CN115228298A - Rolled membrane system and gas-liquid two-phase cleaning method thereof - Google Patents

Abstract

The invention relates to a roll-type membrane system and a gas-liquid two-phase cleaning method thereof, belonging to the technical field of water treatment. The system includes a water inlet unit, a multi-section rolled membrane unit, a liquid phase cleaning unit, a gas phase cleaning unit and a control system for controlling each unit; the multi-section rolled membrane unit includes a one-stage, two-stage or three-stage roll-type membrane unit; liquid The outlet pipelines of the phase cleaning unit and the gas phase cleaning unit are respectively connected to the water inlet and/or end of each section of the rolled membrane unit through a branch, so as to realize the forward and/or reverse water washing of each section of the rolled membrane unit And/or air washing, and each branch is provided with a forward water inlet valve, a forward drain valve, a reverse water inlet valve and a reverse drain valve; the control system controls the switch of each valve. The system and method not only have high cleaning efficiency, reduce the cleaning frequency and prolong the cleaning period, but also can effectively clean the front-end membrane element, which is beneficial to protect the service life of the membrane element.

Description

Rolled membrane system and gas-liquid two-phase cleaning method

technical field

The invention relates to a cleaning method for a roll-type membrane, belongs to the technical field of water treatment, and in particular relates to a roll-type membrane system and a gas-liquid two-phase cleaning method thereof.

Background technique

Membrane separation technology has the characteristics of high treatment efficiency, short process flow, easy control, flexible use, small footprint of membrane separation water plants, and automation of production. Rolled membranes, especially reverse osmosis and nanofiltration, can effectively remove water. In order to obtain stable and reliable clean water quality that has never been achieved by traditional treatment processes in the past, rolled membrane technology is widely used in surface water treatment, seawater desalination, brackish water desalination, The manufacture of ultrapure water in the electronics and pharmaceutical industries, the production of boiler feed water in power plants and the production of circulating water for refrigerators, as well as the treatment and regeneration of various waste water, etc. It has broad application prospects and great market potential. Therefore, the research and application of roll membrane separation has gradually become a hot spot in the field of water supply. It is known as one of the important technologies for obtaining high-quality drinking water today, and is known as "water treatment technology in the 21st century. It is the best alternative to traditional processes." best choice.

Membrane fouling and deterioration of rolled membranes has always been one of the bottlenecks restricting the development of this technology. During the operation of the roll membrane system, the surface of the roll membrane will be deposited due to the presence of pollutants such as suspended solids, colloids, organic matter, microorganisms and other pollutants in the raw water and the concentration of insoluble substances during the membrane separation process. In turn, contamination of the membrane element is formed. The most common of these contaminations are calcium carbonate precipitation, calcium sulfate precipitation, metal (iron, manganese, copper, nickel, aluminum, etc.) oxide precipitation, silicon deposits, inorganic or organic sediment mixtures, NOM natural organic matter, synthetic organic matter ( Such as: scale inhibitor/dispersant, cationic polyelectrolyte), microorganism (algae, mold, fungus) and other pollution. According to the types of pollutants mentioned above, membrane fouling can be summarized as caused by the following processes: (1) deposition of inorganic substances; (2) adsorption of organic molecules; (3) deposition of particulate matter; (4) adhesion and growth of microorganisms. The final result of membrane fouling is: under normal pressure, the water output of the rolled membrane drops below 85% of the normal value, or the effluent conductivity increases by more than 15%, and the pressure difference between the sections of the rolled membrane increases significantly. The harm caused by membrane pollution to the system varies according to the degree of pollution. When the pollution is relatively light, the overall operation of the system does not change significantly, and the impact on the effluent is not very large. The mild pollution can be cleaned online; It has a great impact on the system, not only causing a significant increase in the water inlet pressure, and a significant increase in the energy consumption of the system, but also seriously affecting the water production volume and water quality of the system; in severe cases, it will lead to the inability to restore the membrane filtration performance through cleaning, thus causing the membrane elements to be scrapped in advance , which greatly increases the use cost of the roll membrane system.

The existing anti-fouling methods for roll membrane filtration systems mainly include adding pretreatment equipment such as ultrafiltration, reverse roll membrane, closed loop membrane membrane, and roll membrane cleaning/rinsing technology, etc. These technologies, such as adding ultrafiltration The cost of other pretreatment equipment, reverse roll membrane, and closed-circuit roll membrane is relatively high, while ordinary membrane cleaning/flushing technology has limited effect on highly polluted water sources, and frequent cleaning operations are cumbersome and operating costs are relatively high. There are many types of fouling of rolled membranes, but the locations of these fouling are different. According to the analysis of fouling types, colloids, metal oxides, organic biological fouling, and corrosion damage are most likely to appear in the front-end membrane element of the system (front-end of the first section), However, mineral scale, polymeric silicon precipitation and scale inhibitor fouling are likely to appear in the final and final membrane elements. Especially when the membrane at the front end of the first stage is fouled, since the first stage and the second stage are connected, the traditional flushing method will cause the pollutants at the front end of the first stage to be washed into the end of the first stage or even the second stage membrane element, which seriously affects the cleaning. Effect. In addition, excessive chemical cleaning is used in the traditional method, which will also affect the service life or the salt rejection rate of the coiled membrane element.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention discloses a roll-type membrane system and a gas-liquid two-phase cleaning method thereof. The system and method not only have high cleaning efficiency, reduce the cleaning frequency and prolong the cleaning period, but also can effectively clean the front-end membrane element and protect the service life of the membrane element.

In order to achieve the above technical purpose, the present invention discloses a roll-type membrane system, which includes a water inlet unit, a multi-stage roll-type membrane unit, a liquid-phase cleaning unit, a gas-phase cleaning unit and a control system for controlling each unit; The roll-type membrane unit includes any one of one-stage, two-stage or three-stage roll-type reverse osmosis membrane, roll-type nanofiltration membrane or roll-type ultra/microfiltration membrane;

The outlet pipelines of the liquid-phase cleaning unit and the gas-phase cleaning unit are respectively connected to the water inlet and/or end of each section of the roll-type membrane unit through a branch, so as to realize the forward and/or reverse direction of each section of the roll-type membrane unit. Water washing and/or air washing in the forward direction, and each branch is provided with a forward water inlet valve, a forward drain valve, a reverse water inlet valve and a reverse drain valve; the control system controls the opening and closing of each valve and the start of the pump. stop;

The ends of each section of the coiled membrane unit are also connected with three sub-circuits, one is used to discharge concentrated water, one is used to discharge product water, and the remaining one is used to discharge cleaning and drainage.

Further, the water inlet pressure of the reverse water washing is ≤0.3MPa, preferably ≤0.2MPa, more preferably ≤0.06MPa.

Further, the inlet pressure of the air scrubbing is less than or equal to 0.1 MPa, preferably less than or equal to 0.08 MPa.

Further, the gas phase cleaning unit includes an air pressure tank, a pressure regulating valve and an air washing valve which are connected in sequence.

Further, the liquid-phase cleaning unit includes a dosing device, a cleaning pump and a cleaning and filtering device connected in sequence.

Further, the multi-stage roll-type membrane unit includes a one-stage roll-type membrane unit and a two-stage roll-type membrane unit, wherein the one-stage roll-type membrane unit is provided with forward and/or reverse air washing and/or water washing pipelines, The two-stage roll-type membrane unit is provided with a forward air washing and/or water washing pipeline; the roll-type membrane unit can be a roll-type reverse osmosis membrane, a roll-type nanofiltration membrane or a roll-type ultra/microfiltration membrane;

The outlet pipelines of the cleaning and filtering device and the air washing valve are connected with three branches, the first branch is a positive washing water inlet pipeline, the second branch is a second positive washing water inlet pipeline, and the third branch It is a backwash water inlet pipeline;

The first section of the positive washing water inlet pipeline is connected to a section of the forward washing water inlet valve set on the first section of the rolled membrane unit. Connect a section of positive wash drain valve;

The second-stage positive-washing water inlet pipeline is connected to the second-stage positive-washing water inlet valve set on the second-stage roll-type membrane unit, and the second-stage positive-washing water inlet valve is connected to the water inlet end of the second-stage roll-type membrane unit; The end of the segmented membrane unit is connected to the second-stage positive washing drain valve;

The first section of the backwash inlet pipeline is connected to a section of the backwash inlet valve set on the first section of the roll-type membrane unit, the section of the backwash inlet valve is connected to the end of the first section of the roll-type membrane unit, and the first section of the roll-type membrane unit is connected to the water inlet end. Connect a backwash drain valve;

The first-stage forward washing drain valve, the second-stage forward-washing drain valve and the first-stage backwashing drain valve all lead to cleaning drainage.

Further, the gas of the air washing is air, and the water washing is to use externally added water or rolled membrane to produce water or concentrated water for cleaning, and can also add a medicament to the externally added water, and the medicament includes a bactericide, a surfactant, an acid Any one of cleaning agent, alkaline cleaning agent, neutral cleaning agent and complex cleaning agent, only when the gas-liquid cleaning mode designed in the present invention is used to improve the pressure drop of the system is very rare. Chemical cleaning of agents.

The second purpose of the present invention is to disclose a gas-liquid two-phase cleaning method for the above-mentioned system to the roll-type membrane unit. Or air washing, forward water washing and/or air washing of two-stage wound membrane unit, or any combination.

Further, the cleaning mode is forward washing and/or air washing of one-stage coiled membrane unit + reverse washing and/or air washing of one-stage coiled membrane unit + forward washing and/or air washing of two-stage coiled membrane unit .

Further, when the pressure drop of the one-stage coiled membrane unit and the second-stage coiled membrane unit continues to be above 0.15MPa, the control system closes each pump and valve of the water inlet unit, and opens each pump of the gas phase cleaning unit and the liquid phase cleaning unit. and valve, and a backwash inlet valve and a backwash drain valve are opened, and a gas-liquid reverse flush is performed for 30 to 120 s; 120s; the second-stage positive washing water inlet valve and the second-stage positive washing drain valve are opened, and the second-stage water is flushing forward for 30-150s; and repeat the above operation once every 48h until the pressure drop of the first-stage coiled membrane unit is 0.01-0.10MPa , the pressure drop of the two-stage roll membrane unit is 0.01-0.10MPa. Preferably, the first stage of gas-liquid reverse flushing is performed for 50-80s, the first-stage gas-liquid forward flushing is performed for 50-80s, and the second-stage water forward flushing is performed for 100-150s. It is 0.05～0.08MPa, and the pressure drop of the two-stage roll membrane unit is 0.01～0.02MPa.

Further, the above cleaning method is suitable for a water filtration system with an influent water of 10,000 tons/day and a roll-type membrane water output of 7,500 tons/day.

Compared with the prior art, the technical solutions provided by the embodiments of the present invention have the following advantages:

1. The cleaning method designed in the present invention adopts gas-liquid two-phase cleaning with high efficiency, and can clean each section of the membrane unit individually or at the same time, which is beneficial to reduce the cleaning frequency and prolong the cleaning period.

2. The cleaning method designed in the present invention can realize precise cleaning of the pollutants in the first-stage roll-up membrane unit, avoid contamination of subsequent roll-up membrane units by pollutants, and thus protect the service life of the membrane elements.

3. The cleaning method designed by the present invention mainly adopts the physical cleaning mode of gas-liquid. Only when the pressure drop of the system is not improved well by this mode, the chemical cleaning will be carried out with external agents, so it is beneficial to delay the membrane degradation. The number of chemical cleanings, and finally achieve the technical purpose of protecting the membrane element.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description serve to explain the principles of the invention.

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. In other words, on the premise of no creative labor, other drawings can also be obtained from these drawings.

1 is a schematic structural diagram of a membrane system designed in an embodiment of the present invention;

FIG. 2 is a schematic diagram of the connection relationship of the rolled membrane system in FIG. 1 .

Wherein, each number in the above-mentioned accompanying drawing is as follows:

100. Water inlet unit;

101, water supply pump; 102, water dosing equipment; 103, security filter; 104, booster pump; 105, water inlet valve;

200, a section of roll-type membrane unit; 200-1, the water inlet end of a section of roll-type membrane unit; 200-2, the end of a section of roll-type membrane unit;

201, a section of coiled membrane element; 202, a section of positive washing water inlet pipeline; 203, a section of positive washing water inlet valve; 204, a section of positive washing drain valve; 205, a section of backwash water inlet pipeline; valve; 207, a backwash drain valve; 208, a water production valve; 209, a concentrated water valve;

300, two-stage roll-type membrane unit; 300-1, the water inlet end of the two-stage roll-type membrane unit; 300-2, the end of the two-stage roll-type membrane unit;

301, two-stage coiled membrane element; 302, two-stage positive washing water inlet pipeline; 303, two-stage positive washing water inlet valve; 304, two-stage positive washing drain valve; 305, two-stage water production valve; 306, two-stage Concentrated water valve;

400, liquid phase cleaning unit; 401, dosing device; 402, cleaning pump; 403, cleaning filter device;

500, gas phase cleaning unit; 501, pressure regulating valve; 502, gas washing valve; 503, air pressure tank.

Detailed ways

In order to more clearly understand the above objects, features and advantages of the present invention, the solution of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments may be combined with each other under the condition of no conflict.

The present invention is aimed at the deposition on the surface of the rolled membrane due to the presence of pollutants such as suspended solids, colloids, organic matter, microorganisms and other pollutants in the raw water and the concentration of insoluble substances during the membrane separation process during the operation of the rolled membrane system. Forming pollution to membrane elements, the prior art flushing or cleaning methods have limited effects on highly polluted water sources, frequent cleaning operations are cumbersome, and pollutants from the front-end membrane elements are cleaned to the end membrane elements during ordinary forward flushing, resulting in pollution cleaning. In order to solve the technical problems such as unsatisfactory effects, the present invention discloses a roll-type membrane system and a gas-liquid two-phase cleaning method thereof.

Many specific details are set forth in the following description to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein; obviously, the embodiments in the description are only a part of the embodiments of the present invention, and Not all examples.

Example 1

This embodiment discloses a roll-type membrane system. Referring to FIG. 1 , the system includes a water inlet unit 100 , a one-stage roll-type membrane unit 200 , a second-stage roll-type membrane unit 300 , a liquid-phase cleaning unit 400 , and a gas-phase cleaning unit 500 and the control system for controlling each unit; and the control system is not shown in the accompanying drawing 1, but it actually exists, the preferred control system of the present invention is a PLC control system, and the relevant control equipment is commonly used in this field. I won't go into details.

As shown in FIG. 1 , the liquid phase cleaning unit 400 includes a dosing device 401 , a cleaning pump 402 and a cleaning filter device 403 connected in sequence, and the gas phase cleaning unit 500 includes an air pressure tank 503 and a pressure regulating valve 502 connected in sequence With the air wash valve 501, the cleaning and filtering device 403, and the outlet pipeline of the air wash valve 503 are connected to three branches, the first branch is a first-stage positive washing water inlet pipeline 202, and the second branch is a second-stage positive washing The water inlet pipeline 302, the third branch is a backwash water inlet pipeline 205;

The first section of the positive washing water inlet pipeline 202 is connected to the first section of the positive washing water inlet valve 203 provided on the first section of the rolled membrane unit 200, and the first section of the positive washing water inlet valve 203 is connected to the first section of the rolled membrane unit water inlet 200-1 , the end 200-2 of a section of rolled membrane unit is connected to a section of positive washing drain valve 204;

The second-stage positive washing water inlet pipeline 302 is connected to the second-stage positive washing water inlet valve 303 provided on the second-stage rolling membrane unit 300, and the second-stage positive washing water inlet valve 303 is connected to the second-stage rolling membrane unit inlet. The water end 300-1, the end 300-2 of the second-stage rolled membrane unit is connected to the second-stage positive washing drain valve 304;

The one-stage backwash water inlet pipeline 205 is connected to the one-stage backwash water inlet valve 206 provided on the one-stage roll-type membrane unit 200, and the one-stage backwash water inlet valve 206 is connected to the end 200-2 of the one-stage roll-type membrane unit. The water inlet end 200-1 of the rolled membrane unit is connected to a backwash drain valve 207;

The first-stage forward-washing drain valve 204, the second-stage forward-washing drain valve 304 and the first-stage backwashing drain valve 207 all lead to the cleaning and draining end.

The ends of each section of the coiled membrane unit are also connected with three sub-circuits, one is used to discharge concentrated water, one is used to discharge product water, and the remaining one is used to discharge cleaning and drainage.

In this embodiment, preferably, the end 200-2 of the first-stage coiled membrane unit is further connected to a first-stage water production valve 208 and a first-stage concentrated water valve 209; Concentrate valve 306.

First, there is a series relationship between the one-stage roll-type membrane unit 200 and the second-stage roll-type membrane unit 300, and between each one-stage roll-type membrane element 201 in the one-stage roll-type membrane unit 200, each two-stage roll-type membrane unit 300 has two The multi-group parallel connection mode is adopted between the segmented membrane elements 301, which enables the control of the liquid-phase cleaning unit 400 and the gas-phase cleaning unit 500 to realize independent gas-liquid cleaning of each section, so as to avoid the cleaning flow of the front-end membrane element. The technical problem of contamination of the terminal membrane device is caused at the end, wherein the gas for the air wash is air, and the inlet pressure of the control air wash is ≤ 0.1MPa, preferably ≤ 0.08MPa.

At the same time, when the contamination of each membrane element in the one-stage roll-type membrane unit 200 is relatively serious, such as the above-mentioned phenomena such as biological contamination by colloids, metal oxides, and organic substances in the one-stage roll-type membrane unit 200, it is also possible to select the one-stage roll-type membrane unit 200. The type membrane unit 200 is cleaned by reverse gas-liquid cleaning, but there is a risk of cracking the membrane element or damaging the sealing and bonding surface in reverse flushing. ≤0.2MPa.

Since the contamination of the membrane elements of the two-stage roll-up membrane unit can be reasonably controlled, the present invention can choose not to carry out the design of backwashing the two-stage roll-up membrane unit, but the related design of the backwashing of the two-stage roll-up membrane unit is also within the protection scope of the present invention.

The present invention mainly adopts the gas-liquid forward or reverse physical cleaning mode, and only when the mode does not improve the pressure drop of the system poorly, will the membrane element be chemically cleaned with an external agent, and the agent includes a bactericide , any one of surfactants, acidic cleaning agents, alkaline cleaning agents, neutral cleaning agents and complex cleaning agents. 1 , the water inlet unit designed by the present invention further includes a water supply pump 101 , an inlet water dosing device 102 , a security filter 103 , a booster pump 104 and a water inlet valve 105 , which are connected to each other.

To sum up, the membrane system designed in the present invention can realize multi-mode cleaning of the coiled membrane elements, such as forward water washing, air washing or water washing + air washing, reverse water washing of the first-stage coiled membrane unit, Air washing or water washing + air washing, two-stage coiled membrane unit forward water washing, air washing or water washing + air washing, and one-stage coiled membrane unit and two-stage coiled membrane unit at the same time forward water washing, air washing or water washing + air washing wash etc. And the above mode can be flexibly cleaned according to the actual pressure drop of each permeation unit under the condition of normal water production or stop water production.

Example 2

This embodiment chooses to clean the reclaimed water reuse treatment system with 10,000 tons/day of influent water and 7,500 tons/day of reverse osmosis production water, wherein the requirements for the influent water quality and effluent water quality of the reclaimed water reuse treatment system are as follows in Table 1 with Table 2;

Table 1 Influent water quality parameters of the design of the water reuse treatment system

serial number index unit average value 1 COD mg/L ≤30 2 BOD mg/L ≤6 3 Ammonia nitrogen mg/L ≤1.5 4 TN mg/L ≤15 5 TP mg/L ≤0.3 6 pH 6 to 9 7 SS mg/L ≤10 8 total dissolved solids mg/L ≤1000 9 Sulfate mg/L ≤200 10 total hardness mg/L ≤400 11 chloride mg/L ≤200 12 Alkalinity mg/L ≤400

Table 2 Design water quality parameters of water reuse treatment system

index data Desalination rate 97% (three years) PH 6.5～9.0 Turbidity <1 COD <2 (manganese method) free chlorine <0.1mg/L

The filtration system adopts two sets of reverse osmosis systems as shown in Fig. 2, the designed influent water volume of a single set is 208.4m ³ /h, the permeate water volume is 156.3m ³ /h, the designed operating flux is 17.3LMH, and the one-stage two-stage method , the first section adopts 36 6-core membrane shells, and the second section adopts 18 6-core membrane shells. A total of 324 BW30FR-400/34i RO membrane elements are installed in a single set, and two sets of 648 RO membrane elements are installed. The maintenance and cleaning of the original system adopts the traditional forward water flushing method.

The original reverse osmosis system of the above-mentioned reclaimed water reuse treatment system was completed and put into operation less than 2 months after the reverse osmosis membrane element was polluted and blocked, especially the pressure drop of the 1#RO section and the 2#RO section remained high, such as higher than 0.15MPa , the traditional positive water flushing method of maintenance cleaning has limited flushing effect on the first and second stages, and after the pressure rises, after chemical cleaning, it can only maintain stable operation for about 15 days, not only the cleaning chemical cleaning agent cost is high, but also cleaning It takes time and needs to arrange personnel to clean frequently, and because the RO system needs to be shut down during cleaning, the operation efficiency of the entire system is low.

Wherein, using the cleaning device designed in Example 1 to perform cleaning treatment on the above-mentioned two-stage rolled membrane system respectively, the following Table 3 is obtained, and Table 3 presents the specific cleaning method.

Table 3 List of operating parameters and operating effects of each cleaning method

Combining with Table 3, it can be seen that the operation mode of the original system is "filtering→water flushing→filtering" periodic cycle operation, in which the water flushing only performs forward water flushing for the first and second sections at the same time, and CIP chemical is performed when the pressure is high. Cleaning; after the system is optimized and transformed, the operation mode is "filtering → gas-liquid two-phase flushing → filtering" periodic cycle operation, in which the gas-liquid two-phase flushing includes the first stage reverse gas-liquid two-phase flushing, the first stage forward gas-liquid two-phase flushing Liquid two-phase flushing and second-stage forward water flushing; as can be seen from Table 3, after the gas-liquid two-phase cleaning transformation was carried out on the original system, the effect of each flushing was significantly improved, the CIP chemical cleaning cycle was prolonged, and the The chemical cleaning effect is improved, and the membrane fouling problem of the original traditional membrane system is completely solved.

In addition to the cleaning modes listed in Embodiment 2 above, other cleaning modes may also be used for other types of contamination conditions. If the membrane pressure drop of a first-stage coiled membrane unit reaches the cleaning requirement (0.15MPa) quickly, a separate gas-liquid two-phase cleaning mode can be used: "a first-stage coiled membrane unit reverse water washing + air washing → a first-stage coiled membrane unit Forward water washing + air washing" method; if the pressure drop of the first-stage coiled membrane unit is faster to meet the cleaning requirements (0.15MPa), a separate second-stage gas-liquid two-phase cleaning mode can be used: "The second-stage coiled membrane unit forward Water washing + air washing method”; if the pressure drop of the one-stage coiled membrane unit and the second-stage coiled membrane unit both meet the cleaning requirements (0.15MPa), the “one-stage coiled membrane unit reversed” similar to Example 2 can be used. Water washing + air washing → one-stage coiled membrane unit forward water washing + air washing → two-stage coiled membrane unit forward water washing + air washing” combined cleaning mode; if the membrane pressure drop is high (0.2MPa), you can use the cleaning mode Chemicals are added to the cleaning water, and the cleaning effect is further improved by the gas-liquid two-phase enhanced chemical cleaning method: "One-stage coiled membrane unit reverse drug washing + air washing → one-stage coiled membrane unit forward drug washing + air washing → second stage The coiled membrane unit is a cleaning mode that combines forward chemical washing + air washing.

To sum up, the system and method not only have high cleaning efficiency, reduce cleaning frequency and prolong cleaning cycle, but also can effectively clean the front-end membrane element and protect the service life of the membrane element.

It should be noted that, herein, the terms "comprising", "comprising" or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements, It also includes other elements not expressly listed or inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

The above descriptions are only specific embodiments of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A spiral-wound membrane system is characterized by comprising a water inlet unit, a multi-section spiral-wound membrane unit, a liquid phase cleaning unit, a gas phase cleaning unit and a control system for controlling each unit; the multi-section rolled membrane unit comprises one section, two sections or three sections of rolled reverse osmosis membranes, rolled nanofiltration membranes or rolled ultra/microfiltration membranes;

the outlet pipelines of the liquid phase cleaning unit and the gas phase cleaning unit are respectively connected with the water inlet end and/or the tail end of each section of the roll-type membrane unit through branches for realizing forward and/or reverse water washing and/or gas washing of each section of the roll-type membrane unit, and each branch is provided with a forward water inlet valve, a forward water discharge valve, a reverse water inlet valve and a reverse water discharge valve; the control system controls the opening and closing of each valve and the starting and stopping of each pump;

the tail end of each section of the roll-type membrane unit is also connected with three sub-paths, one sub-path is used for discharging concentrated water, one sub-path is used for discharging produced water, and the other sub-path is used for discharging cleaning and discharging water.

2. Membrane system according to claim 1, characterized in that the water inlet pressure of the reverse water wash is ≤ 0.3MPa.

3. The rolled membrane system of claim 1 wherein the inlet gas pressure of the gas wash is ≤ 0.1MPa.

4. The membrane system according to any one of claims 1 to 3, characterized in that the gas phase washing unit comprises a pneumatic tank, a pressure regulating valve and a gas washing valve connected in series.

5. The membrane system of claim 4, wherein the liquid phase washing unit comprises a dosing device, a washing pump and a washing filtration device connected in sequence.

6. The rolled membrane system of claim 5, characterized in that the multi-sectional rolled membrane unit comprises a one-section rolled membrane unit and a two-section rolled membrane unit, wherein a forward and/or reverse air washing and/or water washing pipeline is arranged on the one-section rolled membrane unit, and a forward air washing and/or water washing pipeline is arranged on the two-section rolled membrane unit;

the outlet pipelines of the cleaning and filtering device and the gas washing valve are connected with three branches, wherein the first branch is a section of forward washing water inlet pipeline, the second branch is a section of forward washing water inlet pipeline, and the third branch is a section of backwashing water inlet pipeline;

the first section of forward washing water inlet pipeline is connected with a first section of forward washing water inlet valve arranged on the first section of spiral membrane unit, the first section of forward washing water inlet valve is communicated with the water inlet end of the first section of spiral membrane unit, and the tail end of the first section of spiral membrane unit is connected with a first section of forward washing drain valve;

the second-stage forward washing water inlet pipeline is connected with a second-stage forward washing water inlet valve arranged on the second-stage spiral-wound membrane unit, the second-stage forward washing water inlet valve is communicated with the water inlet end of the second-stage spiral-wound membrane unit, and the tail end of the second-stage spiral-wound membrane unit is connected with a second-stage forward washing drain valve;

the first section of backwashing water inlet pipeline is connected with a first section of backwashing water inlet valve arranged on the first section of spiral membrane unit, the first section of backwashing water inlet valve is communicated with the tail end of the first section of spiral membrane unit, and the water inlet end of the first section of spiral membrane unit is connected with a first section of backwashing water outlet valve;

and the first section of forward washing drain valve, the second section of forward washing drain valve and the first section of backwashing drain valve are communicated with cleaning drain water.

7. The rolled membrane system of claim 1 or 2 or 3 or 5 or 6, wherein the gas of the gas washing is air, the water washing is cleaning by using external water or water produced by the rolled membrane or concentrated water, and a medicament can be added into the external water, and the medicament comprises any one of a bactericide, a surfactant, an acidic cleaning agent, an alkaline cleaning agent, a neutral cleaning agent and a complex cleaning agent.

8. A method for cleaning gas-liquid two-phase of a rolled membrane by the system of any one of claims 1 to 7, which is characterized in that: the cleaning mode comprises forward water washing and/or air washing of the first-stage roll type membrane unit, reverse water washing and/or air washing of the first-stage roll type membrane unit, forward water washing and/or air washing of the second-stage roll type membrane unit, or any combination.

9. The method of claim 8, wherein: the cleaning mode is forward water washing and/or gas washing of the first-section spiral membrane unit, reverse water washing and/or gas washing of the first-section spiral membrane unit and forward water washing and/or gas washing of the second-section spiral membrane unit.

10. The method of claim 9, wherein: when the pressure drop of the first-section spiral membrane unit and the second-section spiral membrane unit is continuously over 0.15MPa, the control system closes each pump and each valve of the water inlet unit, opens each pump and each valve of the gas-phase cleaning unit and the liquid-phase cleaning unit, opens the first-section backwashing water inlet valve and the first-section backwashing drainage valve, and flushes the first-section gas-liquid reverse direction for 30-120 s; a first-stage forward washing water inlet valve and a first-stage forward washing water outlet valve are opened, and a first-stage gas-liquid forward washing is carried out for 30-120 s; a second-stage forward washing water inlet valve and a second-stage forward washing water outlet valve are opened, and the second-stage water is washed forward for 30-150 seconds; and repeating the operation once every 48h until the pressure drop of the first section of the roll-type membrane unit is 0.01-0.10 MPa, and the pressure drop of the second section of the roll-type membrane unit is 0.01-0.10 MPa.

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