A backwash control system for a rotary drum microfilter

Abstract

The application discloses a backwashing control system of a rotary drum microfilter, wherein a microporous filter screen is arranged on the surface of the rotary drum; a driving device is configured to drive the rotary drum to rotate; a backwashing device is configured to wash the filter screen of the rotary drum to remove the trapped impurities; a sensor group is configured to monitor the operating parameters of the rotary drum microfilter, wherein the sensor group comprises a plurality of differential pressure sensors which are distributed along the circumference of the rotary drum and are configured to monitor the transmembrane pressure difference at different circumferential positions of the rotary drum filter screen respectively, so as to form the circumferential pollution distribution information of the rotary drum filter screen; and the backwashing device and the driving device are controlled in cooperation, so that during the backwashing process, the rotary drum rotates at a cooperative rotating speed which is lower than the filtering rotating speed, and the washing action of the backwashing device is matched with the rotating position of the rotary drum in real time. The scheme can improve the backwashing effect of the filter screen, and further improve the filtering capacity of the rotary drum.

Description

Technical Field

[0001] This invention relates to the field of solid filtration equipment technology, and in particular to a backwashing control system for a rotary drum microfilter. Background Technology

[0002] Against the backdrop of the water treatment industry's pursuit of high efficiency, energy conservation, and intelligent operation, the rotary drum microfilter, as a key solid-liquid separation device in recirculating aquaculture, municipal water supply, and industrial wastewater treatment, primarily consists of a cylindrical rotating filter screen, a drive system, inlet and outlet water pipelines, and a backwashing device. This equipment uses the rotation of the drum to force the water to be treated through a microporous filter screen to achieve solid-liquid separation. The trapped impurities form a filter cake layer, which needs to be removed through backwashing to restore filtration capacity. In the specific functional module of backwashing control, existing technologies face the challenge of accurately determining the timing of backwashing, achieving uniform and efficient cleaning, and simultaneously controlling energy consumption under complex and changing water quality and operating conditions. With the increasing demands for the stability, economy, and automation level of water treatment systems, higher comprehensive requirements are being placed on the accuracy, adaptability, and economy of the backwashing control process.

[0003] However, existing or mainstream technologies commonly employ control methods based on fixed time intervals or single-location differential pressure thresholds, coupled with fixed-parameter flushing procedures. This approach has performance defects. Specifically, because the impurities trapped by the drum filter screen during operation have a naturally uneven circumferential distribution, sensors relying on single points or a few measuring points cannot accurately reflect the overall and local true pollution load, leading to inaccurate triggering decisions and a tendency for flushing lag or over-flushing. Simultaneously, the backwashing action usually lacks coordination with the drum's rotation, making it difficult for the flushing stream to cover the entire circumferential surface of the drum, creating cleaning blind spots and affecting filter recovery. Furthermore, fixed flushing parameters cannot adapt to fluctuations in influent water quality, flow rate, and other operating conditions, resulting in wasted water and electricity resources during light pollution and potentially incomplete cleaning during heavy pollution. The root cause of these defects lies in the fact that traditional technologies treat sensing, decision-making, and execution as relatively independent processes, failing to address the objective problems of dynamics and spatial unevenness in the drum filtration and flushing process from a system-wide collaborative perspective.

[0004] Therefore, a backwashing control scheme that can overcome the above-mentioned defects is needed to achieve precise triggering, uniform cleaning and efficient resource utilization under complex working conditions.

[0005] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0006] In view of the problems pointed out in the background art, the present invention provides a backwashing control system for a rotary drum microfilter.

[0007] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0008] In some embodiments of this application, a backwashing control system for a rotary drum microfiltration machine is provided, comprising:

[0009] A rotating drum, the surface of which is provided with a microporous filter screen;

[0010] A drive unit is configured to drive the drum to rotate;

[0011] The inlet and outlet are used for the inflow of water to be treated and the outflow of filtered water, respectively.

[0012] A backwashing device configured to rinse the filter screen of the rotating drum to remove trapped impurities;

[0013] A sensor array is configured to monitor the operating parameters of the rotary drum microfilter. The sensor array includes multiple differential pressure sensors distributed along the circumference of the drum. The multiple differential pressure sensors are configured to monitor the transmembrane pressure difference at different circumferential positions of the rotary drum filter screen to form information on the circumferential contamination distribution of the rotary drum filter screen.

[0014] The backwashing device and the drive device are controlled in coordination, so that during the backwashing process, the drum rotates at a coordinated speed lower than the filtration speed, and the rinsing action of the backwashing device is matched with the rotation position of the drum in real time.

[0015] In some embodiments of this application, a controller is also included, the controller being configured to:

[0016] Based on the transmembrane pressure difference monitored by the multiple differential pressure sensors, the average transmembrane pressure difference of the drum filter and the local transmembrane pressure difference at each measuring point in the circumferential direction are calculated.

[0017] The backwash trigger differential pressure threshold is dynamically calculated based on at least one of the following parameters: influent turbidity, filtration flow rate, drum motor current, and drum speed.

[0018] When the average transmembrane pressure difference reaches or exceeds the dynamically calculated backwash trigger pressure difference threshold, or the rate of change of the average transmembrane pressure difference reaches or exceeds the first preset rate of change threshold, or any of the local transmembrane pressure differences reaches or exceeds 1.2 times the dynamically calculated backwash trigger pressure difference threshold, the backwash process is initiated.

[0019] In some embodiments of this application, the controller is further configured to:

[0020] Periodic consistency checks are performed on the monitoring data of multiple sensors in the sensor group;

[0021] When a specific sensor data is found to be continuously abnormal, a preset redundant sensor or a prediction model trained based on historical data is activated to generate alternative data.

[0022] When the preset filter damage conditions are met based on monitoring data, the backwashing device is controlled to operate in emergency washing mode with increased washing intensity and / or extended washing time.

[0023] In some embodiments of this application, the backwashing process includes a sequentially executed air washing stage, a combined air-water washing stage, a variable flow water washing stage, and an osmotic pressure soaking stage.

[0024] During the air washing stage, the output air pressure of the control fan is increased in a stepwise manner within the range of 0.3MPa to 0.6MPa, and the washing is performed with a pulse frequency of 1Hz to 3Hz.

[0025] During the combined air-water washing stage, the blower and backwash pump are controlled to operate simultaneously, and the water washing pressure is controlled between 0.2 MPa and 0.4 MPa.

[0026] During the variable flow water washing phase, the backwash pump is controlled to output flushing water at a varying flow rate.

[0027] During the osmotic immersion phase, the flushing fluid output is stopped and the drum is submerged in the liquid for 10 to 30 seconds.

[0028] In some embodiments of this application, during the variable flow water washing stage, the backwash pump is controlled to operate at a first flow rate in the early stage of the stage and at a second flow rate less than the first flow rate in the later stage of the stage, wherein the first flow rate is 1.1 to 1.3 times the rated flow rate of the backwash pump, and the second flow rate is 0.7 to 0.9 times the rated flow rate.

[0029] In some embodiments of this application, during the air washing stage, when a local high pressure differential area is identified based on the circumferential pollution distribution information, the fan is controlled to flush the nozzles of the corresponding area at an enhanced pulse frequency of 3Hz to 5Hz.

[0030] In some embodiments of this application, the sensor group further includes at least two filter cake thickness sensors distributed along the axial direction of the drum, the filter cake thickness sensors being configured to monitor the filter cake thickness at different positions along the axial direction of the drum filter.

[0031] In some embodiments of this application, the backwashing device includes an annular water distributor with a plurality of nozzles arranged along its axial direction. The plurality of nozzles are configured to cover the entire axial length of the rotary drum filter, and the spray ranges of adjacent nozzles have a 30% to 50% overlap area.

[0032] In some embodiments of this application, the driving device includes a variable frequency motor, and the backwashing device includes a variable frequency fan and a variable frequency water pump;

[0033] The controller is also configured to adjust the operating frequency of the variable frequency motor, variable frequency fan and / or variable frequency water pump according to at least one of the real-time monitored flushing pressure, fluid density and temperature, based on a preset variable frequency adjustment formula.

[0034] In some embodiments of this application, a cloud server communicatively connected to the controller is also included for remote monitoring, data storage, and iterative training of optimization algorithms based on the controller's operating data.

[0035] Compared with the prior art, the advantages and positive effects of the present invention are:

[0036] This application's rotary drum microfilter breaks away from the conventional technology of separating sensing and monitoring from drum operation, and independently controlling backwashing and drum rotation. Specifically, it employs the following interconnected solutions: First, at the sensing level, multiple differential pressure sensors are innovatively distributed along the circumference of the drum. These sensors are configured to monitor the transmembrane pressure difference at different circumferential positions of the drum filter, thereby constructing a circumferential contamination distribution map of the drum filter. This provides a data foundation for accurately assessing the overall contamination load and identifying severely clogged areas. Second, at the control and execution level, the collaborative relationship between the backwashing device and the drive device is restructured. The controller is configured to drive the drum to a coordinated rotation speed significantly lower than the filtration speed during backwashing, and ensures that the start / stop of the backwashing device (such as a fan or pump), pressure / flow regulation, and the real-time rotational position of the drum are synchronously matched at the millisecond level via encoder feedback. This allows the flushing stream to sequentially and continuously cover the entire circumferential surface of the drum, fundamentally eliminating cleaning blind spots.

[0037] In the backwashing process itself, this solution employs a refined process involving multiple stages: air washing, combined air-water washing, variable-flow water washing, and osmotic pressure soaking. Parameters for each stage (such as air washing pressure and pulse frequency, water washing pressure and flow rate, and soaking time) are set with optimization ranges and can be locally enhanced based on contamination distribution information (e.g., increasing the pulse frequency in high-pressure differential areas). The variable-flow water washing stage uses a strategy of initial high-flow impact followed by low-flow rinsing, balancing cleaning power and water conservation. The introduction of the osmotic pressure soaking stage utilizes the physical mechanism of hydrostatic pressure difference promoting filter cake peeling.

[0038] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a structural diagram of a rotary drum microfiltration device according to some embodiments.

[0041] Figure label:

[0042] 100. Rotary drum; 200. Drive unit; 300. Sensor group; 310. Circumferential differential pressure sensor submodule; 320. Axial filter cake thickness sensor submodule; 330. Integrated monitoring submodule; 400. Backwashing device; 410. Fluid supply subsystem; 420. Fluid distribution subsystem; 430. Actuator valve group subsystem; 500. Controller; 600. Cloud server. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0045] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0046] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0047] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0048] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0049] This application provides a backwashing control system for a rotary drum microfilter, suitable for scenarios requiring solid-liquid separation in water, such as recirculating aquaculture, municipal water pretreatment, and industrial wastewater treatment. In, for example, an aquaculture recirculating water treatment system, the rotary drum microfilter removes suspended solids such as uneaten feed and feces from the water, and the treated clean water is returned to the aquaculture pond for reuse. The system needs to automatically backwash according to the filter's clogging status to maintain stable filtration capacity, while also considering backwashing effectiveness, water and energy conservation, and ensuring reliable operation under complex water quality fluctuations.

[0050] The backwashing control system framework for the rotary drum microfiltration machine provided in this application mainly includes: a rotary drum 100, a drive unit 200, a sensor group 300, a backwashing device 400, a controller 500, and an optional cloud server 600.

[0051] The rotary drum 100 is the core component for solid-liquid separation. A microporous filter screen is provided on the surface of the rotary drum 100. The inlet and outlet are for the inflow of water to be treated and the outflow of filtered water, respectively.

[0052] The drive unit 200 is mechanically connected to the drum 100, providing it with rotational power. The drive unit 200 drives the drum 100 to rotate.

[0053] The backwashing device 400 is configured to rinse the filter screen of the drum 100 to remove trapped impurities. The backwashing device 400 is connected to the rinsing area of ​​the drum 100 via pipes and valves to perform the rinsing action.

[0054] The backwashing device 400 and the drive device 200 are controlled in coordination, so that during the backwashing process, the drum 100 rotates at a coordinated speed lower than the filtration speed, and the rinsing action of the backwashing device 400 is matched with the rotation position of the drum 100 in real time.

[0055] Sensor array 300 is distributed and installed on the drum 100 and related pipelines to collect system operating status parameters. Sensor array 300 is configured to monitor the operating parameters of the drum microfilter. Sensor array 300 includes multiple differential pressure sensors distributed circumferentially along the drum. These multiple differential pressure sensors are configured to monitor the transmembrane pressure difference at different circumferential positions of the drum filter screen to form circumferential contamination distribution information of the drum filter screen.

[0056] The controller 500 is electrically connected to the sensor group 300, the drive device 200 and the backwashing device 400 via signal lines, and receives sensor data and issues control commands.

[0057] The cloud server 600 communicates with the controller 500 via wired or wireless network for remote data storage, monitoring, and iterative optimization of advanced algorithms. Under the coordination of the controller 500, these units collectively achieve intelligent triggering and coordinated flushing functions based on the sensing of circumferential contamination distribution in the drum.

[0058] In some embodiments, the main body of the drum 100 is a cylindrical structure that can rotate about its axis. The surface of this cylindrical structure is covered with a microporous filter screen. An inlet is provided at one end of the drum 100, through which the water to be treated enters the drum; an outlet is provided at the other end, through which the filtered clean water flows out. A sludge discharge trough is provided below or to the side of the drum 100 to collect impurities stripped off during backwashing. The cylindrical rotating structure of the drum 100 determines that the interception and distribution of pollutants in the circumferential direction of the filter screen has a natural non-uniformity, which is the physical basis for the sensing and decision-making in this solution.

[0059] The working mechanism of the rotary drum 100 is as follows: the water to be treated enters the interior of the rotary drum through the inlet. Driven by the liquid level difference or pump pressure, the water flows outward through the microporous filter screen on the surface of the drum, while suspended solid particles are trapped on the inner surface of the filter screen, gradually accumulating to form a filter cake layer. As filtration proceeds, the thickening of the filter cake layer leads to an increase in filtration resistance (i.e., transmembrane pressure difference). The continuous slow rotation of the rotary drum 100, on the one hand, makes the influent water more evenly distributed inside the drum, and on the other hand, lifts the trapped filter cake layer to the upper part of the drum, making it easier for the subsequent backwashing device 400 to remove it.

[0060] Under normal filtration conditions, the drum 100 and drive unit 200 work together to maintain a relatively stable rotational speed. During backwashing, according to the instructions of the controller 500, the drive unit 200 adjusts the rotational speed of the drum 100 to a lower, coordinated speed while maintaining the direction of rotation. The rotational angular position of the drum 100 is fed back to the controller 500 in real time via an encoder mounted on the shaft; this positional information is crucial for achieving real-time matching between the backwashing action and the drum position.

[0061] The dynamic operation of the drum 100 involves two main working states. In the first state, the normal filtration state, the drum 100 rotates continuously at the filtration speed, water continuously passes through the filter screen, and the filter cake layer gradually thickens uniformly or unevenly on the inner surface of the filter screen. In the second state, the backwashing state, when the triggering condition is met, the controller 500 controls the drive unit 200 to reduce the rotation speed of the drum 100 to a coordinated speed. At this time, the rotation of the drum 100 does not stop, but continues to rotate at a low speed, so that its entire circumferential surface can pass through the washing area of ​​the backwashing device 400 sequentially and slowly. This low-speed rotation ensures that the contact time between the washing fluid (air or water) and any point on the filter screen surface is long enough to achieve effective cleaning, while avoiding the problem that the lower half of the circumference area may not be washed if the rotation stops completely. In the final osmotic pressure soaking stage of the backwashing process, the drive unit 200 may control the drum 100 to stop rotating completely, so that it is completely submerged below the liquid level, and the static pressure difference promotes the peeling of the filter cake.

[0062] Sensor group 300 comprises multiple sensors with different functions, configured to monitor key physical parameters during the operation of the drum microfilter. Sensor group 300 acts as the system's sensory nervous system, providing real-time, multi-dimensional data input for the intelligent decision-making of controller 500. Its core components include multiple differential pressure sensors distributed circumferentially along the drum, filter cake thickness sensors distributed axially along the drum, and turbidity sensors, level sensors, flow sensors, and pressure sensors installed on the inlet and outlet water pipes. Data from sensor group 300 is the direct basis for triggering backwashing, adjusting backwashing parameters, and diagnosing equipment malfunctions.

[0063] In the sensor group 300, multiple differential pressure sensors are arranged circumferentially along the drum 100. In some embodiments, the number of differential pressure sensors is three to six, such as four, and they are distributed approximately evenly along the circumference of the drum. Each differential pressure sensor has two pressure taps: one located on the inner side of the drum filter screen (inlet side) and the other on the outer side of the drum filter screen (outlet side or atmospheric side). The sensor measures the pressure difference between these two taps, i.e., the real-time transmembrane pressure difference of the filter screen at that circumferential location. The values ​​measured by all differential pressure sensors are synchronously acquired by the controller 500 and, after processing, can form a circumferential contamination distribution information map reflecting the distribution of filter screen clogging along the entire circumference of the drum. For example, when a certain part of the drum is severely clogged due to a large accumulation of impurities, the corresponding differential pressure sensor reading will be significantly higher than other locations. This distributed measurement method overcomes the deficiency of single-point measurement in reflecting the uneven distribution of overall contamination. If there are fewer than three sensors, it may be impossible to accurately capture the characteristics of circumferential pollution distribution; if there are more than six, the system cost and complexity increase, while the incremental benefits decrease.

[0064] The sensor array includes at least two filter cake thickness sensors distributed along the axial direction of the drum. These sensors are configured to monitor the filter cake thickness at different positions along the axial direction of the drum's filter screen. The filter cake thickness sensors typically employ ultrasonic or microwave ranging principles, with their probes mounted on the outside of the drum 100 to non-contactly measure the thickness of the filter cake layer on the filter screen surface. Arranging at least two filter cake thickness sensors along the drum's axial direction, for example, at both ends and the middle of the drum, allows monitoring of whether the filter cake is uniformly piled in the axial direction.

[0065] The liquid level sensor is installed on the side wall of the microfilter housing to monitor the water level inside the drum, preventing overflow due to excessively high water levels or dry rotation of the drum due to excessively low water levels.

[0066] Turbidity sensors are installed on the inlet and outlet pipes, respectively, to monitor raw water quality and filtration efficiency. A flow sensor monitors the flow rate of the inlet or backwash water. A pressure sensor monitors the pressure in the backwash water and air lines.

[0067] Sensor group 300 operates continuously in its working sequence. During normal filtration, all sensors continuously collect data at a certain sampling frequency. Controller 500 processes the data from the differential pressure sensors in real time, calculating the average transmembrane differential pressure, the rate of change of differential pressure, and the differential pressure values ​​at each local measuring point of the drum filter. When sensor data becomes abnormal, such as when the reading of a differential pressure sensor deviates significantly from the trend of other sensor readings, or when the reading exceeds the reasonable range for an extended period, controller 500 initiates data consistency verification logic to determine if the sensor may be faulty. It may also activate redundant backup sensors or generate alternative data based on predictive models built from other sensor data to ensure the continuity of system control.

[0068] The backwashing device 400 is the mechanism that performs the cleaning action. According to the instructions of the controller 500, it supplies flushing fluid to the surface of the rotary drum filter screen according to a specific timing and parameters. The backwashing device 400 includes a flushing fluid supply subsystem, a fluid distribution subsystem, and an actuator valve assembly. The flushing fluid supply subsystem typically includes a backwash water pump and a Roots blower or air compressor. The fluid distribution subsystem mainly refers to an annular water (air) distributor. The actuator valve assembly includes multiple pneumatic or electric control valves used to switch between air and water paths and to regulate flow and pressure.

[0069] The backwashing device 400 includes an annular water distributor with multiple nozzles arranged axially on it. These nozzles are configured to cover the entire axial length of the drum filter, with adjacent nozzles having a 30% to 50% overlap in their spray range. The water distributor is annular, with its central axis parallel to the rotation axis of the drum 100 and typically located above or to the side of the drum. The annular water distributor consists of a main pipe and multiple branch pipes, each with a series of nozzles arranged axially. This nozzle arrangement ensures that its spray range covers the entire axial length of the drum filter. The spray ranges of adjacent nozzles are designed to have an overlap, for example, 30% to 50%, to ensure that any location along the axial direction of the drum is covered by the flushing stream, with no blind spots.

[0070] If the overlap area is too small (less than 30%), unwashed strips may form at the nozzle gaps; if the overlap is too large (greater than 50%), it will waste flushing fluid. The nozzle spray angle is adjustable to ensure that the flushing stream impacts the filter surface at the optimal angle.

[0071] The backwashing device 400 operates in a series of sequential stages, divided by the controller 500 and coordinated with the low-speed rotation of the drum 100. The backwashing process includes, in sequence, an air washing stage, a combined air-water washing stage, a variable flow water washing stage, and an osmotic pressure soaking stage.

[0072] The first stage is the air washing stage. During this stage, the output air pressure of the control fan is gradually increased within a stepwise range of 0.3 MPa to 0.6 MPa, and rinsing is performed with pulse frequencies from 1 Hz to 3 Hz. In other words, the controller 500 issues a command to open the air circuit control valve and start the fan. The air pressure output by the fan is gradually increased from its initial value to a set value between 0.3 MPa and 0.6 MPa, and pulsed at a frequency of 1 Hz to 3 Hz. The pulsed airflow generates shearing and impact on the filter cake, causing loosely attached impurities to detach. The duration of this stage is adjusted based on the calculated average filter cake thickness or pressure differential level.

[0073] The second stage is the combined air-water washing stage. During this stage, the blower and backwash pump operate simultaneously, with the water washing pressure controlled between 0.2 MPa and 0.4 MPa. In other words, while maintaining air washing, the controller 500 issues a command to start the backwash water pump and open the water control valve. The water washing pressure is controlled between 0.2 MPa and 0.4 MPa. At this time, the air-water mixture acts on the filter screen simultaneously, utilizing the combined action of water flushing and air oscillation to remove more stubborn contaminants. The duration of this stage can be adjusted within the range of 60 to 180 seconds.

[0074] The third stage is the variable flow rate water washing stage. In this stage, the backwash pump is controlled to output flushing water at varying flow rates. In other words, controller 500 closes the air circuit, keeping only the water circuit open. Initially, the backwash pump operates at a higher first flow rate, for example, 1.1 to 1.3 times the pump's rated flow rate, for powerful rinsing. Later in the stage, the flow rate is reduced to a lower second flow rate, for example, 0.7 to 0.9 times the rated flow rate, for rinsing and water conservation. This stage lasts between 40 and 100 seconds.

[0075] The fourth stage is the osmotic immersion stage. During this stage, the flushing fluid output is stopped, and the drum is submerged in the liquid for 10 to 30 seconds. In other words, the controller 500 shuts off all flushing fluid supply, allowing the drum 100 to be completely submerged in the liquid and held still for 10 to 30 seconds. The hydrostatic pressure difference (osmotic pressure) between the liquid inside and outside the drum further promotes the detachment of the filter cake layer from the filter screen.

[0076] Throughout the backwashing process, the drum 100 rotates at a low, coordinated speed of 0.5 to 1 revolution per minute, ensuring that the fixed nozzles of the annular water distributor can sequentially flush the entire circumferential surface of the drum. When a region is identified as having a particularly high pressure differential (severe local blockage) based on the circumferential contamination distribution information, the controller 500 can issue a command to the corresponding nozzle in that region during the air washing phase, increasing the pulse frequency to 3 to 5 Hz for enhanced local flushing.

[0077] The controller 500 is the core of the system's control, typically implemented using a programmable logic controller (PLC) or an industrial control computer (IPC). The controller 500 includes a central processing module, digital / analog input / output modules, a communication module, and a storage module. The controller 500 is configured to execute a series of processing steps to achieve intelligent triggering and coordinated control.

[0078] The controller is configured to: calculate the average transmembrane pressure difference of the drum filter and the local transmembrane pressure difference at each measuring point in the circumference based on the transmembrane pressure difference monitored by the plurality of differential pressure sensors; dynamically calculate the backwash trigger differential pressure threshold according to at least one of the parameters of influent turbidity, filtration flow rate, drum motor current and drum speed; and control the start of the backwashing process when the average transmembrane pressure difference reaches or exceeds the dynamically calculated backwash trigger differential pressure threshold, or the rate of change of the average transmembrane pressure difference reaches or exceeds a first preset rate of change threshold, or any of the local transmembrane pressure differences reaches or exceeds 1.2 times the dynamically calculated backwash trigger differential pressure threshold.

[0079] The controller is also configured to: perform periodic consistency checks on the monitoring data of multiple sensors in the sensor group; when a specific sensor data is found to be continuously abnormal, activate a preset redundant sensor or generate alternative data based on a prediction model trained on historical data; when the monitoring data determines that a preset filter damage condition is met, control the backwashing device to run an emergency flushing mode with increased flushing intensity and / or extended flushing time.

[0080] Specifically, the controller 500 periodically performs consistency checks on the data from the sensor group 300. For example, it checks whether the upward trend of differential pressure matches the upward trend of liquid level, and whether there is a reasonable correlation between the readings of each circumferential differential pressure sensor. When a sensor's data is found to be continuously abnormal (e.g., unchanged for a long time or fluctuating drastically), the controller 500 marks the sensor as faulty and switches to a preset redundant sensor (if available) to continue operation. If there is no redundant sensor, a predictive model trained based on historical data (e.g., linear regression or neural network model) is activated to use data from other relevant sensors to predict and replace the output value of the faulty sensor, ensuring the continuous operation of the control logic.

[0081] The controller 500 also presets specific filter damage judgment conditions. For example, when the effluent turbidity is detected to suddenly rise by more than 3 NTU in a short period of time (e.g., within 10 seconds), while the average transmembrane pressure difference of the drum filter does not increase significantly at the same time, the controller 500 determines that the filter may be partially damaged. Once the filter damage condition is met, the controller 500 will control the backwash device 400 to operate in emergency flushing mode. In this mode, the water flushing pressure may be increased by 20%, and the total flushing time may be extended by 50% to attempt to flush away impurities that may be stuck at the break or to perform a more thorough cleaning, while simultaneously issuing an audible and visual alarm to remind maintenance personnel.

[0082] The cloud server 600 is an optional expansion unit that establishes a secure communication connection with the controller 500 via the internet. The cloud server 600 receives historical operating data uploaded from one or more field controllers 500, including various sensor data, backwash event records, triggering conditions, parameters used, and post-backwash effect data (such as differential pressure drop rate). Leveraging its powerful computing and storage capabilities, the cloud server 600 runs machine learning algorithms, such as Long Short-Term Memory (LSTM) neural network models. This model uses historical data as a training set to learn the optimal control strategy under different operating conditions and periodically sends optimized model parameters or new control rules to the field controllers 500. This enables the entire system to transcend the experience accumulated by individual devices, achieving continuous self-optimization and performance improvement based on big data analytics.

[0083] In this application, circumferential contamination distribution information refers to a set of data that characterizes the differences in clogging or contamination levels of the drum filter at different circumferential angular positions, obtained by synchronously measuring and processing multiple differential pressure sensors distributed along the circumference of the drum. This information can be represented as a list of differential pressure values ​​corresponding to the circumferential angle, or further visualized as a one-dimensional distribution curve. Coordinated rotation speed refers to a specific low-speed operating state during backwashing, where the drum's rotation speed is adjusted to a significantly lower speed than the normal filtration speed and matched to the timing of the backwashing action, in order to ensure that the fixed-position backwashing devices sequentially cover the entire circumferential surface of the drum. This rotation speed range is between 0.5 revolutions per minute and 1 revolution per minute, ensuring sufficient contact time between the flushing stream and the filter surface.

[0084] As shown in the figure, the sensor group 300 provided in this application includes a circumferential differential pressure sensor submodule 310, an axial filter cake thickness sensor submodule 320, and an integrated monitoring submodule 330.

[0085] The circumferential differential pressure sensor submodule is configured to acquire information on the circumferential contaminant distribution of the drum filter screen. The axial cake thickness sensor submodule is configured to monitor the cake buildup along the axial direction of the drum. The integrated monitoring submodule includes turbidity sensors, level sensors, flow sensors, pressure sensors, and current sensors, used to collect auxiliary parameters for system operation.

[0086] These submodules connect to the input ports of the controller 500 via signal cables or fieldbuses, transmitting the acquired analog or digital signals to the controller 500 for processing. Data from the circumferential differential pressure sensor submodule is the core basis for triggering decisions; data from the axial filter cake thickness sensor submodule is used to assist in determining the pollution load; and data from the integrated monitoring submodule is used for system status monitoring, adaptive parameter adjustment, and fault diagnosis. All submodules work collaboratively to provide the controller 500 with comprehensive, multi-dimensional real-time system operating status information.

[0087] In some embodiments, the circumferential differential pressure sensor submodule includes multiple independent differential pressure sensors. The housings of these differential pressure sensors are made of 316 stainless steel, providing excellent corrosion resistance to suit water treatment environments. Each differential pressure sensor has a cylindrical body. The two pressure taps of the differential pressure sensor are connected to the inner (inlet chamber) and outer (outlet chamber or atmospheric side) of the rotary drum filter screen via a thin-diameter stainless steel tube or pressure-resistant hose, respectively.

[0088] In some embodiments, the circumferential differential pressure sensor submodule contains four differential pressure sensors. These four sensors are evenly distributed along the circumference of the drum 100, i.e., the central angle between adjacent sensors is 90 degrees. This even distribution design allows the submodule to adequately sample the contamination status of the drum's circumference at a reasonable cost. If the number of sensors is reduced to three with an adjacent angle of 120 degrees, although the cost is lower, it may not be able to adequately capture certain local contamination features; if the number is increased to six with an adjacent angle of 60 degrees, the sampling density is higher, but the cost and wiring complexity also increase accordingly.

[0089] The circumferential differential pressure sensor submodule independently measures the real-time transmembrane pressure difference at different circumferential angles of the drum filter screen. Transmembrane pressure difference refers to the pressure loss across the filter screen as water flows through it, directly reflecting the degree of clogging at that location. Each differential pressure sensor in the submodule continuously measures, and the controller 500 synchronously reads the values ​​from all sensors at a fixed sampling period (e.g., once per second). Through synchronous acquisition and data processing, the controller 500 constructs a set of differential pressure data sequences corresponding one-to-one with the circumferential angles of the drum, which constitutes the circumferential contamination distribution information of the drum filter screen. For example, when the filter cake is thicker at a certain point on the drum due to concentrated impurities in the influent or flow field factors, the differential pressure sensor reading at that point will be significantly higher than the readings at other locations. This distributed measurement method fundamentally changes the limitation of traditional single-point measurements, which can only reflect local conditions and cannot reveal overall uneven distribution. Based on the circumferential pollution distribution information, the controller 500 can not only calculate the overall average pressure difference to assess the overall degree of blockage, but also identify areas with severe local blockage, providing target location for possible subsequent localized enhanced flushing measures.

[0090] The circumferential differential pressure sensor submodule has a specific position and connection relationship with the drum 100 and controller 500. Multiple differential pressure sensors are fixed to the frame or housing of the drum 100 via mounting brackets, positioned around the circumference of the drum. The sensors themselves do not rotate with the drum, but their pressure taps are connected to the rotating part of the drum via rotary sealing joints or static pressure taps, ensuring continuous measurement of the differential pressure at various points on the rotating filter screen. The signal output of each differential pressure sensor is connected to a specific channel of the analog input module of the controller 500 via a shielded cable. The controller 500 can distinguish and read the data from each sensor by its module address and channel number. Furthermore, to ensure time synchronization, the power supply and sampling triggering of all differential pressure sensors can be uniformly controlled by the controller 500, or intelligent sensors with internal clock synchronization functions can be used for bus communication.

[0091] The circumferential differential pressure sensor submodule operates continuously. Throughout the normal filtration process of drum 100, all differential pressure sensors in the submodule measure and output data at a constant frequency (e.g., 1 Hz). Controller 500 receives this data in real time and performs subsequent processing. When the system enters the backwashing process, the differential pressure sensor submodule continues to operate, and its data can be used to monitor the decrease in differential pressure during the backwashing process, serving as a reference for evaluating the backwashing effect. After system startup or maintenance, controller 500 can perform a sensor calibration procedure, such as recording the initial zero-point offset value of each sensor while the filter is being cleaned, for compensation of subsequent measurements.

[0092] In some embodiments, the axial cake thickness sensor submodule includes at least two non-contact ranging sensors. These sensors may employ ultrasonic ranging or microwave ranging principles. The ultrasonic ranging sensor includes an ultrasonic transmitting probe and a receiving probe, the probe surface of which is typically covered with corrosion-resistant polytetrafluoroethylene (PTFE). The sensor is mounted on a fixed bracket on the outside of the drum 100, with its acoustic or microwave emission direction perpendicular to the drum's filter screen surface, measuring the distance from the probe to the outermost layer of the filter cake layer on the filter screen surface. The actual thickness of the filter cake can be calculated using a known reference distance from the clean filter screen surface to the probe. For example, installing a cake thickness sensor at each end and the middle of the drum's axial direction can monitor whether the filter cake is uniformly piled axially. The axial cake thickness sensor submodule provides axial dimension data from the three-dimensional distribution information of the filter cake. Combined with circumferential pressure differential distribution information, this allows the controller 500 to more comprehensively assess the contamination load, thereby more accurately determining the duration and intensity of backwashing. For example, when the filter cake is detected to be thicker in the middle and thinner at both ends axially, it can indicate uneven influent distribution, and the controller 500 can adjust the backwashing strategy accordingly.

[0093] In some embodiments, the turbidity sensor in the integrated monitoring submodule employs the principle of scattered light measurement, including an infrared LED light source and a photodetector, and is installed inside the flow tank. The level sensor, either hydrostatic or ultrasonic, is installed on the side wall of the microfilter housing. The flow sensor, which can be an electromagnetic flow meter or an ultrasonic flow meter, is installed on the inlet pipe or backwash water pipe. The pressure sensor, piezoresistive, is installed on the backwash water main and air main pipes. The current sensor, employing the Hall effect principle, is connected to the main power line of the drum drive motor. All these sensors convert the measured values ​​into standard electrical signals that are transmitted to the controller 500.

[0094] The circumferential differential pressure sensor submodule contains 3 to 6 differential pressure sensors, evenly distributed along the circumference of the drum. For example, in one embodiment, four differential pressure sensors are used, located at 0°, 90°, 180°, and 270° azimuths of the drum circumference. In another embodiment, six sensors are used, located at 0°, 60°, 120°, 180°, 240°, and 300° azimuths. This uniform distribution ensures the representativeness of the sampling points along the circumference, avoiding distortion of contamination distribution information caused by sensors concentrated in a single quadrant. This technique solves the problem that traditional single-point or two-point measurements cannot reflect circumferential contamination differences in the drum, providing the necessary data foundation for accurate decision-making based on contamination distribution. The resulting technical benefit is that the system can identify severe local blockages, avoiding the risk of a sharp decline in filtration capacity or equipment overload due to undetected localized high pressure differentials.

[0095] The sensor group 300 also includes at least two filter cake thickness sensor submodules distributed along the axial direction of the drum. For example, one can be installed near the inner side of each flange at both ends of the drum, and another can be installed at the center of the drum along the axial direction. The filter cake thickness data measured by these sensors can be correlated with the circumferential pressure difference data at the corresponding axial position for analysis. For example, when the average circumferential pressure difference at a certain axial position is high, and the measured filter cake thickness at that location is also large, it can be confirmed that the axial area is severely contaminated. This supplementary information allows for more precise setting of backwashing intensity and time parameters, avoiding insufficient or excessive backwashing that may result from relying on a single pressure difference parameter. For example, for areas with large filter cake thickness, the air washing or combined air-water washing time can be appropriately extended.

[0096] The backwashing device 400 provided in this application includes a fluid supply subsystem 410, a fluid distribution subsystem 420, and an actuator valve assembly subsystem 430.

[0097] The fluid supply subsystem 410 is configured to provide the gaseous and liquid media required for backwashing. The fluid distribution subsystem 420 is configured to evenly distribute and deliver the backwashing media to the surface of the rotary drum filter. The actuator valve assembly subsystem 430 is configured to precisely control the on / off state, flow rate, and pressure of each flow path according to instructions from the controller 500. The output of the fluid supply subsystem 410 is connected to the inlet of the actuator valve assembly subsystem 430 via piping, and the outlet of the actuator valve assembly subsystem 430 is connected to the fluid distribution subsystem 420. The controller 500 is connected to the individual control valve actuators in the actuator valve assembly subsystem 430 via a digital output module or fieldbus, sending on / off and adjustment commands. The core improvement of the backwashing device 400 lies in its deep coordination with the rotational motion of the rotary drum 100, and the ability of its backwashing parameters to be dynamically adjusted based on contamination distribution information.

[0098] In some embodiments, the core component of the fluid distribution subsystem 420 is an annular water distributor. The main body of the annular water distributor is an annular pipe, which may be made of UPVC or stainless steel. The central axis of the annular pipe is parallel to the rotation axis of the drum 100 and is typically positioned above the drum. The diameter of the annular pipe is slightly larger than the diameter of the drum to ensure it can surround the drum. Along the inner side of the annular pipe (towards the drum), multiple branch pipes are welded or threaded, extending axially along the drum. On each branch pipe, a series of nozzles are installed axially at fixed intervals. The nozzles may be fan-shaped spray nozzles with a spray angle, for example, 60 degrees. All nozzles are oriented so that their spray centerline points towards the surface of the drum filter screen and is slightly tilted downwards by approximately 10 degrees to optimize the impact effect. The nozzle density is calculated so that the spray coverage areas of adjacent nozzles on the drum filter screen surface overlap. The overlap rate is designed to be between 30% and 50%. This overlapping design ensures that at least one nozzle's jet stream can cover any position along the drum's axis, thus eliminating axial cleaning blind spots. If the overlap rate is too low (less than 30%), unwashed strips may remain in the gaps between the nozzles; if the overlap rate is too high (greater than 50%), it will result in a significant waste of rinsing media and may affect the rinsing effect due to mutual interference of the jet streams.

[0099] The fluid distribution subsystem 420 plays a crucial role in uniformly applying the flushing medium to the surface of the rotating drum filter screen. Its working mechanism involves high-pressure gas or water supplied from the actuator valve assembly subsystem 430 entering the annular main pipe of the annular distributor, then being distributed to various axial branch pipes, and finally sprayed out through nozzles at a specific speed and shape. The fan-shaped nozzles diffuse the fluid into a flat, fan-shaped surface, increasing the contact area with the filter screen surface. When the drum rotates slowly at a coordinated speed, the nozzle array on the stationary annular distributor sprays a stream of fluid that acts like a fixed brush, sequentially brushing across the entire circumference of the drum. This design achieves spatial matching between the flushing action and the drum position. In traditional designs, the spray pipes may only cover a portion of the circumference or axial area, or the lower half of the circumference may be unflushed when the drum stops. However, the combination of the annular distributor and the low-speed rotation of the drum in this design ensures that the 360-degree circumference and the entire axial length of the rotating drum filter screen are effectively flushed.

[0100] The annular water distributor is fixed to the microfilter frame by a support bracket, and its position is stationary relative to the rotating drum 100. The air / water inlet manifold of the annular water distributor is connected to the outlet of the actuator valve assembly subsystem 430 via a high-pressure hose or metal pipe. The actuator valve assembly subsystem 430 is connected to the fluid supply subsystem 410 via piping. The controller 500 is connected to each solenoid valve or electric regulating valve in the actuator valve assembly subsystem 430 via control cables, sending them on / off commands or analog regulation signals.

[0101] The backwashing device 400's operation is divided into multiple timing stages by the controller 500 and is strictly coordinated with the low-speed rotation of the drum.

[0102] In the first stage, the air washing stage, the controller 500 sends an opening command to the valves in the control air path of the actuator valve group subsystem 430, and simultaneously sends a start command and frequency setpoint to the variable frequency fan in the fluid supply subsystem 410. The compressed air generated by the fan enters the annular water distributor through the valve and is ejected from the nozzle. The air pressure increases stepwise from the initial value (e.g., 0.1 MPa) to 0.4 MPa within 30 seconds, and is pulsed on and off at a frequency of 2 Hz. At the same time, the drum rotates at a coordinated speed of 0.8 revolutions per minute under the drive of the drive unit 200.

[0103] In the second stage, the combined air-water washing stage, controller 500 keeps the air circuit open, simultaneously opens the valve controlling the water circuit, and starts the variable frequency water pump. The water pressure is controlled at 0.3 MPa, and the water pump operates at its rated frequency. At this time, air and water are sprayed simultaneously, and the drum continues to rotate at 0.8 revolutions per minute.

[0104] In the third stage, the variable flow water washing stage, controller 500 closes the air circuit valve and fan while keeping the water circuit open. For the first 30 seconds of this stage, the water pump operates at 1.2 times its rated frequency, outputting a higher flow rate; for the next 20 seconds, the pump frequency is reduced to 0.8 times its rated frequency, outputting a lower flow rate. The drum speed remains constant.

[0105] In the fourth stage, namely osmotic immersion, controller 500 closes all valves and water pumps, and the drum completely stops rotating under the control of drive unit 200 and remains stationary for 20 seconds, at which point the drum is completely submerged below the liquid level. Throughout the multi-stage rinsing process, the rotational speed of the drum is always coordinated with the duration of each stage, ensuring that the drum rotates a sufficient angle within each stage so that the entire circumference is treated by the rinsing mode of that stage.

[0106] During the air washing stage, when the controller 500 identifies a localized high-pressure differential area based on circumferential contamination distribution information, it can intensify the washing of specific nozzles or nozzle groups corresponding to that area. For example, if the differential pressure sensor reading at a 90-degree azimuth is abnormally high, the controller 500 can control the pulse valve in the actuator valve group subsystem 430, specifically serving the branch pipe at that azimuth, to increase the pulse frequency of that group of nozzles from the conventional 2 Hz to 4 Hz. This enhances the removal capability of stubborn local contaminants by increasing the number of impacts per unit time. This technique solves the problem of insufficient treatment intensity for key areas in globally uniform parameter washing, optimizes the allocation of washing resources, and improves overall washing efficiency.

[0107] The backwashing process includes sequentially executed air washing, combined air-water washing, variable flow water washing, and osmotic pressure soaking. The key parameters for each stage have optimization ranges.

[0108] The air pressure during the air washing stage should be controlled between 0.3 MPa and 0.6 MPa. If the air pressure is below 0.3 MPa, the shear force of the airflow on the filter cake may be insufficient; if it is above 0.6 MPa, it may cause impact damage to the filter structure and significantly increase energy consumption. The pulse frequency should be between 1 Hz and 3 Hz. If the frequency is too low, the pulse effect will be insignificant; if the frequency is too high, the valve life may be shortened.

[0109] During the combined air-water washing stage, the water pressure is controlled between 0.2 MPa and 0.4 MPa. The water pressure needs to be coordinated with the air pressure to form an effective mixed flush.

[0110] The initial flow rate during the variable flow washing stage is 1.1 to 1.3 times the rated flow rate of the pump, and the later flow rate is 0.7 to 0.9 times. The high initial flow rate ensures flushing force, while the low flow rate in the later stage achieves water conservation.

[0111] The osmotic immersion phase lasts from 10 to 30 seconds. Too short a time results in insufficient osmotic pressure action; too long a time affects the overall rinsing cycle. These parameter ranges were determined based on a balance point derived from fluid mechanics, filter cake shedding mechanisms, and extensive experimental data, optimizing energy and water consumption while ensuring effective rinsing.

[0112] The coordinated rotation speed is 0.5 to 1 revolution per minute (rpm). This speed range was determined through calculation and experimental verification. The effective contact distance and residence time of the nozzle jet need to be matched with this circumferential speed. If the speed is lower than 0.5 rpm, the rinsing efficiency is too low, prolonging the total backwashing time; if the speed is higher than 1 rpm, the contact time between the jet and a certain point on the filter screen is too short, which may lead to incomplete rinsing. Combining this speed with the duration of each stage ensures that the drum rotates at least once in each stage, thus guaranteeing full coverage.

[0113] The controller 500 internal processing framework provided in this application involves multiple software functional modules, mainly including: a data acquisition and preprocessing module, a dynamic threshold calculation module, a multi-condition trigger judgment module, a multi-stage collaborative control module, a fault diagnosis module, and a communication management module. These modules are stored as software programs in the controller 500's non-volatile memory and are scanned and executed by the central processing unit at predetermined cycles. The core improvement of the controller 500 lies in its processing algorithm, which fully utilizes circumferential contamination distribution information and achieves adaptive optimization and intelligent collaboration in the backwashing process.

[0114] The dynamic threshold calculation steps performed by controller 500 are as follows: The controller 500's data acquisition and preprocessing module reads the influent turbidity, filtration flow rate, drum motor current, and real-time drum rotation speed in real time. Simultaneously, it retrieves preset benchmark values ​​from its internal memory: benchmark differential pressure threshold, benchmark filtration flow rate, drum motor no-load current, drum rated rotation speed, and initial weighting coefficients. Subsequently, the dynamic threshold calculation module performs the calculation according to a specific formula.

[0115] The multi-condition trigger judgment steps executed by controller 500 are as follows: In each control cycle, the multi-condition trigger judgment module performs multiple judgments simultaneously. First, it calculates the average value of all current circumferential differential pressure sensor readings to obtain the average transmembrane differential pressure ΔP̄. It then determines whether ΔP̄ is greater than or equal to the dynamically calculated P_set. Second, it calculates the rate of change of ΔP̄ over the past minute, dΔP̄ / dt. It then determines whether dΔP̄ / dt is greater than or equal to a first preset rate of change threshold (e.g., 0.5 kPa per minute). This threshold is used to detect situations where the differential pressure rises rapidly. Even if the absolute differential pressure has not reached P_set, a rapid upward trend indicates accelerated blockage and requires early intervention. Third, it checks the local transmembrane differential pressure ΔP_i at each circumferential measuring point. It then determines whether any ΔP_i is greater than or equal to 1.2 times P_set.

[0116] This condition is specifically designed to detect severe localized blockages. Even if the average differential pressure is not high, if the differential pressure at a certain point is exceptionally high, flushing must be triggered to prevent localized damage or extremely uneven flow distribution. The above three conditions are combined using "OR" logic. As long as any one condition is true, the multi-condition triggering judgment module sends a backflushing start signal to the multi-stage collaborative control module.

[0117] In addition, this module also executes other auxiliary trigger judgments in parallel, such as determining whether the effluent turbidity is greater than 5 NTU, or whether the difference between influent and effluent turbidity is less than 2 NTU, or whether the liquid level is higher than 80% of the upper limit. These conditions are also connected with "OR" logic as supplementary guarantees to the aforementioned core conditions, ensuring that the system can operate safely under various abnormal operating conditions.

[0118] The multi-stage coordinated control steps executed by controller 500 involve precise timing and parameter control. Upon receiving a start signal, the multi-stage coordinated control module first sends a command to drive unit 200 to set the drum speed to the coordinated speed. Then, strictly following the sequence of air washing, combined air-water washing, variable flow water washing, and osmotic pressure soaking, it sequentially sends a series of control commands to the actuator valve group subsystem 430 and fluid supply subsystem 410. The duration, pressure setpoint, flow setpoint, pulse frequency, and other parameters of each stage can be fine-tuned based on specific data at the time of triggering (such as average differential pressure, local maximum differential pressure, and filter cake thickness). An internal timer within the module controls the switching between stages. Throughout the process, controller 500 continuously monitors key parameters, such as flushing water pressure, air pressure, and actual drum speed, and compares them with the setpoints. It then uses a PID control algorithm to fine-tune the inverter frequency or regulating valve opening to ensure the actual value tracks the setpoint.

[0119] The fault diagnosis steps performed by the controller 500 include periodic data verification and specific fault mode identification. The data verification module performs a consistency analysis on relevant sensor data every 10 seconds. For example, it checks whether the liquid level also tends to rise when the differential pressure increases (because increased filter resistance leads to a slower inlet flow rate and a rising liquid level); it checks whether there is a reasonable proportional relationship between the readings of the circumferential differential pressure sensors (e.g., there should not be a discontinuity where one reading is extremely high while adjacent readings are extremely low). If a sensor's data is found to be significantly contradictory to other data trends and persists for multiple cycles, the sensor is marked as suspicious. For sensors marked as suspicious, their data can be ignored in subsequent control, and a substitute value is estimated by the predictive model built into the fault diagnosis module based on other sensor data (such as differential pressure, flow rate, and turbidity at other locations). The specific fault mode identification module monitors filter damage conditions in real time. The condition is defined as follows: within two consecutive sampling periods, the increase in the effluent turbidity sensor reading exceeds 3 NTU, and simultaneously, the increase in the calculated average transmembrane pressure difference ΔP̄ compared to the previous period is less than a small threshold (e.g., 0.1 kPa). This is because when the filter is damaged, impurities pass directly through, causing a sudden increase in effluent turbidity, but the filter's own resistance (pressure difference) does not increase significantly. Once this condition is met, the controller 500 immediately triggers the emergency flushing mode. In this mode, the water flushing pressure setpoint is temporarily increased by 20%, the total time of the variable flow water flushing stage is extended by 50%, and the alarm output relay is activated, illuminating the alarm light or sending an alarm message to the host computer.

[0120] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0121] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A backwashing control system for a rotary drum microfilter, characterized in that, include: A rotating drum, the surface of which is provided with a microporous filter screen; A drive unit is configured to drive the drum to rotate; The inlet and outlet are used for the inflow of water to be treated and the outflow of filtered water, respectively. A backwashing device configured to rinse the filter screen of the rotating drum to remove trapped impurities; A sensor array is configured to monitor the operating parameters of the rotary drum microfilter. The sensor array includes multiple differential pressure sensors distributed along the circumference of the drum. The multiple differential pressure sensors are configured to monitor the transmembrane pressure difference at different circumferential positions of the rotary drum filter screen to form information on the circumferential contamination distribution of the rotary drum filter screen. The backwashing device and the drive device are controlled in coordination, so that during the backwashing process, the drum rotates at a coordinated speed lower than the filtration speed, and the rinsing action of the backwashing device is matched with the rotation position of the drum in real time.

2. The backwashing control system according to claim 1, characterized in that: It also includes a controller, which is configured to: Based on the transmembrane pressure difference monitored by the multiple differential pressure sensors, the average transmembrane pressure difference of the drum filter and the local transmembrane pressure difference at each measuring point in the circumferential direction are calculated. The backwash trigger differential pressure threshold is dynamically calculated based on at least one of the following parameters: influent turbidity, filtration flow rate, drum motor current, and drum speed. When the average transmembrane pressure difference reaches or exceeds the dynamically calculated backwash trigger pressure difference threshold, or the rate of change of the average transmembrane pressure difference reaches or exceeds the first preset rate of change threshold, or any of the local transmembrane pressure differences reaches or exceeds 1.2 times the dynamically calculated backwash trigger pressure difference threshold, the backwash process is initiated.

3. The backwashing control system according to claim 2, characterized in that: The controller is also configured to: Periodic consistency checks are performed on the monitoring data of multiple sensors in the sensor group; When a specific sensor data is found to be continuously abnormal, a preset redundant sensor or a prediction model trained based on historical data is activated to generate alternative data. When the preset filter damage conditions are met based on monitoring data, the backwashing device is controlled to operate in emergency washing mode with increased washing intensity and / or extended washing time.

4. The backwashing control system according to claim 1, characterized in that: The backwashing process includes, in sequence, an air washing stage, a combined air-water washing stage, a variable flow water washing stage, and an osmotic pressure soaking stage; During the air washing stage, the output air pressure of the control fan is increased in a stepwise manner within the range of 0.3MPa to 0.6MPa, and the washing is performed with a pulse frequency of 1Hz to 3Hz. During the combined air-water washing stage, the blower and backwash pump are controlled to operate simultaneously, and the water washing pressure is controlled between 0.2 MPa and 0.4 MPa. During the variable flow water washing phase, the backwash pump is controlled to output flushing water at a varying flow rate. During the osmotic immersion phase, the flushing fluid output is stopped and the drum is submerged in the liquid for 10 to 30 seconds.

5. The backwashing control system according to claim 4, characterized in that: During the variable flow water washing stage, the backwash pump is controlled to operate at a first flow rate in the early stage of the stage and at a second flow rate less than the first flow rate in the later stage of the stage, wherein the first flow rate is 1.1 to 1.3 times the rated flow rate of the backwash pump and the second flow rate is 0.7 to 0.9 times the rated flow rate.

6. The backwashing control system according to claim 4, characterized in that: During the air washing stage, when a local high pressure differential area is identified based on the circumferential pollution distribution information, the fan is controlled to flush the nozzles in the corresponding area with an enhanced pulse frequency of 3Hz to 5Hz.

7. The backwashing control system according to any one of claims 1 to 6, characterized in that: The sensor group also includes at least two filter cake thickness sensors distributed along the axial direction of the drum, the filter cake thickness sensors being configured to monitor the filter cake thickness at different positions along the axial direction of the drum filter screen.

8. The backwashing control system according to any one of claims 1 to 6, characterized in that: The backwashing device includes an annular water distributor with a plurality of nozzles arranged along its axial direction. The plurality of nozzles are configured to cover the entire axial length of the rotary drum filter, and the spray ranges of adjacent nozzles have a 30% to 50% overlap area.

9. The backwashing control system according to any one of claims 1 to 6, characterized in that: The drive device includes a variable frequency motor, and the backwashing device includes a variable frequency fan and a variable frequency water pump; The controller is also configured to adjust the operating frequency of the variable frequency motor, variable frequency fan and / or variable frequency water pump according to at least one of the real-time monitored flushing pressure, fluid density and temperature, based on a preset variable frequency adjustment formula.

10. The backwashing control system according to any one of claims 1 to 6, characterized in that: It also includes a cloud server that is communicatively connected to the controller for remote monitoring, data storage, and iterative training of optimization algorithms based on the controller's operating data.

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