JP2005274519A - Method and apparatus for measuring water quality - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for measuring water quality, which enable detection accuracy to be improved significantly, by eliminating phenomena of drop formation and their dropping occurring at an end opening section of a drain pipe for measurement, suppressing flow rate/pressure variations caused by the phenomena and making detection noise lowered. <P>SOLUTION: In the method and the apparatus for measuring water quality, a measurement of the quality of liquid to be measured is carried out under such conditions that the end section of the pipe is submerged in liquid in a container, whose liquid level is maintained at a fixed height, when the liquid to be measured is drained via the pipe, after being introduced into a water quality detecting means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water quality measurement method and apparatus, and in particular, in a system in which a measurement liquid in a flowing state is measured by a detection means, when the detection sensitivity is affected by the flow rate change or temperature change of the measurement liquid. In particular, the present invention relates to a water quality measurement method and apparatus capable of highly accurate measurement while minimizing the influence thereof.

  When measuring the water quality characteristics of a liquid to be measured, such as an aqueous solution, for example, electrical conductivity, the liquid to be measured is transferred (sampled) to the sensor unit (detection means unit) using a liquid feed pump, etc. The electrical conductivity is detected. However, the flow rate and pressure fluctuate with the pulsating flow due to the operation of the liquid pump, which affects the temperature control of the thermostat etc. provided on the way, and the temperature fluctuation causes a minute change in electrical conductivity. As a result, a minute change (noise) occurs and the magnitude of the noise becomes the limit of the accuracy of detecting the electrical conductivity or the limit of the measurement of the minute change of the electrical conductivity.

  Usually, in such a measurement system, a liquid to be measured is fed using a pump capable of passing water at a constant flow rate or a flow rate control means capable of adjusting the flow rate to a constant flow rate. However, the flow rate of the measured liquid sampled at the time of measurement is usually a few milliliters per minute, and the inner diameter of the pipe through which the measured liquid flows is as small as 1 mmφ or less. It is difficult to keep pressure fluctuations small. In general, in such a measurement system, the liquid to be measured after water quality detection that has passed through the detection means is discharged from the pipe in an open state to the atmosphere or an atmospheric pressure (for example, Patent Document 1, Patent). (Refer to the discharge mechanism of the measurement system shown in Document 2.) That is, at the time of draining the liquid to be measured after the water quality is detected, the pipe end is opened to the atmosphere or to the atmospheric pressure with respect to the drain tank or drain groove.

However, when the liquid is discharged in a state where the atmosphere is completely opened to the atmosphere or atmospheric pressure in this way, the drainage from the drainage pipe end forms droplets of a certain size at the pipe end opening. Then, it is dropped and the same state is repeated again after the dropping. At this time, due to the phenomenon of droplet formation and dripping, minute flow rate and pressure fluctuations occur in the measurement system, resulting in detection noise. Since this detection noise occurs repeatedly and almost continuously, eventually it becomes difficult to detect a minute characteristic value below this noise and a minute change in the characteristic value, which limits the detection accuracy.
Japanese Patent No. 2737920 Japanese Patent Laid-Open No. 5-93717

  Therefore, the object of the present invention is to eliminate the phenomenon of droplet formation and dripping that has occurred at the end of the drainage pipe for measurement, and suppress the fluctuations in flow rate and pressure that have occurred due to this phenomenon, thereby greatly reducing detection noise. It is an object of the present invention to provide a water quality measurement method and apparatus that can be kept small and can greatly improve detection accuracy.

  In order to solve the above-described problems, a water quality measurement method according to the present invention provides a water quality measurement system in which a liquid to be measured is introduced into a water quality detection unit and then discharged through a pipe. The method comprises measuring the water quality of the liquid to be measured in a state of being submerged under the surface of the liquid contained in the container so as to be maintained at a constant height.

  The water quality measurement method according to the present invention is a water quality measurement system in which a liquid to be measured is introduced into a water quality detection means and then discharged through a pipe, and the end of the pipe is kept at a constant level. The method comprises measuring the water quality of the liquid to be measured in a state where it is connected to a position below the liquid level of the container in which the liquid is stored.

  That is, in these methods, the drain pipe is submerged in a container adjusted to a certain liquid level height, or the drain pipe is connected to a container position below the liquid level to discharge the drain. Be sure to discharge into the liquid contained in the container, intentionally eliminate the phenomenon of droplet formation and dripping that has conventionally occurred at the end of the pipe, and stabilize the flow by suppressing the pulsating flow in the pipe be able to. As a result, fluctuations in flow rate and pressure that have occurred due to the phenomenon of droplet formation and dripping can be suppressed, so that detection noise can be suppressed to an extremely low level, and detection accuracy can be greatly improved.

  In order to keep the liquid level at a certain height, for example, by supplying the liquid to the container and constantly overflowing the liquid stored in the container, the liquid level is increased by the surface tension of the stored liquid. While preventing the fluctuation, the liquid level can be maintained at a predetermined constant height stably at all times.

  Furthermore, the water quality measurement method according to the present invention is a water quality measurement system in which a liquid to be measured is introduced into the water quality detection means and then discharged through the pipe. In the water quality measurement system, the end of the pipe is measured from the end. The method comprises measuring the water quality of the liquid to be measured in a state where the liquid is in contact with or close to the object surface that flows down immediately after the liquid is discharged.

  That is, in this method, the liquid to be measured discharged from the end of the pipe is allowed to flow along the object surface without forming a droplet immediately after being discharged, thereby forming and dropping the droplet. This makes it possible to suppress fluctuations in flow rate and pressure that have been caused by this phenomenon, and to suppress detection noise to an extremely small level, thereby greatly improving detection accuracy. The object surface on which the liquid to be measured immediately after discharge is not particularly limited, and a plate surface of a plate, an inner surface of a pipe, or the like can be applied.

  In the water quality measurement method according to the present invention as described above, the water quality detection means is not particularly limited, but the present invention is particularly effective for a system using a water quality detection means that outputs a continuous electric signal as a final output. is there. In other words, noise in the detection signal output as an electrical signal can be suppressed to a very small level, so that the characteristic value to be detected can be kept to a very small absolute value and to a very small change without noise. Measurement with high accuracy. As a typical water quality detection means suitable for application of the present invention, an electrical conductivity detection means can be mentioned.

  The water quality measuring device according to the present invention is a water quality measuring device having a water quality detecting means for detecting the water quality of the sampled liquid to be measured and a discharge mechanism having a pipe for discharging the liquid to be measured after water quality detection. The end of the pipe in the mechanism is submerged under the liquid level of the liquid stored in the container so that the liquid level is maintained at a constant height.

  Further, the water quality measuring device according to the present invention is a water quality measuring device having a water quality detecting means for detecting the water quality of the sampled liquid to be measured and a discharge mechanism having a pipe for discharging the liquid to be measured after the water quality is detected. The end of the pipe in the discharge mechanism is connected to a position below the liquid level of the container in which the liquid is stored so that the liquid level is maintained at a constant height.

  In these water quality measuring devices, it is preferable that liquid supply means for supplying the liquid and always overflowing the liquid stored in the container is attached to the container. By always overflowing, the liquid level can be constantly kept at a predetermined constant height.

  Furthermore, the water quality measuring device according to the present invention is a water quality measuring device having a water quality detecting means for detecting the water quality of the sampled liquid to be measured and a discharge mechanism having a pipe for discharging the liquid to be measured after water quality detection. The end of the pipe in the discharge mechanism is in contact with or close to the object surface that allows the liquid to be measured discharged from the end to flow down immediately after discharge.

  These water quality measuring apparatuses according to the present invention are effective for a system including a water quality detecting means for outputting a continuous electric signal as a final output. As such a water quality detection means, an electrical conductivity detection means can be mentioned, for example.

  According to the water quality measuring method and apparatus according to the present invention, the occurrence of droplet formation and dripping that has occurred at the end of the drainage pipe for measurement is eliminated, and the flow rate and pressure fluctuations that have occurred due to this phenomenon are eliminated. Since the detection noise can be suppressed to an extremely small level, detection of minute characteristic values and detection of minute fluctuations are possible, and detection accuracy can be greatly improved.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
As described above, the present invention is configured to eliminate the occurrence of the droplet formation and dripping phenomenon that has occurred in the end portion of the drainage pipe for measurement. For example, as shown in the schematic configuration of the water quality measuring apparatus according to one embodiment of the present invention in FIG. 1, the water quality detecting means 2 for detecting the water quality of the sample liquid sampled through the sampling pipe 1, and after the water quality detection In the water quality measuring apparatus having the discharge mechanism having the pipe 3 for discharging the liquid to be measured, the end portion of the pipe 3 in the discharge mechanism is placed in the container 5 so that the liquid level 4 is maintained at a constant height. It is submerged under the surface of the contained liquid. The liquid level of the container 5 overflows from the upper part of the container 5, but if the amount of overflow is small, the liquid level 4 rises from the upper end surface of the container due to surface tension at the upper part of the container. Thereafter, when the surface tension reaches the limit, the liquid level fluctuates so that the liquid overflows from the upper part of the container and the liquid level decreases. In order to suppress this fluctuation, the liquid is supplied to the container via the liquid supply line 6 so that the liquid stored in the container 5 is always overflowed, so that the liquid level is increased by the surface tension of the stored liquid. The liquid level is constantly maintained stably at a predetermined constant height while preventing fluctuations.

  FIG. 2 shows a schematic configuration of a water quality measuring apparatus according to another embodiment. In this embodiment, the end portion of the pipe 7 for discharging the liquid to be measured after water quality detection is compared with the mode shown in FIG. The liquid to be measured is connected to a position below the liquid level of the container 5 so that the liquid to be measured after water quality detection is always introduced below the liquid level in the container 5. The other configuration is substantially the same as the configuration shown in FIG.

  Furthermore, in the present invention, the end portion of the pipe for discharging the liquid to be measured after water quality detection is configured to be in contact with or close to the object surface that allows the liquid to be measured discharged from the end portion to flow down immediately after discharge. You can also. For example, as shown in FIG. 3 (A), the plate surface of the plate 11 is used as the object surface, and the end portion of the pipe 12 that discharges the liquid to be measured after water quality detection is contacted or brought close to this, As shown in FIG. 3B, it is possible to employ a configuration in which the inner surface of the pipe 13 is used as the object surface, and the end portion of the pipe 12 that discharges the liquid to be measured after detecting the water quality is brought into contact with or close to the object surface. it can. Even in such a configuration, the liquid immediately after being discharged from the end of the pipe 12 can flow down through the plate surface of the plate 11 and the inner surface of the pipe 13 without forming droplets.

  FIG. 4 shows a conventional structure shown for comparison. As shown in FIG. 4 (A), the liquid discharged from the end of the pipe 21 for discharging the liquid to be measured after water quality detection is first pipe 21. When the droplet 22 is grown at the outlet of the liquid crystal and the droplet 22 grows to some extent, the droplet 22 falls as shown in FIG. Due to the occurrence of the droplet formation and dripping phenomenon, a minute flow rate and pressure fluctuation are generated in the pipe 21 as described above, thereby generating noise and reducing measurement accuracy. In the configuration according to the present invention shown in FIGS. 1 to 3, such a phenomenon of droplet formation and dropping does not occur, so that noise generation is suppressed and measurement accuracy is improved.

Below, this invention is demonstrated based on an Example and a comparative example.
Example 1
In the anion component analyzer by ion chromatography, the end of the pipe after the detector (conductivity meter) was submerged in a plastic container filled with liquid according to the water quality measurement system shown in FIG. At this time, an appropriate amount of liquid was always poured so that the liquid always overflowed from the upper surface of the plastic container, and the liquid level was kept constant. FIG. 5 shows the relationship between the analysis time at the time of measurement and the detected electrical conductivity.

Comparative Example 1
In the anion component analyzer by ion chromatography, the pipe end after the detector (conductivity meter) is left in the atmosphere as shown in FIG. 4, and the liquid discharged from the pipe end forms water droplets. The measurement was performed in a state where the dropping was repeated. FIG. 6 shows the relationship between the analysis time during measurement and the detected electrical conductivity.

  FIG. 7 shows an enlarged trend of the electrical conductivity of FIG. 5 when the measurement initial electrical conductivity of Example 1 is zero, and FIG. 8 shows the case where the measurement initial electrical conductivity of Comparative Example 1 is zero. The expansion trend of the electrical conductivity of FIG. 6 is shown. In FIG. 7, the amount of change in the periodic electrical conductivity is small compared to FIG. 8, and is reduced to about 1/3 or less. The periodic noise of Comparative Example 1 seems to be synchronized with the period of water droplet formation and dripping at the pipe end after the detector. As a result, the noise at the time of measurement is reduced to 1/3 or less of the comparative example 1 by adopting the form as in Example 1 in which the phenomenon of water droplet formation and dripping does not occur at the end of the pipe after the detector. It can be seen that the S / N ratio (signal / noise ratio) in the measurement can be improved, the measurement sensitivity can be improved by 3 times or more, and the measurement accuracy can be greatly improved.

  The water quality measurement method and apparatus according to the present invention can be applied to any measurement system in which, when detecting the water quality characteristics of the liquid to be measured, the liquid to be measured after detection has been formed and dropped from the end of the pipe. In particular, it is suitable for a measurement system in which the final detection output is output as an electric signal picking up noise.

It is a schematic block diagram of the water quality measuring apparatus which concerns on one embodiment of this invention. It is a schematic block diagram of the water quality measuring apparatus which concerns on another embodiment of this invention. It is a schematic block diagram of the water quality measuring apparatus which concerns on another embodiment of this invention. It is explanatory drawing which shows the mode of the droplet formation in the conventional piping terminal part, and a dripping. 3 is a graph showing the results of electrical conductivity measurement in Example 1. 10 is a graph showing the results of electrical conductivity measurement in Comparative Example 1. It is the graph which expanded and showed the measurement result of FIG. It is the graph which expanded and showed the measurement result of FIG. 6 partially.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sampling piping 2 Water quality detection means 3, 7, 12, 21 Piping in discharge mechanism 4 Liquid level 5 Container 6 Liquid supply line 11 Plate 13 Pipe 22 Droplet

Claims (12)

  In a water quality measurement system in which the liquid to be measured is introduced into the water quality detection means and then discharged through the pipe, the liquid contained in the container so that the liquid surface is maintained at a constant height at the end of the pipe. And measuring the water quality of the liquid to be measured in a state of being submerged under the surface of the liquid.   In a water quality measurement system in which the liquid to be measured is introduced into the water quality detection means and then discharged through the pipe, the end of the pipe is placed in a container containing the liquid so that the liquid level is maintained at a constant height. A water quality measurement method comprising measuring the water quality of the liquid to be measured in a state of being connected to a position below the liquid surface.   In the water quality measurement system in which the liquid to be measured is introduced into the water quality detection means and then discharged through the pipe, the end of the pipe contacts the object surface that causes the liquid to be measured discharged from the end to flow down immediately after discharge. Alternatively, a water quality measuring method, wherein the water quality of the liquid to be measured is measured in a state of being close to each other.   The water quality measuring method according to claim 1 or 2, wherein the liquid level is maintained at a constant height by supplying a liquid to the container and constantly overflowing the liquid contained in the container.   The water quality measuring method according to any one of claims 1 to 4, wherein the water quality detecting means outputs a continuous electric signal as a final output.   The water quality measurement method according to claim 1, wherein the water quality detection means comprises electrical conductivity detection means.   In a water quality measuring device having a water quality detection means for detecting the quality of the sampled liquid to be measured and a discharge mechanism having a pipe for discharging the liquid to be measured after water quality detection, the end of the pipe in the discharge mechanism is a liquid A water quality measuring apparatus, wherein the surface is submerged under the surface of the liquid contained in the container so that the surface is maintained at a constant height.   In a water quality measuring device having a water quality detection means for detecting the quality of the sampled liquid to be measured and a discharge mechanism having a pipe for discharging the liquid to be measured after water quality detection, the end of the pipe in the discharge mechanism is a liquid A water quality measuring device, wherein the water quality measuring device is connected to a position below the liquid surface of a container in which the liquid is stored so that the surface is maintained at a constant height.   In the water quality measuring device having a water quality detecting means for detecting the water quality of the sampled liquid to be measured and a discharge mechanism having a pipe for discharging the liquid to be measured after the water quality is detected, the end of the pipe in the discharge mechanism is An apparatus for measuring water quality, characterized in that it is in contact with or close to an object surface that allows the liquid to be measured discharged from the end portion to flow down immediately after discharge.   The water quality measuring device according to claim 7 or 8, further comprising a liquid supply means for supplying the liquid to the container and constantly overflowing the liquid stored in the container.   The water quality measuring device according to any one of claims 7 to 10, wherein the water quality detecting means is configured to output a continuous electric signal as a final output.   The water quality measuring device according to any one of claims 7 to 11, wherein the water quality detecting means comprises electric conductivity detecting means.

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