Coagulant dosage adjustment method based on sedimentation velocity identification

Abstract

The present invention discloses a method for adjusting the dosage of a coagulant based on sedimentation velocity identification. The method identifies the characteristics of floc sedimentation velocity by image processing technology, and calculates the theoretical removal rate by taking the characteristics of floc sedimentation velocity as the core parameter. At the same time, an online monitoring instrument is used to monitor the turbidity of the inlet and outlet water of the sedimentation tank online to calculate the actual removal rate, and the user sets the ideal turbidity of the outlet water of the sedimentation tank to calculate the ideal removal rate, and then the adjustment percentage of the dosage of the coagulant is calculated by comparing the theoretical removal rate, the actual removal rate, and the ideal removal rate. The present invention fully considers the mechanism of removing impurities in water by coagulation and sedimentation, and improves the timeliness and reliability of the prediction by introducing the core parameter of the characteristics of floc sedimentation velocity, which is of great significance for accurately controlling the dosage of the coagulant.

Description

Technical Field

[0001] The invention relates to a method for controlling the dosage of a water treatment coagulant, and more specifically, mainly to a method for adjusting the dosage of a coagulant based on sedimentation velocity identification. Background Art

[0002] Coagulation dosing is an important part of water treatment. The dosage of coagulant has an important influence on its process effect, but its influence has the characteristics of long lag and nonlinearity. Therefore, how to realize the automatic control of coagulation dosing has always been a concern of the water industry. In the past, there were two dosing control methods: one was the control method based on alum floc feature identification and combined with sedimentation effluent turbidity, represented by the FCD method (also known as the FDA method); the other was the mathematical model control method based on operating parameters such as flowing current, flow rate, and sedimentation tank effluent turbidity, represented by the SCD method. Since the control logic was not built based on the mechanism model, there were limitations and unreliability to varying degrees in practice, and no satisfactory control effect was achieved. Therefore, it is necessary to study and improve the control and adjustment methods of coagulant dosage in the water treatment process. Summary of the invention

[0003] One of the purposes of the present invention is to address the above-mentioned shortcomings and provide a method for adjusting the dosage of coagulant based on sedimentation velocity identification, in the hope of solving the technical problems that similar coagulant dosage control methods in the prior art have limitations and unreliability to varying degrees, affecting the effect of the water treatment process.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for adjusting the amount of coagulant based on sedimentation velocity identification, the method comprising the following steps:

[0006] Step A: Online monitoring of the actual effluent turbidity N of the sedimentation tank in the water treatment system 出 and sedimentation tank inlet turbidity N 进 , and then the actual removal rate P is calculated by formula 1 实际 .

[0007]

[0008] Freely set the ideal effluent turbidity N of the sedimentation tank 出 , and then the ideal removal rate P is calculated by formula 2 理想 .

[0009]

[0010] Step B: Compare P 实际 With P 理想 .

[0011] As P 实际 <P 理想 , then the current coagulant dosage is increased according to the coagulant dosage adjustment rate a%, and the dosage is less than the preset coagulant dosage range of the current sedimentation tank.

[0012] As P 实际 =P 理想 , then maintain the existing coagulant dosage.

[0013] As P 实际 >P 理想 , then the current coagulant dosage is reduced according to the coagulant dosage adjustment rate a%, and the dosage is greater than the preset coagulant dosage range of the current sedimentation tank.

[0014] Step C: The above coagulant dosage adjustment rate a% is to identify the floc sedimentation speed in the sedimentation tank after time t (t is the residence time of the coagulation stage of the water plant) through image processing technology, and obtain the floc sedimentation speed u i and floc proportion p i ; The theoretical sedimentation tank treatment efficiency P is calculated by formula 3 理论 .

[0015] The treatment efficiency of vertical flow sedimentation tank is: P 理论 =(1-P0) (Formula 3.1)

[0016] The treatment efficiency of other sedimentation tanks is:

[0017] In formula 3, P0 is the proportion of particles whose sedimentation velocity is less than the interception sedimentation velocity u0. i and floc proportion p i It is obtained through image recognition, but the particle sedimentation speed is not uniform, so what is obtained through image recognition is not a fixed speed, but a speed distribution, and then the proportion of particles whose sedimentation speed is less than the interception sedimentation speed can be obtained.

[0018] The aforementioned interception sedimentation velocity u0 is calculated by formula 4.

[0019]

[0020] In formula 4, Q is the amount of water treated by the sedimentation tank, and A is the equivalent surface area of ​​the sedimentation tank.

[0021] The theoretical sedimentation tank treatment efficiency P is calculated by formula 5. 理论 , recalculate the actual sedimentation tank treatment efficiency P 实际 .

[0022] P 实际 =kP 理论(Formula 5)

[0023] In formula 5, k is the theoretical sedimentation tank treatment efficiency P 理论 The actual sedimentation tank treatment efficiency P 实际 The relationship coefficient is calculated by Formula 6.

[0024]

[0025] The coagulant dosage adjustment rate a% is determined by formula 7.

[0026]

[0027] The dosage of coagulant in the current sedimentation tank is adjusted by the dosage adjustment rate a%.

[0028] Preferably, a further technical solution is: the method further comprises repeating step B and step C after calculating the dosage adjustment rate a%.

[0029] A further technical solution is: when the sedimentation tank is a horizontal flow sedimentation tank, the equivalent surface area A of the sedimentation tank is the projection area of ​​the sedimentation tank on the horizontal plane; when the sedimentation tank is an inclined tube or inclined plate sedimentation tank, the equivalent surface area A of the sedimentation tank is the sum of the projection area of ​​the sedimentation tank on the horizontal plane and the projection area of ​​the inclined tube or inclined plate in the sedimentation tank.

[0030] A further technical solution is: before the method is executed, first set the dosage range of the coagulant [A min , A max ]; if the dosage adjustment rate a% is calculated, the adjusted dosage is > A max , then take the adjusted dosage as A max ; If the dosage adjustment rate a% is calculated and the adjusted dosage is less than A min , then take the adjusted dosage as A min .

[0031] A further technical solution is that the parameters required to be input when executing the method include at least the type of sedimentation tank, sedimentation tank parameters, and the ideal effluent turbidity N 出 ; The types of sedimentation tanks include horizontal flow sedimentation tanks, vertical flow sedimentation tanks, inclined tube sedimentation tanks and inclined plate sedimentation tanks; the sedimentation tank parameters include the coagulation stage residence time t and the equivalent surface area A.

[0032] A further technical solution is: the image processing technology is hyperspectral image target detection and particle swarm algorithm.

[0033] Compared with the prior art, one of the beneficial effects of the present invention is: the characteristics of floc sedimentation rate are identified by image processing technology, and the theoretical removal rate is calculated by taking the characteristics of floc sedimentation rate as the core parameter, and the inlet and outlet turbidity of the sedimentation tank is monitored online by online monitoring instruments to calculate the actual removal rate, and the user sets the ideal effluent turbidity of the sedimentation tank to calculate the ideal removal rate, and then the theoretical removal rate, the actual removal rate, and the ideal removal rate are compared to calculate the adjustment percentage of the coagulant dosage. The present invention fully considers the mechanism of coagulation and sedimentation to remove impurities in water, and by introducing the core parameter of floc sedimentation rate characteristics, the timeliness and reliability of the prediction are improved, which is of great significance for the precise control of the coagulant dosage. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a flowchart for describing an embodiment of the present invention.

[0035] Figure 2 for Figure 1 Flow chart for calculating the coagulant dosage adjustment rate a%. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings.

[0037] refer to Figure 1 As shown, in an embodiment of the present invention, the method for adjusting the amount of coagulant based on sedimentation velocity recognition is performed according to the following steps:

[0038] Step S1: Manually input parameters, including sedimentation tank type (vertical flow, horizontal flow, inclined plate, inclined tube), sedimentation tank parameters (equivalent sedimentation area A, coagulation stage residence time t), ideal effluent turbidity N 理想 , Coagulant dosage range [A min , A max ] and other parameters necessary for calculation.

[0039] Step S2, obtaining parameters, specifically, obtaining parameters from the sedimentation tank through image processing technologies such as hyperspectral image target detection and particle swarm algorithm, specifically, obtaining the sedimentation velocity distribution through the aforementioned image processing technology, and obtaining different sedimentation velocities u i The proportion of flocs i . Use the online monitoring equipment in the water treatment system to obtain the turbidity N of the sedimentation tank inlet water 进 , effluent turbidity N 出 , traffic Q.

[0040] Step S3, calculating the coagulant dosage adjustment rate a% by using the parameters obtained in step S1 and step S2.

[0041] Then, steps S2 and S3 are repeated to update and iterate the coagulant dosage adjustment rate a% through multiple calculations.

[0042] Combination Figure 2 As shown, in this embodiment, the coagulant dosage adjustment rate a% is calculated as follows:

[0043] Through image processing technology, the floc sedimentation speed in the sedimentation tank is identified after the coagulation stage residence time t, and the floc sedimentation speed u is obtained. i and floc proportion p i ; The theoretical sedimentation tank treatment efficiency P is calculated by formula 3 理论 .

[0044] The treatment efficiency of vertical flow sedimentation tank is: P 理论 =(1-P0) (Formula 3.1)

[0045] The treatment efficiency of other sedimentation tanks is:

[0046] In Formula 3, P0 is the proportion of particles whose sedimentation velocity is less than the interception sedimentation velocity u0, and the aforementioned interception sedimentation velocity u0 is calculated by Formula 4.

[0047]

[0048] In Formula 4, Q is the amount of water treated in the sedimentation tank, and A is the equivalent surface area of ​​the sedimentation tank. When the sedimentation tank is a horizontal flow sedimentation tank, the equivalent surface area A of the sedimentation tank is the projection area of ​​the sedimentation tank on the horizontal plane; when the sedimentation tank is an inclined tube or inclined plate sedimentation tank, the equivalent surface area A of the sedimentation tank is the sum of the projection area of ​​the sedimentation tank on the horizontal plane and the projection area of ​​the inclined tube or inclined plate in the sedimentation tank.

[0049] The theoretical sedimentation tank treatment efficiency P is calculated by formula 5. 理论 , recalculate the actual sedimentation tank treatment efficiency P 实际 .

[0050] P 实际 =kP 理论 (Formula 5)

[0051] In formula 5, k is the theoretical sedimentation tank treatment efficiency P 理论 The actual sedimentation tank treatment efficiency P 实际 The relationship coefficient is calculated by Formula 6.

[0052]

[0053] The coagulant dosage adjustment rate a% is determined by formula 7.

[0054]

[0055] The dosage of coagulant in the current sedimentation tank is adjusted by the dosage adjustment rate a%. During the adjustment process, the actual effluent turbidity N in the sedimentation tank is monitored online in the water treatment system. 出 and sedimentation tank inlet turbidity N 进 , and then the actual removal rate P is calculated by formula 1 实际 .

[0056]

[0057] Freely set the ideal effluent turbidity N of the sedimentation tank 出 , and then the ideal removal rate P is calculated by formula 2 理想 .

[0058]

[0059] Compare P 实际 With P 理想 .

[0060] As P 实际 <P 理想 , then the current coagulant dosage is increased according to the coagulant dosage adjustment rate a%, and the dosage is less than the preset coagulant dosage range of the current sedimentation tank.

[0061] As P 实际 =P 理想 , then maintain the existing coagulant dosage.

[0062] As P 实际 >P 理想 , then the current coagulant dosage is reduced according to the coagulant dosage adjustment rate a%, and the dosage is greater than the preset coagulant dosage range of the current sedimentation tank.

[0063] As mentioned above, the coagulant dosage range needs to be set manually [A min , A max ], if the above calculation of dosage adjustment rate a% results in the adjusted dosage > A max , then take the adjusted dosage as A max ; If the dosage adjustment rate a% is calculated and the adjusted dosage is less than A min , then take the adjusted dosage as A min .

[0064] In the above-mentioned embodiment of the present invention, by taking the floc sedimentation rate in the sedimentation tank as the core parameter, and calculating the theoretical sedimentation tank treatment efficiency based on the floc sedimentation rate, and comparing it with the actual sedimentation tank treatment efficiency, the coagulant dosage adjustment percentage is calculated, thereby effectively improving the reliability of the coagulant dosage adjustment in the water treatment process, and reducing the impact of the coagulant dosage problem on the effect of the entire water treatment process.

[0065] In addition to the above, it should be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this specification refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of the present invention.

[0066] Although the present invention is described herein with reference to a number of illustrative embodiments of the present invention, it will be appreciated that those skilled in the art may devise many other modifications and implementations that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the present disclosure, drawings, and claims, a variety of variations and improvements may be made to the components and / or layout of the subject combination layout. In addition to variations and improvements made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A method for adjusting the amount of coagulant based on sedimentation velocity identification, the method comprising the following steps: Online monitoring of the actual effluent turbidity N of the sedimentation tank 出 and sedimentation tank inlet turbidity N 进 , and then the actual removal rate P is calculated by formula 1 实际 ; Freely set the ideal effluent turbidity N of the sedimentation tank 出 , and then the ideal removal rate P is calculated by formula 2 理想 ; Compare P 实际 With P 理想 ; As P 实际 <P 理想 , then the current coagulant dosage is increased according to the coagulant dosage adjustment rate a%, and the dosage is less than the preset coagulant dosage range of the current sedimentation tank; As P 实际 =P 理想 , then maintain the existing dosage of coagulant; As P 实际 >P 理想 , then the current coagulant dosage is reduced according to the coagulant dosage adjustment rate a%, and the dosage is greater than the preset coagulant dosage range of the current sedimentation tank; The coagulant dosage adjustment rate a% is to identify the floc sedimentation speed in the sedimentation tank after the coagulation stage residence time t through image processing technology, and obtain the floc sedimentation speed u i and floc proportion p i ; The theoretical sedimentation tank treatment efficiency P is calculated by formula 3 理论 ; The treatment efficiency of vertical flow sedimentation tank is: P 理论 =(1-P0) (Formula 3.1) The treatment efficiency of other sedimentation tanks is: In Formula 3, P0 is the proportion of particles whose sedimentation velocity is less than the interception sedimentation velocity u0, and the interception sedimentation velocity u0 is calculated by Formula 4; In formula 4, Q is the amount of water treated in the sedimentation tank, and A is the equivalent surface area of ​​the sedimentation tank; The theoretical sedimentation tank treatment efficiency P is calculated by formula 5. 理论 , recalculate the actual sedimentation tank treatment efficiency P 实际 ; P 实际 =kP 理论 (Formula 5) In formula 5, k is the theoretical sedimentation tank treatment efficiency P 理论 The actual sedimentation tank treatment efficiency P 实际 The relationship coefficient is calculated by formula 6; The coagulant dosage adjustment rate a% is determined by formula 7; The dosage of coagulant in the current sedimentation tank is adjusted by the dosage adjustment rate a%.

2. The method for adjusting the amount of coagulant based on sedimentation velocity identification according to claim 1, characterized in that: The method further comprises, after calculating the dosage adjustment rate a%, comparing the P 实际 With P 理想 and recalculate the dosage adjustment rate a% based on the comparison result.

3. The method for adjusting the amount of coagulant based on sedimentation velocity identification according to claim 1, characterized in that: When the sedimentation tank is a horizontal flow sedimentation tank, the equivalent surface area A of the sedimentation tank is the projection area of ​​the sedimentation tank on the horizontal plane; When the sedimentation tank is an inclined tube or inclined plate sedimentation tank, the equivalent surface area A of the sedimentation tank is the sum of the projection area of ​​the sedimentation tank on the horizontal plane and the projection area of ​​the inclined tube or inclined plate in the sedimentation tank.

4. The method for adjusting the amount of coagulant based on sedimentation velocity identification according to claim 1, characterized in that: Before the method is executed, the dosage range of the coagulant is first set. min , A max ]; If the dosage adjustment rate a% is calculated, the adjusted dosage is > A max , then take the adjusted dosage as A max ; If the dosage adjustment rate a% is calculated and the adjusted dosage is less than A min , then take the adjusted dosage as A min .

5. The method for adjusting the amount of coagulant based on sedimentation velocity identification according to claim 1 or 4, characterized in that: The parameters required to be input when executing the method include at least the type of sedimentation tank, sedimentation tank parameters, ideal effluent turbidity N 出 ; The types of sedimentation tanks include horizontal flow sedimentation tanks, vertical flow sedimentation tanks, inclined tube sedimentation tanks and inclined plate sedimentation tanks; the sedimentation tank parameters include the coagulation stage residence time t and the equivalent surface area A.

6. The method for adjusting the amount of coagulant based on sedimentation velocity identification according to claim 1, characterized in that: The image processing technology is hyperspectral image target detection and particle swarm algorithm.

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