A shunt and step-by-step coagulation device and its digital intelligent coagulation control method

Abstract

The present invention discloses a shunt step coagulation device and its digital intelligent coagulation control method, belonging to the field of water treatment. It includes an upper mixing chamber and a lower mixing chamber connected by a draft tube. The upper mixing chamber is connected to a shunt tube through a mixing pipe, and the shunt tube is connected to a water inlet pipe. One side of the lower mixing chamber is connected to the water inlet pipe through a Venturi tube, and the other side of the lower mixing chamber is connected to a water outlet pipe. A shunt regulating valve is arranged on the Venturi tube, a flow velocity tester is arranged on the shunt tube, a chemical dosing pipe is arranged on the mixing pipe, a stirring impeller and a thrust impeller are respectively arranged in the upper mixing chamber and the draft tube, a draft tube communicating with the draft tube is arranged in the lower mixing chamber, and a flowing current sensor is arranged on the water outlet pipe. This solution not only ensures the hydraulic conditions required for the best mixing effect, but also ensures that the turbidity of the sedimentation tank effluent is stably below 1 ntu for a long time through digital intelligent coagulation control for dynamic parameter adjustment and GT optimized operation, achieving the purposes of improving quality and efficiency, saving water and reducing emissions, and saving energy and reducing consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and particularly relates to a shunt step-by-step coagulation device and a digital intelligent coagulation control method thereof. Background Art

[0002] The coagulation process is the core process of water supply and drainage treatment, reclaimed water treatment, and some sewage treatment, including two parts: flocculation and coagulation. Flocculation refers to the stirring and mixing stage of adding a coagulant to water, and coagulation refers to the raw water after adding a coagulant and being fully mixed, where fine flocs contact and collide with each other under the action of water flow to form larger flocs; the development of coagulation technology is the development of the mixing process and the coagulation process.

[0003] In the initial stage of the development of water treatment technology, the importance of the mixing process was not fully recognized; in engineering, the coagulant was simply added in front of the pressure pump, and the mixing process was completed by the stirring action of the water pump. This was the initial mixing mode - pump mixing. Pump mixing causes relatively serious corrosion to the water pump. Therefore, a method of adding the coagulant into the pipeline and using a certain length of pipeline to complete the mixing, called pipeline mixing, emerged. Currently, this mixing method is still in use. Droplet mixing is a mixing method proposed based on the understanding of the intense mixing state of gas and water, and its control parameters are empirical and perceptual. The emergence of the mechanical stirring mixing tank indicates a certain understanding of the fluid dynamics mechanism of mixing, and researchers proposed to control the effect of mechanical stirring mixing with parameters that can characterize the turbulent state of the fluid in the mixing tank.

[0004] The commonly used coagulation technology in the water supply and drainage industry is to form polymers through the hydrolysis of coagulants. These large-particle polymers have a strong adsorption capacity for impurity colloids and can adsorb colloids within a certain distance and sink together. Physical coagulation includes self-coagulation and enhanced thickening sedimentation in which large particles adsorb small particles and sink rapidly. Coagulation control technology refers to the technology and method used to accurately determine the optimal dosage of coagulant per thousand tons of water and the control method of coagulant dosing to obtain the best mixing effect.

[0005] For a specific water treatment process system, the form and performance of the water purification structure are already determined. Coagulation control refers to timely adjusting the dosage of the coagulant to adapt to changes in factors such as raw water quality, water volume, and the efficacy of the coagulant itself, and ensuring that the turbidity of the sedimented water reaches the specified index; selecting different influencing factors as input parameters and determining the input parameters through different methods constitute various different technical methods for coagulant dosing control; these methods can be classified from different perspectives.

[0006] It can be classified according to the control method into: offline control, such as empirical visual inspection method, potentiometric method, etc., and intermittent manual intervention and adjustment of the dosing condition are carried out according to the experimental or observation results; online control, that is, various automatic control methods, and the control system continuously and automatically adjusts the dosing amount according to the results of online continuous monitoring of the controlled parameters. Online control can be divided into: simple feedback control, feedforward control, compound control (feedforward-feedback control, cascade control), and other control methods.

[0007] It can be classified according to the nature of the controlled parameter into: simulation method, which determines the dosing amount through a certain similarity simulation relationship, including beaker experiment method, simulated filter method, simulated sedimentation tank method, etc.; water quality parameter method, which establishes an empirical model through apparent water quality parameters as the basis for controlling the dosing amount, such as mathematical simulation method, etc.; characteristic parameter method, and this type of method all uses the change of a certain microscopic characteristic in the coagulation process as the basis for determining the dosing amount, including charge control methods such as potentiometric method, colloid titration method, streaming current method, etc., and also includes fluorescence method, pulsation parameter method, specific surface area method, etc.; effect evaluation method, which takes the actual effect macroscopically observed after dosing and coagulation as the basis for adjusting the dosing amount, including empirical visual inspection method, turbidity measurement method, etc.

[0008] Currently, the most commonly used digital intelligent coagulation control methods in domestic water purification plants are empirical visual inspection method, beaker experiment method, and the relatively advanced streaming current method.

[0009] All the above-mentioned coagulation control technologies have a major defect, that is, they ignore the important role played by the mixing process facilities and mixing efficiency in coagulation control. This is a difficult problem existing in the coagulation control technology in the domestic and international water supply and drainage industries; because for the most advanced and precise mixing effect detection methods and facilities and equipment, the various data representing the mixing effect detected are only the mixing effect data obtained during the online operation of various different mixing processes, facilities, and equipment. For example, the streaming current sensor is the most advanced mixing effect detection instrument at home and abroad currently, and the mixing effect data it detects is true and precise for now, but the streaming current sensor itself cannot change the mixing effect, and only uses the change of a certain microscopic characteristic in the coagulation process as the basis for determining the dosing amount. To discuss in another way, the offline control of coagulation technology is manual intervention and adjustment to determine the dosing basis. The simulation method of coagulation control technology relies on instruments and facilities for measurement to determine the dosing basis. In short, for the current coagulation control technology, to achieve the best mixing effect, it can only be solved by adjusting the coagulant dosage, which is not scientific and rigorous; because according to the coagulation mechanism of coagulant and the coagulation dynamic mechanism, the existing mixing processes, facilities, and equipment cannot meet the requirements of the hydraulic conditions and mixing residence time that conform to the coagulation mechanism of coagulant and the coagulation dynamic mechanism during the mixing process, and there are many problems in solely relying on adjusting the coagulant dosage to improve the mixing effect. Summary of the Invention

[0010] Aiming at the above deficiencies of the prior art, the present invention provides a shunt step-by-step coagulation device and its digital intelligent coagulation control method, which solves the problems of poor coagulation effect of the existing coagulation device, poor adaptability to changes in external factors, poor quality improvement, efficiency increase, energy consumption reduction and emission reduction effects.

[0011] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0012] In the first aspect, a shunt step-by-step coagulation device is provided, which includes an upper mixing chamber and a lower mixing chamber connected by a draft tube. The upper mixing chamber is connected to a shunt tube through a mixing tube, the shunt tube is connected to a water inlet pipe, one side of the lower mixing chamber is connected to the water inlet pipe through a Venturi tube, and the other side of the lower mixing chamber is connected to a water outlet pipe; a shunt regulating valve is arranged on the Venturi tube, a flow velocity tester is arranged on the shunt tube, a chemical dosing tube is arranged on the mixing tube, the chemical dosing tube is connected to an automatic chemical dosing device, a guide plate is arranged in the mixing tube, a stirring impeller and a thrust impeller are respectively arranged in the upper mixing chamber and the draft tube, the stirring impeller and the thrust impeller are both drivingly connected to a permanent magnet stirring motor, a draft tube communicating with the draft tube is arranged in the lower mixing chamber, a water inlet pH sensor, a turbidity sensor and a flow sensor are arranged on the water inlet pipe, and a water outlet pH sensor and a streaming current sensor are arranged on the water outlet pipe; the shunt regulating valve, the flow velocity tester, the automatic chemical dosing device, the permanent magnet stirring motor, the water inlet pH sensor, the water outlet pH sensor, the turbidity sensor, the flow sensor and the streaming current sensor are all electrically connected to a digital intelligent coagulation control system.

[0013] Further, the digital intelligent coagulation control system includes: a regulating valve actuator, an automatic chemical dosing actuator and a motor actuator respectively electrically connected to the shunt regulating valve, the automatic chemical dosing device and the permanent magnet stirring motor, and a streaming current controller electrically connected to the streaming current sensor. The regulating valve actuator, the motor actuator and the flow velocity tester are all electrically connected to a first PLC controller; the streaming current controller is respectively electrically connected to the first PLC controller and a PDI controller, and the PDI controller is electrically connected to the automatic chemical dosing actuator.

[0014] Further, the guide plate is spiral, the extending direction of the port of the chemical dosing tube is the same as the water flow direction in the mixing tube, a diffusion cone plate is arranged at the port of the chemical dosing tube with a gap, and the tip of the diffusion cone plate faces the port of the chemical dosing tube.

[0015] Further, the shunt regulating valve is arranged at the middle throat of the Venturi tube, a plurality of shunt holes are opened on the gate plate of the shunt regulating valve, and the flow velocity tester is arranged at the connection end of the shunt tube and the mixing tube.

[0016] Further, 2.5 times the sum of the cross-sectional areas of a plurality of shunt holes is equal to the cross-sectional area of the shunt tube.

[0017] Furthermore, an automatic exhaust valve is provided at the top of the upper mixing chamber.

[0018] In a second aspect, a digital intelligent coagulation control method for a split-step coagulation device is provided, which includes a coagulant coagulation method, and the steps are as follows:

[0019] S1: Coagulant mixing process: The coagulant is added through a chemical dosing pipe, and the flow rate of the shunt pipe is controlled by a shunt regulating valve to quickly diffuse the coagulant into the source water in the mixing pipe;

[0020] S2: Coagulant partial destabilization and complete destabilization process: By controlling the rotation speed of the permanent magnet stirring motor, the coagulant is subjected to a combined mixing of stirring and water power in the upper mixing chamber, the coagulant is quickly hydrolyzed, and the impurity colloid particles are destabilized. Then, under the mixing action of the thrust impeller, the impurity colloid particles are completely destabilized in the draft tube;

[0021] S3: Coagulant heterocoagulation process: Through the design of the structural parameters of the draft tube, the fluid generates an axial flow and an axial circulation in the draft tube under the action of the thrust impeller, and then intersects and converges with the radial flow generated by the Venturi tube. The water body forms a three-dimensional flow state in the lower mixing chamber, forming a high-intensity mixing condition, and replacing Brownian motion to ensure that the destabilized impurity colloid particles quickly aggregate and the flocs present a state of small particles that are not easily broken.

[0022] Furthermore, the mixing intensity G value in the coagulant mixing process is ≥600 - 1000s -1 、the residence time T < 0.2s; the mixing intensity G value in the coagulant partial destabilization and complete destabilization process is ≥3000s -1 、the residence time T < 0.2s; the mixing intensity G value in the coagulant heterocoagulation process is ≤2000s -1 、the residence time T ≥ 6s.

[0023] In a third aspect, a digital intelligent coagulation control method for a split-step coagulation device is provided, which includes a double-closed-loop digital intelligent coagulation control method, and the steps are as follows:

[0024] A1: Set the parameter ranges of the shunt pipe flow rate, the rotation speed of the permanent magnet stirring motor, the flow current response value, the optimal value, and the initial dosage of the coagulant;

[0025] A2: According to the change of the flow rate tester, control the shunt regulating valve to automatically adjust until the flow rate of the shunt pipe is stabilized within the corresponding parameter range;

[0026] A3: Monitor the change of the flowing current response value, and control the rotation speed of the permanent magnet stirring motor to automatically adjust within the corresponding parameter setting range until the flowing current response value approaches the optimal value to the greatest extent. If the flowing current response value is within the corresponding parameter setting range at this time, the execution ends; otherwise, execute step A4.

[0027] A4: When the flowing current response value is higher than the upper limit of the parameter setting range, control the automatic dosing device to reduce the dosage of the coagulant until the flowing current response value changes dynamically, and return to step A3; when the flowing current response value is lower than the lower limit of the parameter setting range, execute step A5.

[0028] A5: When the influent flow rate is greater than the rated influent flow rate or when the raw water turbidity is greater than the normal turbidity, execute step A6; when the temperature and turbidity of the raw water are respectively lower than the normal temperature and normal turbidity, execute step A7; when the pH value of the raw water is greater than 8, execute step A8.

[0029] A6: Control the automatic dosing device to increase the dosage of the coagulant until the flowing current response value changes dynamically, and return to step A3.

[0030] A7: First return to step A3, and after step A3 is executed, if the flowing current response value is still lower than the lower limit of the parameter setting range, execute step A6.

[0031] A8: Add carbon dioxide to the raw water until the pH value of the raw water is not greater than 8; or reduce the lower limit value of the parameter setting range until the flowing current response value is within the new parameter setting range; and return to step A3.

[0032] Furthermore, step A1 specifically includes: the parameter range of the flow rate of the shunt pipe is 1.2 - 1.5 m / s; the parameter range of the rotation speed of the permanent magnet stirring motor is 300 - 520 r / min; the parameter range of the flowing current response value when the quality of the raw water meets the standard is -40 - -10.

[0033] The beneficial effects of the present invention are:

[0034] 1. This solution diverts the incoming water of the inlet pipe and then realizes the cross - convergence of radial flow and axial flow in the lower mixing chamber. The purpose is to make full use of the original motive force of the incoming water fluid and add mechanical stirring hybrid power, so as to meet the requirements of the mixing time (T) and mixing intensity (G) for the rapid diffusion, rapid hydrolysis, and complete destabilization of the coagulant, thus realizing the step - by - step diversion mixing of the coagulant and solving the problem that the existing coagulation devices are difficult to meet the mixing intensity and mixing time required for each process of the coagulant coagulation mechanism. At the same time, the G value and T value during the coagulant coagulation process can be adjusted by the opening degree of the diversion regulating valve and the rotation speed of the permanent - magnet stirring motor, and then, through the change of the flowing current response value (mixing effect), the rotation speed of the permanent - magnet stirring motor can be adjusted in reverse to facilitate the optimized combination operation of GT.

[0035] 2. This solution adopts a double - closed - loop digital intelligent coagulation control method. Among them, the first closed - loop is: by adjusting the flow rate of the diversion pipe and the rotation speed of the permanent - magnet stirring motor, the step - by - step diversion coagulation device is adjusted to meet the best hydraulic conditions and the best residence time required by the coagulant coagulation mechanism, and on the basis of the best hydraulic conditions and the best residence time, the optimized combination operation of GT is carried out. The second closed - loop is: on the basis of the former achieving the best mixing efficiency, by timely adjusting the dosage of the coagulant to achieve the best mixing effect. The two closed - loop controls overlap with each other, have the same goal, but independently play their respective roles, with clear causal relationships, safety, reliability, and simplicity; enabling the efficacy of the coagulant to be fully exerted to the extreme and saving the drug consumption to the greatest extent; solving the problem that the existing coagulation control technology has great limitations in changing the coagulation effect simply by adjusting the dosage of the coagulant, and realizing the goals and requirements of improving quality, increasing efficiency, reducing consumption, and reducing emissions in the water treatment industry in a true sense.

[0036] 3. Through the optimization of the diversion and distribution coagulation device and the digital intelligent coagulation control method, this solution not only ensures the hydraulic conditions and mixing efficiency required for the best mixing effect of the coagulation device, but also accurately determines the best dosage of the coagulant; and the best dosage can be quickly and accurately obtained through a trial operation within a certain period of time, so that the efficacy of the coagulant is exerted to the extreme and the drug consumption is saved to the greatest extent. The key is that in the case of various external factors such as changes in raw water quality, water volume, low temperature and low turbidity affecting the coagulation effect, adaptive parameter adjustment can be made to ensure that the turbidity of the sedimentation tank effluent is stably below 1 NTU for a long time, which means laying a foundation for reducing the burden of the filter water treatment process subsequently, reducing the filter backwashing frequency by more than 1 time, saving more than 50% of the backwashing water, reducing sewage emissions by more than 50%, saving more than 30% of the coagulant per thousand tons of water, and reducing the power consumption per thousand tons of water by more than 5%.

[0037] 4. The coagulation device of this solution has dual functions of mixing and heterocoagulation. The heterocoagulation process is mainly caused by Brownian motion, which gradually weakens as the particle size increases. When the particle size grows to a certain size, Brownian motion no longer works. Therefore, this solution incorporates the heterocoagulation process into the coagulation device and accelerates the heterocoagulation process through high-intensity mixing means. By using this means, the collision and aggregation of particles can be effectively promoted, thus achieving an excellent mixing effect.

[0038] 5. By setting the flow rate adjustment range and performing digital intelligent control, this solution can not only ensure the hydraulic conditions required by the coagulant mixing mechanism, but also, importantly, when the influent flow rate changes, especially when the change amount exceeds 60%, the coagulation effect of the coagulant is not affected. The setting of the diversion holes on the diversion regulating valve gate can effectively ensure the formation of three-dimensional fluid in the lower mixing chamber during low-flow operation, thereby ensuring its mixing intensity.

[0039] 6. When external factors such as source water quality, water volume, low temperature and low turbidity, and pH value that affect the coagulation effect of the coagulant occur, the control system converts these sensor signals into digital control and dynamically adjusts and feedback-controls parameters such as the mixing intensity of the coagulation device, the flow rate of the diversion pipe, the flow current response value, and the coagulant dosage control in a timely manner to reduce or eliminate the influence of these external factors on the coagulation effect of the coagulant.

[0040] 7. After the coagulant is added in this solution, the mixing effect can be detected by the flow current detector within 10 seconds, and the coagulant dosage can be accurately determined within 10 minutes, which greatly ensures the safe operation of the water treatment process in the water plant. Brief Description of the Drawings

[0041] Figure 1 It is a structural schematic diagram of the diversion step-by-step coagulation device.

[0042] Figure 2 It is a flow chart of the digital intelligent coagulation control method of this solution.

[0043] Figure 3 It is a structural schematic diagram of the mixing pipe.

[0044] Figure 4 It is a structural schematic diagram of the diversion regulating valve.

[0045] Among them, 1. Draft tube, 2. Upper mixing chamber, 3. Lower mixing chamber, 4. Mixing pipe, 5. Shunt pipe, 6. Water inlet pipe, 7. Venturi tube, 8. Water outlet pipe, 9. Shunt regulating valve, 10. Flow velocity tester, 11. Chemical dosing pipe, 12. Baffle plate, 13. Stirring impeller, 14. Thrust impeller, 15. Permanent magnet stirring motor, 16. Draft tube, 17. Inlet water pH sensor, 18. Outlet water pH sensor, 19. Streaming current sensor, 20. Diffusion cone plate, 21. Shunt hole, 22. Automatic exhaust valve, 23. Flow sensor. Specific implementation manner

[0046] The specific implementation manner of the present invention will be described below to facilitate those skilled in the art of this technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation manner. For those of ordinary skill in the art of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0047] As Figures 1 to 4 shown, the shunt step-by-step coagulation device of this solution includes an upper mixing chamber 2 and a lower mixing chamber 3 connected through a draft tube 1. The upper mixing chamber 2 is connected to a shunt pipe 5 through a mixing pipe 4. The shunt pipe 5 is connected to a water inlet pipe 6. One side of the lower mixing chamber 3 is connected to the water inlet pipe 6 through a Venturi tube 7. The other side of the lower mixing chamber 3 is connected to a water outlet pipe 8.

[0048] A shunt regulating valve 9 is provided on the Venturi tube 7. A flow velocity tester 10 is provided on the shunt pipe 5. A chemical dosing pipe 11 is provided on the mixing pipe 4. The chemical dosing pipe 11 is connected to an automatic chemical dosing device. A baffle plate 12 is provided inside the mixing pipe 4. An automatic exhaust valve 22 is provided at the top of the upper mixing chamber 2. A stirring impeller 13 and a thrust impeller 14 are respectively provided inside the upper mixing chamber 2 and the draft tube 1. Both the stirring impeller 13 and the thrust impeller 14 are in transmission connection with a permanent magnet stirring motor 15. A draft tube 16 connected to the draft tube 1 is provided inside the lower mixing chamber 3. An inlet water pH sensor 17 and a flow sensor 23 are provided on the water inlet pipe 6. An outlet water pH sensor 18 and a streaming current sensor 19 are provided on the water outlet pipe 8. The shunt regulating valve 9, the flow velocity tester 10, the automatic chemical dosing device, the permanent magnet stirring motor 15, the inlet water pH sensor 17, the outlet water pH sensor 18, the streaming current sensor 19 and the flow sensor 23 are all electrically connected to a digital intelligent coagulation control system.

[0049] Among them, the digital intelligent coagulation control system includes: a control valve actuator, an automatic chemical dosing actuator, and a motor actuator that are respectively electrically connected to the flow splitting regulating valve 9, the automatic chemical dosing equipment, and the permanent magnet stirring motor 15, and a flowing current controller that is electrically connected to the flowing current sensor 19. The control valve actuator, the motor actuator, and the flow velocity tester 10 are all electrically connected to the first PLC controller; the flowing current controller is respectively electrically connected to the first PLC controller and the PDI controller, and the PDI controller is electrically connected to the automatic chemical dosing actuator; the digital intelligent coagulation control system of this solution is mainly used for automatic recognition of sensing information, system reading, data analysis, information conversion, detection and acquisition, equipment monitoring and warning, dynamic parameter adjustment, feedback control, etc.

[0050] The flow splitting regulating valve 9 is arranged at the middle throat of the Venturi tube 7. A number of flow splitting holes 21 are opened on the gate plate of the flow splitting regulating valve 9, and 2.5 times the sum of the cross-sectional areas of the number of flow splitting holes 21 is equal to the cross-sectional area of the flow splitting pipe 5; the flow velocity tester 10 is arranged at the connection end of the flow splitting pipe 5 and the mixing pipe 4.

[0051] This solution splits the water inlet of the water inlet pipe 6, and then realizes the cross-convergence of the radial flow and the axial flow in the lower mixing chamber 3. The purpose is to make full use of the original motive force of the inlet fluid and add mechanical stirring hybrid power, so as to meet the requirements of the mixing time (T) and mixing intensity (G) for the rapid diffusion, rapid hydrolysis, and complete destabilization of the coagulant, so as to realize the split-step mixing of the coagulant and solve the problem that the existing coagulation device is difficult to meet the mixing intensity and mixing time required for each process of the coagulant coagulation mechanism.

[0052] Among them, the flow splitting process specifically includes: setting the upper and lower limit flow velocities of the flow splitting pipe 5 according to the optimal flow rate of the flow splitting pipe 5; when the flow velocity of the flow splitting pipe 5 exceeds the upper limit flow velocity of the flow splitting pipe 5 or is lower than the lower limit flow velocity of the flow splitting pipe 5, adjusting the flow splitting regulating valve 9 in a timely manner so that the flow velocity of the flow splitting pipe 5 always remains in the optimal set state; such a setting enables the flow rate of the flow splitting pipe 5 to be always maintained when the water volume of the water inlet pipe 6 changes, and the mixing effect is not affected by the change of the inlet water flow rate; when the water inlet of the water inlet pipe 6 operates at the rated flow rate or greater than the rated flow rate, the flow splitting regulating valve 9 is in the fully open state; when the main water inlet volume is less than 35% of the rated flow rate, the flow splitting regulating valve 9 is in the fully closed state, but through a number of flow splitting holes 21 on the gate plate of the flow splitting regulating valve 9, 10% of the water inlet volume still enters the lower mixing chamber 3 and 25% of the water inlet volume enters the flow splitting pipe 5 and the upper mixing chamber 2, so that the mixing hydraulic conditions of the mixing device can meet the requirements of the coagulant coagulation mechanism to the greatest extent.

[0053] This solution also provides a digital intelligent coagulation control method for a split-step coagulation device, which includes a coagulant coagulation method and a double-closed-loop digital intelligent coagulation control method. Among them, the coagulant coagulation method includes:

[0054] S1: Coagulant mixing process: The coagulant is added through the chemical dosing pipe 11, and the flow rate of the shunt pipe 5 is controlled by the shunt regulating valve 9, so that the coagulant can quickly diffuse into the raw water in the mixing pipe 4; the mixing intensity G value in the coagulant mixing process is ≥600 - 1000 s -1 and the residence time T < 0.2 s; correspondingly, the guide vane 12 in this solution is spiral, the extending direction of the port of the chemical dosing pipe 11 is the same as the water flow direction in the mixing pipe 4, and a diffusion cone plate 20 is arranged at the gap at the port of the chemical dosing pipe 11, and the tip of the diffusion cone plate 20 faces the port of the chemical dosing pipe 11; such a setting enables the liquid medicine sprayed from the chemical dosing pipe 11 to quickly diffuse under the action of the diffusion cone plate 20 and achieve rapid mixing of the coagulant under the action of the spiral guide vane 12; the coagulant mixing process uses the flow velocity power to achieve hydraulic mixing, and the mixing intensity G value and the residence time T value of this process can be calculated through the flow velocity and the structural parameters of the mixing pipe 4;

[0055] S2: Coagulant partial destabilization and complete destabilization process: By controlling the rotation speed of the permanent magnet stirring motor 15, the coagulant is subjected to a combined mixing of stirring and water power in the upper mixing chamber 2, the coagulant is quickly hydrolyzed, and the impurity colloid particles are destabilized. Then, under the mixing action of the thrust impeller 14, the impurity colloid particles are completely destabilized in the draft tube 1; the mixing intensity G value in the coagulant partial destabilization and complete destabilization process is ≥3000 s -1 and the residence time T < 0.2 s; specifically, the mixing intensity G value of this process can be calculated through the rotation speed of the permanent magnet stirring motor 15, and the residence time T value can be calculated through the flow velocity, the structural parameters of the upper mixing chamber 2 and the draft tube 1;

[0056] S3: Coagulant orthokinetic flocculation process: Through the design of the structural parameters of the draft tube 16, the fluid generates an axial flow and an axial circulation in the draft tube 16 under the action of the thrust impeller 14, and then intersects and converges with the radial flow generated by the Venturi tube 7. The water body makes a three-dimensional flow state in the lower mixing chamber 3, forming a high-intensity mixing condition and replacing Brownian motion to ensure that the destabilized impurity colloid particles quickly aggregate and the flocs present a state of small particles that are not easily broken; the mixing intensity G value in the coagulant orthokinetic flocculation process is ≤2000 s -1 and the residence time T ≥ 6 s; specifically, the mixing intensity G value of this process can be calculated through the rotation speed of the permanent magnet stirring motor 15, and the residence time T value can be calculated through the flow velocity and the structural parameters such as the volume of the draft tube 16.

[0057] The mixing intensity G value of this solution is adjustable; the hydrodynamic + mechanical stirring power obtained by the shunt mixing technology realizes strong and rapid mixing in a small-volume container; among them, the hydrodynamic uses the fluid velocity detected by the velocity detector, and the flow rate is adjusted by the flow control valve. The mixing intensity G value generated by the hydraulic stirring power is adjustable. The permanent magnet stirring motor 15 uses a variable frequency motor, and the speed regulation range is 200 - 600 revolutions per minute; the residence time T value is adjustable. If the rated inlet water flow rate < 70% during the actual operation of the mixer, the fluid velocity of the shunt pipe 5 will be too slow, resulting in a decrease in the mixing intensity and an extension of the residence time, which cannot meet the coagulant coagulation mechanism and the strong and rapid mixing requirements during the mixing process; therefore, a velocity detector is used to detect the flow velocity of the mixing chamber 2 on the shunt pipe 5, and the water flow rate of the flow control valve is adjusted according to the flow velocity to meet the strong and rapid mixing requirements during the coagulant mixing process; so under the condition of changing inlet water flow rate, the residence time can still meet the requirements of the coagulant coagulation mechanism; the mixing effect is not affected by the change of water volume, and the mixer has strong adaptability to changes in external environmental factors.

[0058] In summary, the G value and T value during the coagulant coagulation process of this solution can be adjusted by the opening degree of the shunt regulating valve 9 and the rotation speed of the permanent magnet stirring motor 15. Then, through the change of the flowing current response value (mixing effect), the rotation speed of the permanent magnet stirring motor 15 is reversely adjusted to meet the requirements of the mixing intensity G value and the residence time T value required for coagulant mixing, deflocculation, and hetero-flocculation, so as to facilitate the realization of the GT optimized combination operation.

[0059] The double-closed-loop digital intelligent coagulation control method includes:

[0060] A1: Set the parameter range of the flow velocity of the shunt pipe 5, the parameter range of the rotation speed of the permanent magnet stirring motor 15, the parameter range and the optimal value of the flowing current response value, and the initial dosage of the coagulant;

[0061] A2: According to the change of the velocity tester 10, control the shunt regulating valve 9 to automatically adjust until the flow velocity of the shunt pipe 5 is stable within the corresponding parameter range;

[0062] A3: Monitor the change of the flowing current response value, control the rotation speed of the permanent magnet stirring motor 15 to automatically adjust within the corresponding parameter setting range until the flowing current response value is closest to the optimal value to the greatest extent. If the flowing current response value is within the corresponding parameter setting range at this time, the execution ends; otherwise, execute step A4;

[0063] A4: When the flowing current response value is higher than the upper limit of the parameter setting range, control the automatic dosing device to reduce the dosage of the coagulant until the flowing current response value changes dynamically, and return to step A3; when the flowing current response value is lower than the lower limit of the parameter setting range, execute step A5;

[0064] A5: When the influent flow rate is greater than the rated influent flow rate or when the raw water turbidity is greater than the normal turbidity, step A6 is executed; when both the temperature and turbidity of the raw water are respectively lower than the normal temperature and normal turbidity, step A7 is executed; when the pH value of the raw water is greater than 8, step A8 is executed;

[0065] A6: Control the automatic chemical dosing equipment to increase the dosage of the coagulant until the flowing current response value shows dynamic changes, and then return to step A3;

[0066] A7: First return to step A3, and after step A3 is completed, if the flowing current response value is still lower than the lower limit of the parameter setting range, then execute step A6;

[0067] A8: Add carbon dioxide to the raw water until the pH value of the raw water is not greater than 8; or reduce the lower limit value of the parameter setting range until the flowing current response value is within the new parameter setting range; and then return to step A3.

[0068] Among them, step A1 specifically includes: the parameter range of the flow rate of the shunt pipe 5 is 1.2 - 1.5 m / s. When the equipment is operating, if the flow rate of the shunt pipe 5 exceeds 1.5 m / s, the water inlet resistance of the main water inlet pipe 6 will be generated. Therefore, the shunt regulating valve 9 needs to be automatically adjusted to reduce the flow rate; when the flow rate of the shunt pipe 5 is lower than 1.2 m / s, the hydraulic mixing effect in the mixing pipe 4 will be affected. Therefore, the shunt regulating valve 9 needs to be automatically adjusted to increase the flow rate so that the flow rate of the shunt pipe 5 is always within the set parameter range; according to the change of the flowing current response value, considering external factors such as flow rate change, low temperature and low turbidity that affect the mixing effect, and the influence of mixing intensity and residence time on the mixing effect and the change of the flowing current response value, the rotational speed parameter range of the permanent magnet stirring motor 15 is 300 - 520 r / min; considering the relationship between the pH value and the flowing current response value and the change of the pH value, on the premise of ensuring the coagulation effect, the parameter is set to -60 - -10; it should be noted that the flowing current response value is used as the colloid polymerization sedimentation effect (mixing effect), and the best mixing effect is when the flowing current response value = ±0. However, according to the relationship between the flowing current response value and the pH value, it is theoretically impossible to achieve because the pH value of the raw water is uncontrollable. According to the actual operation, the upper limit of the defined flowing current response value is -10 and the lower limit is -60, and the optimal value of the flowing current response value is set in between; when the pH value of the raw water > 8, after adding carbon dioxide to reduce the pH value to 7.6, the flowing current response value can be adjusted to ±0, which means that the ± charges in the water can be fully fused and offset, and the drug effect can be exerted to 100%; therefore, when the quality of the raw water is normal, the flowing current response value is generally controlled between -10 and -40; when the quality of the raw water changes or the pH value > 8, the flowing current response value is generally controlled between -20 and -60. When the equipment is operating, when the flowing current response value is higher than the upper limit, the dosage of the coagulant is automatically reduced; when the flowing current response value is lower than the lower limit, the dosage of the coagulant is automatically increased; on this premise, the turbidity of the sedimentation tank effluent can be stably below 1 NTU for a long time, and even can be stably below 0.3 NTU for a long time. The backwashing frequency of the filter tank can be extended by more than one time, water can be saved by more than 50%, emissions can be reduced by more than 50%, the power consumption for producing 1000 tons of water can be reduced by 5%, and the drug consumption for producing 1000 tons of water can be reduced by 30% (compared with the mechanical mixing tank), and at the same time, the operation and maintenance cost of the filter tank is reduced.

[0069] This solution adopts a double - closed - loop digital intelligent coagulation control method. Among them, the first closed - loop is: by adjusting the flow rate of the shunt pipe 5 and the rotational speed of the permanent magnet stirring motor 15, the shunt step - by - step coagulation device is adjusted to the best hydraulic conditions and the best residence time that meet the requirements of the coagulant coagulation mechanism, and on the basis of the best hydraulic conditions and the best residence time, GT optimization combination operation is carried out.

[0070] The second closed loop is as follows: on the basis of the former achieving the best mixing efficiency, by timely adjusting the dosage of the coagulant, the optimal dosage of the coagulant per thousand tons of water is finally determined to achieve the best mixing effect; the two closed-loop controls overlap with each other, have the same goal, but play their respective roles independently, with a clear causal relationship, being safe, reliable, simple and easy to implement; enabling the efficacy of the coagulant to be fully exerted to the extreme and saving the drug consumption to the greatest extent; solving the problem of the great limitation of the existing coagulation control technology that simply relies on adjusting the dosage of the coagulant to change the coagulation effect, and realizing the goals and requirements of improving quality, increasing efficiency, reducing consumption and emissions in the water treatment industry in a real sense.

[0071] According to the application practice experience and the requirements of the water treatment mixing effect, in order to avoid the asynchronous feedback of the electronic signal and the coagulant dosage signal, which may cause frequent adjustment of the coagulant dosing equipment, resulting in unsafe factors such as equipment damage and malfunction, this solution abandons the typical comparison method of the response value and the set value commonly used in existing water plants, and designs a method of adjusting the output of the dosing amount according to a certain control strategy. A method of adjusting the safe area of the flowing current response value is designed, and within this area, the automatic dosing equipment does not make any adjustment to the dosing amount, so that the automatic dosing equipment does not respond to frequent adjustments due to the small and frequent changes of the flowing current response value, ensuring water quality and safe operation; in addition, under the condition of the same source water quality in the same water plant, the coagulation control can be carried out by means of a flowing current sensor 19 driving N sets of shunt step-by-step coagulation devices, that is, the data of the accurate coagulant dosage per thousand tons of water determined by a second closed loop is transmitted to the control programs of other automatic dosing equipment in real time, and the coagulation control is carried out in a proportional dosing manner.

[0072] To sum up, through the coagulant coagulation method and the double closed-loop digital intelligent coagulation control method, this solution not only ensures the hydraulic conditions required for the best mixing effect, but also accurately determines the optimal dosage of the coagulant; and the optimal dosage can be quickly and accurately obtained through a certain period of trial operation, so that the efficacy of the coagulant is exerted to the extreme and the drug consumption is saved to the greatest extent; at the same time, under the influence of various factors such as the source water quality and water flow changes in the water inlet pipe 6, adaptive adjustments can be made to ensure the effluent water quality.

Claims

1. A split-flow and step-by-step coagulation device, characterized in that: It comprises an upper mixing chamber and a lower mixing chamber connected through a guide tube, wherein the upper mixing chamber is connected to a diverter pipe through a mixing tube, the diverter pipe is connected to a water inlet pipe, one side of the lower mixing chamber is connected to the water inlet pipe through a venturi tube, and the other side of the lower mixing chamber is connected to a water outlet pipe; The venturi tube is provided with a shunt regulating valve, the shunt pipe is provided with a flow rate tester, the mixing tube is provided with a dosing pipe, the dosing pipe is connected to an automatic dosing device, a guide plate is provided in the mixing tube, a stirring impeller and a thrust impeller are respectively provided in the upper mixing chamber and the guide cylinder, the stirring impeller and the thrust impeller are both connected to the permanent magnet stirring motor by transmission, a guide pipe connected to the guide cylinder is provided in the lower mixing chamber, an inlet pH sensor, a turbidity sensor and a flow sensor are provided on the water inlet pipe, and an outlet pH sensor and a flow current sensor are provided on the water outlet pipe; The diversion regulating valve, flow rate tester, automatic dosing equipment, permanent magnet stirring motor, inlet pH sensor, outlet pH sensor, turbidity sensor, flow sensor and flow current sensor are all electrically connected to the digital intelligent coagulation control system; The guide plate is spiral-shaped, the extension direction of the port of the dosing tube is the same as the direction of water flow in the mixing tube, a diffusion cone plate is arranged in the gap at the port of the dosing tube, and the cone tip of the diffusion cone plate is arranged facing the port of the dosing tube; The diverter regulating valve is arranged at the middle throat of the venturi tube, a plurality of diverter holes are opened on the gate plate of the diverter regulating valve, the flow rate tester is arranged at the connecting end of the diverter tube and the mixing tube, and 2.5 times the sum of the cross-sectional areas of the plurality of diverter holes is equal to the cross-sectional area of ​​the diverter tube.

2. The flow-dividing and step-by-step coagulation device according to claim 1, characterized in that: The digital intelligent coagulation control system comprises: A regulating valve actuator, an automatic dosing actuator and a motor actuator electrically connected to the diversion regulating valve, the automatic dosing device and the permanent magnetic stirring motor respectively, wherein the regulating valve actuator, the motor actuator and the flow rate tester are all electrically connected to the first PLC controller; A flow current controller electrically connected to the flow current sensor, wherein the flow current controller is electrically connected to the first PLC controller and the PDI controller respectively, and the PDI controller is electrically connected to the automatic dosing actuator.

3. The flow-dividing and step-by-step coagulation device according to claim 1, characterized in that: An automatic exhaust valve is arranged on the top of the upper mixing chamber.

4. A digital intelligent coagulation control method using the split-flow and step-by-step coagulation device according to any one of claims 1 to 3, characterized in that: The invention comprises a coagulant coagulation method, the steps of which are: S1: Coagulant mixing process: Coagulant is added through the dosing pipe, and the flow rate of the diversion pipe is controlled by the diversion regulating valve, so that the coagulant is quickly diffused into the source water in the mixing pipe; S2: Partial and complete destabilization process of coagulant: By controlling the speed of the permanent magnet stirring motor, the coagulant is mixed in the upper mixing chamber by a combination of stirring and water power, the coagulant is rapidly hydrolyzed, and the impurity colloidal particles are destabilized. Then, under the mixing action of the thrust impeller, the impurity colloidal particles are completely destabilized in the guide tube; S3: Coagulant heterogeneous flocculation process: By designing the structural parameters of the guide tube, the fluid is acted upon by the thrust impeller to generate axial flow and axial circulation in the guide tube, which then intersects and merges with the radial flow generated by the Venturi tube. The water body is made to flow in a three-dimensional state in the lower mixing chamber, forming a high-intensity mixing condition and replacing the Brownian motion, ensuring that the destabilized impurity colloid particles are quickly aggregated and the flocs are in a state of small particles that are not easily broken.

5. The digital intelligent coagulation control method of the split-flow and step-by-step coagulation device according to claim 4 is characterized in that: The mixing intensity G value of the coagulant mixing process is ≥600-1000s‾¹, and the residence time T is <0.2s; the mixing intensity G value of the coagulant partial destabilization and complete destabilization process is ≥3000s‾¹, and the residence time T is <0.2s; the mixing intensity G value of the coagulant anisotropic flocculation process is ≤2000s‾¹, and the residence time T is ≥6s.

6. A digital intelligent coagulation control method using the split-flow and step-by-step coagulation device according to claim 4, characterized in that: The invention comprises a double closed-loop digital intelligent coagulation control method, the steps of which are: A1: Set the parameter range of the flow velocity of the diverter pipe, the parameter range of the permanent magnetic stirring motor speed, the parameter range and optimal value of the streaming current response value, and the initial dosage of the coagulant; A2: According to the changes of the flow rate tester, the flow regulating valve is controlled to automatically adjust until the flow rate of the flow pipe is stabilized within the corresponding parameter range; A3: monitor the change of the flowing current response value, control the speed of the permanent magnet stirring motor to automatically adjust within the corresponding parameter setting range, until the flowing current response value is close to the optimal value to the maximum extent. If the flowing current response value at this time is within the corresponding parameter setting range, the execution ends, otherwise, execute step A4; A4: When the flowing current response value is higher than the upper limit of the parameter setting range, the automatic dosing device is controlled to reduce the dosage of the coagulant until the flowing current response value changes dynamically, and the process returns to step A3; when the flowing current response value is lower than the lower limit of the parameter setting range, step A5 is executed; A5: When the inlet flow rate is greater than the rated inlet flow rate or when the turbidity of the source water is greater than the normal turbidity, execute step A6; when the temperature and turbidity of the source water are lower than the normal temperature and the normal turbidity respectively, execute step A7; when the pH value of the source water is greater than 8, execute step A8; A6: Control the automatic dosing device to increase the dosage of the coagulant until the streaming current response value changes dynamically, and return to step A3; A7: Return to step A3 first, and after step A3 is completed, if the flowing current response value is still lower than the lower limit of the parameter setting range, execute step A6; A8: Add carbon dioxide to the source water until the pH value of the source water is no more than 8; or reduce the lower limit of the parameter setting range until the flow current response value is within the new parameter setting range; and return to step A3.

7. The digital intelligent coagulation control method of the split-flow and step-by-step coagulation device according to claim 6 is characterized in that: Step A1 specifically includes: the parameter range of the flow velocity of the diversion pipe is 1.2~1.5m / s; the parameter range of the speed of the permanent magnet stirring motor is 300~520 r / min; the parameter range of the flow current response value when the source water quality meets the standard is -40~-10.

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