JP2007192683A - Method of forming highly accurate flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a highly accurate flowmeter which can measure the flow of gas only, although the flow contains water vapor. <P>SOLUTION: A second flowmeter superior in measuring accuracy to a first flowmeter is mounted in a pipe body on the downstream side of the first flowmeter along a gas supply passage where a value for the flow is detected by the first flowmeter mounted in the pipe body. The flow of the gas not containing water vapor is computed from the detecting output of the second flowmeter. The value for the flow detected by the first flowmeter is corrected from the computation result of the flow. The corrected value for the flow is used as an output value for the first flowmeter. A third flowmeter is mounted therein instead of the second flowmeter. A value for the flow detected by the third flowmeter is corrected from the output value for the first flowmeter. The corrected value for the flow is used as an output value for the third flowmeter. The corrected value for the flow by the first flowmeter and the corrected value for the flow by the third flowmeter are each equivalent to the value for the flow of the gas not containing water vapor. The third flowmeter removed from the pipe body serves as the highly accurate flowmeter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming a high-precision flow meter, and more particularly to a method for forming a high-precision flow meter suitable for forming a flow rate of hydrogen gas.

  For example, a fuel cell is configured by supplying air to the air electrode (plus electrode) and supplying hydrogen to the fuel electrode (minus electrode). A fuel cell having such a structure has come to be known as a battery having extremely high conversion efficiency because oxygen in the air reacts with the hydrogen and electric energy is directly generated from the reaction.

  In order to control the supply amount of the hydrogen in the path for supplying hydrogen to the fuel electrode of the fuel cell, for example, a flow meter is provided in the middle of a pipe from a hydrogen cylinder. It is normal to carry out actual operation based on this.

  In this case, since the conversion efficiency of the fuel cell is high, the flow rate of the hydrogen gas that is the reactant is expected to be an accurate value. Therefore, an accurate value is required in the measurement value of the flow meter. Needless to say.

The hydrogen supply path in such a fuel cell system is described in detail, for example, in Patent Document 1 below.
JP-A-7-37598

  Here, in the measurement of the flow rate of hydrogen gas by the flow meter described above, it has been found that the measured value is not accurate, and the cause is the water vapor contained in the hydrogen gas.

  This is because the hydrogen gas containing water vapor has a molar mass of hydrogen that is 1/10 that of water vapor, and water vapor can be a sufficient error factor in the flow measurement of the hydrogen gas.

  Therefore, the present applicant is in the process of inventing a flow rate measurement method capable of accurately measuring the flow rate of only the gas that does not contain water vapor even though it contains water vapor, and thus Apart from the method of accurately measuring the flow rate of gas only, can the flow meter itself that can accurately measure the flow rate of only the gas be easily formed and applied to a hydrogen gas supply path such as a fuel cell system as it is? Has been studied and its realization has been requested. This is because a flow meter manufactured for the purpose of high accuracy is generally expensive, and using it for a fuel cell system or the like makes the system itself expensive.

  The present invention has been made based on such circumstances, and the object thereof is a method of forming a high-accuracy flow meter that can measure the flow rate of only gas that does not contain water vapor even though it contains water vapor. Is to provide.

  Another object of the present invention is to provide a method of forming a highly accurate flow meter comparable to a so-called standard flow meter.

  Another object of the present invention is to provide a method for forming the high-accuracy flow meter with a very simple configuration and an extremely simple operation.

   Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

(1) A method for forming a high-accuracy flow meter according to the present invention includes, for example, a gas supply path through which a gas is supplied through a tube and the flow rate value of the gas is detected by a first flow meter attached to the tube. There,
A step of attaching a second flow meter having better measurement accuracy than the first flow meter to the pipe body on the downstream side of the first flow meter;
A step of calculating the flow rate of the gas not containing water vapor from the detection output of the second flow meter;
Correcting the flow value detected by the first flow meter from the calculation result of the flow rate of the gas, and using the corrected flow value as the output value of the first flow meter;
Replacing the second flow meter with a third flow meter attached to the pipe;
Correcting the flow value detected by the third flow meter from the output value of the first flow meter, and using the corrected flow value as the output value of the third flow meter;
Both the corrected flow value in the first flow meter and the corrected flow value in the third flow meter are values corresponding to the flow value of the gas not containing water vapor, and are removed from the tube. The third flow meter is obtained as a high accuracy flow meter.

(2) The method for forming a high-accuracy flow meter according to the present invention includes, for example, a first flow meter that is supplied with gas through a tubular body and is attached to the tubular body, and an output from the first flow meter. A gas supply path having a detection circuit for detection;
A gas that calculates the flow rate of a gas that does not contain water vapor from the output of the second flow meter, and a second flow meter that has better measurement accuracy than the first flow meter, in the tubular body downstream of the first flow meter. A process of arranging a flow extraction circuit;
The first flow meter calculates a difference value between the gas flow rate value calculated by the gas flow rate extraction circuit and the flow rate value from the detection circuit, and then calculates the difference value from the flow rate value from the detection circuit. Performing a subtracted correction, and using the corrected flow rate value as an output value of the first flow meter;
In place of the second flow meter and the gas flow extraction circuit, a step of attaching a third flow meter to the tube;
Correcting the flow value detected by the third flow meter from the output value of the first flow meter, and using the corrected flow value as the output value of the third flow meter;
Both the corrected flow value in the first flow meter and the corrected flow value in the third flow meter are values corresponding to the flow value of the gas not containing water vapor, and are removed from the tube. The third flow meter is obtained as a high accuracy flow meter.

(3) The method for forming a high-precision flow meter according to the present invention is based on, for example, the configuration of (1) or (2), and the calculation of the gas flow rate is detected by the second flow meter. It is characterized by performing using at least a flow rate value, pressure, temperature, and humidity.

(4) The method for forming a high-accuracy flow meter according to the present invention is based on, for example, the configuration of (1), and the first flow meter is provided with a correction circuit that corrects its detection output. Correction of the detected flow rate value is performed by the correction circuit.

(5) The method for forming a high-accuracy flow meter according to the present invention is based on, for example, the configuration of (2). The correction circuit calculates a difference value between the flow rate value of the gas that does not contain water vapor and the flow rate value from the detection circuit, and then corrects the difference value from the flow rate value of the detection circuit. It is characterized by.

(6) A method for forming a high-accuracy flow meter according to the present invention is based on, for example, the configuration of (2) or (5), and the difference value is stored in a memory. Correction is performed to subtract the difference value stored in.

(7) The method for forming a high-accuracy flow meter according to the present invention is based on, for example, the configuration of (2), and the gas flow rate extraction circuit is configured by a microcomputer.

(8) The method for forming a high-accuracy flow meter according to the present invention is premised on, for example, the configuration of either (1) or (2), and the second flow meter is configured as a standard flow meter. To do.

(9) The method for forming a high-accuracy flow meter according to the present invention is based on the configuration of (1), for example, and the third flow meter is provided with a correction circuit for correcting the detection output thereof. Correction of the detected flow rate value is performed by the correction circuit.

(10) The method for forming a high-accuracy flow meter according to the present invention is based on the configuration of (2), for example, and the third flow meter is provided with a correction circuit for correcting the detected output, and the output of the first flow meter The correction circuit calculates a difference value between the value and the flow rate value from the detection circuit and then subtracts the difference value from the flow rate value of the detection circuit.

(11) The method for forming a high-accuracy flow meter according to the present invention is based on, for example, the configuration of either (1) or (2), and the third flow meter has the first flow rate in its physical and electrical circuit configuration. It is characterized by the same physical and electrical circuit configuration of the meter.

(12) A method for forming a fuel cell test system according to the present invention includes, for example, a gas supply path in which a gas is supplied through a tube and the flow rate value of the gas is detected by a first flow meter attached to the tube. There,
A step of attaching a second flow meter having better measurement accuracy than the first flow meter to the pipe body on the downstream side of the first flow meter;
A step of calculating the flow rate of the gas not containing water vapor from the detection output of the second flow meter;
Correcting the flow value detected by the first flow meter from the calculation result of the flow rate of the gas, and using the corrected flow value as a flow output value of the first flow meter;
Replacing the second flow meter with a fuel cell attached to the tube;
A process of measuring an operation output value detected by the fuel cell from a flow output value of the first flow meter, and using the measured flow output value and the operation output value as a performance test result of the fuel cell; ,
Both the corrected flow rate value in the first flow meter and the output value detected in the fuel cell are obtained as values corresponding to the flow rate value of the gas not containing water vapor.

  In addition, this invention is not limited to the above structure, A various change is possible in the range which does not deviate from the technical idea of this invention.

  Embodiments of a method for forming a high-precision flow meter according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram to which an embodiment of a method for forming a high-precision flow meter according to the present invention is applied, for example, a configuration diagram showing a fuel cell test (evaluation) system.

  First, there is a hydrogen gas cylinder 1, and the hydrogen gas in the hydrogen gas cylinder 1 is a standard flow meter equipped with a general-purpose flow meter F disposed in the middle of the tube 2, a humidification source 3, and a pure gas flow extraction circuit according to the present invention. The fuel cell is supplied to the fuel cell side (not shown) through the SF. Here, “pure gas flow rate” means “flow rate of gas not containing water vapor”. The standard flow meter SF may be installed at a fuel cell installation location.

  Here, the flow meter F is configured to be always installed in the pipe body 2. On the other hand, the standard flow meter SF is attached to the tube body 2 when the present invention is applied. That is, the standard flow meter SF is removed from the tube 2 after the present invention is applied, and is not configured as one of the components in the fuel cell system. Yes.

  This standard flow meter SF is configured to be able to measure the flow value extremely accurately compared to the flow meter F, and also detects the pressure, temperature and humidity of the fluid, Since it has a function of extracting a gas flow rate not included, the configuration is more complicated than the flow meter F, and the price is more expensive than the flow meter F. Therefore, in order to accurately measure the hydrogen gas in the fuel cell test system, it is very convenient to use the standard flow meter SF as it is incorporated in the fuel cell test system. However, as the fuel cell test system, Since it is unavoidable that the price is high, it is configured to be removed from the tubular body 2 after the present invention is applied as described above. The standard flow meter SF is usually configured to have an accuracy exceeding a specified level as the name indicates. However, in application of the present invention, the standard flow meter SF is more than the flow meter F. If the measurement accuracy is good, this can be applied. This is because, as will be described later, in this fuel cell test system, accurate flow measurement of pure hydrogen gas (gas not containing water vapor) directly depends on the accuracy of the standard flow meter SF.

  Further, the humidification source 3 is provided for the necessity of a fuel cell in which a battery part (cell stack) for reacting hydrogen and oxygen stably operates in a humid environment. However, as another embodiment, the humidification source 3 is not necessarily provided in the middle of the tubular body 2. Even when the humidification source 3 is not present, the hydrogen gas from the hydrogen gas cylinder 1 may contain water vapor in the middle of the piping. Nevertheless, the present invention is pure hydrogen gas excluding the water vapor. This is because it is intended to accurately measure the flow rate. That is, even if the humidification source 3 does not exist, there is water vapor that cannot be completely removed in the pipe body 2 from the hydrogen gas cylinder 1 to the standard flow meter SF. Because.

  The flow meter F is composed of, for example, a mass flow meter (thermal flow meter), and has a mechanism for preventing the humidification source, the high-precision flow meter, or the moisture resulting from removal of the fuel cell from flowing back to the flow meter F. Therefore, it is not necessary to use a measurement accuracy higher than that of the standard flow meter SF. In this flow meter F, for example, the output from the detection electrode of the thermal flow meter disposed in the tube 2 is input to the detection circuit 4, and the flow rate of hydrogen gas flowing through the flow meter F by the detection circuit 4 Is calculated. Here, the flow rate value of the hydrogen gas calculated by the flow meter F is not the flow rate value of the pure hydrogen gas that does not contain water vapor in the hydrogen gas cylinder 1, but in the pipe from the hydrogen gas cylinder 1 to the flow meter F. The flow rate is affected by the existing water vapor. Since it is very convenient to control the fuel cell system based on the flow rate value of pure hydrogen gas not containing water vapor, the flow rate value calculated by the detection circuit 4 is then used as the correction circuit 5. It is comprised so that it may correct | amend by. In this embodiment, the circuit composed of the detection circuit 4 and the correction circuit 5 is referred to as a pure gas flow rate detection circuit 6. This is because the purpose of the pure gas flow rate detection circuit 6 is not to obtain the output from the detection circuit 4, but to correct the output and output the pure gas flow rate value.

  The correction circuit 5 includes, for example, a first memory 7, a first arithmetic circuit 8, a second memory 9, and a second arithmetic circuit 10. The first memory 7 stores an output value (flow value) from a pure gas flow extraction circuit 14 (to be described later) that calculates the flow value of pure hydrogen gas based on the output from the standard flow meter SF. Information corresponding to the stored flow rate value is input to the first arithmetic circuit 8.

On the other hand, information corresponding to the detected flow rate value from the detection circuit 4 is also input to the first arithmetic circuit 8. The flow rate value of this information and the flow rate value of the information stored in the first memory 7 are also input. Is calculated by the first calculation circuit 8. The difference value is output to and stored in the second memory 9. Thereafter, the flow value from the detection circuit 4 is input to the second arithmetic circuit 10, and the second arithmetic circuit 10 subtracts the difference value stored in the second memory 9 from the flow value. The subtracted value is output as the output of the correction circuit 5, that is, as the output of the pure gas flow rate detection circuit 6. Thereby, the flow rate value corrected by the correction circuit 5 becomes a flow rate value of only pure hydrogen gas not containing water vapor, and the value is displayed on the display device 11.

  After the output value from the pure gas flow rate extraction circuit 14 described later is stored in the first memory 7 of the pure gas flow rate detection circuit 6, both the pure gas flow rate extraction circuit 14 and the standard flow meter SF are required. As shown in FIG. 3, the fuel cell test system is configured by removing the pure gas flow rate extraction circuit 14 and the standard flow meter SF. This is because at this time, the flow meter F has been calibrated as having a measurement accuracy based on the measurement accuracy of the standard flow meter SF.

  Next, each configuration of the standard flow meter SF and the pure gas flow extraction circuit will be described below. The standard flow meter SF detects the flow rate Q of hydrogen gas (including water vapor) in the pipe body 2 to which the standard flow meter SF is attached by the detection circuit 13. In this case, the standard flow meter SF includes sensors that detect the pressure P, temperature T, and absolute humidity ha of the fluid to be measured, and outputs corresponding to the pressure P, temperature T, and absolute humidity ha of these sensors. The value is a parameter for calculating the pure hydrogen gas (without water vapor) flow rate Qgvn.

  The outputs from the detector 13, that is, the output values corresponding to the flow rate Q, the pressure P, the temperature T, and the absolute humidity ha are input to the pure gas flow rate extraction circuit 14, respectively. Yes.

  The pure gas flow extraction circuit 14 is composed of, for example, a microcomputer, and is sequentially operated in steps shown in FIG. Hereinafter, the operation of the pure gas flow extraction circuit 14 will be described in the order of steps.

  Step ST1: The molar fraction Xv of the wet gas is obtained. Here, the wet gas refers to hydrogen gas containing water vapor.

  The wet gas molar fraction Xv is calculated based on the following equation (1).

Xv = (ha · Ru · T) / (P · Nvap) (1)
Here, Nvap is the molar mass of water vapor (= 0.0180150 kg / mol), Ru is the universal gas constant (= 8.31451J / (K · mol)), P is the gas pressure (Pa [abs]), and T is the gas Temperature (K) and ha are absolute humidity (kg / m ₃ ).

  The gas pressure P, gas temperature T, and absolute humidity ha are each calculated from the output from the sensor provided in the standard flow meter SF.

  Step ST2: The molar mass Ngas of the pure gas in the wet gas is obtained. First, from the molar fraction Xv obtained in step ST1, the molar mass N of the wet gas can be decomposed as shown in the following formula (2).

N = Ndry × (1−Xv) + Nvap · Xv (2)
Here, Ndry is the molar mass (kg / mol) of the dry gas. Since this dry gas is a hydrogen gas containing no impurities, it is a predetermined value.

  And the molar mass Ngas of only pure gas is calculated based on following Formula (3).

Ngas = Ndry × (1-Xv) (3)
Step ST3: Obtain an actual density value ρgas of pure gas. This density value ρgas is calculated based on the following equation (4).

ρgas = (Ngas · P) / (Ru · Z · T) (4)
Here, Z is a compression coefficient.

  Step ST4: A mass flow value Qgm of pure gas is obtained. This mass flow value Qgm is calculated based on the following equation (5).

Qgm = ρgas × Q (5)
Here, Q is a volumetric flow rate value (L / min), which is a flow rate value obtained from the standard flow meter SF.

  Step ST5: Determine the normal volume flow rate value Qgvn of the pure gas. The normal volume flow rate value Qgvn is calculated based on the following equation (6).

Qgvn = Qgm / ρgn (6)
Here, ρgn is the density (g / L) of gas under standard (normal) conditions, and is determined as a default value.

  The normal volume flow value Qgvn obtained in this way is obtained as the output of the pure gas flow extraction circuit 14 and stored in the first memory 7 incorporated in the pure gas flow detection circuit 6 of the flow meter F as described above. It has come to be. In this embodiment, the pure gas flow rate extraction circuit 14 is shown as an arithmetic circuit performed by a microcomputer. However, the present invention is not limited to this and may be configured as a dedicated digital circuit. Needless to say. In addition, when the structure of the flow meter F is a simple one that does not include the correction circuit 5, the flow output value Qm (F) may be directly adjusted to the calibration value Qgm. Nor.

  Thereby, the flowmeter F comes to output only the flow value of the gas from which the influence of water vapor is eliminated. Since the flow meter F can be calibrated with a gas flow value that does not contain water vapor by the standard flow meter SF in a timely manner, the flow rate of so-called pure gas can be measured with extremely high accuracy. .

  Furthermore, the use of another flow meter SF with better measurement accuracy than the flow meter F, such as the standard flow meter SF, is temporary (use when correcting the output value of the flow meter F), After that, the pipe body 2 is detached and the flowmeter F provided in the pipe body 2 is used for accurate measurement, so that it is not necessary to use an expensive flowmeter in this measurement. .

  In the case described above, only the gas pressure P, gas temperature T, and absolute humidity ha obtained from the standard flow meter SF are taken into account to obtain the output (flow rate value) from the pure gas flow extraction circuit 14 by calculation. It is a thing. This is to cause the standard flow meter SF to accurately calculate the flow rate of pure hydrogen gas only. That is, since the standard flow meter SF can extract only the flow rate value of the gas not containing water vapor, regardless of changes in the gas pressure P, the gas temperature T, and the absolute humidity ha after passing through the humidification source 3, The detection output is corrected to obtain a flow rate value of pure hydrogen gas. As a rule of thumb, when there is no humidification source upstream of the flow meter F or when there is a stable humidification source, the change in the error correction amount that water vapor has on the flow meter F is gradual, and the amount of change is also extremely high. It is based on smallness.

  Furthermore, when the ability to measure pressure, temperature, and humidity is added to the flow meter F, the flow meter can cope with an unstable humidification source upstream of the flow meter F. As an aspect of this embodiment, for example, the gas pressure, gas temperature, and absolute humidity measured by the flow meter F are grouped in respective set ranges, and the pure gas obtained from the standard flow meter SF for each group. Each flow rate value from the flow rate extraction circuit 14 is stored in the first memory 7. Thereafter, when the standard flow meter SF is removed from the pipe body 2 and the flow rate is measured by the flow meter F, the flow rate value Qm (F) first obtained by the flow meter F is changed to the gas pressure, gas temperature, Then, an approximate group is selected from the above-described groups based on the absolute humidity, a flow value corresponding to the measured flow value Qm (F) is selected in the selected group, and the first calculation is performed using the selected flow value. Needless to say, the circuit 8 and the second arithmetic circuit 10 may be operated. In other words, each flow rate value measured by the standard flow meter SF is mapped and stored in the first memory 7. That is, each flow rate value is stored according to each division of gas pressure, gas temperature, and absolute humidity simultaneously measured by the flow meter F. After that, when the standard flow meter SF is removed and measurement is performed by the flow meter F, the flow rate value stored in the section is corrected according to the measured gas pressure, gas temperature, and absolute humidity. Is to be done. When configured in this manner, even if the gas pressure, gas temperature, and absolute humidity flowing into the flow meter F change, an appropriate flow rate value corresponding to the change can be calculated.

  Further, as another aspect of the embodiment, one or two of gas pressure, gas temperature, and absolute humidity are removed from each aspect described above, and pure gas flow rate extraction is performed by the remaining two or one. Needless to say, the configuration may be such that the output from the circuit is calculated, and in this case, the above-described aspects may be applied.

  In the above-described embodiments, the standard flow meter SF arranged in the fuel cell test system is described as a volumetric flow meter. However, it is needless to say that the present invention is not limited to a volumetric flow meter and can be similarly applied to a mass flow meter. FIG. 4 shows a configuration diagram corresponding to FIG. 1 in this case. 1 differs from the case of FIG. 1 in that the standard flow meter SF disposed on the downstream side of the humidification source 3 is a mass flow meter, and the configuration of the pure gas flow extraction circuit 14 is only slightly different. It has become a thing. That is, the pure gas flow rate extraction circuit 14 operates as in the flowchart shown in FIG. 5 and corresponds to FIG. 2 described above. In the case of FIG. 2, the mass flow value Qgm of the pure gas is calculated in step ST4, and the normal volume flow value Qgvn is calculated from the mass flow value Qgm. In the case of FIG. The mass flow rate Q is obtained by obtaining the mass flow rate Qm and the actual density ρ from the standard flow meter SF, and the same processing is performed thereafter.

  In the case of such a configuration, as in the case of FIG. 1, the first arithmetic circuit 8 uses the flow value detected by the flow meter F and the flow value from the pure gas flow extraction circuit 14 on the standard flow meter SF side. The second arithmetic circuit 10 performs an operation of subtracting the difference value from the flow rate value detected by the flow meter F.

  FIG. 7 shows the fuel cell test system in which the measurement accuracy of the flow meter F that is always provided is improved by applying the above-described embodiment, and then the fuel cell test system is used as it is. It is the block diagram which showed the Example of the method of obtaining flow meter F 'which has a measurement precision of a grade.

  The flowmeter F ′ whose measurement accuracy is improved by using this embodiment is removed from the fuel cell test system, and thereafter, in another similar fuel cell test system or in such a fuel cell test system. It can be used as a permanent flow meter in a hydrogen gas supply path that is not limited.

  FIG. 7 shows the fuel cell test system shown in FIG. 3, for example, in which the flow meter F always provided has already been improved by the calibration with the standard flow meter SF. It is the figure which showed the state by which flowmeter F 'was deployed to the pipe body 2. As the location where the flow meter F ′ is provided, for example, the location where the standard flow meter SF is used for improving the measurement accuracy of the flow meter F is used. The standard flow meter SF is attached for the purpose of being temporarily installed in the tube body 2, and the tube body 2 at the attachment location is configured to facilitate the same. This is because the configuration is suitable for deploying the total F ′.

  In this embodiment, the flow meter F 'has the same configuration as that of the flow meter F provided in the fuel cell system. That is, the flow meter F is also configured to include the detection circuit 4 ′ and the correction circuit 5 ′, and both the mechanical configuration and the electrical circuit configuration are the same. In this case, it is needless to say that the configuration of the flow meter F ′ may be slightly different from the flow meter F as another embodiment, but the standard flow meter as in this embodiment may be used. By using the same configuration for the flow meter F and the flow meter F ′ excluding SF, it is not necessary to distinguish between the uses of the flow meter F and the flow meter F ′, and the manufacturing process is also performed in a separate process. Can be avoided.

  Accordingly, when the flow meter F ′ is, for example, a thermal flow meter, the flow meter F ′ includes a detection circuit 4 ′ connected to an electrode disposed in the tube body 2, and the detection circuit 4 ′ includes information detected by the electrode. Based on the above, the flow rate of the hydrogen gas in the tube body 2 is detected. In this case, when the hydrogen gas contains water vapor, the detection circuit 4 ′ is not equipped with an expensive water vapor detection circuit in the flow meter F ′ as in the flow meter F, but the first memory 7 As in the flow meter F, “has a function that can store a so-called pure gas flow rate value of only gas that does not contain water vapor. Therefore, until the flow meter F ′ is arranged in the pipe body 2 and information (information corresponding to the flow value of pure hydrogen gas) is input from the flow meter F side as described later, in this embodiment, For example, no other information is input to the first memory 7 ′. However, as another embodiment, even if other information is stored in advance, when the information is input from the flow meter F side, the new information can be rewritten in this way. It goes without saying.

  In the first arithmetic circuit 8 ′, the difference value between the information stored in the first memory 7 ′ and the output information from the detection circuit 4 ′ is calculated, and the information of the difference value obtained thereby is the second memory. 9 'is stored. The information on the difference value stored in the second memory 9 'is input to the second arithmetic circuit 10'. The output from the detection circuit 4 ′ is also input to the second arithmetic circuit 10 ′, and the second arithmetic circuit 10 ′ performs an operation for subtracting the difference value from the output value of the detection circuit 4 ′. The calculation result is displayed on the display device 11 ′.

  Further, in the flow meter F ′ having a communication function, after the pipe body 2 is arranged, the output from the correction circuit 5 on the flow meter F side is stored in the first memory 7 ′ on the flow meter F ′ side. Connect each other as you can. The output from the correction circuit 5 of the flow meter F is a flow value of pure hydrogen gas not containing water vapor. By storing this flow value in the first memory 7 ′ on the flow meter F ′ side, the flow meter F ′. The correction circuit 5 ′ on the side calculates a flow rate (corresponding to the difference value) affected by water vapor, and thereafter, an operation for subtracting this flow rate from the output value from the detection circuit 4 ′ is performed. A value obtained by this calculation is a flow rate value of pure hydrogen gas not containing water vapor, and is displayed on the display device 11 '.

  Thus, the flow meter F ′ thus formed has the following characteristics, and is removed from the above fuel cell system and used in another similar fuel cell test system or such a fuel. It can be used in a hydrogen gas supply path that is not limited to a battery system.

  If the flowmeter F ′ has reproducibility, it is calibrated with the flow rate value excluding the flow rate due to the influence of water vapor. Under the same conditions, it is possible to form a high-accuracy flow meter that can measure the flow rate of pure gas only. Since the calibration of the flow meter F 'is performed based on the output value of a high precision flow meter such as a so-called standard flow meter, a high precision flow meter traceable with the standard flow meter can be formed. When the correction circuit 5 ′ is not mounted, the flow meter F ′ is calibrated by adjusting the flow rate output value directly in accordance with the calibration value. If the correction circuit 5 ′ described above is provided, it is only necessary to store appropriate information in the correction circuit 5 ′. Therefore, a highly accurate flow meter can be formed by an extremely simple operation.

  FIG. 8 shows that the fuel cell test system shown in FIG. 3 is already improved by the calibration method shown in FIG. 1 is a configuration diagram of a fuel cell test system showing a case where a fuel cell 20 is installed in the fuel cell test system. Since the output of the fuel cell 20 in this case can be obtained as a value corresponding to the flow rate of hydrogen that does not contain water vapor indicated by the flow meter F, the fuel that can accurately measure the output of the fuel cell 20 A battery test system can be obtained.

  In each of the above-described embodiments, the fuel electronic system is described as an example of the hydrogen gas supply path. However, the present invention is not limited to the fuel cell test system, and it goes without saying that the present invention can be applied to the hydrogen gas supply path in other systems. This is because, in other hydrogen gas supply paths, there is a demand to accurately measure the flow rate of pure hydrogen gas not containing water vapor.

  Each of the embodiments described above may be used alone or in combination. This is because the effects of the respective embodiments can be achieved independently or synergistically.

It is a figure which shows one Example of the formation method of the high precision flow meter by this invention, Comprising: It is explanatory drawing which shows one process applied to a high precision flowmeter calibration system or a fuel cell test system. It is a flowchart which shows one Example of operation | movement of the pure gas flow volume extraction circuit shown in FIG. It is a figure which shows one Example of the formation method of the high precision flowmeter by this invention, Comprising: It is explanatory drawing which shows the process following FIG. 7 or FIG. It is a figure which shows the other Example of the formation method of the high precision flowmeter by this invention, Comprising: It is explanatory drawing which shows the one stroke applied to a high precision flowmeter calibration system or a fuel cell test system. It is a flowchart which shows one Example of operation | movement of the pure gas flow volume extraction circuit shown in FIG. It is a figure which shows the other Example of the formation method of the high precision flowmeter by this invention, Comprising: It is explanatory drawing which shows the process following FIG. 7 or FIG. It is a figure which shows one Example of the formation method of the high precision flow meter by this invention, Comprising: It is explanatory drawing which shows formation of a high precision flow meter. It is a figure which shows one Example of a fuel cell test by the method similar to the formation method of the high precision flowmeter by this invention, Comprising: It is explanatory drawing which shows the performance test of a fuel cell.

Explanation of symbols

F ...... Flow meter (installed in tube 2: first flow meter), SF ... Standard flow meter (removable from tube: second flow meter), F '... Flow meter (third flow meter) 1) Hydrogen gas cylinder, 2 ... Tube, 3 ... Humidification source, 4, 4 ', 13 ... Detection circuit, 5, 5' ... Correction circuit, 6 ... Pure gas flow rate detection circuit, 7 , 7 ′... First memory, 8, 8 ′... First arithmetic circuit, 9, 9 ′... Second memory, 10, 10 ′... Second arithmetic circuit, 11, 11 ′. 14: Pure gas flow extraction circuit.

Claims (12)

In a gas supply path in which gas is supplied through a pipe body, and a flow rate value of the gas is detected by a first flow meter attached to the pipe body,
A step of attaching a second flow meter having better measurement accuracy than the first flow meter to the pipe body on the downstream side of the first flow meter;
A step of calculating the flow rate of the gas not containing water vapor from the detection output of the second flow meter;
Correcting the flow value detected by the first flow meter from the calculation result of the flow rate of the gas, and using the corrected flow value as the output value of the first flow meter;
Replacing the second flow meter with a third flow meter attached to the pipe;
Correcting the flow value detected by the third flow meter from the output value of the first flow meter, and using the corrected flow value as the output value of the third flow meter;
Both the corrected flow value in the first flow meter and the corrected flow value in the third flow meter are values corresponding to the flow value of the gas not containing water vapor, and are removed from the tube. A method for forming a high-precision flow meter, wherein the third flow meter is obtained as a high-precision flow meter. A gas supply path having a first flow meter attached to the tube and a detection circuit for detecting a flow rate value based on an output from the first flow meter;
A gas that calculates the flow rate of a gas that does not contain water vapor from the output of the second flow meter, and a second flow meter that has better measurement accuracy than the first flow meter, in the tubular body downstream of the first flow meter. A process of arranging a flow extraction circuit;
The first flow meter calculates a difference value between the gas flow rate value calculated by the gas flow rate extraction circuit and the flow rate value from the detection circuit, and then calculates the difference value from the flow rate value from the detection circuit. Performing a subtracted correction, and using the corrected flow rate value as an output value of the first flow meter;
In place of the second flow meter and the gas flow extraction circuit, a step of attaching a third flow meter to the tube;
Correcting the flow value detected by the third flow meter from the output value of the first flow meter, and using the corrected flow value as the output value of the third flow meter;
Both the corrected flow value in the first flow meter and the corrected flow value in the third flow meter are values corresponding to the flow value of the gas not containing water vapor, and are removed from the tube. A method for forming a high-precision flow meter, wherein the third flow meter is obtained as a high-precision flow meter.   The high-accuracy flow meter according to claim 1, wherein the calculation of the gas flow rate is performed using at least a flow value, pressure, temperature, and humidity detected by the second flow meter. Forming method.   2. The high flow rate measuring apparatus according to claim 1, wherein the first flow meter is provided with a correction circuit that corrects a detection output thereof, and the correction of the flow value detected by the first flow meter is performed by the correction circuit. Formation method of precision flow meter.   The first flow meter is provided with a correction circuit for correcting the detection output, and calculates a difference value between the flow rate value of the gas not containing water vapor calculated by the gas flow rate extraction circuit and the flow rate value from the detection circuit, 3. The method for forming a high-precision flow meter according to claim 2, wherein the correction for subtracting the difference value from the flow rate value of the detection circuit is performed by the correction circuit.   6. The high-precision flow meter according to claim 2, wherein the difference value is stored in a memory, and correction is performed to subtract the difference value stored in the memory from a flow rate value of a detection circuit. Forming method.   3. The method for forming a high-precision flow meter according to claim 2, wherein the gas flow rate extraction circuit comprises a microcomputer.   The method for forming a high-accuracy flow meter according to claim 1, wherein the second flow meter is configured as a standard flow meter.   2. The high flow rate measurement apparatus according to claim 1, wherein the third flow meter is provided with a correction circuit that corrects a detection output thereof, and the correction of the flow value detected by the third flow meter is performed by the correction circuit. Formation method of precision flow meter.   The third flow meter is provided with a correction circuit for correcting the detection output, and calculates a difference value between the output value of the first flow meter and the flow value from the detection circuit, and then from the flow value of the detection circuit. The method for forming a high-accuracy flow meter according to claim 2, wherein the correction for subtracting the difference value is performed by the correction circuit.   3. The high-precision flow meter according to claim 1, wherein the third flow meter has the same physical and electrical circuit configuration as that of the first flow meter. Forming method. In a gas supply path in which gas is supplied through a pipe body, and a flow rate value of the gas is detected by a first flow meter attached to the pipe body,
A step of attaching a second flow meter having better measurement accuracy than the first flow meter to the pipe body on the downstream side of the first flow meter;
A step of calculating the flow rate of the gas not containing water vapor from the detection output of the second flow meter;
Correcting the flow value detected by the first flow meter from the calculation result of the flow rate of the gas, and using the corrected flow value as a flow output value of the first flow meter;
Replacing the second flow meter with a fuel cell attached to the tube;
A process of measuring an operation output value detected by the fuel cell from a flow output value of the first flow meter, and using the measured flow output value and the operation output value as a performance test result of the fuel cell; ,
The corrected flow value in the first flow meter and the output value detected in the fuel cell are both obtained as values corresponding to the flow value of the gas not containing water vapor. .

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