Sewage treatment plant tail water parallel pipeline flow interval self-stabilization control system and method

Abstract

The invention discloses a sewage treatment plant tail water parallel pipeline flow interval self-stabilization control system and method. When tail water of a traditional sewage treatment plant is discharged or recycled, the tail water needs to be distributed to a plurality of water consumption points. Electric butterfly valves are installed on two parallel pipelines of a branch 1 and a branch 2, and a flow metering device is installed at the water source flow position and used for monitoring the total flow Q of a water source; the automatic control system is used for receiving the flow data and dynamically adjusting the opening degree of the valve; the local head loss coefficient is changed by dynamically adjusting the opening degree of the electric butterfly valve, so that the total head loss of the parallel pipelines is equal, and the target branch flow is kept stable when the total flow changes. According to the method, a high-precision flowmeter is not needed, only existing flow monitoring facilities and valve adjustment of the sewage treatment plant need to be combined, the valve characteristic relation is directly utilized, the system complexity is reduced, and the control logic is simplified.

Description

Technical Field

[0002] This invention belongs to the field of wastewater treatment plant effluent flow distribution technology, specifically relating to a self-stabilizing control system and method for the flow range of parallel pipelines for wastewater treatment plant effluent. Background Technology

[0003] When traditional wastewater treatment plants discharge or reuse effluent, it is often necessary to distribute it to multiple water usage points (or outlets). Due to differences in water pressure, length, pipe diameter, and elevation among the branch pipes, the traditional distribution weir method can distribute the effluent proportionally, but it cannot control the flow variation range at any single water usage point, easily leading to insufficient water flow or overflow at that point. While existing technologies that use branch flow meters to feed back to the automatic control system to adjust valve openings can achieve constant flow, they have the following drawbacks: 1) High cost: It requires high-precision flow meters and complex control systems, resulting in a large investment; 2) Valve wear: Frequent adjustment of valve opening leads to mechanical wear and shortens service life; 3) Redundant control: When only flow range control is required in tailwater reuse scenarios (such as constructed wetlands), high-precision adjustment is not necessary.

[0004] Therefore, there is an urgent need for a low-cost, highly reliable solution that is suitable for imprecise flow control. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a self-stabilizing control system and method for the flow range of parallel pipelines for wastewater treatment plant effluent, which achieves stable distribution of flow at water usage points by dynamically adjusting valve opening.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A self-stabilizing control system for the flow range of parallel pipelines for effluent from a wastewater treatment plant, specifically comprising: The water source flow is divided into two parallel pipelines, branch 1 and branch 2, at water distribution point 0; An electric butterfly valve F1 is installed on parallel branch 1, and an electric butterfly valve F2 is installed on parallel branch 2. A flow metering device is installed at the water source flow point to monitor the total water flow Q. The automatic control system is used to receive flow data and dynamically adjust the valve opening.

[0007] Furthermore, electric butterfly valves are used to adjust the local head loss coefficient.

[0008] Furthermore, the flow metering device adopts a Parshall flume at the end of a wastewater treatment plant.

[0009] Furthermore, the operating method is as follows: System installation: Install electric butterfly valves F1 and F2 on parallel branch 1 and branch 2 respectively, and connect them to the automatic control system; Parameter initialization: Input pipeline parameters, target flow rate Q 1 and the relationship between valve characteristics; Threshold setting: Set the total traffic fluctuation threshold; Real-time adjustment: When the total water flow Q fluctuates beyond the set threshold, the automatic control system adjusts the opening of valve F2 to achieve [the desired effect]. Q 1 Stablize.

[0010] A self-stabilizing control method for the flow range of parallel pipelines for effluent from a wastewater treatment plant is as follows: By dynamically adjusting the opening of the electric butterfly valve, the local head loss coefficient is changed, making the total head loss of parallel pipelines equal, thereby maintaining the stability of the target branch flow when the total flow changes. The steps are as follows: 1) Set target flow rate: Fixed flow rate at water point 1 Q 1 It is a constant value; 2) Monitor total flow: Monitor the total water flow in real time using the flow metering device at the end of the sewage treatment plant. Q And feed it back to the automatic control system; 3) Set the valve opening degree; 4) Dynamic adjustment.

[0011] Furthermore, step 3) specifically includes: Based on the head balance equation of parallel pipelines and combined with valve characteristic relationships, the local head loss coefficient is... g 2 Convert it to the corresponding electric butterfly valve opening degree and set it in the automatic control system.

[0012] Furthermore, step 4) specifically includes: When the total flow of water source Q When the fluctuation exceeds the set value, the automatic control system automatically adjusts the opening of the electric butterfly valve F2 to change the local head loss of branch 2, ensuring that the two parallel pipelines meet the condition of equal total head loss, thus guaranteeing the flow rate of branch 1. Q 1 Stablize.

[0013] Furthermore, the head balance is disclosed as follows: Formula 1): Formula 2): In the formula: P —Water point pressure, m; H—Pipeline elevation, in meters; L — Pipe length, in meters; D —Pipe diameter, in meters; Q —Pipe flow rate, m 3 / s; α —Specific resistance; g —Acceleration due to gravity, m / s² 2 ; u —Pipe flow velocity, m / s; g —Local head resistance coefficient.

[0014] The beneficial effects of this invention are: 1) This invention does not require a high-precision flow meter. It only needs to be combined with the existing flow monitoring facilities and valve regulation of the sewage treatment plant. It directly uses the valve characteristic relationship (opening degree-ζ relationship) to replace the traditional feedback closed loop, which reduces the system complexity and simplifies the control logic. 2) This invention only requires adjusting the valve opening when the total flow fluctuation exceeds the threshold, thereby reducing the frequency of valve operation, reducing mechanical wear, extending equipment life, and saving energy and reducing consumption. Attached Figure Description

[0015] Figure 1 This is the system control logic diagram of the present invention; Figure 2 This is a graph showing the relationship between the local head loss coefficient ζ and the valve opening degree. Detailed Implementation

[0017] The present invention will now be described in detail with reference to specific embodiments.

[0018] This invention provides a self-stabilizing control system and method for the flow range of parallel pipelines for wastewater treatment plant effluent. It is applicable to the stable distribution of flow at water points by dynamically adjusting the valve opening when the total flow of wastewater treatment plant effluent fluctuates. It is particularly suitable for the non-precise but range-controlled flow distribution needs in effluent reuse scenarios (such as constructed wetlands).

[0019] like Figure 1 As shown, the water source flow is divided into two parallel pipelines, branch 1 and branch 2, at water distribution point 0; an electric butterfly valve F1 is installed on parallel branch 1, and an electric butterfly valve F2 is installed on parallel branch 2. The electric butterfly valves are used to adjust the local head loss coefficient. A flow metering device is installed at the water source flow point to monitor the total water flow Q. In this embodiment, the flow metering device is a Parshall flume at the end of the sewage treatment plant. The automatic control system is used to receive flow data and dynamically adjust the valve opening. The automatic control system is the sewage treatment plant's internal automatic control system.

[0020] The operation method of the self-stabilizing control system for the flow range of parallel pipelines for wastewater treatment plant effluent is as follows: System installation: Install electric butterfly valves F1 (fixed opening) and F2 (adjustable opening) on ​​parallel branch 1 and branch 2 respectively, and connect them to the automatic control system; Parameter initialization: Input pipeline parameters (L, D, α), target flow rate Q 1 and the relationship between valve characteristics; Threshold setting: Set the total flow fluctuation threshold. In this example, it is set to ±5% of the wastewater treatment plant's design capacity. Real-time adjustment: When the total water flow Q fluctuates beyond the set threshold, the automatic control system adjusts the opening of valve F2 to achieve [the desired effect]. Q 1 Stablize.

[0021] The present invention provides a self-stabilizing control method for the flow range of parallel pipelines in wastewater treatment plants, specifically as follows: By dynamically adjusting the opening of the electric butterfly valve, the local head loss coefficient is changed, making the total head loss of parallel pipelines equal, thereby maintaining the stability of the target branch flow when the total flow changes; the steps are as follows: 1) Set target flow rate: Fixed flow rate at water point 1 Q 1 It is a constant value; 2) Monitor total flow: Monitor the total water flow in real time using the flow metering device at the end of the sewage treatment plant. Q And feed it back to the automatic control system; 3) Setting the valve opening: Based on the head balance equation of parallel pipelines and combined with the valve characteristic relationship, the local head loss coefficient is set. g 2 Convert to the corresponding electric butterfly valve opening degree and set it in the automatic control system; 4) Dynamic adjustment: When the total flow rate of the water source... Q When the fluctuation exceeds the set value, the automatic control system automatically adjusts the opening of the electric butterfly valve F2 to change the local head loss of branch 2, ensuring that the two parallel pipelines meet the condition of equal total head loss, thus guaranteeing the flow rate of branch 1. Q 1 Stablize.

[0022] The head balance is as follows: Formula 1): Formula 2): In the formula: P —Water point pressure, m; H —Pipeline elevation, in meters; L — Pipe length, in meters; D —Pipe diameter, in meters; Q —Pipe flow rate, m 3 / s; α —Specific resistance; g —Acceleration due to gravity, m / s² 2 ; u —Pipe flow velocity, m / s; g —Local head resistance coefficient.

[0023] In the above formula, subscript 1 represents the corresponding parameter of branch 1, and subscript 2 represents the corresponding parameter of branch 2.

[0024] When the total flow of water source Q When the fluctuation exceeds the set value of the design scale, the automatic control system calculates the flow rate of branch 1 according to formula 2). Q 1 The local head loss required for branch 2 remains unchanged. g 2, and based on Figure 2 find out g The opening degree of the butterfly valve corresponding to 2 is used to adjust the opening degree of the electric butterfly valve F2.

[0025] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] The content of this invention is not limited to the embodiments listed. Any equivalent modifications made by those skilled in the art to the technical solutions of this invention by reading this specification are covered by the claims of this invention.

Claims

1. A self-stabilizing control system for the flow range of parallel pipelines for effluent from a wastewater treatment plant, characterized in that: The water source flow is divided into two parallel pipelines, branch 1 and branch 2, at water distribution point 0; An electric butterfly valve F1 is installed on parallel branch 1, and an electric butterfly valve F2 is installed on parallel branch 2. A flow metering device is installed at the water source flow point to monitor the total water flow Q. The automatic control system is used to receive flow data and dynamically adjust the valve opening.

2. The self-stabilizing control system for the flow range of parallel pipelines for wastewater treatment plant effluent according to claim 1, characterized in that: Electric butterfly valves are used to adjust the local head loss coefficient.

3. The self-stabilizing control system for the flow range of parallel pipelines for wastewater treatment plant effluent according to claim 2, characterized in that: The flow metering device is a Parshall flume at the end of a wastewater treatment plant.

4. The self-stabilizing control system for the flow range of parallel pipelines for wastewater treatment plant effluent according to claim 3, characterized in that: The operation method is as follows: System installation: Install electric butterfly valves F1 and F2 on parallel branch 1 and branch 2 respectively, and connect them to the automatic control system; Parameter initialization: Input pipeline parameters, target flow rate Q 1 and the relationship between valve characteristics; Threshold setting: Set the total traffic fluctuation threshold; Real-time adjustment: When the total water flow Q fluctuates beyond the set threshold, the automatic control system adjusts the opening of valve F2 to achieve [the desired effect]. Q 1 Stablize.

5. A method for self-stabilizing control of flow range in parallel pipelines of wastewater treatment plant effluent, characterized in that: By dynamically adjusting the opening of the electric butterfly valve, the local head loss coefficient is changed, so that the total head loss of the parallel pipelines is equal, thereby maintaining the stability of the target branch flow when the total flow changes.

6. The self-stabilizing control method for the flow range of parallel pipelines for wastewater treatment plant effluent according to claim 5, characterized in that: The specific steps are as follows: 1) Set target flow rate: Fixed flow rate at water point 1 Q 1 It is a constant value; 2) Monitor total flow: Monitor the total water flow in real time using the flow metering device at the end of the sewage treatment plant. Q And feed it back to the automatic control system; 3) Set the valve opening; 4) Dynamic adjustment.

7. A self-stabilizing control system for the flow range of parallel pipelines for wastewater treatment plant effluent according to claim 6, characterized in that: Step 3) specifically refers to: Based on the head balance equation of parallel pipelines and combined with valve characteristic relationships, the local head loss coefficient is... ζ 2 Convert it to the corresponding electric butterfly valve opening degree and set it in the automatic control system.

8. A self-stabilizing control system for the flow range of parallel pipelines for wastewater treatment plant effluent according to claim 7, characterized in that: Step 4) specifically refers to: When the total flow of water source Q When the fluctuation exceeds the set value, the automatic control system automatically adjusts the opening of the electric butterfly valve F2 to change the local head loss of branch 2, ensuring that the two parallel pipelines meet the condition of equal total head loss, thus guaranteeing the flow rate of branch 1. Q 1 Stablize.

9. A self-stabilizing control system for the flow range of parallel pipelines for wastewater treatment plant effluent according to claim 8, characterized in that: The head balance is as follows: Formula 1): Formula 2): In the formula: P —Water point pressure, m; H —Pipeline elevation, in meters; L — Pipe length, in meters; D —Pipe diameter, in meters; Q —Pipe flow rate, m 3 / s; α —Specific resistance; g —Acceleration due to gravity, m / s² 2 ; υ —Pipe flow velocity, m / s; ζ —Local head resistance coefficient.

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