JPH11118698A - Separation-type turbidity meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a separation-type turbidity meter by which a turbidity value can be measured stably even when a detection part and a conversion part are installed so as to be separated by a method wherein communication means are installed at the detection part and the conversion part and a detection signal is communicated between both. SOLUTION: A laser unit 16 and a light receiving unit 17 inside a detector 13 are operated respectively when a power supply is supplied from a converter 22. A pulse signal which is detected by the light receiving unit 17 is signal- processed by a communication driver 50 so as to be transmitted, via a communication line 52, to a communication receiver 51 which is provided inside the converter 22. In addition, the converter 22 performs a prescribed computing operation to the detection signal, it finds the turbidity value of a fluid, to be measured, so as to be displayed, and it outputs an output signal 23 corresponding to a display value. In addition, the converter 22 receives the supply of a power supply 24 from the outside. In this manner, the pulse signal as the detection signal from a detection part can be transmitted at a long distance. As a result, even when the detection part and the conversion part are installed so as to be separated, the turbidity value can be measured stably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water quality meter used in a water purification plant or the like, and more particularly to a high-sensitivity turbidity meter for counting fine particles in water and measuring turbidity. This is in consideration of expanding the scope and the scope of application.

[0002]

2. Description of the Related Art A water quality meter used in a water purification plant or the like includes a turbidity meter for measuring and controlling the degree of turbidity of water.
The turbidity of water supply in conventional water treatment plants is 2 degrees (pp
m.

[0003] However, the demand for safety of tap water is increasing year by year, and it is no longer possible to cope with the conventional management level. In particular, the problem of the toxicity of microorganisms contained in tap water is serious. In 1996, a water-supply plant was established as a provisional guideline of the Ministry of Health and Welfare in response to the outbreak of a multi-micron protozoan called cryptosporidium in Japan. Was required to maintain the turbidity of the filtered water below 0.1 degrees.

As described above, the turbidity management standard is 1 /
Since the sensitivity was insufficient with the conventional turbidimeter due to the reduction to 20, the development of a high-sensitivity turbidimeter based on a new principle has been demanded.

What has appeared here is a high-sensitivity turbidity meter of a particle counter type used for turbidity measurement of ultrapure water or the like. The measurement principle of this turbidity meter employs a method of counting the number of fine particles in a predetermined fluid and converting it into turbidity. Laser light is used as a light source for the detection of particles, and when this is irradiated on a fluid to be measured at a constant flow rate flowing in the measurement cell, the laser light collides with fine particles in the fluid and is scattered. Interference light with light is detected by an optical sensor, and a change in the detected light amount can be detected as a pulse signal. By counting the pulse signal for a predetermined unit time, the number of particles passing through the measurement cell is counted and further converted to turbidity.

Here, in the case of the turbidity range generally used, the above-mentioned pulse signal changes in the range of several Hz to several kHz in proportion to the number of passing particles.

[0007]

According to the above prior art, scattered light scattered by laser light hitting fine particles in a fluid or interference light between scattered light and irradiation light is detected by an optical sensor.
A detection unit that captures the change in the detected light amount as a pulse signal is connected to a conversion unit that counts the number of particles passing through the measurement cell by counting the pulse signal for a predetermined unit time and further converts the number of particles into turbidity. Since the transmission path cannot have a sufficient transmission path length due to the problems of pulse signal attenuation and noise effects, it is necessary to install the detection unit and the conversion unit close to each other.

For this reason, elements that must be installed at the measurement site have become large, and there has been a problem in terms of installation space. In addition, the main elements that make up the conversion unit are mainly electronics such as arithmetic circuits, and such a conversion unit must be installed at the measurement site that handles water, so it is waterproof to maintain reliability. Sufficient attention such as processing was required.

It is an object of the present invention to provide a high-sensitivity turbidity meter of a fine particle counter type which can eliminate the above-mentioned drawbacks and can stably measure turbidity even when a detecting unit and a converting unit are separately installed. .

[0010]

According to the present invention, a fluid is sampled, the number of particles contained in the fluid is measured, and the number of particles of the sampled fluid is detected in a turbidimeter for measuring fluid turbidity. Communication means is provided in each of the detection unit and the conversion unit that converts the detection signal from the detection unit into turbidity.

[0011] Further, the detection signal is communicated between the detection unit and the conversion unit by the communication unit provided in the detection unit and the communication unit provided in the conversion unit, and the detection unit and the conversion unit can be installed separately. is there.

In addition, a plurality of detection units and a single conversion unit are connected to a bus-like or star-like communication path so that detection signals of a plurality of dispersed turbidity measurement points are processed by a single conversion unit. It was done.

[0013] Further, the communication means provided in the detection section and the conversion section is a balanced transmission comprising a differential line driver / receiver.

[0014] Further, the detection section has a structure capable of being mounted on a wall and a stanchion.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. First, FIG. 1 is a configuration diagram of a main part of the present invention.

A fluid 2 to be measured supplied from a sample water inlet 1
Is led to the lower part of the defoaming tank 7 through a pipe 3, a pressure reducing valve 4, a regulating valve 5, and a pipe 6. The defoaming tank 7 is composed of a short inner cylinder 8 and a long outer cylinder 9. The outer cylinder 9 further has an overflow port 11 for maintaining the height of the water surface 10 of the fluid to be measured at an upper portion of its outer peripheral surface. Further, at the lower part of the outer peripheral surface, an outlet 14 for sending out the fluid to be measured 2 to the detector 13 through the pipe 12
Are provided respectively.

The detector 13 incorporates a transparent and cylindrical measuring cell 15 for guiding the fluid 2 to be measured and measuring its turbidity, and an optical lens system for irradiating the measuring cell 15 with a laser beam. A laser unit 16 and a light receiving unit 17 for receiving the laser light passing through the measuring cell 15 are arranged.

The fluid 2 to be measured having passed through the measuring cell 15 is discharged from a discharge port 19 through a pipe 18 under atmospheric pressure. The fluid 2 to be measured overflowing from the discharge port 19 and the overflow port 11 is drained out of the apparatus via a pipe 20 and a discharge port 21.

On the other hand, the laser unit 16 and the light receiving unit 17 in the detector 13 are operated by power supply from the converter 22, respectively. The pulse signal detected by the light receiving unit 17 is processed by the communication driver 50,
The signal is transmitted via a communication path 52 to a communication receiver 51 provided in the converter 22. Further, the converter 22 performs a predetermined operation on the detection signal to obtain a turbidity value of the fluid to be measured, displays the turbidity value, and outputs an output signal 23 corresponding to the displayed value. The converter 22 receives a power supply 24 from outside.

On the other hand, a lid 25 is fitted on the upper end of the defoaming tank 7, and a temperature sensor 26 such as a thermocouple or a resistance temperature detector is held on the lid. It is inserted into the fluid 2 and transmits the temperature of the fluid 2 to be measured to the converter.

In this configuration, the fluid 2 to be measured guided to the inner cylinder 8 of the defoaming tank 7 has a temperature
Many bubbles are contained due to a change in pressure and the like, and the bubbles rise in the inner cylinder 8 while growing and are diffused into the atmosphere from a water surface 10 that is open to the atmosphere. A fluid to be measured having few air bubbles is collected between the inner cylinder 8 and the outer cylinder 9 and sent out from the outlet 14 to the detector 13, so that measurement with less influence of the air bubbles can be performed. At this time, the fluid 2 to be measured flowing in the measurement cell 15
Is determined by the head difference ΔH between the water surface 10 and the discharge port 19 and the pipe resistance.

Next, the principle of measurement in the detector 13 will be described with reference to FIG.

The laser unit 16 shown in FIG. 1 is composed of a semiconductor laser 31 as a light source and a condenser lens 32, and a laser beam 33 generated in a measuring cell 15 made of quartz glass or the like in which the fluid 2 to be measured flows in the direction of the arrow. It is arranged to focus on. A large number of fine particles 34 are contained in the fluid 2 to be measured and flow at a constant flow rate in the direction of the arrow. When the fine particles 34 are irradiated with the laser light, a scattering phenomenon occurs and scattered light 35 is generated. The laser light 33 (transmitted light) and the scattered light 34 generate interference fringes behind the measurement cell 15.
The interference fringes (shading of transmitted light) are detected by the light receiving unit 17 including a plurality of light receiving elements, and differentially amplified by the amplifier 36.

The output waveform 37 is shown in FIG. Each time the fine particles 34 shown in FIG. 2 pass one by one, a peak waveform 41 is output. The number of times that the peak waveform 41 exceeds a predetermined threshold value 42 is counted, and the number of the passing fine particles 34 is measured. Here, in the case of a commonly used turbidity range, the pulse signal has a number H in proportion to the number of passing particles.
It changes in the range of z to several kHz.

FIG. 4 shows that the detection signal is transmitted from the detector 13 to the converter 2.
FIG. 2 is a diagram illustrating an example of a connection form of a communication path for transmitting data to a communication path 2; In FIG. 4, 1 to n detectors 13 and one converter 22 are connected by a bus-shaped communication path 52. The communication driver 50 provided in each detector is constituted by, for example, a differential line driver typified by RS-485, and drives the lines a and b of the communication path 52 in a differential balance with respect to the GND line. The communication receiver 51 provided in the converter 22 is similarly constituted by a differential line receiver represented by RS-485, and restores a detection signal transmitted by a differential input.

In such balanced transmission, it is known that a transmission distance of about 1 km can be obtained at a signal frequency of several kHz. In addition, since a noise voltage is applied to the a-line and the b-line in the same phase with respect to the noise applied to the communication path 52, the differential line receiver does not sense the noise voltage and is a method strong against the noise influence. . FIG.
In this example, since a plurality of detectors and one converter are connected by a bus-like communication path, communication collision between the detectors becomes a problem, but a communication time slot is sequentially given to each detector. There is no problem if a means is provided. The same applies to the case where a plurality of detectors and one converter are connected via a star-shaped communication path.

FIG. 5 is a diagram showing an example of a signal waveform in a process until the detection signal 41 is output from the communication receiver 51 of the converter via the communication path 52.

FIG. 6 is a diagram showing an appearance image of this embodiment. Since the detector and converter can be installed separately, only the detector needs to be installed at the measurement site, making it possible to reduce the size.If the stanchion mounting hole and the wall mounting hole are provided as shown in the figure, Both mounting structures can be easily obtained.

[0029]

According to the present invention, since a pulse signal, which is a detection signal from a detection unit, can be transmitted over a long distance, stable turbidity measurement can be performed even if the detection unit and the conversion unit are installed separately. There is an effect that a degree meter can be provided.

Further, it is sufficient to install only a detection unit that can be mounted on a wall at a measurement point where turbidity measurement is required, and there is an effect that installation at a measurement site where space is generally limited becomes easy.

Further, among the elements constituting the turbidity meter, the conversion section containing the main electronics such as an arithmetic circuit can be installed in an instrument room having a better installation environment than the measurement site where water is measured. Therefore, there is an effect that maintenance of reliability is facilitated.

When turbidity measurement at a plurality of points is required, only the detection unit is installed at the required measurement point, and the detection signal from each detection unit can be processed by a single conversion unit. This has the effect of providing a total meter.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of a separation turbidity meter according to an embodiment of the present invention.

FIG. 2 is a view for explaining the principle of FIG. 1;

FIG. 3 is a characteristic diagram illustrating a detection signal according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating signal connection according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a transmission signal according to an embodiment of the present invention.

FIG. 6 is a view showing an appearance image of a separation type turbidimeter which is an example of the present invention.

[Explanation of symbols]

2 ... fluid to be measured, 7 ... degassing tank, 10 ... water surface, 13 ... detector, 15 ... measuring cell, 16 ... laser unit, 17 ... light receiving unit, 19 ... emission port, 22 ... converter, 26 ... temperature sensor .. 50 communication driver, 51 communication receiver, 5
2: Communication channel, ΔH: Head difference.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsutoshi Yamada 882 Momo, Oaza-shi, Hitachinaka-shi, Ibaraki Pref.

Claims (5)

[Claims] 1. A turbidity meter for sampling a fluid, measuring the number of particles contained in the fluid, and measuring the turbidity of the fluid, comprising: a detection unit for detecting the number of particles of the sampled fluid; A separation type turbidimeter, wherein a communication unit is provided in each of the conversion units for converting a detection signal into turbidity. 2. A detecting means according to claim 1, wherein the detecting section and the converting section communicate a detection signal by a communicating section provided in the detecting section and a communicating section provided in the converting section, and the detecting section and the converting section are separately installed. A separation type turbidity meter characterized by being made possible. 3. The method according to claim 1, wherein the plurality of detection units and a single conversion unit are connected to a bus-like or star-like communication path, and the detection signals of the plurality of dispersed turbidity measurement points are converted into a single signal. A separation type turbidimeter characterized by being processed by a conversion unit. 4. A communication system according to claim 1, wherein the communication means provided in the detection section and the conversion section includes a differential line driver /
A separation type turbidimeter characterized by balanced transmission comprising a receiver. 5. A turbidity meter according to claim 1, wherein said detecting portion is structured to be mounted on a wall and a stanchion.