JPS6039171B2 - Hydrogen detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrogen detection device that can continuously measure the concentration of hydrogen contained in a gas with good responsiveness.

For example, if a small water leak occurs in a steam generator in a metal sodium cooled fast reactor plant, there is a risk of damaging adjacent heat transfer tubes and causing a large-scale leak accident.

Therefore, it is necessary to quickly detect small water leaks and prevent accidents from occurring. To detect this water leak, it is required that the sensor has high sensitivity, stability, can be used for a long time, and has a short response delay. Therefore, various means for detecting water leakage are being considered, and among them, means for detecting hydrogen released into sodium or cover gas during the reaction between sodium and water is suitable. To detect this hydrogen, a hydrogen detection device consisting of a diffusion abdominal vacuum gauge and an exhaust device is used, and the device is constructed as shown in FIG. That is, a cylindrical container 3 is attached with an inflow pipe 1 through which a gas to be measured, such as a mixed gas of argon and hydrogen, flows in from one end toward a pond, and an outflow pipe 2 through which the gas flows out. For example, a stainless steel tubular body 6 attached to the flange 2 is suspended from the opening □4. A flange 5 is attached to the opening 4 and becomes integral with the flange 12. A sleeve-shaped diffusion membrane part 7 is connected to this tubular body 6 downward from the center, and the lower end opening of the diffusion membrane part 7 is connected to a stainless steel end plug 7.
It is sealed with a. The diffusion membrane section 7 is made of palladium, iron, nickel, or the like, which selectively transmits hydrogen. A heater 8 is disposed on the outer peripheral surface of the cylindrical container 3 where the diffusion abdomen 7 is located. The heater 8 is adjusted to a predetermined temperature by a temperature control device 9 to which an electromotive force is supplied from a thermocouple N, using an output signal thereof. A sensor 10 is airtightly connected to the flange 12 through a pipe 11 above the flange 2 . The sensor 10 is controlled by a hydrogen detector controller 13. In this apparatus, when the gas to be measured flows in from the inflow pipe 1, hydrogen permeates through the diffusion membrane section 7 and is detected by the sensor 0, that is, the hydrogen detection section 14.

This hydrogen detection section 14 is performed by measuring current, and the controller 3 has an ion pump controller and a recorder incorporated therein. In this conventional hydrogen detection device, the diffusion membrane portion 7 is heated by eel radiation heat from the surrounding area using a heating heater 8 in order to facilitate the selective permeation of hydrogen.

The diffusion film portion 7 is maintained at a constant temperature by the balance between cooling by the gas to be measured and heating by radiation heat. Here, if the flow rate of the gas to be measured is very low, the diffusion membrane section 7
Although the temperature control is performed with good accuracy, there is a drawback, however, that as the flow rate of the gas to be measured increases, a temperature difference occurs along the flow direction of the gas to be measured in the diffusion membrane portion 7. Further, since the diffusion film portion 7 is a metal film having a wall thickness of, for example, 0.25 willow, its heat capacity is extremely small. Therefore, the temperature of the diffusion film portion 7 changes sensitively with minute fluctuations in the gas to be measured. Considering the large heat capacity of the heater 8, it is difficult to absorb this fluctuation satisfactorily even with the use of a high-performance temperature control device capable of extremely precise control. As described above, the diffusion film part has a large temperature dependence, and there is a limit to its precise control, which has the drawback of significantly reducing measurement accuracy. Therefore, in order to improve the measurement accuracy of a hydrogen detection device, it is necessary to precisely control the temperature of the diffusion membrane to within 1°C of the set temperature, and also to prevent sudden changes in the hydrogen concentration in the gas being measured. However, there is a need for a hydrogen detection device with excellent responsiveness. This invention was made in view of the above-mentioned needs, and it is possible to control the temperature of the diffusion membrane part of the hydrogen detection device to a constant temperature with very high accuracy, and also to provide hydrogen with excellent responsiveness to sudden changes in hydrogen concentration. The purpose is to provide a detection device.

``Hereinafter, this invention will be explained in detail with reference to an embodiment shown in FIG.

In FIG. 2, the same parts as in FIG. 1 are indicated by the same reference numerals, and the explanation of the overlapping parts is omitted. That is, the present invention comprises a cylindrical container 3 having an inflow pipe 1 for gas to be measured at one end and an outflow pipe 11 for hydrogen for detection at the end of the tank, and a hollow section provided in the container 3 in a substantially perpendicular direction. A cylindrical ripening shed with both ends closed connected to the plate 15 substantially parallel to the container 3; 11, a hydrogen concentration measurement system 14 connected to the opening of this sleeve 21, and a hydrogen concentration measurement system 14 connected to the opening of the sleeve 21, and This hydrogen detection device is characterized by comprising an outflow pipe 2 for the gas to be measured, which is provided on the container wall in the vicinity of the dividing plate 15 so as not to mix with the gas to be measured. In this invention, the gas to be measured flows into the cylindrical container 3 from the inflow pipe 1, is heated by the heating heater 8, and is maintained at a predetermined temperature while rising inside the heating body 16. It has a U-turn system where the heat passes through the upper opening □ of the body 16, descends along the outer surface of the body 16, and is discharged from the outflow pipe 2.

Here, the hydrogen gas contained in the gas to be measured passes through the hydrogen selectively permeable sleeve 21 and is exhausted by an ion pump via the hydrogen detector controller 3 that enters the sensor 1. The hydrogen concentration in the gas to be measured can be measured from the current value at this time. That is, in this invention, by providing the heating body 16 in the cylindrical container 3, the gas once restricted by the dividing plate is heated and the gas flow inside the body 16 is reduced. Since the inflow side is detected by the temperature detector 19 and the outflow side is detected by the temperature detector 20 and the heater 8 is controlled, the temperature of the entire Ni diffusion film portion of the hydrogen permselective sleeve 21 can be maintained uniformly. The hydrogen concentration can be accurately measured even if there is a change in the gas flow of the gas to be measured. However, by providing this heat shield and body, the gas to be measured must not be allowed to stagnate. Responsiveness deteriorates due to the use of . For example, although not shown, if the outflow pipe is provided near the flanges 5 and 12, the heat will be reduced and the body 16
Since the gas stays in the space formed by the cylindrical container 3 and the hydrogen is accumulated, the hydrogen concentration in that space changes with time and gradually becomes equal to the hydrogen concentration in the gas to be measured. Therefore, when a gas to be measured with a low hydrogen concentration flows in, the hydrogen gas accumulated in this space heats up, diffuses through the body 16, and mixes into the gas to be measured. The hydrogen concentration in the gas to be measured in the river can be higher than the concentration in the gas to be measured flowing in through the inflow pipe 1. This fact shows that the characteristics shown in FIG. 3 are obtained between the hydrogen concentration in the gas to be measured and the measured value measured by sensor 0.

FIG. 3 shows the response of the hydrogen detection device to changes in the hydrogen concentration in the gas to be measured. FIG. 4 is a characteristic curve diagram showing a comparison between a case where no retention occurs. As is clear from this figure, if hydrogen is supplied from the inflow pipe at a rapid rate as shown in curve 1, if the gas stagnates, the hydrogen concentration in the measured gas will suddenly increase as shown in curve 2. Its ability to follow changes is poor,
It can be seen that in the device of the present invention, where gas retention is small, the followability is significantly improved and the response is excellent, as shown by curve 3. As explained above, according to the present invention, the outflow pipe 2 of the gas to be measured is provided near the inflow side of the cylindrical container 3, and the outflow L of the gas to be measured is inside the shield body 16, which is less heated than the inflow pipe 1. flows in contact with the outer surface of the hydrogen selectively permeable sleeve 21, is heated, and is turned back from the tip entrance of the body 16 to make a U-turn to be heated, and the flow between the outside of the body 16 and the cylindrical container 3 is The structure is such that it flows between the two and reaches the outflow pipe 2.

Therefore, without impairing the temperature control characteristics, the measurement value obtained by the sensor 01 is improved in its ability to follow sudden changes in the hydrogen concentration in the gas to be measured flowing in from the inflow pipe 1, and has excellent responsiveness. effective. Note that the hydrogen selectively permeable sleeve is heated by the heat of the gas to be measured, and the transfer of heat through the heat shield and body can be prevented, which not only makes the temperature of the entire sleeve uniform, but also reduces the gas flow rate. Even if the temperature fluctuation is about 10%, the temperature of the diffused abdomen can be adjusted to ±
It is easy to maintain fluctuations within 1°C.

[Brief explanation of the drawing]

FIG. 1 is a device layout diagram showing an example of a conventional hydrogen detection device partially in longitudinal section; FIG. 2 is a device layout diagram partially showing a longitudinal section of an embodiment of the hydrogen detection device according to the present invention; FIG. 3 is a response curve diagram comparing and showing the relationship between hydrogen concentration and elapsed time. 1... Inflow pipe, 2... Outflow pipe (discharge pipe),
3... Cylindrical container, 8... Heater, 10...
...Sensor, 11...Hydrogen outflow tube for detection, 14...Hydrogen concentration measurement system, 15...
・Hollow partition board, 16... heat-resistant body, 21...
...Hydrogen selectively permeable sleeve, L...Flow path. Figure 3 Figure 1 Figure 2

Claims (1)

[Claims] 1. A cylindrical container having an inflow pipe for the gas to be measured at one end and an outflow pipe for the hydrogen gas for detection at the other end, and a hollow dividing plate provided in the container in a direction approximately perpendicular to the container. a cylindrical heat shield with open ends connected in parallel; and a selectively permeable hydrogen sleeve with an open end installed in the shield with one end sealed and attached to the hydrogen outflow pipe. , a hydrogen concentration measurement system connected to the opening of the sleeve, and a gas to be measured installed on the container wall near the dividing plate so as not to mix with the gas in the vicinity of the inflow pipe of the gas to be measured. A hydrogen detection device comprising: a discharge pipe.