JPH01244341A - Light absorbing type ozone concentration measuring device - Google Patents

Abstract

PURPOSE:To measure the concentration of ozone in a sample highly accurately, by subtracting the output of a second photodetector for detecting the concentration of interfering substance from the output of a first photodetector for detecting the concentration of ozone+interfering substance. CONSTITUTION:An ozonolysis device 3 removes interfering substance other than ozone in a sample which is supplied through a sample introducing port 2. A three-way solenoid valve 4 switches the sample through the ozonolysis device 3 and the sample that does not pass through the device and supplies the sample into a light absorbing cell 5. A first photodetector 10 detects the light, whose wavelength is 253.7nm among the light rays from a low voltage mercury lamp 1. A second photodetector 9 detects the light of 184.9nm in wavelength. A computing means 13 receives the output signals from said photodetectors 9 and 10 when said sample is made to pass the ozonolysis device 3 and when the sample is not made to pass. Then, the concentration of the interfering substance is subtracted from the concentration of ozone+interfering substance, and the concentration of the ozone is computed by Lambert Beer's law.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention is applicable to ozone for deodorizing and decolorizing water, sewage, and human waste treatment plants, sterilization in the medical and food industries, and oxidation treatment and wastewater treatment in chemical factories. The present invention relates to a light absorption type ozone concentration measuring device that automatically, accurately and continuously measures the ozone concentration in the gas phase and liquid phase when carrying out such operations.

(Prior Art) FIG. 3 shows the configuration of a conventional optical absorption type ozone concentration measuring device.

1 is a low-pressure mercury lamp and the light it emits has a wavelength of 184.9
mm, 253.7mm, 435.80m, 546
．． This is a 1 mm emission line spectrum.

20 is a filter that filters 253 of the above bright line spectra.
．． Only 7mm light is allowed to pass through. 8' is a spectroscopic mirror 2
Half of the 53.7mm light is transmitted and half of it is reflected. Reference numeral 5 denotes a light absorption cell through which a fluid sample passes, and which is arranged so that light from a spectroscopic mirror 8' passes through an optical window 6, the sample, and an optical window 7.

10 and 10' are photodetectors that detect light with a wavelength of 253.7 mm and convert it into a current signal.

2 is a sample inlet; 3 is an ozone decomposer that decomposes ozone in the sample to produce a sample containing no ozone; and 4
is a three-way solenoid valve that selects whether the sample sent to the light absorption cell is a sample that has passed through the ozone decomposer 3 or a sample that has not passed through the ozone decomposer 3.

17 is a suction pump for suctioning and passing the sample through the light absorption cell 5; 16 is a needle valve for adjusting the flow rate; and 15 is a flow meter. 11.11' is photodetector 10 and photodetector 10
12.12' is a current-voltage conversion amplifier that converts the current signal into a voltage signal and amplifies it to the required level; 12.12' is a current-voltage conversion amplifier 11 and an A/D converter that converts the analog signal output of 11' into a digital signal. It is a vessel. 13 is a microcomputer that calculates the ozone concentration based on the Beer-Lambert law from the data from the photodetector 10, and 14 is a display for the calculated concentration.

This ozone concentration measuring device focuses on the fact that ozone has the property of absorbing light with a wavelength of 200 nm to 300 nm, with a wavelength of 254 nm at its center, and uses wavelengths of 253. The ozone concentration is measured using 7mm light.

The concentration measurement operation will be explained below. First, ozone decomposer 3
The sample from which ozone has been removed is passed through the light absorption cell 5. The light from the low-pressure mercury lamp 1 is filtered through a filter 20 at 253.
Only 7nn+ passes through, and is divided into two by the spectroscopic mirror 8': one that passes straight through and the other that is reflected. The straight light passes through the optical window 6, passes through the sample in the light absorption cell 5, passes through the optical window 7, and reaches the photodetector 10. The photodetector 10 outputs a current signal whose intensity corresponds to the intensity of light.

The light reflected by the spectroscopic mirror 8' is detected by a photodetector 10'. This detection data is used to correct variations in the light intensity of the low-pressure mercury lamp 1 between when the sample is supplied through the ozone decomposer 3 and when it is supplied without passing through the ozone decomposer 3.

Now, the output value of the photodetector 10 when the sample is passed through the ozone decomposer 3, that is, when it is passed through the light absorption cell 5 without containing ozone, is I. Similarly, the output value of the photodetector 10' is I'o, and then the sample is passed through the light absorption cell 5 without passing through the ozone decomposer 3, that is, in a state containing ozone. It is assumed that the output value is IX and the output value of the photodetector 10' is I'8. Due to fluctuations in the light intensity of the low-pressure mercury lamp 1, the output value of the photodetector 10' changes from T'o to ■
'8, the output value of the photodetector 10 when not passing through the ozone decomposer 3. When converted before fluctuation, it becomes I8・ENGL■'8.

Applying the Beer-Lambert law to this, the ozone concentration C is determined by = log decay I:, ------1) α niosine absorption coefficient t: length of the light absorption cell.

Therefore, the current outputs of the photodetectors 10 and 10' are converted into voltage signals of the required level by current-voltage conversion amplifiers 11 and 11', respectively, and then converted into digital signals by A/D converters 12 and 12'. Then, the ozone concentration is calculated by inputting it into the microcomputer 13 and calculating the formula (1), and the temperature is displayed on the display 14.

(Problems to be Solved by the Invention) However, the conventional ozone concentration measuring device described above has the following problems.

It is not only ozone that absorbs the light with a wavelength of 253.7 nm used in the above concentration measuring device, but also chlorine, sulfur dioxide,
Nitrogen dioxide, dust particles, organic suspended matter, etc. (collectively referred to as interfering substances) also absorb 253.7 nm light. In addition, when these interfering substances pass through the ozone decomposer 3, decomposition, adsorption, filtration, etc. are performed depending on each substance, and as a result, a sample free of these interfering substances is sent out. Therefore, the same processing and action as for ozone in the sample is performed, and the concentration value calculated by the microcomputer 13 is not only the concentration of ozone but also the concentration of interfering substances, so it can be used as an ozone concentration measuring device. has the problem of low measurement accuracy.

In view of the problems of the prior art described above, an object of the present invention is to
In addition to light, there are 184.9no light, 435.8nIII light, and 546no light that are not absorbed by ozone but are absorbed by interfering substances.
．． Simultaneously determine the concentration of interfering substances using 1om light, and
An object of the present invention is to provide an ozone concentration measuring device that can accurately determine ozone concentration by subtracting the concentration of interfering substances from the concentration determined using 53.7 nm light.

(Means for Solving the Problems) The present invention has the following means configuration to achieve the above object.

That is, the optical absorption type ozone concentration measuring device of the present invention detects ozone, chlorine, sulfur dioxide, nitrogen dioxide, and
An ozone decomposer that decomposes, adsorbs, or filters substances such as organic suspended matter and dust particles (other than ozone is collectively referred to as interfering substances) and sends out a fluid sample that does not contain these substances; and low-pressure mercury. A lamp; A light absorption cell that receives, absorbs, and transmits light emitted from a low-pressure mercury lamp into the sample while passing the fluid sample through the sample.
means for switching between a fluid sample that has passed through the ozone decomposer and a fluid sample that has not passed through the ozone decomposer and supplying the same to the light absorption cell; and a first light that detects light having a wavelength of 253.7 nm among the transmitted light from the light absorption cell; a detector; a second photodetector that detects light having a wavelength of 184.9 nm among the transmitted light from the light absorption cell; a fluid sample from the first photodetector and the second photodetector; A calculation that calculates the ozone concentration by subtracting the concentration of the interfering substance from the concentration of the ozonator interfering substance using the Beer-Lambert law based on the output signal when the ozone decomposer is passed and the output signal when the ozone decomposer is not passed. It is characterized by comprising means and; Another configuration is that in the above optical absorption type ozone concentration measuring device, instead of the second photodetector that detects light with a wavelength of 184.9 nm, the second photodetector detects light with a wavelength of 435.8 nm and the second photodetector with a wavelength of 546.1 nm.
This is a light absorption type ozone concentration measuring device equipped with a second photodetector that detects light of i.

(Function) Hereinafter, the function of the light absorption type ozone concentration measuring device of the present invention having the above-mentioned configuration will be explained.

Now, in addition to ozone, the sample fluid contains chlorine, sulfur dioxide,
It is assumed that interfering substances such as nitrogen oxide are mixed in. These interfering substances absorb 253.7n light like ozone, and 184.9am light, which is not absorbed by ozone.
It also absorbs light.

That is, 184.9 nm light is absorbed only by interfering substances.

Therefore, by using 184.9 nm light, the concentration of only interfering substances can be determined.

By using 253.7 nm, the concentration of (ozone + interfering substances) is known, and by subtracting the concentration of only interfering substances from this concentration, the accurate ozone concentration can be determined.

In the measuring device of the present invention, light emitted from a low-pressure mercury lamp is applied to a light absorption cell without passing through a filter. Therefore, 184.9 nm light, 253.7 nm light, 435.8+Il+ light, and 546.1 nm light of the bright line spectrum are all applied to the light absorption cell.

On the other hand, the first photodetector that detects the light transmitted through the light absorption cell detects only 253.7 nm light, and the second photodetector detects only 253.7 nm light.
Detects only 84.9 nm light. Therefore, the output value of the first photodetector when the sample fluid is passed through the ozone decomposer, that is, when it does not contain ozone or interfering substances and does not pass through the light absorption cell, is 1°, and the output value of the second photodetector is 1°. The output value of the device is I′O
If the output value of the first photodetector is ■8 and the output value of the second photodetector is I'8 when the sample fluid is passed through the light absorption cell without passing through the ozonolyzer, then The concentration C1 of (ozone + interfering substances) is α according to the Beer-Lambert law.
: Absorption coefficient t: Length of light absorption cell.

Also, the concentration C2 of only the interfering substance is c2=log decay −・・−・・−−m−−・
-・(3). Since the ratio of I'o and E'8 is very close to 1, α is set to be the same as in equation (2). Therefore, the ozone concentration C is as follows: C=C, -C2 = log + L log = old log - (4).

The calculation means calculates the ozone concentration by calculating the equation (4).

In addition, IO1 engineering'. 1 from the time of detection. , ■ Even if there is a change in the amount of light emitted from the low-pressure mercury lamp until the detection of 8, I' and /IX in equation (4) do not change, so the change in the amount of light does not affect the concentration measurement.

The above explanation deals with the case where interfering substances that absorb 253.7nm light and 184.9nm light coexist. If it is thought that an interfering substance that absorbs 546.1 nm light is contained, ozone concentration can be measured in the same way by simply replacing the second photodetector with one that detects 435.8 nm light and 546.1 nm light. .

Therefore, the second photodetector is a photodetector for detecting 184.9nm light and a photodetector for detecting 435.8nm light and 546.1++m light.
Two types of photodetectors for photodetection may be provided and used appropriately depending on the target sample.

(Example) Hereinafter, an example of the optical absorption type ozone concentration measuring device of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a measuring instrument according to an embodiment of the present invention.

Components with the same numbers as those in FIG. 3 have the same names and the same functions, so their explanations will be omitted.

The difference from Fig. 3 is the low-pressure mercury lamp 1 and the light absorption cell 5.
The filter 20, the spectroscopic mirror 8', and the photodetector 10' placed between them are removed, while the spectroscopic mirror 8 is provided between the light absorption cell 5 and the photodetector 10, and the spectroscopic mirror 8 is installed between the light absorption cell 5 and the photodetector 10 to detect the spectroscopic light. A detector 9 is provided.

Low pressure mercury lamp 1 gives 184.9no+ light, 253.
The light absorption cell 5 is irradiated with all of the 7 nm light, 435.8 nm light, and 546.1 nm light. The photodetector 10 is a first photodetector and detects 253.7 nm light among the transmitted light. Photodetector 9 is a second photodetector and has a wavelength of 184.9 nm.
Detects light or 435.80m light and 546.1nm light. This light selection can be done by giving the spectroscopic mirror 8 an interpretation that allows the 253.7 nm light to pass through and reflects other light, or by using the spectroscopic mirror 8 as a simple half mirror such as quartz glass. The photodetectors 10 and 9 may be wavelength-selective. For example, R1384 manufactured by Hamamatsu Photonics (detection wavelength range 185 nm to 320 nm) is used for detecting 253.7 nm light, and for detecting 184.9 nm light. The company's R1187 (detection wavelength range 115
nm to 200nn+), and the company's R414 (
The detection wavelength range is 300 n+++ to 650 or@), etc.

Figure 2 shows a photodetector for detecting 184.9nm light, a photodetector for detecting 435.8nm light, and a 546.1r+m photodetector as a second photodetector.
This is an example in which two photodetectors for photodetection are provided, and a spectroscopic mirror 18 and a photodetector 19 are added to those in FIG. Then, the method is switched and used as appropriate depending on the interfering substances contained in the measurement target.

(Effects of the Invention) As explained above, the light absorption type ozone concentration measuring device of the present invention has a bright line spectrum light emitted from a low pressure mercury lamp.
We focused on the fact that in addition to the 253.7 nm light that is absorbed by ozone and interfering substances, there is also bright line spectrum light that is absorbed only by interfering substances, and by using this bright line spectrum light, we are able to achieve a scale that is no larger than that of conventional measuring instruments. Without increasing the size or complicating the configuration, the concentration of interfering substances can be measured in parallel with measurement using 253.7 nm light (ozone + interfering substances).
Since the ozone concentration is calculated by subtracting the ozone concentration from the concentration of There are advantages.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a first embodiment of a light absorption type ozone concentration meter of the present invention, Fig. 2 is a block diagram of a second embodiment of the present invention, and Fig. 3 is a block diagram of a conventional light absorption type ozone concentration meter. FIG. 2 is a configuration diagram of a concentration measuring device. 1...Low pressure mercury lamp, 2...Sample inlet, 3...Ozone decomposer, 4...
・3-way solenoid valve, 5...Light absorption cell, 6,7・
...Optical window, 8.8'... Spectroscopic mirror,
9,10.10'...Photodetector, 13.
...Microcomputer, 14...Display, 15...Flowmeter, 16...
Needle pulp, 17...Suction pump, 18
... Spectroscopic mirror, 19 ... Photodetector, 20 ... Filter. Agent: Patent Attorney Hiroshi Hachiman / Diagram 2 Diagram /,? ”-----A/D Chiang Jiang/Goo--Ichisukeyu Mirror

Claims (2)

[Claims] (1) Decompose, adsorb, or filter substances such as ozone, chlorine, sulfur dioxide, nitrogen dioxide, organic suspended matter, and dust particles (other than ozone are collectively referred to as interfering substances) in the inflowing fluid sample. an ozone decomposer that sends out a fluid sample that does not contain these substances; a low-pressure mercury lamp; and a light absorption cell that receives, absorbs, and transmits light emitted by the low-pressure mercury lamp into the sample while passing the fluid sample. ; a means for switching between a fluid sample that has passed through the ozone decomposer and a fluid sample that has not passed through the ozone decomposer and supplying the same to the light absorption cell;
a first photodetector that detects light with a wavelength of 184.9 nm; a second photodetector that detects light with a wavelength of 184.9 nm among the transmitted light from the light absorption cell;
a Lambert-Beer photodetector; receiving output signals when the fluid sample is passed through the ozonolyzer and output signals when the fluid sample is not passed from the first photodetector and the second photodetector; a calculation means for calculating the ozone concentration by subtracting the concentration of the interfering substance from the concentration of (ozone + interfering substance) according to a law;
A light absorption type ozone concentration measuring device characterized by comprising: (2) In the light absorption type ozone concentration measuring device according to claim (1), the second photodetector detects light with a wavelength of 184.9 nm and the second photodetector detects light with a wavelength of 435.8 nm and wavelength of 546.9 nm. A light absorption type ozone concentration measuring device equipped with a second photodetector that detects 1 nm light.