JP2005043291A - Device and method for measuring concentration of hydrogen gas and/or lower hydrocarbon gas in mixture gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method capable of measuring selectively the concentration of hydrogen gas and/or a lower hydrocarbon gas in a mixture gas of two or more kinds including the hydrogen gas. <P>SOLUTION: This device is equipped with an optical interferometer unit 20 and a catalyst unit 50. The catalyst unit has a catalyst storage part 52 for storing a prescribed catalyst, and a heating means 54 for heating the catalyst in the catalyst storage part up to a prescribed temperature. The device has a constitution wherein a measuring mixture gas is allowed to pass the catalyst heated up to the prescribed temperature, the hydrogen gas or the hydrogen gas and the lower hydrocarbon gas in the measuring mixture gas are consumed by a reaction with the catalyst at the prescribed temperature, and the concentration of the hydrogen gas and/or the lower hydrocarbon gas is measured. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention generally relates to an apparatus and method for measuring the concentration of hydrogen gas and / or lower hydrocarbon gas in a mixed gas. More specifically, the present invention selectively measures hydrogen gas and / or lower hydrocarbon gas in a mixed gas containing air in a hydrogen supply / storage facility in a fuel cell system such as an automobile hydrogen station or residential use. The present invention relates to an apparatus and a method for doing so. The lower hydrocarbon in the present invention includes methane, ethane, propane, butane and pentane.

  In recent years, fuel cell systems for automobile hydrogen stations and residential use have been developed, and opportunities for handling hydrogen gas are increasing. As is well known, hydrogen gas is flammable and explosive and must be handled with care. Conventionally, portable measuring instruments for measuring the concentration of hydrogen gas, etc. are based on optical measurements such as optical interference type and optical absorption type, catalytic combustion type using a catalytic element and semiconductor type electrochemical Various types are known, such as a thermistor type using heat conduction.

  However, for example, for combustible gases mixed such as methane gas and hydrogen gas, it is possible to selectively separate and measure two or more types of mixed gases, except when using the above-mentioned light absorption type measuring instrument. Can not. Further, in the conventional technique, in order to measure the total concentration of a plurality of kinds of mixed gases, a large light source having a wide wavelength must be used, so that the apparatus becomes large and does not have a safe explosion-proof structure. There was a problem.

  Accordingly, an object of the present invention is to provide an apparatus and a method that enable selective measurement of the concentration of hydrogen gas and / or lower hydrocarbon gas in two or more gas mixtures containing hydrogen gas.

  The present invention provides a novel gas concentration measuring apparatus and method by combining a conventional technique for measuring a gas concentration using a difference in refractive index of light and a catalyst technique. That is, by utilizing the fact that the catalyst has a different reaction temperature range for a specific gas, the concentration of hydrogen gas and / or lower hydrocarbon gas can be selectively measured.

  The hydrogen gas and / or lower hydrocarbon gas concentration measuring device according to claim 1 comprises an optical interferometer unit, and the optical interferometer unit splits a light beam from a light source into two light beams, and One of the divided light beams passes through a standard gas chamber, and the other of the divided light beams passes through a mixed gas chamber to be measured in which a mixed gas to be measured is sealed; Means for superimposing on one light beam, and means for determining a gas concentration by measuring interference fringes generated when superimposing on the one light beam, further comprising a catalyst unit, wherein the catalyst unit contains a predetermined catalyst. And a heating means for heating the catalyst in the catalyst housing part to a predetermined temperature, and passing the measured mixed gas through the catalyst heated to the predetermined temperature, The reaction with the catalyst at a predetermined temperature consumes hydrogen gas or hydrogen gas and lower hydrocarbon gas in the mixed gas, thereby measuring the concentration of the hydrogen gas and / or lower hydrocarbon gas. It is characterized by that.

  The hydrogen gas and / or lower hydrocarbon gas concentration measuring device according to claim 2 of the present invention is the device according to claim 1, wherein the predetermined temperature is 0 ° C to 50 ° C, 100 ° C to 200 ° C, Alternatively, it is any one of 250 ° C to 350 ° C.

  The hydrogen gas and / or lower hydrocarbon gas concentration measuring device according to claim 3 of the present application is the device according to claim 1 or 2, wherein the catalyst is platinum, palladium, iridium, ruthenium, gold, rhenium, nickel, cobalt. And at least one metal selected from the group consisting of iron.

  The hydrogen gas and / or lower hydrocarbon gas concentration measuring device according to claim 4 of the present application is the device according to any one of claims 1 to 3, wherein the catalyst carrier is activated carbon, carbon nanotube, It is any one of molecular sieve, zeolite, alumina, silica, titanium oxide, zirconium oxide, or cerium oxide.

  The method for measuring hydrogen gas and / or lower hydrocarbon gas concentration according to claim 5 of the present invention uses an optical interferometer unit to split a light beam from a light source into two light beams, and among the split light beams Passing one through a standard gas chamber and passing the other of the divided light beams through a mixed gas chamber to be measured in which a mixed gas to be measured is sealed; and superimposing the two light beams on one light beam; , Determining the gas concentration by measuring interference fringes generated upon superimposing on the one light beam, and passing the measured mixed gas through the catalyst heated to a predetermined temperature, thereby reacting with the catalyst at the predetermined temperature In the mixed gas, hydrogen gas or hydrogen gas and lower hydrocarbon gas are consumed, and the gas thus obtained is supplied to the mixed gas chamber to be measured. It is characterized in that comprising the step of measuring the interference fringes with a unit.

  The hydrogen gas and / or lower hydrocarbon gas concentration measuring method according to claim 6 of the present invention is the method of claim 5, wherein the predetermined temperature is 0 ° C to 50 ° C, 100 ° C to 200 ° C, Alternatively, it is any one of 250 ° C to 350 ° C.

  The hydrogen gas and / or lower hydrocarbon gas concentration measuring method according to claim 7 of the present invention is the method according to claim 5 or 6, wherein the catalyst is platinum, palladium, iridium, ruthenium, gold, rhenium, nickel, cobalt. And at least one metal selected from the group consisting of iron.

  The hydrogen gas and / or lower hydrocarbon gas concentration measuring method according to claim 8 of the present application is the apparatus according to any one of claims 5 to 7, wherein the catalyst carrier is activated carbon, carbon nanotube, It is any one of molecular sieve, zeolite, alumina, silica, titanium oxide, zirconium oxide, or cerium oxide.

  ADVANTAGE OF THE INVENTION According to this invention, the portable measuring apparatus and method which can selectively measure the density | concentration of the hydrogen gas in a mixed gas and / or a lower hydrocarbon gas by adjusting the temperature range of a catalyst are provided. . In addition, the apparatus and method of the present invention have an explosion-proof structure that does not ignite with an electric spark at any flammable gas concentration, and at a gas production site, a hydrogen storage / supply facility for fuel cells, a hydrogen station, etc. It can be used safely.

  Next, a hydrogen gas and / or lower hydrocarbon gas concentration measuring device according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic overall view showing a hydrogen gas and / or lower hydrocarbon gas concentration measuring apparatus according to a preferred embodiment of the present invention. A hydrogen gas and / or lower hydrocarbon gas concentration measuring apparatus according to a preferred embodiment of the present invention, indicated as a whole by reference numeral 10 in FIG. 1, includes an optical interferometer unit 20 and a catalyst unit 50. In FIG. 1, only the gas chamber is shown for the optical interferometer unit 20 in order to simplify the drawing.

  FIG. 2 is a schematic diagram showing a basic configuration of the optical interferometer unit 20. In FIG. 2, 22 is a light source, 24 is a lens, 26 is a slit, 28 is a parallel plane mirror, 30 is a main prism, 32 is a zero adjuster, 34 is a lens, 36 is a photoconductive cell, 38 is a standard gas chamber, 40 Indicates the respective mixed gas chambers to be measured.

  The optical interferometer unit 20 itself shown in FIG. 2 is a known device, and when light passes through the gas, a delay occurs in proportion to the refractive index / concentration of each gas, and the amount of the delayed light. It is intended to measure the gas concentration by measuring. As a method for measuring the amount of delay of light, a known principle of optical interference is used.

  As the light source 22, a tungsten lamp, a visible light emitting diode, or the like is used. Note that the light source 22 has an explosion-proof structure as an intrinsically safe electric device.

The operation principle of the optical interferometer unit 20 is as follows. The light beam output from the light source 22 is converted into a parallel light beam by the lens 24, hits the parallel plane mirror 28 at the point A through the slit 26, and is refracted with two light beams (that is, the light beam P ₁ reflected on the surface of the parallel plane mirror 28). The light beam P ₂ ) is reflected by the back surface of the parallel plane mirror 28. The light ray P ₁ follows the path of point A, point B, point C, point D, and point E, and the light ray P ₂ corresponds to point A, point B ′, point C ′, point D ′, and point E ′. Following the path, both rays P ₁ and P ₂ reach point F. Since there is a slight difference in distance between the optical paths of the two rays that are again coincident with each other, light interference occurs at the point F to form interference fringes of light waves. On the other hand, when the measured mixed gas chamber 40 is disposed in the optical path of the light beam P ₁ and the standard gas chamber 38 is disposed in the optical path of the light beam P ₂ , the interference fringes are expressed in accordance with the refractive index difference between air and the measured mixed gas. It moves according to the concentration (volume) of the gas mixture to be measured. By measuring the amount of movement, the concentration of the mixed gas to be measured can be obtained.

  Next, the catalyst unit 50 that characterizes the hydrogen gas and / or lower hydrocarbon gas concentration measuring device 10 of the present invention will be described. The catalyst unit 50 includes a catalyst housing portion 52 that houses a predetermined catalyst, and a heating means 54 for heating the catalyst to a predetermined temperature.

  The catalyst accommodated in the catalyst accommodating portion 52 is preferably at least one metal selected from the group consisting of platinum, palladium, iridium, ruthenium, gold, rhenium, nickel, cobalt, and iron. As the catalyst carrier, activated carbon, carbon nanotubes, molecular sieve, zeolite, alumina, silica, titanium oxide, zirconium oxide, or cerium oxide is used. The heating means 54 may be a known means such as a heater.

  In FIG. 1, 60 is a first pipe for supplying the mixed gas to the standard gas chamber 38, 62 is a mass flow for controlling the flow rate of the gas to be measured, and 64 is a mass flow for controlling the flow rate of the air. , 66 is a second pipe for supplying the mixed gas from the standard gas chamber 38 to the measured mixed gas chamber 40 via the first electromagnetic valve 68 and the second electromagnetic valve 70, and 72 is the mixed gas to be measured. A third pipe for discharging from the chamber 40, 74 is a fourth pipe for supplying the mixed gas from the first electromagnetic valve 68 to the catalyst housing portion 52, and 76 is a second electromagnetic wave from the catalyst housing portion 52. Each of the fifth lines for supplying the valve 70 is shown. Reference numeral 60a denotes an inlet valve of the standard gas chamber 38, 66a denotes an outlet valve of the standard gas chamber 38, 66b denotes an inlet valve of the measured mixed gas chamber 40, and 72a denotes an outlet valve of the measured mixed gas chamber 40.

The operation of the hydrogen gas and / or lower hydrocarbon gas concentration measuring apparatus 10 configured as described above will be described. First, as a first stage, zero point correction is performed.
(First stage-zero point correction)
A standard gas chamber is formed by mixing a gas mixture (hereinafter referred to as “sample gas”) to be measured with a certain amount of air (hereinafter simply referred to as “gas”) via a first pipe 60 having an inlet valve 60a opened. 38. During mixing, the flow rates of the sample gas and air are controlled by the mass flows 62 and 64. Next, with the first solenoid valve 68 and the second solenoid valve 70 closed so that the gas does not flow to the catalyst unit 50 but directly to the measured mixed gas chamber 40, the outlet valve 66a of the standard gas chamber 38 and the measured The inlet valve 66b of the mixed gas chamber 40 is opened, and the gas is supplied to the mixed gas chamber 40 to be measured through the second pipe 66 (in FIG. 1, the flow of gas at the time of zero point correction is shown by a white arrow. Have been). In this way, the optical interferometer unit 20 is operated in a state where the standard gas chamber 38 and the measured mixed gas chamber 40 are filled with gas, and the zero point correction is performed by adjusting the amount of movement of the interference fringes ( By performing the zero point correction, if the gas in the standard gas chamber 38 and the gas in the measured mixed gas chamber 40 are the same, the interference fringes will not move).

(Second stage)
A gas in which a sample gas and a certain amount of air are mixed is supplied to the standard gas chamber 38 via the first pipe line 60 having the inlet valve 60a opened. Next, the outlet valve 66a of the standard gas chamber 38 is opened with the first solenoid valve 68 and the second solenoid valve 70 opened so that the gas flows to the catalyst unit 50, and the second pipe line 66 and the fourth pipe line are opened. The gas is supplied to the catalyst housing portion 52 through 74. At that time, the heating means 54 is operated so that the catalyst is maintained at about 0 ° C. to about 50 ° C. Then, the gas passing through the catalyst housing 52 reacts to consume hydrogen gas. The gas in which the hydrogen gas has been consumed is supplied to the mixed gas chamber to be measured 40 via the fifth pipe 76 and the second pipe 66 (in FIG. 1, the gas flow is indicated by black arrows). The same applies to the third stage and the fourth stage described below). In this way, the optical interferometer unit 20 is operated in a state where the standard gas chamber 38 and the measured mixed gas chamber 40 are filled with gas, and the amount of movement of the interference fringes is measured (in the standard gas chamber 38). The gas and the gas in the mixed gas chamber 40 to be measured are no longer the same), and the concentration of hydrogen gas in the mixed gas is obtained using a calibration curve.

(3rd stage)
A gas in which a sample gas and a certain amount of air are mixed is supplied to the standard gas chamber 38 via the first pipe line 60 having the inlet valve 60a opened. Next, the outlet valve 66a of the standard gas chamber 38 is opened with the first solenoid valve 68 and the second solenoid valve 70 opened so that the gas flows to the catalyst unit 50, and the second pipe line 66 and the fourth pipe line are opened. The gas is supplied to the catalyst housing portion 52 through 74. At that time, the heating means 54 is operated to keep the catalyst at about 100 ° C. to about 200 ° C. Then, the gas passing through the catalyst housing 52 reacts to consume hydrogen gas and lower hydrocarbon gas (excluding methane gas). The gas in which the hydrogen gas and the lower hydrocarbon gas (excluding methane gas) have been consumed is supplied to the measured mixed gas chamber 40 via the fifth pipe 76 and the second pipe 66. In this way, the optical interferometer unit 20 is operated in a state where the standard gas chamber 38 and the measured mixed gas chamber 40 are filled with gas, the amount of movement of the interference fringes is measured, and the calibration curve is used. The concentration of hydrogen gas and lower hydrocarbon gas (excluding methane gas) in the mixed gas is determined. Then, by subtracting the concentration of the hydrogen gas determined in the second stage from the concentration of the hydrogen gas and the lower hydrocarbon gas (excluding methane gas) determined in this way, E) The concentration of the lower hydrocarbon gas is required.

(Fourth stage)
A gas in which a sample gas and a certain amount of air are mixed is supplied to the standard gas chamber 38 via the first pipe line 60 having the inlet valve 60a opened. Next, the outlet valve 66a of the standard gas chamber 38 is opened with the first solenoid valve 68 and the second solenoid valve 70 opened so that the gas flows to the catalyst unit 50, and the second pipe line 66 and the fourth pipe line are opened. The gas is supplied to the catalyst housing portion 52 through 74. At that time, the heating means 54 is operated so that the catalyst is maintained at about 250 ° C. to about 350 ° C. Then, the gas passing through the catalyst housing 52 reacts to consume hydrogen gas, lower hydrocarbon gas (excluding methane gas), and methane gas. Hydrogen gas, lower hydrocarbon gas (excluding methane gas), and gas in which methane gas is consumed are supplied to the mixed gas chamber 40 to be measured through the fifth pipe 76 and the second pipe 66. In this way, the optical interferometer unit 20 is operated in a state where the standard gas chamber 38 and the measured mixed gas chamber 40 are filled with gas, the amount of movement of the interference fringes is measured, and the calibration curve is used. Determine the concentrations of hydrogen gas, lower hydrocarbon gas (excluding methane gas), and methane gas in the mixed gas. From the hydrogen gas thus obtained, the lower hydrocarbon gas (excluding methane gas), and the concentration of methane gas, the hydrogen gas obtained in the third stage and the lower hydrocarbon gas (excluding methane gas) By subtracting the concentration, the concentration of methane gas in the mixed gas is obtained.

The sample gas (6.2 ml / min) containing methane and hydrogen is mixed with air (31.2 ml / min) and supplied to the standard gas chamber 38 via the first line 60, and then the second line 66 To the measured mixed gas chamber 40 to correct the zero point of the optical interferometer unit 20. Next, a gas obtained by mixing air with the above sample gas is passed through a catalyst maintained at 25 ° C. (1.0 g of a 2% fixed amount supported platinum catalyst using activated carbon as a carrier), and then the gas passed through the catalyst is passed through. The mixed gas chamber 40 to be measured was supplied. Then, the optical interferometer unit 20 was operated to measure the amount of movement of the interference fringes, and the concentration of hydrogen gas in the sample gas was determined using a calibration curve. The results are as shown in Table 1. From Table 1, it was confirmed that the concentration of hydrogen gas in the sample gas was obtained accurately.

Using a sample gas containing methane, hydrogen, N ₂ , and propane having different compositions, the catalyst temperature was maintained at 25 ° C. and the hydrogen gas concentration was measured in the same manner as in Example 1. Next, the catalyst temperature was heated to 100 ° C., and the concentrations of hydrogen gas, propane gas, and methane gas were measured in the same manner as in Example 1. Table 2 shows the concentrations of hydrogen gas, propane gas, and methane gas that were actually measured when mixed gas sample gases having different compositions were used. Example 1 and Example 2 demonstrated that the apparatus and method according to the present invention can measure the concentrations of hydrogen gas, propane gas, and methane gas in a mixed gas.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say, it is something.

  Further, for example, an optical interferometer unit of a type other than the optical interferometer unit 20 described in the above embodiment may be used.

  Further, in the form shown in FIG. 1 and FIG. 2, the mixed gas chamber 40 to be measured is arranged around the standard gas chamber 38, but the arrangement of both gas chambers is a form other than the form shown ( For example, a standard gas chamber may be arranged around the gas chamber to be measured.

1 is a schematic overall view of a hydrogen gas and / or lower hydrocarbon gas concentration measuring device according to a preferred embodiment of the present invention. FIG. 2 is a schematic overall view showing an optical interferometer unit of the hydrogen gas and / or lower hydrocarbon gas concentration measuring device of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydrogen gas and / or lower hydrocarbon gas density | concentration measuring apparatus 20 Optical interferometer unit 22 Light source 28 Parallel plane mirror 30 Main prism 32 Zero point adjuster 36 Photoconductive cell 38 Standard gas chamber 40 Measurement mixed gas chamber 50 Catalyst unit 52 Catalyst Container 54 Heating means 68, 70 Solenoid valve 60, 66, 72, 74, 76 Pipe line

Claims (8)

An apparatus for measuring the concentration of hydrogen gas and / or lower hydrocarbon gas in a mixed gas, comprising an optical interferometer unit, which splits a light beam from a light source into two light beams Means for passing one of the divided light beams through a standard gas chamber, and passing the other of the divided light beams through a mixed gas chamber to be measured in which a mixed gas to be measured is sealed; and In an apparatus comprising means for superimposing two light beams on one light beam and means for determining a gas concentration by measuring interference fringes generated when the light beams are superimposed on the one light beam,
A catalyst unit, and the catalyst unit includes a catalyst storage unit that stores a predetermined catalyst, and a heating unit that heats the catalyst in the catalyst storage unit to a predetermined temperature.
By passing the measured mixed gas through a catalyst heated to a predetermined temperature, hydrogen gas or hydrogen gas and lower hydrocarbon gas in the mixed gas is consumed in the reaction with the catalyst at the predetermined temperature, thereby the hydrogen An apparatus configured to measure the concentration of gas and / or lower hydrocarbon gas. The apparatus according to claim 1, wherein the predetermined temperature is any one of 0 ° C to 50 ° C, 100 ° C to 200 ° C, or 250 ° C to 350 ° C. 3. The catalyst according to claim 1, wherein the catalyst is at least one metal selected from the group consisting of platinum, palladium, iridium, ruthenium, gold, rhenium, nickel, cobalt, and iron. apparatus. The catalyst carrier is any one of activated carbon, carbon nanotube, molecular sieve, zeolite, alumina, silica, titanium oxide, zirconium oxide, or cerium oxide. The device described. A method for measuring the concentration of hydrogen gas and / or lower hydrocarbon gas in a mixed gas, the step of splitting a light beam from a light source into two light beams using an optical interferometer unit, Passing one of the light beams through the standard gas chamber and passing the other of the divided light beams through the mixed gas chamber to be measured in which the mixed gas to be measured is sealed, and passing the two light beams into one light beam. And determining the gas concentration by measuring interference fringes produced when superimposing on the one light beam,
By passing the measured mixed gas through a catalyst heated to a predetermined temperature, hydrogen gas or hydrogen gas and lower hydrocarbon gas in the mixed gas is consumed in the reaction with the catalyst at the predetermined temperature, and thus A method comprising: measuring an interference fringe using the optical interferometer unit after supplying the obtained gas to a mixed gas chamber to be measured. The method according to claim 5, wherein the predetermined temperature is any one of 0 ° C. to 50 ° C., 100 ° C. to 200 ° C., or 250 ° C. to 350 ° C. The catalyst according to claim 5 or 6, wherein the catalyst is at least one metal selected from the group consisting of platinum, palladium, iridium, ruthenium, gold, rhenium, nickel, cobalt, and iron. Method. The catalyst carrier is any one of activated carbon, carbon nanotube, molecular sieve, zeolite, alumina, silica, titanium oxide, zirconium oxide, or cerium oxide. The method described.

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