Magnetic fluid assisted reverse osmosis membrane cleaning equipment and method

Abstract

The invention relates to magnetic fluid assisted reverse osmosis membrane cleaning equipment and method, and belongs to the technical field of water treatment. The equipment comprises a frame body which is provided with a plurality of stations used for installing reverse osmosis membrane assemblies, and the stations are arranged around the central axis of the frame body in an array mode; the magnetofluid storage device is used for storing two magnetofluid finished products suitable for acidic and alkaline cleaning environments; the magnetic fluid director is used for injecting the magnetic fluid with the corresponding property into the reverse osmosis membrane; the core rod is made of a magnetic conductive material and is arranged in the middle of each station along the horizontal direction of the frame body; the electromagnetic coil is located on the outer side of the frame body, coaxially connected with the core rod, capable of moving in the axis direction and connected with a variable alternating current power supply, and the magnetic field intensity and direction are controlled by adjusting current. The magnetic fluid is driven to quickly vibrate and scrub in the reverse osmosis membrane by adjusting the current intensity and the moving direction of the electromagnetic coil, so that the membrane cleaning process is enhanced, the membrane cleaning efficiency is improved, the use amount of chemical agents is reduced, and the service life of the reverse osmosis membrane is prolonged.

Description

Technical Field

[0001] The present application relates to the field of water treatment, and in particular to a magnetic fluid-assisted reverse osmosis membrane cleaning device and method. Background Art

[0002] Reverse osmosis technology has been widely used in the fields of seawater desalination, wastewater treatment and drinking water purification. Reverse osmosis membrane is a semi-permeable membrane. As the core component of membrane filtration technology, it can remove dissolved salts and other impurities in water to obtain high-quality pure water. The reverse osmosis membrane assembly is composed of a certain number of reverse osmosis membrane elements and a pressure vessel. The pressure vessel is composed of two side end covers and a pressure-resistant membrane shell in the middle. However, the reverse osmosis membrane is easily contaminated by microorganisms and inorganic substances. During long-term use, it will lead to problems such as decreased filtration performance of the reverse osmosis membrane assembly, increased operating pressure of the reverse osmosis membrane system, and increased energy consumption of the seawater desalination process.

[0003] In order to solve the problem of reverse osmosis membrane pollution, when the transmembrane pressure difference of the reverse osmosis membrane increases to a certain extent, a membrane cleaning method is needed to restore the water production performance of the reverse osmosis membrane. The traditional seawater desalination reverse osmosis membrane cleaning method mainly includes physical cleaning and chemical cleaning processes. Physical cleaning usually uses low-pressure water washing, but water washing alone has limited effect on removing stubborn dirt; chemical cleaning uses chemical reagents such as acid and alkali to clean the membrane. The conventional reverse osmosis membrane cleaning process is: (1) water washing, the washing time is based on the complete replacement of the concentrated water or waste liquid of the reagent in the membrane with product water; (2) acid washing, the acid reagent circulates in the reverse osmosis membrane for 10 hours, and the reagent needs to be replenished when the reagent concentration decreases; (3) water washing; (4) alkali washing, the alkaline reagent circulates in the reverse osmosis membrane for 10 hours, and the reagent needs to be replenished when the reagent concentration decreases; (5) water washing; (6) alkali washing; (7) water washing; (8) acid washing; (9) water washing. It can be seen that due to the poor cleaning effect of low-pressure water flushing and chemical agent circulation flushing, the conventional seawater desalination reverse osmosis membrane cleaning process has problems such as long cleaning time, large amount of agent usage, and high energy consumption; especially during the long-term agent immersion process, the agent may cause permanent damage to the reverse osmosis membrane material and reduce the filtration performance of the reverse osmosis membrane. At the same time, due to the different degrees of contamination of the front-end membrane elements and the rear-end membrane elements of the reverse osmosis membrane assembly in actual operation, when the membrane is cleaned, the pollutants of the front-end membrane elements of the reverse osmosis membrane assembly will be transported to the rear-end membrane elements along with the flushing water and agents, causing the rear-end membrane elements to be contaminated, increasing the difficulty of cleaning and reducing the cleaning efficiency. Therefore, it is necessary to develop a new auxiliary cleaning method to improve the cleaning efficiency of the reverse osmosis membrane assembly, reduce the amount of agents used, and extend the service life of the reverse osmosis membrane.

[0004] Magnetic fluid is a liquid with magnetic nanoparticles suspended in it. Under the action of an external magnetic field, it can flow, rotate, vibrate, and generate mechanical force on the surface to be cleaned. When magnetic fluid is introduced into the cleaning process of the reverse osmosis membrane assembly, the distribution and movement state of the magnetic fluid are controlled by an external magnetic field. With the help of the rapid movement and vibration of the magnetic fluid in the reverse osmosis membrane, a front and back segmented cleaning method is adopted to improve the cleaning efficiency of pollutants on the membrane surface. Compared with conventional membrane cleaning methods, the magnetic fluid-assisted membrane cleaning method reduces the use of chemical cleaning agents and the cleaning time of the reverse osmosis membrane, reduces damage to the reverse osmosis membrane material, prolongs the life of the membrane, and improves production efficiency. It is of great significance to energy saving, consumption reduction, cost reduction and efficiency improvement of seawater desalination plants.

[0005] Against the above background, the present application proposes a magnetic fluid-assisted reverse osmosis membrane cleaning device and method, which aims to drive the magnetic fluid to move and vibrate rapidly in the reverse osmosis membrane by adjusting the current and movement direction of the electromagnetic coil, thereby enhancing the cleaning process of the reverse osmosis membrane, improving the membrane cleaning efficiency, reducing the use of chemical agents, and extending the service life of the reverse osmosis membrane. Summary of the invention

[0006] In order to solve the problems in the background technology, the present application provides a magnetic fluid assisted reverse osmosis membrane cleaning device and method.

[0007] The present application provides a magnetic fluid assisted reverse osmosis membrane cleaning device, which adopts the following technical solution: A magnetic fluid-assisted reverse osmosis membrane cleaning device comprises: a frame body, provided with a plurality of workstations for installing reverse osmosis membrane components, each workstation being arranged in an array around a horizontal axis of the frame body; The magnetic fluid storage device has two cavities formed inside for storing two kinds of finished magnetic fluids suitable for acidic and alkaline cleaning environments. The finished magnetic fluids are prepared by mixing magnetic fluid base particles and other substances used to mix magnetic fluids. During cleaning, the storage port storing the magnetic fluids of corresponding properties is opened according to the acidic or alkaline environment corresponding to the cleaning process; A magnetic fluid deflector, at least two of which are arranged at each station of the frame corresponding to the frame, each of which is connected to a magnetic fluid reservoir, and each of which can be connected to a reverse osmosis membrane assembly installed at a corresponding station of the frame, and two magnetic fluid deflectors arranged at the same station of the frame can respectively inject magnetic fluid into the reverse osmosis membrane assembly from both ends thereof; The core rod is arranged at the middle position of each workstation of the frame, and the length direction of the core rod is arranged along the horizontal axis direction of the frame, and the core rod is made of magnetic conductive material; The electromagnetic coil is arranged outside each station of the frame corresponding to itself. The central axis of the electromagnetic coil can be arranged in line with the length direction of the core rod. The electromagnetic coil is also connected to a variable AC power supply. Changing the current of the variable AC power supply can adjust the strength of the magnetic field generated by the electromagnetic coil. Changing the current direction of the variable AC power supply can adjust the direction of the magnetic field generated by the electromagnetic coil. The electromagnetic coil is movably connected to the frame. The electromagnetic coil can move along the horizontal axis of the frame. The movement of the electromagnetic coil can drive the magnetic fluid in the reverse osmosis membrane assembly of each station of the frame to move accordingly. The variable AC power supply can adjust the vibration amplitude and vibration frequency of the magnetic fluid in the electromagnetic coil by adjusting the current. By adopting the above technical solution, the magnetic fluid can achieve precise movement and vibration in the reverse osmosis membrane under the action of the magnetic field generated by the electromagnetic coil, thereby effectively removing pollutants attached to the membrane surface and improving the cleaning efficiency.

[0008] Preferably, each pressure-resistant membrane shell at each workstation position of the rack is provided with two relatively arranged pressure-resistant membrane shell end covers, and any two relatively arranged pressure-resistant membrane shell end covers are arranged as a pressure-resistant membrane shell end cover group, and each of the pressure-resistant membrane shell end cover groups can jointly seal the reverse osmosis membrane assembly setting of the corresponding workstation of the rack with the pressure-resistant membrane shell, and when performing magnetic fluid-assisted cleaning, each pressure-resistant membrane shell end cover group and the pressure-resistant membrane shell seal the corresponding reverse osmosis membrane element setting.

[0009] Preferably, the magnetic fluid configuration process used in the magnetic fluid storage device under the pickling cleaning environment is: Fe3+ and Fe2+ are prepared into a solution in a molar ratio of 1:1.5-2, and concentrated ammonia water is added thereto until a black precipitate is completely formed, thereby obtaining a first black precipitate solution; The obtained first black precipitate solution is quickly heated to 80-100° C., and oleic acid and low-carbon alkanes are added thereto, and stirred until the solution is obviously separated into layers, and a magnetic fluid liquid is obtained by a magnetic decantation method, and the magnetic fluid liquid is centrifuged, washed with deionized water, flocculated with an organic solvent, and then low-temperature vacuum dried to obtain a single-layer coated magnetic powder; Weigh the single-layer coated magnetic powder obtained in step 1, add the single-layer coated magnetic powder to the base liquid at room temperature, stir and disperse until there is no precipitation, and then centrifuge. The liquid poured out after centrifugation is the magnetic fluid. Preferably, the magnetic fluid configuration process used in the magnetic fluid reservoir under the alkaline cleaning environment is: Fe3+ and Fe2+ are prepared into a solution in a molar ratio of 1:1.5-2, and concentrated ammonia water is added thereto until a black precipitate is completely formed, thereby obtaining a first black precipitate solution; The obtained first black precipitate solution is quickly heated to 80-100° C., and oleic acid and low-carbon alkanes are added thereto, and stirred until the solution is obviously separated into layers, and a magnetic fluid liquid is obtained by a magnetic decantation method, and the magnetic fluid liquid is centrifuged, washed with deionized water, flocculated with an organic solvent, and then low-temperature vacuum dried to obtain a single-layer coated magnetic powder; Weigh the obtained single-layer coated magnetic powder, stir and disperse the single-layer coated magnetic powder in the intermediate liquid at room temperature to obtain a second intermediate solution, and quickly raise the temperature of the second intermediate solution to 140-170°C, then add polyisobutylene succinimide and base carrier liquid, stir and mix evenly, and cool to room temperature after the intermediate liquid is completely volatilized, and then centrifuge. The liquid poured out after centrifugation is the magnetic fluid. Magnetic fluids with specific properties can be customized according to actual cleaning needs to improve the cleaning effect.

[0010] Preferably, the recovery device is used to recover the magnetic fluid after auxiliary cleaning, and the recovery device includes a recovery pipeline, each recovery pipeline can be connected to the concentrated brine discharge port of each pressure-resistant membrane shell, and each recovery pipeline is provided with a closed valve at one end close to the pressure-resistant membrane shell end cover, and each closed valve can close the corresponding recovery pipeline setting; a recovery bin is provided, and each recovery pipeline is provided with a plurality of electromagnet rings at the position corresponding to its own recovery bin, and the electromagnet ring is coated on the outer side of the corresponding recovery bin along the length direction of the recovery bin, and the cleaning waste liquid of the reverse osmosis membrane is discharged into the recovery pipeline along the concentrated brine discharge port, and the magnetic fluid base particles therein are adsorbed on the inner wall of the recovery bin under the action of the electromagnet ring, so as to achieve separation from other cleaning waste liquids, thereby achieving separation from other cleaning liquids. Pressure-resistant membrane shell end cover Pressure-resistant membrane shell end cover Pressure-resistant membrane shell end cover Pressure-resistant membrane shell end cover The pressure-resistant membrane shell end cover realizes the recycling of resources. By setting a recovery device, the magnetic fluid after cleaning can be recycled and reused, reducing resource consumption and cost.

[0011] Preferably, it also includes a leak detection device, which is used to detect whether the reverse osmosis membrane assembly has structural damage, specifically to detect whether there is magnetic fluid in the cleaning liquid discharged from the water outlet of the reverse osmosis membrane assembly after cleaning, and it includes multiple leak detection pipelines, each of which can be connected to the water outlet of the reverse osmosis membrane assembly installed at each station of the frame, and each leak detection pipeline is connected to the corresponding pressure-resistant membrane shell end cover, and each leak detection pipeline is connected to a closed valve near the position of the pressure-resistant membrane shell end cover, and each closed valve can close the corresponding leak detection pipeline setting, and each leak detection pipeline is provided with a magnetic flux sensor. If the magnetic flux of the magnetic flux sensor changes when the cleaning liquid passes through the leak detection pipeline, it means that there is magnetic fluid mixed therein, thereby judging that there is structural damage inside the reverse osmosis membrane assembly, and preventing the magnetic fluid from flowing out with the cleaning liquid. By adding a leak detection device, the integrity of the reverse osmosis membrane can be monitored in real time during the cleaning process, and structural damage problems can be discovered and handled in time to ensure the safe operation of the equipment.

[0012] Preferably, each station is provided with a fixture for fixing the reverse osmosis membrane assembly, the fixture is detachably connected to the frame, and the fixture is made of non-metallic material. By using a fixture made of non-metallic material to fix the reverse osmosis membrane, unnecessary damage to the reverse osmosis membrane during the cleaning process can be effectively prevented.

[0013] Preferably, it also includes a detection component for detecting the content of the agent in the reverse osmosis membrane component during the cleaning process, including: The sampling tubes are arranged one by one on the end covers of the pressure-resistant membrane shells, and each sampling tube can be connected to the corresponding reverse osmosis membrane assembly; A plurality of probes are provided, each of the probes being arranged one by one at the rear end of each of the sampling tubes (92); during detection, the sampling tube (92) is opened, and the outflow liquid of the sampling tube is detected by the probe to measure the pH value and conductivity of the liquid in the reverse osmosis membrane assembly; The detection control module is electrically connected to each of the probes. The detection control module determines the concentration of the drug solution according to the changes in the pH value and conductivity of the drug solution in each reverse osmosis membrane assembly, and further determines whether the drug solution needs to be supplemented.

[0014] Preferably, it also includes a control system, which is used to control the cleaning process of the reverse osmosis membrane assembly to achieve automation, and the control system includes: The controller sends a signal to start cleaning. The electromagnetic coil is electrically connected to the controller, and the controller can control the movement of the electromagnetic coil; the variable AC power supply is also electrically connected to the controller, and the controller can control the current size and direction of the variable AC power supply; the magnetic fluid deflector is also electrically connected to the controller, and the controller controls the magnetic fluid in the magnetic fluid reservoir to be injected into the reverse osmosis membrane assembly of the corresponding station; The time relay is connected to the controller and is used to measure the execution time of each step.

[0015] A magnetic fluid-assisted reverse osmosis membrane cleaning device and method, applicable to the above-mentioned reverse osmosis membrane cleaning device, comprising: S1: Install the reverse osmosis membrane assembly at each workstation of the frame (1), fix it with a clamp (11), inject raw water into it through the raw water inlet, filter it through the reverse osmosis membrane assembly, and then discharge the pure water through the water outlet through the leak detection pipeline, and discharge the concentrated brine through the concentrated brine outlet of the reverse osmosis membrane assembly through the recovery pipeline, and shut down for cleaning after a fixed operation period; S2: Inject produced water into the reverse osmosis membrane assembly to replace the concentrated brine remaining in the reverse osmosis membrane assembly with the produced water; S3: drain the cleaning water, inject cleaning liquid into the reverse osmosis membrane assembly to pre-treat the pollutants therein, and soak for a period of time to soften the pollutants; S4: injecting magnetic fluid into the front end of the reverse osmosis membrane assembly through the magnetic fluid guide; S5: Control the electromagnetic coil to move repeatedly within the range of the first three membranes of the reverse osmosis membrane assembly along the length direction of the reverse osmosis membrane assembly, and repeatedly change the current direction and magnitude of the variable AC power supply during this process. When the electromagnetic coil moves close to the third membrane of the reverse osmosis membrane assembly, the magnetic fluid is injected into the rear end of the reverse osmosis membrane assembly through the magnetic fluid guide, and the magnetic fluid is driven by another electromagnetic coil to move toward the fourth membrane of the reverse osmosis membrane assembly, so that a certain distance is always maintained between the two electromagnetic coils. The two electromagnetic coils move back and forth to drive the magnetic fluid to scrape and wash the inside of the reverse osmosis membrane assembly. S6: Open the closed valve in the recovery pipeline connected to the front end of each reverse osmosis membrane module, discharge the cleaning liquid and magnetic fluid used to clean the first three membranes of each reverse osmosis membrane module from the concentrated brine discharge port at the front end of the reverse osmosis membrane module, and discharge the magnetic fluid and cleaning liquid of the last four membranes inside the reverse osmosis membrane module from the concentrated brine discharge port at the end of the reverse osmosis membrane module into the recovery pipeline; S7: injecting clean water from the water inlet of each reverse osmosis membrane assembly through the reverse osmosis membrane assembly self-cleaning system to flush the residual liquid medicine and magnetic fluid in each reverse osmosis membrane assembly to the outside of the reverse osmosis membrane assembly; S8: Recover the magnetic fluid base particles stored in the recovery bin installed in the recovery pipeline. The recovered magnetic fluid base particles and other materials used to modulate the magnetic fluid are re-modulated into magnetic fluid products of corresponding properties, and placed in the magnetic fluid storage device for use in the next membrane cleaning.

[0016] In summary, the present application includes at least one of the following beneficial technical effects: 1. By combining magnetic fluid technology and reverse osmosis technology, this application provides an efficient and non-destructive reverse osmosis membrane cleaning device, which achieves efficient removal of pollutants while avoiding damage to the membrane structure caused by traditional cleaning methods; 2. By setting up the preferred solutions such as the pressure-resistant membrane shell end cover group, recovery device and leak detection device, the safety of equipment use and the convenience of maintenance are further improved, and the consumption of reagents and membrane cleaning costs are reduced; 3. The magnetic fluid-assisted reverse osmosis membrane cleaning equipment of the present application has broad application prospects and can be widely used in water treatment, seawater desalination, wastewater recycling and other fields, contributing to technological progress and energy conservation and emission reduction in related industries. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic structural diagram of a magnetic fluid-assisted reverse osmosis membrane cleaning device according to an embodiment of the present application; Figure 2 It is a schematic diagram of the structure of the recovery device of an embodiment of the present application; Figure 3 is a schematic side view of a magnetic fluid-assisted reverse osmosis membrane cleaning device according to an embodiment of the present application; Figure 4is a cross-sectional view of a detection device provided in an embodiment of the present application; Figure 5 It is a cross-sectional view of a magnetic fluid-assisted reverse osmosis membrane cleaning device provided in an embodiment of the present application.

[0017] 1. Frame; 11. Clamp; 12. Pressure-resistant membrane shell; 2. Magnetic fluid storage device; 3. Magnetic fluid deflector; 4. Core rod; 5. Electromagnetic coil; 6. Pressure-resistant membrane shell end cover; 7. Recovery device; 71. Recovery pipeline; 72. Recovery bin; 73. Electromagnetic iron ring; 8. Leak detection device; 81. Leak detection pipeline; 82. Closing valve; 83. Magnetic flux sensor; 9. Detection device; 91. Probe; 92. Sampling tube. DETAILED DESCRIPTION Example

[0018] The magnetic fluid assisted reverse osmosis membrane cleaning device provided in the embodiment of the present application is as follows: Figure 1 and Figure 2 As shown, it includes key components such as a frame 1, a magnetic fluid storage 2, a magnetic fluid deflector 3, a core rod 4 and an electromagnetic coil 5. The frame 1, as the supporting structure of the entire device, is specially designed with multiple stations, which are specifically used to install reverse osmosis membranes, and each station is cleverly arranged circumferentially around the central axis of the frame 1, which saves space and is easy to operate.

[0019] The magnetic fluid reservoir 2 is used as the storage and modulation part of the magnetic fluid, and contains magnetic base particles, base liquid and surfactant. This design enables the magnetic fluid reservoir 2 to flexibly modulate a suitable magnetic fluid base liquid according to the polluted environment that actually needs to be cleaned, thereby ensuring the cleaning effect and efficiency.

[0020] The magnetic fluid deflector 3 is responsible for accurately injecting the magnetic fluid in the magnetic fluid reservoir 2 into the reverse osmosis membrane installed at each station of the frame 1. To this end, each magnetic fluid deflector 3 is connected to the frame 1 through a fastener and is arranged at each station of the frame 1 in a one-to-one correspondence. At the same time, each magnetic fluid deflector 3 is connected to the magnetic fluid reservoir 2 to ensure the smooth supply of magnetic fluid.

[0021] The core rod 4 is an important component arranged at the middle position of each station of the frame 1, and is made of magnetic conductive material. This design enables the core rod 4 to effectively guide and control the moving direction and path of the magnetic fluid in the reverse osmosis membrane under the magnetic field generated by the electromagnetic coil 5.

[0022] The electromagnetic coil 5 is arranged around the outside of each station of the frame 1 and is connected to a variable AC power supply. By changing the current size and direction of the variable AC power supply, the magnetic field strength and direction generated by the electromagnetic coil 5 can be flexibly adjusted. At the same time, the electromagnetic coil 5 is also designed to be able to move along its own central axis. This feature enables the electromagnetic coil 5 to drive the magnetic fluid in the reverse osmosis membrane of each station of the frame 1 to move, thereby achieving a more comprehensive and thorough cleaning effect.

[0023] The implementation principle of Example 1 is as follows: First, according to the actual reverse osmosis membrane assembly cleaning process, a suitable magnetic fluid base liquid is prepared in the magnetic fluid reservoir 2. Then, the prepared magnetic fluid is accurately injected into the reverse osmosis membrane installed at each station of the frame 1 through the magnetic fluid deflector 3. Next, the electromagnetic coil 5 is started and the magnetic field strength and direction generated by it are adjusted, and the electromagnetic coil 5 is controlled to move along its own central axis direction. Under the action of the magnetic field, the magnetic fluid moves accurately in the reverse osmosis membrane and removes the pollutants attached to the membrane. Finally, the electromagnetic coil 5 is turned off and the cleaned magnetic fluid is recovered to complete the entire cleaning process.

[0024] After the reverse osmosis membrane is installed at the station of the frame 1, the magnetic fluid is first injected into the reverse osmosis membrane through the injector, and then the magnetic field generator generates a magnetic field, and the magnetic field generator moves along the axial direction of the reverse osmosis membrane, so that the magnetic fluid is shuttled and cleaned in the membrane, and the attachments on the inner surface of each layer in the reverse osmosis membrane are vibrated and scraped, thereby removing the pollutants in the membrane. After the cleaning is completed, the flushing liquid is injected through the flusher to flush out the cleaned magnetic fluid and the pollutants together. The whole process is simple to operate and has high cleaning efficiency. Compared with traditional cleaning liquid cleaning, it can more effectively remove pollutants attached to the inner surface of the reverse osmosis membrane, reduce the use of cleaning liquid, reduce resource waste and improve the cleaning effect. Example

[0025] Based on Example 1, the embodiment of the present application further refines the sealing and recovery functions of the equipment. Specifically, two opposite end covers 6 of the pressure-resistant membrane shell 12 are provided at each station of the rack, forming a group of 6 end covers of the pressure-resistant membrane shell 12, which can seal the water inlet, the concentrated brine outlet and the product outlet of the reverse osmosis membrane. This design ensures that during the cleaning process, the key interfaces of the reverse osmosis membrane are tightly sealed to prevent leakage of magnetic fluid and maintain the airtightness of the cleaning environment, thereby improving the cleaning efficiency and effect.

[0026] In addition, embodiment 2 further includes a recovery device 7, which is connected to the concentrated brine outlet of each station through a plurality of recovery pipes 71, and is used to recover the magnetic fluid after cleaning. Each recovery pipe 71 is equipped with an electromagnet ring 73, which uses a magnetic field to attract the magnetic fluid to ensure that it is effectively recovered and reduce resource waste.

[0027] In terms of implementation principle, Example 2 not only improves the airtightness and efficiency of cleaning by adding 6 sets of end covers of the pressure-resistant membrane shell 12 and the recovery device 7, but also realizes the recycling of magnetic fluid, reduces operating costs, and embodies the concept of environmental protection. During the cleaning process, the magnetic fluid, driven by the electromagnetic coil 5, accurately removes pollutants on the reverse osmosis membrane, and is then effectively recovered by the recovery device 7. The whole process is efficient, environmentally friendly and economical. Example

[0028] The present application embodiment provides a method for configuring a magnetic fluid for a magnetic fluid-assisted reverse osmosis membrane cleaning device. Specifically, the method comprises the following steps: Step 1: prepare a solution of Fe3+ and Fe2+ in a molar ratio of 1:1.5-2, and add concentrated ammonia water thereto until a black precipitate is completely formed, thereby obtaining a first black precipitate solution. This step is a key step in preparing magnetic base particles. By controlling the ratio of Fe3+ to Fe2+ and the amount of concentrated ammonia water added, base particles with excellent magnetic properties can be generated.

[0029] Step 2: quickly heat the obtained first black precipitate solution to 80-100°C, add oleic acid and low carbon alkane, stir until the solution is clearly separated, and use magnetic decantation to obtain magnetic fluid. This step is to make the magnetic base particles and the base liquid form a stable magnetic fluid by heating and adding specific chemicals.

[0030] Step 3: Centrifuge the magnetic fluid, wash with deionized water, flocculate with an organic solvent, and then dry it in a low-temperature vacuum to obtain a single-layer coated magnetic powder. This step is to further purify and dry the magnetic fluid to obtain high-quality magnetic base particles.

[0031] Step 4, weigh the obtained single-layer coated magnetic powder, add the single-layer coated magnetic powder to the base liquid at room temperature, stir and disperse until there is no precipitation, and then centrifuge. The liquid poured out after centrifugation is the required magnetic fluid. This step is to mix the purified magnetic base particles with the base liquid to form a magnetic fluid that is finally used to clean the reverse osmosis membrane. In step 1, the concentration of ammonia water is 25% ~ 28%; based on the molar amount of Fe3+, the amount of ammonia water added is 400 ~ 700ml / mol Fe3+. The low-carbon alkane is kerosene. In a single flocculation, the volume of the organic solvent is 2 to 4 times the volume of the magnetic fluid liquid. Acetone is used for flocculation. The amount of intermediate liquid added is 3 to 6 times the weight of the weighed single-layer coated magnetic powder. The intermediate liquid is a low-boiling hydrocarbon. The intermediate liquid is a C4~C10 hydrocarbon. The intermediate liquid is one or more of hexane and heptane. The base liquid is a low-carbon oil product; based on the weighed single-layer coated magnetic powder, the volume of the base liquid added is 0.8mL / g-2mL / g of the single-layer coated magnetic powder. The low-carbon oil product is one or more of kerosene and diesel. The amount of polyisobutylene succinimide added is 20%-50% of the weight of the weighed single-layer coated magnetic powder. The base carrier liquid is one or more of diester base carrier liquid, hydraulic oil, total loss system oil, and pump oil. Based on the weighed single-layer coated magnetic powder, the volume of the base carrier liquid added is 0.4mL / g-2mL / g of the single-layer coated magnetic powder.

[0032] In the present invention, magnetic powder is first prepared: the magnetic powder is prepared according to chemical coprecipitation, a solution of Fe2+:Fe3+ massaged at 1:1.5~2 is heated to 25-60°C, and concentrated ammonia water is added until a black precipitate is completely generated to obtain a first black precipitate solution. Furthermore, the concentration of ammonia water is 25%-28%, and the amount added is 400-700ml / molFe3+.

[0033] Secondly, the magnetic powder is coated with a single layer: the first black precipitate is quickly heated to 80°C~100°C, an appropriate amount of oleic acid and low-carbon small molecule alkanes (such as kerosene, etc.) are added, and the stirring is accelerated. The seal is removed after 3-8 minutes (taking kerosene as an example, it forms a liquid seal before stirring, and after stirring, the liquid seal is destroyed, that is, the seal is removed), and the mixed solution is stirred until it is obviously layered, and then separated by strong magnetic separation, and the supernatant is poured out to initially obtain magnetic fluid A. The magnetic fluid A is centrifuged, repeatedly washed with deionized water, and repeatedly flocculated with acetone, and then vacuum dried at low temperature to obtain a single-layer coated magnetic powder. Further, based on Fe3+, the amount of oleic acid is 40-110ml / molFe3+, and the volume of acetone is 2-4 times the volume of magnetic fluid A.

[0034] Finally, for the low-carbon base liquid magnetic fluid, weigh the prepared single-layer coated magnetic powder, stir and disperse it in the base liquid at room temperature until there is no precipitation, then centrifuge and pour out the liquid to obtain the magnetic fluid. The base carrier liquid can be low-carbon oil such as kerosene and diesel, and its added volume is 0.8mL / g-2mL / g of the weight of the magnetic dry powder. In this way, the magnetic fluid coated with the first surfactant (oleic acid) is obtained.

[0035] For esters, hydraulic oil, pump oil, etc. with a large carbon content, weigh the prepared single-layer coated magnetic powder, stir and disperse it in the intermediate liquid at room temperature, quickly heat it to 140~170℃, add a uniform mixture of T154A and base carrier liquid and stir it quickly. After 20-30 minutes, the intermediate liquid is completely volatilized, cooled to room temperature, and centrifuged at high speed to obtain a uniform magnetic fluid. Among them, the intermediate liquid can be a low-boiling hydrocarbon, such as (n-) heptane or (n-) hexane, and the mass of T154A is 20%-50% of the weight of the magnetic powder. Among them, the base carrier liquid can be diesters, hydraulic oil, total loss system oil, pump oil, etc., and its added volume is 0.4mL / g-2mL / g of the weight of the magnetic dry powder. In this way, a magnetic fluid coated with the first surfactant (oleic acid) and the second surfactant (T154A) is obtained.

[0036] In hydrocarbon magnetic fluids, the amount of surfactant used to coat the magnetic particles must be appropriate. If it is too little, it is not enough to form a complete coating layer; if it is too much, multiple layers of adsorption will be formed, which will lead to a decrease in stability and magnetic properties. Under the condition of ensuring that the first coating layer, i.e., the chemical adsorption layer, can completely coat the magnetic particles, in order to remove as much of the physical adsorption layer as possible that cannot exist stably, the present invention adds a step of repeatedly washing the modified nanoparticles. This added step can make the amount of the surface modifier added in the early stage unnecessary, as long as the surfactant is slightly excessive to ensure that the complete chemical coating layer can completely coat the magnetic particles. This added step can, on the one hand, simplify the difficulty of controlling the amount of surfactant added; on the other hand, it can remove as much of the surfactant (physical adsorption layer) that cannot exist stably as possible, so that the surface of the magnetic particles can be coated with a single layer.

[0037] For the magnetic fluids that need secondary modification, such as diesters and pump oil bases, the present invention selects polyisobutylene succinimide (T154A) to disperse the oil. The dispersant is harmless to the human body and the environment and is an environmentally friendly product. Through experimental determination, the magnetic fluid prepared by the present invention using polyisobutylene succinimide has good dispersibility of oil and good magnetic fluid performance; compared with similar products on the market, the saturation magnetization intensity data of the present invention is comparable, and has good application prospects. Example

[0038] This embodiment discloses a magnetic fluid-assisted reverse osmosis membrane cleaning method, which is applicable to the reverse osmosis membrane cleaning device described in any of the above embodiments. The method comprises the following steps: S1: Install the reverse osmosis membrane assembly at each station of the frame 1 and fix it by the clamp 11; S2: raw water is injected into the machine through the raw water inlet, and the pure water is discharged through the water outlet through the leak detection pipeline after being filtered by the reverse osmosis membrane module. The concentrated brine is discharged through the concentrated brine outlet of the reverse osmosis membrane module through the recovery pipeline. After a fixed period of operation, the machine is shut down for cleaning; S3: Before starting cleaning, prepare the appropriate magnetic fluid according to the cleaning needs, and inject clean water into each reverse osmosis membrane assembly to flush and replace the concentrated brine in the membrane; S4: injecting cleaning solution into the reverse osmosis membrane assembly to soak and pretreat the pollutants therein for 300 minutes; S5: Control the electromagnetic coil 5 to repeatedly move within the first three membranes of the reverse osmosis membrane assembly along the length direction of the reverse osmosis membrane assembly, and repeatedly change the current direction and magnitude of the variable AC power supply during this process. When the electromagnetic coil 5 moves close to the third membrane of the reverse osmosis membrane assembly, the magnetic fluid is injected into the rear end of the reverse osmosis membrane assembly through the magnetic fluid guide 3, and the magnetic fluid is driven by another electromagnetic coil 5 to move toward the fourth membrane of the reverse osmosis membrane assembly, so that a certain distance is always maintained between the two electromagnetic coils 5. The two electromagnetic coils 5 reciprocate to drive the magnetic fluid to vibrate and scrape the inside of the reverse osmosis membrane assembly; S6: judging whether it is necessary to add liquid medicine according to the pH value of the liquid medicine in the outflow of the sampling tube measured by the probe; if the pH value measured by the probe deviates too much from the set value, adding liquid medicine suitable for the current cleaning process into the reverse osmosis membrane assembly through the liquid medicine washing pipeline provided by the reverse osmosis membrane assembly; S7: After S5 is executed for a fixed time, the closed valve 82 in the recovery pipeline 71 connected to the front end of each reverse osmosis membrane assembly is opened, and the cleaning liquid and magnetic fluid used to clean the first three membranes of each reverse osmosis membrane assembly are discharged from the concentrated brine discharge port at the front end of the reverse osmosis membrane assembly, and the magnetic fluid and cleaning liquid of the last four membranes inside the reverse osmosis membrane assembly are discharged from the concentrated brine discharge port at the end of the reverse osmosis membrane assembly into the recovery pipeline 71; S8: Recovering the magnetic fluid base particles stored in the recovery bin 72 installed in the recovery pipeline 71; S9: injecting clean water from the water inlet of each reverse osmosis membrane assembly through the reverse osmosis membrane assembly self-cleaning system to flush the residual liquid medicine and magnetic fluid in each reverse osmosis membrane assembly to the outside of the reverse osmosis membrane assembly; S10: During the execution of S9, observe whether the magnetic flux sensor 83 of the leak detection pipeline 81 has a change in magnetic flux. If a change occurs, it is necessary to stop the machine to check the location of structural damage to the reverse osmosis membrane assembly; if there is no change, re-execute step S2 until the next regular cleaning.

[0039] The implementation principle of Example 4 is: by combining magnetic fluid technology and electromagnetic field control technology, this method can achieve efficient cleaning of the reverse osmosis membrane. First, the pretreatment step softens or dissolves some pollutants that are difficult to remove directly; then, the strong shear force, impact force and vibration of the magnetic fluid under the action of the electromagnetic field are used to remove the pollutants attached to the membrane surface; finally, the subsequent cleaning steps ensure that the reverse osmosis membrane is thoroughly cleaned. This method not only improves the cleaning efficiency and quality, but also simplifies the operation process and reduces the difficulty of operation. Example

[0040] This embodiment provides an automatic control system for a magnetic fluid-assisted reverse osmosis membrane cleaning device, which is integrated into the device and used to realize automatic control of the reverse osmosis membrane cleaning process. The automatic control system includes two core components: a controller and a time relay.

[0041] The controller is responsible for receiving and processing various command signals, and controlling the various components of the equipment to work according to the preset process. Specifically, the controller is electrically connected to the electromagnetic coil 5, and can control the power on and off of the electromagnetic coil 5, and then control the strength and direction of the magnetic field generated by it. At the same time, the controller is also electrically connected to the variable AC power supply, and can adjust the current size and direction of the variable AC power supply output, so as to achieve refined control of the magnetic field generated by the electromagnetic coil 5. A pressure-resistant membrane shell 12 end cover 6 is also provided to ensure that the various ports of the reverse osmosis membrane can be effectively closed during the cleaning process to prevent leakage of magnetic fluid. Finally, the controller is also electrically connected to the magnetic fluid deflector 3, and can control the magnetic fluid deflector 3 to inject the magnetic fluid in the magnetic fluid reservoir 2 into the reverse osmosis membrane of the corresponding station to start the cleaning operation. It also includes a detection component for detecting the concentration of the drug in the reverse osmosis membrane assembly during the cleaning process, including a plurality of probes 91, each probe 91 is arranged one by one at the rear end of each sampling tube 92, the sampling tube 92 is opened during the detection, the effluent of the sampling tube 92 is detected by the probe 91, and the pH value and conductivity of the drug solution in the reverse osmosis membrane assembly are determined; a detection control module, each probe 91 is electrically connected to the detection control module, the detection control module determines the concentration of the drug solution according to the change of the pH value of the drug solution in each reverse osmosis membrane assembly, and further determines whether the drug solution needs to be added. If the pH value measured by the probe deviates too much from the set value, the detection control module sends a signal to the controller, and the controller controls the drug washing pipeline of the reverse osmosis membrane assembly to add the drug solution suitable for the current cleaning process; when the detection control module detects that the pH value of the drug solution in the reverse osmosis membrane no longer changes, it is determined that the membrane cleaning is finished. The time relay is used to measure the execution time of each cleaning step. The time relay is connected to the controller and can send a signal to the controller after reaching the preset time, prompting the controller to perform the next operation. For example, during the cleaning process, the time relay can set the residence time of the magnetic fluid in the reverse osmosis membrane to ensure that the magnetic fluid can fully act on the pollutants on the reverse osmosis membrane. When the set time is reached, the time relay will send a signal to the controller, and the controller will then control the electromagnetic coil 5 to cut off the power to complete the entire cleaning process.

[0042] Through the synergistic effect of the controller and the time relay, the automatic control system provided in this embodiment can realize comprehensive automatic control of the reverse osmosis membrane cleaning process. This can not only greatly improve the cleaning efficiency and quality, reduce the manual operation cost, but also ensure the stability and reliability of the cleaning process, and provide a strong guarantee for the long-term and efficient operation of the reverse osmosis membrane.

[0043] The implementation principle of Example 5 is as follows: by integrating automatic control components such as a controller and a time relay, this example constructs an efficient and intelligent reverse osmosis membrane cleaning control system. The system can automatically control the various components of the equipment to work according to a preset process, thereby achieving full automation of the cleaning process.

Claims

1. A magnetic fluid assisted reverse osmosis membrane cleaning device, characterized in that: include: The frame (1) is provided with a plurality of workstations for installing reverse osmosis membrane components, and the workstations are arranged in an array around a horizontal axis of the frame (1); The magnetic fluid storage device (2) has two cavities formed therein for storing two kinds of finished magnetic fluid products suitable for acidic and alkaline cleaning environments, respectively. The finished magnetic fluid products are prepared by mixing magnetic fluid base particles and other materials used to mix magnetic fluid. During cleaning, the storage port storing the magnetic fluid of corresponding properties is opened according to the acidic or alkaline environment corresponding to the cleaning process.

2. A magnetic fluid deflector (3), wherein the frame (1) is provided with at least two magnetic fluid deflectors (3) corresponding to each station position thereof, each of the magnetic fluid deflectors (3) is connected to the magnetic fluid reservoir (2), and each of the magnetic fluid deflectors (3) can be connected to a reverse osmosis membrane assembly installed at a corresponding station position of the frame, and the two magnetic fluid deflectors (3) provided at the same station position of the frame can respectively inject magnetic fluid into the reverse osmosis membrane assembly from both ends thereof; A core rod (4) is arranged at the middle position of each workstation of the frame (1), the length direction of the core rod (4) is arranged along the horizontal axis direction of the frame (1), and the core rod (4) is made of a magnetic conductive material; The electromagnetic coil (5) is arranged outside each workstation of the frame (1) corresponding to the electromagnetic coil (5). The central axis of the electromagnetic coil (5) can be arranged colinearly with the length direction of the core rod (4). The electromagnetic coil (5) is also connected to a variable AC power supply. By changing the current of the variable AC power supply, the intensity of the magnetic field generated by the electromagnetic coil (5) can be adjusted. By changing the current direction of the variable AC power supply, the direction of the magnetic field generated by the electromagnetic coil (5) can be adjusted. The electromagnetic coil (5) is movably connected to the frame (1). The electromagnetic coil (5) can move along the horizontal axis direction of the frame (1). The movement of the electromagnetic coil (5) can drive the magnetic fluid in the reverse osmosis membrane assembly of each workstation of the frame (1) to move accordingly. The variable AC power supply can adjust the current to adjust the vibration amplitude and vibration frequency of the magnetic fluid in the electromagnetic coil (5).

3. The magnetic fluid assisted reverse osmosis membrane cleaning device according to claim 1, characterized in that: Each pressure-resistant membrane shell (12) at each workstation position of the rack is provided with two pressure-resistant membrane shell (12) end covers (6) arranged opposite to each other, and any two pressure-resistant membrane shell (12) end covers (6) arranged opposite to each other are arranged as a pressure-resistant membrane shell (12) end cover (6) group, and each of the pressure-resistant membrane shell (12) end cover (6) groups can seal the reverse osmosis membrane assembly at the corresponding workstation of the rack together with the pressure-resistant membrane shell (12), and when magnetic fluid-assisted cleaning is performed, each pressure-resistant membrane shell (12) end cover (6) group and the pressure-resistant membrane shell (12) seal the corresponding reverse osmosis membrane element.

4. The magnetic fluid assisted reverse osmosis membrane cleaning equipment according to claim 1, characterized in that: The configuration process of the magnetic fluid used in the magnetic fluid storage (2) in the pickling cleaning environment is as follows: Fe3+ and Fe2+ are prepared into a solution in a molar ratio of 1:1.5-2, and concentrated ammonia water is added thereto until a black precipitate is completely formed, thereby obtaining a first black precipitate solution; The obtained first black precipitate solution is quickly heated to 80-100° C., and oleic acid and low-carbon alkanes are added thereto, and stirred until the solution is obviously separated into layers, and a magnetic fluid liquid is obtained by a magnetic decantation method, and the magnetic fluid liquid is centrifuged, washed with deionized water, flocculated with an organic solvent, and then low-temperature vacuum dried to obtain a single-layer coated magnetic powder; Weigh the single-layer coated magnetic powder obtained in the step, add the single-layer coated magnetic powder into the base liquid at room temperature, stir and disperse until there is no precipitation, and then centrifuge. The liquid poured out after centrifugation is the magnetic fluid.

5. The magnetic fluid assisted reverse osmosis membrane cleaning equipment according to claim 1, characterized in that: The magnetic fluid configuration process used in the magnetic fluid storage (2) under the alkaline cleaning environment is as follows: Fe3+ and Fe2+ are prepared into a solution in a molar ratio of 1:1.5-2, and concentrated ammonia water is added thereto until a black precipitate is completely formed, thereby obtaining a first black precipitate solution; The obtained first black precipitate solution is quickly heated to 80-100° C., and oleic acid and low-carbon alkanes are added thereto, and stirred until the solution is obviously separated into layers, and a magnetic fluid liquid is obtained by a magnetic decantation method, and the magnetic fluid liquid is centrifuged, washed with deionized water, flocculated with an organic solvent, and then low-temperature vacuum dried to obtain a single-layer coated magnetic powder; The obtained single-layer coated magnetic powder is weighed, and the single-layer coated magnetic powder is stirred and dispersed in the intermediate liquid at room temperature to obtain a second intermediate solution, and the second intermediate solution is quickly heated to 140-170° C., and polyisobutylene succinimide and base carrier liquid are added thereto, and the mixture is stirred and mixed evenly. After the intermediate liquid is completely evaporated, it is cooled to room temperature and centrifuged. The liquid poured out after centrifugation is the magnetic fluid.

6. The magnetic fluid assisted reverse osmosis membrane cleaning equipment according to claim 2, characterized in that: The invention also comprises a recovery device (7), wherein the recovery device (7) is used to recover the magnetic fluid after auxiliary cleaning, and the recovery device (7) comprises a recovery pipeline (71), each recovery pipeline (71) can be connected to the concentrated brine discharge port of each pressure-resistant membrane shell (12), and each recovery pipeline (71) is provided with a closing valve (82) at one end close to the end cover (6) of the pressure-resistant membrane shell (12), and each closing valve (82) can close the corresponding recovery pipeline (71); A recovery bin (72) is provided, and a plurality of electromagnet rings (73) are arranged at the position of each recovery pipeline (71) corresponding to the recovery bin (72). The electromagnet rings (73) are wrapped around the outer side of the corresponding recovery bin (72) along the length direction of the recovery bin (72). The cleaning waste liquid of the reverse osmosis membrane is discharged into the recovery pipeline (71) along the concentrated brine discharge port. The magnetic fluid base particles therein are adsorbed on the inner wall of the recovery bin (72) under the action of the electromagnet rings (73), so as to achieve separation from other cleaning waste liquids.

7. The magnetic fluid assisted reverse osmosis membrane cleaning equipment according to claim 5, characterized in that: The invention also comprises a leak detection device (8), wherein the leak detection device (8) is used to detect whether the reverse osmosis membrane assembly has structural damage, specifically to detect whether magnetic fluid is present in the cleaning liquid discharged from the water outlet of the reverse osmosis membrane assembly after cleaning, and comprises a plurality of leak detection pipelines (81), each of which can be connected to the water outlet of the reverse osmosis membrane assembly installed at each station of the frame (1) in a one-to-one correspondence, each of which is connected to the corresponding end cover (6) of the pressure-resistant membrane shell (12), and each leak detection pipeline (81) is connected to the corresponding end cover (6) of the pressure-resistant membrane shell (12). A closing valve (82) is connected to the leakage pipeline (81) near the end cover (6) of the pressure-resistant membrane shell (12). Each of the closing valves (82) can close the corresponding leakage detection pipeline (81). A magnetic flux sensor (83) is arranged in each of the leakage detection pipelines (81). If the magnetic flux of the magnetic flux sensor (83) changes when the cleaning fluid passes through the leakage detection pipeline (81), it means that magnetic fluid is mixed therein, thereby judging that structural damage occurs inside the reverse osmosis membrane assembly and preventing the magnetic fluid from flowing out with the cleaning fluid.

8. The magnetic fluid assisted reverse osmosis membrane cleaning equipment according to claim 1, characterized in that: Each workstation is provided with a clamp (11) for fixing the reverse osmosis membrane assembly. The clamp (11) is detachably connected to the frame (1), and the clamp (11) is made of non-metallic material.

9. The magnetic fluid assisted reverse osmosis membrane cleaning equipment according to claim 2, characterized in that: It also includes a detection component for detecting the concentration of the reagent in the reverse osmosis membrane component during the cleaning process, including: The sampling tubes (92) are arranged one by one on the end covers (6) of the pressure-resistant membrane shells (12), and each sampling tube (92) can be connected to the corresponding reverse osmosis membrane assembly; A plurality of probes (91) are provided, each of the probes (91) being arranged one by one at the rear end of each of the sampling tubes (92); during detection, the sampling tube (92) is opened, and the outflow liquid of the sampling tube (92) is detected by the probe (91), so as to measure the pH value and conductivity of the liquid in the reverse osmosis membrane assembly; A detection control module, each of the probes (91) is electrically connected to the detection control module, and the detection control module determines the concentration of the drug solution according to the changes in the pH value and conductivity of the drug solution in each reverse osmosis membrane assembly, and further determines whether the drug solution needs to be supplemented.

10. The magnetic fluid assisted reverse osmosis membrane cleaning equipment according to claim 8, characterized in that: It also includes a control system, which is used to control the cleaning process of the reverse osmosis membrane assembly to achieve automation. The control system includes: The controller sends a signal to start cleaning, the electromagnetic coil (5) is electrically connected to the controller, and the controller can control the movement of the electromagnetic coil (5); the variable AC power supply is also electrically connected to the controller, and the controller can control the current size and direction of the variable AC power supply; the magnetic fluid deflector (3) is also electrically connected to the controller, and the controller controls the magnetic fluid in the magnetic fluid storage (2) to be injected into the reverse osmosis membrane assembly of the corresponding station; The time relay is connected to the controller and is used to measure the execution time of each step.

11. A magnetic fluid assisted reverse osmosis membrane cleaning device and method, characterized in that: The reverse osmosis membrane cleaning device applicable to any one of claims 1 to 9 comprises: S1: Install the reverse osmosis membrane assembly at each workstation of the frame (1), fix it with a clamp (11), inject raw water into it through the raw water inlet, filter it through the reverse osmosis membrane assembly, and then discharge the pure water through the water outlet through the leak detection pipeline, and discharge the concentrated brine through the concentrated brine outlet of the reverse osmosis membrane assembly through the recovery pipeline, and shut down for cleaning after a fixed operation period; S2: Inject produced water into the reverse osmosis membrane assembly to replace the concentrated brine remaining in the reverse osmosis membrane assembly with the produced water; S3: drain the cleaning water, inject cleaning liquid into the reverse osmosis membrane assembly to pre-treat the pollutants therein, and soak for a period of time to soften the pollutants; S4: injecting magnetic fluid into the front end of the reverse osmosis membrane assembly through the magnetic fluid guide (3); S5: Control the electromagnetic coil (5) to repeatedly move along the length direction of the reverse osmosis membrane assembly within the range of the first three membranes of the reverse osmosis membrane assembly, and repeatedly change the current direction and magnitude of the variable AC power supply during this process. When the electromagnetic coil (5) moves close to the third membrane of the reverse osmosis membrane assembly, a magnetic fluid is injected into the rear end of the reverse osmosis membrane assembly through the magnetic fluid guide (3), and this part of the magnetic fluid is driven to move toward the fourth membrane of the reverse osmosis membrane assembly through another electromagnetic coil (5), so that a certain distance is always maintained between the two electromagnetic coils (5). The two electromagnetic coils (5) move back and forth to drive the magnetic fluid to scrape and clean the inside of the reverse osmosis membrane assembly. S6: opening the closed valve (82) in the recovery pipeline (71) connected to the front end of each reverse osmosis membrane module, and discharging the cleaning liquid and magnetic fluid used to clean the first three membranes of each reverse osmosis membrane module from the concentrated brine discharge port at the front end of the reverse osmosis membrane module, and discharging the magnetic fluid and cleaning liquid of the last four membranes in the reverse osmosis membrane module from the concentrated brine discharge port at the end of the reverse osmosis membrane module into the recovery pipeline (71); S7: injecting clean water from the water inlet of each reverse osmosis membrane assembly through the reverse osmosis membrane assembly self-cleaning system to flush the residual liquid medicine and magnetic fluid in each reverse osmosis membrane assembly to the outside of the reverse osmosis membrane assembly; S8: Recover the magnetic fluid base particles stored in the recovery bin (72) installed in the recovery pipeline (71). The recovered magnetic fluid base particles and other materials used to prepare the magnetic fluid are re-prepared into magnetic fluid products with corresponding properties, and placed in the magnetic fluid storage device (2) for use in the next membrane cleaning.

Images