Automatic control method and system for pipeline direct drinking water membrane filtration

Abstract

The present application relates to the technical field of water treatment automation control, in particular to a kind of automatic control method and system of pipeline direct drinking water membrane filtration, comprising the following steps: S100: real-time acquisition membrane filtration system's operating parameter, at least including the water inlet pressure of membrane module, water production pressure and water production flow, and according to the operating parameter real-time calculation membrane module current transmembrane pressure difference value, the present application is by introducing based on the temperature correction and signal filtering algorithm of fluid viscosity characteristics, effectively eliminates the interference of environmental temperature change and pipeline noise to system perception, significantly improves the authenticity and precision of transmembrane pressure difference monitoring;Through monitoring the change rate characteristics of transmembrane pressure difference, the mechanism identification of deposition type pollution and blockage type pollution is realized, and low-loss hydraulic backwashing or high-intensity air-water pulse scrubbing is adaptively matched accordingly, which greatly prolongs the service life of membrane module while reducing operating energy consumption.

Description

Technical Field

[0001] This invention relates to the field of water treatment automation control technology, specifically to an automatic control method and system for membrane filtration of piped drinking water. Background Technology

[0002] With the improvement of residents' living standards, piped drinking water systems (usually using ultrafiltration or nanofiltration / reverse osmosis membrane technology) have been widely used in high-end residential communities, schools, hospitals, and office buildings. These systems remove bacteria, viruses, and colloidal impurities from the water through the physical retention of membrane modules, and then deliver the purified water directly to the user's end-user via a pipeline network. During the operation of membrane filtration systems, membrane fouling is an unavoidable phenomenon. As filtration time increases, contaminants will deposit on the membrane surface to form a filter cake layer or enter the membrane pores to cause blockage, leading to increased transmembrane pressure and decreased permeate flux.

[0003] Currently, existing direct drinking water membrane treatment control systems mainly employ the following two control logics: Timed cleaning mode: Regardless of whether the membrane is dirty or clogged, the system will force a hydraulic backwash at fixed time intervals (e.g., every 1 hour of operation).

[0004] Threshold trigger mode: Set a fixed upper limit for transmembrane pressure difference (e.g., 0.15 MPa). When the detected pressure difference exceeds this threshold, cleaning is triggered.

[0005] However, the aforementioned traditional control methods have the following significant technical drawbacks in practical applications: First, the lack of ability to identify the type of fouling leads to low cleaning efficiency or membrane damage. Existing control logic treats all "pressure differential increases" as the same type of fouling and uses a single hydraulic backwashing method.

[0006] In fact, membrane fouling can be divided into "deposition type" (loose adhesion of filter cake layer) and "clogging type" (pore adsorption / colloidal clogging). For the former, simple water rinsing can remove it; but for the latter, simple hydraulic backwashing not only fails to completely remove the fouling, but may also force the pollutants deeper into the membrane pores under the action of reverse pressure, causing irreversible flux decline.

[0007] Conversely, if the system is configured with high-intensity air-water scrubbing for a long time in order to cope with the risk of blockage, and air scrubbing is performed even when only slight deposit contamination occurs, the membrane fibers will be subjected to frequent and severe mechanical vibration, which will greatly shorten the service life of the membrane module and cause energy waste.

[0008] Second, environmental factors frequently lead to misjudgments. Water viscosity is significantly affected by temperature (the lower the temperature, the higher the viscosity). In low-temperature winter conditions, even if the membrane module is clean, the transmembrane pressure difference will naturally increase. Existing systems often lack temperature correction mechanisms based on fluid viscosity, easily misjudging the high pressure difference caused by low temperature as severe blockage, leading to frequent and unnecessary backwashing, resulting in serious waste of water resources and a decrease in water production rate.

[0009] Third, there is a lack of online safety monitoring mechanisms for membrane integrity. This is the biggest safety hazard in direct drinking water systems. Membrane modules may experience fiber breakage due to water hammer or aging during long-term operation. Once the membrane fibers are damaged, bacteria and viruses can directly penetrate the membrane wall and enter the product water side. Current systems mainly rely on TDS (conductivity to dissolved gases) sensors at the product water end to monitor water quality. However, for ultrafiltration (UF) systems, the primary targets are suspended solids and microorganisms, with extremely low removal rates for dissolved ions. Therefore, when membrane fiber breakage leads to excessive bacteria levels, the TDS value often does not change significantly, and the control system cannot detect it. This results in the system still supplying users with drinking water that "appears acceptable but is biologically unsafe" even with membrane damage, posing a significant public health risk.

[0010] In summary, developing an automatic control method and system that can accurately identify pollution types, eliminate environmental interference, and has a membrane integrity self-checking function is a technical challenge that urgently needs to be solved in the current piped drinking water field. Summary of the Invention

[0011] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an automatic control method for membrane filtration of piped drinking water, comprising the following steps: S100: Real-time acquisition of operating parameters of the membrane filtration system, the operating parameters including at least the inlet water pressure, product water pressure, and product water flow rate of the membrane module, and real-time calculation of the current transmembrane pressure difference value of the membrane module based on the operating parameters; S200: Monitoring the change trend of the transmembrane pressure difference value over time, calculating the rate of change of the transmembrane pressure difference per unit time, and comparing the rate of change of the transmembrane pressure difference with a preset fouling determination threshold to identify whether the current fouling type of the membrane module is deposition-type fouling or clogging-type fouling; S300: Based on the fouling type identified in step S200... The system adaptively matches and executes cleaning control strategies: when the fouling is identified as sediment-type, the control system executes a hydraulic backwashing procedure; when the fouling is identified as clogging-type, the control system executes an air-water mixed scrubbing procedure; S400: monitors the water production operation status of the system. When it is determined that the system is in a non-water production standby state and the duration meets the preset conditions, a membrane integrity self-check procedure is triggered: the control valve group makes the membrane module form a sealed cavity, gas is filled into the sealed cavity to the test pressure and maintained, and the pressure decay rate during the pressure holding period is monitored in real time. If the pressure decay rate exceeds the preset safety tolerance, a lock command is generated to forcibly stop the system water production and output an alarm signal.

[0012] Furthermore, the control system synchronously collects the inlet water pressure of the membrane module according to a preset sampling frequency. Concentrate pressure Water production pressure and raw water temperature The collected pressure data was denoised using a moving average filtering algorithm to obtain stable pressure values; the real-time transmembrane pressure difference was calculated. : And using temperature correction coefficient The real-time transmembrane pressure difference is converted to the standard transmembrane pressure difference value at standard temperature, wherein... The standard transmembrane pressure difference value is used as the transmembrane pressure difference value for monitoring and comparison in step S200.

[0013] Further, step S200 specifically includes: pre-setting a sliding time window. and a pollution change rate threshold The control system calculates the average rate of change of the transmembrane pressure difference within the current sliding time window every preset period during operation. ,in, In the formula, This represents the transmembrane pressure difference at the end of the window. This represents the transmembrane pressure difference at the start of the window; if the rate of change... satisfy The membrane module is determined to be in a deposition-type fouling state where the filter cake layer is slowly thickening; if the rate of change... satisfy The membrane module is determined to be in a clogging-type fouling state, characterized by rapid adsorption or blockage of membrane pores.

[0014] Further, step S300 specifically includes: the hydraulic backwashing procedure is configured to: stop the high-pressure pump and open the concentrate discharge valve, control the backwash pump to inject the purified water from the product water side into the membrane module at a flow rate of 1.5 to 2.0 times the normal water production flux, continuously flush for a first preset time, and use the reverse liquid flow shear force to peel off the loose deposit layer on the membrane surface.

[0015] Further, step S300 specifically includes: the air-water mixed scrubbing procedure is configured as follows: while turning on the backwash pump, the air source inlet valve is opened to inject clean compressed air into the membrane module in a pulse air intake manner, so that the gas-liquid mixed flow forms turbulence in the membrane module and drives the membrane fibers to generate high-frequency vibration. After continuous scrubbing for a second preset time, the air intake is stopped and the high-pressure pump is controlled to perform a high-flow forward flush to discharge the stripped blockage from the system.

[0016] Further, step S400 specifically includes: The control system sequentially closes the inlet electric valve, concentrate discharge valve, and permeate electric valve of the membrane module to form a completely sealed pressure testing chamber; the air supply valve is then opened to inject clean air into the pressure testing chamber until the pressure inside the chamber reaches the preset test pressure. Then the gas supply valve is closed and the pressure stabilization phase begins.

[0017] Further, step S400 specifically includes: after the pressure stabilization phase ends, recording the pressure value at the start of the test. After the preset pressure holding time Then, record the pressure value at the end of the test. Calculate the pressure decay rate ,like If the damage exceeds the safety tolerance, the system determines that the membrane filament has physical damage, executes the locking command, and issues a maintenance alarm; if If the temperature is less than or equal to the safety tolerance, the system determines that the membrane integrity is qualified, automatically opens the concentrate discharge valve and the inlet electric valve to perform low-pressure water replacement and venting, and returns to standby state after the gas in the chamber is discharged.

[0018] An automatic control system for piped drinking water membrane filtration includes: The data acquisition and processing module is configured to communicate with the inlet water pressure sensor, product water pressure sensor, and flow meter in the membrane filtration pipeline. It is used to acquire the system's operating parameters in real time and calculate the current transmembrane pressure difference of the membrane module based on these parameters. The fouling characteristic identification module is connected to the data acquisition and processing module and is configured to receive the transmembrane pressure difference value, monitor its trend over time, and calculate the rate of change of the transmembrane pressure difference per unit time. This module internally stores a preset fouling judgment threshold, which is used to compare the calculated rate of change of the transmembrane pressure difference with the fouling judgment threshold to output an identification signal indicating whether the membrane module is currently in a deposition-type or blockage-type fouling state. The adaptive cleaning execution module is connected to the fouling characteristic identification module and the high-pressure pump, backwash pump, and air source valve in the system. The system is connected to pipeline valve groups and configured to execute corresponding cleaning strategies based on the received identification signals: when a sediment-type contamination status signal is received, the system controls the pipeline valve groups and backwash pump to perform a hydraulic backwashing procedure; when a blockage-type contamination status signal is received, the system controls the pipeline valve groups, backwash pump, and air source valves to perform an air-water mixed scrubbing procedure; the integrity self-check and safety lock module is configured to monitor the water production operation status of the system. When it is determined that the system is in a non-water production standby state and the duration meets the preset conditions, the system automatically controls the valve groups to form a sealed cavity for the membrane module and controls the air source to pressurize the sealed cavity; this module monitors the pressure decay rate during the pressure holding period in real time, and when the pressure decay rate exceeds the preset safety tolerance, it generates a lock command to forcibly stop the system's water production function and outputs an alarm signal.

[0019] Beneficial effects Compared with known public technologies, the technical solution provided by this invention has the following beneficial effects: Compared with existing technologies, this invention effectively eliminates the interference of ambient temperature changes and pipeline noise on system perception by introducing temperature correction and signal filtering algorithms based on fluid viscosity characteristics, significantly improving the authenticity and accuracy of transmembrane pressure difference monitoring. By monitoring the rate of change characteristics of transmembrane pressure difference, it achieves the identification of the mechanisms of deposition-type and blockage-type fouling, and adaptively matches low-loss hydraulic backwashing or high-intensity air-water pulse scrubbing accordingly, greatly extending the service life of membrane modules while reducing operating energy consumption. More importantly, it constructs a membrane integrity self-checking mechanism based on the pressure decay principle, which can automatically detect the risk of tiny membrane filament ruptures that existing sensors cannot identify during non-water production periods, and promptly fuse and lock them, filling the safety blind spot in the direct drinking water industry in terms of microbial leakage monitoring and ensuring the drinking water safety of end users. Attached Figure Description

[0020] Figure 1 This is a flowchart of the overall control method of the present invention; Figure 2This is a flowchart illustrating the pollution type identification logic of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but includes other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings: Example: As shown in the figure S100: Real-time acquisition of operating parameters of the membrane filtration system, including at least the inlet water pressure, product water pressure and product water flow rate of the membrane module, and real-time calculation of the current transmembrane pressure difference value of the membrane module based on the operating parameters; The specific implementation process is as follows: S101: First, raw analog signals are acquired using sensors placed at key nodes of the membrane module. Specifically: Water inlet end: Equipped with a first pressure transmitter for real-time acquisition of water inlet pressure.

[0024] Concentrate end: A second pressure transmitter is installed upstream of the concentrate regulating valve to collect the concentrate discharge pressure. .

[0025] Product water end: A third pressure transmitter is installed at the product water outlet to collect product water back pressure. ; Raw water pipeline: Equipped with a high-precision temperature sensor for real-time monitoring of fluid temperature. .

[0026] S102: The high-pressure pump in the direct drinking water system generates high-frequency mechanical vibrations during operation, resulting in sawtooth-like fluctuations (noise) in the instantaneous pressure signal. Directly using the instantaneous value for calculation can easily trigger false alarms. Therefore, this step employs a **moving average filtering algorithm** to clean the raw data. The system establishes a first-in, first-out (FIFO) data queue of length N.

[0027] The specific logic is as follows: each time a new pressure value is collected... This is used to push the data into the queue, and the earliest data is removed. Calculate queue The arithmetic mean of the data points is used as the current effective pressure value. This process effectively smooths out pressure fluctuations and ensures the stability of subsequent calculations.

[0028] S103: In cross-flow filtration mode, there is a pressure loss along the membrane module between the feed water end and the concentrate end. To more accurately reflect the average pressure on the membrane surface, this embodiment abandons the traditional coarse algorithm that only uses "feed water pressure minus product water pressure," and instead uses the following formula to calculate the real-time physical transmembrane pressure difference.

[0029]

[0030] in, and This represents the average pressure on the inlet side of the membrane fiber.

[0031] S104: In winter, the water viscosity is high, and even if the membrane is clean, the transmembrane pressure difference will naturally increase to maintain the same flow rate; conversely, the pressure difference will naturally decrease in summer. To distinguish whether the "increased pressure difference" is due to "membrane dirt" or "cold weather," normalization processing is necessary.

[0032] Introducing temperature correction factor Under the current working conditions Converted to standard transmembrane pressure at standard temperature The correction formula is: .

[0033] Example scenario: Assuming it is currently winter, the water temperature System test

[0034] Without calibration, 0.15 MPa may already be close to the cleaning threshold.

[0035] After correction: .

[0036] After correction, it was found that The pressure drop is well below the contamination threshold, indicating that the membrane module is very clean. The high pressure drop is only due to water cooling, so the system will not erroneously trigger the cleaning procedure, thus avoiding energy waste and water production interruption.

[0037] S200: Monitor the trend of the transmembrane pressure difference value over time, calculate the rate of change of the transmembrane pressure difference per unit time, and compare the rate of change of the transmembrane pressure difference with a preset fouling determination threshold to identify whether the current fouling type of the membrane module is deposition-type fouling or blockage-type fouling.

[0038] The specific implementation process is as follows: S201: The control system has a preset sliding time window. and a pollution change rate threshold .

[0039] The sliding time window is preferably set to 10 to 30 minutes. This window is used to capture a continuous segment of pressure operation data to avoid the interference of random fluctuations in single-point data with the judgment.

[0040] The rate of change threshold is set based on the antifouling performance curves and historical experimental data provided by the membrane module manufacturer. In this embodiment, for the ultrafiltration membrane system, the threshold is set as follows: .

[0041] S202: The system uses the "sliding window differentiation method" to calculate the slope of the pressure difference increase in real time. Assume the current time is... The system extracts from arrive within the time period Data sequence. The calculation formula is:

[0042] in, This represents the pressure difference at the current moment. This represents the pressure difference at the start of the window.

[0043] S203: The system compares the calculated real-time rate of change with a preset threshold and, in conjunction with the current absolute value of the differential pressure, makes the following three judgments: Scenario 1: Determination of sedimentary contamination (filter cake layer formation) Judgment conditions: ,when A positive but small value indicates a slow, linear increase in transmembrane pressure. This typically corresponds to the gradual accumulation of suspended particles and colloids on the membrane fiber surface, forming a loose "filter cake".

[0044] Scenario 2: Determination of Blockage-Type Pollution: Judgment conditions: ,when A sharp increase in the value indicates an exponential surge in the transmembrane pressure differential. This typically occurs due to sudden changes in raw water quality (such as a surge in raw water turbidity caused by heavy rain) or severe adsorption-induced blockage within the membrane pores. An "accumulation-type fouling" signal is output. If this type of fouling is not treated promptly, it will lead to irreversible flux decline; therefore, the powerful "air-water mixed scrubbing" method in subsequent step S300 must be triggered immediately.

[0045] Scenario 3: Normal operation or self-recovery Judgment conditions: If the differential pressure is stable or decreases, it indicates that the system is operating normally or has just completed an effective cleaning. The system maintains its current water production state and does not trigger the cleaning procedure.

[0046] S300: Based on the type of contamination identified in step S200, adaptively match and execute the cleaning control strategy: when the contamination is identified as sediment-type, the control system executes a hydraulic backwashing procedure; when the contamination is identified as clogging-type, the control system executes an air-water mixed scrubbing procedure. The specific implementation process is as follows: S301: When the system receives a "depositional fouling" signal (i.e., the filter cake layer is slowly thickening), it indicates that the pollutants are mainly attached to the membrane surface and have weak adhesion. At this time, the system performs a low-intensity hydraulic backwash, the specific process of which is as follows: The controller sends a shutdown command to the high-pressure feed pump and simultaneously fully opens the concentrate discharge valve, rapidly reducing the pressure within the membrane module to atmospheric pressure. It then closes the feed electric valve and opens the backwash electric valve on the permeate side. The backwash pump starts, drawing purified water from the permeate tank and injecting it back into the permeate end of the membrane module. The controller adjusts the inverter frequency of the backwash pump to achieve a backwash flux of 1.5 to 2.0 times the normal permeate flux. The backwash process is maintained for 30 to 60 seconds (the first preset duration). After completion, the backwash pump is shut off, and the normal permeate valve position is restored.

[0047] S302: When the system receives a "clogging fouling" signal (i.e., a sharp drop in permeability), it indicates that contaminants have partially entered the membrane pores or are tightly adsorbed. Simple water washing is no longer effective, and the system automatically upgrades to perform a high-intensity air-water mixed scrubbing process. The specific procedure is as follows: While starting the backwash pump (maintaining low-flow backwash water, approximately 0.5 times the flux), open the air inlet valve at the bottom of the membrane module; the system does not continuously supply air, but instead controls the air source valve to perform pulsed air intake at a frequency of "open for 3 seconds - close for 3 seconds"; maintain the above air-water pulse operation for 60 to 120 seconds; after the scrubbing is completed, first close the air source valve to stop air intake. Subsequently, the system does not immediately produce water, but instead starts the high-pressure water inlet pump and fully opens the concentrate discharge valve to perform a high-flow forward flush for 15 to 30 seconds.

[0048] S400: Monitors the water production operation status of the system. When the system is determined to be in a non-water production standby state and the duration meets the preset conditions, it triggers the membrane integrity self-test program: controls the valve group to form a closed cavity for the membrane module, fills the closed cavity with gas to the test pressure and maintains it, and monitors the pressure decay rate during the pressure holding period in real time. If the pressure decay rate exceeds the preset safety tolerance, a lock command is generated to forcibly stop the system from producing water and outputs an alarm signal.

[0049] Traditional direct drinking water systems rely solely on a TDS (Total Dissolved Solids) probe at the water production end to detect water quality. However, when tiny ruptures occur in the membrane fibers, the TDS value often doesn't change significantly, but bacteria and viruses (nanometer-sized) can still penetrate the membrane wall, posing a serious safety hazard. To address this "invisible killer" problem, step S400 introduces a medical-grade membrane integrity self-test procedure.

[0050] The specific implementation process is as follows: S401: The system controller has a built-in clock module and a flow logic judgment module.

[0051] Triggering conditions: The system will automatically enter self-test mode when both of the following conditions are met: The current time is in a preset "off-peak period" (e.g., 02:00 to 04:00). The flow meter detected no user water demand for 30 consecutive minutes.

[0052] Constructing a sealed chamber: The controller issues commands to sequentially close the inlet electric valve, concentrate discharge regulating valve, and permeate electric valve of the membrane module. At this point, the membrane module housing (membrane shell) physically forms a completely isolated closed container.

[0053] S402: Open the air source solenoid valve connected to the inlet (or raw water) side of the membrane module, and use clean compressed air to force out some of the water stored in the membrane module through the dedicated exhaust / drain port (or directly pressurize the top headspace) until the pressure inside the chamber reaches the preset test pressure. It should be noted that Set to 0.10 MPa.

[0054] During the pressure stabilization phase, the gas source solenoid valve is closed. Due to temperature changes and volume expansion during the initial gas injection, the system performs a pressure stabilization wait of 30 to 60 seconds until the pressure reading fluctuations stabilize.

[0055] S403: Pressure decay monitoring, entering the formal testing phase, the system executes the following logic: Data recording: Record the initial pressure at the end of the voltage stabilization process. ; Pressure holding timer: Maintain a sealed state for 3 to 5 minutes (preset pressure holding time) ); Endpoint sampling: After the timing ends, record the final pressure; Rate calculation: The controller calculates the pressure decay rate using the following formula. :

[0056] S404: The system will calculate With the preset safety tolerance value , Scenario 1: Completeness meets requirements

[0057] Physical meaning: This indicates that the membrane system has good airtightness, the membrane fibers are not broken, and the sealing rings are not aging and leaking.

[0058] Reset Operation (Exhaust Logic): This is a critical engineering step. To prevent residual gas from causing cavitation (air lock) in subsequent water pumps, the system first opens the concentrate discharge valve, then slightly opens the inlet electric valve, using low-pressure raw water to slowly push the air out of the membrane housing until it is full of water. After that, the system returns to "standby mode" and is ready to respond to water production needs at any time.

[0059] Scenario 2: Integrity Failure

[0060] Physical meaning: A rapid pressure drop indicates that gas on the high-pressure side has leaked quickly to the low-pressure side through physical damage points (such as broken membrane pores), and the membrane module has lost its ability to retain bacteria.

[0061] Circuit breaker operation (safety lockout): Hardware lockout: The controller immediately cuts off the power supply circuit of the high-pressure pump and forcibly closes the electric valve for producing water, physically cutting off the path for substandard water to enter the user's pipeline network.

[0062] Alarm push notification: The "emergency alarm for membrane filament damage" is pushed to the administrator's mobile phone via the IoT module, and the specific leakage rate value is displayed.

[0063] Manual reset: The system enters a "deadlock" state, which cannot be cleared automatically. It can only be unlocked after maintenance personnel replace the membrane module and enter the "maintenance completion password".

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic control method for membrane filtration of piped drinking water, characterized in that, Includes the following steps: S100: Real-time acquisition of operating parameters of the membrane filtration system, including at least the inlet water pressure, product water pressure and product water flow rate of the membrane module, and real-time calculation of the current transmembrane pressure difference value of the membrane module based on the operating parameters; S200: Monitor the trend of the transmembrane pressure difference value over time, calculate the rate of change of the transmembrane pressure difference per unit time, and compare the rate of change of the transmembrane pressure difference with a preset fouling determination threshold to identify whether the current fouling type of the membrane module is deposition-type fouling or blockage-type fouling. S300: Based on the type of contamination identified in step S200, adaptively match and execute the cleaning control strategy: when the contamination is identified as sediment-type, the control system executes a hydraulic backwashing procedure; when the contamination is identified as clogging-type, the control system executes an air-water mixed scrubbing procedure. S400: Monitors the water production operation status of the system. When the system is determined to be in a non-water production standby state and the duration meets the preset conditions, it triggers the membrane integrity self-test program: controls the valve group to form a closed cavity for the membrane module, fills the closed cavity with gas to the test pressure and maintains it, and monitors the pressure decay rate during the pressure holding period in real time. If the pressure decay rate exceeds the preset safety tolerance, a lock command is generated to forcibly stop the system from producing water and outputs an alarm signal.

2. The automatic control method for membrane filtration of piped drinking water according to claim 1, characterized in that, Step S100 specifically includes: The control system synchronously collects the inlet water pressure of the membrane module according to a preset sampling frequency. Concentrate pressure Water production pressure and raw water temperature The collected pressure data is denoised using a moving average filtering algorithm to obtain a stable pressure value. Calculate real-time transmembrane pressure difference : And using temperature correction coefficient The real-time transmembrane pressure difference is converted to the standard transmembrane pressure difference value at standard temperature, wherein... The standard transmembrane pressure difference value is used as the transmembrane pressure difference value for monitoring and comparison in step S200.

3. The automatic control method for membrane filtration of piped drinking water according to claim 2, characterized in that, Step S200 specifically includes: Pre-set a sliding time window and a pollution change rate threshold The control system calculates the average rate of change of the transmembrane pressure difference within the current sliding time window every preset period during operation. ,in, In the formula, This represents the transmembrane pressure difference at the end of the window. This represents the transmembrane pressure difference at the start of the window; If the rate of change satisfy The membrane module was determined to be in a deposition-type fouling state with a slow increase in the filter cake layer; If the rate of change satisfy The membrane module is determined to be in a clogging-type fouling state, characterized by rapid adsorption or blockage of membrane pores.

4. The automatic control method for membrane filtration of piped drinking water according to claim 3, characterized in that, Step S300 specifically includes: The hydraulic backwashing procedure is configured as follows: stop the high-pressure pump and open the concentrate discharge valve, control the backwash pump to inject the purified water from the production water side into the membrane module at a flow rate of 1.5 to 2.0 times the normal water production flux, continuously flush for a first preset time, and use the reverse liquid flow shear force to peel off the loose deposit layer on the membrane surface.

5. The automatic control method for membrane filtration of piped drinking water according to claim 4, characterized in that, The step S300 specifically includes: the air-water mixed scrubbing procedure is configured as follows: while turning on the backwash pump, the air source inlet valve is opened to inject clean compressed air into the membrane module in a pulse air intake manner, so that the gas-liquid mixed flow forms turbulence in the membrane module and drives the membrane fibers to generate high-frequency vibration. After the second preset scrubbing time is continuously scrubbed, the air intake is stopped and the high-pressure pump is controlled to perform a high-flow forward flush to discharge the stripped blockage from the system.

6. The automatic control method for membrane filtration of piped drinking water according to claim 5, characterized in that, Step S400 specifically includes: The control system sequentially closes the inlet electric valve, concentrate discharge valve, and permeate electric valve of the membrane module to form a completely sealed pressure testing chamber; the air supply valve is then opened to inject clean air into the pressure testing chamber until the pressure inside the chamber reaches the preset test pressure. Then the gas supply valve is closed and the pressure stabilization phase begins.

7. The automatic control method for membrane filtration of piped drinking water according to claim 6, characterized in that, Step S400 specifically includes: after the pressure stabilization phase ends, recording the pressure value at the start of the test. After the preset pressure holding time Then, record the pressure value at the end of the test. Calculate the pressure decay rate ,like If the damage exceeds the safety tolerance, the system determines that the membrane filament has physical damage, executes the locking command, and issues a maintenance alarm; if If the temperature is less than or equal to the safety tolerance, the system determines that the membrane integrity is qualified, automatically opens the concentrate discharge valve and the inlet electric valve to perform low-pressure water replacement and venting, and returns to standby state after the gas in the chamber is discharged.

8. An automatic control system for piped direct drinking water membrane filtration, and an automatic control method for piped direct drinking water membrane filtration according to any one of claims 1-7, characterized in that, The system includes: The data acquisition and processing module is configured to communicate with the inlet water pressure sensor, product water pressure sensor and flow meter in the membrane filtration pipeline, and is used to acquire the operating parameters of the system in real time, and calculate the current transmembrane pressure difference value of the membrane module in real time based on the operating parameters. The contamination feature identification module is connected to the data acquisition and processing module and is configured to receive the transmembrane pressure difference value, monitor its change trend over time, and calculate the rate of change of transmembrane pressure difference per unit time. The module internally stores a preset contamination judgment threshold, which is used to compare the calculated rate of change of transmembrane pressure difference with the contamination judgment threshold to output an identification signal indicating whether the membrane module is currently in a deposition-type contamination state or a blockage-type contamination state. An adaptive cleaning execution module is connected to the contamination feature identification module and the high-pressure pump, backwash pump, air source valve, and pipeline valve group in the system, respectively. It is configured to execute the corresponding cleaning strategy according to the received identification signal: when a deposition-type contamination status signal is received, the pipeline valve group and backwash pump are controlled to execute a hydraulic backwashing procedure; when a blockage-type contamination status signal is received, the pipeline valve group, backwash pump, and air source valve are controlled to execute an air-water mixed scrubbing procedure. The integrity self-check and safety lock module is configured to monitor the water production operation status of the system. When it is determined that the system is in a non-water production standby state and the duration meets the preset conditions, the module automatically controls the valve group to form a sealed cavity for the membrane module and controls the air source to pressurize the sealed cavity. The module monitors the pressure decay rate during the pressure holding period in real time, and when the pressure decay rate exceeds the preset safety tolerance, it generates a lock command to forcibly stop the water production function of the system and outputs an alarm signal.

Images