Opening self-learning liquid level control system and method
By employing a self-learning level control method based on valve opening, and utilizing a valve opening database and a slow-fast adjustment strategy, the problem of response lag and frequent valve adjustment in the level control of sulfur autotrophic filters was solved, achieving rapid and accurate level control and extending the lifespan of the regulating valve.
Patent Information
- Application Number
- CN202511619438.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-06
- Publication Date
- 2025-12-16
AI Technical Summary
Existing PID control methods exhibit lag in response to sulfur autotrophic filter level control, failing to address instantaneous flow fluctuations in a timely manner. This results in level fluctuations exceeding the allowable range, and frequent valve adjustments shorten the lifespan of the regulating valves, increasing maintenance costs.
The self-learning level control method is adopted. By periodically acquiring the filter tank level and flow rate, matching the preset valve opening using the valve opening database, and combining slow and fast adjustment strategies, the valve opening is adjusted according to the degree of level deviation to achieve fast and accurate control.
It improves the response speed and accuracy of liquid level control, reduces the valve adjustment frequency, extends the service life of the control valve, and reduces maintenance costs.
Smart Images
Figure CN121143484A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment technology, specifically to an opening degree self-learning liquid level control system and method. Background Technology
[0002] Sulfur autotrophic filters are biological filters that utilize sulfur autotrophic denitrification technology for deep nitrogen removal. They primarily utilize microorganisms such as *Thiobacillus* to oxidize elemental sulfur or sulfides under anaerobic conditions, providing electrons for the denitrification process and reducing NO3 to N2, thereby achieving deep denitrification of nitrate-contaminated wastewater. Sulfur autotrophic filters are mainly used to treat nitrate-contaminated water bodies, such as groundwater, drinking water sources, or industrial wastewater. During wastewater treatment, the biofilm system composed of colonies (mainly sulfur-oxidizing and denitrifying bacteria) is extremely sensitive to hydraulic disturbances. Excessive fluctuations in the filter level can cause biofilm detachment, damaging the filter's denitrification function and leading to secondary pollution. Therefore, sulfur autotrophic filters require a high-precision level control strategy, with level fluctuations limited to ±3 cm.
[0003] Conventional liquid level control systems often employ PID control, adjusting the control quantity based on proportional, integral, and derivative parameters. This results in a lag in PID control, failing to respond promptly to instantaneous fluctuations in water flow, leading to level fluctuations exceeding permissible limits. Furthermore, PID control causes excessively frequent actuation of the regulating valve, rapidly reducing its lifespan and causing frequent malfunctions. This not only increases equipment maintenance costs but also disrupts the normal operation of the autotrophic sulfur filter due to frequent downtime for repairs, reducing wastewater treatment efficiency. Summary of the Invention
[0004] To address the technical problems of delayed response to instantaneous flow fluctuations and excessively frequent valve actuation in existing technologies, this application provides a self-learning liquid level control method, which includes: The real-time liquid level of the filter bed and the real-time flow rate at the filter bed inlet are periodically acquired. When the real-time liquid level is not within the stable range, search the valve opening database for a preset valve opening that matches the current real-time flow rate. If the valve opening database contains a preset valve opening that matches the real-time flow rate, then the regulating valve at the filter outlet is set to the corresponding preset valve opening, and the real-time liquid level is continuously acquired during the regulation cycle to determine whether the real-time liquid level meets the stability requirements. If there is no preset valve opening in the valve opening database that matches the real-time flow rate, or if the real-time liquid level does not meet the stability requirements, the valve opening of the regulating valve is changed according to the preset adjustment rules until the real-time liquid level meets the stability requirements, and the current valve opening and real-time flow rate are recorded in the valve opening database.
[0005] In some embodiments, the valve opening database includes multiple instantaneous flow ranges, each instantaneous flow range corresponding to a preset valve opening. When the real-time flow is within an instantaneous flow range, the preset valve opening corresponding to that instantaneous flow range is the preset valve opening that matches the real-time flow.
[0006] In some embodiments, the stability requirement is that the real-time liquid level is within a stable range after an adjustment period.
[0007] In some embodiments, the preset adjustment rule is: When the real-time liquid level is within the range of increasing or decreasing the slow adjustment opening, the valve opening of the regulating valve is gradually increased or decreased by a slow adjustment amplitude until the real-time liquid level stabilizes within the stable range. When the real-time liquid level is within the range of increasing or decreasing fast adjustment opening, the valve opening of the regulating valve is gradually increased or decreased by the fast adjustment amplitude until the real-time liquid level drops to the range of increasing or decreasing slow adjustment opening. Then, the valve opening of the regulating valve is gradually increased or decreased by the slow adjustment amplitude until the real-time liquid level stabilizes within the stable range.
[0008] In some embodiments, the adjustment period includes a slow adjustment period and a fast adjustment period.
[0009] In some embodiments, when there is no preset valve opening in the valve opening database that matches the real-time flow rate, or when the real-time liquid level does not meet the stability requirements, the following steps are performed: Obtain the initial valve opening and corresponding initial flow rate of the regulating valve; Calculate the absolute difference between the initial flow and the real-time flow, i.e., the real-time flow difference; Calculate the ratio of the real-time flow difference to the initial flow, and increase or decrease the valve opening according to this ratio; During the adjustment cycle, the real-time liquid level of the filter bed is continuously acquired. After the adjustment cycle, it is determined whether the real-time liquid level meets the stability requirements. If so, the current valve opening is kept unchanged and the current valve opening is stored in the valve opening database. If not, the valve opening of the regulating valve is changed according to the above-mentioned preset adjustment rules until the real-time liquid level meets the stability requirements, and the current valve opening is recorded in the valve opening database.
[0010] In some embodiments, the adjustment period is calculated through the following steps: Calculate the absolute difference between the real-time liquid level and the upper limit of the stable range or the lower limit of the stable range, i.e., the liquid level adjustment height, and calculate the liquid level adjustment volume based on the liquid level adjustment height; The theoretical adjustment time is calculated based on the liquid level adjustment volume and the real-time flow difference, and is used as the adjustment cycle.
[0011] The above method rapidly adjusts the valve opening based on real-time flow using a valve opening database, improving the response speed of the control valve. Simultaneously, when the database does not contain a preset valve opening corresponding to the real-time flow, different adjustment strategies are adopted based on the deviation of the real-time liquid level from the stable range. This reduces the number of control valve operations and allows for rapid liquid level adjustment when the deviation is significant, achieving precise control of the valve opening. Once a suitable valve opening is obtained, it is stored in the valve opening database, enabling rapid control of the control valve the next time the same flow occurs. This achieves self-learning adjustment of the valve opening, obtaining a suitable control valve opening with fewer adjustments, thereby reducing the operating frequency of the control valve and extending its service life.
[0012] This application also provides a self-learning liquid level control system, including: A level sensor is used to measure the real-time level of the filter bed. A regulating valve is installed at the outlet of the filter tank to regulate the flow rate at the outlet of the filter tank. A flow sensor is used to measure the real-time flow rate at the inlet of the filter bed; The controller compares the real-time liquid level with a stable range. When the real-time liquid level is within the stable range, the opening of the regulating valve is not adjusted. When the real-time liquid level is not within the stable range, the opening of the regulating valve is adjusted using the above method.
[0013] The system adopts the above-mentioned self-learning liquid level control method, which can quickly adjust the liquid level of the filter bed according to the real-time flow and real-time liquid level through the valve opening database. While ensuring the control accuracy of the liquid level of the filter bed, it reduces the number of times the regulating valve is activated and extends the service life of the regulating valve.
[0014] The technical effects and advantages of this invention are as follows: First, the valve opening is matched to the real-time flow rate using a valve opening database. This allows for rapid adjustment of the valve opening based on the database when the filter tank liquid level deviates from the stable range, quickly stabilizing the liquid level. When the database does not contain a preset valve opening corresponding to the real-time flow rate, different adjustment strategies are adopted based on the degree of deviation between the real-time liquid level and the stable range. This reduces the number of valve actions and allows for rapid liquid level adjustment when the deviation is significant, achieving precise control of the valve opening. After obtaining a suitable valve opening, it is stored in the valve opening database, enabling rapid control of the valve when the same flow rate occurs again, achieving self-learning adjustment of the valve opening. The adjustment strategy adopted in this application can obtain a stable valve opening with fewer adjustments, thereby reducing the operating frequency of the valve and extending its service life. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the overall structure of the system provided by the present invention.
[0016] Figure 2 This is a flowchart of the self-learning liquid level control method for opening degree according to the present invention.
[0017] Figure 3 This is a schematic diagram of the preset adjustment rules for the self-learning liquid level control method of the present invention.
[0018] The attached diagram is labeled as follows: 1. Liquid level sensor; 2. Flow sensor; 3. Control valve; 4. Controller. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] Example 1 refer to Figure 1 This invention provides a self-learning liquid level control system, specifically including a liquid level sensor 1, a flow sensor 2, a regulating valve 3, and a controller 4. Liquid level sensor 1 is used to periodically acquire the real-time liquid level of the filter bed. During routine monitoring, low-frequency sampling can be used, for example, sampling once every 40 seconds, to balance energy consumption and the need for real-time monitoring. When the real-time liquid level is detected to be outside the stable range, the sampling frequency is increased, for example, sampling once every 20 ms, to coordinate with controller 4 for rapid adjustment of the liquid level.
[0021] Flow sensor 2 is installed at the inlet of the filter bed to measure the real-time flow rate at the inlet of the filter bed.
[0022] The regulating valve 3 is located at the outlet of the filter tank and is used to regulate the flow rate at the outlet.
[0023] The controller 4 is used to control the opening of the regulating valve 3 according to the real-time liquid level and real-time flow of the filter tank, so that the real-time liquid level is within a stable range.
[0024] The liquid level in the sulfur autotrophic filter needs to be maintained within a stable range during daily operation. Fluctuations in the liquid level must not exceed this range, otherwise it will affect the biofilm. When the real-time liquid level deviates from the stable range, the adjustment program needs to be activated to adjust the opening of the regulating valve 3 to stabilize the liquid level in the filter.
[0025] Controller 4 compares the real-time liquid level with the stable range. When the real-time liquid level is within the stable range, the opening of regulating valve 3 is not adjusted. When the real-time liquid level is not within the stable range, the opening of regulating valve 3 is adjusted using a self-learning liquid level control method, referencing... Figure 2 This includes the following steps: S1. Periodically obtain the real-time liquid level of the filter bed and the real-time flow rate of the filter bed inlet. S2. When the real-time liquid level is not within the stable range, search the valve opening database for a preset valve opening that matches the current real-time flow rate. S3. If there is a preset valve opening in the valve opening database that matches the real-time flow, then set the regulating valve 3 at the filter outlet to the corresponding preset valve opening, continuously acquire the real-time liquid level within the regulation cycle, and determine whether the real-time liquid level meets the stability requirements. S4. If there is no preset valve opening in the valve opening database that matches the real-time flow rate, or if the real-time liquid level does not meet the stability requirements, then change the valve opening of the regulating valve 3 according to the preset adjustment rules until the real-time liquid level meets the stability requirements, and record the current valve opening and real-time flow rate in the valve opening database.
[0026] When the real-time liquid level in the filter bed deviates from the stable range, the system first searches the valve opening database for a preset valve opening that matches the real-time flow rate. If such a valve opening exists, the opening of regulating valve 3 is set to the matching preset valve opening, thereby achieving rapid and accurate adjustment of the filter bed liquid level. Specifically, the valve opening database includes multiple different instantaneous flow ranges, each corresponding to a preset valve opening. Each preset valve opening is obtained through an opening self-learning process. The following table shows a portion of the valve opening database. For example, when the real-time flow rate is 206.5 m³ / h, the valve opening of regulating valve 3 is set to 22.2%.
[0027] Instantaneous flow range ID <![CDATA[Instantaneous flow rate lower limit m 3 / h]]> <![CDATA[Instantaneous flow rate upper limit m 3 / h]]> Preset valve opening % Instantaneous flow range 1 201.00 205.50 19.2 Instantaneous flow range 2 205.50 210.00 22.2 Instantaneous flow range 3 210.00 214.50 23.4 Instantaneous flow range 4 214.50 219.00 Null (empty) Instantaneous flow range 5 219.00 223.50 25.2% refer to Figure 3 When there is no preset valve opening in the valve opening database that matches the real-time flow, the opening of regulating valve 3 needs to be automatically adjusted according to the preset adjustment rules to find a valve opening that matches the real-time flow. This includes the following steps: When the liquid level exceeds the upper limit of the stable range but is lower than the upper limit of the slow adjustment increase range (slow adjustment opening increase range): S411. Gradually increase the valve opening of regulating valve 3 with a slow adjustment range; S412. After the slow adjustment cycle, determine whether the real-time liquid level has dropped. If so, maintain the current valve opening until the real-time liquid level drops to a stable range. Otherwise, return to step S411. S413. When the real-time liquid level drops to within the stable range, gradually reduce the valve opening of regulating valve 3 with a slow adjustment range. S414. After the slow adjustment cycle, determine whether the real-time liquid level is stable. If so, maintain the current valve opening; otherwise, return to step S413.
[0028] When the liquid level exceeds the upper limit of the slow adjustment increase (the range of the fast adjustment increase): S421. Gradually increase the valve opening of regulating valve 3 with a fast adjustment range; S422. After the fast adjustment cycle, determine whether the real-time liquid level has dropped. If so, maintain the current valve opening until the real-time liquid level drops to a stable range. Otherwise, return to step S421. S423. Once the real-time liquid level drops to within the stable range, proceed to step S413.
[0029] When the liquid level is below the lower limit of the stable range and above the lower limit of the slow adjustment reduction range (slow adjustment reduction range): S431. Gradually reduce the valve opening of regulating valve 3 with a slow adjustment range; S432. After the slow adjustment cycle, determine whether the real-time liquid level has risen. If so, maintain the current valve opening until the real-time liquid level rises to the stable range. Otherwise, return to step S431. S433. When the real-time liquid level rises to the stable range, gradually increase the valve opening of regulating valve 3 with a slow adjustment range. S434. After the slow adjustment cycle, determine whether the real-time liquid level is stable. If so, maintain the current valve opening; otherwise, return to step S433.
[0030] When the liquid level is below the lower limit of the slow adjustment reduction (the range of the fast adjustment reduction): S441. Gradually reduce the valve opening of regulating valve 3 with a fast adjustment range; S442. After the fast adjustment cycle, determine whether the real-time liquid level has risen. If so, maintain the current valve opening until the real-time liquid level rises to the stable range. Otherwise, return to step S441. S443. Once the real-time liquid level rises to a stable range, proceed to step S433.
[0031] Specifically, in the aforementioned preset adjustment rules, the slow adjustment amplitude can be set to 0.3% of the total valve opening (regulating valve 3 is fully open), and the corresponding slow adjustment period can be set to 8s. The fast adjustment amplitude can be set to 0.9% of the total valve opening, and the corresponding fast adjustment period can be set to 12s.
[0032] Specifically, the stability requirement is that the real-time liquid level in the filter tank should be within the stable range during the stabilization period. Generally, the stabilization period can be set to 200~280s. If the real-time liquid level remains within the stable range during the stabilization period, it indicates that the opening of regulating valve 3 is well matched with the real-time flow rate.
[0033] Specifically, the adjustment period in step S3 includes the slow adjustment period and the fast adjustment period described in the preset adjustment rules above.
[0034] Through the above steps, different valve opening adjustment strategies are adopted based on the degree of deviation between the real-time liquid level and the stable range. When the real-time liquid level deviates significantly from the stable range, a larger valve opening adjustment scale is used to quickly change the liquid level in the filter bed and bring it back to the stable range. When the real-time liquid level deviates only slightly from the stable range, a smaller valve opening adjustment scale is used to fine-tune the liquid level in the filter bed, preventing over-adjustment of the valve opening and thus quickly finding the valve opening that matches the current real-time flow rate.
[0035] Furthermore, the regulating valve 3 will age continuously during use, which may cause the preset valve opening in the valve opening database to be unable to keep the filter tank liquid level within a stable range. Therefore, after the preset valve opening found in the valve opening database is assigned to the regulating valve 3, the real-time liquid level of the filter tank can still be monitored to determine whether the regulating valve 3 can keep the filter tank liquid level within a stable range under the preset valve opening. If not, the opening of the regulating valve 3 still needs to be adjusted, and the adjusted valve opening is stored in the corresponding instantaneous flow range to overwrite the original preset valve opening. Thus, the valve opening database is modified according to the actual control effect of the regulating valve 3.
[0036] The method provided in this application first matches the valve opening to a valve opening database based on the real-time flow rate. This allows for rapid adjustment of the valve opening according to the database when the filter tank liquid level deviates from the stable range, quickly stabilizing the liquid level. When the database does not contain a preset valve opening corresponding to the real-time flow rate, different adjustment strategies are adopted based on the degree of deviation between the real-time liquid level and the stable range. This reduces the number of operations required for the regulating valve 3 and allows for rapid adjustment of the liquid level when the deviation is significant, achieving precise control of the regulating valve 3's opening. After obtaining a suitable valve opening, it is stored in the valve opening database, enabling rapid control of the regulating valve 3 when the same flow rate occurs again, achieving self-learning adjustment of the valve opening. The adjustment strategy employed in this application can obtain a stable regulating valve 3 opening with fewer adjustments, thereby reducing the operating frequency of the regulating valve 3 and extending its service life.
[0037] Example 2 In practical applications, the inlet flow rate of the filter bed is not in a stable state, but fluctuates to a certain extent. Furthermore, the scale of the filter bed varies from project to project, and the specifications of the inlet and regulating valve 3 are different. This makes it difficult to achieve the desired effect by using a fixed adjustment cycle (slow adjustment cycle and fast adjustment cycle) and a stabilization cycle to determine whether the liquid level meets the stability requirements.
[0038] In step S4, if there is no preset valve opening in the valve opening database that matches the real-time flow rate, or if the real-time liquid level does not meet the stability requirements, then the following steps are performed: S51. Obtain the initial valve opening degree and corresponding initial flow rate of the regulating valve 3; After the system is put into use and debugged, the liquid level in the filter tank is relatively stable for a period of time. Record the flow rate at the inlet and the opening degree of regulating valve 3 at this time as the initial valve opening degree and initial flow rate.
[0039] S52. Calculate the absolute difference between the initial flow and the real-time flow, i.e., the real-time flow difference; S53. Calculate the ratio of the real-time flow difference to the initial flow, and increase or decrease the valve opening according to this ratio; S54. Calculate the absolute difference between the real-time liquid level and the upper limit of the stable interval or the lower limit of the stable interval, i.e., the liquid level adjustment height, and calculate the liquid level adjustment volume based on the liquid level adjustment height. S55. Calculate the theoretical adjustment time based on the difference between the liquid level adjustment volume and the real-time flow rate, and use it as the adjustment cycle (slow adjustment cycle or fast adjustment cycle). S56. During the adjustment cycle, continuously acquire the real-time liquid level of the filter tank. After the adjustment cycle, determine whether the real-time liquid level meets the stability requirements. If yes, keep the current valve opening unchanged and store the current valve opening in the valve opening database. If no, change the valve opening of the regulating valve 3 according to the above-mentioned preset adjustment rules.
[0040] When the real-time flow difference is large, the liquid level in the filter bed changes rapidly. Therefore, it is necessary to quickly adjust the opening of valve 3 to stabilize the liquid level. When the real-time flow difference is small, the liquid level in the filter bed changes slowly. Therefore, the opening of valve 3 can be adjusted slightly to keep the liquid level stable.
[0041] By calculating the real-time flow difference to adjust the valve opening, the valve opening can be quickly adjusted to the appropriate size, further reducing the number of valve operations. Simultaneously, by calculating the liquid level adjustment height and volume in real time, the adjustment time can be determined more accurately, making the valve opening adjustment more scientific and rational. Furthermore, this method has strong adaptability and flexibility, automatically adjusting the adjustment strategy according to different actual operating conditions and flow changes, ensuring stable liquid level control under various complex conditions.
[0042] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A self-learning liquid level control method for liquid level opening, characterized in that, Includes the following steps: The real-time liquid level of the filter bed and the real-time flow rate at the filter bed inlet are periodically acquired. When the real-time liquid level is not within the stable range, search the valve opening database for a preset valve opening that matches the current real-time flow rate. If the valve opening database contains a preset valve opening that matches the real-time flow rate, then the regulating valve at the filter outlet is set to the corresponding preset valve opening, and the real-time liquid level is continuously acquired during the regulation cycle to determine whether the real-time liquid level meets the stability requirements. If there is no preset valve opening in the valve opening database that matches the real-time flow rate, or if the real-time liquid level does not meet the stability requirements, the valve opening of the regulating valve is changed according to the preset adjustment rules until the real-time liquid level meets the stability requirements, and the current valve opening and real-time flow rate are recorded in the valve opening database.
2. The method according to claim 1, characterized in that, The valve opening database includes multiple instantaneous flow ranges, each of which corresponds to a preset valve opening. When the real-time flow rate is within an instantaneous flow rate range, the preset valve opening corresponding to that instantaneous flow rate range is the preset valve opening that matches the real-time flow rate.
3. The method according to claim 1, characterized in that, The stability requirement is that the real-time liquid level is within the stable range after the adjustment cycle.
4. The method according to claim 1, characterized in that, The preset adjustment rule is as follows: When the real-time liquid level is within the range of increasing or decreasing the slow adjustment opening, the valve opening of the regulating valve is gradually increased or decreased by a slow adjustment amplitude until the real-time liquid level stabilizes within the stable range. When the real-time liquid level is within the range of increasing or decreasing fast adjustment opening, the valve opening of the regulating valve is gradually increased or decreased by the fast adjustment amplitude until the real-time liquid level drops to the range of increasing or decreasing slow adjustment opening. Then, the valve opening of the regulating valve is gradually increased or decreased by the slow adjustment amplitude until the real-time liquid level stabilizes within the stable range.
5. The method according to claim 4, characterized in that, The adjustment cycle includes a slow adjustment cycle and a fast adjustment cycle.
6. The method according to claim 1, characterized in that, When the valve opening database does not contain a preset valve opening that matches the real-time flow rate, or when the real-time liquid level does not meet the stability requirements, the following steps are performed: Obtain the initial valve opening and corresponding initial flow rate of the regulating valve; Calculate the absolute difference between the initial flow and the real-time flow, i.e., the real-time flow difference; Calculate the ratio of the real-time flow difference to the initial flow, and increase or decrease the valve opening according to this ratio; During the adjustment cycle, the real-time liquid level of the filter bed is continuously acquired. After the adjustment cycle, it is determined whether the real-time liquid level meets the stability requirements. If so, the current valve opening is kept unchanged and the current valve opening is stored in the valve opening database. If not, the valve opening of the regulating valve is changed according to the above-mentioned preset adjustment rules until the real-time liquid level meets the stability requirements, and the current valve opening is recorded in the valve opening database.
7. The method according to claim 6, characterized in that, The adjustment period is calculated through the following steps: Calculate the absolute difference between the real-time liquid level and the upper limit of the stable range or the lower limit of the stable range, i.e., the liquid level adjustment height, and calculate the liquid level adjustment volume based on the liquid level adjustment height; The theoretical adjustment time is calculated based on the liquid level adjustment volume and the real-time flow difference, and is used as the adjustment cycle.
8. A self-learning liquid level control system for liquid level opening, characterized in that, include: A level sensor is used to measure the real-time level of the filter bed. A regulating valve is installed at the outlet of the filter tank to regulate the flow rate at the outlet of the filter tank. A flow sensor is used to measure the real-time flow rate at the inlet of the filter bed; The controller is used to compare the real-time liquid level with a stable range. When the real-time liquid level is within the stable range, the opening of the regulating valve is not adjusted. When the real-time liquid level is not within the stable range, the opening of the regulating valve is adjusted by the method of any one of claims 1 to 7.