JP2001038343A - Method and apparatus for controlling a water treatment process - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a method of controlling a water treatment process capable of maintaining a stable treated water quality even when the reliability of a driving operation model that determines an operation amount according to the quality of treated water is not sufficient. It is to provide a device. According to the present invention, a set operation amount D of a water treatment process 10 is obtained by a driving operation model 200 based on the quality of water to be treated, and an estimated treatment water quality C is obtained by a simulator 100 based on an actual operation amount D ^* of the water treatment process 10. The actual operation amount D ^* of the water treatment process 10 is obtained by correcting the set operation amount D by the deviation E between the target treatment water quality C and the estimated treatment water quality C ^* determined in the operation amount determination unit 300.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a water treatment process for performing a water treatment operation in a water purification plant or a sewage treatment plant.

[0002]

2. Description of the Related Art Raw water taken from rivers and other water intake sources contains various substances. At a water purification plant, chemicals such as chlorine and coagulants are injected to make the raw water taken into drinking water. ing.

[0003] In a water purification plant, the trihalomethane concentration and turbidity of treated water are set to target values by appropriately controlling operation amounts such as a coagulant injection amount and a chlorine injection amount in coagulation sedimentation treatment and chlorination treatment. The quality of water purification control in a water purification plant directly affects the quality of tap water used by many consumers, and therefore, it is required to increase reliability.

[0004] On the other hand, in a sewage treatment plant as well, it is required to improve the quality of treated water to increase reliability, as in a water treatment plant.

[0005] By the way, since the treatment time in the water treatment process in a water purification plant or a sewage treatment plant is several hours, the feedback control based on the quality of treated water causes a large time delay. For this reason, an operation operation model (coagulant injection model or chlorine injection model) has been introduced that allows the amount of operation of chemicals and return sludge to be appropriately set based on the quality of raw water and sewage to be treated.
Feedforward control has been attempted.

[0006] Feedforward control using a computer for controlling a water purification plant as described above is described in, for example, JP-A-6-296973 and JP-A-9-204218.

In these conventional examples, if a highly reliable driving operation model (such as a chlorine injection amount model) for setting the operation amount can be prepared, feedforward control without time delay can be performed. However, if the reliability of the driving operation model is low, the predetermined treated water quality cannot be achieved, and if the treated water quality is to be maintained at a predetermined level or higher, it is necessary to use feedback control based on the treated water quality.

[0008]

In the prior art, if the reliability of a driving operation model that determines the operation amount based on the quality of the water to be treated flowing into the water treatment process is not sufficient, it is possible to prevent the quality of the treated water from becoming poor. After all, combined use of feedback control is indispensable.

However, even if the feedback control is used, it is unavoidable that the quality of the treated water becomes poor due to the control delay. During this period, it will be difficult to recover the treated water quality.

In general, the treatment time (retention time of raw water or inflowing sewage to-be-treated water) in a water treatment process exceeds several hours, so that the effect is extremely large.

An object of the present invention is to provide a method and an apparatus for controlling a water treatment process capable of maintaining a stable treated water quality even when the reliability of a driving operation model for determining an operation amount according to the quality of treated water is not sufficient. It is in.

[0012]

A feature of the present invention is that a set operation amount of a water treatment process is obtained based on the quality of water to be treated, and an estimated treatment water quality is obtained based on an actual operation amount of the water treatment process. The set operation amount is corrected based on the difference between the target treated water quality and the estimated treated water quality to obtain the actual operation amount of the water treatment process.

According to the present invention, the set operation amount is corrected based on the difference between the estimated treatment water quality obtained from the actual operation amount of the water treatment process and the predetermined target treatment water quality to obtain the actual operation amount of the water treatment process. The set operation amount can be corrected without time delay. Therefore, even if the reliability of the driving operation model that determines the set operation amount based on the quality of the water to be treated is low, the quality of the treated water can be maintained satisfactorily.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

FIG. 1 shows an example in which the present invention is applied to control of a water purification plant.

In FIG. 1, raw water (water to be treated) taken from a water source 1 such as a river is supplied to a water purification plant (water purification process) 10.
It is led to. The water purification plant 10 has a landing well 10A, a mixing pond 10
B, a floc forming pond 10C and a sedimentation pond 10D. The illustration of the filtration pond and the like is omitted.

A flocculant (a chemical, which is an operation target of the present invention) is injected into the floc forming pond 10B by the actuator 8. The quality of the raw water flowing into the water purification plant 10 is measured by the water quality sensor 5a, and the quality of the treated water treated in the water purification plant 10 is measured by the water quality sensor 5b.

Water quality information (water quality data) measured by the water quality sensors 5a and 5b is taken into the information input unit 50 of the process computer 500. The water quality data taken into the information input unit 50 is stored in the database 30.

The simulator 100 simulates the water purification plant 10 using the water quality data (process data) stored in the database 30 to obtain an estimated treated water quality (estimated treated water quality value) C, and supplies the estimated treated water quality C to the operation amount determining unit 300. In addition, the driving operation model 200 uses the raw water quality data (process data) obtained from the database 30 to obtain a set operation amount (operation amount set value) D and provides the operation amount determination unit 300 with the operation amount determination unit 300.

The processing results of the process computer 500 and the data reference of the database 30 are displayed off-line on the display (CRT) 15 by an operation from the keyboard 20 or an operation panel (not shown).

FIG. 2 is a detailed block diagram of an example of the manipulated variable determiner 300.

The setting operation amount D given from the driving operation model 200 and the operation correction amount (operation amount correction value) △ D of the correction calculation unit 30A are added by the addition unit 30B. Adder 30B
, An actual operation amount (actual operation amount) D ^{* of the} water purification plant 10 is obtained and given to the actuator 8 and the simulator 100.

The adder 30C gives a deviation E between the target treated water quality (target treated water quality) C ^* and the estimated treated water quality C given from the simulator 100 to the correction amount calculator 30A. The correction amount calculator 30A outputs an operation correction amount ΔD proportional to the deviation E.

Next, the operation will be described.

A water purification plant (water purification process) 10 performs a water purification process by taking raw water from a water source 1 such as a river.
Water quality data of raw water quality and treated water quality is obtained from the water quality sensor 5a,
5b, and is taken into the process computer 500 by the information input unit 50. Water quality data is stored in the database 30.

The driving operation model 200 is a database 30
Set amount of operation D using raw water quality data stored in
Is calculated. Simulator 100 is a database 30
The water purification plant 10 is simulated using the water quality data stored in the water quality data and the actual operation amount D ^* of the operation amount determination unit 300 to obtain an estimated treatment water quality C. When the operation of the water purification plant 10 is started, the operation amount determination unit 300 is provided to the simulator 100.
The set operation amount D of the driving operation model 200 is given instead of the actual operation amount D ^* .

The set operation amount D of the driving operation model 200 and the estimated water quality C of the simulator 100 are determined by the operation amount determination unit 30.
0 is given. The driving operation model 200 includes raw water quality data (process data) obtained from the database 30.
Is used to obtain the set operation amount, and the obtained operation amount is provided to the operation amount determination unit 300.

The manipulated variable determiner 300 adds the estimated treated water quality C and a predetermined target treated water quality C ^* with the polarity shown in an adder 30C, and calculates a deviation E of the difference E by a correction amount calculator 30A.
Add to The correction amount calculation unit 30A obtains the operation correction amount ΔD and adds it to the addition unit 30B as described later.

The adder 30B adds the set operation amount D and the operation correction amount ΔD with the polarity shown in the drawing, in other words, outputs the actual operation amount D ^* obtained by correcting the set operation amount D by the operation correction amount ΔD. The actual operation amount D ^* of the adding unit 30B is added to the actuator 8 as an output of the operation amount determining unit 300, and the water purification plant 10 is controlled.

The actual operation amount D ^* of the operation amount determination unit 300
Is added to the simulator 100, and the simulator 10
It is used to obtain an estimated treated water quality C of zero.

The process computer 500 has a target treated water quality C ^*.
This process is repeatedly executed until the estimated water quality C matches with the estimated water quality C. A computer process for proceeding with such a control procedure is repeatedly executed online at a cycle of several tens of seconds to several minutes.

The intermediate results of the processing of the process computer 500 and the data reference of the database 30 can also be displayed on the CRT 15 off-line by operating the keyboard 20 or an operation panel (not shown).

Next, details of each component of the process computer 500 will be sequentially described.

First, the information input unit 50 will be described with reference to FIG.

FIG. 3 shows the steps of processing performed by the information input unit 50. In the water quality data reading step 55, the water quality sensors 5a, 5b installed in the water purification process 10
The signal of the water quality data measured in is taken in.

Since the water quality data itself is information having a short cycle of about several tens of msec, in order to reduce the amount of information by converting the data into data averaged in a required cycle, the average data calculation step 60 is performed. Then, the acquired water quality data is averaged over a preset time width and output. In the data output step 65, the averaged water quality data is output to the database 30.

In parallel with these online processes, data can be inputted off-line by input from the keyboard 20. In the water quality data reading step 55, data input from the keyboard 20, for example, water quality data obtained by water quality analysis and the like can be read and output to the data output step 65.

The water quality data processed by the information input unit 50 is stored in the database 30. The database 30 stores not only the water quality data in each processing step of the water purification process 10 but also the operation amount data and the equipment. It also stores data related to the maintenance of the system.

FIG. 4 is a conceptual diagram of the configuration of the simulator 100.

The water purification treatment process 10 comprises several treatment steps. In the case of the coagulation sedimentation rapid filtration treatment which is the most common in water purification treatment, the landing well 10A and the mixing pond 1
OB, floc forming pond 10C, sedimentation pond 10D, and filtration pond 10E are arranged in series.

The simulator 100 has a module configuration corresponding to each of these processing steps, and includes a dynamic characteristic model capable of reproducing a phenomenon in the corresponding processing step. Each module functions independently and exchanges only data input and output with other modules.

For example, the floc formation pond module has a function of simulating the flocking phenomenon of floc generated by the reaction between the turbid component in raw water and the flocculant. The model for this refers to the data in the database 30 and also refers to the calculation output result from the mixing pond module, which is the preceding processing step, as input data. The calculation output result of the floc formation pond module is used as input data to the settling pond module. Each module is composed of several subroutines that share functions.

FIG. 5 shows an example of the processing procedure of the simulator 100.

In the process data reading step 105,
Data necessary for the simulation is read from the database 30 and is made available for calculation. In the operation amount reading step 110, the actual operation amount D ^* obtained by the operation amount determining unit 300 is read.

In the process simulator module execution step 120, the above-described module calculation is performed and output in three steps. The three steps are a process data reference step 125, a process dynamic characteristic model 130, and a model calculation result output step 135.

In the estimated treatment water quality calculation step 150, the result output from the model calculation result output step 135 of the process simulator module execution step 120 is output to the manipulated variable determination unit 30.
Output to 0.

FIG. 6 shows an example of a processing procedure of the driving operation model 200.

In the process data reading step 210,
The raw water quality data and the like necessary for executing the driving operation model are read from the database 30.

In the operation operation model selection step 220, an operation operation model is selected based on the condition of the raw water quality and the like.
For example, in the case of a coagulant injection model for calculating the coagulant injection amount, it is difficult for one model to cope with a wide range of raw water turbidity. Prepare models for turbidity and use them properly. In this case, a model is selected based on a preset raw water turbidity threshold.

In the operation operation model calculation step 230, the set operation amount is calculated based on the latest water quality data read from the database 30 and the selected model. The model here is a physical model based on knowledge of phenomena or a statistical model based on historical data of past operation results (multiple regression equations or neural networks using raw water turbidity, pH, alkalinity, etc. as explanatory variables). Model). Further, a fuzzy rule model or the like based on the empirical knowledge of the operation manager of the water purification process 10 can be applied.

In the calculated manipulated variable check step 240, it is checked whether or not the set manipulated variable D calculated in the driving operation model calculating step 230 is within the upper and lower limit range where the operation can be actually performed. If the operation is out of the upper and lower limiter values, the limiter value is used as the set operation amount.

In the manipulated variable output step 250, the set manipulated variable D
Is output to the manipulated variable determiner 300. In the conventional control using the driving operation model, the set operation amount D is
In the present invention, the set operation amount D is corrected by the operation amount determination unit 300 in the present embodiment.

The manipulated variable determiner 300 is configured as shown in FIG.

The set operation amount D calculated by the driving operation model 200 and the estimated water quality C obtained by the simulator 100 are input. The adding unit 30C adds the target treated water quality C ^* and the estimated treated water quality C, and adds the deviation E to the correction amount calculating unit 30A.

When the deviation E is equal to or less than a predetermined value, the correction amount calculating section 30A sets the operation correction amount ΔD to zero. Therefore,
In this case, the set operation amount D of the driving operation model 200 is added to the actuator 8 without correction as the actual operation amount D ^* .

When the deviation E exceeds a predetermined value, the correction amount calculating section 30A calculates the operation correction amount ΔD and corrects the set operation amount D as follows. The operation correction amount ΔD is calculated by the steepest descent method for the deviation E as shown in the following equation.

[0058]

１D∝− (最 E / ∂D) In the steepest descent method, as shown in Equation 1, the partial differential of the manipulated variable D with respect to the deviation E, that is, the slope is obtained, and the inverse proportional to the slope is obtained. The operation correction amount ΔD is calculated as the sign amount.
Specifically, assuming that the deviation E changes as shown in FIG. 8, when the set operation amount D is Da, the inclination is positive and the operation correction amount ΔD is obtained so as to decrease the operation amount D. ,
In the case of Db, the operation correction amount ΔD is determined so as to increase.

The correction amount calculation unit 30A adds the operation correction amount ΔD obtained in this way to the addition unit 30B and adds the operation amount D to the set operation amount D. That is, the set operation amount D of the driving operation model 200 is corrected by the set operation correction amount ΔD, and is added to the actuator 8 as the actual operation amount D ^* .

Actual manipulated variable D output by manipulated variable determiner 300
^* Is also input to the simulator 100 and the estimated treated water quality C
Is used to calculate

By repeating such an operation, the deviation E
Is not more than a predetermined value.

The above procedure is summarized as a flowchart shown in FIG.

In FIG. 7, a setting operation amount reading step 3
At 10, the set operation amount D is read from the driving operation model 200. In the target treated water quality reference step 320, a preset target treated water quality C ^* is referred to. In the estimated process water quality reading step 330, a predicted value of the estimated process water quality is read from the simulator 100. These reading processes are performed in synchronization with the control cycle of the operation amount.

In the operation correction amount calculating step 340, the operation correction amount ΔD is calculated according to the deviation E between the target treated water quality C ^* and the predicted treated water quality C as described above, and the corrected manipulated variable output step 3 is performed.
At 50, the correction manipulated variable △ D is output to the simulator 100 until the deviation E becomes equal to or less than the predetermined value, and the calculation is repeatedly performed.

In the manipulated variable output step 360, the set manipulated variable D
Is corrected by the operation correction amount ΔD, and the actual operation amount D ^* is output to the actuator 8.

The control of the water purification plant is performed in this manner. The set operation amount obtained from the raw water quality is corrected by the difference between the estimated treated water quality obtained from the actual operation amount of the chemical to be injected and a predetermined target treated water quality. Thus, the set operation amount can be corrected without time delay. Therefore, the quality of the treated water can be maintained satisfactorily even if the reliability of the driving operation model that determines the set operation amount based on the raw water (the quality of the water to be treated) is low.

Although the above-described embodiment describes an example of a water purification process, it is apparent that the present invention can be applied to a sewage treatment process. The amount of operation in the sewage treatment process is the amount of aerated air and returned sludge.

Further, the method of obtaining the correction operation amount based on the deviation between the target treated water quality and the estimated treated water quality is not limited to the steepest descent method, but may be another method.

[0069]

According to the present invention, water treatment is performed by correcting the set operation amount determined based on the quality of the water to be treated by the difference between the estimated treatment water quality determined based on the actual operation amount of the water treatment process and a predetermined target treatment water quality. Since it is the actual operation amount of the process,
The set operation amount can be corrected without time delay. Therefore, even if the reliability of the driving operation model that determines the set operation amount based on the quality of the water to be treated is low, the quality of the treated water can be favorably maintained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a detailed configuration diagram illustrating an example of an operation amount determination unit.

FIG. 3 is a flowchart for explaining the operation of the present invention.

FIG. 4 is a configuration diagram illustrating an example of a simulator.

FIG. 5 is a flowchart for explaining the operation of the present invention.

FIG. 6 is a flowchart for explaining the operation of the present invention.

FIG. 7 is a flowchart for explaining the operation of the present invention.

FIG. 8 is a characteristic diagram for explaining the operation of the present invention.

[Explanation of symbols]

1 ... water source, 5 ... water quality sensor, 8 ... actuator, 10 ...
Water purification process, 15 CRT, 20 keyboard, 30 database, 50 information input unit, 100 simulator, 200
… Driving operation model, 300… Manipulated variable determining unit, 500… Process computer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Naoki Hara 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture F-term in the Omika Plant of Hitachi, Ltd. F-term (reference) 4D062 BA21 CA14 EA03 EA32

Claims (8)

[Claims] 1. A water treatment process for performing a water treatment operation on water to be treated, wherein a set operation amount of the water treatment operation is obtained based on the quality of the water to be treated, and the water quality of the water to be treated and the water treatment are determined. An estimated operation water quality of the water treatment process is obtained based on an actual operation amount of the operation, and the set operation amount is corrected based on a difference between a predetermined target treatment water quality and the estimated operation water quality to obtain an actual operation amount of the water treatment operation. A method for controlling a water treatment process, the method comprising: 2. A water treatment process for performing a water treatment operation on water to be treated, wherein a set operation amount of the water treatment operation is determined based on the quality of the water to be treated, and the water quality of the water to be treated and the water treatment are determined. The estimated operation water quality of the water treatment process is obtained by the actual operation amount of the operation, the correction operation amount is obtained by the gradient of the deviation between the predetermined target processing water quality and the estimated processing water quality, and the set operation amount is obtained by the correction operation amount. A method for controlling a water treatment process, wherein a correction is made to an actual operation amount of the water treatment operation. 3. A water treatment process for adding an operation target to be treated to water to be treated, wherein a set operation amount of the operation target is obtained based on the quality of the treatment water, and the water quality of the treatment water and the operation are determined. Obtain the estimated treated water quality of the water treatment process based on the actual manipulated variable of the object, determine the corrected manipulated variable based on a deviation between a predetermined target treated water quality and the estimated treated water quality, and correct the set manipulated variable with the corrected manipulated variable. A method of controlling the water treatment process, wherein the actual operation amount of the operation target is set to the actual operation amount. 4. A water treatment process for purifying water by injecting a chemical into raw water that has been withdrawn, wherein a set operation amount of the chemical is determined based on the quality of the raw water, and the actual operation amount of the chemical is determined based on the actual operation amount of the chemical. An estimated treatment water quality of the water treatment process is obtained, and the set operation amount is corrected to an actual operation amount of the chemical by a correction operation amount based on a deviation between a predetermined target treatment water quality and the estimated treatment water quality. Water treatment process control method. 5. A means for determining a set operation amount of a water treatment operation according to the quality of the water to be treated, a means for determining an estimated treatment water quality of the water treatment process based on the quality of the water to be treated and the actual operation amount of the water treatment operation. Means for correcting the set amount of operation based on a difference between a predetermined target treated water quality and the estimated treated water quality, and outputting the corrected manipulated variable as an actual manipulated variable of the water treatment operation. 6. A means for determining a set operation amount of a water treatment operation according to the quality of the water to be treated, a means for determining an estimated treatment water quality of the water treatment process based on the quality of the water to be treated and the actual operation amount of the water treatment operation. Means for obtaining a corrected operation amount by a gradient of a deviation between a predetermined target treated water quality and the estimated treated water quality, correcting the set operation amount by the corrected operation amount, and outputting the corrected operation amount as an actual operation amount of the water treatment operation, A control device for a water treatment process, comprising: an actuator for performing a water treatment operation based on the actual operation amount. 7. A process for estimating the water treatment process based on a driving operation model for obtaining a set operation amount of an operation target for performing water treatment according to the quality of the water to be treated, and an actual operation amount of the water to be treated and the operation target. A simulator for obtaining water quality, a correction operation amount is obtained by a deviation between a predetermined target treatment water quality and the estimated treatment water quality, and the set operation amount is corrected by the correction operation amount and output as an actual operation amount of the operation target. A control device for a water treatment process, comprising: an operation amount determining unit that performs a water treatment operation based on the actual operation amount obtained by the operation amount determining unit. 8. In a water treatment process for purifying water by injecting a chemical into raw water that has been taken, an operation model for obtaining a set operation amount of the chemical based on the raw water quality, and an actual operation amount of the raw water quality and the chemical. A simulator for obtaining an estimated treatment water quality of the water treatment process, and an operation amount for correcting the set operation amount by a correction operation amount based on a deviation between a predetermined target treatment water quality and the estimated treatment water quality and outputting the corrected operation amount as an actual operation amount of the chemical. A control apparatus for a water treatment process, comprising: a determination unit; and an actuator that performs an injection operation of the chemical based on the actual operation amount obtained by the operation amount determination unit.