JP2024022246A - water quality analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fulfill the need to correct increases or decreases in a detection signal due to staining.

SOLUTION: Provided is a water quality analyzer for measuring a concentration of a measuring object substance contained in sample water, and the water quality analyzer comprises: a flow cell which has a wall part transmitting light and an internal space surrounded by the wall part and allows the sample water to pass through the internal space; a light source which emits light toward the flow cell; a concentration measuring part which, on the basis of light to be measured from the flow cell when emitting light source light from the light source to the flow cell, measures the concentration of the measuring object substance contained in the sample water, in the state of flowing the sample water to the flow cell; a stain detection part which, on the basis of a light quantity of the light to be measured from the flow cell, measures an optical attenuation due to stain of the flow cell in the state of flowing to the flow cell reference water with a known concentration of the measuring object substance; and a stain correction part which, on the basis of the optical attenuation due to the stain of the flow cell, corrects a measurement result of the concentration of the measuring object substance when flowing the sample water.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a water quality analysis device.

BACKGROUND ART Water quality analyzers that analyze the water quality of sample water are conventionally known (see, for example, Patent Documents 1 and 2).
[Prior art documents]
[Patent document]
[Patent Document 1] Japanese Patent No. 6436266 [Patent Document 2] Japanese Patent Application Publication No. 2007-46978

When dirt accumulates in the part through which sample water flows in a water quality analyzer, a detection signal indicating the concentration of a substance to be measured contained in the sample water fluctuates.

In a first aspect of the present invention, a water quality analysis device is provided. The water quality analyzer may include a flow cell. Any of the above water quality analysis devices may include a light source. Any of the above water quality analyzers may include a concentration measuring section. Any of the above water quality analyzers may include a dirt detection section. Any of the above water quality analyzers may include a dirt correction section. In any of the above water quality analyzers, the flow cell may have a wall that transmits light. In any of the above water quality analyzers, the flow cell may be surrounded by a wall and have an internal space through which sample water passes. In any of the above water quality analyzers, the light source may irradiate light toward the flow cell. In any of the above water quality analyzers, the concentration measurement unit determines the amount of water contained in the sample water based on the measured light from the flow cell when the flow cell is irradiated with source light from the light source while the sample water is flowing through the flow cell. The concentration of the substance to be measured may be measured. In any of the above water quality analyzers, the contamination detection unit detects the light attenuation due to contamination of the flow cell based on the amount of light to be measured from the flow cell when reference water with a known concentration of the substance to be measured is flowing through the flow cell. The amount can be detected. In any of the above water quality analyzers, the dirt correction section may correct the measurement result of the concentration of the substance to be measured when the sample water is passed, based on the amount of light attenuation due to dirt in the flow cell.

In any of the above water quality analyzers, the contamination correction section stores the detected amount of light attenuation due to contamination of the flow cell, and stores the stored amount of light attenuation until the next time the amount of light attenuation due to contamination of the flow cell is detected. may be used to correct the measurement results of the concentration of the substance to be measured.

Any of the above water quality analyzers may further include a cleaning section. In any of the above water quality analyzers, the dirt detection section may flow reference water through the flow cell and detect the amount of optical attenuation after cleaning the flow cell and before flowing the sample water.

Any of the above water quality analyzers may further include a light source light amount monitor. In any of the above water quality analyzers, the light source light amount monitor may detect the amount of light source light that enters the flow cell. In any of the above water quality analyzers, the dirt detection section may detect the amount of light attenuation using the amount of light from the light source when measuring the reference water.

In any of the above water quality analyzers, the dirt correction section may maintain a history of attenuation information corresponding to the amount of light attenuation measured in the past, and may predict the amount of light attenuation in the future.

In any of the above water quality analyzers, the dirt correction section may estimate the time when the predicted value of the amount of light attenuation exceeds the allowable value.

Any of the above water quality analyzers may further include a cleaning section. In any of the above water quality analyzers, the dirt detection section may flow reference water through the flow cell and detect the amount of optical attenuation after cleaning the flow cell and before flowing the sample water. In any of the above water quality analyzers, the cleaning section may change the cleaning method depending on the prediction of the amount of light attenuation.

In any of the water quality analyzers described above, the cleaning unit may select a cleaning method for the next cleaning depending on a change in light attenuation before and after cleaning when the cleaning method is changed.

In any of the above water quality analyzers, the dirt detection section detects the amount of light attenuation using reference water multiple times between washings, and based on the rate of increase in the amount of light attenuation, Changes in optical attenuation up to cleaning may be predicted. In any of the above water quality analyzers, the dirt correction section may correct the measurement result of the concentration of the substance to be measured based on the prediction of the change in the amount of light attenuation.

In any of the above water quality analyzers, when detecting the amount of optical attenuation from one wash to the next wash, the flow rate of the reference water is set to the flow rate of the sample water when measuring the concentration of the target substance contained in the sample water. The flow rate may be lower than that.

In any of the above water quality analyzers, when detecting the amount of optical attenuation from one wash to the next wash, the flow rate of the reference water may be set to be equal to or lower than the flow rate of the wash water used during washing.

In any of the above water quality analyzers, the cleaning unit determines whether or not cleaning of the flow cell has been completed based on the detection result of the amount of optical attenuation, and if cleaning has not been completed within a set period from the start of cleaning of the flow cell, The cleaning method in the cleaning section may be changed.

In any of the above water quality analyzers, the cleaning section may select a flow cell cleaning method based on the history of sample water that has been passed through the flow cell in the past.

Any of the above water quality analyzers may further include a transmitted light detection section and a scattered light amount detection section. In any of the above water quality analyzers, the transmitted light detection section may detect the amount of transmitted light that is the amount of transmitted light that has passed through the flow cell. In any of the above water quality analyzers, the scattered light amount detection section may detect the amount of scattered light that is the amount of scattered light from the reference water. In any of the above water quality analyzers, the dirt detection section may detect the amount of light attenuation due to dirt in the flow cell based on the amount of transmitted light and the amount of scattered light when reference water is flowing through the flow cell.

Note that the above summary of the invention does not list all the necessary features of the invention. Furthermore, subcombinations of these features may also constitute inventions.

1 is a diagram showing an example of a water quality analysis device 100 according to one embodiment of the present invention. FIG. 3 is a diagram illustrating correction to the measurement result of the concentration of a substance to be measured. It is a figure showing an example of water quality analyzer 100 concerning other embodiments of the present invention. It is a figure showing an example of water quality analyzer 100 concerning other embodiments of the present invention. 5 is a flowchart showing an example of the operation of the water quality analyzer 100 in the embodiment of FIG. 4. FIG. It is a figure showing an example of water quality analyzer 100 concerning other embodiments of the present invention. It is a diagram which predicts the amount of light attenuation in the future based on the amount of light attenuation in the past. It is a figure showing an example of water quality analyzer 100 concerning other embodiments of the present invention. FIG. 7 is a diagram illustrating another example of predicting future optical attenuation based on past optical attenuation. It is a figure showing an example of water quality analyzer 100 concerning other embodiments of the present invention.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Furthermore, not all combinations of features described in the embodiments are essential to the solution of the invention.

FIG. 1 is a diagram showing an example of a water quality analysis device 100 according to one embodiment of the present invention. The water quality analyzer 100 measures the concentration of a substance to be measured contained in sample water. The water quality analyzer 100 of this example includes a light source 10, a flow cell 20, a concentration measurement section 36, a transmitted light detection optical system 70, a transmitted light detection signal processing section 72, a dirt detection section 40, and a dirt correction section 42. The concentration measurement section 36 includes a concentration detection optical system 30 and a concentration detection signal processing section 32. The concentration detection optical system 30 and the transmitted light detection optical system 70 are devices that detect the amount of received light using a light receiving element such as a CCD or a photodiode. In this specification, the amount of light refers to the total amount of light flux (lm/S) that passes through a predetermined surface within a predetermined unit time, but the intensity of light (cd) may also be used as the amount of light. The concentration detection optical system 30 and the transmitted light detection optical system 70 output electric signals corresponding to the detected amount of light. The concentration detection signal processing section 32 and the transmitted light detection signal processing section 72 perform signal processing such as amplification or noise removal on the electrical signal.

The light source 10 irradiates light 91 toward the flow cell 20 . Flow cell 20 has a wall 22 and an interior space 24 . At least a portion of the wall portion 22 is made of a material that transmits at least a portion of the components of the light 91 irradiated by the light source 10 . At least a portion of the wall portion 22 is made of glass, for example. The wall portion 22 may include a window portion through which the light 91 enters or exits, and a support portion that supports the window portion. In this specification, the window portion through which the light 91 enters or exits may be referred to as the wall portion 22. Internal space 24 is surrounded by wall portion 22 . Sample water passes through the internal space 24 . As an example, the wall portion 22 has a cylindrical shape. In FIG. 1, a cross section of the wall portion 22 and the internal space 24 is schematically shown.

The concentration detection optical system 30 detects the measurement light 92 from the flow cell 20. The concentration detection optical system 30 measures the amount of measurement light 92 at at least one wavelength. The measurement light 92 is light that is emitted from the flow cell 20 when the light source 10 irradiates the light 91 with sample water present in the flow cell 20 . The measurement light 92 may include fluorescence emitted from the substance to be measured when the substance to be measured contained in the sample water is irradiated with the light 91 . In this case, the concentration detection optical system 30 may measure the amount of the measurement light 92 at a wavelength different from that of the light 91.

The concentration detection signal processing unit 32 calculates the concentration of the substance to be measured contained in the sample water based on the measurement results in the concentration detection optical system 30. Examples of sample water include, but are not limited to, tap water, sewage water, seawater, and wastewater from factories. When the sample water contains a fluorescent substance such as polycyclic aromatic hydrocarbons (hereinafter referred to as PAH), when the sample water is irradiated with ultraviolet light 91, fluorescence at a wavelength unique to the substance (measurement light 92) is emitted. ) occurs. Since the fluorescence intensity is proportional to the concentration of the fluorescent substance contained, by measuring the amount of measurement light 92 at the relevant wavelength, the concentration of the fluorescent substance, which is the substance to be measured, can be accurately measured. . The concentration detection signal processing section 32 outputs the measurement result to the dirt correction section 42 .

When dirt occurs on the wall portion 22 of the flow cell 20, the intensity of the light 91 or the measurement light 92 is attenuated by the dirt. When the wall portion 22 is provided with the above-mentioned window portion, the dirt on the wall portion 22 refers to the dirt on the window portion. Dirt on the wall 22 is, for example, foreign matter attached to the inner or outer surface of the wall 22. If the intensity of the light 91 or the measurement light 92 is attenuated, an error will occur in the measurement result of the concentration of the substance to be measured. For this reason, it is preferable to be able to correct the influence of dirt occurring on the wall portion 22 of the flow cell 20.

The dirt detection unit 40 detects dirt on the wall portion 22. The dirt detection unit 40 may detect dirt on the wall portion 22 using a predetermined operation in the water quality analyzer 100 as a trigger. The dirt detection unit 40 may detect dirt on the wall portion 22 every time a set detection period elapses. The dirt detection unit 40 may detect dirt on the wall portion 22 in response to instructions from a user or the like.

When the dirt detection unit 40 detects dirt on the wall 22 , the light source 10 irradiates the flow cell 20 with light 91 having a predetermined wavelength component. When detecting dirt on the wall 22, the water quality analyzer 100 may flow reference water in which the concentration of the substance to be measured is known through the flow cell 20. The concentration of the substance to be measured in the reference water may be below the measurement limit or resolution of the concentration measuring section 36. The turbidity of the reference water may be less than or equal to 1 FNU. The wavelength of the light 91 when detecting dirt may be different from the wavelength of the light 91 when measuring the fluorescence of the substance to be measured. The light source 10 may include a light source unit that emits light 91 for detecting dirt and a light source unit that emits light 91 for detecting fluorescence.

The transmitted light detection optical system 70 allows light 91 to enter the flow cell 20 and detects transmitted light 94 that has passed through the flow cell 20 . The transmitted light detection optical system 70 may detect the light 91 that has gone straight through the flow cell 20 and is emitted as transmitted light 94 . The wall 22 may be provided with a window through which the light 91 enters, a window through which the measurement light 92 exits, and a window through which the transmitted light 94 exits. The transmitted light detection optical system 70 detects the amount of transmitted light, which is the amount of transmitted light 94. The transmitted light detection optical system 70 may detect the amount of transmitted light of a set wavelength. The transmitted light detection optical system 70 outputs an electrical signal indicating the amount of transmitted light to the dirt detection section 40. The transmitted light detection signal processing section 72 may perform signal processing such as amplification or noise removal on the electrical signal. Note that the concentration of the substance to be measured may be detected using the transmitted light detection optical system 70 and the transmitted light detection signal processing section 72 instead of the concentration measurement section 36.

When dirt adheres to the wall portion 22, the intensity of light is attenuated by the dirt, so the amount of transmitted light 94 is reduced. Therefore, by detecting how much the amount of transmitted light 94 is attenuated with respect to the amount of light 91 emitted by the light source 10, the degree of dirt on the wall portion 22 can be estimated. In this example, the amount of attenuation of the amount of transmitted light 94 relative to light 91 is referred to as the amount of optical attenuation. The dirt detection section 40 calculates the amount of optical attenuation and outputs it to the dirt correction section 42 .

FIG. 2 is a diagram illustrating correction of the measurement result of the concentration of the substance to be measured. The dirt correction section 42 performs the correction based on the amount of light attenuation. The vertical axis in FIG. 2 indicates the density or a correction value for correcting the density. The horizontal axis shows the time series. The water quality analyzer 100 measures the concentration of the target substance contained in the sample water from time 1 to time 5. A in the figure shows the measurement result of the concentration of the substance to be measured before being corrected by the amount of optical attenuation. In this example, the concentration of the substance to be measured is calculated based on the amount of transmitted light 94. When the transmitted light 94 is attenuated due to contamination of the flow cell 20, the concentration of the substance to be measured in the measurement result before correction increases. Therefore, as time passes and dirt accumulates in the flow cell 20, the concentration of the substance to be measured in the measurement results before correction increases. B in the figure indicates the amount of correction based on the amount of optical attenuation. The correction amount based on the amount of optical attenuation is, for example, the difference value between the measured amount of optical attenuation and the amount of optical attenuation during calibration. The amount of correction based on the amount of optical attenuation can be obtained from the following equation, for example.
Amount of correction based on the amount of optical attenuation = measured amount of optical attenuation - amount of optical attenuation during calibration The amount of correction based on the amount of optical attenuation also increases in accordance with the amount of dirt that accumulates on the flow cell 20 over time.

C in the figure indicates the concentration obtained by correcting the concentration of the substance to be measured before correction using the correction amount based on the amount of optical attenuation. For example, the correction is performed by subtracting a correction amount based on the amount of optical attenuation from the density before correction. For example, the correction is performed according to the following formula.
Concentration after correction = concentration before correction - amount of correction by optical attenuation The concentration of the target substance before correction, which does not take into account the influence of dirt on the flow cell 20, increases with the accumulation of dirt on the flow cell 20, but the light attenuation By performing the correction based on the amount, the density after correction becomes a substantially constant value. In other words, results closer to the original concentration of the target substance to be measured can be obtained.

In this example, a case has been described in which the concentration of the substance to be measured is calculated based on the transmitted light 94, but this correction can also be applied to the case where the concentration of the substance to be measured is calculated based on the measurement light 92. In that case, the sign of the addition or subtraction in the equation of the correction amount based on the amount of light attenuation and the corrected density is determined based on the generation principle of the measurement light 92.

FIG. 3 is a diagram showing an example of a water quality analyzer 100 according to another embodiment of the present invention. The water quality analyzer 100 of this example includes a memory 46 in addition to the configuration described in FIG. The memory 46 stores the amount of light attenuation detected by the dirt detection section 40. The dirt correction unit 42 may use the stored light attenuation amount to correct the measurement result of the concentration of the substance to be measured until the next time the amount of light attenuation due to the dirt on the flow cell 20 is detected.

FIG. 4 is a diagram showing an example of a water quality analyzer 100 according to another embodiment of the present invention. The water quality analyzer 100 of this example includes a cleaning section 50 in addition to any of the configurations described in FIGS. 1 to 3. In FIG. 4, a cleaning section 50 is added to the configuration shown in FIG. The cleaning section 50 cleans the flow cell 20. The cleaning section 50 may clean the flow cell 20 by flowing clean water or a cleaning liquid containing chemicals or the like into the internal space 24 of the flow cell 20, or may wash the flow cell 20 using a cleaning liquid with a different pH, and may clean the flow cell 20 by using a member such as a brush. The flow cell 20 may be cleaned by sweeping the internal space 24, or the flow cell 20 may be cleaned by a combination of these methods.

FIG. 5 is a flowchart showing an example of the operation of the water quality analyzer 100 in the embodiment of FIG. In trigger step S200, water quality analyzer 100 determines whether a predetermined cleaning trigger has been input. The water quality analyzer 100 performs a cleaning process (S202 to S210) on the flow cell 20 when a predetermined cleaning trigger is input. The trigger signal may be input in response to an operation by a user, etc., may be automatically input in response to a change in the surrounding environment, may be automatically input every time a predetermined period elapses, or may be input automatically in response to a change in the surrounding environment. may be input depending on the factors. The water quality analyzer 100 may perform the sample water measurement process (S212 to S220) while the cleaning trigger is not input.

When the cleaning trigger is input, the cleaning unit 50 cleans the flow cell 20 in the cleaning step S202. After the cleaning of the flow cell 20 is completed, in the reference water flow step S204, the water quality analyzer 100 flows reference water in which the concentration of the substance to be measured is known through the flow cell in order to obtain the amount of optical attenuation. In the post-cleaning signal processing step S206, light 91 from the light source 10 is incident on the flow cell 20 through which reference water is flowing. The transmitted light detection optical system 70 detects the transmitted light 94 that has passed through the flow cell 20 after cleaning. The transmitted light detection signal processing section 72 may perform signal processing such as amplification or noise removal on the electrical signal output by the transmitted light detection optical system 70.

In the signal correction processing step S208, the transmitted light detection signal processing section 72 performs arbitrary correction processing on the electrical signal output by the transmitted light detection optical system 70. The correction process includes, for example, a process for correcting a change in the amount of transmitted light 94 due to a change in the amount of light 91, or a process for correcting nonlinearity in the magnitude of the electrical signal with respect to the amount of light received by the transmitted light detection optical system 70. .

In the light attenuation amount obtaining step S210, the dirt detection unit 40 obtains the light attenuation amount. In this example, the stain detection unit 40 flows reference water into the flow cell 20 after the cleaning unit 50 cleans the flow cell 20, and acquires the amount of optical attenuation. This makes it possible to obtain the amount of light attenuation due to dirt that cannot be removed by cleaning alone. The amount of correction based on the amount of optical attenuation in this example is obtained from the following equation, for example.
Amount of correction based on the amount of light attenuation = amount of light attenuation after cleaning - amount of light attenuation during calibration The dirt detection section 40 outputs the amount of light attenuation or the amount of correction based on the amount of light attenuation to the dirt correction section 42 .

After the cleaning is completed or if a predetermined cleaning trigger signal is not input, the water quality analyzer 100 causes the sample water to flow through the flow cell 20 in the sample water flow step S212. In the measurement signal processing step S214, the concentration measurement unit 36 detects the amount of measurement light 92 and measures the sample water. The density measurement section 36 outputs the measurement result to the dirt correction section 42.

In measurement light amount and other correction processing S216, the concentration detection signal processing section 32 performs arbitrary correction processing on the electric signal output from the concentration detection optical system 30. The correction process includes, for example, a process for correcting a change in the amount of transmitted light 94 due to a change in the amount of light 91, or a process for correcting nonlinearity in the magnitude of the electrical signal with respect to the amount of light received by the concentration detection optical system 30. In the light attenuation amount correction processing step S218, the dirt correction unit 42 corrects the measurement result of the concentration of the substance to be measured using the light attenuation amount. Note that the dirt correction unit 42 in this example corrects the value that has been converted into density in advance in the light attenuation amount correction processing step S218, but it corrects the detection signal before converting into density in the light attenuation amount correction processing step S218. The detected signal may be acquired, corrected, and then converted to concentration.

FIG. 6 is a diagram showing an example of a water quality analyzer 100 according to another embodiment of the present invention. The water quality analyzer 100 of this example includes a light source light amount monitor 60 and a correction processing section 62 in addition to any of the configurations described in FIGS. 1 to 4. In addition to the configuration shown in FIG. 1, FIG. 6 includes a light source light amount monitor 60 and a correction processing section 62. The light source light amount monitor 60 detects the light source light amount of the light 91 before entering the flow cell 20 . The light source light amount monitor 60 may receive branched light 93 obtained by branching a part of the light 91. The correction processing unit 62 performs signal processing such as amplification and noise removal of the detection signal. The amount of light from the light source is output to the dirt detection section 40.

The dirt detection unit 40 of this example detects dirt on the wall portion 22 of the flow cell 20 based on the amount of light from the light source and the amount of transmitted light. The dirt detection unit 40 corrects the amount of transmitted light based on the amount of light from the light source, and detects dirt on the wall portion 22 based on the correction result. For example, the dirt detection unit 40 corrects the amount of transmitted light such that the smaller the amount of light from the light source is, the larger the amount of transmitted light is, and determines that the smaller the corrected amount of transmitted light is, the greater the degree of dirt on the wall portion 22 is. As an example, the stain detection unit 40 detects stains on the wall portion 22 based on the ratio of the amount of light from the light source to the amount of transmitted light (amount of transmitted light/amount of light source light). The dirt detection unit 40 determines that the smaller the light amount ratio, the greater the degree of dirt. In this way, by detecting dirt on the wall portion 22 using the amount of light from the light source and the amount of transmitted light, the influence of deterioration of the light source 10 and the like can be reduced, and dirt on the wall portion 22 can be detected with high accuracy.

FIG. 7 is a diagram in which future optical attenuation amounts are predicted based on past optical attenuation amounts. The dirt correction unit 42 of this example maintains a history of attenuation information of the amount of light attenuation measured in the past, and predicts the amount of light attenuation in the future. The circles in the figure indicate past measurement results. The dirt correction unit 42 may perform at least one of two types of prediction. Of the two types of predictions, one is a prediction of the amount of light attenuation due to dirt that cannot be removed by cleaning. In this prediction, the subsequent amount of light attenuation is predicted based on the amount of light attenuation obtained after washing and before flowing the sample water. The solid line in the figure represents this prediction. The dirt correction unit 42 may predict the future amount of light attenuation by approximating the transition of the measurement results immediately after cleaning with an approximation line 102 such as a straight line or a curve. The dirt correction unit 42 may store information regarding the approximate line 102 as attenuation information. Since this prediction is a prediction of the amount of light attenuation due to dirt that cannot be removed by cleaning, the prediction can be made over the period of use regardless of whether or not there will be subsequent cleaning.

Another prediction is the amount of light attenuation due to all dirt, including dirt that can be removed by cleaning. In this prediction, measurements are performed multiple times between one cleaning and the next cleaning, and the subsequent amount of optical attenuation is predicted based on the change in the amount of optical attenuation obtained. The dashed line in the figure represents this prediction. The dirt correction unit 42 may predict the future amount of light attenuation by approximating the transition of a plurality of measurement results between cleanings with an approximation line 104 such as a straight line or a curve. The stain correction unit 42 may store information regarding the approximate line 104 as attenuation information. The dirt correction unit 42 may perform prediction based on attenuation information of the amount of light attenuation between multiple past cleanings. This prediction includes the influence of dirt that can be removed by cleaning, so the prediction range is from one cleaning to the next cleaning. The stain correction unit 42 can apply the attenuation information between past washes to any subsequent wash.

The dirt correction unit 42 may combine the attenuation information regarding the approximate line 102 and the attenuation information regarding the approximate line 104 to estimate the future amount of optical attenuation. For example, the dirt correction unit 42 uses the approximation line 102 to estimate the amount of light attenuation immediately after cleaning to be performed at an arbitrary timing in the future. The stain correction unit 42 may estimate the transition of the amount of light attenuation after cleaning when cleaning is performed at an arbitrary timing by applying the approximate line 104 starting from the amount of light attenuation immediately after the cleaning. .

In either case of prediction, the accuracy of prediction improves as the number of measurement points increases. The dirt correction unit 42 may change the prediction approximation method according to the increase in the number of measurement points. Changing the approximation method is, for example, changing the order in the approximation formula.

The stain correction unit 42 of this example may estimate the time when the predicted value of the amount of light attenuation exceeds the allowable value. The allowable value may be a value predetermined by the user, or may be a value determined for each device. The predicted value may be calculated using either of the two types of predictions described above. The time when the tolerable value is exceeded when predicting the amount of light attenuation due to dirt that cannot be removed by cleaning corresponds to t ₁ in the figure, and the time when the amount of light attenuation due to all dirt is exceeded when predicting the amount of light attenuation due to all dirt is exceeded. The period corresponds to t ₂ in the figure. By estimating the time when the permissible value is exceeded, the maintenance time and usage limit time can be estimated.

The dirt correction unit 42 may sequentially correct the correction value of the amount of light attenuation during subsequent measurements based on the prediction of the amount of light attenuation. Thereby, it is possible to take into account the influence of dirt that accumulates after measuring the amount of optical attenuation and perform correction.

FIG. 8 is a diagram showing an example of a water quality analyzer 100 according to another embodiment of the present invention. The water quality analyzer 100 of this example has the same configuration as the example described in FIG. 4, but differs in that the cleaning section 50 and the dirt correction section 42 cooperate. This embodiment may also be added to any of the configurations shown in FIGS. 1 to 6. The cleaning section 50 of this example changes the cleaning method depending on the prediction of the amount of light attenuation described above. If the increase in soiling is expected to be greater than previously, a more aggressive cleaning method than the previous cleaning method may be employed. Further, if the estimated time when the predicted value of the amount of light attenuation exceeds the allowable value is closer than the predetermined reference time, a more powerful cleaning method than before may be adopted. As a cleaning method, the flow cell 20 may be washed by flowing clean water or a cleaning liquid containing chemicals into the internal space 24 of the flow cell 20, or cleaning may be performed using a cleaning liquid with a different pH, and the internal space may be cleaned using a member such as a brush. The flow cell 20 may be cleaned by sweeping 24, or the flow cell 20 may be cleaned by a combination of these methods. When the cleaning method is changed, the cleaning unit 50 may select the cleaning method for the next cleaning according to the change in the amount of optical attenuation before and after cleaning.

The cleaning unit 50 may determine whether cleaning of the flow cell 20 has been completed based on the detection result of the amount of optical attenuation. The determination is made, for example, based on whether the amount of optical attenuation is less than a predetermined value. The predetermined value may be a value unique to the device or may be a value depending on the type of sample water. If the cleaning does not end within a set period from the start of cleaning the flow cell 20, the cleaning method may be changed. Further, the cleaning unit 50 may select a cleaning method for the flow cell 20 based on the history of sample water that has been passed through the flow cell 20 in the past. Selection of a cleaning method based on the history of sample water means, for example, selecting the type and pH of a cleaning liquid that is known to be effective against stains attached by a certain sample water. The sample water history may include information indicating the types of dirt components contained in the sample water.

FIG. 9 is a diagram showing another example of predicting future optical attenuation based on past optical attenuation. The dirt correction unit 42 of this example calculates the rate of increase in the amount of light attenuation from the past history of the amount of light attenuation from one cleaning to the next cleaning, and based on the increase rate, the amount of light attenuation from one cleaning to the next cleaning. make predictions. The amount of light attenuation includes the amount of light attenuation due to dirt that can be removed by cleaning and the amount of light attenuation due to dirt that cannot be removed. The stain correction unit 42 corrects the measurement result of the concentration of the substance to be measured based on the prediction of the change in the amount of light attenuation. The dirt correction unit 42 may sequentially correct the correction value of the amount of light attenuation during subsequent measurements based on the prediction of the amount of light attenuation. Thereby, it is possible to take into account the influence of dirt that accumulates after measuring the amount of optical attenuation and perform correction. Further, the timing of the next cleaning may be determined based on the prediction of the change in the amount of optical attenuation. This means, for example, that cleaning is performed when the predicted change in optical attenuation exceeds a permissible value.

When detecting the amount of optical attenuation between one wash and the next wash, the flow rate of the reference water flowing through the flow cell 20 may be set to be lower than the flow rate of the sample water when measuring the concentration of the substance to be measured. Thereby, it is possible to prevent dirt from being removed by the flow rate of the reference water, and it is possible to more accurately predict the amount of light attenuation. The flow rate of the reference water may be lower than the flow rate of the sample water, and may be 80% or less.

When detecting the amount of optical attenuation between one cleaning and the next cleaning, the flow rate of the reference water flowing through the flow cell 20 may be set to be lower than the flow rate of the cleaning water flowing during cleaning. This can prevent dirt that has not been removed by cleaning from being removed by the reference water, allowing more accurate prediction of the amount of light attenuation. The flow rate of the reference water may be lower than the flow rate of the wash water, and may be 80% or less.

FIG. 10 is a diagram showing an example of a water quality analysis device 100 according to another embodiment of the present invention. The water quality analyzer 100 of this example includes a scattered light amount detection section 86 in addition to any of the configurations described in FIGS. 1 to 8. In addition to the configuration shown in FIG. 1, FIG. 10 includes a scattered light amount detection section 86. The scattered light amount detection unit 86 detects the scattered light 96 from the flow cell 20 and includes a scattered light detection optical system 80 that outputs an electrical signal, and a scattered light signal processing unit 82 that performs signal processing such as amplification or noise removal on the electrical signal. Equipped with. Further, in this example, the transmitted light detection optical system 70 and the transmitted light detection signal processing section 72 are collectively referred to as a transmitted light detection section 76. In this example, the dirt detection section 40 calculates the amount of light attenuation based on the amount of transmitted light outputted from the transmitted light detection section 76 and the amount of scattered light outputted from the scattered light amount detection section 86 while the reference water is flowing through the flow cell 20. Detect. By taking the amount of scattered light into consideration, the amount of optical attenuation can be detected more accurately.

In each embodiment, not only the measurement light 92 but also the transmitted light 94 and the scattered light 96 may be corrected using the amount of optical attenuation. Thereby, the concentration of the substance to be measured can be measured more accurately.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the range described in the above embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the embodiments described above. It is clear from the claims that such modifications or improvements may be included within the technical scope of the present invention.

The order of execution of each process, such as the operation, procedure, step, and stage in the apparatus, system, program, and method shown in the claims, specification, and drawings, is specifically defined as "before" or "before". It should be noted that they can be implemented in any order unless the output of the previous process is used in the subsequent process. Even if the claims, specifications, and operational flows in the drawings are explained using "first," "next," etc. for convenience, this does not mean that it is essential to carry out the operations in this order. It's not a thing.

DESCRIPTION OF SYMBOLS 10... Light source, 20... Flow cell, 22... Wall part, 24... Internal space, 30... Concentration detection optical system, 32... Concentration detection signal processing section, 36... Concentration Measuring section, 40... Stain detection section, 42... Stain correction section, 46... Memory, 50... Cleaning section, 60... Light source light amount monitor, 62... Correction processing section, 70. ...Transmitted light detection optical system, 72... Transmitted light detection signal processing section, 76... Transmitted light detection section, 80... Scattered light detection optical system, 82... Scattered light signal processing section, 86. ...Scattered light amount detection unit, 91...Light, 92...Measurement light, 93...Branched light, 94...Transmitted light, 96...Scattered light, 100...Water quality analyzer, 102 ...Approximate line, 104...Approximate line

Claims (14)

A water quality analyzer that measures the concentration of a target substance contained in sample water,
A flow cell having a wall that transmits light and an internal space surrounded by the wall, and through which the sample water passes through the internal space;
a light source that irradiates light toward the flow cell;
With the sample water flowing through the flow cell, the concentration of the substance to be measured contained in the sample water is measured based on the measured light from the flow cell when the flow cell is irradiated with light source light from the light source. a concentration measuring section,
a dirt detection unit that detects the amount of light attenuation due to dirt on the flow cell based on the amount of the light to be measured from the flow cell in a state where reference water having a known concentration of the substance to be measured is flowing through the flow cell;
A water quality analysis device comprising: a dirt correction section that corrects a measurement result of the concentration of the substance to be measured when the sample water is passed, based on the amount of light attenuation due to dirt in the flow cell. The dirt correction unit stores the detected amount of light attenuation due to dirt on the flow cell, and uses the stored amount of light attenuation to correct the amount of light attenuation until the next time the amount of light attenuation due to dirt on the flow cell is detected. The water quality analysis device according to claim 1, wherein the measurement result of the concentration of the substance to be measured is corrected. further comprising a cleaning section for cleaning the flow cell,
The water quality analysis device according to claim 1 or 2, wherein the dirt detection section detects the light attenuation amount by flowing the reference water through the flow cell before flowing the sample water after washing the flow cell. The method further includes a light source light amount monitor that detects the amount of light from the light source that enters the flow cell, and the dirt detection section detects the amount of light attenuation using the amount of light from the light source when measuring the reference water. The water quality analysis device according to claim 1 or 2. The water quality analysis device according to claim 1, wherein the dirt correction section maintains a history of attenuation information corresponding to the light attenuation measured in the past, and predicts the light attenuation in the future. The water quality analysis device according to claim 5, wherein the stain correction unit estimates a time when the predicted value of the amount of light attenuation exceeds a tolerance value. further comprising a cleaning section for cleaning the flow cell,
The dirt detection unit detects the light attenuation amount by flowing the reference water into the flow cell after washing the flow cell and before flowing the sample water,
The water quality analysis device according to claim 5, wherein the cleaning section changes the cleaning method according to the prediction of the amount of light attenuation. The water quality analysis device according to claim 7, wherein the cleaning method for the next cleaning is selected according to a change in the amount of light attenuation before and after cleaning when the cleaning method is changed. The dirt detection unit detects the light attenuation using the reference water multiple times between washing and the next washing, and detects the amount of light attenuation during the period until the next washing based on the rate of increase in the light attenuation. predicting a change in the optical attenuation of
The water quality analysis device according to claim 3, wherein the stain correction section corrects the measurement result of the concentration of the substance to be measured based on the prediction of the change in the amount of light attenuation. When detecting the amount of optical attenuation between one wash and the next wash, the flow rate of the reference water is set to be equal to or lower than the flow rate of the sample water when measuring the concentration of the substance to be measured contained in the sample water. The water quality analysis device according to claim 9. The water quality analyzer according to claim 9, wherein when detecting the amount of optical attenuation from one wash to the next wash, the flow rate of the reference water is set to be equal to or lower than the flow rate of the wash water used during washing. The cleaning section determines whether or not cleaning of the flow cell is completed based on the detection result of the amount of light attenuation, and if the cleaning is not completed within a set period from the start of cleaning of the flow cell, cleaning in the cleaning section is performed. The water quality analysis device according to claim 3, wherein the method is changed. The water quality analyzer according to claim 3, wherein the cleaning section selects a cleaning method for the flow cell based on a history of the sample water that has been passed through the flow cell in the past. a transmitted light detection unit that detects the amount of transmitted light that is the amount of transmitted light that has passed through the flow cell;
further comprising a scattered light amount detection unit that detects the amount of scattered light that is the amount of scattered light from the reference water,
The water quality according to claim 1 or 2, wherein the dirt detection unit detects the amount of light attenuation due to dirt in the flow cell based on the amount of transmitted light and the amount of scattered light when the reference water is flowing through the flow cell. Analysis equipment.

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