JP2015169581A - Physical property dependence type pressure gauge and hydrogen concentration measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen concentration measurement device capable of measuring hydrogen concentration in measured gas with high sensitivity without restricting kinds of measured gas, and a physical property dependence type pressure gauge used in the hydrogen concentration measurement device.SOLUTION: A physical property dependence type pressure gauge 30 includes a pressure measurement element 31, a container 32 storing the pressure measurement element and having an opening 34B, and a hydrogen permeation film 35 arranged in the opening of the container. In the container, gas other than hydrogen is stored, and hydrogen can be introduced or derived through the hydrogen permeation film. The pressure measurement element detects pressure depending on the physical property of mixture gas in the container.

Description

  The present invention relates to a physical property dependent pressure gauge used for measuring a hydrogen concentration in a gas, a hydrogen concentration measuring apparatus using the same, and the like.

  In recent years, the measurement of hydrogen concentration has attracted attention as a result of a hydrogen explosion at a nuclear power plant. For example, Patent Documents 1 and 2 disclose hydrogen concentration meters that are scheduled to be used in a harsh environment such as in a nuclear reactor.

  On the other hand, as a method for obtaining the concentration of a known mixed gas composed of two kinds of gases (for example, a mixed gas of ozone and oxygen), the viscosity, thermal conductivity, density, molecular weight of the mixed gas, and the mixed gas as a function thereof are described. A method is known in which a physical property value is measured and a gas concentration is calculated based on a physical property value unique to pure gas (Patent Document 3).

JP-A-6-130177 Japanese Patent No. 5170600 Japanese Patent No. 3336384

  Some hydrogen concentration meters of Patent Document 1 are provided with, for example, plastic, and there is a problem in terms of heat resistance. The hydrogen concentration meter of Patent Document 2 determines the hydrogen concentration of a monitoring target gas by using the ionization ability of a recoil proton generated by elastic scattering between neutrons and protons (hydrogen nuclei). There is a problem in terms of detection sensitivity. Since patent document 3 measures the density | concentration of the mixed gas which consists of two types of known gas, it is not suitable for the detection of the hydrogen concentration in the air which has multicomponent gas.

  Accordingly, an object of the present invention is to detect hydrogen concentration in the gas to be measured with high sensitivity regardless of the type of gas to be measured, including the case of measuring the hydrogen concentration in the air to be measured. An object of the present invention is to provide a concentration measuring device and a physical property dependent pressure gauge used therefor.

(1) One aspect of the present invention is
A pressure measuring element;
A container having an opening for accommodating the pressure measuring element;
A hydrogen permeable membrane disposed in the opening of the container;
Have
In the container, gas other than hydrogen is accommodated, and hydrogen can be introduced and extracted through the hydrogen permeable membrane,
The pressure measuring element relates to a physical property dependent pressure gauge that detects a pressure depending on a physical property of a mixed gas of the gas and hydrogen in the container.
According to one aspect of the present invention, the amount of hydrogen permeating through the hydrogen permeable membrane is proportional to the difference between the square root of the hydrogen partial pressure in the gas to be measured and the square root of the hydrogen partial pressure in the mixed gas in the container. Therefore, if the hydrogen partial pressure (concentration) in the measurement gas increases, hydrogen in the measurement gas is introduced into the container through the hydrogen permeable membrane. The apparent physical properties (viscosity, thermal conductivity, density, molecular weight, or their function, etc.) of the gas mixture in the container (gas + hydrogen in the container) differ between the physical properties of the gas in the container and the physical properties of hydrogen. From this, it changes according to the hydrogen concentration introduced into the container through the hydrogen permeable membrane. The pressure measuring element of the physical property dependent pressure gauge detects a pressure depending on the physical properties of the mixed gas in the container. The pressure measured by this pressure measuring element reflects the hydrogen concentration in the gas to be measured. In particular, since hydrogen permeable membranes do not transmit gases other than hydrogen, the pressure measuring element in the physical property-dependent pressure gauge is less likely to be affected by the environment, eliminating the cause of measurement errors and providing highly sensitive and accurate hydrogen concentration. Detection is possible. Further, since the hydrogen permeable membrane does not transmit gas other than hydrogen, the gas to be measured other than hydrogen does not contact the pressure measuring element of the physical property dependent pressure gauge. Therefore, there are no restrictions on the type of gas to be measured in using the physical property dependent pressure gauge.

(2) In one mode of the present invention, the gas may be a gas having a viscosity value that differs by one digit or more with respect to the viscosity value (μ · Pa · s) of hydrogen.
The physical property-dependent pressure gauge can include, for example, gas viscosity as a dependent physical property. The viscosity value of hydrogen is 8.8 (μ · Pa · s). As the viscosity value of the gas in the container is larger than the viscosity value of hydrogen, for example, the apparent viscosity value of the mixed gas in the container mixed with hydrogen introduced into the container through the hydrogen permeable membrane decreases. As a result, the apparent pressure of the mixed gas measured by the physical property (viscosity) dependent pressure gauge decreases. If the difference between the viscosity value of the gas in the container and the viscosity value of hydrogen is large, the output change of the physical property (viscosity) -dependent pressure gauge is large according to the hydrogen concentration introduced into the container. According to one embodiment of the present invention, the measurement sensitivity with respect to the hydrogen concentration can be improved by using a gas having a viscosity value that differs by one digit or more with respect to the viscosity value of hydrogen.

(3) In one aspect of the present invention, the gas may be air.
The viscosity value of air is 17.08 (μ · Pa · s), and the viscosity value differs by one digit or more from the viscosity value of hydrogen.

(4) In one embodiment of the present invention, the gas may be nitrogen.
The viscosity value of nitrogen is 17.6 (μ · Pa · s), and the viscosity value differs by one digit or more from the viscosity value of hydrogen.

(5) In one mode of the present invention, it can further have a filter which protects the above-mentioned hydrogen permeable film from impurities.
When the physical property-dependent pressure gauge is used in a nuclear reactor, for example, it is possible to prevent the hydrogen permeable membrane from being contaminated by water vapor or the like that is generated in a large amount in the event of a nuclear reactor accident.

(6) In one aspect of the present invention, the pressure measuring element may be a tuning fork type crystal resonator.
According to one aspect of the present invention, the tuning fork type crystal resonator as the pressure measuring element measures the pressure using the viscosity (friction), and thus measures the pressure depending on the physical property (viscosity) of the mixed gas. be able to.

(7) Another aspect of the present invention is:
A hydrogen concentration measuring device for measuring a hydrogen concentration in a gas to be measured,
The physical property dependent pressure gauge according to any one of (1) to (6) above,
A pressure-sensitive pressure gauge that is in contact with the gas to be measured and measures a pressure that does not depend on a physical property value of the gas to be measured;
The physical property-dependent pressure gauge under a first pressure measured by the physical property-dependent pressure gauge, a second pressure measured by the pressure-sensitive pressure gauge, a known hydrogen concentration and a known pressure of a measured object A concentration calculator for obtaining a hydrogen concentration in the measurement gas based on a calibration curve acquired in advance by
The present invention relates to a hydrogen concentration measuring apparatus having
According to another aspect of the present invention, a pressure sensitive pressure gauge is used in combination with the physical property dependent pressure gauge described in (1) to (6). The pressure-sensitive pressure gauge in contact with the gas to be measured detects the pressure of the gas to be measured without being affected by the physical properties of the gas to be measured. The physical property dependent pressure gauge outputs the first pressure. The pressure-sensitive pressure gauge outputs the second pressure. The concentration calculator can determine the hydrogen concentration using the first pressure, the second pressure, and the calibration curve. Here, the ridge line is acquired in advance by a physical property-dependent pressure gauge under a known hydrogen concentration and a known pressure of the object to be measured.

It is a block diagram of the hydrogen concentration measuring device concerning one embodiment of the present invention. FIG. 2 is an exploded perspective view of a physical property-dependent pressure gauge (for example, a viscous pressure gauge) that measures a pressure depending on the physical properties of a gas used in the hydrogen concentration measurement apparatus shown in FIG. 1. It is a figure which shows the permeation | transmission principle of hydrogen in the palladium membrane which is an example of a hydrogen permeable thin film. It is a characteristic view which shows the instruction | indication change of the crystal oscillator type pressure gauge when the viscosity coefficient of nitrogen is used. It is a characteristic view which shows the change by the gas pressure of the resonance resistance of a crystal oscillator. It is a characteristic view which shows the instruction | indication change of the crystal oscillator type pressure gauge when hydrogen is mixed. It is a characteristic view which shows the instruction | indication change (calibration curve) of the quartz oscillator type pressure gauge with respect to the pressure when mixing hydrogen with air. It is the schematic of the experimental apparatus containing a chamber. It is a characteristic view which shows the change of the display output of a crystal oscillator type pressure gauge when hydrogen is introduce | transduced in the chamber with the experimental apparatus of FIG. 10A to 10D show the relationship between the hydrogen concentration (%) and the preamplifier output (V) when the gas in the container is air and the temperature is raised from room temperature to 150 ° C. FIG. 11A to 11C show the relationship between the hydrogen concentration (%) and the preamplifier output (V) when the gas in the container is air and the temperature is raised from 200 ° C. to 300 ° C. FIG. 12 (A) to 12 (D) show the relationship between the hydrogen concentration (%) and the preamplifier output (V) when the gas in the container is nitrogen and the temperature is raised from room temperature to 150 ° C. FIG. FIGS. 13A to 13C show the relationship between the hydrogen concentration (%) and the preamplifier output (V) when the gas in the container is nitrogen and the temperature is raised from 200 ° C. to 300 ° C. FIG. It is a control system figure of a hydrogen concentration measuring device. It is another control system figure of a hydrogen concentration measuring device. It is a control system block diagram of a hydrogen concentration measuring device. It is a figure which shows the example which added the filter which blocks | prevents passage of an impurity and protects a hydrogen permeable film to the physical property dependence type pressure gauge shown in FIG.

1. Outline of Hydrogen Concentration Measuring Device Hereinafter, embodiments of the present invention will be described. FIG. 1 is a block diagram of a hydrogen concentration measuring apparatus according to an embodiment of the present invention. In FIG. 1, for example, a hydrogen concentration measuring device 20 that measures the hydrogen concentration of a gas to be measured in a chamber 10 includes a physical property-dependent pressure gauge 30, a pressure-sensitive pressure gauge 40, and a concentration calculator 50. The physical property-dependent pressure gauge 30 and the pressure-sensitive pressure gauge 40 are connected to the chamber 10 via the pipe 11.

  Examples of the physical property-dependent pressure gauge 30 whose pressure changes according to the physical properties of gas (viscosity, thermal conductivity, density, molecular weight, or a function thereof) include a quartz friction vacuum gauge and a spinning rotor that use viscosity (friction). Gauges, thermocouple vacuum gauges and Pirani vacuum gauges that use heat conduction, Knudsen vacuum gauges, etc. can also be used. Also, for example, hot cathode ionization vacuum gauges, cold cathode ionization vacuum gauges, radiation ionization vacuums that use ionization phenomena A meter or the like can be used.

  As the pressure-sensitive pressure gauge 40, for example, a liquid column differential gauge, a compression gauge, a diaphragm gauge, a Bourdon tube gauge, etc. can be used.

2. Physical Property Dependent Pressure Gauge FIG. 2 is an exploded perspective view of sensor element 30A in, for example, viscosity pressure gauge 30 which is a physical property dependent pressure gauge used in hydrogen concentration measuring apparatus 20 shown in FIG. In FIG. 2, the sensor element 30 </ b> A includes, for example, a tuning fork type crystal resonator 31 that is a pressure measuring element, and a container 32 that houses the tuning fork type crystal resonator 31. For this reason, the viscous pressure gauge 30 is also referred to as a quartz vibrator pressure gauge 30. The container 32 includes a base 33 and a cylinder 34. An opening 34 </ b> A on one end side of the cylinder 34 is connected to the base portion 33. The opening 34 </ b> B on the other end side of the cylinder 34 is covered with a hydrogen permeable film 35.

  The hydrogen permeable membrane 35 may be of any type as long as it is permeable to hydrogen. However, when pores such as polymer membranes, ceramic membranes, zeolite membranes, and nanocarbon materials are used, problems of heat resistance and hydrogen selectivity may occur. Therefore, it is preferable to use a hydrogen-permeable metal thin film in which molecules dissociate into atoms and permeate on the metal surface. The hydrogen permeable film 35 is compensated for mechanical strength, for example, by forming a hydrogen permeable metal thin film on a porous body. This is because the thinner the hydrogen-permeable metal thin film, the better the hydrogen permeability, and the mechanical strength cannot be compensated only by the hydrogen-permeable thin film. Examples of the hydrogen permeable metal thin film include palladium (PD), vanadium (V), niobium (NB), tantalum (Ta), or an alloy containing any of them, Nb-TiNi alloy, zirconium (Zr) and nickel (Ni An amorphous alloy made of

  The hydrogen permeable membrane 35 can come into contact with the gas to be measured in the chamber 10 through the pipe 11 shown in FIG. The base 33 supports the lead wire 31B connected to the electrode 31A of the tuning-fork type crystal resonator 31, so that the tuning-fork type crystal resonator 31 is not in contact with the container 32 except for the lead wire 31B. Be contained. The base 33 is provided with an external terminal 36 that is electrically connected to the lead wire 31 </ b> B and exposed to the outside of the container 32. In addition, a gas different from hydrogen, such as air, is enclosed in the container 32.

  The viscous pressure gauge 30 is a drive / detection circuit 100 connected to the sensor element 30A shown in FIG. 2 (see FIG. 16). The drive / detection circuit 100 supplies a drive signal to the tuning fork crystal unit 31 and detects an output signal thereof. When the drive / detection circuit 100 is viewed as an output stage of the sensor element 30A, the drive / detection circuit 100 has a function as a preamplifier for preamplification. Therefore, in this specification, the drive / detection circuit 100 is also referred to as a preamplifier.

3. Hydrogen Permeation Principle of Hydrogen Permeation Membrane FIG. 3 shows the hydrogen permeation principle in a palladium membrane 35A which is an example of a hydrogen permeable thin film in the hydrogen permeable membrane 35. The gas to be measured in the chamber 10 shown in FIG. 1 comes into contact with the palladium film 35 </ b> A of the viscous pressure gauge 30 through the pipe 11. If hydrogen is present in the gas to be measured in the chamber 10, hydrogen molecules are adsorbed on the surface of the palladium film 35A. The adsorbed hydrogen molecules are dissociated into hydrogen atoms at the palladium film 35A. Furthermore, hydrogen atoms dissociate into atomic hydrogen (protons) and electrons. The atomic hydrogen (proton) and electrons diffuse into the palladium film 35A. Atomic hydrogen (proton) and electrons diffused toward the container 32 in the palladium film 35A are recombined to form hydrogen atoms. The hydrogen atoms recombine with hydrogen molecules, desorb from the palladium film 35A, and are mixed with the air in the container 32.

The hydrogen permeation amount J (Nml / min · cm ² ) of the palladium membrane 35A is obtained by the following equation (2).
J = α (PH ₂ (1) ^1/2 −PH ₂ (2) ^1/2 ) (2)
Here, α is the hydrogen permeation rate, PH ₂ (1) is the hydrogen partial pressure of the gas to be measured in the chamber 10, and PH ₂ (2) is the hydrogen partial pressure in the mixed gas in the container 32. As described above, in the palladium film 35A, the hydrogen molecules are dissociated to become atomic hydrogen (protons). Therefore, the square root of the hydrogen partial pressure PH ₂ (1) of the gas to be measured in the chamber 10 and the mixed gas in the container 32 It is proportional to the difference from the square root of the hydrogen partial pressure PH ₂ (2). The hydrogen permeation amount J is inversely proportional to the film thickness of the palladium film 35A. Therefore, the hydrogen permeation amount J increases as (PH ₂ (1) ^1/2 -PH ₂ (2) ^1/2 ) increases and / or the thickness of the palladium film 35A decreases. If the value of (PH ₂ (1) ^1/2 -PH ₂ (2) ^1/2 ) is positive, hydrogen permeates to the container 32 side, and (PH ₂ (1) ^1/2 -PH ₂ ( 2) If the value of ^1/2 ) is negative, hydrogen permeates to the chamber 10 side. Therefore, the hydrogen concentration in the container 32 is correlated with the hydrogen concentration in the chamber 10.

  As described above, by disposing the hydrogen permeable film 35 in the container 32, the hydrogen permeable film 35 does not allow other than hydrogen to pass through the container 32. Therefore, it is possible to prevent impurities from adhering to the tuning fork type crystal resonator 31, and the adverse effect due to the composition variation of the gas to be measured in the chamber 10 does not affect the tuning fork type crystal resonator 31. Therefore, it becomes difficult to be affected by the environment, and it is possible to detect the hydrogen concentration with high sensitivity and high accuracy by eliminating the cause of the measurement error.

4). Principle of gas measurement by tuning fork type crystal resonator The drag received by the vibrating tuning fork type crystal resonator 31 is not only the pressure of the mixed gas (for example, air or nitrogen + hydrogen) in the container 32 but also the viscosity of the mixed gas. Sensitive. Since the viscosity of the gas is specific to the gas type, the drag received by the tuning fork type crystal resonator 31 varies with the gas type. An example is shown in FIG. When the pressures of various gases (hydrogen, argon, helium) are measured by the quartz oscillator pressure gauge 30 (all assuming that nitrogen is accommodated in the container 32, the quartz oscillator pressure gauge 30 Indicates the pressure measurement value of the gas (hydrogen, argon, helium) with respect to the pressure of the gas to be measured. Hydrogen whose viscosity is lower than that of nitrogen is measured with a low apparent pressure, and argon with a high viscosity has a large measured pressure. This is due to the fact that the drag becomes small even at the same pressure in the case of a gas having a low viscosity. It is known that the change ΔZ of the resonance impedance of the crystal resonator is expressed by the following unified formula in the entire pressure region (molecular flow, intermediate flow, viscous flow).

Here, in Equation (1), C is a constant, R is the thickness of the tuning fork crystal unit 31, ω is the resonance frequency, η is the gas viscosity, and ρ is the gas density.

  In the actual quartz crystal type pressure gauge 30, the change in the resonance resistance of the tuning fork type crystal resonator 31 is read and calculated as a pressure change. FIG. 5 shows the theoretical characteristics of the change in resonance resistance due to pressure. At a pressure of 10 Pa or more, particularly near atmospheric pressure, the resonance resistance depends on both the viscosity and the density of the gas molecules, and both change in proportion to their square roots. When the pressure is changed from reduced pressure to atmospheric pressure, the amount of change in the resonance resistance increases as the molecular weight of the gas increases, and the magnitude is proportional to the square root of the molecular weight of the gas molecule.

  In addition, the pressure depending on the density of the gas molecules can be excluded from the output of the quartz oscillator type pressure gauge 30. The pressure depending on the density of gas molecules has a correlation with the output of the pressure-sensitive pressure gauge 40. That is, even if the hydrogen concentration is the same, if the gas pressure in the chamber 10 is high, the output of the quartz oscillator pressure gauge 30 also increases. For this reason, it is preferable to authorize the output of the quartz oscillator pressure gauge 30 with the output of the pressure-sensitive pressure gauge 40 to obtain a pressure depending on the viscosity of the gas. Thereby, the accuracy of the measured hydrogen concentration can be increased.

5. Principle of Measurement with Hydrogen Concentration Measurement Device FIG. 6 shows an example in which the change in viscosity when hydrogen is mixed into the air in the container 32 is observed as a change in the indicated value of the quartz vibrator type pressure gauge 30. Here, air is accommodated in the container 32 of the quartz oscillator pressure gauge 30, and the quartz oscillator pressure gauge 30 uses the viscosity value of air.

  Here, the difference in physical properties such as hydrogen and air is as follows. First, the molecular weight of hydrogen is 2.0016 (g / mole), and the viscosity of hydrogen is 8.8 (μ · Pa · s). The air contains 78% nitrogen, 21% oxygen, 0.9% Ar, 0.03% CO2, and the like. The molecular weight of air is 28.966 (g / mole), and the viscosity of air is 17.08 (μ · Pa · s), both of which are one or more orders of magnitude higher than hydrogen. The molecular weight of nitrogen, which is the main gas of air, is 28.0134 (g / mole), and the viscosity of nitrogen is 28.0134 (μ · Pa · s), both of which are one or more orders of magnitude higher than hydrogen. The molecular weight of oxygen, the other main gas of air, is 31.9998 (g / mole), and the viscosity of oxygen is 20.4 (μ · Pa · s), both of which are more than an order of magnitude compared to hydrogen. large.

  In FIG. 6, the indication value of the pressure-sensitive pressure gauge (BARATRON) 40 that measures the pressure of the gas to be measured in the chamber 10 hardly changes before and after the introduction of hydrogen. On the other hand, the indication value of the quartz oscillator type pressure gauge 30 becomes smaller than the viscosity of only air due to the mixing of hydrogen, and the apparent pressure decreases. As described above, since the mass and viscosity of hydrogen and air are greatly different, when air and hydrogen are mixed in the container 32, the average mass and viscosity of the mixed gas are reduced. Therefore, it is easy to estimate the hydrogen concentration by applying a pressure depending on the change in the physical properties of the mixed gas in the container 32 with the quartz oscillator pressure gauge 30 before and after the hydrogen leakage in the chamber 10.

  The change in the pressure indication value of the quartz oscillator type pressure gauge 30 due to hydrogen mixing is observed in the entire pressure region as shown in FIG. 7, and is also observed under reduced pressure. The amount of change in the measurement pressure in the quartz oscillator type pressure gauge 30 has a monotonous relationship between the viscosity of the gas and the concentration ratio of the gas to be measured. The response speed of hydrogen detection by the quartz oscillator type pressure gauge 30 can be obtained by an experiment with an experimental apparatus shown in FIG. As shown in FIG. 8, a known hydrogen gas is introduced through a mass flow meter (MFC) 61 after air is introduced to atmospheric pressure into a chamber 10 into which air can be introduced by a rotary pump (RP) 60. It calculated | required from the pressure change in the chamber 10 at that time. FIG. 9 shows the results, with the horizontal axis representing time, the left vertical axis representing the output change of the tuning fork type crystal resonator 31, and the output before hydrogen introduction as 1.0. The right vertical axis in FIG. 9 indicates the hydrogen concentration. The irregular change in the indicated value after the introduction of hydrogen is due to flow disturbance. From this result, it can be seen that the response speed of the hydrogen detection of the quartz oscillator type pressure gauge 30 is as short as about 1 second.

  In the quartz resonator type pressure gauge 30 shown in FIG. 2, the resonance resistance of the tuning fork type quartz resonator 31 depends on both viscosity and pressure parameters in the vicinity of atmospheric pressure. Therefore, the pressure of the mixed gas in the container 32 is measured by the pressure-sensitive pressure gauge 40, and the pressure component of the quartz oscillator pressure gauge 30 is eliminated, thereby obtaining a pressure depending on the viscosity of the mixed gas in the container 32. .

  From the pressure of the quartz oscillator pressure gauge 30, the pressure of the pressure sensitive pressure gauge 40, and the acquired data (calibration curve) of the indicated value of the quartz oscillator pressure gauge 30 for the known concentration and pressure shown in FIG. The concentration can be calculated. That is, in FIG. 1, the absolute pressure of the gas to be measured in the chamber 10 is measured by the pressure-sensitive pressure gauge 40, the pressure depending on the viscosity of the mixed gas in the container 32 is measured by the quartz oscillator pressure gauge 30, and the concentration is measured. The computing unit 50 can compare the known calibration curve shown in FIG. 6 with the measured pressure to calculate the hydrogen concentration. At this time, as described above, it is preferable that the output of the quartz oscillator pressure gauge 30 is authorized by the output of the pressure-sensitive pressure gauge 40 and a pressure depending on the viscosity of the gas is used.

6). Measurement Results FIGS. 10A to 10D and FIGS. 11A to 11C show hydrogen when the gas in the container 32 is air and the temperature is raised from room temperature to 300 ° C. It is a characteristic view showing the relationship between density (%) and preamplifier output voltage (V). 12 (A) to 12 (D) and FIGS. 13 (A) to 13 (C) show the hydrogen concentration when the gas in the container 32 is nitrogen and the temperature is raised from room temperature to 300 ° C. %) And a preamplifier output (V). Here, the horizontal axis of FIGS. 10 to 13 is the hydrogen concentration (%), and the vertical axis is the preamplifier output voltage (V). Further, QO in FIGS. 10 to 13 is an output of the quartz oscillator type pressure gauge 30, PQO is a value obtained by normalizing QO with a total pressure as an output of the pressure-sensitive pressure gauge 40, and NQO further represents PQO It is the value normalized by temperature. Regardless of whether the gas in the container 32 is air or nitrogen, the viscosity value is significantly different from that of hydrogen as shown in Table 1, so that a highly sensitive and linear characteristic can be obtained. Note that the variation in data at 250 ° C. and 300 ° C. is caused by melting of the solder used in the apparatus, and can be eliminated by changing to the joining means such as wire bonding.

7). Control Unit of Hydrogen Concentration Measurement Device Among the hydrogen concentration measurement device 20 shown in FIG. 1 including the crystal oscillator type pressure gauge 30 and the pressure sensitive pressure gauge 40, the pressure sensitive pressure gauge 40 is a pressure sensitive type installed in the chamber 10. The pressure gauge can be used as it is.

  14 shows, for example, a maximum of 16 quartz crystal type pressure gauges 30 in which a drive / detection circuit (preamplifier) 100 is added to the sensor element 30A of FIG. The control unit 80 (concentration calculator 50) calculates the concentration. The measurement results measured within 1 second by each crystal oscillator pressure gauge 30 can be displayed on a display unit (not shown).

  FIG. 15 shows an example in which the signal of up to 16 crystal oscillator type pressure gauges 30 is switched by an analog switch 91 and the concentration is calculated by one control unit 90 (concentration calculator 50) as in FIG. . In this case, the sampling time of each crystal oscillator type pressure gauge 30 is 1 second / ch, and when a maximum of 16 channels are used, the density display of one channel is every 16 seconds.

  A pressure-sensitive pressure gauge 40 installed in the chamber 10 is also connected to the control unit 80 shown in FIG. 13 and the control unit 90 shown in FIG. 14, but is omitted in FIGS. 13 and 14.

  FIG. 16 shows a control system block diagram of the crystal oscillator type pressure gauge 30 and the control unit 80 (90) shown in FIG. 14 or FIG. In FIG. 15, the sensor element 30 </ b> A of the crystal resonator type pressure gauge 30 is connected to a drive / detection circuit (preamplifier) 100. The drive / detection circuit 100 (preamplifier) supplies a drive signal from the drive circuit 101 to the tuning fork crystal resonator 31 in the sensor element 30A, and amplifies and outputs the signal detected by the tuning fork crystal resonator 31. It is.

  The signal from the sensor element 30 </ b> A is voltage-converted by the current-voltage converter 102, amplified by the 32 KHz amplifier 103, converted to a direct current of the 32 KHz AC signal by the full-wave rectifier circuit 104, and output to the concentration calculator 50. The 32 KHz AC signal from the 32 KHz amplifier 103 is input to the phase detector 105 to detect the phase. Based on the output of the phase detector 105, the analog switch 106 generates a rectangular wave signal that is alternately inverted between positive and negative at 32 KHz, and supplies it to the drive circuit 101. The drive circuit 101 drives the tuning fork type crystal resonator 31 using positive and negative rectangular wave signals as drive signals. A reference voltage supplied to a circuit in the drive / detection circuit (preamplifier) 100 is generated by a reference voltage generation unit 109. When the substrate temperature changes, the output voltage of the drive / detection circuit (preamplifier) 100 varies even at the same hydrogen concentration. Therefore, a temperature sensor 107 is provided on the substrate on which the drive / detection circuit (preamplifier) 100 is mounted. The voltage correction unit 108 outputs a correction signal for correcting the reference voltage generated by the reference voltage generation unit 109 based on the detection signal from the temperature sensor 107. As a result, the temperature of the drive / detection circuit (preamplifier) 100 is compensated. A temperature monitor signal is output from the reference voltage generator 109 and supplied to the concentration calculator 50.

  In the density calculator 50, the output of the full-wave rectifier circuit 104 is converted to a digital value by a 16-bit resolution A / D converter 51 and input to a CPU 52 having a RAM and a ROM. The flash memory 53 connected to the CPU 52 stores in advance the relationship between the gas viscosity and the gas concentration (calibration curve shown in FIG. 7) and the output voltage versus temperature characteristic data of the drive / detection circuit (preamplifier) 100.

  The preamplifier substrate temperature is determined by the temperature sensor 107 installed on the preamplifier substrate on which the drive / detection circuit (preamplifier) 100 is mounted, and the output voltage due to the preamplifier substrate temperature is corrected. From the viscosity information of the pressure gauge 30 and calibration curve data, the hydrogen concentration is calculated by the CPU 52 and displayed on the display 110. In order to remove the above-described pressure component depending on the gas density included in the output of the quartz oscillator type pressure gauge 30, the output of the pressure-sensitive pressure gauge 40 that detects the pressure in the chamber 10 is used.

  The measurement accuracy of the hydrogen concentration is the cost for reading the impedance change amount of the tuning-fork type crystal resonator 31 which is a sensor of the crystal resonator type pressure gauge 30 employed as a viscous pressure gauge as stable and with high resolution as possible. It is determined by electronic circuits with good performance and software.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above. For example, the gas to be measured is not limited to air but may be any gas. The gas accommodated in the container 32 is not limited to air or nitrogen, but has a viscosity value different from that of hydrogen, does not react with hydrogen, and has a larger difference in viscosity value with respect to hydrogen. Examples of other gases having a viscosity value different by one digit or more with respect to the viscosity value (μ · Pa · s) of hydrogen include He, Ne, Kr, and Xe. The gas other than hydrogen stored in the container 32 is not limited to a single gas, but may be a mixed gas of various gases such as air.

  FIG. 17 shows an example in which a filter 37 that prevents the passage of impurities and protects the hydrogen permeable membrane 35 is added to the physical property dependent pressure gauge 30 shown in FIG. The filter 37 is fixed to a support 38, and the support 38 is attached to the cylinder 34 of the physical property-dependent pressure gauge 30 with, for example, Kovar glass interposed therebetween. When the physical property dependent pressure gauge 30 is used in, for example, a nuclear reactor, the filter 37 can prevent the hydrogen permeable membrane 35 from being contaminated by a large amount of water vapor generated in a nuclear reactor accident. As the filter 37, for example, a porous body such as a SUS316L fine particle sintered body can be used.

  10 chambers, 11 pipes, 20 hydrogen concentration measuring device, 30 physical property dependent pressure gauge (viscosity pressure gauge, crystal oscillator pressure gauge), 30A sensor element, 31 pressure measurement element (tuning fork type crystal oscillator), 32 container , 33 base, 34 cylinder, 34B opening, 35 hydrogen permeable membrane, 40 pressure sensitive pressure gauge, 50 concentration calculator, 51 AD converter, 52 CPU, 53 flash memory, 80, 90 control unit, 100 drive / detection circuit ( Preamplifier), 101 drive circuit, 102 current-voltage converter, 103 32 KHz amplifier, 104 full-wave rectifier circuit, 105 phase detector, 106 analog switch, 110 display

Claims (7)

A pressure measuring element;
A container having an opening for accommodating the pressure measuring element;
A hydrogen permeable membrane disposed in the opening of the container;
Have
In the container, gas other than hydrogen is accommodated, and hydrogen can be introduced and extracted through the hydrogen permeable membrane,
The physical property dependent pressure gauge, wherein the pressure measuring element detects a pressure depending on a physical property of a mixed gas of the gas and hydrogen in the container. In claim 1,
The physical property-dependent pressure gauge, wherein the gas has a viscosity value that differs by one digit or more with respect to a viscosity value (μ · Pa · s) of hydrogen. In claim 2,
The physical property-dependent pressure gauge, wherein the gas is air. In claim 2,
The physical property-dependent pressure gauge, wherein the gas is nitrogen. In any one of Claims 1 thru | or 4,
A physical property dependent pressure gauge further comprising a filter for protecting the hydrogen permeable membrane from impurities. In any one of Claims 1 thru | or 5,
The physical property-dependent pressure gauge, wherein the pressure measuring element is a tuning fork type crystal resonator. A hydrogen concentration measuring device for measuring a hydrogen concentration in a gas to be measured,
The physical property dependent pressure gauge according to any one of claims 1 to 6,
A pressure-sensitive pressure gauge that is in contact with the gas to be measured and measures a pressure that does not depend on a physical property value of the gas to be measured;
The physical property-dependent pressure gauge under a first pressure measured by the physical property-dependent pressure gauge, a second pressure measured by the pressure-sensitive pressure gauge, a known hydrogen concentration and a known pressure of a measured object A concentration calculator for obtaining a hydrogen concentration in the measurement gas based on a calibration curve acquired in advance by
A hydrogen concentration measuring apparatus comprising: