PLC control system and control method for gas dissolution oxygenation

Abstract

The application provides a PLC control system and method for gas dissolution oxygenation. The system comprises a host PLC control master station, a plurality of precise regulation and control system PLC sub-stations, a plurality of water quality monitoring system remote sub-stations and an oxygen production system PLC sub-station. The control method comprises the following steps: calculating required oxygenation parameters, system pressure and water inflow, setting water pump operation frequency, using PLC to control water pump and gas flow, realizing precise regulation and control oxygenation, and feedback control through the water quality monitoring system remote sub-station, thereby realizing efficient and accurate oxygenation. Through integrated control, accurate data acquisition, parameter optimization and efficient sub-station control, intelligent and unmanned efficient oxygen-rich water production and accurate oxygenation are realized, and the water quality and ecological environment of the lake are improved.

Description

Technical Field

[0001] This invention relates to the field of water environment treatment technology, and in particular to a PLC control system and control method for dissolved oxygen reoxygenation. Background Technology

[0002] Dissolved oxygenation systems are primarily used for lake water environment management, improving dissolved oxygen levels in the water, creating oxygen-rich and healthy habitats, and restoring biodiversity in rivers and lakes. Currently, some lake reoxygenation devices on the market use PLC control systems; however, ordinary PLC control systems cannot accurately reoxygenate every reoxygenation point within the water body during the lake reoxygenation process, making their limitations in lake reoxygenation quite apparent.

[0003] Because PLC systems typically operate according to preset programs, they struggle to achieve precise control over dynamically changing aquatic environments, such as flow rates and uneven dissolved oxygen concentration distribution. The water quality at each reoxygenation point may vary, and ordinary PLC control systems cannot adjust in real time to these differences, resulting in unsatisfactory reoxygenation effects. Furthermore, the inability of ordinary PLC control systems to precisely control the oxygen supply at each reoxygenation point easily leads to oxygen waste or insufficient supply, thus reducing overall reoxygenation efficiency. In addition, the lack of precise control often results in low dissolved oxygen concentrations in the oxygen-enriched water produced by the system, failing to achieve the expected ecological restoration effect. Due to imprecise control, ordinary PLC control systems may cause oxygen loss or dissipation when injecting oxygen into the water, reducing oxygen utilization. Moreover, the lack of effective monitoring and regulation of oxygen mass transfer efficiency during the reoxygenation process leads to low overall mass transfer efficiency. The modern trend in water environment management is towards intelligent and unmanned systems. Due to the aforementioned limitations, ordinary PLC control systems cannot meet this trend, limiting their application in modern water environment management.

[0004] In summary, current PLC control systems for dissolved oxygen reoxygenation suffer from technical shortcomings, including low reoxygenation efficiency, low dissolved oxygen levels in the produced oxygen-enriched water, low oxygen utilization, low oxygen mass transfer efficiency in the water, and an inability to achieve intelligent and unmanned operation. Therefore, it is necessary to design an improved PLC control system and method for dissolved oxygen reoxygenation to address these technical challenges. Summary of the Invention

[0005] The purpose of this invention is to provide a PLC control system and control method for dissolved oxygen reoxygenation. Through a multi-level communication network and an integrated control system, the oxygen supply and distribution are precisely controlled, enabling continuous monitoring and automatic adjustment of the lake water environment, thereby effectively improving water quality, restoring ecological balance, and reducing operating costs.

[0006] To achieve the above-mentioned objectives, the present invention provides a PLC control system for dissolved oxygenation, which includes a main PLC control station, several precision regulation system PLC substations for controlling the flow rate of oxygen-enriched water, several remote water quality monitoring system substations for collecting water quality parameter data, and an oxygen generation system PLC substation for regulating the preparation of oxygen-enriched water.

[0007] The host PLC control master station is wirelessly connected to the aforementioned substations. By receiving and processing the water quality parameter data transmitted by the remote substation of the water quality monitoring system, it controls the PLC substation of the oxygen production system to regulate the preparation of oxygen-enriched water. It also sends oxygen-enriched water flow parameter adjustment and control signals to the PLC substation of the precision regulation system to achieve precise dissolved oxygenation at each reoxygenation point in the water body.

[0008] As a further improvement of the present invention, the host PLC control master station includes a master station touch screen, a master station switch, a master station data acquisition and electrical control unit, and a data exchange cloud platform;

[0009] The water quality parameters of the remote substation of the water quality monitoring system are transmitted and stored to the data exchange cloud platform, and the data exchange cloud platform further sends the processed data to the host PLC control master station.

[0010] As a further improvement of the present invention, the main station data acquisition and electrical control unit acquires data from pressure sensors, level sensors, and inlet electromagnetic flow meters using analog and Ethernet communication methods; it controls the frequency converter to drive the water pump using Ethernet communication methods, and controls the gas flow quality controller to control the balance of the inlet air volume; furthermore, the main station is controlled by the host PLC to optimize and correct the PID parameters of the gas flow quality controller.

[0011] As a further improvement of the present invention, the precision control system PLC substation includes a substation touch screen, a substation switch, and a substation data acquisition and electrical control unit; the substation data acquisition and electrical control unit acquires data from the effluent electromagnetic flow meter and electric valve using analog and Ethernet communication methods; and controls the opening degree of the electric valve using Ethernet communication methods.

[0012] As a further improvement of the present invention, the remote substation of the water quality monitoring system includes a remote substation gateway and a remote substation data acquisition and electrical control unit;

[0013] The remote substation data acquisition and electrical control unit is wirelessly connected to the water quality sensor to collect various water quality parameter data.

[0014] To achieve the above-mentioned objectives, the present invention also provides a method for controlling dissolved oxygen reoxygenation, which employs the aforementioned PLC control system for dissolved oxygen reoxygenation and includes the following steps:

[0015] S1. Calculate the reoxygenation parameters required for the reoxygenated water body, input the reoxygenation scale calculation formula and the actual measured reoxygenation data into the host PLC control station, and determine the air intake of the host equipment of the reoxygenation system according to the reoxygenation scale.

[0016] S2. Calculate the system pressure required by the main equipment of the reoxygenation system, and input the system pressure calculation formula and the actual measured pressure data into the host PLC control station;

[0017] S3. Based on the system pressure and reoxygenation scale, calculate the influent flow rate required for the main equipment of the reoxygenation system;

[0018] S4. Input the performance parameters of the water pump into the host PLC control station, and determine the range of the water pump operating frequency through the water pump performance parameters, system pressure, and inlet flow rate.

[0019] S5. The main PLC control station controls the frequency converter to drive the water pump to pump the water source to the main equipment of the reoxygenation system. The main PLC control station controls the gas flow quality controller according to the parameter data of the oxygen production system PLC substation, and then adjusts the air intake flow to meet the reoxygenation scale of step S1.

[0020] S6. The water quality monitoring system set within a certain range of the reoxygenation water body points transmits water quality parameter data to the main PLC control station. The oxygen-enriched water generated by the main equipment of the reoxygenation system is sent to the precision control equipment. The PLC substation of the precision control system controls the opening of the electric valve of the precision control equipment to regulate the flow rate of the oxygen-enriched water and deliver the reoxygenated water to the reoxygenation water body points for reoxygenation.

[0021] As a further improvement of the present invention, in step S1, the formula for calculating the required reoxygenation scale of the reoxygenated water is as follows:

[0022]

[0023] M = M1 + M2 + M3

[0024] Where: M is the oxygen demand of the water body, kg; M1 is the oxygen demand for sulfide, kg; M2 is the oxygen demand for sulfate reduction by sulfate-inhibiting bacteria, kg; M3 is the oxygen demand for inhibited biological processes, kg; B0 is the five-day biological oxygen demand, mg / L; C0 is the raw water sulfide concentration, mg / L; V 有效 λ is the effective volume of the water body, in m3; λ is an empirical parameter, dimensionless, 1.0-1.5; D0 is the dissolved oxygen limit, in mg / L.

[0025]

[0026] Where: Q is the reoxygenation scale, kg / h; t is the reoxygenation time, h; η is the dissolved oxygen efficiency, dimensionless, 90%-95%.

[0027] As a further improvement of the present invention, in step S2, according to Heinz's law, under isothermal and isobaric conditions, the solubility of a certain volatile solute in a solution is directly proportional to the equilibrium pressure of the solute on the liquid surface, and the calculation formula is as follows:

[0028] Pg=H*x

[0029] Where H is Henry's constant, Pa; x is the mole fraction solubility of the gas, dimensionless; Pg is the partial pressure of the gas, Pa; Henry's constant is the oxygen constant, with the temperature taken as 25℃; and O2 dissolved oxygen is taken as 70-90 mg / L.

[0030] The system pressure value is used as the basis for setting the operating frequency of the water pump, and the calculation formula is as follows:

[0031]

[0032] Where: P is the system pressure, Pa; Pg is the partial pressure of the gas, Pa; η is the dissolved oxygen efficiency, 90%-95%; k is the effluent pressure loss coefficient, dimensionless 1.1-1.3; γ is the gas partial pressure compensation coefficient under high dissolved oxygen conditions, dimensionless 0.7-1.

[0033] As a further improvement of the present invention, in step S4, the host PLC control master station and the frequency converter use Profint communication;

[0034] In step S6, the water quality parameters include, but are not limited to, one or more of dissolved oxygen, chemical oxygen demand, and ammonia nitrogen; the water quality monitoring system is set up in an area with a radius of 20m centered on the reoxygenated water body point.

[0035] As a further improvement of the present invention, in step S6, the method for controlling the reoxygenation of the reoxygenated water body points is as follows: the dissolved oxygen value is preset according to the process, the host PLC controls the main station to calculate the range of the target value to control the precision control system PLC substation, controls the opening of the electric valve to adjust the flow rate of the oxygen-enriched water, and reoxygenates each reoxygenated water body point in the water body.

[0036] The processes include: black and odorous water body treatment process, river and lake ecological restoration process, pipeline / box culvert / storage tank deodorization process, ditch sludge remote degradation process, and customized process; different factory operation parameters are set according to different process selections.

[0037] The beneficial effects of this invention are:

[0038] 1. The PLC control system for dissolved oxygen reoxygenation provided by this invention collects data from various sensors and integrates process parameters and model parameters input from the main station touchscreen. The host PLC controls the main station to precisely drive the operation of each component and communicates with the oxygen generator PLC substation via Ethernet to control oxygen production. This integrated control system can effectively and stably produce ultra-nano oxygen-enriched water with the target dissolved oxygen concentration, ensuring that the dissolved oxygen content of the reoxygenated water achieves the expected ecological restoration effect.

[0039] 2. The PLC control system for dissolved reoxygenation provided by this invention adopts industrial Ethernet and 5G communication technologies. The main PLC control station is equipped with a touch screen, switch, 5G gateway, data acquisition and electrical control module, and data exchange cloud platform. The main station's data acquisition and electrical control department can accurately acquire data from various sensors through analog and Ethernet communication. The comprehensive application of these technologies and integrated design enables the system to efficiently and accurately reoxygenate each reoxygenation point in the water body, realizing the intelligent and unmanned operation of the system, and greatly improving the reoxygenation efficiency and the system's automation level.

[0040] 3. The dissolved reoxygenation control method provided by the present invention accurately calculates reoxygenation parameters, system pressure and influent flow rate, uses PLC to control water pump and gas flow rate, precisely regulates reoxygenation, and uses a remote substation of water quality monitoring system for feedback regulation, thereby achieving efficient and precise reoxygenation and effectively improving the lake water environment. Attached Figure Description

[0041] Figure 1 A flowchart illustrating the control method for dissolved oxygen reoxygenation provided by the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0044] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0045] This invention provides a PLC control system for dissolved oxygenation, including a main PLC control station, several precision regulation PLC substations for controlling the flow rate of oxygen-enriched water, several remote water quality monitoring substations for collecting water quality parameter data, and an oxygen generation system PLC substation for regulating the preparation of oxygen-enriched water.

[0046] The host PLC control master station is wirelessly connected to the aforementioned substations. By receiving and processing the water quality parameter data transmitted by the remote substation of the water quality monitoring system, it controls the PLC substation of the oxygen production system to regulate the preparation of oxygen-enriched water. It also sends oxygen-enriched water flow parameter adjustment and control signals to the PLC substation of the precision regulation system to achieve precise dissolved oxygenation at each reoxygenation point in the water body.

[0047] The dissolved oxygenation device includes a water pump, a frequency converter for driving the water pump, a gas flow and quality controller, a main unit for the oxygenation system, precision control equipment, and a water quality monitoring system.

[0048] The host PLC control station is electrically connected to the frequency converter and is used to regulate the frequency converter.

[0049] The host PLC control station is electrically connected to the gas flow and quality controller and is used to regulate the gas flow and quality controller.

[0050] The host PLC control station is electrically connected to the main equipment of the reoxygenation system and is used to regulate the main equipment of the reoxygenation system.

[0051] The PLC substation of the precision control system is electrically connected to the precision control equipment and is used to control the flow rate of oxygen-enriched water.

[0052] The remote substation of the water quality monitoring system is electrically connected to the water quality monitoring system and is used to collect and transmit water quality parameter data.

[0053] The oxygen generation system PLC substation is electrically connected to the main equipment of the reoxygenation system and is used to regulate the preparation of oxygen-enriched water.

[0054] In some specific embodiments, the PLC control system for dissolved oxygen reoxygenation includes a host PLC control master station, a first precision control system PLC substation and a second precision control system PLC substation respectively connected to the host PLC control master station via industrial Ethernet, a first water quality monitoring system remote substation, a second water quality monitoring system remote substation, a third water quality monitoring system remote substation and a fourth water quality monitoring system remote substation respectively connected to the host PLC control master station via 5G, and an oxygen generation system PLC substation connected to the host PLC control master station via Ethernet.

[0055] The host PLC control master station includes a master station touch screen, a master station switch for providing network connectivity between various components, a master station 5G gateway for providing wireless connectivity to external networks, a master station data acquisition and electrical control unit, and a data exchange cloud platform for storing data and performing data analysis.

[0056] The main station data acquisition and electrical control unit uses analog and Ethernet communication to acquire data from pressure sensors, level sensors, and inlet electromagnetic flow meters; it uses Ethernet communication to control frequency converters to drive water pumps; it uses Ethernet communication to control gas flow quality controllers to balance the inlet airflow; and it uses the host PLC to control the main station to optimize and correct the PID parameters of the gas flow quality controllers.

[0057] Both the first and second precision control system PLC substations include a substation touchscreen, a substation switch for providing network connectivity between various components within the substation, and a substation data acquisition and electrical control unit. The substation data acquisition and electrical control unit acquires data from the effluent electromagnetic flow meter and electric valves using analog and Ethernet communication methods, and controls the opening degree of the electric valves using Ethernet communication.

[0058] The first, second, third, and fourth remote substations of the water quality monitoring system each include a remote substation 5G gateway and a remote substation data acquisition and electrical control unit; the remote substation data acquisition and electrical control unit all use 485 communication to communicate with the water quality sensor to collect water quality data.

[0059] Example 1

[0060] Based on the above-mentioned PLC control system for dissolved oxygen reoxygenation, Embodiment 1 of the present invention provides a control method for dissolved oxygen reoxygenation, which mainly includes the following steps:

[0061] S1. Calculate the reoxygenation parameters required for the reoxygenated water body, and write the reoxygenation scale calculation formula into the host PLC control station and the main station touch screen program. Fill the actual measured reoxygenation data into the parameter areas of the main station touch screen, and use a retention memory in the host PLC control station program. The air intake of the main equipment of the reoxygenation system can be determined according to the reoxygenation scale.

[0062] Formula for calculating the required reoxygenation scale of the water body to be reoxygenated:

[0063]

[0064] M = M1 + M2 + M3

[0065] Where: M is the oxygen demand of water, in kg;

[0066] M1 is the sulfide oxygen demand, in kg;

[0067] M2 represents the oxygen demand (kg) for sulfate reduction by sulfate-reducing bacteria;

[0068] M3 represents the inhibition of biological oxygen demand, expressed in kg.

[0069] B0 is the five-day biological oxygen demand, in mg / L;

[0070] C0 represents the concentration of sulfides in the raw water, in mg / L;

[0071] V 有效 The effective volume of the water body is expressed in m³.

[0072] λ is an empirical parameter, dimensionless, ranging from 1.0 to 1.5.

[0073] D0 is the dissolved oxygen limit, mg / L;

[0074]

[0075] Where: Q is the reoxygenation capacity, kg / h;

[0076] t represents the reoxygenation time, in hours (h).

[0077] η is the dissolved oxygen efficiency, dimensionless, 90%-95%;

[0078] S2. Calculate the system pressure required by the main equipment of the reoxygenation system. According to Heinz's law, under isothermal and isobaric conditions, the solubility of a certain volatile solute (usually a gas) in a solution is directly proportional to the equilibrium pressure of that solute on the liquid surface. The calculation formula is as follows:

[0079] Pg=H*x

[0080] Where H is Henry's constant, Pa;

[0081] x is the mole fraction solubility of the gas, which is dimensionless;

[0082] Pg is the partial pressure of the gas, in Pa;

[0083] The Henry constant is the oxygen constant, with a temperature of 25℃ and dissolved oxygen (O2) of 70-90 mg / L.

[0084] The above calculation formula is written into the host PLC control master station and the master station touch screen program. The actual measured pressure data is filled into the parameter areas of the touch screen, and a retention memory is used in the host PLC control master station program. The system pressure value can be used as the basis for setting the water pump operating frequency.

[0085]

[0086] Where: P is the system pressure, Pa;

[0087] Pg is the partial pressure of the gas, in Pa;

[0088] η represents dissolved oxygen efficiency, 90%-95%;

[0089] k is the outlet pressure loss coefficient; dimensionless, 1.1-1.3;

[0090] γ is the partial pressure compensation coefficient for gas under high dissolved oxygen conditions; dimensionless, 0.7-1.

[0091] S3. Calculate the inlet flow rate required for the main equipment of the reoxygenation system. Based on the solubility of gas mole fraction x in S2 and the reoxygenation scale calculated in step S1, the required inlet flow rate can be determined as the basis for setting the pump operating frequency.

[0092] S4. Based on the relevant parameters of the water pump, the data values ​​of the water pump performance curve are written into the main PLC control station and the main station touch screen program. The parameters of the water pump are written into the frequency converter. The range of the water pump operating frequency is determined by inputting the water pump performance parameters, the required inlet flow rate of the main equipment of the reoxygenation system, and the required system pressure of the main equipment of the reoxygenation system into the main PLC control station. The main PLC control station and the frequency converter controlling the water pump communicate using Profint.

[0093] S5. After the relevant parameters are input on the main station touch screen, the host PLC controls the inverter to drive the water pump to pump water to the host equipment. The host PLC controls the communication between the host PLC and the oxygen generator PLC substation to transmit the oxygen pressure and purity of the oxygen generator PLC substation and the operating parameters of the oxygen generator to the host PLC control station. The host PLC control station controls the gas flow quality controller through Ethernet communication to control the air intake flow to meet the reoxygenation scale in step S1.

[0094] S6. The oxygen-enriched water produced by the main equipment of the reoxygenation system is directed to the precision control equipment. This equipment then delivers the reoxygenated water to designated reoxygenation points. A water quality monitoring system is installed within a certain range of these points. The main PLC control station transmits water quality parameters from remote substations of each monitoring system. The precision control system's PLC substations reoxygenate each reoxygenation point within the water body. These water quality parameters include dissolved oxygen (DO), chemical oxygen demand (COD), and ammonia nitrogen. The water quality monitoring system is located within a 20m radius centered on the reoxygenated water point.

[0095] The specific method for reoxygenating the reoxygenation points is as follows: the dissolved oxygen (DO) value is preset according to the process, the main PLC control station calculates the range of the target value to control the precision control equipment, and the PLC substation of the precision control system controls the opening of the electric valve to adjust the flow rate of the oxygen-enriched water, which can accurately reoxygenate each reoxygenation point in the water body.

[0096] The PLC control system for dissolved oxygenation provided by this invention also includes a human-machine interface and a process scheme, which are described in detail below:

[0097] The human-machine interface is set on the host PLC control master station:

[0098] System login: On the login page of the human-machine interface, enter the preset administrator account and password to obtain administrator operation permissions. You can perform the following on the equipment: manual operation, automatic operation, parameter viewing, parameter modification, operation data viewing, operation fault history viewing, operation process viewing, substation system operation and settings, and operation data download.

[0099] Permission settings allow you to set different operation permissions based on actual needs by setting different account passwords. Administrator permissions allow you to perform all operations, engineer permissions allow you to perform operations, modify parameters, and view data, and operator permissions allow you to perform operations and view data.

[0100] The main process screen consists of a high-efficiency oxygen generation system, a high and low pressure water inlet system, an ultra-nano aerosol equipment system, a precision control system, a water quality monitoring system, and an energy consumption system.

[0101] The main process screen can monitor the operating status of all equipment, including whether the equipment is in "local", "remote control", "running", "stopped", "faulty", "fully open", "fully closed" or "communication status". It can monitor the operating parameters of each system, including but not limited to total inlet water flow, inlet water pressure, operating current of each water pump, operating frequency of each water pump, filter clogging status, main unit operating pressure, air inlet flow, air inlet pressure, air source pressure, cumulative inlet water flow, cumulative air inlet mass, air inlet mass number, equivalent dissolved oxygen in the effluent, effluent flow of each system, valve opening, oxygen generation system and other related operating parameters, water quality monitoring system data, and the operating status of other auxiliary systems.

[0102] The equipment can be controlled manually. Each water pump in the system can be set to manual operation. When operating manually, it can be started, stopped, and its frequency can be set individually, and its associated status and operating parameters can be displayed.

[0103] Each electric valve in the system can be set to manual operation. When manually operated, it can be opened, closed, and its opening degree can be set individually, and its associated status and operating parameters can be displayed.

[0104] The precision control system and oxygen generation system can be set to "local" or "remote control". When controlled locally, the system is operated by the human-machine interface configured in the substation system; when controlled remotely, the system is operated by the human-machine interface of the main station system.

[0105] The system features automated operation. The human-machine interface allows users to select automatic operation, and the main system runs automatically based on the system's process and pre-set operating parameters, coordinating the operation of each substation. This setup enables automated control of the entire reoxygenation system. The main process screen also includes alarm and fault handling modules, displaying real-time equipment operating status and fault information for timely intervention. The system also has data recording and analysis functions, storing and analyzing operational data to support the optimization of process parameters and improve system efficiency. Through the human-machine interface, operators can easily monitor and control the entire reoxygenation system, ensuring stable and efficient operation.

[0106] Process plan:

[0107] For process application selection, depending on the specific situation, the following process applications can be selected on the human-machine interface: black and odorous water body treatment process, river and lake ecological restoration process, pipeline / box culvert / storage tank deodorization process, remote degradation process of sludge in drainage ditches, and custom parameter process; the system will set preset factory operating parameters according to different process application selections, and the relevant parameters can also be optimized and modified.

[0108] Operating mode selection: Depending on the specific situation, the following operating modes can be selected on the human-machine interface: Time control mode, which allows setting multiple sets of equipment start and stop times, such as turning on during the day and turning off at night, turning on in the morning and turning off at noon and turning on at midnight, etc. When setting the time control mode, it has higher priority than other control modes.

[0109] 1. Flow mode: The flow mode can be set in combination with the time control mode. From 9:00 AM to 12:00 PM, the main equipment of the reoxygenation system uses 10 kg / h of oxygen for reoxygenation, and from 12:00 PM to 5:00 PM, the equipment uses 5 kg / h of oxygen for reoxygenation.

[0110] 2. Concentration mode: The concentration mode can be set in conjunction with the time control mode. In winter, the equipment operates with an equivalent dissolved oxygen content of 95 mg / L for reoxygenated water, and in summer, the equipment operates with an equivalent dissolved oxygen content of 70 mg / L for reoxygenated water.

[0111] 3. Dissolved oxygen mode: Based on the dissolved oxygen value feedback device, the corresponding dissolved oxygen target value of the water body can be set for the main equipment of the reoxygenation system. If the dissolved oxygen target value is set to 12mg / L, the system will automatically adjust the flow mode and concentration mode of the main equipment of the reoxygenation system in real time according to the difference between the actual value and the target value to make the water body close to 12mg / L.

[0112] 4. Precise Control Mode: The system is equipped with a substation-based flow distribution and dissolved oxygen precise control system and a remote station water quality monitoring system. Raw water is transformed into super-oxygenated water through the ultra-nano system and enters the flow distribution and dissolved oxygen precise control system. Multiple streams are then distributed to corresponding areas of the lake. Water quality monitoring float stations are configured in each area, feeding back data to the flow distribution and dissolved oxygen precise control system. The system adjusts the flow rate of super-oxygenated water in each area based on relevant parameters. Areas meeting water quality requirements have reduced flow rates, while areas not meeting requirements have increased flow rates. Different dissolved oxygen target values ​​can be set for different points. The equipment has 8 reoxygenation points and 8 sets of water quality monitoring systems. The target value for each reoxygenation point is set to 12 mg / L. After the equipment has been running for a period of time, some points may have dissolved oxygen levels exceeding 12 mg / L, while others may be lower. The equipment automatically adjusts the reoxygenation capacity (flow rate) of each point. The system improves water quality more efficiently while maintaining flow balance in each area, and ensures that changes in flow rates in different areas do not affect the system balance of the ultra-nano system.

[0113] 5. Custom mode: Customize a reasonable operation mode according to the specific project. When treating the discharge culvert, reoxygenate different water areas on sunny and rainy days. At this time, it is necessary to set the sunny and rainy day mode. The precise control system will switch the system to different reoxygenation points on sunny and rainy days.

[0114] Parameter settings: The parameters of each system can be set and viewed in the human-machine interface, including general parameters and process parameters.

[0115] Inlet water flow rate includes: range setting, upper limit setting, lower limit setting, delayed sampling, pump blockage flow rate, filter blockage flow rate, and fault shutdown flow rate.

[0116] Pump settings: upper limit operating frequency, lower limit operating frequency, upper limit current, etc.

[0117] Inlet water pressure settings: range setting, lower pressure limit, upper pressure limit, fault shutdown pressure, filter clogging pressure, etc.

[0118] Inlet pressure: range setting, upper pressure limit, lower pressure limit, fault shutdown pressure, filter blockage pressure, etc.

[0119] Intake flow: range setting, flow setting, daily cumulative flow, fault shutdown setting, etc.

[0120] Main unit pressure: range setting, pressure range setting, fault shutdown pressure, unloading pressure, etc.

[0121] Oxygen generation system: Substation parameter settings (including purity, pressure, flow rate, etc.).

[0122] Precision control system: Substation parameter settings (including flow, opening degree, quantity, etc.).

[0123] Water quality monitoring system: main station display and calculation range settings, upper and lower limit settings, and fault value settings.

[0124] Operating mode parameter settings: Time control mode (including time settings, etc.), Flow mode (including time control settings, flow settings, etc.), Concentration mode (including time control settings, equivalent dissolved oxygen settings), Dissolved oxygen mode (including dissolved oxygen target settings, PID-like related parameter settings), Precision control mode (including point settings, target value settings, and precision adjustment substation settings).

[0125] Other process calculation related parameter settings.

[0126] Fault alarms: The system can automatically trigger fault alarms and, based on the set values, can issue warnings and shut down the system.

[0127] This includes: pressure alarm, flow alarm, blockage alarm, frequency converter fault alarm (water pump), communication fault alarm, valve fault alarm, system fault alarm, water quality parameter alarm, oxygen production system alarm, and control system alarm.

[0128] Alarms can be manually cleared or automatically deactivated, and alarms are recorded in detail in an alarm table.

[0129] Alarms can be sent to different roles via a 4G gateway, with notifications sent to each role (including WeChat push, SMS push, voice call push, etc.).

[0130] The data reports include records of relevant parameters during system operation, process parameters, water quality parameters, and trend charts. Key data includes: daily influent flow statistics, daily electricity consumption statistics, influent pressure and flow trend charts, daily air intake flow statistics, air intake pressure and flow trend charts, start-up and shutdown records, main unit pressure trend charts and historical statistics, system reoxygenation capacity, effluent equivalent dissolved oxygen statistics, statistics on precise control system switching actions, flow statistics at each reoxygenation point, operation records, etc. Data reports can be viewed and downloaded for analysis in real time.

[0131] This configuration allows operators to easily select process applications, operating modes, parameter settings, and fault alarms, ensuring the system operates stably according to preset process flows and parameters. The data reporting function provides detailed data records and trend analysis during system operation, helping operators understand the system's operating status in a timely manner and adjust and optimize operating parameters. The alarm push function of the 4G gateway enables real-time notification of critical information, ensuring a rapid response in case of problems. This configuration ensures the efficient and stable operation of the reoxygenation system, achieving the expected water environment treatment results.

[0132] In summary, this invention provides a PLC control system and method for dissolved reoxygenation. The system includes a main PLC control station, several precision regulation system PLC substations, several water quality monitoring system remote substations, and an oxygen production system PLC substation. The control method includes the following steps: calculating the required reoxygenation parameters, system pressure, and influent flow rate; setting the water pump operating frequency; using the PLC to control the water pump and gas flow rate to achieve precise regulation of reoxygenation; and using the water quality monitoring system remote substations for feedback regulation, thereby achieving efficient and precise reoxygenation. Through integrated control, precise data acquisition, parameter optimization, and efficient substation regulation, intelligent and unmanned high-efficiency oxygen-enriched water production and precise reoxygenation are achieved, improving lake water quality and the ecological environment.

[0133] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A PLC control system for dissolved oxygen reoxygenation, characterized in that: It includes a main PLC control station, several precision regulation system PLC substations for controlling the flow of oxygen-enriched water, several remote water quality monitoring system substations for collecting water quality parameter data, and an oxygen generation system PLC substation for regulating the preparation of oxygen-enriched water. The host PLC control master station is electrically connected to the aforementioned substations. By receiving and processing the water quality parameter data transmitted by the remote substation of the water quality monitoring system, it controls the PLC substation of the oxygen production system to regulate the preparation of oxygen-enriched water. It also sends oxygen-enriched water flow parameter adjustment and control signals to the PLC substation of the precision regulation system to achieve precise dissolved oxygenation at each reoxygenation point in the water body. The host PLC control station includes a host touch screen, a host switch, a host data acquisition and electrical control unit, and a data exchange cloud platform; The water quality parameters of the remote substation of the water quality monitoring system are transmitted and stored to the data exchange cloud platform, and the data exchange cloud platform further sends the processed data to the host PLC control master station. The precision control system PLC substation includes a substation touch screen, a substation switch, and a substation data acquisition and electrical control unit. The substation data acquisition and electrical control unit acquires data from the effluent electromagnetic flow meter and electric valves using analog and Ethernet communication methods. It controls the opening degree of the electric valves using Ethernet communication.

2. The PLC control system for dissolved oxygen reoxygenation according to claim 1, characterized in that: The main station data acquisition and electrical control unit acquires data from pressure sensors, level sensors, and inlet electromagnetic flow meters using analog and Ethernet communication methods; it controls the frequency converter to drive the water pump using Ethernet communication and controls the gas flow quality controller to balance the inlet airflow; furthermore, the main station is controlled by the host PLC to optimize and correct the PID parameters of the gas flow quality controller.

3. The PLC control system for dissolved oxygen reoxygenation according to claim 1, characterized in that: The water quality monitoring system remote substation includes a remote substation gateway and a remote substation data acquisition and electrical control unit; The remote substation data acquisition and electrical control unit is wirelessly connected to the water quality sensor to collect various water quality parameter data.

4. A method for controlling dissolved oxygen reoxygenation, characterized in that: Controlling the dissolved oxygen reoxygenation system using any one of claims 1 to 3, comprising the following steps: S1. Calculate the reoxygenation parameters required for the reoxygenated water body, input the reoxygenation scale calculation formula and the actual measured reoxygenation data into the host PLC control station, and determine the air intake of the host equipment of the reoxygenation system according to the reoxygenation scale. S2. Calculate the system pressure required by the main equipment of the reoxygenation system, and input the system pressure calculation formula and the actual measured pressure data into the host PLC control station; S3. Based on the system pressure data and the reoxygenation scale, calculate the influent flow rate required for the main equipment of the reoxygenation system; S4. Input the performance parameters of the water pump into the host PLC control station, and determine the range of the water pump operating frequency through the water pump performance parameters, system pressure, and inlet flow rate. S5. The main PLC control station controls the frequency converter to drive the water pump to pump the water source to the main equipment of the reoxygenation system. The main PLC control station controls the gas flow quality controller according to the parameter data of the oxygen production system PLC substation, thereby adjusting the air intake flow to meet the reoxygenation scale of step S1. S6. The remote substation of the water quality monitoring system, located within a certain range of the reoxygenation water body, transmits water quality parameter data to the main PLC control station. The oxygen-enriched water generated by the main equipment of the reoxygenation system is directed to the precision control equipment. The PLC substation of the precision control system controls the opening of the electric valve of the precision control equipment to regulate the flow rate of the oxygen-enriched water, and delivers the reoxygenated water to the reoxygenation water body for reoxygenation.

5. The method for controlling dissolved oxygen reoxygenation according to claim 4, characterized in that: In step S1, the formula for calculating the required reoxygenation scale of the reoxygenated water is: Where: M is the oxygen demand of water, in kg; M 1 represents the oxygen demand for sulfides, in kg; M 2. The oxygen demand for sulfate reduction by sulfate-reducing bacteria, in kg; M 3 is used to suppress biological oxygen demand, in kg; B 0 represents the five-day biological oxygen demand, in mg / L; C 0 represents the concentration of sulfides in the raw water, in mg / L; V 有效 λ is the effective volume of the water body, in m3; λ is an empirical parameter, dimensionless, 1.0-1.5; D 0 represents the dissolved oxygen limit, in mg / L; Where: Q is the reoxygenation capacity, kg / h; t Reoxygenation time, in hours (h). η The dissolved oxygen efficiency is dimensionless and ranges from 90% to 95%.

6. The method for controlling dissolved oxygen reoxygenation according to claim 4, characterized in that: In step S2, according to Heinz's law, under isothermal and isobaric conditions, the solubility of a certain volatile solute in a solution is directly proportional to the equilibrium pressure of that solute on the liquid surface. The calculation formula is as follows: in, H Here is Henry's constant, Pa; x , where is the mole fraction solubility of the gas, dimensionless; Pg Here, is the partial pressure of the gas, Pa; Henry's constant is the oxygen constant, the temperature is taken as 25℃, and the dissolved oxygen in O2 is taken as 70-90 mg / L; The system pressure value is used as the basis for setting the water pump operating frequency, and the calculation formula is as follows: Where: P is the system pressure, Pa; Pg Pa represents the partial pressure of a gas. η Dissolved oxygen efficiency is 90%-95%; k The pressure loss coefficient is dimensionless and ranges from 1.1 to 1.

3. γ The partial pressure compensation coefficient for gas under high dissolved oxygen conditions is dimensionless and is 0.7-1.

7. The method for controlling dissolved oxygen reoxygenation according to claim 4, characterized in that: In step S4, the host PLC control master station communicates with the frequency converter using Profint. In step S6, the water quality parameters include, but are not limited to, one or more of dissolved oxygen, chemical oxygen demand, and ammonia nitrogen; the water quality monitoring system is set up in an area with a radius of 20m centered on the reoxygenated water body point.

8. The method for controlling dissolved oxygen reoxygenation according to claim 4, characterized in that: In step S6, the method for controlling the reoxygenation of the reoxygenated water points is as follows: the dissolved oxygen value is preset according to the process, the main PLC control station calculates the range of the target value to control the PLC substation of the precision control system, controls the opening of the electric valve to adjust the flow rate of the oxygen-enriched water, and reoxygenates each reoxygenated water point in the water body. The processes include: black and odorous water body treatment process, river and lake ecological restoration process, pipeline / box culvert / storage tank deodorization process, ditch sludge remote degradation process, and customized process. Different factory operating parameters are set depending on the selected process.

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