JPS6166949A - hydrogen gas detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a hydrogen gas detector that optically measures the amount of hydrogen gas.

(Prior art and its disadvantages) Detection of hydrogen gas is required in various fields, for example, in liquid sodium cooling plants used in fast breeder reactors, when a small amount of water leaks into the sodium vapor generator, Water and sodium react violently, creating an extremely dangerous situation, but if the hydrogen gas generated by the reaction between water and sodium can be detected in advance in the early stages of the reaction, major accidents can be prevented. It is known that when a metal is placed in a corrosive environment, the metal corrodes and at the same time becomes brittle due to the hydrogen atoms VC dissolved in the metal. This can be determined by measuring the amount of hydrogen present in the hydrogen embrittlement, and thereby it is possible to predict and prevent fracture accidents due to hydrogen embrittlement. moreover,
An oxyhydrogen flame is often used in silica glass processing, such as in the manufacture of optical fibers, but in this case as well, detection of hydrogen gas is necessary to prevent hydrogen gas leakage accidents.

Conventional methods for detecting hydrogen gas include gas chromatography, measuring diffused hydrogen gas from pressure changes using a nickel diffusion membrane, and measuring the electrical conductivity of an electrolyte for hydrogen detection. etc., but
Among these methods, the method using gas chromatography and the method using a nickel diffusion membrane each require a large column and mechanically moving parts such as a vacuum pump, which not only require heavy equipment but also require a high-temperature atmosphere. The use of electrolytes is highly restricted depending on the measurement situation, such as in a solution, and methods using electrolytes also have the disadvantages that the sensitivity changes depending on the amount of dissolved oxygen in the solution, and that water evaporates and requires replenishment. The drawback is that many electrolytes are corrosive, and the conditions of use are severely restricted.

(Structure of the Invention) The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and for this reason, the hydrogen gas detector according to the present invention includes a light source of a constant wavelength and a quartz-based light source to which the light from the light source is guided. It consists of a sensor section made of an optical fiber and a measuring means for measuring the amount of transmission loss of light passing through the sensor section, and it is possible to optically measure the amount or concentration of hydrogen gas using the optical fiber. Features.

(Principle and operation of the invention) It has been known that quartz glass has a considerably higher transmittance to l-12 than metals.

Now, when an optical fiber whose core and cladding are made of silica glass is placed in a 1-1 atmosphere, 112 gradually penetrates into the optical fiber, and the 112 molecules become infrared active, increasing the transmission loss of the optical fiber. . Therefore, by using an optical fiber as a sensor section made of quartz glass and measuring the amount of increase in transmission loss, the concentration or concentration of the 11□ gas can be determined.

When the core is 100% 5in2 glass, the increase in transmission loss is due to the increase in the absorption loss of 11□ molecules, which has an absorption peak around the wavelength of 1.24 μm, and this absorption peak lowers the external 11□ partial pressure. Since It2 inside the fiber reversibly diffuses to the outside, it increases or decreases depending on the external 112 partial pressure each time. When the core contains qe02, there is an increase in the absorption loss of Ge0II, which has an absorption peak near a wavelength of 1.4 μm, and this increase in absorption peak is caused by the external I
-12 Shows irreversible characteristics that do not decrease even if the partial pressure is lowered.

This irreversible (', earl absorption peak is P2O
, and by adjusting the fiber temperature, I-
It was found that the sensitivity to 1 increases, and the absorption peak increases in proportion to the 0.4th power of the 112 partial pressure.

(Example) Next, an example of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows an example of the configuration of a hydrogen gas detector according to the present invention, in which light from a light source 1 such as a light emitting diode is separated into measurement light and reference light by a half mirror B, and the measurement light passes through the sensor section. After propagating through the constituent optical fibers 5, it is photoelectrically converted by a light receiver 7, while the reference light is photoelectrically converted by a light receiver 9 for monitoring the light source output, and the outputs of both light receivers 7 and 9 are sent to a computer 11. By comparing optical fiber 5
transmission loss is required. When this optical fiber 5 is placed in an H atmosphere, the transmission loss increases reversibly or irreversibly depending on the type of core glass of the optical fiber as described above. Concentration can be measured.

To make the detector highly sensitive, connect optical fiber 5 as shown in the figure.
It is desirable to increase the working length by winding the optical fiber around the bobbin 13, and it is also preferable to incorporate a heater 15 into the optical fiber to accelerate the reaction. Furthermore, high sensitivity can also be achieved by irradiating the optical fiber serving as the sensor section with gamma rays or ultraviolet rays in advance to increase internal defects.

According to the experimental results of the present invention, 10% by weight of Qe02, P2
An optical fiber 5 having a core made of SiO□ glass containing 10% by weight of O was wound around a 500M bobbin 13, and the optical fiber was heated to about 200'C by a heater 15. A light source 1 with a wavelength of 14 μm OL E'D was used. When the optical fiber 5 was installed in a II2 partial pressure atmosphere of 1 ptILI, an increasing loss of 0.1 dB/i per minute was observed. The same optical fiber used in the above experimental example was passed through the ultraviolet lamp irradiation section at a speed of 10 m/min.
Using an optical fiber as a sensor part, the measurement was performed under the same conditions as in the above experimental example.
An increase in loss was observed. Furthermore, 5i02100%
1kl optical fiber 5 with glass core 13
The optical fiber is wrapped around the heater 15 &
℃ and L E with a wavelength of 1.24 μm as light source 1.
When the optical fiber 5 was installed in a 1% II2 atmosphere using D, 1 dlr/8 cIn was obtained after about 15 minutes.
An increased loss was observed, and this loss decreased with decreasing II2 concentration.

(Effects of the Invention) As described above, according to the present invention, since the hydrogen gas concentration can be detected optically using an optical fiber, the structure of the entire sensor section can be made extremely simple, small and lightweight. It would be possible to greatly alleviate restrictions on use depending on the measurement situation. In particular, since the optical fiber serving as the sensor section has excellent flexibility, fire resistance, water resistance, and corrosion resistance, it is possible to detect hydrogen gas concentration in a wide range of areas and measurement environments.

It should be noted that the present invention can of course be used as a reversible or irreversible sensor by selecting the glass component of the core of the optical fiber used in the sensor section. Composite detection not only allows you to change the measurement range of hydrogen gas concentration by appropriately selecting the heating temperature, but also covers a wide i-1 measurement range by combining multiple detectors with different measurement ranges. It can also be used as a vessel.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the configuration of a hydrogen gas detector according to the present invention. 1: Light source 5: Optical fiber 7.9: Receiver 11: Computer 15: Heater Patent E Sumitomo Electric Industries, Ltd.

Claims (6)

[Claims] (1) A hydrogen gas detector comprising a light source of a constant wavelength, a sensor section made of a quartz optical fiber to which light is guided from the light source, and a measuring means for measuring the amount of transmission loss of the light passing through the sensor section. (2) The core of the optical fiber is made of 100% SiO_2 glass, and the light source is an LE with a wavelength of around 1.24 μm.
A hydrogen gas detector according to claim 1, comprising D. (3) The core of the optical fiber is SiO containing GeO_2
_2 The hydrogen gas detector according to claim 1, wherein the light source is an LED having a wavelength of around 1.4 μm. (4) The core of the early optical fiber is GeO_2 and P_2O_
5. The hydrogen gas detector according to claim 1, wherein the light source is an LED having a wavelength of around 1.4 μm. (5) A hydrogen gas detector according to any one of claims 2 to 4, wherein the sensor section includes a heating mechanism. (6) Claims 2 to 5 in which the optical fiber is an optical fiber that has been irradiated with gamma rays or ultraviolet rays in advance.
Hydrogen gas detector according to any of the paragraphs.