Reverse osmosis membrane cleaning system and reverse osmosis membrane cleaning method

Abstract

The invention provides a reverse osmosis membrane cleaning system and a reverse osmosis membrane cleaning method.The cleaning system comprises at least one cleaning pipeline, the cleaning pipeline comprises a dosing box, a dosing pump and a membrane assembly which are connected end to end, the dosing box is configured to contain and mix a target solution, and the dosing pump is configured to obtain and convey the target solution from the dosing box; the membrane component comprises a membrane element and a membrane shell, and the membrane shell is used for accommodating the membrane element and a target solution; the cleaning system further comprises a valve assembly, and the valve assembly is opened when the membrane element is cleaned, so that a target solution circulates among the dosing tank, the dosing pump and the membrane assembly; the target solution comprises a cleaning agent and a cleaning solution, the cleaning agent is used for dissolving and removing pollutants on the membrane element, and the cleaning solution is used for washing the dosing box and the membrane element. According to the cleaning system, online cleaning can be carried out on stably-operated equipment of the reverse osmosis membrane system, the cleaning process is simple, the cleaning effect of offline cleaning can be achieved, labor consumption is reduced, and the online cleaning cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a reverse osmosis membrane cleaning system and a reverse osmosis membrane cleaning method. Background Art

[0002] With the continuous development of society and environmental protection technology, the requirements for wastewater treatment are getting higher and higher. The "Water Pollution Prevention and Control Action Plan" ("Water Ten Articles") issued by the state clearly proposed to promote the application of advanced water treatment technology to improve the efficiency of water resource utilization and water quality safety. Membrane separation technology has been widely used in wastewater treatment in the past few decades. The core of the wastewater membrane separation process is the membrane assembly. The membrane assembly acts as a selective barrier in the fluid and uses the different mass transfer rates of different components in the mixture in the membrane to achieve the separation of the mixture. The size of the mixture screened by the membrane assembly is different, and the wastewater membrane separation process is divided into different types such as microfiltration, ultrafiltration, nanofiltration, and reverse osmosis. Reverse osmosis membrane separation technology is a technology that uses a higher pressure than the natural osmotic pressure on the raw water side to penetrate the solvent in the raw water into the dilute solution at the other end of the membrane. Under common operating conditions, it has ultra-high water flux and more than 99% impurity removal rate. It is a crucial technology in the current water treatment process. It has been widely used in seawater desalination, industrial wastewater treatment, drinking water purification and other fields.

[0003] During the operation of the reverse osmosis membrane, the membrane element will be polluted by particulate matter, untreated organic matter, microorganisms and other substances that cannot penetrate the reverse osmosis membrane that may exist in the incoming water. According to the types of substances in the membrane pollution, pollutants can be divided into organic pollution (protein, humus, etc.), inorganic pollution (calcium carbonate, calcium sulfate and metal oxide precipitation, etc.), biological pollution (extracellular polymers, etc.) and colloidal pollution (aluminum silicate, excessive antiscalant, etc.). Usually, the formation process of reverse osmosis membrane pollution is gradual. Controlling membrane pollution as soon as possible can effectively extend the service life of the membrane element. Therefore, regular cleaning and maintenance during the operation of the reverse osmosis membrane is crucial.

[0004] Reverse osmosis membrane cleaning includes online cleaning and offline cleaning. Among them, online cleaning is to clean the membrane element without taking it out of the pressure vessel. The cleaning process is simple and convenient, but the cleaning is not thorough. It is usually used for daily maintenance with light pollution. Offline cleaning is to take the membrane element out of the reverse osmosis equipment and put it into a special cleaning equipment for cleaning. The cleaning effect is obvious, but the removal process is complicated and requires special operators to operate. Summary of the invention

[0005] The object of the present invention is to provide a reverse osmosis membrane cleaning system and a reverse osmosis membrane cleaning method. The cleaning system can perform online cleaning on equipment with stably operating reverse osmosis membrane systems. The cleaning process is simple, which can reduce the labor consumed during offline cleaning of reverse osmosis membranes and reduce the cost of offline cleaning.

[0006] To achieve the above-mentioned object, the present invention provides a reverse osmosis membrane cleaning system, comprising at least one cleaning pipeline, wherein the cleaning pipeline comprises a dosing box, a dosing pump and a membrane assembly connected end to end, wherein the dosing box is configured to contain and mix a target solution, and the dosing pump is configured to obtain and transport the target solution from the dosing box; the membrane assembly comprises a membrane element and a membrane housing, wherein the membrane housing is used to contain the membrane element and the target solution; the cleaning system further comprises a valve assembly, wherein at least part of the valve assembly is used to be opened when the membrane element is cleaned, so that the target solution circulates between the dosing box, the dosing pump and the membrane assembly;

[0007] The target solution includes a cleaning agent and a cleaning liquid. The cleaning agent is used to dissolve and remove pollutants on the membrane element, and the cleaning liquid is used to flush the dosing tank and the membrane element.

[0008] Optionally, each of the cleaning pipelines also includes a connected filter element and a cleaning pump, and the filter element and the cleaning pump are arranged between the dosing pump and the membrane assembly; wherein the filter element is connected to the dosing pump, and the cleaning pump is connected to the membrane assembly; the filter element is configured to remove particulate matter in the cleaning agent, and the cleaning pump is configured to obtain the target solution from the filter element and to transport the target solution to the membrane assembly.

[0009] Optionally, the number of the cleaning pumps and the number of the membrane assemblies are both plural, and the cleaning pump is configured to be connected to a corresponding one of the membrane assemblies and to provide the target solution to the corresponding one of the membrane assemblies.

[0010] Optionally, the number of the cleaning pipelines is at least two, and each of the cleaning pipelines includes the dosing box, the dosing pump, the filter element, the cleaning pump and the membrane assembly connected end to end.

[0011] Optionally, each of the cleaning pipelines includes a plurality of the cleaning pumps and a plurality of membrane assemblies, and each of the membrane assemblies is connected to a corresponding one of the cleaning pumps; all the cleaning pumps on the two cleaning pipelines are respectively connected to the filter element on each of the cleaning pipelines.

[0012] Optionally, the valve assembly includes a first valve, and the first valve is arranged between the dosing tank and the dosing pump.

[0013] Optionally, the valve assembly further includes a second valve, and the second valve is arranged between the cleaning pump and the filter element.

[0014] Optionally, there are multiple cleaning pumps and multiple second valves, and each cleaning pump is connected to the filter element through a corresponding second valve.

[0015] Optionally, the valve assembly further includes a third valve, and the third valve is disposed between the cleaning pump and the membrane assembly.

[0016] Optionally, the valve assembly further includes a fourth valve and a fifth valve; the membrane assembly has a concentrated water outlet and a produced water outlet, the fourth valve is arranged between the concentrated water outlet of the membrane assembly and the drug adding tank, and the fifth valve is arranged between the produced water outlet of the membrane assembly and the drug adding tank.

[0017] Optionally, the reverse osmosis membrane cleaning system also includes a concentrate pool and a production water pool, and the valve assembly also includes a sixth valve and a seventh valve, the sixth valve is arranged between the concentrate outlet of the membrane assembly and the concentrate water pool, and the seventh valve is arranged between the production water outlet of the membrane assembly and the production water pool.

[0018] Optionally, the valve assembly further includes an eighth valve, wherein the eighth valve is disposed between the water production pool and the drug dosing tank, and the water production pool is used to provide the cleaning fluid to the drug dosing tank.

[0019] Optionally, a plurality of control points are provided on the cleaning pipeline, and the control points include one or more of a pressure control node, a temperature control node, a flow control node, a pH detection node and a conductivity detection node.

[0020] Optionally, the temperature control node and / or the PH detection node are provided on the medicine adding box.

[0021] and / or, the pressure control node is disposed on at least one side of the filter element,

[0022] and / or, at least one of the flow control node, the pressure control node and the conductivity detection node is respectively arranged between the cleaning pump and the membrane assembly,

[0023] And / or, at least one of the flow control node, the pressure control node, the pH detection node and the conductivity detection node is respectively provided at the concentrated water outlet and the produced water outlet of the membrane assembly.

[0024] Optionally, the reverse osmosis membrane cleaning system further includes a detection device and a control device, wherein the detection device includes at least one of a pressure monitoring instrument, a pH detection instrument, a temperature monitoring instrument, a flow monitoring instrument, and a conductivity detection instrument; the pressure monitoring instrument, the pH detection instrument, the temperature monitoring instrument, the flow monitoring instrument, or the conductivity detection instrument are respectively connected to the control device;

[0025] The pressure monitoring instrument is used to monitor the pressure value at the pressure detection node, the PH detection instrument is used to detect the PH value at the PH detection node, the temperature monitoring instrument is used to monitor the temperature value at the temperature control node, the flow monitoring instrument is used to monitor the flow value at the flow control node, and the conductivity detection instrument is used to detect the conductivity at the conductivity detection node.

[0026] To achieve the above object, the present invention further provides a reverse osmosis membrane cleaning method, using any one of the reverse osmosis membrane cleaning systems, the reverse osmosis membrane cleaning steps comprising:

[0027] S01, adding cleaning agent into the drug adding box;

[0028] S02, opening the dosing pump and at least part of the valve assembly, and delivering the cleaning agent to the membrane assembly through the dosing pump, so that the membrane element is placed in the membrane housing containing the cleaning agent;

[0029] S03, allowing the cleaning agent to circulate between the dosing tank, the dosing pump and the membrane assembly for a first predetermined time;

[0030] S04, closing the dosing pump and at least part of the valve assembly, so that the membrane element is immersed in the membrane housing filled with the cleaning agent for a second predetermined time;

[0031] S05, discharging the cleaning agent in the cleaning pipeline;

[0032] S06, adding the cleaning solution into the drug adding box;

[0033] S07, turning on the dosing pump and at least part of the valve assembly to allow the cleaning liquid to circulate between the dosing tank, the dosing pump and the membrane assembly until the pH value of the liquid in the membrane assembly reaches a preset range;

[0034] S08, closing the dosing pump and at least part of the valve assembly, and discharging the cleaning liquid in the cleaning pipeline to complete the cleaning of the membrane element.

[0035] Optionally, the cleaning agent includes an alkaline cleaning agent and an acidic cleaning agent;

[0036] In step S01, the step of adding the cleaning agent into the agent adding box includes:

[0037] S011. First, add the alkaline cleaning agent to the dosing box, and execute steps S02 to S07; then add the acidic cleaning agent to the dosing box, and execute steps S02 to S07; thereafter, execute steps S06 to S08 to complete the cleaning of the membrane element.

[0038] Optionally, each of the cleaning pipelines further comprises a filter element and a cleaning pump connected thereto, the filter element is in communication with the dosing pump, and the cleaning pump is in communication with the membrane assembly;

[0039] In step S02 and step S07, the steps before turning on the dosing pump include: turning on the cleaning pump;

[0040] In step S04 and step S08, the step before shutting down the dosing pump includes: shutting down the cleaning pump.

[0041] Optionally, the valve assembly includes a first valve, a second valve, a third valve, a fourth valve and a fifth valve, the first valve is arranged between the dosing tank and the dosing pump, the second valve is arranged between the cleaning pump and the filter element, and the third valve is arranged between the cleaning pump and the membrane assembly; the membrane assembly has a concentrated water end and a produced water end, the fourth valve is arranged between the concentrated water end of the membrane assembly and the dosing tank, and the fifth valve is arranged between the produced water end of the membrane assembly and the dosing tank;

[0042] In step S02 and step S07, the step of opening at least part of the valve assembly includes:

[0043] Open the first valve, the second valve, the third valve, the fourth valve and the fifth valve respectively;

[0044] In step S04 and step S08, the step of closing at least part of the valve assembly includes:

[0045] Close the first valve, the second valve, the third valve, the fourth valve and the fifth valve respectively.

[0046] Optionally, the reverse osmosis membrane cleaning system further includes a concentrated water pool and a produced water pool; the valve assembly further includes a sixth valve and a seventh valve, the sixth valve being arranged between the concentrated water end of the membrane assembly and the concentrated water pool, and the seventh valve being arranged between the produced water end of the membrane assembly and the produced water pool;

[0047] In step S01, the steps before adding the cleaning agent into the dosing box include:

[0048] Open the sixth valve and the seventh valve respectively to discharge the liquid in the membrane module into the concentrated water tank and the produced water tank;

[0049] Step S02 also includes: closing the sixth valve and the seventh valve respectively.

[0050] Optionally, the reverse osmosis membrane cleaning system further comprises a drainage pipeline, and the drainage pipeline is connected to the membrane assembly or the drug adding tank;

[0051] In step S05 and step S08, the step of discharging the cleaning agent or the cleaning liquid in the cleaning pipeline includes: discharging the cleaning agent or the cleaning liquid in the cleaning pipeline through the drainage pipeline.

[0052] Optionally, the reverse osmosis membrane cleaning system further comprises a pH detection instrument, and the pH detection instrument is connected to the membrane assembly;

[0053] Step S03 also includes: detecting the pH value of the liquid at the outlet of the membrane module by the pH detection instrument; if the pH value of the liquid at the outlet of the membrane module is less than a preset value, adding the cleaning agent into the dosing box;

[0054] Step S07 also includes: detecting the pH value of the liquid at the outlet of the membrane module by the pH detection instrument.

[0055] The present invention provides a reverse osmosis membrane cleaning system, which can perform online cleaning on equipment with a reverse osmosis membrane system in stable operation, that is, the system can perform online cleaning on membrane elements without disassembling the membrane elements, and can achieve the cleaning effect of offline cleaning. The cleaning process is simple, avoiding the disassembly process of the membrane element for offline cleaning, reducing the labor consumed in reverse osmosis membrane cleaning, and reducing the cost of online cleaning.

[0056] The present application also provides a reverse osmosis membrane cleaning method, which can perform online cleaning of the membrane element and can sequentially implement the steps of cleaning, soaking and flushing the membrane element, thereby improving the cleaning efficiency and meeting different cleaning requirements of the membrane element. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a process flow chart of a reverse osmosis membrane cleaning system in a preferred embodiment of the present invention, wherein the reverse osmosis membrane cleaning system includes a valve assembly;

[0058] Figure 2 It is a process flow chart of a reverse osmosis membrane cleaning system in a preferred embodiment of the present invention, wherein the reverse osmosis membrane cleaning system includes a control component;

[0059] Figure 3 The present invention is a flowchart of a reverse osmosis membrane cleaning method in a preferred embodiment of the present invention.

[0060] In the figure:

[0061] Dosing box 1; dosing pump 2; membrane assembly 3; concentrate outlet 31; produced water outlet 32; filter element 4; cleaning pump 5; first valve 61; second valve 62; third valve 63; fourth valve 64; fifth valve 65; sixth valve 66; seventh valve 67; eighth valve 68; ninth valve 69; concentrate tank 7; produced water tank 8; pre-treatment water tank 9. DETAILED DESCRIPTION

[0062] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in very simplified form and in non-precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0063] The orientation or position relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientation or position relationship shown in the drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred mechanism or element must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0064] In the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", "fixation" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or a connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] As used in this specification, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0066] The present invention is described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the absence of conflict, the following embodiments and features in the embodiments may complement or be combined with each other.

[0067] Reference Figure 1 As shown, a preferred embodiment of the present invention provides a reverse osmosis membrane cleaning system, including at least one cleaning pipeline, the cleaning pipeline includes a dosing box 1, a dosing pump 2 and a membrane assembly 3 connected end to end, that is, one end of the dosing box 1 is connected to one end of the dosing pump 2, the other end of the dosing pump 2 is connected to one end of the membrane assembly 2, and the other end of the membrane assembly 3 is connected to the other end of the dosing box 1. The dosing box 1 is configured to accommodate and mix the target solution, and the dosing pump 2 is configured to obtain and transport the target solution from the dosing box 1. The membrane assembly 3 includes a membrane element and a membrane housing (not shown), and the membrane housing is used to accommodate the membrane element and the target solution. The cleaning system also includes a valve assembly, at least part of which is used to open when cleaning the membrane element to allow the target solution to circulate between the dosing box 1, the dosing pump 2 and the membrane assembly 3.

[0068] Furthermore, the target solution includes a cleaning agent and a cleaning liquid. The cleaning agent is used to dissolve and remove pollutants on the membrane element, and the cleaning liquid is used to flush the dosing tank 1 and the membrane element 3 .

[0069] It should be noted that membrane elements are used to remove pollutants such as soluble salts, colloids or organic matter in the incoming water. Specifically, the pollutants in the membrane elements include but are not limited to organic pollution (protein, humus, etc.), inorganic pollution (calcium carbonate, calcium sulfate and metal oxide precipitation, etc.), biological pollution (extracellular polymers, etc.) and colloidal pollution (aluminum silicate, excessive antiscalant, etc.).

[0070] It should be known that the above-mentioned cleaning agents include but are not limited to acidic, alkaline or non-oxidizing cleaning agents required in the process of cleaning membrane elements, and the above-mentioned cleaning liquid includes but is not limited to reverse osmosis produced water or pure water. It should be known that the dosing box 1 is configured to provide the cleaning agents used in the online cleaning process to the membrane assembly 3, and provide a place for the configuration of a variety of cleaning agents. The membrane assembly 3 here is a reverse osmosis membrane stable operation equipment, and the membrane element is placed in the membrane housing, and the membrane element is used to filter the incoming water. Generally speaking, the membrane housing used by the membrane assembly 3 can be a reverse osmosis membrane shell commonly used in industrial wastewater treatment projects, and the size can be selected from 80mm*40mm or 40mm*40mm.

[0071] In actual operation, one or more cleaning agents can be added to the dosing box 1. When there are multiple cleaning agents, the dosing box 1 can mix the cleaning agents. After adding the cleaning agents to the dosing box 1, the dosing pump 2 can be turned on. At this time, the cleaning agents can circulate in the membrane assembly 3, the dosing box 1 and the dosing pump 2, thereby cleaning the membrane element.

[0072] The present invention provides a reverse osmosis membrane cleaning system, which can perform online cleaning on equipment with stably operating reverse osmosis membrane systems. That is, the system can perform online cleaning of membrane elements without disassembling the membrane elements, and can achieve the cleaning effect of offline cleaning; the cleaning process is simple, avoiding the disassembly process of membrane elements for offline cleaning, reducing the labor consumed in reverse osmosis membrane cleaning, and reducing the cost of online cleaning.

[0073] Continue to refer to Figure 1 , each cleaning pipeline further includes a connected filter element 4 and a cleaning pump 5, and the filter element 4 and the cleaning pump 5 are arranged between the dosing pump 2 and the membrane assembly 3. The filter element 4 is connected to the dosing pump 2, and the cleaning pump 5 is connected to the membrane assembly 3. The filter element 4 is configured to remove particulate matter in the cleaning agent, and the cleaning pump 5 is configured to obtain the target solution from the filter element 4 and to deliver the target solution to the membrane assembly 3. In other words, the cleaning pump 5 is used to deliver the target solution filtered by the filter element 4 to the membrane assembly 3. The dosing pump 2 is configured to deliver the target solution in the dosing tank 1 to the filter element 4.

[0074] Specifically, after adding the cleaning agent (or cleaning liquid) to the dosing tank 1, the dosing pump 2 and the cleaning pump 5 are turned on, and the cleaning agent (or cleaning liquid) is transported to the filter element 4 under the drive of the dosing pump 2, and the cleaning agent can remove large particle pollutants in the filter element 4. The filtered cleaning agent (or cleaning liquid) is transported to the membrane assembly 3 under the drive of the cleaning pump 5 to clean (or rinse) the membrane assembly 3. Subsequently, the cleaning agent (or cleaning liquid) can flow back from the membrane assembly 3 to the dosing tank 1, and the cycle is repeated.

[0075] It should be understood that the cleaning agent (or cleaning liquid) flowing back from the membrane module 3 to the dosing tank 1 may also include one or more pollutants peeled off from the membrane element.

[0076] In a preferred example, both the dosing pump 2 and the cleaning pump 5 are centrifugal pumps. In another preferred example, the dosing pump 2 and the cleaning pump 5 may also be other types of pump devices.

[0077] Preferably, a stirring device (not shown) is provided in the dosing box 1 to mix the cleaning agent evenly.

[0078] The present application does not limit the type of the filter element 4. In a specific example, the filter element 4 can be set as a security filter, which can be used to remove large particle contaminants in the cleaning agent. In another specific example, the filter element 4 can also be set as other types of filters as needed.

[0079] The present application does not limit the preparation material of the security filter. The security filter is preferably made of a high temperature resistant material, such as polypropylene or polyester high temperature resistant material, but is not limited thereto. The pore size of the security filter can be selected to be 5um.

[0080] In a preferred embodiment, in each cleaning pipeline, the number of cleaning pumps 5 and the number of membrane assemblies 3 are both multiple, and the number of cleaning pumps 5 is preferably the same as the number of membrane assemblies 3. The cleaning pump 5 is configured to be connected to a corresponding membrane assembly 3, and the cleaning pump 5 corresponds to the membrane assembly 3 one by one, and the cleaning pump 5 is used to provide the target solution to the corresponding membrane assembly 3. In this way, the reverse osmosis membrane cleaning system can clean different membrane elements respectively to improve the cleaning efficiency of the membrane assembly 3.

[0081] In this solution, each cleaning pipeline includes a filter element 4, the number of cleaning pumps 5 and the number of membrane components 3 are both multiple, all cleaning pumps 5 are connected to the filter element 4, and the dosing box 1 can provide the target solution to multiple membrane components 3 through the filter element 4.

[0082] Reference Figure 1 As shown, in a preferred embodiment, the reverse osmosis membrane cleaning system includes at least two cleaning pipelines, each of which includes a dosing box 1, a dosing pump 2, a filter element 4, a cleaning pump 5 and a membrane assembly 3 connected end to end. In this way, multiple membrane elements can be cleaned synchronously and independently through multiple cleaning pipelines to improve the cleaning efficiency and meet the different cleaning requirements of multiple membrane elements. For example, when there are multiple membrane elements, daily online cleaning and deep online cleaning can be performed on different membrane elements synchronously to meet the diverse cleaning needs of the membrane elements.

[0083] It should be noted that the reverse osmosis membrane cleaning system can not only perform daily online cleaning of membrane elements, but also perform deep online cleaning of reverse osmosis membranes. The difference between daily online cleaning and deep online cleaning lies in the different cleaning time, cleaning agents or cleaning steps.

[0084] It should also be noted that the number of cleaning pipelines included in the reverse osmosis membrane cleaning system can be set and adjusted according to the number of membrane elements that need to be cleaned. This application does not limit the number of cleaning pipelines in the cleaning system, and the number of cleaning pipelines can be set to 1, 2, 3 or more as needed.

[0085] Reference Figure 1As shown, in a preferred example, there are two cleaning lines, each of which includes a plurality of cleaning pumps 5 and a plurality of membrane modules 3, and each membrane module 3 is connected to a corresponding cleaning pump 5. All cleaning pumps 5 on the two cleaning lines are respectively connected to the filter element 4 on each cleaning line, that is, all cleaning pumps 5 on each cleaning line are respectively connected to the filter element 4 on the first cleaning line and the filter element 4 on the second cleaning line.

[0086] This arrangement enables the filter elements 4 on the two cleaning pipelines to be connected to all membrane assemblies 3. When multiple membrane assemblies 3 need to be cleaned, two membrane assemblies 3 can be connected to different filter elements 4 respectively, and the two cleaning pipelines can be opened at the same time. At this time, the two cleaning pipelines can work independently and realize the synchronous cleaning of the two groups of membrane assemblies 3.

[0087] In a preferred embodiment, the reverse osmosis membrane cleaning system has a daily online cleaning pipeline and a deep online cleaning pipeline. Different membrane components 3 can be simultaneously cleaned online and deeply online through the two cleaning pipelines. For example, while one membrane element is soaked in deep online cleaning, another membrane element can be cleaned online during daily operation. Figure 1 The valve assembly includes a first valve 61, which is arranged between the dosing box 1 and the dosing pump 2 to control the on-off between the dosing box 1 and the dosing pump 2.

[0088] Furthermore, the valve assembly further includes a second valve 62 , which is disposed between the cleaning pump 5 and the filter element 4 to control the on-off connection between the filter element 4 and the cleaning pump 5 .

[0089] In an optional example, in each cleaning pipeline, the second valve 62 is a throttle valve, the number of cleaning pumps 5 and the second valve 62 are both multiple, the number of second valves 62 is preferably the same as the number of cleaning pumps 5, and each cleaning pump 5 is connected to the filter element 4 through a corresponding second valve 62. In this way, multiple membrane assemblies 3 can be connected to one filter element 4. In actual use, the cleaning pump 5 can be connected to the predetermined membrane assembly 3 by opening the second valve 62 between the target cleaning pump 5 and the filter element 4 and closing the second valve 62 between other cleaning pumps 5 and the filter element 4.

[0090] Of course, in other optional examples, in each cleaning pipeline, the number of the cleaning pump 5 and the second valve 62 are both one, and the cleaning pump 5 is connected to the filter element 4 through the second valve 62 .

[0091] In addition, the valve assembly preferably also includes a third valve 63, and a third valve 63 is arranged between the cleaning pump 5 and the membrane assembly 3, that is, the third valve 63 is arranged between a corresponding cleaning pump 5 and a corresponding membrane assembly 3 to control the connection between the corresponding cleaning pump 5 and the membrane assembly 3.

[0092] Preferably, the valve assembly further includes a fourth valve 64 and a fifth valve 65. The membrane assembly 3 has a concentrated water outlet 31 and a produced water outlet 32. The fourth valve 64 is arranged between the concentrated water outlet 31 of the membrane assembly 3 and the dosing tank 1, and the fifth valve 65 is arranged between the produced water outlet 32 ​​of the membrane assembly 3 and the dosing tank 1. With such an arrangement, the membrane assembly 3 can be connected to the dosing tank 1, so that the liquid in the membrane assembly 3 can flow back to the dosing tank 1 through the concentrated water outlet 31 and / or the produced water outlet 32.

[0093] It should be noted that the concentrated water outlet 31 of the membrane assembly 3 is located at one end of the water inlet pipe close to the membrane housing, and the liquid flowing out of the concentrated water outlet 31 is the reverse osmosis concentrated water that is basically not filtered by the membrane element. The produced water outlet 32 ​​of the membrane assembly 3 is located at one end of the water outlet pipe close to or connected to the membrane housing, and the liquid flowing out of the produced water outlet 32 ​​is the reverse osmosis produced water after being filtered by the membrane element.

[0094] Reference Figure 1 As shown, the reverse osmosis membrane cleaning system further includes a concentrate tank 7 and a production water tank 8, and the valve assembly further includes a sixth valve 66 and a seventh valve 67 (i.e., a reflux valve), the sixth valve 66 is arranged between the concentrate outlet 31 of the membrane assembly 3 and the concentrate tank 7, and the seventh valve 67 is arranged between the production water outlet 32 ​​of the membrane assembly 3 and the production water tank 8. The concentrate tank 7 is used to collect the reverse osmosis concentrate discharged from the concentrate outlet 31 of the membrane assembly 3, and the production water tank 8 is used to collect the reverse osmosis production water discharged from the production water outlet 32 ​​of the membrane assembly 3.

[0095] When the membrane element is actually cleaned, the sixth valve 66 and the seventh valve 67 can be opened before adding the cleaning agent into the dosing tank 1, thereby discharging the reverse osmosis concentrated water in the membrane assembly 3 into the concentrated water tank 7, and discharging the reverse osmosis produced water in the membrane assembly 3 into the produced water tank 8.

[0096] More preferably, the valve assembly further includes an eighth valve 68 , which is disposed between the water production pool 8 and the drug adding tank 1 , and the water production pool 8 is used to provide cleaning liquid (ie, reverse osmosis produced water) to the drug adding tank 1 .

[0097] Specifically, when flushing the membrane assembly 3, it is preferred to open the eighth valve 68 to allow the reverse osmosis water in the water production pool 8 to enter the dosing tank 1 and then enter the membrane assembly 3 through the dosing tank 1 to flush the membrane elements.

[0098] As another preferred example, when flushing the membrane assembly 3 , the dosing tank 1 may also be connected to other water supply devices so that cleaning liquid can be added to the dosing tank 1 through the water supply devices.

[0099] In addition, when preparing cleaning agents, the eighth valve 68 can be opened to add the reverse osmosis produced water in the water production pool 8 into the dosing tank 1 to prepare cleaning agents of different concentrations.

[0100] In addition, the reverse osmosis membrane cleaning system also includes a pre-treated water tank 9, and the valve assembly also includes a ninth valve 69 (refer to Figure 1 ), the ninth valve 69 is arranged between the pre-treatment water pool 9 and the membrane assembly 3. The pre-treatment water pool 9 is used to provide the membrane assembly 3 with water to be filtered when the membrane assembly is running stably.

[0101] During the membrane element cleaning process, the third valve 63 and the ninth valve 69 can be opened to allow the target solution to flow into the membrane assembly 3 through the cleaning pump 5. After the membrane element cleaning is completed, the sixth valve 66, the seventh valve 67 and the ninth valve 69 can be opened to allow the membrane assembly 3 to operate stably to filter the incoming water, and to transport the reverse osmosis concentrated water and reverse osmosis produced water (i.e., filtered water) in the membrane assembly 3 to the concentrated water tank 7 and the produced water tank 8, respectively.

[0102] Reference Figure 2 As shown, a plurality of control nodes are arranged on the cleaning pipeline, and the control nodes include one or more of the pressure control node PIC, the temperature control node TIC, the flow control node LIC, the PH detection node YI and the conductivity detection node CI. During actual cleaning, the pressure value, temperature value, PH value, conductivity and flow value of the dosing box 1 or the cleaning pipeline can be detected through the above control nodes.

[0103] Continue to refer to Figure 2 The dosing box 1 is preferably provided with a temperature control node TIC and / or a PH detection node YI, which are used to detect the temperature value and PH value in the dosing box 1 respectively. At least one side of the filter element 4 is preferably provided with a pressure control node PIC, which is used to detect the pressure of the liquid flowing into and / or out of the filter element 4. At least one of a flow control node LIC, a pressure control node PIC and a conductivity detection node CI is preferably provided between the cleaning pump 5 and the membrane assembly 3, which is used to measure the liquid flow, pressure and conductivity flowing into the membrane assembly 3. At least one of a flow control node LIC, a pressure control node PIC, a PH detection node YI and a conductivity detection node CI is preferably provided at the concentrated water outlet 31 and the produced water outlet 32 ​​of the membrane assembly 3, which is used to detect the liquid flow, pressure, PH value and conductivity at the concentrated water outlet 31 and the produced water outlet 32 ​​of the membrane assembly.

[0104] Furthermore, the reverse osmosis membrane cleaning system also includes a detection device and a control device, wherein the detection device includes at least one of a pressure monitoring instrument, a temperature monitoring instrument, a flow meter monitoring instrument, a pH detection instrument, and a conductivity detection instrument. The control device in the present invention can monitor the operating status of the reverse osmosis membrane system and control the conditions during the online cleaning process, so as to facilitate the adjustment of parameters during the cleaning process.

[0105] Among them, the pressure monitoring instrument is used to monitor the pressure value at the pressure detection node PIC, the PH detection instrument is used to detect the PH value at the PH detection node YI, the temperature monitoring instrument is used to monitor the temperature value at the temperature control node TIC, the flow monitoring instrument is used to monitor the flow value at the flow control node LIC, and the conductivity detection instrument is used to detect the conductivity at the conductivity detection node CI, so as to realize the continuous operation status monitoring of the membrane module.

[0106] In more detail, a pressure monitoring instrument may be provided at the pressure control node PIC, a temperature monitoring instrument may be provided at the temperature control node TIC, a flow monitoring instrument may be provided at the flow control node LIC, a PH detection instrument may be provided at the PH detection node YI, and a conductivity detection instrument may be provided at the conductivity detection node CI.

[0107] The pressure control instrument, pH detection instrument, temperature monitoring instrument, flow monitoring instrument or conductivity detection instrument are respectively connected to the control device and used to transmit pressure signals, temperature signals, flow signals, pH signals and conductivity signals to the control device.

[0108] Preferably, the valve assembly is configured as an electric valve and is controlled by a control device. At this time, the control device can also control the opening and closing of each valve according to the pressure signal, the temperature signal and the flow signal.

[0109] Furthermore, the entire control process of the cleaning system is based on various control nodes. In a preferred case, when the pressure control node PIC detects that the pressure value at the outlet of the membrane component 3 has increased by 0.1 to 0.3 MPa compared with the pressure value during stable operation, or when the flow control node LIC detects that the flow value at the water outlet of the membrane component 3 has decreased by more than 15% compared with the flow value during stable operation, the cleaning system will remind the operator to clean the membrane element.

[0110] The pressure monitoring instrument, temperature monitoring instrument, flow monitoring instrument, pH detection instrument and conductivity detection instrument in this application can be controlled by conventional instruments, which will not be described in detail here.

[0111] Furthermore, the reverse osmosis membrane cleaning system also includes a drain pipeline, which is connected to the membrane assembly 3 or the drug adding tank 1 and is used to discharge the target solution in the cleaning pipeline.

[0112] In a specific example, the drainage pipeline is set as an external discharge port (not shown) at the bottom of the dosing tank 1, and the external discharge port is used to discharge the liquid in the dosing tank 1 or the cleaning pipe. In other examples, the drainage pipeline can also be set on the membrane housing.

[0113] Reference Figure 3 As shown, a preferred embodiment of the present invention also provides a reverse osmosis membrane cleaning method, using a reverse osmosis membrane cleaning system, the reverse osmosis membrane cleaning steps include:

[0114] S01, adding cleaning agent into the dosing box 1.

[0115] S02, opening the dosing pump 2 and at least part of the valve assembly, and delivering the cleaning agent to the membrane assembly 3 through the dosing pump 2, so that the membrane element is placed in the membrane housing filled with the cleaning agent.

[0116] S03, making the cleaning agent circulate between the dosing tank 1, the dosing pump 2 and the membrane assembly 3 for a first predetermined time.

[0117] S04, closing the dosing pump 2 and at least part of the valve assembly, so that the membrane element is immersed in the membrane housing filled with the cleaning agent for a second predetermined time.

[0118] S05. Discharge the cleaning agent in the cleaning pipeline.

[0119] S06, adding cleaning liquid into the dosing box 1.

[0120] S07, opening the dosing pump 2 and at least part of the valve assembly, so that the cleaning liquid circulates between the dosing tank 1, the dosing pump 2 and the membrane assembly 3, until the pH value of the liquid in the membrane assembly 3 reaches a preset range.

[0121] S08, closing the dosing pump 2 and at least part of the valve components, and draining the cleaning liquid in the cleaning pipeline to complete the cleaning of the membrane element.

[0122] The present application provides a method for cleaning a reverse osmosis membrane, which can be used for online cleaning of a device with a stable reverse osmosis membrane system, that is, the membrane element can be cleaned online without disassembling the membrane element, and can achieve the cleaning effect of offline cleaning. At the same time, the steps of cleaning, soaking and rinsing the membrane element can be implemented in sequence, which can improve the cleaning efficiency and meet the different cleaning requirements of the membrane element.

[0123] Furthermore, the cleaning agent includes alkaline cleaning agent and acid cleaning agent. The daily online cleaning and deep online cleaning steps of the membrane component include three steps of alkaline cleaning, acid cleaning and flushing in sequence. The type of cleaning agent used when cleaning the membrane element can be determined according to the type of contaminants in the membrane element.

[0124] In step S01, the step of adding cleaning agent to the agent adding box 1 includes:

[0125] S011, first add alkaline cleaning agent to the dosing box 1, and execute steps S02 to S07. Then add acidic cleaning agent to the dosing box 1, and execute steps S02 to S07. After that, execute steps S06 to S08 to complete the cleaning of the membrane element. In this way, all steps of alkaline cleaning, acid cleaning and flushing of the membrane element can be implemented in sequence to ensure the removal of predetermined contaminants on the membrane element, and the alkaline cleaning agent and acidic cleaning agent in the dosing box 1, the membrane assembly 3 and the entire cleaning pipeline can be flushed clean.

[0126] Preferably, each cleaning pipeline further includes a filter element 4 and a cleaning pump 5 connected to each other, the filter element 4 is connected to the dosing pump 2 , and the cleaning pump 5 is connected to the membrane assembly 3 .

[0127] In step S02 and step S07 , the steps before turning on the dosing pump 2 include: turning on the cleaning pump 5 .

[0128] In step S04 and step S08 , the steps before shutting down the dosing pump 2 include: shutting down the cleaning pump 5 .

[0129] Specifically, the dosing pump 2 and the cleaning pump 5 can be turned on when flushing the membrane element after cleaning to achieve the circulation of the cleaning agent and the cleaning liquid in the cleaning pipeline.

[0130] In step S02 and step S07, the step of opening at least part of the valve assembly includes:

[0131] The first valve 61 , the second valve 62 , the third valve 63 , the fourth valve 64 and the fifth valve 65 are opened respectively.

[0132] In step S04 and step S08, the step of closing at least part of the valve assembly includes:

[0133] The first valve 61 , the second valve 62 , the third valve 63 , the fourth valve 64 and the fifth valve 65 are closed respectively.

[0134] Furthermore, the reverse osmosis membrane cleaning system also includes a concentrate tank 7 and a production water tank 8. The valve assembly also includes a sixth valve 66 and a seventh valve 67, wherein the sixth valve 66 is arranged between the concentrate outlet 31 of the membrane assembly 3 and the concentrate tank 7, and the seventh valve 67 is arranged between the production water outlet 31 of the membrane assembly 3 and the production water tank 8.

[0135] Furthermore, in step S01, the steps before adding the cleaning agent into the dosing box 1 include:

[0136] The sixth valve 66 and the seventh valve 67 are opened respectively to discharge the liquid in the membrane module 3 into the concentrated water tank 7 and the produced water tank 8 .

[0137] Step S02 further includes: closing the sixth valve 66 and the seventh valve 67 respectively.

[0138] Furthermore, the reverse osmosis membrane cleaning system also includes a drain pipeline, which is connected to the membrane assembly 3 or the drug adding tank 1 and is used to discharge the target solution in the cleaning pipeline.

[0139] In step S05 and step S08, the step of discharging the cleaning agent or the cleaning liquid in the cleaning pipeline includes: discharging the cleaning agent or the cleaning liquid in the cleaning pipeline through the drainage pipeline.

[0140] In addition, the reverse osmosis membrane cleaning system further comprises a pH detection instrument, which is connected to the membrane assembly 3 .

[0141] Step S03 also includes: detecting the pH value of the liquid at the outlet of the membrane assembly 3 by a pH detection instrument; if the pH value of the liquid at the outlet of the membrane assembly 3 is less than a preset value, adding a cleaning agent to the dosing box 1, so that during the membrane element cleaning process, the pH value of the cleaning agent in the dosing box 1 is always within the preset range.

[0142] Step S07 also includes: detecting the pH value of the liquid at the outlet of the membrane assembly 3 by a pH detection instrument until the pH value of the liquid in the membrane assembly 3 reaches a preset range when the membrane element is flushed, and then executing step S08.

[0143] In a non-limiting embodiment, the entire cleaning process of the membrane element includes the following steps:

[0144] First, before starting to clean the membrane assembly 3, it is necessary to close the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and open the sixth valve 66 and the seventh valve 67 to discharge the liquid in the membrane assembly 3 into the concentrated water tank 8 and the production water tank 9 respectively.

[0145] The membrane elements are then alkaline washed, acid washed and rinsed in turn.

[0146] Generally speaking, the alkaline cleaning process of membrane elements includes: first, circulating an alkaline cleaning agent in the cleaning pipeline to preliminarily dissolve the alkaline soluble contaminants on the membrane elements.

[0147] In a non-limiting embodiment, the specific operation steps include selecting an alkaline cleaning agent according to the type of contaminants on the membrane element to be cleaned.

[0148] First, close the sixth valve 66 and the seventh valve 67, and place the alkaline cleaning agent in the dosing box 1. The alkaline cleaning agent includes surfactants, alkali solution and other ingredients, and the pH of the alkaline cleaning agent is controlled between 10-12. After that, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and extract the alkaline cleaning agent in the dosing box 1 through the dosing pump 2 and transport it to the security filter to remove impurities in the alkaline cleaning agent. Then, the alkaline cleaning agent is transported to the membrane assembly 3 through the cleaning pump 5, and the alkaline cleaning agent circulates in the membrane assembly 3 for the first predetermined time (for example, 0.5h to 2h).

[0149] During the circulation process of the alkaline cleaning agent, the pH change of the alkaline cleaning agent at the concentrated water outlet 31 of the membrane assembly 3 can be detected by a pH detection instrument connected to the membrane assembly 3. When the pH of the alkaline cleaning agent drops below 10, it is necessary to add alkaline cleaning agent to the dosing box 1 to keep the pH between 10 and 12.

[0150] Secondly, the membrane element is soaked in an alkaline cleaning agent to further dissolve some of the contaminants on the membrane element.

[0151] In a non-limiting embodiment, the specific operation steps include: closing the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and soaking the membrane element in the alkaline cleaning agent for a second predetermined time (e.g., 0.5h to 2h) so that the alkaline cleaning agent further dissolves the pollutants on the surface of the membrane element. After soaking for the predetermined time, the liquid in the membrane assembly 3 (i.e., a mixture of pollutants on the membrane element and the alkaline cleaning agent) can be discharged through the drainage pipeline or the concentrated water tank 7.

[0152] The membrane element is then rinsed to remove pollutants and alkaline cleaning agents on the surface of the membrane element.

[0153] In a non-limiting embodiment, the specific operation steps include: opening the eighth valve 68 to add reverse osmosis produced water to the dosing tank 1, flushing the dosing tank 1 with the reverse osmosis produced water, and discharging the flushed liquid through the external discharge port of the dosing tank 1. After the flushing of the dosing tank 1 is completed, the reverse osmosis produced water is added to the dosing tank 1 again, and the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5 are opened to circulate the reverse osmosis produced water in the dosing tank 1 in the cleaning pipeline to flush the membrane element. The flushing time is expected to be 15 minutes to 60 minutes.

[0154] After the predetermined flushing time, the pH value of the reverse osmosis water at the concentrated water outlet 31 of the membrane assembly 3 can be detected by a pH detection instrument connected to the membrane assembly 3. If the pH value of the reverse osmosis water at the concentrated water outlet 31 of the membrane assembly 3 is consistent with the pH value of the reverse osmosis water in the dosing tank 1, the flushing is stopped. After that, the reverse osmosis water in the membrane assembly 3 can be discharged through the drainage pipeline or the concentrated water tank 8 to end the entire alkaline washing process of the membrane element.

[0155] Then the membrane element enters the acid cleaning step. Generally speaking, the acid cleaning process of the membrane element includes: first, circulating the acid cleaning agent in the cleaning pipeline to preliminarily dissolve the acid-soluble contaminants on the membrane element.

[0156] In a non-limiting embodiment, the specific operation steps include selecting an acid cleaning agent according to the type of contaminants on the membrane element to be cleaned. Then, the acid cleaning agent is configured in the dosing box 1. The acid cleaning agent can be selected from HCL, H3PO4, citric acid and other components according to the contamination of the membrane element, and the pH of the acid cleaning agent is controlled between 2-4. After that, the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5 are opened, and the acid cleaning agent in the dosing box 1 is extracted by the dosing pump 2 and transported to the security filter to remove impurities in the acid cleaning agent, and the acid cleaning agent is transported to the membrane assembly 3 by the cleaning pump 5, and the acid cleaning agent is circulated in the membrane assembly 3 for a first predetermined time (for example, 0.5h to 2h).

[0157] During the circulation process of the acid cleaning agent, the pH change of the acid cleaning agent at the concentrated water outlet 31 of the membrane assembly 3 can be detected by a pH detection instrument connected to the membrane assembly 3. When the pH of the acid cleaning agent rises to above 4, it is necessary to add acid cleaning agent in the dosing box 1 to keep the pH between 2 and 4.

[0158] Secondly, the membrane elements are soaked in an acidic cleaning agent to further dissolve the contaminants on the membrane elements.

[0159] In a non-limiting embodiment, the specific operation steps include: closing the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and soaking the membrane element in the acid cleaning agent for a second predetermined time (e.g., 0.5h to 2h) so that the acid cleaning agent further dissolves the pollutants on the surface of the membrane element. After soaking, the liquid in the membrane assembly 3 (i.e., the mixture of pollutants on the membrane element and the acid cleaning agent) can be discharged through the drainage pipeline or the concentrated water tank 8.

[0160] The membrane element is then rinsed to remove pollutants and acidic cleaning agents on the surface of the membrane element.

[0161] In a non-limiting embodiment, the specific operation steps include: opening the eighth valve 68 to add reverse osmosis produced water to the dosing tank 1, flushing the dosing tank 1 with the reverse osmosis produced water, and discharging the flushing liquid through the external discharge port of the dosing tank 1. After the flushing of the dosing tank 1 is completed, the reverse osmosis produced water is added to the dosing tank 1 again, and the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5 are opened to circulate the reverse osmosis produced water in the dosing tank 1 in the cleaning pipeline to flush the membrane element. The flushing time is estimated to be 15 minutes to 60 minutes.

[0162] After the predetermined flushing time, the pH value of the reverse osmosis produced water at the concentrated water outlet 31 of the membrane assembly 3 can be detected by a pH detection instrument connected to the membrane assembly 3. If the pH value of the reverse osmosis produced water at the concentrated water outlet 31 of the membrane assembly 3 is consistent with the pH value of the reverse osmosis produced water in the dosing tank 1, the flushing is stopped. After that, the reverse osmosis produced water in the membrane assembly 3 can be discharged through the drainage pipeline or the concentrated water tank 8 to end the entire acid washing process of the membrane element.

[0163] Then enter the flushing step of the membrane element. Generally speaking, the flushing process of the membrane element includes: first, close all valve components. Then add reverse osmosis product water to the dosing tank 1, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5. When the reverse osmosis water reaches the predetermined flow rate, the reverse osmosis water in the dosing tank 1 is circulated in the cleaning pipeline to perform low-pressure flushing on the membrane element for a predetermined time (for example, 1h to 2h). In order to discharge all the acidic cleaning agents, alkaline cleaning agents and pollutants remaining in the dosing tank 1, the filter element 4 and the membrane assembly 3.

[0164] After the predetermined flushing time, the pH value of the reverse osmosis water at the concentrated water outlet 31 of the membrane assembly 3 can be detected by a pH detection instrument connected to the membrane assembly 3. If the pH value of the reverse osmosis water at the concentrated water outlet 31 of the membrane assembly 3 is consistent with the pH value of the reverse osmosis water in the dosing tank 1, the flushing is completed. If the pH value at the concentrated water outlet 31 of the membrane assembly 3 is different from the pH value of the reverse osmosis water in the dosing tank 1, continue flushing until the pH value at the concentrated water outlet 31 of the membrane assembly 3 is the same as the pH value of the reverse osmosis water in the dosing tank 1. After that, the reverse osmosis water in the membrane assembly 3 can be discharged through the drainage pipeline or the concentrated water tank 8, and the online chemical cleaning of the membrane element is completed.

[0165] The present invention is described in detail below with reference to the accompanying drawings and preferred embodiments.

[0166] <Example 1>

[0167] This embodiment uses a reverse osmosis membrane cleaning system to perform daily online cleaning of the membrane assembly.

[0168] While maintaining the same product water flow rate, the total pressure of the reverse osmosis membrane system increased by 0.15MPa compared to the initial operation, so daily online cleaning is required through the reverse osmosis membrane cleaning system.

[0169] The reverse osmosis membrane cleaning system includes two cleaning pipelines, each of which includes two sets of membrane components. In this reverse osmosis membrane system, the pollutants on the membrane components are mainly organic matter and inorganic salt scale, which need to be removed by online chemical daily cleaning.

[0170] Before online chemical cleaning, the conductivity, flow rate and pressure data of the water inlet, water outlet and concentrate outlet of the reverse osmosis membrane system are obtained through the control device.

[0171] Daily online cleaning of membrane components includes three steps: alkaline cleaning, acid cleaning and flushing.

[0172] The alkaline washing process of the membrane module 3 includes:

[0173] According to the types of pollutants on the membrane elements, 3% NaOH solution and 0.5% EDTA solution are selected as alkaline cleaning agents, the temperature in the dosing box 1 is controlled at about 25°C, and the pH value of the alkaline cleaning agent in the dosing box 1 is controlled at 10-12.

[0174] First, add alkaline cleaning agent into the dosing tank 1, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, remove impurities in the alkaline cleaning agent through the security filter, and circulate the alkaline cleaning agent in the membrane module 3 for 30 minutes. The pH change of the alkaline cleaning agent at the concentrated water outlet 31 of the membrane module 3 is detected by a pH detection instrument connected to the membrane module 3. By adding alkaline cleaning agent into the dosing tank 1, the pH value of the alkaline cleaning agent in the dosing tank 1 is always controlled between 9.5 and 10.5.

[0175] Then, close the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and soak the membrane element in the alkaline cleaning agent for 30 minutes to further dissolve the pollutants on the surface of the membrane element.

[0176] After that, open the eighth valve 68 to add reverse osmosis produced water to the dosing box 1, flush the dosing box 1 with the reverse osmosis produced water, and discharge the flushing liquid through the external discharge port of the dosing box 1. After flushing the dosing box 1, add reverse osmosis produced water to the dosing box 1 again, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and flush the membrane element by circulating the reverse osmosis produced water in the cleaning pipeline until the pH value of the reverse osmosis produced water at the concentrated water outlet 31 of the membrane assembly 3 is consistent with the pH value of the reverse osmosis produced water in the dosing box 1. The flushing time is estimated to be 15 minutes. After flushing, the reverse osmosis produced water in the membrane assembly 3 can be discharged through the drainage pipeline to end the entire alkaline cleaning process of the membrane element.

[0177] The pickling process of membrane module 3 includes:

[0178] According to the types of pollutants on the membrane elements, a citric acid solution with a composition of 1.5% is selected as the pickling cleaning agent, the temperature in the dosing box 1 is controlled at about 25°C, and the pH value of the acid cleaning agent in the dosing box 1 is controlled at 2.5-3.5.

[0179] First, add acid cleaning agent into the dosing tank 1, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, remove impurities in the acid cleaning agent through the security filter, and circulate the acid cleaning agent in the membrane module 3 for 30 minutes. The pH change of the acid cleaning agent at the concentrated water outlet 31 of the membrane module 3 is detected by the pH detection instrument connected to the membrane module 3. By adding acid cleaning agent into the dosing tank 1, the pH of the acid cleaning agent in the dosing tank 1 is always controlled between 2.5 and 3.5.

[0180] Then, close the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and soak the membrane element in the acidic cleaning agent for 30 minutes to further dissolve the pollutants on the surface of the membrane element.

[0181] After that, open the eighth valve 68 to add reverse osmosis produced water to the dosing box 1, flush the dosing box 1 with the reverse osmosis produced water, and discharge the flushing liquid through the external discharge port of the dosing box 1. After the flushing of the dosing box 1 is completed, add reverse osmosis produced water to the dosing box 1 again, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and flush the membrane element by circulating the reverse osmosis produced water in the cleaning pipeline until the pH value of the reverse osmosis produced water at the concentrated water outlet 31 of the membrane assembly 3 is consistent with the pH value of the reverse osmosis produced water in the dosing box 1. The flushing time is expected to be 15 minutes. After flushing, the reverse osmosis produced water in the membrane assembly 3 can be discharged through the drainage pipeline to end the entire acid cleaning process of the membrane element.

[0182] The flushing process of the membrane assembly 3 includes: first, closing all valve assemblies. Then, add reverse osmosis product water to the dosing tank 1, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, so that the reverse osmosis product water in the dosing tank 1 circulates and flushes in the cleaning pipeline for 2 hours to perform low-pressure flushing on the membrane element until the pH value of the reverse osmosis product water at the concentrated water outlet 31 of the membrane assembly 3 is consistent with the pH value of the reverse osmosis product water in the dosing tank 1, and the online chemical cleaning of the membrane element is completed. During the flushing process, the membrane assembly 3 can discharge all the acidic cleaning agents, alkaline cleaning agents and pollutants remaining in the dosing tank 1, the filter element 4 and the membrane assembly 3.

[0183] Subsequently, the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the dosing pump 2 and the cleaning pump 5 are closed, and the sixth valve 66, the seventh valve 67 and the ninth valve 69 are opened to put the reverse osmosis membrane system into operation again.

[0184] The conductivity, flow rate and pressure data of the water inlet, water outlet and concentrated water outlet of the reverse osmosis membrane system after the membrane element is cleaned are obtained through the control device. By comparing with the data before the membrane element is cleaned, it can be seen that after the membrane component 3 is cleaned online chemically, under the condition of inlet water temperature of 25°C, the inlet pressure of the reverse osmosis membrane system is 1.33MPa, the inlet conductivity is 1550μS / cm, the produced water conductivity is 12.9μS / cm, and the desalination rate reaches 99.17%. The inlet pressure and desalination rate of the reverse osmosis membrane system are restored to the normal operating values.

[0185] <Example 2>

[0186] This embodiment uses a reverse osmosis membrane cleaning system to perform deep online cleaning of the membrane assembly.

[0187] While maintaining the same product water flow rate, the total water inlet pressure of the reverse osmosis membrane system increased by 0.25 MPa compared with the initial operation, and the desalination rate dropped significantly (for example, the desalination rate dropped to 96.5%), requiring deep online cleaning by the reverse osmosis membrane cleaning system.

[0188] The reverse osmosis membrane cleaning system includes two cleaning pipelines, each of which includes two sets of membrane components. In this reverse osmosis membrane system, the pollutants on the membrane components are mainly microorganisms, organic matter, and inorganic salt scale, which need to be removed by online chemical deep cleaning.

[0189] Before online chemical cleaning, the conductivity, flow rate and pressure data of the water inlet, water outlet and concentrate outlet of the reverse osmosis membrane system are obtained through the control device.

[0190] The deep online cleaning of membrane components includes three steps: alkaline cleaning, acid cleaning and flushing.

[0191] The alkaline washing process of the membrane module 3 includes:

[0192] According to the types of pollutants on the membrane elements, a 3% NaOH solution is selected as the alkaline cleaning agent, the temperature in the dosing box 1 is controlled at about 30°C, and the pH value of the alkaline cleaning agent in the dosing box 1 is controlled at about 11.

[0193] First, add alkaline cleaning agent into the dosing box 1, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, remove impurities in the alkaline cleaning agent through the security filter, and transport the alkaline cleaning agent to the membrane assembly 3 through the cleaning pump 5, so that the alkaline cleaning agent circulates in the membrane assembly 3 for 2 hours. During the circulation process, the pH change of the alkaline cleaning agent at the concentrated water outlet 31 of the membrane assembly 3 is detected by a pH detection instrument connected to the membrane assembly 3, and the pH of the alkaline cleaning agent in the dosing box 1 is always controlled between 10.5 and 11.5 by adding alkaline cleaning agent into the dosing box 1.

[0194] Then, close the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and soak the membrane element in the alkaline cleaning agent for 20 hours to further dissolve the pollutants on the surface of the membrane element.

[0195] Afterwards, open the eighth valve 68 to add reverse osmosis produced water to the dosing box 1, flush the dosing box 1 with the reverse osmosis produced water, and discharge the flushing liquid through the external discharge port of the dosing box 1. After the flushing of the dosing box 1 is completed, add reverse osmosis produced water to the dosing box 1 again, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and flush the membrane element by circulating the reverse osmosis produced water in the cleaning pipeline until the pH value of the reverse osmosis produced water at the concentrated water outlet 31 of the membrane assembly 3 is consistent with the pH value of the reverse osmosis produced water in the dosing box 1. The flushing time is expected to be 1 hour. After flushing, the reverse osmosis produced water in the membrane assembly 3 can be discharged through the drainage pipeline to end the entire alkaline cleaning process of the membrane element.

[0196] The pickling process of membrane module 3 includes:

[0197] According to the types of pollutants on the membrane element, a 2% citric acid solution is selected as the acid cleaning agent, the temperature in the dosing box 1 is controlled at about 30°C, and the pH value of the acid cleaning agent in the dosing box 1 is controlled at about 2.

[0198] First, add acid cleaning agent into the dosing tank 1, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, remove impurities in the acid cleaning agent through the security filter, and circulate the acid cleaning agent in the membrane module 3 for 2 hours. The pH change of the acid cleaning agent at the concentrated water outlet 31 of the membrane module 3 is detected by the pH detection instrument connected to the membrane module 3. By adding acid cleaning agent into the dosing tank 1, the pH of the acid cleaning agent in the dosing tank 1 is always controlled between 2 and 3.

[0199] Then, close the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and soak the membrane element in the acidic cleaning agent for 20 hours to further dissolve the pollutants on the surface of the membrane element.

[0200] Afterwards, open the eighth valve 68 to add reverse osmosis produced water to the dosing tank 1, flush the dosing tank 1 with the reverse osmosis produced water, and discharge the flushing liquid through the external discharge port of the dosing tank 1. After flushing the dosing tank 1, add reverse osmosis produced water to the dosing tank 1 again, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, and flush the membrane element by circulating the reverse osmosis produced water in the cleaning pipeline until the pH value of the reverse osmosis produced water at the concentrated water outlet 31 of the membrane assembly 3 is consistent with the pH value of the reverse osmosis produced water in the dosing tank 1. The flushing time is expected to be 1 hour. After flushing, the reverse osmosis produced water in the membrane assembly 3 can be discharged through the drainage pipeline to end the entire acid cleaning process of the membrane element.

[0201] The flushing process of the membrane assembly 3 includes: first, closing all valve assemblies. Then, add reverse osmosis product water to the dosing tank 1, open the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the ninth valve 69, the dosing pump 2 and the cleaning pump 5, so that the reverse osmosis product water in the dosing tank 1 circulates and flushes in the cleaning pipeline for 2 hours to perform low-pressure flushing on the membrane element until the pH value of the reverse osmosis product water at the concentrated water outlet 31 of the membrane assembly 3 is consistent with the pH value of the reverse osmosis product water in the dosing tank 1, and the online chemical cleaning of the membrane element is completed. During the flushing process, the membrane assembly 3 can discharge all the acidic cleaning agents, alkaline cleaning agents and pollutants remaining in the dosing tank 1, the filter element 4 and the membrane assembly 3.

[0202] Subsequently, the first valve 61, the second valve 62, the third valve 63, the fourth valve 64, the fifth valve 65, the dosing pump 2 and the cleaning pump 5 are closed, and the sixth valve 66, the seventh valve 67 and the ninth valve 69 are opened to put the reverse osmosis membrane system into operation again.

[0203] The conductivity, flow rate and pressure data of the water inlet, water outlet and concentrated water outlet of the reverse osmosis membrane system after the membrane element is cleaned are obtained through the control device. By comparing with the data before the membrane element is cleaned, it can be seen that after the membrane component 3 is cleaned online chemically, under the condition of an inlet water temperature of 30°C, the inlet pressure of the reverse osmosis membrane system drops to 1.4MPa, the inlet conductivity is 2200μS / cm, the produced water conductivity is 22.7μS / cm, and the desalination rate reaches 98.96%, that is, the inlet pressure and desalination rate of the reverse osmosis membrane system are restored to the normal operating values.

[0204] In summary, the present invention provides a reverse osmosis membrane cleaning system, which can perform online cleaning on equipment with a reverse osmosis membrane system in stable operation, that is, the system can perform online cleaning of membrane elements without disassembling the membrane elements, and can achieve the cleaning effect of offline cleaning. The cleaning process is simple, avoiding the disassembly process of membrane elements for offline cleaning, reducing the labor consumed in reverse osmosis membrane cleaning, and reducing the cost of online cleaning.

[0205] The present application also provides a reverse osmosis membrane cleaning method, which can perform online cleaning of the membrane element and can sequentially implement the steps of cleaning, soaking and flushing the membrane element, thereby improving the cleaning efficiency and meeting different cleaning requirements of the membrane element.

[0206] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the protection scope of the present invention.

Claims

1. A reverse osmosis membrane cleaning system, characterized in that: The cleaning system comprises at least one cleaning pipeline, wherein the cleaning pipeline comprises a dosing box, a dosing pump and a membrane assembly connected end to end, wherein the dosing box is configured to contain and mix a target solution, and the dosing pump is configured to obtain and transport the target solution from the dosing box; the membrane assembly comprises a membrane element and a membrane housing, wherein the membrane housing is used to contain the membrane element and the target solution; the cleaning system further comprises a valve assembly, wherein at least part of the valve assembly is used to be opened when the membrane element is cleaned, so that the target solution circulates between the dosing box, the dosing pump and the membrane assembly; The target solution includes a cleaning agent and a cleaning liquid. The cleaning agent is used to dissolve and remove pollutants on the membrane element, and the cleaning liquid is used to flush the dosing tank and the membrane element.

2. The reverse osmosis membrane cleaning system according to claim 1, characterized in that: Each of the cleaning pipelines also includes a connected filter element and a cleaning pump, and the filter element and the cleaning pump are arranged between the dosing pump and the membrane assembly; wherein the filter element is connected to the dosing pump, and the cleaning pump is connected to the membrane assembly; the filter element is configured to remove particulate matter in the cleaning agent, and the cleaning pump is configured to obtain the target solution from the filter element and to transport the target solution to the membrane assembly.

3. The reverse osmosis membrane cleaning system according to claim 2, characterized in that: The number of the cleaning pumps and the number of the membrane modules are both plural, and the cleaning pump is configured to be connected to a corresponding one of the membrane modules and used to provide the target solution to the corresponding one of the membrane modules.

4. The reverse osmosis membrane cleaning system according to claim 2, characterized in that: The number of the cleaning pipelines is at least two, and each of the cleaning pipelines includes the dosing box, the dosing pump, the filter element, the cleaning pump and the membrane assembly connected end to end.

5. The reverse osmosis membrane cleaning system according to claim 4, characterized in that: Each of the cleaning pipelines comprises a plurality of cleaning pumps and a plurality of membrane assemblies, and each of the membrane assemblies is connected to a corresponding cleaning pump; all the cleaning pumps on the two cleaning pipelines are respectively connected to the filter element on each of the cleaning pipelines.

6. The reverse osmosis membrane cleaning system according to any one of claims 1 to 5, characterized in that: The valve assembly includes a first valve, which is arranged between the dosing tank and the dosing pump.

7. The reverse osmosis membrane cleaning system according to any one of claims 2 to 5, characterized in that: The valve assembly further includes a second valve disposed between the cleaning pump and the filter element.

8. The reverse osmosis membrane cleaning system according to claim 7, characterized in that: There are multiple cleaning pumps and multiple second valves, and each cleaning pump is connected to the filter element through a corresponding second valve.

9. The reverse osmosis membrane cleaning system according to any one of claims 2 to 5, characterized in that: The valve assembly further comprises a third valve, and the third valve is arranged between the cleaning pump and the membrane assembly.

10. The reverse osmosis membrane cleaning system according to any one of claims 1 to 5, characterized in that: The valve assembly also includes a fourth valve and a fifth valve; the membrane assembly has a concentrated water outlet and a produced water outlet, the fourth valve is arranged between the concentrated water outlet of the membrane assembly and the drug adding tank, and the fifth valve is arranged between the produced water outlet of the membrane assembly and the drug adding tank.

11. The reverse osmosis membrane cleaning system according to claim 10, characterized in that: It also includes a concentrated water pool and a produced water pool. The valve assembly also includes a sixth valve and a seventh valve. The sixth valve is arranged between the concentrated water outlet of the membrane assembly and the concentrated water pool, and the seventh valve is arranged between the produced water outlet of the membrane assembly and the produced water pool.

12. The reverse osmosis membrane cleaning system according to claim 10, characterized in that: The valve assembly further includes an eighth valve, which is disposed between the water production pool and the drug adding tank. The water production pool is used to provide the cleaning fluid to the drug adding tank.

13. The reverse osmosis membrane cleaning system according to any one of claims 2 to 5, characterized in that: A plurality of control nodes are arranged on the cleaning pipeline, and the control nodes include one or more of a pressure control node, a temperature control node, a flow control node, a PH detection node and a conductivity detection node.

14. The reverse osmosis membrane cleaning system according to claim 13, characterized in that: The temperature control node and / or the PH detection node are arranged on the medicine adding box. and / or, the pressure control node is disposed on at least one side of the filter element, and / or, at least one of the flow control node, the pressure control node and the conductivity detection node is respectively arranged between the cleaning pump and the membrane assembly, And / or, at least one of the flow control node, the pressure control node, the pH detection node and the conductivity detection node is respectively provided at the concentrated water outlet and the produced water outlet of the membrane assembly.

15. The reverse osmosis membrane cleaning system according to claim 13, characterized in that: It also includes a detection device and a control device, wherein the detection device includes at least one of a pressure monitoring instrument, a pH detection instrument, a temperature monitoring instrument, a flow monitoring instrument, and a conductivity detection instrument; The pressure control instrument, the pH detection instrument, the temperature monitoring instrument, the flow monitoring instrument or the conductivity detection instrument are respectively connected to the control device; The pressure monitoring instrument is used to monitor the pressure value at the pressure detection node, the PH detection instrument is used to detect the PH value at the PH detection node, the temperature monitoring instrument is used to monitor the temperature value at the temperature control node, the flow monitoring instrument is used to monitor the flow value at the flow control node, and the conductivity detection instrument is used to detect the conductivity at the conductivity detection node.

16. A method for cleaning a reverse osmosis membrane, characterized in that: Using the reverse osmosis membrane cleaning system according to any one of claims 1 to 15, the reverse osmosis membrane cleaning step comprises: S01, adding cleaning agent into the drug adding box; S02, opening the dosing pump and at least part of the valve assembly, and delivering the cleaning agent to the membrane assembly through the dosing pump, so that the membrane element is placed in the membrane housing containing the cleaning agent; S03, allowing the cleaning agent to circulate between the dosing tank, the dosing pump and the membrane assembly for a first predetermined time; S04, closing the dosing pump and at least part of the valve assembly, so that the membrane element is immersed in the membrane housing filled with the cleaning agent for a second predetermined time; S05, discharging the cleaning agent in the cleaning pipeline; S06, adding the cleaning solution into the drug adding box; S07, turning on the dosing pump and at least part of the valve assembly to allow the cleaning liquid to circulate between the dosing tank, the dosing pump and the membrane assembly until the pH value of the liquid in the membrane assembly reaches a preset range; S08, closing the dosing pump and at least part of the valve assembly, and discharging the cleaning liquid in the cleaning pipeline to complete the cleaning of the membrane element.

17. The reverse osmosis membrane cleaning method according to claim 16, characterized in that: The cleaning agent includes an alkaline cleaning agent and an acidic cleaning agent; In step S01, the step of adding the cleaning agent into the agent adding box includes: S011, first add the alkaline cleaning agent into the dosing box, and execute steps S02 to S07; Then, the acid cleaning agent is added into the drug adding box, and steps S02 to S07 are performed; thereafter, steps S06 to S08 are performed to complete the cleaning of the membrane element.

18. The reverse osmosis membrane cleaning method according to claim 16, characterized in that: Each of the cleaning pipelines further comprises a filter element and a cleaning pump connected thereto, wherein the filter element is in communication with the dosing pump, and the cleaning pump is in communication with the membrane assembly; In step S02 and step S07, the steps before turning on the dosing pump include: turning on the cleaning pump; In step S04 and step S08, the step before shutting down the dosing pump includes: shutting down the cleaning pump.

19. The reverse osmosis membrane cleaning method according to claim 18, characterized in that: The valve assembly includes a first valve, a second valve, a third valve, a fourth valve and a fifth valve, wherein the first valve is arranged between the dosing tank and the dosing pump, the second valve is arranged between the cleaning pump and the filter element, and the third valve is arranged between the cleaning pump and the membrane assembly; the membrane assembly has a concentrated water end and a produced water end, the fourth valve is arranged between the concentrated water end of the membrane assembly and the dosing tank, and the fifth valve is arranged between the produced water end of the membrane assembly and the dosing tank; In step S02 and step S07, the step of opening at least part of the valve assembly includes: Open the first valve, the second valve, the third valve, the fourth valve and the fifth valve respectively; In step S04 and step S08, the step of closing at least part of the valve assembly includes: Close the first valve, the second valve, the third valve, the fourth valve and the fifth valve respectively.

20. The reverse osmosis membrane cleaning method according to claim 19, characterized in that: The reverse osmosis membrane cleaning system further includes a concentrated water pool and a produced water pool; the valve assembly further includes a sixth valve and a seventh valve, the sixth valve being arranged between the concentrated water outlet of the membrane assembly and the concentrated water pool, and the seventh valve being arranged between the produced water outlet of the membrane assembly and the produced water pool; In step S01, the steps before adding the cleaning agent into the dosing box include: Open the sixth valve and the seventh valve respectively to discharge the liquid in the membrane module into the concentrated water tank and the produced water tank; Step S02 also includes: closing the sixth valve and the seventh valve respectively.

21. The reverse osmosis membrane cleaning method according to claim 16, characterized in that: The reverse osmosis membrane cleaning system further comprises a liquid discharge pipeline, which is connected to the membrane assembly or the drug adding tank; In step S05 and step S08, the step of discharging the cleaning agent or the cleaning liquid in the cleaning pipeline includes: discharging the cleaning agent or the cleaning liquid in the cleaning pipeline through the drainage pipeline.

22. The reverse osmosis membrane cleaning method according to claim 16, characterized in that: The reverse osmosis membrane cleaning system also includes a pH detection instrument, which is connected to the membrane assembly; Step S03 also includes: detecting the pH value of the liquid at the outlet of the membrane module by the pH detection instrument; if the pH value of the liquid at the outlet of the membrane module is less than a preset value, adding the cleaning agent into the dosing box; Step S07 also includes: detecting the pH value of the liquid at the outlet of the membrane module by the pH detection instrument.

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