Water quality analysis device

Abstract

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

Description

[Technical Field]

[0001] The present invention relates to a water quality analyzer. [Background Art]

[0002] Conventionally, water quality analyzers that analyze the quality of sample water are known (see, for example, Patent Documents 1 and 2). [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent No. 6436266 [Patent Document 2] Japanese Unexamined Patent Publication No. 2007-46978 [Summary of the Invention] [Problem to be Solved by the Invention]

[0003] When dirt accumulates in a portion of a water quality analyzer through which sample water flows, a detection signal indicating the concentration of a measurement target substance contained in the sample water fluctuates. [Means for Solving the Problem]

[0004] In a first aspect of the present invention, a water quality analyzer is provided. The water quality analyzer may include a flow cell. Any of the above water quality analyzers may include a light source. Any of the above water quality analyzers may include a concentration measuring unit. Any of the above water quality analyzers may include a fouling detection unit. Any of the above water quality analyzers may include a fouling correction unit. In any of the above water quality analyzers, the flow cell may have walls that transmit light. In any of the above water quality analyzers, the flow cell may have an internal space surrounded by walls through which the sample water passes. In any of the above water quality analyzers, the light source may irradiate the flow cell with light. In any of the above water quality analyzers, the concentration measuring unit may measure the concentration of the substance to be measured in the sample water based on the light to be measured from the flow cell when the light source irradiates the flow cell with light from the light source while the sample water is flowing through the flow cell. In any of the above water quality analyzers, the fouling detection unit may detect the amount of light attenuation due to fouling of the flow cell based on the amount of light to be measured from the flow cell while reference water with a known concentration of the substance to be measured is flowing through the flow cell. In any of the above water quality analyzers, the fouling correction unit may correct the measurement result of the concentration of the target substance when the sample water is flowed through it, based on the amount of light attenuation due to fouling of the flow cell.

[0005] In any of the above-mentioned water quality analyzers, the fouling correction unit may store the amount of light attenuation due to fouling of the flow cell that has been detected, and use the stored amount of light attenuation to correct the measurement result of the concentration of the target substance until the next amount of light attenuation due to fouling of the flow cell is detected.

[0006] Any of the above water quality analyzers may further include a cleaning unit. In any of the above water quality analyzers, the contamination detection unit may, after cleaning the flow cell and before flowing the sample water, flow reference water through the flow cell to detect the amount of light attenuation.

[0007] Any of the above water quality analyzers may further include a light source intensity monitor. In any of the above water quality analyzers, the light source intensity monitor may detect the amount of light from the light source incident on the flow cell. In any of the above water quality analyzers, the contamination detection unit may detect the amount of light attenuation using the amount of light from the light source when measuring the reference water.

[0008] In any of the above-mentioned water quality analyzers, the fouling correction unit may retain a history of attenuation information corresponding to the amount of light attenuation measured in the past and predict future amounts of light attenuation.

[0009] In any of the above-mentioned water quality analyzers, the fouling correction unit may estimate the time when the predicted value of the light attenuation exceeds the permissible value.

[0010] Any of the above water quality analyzers may further include a cleaning unit. In any of the above water quality analyzers, the contamination detection unit may, after cleaning the flow cell and before flowing the sample water, flow reference water through the flow cell to detect the amount of light attenuation. In any of the above water quality analyzers, the cleaning unit may change the cleaning method according to the predicted amount of light attenuation.

[0011] In any of the above-mentioned water quality analyzers, the cleaning unit may select the next cleaning method according to the change in the amount of light attenuation before and after cleaning when the cleaning method is changed.

[0012] In any of the above water quality analyzers, the contamination detection unit may detect the amount of light attenuation using reference water multiple times between washes and predict the change in the amount of light attenuation between washes based on the rate of increase of the amount of light attenuation. In any of the above water quality analyzers, the contamination correction unit may correct the measurement result of the concentration of the target substance based on the prediction of the change in the amount of light attenuation.

[0013] In any of the above-mentioned water quality analyzers, when detecting the amount of light attenuation between washes, the flow rate of the reference water may be set to be less than or equal to the flow rate of the sample water used when measuring the concentration of the target substance contained in the sample water.

[0014] In any of the above-mentioned water quality analyzers, when detecting the amount of light attenuation between washes, the flow rate of the reference water may be set to be less than or equal to the flow rate of the wash water used during the wash.

[0015] In any of the above-mentioned water quality analyzers, the cleaning unit determines whether the cleaning of the flow cell is complete 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 the flow cell, the cleaning unit may change the cleaning method.

[0016] In any of the above-mentioned water quality analyzers, the cleaning unit may select a method for cleaning the flow cell based on the history of sample water previously flowed through the flow cell.

[0017] Any of the above water quality analyzers may further include a transmitted light detection unit and a scattered light intensity detection unit. In any of the above water quality analyzers, the transmitted light detection unit may detect the transmitted light intensity, which is the amount of transmitted light that has passed through the flow cell. In any of the above water quality analyzers, the scattered light intensity detection unit may detect the scattered light intensity, which is the amount of scattered light from the reference water. In any of the above water quality analyzers, the fouling detection unit may detect the amount of light attenuation due to fouling of the flow cell based on the transmitted light intensity and scattered light intensity when the reference water is flowing through the flow cell.

[0018] It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. Furthermore, subcombinations of these features may also constitute an invention. [Brief explanation of the drawing]

[0019] [Figure 1] This figure shows an example of a water quality analyzer 100 according to one embodiment of the present invention. [Figure 2] This diagram explains the correction applied to the measurement results for the concentration of the substance being measured. [Figure 3] This figure shows an example of a water quality analyzer 100 according to another embodiment of the present invention. [Figure 4] This figure shows an example of a water quality analyzer 100 according to another embodiment of the present invention. [Figure 5] It is a flowchart showing an operation example of the water quality analyzer 100 in the embodiment of FIG. 4 [Figure 6] It is a diagram showing an example of the water quality analyzer 100 according to another embodiment of the present invention [Figure 7] It is a diagram where prediction of subsequent light attenuation amounts is performed based on past light attenuation amounts [Figure 8] It is a diagram showing an example of the water quality analyzer 100 according to another embodiment of the present invention [Figure 9] It is a diagram showing another example of performing prediction of subsequent light attenuation amounts based on past light attenuation amounts [Figure 10] It is a diagram showing an example of the water quality analyzer 100 according to another embodiment of the present invention MODE FOR CARRYING OUT THE INVENTION

[0020] Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention claimed in the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention

[0021] Figure 1 shows an example of a water quality analyzer 100 according to one embodiment of the present invention. The water quality analyzer 100 measures the concentration of a target substance contained in a sample water. The water quality analyzer 100 in this example comprises a light source 10, a flow cell 20, a concentration measurement unit 36, a transmitted light detection optical system 70, a transmitted light detection signal processing unit 72, a contamination detection unit 40, and a contamination correction unit 42. The concentration measurement unit 36 ​​comprises a concentration detection optical system 30 and a concentration detection signal processing unit 32. The concentration detection optical system 30 and the transmitted light detection optical system 70 are devices that detect the amount of light received using a light-receiving element such as a CCD or a photodiode. In this specification, the amount of light is the total amount of light flux (lm / S) passing through a predetermined surface in 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 an electrical signal corresponding to the detected amount of light. The concentration detection signal processing unit 32 and the transmitted light detection signal processing unit 72 perform signal processing such as amplification or noise reduction on the electrical signal.

[0022] The light source 10 irradiates light 91 toward the flow cell 20. The flow cell 20 has a wall portion 22 and an internal 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, for example, glass. The wall portion 22 may have a window portion through which light 91 enters or exits, and a support portion that supports the window portion. In this specification, the window portion through which light 91 enters or exits may be described as the wall portion 22. The internal space 24 is surrounded by the wall portion 22. Sample water passes through the internal space 24. As an example, the wall portion 22 has a cylindrical shape. Figure 1 schematically shows a cross-section of the wall portion 22 and the internal space 24.

[0023] 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 light at at least one wavelength of the measurement light 92. The measurement light 92 is the light emitted from the flow cell 20 when light 91 is irradiated from the light source 10 while the sample water is present in the flow cell 20. The measurement light 92 may include fluorescence emitted from the substance to be measured when light 91 is irradiated onto the substance to be measured contained in the sample water. In this case, the concentration detection optical system 30 may measure the amount of light of the measurement light 92 at a wavelength different from that of light 91.

[0024] The concentration detection signal processing unit 32 calculates the concentration of the target substance contained in the sample water based on the measurement results from the concentration detection optical system 30. The sample water is, for example, tap water, sewage water, seawater, or wastewater from a factory, but is not limited to these. If the sample water contains fluorescent substances such as polycyclic aromatic hydrocarbons (PAHs), irradiating the sample water with ultraviolet light 91 generates fluorescence (measurement light 92) at a wavelength specific to the substance. Since the fluorescence intensity is proportional to the concentration of the fluorescent substance contained, the concentration of the target substance, the fluorescent substance, can be accurately measured by measuring the amount of measurement light 92 at that wavelength. The concentration detection signal processing unit 32 outputs the measurement results to the contamination correction unit 42.

[0025] If contamination occurs on the wall portion 22 of the flow cell 20, the intensity of the light 91 or measurement light 92 will be attenuated by the contamination. If the wall portion 22 is provided with the aforementioned window portion, the contamination of the wall portion 22 refers to the contamination of the window portion. The contamination of the wall portion 22 refers to, for example, foreign matter adhering to the inner or outer surface of the wall portion 22. When the intensity of the light 91 or 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 for the effect of contamination occurring on the wall portion 22 of the flow cell 20.

[0026] The dirt detection unit 40 detects dirt on the wall 22. The dirt detection unit 40 may detect dirt on the wall 22 triggered by a predetermined operation in the water quality analyzer 100. The dirt detection unit 40 may also detect dirt on the wall 22 at intervals of a set detection period. The dirt detection unit 40 may also detect dirt on the wall 22 in response to instructions from the user or others.

[0027] 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 the water quality analyzer 100 detects dirt on the wall 22, it may flow reference water with a known concentration of the substance to be measured into the flow cell 20. The concentration of the substance to be measured in the reference water may be less than or equal to the detection limit or resolution of the concentration measurement unit 36. The turbidity of the reference water may be 1 FNU or less. The wavelength of the light 91 used to detect dirt may be different from the wavelength of the light 91 used to measure the fluorescence of the substance to be measured. The light source 10 may have a light source unit that irradiates light 91 for detecting dirt and a light source unit that irradiates light 91 for detecting fluorescence.

[0028] The transmitted light detection optical system 70 detects transmitted light 94 that has passed through the flow cell 20 after light 91 has entered the flow cell 20. The transmitted light detection optical system 70 may detect the light emitted as transmitted light 94 after light 91 has traveled straight through the inside of the flow cell 20. The wall portion 22 may be provided with a window for light 91 to enter, a window for measurement light 92 to exit, and a window for transmitted light 94 to exit. 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 at a set wavelength. The transmitted light detection optical system 70 outputs an electrical signal indicating the amount of transmitted light to the contamination detection unit 40. The transmitted light detection signal processing unit 72 may perform signal processing such as amplification or noise reduction on the electrical signal. Alternatively, 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 unit 72 instead of the concentration measurement unit 36.

[0029] When dirt adheres to the wall portion 22, the intensity of light is attenuated by the dirt, so the amount of transmitted light 94 decreases. Therefore, the degree of dirt on the wall portion 22 can be estimated by detecting how much the amount of transmitted light 94 is attenuated relative to the amount of light 91 emitted from the light source 10. In this example, the amount of attenuation of the amount of transmitted light 94 relative to the light 91 is called the light attenuation amount. The dirt detection unit 40 calculates the light attenuation amount and outputs it to the dirt correction unit 42.

[0030] Figure 2 illustrates the correction of the measurement results for the concentration of the target substance. The fouling correction unit 42 performs the correction based on the amount of light attenuation. The vertical axis in Figure 2 shows the concentration or the correction value for correcting the concentration. 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. In the figure, A shows the measurement result of the concentration of the target substance before correction by the amount of light attenuation. In this example, the concentration of the target substance is calculated based on the amount of transmitted light 94. When the transmitted light 94 is attenuated by fouling in the flow cell 20, the concentration of the target substance in the measurement result before correction increases. Therefore, as time passes and fouling accumulates in the flow cell 20, the concentration of the target substance in the measurement result before correction increases. In the figure, B shows the correction amount based on the amount of light attenuation. The correction amount based on the amount of light attenuation is, as an example, the difference between the measured amount of light attenuation and the amount of light attenuation at calibration. The correction amount based on the amount of light attenuation can be obtained from the following formula as an example. Correction amount due to light attenuation = Measured light attenuation - Light attenuation during calibration The correction amount based on the light attenuation also increases in accordance with the amount of dirt that accumulates on the flow cell 20 over time.

[0031] In the figure, C represents the concentration of the measured substance after correction using a correction amount based on optical attenuation. The correction is performed, for example, by subtracting the correction amount based on optical attenuation from the original concentration. The correction is performed according to the following formula, for example. Corrected density = Uncorrected density - Correction amount due to light attenuation The concentration of the target substance before correction, which does not take into account the effect of contamination in flow cell 20, increases with the accumulation of contamination in flow cell 20. However, by performing a correction based on the amount of light attenuation, the corrected concentration becomes almost constant. In other words, a result closer to the original concentration of the target substance is obtained.

[0032] In this example, we have explained the case where the concentration of the substance to be measured is calculated based on transmitted light 94, but this correction can also be applied when calculating the concentration of the substance to be measured based on measurement light 92. In that case, the correction amount due to the amount of light attenuation and the signs of addition and subtraction in the formula for the corrected concentration are determined based on the generation principle of measurement light 92.

[0033] Figure 3 shows an example of a water quality analyzer 100 according to another embodiment of the present invention. In addition to the configuration described in Figure 1, the water quality analyzer 100 in this example is equipped with a memory 46. The memory 46 stores the amount of light attenuation detected by the contamination detection unit 40. The contamination correction unit 42 may use the stored amount of light attenuation to correct the measurement result of the concentration of the substance to be measured until the next amount of light attenuation due to contamination of the flow cell 20 is detected.

[0034] Figure 4 shows an example of a water quality analyzer 100 according to another embodiment of the present invention. In this example, the water quality analyzer 100 includes a cleaning unit 50 in addition to any of the configurations described in Figures 1 to 3. In Figure 4, the cleaning unit 50 is added to the configuration shown in Figure 1. The cleaning unit 50 cleans the flow cell 20. The cleaning unit 50 may clean the flow cell 20 by flowing clean water or a cleaning solution containing chemicals, etc., into the internal space 24 of the flow cell 20, or by using cleaning solutions with different pH levels, or by sweeping the internal space 24 with a brush or other component, or by combining these methods to clean the flow cell 20.

[0035] Figure 5 is a flowchart illustrating an example of the operation of the water quality analyzer 100 in the embodiment shown in Figure 4. In the trigger stage S200, the water quality analyzer 100 determines whether a predetermined cleaning trigger has been input. If a predetermined cleaning trigger has been input, the water quality analyzer 100 performs a cleaning process of the flow cell 20 (S202-S210). This trigger signal may be input in response to user operation, automatically in response to changes in the surrounding environment, automatically at predetermined intervals, or in response to other factors. While no cleaning trigger is input, the water quality analyzer 100 may perform a measurement process of the sample water (S212-S220).

[0036] When a cleaning trigger is input, in cleaning stage S202, the cleaning unit 50 cleans the flow cell 20. After the cleaning of the flow cell 20 is completed, in reference water flow stage S204, the water quality analyzer 100 flows reference water with a known concentration of the substance to be measured into the flow cell in order to obtain the amount of light attenuation. In the post-cleaning signal processing stage S206, light 91 is incident from the light source 10 onto the flow cell 20 through which the reference water is flowing. The transmitted light detection optical system 70 detects the transmitted light 94 that has passed through the cleaned flow cell 20. The transmitted light detection signal processing unit 72 may perform signal processing such as amplification or noise reduction on the electrical signal output by the transmitted light detection optical system 70.

[0037] In the signal correction processing step S208, the transmitted light detection signal processing unit 72 performs arbitrary correction processing on the electrical signal output by the transmitted light detection optical system 70. This correction processing includes, for example, a process to correct fluctuations in the amount of transmitted light 94 due to fluctuations in the amount of light 91, or a process to correct the nonlinearity of the magnitude of the electrical signal with respect to the amount of light received by the transmitted light detection optical system 70.

[0038] In the light attenuation acquisition stage S210, the dirt detection unit 40 acquires the light attenuation. In this example, the dirt detection unit 40 acquires the light attenuation by flowing reference water into the flow cell 20 after the cleaning unit 50 has cleaned the flow cell 20. This makes it possible to acquire the light attenuation due to dirt that cannot be completely removed by cleaning alone. The correction amount due to the light attenuation in this example can be calculated using the following formula as an example. Correction amount due to light attenuation = Light attenuation after cleaning - Light attenuation during calibration The dirt detection unit 40 outputs the amount of light attenuation or the amount of correction based on the amount of light attenuation to the dirt correction unit 42.

[0039] After the cleaning is complete or if no predetermined cleaning trigger signal is input, the water quality analyzer 100 flows the sample water into the flow cell 20 during the sample water flow stage S212. During the measurement signal processing stage S214, the concentration measurement unit 36 ​​detects the amount of light from the measurement light 92 and measures the sample water. The concentration measurement unit 36 ​​outputs the measurement result to the contamination correction unit 42.

[0040] In the measurement light intensity and other correction processing S216, the concentration detection signal processing unit 32 performs arbitrary correction processing on the electrical signal output by the concentration detection optical system 30. This correction processing includes, for example, a process to correct fluctuations in the amount of transmitted light 94 due to fluctuations in the amount of light 91, or a process to correct the nonlinearity of 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 correction processing step S218, the contamination correction unit 42 corrects the measurement result of the concentration of the substance to be measured using the light attenuation. In this example, the contamination correction unit 42 corrects a value that has been converted to concentration in advance in the light attenuation correction processing step S218, but it may also acquire the detection signal before it is converted to concentration in the light attenuation correction processing step S218, correct the detection signal, and then convert it to concentration.

[0041] Figure 6 shows an example of a water quality analyzer 100 according to another embodiment of the present invention. In this example, the water quality analyzer 100 includes a light source intensity monitor 60 and a correction processing unit 62 in addition to any of the configurations described in Figures 1 to 4. In Figure 6, in addition to the configuration shown in Figure 1, a light source intensity monitor 60 and a correction processing unit 62 are included. The light source intensity monitor 60 detects the light source intensity of the light 91 before it enters the flow cell 20. The light source intensity monitor 60 may receive branched light 93 obtained by branching a portion of the light 91. The correction processing unit 62 performs signal processing such as amplification of the detection signal and noise reduction. The light source intensity is output to the contamination detection unit 40.

[0042] In this example, the dirt detection unit 40 detects dirt on the wall portion 22 of the flow cell 20 based on the light intensity of the light source and the transmitted light intensity. The dirt detection unit 40 corrects the transmitted light intensity with the light intensity of 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 transmitted light intensity so that it increases as the light intensity of the light source decreases, and determines that the degree of dirt on the wall portion 22 is greater the smaller the corrected transmitted light intensity. As another example, the dirt detection unit 40 detects dirt on the wall portion 22 based on the light intensity ratio of the light intensity of the light source and the transmitted light intensity (transmitted light intensity / light intensity of the light source). The dirt detection unit 40 determines that the degree of dirt is greater the smaller the light intensity ratio. In this way, by detecting dirt on the wall portion 22 using the light intensity of the light source and the transmitted light intensity, the effects of deterioration of the light source 10 and other factors can be reduced, and dirt on the wall portion 22 can be detected with high accuracy.

[0043] Figure 7 shows how future light attenuation is predicted based on past light attenuation. The dirt correction unit 42 in this example maintains a history of attenuation information of previously measured light attenuation and predicts future light attenuation. The circles in the figure indicate past measurement results. The dirt correction unit 42 may perform at least one of two types of predictions. One of the two types of predictions is a prediction of light attenuation due to dirt that cannot be removed by washing. In this prediction, future light attenuation is predicted based on the light attenuation obtained after washing and before the sample water is flushed. The solid line in the figure represents this prediction. The dirt correction unit 42 may predict future light attenuation by approximating the change in measurement results immediately after washing with an approximation line 102 such as a straight line or curve. The dirt correction unit 42 may store information about the approximation line 102 as attenuation information. Since this prediction is a prediction of light attenuation due to dirt that cannot be removed by washing, it is possible to predict over the usage period regardless of whether subsequent washing is performed or not.

[0044] Another prediction is the prediction of the amount of light attenuation due to all dirt, including dirt that can be completely removed by washing. In this prediction, multiple measurements are taken between washes, and the subsequent amount of light attenuation is predicted based on the changes in the amount of light 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 changes in multiple measurement results between washes with an approximation line 104 such as a straight line or curve. The dirt correction unit 42 may store information about the approximation line 104 as attenuation information. The dirt correction unit 42 may make predictions based on the attenuation information of the amount of light attenuation between multiple washes in the past. Since this prediction includes the effect of dirt that can be completely removed by washing, the range of the prediction is from one wash to the next. The dirt correction unit 42 can apply the attenuation information from past washes to any subsequent washes.

[0045] The dirt correction unit 42 may estimate future light attenuation by combining attenuation information related to the approximation line 102 and attenuation information related to the approximation line 104. For example, the dirt correction unit 42 uses the approximation line 102 to estimate the light attenuation immediately after cleaning, which can be performed at any future time. The dirt correction unit 42 can then apply the approximation line 104, starting from the light attenuation immediately after cleaning, to estimate the progression of light attenuation after cleaning, assuming cleaning is performed at any given time.

[0046] In either prediction method, the accuracy of the prediction improves as the number of measurement points increases. The contamination correction unit 42 may change the prediction approximation method in accordance with the increase in the number of measurement points. Changing the approximation method means, for example, changing the order of the approximation formula.

[0047] The dirt correction unit 42 in this example may estimate the time when the predicted value of the light attenuation exceeds the permissible value. The permissible value may be a value predetermined by the user, or it may be a value determined for each piece of equipment. The predicted value may be calculated using either of the two types of predictions described above. The time when the permissible value is exceeded when using the prediction of light attenuation due to dirt that cannot be completely removed by cleaning corresponds to t1 in the figure, and the time when the permissible value is exceeded when using the prediction of light attenuation due to all types of dirt corresponds to t2 in the figure. By estimating the time when the permissible value is exceeded, maintenance timing and usage limit timing can be estimated.

[0048] The dirt correction unit 42 may sequentially adjust the correction value for the light attenuation during subsequent measurements based on the prediction of the light attenuation. This allows the correction to take into account the effects of dirt that accumulates after the measurement of light attenuation.

[0049] Figure 8 shows an example of a water quality analyzer 100 according to another embodiment of the present invention. The water quality analyzer 100 in this example has the same configuration as the embodiment described in Figure 4, but differs in that the cleaning unit 50 and the fouling correction unit 42 are in cooperation. This embodiment may also be added to any of the configurations in Figures 1 to 6. The cleaning unit 50 in this example changes the cleaning method according to the predicted amount of light attenuation. If an increase in fouling is predicted to be greater than before, a stronger cleaning method than the previous cleaning method may be adopted. Also, if the estimated time when the predicted value of the amount of light attenuation exceeds the allowable value becomes closer than a predetermined reference time, a stronger cleaning method than before may be adopted. As a cleaning method, the flow cell 20 may be cleaned by flowing clean water or a cleaning solution containing chemicals, etc., into the internal space 24 of the flow cell 20, cleaning may be done using cleaning solutions with different pH values, cleaning may be done by sweeping the internal space 24 with a brush or other member, or a combination of these may be used to clean the flow cell 20. 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 light attenuation before and after cleaning.

[0050] The cleaning unit 50 may determine whether the cleaning of the flow cell 20 is complete based on the detection result of the light attenuation amount. This determination is made, for example, by determining whether the light attenuation amount falls below a predetermined value. The predetermined value may be a value specific to the device, or it may be a value corresponding to the type of sample water. If the cleaning of the flow cell 20 is not completed within a set period from the start of cleaning, the cleaning method may be changed. The cleaning unit 50 may also select a cleaning method for the flow cell 20 based on the history of sample water that has been flowed through the flow cell 20 in the past. Selecting a cleaning method based on the history of sample water means, for example, selecting a type of cleaning solution and pH that has been shown to be effective against the dirt that adheres to a particular sample water. The history of sample water may include information indicating the types of dirt components contained in the sample water.

[0051] Figure 9 shows another example of predicting future light attenuation based on past light attenuation. In this example, the fouling correction unit 42 calculates the rate of increase in light attenuation from the past history of light attenuation between washes, and predicts the light attenuation until the next wash based on this. This light attenuation includes light attenuation due to dirt that can be removed by washing and light attenuation due to dirt that cannot be removed. The fouling correction unit 42 corrects the measurement result of the concentration of the substance to be measured based on the prediction of the change in light attenuation. The fouling correction unit 42 may sequentially adjust the correction value of light attenuation for subsequent measurements based on the prediction of light attenuation. This makes it possible to correct even the effect of dirt that accumulates after the measurement of light attenuation. The timing of the next wash may also be determined based on the prediction of the change in light attenuation. This means, for example, that wash is performed when the prediction of the change in light attenuation exceeds an acceptable value.

[0052] When detecting the amount of light attenuation between washes, the flow rate of the reference water flowing through the flow cell 20 may be set to be less than or equal to the flow rate of the sample water used when measuring the concentration of the substance to be measured. This prevents the removal of contaminants by the flow rate of the reference water, allowing for a 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 sample water, and may be 80% or less.

[0053] When detecting the amount of light attenuation between washes, the flow rate of the reference water flowing through the flow cell 20 may be set to be less than or equal to the flow rate of the wash water flowing during the wash. This prevents dirt that was not removed during the wash from being removed by the reference water, allowing for a more accurate prediction of the amount of light attenuation. The flow rate of the reference water may be less than the flow rate of the wash water, and may be 80% or less.

[0054] Figure 10 shows an example of a water quality analyzer 100 according to another embodiment of the present invention. In this example, the water quality analyzer 100 includes a scattered light intensity detection unit 86 in addition to any of the configurations described in Figures 1 to 8. In Figure 10, the scattered light intensity detection unit 86 is included in addition to the configuration in Figure 1. The scattered light intensity detection unit 86 includes a scattered light detection optical system 80 that detects scattered light 96 from the flow cell 20 and outputs an electrical signal, and a scattered light signal processing unit 82 that performs signal processing such as amplification or noise reduction on the electrical signal. In this example, the transmitted light detection optical system 70 and the transmitted light detection signal processing unit 72 are combined to form the transmitted light detection unit 76. In this example, the contamination detection unit 40 detects the amount of light attenuation based on the amount of transmitted light output from the transmitted light detection unit 76 and the amount of scattered light output from the scattered light intensity detection unit 86 while reference water is flowing through the flow cell 20. By taking the amount of scattered light into consideration, the amount of light attenuation can be detected more accurately.

[0055] In each embodiment, not only the measurement light 92, but also the transmitted light 94 and scattered light 96 may be corrected using the optical attenuation. This allows for more accurate measurement of the concentration of the substance to be measured.

[0056] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0057] It should be noted that the execution order of operations, procedures, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before," "prior to," etc., and that these can be implemented in any order unless the output of a previous process is used in a later process. Even if the operation flow in the claims, specifications, and drawings is described using phrases such as "first," "next," etc. for convenience, it does not mean that it is essential to perform the operations in that order. [Explanation of Symbols]

[0058] 10...Light source, 20...Flow cell, 22...Wall section, 24...Internal space, 30...Concentration detection optical system, 32...Concentration detection signal processing section, 36...Concentration measurement section, 40...Dirt detection section, 42...Dirt correction section, 46...Memory, 50...Washing section, 60...Light source light intensity 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 intensity detection section, 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

1. A water quality analyzer for measuring the concentration of a target substance contained in a sample of water, A flow cell having a light-transmitting wall and an internal space surrounded by the wall, through which the sample water passes the internal space, A light source that irradiates light toward the flow cell, A concentration measuring unit measures the concentration of the substance to be measured in the sample water based on the light emitted from the flow cell when the flow cell is irradiated with light from the light source while the sample water is flowing through the flow cell. A fouling detection unit detects the amount of light attenuation due to fouling 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 flowed through the flow cell. A contamination correction unit corrects the measurement result of the concentration of the target substance when the sample water is flowed, based on the amount of light attenuation due to contamination of the flow cell. Equipped with, The aforementioned contamination correction unit maintains a history of attenuation information corresponding to the previously measured amount of light attenuation and predicts the amount of light attenuation thereafter. Water quality analyzer.

2. The aforementioned dirt correction unit estimates the time when the predicted value of the light attenuation exceeds the allowable value. The water quality analyzer according to claim 1.

3. The system further comprises a cleaning unit for cleaning the flow cell, The aforementioned contamination detection unit, after cleaning the flow cell and before flowing the sample water, flows the reference water into the flow cell to detect the amount of light attenuation. The cleaning unit changes the cleaning method according to the predicted amount of light attenuation. The water quality analyzer according to claim 1.

4. Depending on the change in the amount of light attenuation before and after cleaning when the cleaning method is changed, the cleaning method for the next cleaning will be selected. The water quality analyzer according to claim 3.

5. A water quality analyzer for measuring the concentration of a target substance contained in a sample of water, A flow cell having a light-transmitting wall and an internal space surrounded by the wall, through which the sample water passes the internal space, A light source that irradiates light toward the flow cell, A concentration measuring unit measures the concentration of the substance to be measured in the sample water based on the light emitted from the flow cell when the flow cell is irradiated with light from the light source while the sample water is flowing through the flow cell. A fouling detection unit detects the amount of light attenuation due to fouling 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 flowed through the flow cell. A contamination correction unit corrects the measurement result of the concentration of the target substance when the sample water is flowed through the flow cell based on the amount of light attenuation due to contamination of the flow cell, Cleaning unit for cleaning the flow cell Equipped with, The aforementioned contamination detection unit, after cleaning the flow cell and before flowing the sample water, flows the reference water into the flow cell to detect the amount of light attenuation. The dirt detection unit detects the amount of light attenuation multiple times using the reference water between washes, and predicts the change in the amount of light attenuation between washes based on the rate of increase of the amount of light attenuation. The aforementioned contamination correction unit 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. Water quality analyzer.

6. When detecting the amount of light attenuation between washes, the flow rate of the reference water is set to be less than or equal to 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 analyzer according to claim 5.

7. When detecting the amount of light attenuation between washes, the flow velocity of the reference water is set to be less than or equal to the flow velocity of the wash water used during the wash. The water quality analyzer according to claim 5.

8. The cleaning unit determines whether the cleaning of the flow cell is complete based on the detection result of the light attenuation amount, and if the cleaning of the flow cell is not completed within a set period from the start of cleaning, it changes the cleaning method in the cleaning unit. The water quality analyzer according to claim 5.

9. The cleaning unit selects a cleaning method for the flow cell based on the history of the sample water that has been previously flowed through the flow cell. The water quality analyzer according to claim 5.

10. A water quality analyzer for measuring the concentration of a target substance contained in a sample of water, A flow cell having a light-transmitting wall and an internal space surrounded by the wall, through which the sample water passes the internal space, A light source that irradiates light toward the flow cell, A concentration measuring unit measures the concentration of the substance to be measured in the sample water based on the light emitted from the flow cell when the flow cell is irradiated with light from the light source while the sample water is flowing through the flow cell. A fouling detection unit detects the amount of light attenuation due to fouling 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 flowed through the flow cell. A contamination correction unit corrects the measurement result of the concentration of the target substance when the sample water is flowed through the flow cell based on the amount of light attenuation due to contamination of the flow cell, A transmitted light detection unit detects the amount of transmitted light, which is the amount of light transmitted through the flow cell, Scattered light intensity detection unit that detects the amount of scattered light, which is the amount of scattered light from the reference water. Equipped with, The contamination detection unit detects the amount of light attenuation due to contamination of the flow cell based on the amount of transmitted light and the amount of scattered light when the reference water is flowed through the flow cell. Water quality analyzer.

11. The contamination correction unit stores the amount of light attenuation due to contamination of the flow cell that it has detected, and uses the stored amount of light attenuation to correct the measurement result of the concentration of the substance to be measured until it is time to detect the next amount of light attenuation due to contamination of the flow cell. A water quality analyzer according to any one of claims 1 to 4 or 10.

12. The flow cell is further equipped with a light source intensity monitor that detects the amount of light from the light source incident on the flow cell, and the contamination detection unit detects the amount of light attenuation using the amount of light from the light source when measuring the reference water. A water quality analyzer according to any one of claims 1 to 10.

13. A water quality analyzer for measuring the concentration of a target substance contained in a sample of water, A wall portion having a light-transmitting section, A light source that irradiates light toward the light-transmitting portion, A concentration measuring unit that measures the concentration of the substance to be measured in the sample water based on the light emitted from the light-transmitting part when the light source is irradiated onto the light-transmitting part from the light source while the sample water is flowing through the light-transmitting part, A dirt detection unit detects the amount of light attenuation due to dirt in the light transmission section based on the amount of light to be measured from the light transmission section when reference water with a known concentration of the substance to be measured is flowed through the light transmission section. A dirt correction unit corrects the measurement result of the concentration of the target substance when the sample water is flowed, based on the amount of light attenuation due to the dirt in the light-transmitting part. Equipped with, The aforementioned contamination correction unit is a water quality analyzer that maintains a history of attenuation information corresponding to the previously measured amount of light attenuation and predicts the amount of light attenuation thereafter.

14. A water quality analyzer for measuring the concentration of a target substance contained in a sample of water, A wall portion having a light-transmitting section, A light source that irradiates light toward the light-transmitting portion, A concentration measuring unit that measures the concentration of the substance to be measured in the sample water based on the light emitted from the light-transmitting part when the light source is irradiated onto the light-transmitting part from the light source while the sample water is flowing through the light-transmitting part, A dirt detection unit detects the amount of light attenuation due to dirt in the light transmission section based on the amount of light to be measured from the light transmission section when reference water with a known concentration of the substance to be measured is flowed through the light transmission section. A contamination correction unit corrects the measurement result of the concentration of the target substance when the sample water is flowed, based on the amount of light attenuation due to contamination of the light-transmitting part, Cleaning section for cleaning the light-transmitting section Equipped with, The dirt detection unit, after cleaning the light-transmitting section and before flowing the sample water, flows the reference water through the light-transmitting section to detect the amount of light attenuation. The dirt detection unit detects the amount of light attenuation multiple times using the reference water between washes, and predicts the change in the amount of light attenuation between washes based on the rate of increase of the amount of light attenuation. The aforementioned contamination correction unit is a water quality analyzer that corrects the measurement result of the concentration of the target substance based on the prediction of the change in the amount of light attenuation.

15. A water quality analyzer for measuring the concentration of a target substance contained in a sample of water, A wall portion having a light-transmitting section, A light source that irradiates light toward the light-transmitting portion, A concentration measuring unit that measures the concentration of the substance to be measured in the sample water based on the light emitted from the light-transmitting part when the light source is irradiated onto the light-transmitting part from the light source while the sample water is flowing through the light-transmitting part, A dirt detection unit detects the amount of light attenuation due to dirt in the light transmission section based on the amount of light to be measured from the light transmission section when reference water with a known concentration of the substance to be measured is flowed through the light transmission section. A contamination correction unit corrects the measurement result of the concentration of the target substance when the sample water is flowed, based on the amount of light attenuation due to contamination of the light-transmitting part, A transmitted light detection unit detects the amount of transmitted light, which is the amount of light transmitted through the light-transmitting section, Scattered light intensity detection unit that detects the amount of scattered light, which is the amount of scattered light from the reference water. Equipped with, The aforementioned contamination detection unit is a water quality analyzer that detects the amount of light attenuation due to contamination in the light transmission unit based on the amount of transmitted light and the amount of scattered light when the reference water is flowed through the light transmission unit.

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