One-to-one pressure dosing method and system for sewage treatment

Abstract

The invention relates to the technical field of sewage treatment, in particular to a one-to-one pressure dosing method and system for sewage treatment. According to the method, the Bernoulli equation principle in fluid mechanics is utilized, it is found that the square of a pressure value and the square of a flow value have a direct proportion relation, under a certain working condition, firstly, a pressure-flow corresponding relational expression is established, after a target dosing flow value is obtained, the target dosing flow value is substituted into the preset pressure-flow corresponding relational expression, and the pressure value needed by a dosing tank is calculated; the actual flow value is obtained through the liquid level change value, and the actual flow value is compared with the target dosing flow value for calibration; the defect that a traditional flowmeter is prone to being damaged when used is overcome, the stable and reliable pressure sensor and the liquid level sensor are adopted, accurate metering is achieved through an intelligent algorithm, cost is lower, and reliability is higher.

Description

Technical Field

[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a one-to-one pressure dosing method and system for sewage treatment. Background Art

[0002] Sewage treatment is an important field of environmental protection. At present, centralized treatment is mainly carried out in sewage treatment plants in China. Various types of chemicals need to be added during the sewage treatment process, including acid-base chemicals, redox chemicals, flocculation chemicals in the physical and chemical treatment units during the sewage treatment process, as well as carbon source supplementation and alkalinity supplementation in the biochemical treatment unit. The types and dosages of chemicals required for different types of wastewater are different.

[0003] Currently, electromagnetic flowmeters or rotor flowmeters are generally used in combination with dosing pumps for chemical dosing control in sewage treatment. Due to the diverse properties of chemicals, such as PAM being viscous, lime milk being prone to scaling, and acids and bases being corrosive, these properties have a greater impact on the accuracy and service life of metering equipment.

[0004] Existing flowmeters are easily affected by chemical corrosion and scaling during use, resulting in a gradual decrease in metering accuracy; some chemicals will stain or block the flowmeter, causing it to lose its metering function; in addition, the failure of the flowmeter often needs to be dealt with after an abnormality is detected, lacking real-time monitoring and automatic calibration capabilities, and this situation needs to be further improved. Summary of the Invention

[0005] In order to solve the problems that existing flowmeters are easily affected by chemical corrosion and scaling during use, resulting in a gradual decrease in metering accuracy, and the failure of the flowmeter often needs to be dealt with after an abnormality is detected, lacking real-time monitoring and automatic calibration capabilities, the present application provides a one-to-one pressure dosing method and system for sewage treatment, and adopts the following technical solutions: In the first aspect, the present application provides a one-to-one pressure dosing method for sewage treatment, which is characterized by including the following steps: Obtain the target dosing flow value, substitute the target dosing flow value into a preset pressure-flow corresponding relationship formula, and calculate the required pressure value of the dosing tank. Among them, the pressure value in the pressure-flow corresponding relationship formula is proportional to the square of the flow value; Measure the liquid level change value through a liquid level sensor to obtain the measured flow value; Compare the target dosing flow value and the measured flow value to determine the flow error rate; When the flow error rate exceeds the preset range, adjust the pressure value of the dosing tank for calibration until the flow error rate is within the preset range.

[0006] By adopting the above technical solution, to solve the problem that the metering equipment of the dosing system in sewage treatment is vulnerable to corrosion and scaling. For example, when adding lime milk, even if a corrosion-resistant electromagnetic flowmeter is used, scaling will occur after a period of use, resulting in a decrease in metering accuracy and high replacement and maintenance costs; when adding sodium sulfide, the rotor flowmeter will be blackened and unable to read. This application utilizes the Bernoulli equation principle in fluid mechanics and discovers that there is a proportional relationship between the pressure value and the square of the flow value. First, obtain the target dosing flow value, substitute the target dosing flow value into the preset pressure-flow corresponding relationship formula, calculate the required pressure value of the dosing tank, and then use the liquid level change value to obtain the actual flow value, and compare and calibrate the actual flow value with the target dosing flow value; avoiding the disadvantage that the flowmeter is easily damaged when using traditional flowmeters, adopting stable and reliable pressure sensors and liquid level sensors, and achieving accurate metering through intelligent algorithms, with lower costs and higher reliability.

[0007] Optionally, the pressure-flow corresponding relationship formula is obtained through calibration, and specifically includes the following steps: Select multiple pressure values, and the pressure values are set from low to high within the allowable working pressure range; Calculate the corresponding actual average flow value under each of the above pressure values through the liquid level change of the dosing tank within a preset time period; Fit multiple set pressure values and the corresponding measured average flow values with the relationship formula P = MQ² + N to determine the values of the fitting coefficients M and N, where P is the pressure value of the dosing tank and Q is the dosing flow value; Judge whether the fitting correlation coefficient exceeds the correlation coefficient of the preset fitting formula. When the fitting correlation coefficient exceeds the correlation coefficient of the preset fitting formula, complete the calibration of the pressure-flow corresponding relationship formula.

[0008] The traditional method is only applicable to one working condition. When the type of reagent changes, or the flowmeter or pipeline is scaled, the measurement accuracy will be greatly reduced; for example, in a certain sewage treatment plant, when adding lime, due to the strong scaling property of the reagent, the dosing flow deviation can reach more than 30%. This application first selects multiple pressure values within the working pressure range, obtains the actual flow through accurate measurement of the liquid level change under each pressure value, and then uses the mathematical model P = MQ² + N for data fitting, and introduces the fitting correlation coefficient as the judgment basis for the calibration quality; establishing a general pressure-flow relationship through mathematical modeling and statistical methods, not only improving the dosing accuracy, but also being able to adapt to the working condition changes under different viscosities and temperature conditions.

[0009] Optionally, the pressure-flow corresponding relationship formula is obtained through calibration, and further includes the following steps: Judge whether the dosing tank reaches the low liquid level through liquid level monitoring; When the dosing tank reaches the low liquid level, close the dosing valve, pause the calibration, and open the inlet valve to add medicine to the high liquid level; After the medicine addition reaches the high liquid level, close the medicine inlet valve and continue to perform the calibration. When the fitting correlation coefficient does not exceed the correlation coefficient of the preset fitting formula, re - execute the calibration step.

[0010] By adopting the above - mentioned technical solution, the continuity and accuracy of the calibration process are ensured, and the problem that traditional calibration methods often require manual judgment and manual liquid replenishment when the liquid medicine is insufficient, which is likely to cause calibration interruption or data incoherence, is improved. The system of this application continuously monitors the liquid level change. When the liquid level drops to the preset low value, the medicine addition valve is automatically closed and the medicine inlet valve is opened for liquid replenishment. After the liquid level is restored, the calibration process continues seamlessly. At the same time, the fitting correlation coefficient is introduced as an evaluation index for the calibration quality to ensure obtaining a high - precision pressure - flow corresponding relationship. It not only avoids the errors and interruptions brought by manual intervention, but also realizes the high - efficiency, precision and reliability of the calibration process through intelligent control and data quality evaluation.

[0011] Optionally, when the flow error rate exceeds the preset range, adjust the pressure value of the medicine addition tank for calibration, which specifically includes the following steps: When the absolute value of the flow error rate exceeds the first preset threshold and is less than the second preset threshold, automatically adjust the output pressure value according to the current output pressure and the flow error rate. Output according to the adjusted pressure value through the proportional valve. When the absolute value of the flow error rate after calibration is less than the first preset threshold, stop the automatic calibration. When the absolute value of the flow error rate still cannot be less than the first preset threshold after exceeding the preset calibration times, and the tank pressure exceeds the preset safe working pressure value, stop the automatic calibration and trigger an alarm prompt to re - calibrate.

[0012] By adopting the above - mentioned technical solution, to solve the problem of automatic correction of flow deviation during the operation of the medicine addition system, traditional methods often adopt simple proportional regulation or fixed - step regulation, lacking a refined control strategy. This application first determines whether the flow error rate falls within the preset interval. When the error exceeds the limit, the optimal pressure value is automatically calculated according to the current pressure and the error rate, and is precisely executed through the proportional valve. At the same time, the upper limit of the calibration times and the pressure over - limit protection are set, and an alarm prompt is given in time to re - calibrate when the normal state cannot be restored through automatic calibration. It not only realizes the automatic maintenance of the medicine addition accuracy, but also avoids the waste of medicine caused by calibration failure by introducing a safety protection mechanism, reflecting the unity of intelligence and safety.

[0013] Optionally, automatically adjusting the output pressure value according to the current output pressure and the flow error rate specifically includes the following steps: When the flow error rate is negative, the adjusted pressure value is equal to the current pressure value multiplied by (1 + the absolute value of the flow error rate). When the flow error rate is positive, the adjusted pressure value is equal to the current pressure value multiplied by (1 - the absolute value of the flow error rate); Wherein, the current pressure value is the pressure value obtained from the previous calibration. If it is the first calibration, the current pressure value is the pressure value calculated according to the pressure-flow correspondence relationship.

[0014] By adopting the above technical solution, in order to accurately calculate the pressure calibration value, traditional methods often adopt fixed step size or simple proportional adjustment, which are difficult to meet the adjustment requirements under different error degrees. The system of this application judges the positive and negative directions of the flow error. When the actual flow is less than the target value, the pressure value is increased according to the error ratio; when the actual flow is greater than the target value, the pressure value is decreased according to the error ratio. At the same time, by introducing the historical pressure value as a reference, the continuity and stability of the adjustment are ensured; the adaptive optimization of the adjustment step size is realized, and through the differential processing of positive and negative errors, the accuracy and efficiency of the adjustment are improved.

[0015] Optionally, the method further includes the following steps: When the flow error rate is negative and exceeds the first preset threshold after continuous multiple calibrations, it is determined that there is a risk of clogging in the medicine discharge pipe, and an alarm for clogging in the medicine discharge pipe is triggered and recalibration is prompted; When the flow error rate is positive and exceeds the first preset threshold after continuous multiple calibrations, it is determined that there is a risk of proportional valve failure or leakage in the medicine adding pipe, and the corresponding alarm is triggered and inspection and troubleshooting are prompted.

[0016] By adopting the above technical solution, in order to timely detect equipment failures and potential safety hazards in the medicine adding system, traditional methods mainly rely on manual inspections and experience judgments, which are difficult to achieve early warning. For example, in a sewage treatment plant during the flocculant adding process, due to the inability to timely detect the clogging risk caused by pipeline scaling, the medicine adding pipeline was finally completely blocked, and it had to be shut down for cleaning, affecting the process continuity. The system of this application continuously monitors the change trend of the flow error rate. When a persistent negative error is found, it is determined that there may be a clogging risk in the medicine discharge pipeline; when a persistent positive error appears, it is determined that there is a risk of proportional valve failure or pipeline leakage, and different types of fault risks are given differential alarms and treatment suggestions; not only the early warning of equipment failures is realized, but also a preliminary diagnosis of the cause of the failure is provided through intelligent analysis.

[0017] In a second aspect, this application provides a one-to-one pressure medicine adding system for sewage treatment, including: A medicine adding tank, a pressure sensor, a liquid level sensor, a proportional valve, and a controller; The pressure sensor is used to measure the current pressure value of the medicine adding tank; The liquid level sensor is used to measure the change value of the liquid level of the medicine adding tank; The proportional valve is used to adjust the pressure value of the chemical dosing tank; The controller is electrically connected to the pressure sensor, the liquid level sensor and the proportional valve respectively, and is used to execute the above one-to-one pressure chemical dosing method for sewage treatment.

[0018] Optionally, the system further includes: A chemical inlet valve for supplementing the chemical liquid into the chemical dosing tank; A chemical dosing valve for controlling the output of the chemical liquid; The controller is also electrically connected to the chemical inlet valve and the chemical dosing valve, and is used to control the chemical inlet and dosing processes according to the measured value of the liquid level sensor.

[0019] In a third aspect, the present application provides a chemical dosing device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the above one-to-one pressure chemical dosing method for sewage treatment are implemented.

[0020] In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above one-to-one pressure chemical dosing method for sewage treatment are implemented.

[0021] In summary, the present application includes at least one of the following beneficial technical effects: 1. By using the Bernoulli equation principle in fluid mechanics, the present application discovers that there is a proportional relationship between the pressure value and the square of the flow rate value. Under a certain working condition, first establish the corresponding relationship between pressure and flow rate, after obtaining the target chemical dosing flow rate value, substitute the target chemical dosing flow rate value into the preset pressure-flow corresponding relationship, calculate the required pressure value of the chemical dosing tank, and then use the liquid level change value to obtain the actual flow rate value, and compare and calibrate the actual flow rate value with the target chemical dosing flow rate value; avoiding the disadvantage that the flow meter is easily damaged when using the traditional flow meter, adopting stable and reliable pressure sensors and liquid level sensors, and realizing accurate measurement through intelligent algorithms, with lower cost and higher reliability; 2. The traditional method is only applicable to one working condition. When the type of chemical agent changes, or the flow meter or pipeline is fouled, the measurement accuracy will be greatly reduced; for example, when a certain sewage treatment plant adds lime, due to the strong fouling property of the chemical agent, the chemical dosing flow deviation can reach more than 30%. The present application first selects multiple pressure values within the working pressure range, obtains the actual flow rate by accurately measuring the liquid level change at each pressure value, and then uses the mathematical model P = MQ² + N for data fitting, and introduces the fitting correlation coefficient as the judgment basis for the calibration quality; establishing a general pressure-flow relationship through mathematical modeling and statistical methods, not only improving the chemical dosing accuracy, but also being able to adapt to the working condition changes under different viscosity and temperature conditions; 3. It ensures the continuity and accuracy of the calibration process, and improves the problem that traditional calibration methods often require manual judgment and manual liquid replenishment when the liquid medicine is insufficient, which is prone to cause calibration interruption or data incoherence. The system of this application continuously monitors the liquid level change. When the liquid level drops to the preset low value, the dosing valve is automatically closed and the medicine inlet valve is opened for liquid replenishment. After the liquid level recovers, the calibration process continues seamlessly. At the same time, the fitting correlation coefficient is introduced as an evaluation index for the calibration quality to ensure obtaining a high-precision pressure-flow correspondence relationship. It not only avoids the errors and interruptions caused by manual intervention, but also realizes the high efficiency, precision and reliability of the calibration process through intelligent control and data quality evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic flow chart of a one-to-one pressure dosing method for sewage treatment according to an embodiment of this application; Figure 2 is a schematic diagram of the dosing system according to an embodiment of this application; Figure 3 is a schematic flow chart of step S110 in a one-to-one pressure dosing method for sewage treatment according to an embodiment of this application; Figure 4 is a schematic diagram of data fitting according to an embodiment of this application; Figure 5 is a schematic flow chart of calibrating the pressure-flow correspondence relationship according to an embodiment of this application; Figure 6 is a schematic flow chart of step S140 in a one-to-one pressure dosing method for sewage treatment according to an embodiment of this application; Figure 7 is a schematic flow chart of step S141 in a one-to-one pressure dosing method for sewage treatment according to an embodiment of this application; Figure 8 is a schematic flow chart of fault analysis in a one-to-one pressure dosing method for sewage treatment according to an embodiment of this application; Figure 9 is a schematic module diagram of a one-to-one pressure dosing system for sewage treatment according to an embodiment of this application; Figure 10 is an internal structure diagram of a dosing device according to an embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The terms used in the following embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and appended claims of the present application, the singular forms "a", "an", "the", "above-mentioned", "said", and "this" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term " / or" used in the present application refers to any or all possible combinations including one or more of the listed items.

[0024] Hereinafter, the terms "first" and "second" are only used for descriptive purposes and should not be construed as implying or suggesting relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0025] The embodiments of the present application will be further described in detail below with reference to the accompanying drawings of the specification.

[0026] In a first aspect, the present application provides a one-to-one pressure dosing method for sewage treatment. Referring to Figure 1 , the method includes the following steps: S110. Obtain the target dosing flow value, substitute the target dosing flow value into the preset pressure-flow corresponding relationship formula, and calculate the required pressure value of the dosing tank.

[0027] Among them, in the pressure-flow corresponding relationship formula, the pressure value is positively correlated with the square of the flow value.

[0028] In this embodiment, an A / B dual-tank alternating dosing system is adopted, as Figure 2 shown. Each dosing tank is equipped with an independent pressure sensor and a liquid level sensor, and the respective dosing valves and medicine inlet valves are controlled by a PLC. The system is set with an automatic switching mechanism. When the working dosing tank (such as tank A) runs to the low liquid level, it automatically switches to another full-liquid-level dosing tank (tank B) to continue dosing, ensuring that the dosing process is uninterrupted. The two dosing tanks work alternately and serve as backups for each other.

[0029] Among them, the pressure-flow corresponding relationship formula is obtained through pre-calibration. The calibration process is to measure the corresponding flow values with different pressure values as inputs under stable working conditions and establish the corresponding relationship between pressure P and flow Q. Through data analysis, it is found that there is a linear relationship between pressure and the square of the flow, that is, P = kQ², where k is the pipeline characteristic coefficient and is related to factors such as pipeline layout and liquid physical properties.

[0030] Specifically, in practical applications, first input the target flow value, calculate the theoretical pressure value through the relational formula, adjust the opening of the proportional valve through PLC analog conversion to stabilize the tank pressure within the range of this pressure value, and then start the chemical dosing process.

[0031] S120. Measure the liquid level change value through the liquid level sensor to obtain the measured flow value.

[0032] In this embodiment, a liquid level sensor is used to measure the liquid level change of the chemical dosing tank. Within a preset time interval, record the liquid level drop value ΔH. Combining with the cross-sectional area S of the chemical dosing tank, the actual volume flow can be calculated. This method is used to replace the flowmeter to solve the problems (such as scaling, staining, and reduced accuracy) that occur when using the flowmeter, while ensuring the measurement accuracy. To reduce the influence caused by liquid level fluctuations, the system uses the sliding average value of multiple measurements as the final measured flow value.

[0033] S130. Compare the target chemical dosing flow value with the measured flow value to determine the flow error rate.

[0034] In this embodiment, the flow error rate ε is calculated using the relative error method, that is, ε = (Q measured - Q target) / Q target × 100%. The system establishes an error evaluation database to record the error change trend under different working conditions for subsequent fault diagnosis and predictive maintenance.

[0035] Specifically, the system divides the error rate into a normal range, a warning range, and an alarm range, and displays them in different colors on the control interface for the operator to intuitively judge the system operation status.

[0036] S140. When the flow error rate exceeds the preset range, adjust the pressure value of the chemical dosing tank for calibration until the flow error rate is within the preset range.

[0037] In this embodiment, multiple levels of error ranges are preset. For example, the first level of ±5% is the normal range and no adjustment is required; the second level of ±5% - ±15% requires automatic calibration; the third level exceeding ±15% triggers an alarm and requests manual intervention. The system uses the look-up table method to establish the corresponding relationship between the error rate and the pressure correction value, avoiding complex model calculations.

[0038] Specifically, when the flow error rate is -8%, the system queries the preset calibration table and determines that the current pressure value needs to be increased by 8%. For example, when the current pressure is 0.5 MPa, the adjusted pressure value is 0.54 MPa. The system performs pressure regulation through a proportional regulating valve, waits for the system to stabilize (about 30 s) after each adjustment, and then conducts the next error assessment until the error rate returns to the normal range. During actual operation, the program conducts multiple calibrations within the error range of 5 - 15%. Among them: If the pressure increases beyond the preset safety tank pressure and the actual chemical addition flow still does not return to the normal range, the calibration is stopped; or, if the pressure decreases below the preset low-limit tank pressure and the actual chemical addition flow still does not return to the normal range, the calibration is also stopped, and an abnormal alarm can be triggered simultaneously.

[0039] Further, the system can also be set such that if the error has not improved after continuously adjusting the preset number of times, the calibration is stopped and an abnormal alarm is triggered.

[0040] In one embodiment, referring to Figure 3 , in step S110, the pressure-flow corresponding relationship is obtained through calibration, which specifically includes the following steps: S111. Select multiple pressure values, which are set from low to high within the allowable range of the working pressure.

[0041] This embodiment is based on the Bernoulli equation principle and uses the least squares method to fit the pressure-flow data. As Figure 4 shown, the horizontal axis is the square value of the flow rate, and the vertical axis is the pressure value (unit: MPa). In the fitting equation P = MQ² + N, M reflects the pipeline characteristics (related to pipe diameter, layout, etc.), and N reflects the static pressure loss. It can be seen from the figure that the measured data points are basically evenly distributed on the fitting line within the range of flow rate square from 100 to 300, and the fitting correlation coefficient R² reaches 0.99, indicating that there is a significant linear relationship between the pressure and the square of the flow rate.

[0042] Specifically, the system establishes a database to record the pressure values, flow rate values, and fitting parameters during the calibration process. Taking Figure 4 as an example, when the square of the flow rate is 100, the corresponding pressure value is approximately 0.1 MPa; when the square of the flow rate increases to 200, the pressure value rises to approximately 0.2 MPa. Through this linear correspondence, the system can quickly calculate the required pressure value according to the target flow rate. For example, if it is necessary to reach the working condition with a flow rate square of 150, the required pressure value can be directly read from the figure or calculated by substituting into the fitting equation, which is approximately 0.15 MPa.

[0043] Further, in this embodiment, the two chemical addition tanks A and B are calibrated respectively. First, the whole process calibration of tank A is carried out: select 5 - 10 points, perform calibration from low to high, and the pressure setting range is the working allowable range, which is an empirical value. Through on-site debugging, find the output pressure values corresponding to the minimum and maximum chemical addition flow rates required, further determine the calibration pressure setting range, and record the steady-state flow rate data for 30 seconds at each pressure point. After completing the calibration of tank A and saving the parameters, switch to tank B for calibration of the same process. Considering that there may be slight differences in the pipeline layouts of the two chemical addition tanks (such as pipeline length, number of elbows, etc.), the system establishes the corresponding relational expressions of pressure and flow rate for each of them respectively, and finally obtains two sets of values M and N.

[0044] S112. Calculate the corresponding actual average flow rate value under each of the above pressure values through the change in the liquid level of the chemical addition tank within a preset time period.

[0045] In this embodiment, a liquid level sensor is used to measure the change in the liquid level of the chemical addition tank. At each pressure point, the system maintains a stable chemical addition time of 30 seconds, and calculates the average flow rate value through the change in the liquid level.

[0046] Specifically, assume the radius of the chemical addition tank is 0.25 meters. Then when the pressure is stable at 0.5 MPa, if the liquid level drops from 1200 mm to 1180 mm within 30 seconds, the corresponding flow rate Q = cross-sectional area × liquid level change / time = 0.196 × 0.02 × 120 = 0.471 m³ / h. The system samples the instantaneous flow rate within 30 seconds 5 times and takes the average to eliminate the influence of random errors. The liquid level curve and the calculated flow rate value are displayed in real time through the operation screen, enabling the operator to intuitively monitor the calibration process.

[0047] S113. Fit multiple set pressure values and the corresponding measured average flow rate values with the relational expression P = MQ² + N to determine the values of the fitting coefficients M and N.

[0048] Among them, P is the pressure value of the chemical addition tank, and Q is the chemical addition flow rate value.

[0049] In this embodiment, based on the Bernoulli equation principle, the least squares method is used to fit the pressure and flow rate data. In the fitting equation P = MQ² + N, M reflects the pipeline characteristics (related to pipe diameter, layout, etc.), and N reflects the static pressure loss. The system substitutes 10 groups of pressure and flow rate data into the equation and solves for the optimal fitting parameters through matrix operations.

[0050] Specifically, the system establishes a database to record the pressure values, flow rate values, and fitting parameters during the calibration process.

[0051] S114. Determine whether the fitting correlation coefficient exceeds the correlation coefficient of the preset fitting formula. When the fitting correlation coefficient exceeds the correlation coefficient of the preset fitting formula, complete the calibration of the pressure-flow rate corresponding relational expression.

[0052] In this embodiment, the correlation coefficient of the fitting formula is set to 0.99, that is, it is required that the fitting correlation coefficient R² of the pressure-flow data is ≥0.99. The system evaluates the fitting quality by calculating the sum of the squared deviations between the measured values and the fitting values. Re-calibration is triggered when the following situations occur: the device is used for the first time, it runs continuously for 30 days, it is restarted after 30 days of shutdown, the pipeline is modified, the calibration fails, etc. It can be understood that for the number of days of continuous operation and the restart after the number of days of shutdown, the number of days can be adjusted dynamically according to the actual situation.

[0053] Specifically, when the system calculates that R² = 0.995, it indicates that the calibration result is reliable, automatically saves the fitting parameters and switches to the normal operation mode. If R² < 0.99, the system will give an alarm prompt "Calibration abnormal" and display the possible reasons (such as unstable pressure, level gauge failure, etc.). The operator can view the calibration curve, judge the abnormal points and re-calibrate.

[0054] In one embodiment, referring to Figure 5 , the pressure-flow corresponding relationship is obtained through calibration, and the following steps are further included: S115. Judge whether the chemical addition tank reaches the low liquid level through liquid level monitoring.

[0055] In this embodiment, a three-level liquid level early warning mechanism is established. High, medium and low liquid level points are set in the medicine storage module, which are 80%, 50% and 20% of the total height of the liquid level in the tank respectively. The system collects liquid level data in real time through liquid level sensors and sets a simple liquid level judgment table to convert the liquid level signal into a percentage for automatic control during the calibration process.

[0056] Specifically, when the liquid level is lower than 20%, the system will trigger a low liquid level early warning. To ensure the accuracy of the calibration data, when the system records the liquid level change at each pressure point, it will first check whether the current liquid level meets the minimum liquid level requirement. For example, if the calibration at the 0.2 MPa pressure point is currently in progress and it is expected that the liquid level will drop by 20 mm within 30 seconds, the system will predict whether the end liquid level will be lower than 300 mm, so as to decide in advance whether it is necessary to supplement the medicine.

[0057] S116. When the chemical addition tank reaches the low liquid level, close the chemical addition valve, pause the calibration, and open the medicine inlet valve to add medicine to the high liquid level.

[0058] In this embodiment, a sequential control strategy is adopted for automatic medicine supplementation. When the low liquid level signal is detected, the control system first closes the chemical addition solenoid valve and records the parameters of the uncompleted calibration pressure points. Then, it sends a medicine supplementation instruction to the PLC, opens the medicine inlet pump and the medicine inlet valve according to the preset program, and at the same time displays the "Medicine supplementing" status on the operation screen.

[0059] S117. After the medicine addition reaches the high liquid level, close the medicine inlet valve and continue to perform the calibration.

[0060] In this embodiment, a function of resuming calibration from a breakpoint is designed. After the medicine replenishment is completed, the system first enters a 2-minute static waiting period to make the liquid level tend to be stable. Subsequently, query the last calibrated pressure value and the completed data points stored in the breakpoint record table, and automatically continue to execute the uncompleted calibration steps.

[0061] Specifically, if the system was performing the calibration of the 6th pressure point (1.1 MPa) before the medicine replenishment, after the medicine replenishment is completed, when the system re-intakes gas and stabilizes the pressure, it will monitor whether the pressure is stable at the 6th pressure point, then re-calibrate the 6th point according to the pressure monitoring result to verify the accuracy of the calibrated data, and then re-record the flow rate for 30 seconds at this pressure point. The data of the completed 5 pressure points remain unchanged, and continue to collect the data of the 6th to 10th pressure points. This mechanism of resuming calibration from a breakpoint significantly improves the calibration efficiency and avoids repetitive work.

[0062] S118. When the fitting correlation coefficient does not exceed the correlation coefficient of the preset fitting formula, re-execute the calibration steps.

[0063] In this embodiment, the system establishes a calibration quality evaluation mechanism. After the data collection of all pressure points is completed, calculate the fitting correlation coefficient R² by the least square method. If R² < 0.99, analyze the abnormal reasons manually, and judge the possible fault points by querying the preset fault feature table according to parameters such as the pressure fluctuation degree and the liquid level change trend. It can be understood that the system can also automatically query the preset fault feature table to judge the possible fault points according to parameters such as the pressure fluctuation degree and the liquid level change trend.

[0064] Specifically, when the calibration fails, the system first performs a self-check of the equipment: check whether the signal of the pressure sensor is stable (fluctuation < 1%), whether the liquid level sensor is working properly (signal continuity), whether the actions of each valve are in place, etc. If the equipment status is normal, re-perform the calibration, and at the same time extend the stable time of each pressure point to 45 seconds to obtain more stable flow rate data. If the calibration still fails after three consecutive attempts, the system will alarm and prompt for manual inspection.

[0065] In one embodiment, referring to Figure 6 , in step S140, when the flow rate error rate exceeds the preset range, adjust the pressure value of the medicine addition tank for calibration, which specifically includes the following steps: S141. When the absolute value of the flow rate error rate exceeds the first preset threshold and is less than the second preset threshold, automatically adjust the output pressure value according to the current output pressure and the flow rate error rate.

[0066] Among them, this application provides two pressure adjustment methods, including adjusting using the corresponding relational formula and adjusting using the preset look-up table method, and establishing a correspondence table between the error rate and the correction coefficient; one of them can be selected for implementation according to the specific application scenario. When adjusting using the corresponding relational formula, when the flow error rate is negative, the adjusted pressure value is equal to the current pressure value multiplied by (1 + the absolute value of the flow error rate); when the flow error rate is positive, the adjusted pressure value is equal to the current pressure value multiplied by (1 - the absolute value of the flow error rate). Among them, the current pressure value is the pressure value obtained from the previous calibration. If it is the first calibration, the current pressure value is the pressure value calculated according to the pressure-flow corresponding relational formula. When adjusting the output pressure value using the preset look-up table method; this embodiment sets a two-stage flow error warning mechanism, the first preset threshold is 5%, and the second preset threshold is 15%. The system establishes a correspondence table between the error rate and the pressure correction coefficient through the look-up table method, avoiding complex calculations. For example, when the error rate is in the range of 5%-7%, the pressure correction coefficient is taken as 1.05~1.07; when the error rate is in the range of 7%-10%, the correction coefficient is taken as 1.07~1.1; when the error rate is in the range of 10%-15%, the correction coefficient is taken as 1.1~1.15.

[0067] In this embodiment, the system establishes independent calibration parameter databases for each of the two chemical addition tanks A and B. When tank A is operating, the pressure-flow relational formula of tank A and historical calibration data are used for control; when switching to tank B, the corresponding parameters of tank B are automatically called. This sub-tank control strategy takes into account the possible differences between the two chemical addition systems in actual installation and use, improving the chemical addition accuracy.

[0068] It can be understood that the operating parameters of only A or B can be simultaneously applied to the two chemical addition tanks to improve the calibration efficiency and achieve calibration without stopping the machine during actual operation.

[0069] S142. Output according to the adjusted pressure value through the proportional valve.

[0070] This embodiment adopts a segmented adjustment strategy to control the output of the proportional valve. The system divides the pressure range of 0-1 MPa into 10 intervals and establishes a segmented linear correspondence table between the valve opening and the pressure. Different PID parameters are used for each interval to ensure that the adjustment process is both fast and stable.

[0071] Specifically, when it is necessary to adjust the pressure from 0.3 MPa to 0.315 MPa, the system first determines the interval (0.2-0.4 MPa) where the target pressure is located and calls the corresponding PID parameter group. The proportional valve adjusts the output step by step according to the preset change rate, and at the same time, real-time feedback is carried out through the pressure sensor to ensure that the pressure is stabilized at the target value.

[0072] S143. When the absolute value of the flow error rate after calibration is less than the first preset threshold, stop the automatic calibration.

[0073] In this embodiment, a flow error evaluation database is established to record the error change trend after each calibration. The system calculates the average flow rate every 30 seconds. When the error rates for three consecutive times are all less than 5%, it is determined that the calibration is successful. To avoid error jitter, the system uses the moving average method to process the original data.

[0074] Specifically, assume that the error rate calculated for the first time after calibration is -4.8%, the second time is -4.2%, and the third time is -4.5%. The absolute values of the error rates for all three times are less than 5%, and the change trend is stable. The system then considers the calibration to be up to standard and continues to operate while maintaining the current pressure setting value. At the same time, the starting error, adjustment process, and final result of this calibration are recorded in the database for subsequent system optimization.

[0075] S144. When the absolute value of the flow error rate still cannot be made less than the first preset threshold after exceeding the preset number of calibrations, and the tank pressure exceeds the preset safe working pressure value, stop the automatic calibration and trigger an alarm to prompt for recalibration.

[0076] In this embodiment, the number of calibrations is set to 3 times, and the preset pressure value is 0.4 MPa. The system records the number of calibrations through a counter and establishes an empirical pressure overrun judgment table. When the error still exceeds 5% after three consecutive calibrations and the current pressure has reached 0.4 MPa, the system determines that the current working condition has exceeded the range of automatic calibration capabilities.

[0077] Specifically, if the error after the first calibration of the system is -8%, the second is -7%, and the third is still -6%, and the final pressure reaches 0.42 MPa, exceeding the preset pressure value of 0.4 MPa, then stop the automatic calibration. The system triggers an alarm and displays a prompt message of "Calibration pressure overrun, please recalibrate" on the operation screen. At the same time, the current working condition parameters, including pressure value, flow rate value, error rate, etc., are recorded for technical personnel to conduct fault analysis and optimize the calibration parameters.

[0078] In one embodiment, referring to Figure 7 , in step S141, automatically adjusting the output pressure value according to the current output pressure and the flow error rate specifically includes the following steps: S1411. When the flow error rate is negative, the adjusted pressure value is equal to the current pressure value multiplied by (1 + the absolute value of the flow error rate).

[0079] In this embodiment, a proportional adjustment method is adopted to handle the negative flow error. When it is detected that the actual flow is less than the target flow, it indicates that the current pressure is insufficient, and the pressure needs to be increased according to the error ratio. The system sets a pressure adjustment limit table, and sets the maximum adjustment step according to different pressure intervals to avoid the system instability caused by too large a single adjustment amplitude.

[0080] S1412. When the flow error rate is positive, the adjusted pressure value is equal to the current pressure value multiplied by (1 - the absolute value of the flow error rate).

[0081] Among them, the current pressure value is the pressure value obtained from the previous calibration. If it is the first calibration, the current pressure value is the pressure value calculated according to the pressure-flow corresponding relationship.

[0082] In this embodiment, a decreasing adjustment strategy is designed for the positive flow error. The system establishes a pressure attenuation coefficient table. Considering the non-linear relationship between flow and pressure, different attenuation rates are adopted in different error ranges to ensure that the adjustment process is both accurate and stable.

[0083] Furthermore, this embodiment also designs an adaptive adjustment mechanism based on the system operation characteristics. Specifically, when tank A is operating, the pressure adjustment value needs to consider the following factors: the historical adjustment effect influence coefficient α = 1 ± 0.2×(1 - E_last / E_current), where E_last is the error rate after the previous adjustment, and E_current is the current error rate. When the adjustment effect gets better, the adjustment amplitude is reduced; the liquid level influence coefficient of the chemical dosing tank β = 1 + 0.1×(H_max - H_current) / H_max, where H_current is the current liquid level height and H_max is the maximum liquid level of the tank. As the liquid level decreases, the pressure adjustment becomes more sensitive; the continuous operation time influence coefficient γ = 1 + 0.05×(T_current / T_standard), where T_current is the current continuous operation time and T_standard is the standard operation cycle (such as 8 hours), considering that long-term operation may cause system characteristic drift.

[0084] Therefore, when the flow error rate is negative, P_new = P_current × (1 + |A|) × α × β × γ; when the flow error rate is positive, P_new = P_current × (1 - |A|) × α × β × γ, where |A| is the absolute value of the flow error rate. For example, during a certain adjustment of Tank A, the error rate after the previous adjustment was -10% and the current error rate is -8%. After calculation, α = 0.95; the current liquid level is 40% of the maximum liquid level, and after calculation, β = 1.06; the system has been continuously operating for 6 hours, and after calculation, γ = 1.0375; the current pressure is 0.3 MPa and the flow error rate is -8%, then the adjusted pressure value is 0.34 MPa. When switching to Tank B, the system will reset the continuous operation time counter but retain the historical adjustment effect data to ensure the smoothness of the switching process. Through this multi-factor adaptive adjustment mechanism, the system can better adapt to the chemical dosing requirements under different working conditions and improve the adjustment accuracy and stability.

[0085] In one embodiment, referring to Figure 8 , the method further includes the following steps: S210. When the flow error rate is negative and exceeds the first preset threshold after continuous calibration for multiple times, it is determined that there is a risk of clogging in the medicine discharge pipe, and a clogging alarm for the medicine discharge pipe is triggered and a prompt for re-calibration is given.

[0086] In this embodiment, a fault feature library is established to identify the risk of clogging in the medicine discharge pipe. The system sets three consecutive calibrations as the judgment period, and records the change trends of the error rate and pressure value after each calibration. When it is found that the error rates are all negative and greater than 5% for three consecutive times, even if the pressure is continuously increasing but the flow rate is always small, the system matches this feature with the clogging mode in the fault library.

[0087] Specifically, assume that during three consecutive calibrations of the system, the flow error rates are -6.5%, -7.2%, and -8.1% respectively, and the pressure value gradually increases from the initial 0.3 MPa to 0.35 MPa, but the actual flow rate still does not reach the target value. This phenomenon of increasing pressure but continuously small flow rate conforms to the characteristics of gradual clogging of the medicine discharge pipe. The system will trigger a "pipe clogging warning", display a red warning sign on the operation screen, and give a recommended operation prompt: "Please check the medicine discharge pipeline and perform backwashing. After the treatment is completed, re-calibration is required."

[0088] Further, in this embodiment, fault cross-verification is performed by comparing the operation data of dosing tanks A and B. For example, when the flow error rates of tank A are -6.5%, -7.2%, and -8.1% respectively after three consecutive calibrations, while tank B is operating normally during the same period, the system is more likely to determine that the pipeline of tank A is blocked rather than a fault in the common part of the system. When the system triggers an alarm, it will suggest switching to the normally operating tank B first and simultaneously repairing tank A. Similarly, when it is detected that a certain dosing tank may have leakage, the system will record the historical data of the pressure and flow rate of this tank and compare it with the data of another dosing tank operating normally to assist the maintenance personnel in quickly locating the fault point.

[0089] S220. When the flow error rate is positive and exceeds the first preset threshold after multiple consecutive calibrations, it is determined that there is a proportional valve fault or a risk of leakage in the dosing pipe, and the corresponding alarm is triggered and a prompt for inspection and troubleshooting is given.

[0090] In this embodiment, a two-way diagnosis strategy is adopted to distinguish proportional valve faults and pipeline leakage. The system has preset the typical characteristics of the two faults in the working condition database: proportional valve faults usually manifest as a mismatch between the valve opening and the pressure value, while pipeline leakage is manifested as normal pressure but abnormally large flow rate. Through a logic judgment tree, the possible fault points can be quickly located.

[0091] Specifically, when the system detects that the flow error rates in three consecutive calibrations are +7.8%, +8.5%, and +9.2% respectively, first analyze the corresponding relationship between the pressure and the valve opening. If the pressure shows 0.25 MPa but the actual valve opening significantly deviates from the standard curve, the system determines that there is a proportional valve fault and triggers a "Proportional valve abnormal" warning; if the pressure and the valve opening match but the flow rate continues to be large, it is determined that there is a risk of pipeline leakage and a "Pipeline leakage inspection" prompt is triggered. Different alarm types are configured with different warning colors and handling suggestions, such as "Please check the proportional valve feedback signal" or "Please inspect whether there is a leakage point in the pipeline". At the same time, the system automatically records the complete working condition data when the fault occurs, including parameters such as pressure, flow rate, and valve opening, providing a basis for subsequent maintenance.

[0092] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0093] In a second aspect, the present application provides a one-to-one pressure dosing system for sewage treatment. The one-to-one pressure dosing system for sewage treatment of the present application will be described below in combination with the above-mentioned one-to-one pressure dosing method for sewage treatment.

[0094] Refer to Figure 9 , a one-to-one pressure dosing system for sewage treatment, comprising: A chemical dosing tank, a pressure sensor, a liquid level sensor, a proportional valve, and a controller; The pressure sensor is used to measure the current pressure value of the chemical dosing tank; The liquid level sensor is used to measure the change value of the liquid level in the chemical dosing tank; The proportional valve is used to adjust the pressure value of the chemical dosing tank; The controller is electrically connected to the pressure sensor, the liquid level sensor, and the proportional valve respectively, and is used to execute the above-mentioned one-to-one pressure chemical dosing method for sewage treatment.

[0095] In one embodiment, the system further includes: A chemical inlet valve, which is used to supplement the chemical liquid into the chemical dosing tank; A chemical dosing valve, which is used to control the output of the chemical liquid; The controller is also electrically connected to the chemical inlet valve and the chemical dosing valve, and is used to control the chemical inlet and chemical dosing processes according to the measured value of the liquid level sensor.

[0096] In one embodiment, the present application provides a chemical dosing device, and its internal structure diagram can be as Figure 10 shown. The chemical dosing device includes a processor, a memory, and a network interface connected through a system bus. Among them, the processor of the chemical dosing device is used to provide computing and control capabilities. The memory of the chemical dosing device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the chemical dosing device is used to store data. The network interface of the chemical dosing device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a one-to-one pressure chemical dosing method for sewage treatment.

[0097] Those skilled in the art can understand that Figure 10 the structure shown in

[0098] is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the chemical dosing device to which the solution of the present application is applied. The specific chemical dosing device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0099] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The above computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above various methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0100] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereby. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A one-to-one pressure dosing method for sewage treatment, characterized in that, The method includes the following steps: Obtain the target chemical dosing flow value, substitute the target chemical dosing flow value into a preset pressure-flow corresponding relationship formula, and calculate the required pressure value of the chemical dosing tank. In the pressure-flow corresponding relationship formula, the pressure value is proportional to the square of the flow value; Measure the liquid level change value through a liquid level sensor to obtain the measured flow value; Compare the target chemical dosing flow value with the measured flow value to determine the flow error rate; When the flow error rate exceeds the preset range, adjust the pressure value of the chemical dosing tank for calibration until the flow error rate is within the preset range; 2. The one-to-one pressure chemical addition method for sewage treatment according to claim 1, characterized in that The pressure-flow corresponding relationship formula is obtained through calibration, which specifically includes the following steps: Select multiple pressure values, which are set from low to high within the allowable working pressure range; Calculate the corresponding actual average flow value at each of the above pressure values through the liquid level change of the chemical dosing tank within a preset time period; Fit multiple set pressure values and the corresponding measured average flow values with the relationship formula P = MQ² + N to determine the values of the fitting coefficients M and N, where P is the pressure value of the chemical dosing tank and Q is the chemical dosing flow value; Judge whether the fitting correlation coefficient exceeds the correlation coefficient of the preset fitting formula. When the fitting correlation coefficient exceeds the correlation coefficient of the preset fitting formula, complete the calibration of the pressure-flow corresponding relationship formula; 3. The one-to-one pressure chemical dosing method for sewage treatment according to claim 2, wherein The pressure-flow corresponding relationship formula is obtained through calibration, and it also includes the following steps: Judge whether the chemical dosing tank reaches the low liquid level through liquid level monitoring; When the chemical dosing tank reaches the low liquid level, close the chemical dosing valve, pause the calibration, and open the medicine inlet valve to add medicine to the high liquid level; When the liquid level reaches the high liquid level after adding medicine, close the medicine inlet valve and continue to perform the calibration; When the fitting correlation coefficient does not exceed the correlation coefficient of the preset fitting formula, re-execute the calibration steps; 4. The one-to-one pressure chemical addition method for sewage treatment according to claim 1, characterized in that, When the flow error rate exceeds the preset range, adjust the pressure value of the chemical dosing tank for calibration, which specifically includes the following steps: When the absolute value of the flow error rate exceeds the first preset threshold and is less than the second preset threshold, automatically adjust the output pressure value according to the current output pressure and the flow error rate; Output according to the adjusted pressure value through a proportional valve; When the absolute value of the flow error rate after calibration is less than the first preset threshold, stop the automatic calibration; When the absolute value of the flow error rate still cannot be less than the first preset threshold after exceeding the preset calibration times, and the tank pressure exceeds the preset safe working pressure value, stop the automatic calibration and trigger an alarm to prompt re-calibration; 5. The one-to-one pressure chemical addition method for sewage treatment according to claim 4, characterized in that Automatically adjust the output pressure value according to the current output pressure and the flow error rate, which specifically includes the following steps: When the flow error rate is negative, the adjusted pressure value is equal to the current pressure value multiplied by (1 + the absolute value of the flow error rate); When the flow error rate is positive, the adjusted pressure value is equal to the current pressure value multiplied by (1 - the absolute value of the flow error rate); Wherein, the current pressure value is the pressure value obtained from the previous calibration. If it is the first calibration, the current pressure value is the pressure value calculated according to the pressure-flow corresponding relationship formula; 6. The one-to-one pressure chemical addition method for sewage treatment according to claim 5, wherein The method further includes the following steps: When the flow error rate is negative and exceeds the first preset threshold after continuous multiple calibrations, it is determined that there is a risk of blockage in the medicine discharge pipe, trigger an alarm for blockage of the medicine discharge pipe and prompt re-calibration; When the flow error rate is positive and exceeds the first preset threshold after continuous calibration for multiple times, it is determined that there is a proportional valve failure or a risk of chemical addition pipe leakage, triggering corresponding alarms and prompting inspection and troubleshooting.

7. A one-to-one pressure chemical dosing system for sewage treatment, characterized in that, Including: A chemical addition tank, a pressure sensor, a liquid level sensor, a proportional valve, and a controller; The pressure sensor is used to measure the current pressure value of the chemical addition tank; The liquid level sensor is used to measure the liquid level change value of the chemical addition tank; The proportional valve is used to adjust the pressure value of the chemical addition tank; The controller is electrically connected to the pressure sensor, the liquid level sensor, and the proportional valve respectively, and is used to execute the one-to-one pressure chemical addition method for sewage treatment described in any one of claims 1-6.

8. The one-to-one pressure chemical dosing system for sewage treatment according to claim 7, characterized in that, The system further includes: A chemical inlet valve for replenishing the chemical addition tank with liquid medicine; A chemical addition valve for controlling the output of the liquid medicine; The controller is also electrically connected to the chemical inlet valve and the chemical addition valve, and is used to control the chemical inlet and chemical addition processes according to the measurement value of the liquid level sensor.

9. A chemical dosing device, characterized in that, Including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the computer program, the steps of the one-to-one pressure chemical addition method for sewage treatment described in any one of claims 1-6 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the one-to-one pressure chemical addition method for sewage treatment described in any one of claims 1-6 are implemented.

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