JP7117009B2 - GAS MEASURING DEVICE, GAS MEASURING METHOD AND PROGRAM - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law On June 20, 2019, Yabegawa Electric Industry Co., Ltd. published at Tokyo Gas Co., Ltd. Applied Technology Research Institute.

The present invention relates to a gas measurement device, a gas analysis system, a gas measurement method, a gas analysis method and a program, and more particularly to a gas measurement device and the like for measuring impurities in gas.

In recent years, there has been an increasing need to provide good-quality hydrogen gas for the practical use of fuel cells. An example of impurity concentration monitoring in a hydrogen station will be described with reference to FIG. FIG. 10 is a flow diagram showing an example of the flow from production to supply of hydrogen fuel. First, city gas or LPG is supplied to the hydrogen production device 101 at a low pressure such as 0.6 MPa. Hydrogen gas produced by the hydrogen production device 101 is supplied to the compressor 103 . At this time, a gas measuring device 105 is connected to the supply line from the hydrogen production device 101 to the compressor 103 to monitor the impurity concentration. Subsequently, the hydrogen gas pressurized to a high pressure such as 87.5 MPa by the compressor 103 is supplied to the pressure accumulator 107 . The hydrogen gas connected to the inspection low-pressure pipe before being supplied from the pressure accumulator 107 to the dispenser 111 is connected to the gas measuring device 109 to monitor the impurity concentration. Finally, hydrogen gas is supplied from the dispenser 111 to the fuel cell vehicle 113 and consumed.

In addition to the above-described on-site supply, the supply route to the compressor 103 may be an off-site supply. In this case, the hydrogen cardle is transported by a hydrogen trailer, and the hydrogen in the hydrogen cardle compressed to 14.7 MPa to 45 MPa is supplied to the compressor 103 . Same as onsite supply except as noted here.

The inventor of the present application has developed a protection device for fuel cells, a temperature/humidity adjustment device, a fluid transfer device, and the like (Patent Documents 1 to 3).

Also, a gas chromatography apparatus that continuously analyzes a sample gas by gas chromatography has been known (Patent Document 4). Furthermore, a sensor cell that monitors various impurities in fuel hydrogen with a single sensor cell has been known (Patent Document 5).

JP 2018-092786 A JP 2016-039139 A JP 2014-177892 A JP-A-2002-181798 Japanese Patent No. 5597004

However, no device has been provided that can continuously measure hydrogen sulfide gas (H2S) with high accuracy. Here, the measurement cell will be destroyed if only 4 ppb of hydrogen sulfide gas is mixed. If the hydrogen sulfide gas could not be measured continuously, it would not be possible to immediately detect the contamination of the hydrogen sulfide gas, and the measurement cell could not be sufficiently protected. As a result, 10 ppb of hydrogen sulfide gas was mixed in, resulting in the shutdown of all hydrogen stations.

The device described in Patent Document 5 can be said to be advantageous in terms of high accuracy, but there is room for improvement in that impurities accumulate in a short period of time and the life of the measurement cell ends in about three days.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a gas measuring device or the like that continuously measures impurities and has a measuring cell with a long life.

A first aspect of the present invention is a gas measuring device for measuring impurities in a gas, comprising: an electrolyte membrane impervious to the impurities; a channel for sending the gas to the electrolyte membrane; a power supply that applies a power supply, a power supply control unit that controls the power supply, a voltmeter that measures the voltage applied to the electrolyte membrane, and an ammeter that measures the current flowing through the electrolyte membrane, wherein the power supply control unit is a gas measurement device that controls the power supply to apply an alternating voltage to the electrolyte membrane.

A second aspect of the present invention is the gas measurement device according to the first aspect, wherein the power source uses a sine wave as the AC voltage.

A third aspect of the present invention is the gas measurement device according to the first or second aspect, wherein a part of the flow channel is a tubular water vapor imparting flow channel whose walls are made of an ion exchange resin, A steam generator for generating steam is further provided around the steam imparting channel, and humidity is imparted to the gas in the steam imparting channel through the wall of the steam imparting channel.

A fourth aspect of the present invention is the gas measuring device according to the third aspect, wherein the ion exchange resin is Nafion.

A fifth aspect of the present invention is the gas measuring device according to the third or fourth aspect, wherein the water vapor generating section is provided with a water vapor atmosphere of 30°C or higher and 50°C or lower with respect to the water vapor imparting flow path. generate

A sixth aspect of the present invention is the gas measuring device according to any one of the first to fifth aspects, wherein a pair of catalyst layers sandwiching the electrolyte membrane and the electrolyte membrane and the pair of catalyst layers are stabilized. a pair of wire meshes sandwiching the pair of catalyst layers; a plurality of bar-shaped current collecting electrodes sandwiching the wire meshes, one end of which is a connector portion for outputting a signal; a holding supporter holding the end opposite to the one end of the plurality of current collecting electrodes; and a fixed supporter for fixedly holding.

A seventh aspect of the present invention is a gas analysis system for measuring and analyzing impurities in a gas, comprising: the gas measuring device according to any one of the first to fifth aspects; an analysis unit for analyzing results, wherein the analysis unit analyzes a first impurity and a second impurity as the plurality of impurities, and a second parameter based on the impurity concentration of the second impurity is set to the first impurity. A gas analysis system having a conversion unit for converting into a first parameter based on an impurity concentration of an impurity.

An eighth aspect of the present invention is the gas analysis system according to the seventh aspect, wherein the power supply applies the AC voltage so as to cause a current of constant amplitude to flow through the electrolyte membrane, and the conversion calculates the impurity concentration when converted to the first impurity from the increase value of the AC voltage based on the impurity concentration of the second impurity.

A ninth aspect of the present invention is a gas measuring method using a gas measuring device for measuring impurities in a gas, wherein the gas measuring device comprises an electrolyte membrane impermeable to the impurities, A power source for applying a voltage to the electrolyte membrane, and a power control section for controlling the power source, wherein the power control section controls the power source to apply an alternating voltage to the electrolyte membrane. It is a gas measurement method including an alternating current application step to apply.

A tenth aspect of the present invention is a gas analysis method using a gas measuring device for measuring impurities in a gas, wherein the gas measuring device comprises an electrolyte membrane impervious to the impurities, a flow path for feeding to a membrane, a power source for applying a voltage to the electrolyte membrane, a power control section for controlling the power source, and an analysis section for analyzing a first impurity and a second impurity as the plurality of impurities, an alternating voltage applying step in which the power supply control unit controls the power supply to apply an alternating voltage to the electrolyte membrane; A gas analysis method including a conversion step of converting to a concentration-based first parameter.

An eleventh aspect of the present invention is a program for causing a computer to function as the power control section of the ninth or tenth aspect or the analysis section of the tenth aspect.

According to each aspect of the present invention, it is possible to extend the life of the measurement cell by delaying deterioration of the electrolyte membrane in the measurement cell due to impurities such as carbon monoxide in the gas. Therefore, it is possible to continuously measure impurities and provide a gas measuring device or the like having a measuring cell with a long life. The present inventors have confirmed through experiments that the life can be extended by 100 times or more compared to the conventional method using direct current.

Moreover, according to the second aspect of the present invention, in the gas measuring device according to the present invention, it becomes easier to obtain stable data as compared with the case of applying an alternating current with another waveform.

Here, in the gas measuring device according to the present invention, it is necessary for measurement to stably supply constant humidity such as 80% to the electrolyte membrane. According to the third and fourth aspects of the present invention, it is possible to supply the gas with stable humidity in a state in which dew condensation is difficult to occur by providing the gas with water vapor having fine particle diameters.

Furthermore, according to the fifth aspect of the present invention, by supplying water vapor vaporized at a relatively low temperature to the water vapor supply channel, water vapor having a fine particle size is provided, and stable humidity is maintained in a state where condensation is difficult to occur. It becomes easier to supply to

Further, according to the sixth aspect of the present invention, uniform contact between the sensor and the electrode can be achieved while stabilizing the contact area between the sensor and the gas to be measured, so that stable signal acquisition is possible. Therefore, it becomes easy to simultaneously improve both the sensitivity of the sensor and the stability of signal acquisition.

Furthermore, according to the seventh or eighth aspect of the present invention, it is possible to evaluate the influence of deterioration on the measurement cell due to different types of impurity concentrations using a common index. Therefore, it becomes easy to evaluate the lifetime of the measurement cell and the effect on the lifetime.

It is a figure which shows the display example by (a) an individual display method and (b) collective display method of the gas measurement result by the gas measuring device 1 which concerns on a present Example. FIG. 4 is a diagram showing the necessity of continuous measurement of the hydrogen supply line; 1 is a block diagram showing an example of an overview of the configuration of a gas analysis system 1; FIG. 2 is a diagram showing an example of a piping system of the gas analysis system 1; FIG. It is a figure explaining the principle of a hydrogen pump type cell. FIG. 4 is a diagram showing an example of a sensor holder that holds detection cells 15. FIG. 4 is a diagram showing an example of analysis results using the gas analysis system 1; FIG. 5 is a graph showing an example of changes over time such as output voltage for about five days when a DC voltage is applied to the detection cell 15. FIG. 4 is a graph showing an example of changes over time such as output voltage for about 27 days when an AC voltage is applied to the detection cell 15. FIG. FIG. 2 is a flow diagram showing an example of the flow from production to supply of hydrogen fuel.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, embodiment of this invention is not limited to the following examples.

An outline of the gas analysis system 1 (which is an example of the "gas analysis system" described in the claims of the present application) according to the present embodiment will be described. The gas analysis system 1 collectively detects a plurality of poisoning substances such as carbon monoxide (CO) in hydrogen fuel (an example of the "impurities" described in the claims of the present application) that cause performance deterioration of fuel cell vehicles. It is an analysis system that monitors quality continuously in real time.

In the first place, if there are multiple impurity components, it is necessary to arrange and monitor the sensors corresponding to the number. However, a highly sensitive sensor capable of selective identification has not been put into practical use. Therefore, a plurality of measuring devices were required.

On the other hand, the hydrogen pump type cell 3 of the gas analysis system 1 can detect at least carbon monoxide and hydrogen sulfide in one cell.

Also, collective display will be described with reference to FIG. FIG. 1 is a diagram showing a display example of a gas analysis result by the gas analysis system 1. As shown in FIG. The gas analysis system 1 only separately displays a plurality of impurities such as carbon monoxide (an example of the "first impurity" in the claims of the present application) and hydrogen sulfide (an example of the "second impurity" in the claims of the present application). It is also possible to collectively display CO conversion instead. Moreover, impurities other than the calibration gas can also be measured and displayed. As a result, as shown in FIG. 1(a), in addition to individually displaying only expected impurities, unexpected impurities can also be individually displayed. Moreover, as shown in Fig. 1(b), it is possible to collectively display the degree of impurity contamination based on a single CO conversion standard, such as the increase in resistance value and voltage increase when CO contacts the catalyst layer. is. Here, in order to obtain the CO conversion value, for example, it is obtained by referring to the indicated value when measuring gases other than CO with an instrument calibrated with a CO standard cylinder. For example, when 100 ppb of H ₂ S was passed through a meter calibrated at 200 ppb of CO, the reading of the meter was 200 ppb. In this case, the CO conversion value of H ₂ S100ppb is CO200ppb. Furthermore, considering that the conversion value of H ₂ S converted to CO is proportional to H 2 S 1 ppb, CO ₂ ppb may be used, or another relational expression may be used.

Next, with reference to FIG. 2, the need for continuous measurement will be described. FIG. 2 is a diagram showing the necessity of continuous measurement of the hydrogen supply line. Conventionally, there was no measuring instrument for continuously measuring impurities in hydrogen gas, and sampling inspections were performed. However, as shown in FIG. 2, when the hydrogen gas mixed with the impurity gas is temporarily supplied, the hydrogen gas without the impurity gas is then supplied to the line. Therefore, in the sampling inspection, the contamination of the impurity gas is detected only when the timing of the contamination and the timing of the inspection match. On the other hand, if the timing of mixing does not match the timing of inspection, the mixing of the impurity gas will be overlooked. On the other hand, in the case of continuous measurement (continuous inspection), since inspection is always performed, it is possible to detect impurities at any timing. Continuous measurement enables early detection of abnormal values due to contamination by impurities, verification by gas chromatography, etc., and implementation of countermeasures.

When performing continuous measurement with the gas analysis system 1, it is necessary to constantly supply the sample gas and the zero gas. Conventionally, there is a gas chromatograph as an impurity measurement device, but a large amount of carrier gas such as 3 L/min is required to separate a sample with a column. However, since the gas analysis system 1 does not use a gas chromatograph, it does not use such a large amount of carrier gas. In addition, while the conventional analysis system requires an analysis system for each impurity component, the gas analysis system 1 can analyze a plurality of impurities with a single unit by using a detection cell to be described later. . Therefore, the amount of gas required is 1/30 of the flow rate of a general measuring device, and the running cost can be reduced.

Next, the configuration of the gas analysis system 1 will be described with reference to FIG. FIG. 3 is a block diagram showing an example of an overview of the configuration of the gas analysis system 1. As shown in FIG. The gas analysis system 1 includes a gas measurement device 3 (an example of the "gas measurement device" in the claims of the present application), an electronic cooler 5, and an analysis section 7 (an example of the "analysis section" in the claims of the present application). , and an uninterruptible device 9 . The gas measurement device 3 includes a hydrogen fuel supply unit 11, a humidifier 13 (which is an example of the "steam generation unit" described in the claims of the present application), a detection cell 15, a discharge unit 17, a flow path 19, It includes a flow rate adjusting section 21 , a power adjusting section 23 , a cell power source 25 , a display section 27 and a control section 29 . The humidifier 13 has a water vapor imparting flow path 31 (an example of the "water vapor imparting flow path" described in the claims of the present application). The control unit 29 includes a gas flow control unit 33, a humidifier temperature control unit 35, a flow path temperature control unit 37, and a power supply control unit 39 (which is an example of the "power supply control unit" described in the claims of the present application). , a cell temperature controller 41 and a cell humidity controller 43 . The analysis unit 7 has a conversion unit 45 (an example of a "conversion unit" in the claims of the present application).

The gas measuring device 3 measures the concentration of impurities in the hydrogen fuel to be analyzed. Electronic cooler 5 regulates the temperature of gas analysis system 1 . The analysis unit 7 acquires and analyzes the measurement result of the gas measuring device 3 . The uninterruptible device 9 has a battery, and supplies power to the gas measuring device or the like in the event of a power failure such as when power is not normally supplied from the power source due to a power failure or the like. The hydrogen fuel supply unit 11 supplies hydrogen fuel. The humidifier 13 humidifies the hydrogen fuel by giving steam to the hydrogen fuel in the steam giving channel. The detection cell 15 detects impurities in the hydrogen fuel and outputs them as changes in voltage. The discharge unit 17 discharges hydrogen fuel and water droplets after measurement. Hydrogen fuel passes through a channel 19 (which is an example of a “channel” described in the claims of the present application) from the hydrogen fuel supply unit 11 to the discharge unit 17 . The flow rate adjusting section 21 adjusts the flow rate of the hydrogen fuel supplied from the hydrogen fuel supplying section 11 to the flow path 19 . The power adjuster 23 adjusts the power, particularly the voltage, applied to the detection cell 15 . A cell power supply 25 (which is an example of a “power supply” described in the claims) applies a voltage to the detection cell 15 . The display unit 27 displays the analysis result of the gas analysis system 1 and/or the measurement result of the gas measuring device 3 to the user.

The control unit 29 controls each parameter of the gas measuring device. The gas flow rate control unit 33 controls the hydrogen fuel supply unit 11 to adjust the flow rate of the supplied hydrogen fuel. The flow channel temperature control unit 37 controls the temperature of the flow channel 19, particularly the temperature of the flow channel between the humidifier 13 and the detection cell 15, to be kept higher than the temperature of the detection cell 15, for example. . Based on the measurement result of the current flowing through the detection cell 15, the power control unit 39 controls the power adjustment unit 23 to adjust the voltage applied to the detection cell 15 by the cell power supply 25 so that a constant current flows through the detection cell 15. adjust. The cell temperature control unit 41 adjusts the temperature of the detection cell 15 based on the measurement result so that the temperature is the same as or approximately the same as the temperature controlled by the humidifier temperature control unit 35, for example. The cell humidity control unit 43 controls the temperature of the humidifier 13 based on the humidity measurement result of the detection cell 15 to adjust the water vapor given to the water vapor giving channel 31 by the humidifier 13 .

The gas flow controller 33 periodically causes pure hydrogen fuel to flow through the flow path 19 . This eliminates the need for calibration by a professional analyst.

A steam supply channel 31 of the humidifier 13 is part of the channel 19 . When the humidifier 13 gives water vapor to the water vapor application channel 31, the water vapor application channel 31 and the water vapor application channel 19 positioned downstream thereof are humidified, and as a result, the detection cell 15 is humidified.

The conversion unit 45 of the analysis unit 7 compares the value of the voltage rise in the detection cell 15 due to impurities in the hydrogen fuel other than carbon monoxide with the value of the voltage rise in the detection cell 15 due to carbon monoxide. The concentration of impurities other than carbon monoxide is converted into the concentration of impurities in the case of carbon monoxide.

Next, the piping system of the gas analysis system 1 will be described with reference to FIG. FIG. 4 is a diagram showing an example of a piping system of the gas measuring device 1. As shown in FIG.

There is a hydrogen receiving device 63 in the middle of a hydrogen pipeline 62 that supplies hydrogen to the hydrogen fuel cells 61 ₁ to 61 _n . A sample hydrogen gas to be analyzed is supplied from the hydrogen receiving device 63 via the main valve 65 to the gas analysis system 1 housed in, for example, an outdoor cabinet. Sample hydrogen gas is supplied, for example, at 0.1 Mpa and 0.2 L/min. The line that supplies the sample hydrogen gas to the gas measuring device 3 branches into a line that enters the gas measuring device 3 via the valve 69 and the zero gas filter 71 and a line that enters the gas measuring device 3 via only the valve 73. ing. Also connected to the gas measuring device 3 is a line through which hydrogen gas mixed with 0.2 ppm of CO, for example, is supplied from a gas cylinder 75 containing a standard gas. The gas measuring device 3 is electrically connected via an uninterruptible device 9 to an electronic cooler 5, a data logger 77, and a power supply 67 (AC100V, 15A). The data logger 77 is, for example, a notebook computer with an analysis unit 7 .

By using the zero gas filter 71, it becomes possible to stabilize the zero adjustment and stabilize the measurement. In addition, it is possible to reduce the cost of preparing a pure hydrogen cylinder and the labor of replacing the cylinder.

Next, with reference to FIG. 5, a hydrogen pump type cell, which is an example of the detection cell 15 responsible for detecting impurities in the gas measuring device 1, will be described. FIG. 5 is a diagram for explaining the principle of the hydrogen pump type cell, and shows (a) the case where pure hydrogen gas is flowed and (b) the case where impurities such as CO are mixed in the hydrogen gas. The hydrogen pump type cell includes an electrolyte membrane 81 such as Nafion (registered trademark) (an example of the "electrolyte membrane" described in the claims of the present application), and a first catalyst layer 83 and a second catalyst layer 83 sandwiching the electrolyte membrane. It includes a catalyst layer 85 (which is an example of the “pair of catalyst layers” described in the claims of the present application), a cell power source (not shown), an ammeter 87 and a voltmeter 89 . The electrolyte membrane 81 allows hydrogen ions to pass through. The first catalyst layer 83 and the second catalyst layer 85 each have platinum as a material. When the first catalyst layer 83 exists on the positive electrode side of the electrolyte membrane 81, the platinum contained in the first catalyst layer 83 acts as a catalyst for the decomposition reaction that decomposes the hydrogen molecule into two hydrogen ions when it comes into contact with the hydrogen molecule. . The generated hydrogen ions pass through the electrolyte membrane 81 and reach the second catalyst layer 85 existing on the negative electrode side. The platinum included in the second catalyst layer 85 acts as a catalyst that binds two hydrogen ions to form a hydrogen molecule. A power supply applies a voltage between the first catalyst layer 83 , the electrolyte membrane 81 and the second catalyst layer 85 .

As shown in FIG. 5A, by controlling the voltage so that a constant current flows between the first catalyst layer 83, the electrolyte membrane 81, and the second catalyst layer 85, the voltage is kept constant. Here, as shown in FIG. 5B, when impurities such as carbon monoxide come into contact with the first catalyst layer 83, the contact of hydrogen molecules with the first catalyst layer 83 is inhibited, and the resistance value increases. Increase. In that case as well, the voltage value is increased because the voltage is controlled so that a constant current flows. This voltage rise makes it possible to detect the presence of impurities.

Conventionally, gas chromatography was used to detect impurities, but it required advanced knowledge. Since the hydrogen pump type cell is of a pump type, it can have a simple structure in which pure hydrogen gas with no impurities is first flowed to determine the zero point, and then the gas to be measured is flowed. Moreover, a stable zero point can be obtained.

Here, the above hydrogen pump type cell cannot be measured without humidification because the impedance is high and protons cannot move. In addition, the measured value of humidity becomes unstable unless it is controlled very precisely. Humidity control is the most important control for hydrogen gas analysis using a hydrogen pump cell, as high humidity (80%) prolongs the life of the cell, but dew condensation is likely to occur. In the gas measurement device 3, water vapor is applied to the sample gas in the water vapor application flow path 31 through the wall of Nafion, which is an ion exchange resin. By controlling the temperature with a Peltier element to 30° C. or higher and 50° C. or lower, more preferably 35° C. or higher and 40° C. or lower, and passing through the wall, water vapor having a small particle size can be applied. As a result, it is possible to stably control the humidity as high as 80.00% without condensation. Moreover, even if dew condensation occurs, it will soon evaporate.

When the power supply supplies a direct current to the detection cell 15, although the sensitivity is excellent, the cell needs to be replaced after about three days due to accumulation of impurities. On the other hand, when the power source applies an AC voltage to the detection cell 15, it was confirmed that sufficient measurement can be performed in an endurance test assuming one year or more.

In this embodiment, a sine wave is used as the waveform of the AC voltage applied to the detection cell 15 . A rectangular wave or a triangular wave may be used instead of the sine wave. The frequency of the alternating current may be determined in relation to the speed at which hydrogen ions pass through the electrolyte membrane, and may be any frequency that yields stable results.

Furthermore, referring to FIG. 6, a sensor holder that holds the detection cell 15 will be described. 6A and 6B are views showing an example of the sensor holder 151 developed by the present inventors, including (a) front view, (b) plan view, (c) bottom view, (d) right side view, and (e). It is a figure which shows the one part expansion reference view of a side view. Note that the rear view and left side view are omitted because they appear the same as the front view and right side view, respectively.

In the first place, the problem was how to fix the sensor that reacts to impurity gases such as CO in the atmosphere of hydrogen gas, install it in the gas to be measured, and extract the signal.

Conventionally, signals were acquired by fixing and installing by the following method. That is, the sensor is sandwiched by the force of a spring that also serves as an electrode, and is fixed with an insulator. Alternatively, the sensor is sandwiched between a fixed electrode and a screw electrode and fixed with an insulator. Alternatively, the sensor has been used with electrodes formed by vapor deposition or the like.

The function as a sensor could be confirmed by any of the above methods. However, the contact resistance changes depending on the degree of tightening of the screws, and it is necessary to adjust the force when pinching and the position of picking up the signal with high accuracy. The data also fluctuated due to vibration and temperature changes. From this point of view, there has been a need for a sensor storage device that can provide stable performance regardless of who manufactures it and that can be operated as simply as possible. Therefore, the inventors of the present invention developed and provided a sensor holder or the like that provides stable sensor performance.

Such a sensor holder is based on the following conditions. The sensor held by the sensor holder has a Nafion membrane and catalyst layers sandwiching the Nafion membrane. It functions as a sensor based on a change in resistance when the gas to be measured flowing on the surface of the catalyst layer comes into contact with the catalyst layer. Therefore, in order to increase the sensitivity as a sensor, it is preferable that as much gas as possible can come into contact with the surface of the catalyst layer.

On the other hand, it is necessary to arrange electrodes on the surface of the catalyst layer in order to externally supply a driving power source to the sensor and/or extract a signal. The catalyst layer may also serve as an electrode. Here, in order to stably acquire a signal, it is preferable that as many areas of the catalyst layer as possible are electrodes.

Therefore, it is necessary to find a compromise that satisfies contradictory requirements as much as possible between the viewpoint of sensor sensitivity and the viewpoint of extraction of output signals.

Referring to FIG. 6, a sensor holder 151 includes a plurality of rod-shaped collector electrodes 153 (an example of a "collector electrode" in the claims of the present application) and a holding supporter 155 (an example of the "holding supporter" in the claims of the present application). , a fixed supporter 157 (an example of a “fixed supporter” in the claims of the present application), a connector portion 159 (an example of the “connector portion” in the claims of the present application), and a wire mesh 161 . A sensor holder 151 holds the detection cell 15 . The detection cell 15 has a Nafion membrane 81 and a first catalyst layer 83 and a second catalyst layer 85 with the Nafion membrane 81 interposed therebetween. As shown in FIG. 6, the sensor holder 151 has eight collector electrodes 153 of 4×2 rows. The collector electrode 153 is plated with gold, holds the detection cell 15 and acquires a signal output from the detection cell 15 . The holding supporter 155 is made of resin, and holds the detection cells 15 and a pair of wire meshes 161 (an example of the “pair of wire meshes” described in the claims of the present application) between the two rows of collector electrodes 153 . The fixed supporter 157 is made of resin and holds the collector electrode 153 between the holding supporter 155 and the connector portion 159 . Moreover, the fixed supporter 157 holds the plurality of collector electrodes 153 so as to fix the distance between the plurality of collector electrodes 153 . The connector part 159 is one end of the collector electrode 153 or is connected to one end of the collector electrode 153, and outputs a signal acquired by the collector electrode 153 to the outside. The wire mesh 161 has at least a surface made of metal such as gold or platinum, and has a net-like structure. Also, the wire meshes 161 are paired so as to sandwich the first catalyst layer and the second catalyst layer 85 .

The wire mesh 161 is in contact with the entire surfaces of the first catalyst layer 83 and the second catalyst layer 85 at regular intervals, thereby enabling stable signal acquisition. Moreover, the gaps between the wire meshes 161 secure areas where the gas to be measured contacts the first catalyst layer 83 and the second catalyst layer 85 . Therefore, the sensor holder 151 can achieve both sensor sensitivity and output signal extraction. In addition, since the holding supporter 155 and the fixing supporter 157 firmly fix the rod-shaped collector electrode 153, a stable output signal can be obtained, and the connector portion at one end of the collector electrode 153 and the outside can be stably electrically connected. easy to connect to.

The sensor holder 151 makes it possible to stabilize the contact area between the sensor and the gas to be measured. Moreover, since uniform contact between the sensor and the electrode can be achieved, stable signal acquisition is possible. Furthermore, since the assembling work of the sensor holder 151 and the assembling work of the detection cell 15 are simplified, there is no human error or assembling error, and the manufacturing accuracy of the sensor holder 151 is improved. Also, the sensor holder 151 is stable against temperature changes. Furthermore, since the gas flows without resistance in the piping installed with the smart sensor holder, measurement errors due to residual gas to be measured are reduced. As a result, it contributes to improvement of the gas measuring device 3 .

Next, with reference to FIG. 7, analysis results using the gas analysis system 1 will be described. FIG. 7 is a diagram showing an example of analysis results using the gas analysis system 1. FIG.

In order to confirm the accuracy of the gas analysis system 1, hydrogen gas mixed with various concentrations of CO was measured from a gas cylinder 75 with a CO concentration of 490 ppb using a control valve connected to the gas cylinder 75 . During the measurement time of about 2 hours, the impurity concentration of CO was changed from 490ppb→400ppb→300ppb→200ppb→100ppb→0ppb→100ppb→200ppb→300ppb→400ppb→490ppb. As shown in the measurement results in FIG. 7, highly accurate analysis results of CO concentration were obtained as 491 ppb→399 ppb→294 ppb→193 ppb→94 ppb→0.0 ppb→96 ppb→191 ppb→290 ppb→393 ppb→494 ppb. The CO sensor voltage [mV] during this period was stable at about 352mV.

Next, with reference to FIGS. 8 and 9, it will be shown that application of an AC voltage to the detection cell dramatically extends the life of the detection cell. FIG. 8 is a graph showing an example of temporal changes in the output voltage, etc. for about five days when a DC voltage is applied to the detection cell 15 . FIG. 9 is a graph showing an example of temporal changes in (a) output voltage, (b) humidity of the detection cell 15, and (c) temperature of the humidifier 13 for about 27 days when an AC voltage is applied to the detection cell 15. is.

In FIG. 8, the horizontal axis is time, and the vertical axis is the output voltage [mV], current [mA] when a DC voltage is applied to the detection cell 15, the rate of change of the output voltage [mV], and the hydrogen flow rate [ml/min]. ], drying flow rate [ml/min], temperature of the detection cell 15 [° C.], and humidity of the detection cell 15 [%RH]. In particular, the output voltage of the detection cell 15 overflowed in about 2.5 days, after which the detection cell 15 stopped functioning. For a detection cell that is expected to be used all year round, such a short replacement period would be impractical.

As shown in FIG. 9(a), when an AC voltage was applied to the detection cell 15, the output voltage increased by only 56 [mV] in 27 days, an average increase of just over 2 mV per day. . Therefore, it is expected to be used for at least one year until the upper limit of 1000 [mV] is reached. In addition, when the output voltage exceeds 500mV, the increase in output voltage tends to be less than 1mV on average per day. Therefore, by applying an AC voltage to the detection cell 15, it is possible to provide a practical gas analysis system.

Furthermore, it is important for the detection cell 15 to keep the humidity stable at a high level for highly accurate detection. As shown in FIG. 9(b), it was possible to control the temperature of the humidifier 13 at 37±0.1° C. for 27 days. Further, as shown in FIG. 9(c), the humidity in the detection cell 15 could be maintained with high accuracy of 70%±0.1% for 27 days. FIGS. 9B and 9C show that the humidity of the detection cell 15 is controlled with high accuracy as a result of the temperature of the humidifier 13 being controlled with high accuracy.

By using the gas analysis system 1, the impurity concentration can be confirmed without requiring a specialized analyst unlike the conventional apparatus. Therefore, with the advent of the hydrogen society approaching, users who have not necessarily received specialized training can use the gas analysis system 1 at many sites. Also, when an abnormal value is detected by the hydrogen analysis system 1, it is possible to carry out quality control of the hydrogen fuel by performing early detection and total component analysis by using it together with gas chromatography or the like.

1; gas analysis system, 3; gas measuring device, 7; analysis unit, 13; humidifier, 15; detection cell, 23; power adjustment unit, 25; 37; flow path temperature control unit, 39; power supply control unit, 41; cell temperature control unit, 43; cell humidity control unit, 45; conversion unit, 81; layer, 87; ammeter, 89; voltmeter, 151; sensor holder

Claims (11)

A gas measuring device for measuring impurities in a gas,
an electrolyte membrane impervious to said impurities;
a pair of catalyst layers sandwiching the electrolyte membrane;
a channel for sending the gas to the electrolyte membrane;
electric source and
An alternating voltage is applied between the pair of catalyst layers so that an alternating current having a constant amplitude value is generated in the electrolyte membrane. a power control unit that controls the power supply;
the electrolyte membraneThe change in the voltage value that occurs between the pair of catalyst layers via the gas according to the concentration of the impurity is set to a zero reference for the gas that does not contain the impurity, and is compared with the zero reference.VoltageThe value of theand a voltmeter to measureofPreparationrice field, gas meter. 2. The gas measurement device according to claim 1, wherein said power supply control unit controls to apply a sinusoidal AC voltage to said power supply so as to generate an AC current having said constant amplitude value . A part of the flow path is a tubular water vapor imparting flow path having an ion exchange resin as a wall material,
Further comprising a steam generator for generating steam around the steam imparting channel,
3. The gas measuring device according to claim 1, wherein said gas in said water vapor imparting channel is humidified through a wall of said water vapor imparting channel. 4. The gas measuring device according to claim 3, wherein said ion exchange resin is Nafion (registered trademark) . 5. The gas measuring device according to claim 3, wherein said steam generator generates a steam atmosphere of 30[deg.] C. or higher and 50[deg.] C. or lower to said steam applying channel. A gas measuring device for measuring impurities in a gas,
an electrolyte membrane impervious to said impurities;
a channel for sending the gas to the electrolyte membrane;
a power source that applies a voltage to the electrolyte membrane;
a power control unit that controls the power supply;
a voltmeter for measuring the voltage applied to the electrolyte membrane;
and an ammeter that measures the current flowing through the electrolyte membrane,
The power supply control unit controls the power supply to apply an alternating voltage to the electrolyte membrane,
a pair of catalyst layers sandwiching the electrolyte membrane;
further comprising a sensor holder for stably holding the electrolyte membrane and the pair of catalyst layers;
The sensor holder is
a pair of wire meshes sandwiching the pair of catalyst layers;
a plurality of rod-shaped current collecting electrodes sandwiching the wire mesh and one end of which is a connector portion for outputting a signal;
a holding supporter holding ends opposite to the one ends of the plurality of current collecting electrodes;
a fixed supporter that holds between the holding supporter and the connector portion of the current collecting electrodes and fixes and holds the distance between the plurality of current collecting electrodes;airBody measurement device. A gas analysis system for measuring and analyzing impurities in gas,
air Body measurement deviceofprepared,
The gas measuring device is
an electrolyte membrane impervious to said impurities;
a pair of catalyst layers sandwiching the electrolyte membrane;
a channel for sending the gas to the electrolyte membrane;
a power source that applies a voltage to the electrolyte membrane;
a power supply control unit that controls the power supply;
a voltmeter for measuring the voltage applied to the electrolyte membrane;
and an ammeter that measures the current flowing through the electrolyte membrane,
The power supply control unit controls the power supply to apply an alternating voltage to the electrolyte membrane,
an analysis unit that analyzes the measurement results of the gas measuring device;moreprepared,
The analysis unit
Analyzing a first impurity and a second impurity as the plurality of impurities,
A gas analysis system comprising a conversion unit that converts a second parameter based on the impurity concentration of the second impurity into a first parameter based on the impurity concentration of the first impurity. The power supply applies the AC voltage so as to flow a current of constant amplitude to the electrolyte membrane,
8. The gas analysis system according to claim 7, wherein said conversion unit calculates the impurity concentration when converted to said first impurity from the increased value of said AC voltage based on said impurity concentration of said second impurity. A gas measurement method using a gas measurement device for measuring impurities in a gas,
The gas measuring device is
an electrolyte membrane impervious to said impurities;
a pair of catalyst layers sandwiching the electrolyte membrane;
a channel for sending the gas to the electrolyte membrane;
electricsource and
An alternating voltage is applied between the pair of catalyst layers so that an alternating current having a constant amplitude value is generated in the electrolyte membrane. a power supply control unit that controls the power supply;
and a voltmeter for measuring the voltage applied to the electrolyte membrane,
A part of the flow path is a tubular water vapor imparting flow path having an ion-exchange resin as a wall material,
further comprising a steam generator for generating steam around the steam imparting channel,
wherein the water vapor generating part gives humidity to the gas in the water vapor imparting channel through the wall of the water vapor imparting channel,
The voltmeter sets the change in the voltage value generated between the pair of catalyst layers through the electrolyte membrane according to the concentration of the impurity to a zero reference in the case of the gas not containing the impurity, Measure the value of the voltage compared to the zero reference A gas measurement method including a measurement step. A gas analysis method using a gas measuring device for measuring impurities in a gas,
The gas measuring device is
an electrolyte membrane impervious to said impurities;
a pair of catalyst layers sandwiching the electrolyte membrane;
a channel for sending the gas to the electrolyte membrane;
a power source that applies a voltage to the electrolyte membrane;
a power control unit that controls the power supply;
an analysis unit that analyzes a first impurity and a second impurity as the plurality of impurities,
an AC applying step in which the power supply control unit controls the power supply to apply an AC voltage to the electrolyte membrane;
The gas analysis method, wherein the analysis section converts a second parameter based on the impurity concentration of the second impurity into a first parameter based on the impurity concentration of the first impurity. The computer is caused to execute the measurement step for realizing the gas measurement method according to claim 9, or the alternating current application step and the conversion step for realizing the gas analysis method according to claim 10. program for.

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