JP7649032B2 - Method, program and system for measuring hydrogen sulfide gas in hydrogen gas - Google Patents

Description

The present invention relates to a method, program, and system for measuring hydrogen sulfide gas in hydrogen gas.

In recent years, there has been an increasing need to provide high-quality hydrogen gas in preparation for the practical application of fuel cells. The inventors of this application have previously developed fuel cell protection devices, temperature and humidity control devices, fluid transfer devices, and the like (Patent Documents 1 to 3).

A gas chromatography device that continuously analyzes sample gas by gas chromatography is also known (Patent Document 4). Furthermore, a sensor cell that monitors various impurities in fuel hydrogen using a hydrogen pump type sensor cell is also known (Patent Document 5).

JP 2018-092786 A Patent No. 6684491 JP 2014-177892 A JP 2002-181798 A Patent No. 5597004

However, no hydrogen sulfide gas measurement method or hydrogen sulfide gas measurement system is known that can continuously measure hydrogen sulfide gas, an impurity in hydrogen gas, online with high accuracy.

The present invention aims to provide a hydrogen sulfide gas measurement method that enables highly accurate measurement of hydrogen sulfide gas, an impurity in hydrogen gas.

The first aspect of the present invention is a hydrogen sulfide gas measurement method using a hydrogen sulfide gas measurement system that measures hydrogen sulfide gas in hydrogen gas, the hydrogen sulfide gas measurement system comprising a flow path through which the hydrogen gas flows, a flow rate control unit that controls the speed at which the gas flows through the flow path, and a detection cell that detects hydrogen sulfide gas contained in the hydrogen gas, the hydrogen sulfide gas measurement method including a hydrogen sulfide attachment step in which the flow rate control unit introduces hydrogen sulfide gas into the flow path and attaches the hydrogen sulfide gas to the flow path, a collection step in which the hydrogen gas is collected, and a measurement step in which the hydrogen gas is measured.

The second aspect of the present invention is the hydrogen sulfide gas measurement method of the first aspect, in which in the hydrogen sulfide attachment step, hydrogen sulfide gas is attached to the flow path until a saturated state is reached.

A third aspect of the present invention is a hydrogen sulfide gas measurement method according to the first or second aspect, in which the hydrogen sulfide gas measurement system further comprises a hydrogen sulfide gas cylinder containing calibrated hydrogen sulfide gas, and in the hydrogen sulfide attachment step, the calibrated hydrogen sulfide gas is supplied from the hydrogen sulfide gas cylinder to the flow path.

A fourth aspect of the present invention is a hydrogen sulfide gas measurement method according to any one of the first to third aspects, wherein the hydrogen sulfide gas measurement system further comprises a zero gas cylinder containing zero gas from which impurities have been removed in advance, and further comprises a purging step of supplying the zero gas from the zero gas cylinder to the flow path prior to the collection step.

A fifth aspect of the present invention is a hydrogen sulfide gas measurement method according to any one of the first to fourth aspects, in which the measurement target gas is hydrogen gas, the hydrogen sulfide gas measurement system further includes a gas separation unit that separates at least carbon monoxide and hydrogen sulfide, and further includes a carbon monoxide removal step in which the gas separation unit separates carbon monoxide contained in the hydrogen gas and removes it from the hydrogen gas prior to the measurement step.

A sixth aspect of the present invention is a program for causing a computer to function as the flow rate control unit of any one of the first to fifth aspects.

The seventh aspect of the present invention is a hydrogen sulfide gas measurement system for measuring hydrogen sulfide gas in hydrogen gas, comprising a flow path through which the hydrogen gas flows, a hydrogen sulfide gas cylinder containing hydrogen sulfide gas, a flow rate control unit that controls the speed at which the gas flows through the flow path, and a detection cell that detects the hydrogen sulfide gas contained in the hydrogen gas, and the hydrogen sulfide gas cylinder is connected to the flow path via a control valve.

The eighth aspect of the present invention is the hydrogen sulfide gas measurement system of the seventh aspect, in which the hydrogen sulfide gas cylinder contains calibrated hydrogen sulfide gas.

A ninth aspect of the present invention is the hydrogen sulfide gas measurement system of the seventh or eighth aspect, further comprising a gas separation section that separates at least carbon monoxide and hydrogen sulfide.

The present invention may also be considered as an analysis method, program, and analysis system for continuously and online analyzing the presence or absence and amount of hydrogen sulfide gas contained in a gas to be measured.

According to each aspect of the present invention, it is possible to continuously measure hydrogen sulfide gas contained in hydrogen gas online with high reactivity and high accuracy.

The inventors believe that one of the reasons why it is difficult to measure hydrogen sulfide gas with high accuracy is the poor measurement responsiveness. Measurement methods with poor responsiveness are not suitable for practical use. Furthermore, they have determined that the cause of the poor responsiveness is that hydrogen sulfide has a tendency to adhere to parts of the stainless steel piping, etc., and does not reach the sensor cell.

Furthermore, the inventors came up with the unique technical idea that by deliberately attaching hydrogen sulfide to the entire flow path, it is possible to improve the accuracy of hydrogen sulfide measurement.

In particular, according to the second aspect of the present invention, by maximizing the amount of hydrogen sulfide attached to the entire flow path, it becomes easier to measure the hydrogen sulfide contained in the hydrogen gas that subsequently flows through the flow path with good reactivity and high accuracy.

Furthermore, according to the third or eighth aspect of the present invention, by attaching calibrated hydrogen sulfide, it becomes easier to ensure that the maximum amount of hydrogen sulfide is attached in each cycle. This makes it even easier to measure the hydrogen sulfide contained in hydrogen gas with high accuracy.

Furthermore, according to the fourth aspect of the present invention, it is possible to prepare the same environment before and after measurement, including by attaching hydrogen sulfide to the entire flow path. This makes it easy to repeatedly perform stable, highly reactive, and highly accurate measurements.

Furthermore, according to the fifth or ninth aspect of the present invention, impurities other than hydrogen sulfide gas contained in hydrogen gas can be removed in advance. Therefore, it becomes easier to measure the hydrogen sulfide contained in hydrogen gas with high accuracy.

1 is a block diagram showing an overview of a hydrogen sulfide gas measurement system according to an embodiment of the present invention. FIG. 1 is a system configuration diagram showing an example of an overview of a hydrogen sulfide gas measurement system according to an embodiment of the present invention. FIG. 1 is a diagram showing an example of an outline of a hydrogen sulfide gas measuring device according to an embodiment of the present invention; FIG. 1 is a flow chart showing an example of an outline of a measurement process flow in a hydrogen sulfide gas measuring method according to an embodiment of the present invention. FIG. 2 is a flow diagram showing an example of an operation flow of a hydrogen sulfide gas measuring device in a hydrogen sulfide gas measuring method according to an embodiment of the present invention. 1 is a graph showing an example of changes over time in the concentration of hydrogen sulfide gas impurity in hydrogen gas actually analyzed by the hydrogen sulfide gas measurement system according to the present embodiment.

The following describes in detail an embodiment of the present invention with reference to the drawings. Note that the examples of the present invention are not limited to the contents described below. Also, when there are multiple devices or components of the same type, they may be described collectively with the subscripts omitted.

First, we will explain the difficulties in measuring hydrogen sulfide gas that the inventors have discovered. Hydrogen sulfide gas has the property of being adsorbed by stainless steel. If the inside of the pipe is glass coated, adsorption is less likely, but joints and other parts are often made of stainless steel, so hydrogen sulfide is adsorbed. For this reason, even if hydrogen sulfide gas is mixed into the gas to be measured, detection is delayed. Even if hydrogen sulfide gas is detected, it is difficult to measure the concentration of hydrogen sulfide with high accuracy.

Figure 1 shows an example of a graph of changes over time that demonstrates the difficulty of measuring hydrogen sulfide. The vertical axis represents hydrogen sulfide concentration [ppb], and the horizontal axis represents time elapsed. Referring to Figure 1, it shows that the detected hydrogen sulfide concentration is not stable even 12 hours after starting to mix a constant concentration of hydrogen sulfide gas into hydrogen gas. If it takes such a long time to measure hydrogen sulfide concentration, it is an inappropriate measurement method.

The following describes a hydrogen sulfide gas measurement system and method invented by the present inventor to measure the hydrogen sulfide concentration in a gas to be measured with high sensitivity and accuracy.

2 is a diagram showing an example of the outline of a hydrogen sulfide gas measurement system (an example of a "hydrogen sulfide gas measurement system" in the claims) according to this embodiment. The hydrogen sulfide gas measurement system 1 includes a hydrogen sulfide gas measurement device panel 3 and a gas supply unit 5. The hydrogen sulfide gas measurement device panel 3 includes a hydrogen sulfide gas measurement device 7, a fuel gas flow path 9 ₁ (an example of a "flow path" in the claims), a zero gas flow path 9 ₂ , a hydrogen sulfide flow path 9 ₃ , a control valve 11, a backflow valve 13, and a connection point 15. The gas supply unit 5 includes a zero gas cylinder 17 (an example of a "zero gas cylinder" in the claims), a backup cylinder 19, a hydrogen sulfide gas cylinder 21, and a connection point 23.

The hydrogen sulfide gas measuring device panel 3 is a metal container in which the main devices of the hydrogen sulfide gas measuring system 1 other than various cylinders are packaged so that they can be installed outdoors. A plurality of flow paths 9 are connected to the hydrogen sulfide gas measuring device 7. The flow paths 9 include a fuel gas flow path 9 1 through which hydrogen fuel gas to be measured (an example of the "gas to be measured" in the claims of the present application) is supplied, a zero gas flow path 9 ₂ through which industrial hydrogen gas from which impurities have been removed in advance as zero gas (an example of the "zero gas" in the claims of the present application) is supplied, _and a hydrogen sulfide flow path 9 ₃ through which calibrated hydrogen sulfide gas is supplied. The hydrogen fuel supply flow path 33 connected to an external hydrogen fuel supply device 31 is branched at a connection point 35 located midway. The branched flow paths are connected to the fuel gas flow path 9 ₁ at a connection point 15 ₁ via a control valve 11 ₁ and a check valve 13 _1. The fuel gas flow path 9 ₁ is connected to the zero gas flow path 9 ₂ at a connection point 15 ₂ .

The gas supply unit 5 supplies various gases to the hydrogen sulfide gas measuring device. The zero gas cylinder 17 and the backup cylinder 19 of the gas supply unit 5 contain industrial hydrogen gas from which impurities have been removed in advance as zero gas. The hydrogen sulfide gas cylinder 21 contains calibrated hydrogen sulfide gas. In this embodiment, the hydrogen sulfide gas cylinder 21 contains 10 L of hydrogen sulfide at 1.5 ppm. The zero gas cylinder 17 is connected to the fuel gas flow path 9 ₁ via a gate valve, a control valve 11 ₂ , a connection point _{15 2} , a check valve 13 ₂ , and a connection point 15 1 in this order. The backup cylinder 19 is connected to a flow path connected to the zero gas cylinder 17 at a connection point 23 via a gate valve. The hydrogen sulfide gas cylinder 21 is connected to the hydrogen sulfide flow path 9 ₃ via a gate valve.

The hydrogen sulfide gas measurement system 1 samples and measures a portion of the hydrogen fuel gas supplied at 0.2 to 0.8 MPa from an external hydrogen fuel supply device 31 as a measurement target gas. The hydrogen sulfide gas measurement device 7 measures the concentration of hydrogen sulfide contained in the supplied hydrogen fuel gas. The hydrogen sulfide gas measurement device 7 is capable of communicating with an external computer 37. The hydrogen sulfide gas measurement device 7 can be controlled by the computer 37, and the measurement results can be displayed on the computer 37. The flow path 9 is a flow path for various gases. The adjustment valve 11 adjusts the flow rate of gas flowing through the flow path. The adjustment valve _11-1 adjusts the flow rate of the sampled hydrogen fuel gas to 0.20 MPa. The adjustment valve _11-2 adjusts the flow rate of the zero gas supplied from the zero gas cylinder 17 and/or the backup cylinder 19 to 0.15 MPa.

Figure 3 is a block diagram showing an overview of the hydrogen sulfide gas measurement system 1 according to the present embodiment. Referring to Figure 3, the hydrogen sulfide gas measurement system 1 includes a gas supply unit 5, a hydrogen sulfide gas measurement device 7, a flow path 9, a valve unit 10, a column 25 (an example of a "gas separation unit" in the present claims), a conversion unit 27, a display unit 29, and a control unit 51. The gas supply unit 5 includes a zero gas cylinder 17, a backup gas cylinder 19, and a hydrogen sulfide gas cylinder 21. The hydrogen sulfide gas measurement device 7 includes an electromagnetic valve 71, a flow controller 73, a distilled water tank 74, and a measurement unit 75. The measurement unit 75 includes a sensor cell 77 (an example of a "detection cell" in the present claims), a power source 79, a voltmeter 81, a temperature and humidity sensor 83, and a humidification pot 85. The control unit 51 has a valve control unit 53, a flow rate control unit 55 (an example of the "flow rate control unit" described in the claims), a power supply control unit 57, and a display control unit 59.

The solenoid valve 71 is a two-way or three-way solenoid valve that can switch the direction of gas flow and open/close by turning it ON and OFF. The flow controller 73 adjusts the flow rate of gas at a specific point in the flow path 9. The distilled water tank 74 holds distilled water to be supplied to the humidification pot 85. The measurement unit 75 measures the concentration of impurities contained in the supplied gas.

In the measurement unit 75, the sensor cell 77 is a hydrogen pump type sensor cell. The resistance value of the sensor cell 77 changes depending on the impurity concentration. The sensor cell 77 has the property of reacting with high sensitivity when hydrogen sulfide in hydrogen adheres to it, and quickly peeling off the hydrogen sulfide when the hydrogen sulfide decreases. The power source 79 supplies current to the sensor cell 77. The voltmeter 81 measures the voltage of the sensor cell 77. The temperature and humidity sensor 83 measures the temperature and humidity of the measurement unit 75. The humidification pot 85 humidifies the gas supplied to the sensor cell 77.

The valve 10 has valves such as a gate valve, a control valve, and a check valve, and controls the movement of gas in the hydrogen sulfide gas measurement system 1. The column 25 separates impurities contained in the hydrogen gas. In particular, in this embodiment, it is used to separate and remove carbon monoxide from the hydrogen gas. Since the sensor cell 77 reacts not only to hydrogen sulfide but also to carbon monoxide, removing carbon monoxide with the column 25 makes it even easier to improve the detection accuracy of hydrogen sulfide.

The conversion unit 27 converts the change in the measured voltage detected by the voltmeter 81 into a hydrogen sulfide concentration. The display unit 29 displays the converted hydrogen sulfide concentration.

In the control unit 51, the valve control unit 53 controls the flow direction, adjustment amount, and opening and closing of the various valves in the valve unit 10. The flow rate control unit 55 controls the flow controller 73 to control the flow rate at a specified location. The power supply control unit 57 controls the power supply 79. The display control unit 59 controls the display unit 29.

Figure 4 is a diagram showing an example of the configuration of the hydrogen sulfide gas measurement system 1 according to this embodiment. Hereinafter, for the three-way solenoid valves SV1 to SV5 among the solenoid valves SV, the input valve is referred to as "IN", the output valve that is open when OFF is referred to as "NO", and the output valve that is open when ON is referred to as "NC". Also, the solenoid valve SV may be referred to simply as "SV". SV6 is a two-way solenoid valve.

In FIG. 4, an external hydrogen fuel supply device 31 that supplies hydrogen gas, which is the gas to be measured, is connected to the hydrogen fuel supply flow path 33, gate valve V4, regulator valve R4, check valve G1, connection point C1, main valve V1, regulator valve R1, connection point C2, the IN valve of SV2, the NO valve, and connection point C3, in that order, via the NC valve of SV3. The NC valve of SV1 and the NC valve of SV2 are also connected. The check valve G2 prevents gas from flowing from connection point C1 in the direction of the hydrogen fuel supply device 31.

The zero gas cylinder 17 is connected to the measuring unit 75 via the connection point C4, the gate valve V5, the control valve R5, the connection point C5, the control valve R2, the connection point C6, the IN valve to the NO valve of SV3, the NO valve to the IN valve of SV5, the NO valve to the IN valve of SV1, the column 25, and the flow controller _73-1 in this order. Also, the backup cylinder 19 is connected to the connection point C4.

The hydrogen sulfide gas cylinder 21 is connected to the connection point C6 via the main valve V3, the control valve R3, the flow controller 733, the branch B1, and the SV6. The branch B1 is also connected to the NC valve of SV5 via the IN valve of SV4 and the NO valve.

Furthermore, the connection point C5 is connected to the connection point C1 via a check valve G2. The check valve G2 prevents gas from flowing from the connection point C1 to the connection point C5. The connection point C2 is also connected to the outlet of the gas to be measured via the main valve V2. The NC valve of SV4 is also connected to the exhaust gas outlet via the connection point C3 and the flow controller ₇₃₂ .

The gas supplied to the measuring unit 75 is humidified in the humidification pot 85 and reaches the detection pot where it is measured. After measurement, the gas is exhausted to the outside.

The hydrogen fuel supply device supplies hydrogen fuel at 0.2 to 0.8 MPa. The zero gas cylinder 17 supplies industrial hydrogen gas, from which impurities have been removed in advance, as zero gas at 0.2 to 0.8 MPa. The backup cylinder 19 supplies zero gas to the connection point C4 continuously and without interruption, without relying on electrical control, so there are no gaps in the concentration measurement. It also makes it possible to prevent the electrode element of the sensor cell 77 from being exposed to air and damaged. The hydrogen sulfide gas cylinder 21 supplies hydrogen sulfide gas calibrated at 0.1 MPa (an example of the "calibrated hydrogen sulfide gas" described in the claims of this application).

Adjusting valve R1 adjusts the gas pressure to 0.05 MPa. Adjusting valve R2 adjusts the gas pressure to 0.05 MPa. Adjusting valve R3 adjusts the gas pressure to 0.06 MPa. Adjusting valve R4 adjusts the gas pressure to 0.20 MPa. Adjusting valve R5 adjusts the gas pressure to 0.15 MPa.

Figure 5 is a flow diagram showing an example of a hydrogen sulfide gas measurement method according to this embodiment. Referring to Figure 5, hydrogen sulfide is preliminarily attached to the entire pipe, particularly the stainless steel parts, until it becomes saturated (an example of the "hydrogen sulfide attachment step" described in the claims of this application). Hydrogen sulfide attached to the stainless steel parts of the pipe does not peel off for a long time. When the flow is started, the main valves V1, V2, and V3 are open. Also, the solenoid valves SV1 to SV6 are OFF.

In step S11, SV1 to SV6 are kept OFF, zero gas is supplied from the zero gas cylinder 17 to the flow path 9, and purging is performed for 100 seconds (an example of the "purge step" described in the claims of this application).

Next, in step S12, SV1, SV2, and SV3 are turned ON, and SV4, SV5, and SV6 are turned OFF, and hydrogen fuel gas is sampled from the hydrogen generator 31 as the gas to be measured for 10 seconds and supplied to the flow path 9 (an example of the "sample step" described in the claims of this application).

Next, in step S13, SV2, SV4, and SV6 are turned ON, and SV1, SV3, and SV5 are turned OFF. Zero gas is supplied from the zero gas cylinder 17 to the flow path 9 while carbon monoxide is removed from the hydrogen gas in the column 25 over 35 seconds (carbon monoxide removal step). Calibrated flow path hydrogen gas is also supplied to the flow path 9 from the hydrogen sulfide gas cylinder 21. However, since the NC valve of SV4 is open and exhausted, the calibrated flow path hydrogen gas does not mix with the gas to be measured. The flow controller 3 controls the hydrogen sulfide concentration to 20 ppb.

Next, in step S14, SV2, SV5, and SV6 are turned ON, and SV1, SV3, and SV4 are turned OFF, and calibrated flow path hydrogen gas is supplied from hydrogen sulfide gas cylinder 21 to flow path 9 over 10 seconds. Flow controller 3 controls the hydrogen sulfide concentration to 20 ppb. This causes hydrogen sulfide gas to be adsorbed to flow path 9 and the solenoid valve again until it reaches a saturated state. This makes it possible to measure hydrogen sulfide with good sensitivity and high accuracy even if hydrogen sulfide is contained in the gas to be measured.

Next, in step S15, SV1 to SV6 are turned OFF, and zero gas is supplied from the zero gas cylinder 17 to the flow path 9 while measurements are taken over 25 seconds (an example of the "measurement step" described in the claims of this application).

Next, in step S16, the control unit determines whether or not to continue measuring the target gas. If it does, the process returns to step S11. If it does not, the process ends.

Figure 6 is a graph showing an example of the change over time in the hydrogen sulfide concentration in hydrogen gas actually measured by the hydrogen sulfide gas measurement system 1 according to this embodiment. The vertical axis represents the hydrogen sulfide concentration [ppb], and the horizontal axis represents the elapsed time. In the measurement, hydrogen gas with hydrogen sulfide concentrations of 0 ppb, 5 ppb, 10 ppb, 15 ppb, and 20 ppb was prepared by diluting 20 ppb of calibrated hydrogen sulfide gas with hydrogen gas.

As shown in FIG. 6, unlike the graph in FIG. 1, it can be seen that by using the hydrogen sulfide gas measurement system 1 of this embodiment, it is possible to measure extremely small amounts of hydrogen sulfide gas contained in hydrogen fuel gas with good responsiveness and high accuracy.

The column 25 may be included inside the hydrogen sulfide gas measuring device 7.

1; Hydrogen sulfide gas measurement system, 5; Gas supply unit, 7; Hydrogen sulfide gas measurement device, 9; Flow path, 17; Zero gas cylinder, 19; Backup cylinder, 21; Hydrogen sulfide gas cylinder, 25; Column, 31; Hydrogen fuel supply device, 71; Solenoid valve, 73; Flow controller, SV; Solenoid valve

Claims (6)

A hydrogen sulfide gas measurement method using a hydrogen sulfide gas measurement system that measures hydrogen sulfide gas in hydrogen gas, comprising:
The hydrogen sulfide gas measurement system includes:
A flow path through which the hydrogen gas flows;
a flow rate control unit for controlling a rate at which the gas flows through the flow path;
a detection cell for detecting hydrogen sulfide gas contained in the hydrogen gas ;
The hydrogen sulfide gas measurement system includes a hydrogen sulfide gas cylinder containing calibrated hydrogen sulfide gas;
A zero gas cylinder containing zero gas from which impurities have been removed in advance ,
a hydrogen sulfide adhering step in which the flow rate control unit introduces hydrogen sulfide gas into the flow path to cause the hydrogen sulfide gas to adhere to the flow path;
a purging step of supplying the zero gas from the zero gas cylinder to the flow path;
A collection step of collecting the hydrogen gas;
and a measuring step of measuring the hydrogen gas ,
A hydrogen sulfide gas measurement method, wherein in the hydrogen sulfide adhering step, the calibration hydrogen sulfide gas is supplied from the hydrogen sulfide gas cylinder to the flow path, and the hydrogen sulfide gas is allowed to adhere to the flow path until a saturated state is reached . The hydrogen sulfide gas measurement system further includes a gas separation unit that separates at least carbon monoxide and hydrogen sulfide,
2. The hydrogen sulfide gas measuring method according to claim 1 , further comprising a carbon monoxide removing step, prior to the measuring step, in which the gas separating section separates carbon monoxide contained in the hydrogen gas and removes it from the hydrogen gas. A program for causing a computer to function as the flow rate control unit according to claim 1 or 2 . A hydrogen sulfide gas measurement system for measuring hydrogen sulfide gas in hydrogen gas, comprising:
A flow path through which the hydrogen gas flows;
a hydrogen sulfide gas cylinder containing hydrogen sulfide gas;
a flow rate control unit for controlling a rate at which the gas flows through the flow path;
a detection cell for detecting hydrogen sulfide gas contained in the hydrogen gas ;
A zero gas cylinder containing zero gas from which impurities have been removed in advance ,
The hydrogen sulfide gas cylinder is connected to the flow path via a control valve. 5. The hydrogen sulfide gas measurement system of claim 4 , wherein the hydrogen sulfide gas cylinder contains calibrated hydrogen sulfide gas. 6. The hydrogen sulfide gas measuring system according to claim 4 , further comprising a gas separation section that separates at least carbon monoxide and hydrogen sulfide.

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