Method and system for controlling coagulant dosing through on-line prediction of turbidity after flocculation water sedimentation

A coagulant and turbidity technology, which is applied in the direction of flocculation/sedimentation water/sewage treatment, etc., can solve the problems of insufficient turbidity and accuracy of sedimentation water, so as to improve the quality of water purification, reduce the cost of water purification, and reduce refilling. amount of effect

Inactive Publication Date: 2010-08-18
SHANGHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

There are always a small number of tiny particles in the water that are not coagulated, so that the water has a certain turbidity. Compared with 5NTU, this part of turbidity can be ignored, but compared with 0.5NTU, it accounts for a certain ratio and cannot be completely ignored.
Therefore, under the condition that the sedimentation water turbidity requirement is low, it is not comprehensive and accurate to use the sedimentation characteristics of flocs to predict the sedimentation water turbidity.

Method used

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  • Method and system for controlling coagulant dosing through on-line prediction of turbidity after flocculation water sedimentation
  • Method and system for controlling coagulant dosing through on-line prediction of turbidity after flocculation water sedimentation
  • Method and system for controlling coagulant dosing through on-line prediction of turbidity after flocculation water sedimentation

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] Embodiment 1: see figure 1 , the method of controlling the amount of coagulant injection by online prediction of turbidity after flocculation water sinking is: the raw water enters the flocculation tank 5 to mix, react, and flocculate with the added coagulant to produce flocs, and the water at the end of the flocculation tank 5 The flocculation water is collected in real time through the sensor 8 for measuring turbidity, and then the turbidity is measured after settling in the sensor 8 for a given settling time; and the measured value is compared with the set value, and the difference is calculated by PID. Obtain the required filling rate, and then multiply it by the flow rate of the incoming water to obtain the filling volume, convert it into a standard current output signal to control the filling volume of the filling pump 3, and perform online coagulant filling.

Embodiment 2

[0041] 1. Raw water enters the flocculation tank, mixes, reacts, and flocculates with the added coagulant to produce flocs. In the method, the flocculation water is collected in real time through sensors underwater at the end of the flocculation tank.

[0042] 2. The water flows in slowly from the water inlet hole. After the water level in the sensor reaches the measured water level, close the gate valve of the water inlet hole to keep the water level unchanged. After the sedimentation time in the sensor settles, measure the turbidity of the water 2cm below the water level.

[0043] 3. After a measurement is completed, the gate valve of the water outlet hole is opened, and the submersible pump works at a low speed to pump out the water in the sensor. When the water surface drops to the vicinity of the water inlet hole, the water inlet hole is opened, so that water flows in from the water inlet hole and flows out of the water outlet hole. , the water level remains basically unc...

Embodiment 3

[0049] Embodiment 3: see figure 1 , the system used in the above method to control the amount of coagulant injection by online prediction of the turbidity after the flocculation water sinks, including a sedimentation tank 6, a flocculation tank 5, a coagulant tank, the flocculation tank 5 and the sedimentation tank 6 Connected in parallel and integrated, a turbidity meter 9 is installed at the outlet of the sedimentation tank 6, a sensor 8 for measuring turbidity is inserted at the end of the flocculation tank 5, and the water inlet pipe passes through an inlet pump 1 and a flow meter 2. Connect the water inlet of the flocculation tank 5, and the outlet of the coagulant tank 4 is connected to the water inlet of the flocculation tank (5) through a filling pump 3; a microprocessor 7 is electrically connected to the flow rate Meter 2, filling pump 3, sensor 8 and turbidity meter 9 for measuring turbidity.

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Abstract

The invention relates to a method and a system for controlling coagulant dosing through on-line prediction of turbidity after flocculation water sedimentation. The method comprises the following steps of: making raw water enter a flocculation tank to mix, react and flocculate with the added coagulant so as to generate a flocculating substance; collecting the flocculation water in real time through a sensor for measuring the turbidity under the water at the tail end of the flocculation tank; sedimenting in the sensor in the given sedimentation time, and measuring the turbidity; comparing the measured value with the set value; and after the difference is subjected to PID operation, obtaining the needed dosing ratio, and multiplying the dosing ratio with the water inlet flow to obtain the dosing, converting the dosing into a standard current output signal to control the dosing of a dosing pump, and dosing the coagulant on line. The system consists of the flocculation tank, a sedimentation tank, the dosing pump, a coagulation tank, a microprocessor and a sensor 5 which is specially designed for measuring the turbidity. Due to adoption of the sensor for measuring the turbidity, the turbidity after flocculation water sedimentation can be accurately measured on line without being disturbed by other factors. Therefore, the on-line coagulant dosing can be accurately controlled, the coagulant dosing is reduced, the water purification quality is improved, and the water purification cost is lowered.

Description

technical field [0001] The invention relates to a method and system for realizing automatic control of coagulant filling amount by online pre-measurement of the settled turbidity of flocculation water at the end of a flocculation tank. It belongs to the field of water supply engineering. Background technique [0002] Adding coagulant to make small particles in water agglomerate into large particles and precipitate in water is the most commonly used method for liquid-solid separation in the process of water purification. Whether the filling amount of the coagulant is appropriate is directly related to the quality of the factory water and the production cost. If the amount of injection is too small, the flocculation effect will deteriorate and the water quality will not meet the requirements; if the amount of injection is too large, the consumption of coagulant will increase, which will increase the production cost, and when the amount of injection is too large, the flocculat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/52
Inventor 宋启敏宋振亚巴怡然
Owner SHANGHAI UNIV
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