Chemical injection support system, chemical injection support method, and program

Abstract

To provide support for more appropriate injection of a chemical in a water treatment plant.SOLUTION: A chemical injection support system includes: a water quality reaction model predicting part for predicting the water quality of treatment water by a water quality reaction model obtained by modeling a reaction caused by a chemical to be injected into raw water by using water quality information of the raw water and injection information of the chemical to be injected into the raw water; and a parameter adjusting part for adjusting a model parameter to be applied to the water quality reaction model by using a prediction value of the water quality of the treatment water predicted by the water quality reaction model predicting part and an actual value of the water quality of the treatment water, wherein the model parameter adjusted by the parameter adjusting part includes a parameter corresponding to a change amount of the water quality of the treatment water per unit injection rate of the chemical.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a chemical injection support system, a chemical injection support method, and a program. [Background technology]

[0002] The main purpose of operation and management of the water purification process at a water purification plant is to maintain the quality of treated water so that it meets the water quality standards for drinking water. Each water purification plant generally sets a management target water quality that is higher than the water quality standards, and strives to achieve cost and energy savings in the costs and energy required for cleaning and sludge disposal. In particular, in recent years, there has been a demand for low-cost operation and management technologies in order to strengthen the operational foundations of water utilities.

[0003] Water treatment plants, such as water purification plants, typically use a process for settling and removing suspended solids from raw water. This process is called a solid-liquid separation process. This process involves a flocculation process, in which chemicals called coagulants are injected to increase the rate of settling and form flocs. Flocs are formed when suspended solids and coagulants aggregate together. Flocs vary in size, from microflocs that are invisible to the naked eye (tens of micrometers) to giant flocs that grow to a few millimeters or centimeters and are visible to the naked eye. A good flocculation process is one that produces good flocs. To achieve good flocculation, it is important not only to properly manage the amount of coagulant injected relative to the suspended solids, but also to consider water quality parameters such as pH, alkalinity, and temperature of the raw water. Maintaining the pH within an appropriate range after coagulant injection is particularly important for good floc formation. When good flocs are formed, the density of the flocs is high and the particle size is large, which improves the settling property and promotes solid-liquid separation.

[0004] The dosing rates of chemicals used in water purification plants, such as coagulants and pH adjusters, are often determined based on the experience and know-how of skilled workers, making it difficult to transfer skills. To address this issue, technologies are being developed that predict and guide chemical dosing rates by statistically processing past water quality data and actual chemical dosing data or by machine learning. In recent years, technologies that use AI and machine learning to analyze the relationship between chemical dosing and water quality have also been proposed. However, chemical dosing at water purification plants is often excessive due to operational waste or excessive dosing due to plant circumstances. Therefore, even if chemical dosing rates are predicted using machine learning and other analyses based on past data, the predicted dosing rates may include the waste and excess. Furthermore, excessive dosing of chemicals is an obstacle to reducing the cost of water purification plant operation and management.

[0005] In response to this, a method has been devised that uses a physical model incorporating water treatment reactions and chemical injection information, including chemical injection rates, to simulate the quality of treated water. This method may make it possible to perform simulations using water qualities and chemical injection rates that have never been experienced before. However, chemical injection information differs from water purification plant to water purification plant, and therefore, in order to achieve practical accuracy in simulations using physical models, it is necessary to constantly adjust the internal parameters of the model. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-10613 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide a chemical injection support system, a chemical injection support method, and a program that can support the injection of more appropriate amounts of chemicals in a water treatment plant. [Means for solving the problem]

[0008] According to an embodiment, a chemical injection support system is provided, which includes a water quality reaction model prediction unit that predicts the water quality of treated water using a water quality reaction model that models the reaction caused by a chemical injected into the raw water using water quality information of the raw water and injection information of the chemical injected into the raw water, and a parameter adjustment unit that adjusts model parameters applied to the water quality reaction model using the predicted value of the water quality of the treated water predicted by the water quality reaction model prediction unit and the actual value of the water quality of the treated water, and the model parameters adjusted by the parameter adjustment unit include a parameter corresponding to the amount of change in the water quality of the treated water per unit injection rate of the chemical. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an example of the configuration of a water purification plant equipped with a chemical injection support system according to an embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the detailed configuration of the data collection and storage unit 21 and the main parts of the chemical injection support system shown in FIG. 1. [Figure 3] 4 is a flowchart showing an example of the operation of the data collection and storage unit and the main parts of the chemical injection support system in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings.

[0011] [Overall composition] Fig. 1 is a diagram showing an example of the configuration of a water purification plant equipped with a chemical injection support system according to an embodiment. Fig. 2 is a diagram showing an example of the detailed configuration of a data collection and storage unit 21 and main parts of chemical injection support system 20 shown in Fig. 1.

[0012] First, with reference to FIG. 1, an outline of a water purification plant and a chemical injection support system for the water purification plant according to this embodiment will be described.

[0013] As shown in Figure 1, water purification plant 1 includes, as water storage facilities for treating raw water, a receiving well 3, an activated carbon contactor basin 4, a mixing basin 5, a flocculation basin 6, a sedimentation basin 7, a sand filter basin 8, and a clear water basin 9. Water purification plant 1 further includes flow meters 2a-2d, a sampling pump 4a, a raw water temperature meter 10, a raw water alkalinity meter 11, a raw water pH meter 12, a flow meter 13, a sedimentation basin outlet turbidity meter 14, a coagulant dosage control unit 15, a coagulant injection system 16, a pH adjuster injection system 17, a mixing basin pH meter 18, a mixing basin alkalinity meter 19, and a plant operation unit 26.

[0014] The chemical injection support system 20 includes a water quality reaction model prediction unit 23, a parameter adjustment unit 24, and an operational chemical injection support unit 25. The chemical injection support system 20 can always use the data in the data collection and storage unit 21.

[0015] The data collection and storage unit 21 collects and stores data (hereinafter referred to as plant data) measured by the flow meters 2a to 2d, raw water temperature meter 10, raw water alkalinity meter 11, raw water pH meter 12, flow meter 13, mixing basin pH meter 18, and mixing basin alkalinity meter 19. In other words, the data collection and storage unit 21 corresponds to a database storing process data in a water purification plant or the like, and stores plant information such as minute-by-minute time series data, hourly time series data, and other setting value data.

[0016] The chemical injection support system 20 has the function of transmitting information indicating the injection rate of chemicals such as coagulants to the plant operation unit 26 based on the plant data collected in the data collection and storage unit 21, and is composed of, for example, one or more computers.

[0017] At the water purification plant 1, multiple water purification processes are carried out, such as a water intake process using a receiving well 3, an activated carbon adsorption process using an activated carbon contact basin 4, a coagulant injection process using a mixing basin 5, a flocculation process using a flocculation basin 6, a sedimentation filtration process using a settling basin 7, and a sand filtration process using a sand filter basin 8.

[0018] In the water intake process, for example, raw water is taken from multiple water intake sources A to D and flows into a receiving well 3 through each of the pipes. The intake flow rate of the raw water from each of the water intake sources A to D is measured by flow meters 2a to 2d installed in the respective pipes. The flow rate data measured by the flow meters 2a to 2d is sent to the data collection and storage unit 21 as part of the plant data. Some water purification plants have only one water intake source system, in which case one system of flow meters is also installed.

[0019] A raw water sample is extracted from the receiving well 3 by the sampling pump 4a. The raw water temperature, alkalinity, and pH are measured by a raw water temperature meter 10, a raw water alkalinity meter 11, and a raw water pH meter 12 as raw water quality information indicating the quality of the raw water. These measurements are sent to the data collection and storage unit 21 as part of the plant data. After the raw water quality information is measured, a pH adjuster is injected from a pH adjuster injection unit 17 into the raw water taken into the receiving well 3 to adjust the pH to a level suitable for the coagulation and sedimentation treatment. Examples of pH adjusters include caustic soda (sodium hydroxide) for adjusting the pH to alkaline, and sulfuric acid for adjusting the pH to acidic. The pH adjuster injection rate of the pH adjuster injection unit 17 is controlled by an operation chemical injection support unit 25 via a plant operation unit 26, as described below.

[0020] The raw water is also fed into the activated carbon contact basin 4 through a pipe. The fed raw water is treated with deodorization and other processes through an activated carbon adsorption process in the activated carbon contact basin 4. Activated carbon is added here when it is necessary to deal with odors such as mold or to remove colors. Some water purification plants are equipped with activated carbon equipment, but do not always inject it.

[0021] From the activated carbon contact basin 4, raw water that has been treated for deodorization and other purposes flows through a pipe into the mixing basin 5. Flow rate data measured by a flow meter 13 installed in the pipe is sent to a data collection and storage unit 21 as part of the plant data. In the mixing basin 5, a flocculant injection process is carried out in which a flocculant (e.g., polyaluminum chloride (PAC)) is injected from a flocculant injection system 16. The injection rate of the flocculant injection system 16 is controlled by an operation chemical injection support unit 25 via the plant operation unit 26 via an injection amount control unit 15 and a plant operation unit 26, as will be described later.

[0022] At the outlet of the mixing basin 5, a sample of the mixed water is taken using a sampling pump or the like (not shown). The pH of the mixed water is measured using a mixing basin pH meter 18, and the alkalinity of the mixing basin is measured using a mixing basin alkalinity meter 19, providing treated water quality information. These measurements are sent to the data collection and storage unit 21 as part of the plant data. In the mixing basin 5, the raw water to which coagulant has been injected undergoes collisions between the turbidity in the raw water and the coagulant, resulting in agglomeration and formation of microflocs due to electrical attraction. The raw water is then sent to the flocculation basin 6, where a flocculation process takes place, in which microflocs, residual coagulant, and residual turbidity contained in the raw water are coagulated to form flocs. Furthermore, in the sedimentation basin 7, the turbidity in the raw water is removed by sedimentation separation using a sedimentation filtration process.

[0023] [Data Collection and Storage Unit 21 Configuration] As shown in Figure 2, the data collection and storage unit 21 stores the plant's raw water quality information (raw water quality information), chemical injection information (injection information of chemicals injected into raw water), and treated water quality information (treated water quality information) as time-series data.

[0024] The raw water quality information includes information indicating the quality of the raw water, such as the pH, temperature, and alkalinity of the raw water. The chemical injection information includes information indicating the injection rate of chemicals into the raw water, such as the injection rate [mg / L] of a coagulant such as PAC and the injection rate [mg / L] of a pH adjuster such as caustic soda. This chemical injection information also includes information such as the type of coagulant and, in the case of an aluminum-based coagulant, the basicity of the aluminum, as well as the type and concentration of the pH adjuster. The treated water quality information includes information indicating the actual water quality of the treated water after treatment with chemicals injected according to the chemical injection information, such as the pH of the mixing basin after chemical addition and the alkalinity of the mixing basin after chemical addition.

[0025] Information indicating the volume of each pond is stored as structural information (fixed value information) of the plant in the data collection and storage unit 21. Since structural information is rarely variable, it often remains a constant value unless construction work such as updating is carried out.

[0026] The data collection and storage unit 21 also stores information indicating the flow rate of raw water collected from flow meters 2a to 2d and flow meter 13. The flow rate of raw water at a water purification plant may be constant 24 hours a day, or it may fluctuate depending on the demand for tap water. The retention time of raw water in each pond can be calculated using the flow rate of raw water and the structural volume of the plant.

[0027] The data collection and storage unit 21 described above stores information indicating the actual alkalinity values ​​after chemical injection and the actual pH values ​​after chemical injection as treated water quality information in chronological order. The actual alkalinity values ​​after chemical injection and the actual pH values ​​after chemical injection, which are treated water quality information, are paired data with the predicted alkalinity and pH values ​​after chemical addition output by the water quality reaction model prediction unit 23. The former are actual values, and the latter are model values. Here, the treated water quality information and output information are accompanied by time information. This makes it possible to compare the two at the same time, or to consider the data by shifting it by the time it takes for the water to flow downstream. The actual water quality value of the treated water is measured at a time delayed by the time it takes for the water to flow downstream.

[0028] [Configuration of water quality reaction model prediction unit 23] The water quality reaction model prediction unit 23 uses the raw water quality information and chemical injection information stored in the data collection unit and storage unit 21 to predict the water quality of the treated water using a water quality reaction model that models the reaction caused by chemicals injected into the raw water.

[0029] The water quality reaction model prediction unit 23 predicts the water quality of treated water based on a model that more specifically mathematically expresses water quality reactions at a water purification plant, for example. To this end, the water quality reaction model prediction unit 23 defines a water quality reaction model for the water treatment process and predicts the resulting water quality of treated water when an arbitrary chemical injection rate of a coagulant or pH adjuster is selected using chemical injection information stored in the data collection and storage unit 21. For example, the water quality reaction model prediction unit 23 receives raw water quality information and chemical injection information as input, and outputs the pH and alkalinity of the blended water predicted based on the raw water quality information and the chemical injection information. The water quality reaction model prediction unit 23 can also receive arbitrarily set raw water quality information and arbitrarily set chemical injection information as input, and output the pH and alkalinity of the blended water predicted based on the raw water quality information and the chemical injection information. The water quality reaction model may be, for example, a model that uses the total carbon dioxide concentration in water or the equilibrium constant of carbonate ions.

[0030] [Configuration of parameter adjustment unit 24] The parameter adjustment unit 24 adjusts the model parameters applied to the water quality reaction model used in the water quality reaction model prediction unit 23 using the predicted value of the water quality of the treated water predicted by the water quality reaction model prediction unit 23 and the actual value of the water quality of the treated water obtained from the data collection and storage unit 21.

[0031] This parameter adjustment unit 24 uses the input information (raw water quality information and chemical injection information) used by the water quality reaction model prediction unit 23 when predicting the water quality of the treated water to compare the predicted values ​​of the water quality of the treated water predicted by the water quality reaction model prediction unit 23 (predicted values ​​of pH in the mixing basin and alkalinity in the mixing basin) with the actual values ​​of the water quality of the treated water indicated by the treated water quality information stored in the data collection and storage unit 21 (specifically, the actual values ​​of the water quality of the treated water indicated by the treated water quality information obtained after raw water has actually been treated based on the input information (raw water quality information and chemical injection information) used by the water quality reaction model prediction unit 23 when predicting the water quality of the treated water (actual values ​​of pH in the mixing basin and alkalinity in the mixing basin)), and stores data showing the results of the comparison.

[0032] The parameter adjustment unit 24 also determines whether there is a discrepancy between the data indicating the comparison result and the predicted value of the water quality of the treated water predicted by the water quality reaction model prediction unit 23 (predicted values ​​of pH in the mixing basin and alkalinity in the mixing basin) and the actual value of the water quality of the treated water indicated by the treated water quality information stored in the data collection and storage unit 21 (specifically, the actual value of the water quality of the treated water indicated by the treated water quality information obtained after the raw water is actually treated based on the input information (raw water quality information and chemical injection information) used when the water quality reaction model prediction unit 23 predicts the water quality of the treated water)) exceeds a predetermined threshold value.

[0033] Furthermore, if the parameter adjustment unit 24 determines that the difference exceeds the threshold, it changes the parameters (state variables) used in the water quality reaction model prediction unit 23 using the data from the data collection and storage unit 21, and sets the new parameters in the water quality reaction model prediction unit 23. In this case, the parameter adjustment unit 24 may adjust the parameters so that the difference falls below the threshold until it obtains parameters that determine that the difference between the predicted value of the treated water quality predicted by the water quality reaction model prediction unit 23 (predicted value of pH in the mixing basin and alkalinity in the mixing basin) and the actual value of the treated water quality indicated by the treated water quality information stored in the data collection and storage unit 21 (specifically, the actual value of the treated water quality (actual value of pH in the mixing basin and alkalinity in the mixing basin) indicated by the treated water quality information obtained after the raw water has actually been treated based on the input information (raw water quality information and chemical injection information) used when the water quality reaction model prediction unit 23 predicted the treated water quality does not exceed the threshold.

[0034] The parameter adjustment unit 24 may periodically determine whether the difference exceeds the threshold value and perform the above-mentioned parameter adjustment operation. Furthermore, instead of being limited to a periodic operation, the parameter adjustment unit 24 may monitor changes in the treated water quality information stored in the data collection and storage unit 21, and perform the above-mentioned parameter adjustment operation when the treated water quality information changes significantly. Furthermore, the parameter adjustment operation may be performed based on instructions input by an operator.

[0035] [Configuration of Operation Management Support Department 25] The operation management support unit 25 has a function of acquiring a target water quality level for the treated water. The target water quality level for the treated water may be set by an operator, or a water quality level that minimizes chemical costs and electricity costs may be calculated separately and automatically set. Based on the operating conditions from the water quality reaction model prediction unit 23, the operation management support unit 25 generates optimal operating conditions within a range that achieves the target water quality, and outputs information indicating the generated operating conditions to the plant operation unit 26.

[0036] [Configuration of Plant Operation Unit 26] 1 controls the injection rate of the flocculant and the injection rate of the pH adjuster in accordance with the operation conditions from the operation management support unit 25. Specifically, the plant operation unit 26 outputs a control signal to the injection amount control unit 15 to control the injection rate of the flocculant in accordance with the injection rate included in the operation conditions from the operation management support unit 25.

[0037] The injection amount control unit 15 controls the injection amount of the flocculant to be injected into the mixing basin 5 by the flocculant injection equipment 16 in response to a control signal received from the plant operation unit 26. Furthermore, the pH adjuster injection equipment 17 controls the injection amount of the pH adjuster to be injected into the receiving well 3 in response to a control signal received from the plant operation unit 26. The plant operation unit 26 may be a unit that has been conventionally installed in water treatment plants.

[0038] The operation management support unit 25 and the plant operation unit 26 are connected to each other via a network so that they can communicate with each other. However, the configuration between the operation management support unit 25 and the plant operation unit 26 is not limited to a configuration in which they can communicate with each other via a network. The operation management support unit 25 may be configured to present operating conditions to an operator who operates the plant operation unit 26 (for example, by displaying the operating conditions on a mobile terminal carried by the operator). This allows the operator to perform operations on the plant operation unit 26 in accordance with the presented operating conditions, even if the operation management support unit 25 and the plant operation unit 26 are not connected via a network or the like.

[0039] With this configuration, when injecting a flocculant or pH adjuster at the water purification plant 1, the chemical injection support system 20 can support injection that is more suitable for maintaining the target water quality level of the treated water. The water quality reaction model prediction unit 23 can calculate the injection rate of the flocculant or pH adjuster that will achieve the target water quality level based on a water quality reaction model that uses parameters that are more suitable for the water quality of the raw water to be treated. The chemical injection support system 20 can instruct the plant operation unit 26 of the water purification plant 1 on the injection rates of the flocculant or pH adjuster that take into account the injection rates calculated by the water quality reaction model prediction unit 23.

[0040] [Specific example of the configuration of the water quality reaction model prediction unit 23] 2, the water quality reaction model prediction unit 23 has a model calculation unit 201 for performing model calculations. The water quality reaction model prediction unit 23 uses data stored in the data collection unit / storage unit 21 as input information, performs calculations using the model calculation unit 201, and generates output information.

[0041] Input information includes raw water quality information such as raw water turbidity, raw water pH, raw water temperature, and raw water alkalinity; chemical injection information such as the coagulant injection rate, the injection rate of caustic soda or sulfuric acid injected as a pH adjuster, and the injection rate of chlorine injected for disinfection; and other information such as flow rate and structure volume. Input information only needs to be temporarily stored in the data collection and storage units, and near-real-time plant data can be used. In addition to actual plant data, operators can also create and provide separate input information. Output information includes treated water quality information such as the alkalinity of the mixing basin after chemical addition and the pH of the mixing basin after chemical addition.

[0042] 2, the water quality reaction model prediction unit 23 is provided with a model parameter storage unit 202 that stores model parameters used in the model calculation. In the model calculation, calculations are performed using the model parameters stored in the model parameter storage unit 202.

[0043] The model parameters used here include parameters corresponding to the amount of change in the quality of the treated water per unit chemical injection rate. This improves prediction accuracy. The chemicals are those corresponding to the chemical injection rate stored in the data collection and storage units, and the quality of the treated water is information such as pH and alkalinity that is output as output information. The inventors have discovered that prediction accuracy can be further improved by applying, in particular, the amount of alkalinity decrease per unit chemical injection rate (alkalinity decrease coefficient) as the amount of change in the quality of the treated water per unit chemical injection rate. Specific examples of parameters that can improve prediction accuracy will be described later.

[0044] The output information of the model calculation is output to the operation management support unit 25 and simultaneously saved in the parameter adjustment unit 24. The parameter adjustment unit 24 has a function of outputting model parameters to the model parameter storage unit 202 in the water quality reaction model calculation unit 201. The model parameters that are output may be newly adjusted by the parameter adjustment unit 24, or may be output in response to input values ​​from the operator. The operator can also set newly determined parameters through offline data analysis.

[0045] [Specific example of the configuration of the parameter adjustment unit 24] As shown in FIG. 2, the parameter adjustment unit 24 has a data adjustment unit 203 and a recalculation unit 204. The data adjustment unit 203 stores treated water quality information such as the actual alkalinity value after chemical injection, the actual pH value after chemical injection, and the corresponding alkalinity and pH information after chemical addition output by the water quality reaction model prediction unit 23, as well as time information. The data adjustment unit 203 also acquires data on the body volume and flow rate for adjusting the flow time from the data collection and storage unit 21. The recalculation unit 204 recalculates the model parameters using the information stored in the data adjustment unit 203. The recalculated parameters are output to the model parameter storage unit 202 of the water quality reaction model prediction unit 23, and the parameters used in the model are updated.

[0046] [Examples of model parameters] When performing model calculations in the water quality reaction model prediction unit 23, as described above, parameters corresponding to the amount of change in the water quality of the treated water per unit injection rate of the chemical are used.

[0047] On the other hand, the change in treated water quality per unit chemical injection rate can vary significantly depending on the quality of the target raw water, or when considering application to raw water at different water purification plants. If the model is not adjusted for each application, the model's prediction accuracy cannot be maintained. Adjustments are required each time the model is applied to a different water purification plant. Even within the same water purification plant, raw water quality fluctuates seasonally, so model accuracy must be adjusted accordingly. Ideally, constant updates every few days to a week can improve prediction accuracy. Furthermore, the degree of degradation of chemicals used may fluctuate over the long term. Therefore, even when the same chemical is injected at the same injection rate, the range of fluctuation in treated water quality may not be the same. In response to this, the accuracy of the model can be improved by adjusting the change in treated water quality per unit chemical injection rate over a short period of time based on actual results.

[0048] The change in water quality of treated water per unit dosage of a chemical could be, for example, the change in alkalinity per 1 mg / L dosage of a coagulant such as PAC, or the change in alkalinity per 1 mg / L dosage of sodium hypochlorite. These are parameters specific to each chemical. Other examples include the change in pH per 1 mg / L dosage of caustic soda or the change in alkalinity per 1 mg / L dosage of sulfuric acid. Using these types of parameters as model parameters can improve prediction accuracy.

[0049] [Examples of data adjustment] Next, a specific example of data adjustment in the data adjustment unit 203 will be described. When multiple chemicals are injected simultaneously, it is not possible to accurately determine the amount of change in the quality of the treated water per unit injection rate of a specific chemical. Therefore, by extracting only data from times when the injection rates of chemicals other than the target chemical are almost unchanged, the influence of chemicals other than the target chemical can be reduced. Specifically, the injection rate of chlorine hardly changes during the nighttime hours. This is because there is no solar radiation at night and fluctuations in the residual chlorine concentration are small. In this case, if the injection rate of the coagulant changes during this period, resulting in fluctuations in the quality of the treated water, it can be assumed that the change in the injection rate of the coagulant contributed to the fluctuations in the quality of the treated water.

[0050] Furthermore, by extracting the above data only from data for time periods when the raw water quality information is almost constant, it can be assumed that the fluctuations in the treated water quality described above are solely due to the change in the coagulant injection rate during that period. The range of data that is almost constant can be set arbitrarily. For example, by using data from a time period where only the raw water pH is 7.3 to 7.4, the impact of different input information on fluctuations in the treated water quality can be reduced. Time periods when multiple items are constant can also be used as raw water quality information.

[0051] In this way, it is possible to calculate the amount of change in the quality of the treated water at the injection rate of a specific chemical. In addition, in the case of chlorine, where there is a difference in the injection rate between daytime and nighttime, if there is no difference in the injection rates of chemicals other than chlorine between daytime and nighttime, the range of fluctuation in the quality of the treated water can be considered to be due to the change in the injection rate of chlorine between daytime and nighttime. In this way, the role of the data adjustment unit 203 is to extract the time periods in which only the change in the range of a specific chemical is affected and to process the data.

[0052] The data used by the data adjustment unit 203 is basically data in minutes, but hourly data is also possible. Furthermore, if abnormal values ​​due to sensor maintenance periods or the like are detected, a data filter function can be provided to prevent the use of such data. Furthermore, in order to suppress the influence of data variability, a moving average can be calculated, or a trimmed average function that excludes values ​​in the upper and lower 10% ranges (the exclusion range can be adjusted as desired) can be provided. Since the data processing in the data adjustment unit 203 is not required to be performed in real time and is performed using stored past data, sufficient time is ensured for this data processing.

[0053] [Example of operation of data collection and storage unit 21 and chemical injection support system 20] Next, an example of the operation of the main parts of data collection and storage unit 21 and chemical injection support system 20 in this embodiment will be described with reference to the flowchart in FIG.

[0054] First, the data collection and storage unit 21 acquires raw water quality information, chemical injection information, and treated water quality information (step S71).

[0055] Next, the water quality reaction model prediction unit 23 reads out the chemical injection information and treated water quality information from the data collection and storage unit 21 as the latest model parameters (step S72). The chemical injection information includes chemical injection rate information such as the coagulant injection rate [mg / L] and the pH adjuster injection rate [mg / L]. The treated water quality information includes information such as the alkalinity of the mixing basin after chemical addition and the pH of the mixing basin after chemical addition. The water quality reaction model prediction unit 23 then predicts the treated water quality using the model, using the chemical injection information, chemical injection rate, and model parameters obtained from the data collection and storage unit 21 (step S73). At the same time, the predicted treated water quality information is sent to the operation management support unit 25.

[0056] Next, the parameter adjustment unit 24 obtains information on the quality of the treated water after the raw water has flowed for a predetermined time from the data collection and storage unit 21, using the input information (raw water quality information and chemical injection information) used when the water quality reaction model prediction unit 23 predicted the quality of the treated water. Then, in accordance with the set cycle and instructions from the operator, the parameter adjustment unit 24 determines whether the difference between the predicted value of the treated water quality predicted by the water quality reaction model prediction unit 23 and the actual value of the treated water quality after the flow time has elapsed exceeds a preset threshold value (step S74).

[0057] Here, if the parameter adjustment unit 24 determines that the difference between the predicted value of the water quality of the treated water predicted by the water quality reaction model prediction unit 23 and the actual value of the water quality of the treated water after the flow time has elapsed exceeds the threshold value (YES in step S74), it uses the difference to adjust the parameters used in the water quality reaction model prediction unit 23 (step S75) and sets the new parameters in the water quality reaction model prediction unit 23. When the parameter adjustment unit 24 finishes the processing of step S75, it proceeds to the processing of step S73.

[0058] On the other hand, if the parameter adjustment unit 24 determines that the difference between the predicted value of the water quality of the treated water predicted by the water quality reaction model prediction unit 23 and the actual value of the water quality of the treated water after the flow time has passed does not exceed the threshold value (NO in step S74), no parameter adjustment is performed.

[0059] The operational chemical injection support unit 25 generates operating conditions for controlling the chemical injection rate in the water treatment plant based on the chemical injection information used for prediction by the water quality reaction model prediction unit 23, and outputs the generated operating conditions to the plant operation unit 26 (step S76).

[0060] 3 is merely an example and is not limited to this example. For example, when comparing the water quality value of the treated water predicted by the water quality reaction model prediction unit 23 with the actual water quality value of the treated water after the flow time has elapsed, integrated data may be used, and for example, 24 hours' worth of data for both may be used to determine the discrepancy. Furthermore, instead of determining based on a threshold value, the values ​​may be periodically updated at a preset interval of several days to one week.

[0061] According to this embodiment, the chemical injection support system 20 can achieve the target water quality of the treated water when injecting chemicals into the water purification plant 1, and can also provide support for injecting a more appropriate amount of chemicals. By setting the appropriate chemical injection rate, it is possible to safely manage the water quality of the water purification plant 1 and reduce the cost of chemical injection for the following four reasons.

[0062] (1) It is possible to predict and set the alkaline agent injection rate to adjust the pH and alkalinity at designated control points within the water purification plant to the target control values.

[0063] (2) When an arbitrary chemical injection rate is set, the changes in pH and alkalinity at a specified control point can be known before the chemical injection rate is set.

[0064] (3) For water quality personnel who are examining changes in the quality of treated water after the injection of multiple chemicals, the time required for examination in actual jar tests with different injection patterns can be shortened, enabling them to respond to changes in water quality without delay.

[0065] (4) Even if the water quality characteristics of the raw water or the chemicals deteriorate, the parameters used in the water quality reaction model can be readjusted over a short period of time based on the discrepancy between actual and predicted values, allowing the use of a highly accurate water quality reaction model over the long term.

[0066] Furthermore, the data collection and storage unit 21 in the chemical injection support system 20 may be configured in any manner to collect data measured by the flowmeters 2a-2d, the water temperature meter 10, the alkalinity meter 11, the pH meter 12, the flowmeter 13, the settling basin outlet turbidity meter 14, the mixing basin pH meter 18, and the mixing basin alkalinity meter 19. The data collection and storage unit 21 may, for example, be configured to collect measured data via wired or wireless communication, such as via a network such as the Internet or via a dedicated line. For example, the data collection and storage unit 21 may be configured based on the Internet, such as cloud computing. In this case, the chemical injection support system 20 may be configured to include a chemical injection support device including a water quality reaction model prediction unit 23, a parameter adjustment unit 24, and an operational chemical injection support unit 25, and access the data collection and storage unit 21 on the cloud from the chemical injection support device.

[0067] In the above-described embodiment, each functional unit in chemical injection support system 20 may be configured as a software functional unit, or may be a hardware functional unit such as an LSI. Furthermore, each functional unit in chemical injection support system 20 may be configured using a PCL (programmable logic controller). In the above-described embodiment, a water purification plant process is shown as an example of the process that chemical injection support system 20 supports, but the system can be applied to any process in which raw water is purified using chemicals.

[0068] According to at least one of the embodiments described above, it is possible to provide support for injecting chemicals in more appropriate amounts in a water treatment plant.

[0069] Furthermore, when the functions of the chemical injection support system 20 described above are implemented by software, a program for implementing those functions may be recorded on a computer-readable recording medium and loaded into a computer system for execution. Note that the term "computer system" as used herein includes hardware such as an operating system (OS) and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and compact disks (CDs)-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" also includes devices that retain a program for a certain period of time, such as volatile memory (RAM) within a computer system that acts as a server or client when the program is transmitted via a network such as the Internet or a communication line such as a telephone line.

[0070] The above program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by transmission waves in the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.

[0071] The above program may also be a program for realizing some of the above functions. Furthermore, the above program may be a so-called differential file (differential program) that can realize the above functions in combination with a program already recorded in the computer system.

[0072] As described above in detail, according to the embodiment, it is possible to provide support for injecting chemicals in more appropriate amounts in a water treatment plant.

[0073] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0074] 1...water purification plant, 3...receiving well, 4...activated carbon contact basin, 5...mixing basin, 6...flocculation basin, 7...sedimentation basin, 8...sand filter basin, 9...clean water basin, 10...raw water temperature meter, 11...raw water alkalinity meter, 12...raw water pH meter, 13...flow meter, 14...sedimentation basin outlet turbidity meter, 15...coagulant dosage control unit, 16...coagulant injection equipment, 17...pH adjuster injection equipment, 18...mixing basin pH meter, 19...mixing basin alkalinity meter, 20...chemical injection support system, 21...data collection and storage unit, 23...water quality reaction model prediction unit, 24...parameter adjustment unit, 25...operational chemical injection support unit, 26...plant operation unit, 201...model calculation unit, 202...model parameter storage unit, 203...data adjustment unit, 204...recalculation unit.

Claims

1. a water quality reaction model prediction unit that predicts the water quality of treated water using a water quality reaction model that models reactions caused by chemicals injected into the raw water, using water quality information about the raw water and injection information about chemicals injected into the raw water; a parameter adjustment unit that adjusts model parameters applied to the water quality reaction model using the predicted value of the water quality of the treated water predicted by the water quality reaction model prediction unit and the actual value of the water quality of the treated water; Equipped with A chemical injection support system, wherein the model parameters adjusted by the parameter adjustment unit include a parameter corresponding to an amount of change in water quality of the treated water per unit injection rate of the chemical.

2. The change in the water quality of the treated water per unit injection rate of the chemical includes a decrease in alkalinity. The chemical injection support system according to claim 1 .

3. The change in the water quality of the treated water per unit injection rate of the chemical includes at least one of the change in alkalinity per injection rate of 1 mg / L of coagulant, the change in alkalinity per injection rate of 1 mg / L of sodium hypochlorite, the change in alkalinity per injection rate of 1 mg / L of sulfuric acid, and the change in pH per injection rate of 1 mg / L of caustic soda. The chemical injection support system according to claim 1 .

4. the parameter adjustment unit, when a difference between a predicted value of the water quality of the treated water predicted by the water quality reaction model prediction unit and an actual value of the water quality of the treated water exceeds a preset threshold, changes the model parameters so as to reduce the difference; The chemical injection support system according to any one of claims 1 to 3.

5. The chemical injection support system according to claim 1 , wherein the water quality information of the raw water includes information indicating the turbidity, pH, water temperature, and alkalinity of the raw water.

6. The chemical injection support system according to claim 1 , wherein the chemical injection information includes information indicating a coagulant injection rate, a caustic soda injection rate, a sulfuric acid injection rate, and a chlorine injection rate.

7. 7. The chemical injection support system according to claim 1, wherein the performance values ​​of the water quality of the treated water include a performance value of alkalinity after chemical addition and a performance value of pH after chemical addition.

8. A water quality reaction model prediction unit predicts the water quality of the treated water using a water quality reaction model that models reactions caused by chemicals injected into the raw water using water quality information of the raw water and injection information of chemicals injected into the raw water; A parameter adjustment unit adjusts model parameters applied to the water quality reaction model using the predicted value of the water quality of the treated water and the actual value of the water quality of the treated water; wherein the model parameters adjusted by the parameter adjustment unit include a parameter corresponding to an amount of change in water quality of the treated water per unit injection rate of the chemical.

9. On the computer, A function of predicting the quality of treated water using a water quality reaction model that models the reaction of chemicals injected into the raw water using water quality information of the raw water and injection information of chemicals injected into the raw water; a function of adjusting model parameters applied to the water quality reaction model using the predicted value of the water quality of the treated water and the actual value of the water quality of the treated water; wherein the model parameters to be adjusted include a parameter corresponding to an amount of change in the water quality of the treated water per unit injection rate of the chemical.

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