected to the high-pressure side interface I of the reverse osmosis membrane module, the fourth port of the first switching valve is connected to the sixth pipe, the first port of the second switching valve is connected to the high-pressure side interface II of the reverse osmosis membrane module, the second port of the second switching valve is connected to the post-pressurization container, the third port of the second switching valve is connected to the next effect reverse osmosis membrane module, and the fourth port of the second switching valve is connected to the sixth pipe. The first switching valve has two valve positions. In the first valve position, the first port of the first switching valve is connected to the fourth port of the first switching valve, and the second port of the first switching valve is connected to the third port of the first switching valve. In the second valve position, the first port of the first switching valve is connected to the second port of the first switching valve, and the third port of the first switching valve is connected to the fourth port of the first switching valve. The second switching valve has two valve positions. In the first valve position, the first port of the second switching valve is connected to the third port of the second switching valve, and the second port of the second switching valve is connected to the fourth port of the second switching valve. In the second valve position, the first port of the second switching valve is connected to the second port of the second switching valve, and the third port of the second switching valve is connected to the fourth port of the second switching valve. The function of the pressurization component includes pressurization and switching between co-current and counter-current flow on the high-pressure and low-pressure sides of the reverse osmosis membrane module; pressurization can improve the reverse osmosis efficiency of each reverse osmosis membrane module; switching between co-current and counter-current flow can reduce the degradation of the membrane in the reverse osmosis membrane module. Through the above structure, the high-voltage side can also switch between forward and reverse flow, further reducing the number of maintenance operations and extending the maintenance and cleaning cycle. Specifically, the switching methods using the above systems include: The low-pressure side switching method of the system is as follows: the switching valves on the third and fourth pipes are open, and the switching valves on the second and fifth pipes are closed; the low-pressure side switching method of the system is as follows: the switching valves on the third and fourth pipes are closed, and the switching valves on the second and fifth pipes are open; a first threshold and a second threshold are set; Step 1: Monitor the outflow rate on the low-pressure side of the first-effect reverse osmosis membrane module; Step 2: When the water flow rate falls below the first threshold, switch the system to either forward or reverse flow mode. Step 3: When the water flow rate falls below the second threshold, clean the system. Repeat steps one through three in a loop; It also includes the supplementary reverse osmosis membrane module, and the switching valves connected to the low-pressure side interface I and the low-pressure side interface II switch mutually exclusively according to the system's co-current or counter-current flow, so that low brine passes through the first-stage reverse osmosis membrane module; It also includes the pressurization component, which adjusts the flow direction through the high-pressure side of the reverse osmosis membrane component by switching a two-position four-way valve. The two-position four-way valve switches periodically, and the period is set to the filling time of the pre-pressurization container or the post-pressurization container. The pre-pressurization container and the post-pressurization container are pressurized according to the alternating volume change of the liquid level. The above system uses multi-effect reverse osmosis membrane modules connected in series to form a low-pressure, high-expansion membrane concentration system, which reduces the reverse osmosis ion osmotic pressure difference between the high-pressure and low-pressure sides of each stage, thereby reducing the driving pressure of reverse osmosis operation and the difficulty of concentration, enabling multi-stage high-expansion membrane concentration to be completed at a lower pressure, while reducing energy consumption and improving safety; by switching between forward and reverse flow, the number of maintenance operations is reduced and the maintenance cycle is extended.

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