A method and system for controlling the flow of water in a horizontal flow sedimentation basin

Abstract

The present application relates to the field of environmental protection technology, especially to a kind of horizontal flow sedimentation tank water distribution flow control method and system, including, the historical flow value interval of inlet water main is divided into n sections, and n basic flow points are used as node in each flow interval section;"flow-valve position" mapping table is established;When the set flow x of inlet water main is located between any two adjacent basic flow points, the initial set valve position of branch pipe regulating valve is calculated;Real-time acquisition each branch pipe actual flow, and the average flow of n branch pipes is calculated as the flow set value of branch pipe regulating valve;Each PI regulator is configured to output to the actuator of corresponding branch pipe regulating valve according to the corresponding branch pipe actual flow received and the flow set value of branch pipe regulating valve.The advantages of the present application are: ensure that the effluent of each horizontal flow sedimentation tank is evenly distributed, avoid local overload;Reduce the actual effluent flow deviation of each tank, balance the effluent of each tank, so that suspended solids are more fully precipitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental protection, and in particular to a flow control method and system for a horizontal flow sedimentation tank. BACKGROUND

[0002] In the turbid water treatment process of a certain plant, a horizontal flow sedimentation tank is arranged after a vortex flow well and is mainly used for secondary sedimentation and purification of water after primary sedimentation in the vortex flow well. The main treatment objects are suspended solids (mainly iron oxide particles) and industrial grease in the water. The sediment at the bottom of the tank is removed by a skimming and raking vehicle, and the floating oil on the surface of the tank is removed by an oil skimmer. However, in actual operation, the process has the following problems:

[0003] 1. Uneven water output:

[0004] The horizontal flow sedimentation tank adopts 5-tank parallel operation, but the actual water output of each tank is uneven, which causes excessive load of part of the tank and affects the overall treatment effect. In the original design, the horizontal flow tank has no flow detection element, and the water inflow can only be controlled by manually adjusting two manual water distribution valves of each tank. Due to the lack of accurate flow detection means, it is difficult to ensure that the water inflow of each water distribution valve and the 5 tanks is consistent.

[0005] 2. Equipment operation failure:

[0006] The skimming and raking vehicle frequently derails and tilts when the rake falls and scrapes mud, and even pulls the rail, which seriously affects the stability and service life of the equipment.

[0007] 3. Poor sedimentation effect:

[0008] Through sampling and testing of the water outlet of the horizontal flow sedimentation tank, it is found that the suspended solids index of the tank with excessive flow exceeds the standard, indicating that the sedimentation effect does not meet the expectation. Further inspection by draining the tank water shows that the sludge distribution at the bottom of the tank is extremely uneven, and the accumulation is too high. A large amount of suspended solids enters the subsequent water treatment process without sedimentation, causing excessive load of the subsequent water treatment equipment and even damage. SUMMARY

[0009] The purpose of the present application is to provide a flow control method and system for a horizontal flow sedimentation tank, which can quickly adjust the water inflow, make the treatment load of each tank the same, ensure the stable operation of the horizontal flow sedimentation tank process equipment, reduce the maintenance cost, and improve the water quality.

[0010] To achieve the above purpose, the present application realizes the following technical scheme:

[0011] A flow control method for a horizontal flow sedimentation tank, comprising:

[0012] S1, divide the water inlet main historical flow value interval into n segments, and take n basic flow points as nodes in each flow interval segment to form n+1 segments of broken lines;

[0013] S2, establish a "flow-valve position" mapping table according to the adjustment valve position data recorded at the n basic flow points;

[0014] S3, calculate the initial set valve position of the branch pipe adjustment valve when the water inlet main set flow x is located between any two adjacent basic flow points;

[0015] S4, use the initial set valve position of the branch pipe adjustment valve obtained in step S3 as the initial opening of the branch pipe adjustment valve, and put it into operation;

[0016] S5, real-time acquisition of each branch pipe actual flow, and calculation of the average flow of n branch pipes as the flow set value of the branch pipe adjustment valve;

[0017] S6, each PI regulator is configured to output to the corresponding branch pipe adjustment valve according to the received corresponding branch pipe actual flow and the flow set value of the branch pipe adjustment valve.

[0018] In S3, the initial set valve position of the branch pipe adjustment valve, the calculation formula is as follows:

[0019] ①;

[0020] ②;

[0021] In formula ①, represents the initial set valve position of the branch pipe adjustment valve, represents the water inlet main set flow, and is located between two adjacent basic flow points and , represents the basic flow point corresponding basic valve position, represents the basic flow point corresponding basic valve position.

[0022] In S5, the average flow of n branch pipes, the calculation formula is as follows:

[0023] ③;

[0024] In formula ③, represents the flow set value of the branch pipe adjustment valve, represents the actual flow of each branch pipe.

[0025] In S6, the actual flow of the corresponding branch pipe is less than the flow set value of the branch pipe regulating valve, the branch pipe regulating valve is opened; the actual flow of the corresponding branch pipe is greater than the flow set value of the branch pipe regulating valve, the branch pipe regulating valve is closed; the actual flow of the corresponding branch pipe is equal to the flow set value of the branch pipe regulating valve, the branch pipe regulating valve maintains the original valve position state.

[0026] A flow control system for water distribution of a horizontal flow sedimentation tank comprises a water distribution channel, a water suction well, a plurality of parallel horizontal flow sedimentation tanks, the water distribution channel being used for distributing water from a swirl flow well to be treated to each horizontal flow sedimentation tank, the water suction well being used for collecting effluent after sedimentation of the horizontal flow sedimentation tank, and further comprising branch pipes and regulating valves, each of the branch pipes being provided in the water distribution channel, one end of each of the branch pipes being connected with a water inlet main pipe, the water inlet main pipe being connected with a water distribution pipeline, each of the horizontal flow sedimentation tanks being supplied with water by a corresponding branch pipe, and each of the branch pipes being provided with a regulating valve.

[0027] Each of the branch pipes is further provided with a flow meter and a magnetic water filter, the flow meter being arranged at an input end of the regulating valve, and the magnetic water filter being arranged at an output end of the regulating valve.

[0028] Compared with the prior art, the flow control system for water distribution of the horizontal flow sedimentation tank has the following beneficial effects:

[0029] 1. By means of segmented flow control and optimization of initial settings of the branch pipe regulating valves, and taking the flow of each branch pipe as a controlled object to make PI closed loop compensation, the water discharge of each horizontal flow sedimentation tank in parallel operation is evenly distributed, and local overload is avoided; the opening degree of the corresponding branch pipe regulating valve is dynamically adjusted by using a PI regulator, the actual effluent flow deviation of each tank is further reduced, the water discharge of each tank is balanced, the suspended matter is more fully precipitated, and the effluent water quality is ensured to reach the standard;

[0030] 2. After uniform water distribution, the single tank load is stable, the water discharge of each tank is balanced, the sludge is uniformly deposited, the uneven force problem of the oil and sludge scraping vehicle is alleviated, the risks of derailment, body deflection and track damage are reduced, the downtime maintenance time caused by equipment failure is reduced, the turbid circulating water quality index is effectively improved, the operation load of the entire water treatment process equipment and facility is reduced, the operation stability is improved, and the operation cost is reduced;

[0031] 3. By accurately calculating the opening degree of each branch pipe regulating valve at the intermediate flow point, the continuity and accuracy of water distribution control are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a layout of the flow control system for water distribution of the horizontal flow sedimentation tank Figure 1 .

[0033] Figure 2 is a layout of the flow control system for water distribution of the horizontal flow sedimentation tank Figure 2 .

[0034] Figure 3 is a position diagram of the flow meter of the water distribution pipeline.

[0035] Figure 4 is the flow segmentation and valve position curve of the horizontal flow tank inlet main.

[0036] In the figure: 1, water distribution channel; 2, water suction well; 3, oil scraping and slag hanging car; 4, oil skimmer; 5, inlet main; 6, branch pipe; 7, horizontal flow sedimentation tank; 8, regulating valve; 9, flow meter; 10, magnetic water filter. DETAILED DESCRIPTION

[0037] The application will be described in detail below with reference to the accompanying drawings of the specification, but it should be pointed out that the implementation of the application is not limited to the following embodiments.

[0038] The following examples are implemented on the premise of the technical solution of the application, and detailed implementation methods and specific operation processes are given, but the protection scope of the application is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0039] Example 1:

[0040] See Figures 1-3 A horizontal flow sedimentation tank 7 water distribution flow control system, including water distribution channel 1, water suction well 2, branch pipe 6, regulating valve 8, 5 parallelly used horizontal flow sedimentation tanks 7, the water distribution channel 1 is used for distributing the vortex flow well water to be treated to each horizontal flow sedimentation tank 7, the water suction well 2 is used for collecting the effluent after the horizontal flow sedimentation tank 7 is deposited, 10 branch pipes 6 are arranged in the water distribution channel 1, one end of each branch pipe 6 is connected with the inlet main 5, the inlet main 5 is connected with the water distribution pipeline, each horizontal flow sedimentation tank 7 is supplied with water by two branch pipes 6, the water supply by two branch pipes can effectively improve the uniformity of the water flow of the single tank, avoid the turbulent water flow at the central part of the inlet end and the slow water flow at the peripheral part, and guarantee the deposition effect, a flow meter 9, a regulating valve 8 and a magnetic water filter 10 are arranged on each branch pipe 6, in order to avoid the interference of the flow meter 9 caused by the insufficient flow of the branch pipe 6 pipeline, the flow meter 9 is arranged on the ascending section of the branch pipe 6 pipeline, the flow meter 9 is located on the input end side of the regulating valve 8, the flow meter 9 is used for collecting the actual flow of the corresponding branch pipe 6 in real time, the magnetic water filter 10 is located on the output end side of the regulating valve 8, see Figure 3 .

[0041] A horizontal flow sedimentation tank 7 water distribution flow control method, in the original design, the horizontal flow tank water distribution pipeline has no flow detection element, the water inflow is controlled by manually adjusting two water distribution valves of each tank, the adjustment effect is roughly evaluated by observing the water level height of the overflow weir position of the horizontal flow tank outlet end, it is difficult to guarantee that the water inflow of each water distribution valve and the five tanks is consistent, after the transformation, the steps are as follows:

[0042] S1, each branch pipe 6 is equipped with a PI regulator, each PI regulator compares the actual flow of its branch pipe 6 with a common flow set value, calculates the deviation, and adjusts the opening of the regulating valve 8 on the branch pipe 6 according to the proportional and integral components of the deviation to eliminate the deviation, so that the actual flow of the corresponding branch pipe 6 is equal to the set value, comprising:

[0043] The historical flow value interval of the horizontal pool inlet pipe 5 is divided into 10 segments, and 10 basic flow points are taken as nodes in each flow interval segment, such as , forming an 11-segment polyline. , forming an 11-segment polyline.

[0044] S2, for each branch pipe 6, the valve position of the regulating valve 8 at the 10 basic flow points is recorded according to the opening data of the regulating valve 8, and a "flow-valve position" mapping table is established:

[0045] Using the flow of the inlet pipe 5 as a basis, the 11-segment polyline is searched as the initial set value SP of the 10 branch pipe 6 regulating valves 8 at each flow, and the set value is accumulated and optimized at this flow:

[0046] According to the actual operating conditions of the system, set the average of the minimum and maximum values of the inlet pipe 5 flow to set 10 basic flow points, and record the basic valve position of each regulating valve 8 at the 10 basic flow points according to the actual use on site.

[0047] S3, when the set flow x of the inlet pipe 5 is located between any two adjacent basic flow points and , the initial set valve position of the branch pipe 6 regulating valve 8 is calculated, and the calculation formula is as follows:

[0048] ①;

[0049] ②;

[0050] In formula ①, represents the initial set valve position of the branch pipe 6 regulating valve 8, represents the set flow of the inlet pipe 5, and is located between two adjacent basic flow points and , represents the basic valve position corresponding to the basic flow point , represents the basic valve position corresponding to the basic flow point ;

[0051] For example:

[0052] See Figure 4 , when the set flow of the inlet pipe 5 For 6000 m³ / h, the basic valve position corresponding to the basic flow point 6000 of branch pipe 6 regulating valve 8 is found from the table ; when the set flow of water inlet main pipe 5 is 6500 m³ / h, the basic valve position corresponding to the basic flow point 6500 m³ / h of branch pipe 6 regulating valve 8 is found from the table Then when the flow set of water inlet main pipe 5 is 6200 m³ / h, according to formula ①, we get:

[0053] .

[0054] Figure 4 The basic valve position corresponding to the basic flow point 6500 of branch pipe 6 regulating valve 8 = 12% and the basic valve position corresponding to the basic flow point 6000 of branch pipe 6 regulating valve 8 = 10%, the initial set valve position of branch pipe 6 regulating valve 8 The final calculation result is 10 + (12-10) / (6500-6000) x (6200-6000) = 10.8%.

[0055] S4, the initial set valve position of branch pipe 6 regulating valve 8 obtained in step S3 is taken as the initial opening of branch pipe 6 regulating valve 8, and put into operation;

[0056] S5, real-time collection of actual flow of each branch pipe 6 is carried out, and the average flow of 10 branch pipes 6 is calculated as the flow set value of branch pipe 6 regulating valve 8; the average flow of 10 branch pipes 6 is calculated according to the following formula:

[0057] ③;

[0058] In formula ③, represents the flow set value of branch pipe 6 regulating valve 8, represents the actual flow of each branch pipe 6;

[0059] The average flow of 10 branch pipe 6 distribution valves is calculated , as the flow set and PI control of the flow of each branch pipe 6, the valve set deviation ΔSP is calculated, the flow set value of branch pipe 6 can be calculated by the sum of the flow of each branch pipe 6 / 10, , the calculation error , if , it means that the flow of this branch pipe 6 is lower than the target value and the valve needs to be opened, if , it means that the flow of this branch pipe 6 is higher than the target value and the valve needs to be closed.

[0060] S6. Each PID controller is configured to output to the actuator of the corresponding branch pipe 6 regulating valve 8 based on the received actual flow rate of the corresponding branch pipe 6 and the flow rate setpoint of the branch pipe 6 regulating valve 8. If the actual flow rate of the corresponding branch pipe 6 is less than the flow rate setpoint of the branch pipe 6 regulating valve 8, the branch pipe 6 regulating valve 8 is opened wider; if the actual flow rate of the corresponding branch pipe 6 is greater than the flow rate setpoint of the branch pipe 6 regulating valve 8, the branch pipe 6 regulating valve 8 is closed less; if the actual flow rate of the corresponding branch pipe 6 is equal to the flow rate setpoint of the branch pipe 6 regulating valve 8, the branch pipe 6 regulating valve 8 maintains its original valve position.

[0061] The PI controller control process is as follows:

[0062] The proportional gain Kp is set so that when the flow rate of a certain branch pipe 6 deviates from the set value, the PI controller will immediately generate a valve adjustment action proportional to the magnitude of the deviation ΔSP, and quickly adjust the flow rate. The integral gain Ki is set to solve the residual small deviation that the proportional control cannot completely eliminate. If the flow rate of a certain branch pipe 6 is slightly lower than the set value for a long time, the integral term will continue to accumulate this small deviation and gradually open the valve until the flow rate accurately reaches the set value.

[0063] This invention achieves uniform effluent distribution in parallel-operated sedimentation tanks by segmented flow control and optimized initial settings of branch pipe regulating valves, followed by PI closed-loop compensation using the flow rate of each branch pipe as the controlled object, thus avoiding local overload. A PI controller dynamically adjusts the opening of the corresponding branch pipe regulating valves to further reduce the actual effluent flow deviation in each tank, balancing the effluent flow and ensuring more thorough sedimentation of suspended solids, guaranteeing that the effluent quality meets standards. After uniform water distribution, the load on each tank stabilizes, balancing the effluent flow and promoting uniform sludge deposition, mitigating uneven stress on the oil and sludge scraper, reducing the risk of derailment, vehicle skew, and track damage, and minimizing downtime for maintenance due to equipment failure. It effectively improves the turbidity and circulating water quality indicators, reduces the overall operating load of the water treatment process equipment, enhances operational stability, and lowers operating costs. By precisely calculating the opening of each branch pipe regulating valve at intermediate flow points, the continuity and accuracy of water distribution control are ensured.

Claims

1. A method for controlling the water distribution flow rate in a horizontal flow sedimentation tank, used for several horizontal flow sedimentation tanks operating in parallel, characterized in that, include: S1. Divide the historical flow value range of the main inlet pipe into n segments, and form n+1 broken lines within each flow range segment using n basic flow points as nodes. S2. Based on the valve position of the branch regulating valve recorded at n basic flow points according to the valve opening data, establish a "flow-valve position" mapping table; S3. When the set flow rate x of the main inlet pipe is between any two adjacent basic flow rate points, calculate the initial set valve position of the branch pipe regulating valve. S4. Using the initial set valve position of the branch pipe regulating valve obtained in step S3 as the initial opening degree of the branch pipe regulating valve, put it into operation. S5. Real-time acquisition of the actual flow rate of each branch pipe, and calculation of the average flow rate of n branch pipes as the flow rate set value of the branch pipe regulating valve; S6. Each PI controller is configured to output to the actuator of the corresponding branch control valve based on the received actual flow rate of the corresponding branch and the flow rate set value of the branch control valve, thereby dynamically adjusting the opening degree of the corresponding branch control valve. The initial set valve position of the branch pipe regulating valve is calculated using the following formula: ①； ②； In formula ①, This indicates the initial set valve position of the branch pipe regulating valve. This indicates the set flow rate of the main inlet pipe, and Located at two adjacent basic flow points and between, Indicates the basic flow point The corresponding basic valve position, Indicates the basic flow point The corresponding basic valve position.

2. The method for controlling the water distribution flow rate in a horizontal flow sedimentation tank according to claim 1, characterized in that, In S5, the average flow rate of the n branch pipes is calculated using the following formula: ③； In formula ③, This indicates the flow setpoint of the branch pipe regulating valve. This indicates the actual flow rate of each branch pipe.

3. The method for controlling the water distribution flow rate in a horizontal flow sedimentation tank according to claim 1, characterized in that, In S6, if the actual flow rate of the corresponding branch pipe is less than the flow rate setting value of the branch pipe regulating valve, the branch pipe regulating valve is opened wider; if the actual flow rate of the corresponding branch pipe is greater than the flow rate setting value of the branch pipe regulating valve, the branch pipe regulating valve is closed less; if the actual flow rate of the corresponding branch pipe is equal to the flow rate setting value of the branch pipe regulating valve, the branch pipe regulating valve maintains its original valve position.

4. A horizontal flow sedimentation tank water distribution flow control system for implementing the method described in any one of claims 1-3, comprising a water distribution channel, a suction well, and a plurality of parallel horizontal flow sedimentation tanks, wherein the water distribution channel is used to distribute the vortex well water to be treated to each horizontal flow sedimentation tank, and the suction well is used to collect the effluent from the horizontal flow sedimentation tanks after sedimentation, characterized in that, It also includes branch pipes and regulating valves. Each water distribution channel is equipped with branch pipes, one end of which is connected to the main water inlet pipe. The main water inlet pipe is connected to the water distribution pipeline. Each horizontal flow sedimentation tank is supplied with water by a corresponding branch pipe, and each branch pipe is equipped with a regulating valve.

5. The water distribution flow control system for a horizontal flow sedimentation tank according to claim 4, characterized in that, Each branch pipe is also equipped with a flow meter and a magnetic water filter. The flow meter is installed at the input end of the regulating valve, and the magnetic water filter is installed at the output end of the regulating valve.

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