JPH0735996B2 - Method for measuring halogen ion concentration - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the ion concentration of halogen elements contained in water in trace amounts.

[0002]

The cooling water used in the Background of the Invention power plant Cl ^- ions are contained in trace amounts, the Cl ^- ions is preferably suppressed to as low as possible concentration for 1 comprising bract factor corrosion cracking of the piping. Typical conventional methods for measuring such ion concentration include a mercury (II) thiocyanate absorptiometric method, a mercury (II) nitrate titration method, and a silver nitrate titration method.

[0003]

However, in the above-mentioned measuring method, it is generally necessary to carry out absorption analysis and titration analysis after pretreatment such as addition of reagents and heating.
Therefore, a great deal of time and labor are required for analysis and measurement.
In addition, since it is a method that involves a chemical operation such as adding a reagent, it is difficult to perform on-line measurement, and in particular at a nuclear power plant or the like, handling cooling water directly causes radiation exposure to some extent.

The present invention has been made in view of the current state of the art of measuring the conventional halogen ion concentration, and its purpose is to generate an anion of a halogen atom, a hydrated electron or a halogen molecule by a laser beam, and to this. To provide a measurement method that can measure the light absorption of each light and measure the concentration of halogen ions in a non-contact manner in a short time with sufficient accuracy without the need for pretreatment and enable online measurement. is there.

[0005]

In order to solve the above problems, the present invention irradiates a halogen ion in water with a predetermined short wavelength laser beam, and the product produced by the irradiation of this laser beam is provided with another light source. The halogen ion concentration was measured by irradiating and measuring the absorbance of each of the above products from the transmitted light, and determining the halogen ion concentration from the previously determined relationship between the absorbance and the halogen ion concentration.

In the above-mentioned solution means, the laser light is irradiated by the excimer laser to the water guided to the measured portion of the pipe, and the water containing the generated product is irradiated with the light having the absorption wavelength. Light in the vicinity of the peak wavelength of the absorption band of the product may be extracted from the transmitted light through a spectroscope, and the light may be received by a light receiver to measure the absorbance from the received light intensity.

In any of the above-mentioned concentration measuring methods, the product may be a halogen atom or a hydrated electron produced from a halogen ion.

Alternatively, the product may be an anion of a halogen molecule produced from a halogen ion.

[0009]

The measuring principle of the concentration measuring method according to the present invention is as follows. When a halogen ion X ⁻ in water is irradiated with a laser beam having a specific short wavelength, a halogen atom and a hydrated electron, and then an anion X ₂ ^{− of a} halogen molecule are first generated by the following two-step reaction. Incidentally, the halogen ion X ^-
Excludes F ⁻ (fluorine ion). X ⁻ → X + e ⁻ X + X ⁻ → X ₂ ^{− In the} above two-step reaction, the reaction time of the first step is generally faster, and the latter is slower. For example, when the halogen ion is Cl ⁻ ion, after the start of the reaction, the reaction appears remarkably at a time of about 50 ns (nanosecond) and the latter at a time of about 500 ns. When a halogen atom, a hydrated electron or an anion X ₂ ^{− of a} halogen molecule is generated, the product at each stage is irradiated with light from another light source and the absorbance of the product is measured from the transmitted light. In this case, the other light source may emit a specific light in the vicinity of the absorption band peak wavelength of the product, or may emit white light such as an Xe (xenon) lamp containing various wavelengths. It may be one. Since the absorption band of the above product is different from that of the halogen ion X ⁻ and the change can be easily discriminated and accurately measured, the indirect measurement method using this light absorption band was adopted.

When the absorbance of a halogen atom, a hydrated electron, or the anion of a halogen molecule is measured, the halogen is determined from the relationship between the halogen ion concentration and the absorbance of the halogen atom, a hydrated electron, or the anion of the halogen molecule measured in advance. The ion concentration is determined. In this case, it has been confirmed by experiments that the halogen ion concentration and the absorbance of the halogen atom, the hydrated electron, or the anion of the halogen molecule have a proportional relationship within a certain range.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of an apparatus for measuring the Cl ⁻ ion concentration of water in piping. The pipe 1 is provided with a bypass pipe 2 for guiding water to be measured, and windows 3 for transmitting light are provided at both ends of the bypass pipe 2. The water guided to the bypass pipe 2 is irradiated with laser light. An excimer laser 4 that generates this laser light is installed, and the generated laser light is irradiated onto water through the window 3 through the reflection mirror 5 and the diaphragm 6. The window 3 can be made of a material such as synthetic quartz.

The excimer laser 4 is a high-power laser that produces ArF laser light (wavelength 193 nm). A light intensity measuring device (joule meter) 7 is provided to calibrate the output of the laser, and the output is measured via a mirror provided in the path of the laser light. A Xe lamp 8 is provided on the optical path passing through the reflection mirror 5. The white light of the Xe lamp 8 is irradiated at the moment when the trace amount of Cl ⁻ ions in the water changes to Cl atoms and hydrated electrons or the anion Cl ₂ ⁻ of Cl molecule by the irradiation of the laser beam. A specific wavelength (in this embodiment, Cl atom is 320 nm, hydrated electron is 720 nm,
Spectrometer 9 for extracting only Cl ₂ ⁻ ions (340 nm)
Is provided close to the window 3 on the opposite side to the above, and a photomultiplier tube 10 for receiving the extracted light is further provided. The photomultiplier tube 10 detects weak light using a photoelectric effect and outputs a signal. This signal is sent to the oscilloscope 1
Observe at 1 and measure the light intensity.

[0013] water Cl by configured measuring device as described above ^- the ion concentration measured as follows. When ArF laser light is emitted from the excimer laser 4 to the water in the bypass tube 2, Cl ⁻ ions in the water change as follows. ^{Cl - → Cl + e - Cl} + Cl - → Cl 2 - As shown in FIG. 2, Cl ^- from the optical absorption spectrum of ions, Cl ^- ions Cl atoms above with absorbing light of a wavelength of position 190~200nm and water WA electrons generate Cl ₂ ⁻ ions in the next step, and wavelength 193 is generated in this wavelength band.
A nm ArF laser beam is suitable.

[0014] Cl atoms and hydrated electrons or Cl _2, ^- the ion occurs, white light Xe lamp 8 is illuminated in each production stage (Cl atom, hydrated electrons or C,
l ₂ ^- may have been irradiated before the ions occurs).
This white light may include various wavelength components, Cl atom has a light absorption band with a peak wavelength component of 320 nm, hydrated electrons 720 nm, Cl ₂ ^- ions 340n
It has an absorption peak at m. In Fig. 3, Cl atom, hydrated electron,
And Cl ₂ ^- The spectrum of the absorption band of the ion, Cl ₂ in FIG. 4 ^- shows a partial enlarged view of the absorption band spectrum of ions. The light having the peak wavelength of the absorption band spectrum is analyzed by the spectroscope 9
Is used to detect the intensity, and the oscilloscope 11 measures the respective intensities. And
By measuring the received light intensity ratio of the light of the peak wavelength emitted from the Xe lamp 8 before and after Cl atoms, hydrated electrons, or Cl ₂ ⁻ ions are generated, Cl atoms, hydrated electrons, or Cl ₂ ^- absorbance of the ion can be seen.

As an example, FIG. 5 shows the time change of absorption by Cl atoms and Cl ₂ ⁻ ions. It can be seen that when Cl atoms or Cl ₂ ⁻ ions are generated, the received light intensity is reduced for a very short time. Thus, the lifetime of Cl ₂ ⁻ ions is extremely short, the lifetime of Cl atoms and hydrated electrons is even shorter, and the light absorption band of Cl atoms, hydrated electrons, or Cl ₂ ⁻ ions is mixed with Cl ⁻ ions and other ions. Since it is different from the absorption bands of various ions, it is easy to identify the change. This is C
This is the reason why the concentration of Cl ⁻ ion is not directly measured from the absorbance of l ⁻ ion, but the concentration of Cl ⁻ ion is indirectly measured from Cl atom, hydrated electron or Cl ₂ ⁻ ion.

Then, the absorbance at each of the above peak wavelengths and the concentration of Cl ⁻ ions are in a certain range as shown in FIGS. 6 to 8 (for example, 1 to 70 ppm in the case of Cl ₂ ⁻ ions).
And there is a proportional relationship. Therefore, when the absorbance at each peak wavelength is measured, the concentration of Cl ⁻ ions can be known. In this example, a concentration of about 1 ppm is measured. In the above embodiment Cl ^- it has been described a method of measuring the ion concentration measuring method according to the present invention halogen ion I ^- (iodide ion), Br - can be similarly applied to ^(bromide ions) (F ^- Fluorine Excluding ions).

The absorption peak wavelength (nm) of each ion etc. is as follows. ^{Cl - 174 Br - 175,186,198 I -} 171,183,196,228 Cl atoms 320 Br atom 275 I atom _{^{260 Cl 2 - 340 Br 2 -}} 364 I 2 - 380 also, Cl atoms in the above embodiment, water sum electronic, or Cl ₂ ^-
Although it is stated that the absorbance of each product is measured at the absorption peak wavelength of the ion, the measurement of the absorbance is not limited to the absorption peak wavelength and can be measured within a certain range around that wavelength. The measurable wavelength range (nm) of each product is shown below.

[0018] Cl atoms 300 to 340 Br atom two hundred fifty-five to two hundred ninety-five I atom 240-280 hydrated electron _{^{550~900 Cl 2 - 320~360 Br 2 -}} 344~384 I 2 - 360~400 However, Cl for hydrated electron ^- ions, Br ^- ions, I ^- ions not only when present alone, but hydrated electrons if that might they are mixed are generated from each ion, the ratio of each ion concentration It will occur according to the ratio of.

From these numerical values, it can be seen that the method according to the present invention can be applied to the measurement of Br ⁻ and I ⁻ ion concentrations. In that case, the usable laser wavelength range is as follows. Cl ^- 190-200 (nm) Br ^- 190-220 I ^- 190-260

[0020]

As described above in detail, the present invention irradiates a laser beam having a predetermined wavelength and contains a small amount of Cl ⁻ and B contained in water.
The halogen ions of r ⁻ and I ⁻ (excluding F ⁻ ) are converted into halogen atoms and hydrated electrons or anions of halogen molecules, and this is irradiated with another light source to generate halogen atoms, hydrated electrons, or halogens. Since the halogen ion concentration was measured by measuring the absorbance in the vicinity of the absorption band peak wavelength of the anion of the molecule, addition of reagents as in the conventional measurement method, complicated pretreatment such as heating is unnecessary, It is possible to obtain various effects such as non-contact measurement of a very small amount of concentration in a short time with sufficient accuracy and online measurement.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a Cl ⁻ ion concentration measuring device according to an embodiment.

FIG. 2 Absorption spectrum of Cl ⁻ ion

[Figure 3] Cl atoms, hydrated electrons, and Cl ₂ ^- absorption spectrum showing a peak absorption wavelength of the ions

FIG. 4 is a partially enlarged view of the peak absorption wavelength spectrum diagram of Cl ₂ ⁻ ion in FIG.

FIG. 5 is a diagram showing changes over time in transmitted light intensity of Cl atoms and Cl ₂ ⁻ ions.

FIG. 6 is a diagram showing the relationship between the absorbance of Cl atoms and hydrated electrons and the concentration of Cl ⁻ ions.

FIG. 7 is a graph showing the relationship between the absorbance of Cl ₂ ⁻ ions and the concentration of Cl ⁻ ions.

FIG. 8 is a partially enlarged view of the relationship between the absorbance of Cl ₂ ⁻ ions and the concentration of Cl ⁻ ions.

[Explanation of symbols]

 1 Piping 2 Bypass Tube 3 Window 4 Excimer Laser 5 Reflection Mirror 8 Xe Lamp 9 Spectrometer 10 Photomultiplier Tube 11 Oscilloscope

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshinori Kitada 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Chiyoe Yamanaka 1, 8-chome, Tsubuhoncho, Nishi-ku, Osaka City, Osaka Prefecture No. 4 Inside the Laser Technology Research Institute (72) Inventor Yasukazu Izawa 1-8-4 Tsutohoncho, Nishi-ku, Osaka-shi Osaka Prefecture Inside the Laser Technology Research Institute (72) Nobuaki Nakajima Nishi-ku, Osaka City Osaka Incorporated Laser Technology Research Institute, 1-8-4, Tsubomoto Town (72) Inventor, Akihiro Iwata 1-8-4, Intokuhoncho, Nishi-ku, Osaka-shi, Osaka (56) References 58-55839 (JP, A) JP-A-52-15390 (JP, A) JP-A-62-239051 (JP, A)

Claims (4)

[Claims] 1. A halogen ion in water is irradiated with a predetermined short-wavelength laser beam, and a product produced by the irradiation of this laser beam is irradiated with another light source, and the absorbance of each of the above products is measured from the transmitted light. A method for measuring the concentration of halogen ions, which comprises measuring and measuring the concentration of halogen ions from the relationship between the absorbance and the concentration of halogen ions obtained in advance. 2. The laser light generated by an excimer laser and applied to the water to be measured in the pipe is irradiated, and the water containing the generated product is irradiated with light having the absorption wavelength to transmit the light. The light near the absorption band peak wavelength of the product is taken out from the detector through the spectroscope, and the light is received by the photodetector, and the absorbance is measured from the intensity of the received light. Method for measuring halogen ion concentration. 3. The method for measuring a halogen ion concentration according to claim 1, wherein the product is a halogen atom generated from a halogen ion or a hydrated electron. 4. The method for measuring a halogen ion concentration according to claim 1, wherein the product is an anion of a halogen molecule produced from a halogen ion.