Device for cleaning nanofiltration membrane by utilizing micron bubbles

Abstract

The utility model provides a device for cleaning a nanofiltration membrane by using microbubbles, which comprises a cleaning water tank, a pure water tank, a cleaning water pump, an air dissolving device, an air flow regulator and an air compressor, the cleaning water tank and the pure water tank are respectively connected with an inlet of the cleaning water pump through pipelines, an outlet pipeline of the cleaning water pump is connected with an inlet of the air dissolving device, and the air flow regulator is connected with an outlet pipeline of the air dissolving device. An inlet pipeline of the air dissolving device is connected with an inlet pipeline of the air compressor, an outlet pipeline of the air dissolving device is connected with a cleaning water inlet pipeline of the nanofiltration device, an inlet pipeline of the air flow regulator is connected with an outlet pipeline of the air compressor, and an outlet pipeline of the air flow regulator is connected with the air dissolving device. The cleaning agent can deeply clean dirt and blockage in the operation process of the nanofiltration membrane, prolongs the cleaning period, reduces the dosage of chemicals, prolongs the service life of the nanofiltration membrane, and reduces the operation cost.

Description

Technical Field

[0001] The utility model relates to a nanofiltration membrane cleaning device in a brine system, in particular to the field of nanofiltration refining of brine and seawater and other fields using nanofiltration membranes. Background Art

[0002] Nanofiltration membrane is a new type of separation membrane that came out in the late 1980s. Its molecular weight cutoff is between that of reverse osmosis membrane and ultrafiltration membrane, about 100-2000Da, and its pore size is about 1-10nm, so it is called "nanofiltration". It is often used in the chemical industry for salt water separation and concentration. During the use of nanofiltration membrane, the membrane surface may be contaminated due to various reasons. The pollutants may be inorganic salt scale, hydrated metal oxides, organic matter and microorganisms. The membrane pollution will cause the decline of membrane performance, such as flux decline, desalination rate decline, etc. At this time, the membrane needs to be cleaned. According to the different pollutants, fresh water is generally directly added with targeted agents to prepare the corresponding cleaning water.

[0003] During the use of nanofiltration membranes, cleaning is an indispensable part of membrane maintenance. Whether the selected cleaning method is appropriate directly affects the cleaning effect, frequency and agent consumption, which in turn affects the degree of recovery of membrane performance, service life and production and operation costs. Therefore, optimizing the cleaning method has always been an important exploration direction in the process of nanofiltration membrane maintenance.

[0004] In the cleaning process of ultrafiltration membranes and reverse osmosis membranes, the idea of ​​using dissolved air water to clean the membranes has been proposed. Due to the different structures and properties of ultrafiltration membranes, reverse osmosis membranes and nanofiltration membranes, the cleaning methods are different; the cleaning methods of ultrafiltration membranes and reverse osmosis membranes cannot be fully applicable to the cleaning of nanofiltration membranes, and even under certain specific cleaning process conditions, contaminants will penetrate into the membrane, increasing the difficulty of cleaning.

[0005] Chinese patent CN109954406A discloses "a reverse osmosis membrane cleaning process". This method mainly mentions the use of acid and alkali solution combined with micro-nano bubbles and ultrasonic treatment to clean the reverse osmosis membrane, but its application is limited to the field of reverse osmosis membrane cleaning, and the specific process conditions for microbubble cleaning are not proposed throughout the article, which has little reference significance for the cleaning of nanofiltration membranes. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a device for cleaning nanofiltration membranes using micron bubbles. Cleaning water containing micron bubbles has higher cleaning efficiency, thereby shortening the cleaning time, reducing the consumption of reagents, extending the service life of the nanofiltration membrane, and reducing the production cost.

[0007] In order to solve the above technical problems, the utility model discloses a device for cleaning nanofiltration membrane using micron bubbles, comprising a cleaning water tank, a pure water tank, a cleaning water pump, an air dissolving device, an air flow regulator and an air compressor, and is characterized in that the cleaning water tank and the pure water tank are respectively connected to the inlet of the cleaning water pump through pipelines, the outlet pipeline of the cleaning water pump is connected to the inlet of the air dissolving device, the outlet pipeline of the air dissolving device is connected to the cleaning water inlet pipeline of the nanofiltration device, the inlet pipeline of the air flow regulator is connected to the outlet pipeline of the air compressor, and the outlet pipeline of the air flow regulator is connected to the air dissolving device.

[0008] Preferably, a drug inlet, a water inlet and a reflux port are arranged at the top of the cleaning water tank, and a discharge valve and a discharge pipeline are arranged at the bottom; a water inlet is arranged at the top of the pure water tank, and a discharge valve and a discharge pipeline are arranged at the bottom.

[0009] Preferably, the inlet pipeline of the cleaning water pump is divided into two routes: one pipeline is connected to the cleaning water tank, and the other pipeline is connected to the pure water tank. Gate valves are respectively provided on the two pipelines, and a butterfly valve is provided on the outlet pipeline of the cleaning water pump, and a seismic-resistant pressure gauge is provided behind the butterfly valve.

[0010] Preferably, the gas dissolving device is provided with a gas dissolving device inlet pipeline, a gas dissolving device outlet pipeline, an exhaust outlet pipeline, an observation sampling pipeline and three compressed air inlet pipelines at the front, middle and rear. The gas dissolving efficiency of the gas dissolving device is 90-98%, the air dissolution rate is ≥20%, and the bubble particle size is 3-8um.

[0011] Preferably, the three outlet pipelines of the air flow regulator are respectively connected to the front, middle and rear compressed air inlet pipelines of the air dissolving device, and the three pipelines are all provided with flow regulating valves and flow meters.

[0012] The utility model adds a dissolving device on the basis of a conventional nanofiltration membrane cleaning device, and uses the dissolving device to make micron bubbles fully dissolved in flushing water (pure water) and chemical cleaning water, and the micron bubble cleaning effect is played in the flushing process of the nanofiltration membrane and the circulating immersion chemical cleaning process, thereby improving the cleaning efficiency of the nanofiltration membrane; thereby reducing the amount of chemical cleaning agents, reducing the cleaning frequency of the nanofiltration membrane and extending the service life of the nanofiltration membrane, and finally achieving the purpose of reducing costs and increasing efficiency. The beneficial effect of the utility model is that after adopting the above-mentioned device for cleaning the nanofiltration membrane using micron bubbles, in the process of nanofiltration membrane cleaning, the air flow regulator is used to adjust the ratio of the front, middle and rear three-way air intake and the relationship between the water intake of the dissolving device and the total air intake, so as to ensure that the micron bubbles can be fully and stably dissolved in the cleaning water; when using the cleaning device of the utility model, compared with the cleaning effect of the original nanofiltration membrane cleaning device, when the same cleaning effect is achieved, the cleaning device of the utility model can shorten the cleaning time, reduce the amount of chemical cleaning agents, reduce the cleaning frequency, thereby improving the cleaning efficiency, extending the service life of the nanofiltration membrane, and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of an embodiment of the utility model;

[0014] Figure 2 yes Figure 1 A schematic diagram of the gas dissolving device in the embodiment;

[0015] Figure 1 In: 1. Cleaning water tank, 2. Pure water tank, 3. Cleaning water pump, 4. Air flow regulator, 5. Compressed air main pipe, 6. Air compressor, 7. Nanofiltration device, 8. Concentrated water collection tank, 9. Dissolved gas device outlet pipeline, 10. Observation sampling pipeline, 11. Exhaust outlet pipeline, 12 Produced water discharge valve, 13 Produced water reflux valve, 14 Cleaning water tank outlet valve, 15 Pure water tank outlet valve, 16 Cleaning water pump inlet valve, 17 Cleaning water pump outlet valve, 18 Dissolved gas device inlet pressure gauge, 19 Dissolved gas device outlet pressure gauge, 20 Concentrated water discharge valve, 21. Dissolved gas device inlet pipeline, 22. Dissolved gas device;

[0016] Figure 2 In: 21. Dissolved air device inlet pipeline, 9. Dissolved air device outlet pipeline, 4. Air flow regulator, 5. Compressor outlet pipeline; 11. Exhaust outlet pipeline, 10. Observation sampling pipeline, 5-1. Compressed air front inlet pipeline, 5-2. Compressed air middle inlet pipeline, 5-3. Compressed air rear inlet pipeline, 18. Dissolved air device inlet pressure gauge, 19. Dissolved air device outlet pressure gauge. DETAILED DESCRIPTION

[0017] The following is combined with Figure 1 The utility model is described in further detail.

[0018] Reference Figure 1The device for cleaning nanofiltration membrane by using micron bubbles of the utility model comprises a cleaning water tank 1, a pure water tank 2, a cleaning water pump 3, an air dissolving device 22, an air flow regulator 4 and an air compressor 6. The cleaning water tank 1 and the pure water tank 2 are respectively connected to the inlet of the cleaning water pump 3 through pipelines, the outlet pipeline of the cleaning water pump 3 is connected to the inlet pipeline 21 of the air dissolving device, the outlet pipeline 9 of the air dissolving device is connected to the cleaning water inlet pipeline of the nanofiltration device 7, the inlet pipeline of the air flow regulator 4 is connected to the outlet pipeline of the air compressor 6, and the outlet pipeline of the air flow regulator 4 is connected to the air dissolving device 22. Specifically, the gas dissolving device is provided with a gas dissolving device inlet pipeline 21, a gas dissolving device outlet pipeline 9, an exhaust outlet pipeline 11, an observation sampling pipeline 10 and three front, middle and rear compressed air inlet pipelines, the front, middle and rear compressed air inlet pipelines are respectively the front compressed air inlet pipeline 5-1, the middle compressed air inlet pipeline 5-2 and the rear compressed air inlet pipeline 5-3; correspondingly, the three outlet pipelines of the air flow regulator 4 are respectively connected to the front, middle and rear compressed air inlet pipelines of the gas dissolving device and the three pipelines are all provided with flow regulating valves and flow meters. The gas dissolving efficiency of the gas dissolving device is 90~98%, the air dissolution rate is ≥20%, and the bubble particle size is 3~8um. Its specific structure refers to Figure 2 As shown, it includes a shell and a bubble generator located in the shell. Its specific structure is not described in detail here. The gas dissolving device on the market can be purchased. The utility model only changes the arrangement of its inlet pipeline and outlet pipeline to adapt to other structures of the utility model. The gas dissolving device outlet valve is arranged on the gas dissolving device outlet pipeline 9, the gas dissolving device discharge sampling valve is arranged on the observation sampling pipeline, the gas dissolving device exhaust valve is arranged on the exhaust port pipeline 11, the gas dissolving device inlet pressure gauge 18 is arranged on the gas dissolving device inlet pipeline of the gas dissolving device 18, and the gas dissolving device outlet pressure gauge 19 is arranged on the gas dissolving device outlet pipeline, so as to monitor the pressure in real time and ensure the generation of micron bubbles.

[0019] Reference Figure 1 As shown, the outlet of the nanofiltration device 7 is connected to the concentrated water collection tank 8 through a pipeline, and a concentrated water discharge valve 20 is arranged on the outlet pipeline of the nanofiltration device 7. The cleaning water tank 1 is respectively connected to the nanofiltration device 7 and the concentrated water collection tank 8 through pipelines. The pipeline between the cleaning water tank 1 and the nanofiltration device 7 is connected to the produced water reflux valve 13. A pipeline is arranged between the outlet pipeline of the nanofiltration device 7 and the pipelines of the above-mentioned cleaning water tank 1 and the nanofiltration device 7, and a produced water discharge valve 12 is installed on the pipeline. The cleaning water tank 1 is provided with a drug inlet, a water inlet and a reflux port at the top, and a discharge valve and a discharge pipeline at the bottom; the pure water tank is provided with a water inlet at the top, and a discharge valve and a discharge pipeline at the bottom, the clean water tank 1 is provided with a cleaning water tank outlet valve 14, the pure water tank 2 is provided with a pure water tank outlet valve 15, the cleaning water pump 3 is provided with a cleaning water pump inlet valve 16 and a cleaning water pump outlet valve 17, the cleaning water pump inlet valve 16 is a gate valve, and the cleaning water pump outlet valve 17 is a butterfly valve.

[0020] The inlet pipeline of the cleaning water pump is divided into two routes: one pipeline is connected to the cleaning water tank, and the other pipeline is connected to the pure water tank. Gate valves are respectively provided on the two pipelines. The pump outlet pipeline is provided with a butterfly valve, and a seismic pressure gauge is provided behind the butterfly valve. The air compressor outlet air flow rate is 6-12m 3 / h, pressure ≥0.6MPa. Example 1

[0021] This embodiment is used to clean the nanofiltration membrane affected by calcium carbonate scaling. Cleaning begins when the flux decreases to 90% of the normal water production flux. The main devices used are as follows: Figure 1 As shown, the specific cleaning steps are as follows:

[0022] First, rinse the nanofiltration membrane with pure water. All valves in the system are in the closed state. Open the pure water tank outlet valve 15, the cleaning water pump inlet valve 16, the cleaning water pump outlet valve 17, the valves on the exhaust port pipeline, the valves on the outlet pipeline of the dissolved gas device, the water production discharge valve 12 of the nanofiltration device, and the concentrated water discharge valve 20. Keep the pure water level in the pure water tank, start the cleaning water pump, observe the inlet pressure gauge 18 of the dissolved gas device, and control the pressure at 0.4-0.6Mpa by adjusting the clean cleaning water pump outlet valve 17. After the water is discharged from the exhaust port pipeline 11 of the dissolved gas device, close the exhaust valve, start the air compressor 6, and adjust the air intake of the front, middle and rear three routes of the dissolved gas device through the air flow regulator 4. During this cleaning period, the discharge valve of the sampling pipeline 10 of the dissolved gas device can be opened to receive dissolved gas water to observe the dissolved gas effect, and the air flow regulator can be adjusted to adjust the dissolved gas effect. This pure water flushing machine lasts for 10 minutes. After the pure water flushing is completed, the pure water tank outlet valve 15 is closed, the cleaning water pump 3 is stopped, the air compressor 6 is stopped, and an aqueous solution containing 0.2% hydrochloric acid is prepared in the cleaning water tank 1 as acidic cleaning water.

[0023] After the acidic cleaning water is prepared, open the cleaning water tank outlet valve 14, close the nanofiltration device water discharge valve 12, open the nanofiltration device water return valve 13, start the cleaning water pump 3, start the air compressor 6, and start the chemical cleaning of the nanofiltration device for 2 hours.

[0024] After the chemical cleaning of the nanofiltration device is completed, stop the air compressor 6, stop the cleaning water pump 3, close the cleaning water tank outlet valve 14, open the nanofiltration device water discharge valve, close the nanofiltration device water return valve 13, add pure water to the pure water tank, open the pure water tank outlet valve 15, start the air compressor 6, start the cleaning water pump 3, and keep flushing the nanofiltration device with pure water for 10 minutes. After the pure water flushing is completed, stop the air compressor 6, stop the cleaning water pump 3, and close all the valves of the cleaning device, and the entire cleaning is completed.

[0025] After testing, the nanofiltration membrane flux recovered to 98% of the initial flux. The cleaning cycle from this cleaning to the next cleaning was 40 days, which was 19% longer than the cleaning cycle calculated by traditional cleaning methods, and the annual chemical consumption was reduced by 16%.

Claims

1. A device for cleaning a nanofiltration membrane using micron bubbles, comprising a cleaning water tank, a pure water tank, and a cleaning water pump, characterized in that: It also includes a dissolving device, an air flow regulator and an air compressor. The cleaning water tank and the pure water tank are respectively connected to the inlet of the cleaning water pump through pipelines, the outlet pipeline of the cleaning water pump is connected to the inlet of the dissolving device, the outlet pipeline of the dissolving device is connected to the cleaning water inlet pipeline of the nanofiltration device, the inlet pipeline of the air flow regulator is connected to the outlet pipeline of the air compressor, and the outlet pipeline of the air flow regulator is connected to the dissolving device.

2. The device for cleaning nanofiltration membrane using microbubbles according to claim 1, characterized in that: The top of the cleaning water tank is provided with a drug inlet, a water inlet and a reflux port, and the bottom is provided with a discharge valve and a discharge pipeline; the top of the pure water tank is provided with a water inlet, and the bottom is provided with a discharge valve and a discharge pipeline.

3. The device for cleaning nanofiltration membrane using microbubbles according to claim 1, characterized in that: The pipelines connecting the inlet of the cleaning water pump and the cleaning water tank and the pure water tank are respectively provided with gate valves, and the outlet pipeline of the cleaning water pump is provided with a butterfly valve.

4. The device for cleaning nanofiltration membrane using microbubbles according to claim 1, characterized in that: The gas dissolving device is provided with a gas dissolving device inlet pipeline, a gas dissolving device outlet pipeline, an exhaust outlet pipeline, an observation sampling pipeline and three compressed air inlet pipelines, front, middle and rear.

5. The device for cleaning nanofiltration membrane using microbubbles according to claim 4, characterized in that: The outlet of the air flow regulator is a three-way pipeline, which is respectively connected to the front, middle and rear of the air dissolving device, and the flow of the three-way pipeline can be adjusted by the air flow regulator.

6. The device for cleaning nanofiltration membrane using microbubbles according to any one of claims 1 to 5, characterized in that 。

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