JP2017181215A - Method for evaluating hydrogen gas dispenser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaluation method which can accurately evaluate the accuracy of the measured value of a gas flow rate obtained by a built-in gas flowmeter of a hydrogen gas dispenser, over a wide range (wide pressure range and a wide flow rate range).SOLUTION: The method for evaluating a hydrogen gas dispenser according to the present invention includes the steps of: connecting an evaluation gas flowmeter and a hydrogen gas dispenser with a built-in gas flowmeter to each other; introducing a hydrogen gas and measuring the flow rate of the hydrogen gas by the gas flowmeter and the evaluation gas flowmeter; and determining whether the built-in gas flowmeter is functioning appropriately based on the difference between the measured value of the gas flow rate of the built-in gas flowmeter (MV) and the measured value of the gas flow rate of the evaluation gas flowmeter (SV). The evaluation gas flowmeter is corrected and is priced using the hydrogen gas based on a standard gas flowmeter having at least two critical flow nozzles with different throat diameters and on-off valves corresponding to the critical flow nozzles.SELECTED DRAWING: Figure 15

Description

  The present invention relates to a method for evaluating a hydrogen gas dispenser.

In recent years, automobiles (fuel cell automobiles, etc.) using hydrogen gas as a power source instead of fossil fuels such as gasoline have attracted attention. In order to supply hydrogen gas to such an automobile, installation of a hydrogen station capable of supplying hydrogen gas is required. The hydrogen station includes a hydrogen gas dispenser that supplies hydrogen gas, and hydrogen gas is supplied to the automobile using the hydrogen gas dispenser. Specifically, the high-pressure hydrogen tank provided in the automobile is filled with hydrogen gas supplied from a hydrogen gas dispenser. The hydrogen gas dispenser includes a built-in gas flow meter that measures the flow rate of hydrogen gas supplied to the automobile.
By the way, if there is an error between the measured gas flow rate measured by the built-in gas flow meter and the flow rate of the hydrogen gas actually supplied, the amount of hydrogen gas supplied to the automobile is excessive or insufficient. Therefore, there is a need for an evaluation method that can determine whether the gas flow rate measurement value of the built-in gas flow meter is accurate, that is, whether the hydrogen gas dispenser is good or bad. In particular, the hydrogen gas supplied from the hydrogen gas dispenser is compressed to a high pressure, and the pressure is wide. For example, hydrogen gas is compressed to 10 MPa to 120 MPa. Further, the hydrogen gas dispenser is expected to be able to supply 5 kg of hydrogen by filling for 3 minutes, although the supply amount of hydrogen required at the beginning and end of filling varies. For example, the supply amount of hydrogen gas supplied from the hydrogen gas dispenser is 0.1 kg / min to 3.6 kg / min.
Therefore, there is a need for an evaluation method that can accurately evaluate the accuracy of the gas flow rate measurement value of the built-in gas flow meter over a wide range (wide pressure range and wide flow range).

Conventionally, a Coriolis type gas flow meter is known as an evaluation gas flow meter used for evaluating a gas flow measurement value of a built-in gas flow meter (Patent Document 1).
However, although the conventional gas flowmeter can measure the flow rate of hydrogen gas in a wide range, it is not accurate because it is not calibrated and priced using a wide range of hydrogen gas. Therefore, there is a problem that even if a conventional gas flow meter is used, the quality of the hydrogen gas dispenser, that is, whether the measured value of the built-in gas flow meter is accurate cannot be evaluated with high accuracy.

JP 2012-026776 A

  An object of the present invention is to provide a method that can accurately evaluate the accuracy of a gas flow rate measurement value of a built-in gas flow meter included in a hydrogen gas dispenser over a wide range (wide pressure range and wide flow range). is there.

The method for evaluating a hydrogen gas dispenser of the present invention comprises a connecting step of connecting an evaluation gas flow meter and a hydrogen gas dispenser equipped with a built-in gas flow meter to form a gas flow path, and hydrogen gas in the gas flow path. A measurement step of measuring the flow rate of the hydrogen gas using the built-in gas flow meter and the evaluation gas flow meter, a gas flow rate measurement value (MV) of the built-in gas flow meter, and the evaluation gas A determination step of determining whether the built-in gas flow meter is good or not based on an error in a gas flow rate measurement value (SV) of the flow meter.
However, the gas flow meter for evaluation uses hydrogen gas based on a standard gas flow meter having at least two critical nozzles having different throat diameters and open / close valves provided corresponding to the respective critical nozzles. Are calibrated and priced.

  Preferably, in the determination step, the ratio (MV / SV) of the gas flow rate measurement value (MV) of the built-in gas flow meter and the gas flow rate measurement value (SV) of the evaluation gas flow meter is 0.95 to 1.05. When it is out of the range, it is a step of determining that the built-in gas flowmeter is defective.

Preferably, the evaluation method of the hydrogen gas dispenser of the present invention includes a repetition process in which the measurement process and the determination process are repeated while changing the conditions of the hydrogen gas introduced into the gas flow path, and a final pass / fail obtained through the repetition process. The system further includes a comprehensive evaluation step for performing a comprehensive pass / fail determination of the built-in gas flowmeter based on the number of determinations (y) and the number of determinations (z).
Preferably, when the ratio (z / y) of the number of times of failure determination (z) to the number of times of final quality determination (y) (z / y) exceeds 1/5 in the overall evaluation process, the built-in gas flow meter is integrated. This is a step of determining that the defect is defective.

  Preferably, the evaluation gas flow meter is a Coriolis gas flow meter.

  The evaluation method of the hydrogen gas dispenser of the present invention uses an evaluation gas flow meter calibrated and priced by a standard gas flow meter for evaluation of the built-in gas flow meter, and the standard gas flow meters have different throats. It has at least two critical nozzles with a diameter. Therefore, the accuracy of the gas flow measurement value of the built-in gas flow meter can be evaluated with high accuracy over a wide range (wide pressure range and wide flow range).

The schematic diagram which shows the gas flowmeter for evaluation connected to the hydrogen gas dispenser and the hydrogen gas dispenser. The schematic diagram which shows the critical nozzle type gas flowmeter (1st critical nozzle type gas flowmeter) which has one critical nozzle. The graph which shows the calibration curve obtained using a 1st critical nozzle type gas flowmeter. The schematic diagram which shows the critical nozzle type gas flow meter (2nd critical nozzle type gas flow meter) which has two critical nozzles which have the same throat diameter. The graph which shows the calibration curve obtained using the 2nd critical nozzle type gas flowmeter. The schematic diagram which shows the standard gas flowmeter used in 1st Embodiment of this invention, and the enlarged view of a critical nozzle. The graph which shows the calibration curve obtained using the critical nozzle type gas flow meter concerning a 1st embodiment. The VIII-VIII line enlarged end elevation in the enlarged view of FIG. The schematic diagram which shows the standard gas flowmeter used in 2nd Embodiment of this invention. The schematic diagram which shows the standard gas flowmeter used in 3rd Embodiment of this invention. The schematic diagram which shows the standard gas flowmeter used in 4th Embodiment of this invention. The schematic diagram which shows the state which connected the standard gas flowmeter and the test gas flowmeter, and formed the gas flow path. The schematic plan view which shows the Coriolis type | mold gas flowmeter which is a kind of gas flowmeter for evaluation. FIG. 14 is a schematic side view of the Coriolis type gas flow meter of FIG. 13. The flowchart which shows the evaluation procedure of a hydrogen gas dispenser.

  In this specification, although the evaluation method of a hydrogen gas dispenser is demonstrated, the term used in this specification and the code | symbol used in drawing are annotated as follows beforehand.

<Terminology>
A “gas flow meter” is a device capable of measuring a gas flow rate.
The “built-in gas flow meter” is a gas flow meter built in the hydrogen gas dispenser.
The “critical nozzle type gas flow meter” is a gas flow meter provided with a critical nozzle. The critical nozzle type gas flow meter can be used not only as a flow meter itself, but also as a standard gas flow meter serving as a reference for calibration and pricing of the test gas flow meter.
The “test gas flow meter” is a gas flow meter to be calibrated and priced by a standard gas flow meter. The test gas flow meter may be a critical nozzle gas flow meter, or may be another gas flow meter (for example, a thermal gas flow meter or a Coriolis gas flow meter).
The “evaluation gas flow meter” is a gas flow meter used for evaluating whether or not the gas flow measurement value of the built-in gas flow meter provided in the hydrogen gas dispenser is accurate. The gas flow meter for evaluation used for evaluation of the built-in gas flow meter in the present application is obtained by calibrating and pricing a specific test gas flow meter using a standard gas flow meter.
“Calibration” is to derive an error between the gas flow rate measurement value of the standard gas flow meter and the gas flow rate measurement value of the test gas flow meter.
“Pricing” is to correct the gas flow measurement value of the test gas flow meter so that the error between the gas flow measurement value of the standard gas flow meter and the gas flow measurement value of the test gas flow meter is reduced. .
“Adjustment” is to perform calibration and pricing.
The numerical range represented by “AA to BB” means AA or more and BB or less.

<About drawings>
2 and 4 show not the standard gas flow meter used in the present invention but the standard gas flow meter (critical nozzle type gas flow meter) examined in the formation process of the present invention. The same reference numerals as those in FIGS. 6 and 9 to 11 showing the standard gas flowmeter used are used in FIGS.
4, 6, and 9 to 11, in order to distinguish a plurality of members (a plurality of critical nozzles and a plurality of on-off valves), lower-case alphabets (“a” and “ b ").
Moreover, the black arrow attached | subjected to FIG.2, FIG.4, FIG.6, FIG. 9 thru | or 13 means the flow direction of hydrogen gas. 14 indicates the order of the vibration cycle of the flow tube (a process in which the vibration of the flow tube changes).
Furthermore, in FIG. 3, FIG. 5, and FIG. 7, a region surrounded by a broken line located in the vicinity of each of the calibration curves S1 to S6 represents a 95% confidence interval of each of the calibration curves S1 to S6.

<Outline of configuration of hydrogen gas dispenser and its evaluation method>
In order to evaluate the hydrogen gas dispenser, that is, to determine whether the gas flow measurement value of the built-in gas flow meter provided in the hydrogen gas dispenser is accurate, it is necessary to connect the evaluation gas flow meter to the hydrogen gas dispenser. is there.
Specifically, as shown in FIG. 1, the hydrogen gas dispenser 1 normally includes a built-in gas flow meter 11, a nozzle 12 that supplies hydrogen gas to a hydrogen automobile and the like, and a display 13. The flow rate of the hydrogen gas supplied from the nozzle 12 is measured over time by the built-in gas flow meter 11, and the measured gas flow rate is displayed on the display 13. For example, by connecting the evaluation gas flow meter 2 to the nozzle 12, the flow rate of the hydrogen gas supplied from the hydrogen gas dispenser 1 can be measured by both the built-in gas flow meter 11 and the evaluation gas flow meter 2. Then, on the assumption that the gas flow measurement value (SV) of the evaluation gas flow meter 2 is accurate, it is determined whether or not the gas flow measurement value (MV) of the built-in gas flow meter 11 is accurate, that is, the built-in gas. The quality of the flow meter 11 is judged. Note that a hydrogen gas tank (not shown) is connected to the evaluation gas flow meter 2, and the hydrogen gas flowing into the evaluation gas flow meter 2 from the hydrogen gas dispenser 1 is finally stored in the hydrogen gas tank. .

Since the hydrogen gas dispenser 1 is designed so that hydrogen gas can be supplied over a wide range (wide pressure range and wide flow range), the evaluation gas flow meter 2 can accurately measure the hydrogen gas over a wide range. It must be possible to measure the flow rate. Therefore, it is desirable that the evaluation gas flow meter is calibrated and priced using a standard gas flow meter (not shown in FIG. 1) capable of pricing the flow rate of hydrogen gas over a wide range. That is, it is desirable to produce an evaluation gas flow meter by calibrating and pricing the measured gas flow rate of a specific test gas flow meter using a standard gas flow meter.
The inventors of the present invention focused on a critical nozzle type gas flow meter having a specific structure as a standard gas flow meter capable of calibrating and pricing the flow rate of hydrogen gas over a wide range and made the present invention.

<About the formation process of the present invention>
The gas flow meter for evaluation used in the present invention is calibrated and priced using hydrogen gas with reference to a critical nozzle type gas flow meter which is a standard gas flow meter. The critical nozzle type gas flow meter is a gas flow meter having a critical nozzle. The critical nozzle is a device capable of generating a constant reference flow rate under a constant pressure condition, and a calibration curve can be obtained based on the reference flow rate generated using the critical nozzle. This calibration curve is a standard for calibration and pricing of the gas flowmeter.
Hereinafter, the principle of the critical nozzle type gas flow meter will be described with reference to the drawings, and then the two types of critical nozzle type gas flow meters studied in the formation process of the present invention will be described. A critical nozzle type gas flow meter used as a meter will be described.

(About the principle of the critical nozzle type gas flow meter)
As shown in FIG. 2, the critical nozzle type gas flow meter 3 generally includes an upstream gas passage (also referred to as a rectifying pipe) 31 having a constant inner diameter and a downstream gas having the same inner diameter as the upstream gas passage 31. The flow path 32, one critical nozzle 33 provided between the upstream gas flow path 31 and the downstream gas flow path 32, the gas sensor 34 connected to the upstream gas flow path 31, and the gas sensor 34 A flow rate calculation unit 35.
The critical nozzle 33 includes a throttle portion 331 whose inner diameter decreases from the upstream gas passage 31 side to the downstream gas passage 32 side, and a diffuser portion whose inner diameter increases from the upstream gas passage 31 side to the downstream gas passage 32 side. 332 and a throat portion 333 which is a boundary portion between the throttle portion 331 and the diffuser portion 332 and has the smallest inner diameter.
The maximum inner diameter of the throttle portion 331 is equal to or smaller than the inner diameter of the upstream gas flow path 31, and the maximum inner diameter of the diffuser portion 332 is equal to or smaller than the inner diameter of the downstream gas flow path 32. The maximum inner diameter of the throttle portion 331 means the inner diameter at the portion facing the upstream gas flow path 31 of the throttle portion 331, and the maximum inner diameter of the diffuser portion 332 faces the downstream gas flow path 32 of the diffuser portion 332. This means the inner diameter of the part.
In the critical nozzle type gas flow meter 3 of FIG. 2, the maximum inner diameter of the throttle portion 331 and the inner diameter of the upstream gas flow path 31 are the same length, and the maximum inner diameter of the diffuser portion 332 and the inner diameter of the downstream gas flow path 32 are the same length. It is comprised so that it may become.

  Although not shown, a pressure reducing means such as a vacuum pump is connected downstream of the downstream gas flow path 32, and by operating this vacuum pump, a gas flowing through the upstream gas flow path 31 (hereinafter referred to as "upstream gas"). Is at a higher pressure than the gas flowing through the downstream gas flow path 32 (hereinafter referred to as “downstream gas”). That is, a pressure difference is generated between the upstream gas and the downstream gas. As the pressure difference between the upstream gas and the downstream gas increases, the flow velocity of the gas flowing through the throat portion 333 of the critical nozzle 33 increases. When the ratio of the upstream gas pressure and the downstream gas pressure reaches the critical pressure ratio, the gas flow velocity reaches the critical velocity (sound velocity), and the gas flow velocity does not increase any more. When the gas flow velocity reaches the critical velocity, a gas having a constant mass determined by the upstream gas pressure, temperature, and the inner diameter (throat diameter) of the throat portion 333 flows regardless of the downstream gas flow.

The gas sensor 34 includes a pressure gauge capable of measuring at least the upstream gas pressure, and preferably includes not only the pressure gauge but also a thermometer capable of measuring the temperature of the upstream gas. Based on parameters such as the pressure and temperature of the upstream gas measured by the gas sensor 34, the throat diameter of the critical nozzle 33, and the cross-sectional area of the throat portion 333, the mass flow rate of the gas flowing through the throat portion 333 (that is, the reference flow rate) is 34 is calculated by a flow rate calculation unit 35 connected to 34.
A calibration curve is created using the reference flow rate generated by the critical nozzle 33 provided in the critical nozzle gas flow meter 3, and the test gas flow meter can be calibrated and priced based on this calibration curve.

(First critical nozzle type gas flow meter)
In order to obtain a standard gas flow meter capable of calibrating and pricing the gas flow measurement value of the test gas flow meter over a wide pressure range and a wide flow range, first, as shown in FIG. Attention was focused on the critical nozzle type gas flow meter 3 (first critical nozzle type gas flow meter) having only one critical nozzle 33.
High-pressure hydrogen gas is allowed to flow through the first critical nozzle type gas flow meter 3 a plurality of times while changing the pressure condition, and the flow rate value (reference flow rate) in the critical state is measured a plurality of times. By plotting the reference flow rate thus obtained on the coordinates, a calibration curve S1 as shown in FIG. 3 is obtained. In FIG. 3, “gas flow rate” means the mass flow rate of hydrogen gas flowing through the throat portion 333.
However, since the first critical nozzle type gas flow meter 3 has only one critical nozzle 33, there is necessarily only one pattern of the throat diameter. Therefore, theoretically, only one reference flow rate is generated under a certain pressure condition, and as a result, only one calibration curve can be obtained. Therefore, even if the gas flow meter for evaluation is produced by calibrating and pricing the gas flow meter to be tested based on the first critical nozzle type gas flow meter 3 (only the calibration curve S1), this gas flow rate for evaluation is used. The meter cannot accurately measure the flow rate of hydrogen gas over a wide range (wide pressure range and wide flow range). Therefore, even if this evaluation gas flow meter is used, the accuracy of the gas flow measurement value of the built-in gas flow meter cannot be evaluated with high accuracy over a wide range.

Specifically, when calibration and pricing of the test gas flow meter is performed based on the calibration curve S1, the range of the 95% confidence interval on the calibration curve S1 (for example, point i in FIG. 3) and the calibration curve S1. The inside (for example, point ii) can be calibrated and priced with high accuracy. Therefore, when the flow rate of hydrogen gas is measured using the evaluation gas flow meter calibrated and priced using the first critical nozzle type gas flow meter 3, the measured value of the hydrogen gas flow rate is the calibration curve. When the value is included in the range of 95% confidence interval on S1 and calibration curve S1, the reliability of the measured gas flow rate is high.
On the other hand, when the flow rate of a certain hydrogen gas is measured using an evaluation gas flow meter, if the measured gas flow rate is a value outside the 95% confidence interval, the reliability of the measured gas flow rate is low. That is, when the flow rate of hydrogen gas is measured over a wide range (wide pressure range and wide flow range) using the evaluation gas flow meter calibrated and priced by the first critical nozzle type gas flow meter 3 The gas flow meter for evaluation showed a high flow rate measurement value under low pressure conditions (see point iii in FIG. 3), or a low flow rate measurement value under high pressure conditions (point iv in FIG. 3). Even if it is shown, the reliability of the measured value is low. Thus, the reliability of the gas flow rate measurement value of the evaluation gas flow meter decreases as the value deviates from the calibration curve S1.
Therefore, even if the first critical nozzle type gas flow meter 3 is used as a standard gas flow meter, the test gas flow meter cannot be calibrated and priced with high accuracy under a wide range of pressure conditions and a wide range of gas flow rates.

In FIG. 3, for the sake of convenience, the calibration curve S1 (solid line) and the upper and lower limits (broken line) of the 95% confidence interval are shown as straight lines represented by a linear function. The upper and lower limits of the calibration curve S1 and the 95% confidence interval are not limited to those represented by such straight lines but may be represented by curves (the same applies to FIGS. 5 and 7 described later).
The functions represented by the calibration curve S1 and the upper and lower limits of the 95% confidence interval may vary depending on the temperature and purity of the reference hydrogen gas, the throat diameter of the critical nozzle, and the like.
However, no matter what hydrogen gas is used as a reference or whatever critical nozzle is used, there is a relationship in which the gas flow rate increases in proportion to the increase in upstream gas pressure.

(Second critical nozzle type gas flow meter)
In view of the above problems when the first critical nozzle type gas flow meter 3 is used, the present inventors have provided a second critical nozzle type gas flow meter 3 having a plurality of critical nozzles 33 having the same throat diameter. We focused on calibrating and pricing the gas flow meter to be detected using.
FIG. 4 is a schematic diagram showing a second critical nozzle type gas flow meter 3 having a plurality of critical nozzles 33 (two of the first critical nozzle 33a and the second critical nozzle 33b in FIG. 4) having the same throat diameter. is there.
The upstream gas flow path 31 of the second critical nozzle type gas flow meter 3 includes an upstream single path portion 311 and a plurality of upstream branches branched from the upstream single path portion 311 in accordance with the number of critical nozzles 33 from upstream to downstream. And a path portion 312 (two in FIG. 4). Further, the downstream gas flow path 32 includes, from upstream to downstream, the same number of downstream branch path portions 322 as the number of critical nozzles 33, and a downstream single path portion 321 configured by joining the downstream branch path portions. . The upstream gas channel 31 and the downstream gas channel 32 are connected by a plurality of critical nozzles 33 (a first critical nozzle 33a and a second critical nozzle 33b) provided between the upstream branching channel portion 312 and the downstream branching channel portion 322. Has been. In other words, the plurality of critical nozzles 33 are arranged in parallel via the upstream branch path portion 312 of the upstream gas flow path 31 and the downstream branch path portion 322 of the downstream gas flow path 32.

  In the second critical nozzle type gas flow meter 3, the number of on-off valves 36 corresponding to the critical nozzle 33 is provided. In FIG. 4, a first on-off valve 36 a corresponding to the first critical nozzle 33 a and a second on-off valve 36 b corresponding to the second critical nozzle 33 b are provided, and the upstream branch passage 312 of the upstream gas passage 31 is provided respectively. Each on-off valve 36a, 36b is provided. By operating the on-off valve 36, the upstream branch passage 312 can be switched between an open state (a state in which hydrogen gas flows into the critical nozzle 33) and a closed state (a state in which hydrogen gas does not flow into the critical nozzle 33). As a result, the gas can flow from the upstream gas channel 31 to the downstream gas channel 32 through the first critical nozzle 33a or the second critical nozzle 33b, or through the first critical nozzle 33a and the second critical nozzle 33b.

Similarly to the first critical nozzle type gas flow meter 3, a gas sensor 34 is connected to the upstream single path portion 311 of the upstream gas flow path 31, and a flow rate calculation unit 35 is connected to the gas sensor 34. Therefore, two calibration curves S2 and S3 as shown in FIG. 5 are obtained by flowing the reference hydrogen gas through the second critical nozzle type gas flow meter 3 while changing the pressure condition. That is, hydrogen gas flows through the first critical nozzle 33a or the second critical nozzle 33b when one of the two open / close valves 36a and 36b is opened and the other open / close valve 36 is closed. Thus, a calibration curve S2 is obtained (the first critical nozzle 33a and the second critical nozzle 33b have the same throat diameter, so the same calibration curve is theoretically obtained).
On the other hand, when both the two on-off valves 36a and 36b are opened, the hydrogen gas flows through the first critical nozzle 33a and the second critical nozzle 33b, so that a calibration curve S3 is obtained. When two critical nozzles 33a and 33b are used, the same flow rate can be obtained under a low gas pressure condition as compared with the case where one critical nozzle 33 is used.

When the second critical nozzle type gas flow meter 3 is used, a plurality of calibration curves are obtained as described above. Since the plurality of critical nozzles 33 included in the second critical nozzle type gas flow meter 3 all have the same throat diameter, the number of calibration curves obtained is the critical nozzle 33 included in the second critical nozzle type gas flow meter 3. Is equal to the number of
That is, as shown in FIG. 5, in the case of the critical nozzle type gas flow meter 3 using two critical nozzles 33, two calibration curves are obtained, and the critical nozzle type using three or more critical nozzles 33 is obtained. In the case of the gas flow meter 3, three or more calibration curves equal to the number of critical nozzles 33 are obtained (not shown).
Then, when the gas flow meter for evaluation is prepared by calibrating and pricing the test gas flow meter based on the calibration curves S2 and S3, and when the flow rate of a certain hydrogen gas is measured using this gas flow meter for evaluation The gas flow rate measurement value is on the calibration curve S2 (for example, the point v in FIG. 5), within the range of the 95% confidence interval of the calibration curve S2 (for example, the point vi), and on the calibration curve S3 (for example, FIG. 5 is a value within the range of the 95% confidence interval of the calibration curve S3 (for example, the point viii), the reliability of the measured gas flow rate is high.
On the other hand, when the flow rate of a certain hydrogen gas is measured using an evaluation gas flow meter, if the measured gas flow rate is a value outside the 95% confidence interval (see point ix and point x in FIG. 5), The reliability of the measured gas flow rate is low.

Thus, even if the second critical nozzle type gas flow meter 3 is used as a standard gas flow meter, only the same number of calibration curves as the number of critical nozzles 33 can be obtained. When trying to price the test gas flow meter with a wide range of gas flow rates under a wide range of pressure conditions, it is necessary to use a large number of critical nozzles 33.
However, in general, the critical nozzle 33 is large. When measuring the flow rate of high-pressure hydrogen gas, it is necessary to use a larger critical nozzle 33 in order to provide the critical nozzle 33 with a sufficient pressure-resistant structure. Accordingly, it is extremely impractical and impractical to calibrate and price the test gas flow meter using the second critical nozzle gas flow meter 3.

<Standard gas flowmeter used in the present invention>
As described above, the present invention has been made in view of the problems that occur when the gas flow meter to be measured is calibrated and priced using the first and second critical nozzle gas flow meters. An evaluation gas flow meter used in the present invention is a critical nozzle type gas flow meter according to any one of the first to fourth embodiments, which will be described later. It is obtained by calibrating and pricing the detection gas flow meter.
A standard gas flow meter used as a calibration and pricing reference in the present invention is a critical nozzle type having at least two critical nozzles having different throat diameters, and on-off valves provided corresponding to the respective critical nozzles. It is a gas flow meter. Hereinafter, the critical nozzle type gas flowmeter used in the present invention will be described in detail.

(First embodiment)
The configuration of the critical nozzle type gas flow meter according to the first embodiment is basically the same as that of the second critical nozzle type gas flow meter, but at least two critical nozzles among the plurality of critical nozzles have different throat diameters. It differs from the 2nd critical nozzle type gas flowmeter in having.
In the description of the first embodiment, since the configuration other than the throat diameter of the critical nozzle is the same as that of the second critical nozzle type gas flow meter, the description thereof is omitted as appropriate.

As shown in FIG. 6, the critical nozzle type gas flowmeter 3 used in the present invention includes a plurality of upstream gas passages 31, downstream gas passages 32, and a plurality of gas passages 31, 32 (in FIG. 6). 2) critical nozzles 33. The upstream gas flow path 31 has an upstream single path portion 311 and an upstream branch path portion 312 branched from the upstream single path portion 311 in accordance with the number of critical nozzles 33. Similarly, the downstream gas flow path 32 is also It has a downstream single path part 321 and a downstream branch path part 322.
The upstream branch passage 312 of the upstream gas passage 31 is provided with an opening / closing valve 36 corresponding to each critical nozzle 33. By operating the on-off valve 36, the upstream branching passage 312 can be switched between the open state and the closed state. As a result, hydrogen flows through the selected critical nozzle 33 from the upstream gas passage 31 to the downstream gas passage 32. Gas can flow.
A gas sensor 34 is connected to the upstream single path portion 311 of the upstream gas flow path 31, and a flow rate calculation unit 35 is connected to the gas sensor 34.

  In the critical nozzle type gas flow meter 3 used in the present invention, a plurality of critical nozzles 33 are used, and at least two critical nozzles 33 have different throat diameters. In the example shown in FIG. 6, two critical nozzles 33 (first critical nozzle 33a and second critical nozzle 33b) are provided, and the throat diameter of the first critical nozzle 33a is equal to the throat diameter of the second critical nozzle 33b. It is configured to be doubled.

Three calibration curves S4 to S6 as shown in FIG. 7 are obtained by flowing a reference hydrogen gas through the critical nozzle type gas flow meter 1 while changing the pressure condition. That is, when the on / off valve 36a corresponding to the first critical nozzle 33a is opened and the on / off valve 36b corresponding to the second critical nozzle 33b is closed among the two on / off valves 36a and 36b, the second throat diameter is large. Since hydrogen gas flows only through the one critical nozzle 33a, a calibration curve S4 is obtained. On the other hand, when the on-off valve 36b corresponding to the second critical nozzle 33b is opened and the on-off valve 36a corresponding to the first critical nozzle 33a is closed, hydrogen gas is only passed through the second critical nozzle 33b having a small throat diameter. Since it flows, a calibration curve S5 is obtained. Further, when both the two on-off valves 36a and 36b are opened, the hydrogen gas flows through the first critical nozzle 33a and the second critical nozzle 33b, so that a calibration curve S6 is obtained.
Thus, since the critical nozzle type gas flowmeter 3 used in the present invention has at least two critical nozzles 33 having different throat diameters, the critical nozzles 33 of the critical nozzle 33 can be appropriately combined with the critical nozzles 33 through which hydrogen gas passes. More calibration curves than the number are obtained.
Therefore, if the critical nozzle type gas flow meter 3 used in the present invention is used as a standard gas flow meter, the test gas flow meter is calibrated and priced over a wide range (wide pressure condition and wide flow range). As a result, the accuracy of the gas flow rate measurement value of the built-in gas flow meter can be evaluated with high accuracy over a wide range.

  The lower limit value of the number of critical nozzles included in the critical nozzle type gas flowmeter used in the present invention is two, preferably three, and more preferably four. The upper limit value of the number of critical nozzles is not particularly limited, but is preferably 7 and more preferably 6. If the number of critical nozzles exceeds seven, the critical nozzle type gas flow meter becomes too large, which may impair practicality.

  In the present invention, it is preferable that all of the plurality of critical nozzles have different throat diameters. If the throat diameters of the critical nozzles are all different, the maximum number of calibration curves represented by the following formula (1) can be obtained.

As described above, in the case of a gas flow meter (second critical nozzle type gas flow meter) provided with critical nozzles having the same throat diameter, only the same number of calibration curves as the number of critical nozzles can be obtained. For example, when the number of critical nozzles is three, only three calibration curves are obtained, and when the number of critical nozzles is four, only four calibration curves are obtained.
On the other hand, in the present invention, when the number of critical nozzles is 3 (n = 3) based on the above formula (1), a maximum of 7 calibration curves can be obtained, and the number of critical nozzles is When there are four (n = 4), a maximum of 15 calibration curves can be obtained.
As described above, in the present invention, as the number of critical nozzles increases, the number of calibration curves obtained by the combination increases. Therefore, the test gas flowmeter is calibrated under a wide range of pressure conditions and a wide range of gas flow rates. And can be priced.

Further, in the critical nozzle type gas flowmeter used in the present invention, the ratio of the throat diameter D _MAX of the critical nozzle having the largest throat diameter to the throat diameter D _MIN of the critical nozzle having the smallest throat diameter is (D _MAX / D _MIN ) Although not particularly limited, the lower limit of the ratio is preferably 1.4, more preferably 2.0, and particularly preferably 2.4.
The upper limit of the throat diameter ratio (D _MAX / D _MIN ) is not particularly limited, but is preferably 5.0, more preferably 4.0, and particularly preferably 3.0.
When the ratio of the throat diameter (D _MAX / D _MIN ) is less than 1.4, the calibration curve obtained by each critical nozzle becomes too close, and the 95% confidence interval of each calibration curve overlaps more than necessary. There is a possibility that calibration and pricing of the detection gas flow meter may become inefficient.
When the throat diameter ratio (D _MAX / D _MIN ) exceeds 5.0, the calibration curve obtained by combining the critical nozzle with the largest throat diameter and the critical nozzle with the smallest throat diameter and the criticality with the largest throat diameter are obtained. The calibration curve obtained with the nozzle alone is too close. As a result, the 95% confidence intervals of both calibration curves overlap more than necessary, which may result in inefficient calibration and pricing of the test gas flowmeter.

As a specific example, the throat diameter (D _MAX ) of the critical nozzle having the largest throat diameter is 1.8 mm to 3.0 mm, preferably 1.8 mm to 2.0 mm. In addition, the throat diameter (D _MIN ) of the critical nozzle having the smallest throat diameter is 0.1 mm to 0.6 mm, preferably 0.2 mm to 0.5 mm.
However, the length of the throat diameter is not limited to the above range, and can be appropriately set according to the purity of hydrogen gas used for calibration and pricing, the pressure range of hydrogen gas, the flow rate of hydrogen gas, and the like.

In this specification, the throat diameter of the critical nozzle is a distance obtained by connecting a first point of the inner edge of the throat part and a second point of the inner edge of the throat part independent of the first point by a straight line. is there. There are an infinite number of such straight lines, but an infinite number of straight lines having the maximum distance corresponds to the throat diameter in the present invention.
Usually, as shown in FIG. 8, since the end surface shape of the throat portion 333 is circular, the throat diameter means the length X of the diameter of the circle.

  The critical nozzle type gas flowmeter used in the present invention has a plurality of critical nozzles, and at least two critical nozzles of the plurality of critical nozzles have different throat diameters. Therefore, a large number of calibration curves can be obtained by combining critical nozzles. Therefore, by using this critical nozzle type gas flow meter as a standard gas flow meter, the test gas flow meter can be calibrated and priced under a wide range of pressure conditions and a wide range of gas flow rates, and a highly accurate evaluation is possible. A gas flow meter can be obtained.

In the first embodiment, as shown in FIG. 6, the upstream gas flow path 31 has an upstream single path section 311 and an upstream branch path section 312, and a plurality of upstream gas flow path sections 312 are arranged at the most downstream of the upstream branch path section 312. Although the critical nozzles 33 (the first critical nozzle 33a and the second critical nozzle 33b) are connected, the critical nozzle gas flow meter 3 used in the present invention is not limited to the first embodiment.
Hereinafter, the critical nozzle type gas flowmeter 3 according to the second embodiment to the fourth embodiment used in the present invention will be described, but mainly only the parts different from the critical nozzle type gas flowmeter 3 according to the first embodiment. explain.

(Second Embodiment)
FIG. 9 is a schematic diagram showing a critical nozzle type gas flow meter 1 according to the second embodiment used in the present invention.
In the present embodiment, the upstream gas flow path 31 and the downstream gas flow path 32 are connected via a gas introduction chamber 37, and a plurality of critical nozzles 33 (in FIG. Two nozzles, a nozzle 33a and a second critical nozzle 33b) are provided.
The gas introduction chamber 37 is a closed space. The interior of the gas introduction chamber 37 is partitioned by a partition wall 373 into a first chamber 371 on the upstream gas flow path 31 side and a second chamber 372 on the downstream gas flow path 32 side, and the plurality of critical nozzles 33 are arranged in the first chamber. The partition 373 is provided so as to communicate the 371 and the second chamber 372. Specifically, the first critical nozzle 33 a and the second critical nozzle 33 b have their throttle portions 331 a and 331 b exposed to the first chamber 371 of the gas introduction chamber 37 and their diffuser portions 332 a and 332 b of the gas introduction chamber 37. The partition 373 is attached so as to be exposed to the second chamber 372.

  The second chamber 372 of the gas introduction chamber 37 is provided with an open / close valve 36 corresponding to each critical nozzle 33. By operating the open / close valve 36, the critical nozzle 33 is opened (hydrogen gas is in a second state). The state of flowing into the chamber 372) and the closed state (the state where hydrogen gas does not flow into the second chamber 372) can be switched. In the critical nozzle type gas flow meter 3 of FIG. 9, since two critical nozzles 33 (first critical nozzle 33a and second critical nozzle 33b) are used, the first on-off valve 36a corresponding to the first critical nozzle 33a. A second on-off valve 36b corresponding to the second critical nozzle 33b is provided in the second chamber 372. Therefore, by operating the first on-off valve 36a and the second on-off valve 36b, from the first chamber 371 to the second chamber 372 of the gas introduction chamber 37, through the first critical nozzle 33a or the second critical nozzle 33b, or Hydrogen gas can flow through the first critical nozzle 33a and the second critical nozzle 33b.

  Although the structure of the on-off valve 36 is not particularly limited, in the example shown in FIG. 9, the first on-off valve 36a corresponding to the first critical nozzle 33a is exposed to the diffuser portion 332a of the first critical nozzle 33a (exposed to the second chamber 372). A plug portion 361a covering the opening) and an elongated rod portion 362a. One end of the rod portion 362 a is connected to the plug portion 361 a, and the other end of the rod portion 362 a is exposed to the outside of the second chamber 372 of the gas introduction chamber 37. Since the position of the plug portion 361a can be operated from the outside of the gas introduction chamber 37 via the rod portion 362a, the first critical nozzle 33a is opened from the outside of the gas introduction chamber 37 (the diffuser portion 332a is opened and closed first). The state where the valve 36a is not covered) and the closed state of the first critical nozzle 33a (the state where the diffuser portion 332a is covered with the first on-off valve 36a) can be switched. Similarly to the first on-off valve 36a, the second on-off valve 36b corresponding to the second critical nozzle 33b also has a plug portion 361b and a rod portion 362b, and the second critical nozzle 33b is opened from the outside of the gas introduction chamber 37. And can be switched between closed states.

In the critical nozzle type gas flow meter 3 according to the first embodiment shown in FIG. 6, the upstream gas passage 31 has an upstream branch portion 312. If the gas stays in the upstream branch portion 312, there is a possibility that a highly reliable calibration curve cannot be obtained.
On the other hand, in the critical nozzle type gas flow meter 3 according to the second embodiment, the upstream gas flow path 31 and the downstream gas flow path 32 are not branched, so the critical nozzle type gas flow meter 3 according to the first embodiment. A calibration curve with higher reliability than that can be obtained.

(Third embodiment)
FIG. 10 is a schematic diagram showing a critical nozzle type gas flow meter 3 according to the third embodiment used in the present invention.
A critical nozzle gas flow meter 3 according to the third embodiment has both the configuration of the first embodiment and the configuration of the second embodiment.
Specifically, the critical nozzle type gas flow meter 3 according to the third embodiment includes an upstream gas passage 31, a gas introduction chamber 37 connected to the most downstream side of the upstream gas passage 31, and a gas introduction chamber 37. A plurality of critical nozzles 33 provided on the outer wall and downstream gas flow paths 32 connected to the respective critical nozzles 33 are provided. In the present embodiment, the upstream gas flow path 31 is configured only from the upstream single path portion 311, and the downstream gas flow path 32 includes the same number of downstream branch path portions 322 as the number of critical nozzles 33 from upstream to downstream, A downstream single path portion 321 configured by joining the downstream branch path portions 322.
In the present embodiment, the first on-off valve 36 a corresponding to the first critical nozzle 33 a and the second on-off valve 36 b corresponding to the second critical nozzle 33 b are respectively provided in the branch passage portion 322 of the downstream gas passage 32. .

(Fourth embodiment)
FIG. 11 is a schematic view showing a critical nozzle type gas flow meter 3 according to the fourth embodiment used in the present invention.
Similar to the third embodiment, the critical nozzle gas flow meter 3 according to the fourth embodiment has both the configuration of the first embodiment and the configuration of the second embodiment.
Specifically, the critical nozzle type gas flow meter 3 according to the fourth embodiment includes an upstream gas channel 31, a plurality of critical nozzles 33 connected to the most downstream side of the upstream gas channel 31, and each critical nozzle 33. And a downstream gas passage 32 connected to the gas inlet chamber 37. In the present embodiment, the upstream gas flow path 31 has an upstream single path section 311 and an upstream branch path section 312 that branches according to the number of critical nozzles 33, and each critical nozzle 33 has its diffuser. The portion 332 is provided on the outer wall of the gas introduction chamber 37 such that the portion 332 is positioned inside the gas introduction chamber 37. Further, the downstream gas flow path 32 is configured only from the downstream single path portion 321 communicating with the gas introduction chamber 37.
In the present embodiment, the first on-off valve 36a corresponding to the first critical nozzle 33a and the second on-off valve 36b corresponding to the second critical nozzle 33b are respectively provided in the gas introduction chamber 37 as in the second embodiment. ing.

  Also in the second to fourth embodiments, the critical nozzle type gas flowmeter 3 has a plurality of critical nozzles 33, and at least two critical nozzles 33 among the plurality of critical nozzles 33 are different throats. Have a diameter. Therefore, as with the critical nozzle gas flow meter 3 according to the first embodiment, a large number of calibration curves can be obtained by combining the critical nozzles 33. Therefore, the test gas flow meter can be priced over a wide range (wide pressure conditions and wide flow range), and as a result, the accuracy of the gas flow rate measurement value of the built-in gas flow meter is extended over a wide range. An evaluation gas flow meter that can be evaluated with high accuracy is obtained.

The critical nozzle type gas flow meter 3 used in the present invention is not limited to the first to fourth embodiments described above as long as it has a plurality of critical nozzles 33 having different throat diameters. Therefore, the critical nozzle type gas flow meter 3 used in the present invention can divert the configuration of a conventionally known critical nozzle type gas flow meter as it is, except for the configuration of the critical nozzle 33.
For example, in the first to fourth embodiments, as shown in FIGS. 6 and 9 to 11, the gas sensor 34 and the flow rate calculation unit 35 are depicted as separate devices, but the gas sensor 34 uses the flow rate calculation unit 35. You may also serve.

<Test gas flow meter>
An evaluation gas flow meter can be obtained by calibrating and pricing the test gas flow meter using the critical nozzle type gas flow meter of any of the first to fourth embodiments as described above as a standard gas flow meter. When performing calibration and pricing, as shown in FIG. 12, a critical nozzle type gas flow meter 3 which is a standard gas flow meter and a test gas flow meter 4 are connected in series to form a gas flow path. A specific method of calibration and pricing will be described in detail later in the section <Method for adjusting gas flow meter to be detected>.

As the test gas flow meter, a conventionally known gas flow meter capable of measuring the mass flow rate of hydrogen gas can be used. For example, a positive displacement type, an area type, a turbine type, a differential pressure type, an electromagnetic type, a vortex type, A sonic, Coriolis, or thermal gas flow meter can be used.
Preferably, the test gas flow meter is a Coriolis gas flow meter. The Coriolis type gas flow meter is not only a relatively small gas flow meter, but can measure a wide range of gas flow rate under a wide range of pressure conditions.
A gas flow meter for evaluation is produced by calibrating and pricing a Coriolis gas flow meter, which is a gas flow meter to be detected, by the critical nozzle gas flow meter of any of the first to fourth embodiments. be able to. By using this gas flow meter for evaluation, the accuracy of the gas flow rate measurement value of the built-in gas flow meter included in the hydrogen gas dispenser can be evaluated with high accuracy over a wide range.
Hereinafter, the measurement principle of the Coriolis gas flow meter will be briefly described with reference to FIGS. 13 and 14. The Coriolis gas flow meter is a kind of test gas flow meter. However, since it becomes an evaluation gas flow meter depending on the configuration and pricing, in FIG. 13 and FIG. 14, as a symbol indicating the Coriolis gas flow meter. The same symbol “2” as that of the gas flow meter for evaluation is attached.

(Measurement principle of Coriolis gas flow meter)
FIG. 13 is a schematic plan view of the Coriolis gas flow meter 2. As shown in FIG. 13, the Coriolis gas flow meter 2 includes an upstream manifold section 21, a downstream manifold section 22, and a flow tube 23 that connects the upstream manifold section 21 and the downstream manifold section 22.
The upstream manifold portion 21 and the downstream manifold portion 22 are cylindrical members having gas flow paths therein. The end of the flow tube 23 is fixed to the upstream manifold portion 21 and the downstream manifold portion 22. Since the flow tube 23 has flexibility, it vibrates by Coriolis force when a gas flows through the flow tube 23.
The gas flow path of the upstream manifold section 21 and the gas flow path of the downstream manifold section 22 are not directly connected, but are indirectly connected via the flow tube 23. In FIG. 13, a partition wall 24 is provided between the manifold parts 21 and 22 so that gas does not flow directly from the upstream manifold part 21 into the downstream manifold part 22. Accordingly, when a gas is passed through the Coriolis gas flow meter 2, the gas flows in the order of the upstream manifold portion 21, the flow tube 23, and the downstream manifold portion 22.

The flow tube 23 includes a first straight body portion 231 connected substantially vertically to the upstream manifold portion 21, a second straight body portion 232 connected substantially vertically to the downstream manifold portion 22, and an end portion of the first straight body portion 231. U connecting the end of the second straight body 232 (the end opposite to the end connected to the downstream manifold 22) and the end of the second straight body 232 (the end opposite to the end connected to the upstream manifold 21) A character-shaped portion 233.
The first displacement sensor 25 is attached to the end of the U-shaped portion 233 connected to the first straight body portion 231 of the flow tube 23, and the U-shaped portion 233 connected to the second straight body portion 232 is attached. A second displacement sensor 26 is attached to the end, and a vibration device 27 is attached to the tip of the U-shaped part 233. The first displacement sensor 25 and the second displacement sensor 26 are connected to a flow rate calculation unit 28, and the mass flow rate of the gas flowing through the Coriolis gas flow meter 2 is calculated in the flow rate calculation unit 28.
Hereinafter, description will be made with reference to FIG.

FIG. 14 is a schematic side view of the Coriolis gas flow meter 2 in a state in which hydrogen gas is flown (however, for convenience, the vibration device 27 is omitted), the gas is flowed through the Coriolis gas flow meter 2, In addition, the flow tube 23 is vibrated using the vibration device 27.
When a gas is passed through the Coriolis gas flow meter 2 and the flow tube 23 is vibrated, the flow tube 23 exhibits a constant vibration cycle due to the Coriolis force. Specifically, the U-shaped portion 233 of the flow tube 23 changes continuously and periodically to the states of FIGS. 14A to 14D while the gas is flowing. When the flow tube 23 exhibits such a vibration cycle, the first displacement sensor 25 and the second displacement sensor 26 also vibrate (displace), so that the position information measured by the first displacement sensor 25 and the second displacement sensor 26 The measured position information also changes continuously and periodically.
Based on the measurement value of the first displacement sensor 25 and the measurement value of the second displacement sensor 26, the mass flow rate of the gas flowing through the flow tube 23 is calculated by the flow rate calculation unit 28.
As described above, the Coriolis gas flow meter 2 is a device that measures the mass flow rate of the gas by utilizing the fact that the flexible flow tube 23 exhibits a constant vibration cycle due to the Coriolis force.

<Adjustment method of test gas flow meter>
By using the critical nozzle gas flow meter as the standard gas flow meter, the test gas flow meter can be calibrated and priced (adjusted), and as a result, an evaluation gas flow meter can be obtained. Hereinafter, a method for adjusting the test gas flow meter, that is, a method for producing an evaluation gas flow meter will be described.
The adjustment method of the test gas flow meter includes a preparation step of preparing a test gas flow meter to be adjusted and a critical nozzle type gas flow meter, and connecting the test gas flow meter and the critical nozzle type gas flow meter. A gas flow path forming step for forming a gas flow path, a gas introduction process for introducing hydrogen gas into the gas flow path, a gas flow rate measurement value of the test gas flow meter, and a critical nozzle type gas flow meter And a pricing step of correcting the gas flow rate measurement value of the test gas flow meter so that the error of the gas flow rate measurement value is reduced.

(Preparation process)
The preparation step is a step of preparing a critical nozzle type gas flow meter and a test gas flow meter to be adjusted by the critical nozzle type gas flow meter.
As described above, the test gas flowmeter used in the present invention is not particularly limited, but a Coriolis gas flowmeter is preferably used.

(Gas flow path forming process)
The gas flow path forming step is a step of forming a gas flow path by connecting a test gas flow meter and a critical nozzle type gas flow meter. Specifically, as shown in FIG. 12, by connecting the test gas flow meter 4 in series to the upstream gas flow path 31 of the critical nozzle type gas flow meter 3 which is a standard gas flow meter, from upstream to downstream. A gas flow path in which the test gas flow meter 4 and the critical nozzle gas flow meter 1 are connected is formed.
In FIG. 12, the test gas flow meter 4 is connected upstream of the critical nozzle type gas flow meter 3 which is a standard gas flow meter, but the test gas flow meter 4 is connected to the critical nozzle type gas flow rate. It may be connected downstream from the total 3. Whether the test gas flow meter 4 is connected upstream or downstream of the critical nozzle type gas flow meter 3 can be appropriately set in consideration of the properties (pressure resistance, etc.) of the test gas flow meter 4. it can.

(Gas introduction process)
The gas introduction step is a step of introducing hydrogen gas into a gas flow path configured by connecting a test gas flow meter and a critical nozzle type gas flow meter. The introduced hydrogen gas reaches a critical velocity in the throat portion by operating a decompression means (for example, a vacuum pump) included in the critical nozzle type gas flow meter.
By appropriately changing the pressure of the introduced hydrogen gas, a reference flow rate is generated under each pressure condition. Therefore, as described above, a plurality of calibration curves can be obtained based on a combination of each critical nozzle and a plurality of critical nozzles by arbitrarily changing the opening / closing state of the on-off valve of the critical nozzle gas flow meter.
The pressure range of the hydrogen gas to be introduced is not particularly limited. For example, considering the pressure range required by the dispenser of the hydrogen station, the lower limit value of the pressure range of the hydrogen gas to be introduced is preferably 0.5 MPa, more preferably 1.0 MPa, and further preferably 2 MPa. 0.0 MPa, particularly preferably 10 MPa. Further, the upper limit value of the pressure range of the hydrogen gas to be introduced is preferably 120 MPa, more preferably 100 MPa.

(Pricing process)
In the pricing process, the error of the test gas flow meter is corrected so that the error between the gas flow measurement value of the test gas flow meter and the gas flow measurement value of the critical nozzle type gas flow meter is reduced. It is a process of producing.
Specifically, based on a plurality of calibration curves obtained in the gas introduction process, an error between the gas flow measurement value indicated by the gas flow meter to be detected and the gas flow measurement value indicated by the critical nozzle gas flow meter is derived (calibration). Furthermore, the measured gas flow rate of the test gas flow meter is corrected so that this error is reduced. In other words, the gas flow rate measurement value of the test gas flow meter is corrected so that the gas flow rate measurement value indicated by the test gas flow meter and the gas flow rate measurement value indicated by the critical nozzle type gas flow meter become the same value. As a method for correcting the gas flow rate measurement value of the test gas flow meter, for example, a correction coefficient stored in a flow rate calculation unit of the test gas flow meter is changed.
In addition, by using the critical nozzle type gas flowmeter according to the first to fourth embodiments, the maximum number of calibration curves represented by the above formula (1) can be obtained. The flow meter may be calibrated and priced based on all the obtained calibration curves, or may be calibrated and priced based on a plurality of calibration curves selected from the obtained calibration curves. This is because if the number of critical nozzles increases, the number of calibration curves obtained becomes enormous, and it may take too much time to calibrate and price the test gas flowmeter.

  By using the critical nozzle type gas flow meter according to the first to fourth embodiments, a large number of calibration curves can be obtained by a combination of critical nozzles. Therefore, the gas flow measurement value of the test gas flow meter can be calibrated and priced over a wide pressure range and a wide flow range, and as a result, a wide range gas flow rate can be accurately measured under a wide range of pressure conditions. A measurable gas flow meter for evaluation can be produced.

After the pricing process, the test gas flow meter becomes an evaluation gas flow meter. Thereafter, the evaluation gas flow meter can be used as an independent gas flow meter by disconnecting from the critical nozzle gas flow meter which is a standard gas flow meter.
In other words, it can be said that the evaluation gas flow meter has the standard gas flow meter as an accessory until the connection with the standard gas flow meter is released. Specifically, the evaluation gas flow meter has a critical nozzle type gas flow meter, and the critical nozzle type gas flow meter includes a plurality of critical nozzles and an on-off valve provided corresponding to each critical nozzle. It can be said that at least two critical nozzles of the plurality of critical nozzles have different throat diameters.

<Method for evaluating hydrogen gas dispenser>
The present invention is a method for evaluating the accuracy of a gas flow rate measurement value of a built-in gas flow meter, that is, a hydrogen gas dispenser, using an evaluation gas flow meter produced by the above-described procedure.
The hydrogen gas dispenser evaluation method of the present invention comprises a connection step of connecting a gas flow meter for evaluation and a hydrogen gas dispenser equipped with a built-in gas flow meter to form a gas flow path, and hydrogen gas to the gas flow path. Introducing and measuring the flow rate of hydrogen gas using the built-in gas flow meter and the evaluation gas flow meter, the gas flow measurement value (MV) of the built-in gas flow meter and the gas flow measurement of the evaluation gas flow meter And a determination step of determining pass / fail of the built-in gas flow meter based on the error of the value (SV).
Hereafter, each process is demonstrated, referring FIG.1 and FIG.15. FIG. 15 is a flowchart showing the evaluation procedure of the hydrogen gas dispenser.

(Connection process)
The connection step is a step of connecting the evaluation gas flow meter 2 and the hydrogen gas dispenser 1 to form a gas flow path. For example, as shown in FIG. 1, a gas flow path is formed by connecting an evaluation gas flow meter 2 to the nozzle 12 of the hydrogen gas dispenser 1.
This step is a step of preparing an environment in which the built-in gas flow meter 11 and the evaluation gas flow meter 2 provided in the hydrogen gas dispenser 1 can simultaneously measure the flow rate of hydrogen gas. In other words, this step is also a step of connecting the built-in gas flow meter 11 and the evaluation gas flow meter 2 in series (see FIG. 12).
Therefore, the evaluation gas flow meter 2 does not necessarily have to be connected to the nozzle 12 and may be connected to a gas pipe (not shown) through which hydrogen gas flows inside the main body of the hydrogen gas dispenser 1.

(Measurement process)
The measurement step is a step of introducing hydrogen gas into the gas flow path and measuring the flow rate of the introduced hydrogen gas using the built-in gas flow meter 11 and the evaluation gas flow meter 2. By this step, the gas flow rate measurement value (MV) of hydrogen gas by the built-in gas flow meter 11 and the gas flow rate measurement value (SV) of hydrogen gas by the evaluation gas flow meter 2 are detected.

(Judgment process)
The determination step is a step of determining pass / fail of the built-in gas flow meter 11 based on an error between the measured gas flow value (MV) of the built-in gas flow meter 11 and the measured gas flow value (SV) of the evaluation gas flow meter 2. . In this step, if there is a large error between the gas flow rate measurement value (MV) of the built-in gas flow meter 11 and the gas flow rate measurement value (SV) of the evaluation gas flow meter 2, the built-in gas flow meter 11 with respect to a specific hydrogen gas It is determined that the measured gas flow rate is bad, that is, inaccurate.
For example, the pass / fail judgment of the built-in gas flow meter 11 based on the ratio (MV / SV) of the gas flow rate measurement value (MV) of the built-in gas flow meter 11 and the gas flow rate measurement value (SV) of the evaluation gas flow meter 2 Can do. Specifically, when the ratio (MV / SV) is 1, it is determined that the built-in gas flow meter 11 is good because there is substantially no error, and the ratio (MV / SV) is 0 except for 1. If it is within the range of .95 to 1.05, the built-in gas flow meter 11 is determined to be good because there is an error, but the ratio (MV / SV) is 0.95 to 1.05. If it is out of the range, it is determined that the built-in gas flow meter 11 is defective because the error is large.
The permissible range of the ratio (MV / SV) can be appropriately changed according to the accuracy of the gas flow rate measurement value required for the built-in gas flow meter 11, and in addition to 0.95 to 1.05, 0.90 A relatively wide tolerance range of ˜1.10 can be employed, and a relatively narrow tolerance range of 0.98 to 1.02 can be employed.

(Repeated process)
The repeating step is not essential in the present invention, but is preferably a step that is performed after the determination step.
The repeating step is a step of repeatedly performing the measuring step and the determining step after changing the conditions of the hydrogen gas introduced into the gas flow path after the determining step. Changing the conditions of hydrogen gas means changing at least one of the pressure and flow rate of hydrogen gas. By changing the conditions of the hydrogen gas that is the criterion for determination, the accuracy of the gas flow rate measurement value of the built-in gas flow meter 11 can be evaluated over a wide range (wide pressure range and wide flow range). The number of times of repeating the hydrogen gas introduction step and the determination step is not particularly limited, and can be appropriately changed according to the number of conditions of the hydrogen gas to be introduced.
For example, when the first hydrogen gas introduction process introduces low pressure and high flow hydrogen gas (see point iii in FIG. 3) and determines whether the built-in gas flow meter 11 is good or bad, Hydrogen gas at a flow rate in pressure (see point i or point ii in FIG. 3) is introduced to determine whether the built-in gas flow meter 11 is good or bad. 3), the quality of the built-in gas flow meter 11 is judged.
The pressure and flow rate of the hydrogen gas to be introduced are not particularly limited. For example, the pressure of hydrogen gas may be 10 MPa or more and 40 MPa or less (low pressure), may be more than 40 MPa and 80 MPa or less (medium pressure), may be more than 80 MPa and 120 MPa or less (high pressure). . Further, the flow rate of hydrogen gas may be 0.1 kg / min to 1.0 kg / min (low flow rate), may exceed 1.0 kg / min and not more than 2.0 kg / min (medium flow rate). , More than 2.0 kg / min and 5.0 kg / min or less (high flow rate).

  When the repetitive process is performed x times, the quality determination is finally performed x + 1 times (hereinafter, the number of quality determinations finally performed is referred to as y. Y = x + 1). The number of quality determinations (y) to be finally performed is not particularly limited, but the accuracy of the gas flow rate measurement value of the built-in gas flow meter 11 is evaluated over a wide range (wide pressure range and wide flow range). Therefore, preferably y is 3 or more, more preferably 5 or more, and particularly preferably 8 or more. However, since it takes too much time to evaluate the built-in gas flow meter 11 when the number of pass / fail judgments (y) is too large, y is preferably 20 or less, more preferably 15 or less, and particularly preferably 10 or less. It is.

(Comprehensive evaluation process)
A comprehensive evaluation process is a process performed after performing a repetition process. The comprehensive evaluation step is a step of comprehensively evaluating the quality of the built-in gas flow meter 11 based on a plurality of quality determination results obtained through the repetition process.
Specifically, the comprehensive evaluation step is a step of making a comprehensive pass / fail determination of the built-in gas flow meter 11 based on the final pass / fail determination count (y) and the failure determination count (z).
For example, the overall quality of the built-in gas flow meter 11 can be determined by the ratio (z / y) of the number of times of defect determination (z) to the number of times of final quality determination (y). For example, if the ratio is 1/5 or less, the built-in gas flow meter 11 is determined to be comprehensively good, and if the ratio exceeds 1/5, the built-in gas flow meter 11 is generally determined to be defective. it can.
The value of the ratio (z / y) that serves as a reference for comprehensively determining good can be appropriately changed according to the accuracy of the gas flow rate measurement value required for the built-in gas flow meter 11, for example, 1/5 or less In addition, a relatively moderate value such as 1/3 or less can be adopted, and a relatively severe value such as 1/10 or less can be adopted.

  The evaluation method of the hydrogen gas dispenser of the present invention is an evaluation gas flow meter calibrated and priced using a critical nozzle type gas flow meter (standard gas flow meter) having at least two critical nozzles having different throat diameters. Is used. Therefore, the accuracy of the gas flow measurement value of the built-in gas flow meter can be evaluated with high accuracy over a wide range (wide pressure range and wide flow range).

  Hereinafter, the present invention will be further described with reference to examples. However, the present invention is not limited only to the following examples. The critical nozzle type gas flowmeter used in the present invention was produced by constructing the following traceability system.

(Calibration and pricing using a primary standard critical nozzle gas flow meter)
(National Institute of Technology) A critical nozzle type gas flow meter (hereinafter referred to as critical nozzle type gas flow meter A) owned by the National Institute of Advanced Industrial Science and Technology was prepared as a primary standard. The critical nozzle type gas flow meter A includes one critical nozzle having a throat diameter of 2.4 mm. The pressure range of the critical nozzle type gas flow meter A that can be priced is 0.6 MPa or less, and the flow rate range that can be priced is 0.1 kg / min or less.
Subsequently, a critical nozzle type gas flow meter (hereinafter referred to as a critical nozzle type gas flow meter B), which is an object of calibration and pricing, was prepared. The critical nozzle type gas flow meter B includes ten critical nozzles having the same throat diameter of 2.4 mm as the critical nozzle type gas flow meter A.
A critical nozzle type gas flow meter A, which is a primary reference, was connected upstream of the critical nozzle type gas flow meter B, and pricing was performed using hydrogen gas. In this way, the critical nozzle type gas flow meter B was calibrated and priced using the primary standard critical nozzle type gas flow meter A, so that the critical nozzle type gas flow meter B was made the 2.1 order reference.
2. The pressure range that can be calibrated and priced for the critical nozzle type gas flow meter B of the primary standard was 0.6 MPa or less, and the flow rate range that could be calibrated and priced was 1.0 kg / min or less.

(Calibration and pricing using 2.1 standard nozzle critical gas flow meter)
Subsequently, a critical nozzle type gas flow meter (hereinafter referred to as a critical nozzle type gas flow meter C), which is an object of further calibration and pricing, was prepared. The critical nozzle type gas flow meter C includes ten critical nozzles having a throat diameter of 3.6 mm. The critical nozzle of the critical nozzle type gas flow meter C has a pressure resistance and is larger than the critical nozzles provided in the primary standard and 2.1 standard critical nozzle type gas flow meters.
A critical nozzle type gas flow meter B, which is the 2.1st order standard, was connected downstream of the critical nozzle type gas flow meter C, and pricing was performed using hydrogen gas. Thus, by calibrating and pricing the critical nozzle type gas flow meter C using the 2.1 order standard critical nozzle type gas flow meter B, the critical nozzle type gas flow meter C is changed to the 2.2 order standard. did.
The pressure range in which the calibration and pricing of the critical nozzle type gas flow meter C of the second order standard was 0.9 MPa or less, and the flow rate range in which calibration and pricing were possible was 3.6 kg / min or less.

(Calibration and pricing using a critical nozzle type gas flow meter of 2.2 standard)
Subsequently, a critical nozzle type gas flow meter (hereinafter referred to as a critical nozzle type gas flow meter D), which is an object of further calibration and pricing, was prepared. The critical nozzle type gas flow meter D includes five critical nozzles having different throat diameters, and the throat diameters are 1.95 mm, 1.25 mm, 0.94 mm, 0.67 mm, and 0.48 mm in this order. It was. The critical nozzle of the critical nozzle type gas flow meter D has a pressure resistance and is larger than the critical nozzle provided in the 1st to 2.2th order critical nozzle type gas flow meter.
A critical nozzle type gas flow meter C which is a 2.2 order reference or a critical nozzle type gas flow meter B which is a 2.1 order reference is connected downstream of the critical nozzle type gas flow meter D and is calibrated using hydrogen gas. Priced. In this way, by calibrating and pricing the critical nozzle type gas flow meter D using the 2.2 order standard critical nozzle type gas flow meter C and the 2.1 order standard critical nozzle type gas flow meter B, A critical nozzle gas flow meter (2.3th order standard), which is a standard gas flow meter used in the present invention, was produced.
The prepared standard gas flow meter (critical nozzle type gas flow meter) had a pressure range of 87.5 MPa or less, and the flow rate range that could be calibrated and priced was 3.6 kg / min or less.

(2.3 Calibration and pricing using a 3rd order critical nozzle gas flow meter)
Using the fabricated 2.3th-order critical nozzle gas flow meter (standard gas flow meter), the Coriolis gas flow meter, which is the test gas flow meter, was calibrated and priced, and the evaluation gas flow meter (3 Next standard) was prepared.
In this embodiment, the standard gas flow meter (critical nozzle type gas flow meter) has five critical nozzles having different throat diameters, so that a maximum of 31 calibration curves can be obtained by combining critical nozzles. it can. Therefore, the test gas flow meter could be calibrated and priced under a wide range of pressure conditions and a wide range of gas flow rates.
When the evaluation of the hydrogen gas dispenser (evaluation of the built-in gas flow meter provided in the hydrogen gas dispenser) was performed using the obtained gas flow meter for evaluation, the gas flow rate measurement value of the built-in gas flow meter was highly accurate. I was able to evaluate.

DESCRIPTION OF SYMBOLS 1 ... Hydrogen gas dispenser, 11 ... Built-in gas flow meter, 12 ... Nozzle, 2 ... Gas flow meter for evaluation, 3 ... Standard gas flow meter (critical nozzle type gas flow meter), 31 ... Upstream gas flow path, 32 ... Downstream Gas flow path, 33 ... critical nozzle, 34 ... gas sensor, 35 ... flow rate calculation unit, 36 ... open / close valve, 37 ... gas introduction chamber

Claims (5)

A connection step of connecting a gas flow meter for evaluation and a hydrogen gas dispenser equipped with a built-in gas flow meter to form a gas flow path;
A measuring step of introducing hydrogen gas into the gas flow path and measuring the flow rate of the hydrogen gas using the built-in gas flow meter and the evaluation gas flow meter;
A determination step of determining pass / fail of the built-in gas flow meter based on an error between the measured gas flow value (MV) of the built-in gas flow meter and the measured gas flow value (SV) of the evaluation gas flow meter. Evaluation method of gas dispenser.
However, the gas flow meter for evaluation uses hydrogen gas on the basis of a standard gas flow meter having at least two critical nozzles having different throat diameters and open / close valves provided corresponding to the respective critical nozzles. Used and calibrated and priced.   In the determination step, a ratio (MV / SV) of a gas flow rate measurement value (MV) of the built-in gas flow meter and a gas flow rate measurement value (SV) of the evaluation gas flow meter is 0.95 to 1.05. The method for evaluating a hydrogen gas dispenser according to claim 1, which is a step of determining that the built-in gas flow meter is defective when it is out of range. A repeating step of repeatedly performing the measurement step and the determination step by changing the conditions of the hydrogen gas introduced into the gas flow path;
The overall evaluation step of performing a comprehensive pass / fail determination of the built-in gas flowmeter based on the final pass / fail determination count (y) and failure determination count (z) obtained through the repetition step. The evaluation method of the hydrogen gas dispenser of 1 or 2.   When the ratio (z / y) of the number of times of defect judgment (z) to the number of times of final judgment (y) in the comprehensive evaluation step exceeds 1/5, the built-in gas flow meter is totally defective. The method for evaluating a hydrogen gas dispenser according to claim 3, wherein the method is a step of determining that   The method for evaluating a hydrogen gas dispenser according to claim 1, wherein the gas flow meter for evaluation is a Coriolis gas flow meter.

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