CN207645874U - A kind of coagulation automatic dosing control system - Google Patents

A kind of coagulation automatic dosing control system Download PDF

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CN207645874U
CN207645874U CN201721418101.6U CN201721418101U CN207645874U CN 207645874 U CN207645874 U CN 207645874U CN 201721418101 U CN201721418101 U CN 201721418101U CN 207645874 U CN207645874 U CN 207645874U
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control system
output end
sewage
phosphorus
mixer
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吴乾元
胡洪营
王众众
龚靖婷
郭玉梅
郭昉
林阳
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KUNMING DIANCHI WATER Co Ltd
Shenzhen Graduate School Tsinghua University
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KUNMING DIANCHI WATER Co Ltd
Shenzhen Graduate School Tsinghua University
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Abstract

The utility model discloses a kind of coagulation automatic dosing control systems, including:Feedforward control system, PLC control system, feedback control system, adding of agent pump, mixer and filtering ponds;Feedforward control system includes flowmeter and the first orthophosphates on-line monitoring analyzer, is set to sewage output end;Feedback control system includes that the second orthophosphates monitors analyzer on-line, is set to the filtering ponds output end;The input terminal of PLC control system is connect with feedforward control system, feedback control system, and output end is connected with adding of agent pump;The output end of adding of agent pump is connect with the mixer, and mixer is connect with filtering ponds.This system by using feedforward and feedback multiplex control system, other interference influence caused by system in timely compensation correction coagulation administration system, improve the control accuracy and accuracy of system, the stably reaching standard of water outlet total phosphorus concentration has been effectively ensured, while having improved automation technolo level and reducing operational management cost.

Description

Automatic coagulation dosing control system
Technical Field
The utility model relates to a sewage treatment field especially relates to a thoughtlessly congeal automatic reagent feeding control system.
Background
The domestic town sewage treatment plants generally adopt a coagulation/micro-flocculation filtration process to carry out advanced treatment on the phosphorus in the sewage. The addition amount of the coagulant is the largest influence factor of chemical phosphorus removal, and how to control the addition amount according to the real-time change of the actual water quality and water quantity of the sewage is increasingly paid attention and paid attention to in the engineering field. The coagulation effect is influenced by the concentration and flow rate of the phosphate of the inlet water, the type of the coagulant, the adding amount of the coagulant and the adding position, and the coagulant adding amount is controlled by manual experience, so that the phosphate of the outlet water is difficult to stably reach the standard, and the medicament is wasted, thereby increasing the process operation cost. Therefore, establishing an automatic dosing control system based on the actual water quality and water quantity change of the sewage is of great significance for guiding the actual production of sewage treatment.
In practical application, because the feedforward system is open-loop control and has no feedback effect of controlled amount, the influence of other interference in the system after dosing on the system cannot be controlled, and the stable standard of the total phosphorus of the effluent is difficult to ensure.
SUMMERY OF THE UTILITY MODEL
In order to solve the problems, the utility model provides a coagulate automatic reagent feeding control method and system, it can the accurate control add the dose, effectively guarantees to go out stable up to standard of water total phosphorus concentration, improves the automatic level of technology and reduces the operation administrative cost simultaneously.
The utility model provides a thoughtlessly congeal automatic reagent feeding control system, include: a feed-forward control system, a PLC control system, a feedback control system, a medicament feeding pump, a mixer and a filter tank; the feed-forward control system comprises a flowmeter and a first phosphate online monitoring analyzer, and is arranged at the sewage output end; the input end of the flow meter is connected with the sewage output end, and the output end of the flow meter is connected with the input end of the PLC control system and used for measuring the sewage flow at the sewage output end; the input end of the first orthophosphate on-line monitoring analyzer is connected with the sewage output end, and the output end of the first orthophosphate on-line monitoring analyzer is connected with the input end of the PLC control system and is used for measuring the influent phosphorus concentration of the sewage output end; the output end of the PLC control system is connected with the input end of the medicament feeding pump, and the PLC control system calculates the required medicament feeding amount by using an exponential function model and transmits the required medicament feeding amount to the medicament feeding pump; the feedback control system comprises a second orthophosphate on-line monitoring analyzer which is arranged at the output end of the filter tank; the input end of the second orthophosphate on-line monitoring analyzer is connected with the output end of the filtering tank, and the output end of the second orthophosphate on-line monitoring analyzer is connected with the input end of the PLC control system and is used for measuring the phosphorus concentration of the effluent at the output end of the filtering tank; the output end of the medicament feeding pump is connected with the mixer; and sewage is output from the sewage output end, flows into the mixer, flows into the filtering tank and is filtered to discharge water.
The utility model has the advantages that: the system adopts a feedforward-feedback composite control system to compensate and correct the influence of other interferences in the coagulation dosing system on the system in time, thereby effectively improving the control precision and accuracy of the system, effectively ensuring the stable standard reaching of the effluent phosphorus concentration, improving the process automation level and reducing the operation management cost.
Drawings
Fig. 1 is a schematic frame diagram of an embodiment of the coagulation automatic drug feeding control system of the present invention.
Fig. 2 is a schematic flow chart of the coagulation automatic dosing control method according to an embodiment of the present invention.
Fig. 3 is a fitting curve of different influent phosphorus concentrations of the secondary effluent of a sewage plant according to an embodiment of the present invention.
Fig. 4 is a fitting curve of different water phosphorus concentrations of water for laboratory water distribution according to an embodiment of the present invention.
Fig. 5 is a diagram of fitting parameters of an exponential function model according to an embodiment of the present invention and a variation of phosphorus concentration in secondary effluent of a sewage plant.
Fig. 6 is a graph of the variation of the fitting parameters of the exponential function model and the phosphorus concentration of the laboratory water distribution according to an embodiment of the present invention.
Detailed Description
The present invention is described in further detail below with reference to specific embodiments and with reference to the attached drawings, it should be emphasized that the following description is merely exemplary and is not intended to limit the scope and application of the present invention.
Fig. 1 is a schematic frame diagram of a coagulation automatic drug-adding control system according to an embodiment of the present invention, the coagulation automatic drug-adding control system includes: a feedforward control system consisting of a flowmeter and a first orthophosphate on-line monitoring analyzer, a PLC control system, a feedback control system consisting of a second orthophosphate on-line monitoring analyzer, a medicament feeding pump, a mixer and a filter tank.
The feed-forward control system is arranged at the sewage output end, the input end of the flowmeter is connected with the sewage output end, and the output end of the flowmeter is connected with the input end of the PLC control system and used for measuring the sewage flow at the sewage output end; the input end of the first orthophosphate on-line monitoring analyzer is connected with the sewage output end, and the output end of the first orthophosphate on-line monitoring analyzer is connected with the input end of the PLC control system and used for measuring the concentration of the influent phosphorus at the sewage output end.
The feedback control system is arranged at the output end of the filtering tank, the input end of the second orthophosphate on-line monitoring analyzer is connected with the output end of the filtering tank, and the output end of the second orthophosphate on-line monitoring analyzer is connected with the input end of the PLC control system and used for measuring the concentration of the phosphorus in the outlet water at the output end of the filtering tank.
The output end of the PLC control system is connected with the input end of the medicament feeding pump, and the output end of the medicament feeding pump is connected with the mixer. The sewage is output from the sewage output end, flows into the mixer and then flows into the filtering tank, and the water is discharged after filtering.
Based on the system, the coagulation automatic dosing control can be realized, and the control method of one embodiment of the system has a flow diagram as shown in FIG. 2 and comprises the following steps:
s1, determining sewage flow Q and influent phosphorus concentration P at a sewage output end by adopting a flowmeter and a first orthophosphate on-line monitoring analyzer in a feedforward control systeminAnd transmitting the data result to the PLC control system.
S2, the PLC control system controls the system to control the flow rate of sewage Q and the concentration of phosphorus in the inlet water PinAnd the phosphorus concentration target value P of the effluenteAnd calculating the required dosage and transmitting the dosage to a medicament dosing pump.
The required dosage is calculated, the control precision of the dosage depends on the accuracy of the established mathematical model and the selected parameters, particularly the established mathematical model, and the selection of a proper model can ensure the dosing precision and the stability of the phosphorus concentration of the effluent.
The concentration of phosphorus in the inlet water is one of the important influence factors in the coagulation process, and the adding amount of the coagulant is determined to a certain degree, so that the adding ratio β of the inlet water coagulant is introduced (the coagulant is preferably polyaluminium chloride, the mol ratio of the adding amount of aluminum element to the total phosphorus in the inlet water,mol/mol)。
with the increase of the adding ratio β of the water-entering coagulant, the removal rate of phosphorus is continuously improved, but the change rate of the removal rate is continuously reduced, namely when the concentration of phosphorus in water is continuously reduced, the removal difficulty of chemical phosphorus removal is continuously increased, which is related to chemical equilibrium and a solubility product constant.
In the chemical phosphorus removal process, due to the difference of the concentration of the inlet water phosphorus, the relation curve of the concentration of the outlet water phosphorus and the adding amount of the coagulant shows three different areas, which are respectively: a metering reaction zone (linear relationship zone), an equilibrium reaction zone (stability zone) and a transition zone therebetween. The three regions are: when the concentration of the phosphorus in the inlet water is higher, the phosphorus removal rate is linearly related to the coagulant adding amount, namely the metering reaction zone; when the phosphorus degree of the inlet water is lower, the coagulant addition amount required for removing phosphorus of unit concentration is obviously higher than that of the metering reaction zone, and the phosphorus concentration of the outlet water tends to be balanced, namely the equilibrium reaction zone; when the concentration of the phosphorus in the inlet water is between the two, the phosphorus removal rate and the coagulant adding amount present a more complex curve relationship, and the curve relationship is between the linear relationship and the equilibrium relationship, namely the transition zone.
In actual production, when the mathematical model is established, the concentration of phosphorus in inlet water, the adding ratio β and the concentration of phosphorus in outlet water need to be comprehensively considered, so that the following exponential function model is selected:
wherein,the phosphorus concentration (mg/L) of inlet water;
a phosphorus concentration target value (mg/L) of effluent;
β, coagulant adding ratio;
Ka、Kb: dimensionless empirical constants.
According to the exponential function model, secondary effluent of a sewage plant and laboratory water distribution are respectively used as water inlet sources for carrying out experiments, the target value of the effluent phosphorus concentration is set to be 0.3mg/L, different inlet phosphorus concentrations are fitted, polyaluminium chloride (PAC) is adopted as a coagulant, unitary nonlinear regression calculation is carried out on experimental data, and fitting of a relation model between the inlet phosphorus concentration and the outlet phosphorus concentration and the PAC addition ratio β is obtained.
For the second-stage effluent phosphorus, the fitting curves of different influent phosphorus concentrations are shown in fig. 3, and the obtained fitting results are shown in the following table 1:
TABLE 1 sewage plant secondary effluent exponential function model fitting results
For laboratory-distributed phosphorus, a fitting curve of phosphorus concentrations of different water inlets is shown in fig. 4, and the obtained fitting results are shown in the following table 2:
TABLE 2 laboratory Water distribution index function model fitting results
From the results of tables 1 and 2, it can be seen that: correlation R of fitting result2Are all high (0.930, 0.978, 0.986, 0.963, 0.955, 0.993, 0.969, 0.979; 0.993, 0.986, 0.966), and the residual sum of squares is also small, indicating that the fitting effect of the exponential function model is good and the fitting degree is high.
The fitting results obtained by comparing different water inlet phosphorus concentrations show that when the water inlet phosphorus concentration is close to 1 mg/L, the obtained fitting curves are relatively close no matter water distribution in a laboratory or secondary water outlet of an actual sewage plant, and the fitting parameter K isa、KbAre substantially similar. As can be seen from fig. 3 and 4, for different feed water phosphorus concentrations, lower concentrations may require higher PAC dosing ratios to achieve the same phosphorus removal rate.
Fitting parameter K of exponential function modela、KbThe phosphorus concentration of the secondary effluent of the sewage plant and the phosphorus concentration of the laboratory water distribution are shown in fig. 5 and fig. 6. As can be seen, for the exponential function model,key parameter K of modela、KbThe change along with the change of the phosphorus concentration of the inlet water is relatively small, and when the phosphorus concentrations of the inlet water of different batches are close, the difference of the parameters of the obtained fitting curve is smaller.
According to the analysis result, the fitting parameters of the exponential function model are relatively stable, and the model can accurately simulate the relation between the coagulant adding amount and the water quality of inlet water and outlet water.
In practical engineering application, besides the water quality parameter of the inflow water flow, due to the error between theory and practice, the model fitting parameter needs to be corrected through practical operation data, and the exponential function model is analyzed and corrected as follows:
wherein a and b are dimensionless empirical constants; qPAC: liquid PAC dosage; k: the correction coefficient is more than or equal to 0.5 and less than or equal to 1.5; q: inflow (m)3/h);The phosphorus concentration target value of the effluent water;the phosphorus concentration of the inlet water; λ: the specific gravity of the liquid medicine; n: percentage of liquid medicine.
Selecting the optimal fitting parameter, K, according to the fitting resulta=1.07、Kb-0.157, which is substituted into the exponential function model:
combining the formula (3) with the water inflow, correcting the model fitting parameters, analyzing and correcting the formula (3) according to the formula (2), and obtaining the following result:
wherein Q isPAC: calculated liquid PAC dosage (m)3/h);
K: a correction coefficient (0.5-1.5);
λ: specific gravity (g/cm) of the liquid medicine3And may be 1 within 5%);
n: percentage of liquid medicine (0-100%).
The measured sewage flow and the measured influent phosphorus concentration CPinThe phosphorus concentration target value C of the effluentPeSubstituting into formula (4) can calculate the PAC dosage.
And S3, the medicament feeder pump feeds the medicament into the mixer according to the medicament feeding amount calculated in the step S2.
Application example: taking a deep dephosphorization treatment process by adopting a coagulation-filtration technology in a certain sewage treatment plant as an example. When manual dosing and a coagulation automatic dosing system are adopted, the phosphorus concentration target value of the effluent is 0.2 mg/L. The total phosphorus concentration of the effluent after manual dosing is maintained at 0.3mg/L, the total phosphorus concentration of the effluent of the coagulation dosing system is mostly lower than 0.2mg/L, and the total phosphorus concentration of the effluent can be kept stable. When manual dosing is adopted, the PAC dosage of unit total phosphorus concentration (TP) removal amount fluctuates within 10-20mg Al/mg P, and the average removal rate of TP is high; after the coagulation automatic dosing system is adopted, the PAC dosage per unit TP removal amount is distributed below 10mgAl/mg P in a large amount, and the PAC dosage per unit TP removal amount is obviously reduced. Therefore, the automatic control system for adding the coagulant not only realizes the purpose of relatively stabilizing the quality of the effluent total phosphorus, but also effectively saves the adding amount of the coagulant.
In order to further accurately control the phosphorus concentration of the outlet water at the water outlet end of the filter tank to reach the set target value, the following steps can be further carried out.
S4, adopting feedback controlThe second orthophosphate on-line monitoring analyzer in the system determines the phosphorus concentration P of the effluent at the output end of the filter tankoutAnd transmitting the data result to the PLC control system.
S5, the PLC control system obtains a result P according to the data of the effluent phosphorus concentrationoutAnd a target value PeThe deviation between the two is fed back and adjusted, and the required second dosage is calculated.
The feedback control system adopts a PID feedback controller, the feedback regulation adopts PID regulation, the effluent phosphorus concentration through online monitoring is taken as a feedback signal, and in the feedback regulation, the feedback regulation mainly comprises four parameters to be determined, which are respectively: a proportionality coefficient, an integral coefficient, a derivative coefficient, and a run length. There are multiple methods about the definite of above-mentioned parameter, the utility model discloses a trial and error method, the basic process of trial and error method is: firstly, determining a group of parameters according to actual engineering experience, enabling a feedback system to perform trial operation, simultaneously recording the dosage of a medicament and the actual effluent phosphorus concentration, analyzing the variation trend of the effluent phosphorus concentration along with the dosage of the medicament, observing whether the concentration of the effluent phosphate meets the requirement, slightly modifying related parameter values aiming at the existing problems if the concentration of the effluent phosphate cannot meet the requirement, repeatedly modifying related parameters through the effect of the trial operation of the analysis system, repeating the process in such a way until the feedback system achieves the expected operation effect, and finally determining all parameter values.
According to the determined parameter value, the phosphorus concentration P of the effluent is determinedoutA set value PeAnd substituting, and calculating the required second dosage.
And S6, the medicament feeding pump feeds medicament into the mixer according to the second medicament feeding amount.
Through the feedback adjustment of the feedback control system, the second dosage is calculated, the requirement that the concentration of the discharged water phosphorus reaches the target value can be more accurately ensured, and the stability is kept.
The utility model discloses established the automatic control system of offeing medicine based on the actual quality of water of sewage and the change of water yield, effectively overcome the influence of unfavorable factors such as the quality of water sudden change of intaking, reduced the dose of throwing, improved production efficiency.
Under the preferable condition, the filtering tank of the utility model adopts an Actiflo sanding high-speed sedimentation tank-D type filtering tank, and the filtering process correspondingly adoptsA model filter tank process.The process combines the micro-sand weighted flocculation and the inclined plate sedimentation, micro-sand is added into the flocculation tank to serve as the core of the floc, and the density of the floc formed by taking the micro-sand as the core is high, so that the floc is easy to separate from water and settle, and the ascending flow rate and the treatment efficiency are improved.Has the advantages of high precipitation speed, high treatment efficiency and strong impact load resistance. The D-type filter tank is a gravity type high-speed filter tank adopting comet type fiber filter materials and has the advantages of high filter speed, high filter precision and large sewage interception capacity. The utility model discloses aThe process design treatment capacity of the filter is 21 ten thousand meters3And d, designing the quality of the outlet water to reach the first-class A standard of GB18918-2002 discharge Standard of pollutants for municipal wastewater treatment plants.
The foregoing is a more detailed description of the present invention, taken in conjunction with the specific/preferred embodiments thereof, and it is not intended that the invention be limited to the specific embodiments shown and described. For those skilled in the art to which the invention pertains, a plurality of alternatives or modifications can be made to the described embodiments without departing from the concept of the invention, and these alternatives or modifications should be considered as belonging to the protection scope of the invention.

Claims (3)

1. The utility model provides a thoughtlessly congeal automatic reagent feeding control system which characterized in that includes: a feed-forward control system, a PLC control system, a feedback control system, a medicament feeding pump, a mixer and a filter tank;
the feedforward control system comprises a flowmeter and a first orthophosphate on-line monitoring analyzer, and is arranged at the sewage output end; the input end of the flow meter is connected with the sewage output end, and the output end of the flow meter is connected with the input end of the PLC control system and used for measuring the sewage flow at the sewage output end; the input end of the first orthophosphate on-line monitoring analyzer is connected with the sewage output end, and the output end of the first orthophosphate on-line monitoring analyzer is connected with the input end of the PLC control system and is used for measuring the influent phosphorus concentration of the sewage output end;
the output end of the PLC control system is connected with the input end of the medicament feeding pump, and the PLC control system calculates the required medicament feeding amount and transmits the required medicament feeding amount to the medicament feeding pump;
the feedback control system comprises a second orthophosphate on-line monitoring analyzer which is arranged at the output end of the filter tank; the input end of the second orthophosphate on-line monitoring analyzer is connected with the output end of the filtering tank, and the output end of the second orthophosphate on-line monitoring analyzer is connected with the input end of the PLC control system and is used for measuring the phosphorus concentration of the effluent at the output end of the filtering tank;
the output end of the medicament feeding pump is connected with the mixer;
and sewage is output from the sewage output end, flows into the mixer, flows into the filtering tank and is filtered to discharge water.
2. The control system of claim 1, wherein the feedback control system is a PID feedback controller.
3. The control system of claim 1, wherein the filtration tank is a tank-a type D process filtration tank.
CN201721418101.6U 2017-10-30 2017-10-30 A kind of coagulation automatic dosing control system Active CN207645874U (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022057121A1 (en) * 2020-09-17 2022-03-24 广东粤海水务股份有限公司 Online dephosphorisation apparatus and method used for sewage treatment
CN114956294A (en) * 2022-06-14 2022-08-30 山东新日电气设备有限公司 Intelligent medicine feeding system and method based on artificial neural network

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022057121A1 (en) * 2020-09-17 2022-03-24 广东粤海水务股份有限公司 Online dephosphorisation apparatus and method used for sewage treatment
CN114956294A (en) * 2022-06-14 2022-08-30 山东新日电气设备有限公司 Intelligent medicine feeding system and method based on artificial neural network
CN114956294B (en) * 2022-06-14 2024-02-09 山东新日电气设备有限公司 Intelligent dosing system and method based on artificial neural network

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