An adjustable water quantity control system and method for a distribution well of a sewage treatment plant

Abstract

The application provides an adjustable water quantity control system and method for a distribution well of a sewage treatment plant. The system comprises: a plurality of siphon pipes, which are arranged in parallel between the water inlet area and each water outlet area of the distribution well, and are provided with an adjusting valve and a siphon breaking valve on each siphon pipe; a vacuum supply system connected to the top of each siphon pipe, which is used to independently vacuum each siphon pipe to form a siphon flow; a detection unit used to output the actual flow signal of each water outlet area in real time; and a controller used to receive the target flow instruction and the actual flow signal of each water outlet area. The controller selects a siphon pipe and vacuums to form a siphon flow in the starting stage; adjusts the opening degree of the adjusting valve according to the deviation between the actual flow and the target flow in the adjusting stage; and opens the siphon breaking valve and cuts off the vacuum supply in the stopping stage. The application realizes the rapid, accurate and automatic distribution of the water quantity of each stage of the distribution well, does not need an additional lifting pump, and significantly reduces the operation energy consumption and manual intervention.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment and automatic control technology, specifically relating to an adjustable water volume control system and method for water distribution wells in wastewater treatment plants, so as to achieve accurate and automatic allocation of influent volume for each stage of the process line and reduce the overall plant operating cost. Background Technology

[0002] Currently, with the advancement of upgrading and expansion projects for urban wastewater treatment plants, many plants are being constructed in phases. Due to technological advancements and land constraints, each phase may employ drastically different treatment processes. These processes differ significantly in investment, treatment efficiency, and especially in daily operating energy and material consumption (i.e., operating costs). To achieve the goals of energy conservation, consumption reduction, and optimized operation across the entire plant, ideally, more influent should be allocated to processes with lower operating costs.

[0003] However, currently, most wastewater treatment plants rely on fixed weirs, gates, or simple valves in distribution wells for rough, experience-based manual allocation between different production lines (phases). Existing solutions typically include: a main intake well containing multiple concrete distribution weirs leading to each phase of the process, with manual or electric gates installed on each outlet channel behind the weirs. Since the length of the weirs is fixed, the water allocation ratio for each phase is also fixed. To adjust the allocation ratio, there are generally two methods: the first is to submerge the fixed weirs and manually adjust the opening degree of the gates on each outlet channel to control the influent volume for each phase; the second is to add a lift pump to the main intake well to change the original allocation ratio of the fixed weirs.

[0004] The aforementioned prior art has the following drawbacks: The adjustment is lagging and inefficient: relying on manual inspection and operation, the adjustment cycle is long (hours or days), and it cannot respond to real-time fluctuations in water quality and quantity. At present, AI technology has the ability to realize production decision-making, dynamic scheduling and collaborative management of wastewater treatment plants. However, after the decision-making instructions are issued, the implementation end often fails to implement the instructions in a timely and accurate manner due to incomplete facilities.

[0005] High gate failure rate: The failure rate increases significantly when the gate operates frequently. For large gates, problems such as screw bending may even occur.

[0006] Increased energy consumption: Using pumps to lift sewage will directly increase energy consumption, which contradicts the original intention of sewage treatment plants to save energy and reduce consumption.

[0007] Therefore, providing an adjustable water volume control system and method that can quickly respond to superior dispatch instructions, accurately control the water inflow in each period, and has low operating energy consumption is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides an adjustable water volume control system and method for water distribution wells in wastewater treatment plants, overcoming the technical defects of existing technologies such as slow adjustment, high energy consumption, and high equipment failure rate.

[0009] This invention constructs a core architecture of "parallel siphon pipes + one-to-many shared vacuum system", which utilizes the siphon principle to achieve water delivery without power and achieves precise allocation of water intake in each period through closed-loop automatic control.

[0010] The system adopts a modular architecture, consisting of a parallel siphon unit, a vacuum supply system, a detection unit, and a controller. The units work together to form a complete closed-loop control system.

[0011] Specifically, this invention utilizes the siphon effect to achieve non-powered water delivery by connecting multiple siphon pipes in parallel between the inlet area and the outlet areas of each phase of the water distribution well. All siphon pipes share a single vacuum generator (vacuum pump) and vacuum holding device (vacuum buffer tank), connected to the top of each siphon pipe via a main vacuum pipe and vacuum branch pipes with on / off valves, achieving a shared vacuum supply for multiple siphon pipes. The controller receives target flow commands for each phase from the upper-level system and automatically adjusts the opening of the electric regulating valves at the outlet of each siphon pipe based on real-time flow feedback, forming a closed-loop control to achieve precise allocation of inlet water volume for each phase.

[0012] Thus, this invention realizes a complete closed loop from receiving flow command, starting the siphon, precise adjustment to stopping the siphon, significantly improving the automation level and adjustment accuracy of water distribution in the distribution well.

[0013] According to one aspect of the present invention, a water volume control system for a water distribution well in a wastewater treatment plant is provided, comprising: Multiple siphon pipes are connected in parallel between the water inlet area and the corresponding water outlet area of ​​the water distribution well. The water inlet end of each siphon pipe is located below the liquid level of the water inlet area, and the water outlet end is connected to the corresponding water outlet area. Each siphon pipe is equipped with a regulating valve and a siphon breaking valve. A vacuum supply system, connected to the top of each of the siphon tubes, is used to independently evacuate each of the siphon tubes to form a siphon flow; The detection unit includes at least a flow detection element disposed in each of the water outlet areas or on the downstream pipeline, for outputting the actual flow signal of each of the water outlet areas in real time; The controller has its input terminal connected to the detection unit to receive the actual flow signal and to receive the target flow command for each of the water outlet areas. The output terminal of the controller is respectively connected to the vacuum supply system, each of the regulating valves and each of the siphon breaking valves. The controller is further configured to: select a number of corresponding siphon tubes according to the target flow command during the startup phase, and control the vacuum supply system to evacuate the selected siphon tubes to form a siphon flow; calculate the flow deviation according to the actual flow signal and the target flow command during the adjustment phase, and adjust the opening of the regulating valve on the corresponding siphon tube according to the flow deviation to make the actual flow approach the target flow; and control the siphon breaking valve on the corresponding siphon tube to open during the shutdown phase to break the siphon, and then control the vacuum supply system to cut off the vacuum supply to the siphon tube.

[0014] In another aspect, the present invention provides a method for controlling the water volume of a distribution well in a wastewater treatment plant, comprising the following steps: Start-up phase: The controller receives the target flow instructions for each water outlet area, selects a number of corresponding siphon tubes according to the target flow instructions, and controls the vacuum supply system to evacuate the selected siphon tubes to form a siphon flow. Adjustment phase: The controller receives the actual flow signals of each of the water outlet areas in real time, calculates the flow deviation based on the actual flow signals and the target flow command, and adjusts the opening of the regulating valve on the corresponding siphon pipe according to the flow deviation to make the actual flow rate approach the target flow rate; Stopping phase: The controller controls the siphon breaking valve on the corresponding siphon tube to open to break the siphon, and then controls the vacuum supply system to cut off the vacuum supply to the siphon tube.

[0015] Compared with the prior art, the present invention has the following beneficial effects: Rapid response and precise control: The system response is automatically executed by the controller, and can be completed from receiving the command to adjustment and stabilization in minutes or even seconds, far exceeding manual operation (hours). Closed-loop control ensures that the flow rate can be accurately stabilized near the target value, such as in Example 3 where the actual flow rate is stably controlled within the range of 4000-4200 m³ / h.

[0016] Energy-saving and efficient: The core water conveyance power comes from the siphon effect (utilizing liquid level difference and atmospheric pressure), eliminating the need for additional water pumps to lift sewage. Only a small amount of electricity is consumed when drawing and maintaining vacuum (the power of the vacuum pump is much smaller than that of the sewage lift pump), which significantly reduces the energy consumption of the execution process and truly meets the original intention of energy conservation and consumption reduction.

[0017] Reliable operation and easy maintenance: The main moving parts are small electric valves and vacuum pumps, whose operating frequency and mechanical load are much lower than those of large gates and their hoists that require frequent regulation, resulting in a low failure rate and long service life. There are no rotating parts inside the siphon pipe, making it less prone to clogging and easy to maintain.

[0018] Perfectly integrated with intelligent decision-making systems: As a standard automated execution unit, this system can directly receive instructions from upper-level systems (such as AI optimization systems and central control rooms) through standard interfaces (such as 4-20mA, Modbus), solving the problem of disconnect between the "intelligent brain" and "traditional hands and feet", and realizing a closed loop of plant-wide optimized control. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application 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 only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall architecture of the adjustable water volume control system for a wastewater treatment plant distribution well provided in an embodiment of the present invention, showing the four core components—parallel siphon unit, vacuum supply system, detection unit, and controller—and their interrelationships. Figure 2 This is a flowchart of the adjustable water volume control method for a wastewater treatment plant distribution well provided in this embodiment of the invention, showing three main stages: start-up, adjustment, and shutdown. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0022] The embodiments of this invention are written in a progressive manner.

[0023] Terminology Explanation To facilitate understanding of the technical solution of this invention, some technical terms appearing in the specification are explained as follows: Siphon: refers to the physical phenomenon of using the difference in liquid level and atmospheric pressure to make liquid flow from a high level to a low level through a closed pipe.

[0024] Distribution well: A structure in a wastewater treatment plant used to receive and distribute incoming water to subsequent treatment units.

[0025] A multi-channel shared vacuum system refers to a system that uses the same set of vacuum generating equipment (vacuum pump) and vacuum main pipeline to provide and maintain the required vacuum level for multiple parallel siphon tubes.

[0026] PLC: Programmable Logic Controller, a digital computing and operating electronic system used for industrial control.

[0027] The terms used above are only for explaining specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art will understand that other existing technologies with the same or similar functions can be employed without departing from the concept of the present invention.

[0028] Example 1: System Architecture like Figure 1 As shown, this invention provides an adjustable water volume control system for a wastewater treatment plant's distribution well. Its core lies in using multiple siphon pipes connected in parallel between the inlet area and the outlet areas of each phase of the distribution well. This utilizes the siphon effect to achieve non-powered water delivery, and closed-loop automatic control enables precise allocation of the inlet volume for each phase. The system adopts a modular architecture, with four core components working collaboratively to achieve a complete closed loop from flow command reception to water volume allocation execution.

[0029] Specifically, the system includes the following functional components: The parallel siphon unit comprises multiple siphon pipes fixed side-by-side in different distribution wells. The inlet end of each siphon pipe is located below the normal liquid level of the inlet well, and the outlet end leads to the distribution weir. The diameters of the siphon pipes can be the same or different to cover different flow ranges. Each siphon pipe is equipped with an electric regulating valve and a siphon breaker valve.

[0030] The vacuum supply system, connected to the top of each siphon tube, is used to independently evacuate each siphon tube to form a siphon flow. Specifically, it includes: a common vacuum passage – the main vacuum pipe; a vacuum generator – a vacuum pump, connected to the common vacuum passage; multiple vacuum branches – vacuum branch lines, one end of each branch line connected to the common vacuum passage, and the other end connected to the top of each siphon tube; each branch line is equipped with an on / off valve – a vacuum branch solenoid valve, used to independently control the vacuum on / off of the corresponding siphon tube. The vacuum supply system also includes a vacuum holding device – a vacuum buffer tank, connected in series between the vacuum generator and the common vacuum passage, used to stabilize the vacuum level of the vacuum supply system, smooth vacuum fluctuations caused by vacuum pumping and single-tube start / stop, and ensure stable start-up and operation. The vacuum generator is a vacuum pump, and there are two vacuum pumps, one for each other and one as a backup. As a preferred embodiment, the vacuum pump has a flow rate of 140 L / min, a vacuum degree of -95 kPa, and a power of 0.75 kW; the response time of the vacuum pipeline solenoid valve is less than 0.5 s; and the response time of the siphon failure valve is less than 2 s.

[0031] The detection unit includes at least one flow detection element—an online flow meter—installed in each outlet area or its downstream pipeline, for real-time output of the actual flow signal of each outlet area. In a preferred embodiment, the detection unit further includes a first level gauge installed in the inlet area and a second level gauge installed in each outlet area, for assisting in calculating the current flow rate of each siphon pipe to correct the measured values ​​of the flow detection elements. The level gauges may be ultrasonic level gauges.

[0032] The controller's input is connected to the detection unit to receive the actual flow rate signal and to receive target flow rate commands for each outlet area. The controller's outputs are connected to the vacuum supply system (vacuum pump, on / off valves), regulating valves, and siphon breaker valves. The controller is a programmable logic controller (PLC, such as the Siemens S7-1500 series). By comparing the real-time flow rate with the target flow rate, the controller calculates the flow rate and adjustable range of siphons of different diameters at the current liquid level difference and selects the appropriate siphon to open.

[0033] The four components mentioned above work together to form a complete closed-loop system. When the upper-level system (such as the AI ​​optimization system and the central control room) issues the target flow instructions for each period, the controller selects the corresponding siphon tube according to the target flow and controls the vacuum supply system to evacuate the selected siphon tube to form a siphon flow. After the siphon is formed, the controller automatically adjusts the opening of the electric regulating valve according to the deviation between the actual flow and the target flow fed back by the online flow meter, so that the actual flow approaches the target flow. When it is necessary to stop, the controller controls the siphon breaking valve to open to break the siphon, and then controls the vacuum supply system to cut off the vacuum supply to the corresponding siphon tube.

[0034] All components are connected and communicate with each other through well-defined electrical interfaces and communication protocols (such as 4-20mA current signals and Modbus communication protocols) to ensure the scalability and stability of the system.

[0035] Example 2: General Process like Figure 2 As shown, the present invention provides an adjustable water volume control method for a wastewater treatment plant distribution well, comprising the following start-up phase, adjustment phase, and stop phase: S1. Startup Phase: Upon receiving the target flow instructions for each period from the upper-level system (such as the AI ​​optimization system or the central control room), the controller calculates the flow rate and adjustable range of siphons of different diameters under the current liquid level difference by comparing the difference between the real-time flow rate and the target flow rate, and selects to open the corresponding siphon. Specifically, the controller controls the opening of the solenoid valve of the vacuum branch corresponding to the selected siphon, and then starts the vacuum pump to evacuate the siphon through the vacuum main pipe and the vacuum buffer tank. When the air in the pipe is extracted to form a negative pressure, the water in the inlet well is forced into the siphon under atmospheric pressure, forming a siphon flow. The vacuum buffer tank can effectively suppress vacuum fluctuations caused by the vacuum pump's extraction and the start and stop of single pipes, ensuring stable startup and operation. After the siphon is formed, the vacuum pump switches to maintenance mode (intermittent operation).

[0036] S2. Adjustment Phase: The controller continuously receives the actual flow rate values ​​from the online flow meters in each effluent area and compares them with the target value. Through internal PID and other control algorithms, the controller automatically adjusts the opening of the electric regulating valve to quickly and accurately stabilize the actual flow rate near the target value. For example, a coordinated mode (main-auxiliary regulation mode) can be implemented using one pipe as the main regulator and another as a coarse or auxiliary regulator, achieving wide-range, high-precision flow control. Specifically: if the target flow rate is less than or equal to 80% of the maximum flow rate of the main regulating pipe, only the main regulating pipe is used; if the target flow rate is greater than 80% of the sum of the maximum flow rate of the main regulating pipe and the maximum flow rate of auxiliary pipe 1, but less than or equal to their sum, both the main regulating pipe and auxiliary pipe 1 are activated; otherwise, the main regulating pipe, auxiliary pipe 1, and auxiliary pipe 2 are activated.

[0037] S3. Stopping Phase: When it is necessary to stop the water intake for a certain period, the controller controls the siphon breaking valve on the corresponding siphon pipe to open, introducing air to break the siphon effect, then closes the corresponding vacuum branch solenoid valve, and stops the vacuum pump. As a preferred embodiment, the present invention may also include the following multi-siphon pipe collaborative control strategy: the main regulating pipe selects a siphon pipe with a suitable diameter and a wide adjustment range as the main regulating channel, responsible for fine adjustment; the auxiliary regulating pipe is automatically activated when the flow demand exceeds the capacity of the main regulating pipe, responsible for coarse or auxiliary adjustment.

[0038] Example 3: Application of water distribution well renovation in a 450,000-ton / day wastewater treatment plant Taking the renovation project of the water distribution well of a 450,000-ton / day wastewater treatment plant as an example, the plant was constructed in three phases (Phase I: 250,000 m³ / d, Phase II: 100,000 m³ / d, Phase III: 100,000 m³ / d). Phase III has advanced technology and low overall unit cost, but because the concrete weir of the Phase III water distribution well has a higher elevation, the designed influent volume cannot reach the designed scale. Now, the system of this invention is used for renovation.

[0039] Modification plan: Install two DN400 siphon pipes in Phase III to increase the water intake of Phase III and reduce the overall plant operating cost.

[0040] Main equipment: Vacuum pump, flow rate 140L / min, vacuum degree -95kPa, power 0.75kW, with matching buffer tank; Electric regulating valve, DN400, intelligent type, 1 unit, stroke time 60s; Two DN25 vacuum pipeline solenoid valves with a response time of less than 0.5s. Siphon breaker valve, DN40, 2 units, response time less than 2s; Two ultrasonic level gauges; Two vacuum pressure gauges, ranging from -0.1 to 0 mPa. PLC, Siemens S7-1500 series.

[0041] System workflow: (1) Start-up phase (formation of siphon) Command reception: The PLC receives the three-phase target flow rate from the central controller. ; Siphon tube selection: The PLC calculates the required number of siphon tubes to be opened based on the target flow rate and the current liquid level difference; Vacuum preparation: Open the solenoid valve of the vacuum branch corresponding to the selected siphon tube, start the vacuum pump, monitor the vacuum level, and proceed to the next step when the set value (e.g., -0.085 MPa) is reached; Siphon formation: After the vacuum is reached, the water enters the siphon tube under atmospheric pressure; Monitor the initial flow rate to confirm that the siphon is established normally; The vacuum pump switches to maintenance mode (intermittent operation).

[0042] (2) Adjustment phase Data collection: Actual traffic flow for three phases is collected every 10 seconds. ; Deviation calculation: ; Valve control: The valve opening adjustment amount is calculated through a PID control algorithm, and a 4-20mA signal is output to the electric regulating valve to adjust the opening. Limiting protection: Valve opening is limited to 0-100%.

[0043] (3) Stopping phase (siphon failure) Open the siphon breaker valve to introduce air; Close the vacuum branch solenoid valve; Stop the vacuum pump.

[0044] Actual results: With large fluctuations in total water inflow, the water inflow of Phase III was stably controlled at 4000-4200 m³ / h (the water inflow fluctuated between 2500-3800 m³ / h before the siphon was added), which is beneficial to the overall equipment and process control of Phase III; the operating cost per ton of water for the whole plant decreased by 3% compared with before the siphon was added.

[0045] This invention is applicable not only to the design of water distribution wells in newly built sewage treatment plants, but also to the renovation and upgrading of water distribution wells in existing sewage treatment plants. It is suitable for sewage treatment plants of various sizes and different process combinations, and has broad application prospects.

[0046] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

[0047] If flowcharts are used in this application, they are used to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these flows, or one or more steps can be removed from these flows.

[0048] The above provides a detailed description of an adjustable water volume control method and system for a wastewater treatment plant distribution well, as provided in this application. The above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A water volume control system for a water distribution well in a sewage treatment plant, characterized in that, include: Multiple siphon pipes are connected in parallel between the water inlet area and the corresponding water outlet area of ​​the water distribution well. The water inlet end of each siphon pipe is located below the liquid level of the water inlet area, and the water outlet end is connected to the corresponding water outlet area. Each siphon pipe is equipped with a regulating valve and a siphon breaking valve. A vacuum supply system, connected to the top of each of the siphon tubes, is used to independently evacuate each of the siphon tubes to form a siphon flow; The detection unit includes at least a flow detection element disposed in each of the water outlet areas or on the downstream pipeline, for outputting the actual flow signal of each of the water outlet areas in real time; The controller has its input terminal connected to the detection unit to receive the actual flow signal and to receive the target flow command for each of the water outlet areas. The output terminal of the controller is respectively connected to the vacuum supply system, each of the regulating valves and each of the siphon breaking valves. The controller is also used to select a number of corresponding siphon tubes according to the target flow command during the startup phase, and control the vacuum supply system to evacuate the selected number of siphon tubes to form a siphon flow; during the adjustment phase, it calculates the flow deviation according to the actual flow signal and the target flow command, and adjusts the opening of the regulating valve on the corresponding siphon tube according to the flow deviation, so that the actual flow approaches the target flow. During the stopping phase, the siphon breaking valve on the corresponding siphon tube is opened to break the siphon, and then the vacuum supply system is controlled to cut off the vacuum supply to the siphon tube.

2. The water volume control system according to claim 1, characterized in that, The vacuum supply system includes: Vacuum shared passage; A vacuum generating device, which is connected to the shared vacuum passage; Multiple vacuum branches, one end of each vacuum branch is connected to the common vacuum passage, and the other end of each vacuum branch is connected to the top of each siphon tube; Each vacuum branch is equipped with an on / off valve to independently control the vacuum on / off of the corresponding siphon tube.

3. The water control system according to claim 2, characterized in that, The vacuum supply system also includes: a vacuum holding device; The vacuum holding device is connected in series between the vacuum generating device and the vacuum common passage.

4. The water volume control system according to claim 3, characterized in that, The vacuum holding device is a vacuum buffer tank, which is used to stabilize the vacuum level of the vacuum supply system.

5. The water volume control system according to claim 2, characterized in that, The vacuum generating device is a vacuum pump, and there are two vacuum pumps, each serving as a backup for the other.

6. The water volume control system according to claim 2, characterized in that, The on / off valve is a solenoid valve, and each solenoid valve is used to independently control the on / off state of the corresponding vacuum branch.

7. The water volume control system according to claim 1, characterized in that, The detection unit further includes: a first level gauge disposed in the water inlet area and a second level gauge disposed in each of the water outlet areas; The controller calculates the current flow rate of each siphon tube based on the difference between the detection values ​​of the first level gauge and the second level gauge; The current flow rate is compared with the measurement value of the flow detection element; The measured value is corrected based on the comparison results, and the corrected measured value is used as the actual flow signal.

8. The water volume control system according to claim 1, characterized in that, The controller employs a PID control algorithm. The PID control algorithm is specifically as follows: calculate the proportional term based on the flow deviation at the current sampling time, calculate the integral term based on the cumulative value of the historical flow deviation at each sampling time, calculate the derivative term based on the change in flow deviation between the current sampling time and the previous sampling time, and use the sum of the proportional term, the integral term, and the derivative term as the valve opening adjustment amount.

9. The water volume control system according to claim 1, characterized in that, The regulating valve is an electric regulating valve, which is used to receive the opening adjustment signal output by the controller and adjust the opening. The flow detection element is an online flow meter, which is used to output the actual flow signal of each of the water outlet areas in real time. The controller is a programmable logic controller.

10. A method for controlling the water volume of a distribution well in a wastewater treatment plant, applied to the water volume control system as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Start-up phase: The controller receives the target flow instructions for each of the water outlet areas, selects a number of corresponding siphon tubes according to the target flow instructions, and controls the vacuum supply system to evacuate the selected number of siphon tubes to form a siphon flow. Adjustment phase: The controller receives the actual flow signals of each of the water outlet areas in real time, calculates the flow deviation based on the actual flow signals and the target flow command, and adjusts the opening of the regulating valve on the corresponding siphon pipe according to the flow deviation to make the actual flow rate approach the target flow rate; Stopping phase: The controller controls the siphon breaking valve on the corresponding siphon tube to open to break the siphon, and then controls the vacuum supply system to cut off the vacuum supply to the siphon tube.

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