JP7780432B2 - Calorie measuring device and calorie calculation method - Google Patents

Description

The present invention relates to, for example, a gas calorific value measuring device and a calorific value calculation method, and in particular to a calorific value measuring device and a calorific value calculation method for paraffinic hydrocarbon gases that contain interference gases that become error components.

Conventionally, commonly available natural gas is primarily composed of paraffinic hydrocarbon gas and contains interference gases (miscellaneous gases) such as nitrogen ( _N2 ), carbon monoxide (CO), and carbon dioxide ( _CO2 ), which can cause errors in calorific value measurements.

Here, when measuring the calorific value of the natural gas, the calorific value _of paraffinic hydrocarbon gases (e.g., methane gas ( _CH4 ), ethane gas ( _C2H6 ), propane gas ( _C3H8 ), butane gas ( _{n - C4H10} ), etc.) can be measured because the calorific value and refractive index, and the calorific value and thermal conductivity are proportional to each other.

Furthermore, for miscellaneous gases such as nitrogen ( _N2 ), carbon monoxide (CO), and carbon dioxide ( _CO2 ), there is no proportional relationship between the calorific value and the refractive index, nor between the calorific value and the thermal conductivity. However, it has been found that the influence (error) on the calorific value calculation can be almost completely eliminated by performing calculations using both the calorific value converted to the refractive index and the calorific value converted to the thermal conductivity (see, for example, Patent Document 1).

Patent No. 5308842

However, since there is no proportional relationship between the calorific value and the thermal conductivity of hydrogen gas (H ₂ ), errors cannot be eliminated by conventional calculation processing. Therefore, when calculating the calorific value of a paraffinic hydrocarbon gas containing hydrogen gas, the presence of hydrogen gas (gas) is a major error factor.

Furthermore, even in the case of gases containing nitrogen ( _N2 ) or carbon monoxide (CO), the calorimetric measurement device described in Patent Document 1 requires both a thermal conductivity measurement means and a refractive index measurement means, which hinders progress in miniaturization and price reduction through simplified configuration.

The present invention has been made in consideration of the above-mentioned problems, and aims to provide a calorific value measuring device and a calorific value calculation method that can accurately measure the calorific value of natural gas containing hydrogen gas as a primary interfering gas, while also being compact and inexpensive.

The present invention relates to a calorimetry device for measuring the calorific value of a target gas, the calorimetry device measuring the calorific value of the target gas, the calorific value being provided with a thermal conductivity converted calorific value measuring means capable of measuring the calorific value obtained from the thermal conductivity of the target gas, the target gas being composed mainly of a first gas and containing a second gas which becomes a measurement error component, and the thermal conductivity converted calorific value measuring means calculates the calorific value obtained from the thermal conductivity of the target gas based on a relational expression showing the correlation between the output measured by the thermal conductivity measuring means and the actual calorific value, the relational expression being obtained in advance for a plurality of the first gases which serve as references, and the second gas. and a heat quantity measuring device for measuring the calorific value of the target gas by correcting an error due to the thermal conductivity of the target gas, the heat quantity measuring device comprising a correction device and a converted heat quantity calculating device, the correction device comprising a difference calculating device that calculates a difference between a first output and a second output measured for the target gas by applying different voltages to the thermal conductivity measuring device, and a corrected output value calculating device that calculates a corrected output value for the target gas based on the difference, and the converted heat quantity calculating device calculates the heat quantity of the target gas based on the corrected output value and the relational expression .
The present invention also provides a calorimetry measuring device for measuring the calorific value of a target gas, comprising a thermal conductivity converted calorific value measuring means capable of measuring the calorific value obtained from the thermal conductivity of the target gas, wherein the target gas is composed mainly of a first gas and contains a second gas that is a measurement error component, the first gas being a paraffinic hydrocarbon gas, and the second gas being any one of hydrogen gas, carbon dioxide gas, and nitrogen gas, and the thermal conductivity converted calorific value measuring means calculates the calorific value of the target gas by correcting the measured output of the target gas for an error due to the second gas, based on a relational equation indicating the correlation between the output measured by the thermal conductivity measuring means, which is obtained in advance for a plurality of first gases that serve as references, and the actual calorific value.

The present invention also provides a calorific value calculation method for calculating the calorific value of a gas, wherein the target gas contains a first gas as a main component and a second gas that is a measurement error component, and the calorific value of the target gas is calculated by correcting an error due to the second gas with respect to the measured output of the target gas based on a relational equation showing the correlation between a measured value of thermal conductivity of the first gas obtained in advance for a plurality of reference gases and an actual calorific value, the calorific value of the target gas being calculated, the calorific value calculation method comprising the steps of applying a first voltage to a thermal conductivity measuring means to measure the target gas and obtain a first output, applying a second voltage to the thermal conductivity measuring means to measure the target gas and obtain a second output, obtaining a corrected output value of the target gas based on the difference between the first output and the second output, and calculating the calorific value of the target gas based on the corrected output value and the relational equation.
The present invention also provides a calorific value calculation method for calculating the calorific value of a gas, wherein a target gas contains a first gas as a main component and a second gas that becomes a measurement error component, the first gas being a paraffinic hydrocarbon gas, and the second gas being any one of hydrogen gas, nitrogen gas, and carbon dioxide gas, and the calorific value of the target gas is calculated by correcting an error due to the second gas for the measured output of the target gas based on a relational equation showing a correlation between a measured value of thermal conductivity obtained in advance for the first gas among a plurality of reference gases and an actual calorific value.

The present invention also provides a calorific value measuring device for measuring the calorific value of a target gas, comprising: a thermal conductivity converted calorific value measuring means capable of measuring a thermal conductivity converted calorific value obtained from the thermal conductivity of the target gas; a refractive index converted calorific value measuring means capable of measuring a refractive index converted calorific value obtained from the refractive index of the target gas; and a calorific value calculating means, wherein the target gas is composed mainly of a first gas and contains a third gas and a fourth gas that become measurement error components; the thermal conductivity converted calorific value measuring means is configured to calculate the thermal conductivity converted calorific value by correcting an error due to the third gas based on a relational expression showing a correlation between the output measured by the thermal conductivity measuring means for a plurality of the first gases and the actual calorific value; and the calorific value calculating means calculates the calorific value of the target gas using the thermal conductivity converted calorific value, the refractive index converted calorific value, and a coefficient for correcting an error due to the fourth gas.
The calorimetric device is characterized by the above.

The present invention also provides a calorific value calculation method for measuring the calorific value of a gas, wherein the target gas contains a first gas as its main component and a third gas and a fourth gas that are measurement error components, and the method comprises the steps of: calculating the calorific value obtained from the thermal conductivity of the target gas (hereinafter referred to as the "thermal conductivity converted calorific value") by correcting the error due to the third gas based on a relational equation showing the correlation between the measured thermal conductivity value and the actual calorific value for a plurality of the first gases; acquiring the calorific value obtained from the refractive index of the target gas (hereinafter referred to as the "refractive index converted calorific value"); and calculating the calorific value of the target gas using the thermal conductivity converted calorific value, the refractive index converted calorific value, and a coefficient that corrects the error due to the fourth gas.

The present invention also provides a program for causing a computer to execute the above-mentioned calorie calculation method.

The present invention provides a calorific value measuring device and a calorific value calculation method that can accurately measure the calorific value of natural gas, which primarily contains hydrogen gas as an interfering gas, while also being compact and inexpensive.

1 is a schematic diagram showing the configuration of a calorimetry device according to a first embodiment of the present invention. 1A and 1B are graphs showing the relationship between the calorific value and the output of a thermal conductivity meter, illustrating a method for correcting errors in hydrogen gas in the calorific value measuring device according to the first embodiment of the present invention, where (A) is the graph before correction and (B) is the graph after correction. 1A and 1B are graphs showing the relationship between the calorific value and the output of a thermal conductivity meter, illustrating a method for correcting errors in nitrogen gas in the calorific value measuring device according to the first embodiment of the present invention, where (A) is the graph before correction and (B) is the graph after correction. 10A and 10B are schematic diagrams showing the configuration of a calorimetry device according to a second embodiment of the present invention, in which FIG. 10A is a schematic diagram showing the overall configuration, and FIG. 10B is a schematic diagram showing a refractive index converted calorie calculation means. 10A and 10B are graphs showing the relationship between calorific value and the output of a thermal conductivity meter, illustrating a method for correcting errors for interference gases in a calorific value measuring device according to a second embodiment of the present invention, where (A) is a graph before correction of errors for hydrogen gas, and (B) is a graph after correction. 10A and 10B are graphs for explaining a method for correcting errors due to interference gases in a calorimetry device according to a second embodiment of the present invention, where FIG. 10A is a graph showing the relationship between calorie and refractive index, and FIG. 10B is a graph showing the relationship between calorie and the output of a thermal conductivity meter. 10 is a graph showing the relationship between the actual calorific value after correcting for errors due to interference gases in the calorific value measuring device according to the second embodiment of the present invention and the measurement results in the calorific value measuring device. 10 is a graph showing the relationship between the output difference of the normalized output due to the difference in applied voltage of the thermal conductivity measuring means in the calorimeter according to the second embodiment of the present invention and the measured concentration of hydrogen gas. 10 is a graph showing the relationship between the normalized output of the thermal conductivity measuring means and the applied voltage in the calorimeter according to the second embodiment of the present invention. 10A and 10B are diagrams illustrating a method for measuring a calorie quantity using a calorie measuring device according to a third embodiment of the present invention, in which (A) is a graph showing an output-voltage function, and (B) is a graph showing a slope-voltage function. 10A and 10B are diagrams illustrating a method for measuring the calorific value of a calorimeter according to a third embodiment of the present invention, in which (A) is a graph showing a H ₂ proportion-voltage curve, and (B) is a graph showing an output- _{H 2} proportion function. FIG. 10 is a diagram for explaining a method for measuring the calorific value of the calorific value measuring device according to the third embodiment of the present invention, and is a graph showing the relationship between the hydrogen gas concentration and a value based on the normalized output. FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. FIG. 10 is a schematic diagram showing the configuration of a calorimetry device according to a third embodiment. FIG. 10 is a schematic diagram showing the configuration of a calorimetry device according to a third embodiment. 11 is a graph showing the relationship between the calculated heat quantity and the actual heat quantity in the third embodiment. 11 is a graph showing the relationship between the calculated heat quantity and the actual heat quantity in the third embodiment. 11 is a graph showing the relationship between the calculated heat quantity and the actual heat quantity in the third embodiment. 11 is a graph showing the relationship between the calculated heat quantity and the actual heat quantity in the third embodiment. FIG. 10 is a schematic diagram showing a first configuration of a hydrogen gas concentration calculation device according to a fourth embodiment of the present invention. FIG. 10 is a schematic diagram showing a second configuration of a hydrogen gas concentration calculation device according to a fourth embodiment of the present invention. 10 is a graph showing measurement results obtained by a second configuration of the hydrogen gas concentration calculation device according to the fourth embodiment of the present invention. FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. 10 is a graph showing measurement results obtained by the first configuration of the hydrogen gas concentration calculation device according to the fourth embodiment of the present invention. FIG. 10 is a schematic diagram showing a third configuration of a hydrogen gas concentration calculation device according to a fourth embodiment of the present invention. 10 is a graph showing measurement results obtained by a third configuration of the hydrogen gas concentration calculation device according to the fourth embodiment of the present invention. 10 is a table illustrating a measurement experiment using a third configuration of the hydrogen gas concentration calculation device according to the fourth embodiment of the present invention. 10 is a graph showing measurement results obtained by the first configuration of the hydrogen gas concentration calculation device according to the fourth embodiment of the present invention. 10 is a graph showing measurement results obtained by a third configuration of the hydrogen gas concentration calculation device according to the fourth embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
First Embodiment
First, a first embodiment of the present invention will be described with reference to Figures 1 to 3. Figure 1 is a block diagram that schematically shows an example of the configuration and functions of a calorimetry device 10 according to the first embodiment.

The calorific value measuring device 10 measures the calorific value of a target gas flowing, for example, through a gas pipeline 11 in the direction of the arrow in Figure 1, and includes a thermal conductivity converted calorific value measuring means 12 capable of measuring the calorific value obtained from the thermal conductivity of the target gas, and an output means 18. The gas pipeline 11 and the thermal conductivity converted calorific value measuring means 12 are connected by a gas flow path 19, and the target gas in the gas pipeline 11 is supplied to the thermal conductivity converted calorific value measuring means 12. The thermal conductivity converted calorific value measuring means 12 is disposed, for example, within an explosion-proof container 50.

Here, the gas to be measured by the calorific value measuring device 10 of this embodiment (target gas) is, for example, natural gas or biogas just produced from a gas field, and more specifically, a gas containing a first gas as the main component and a second gas that contributes to measurement error. More specifically, the first gas is, for example, a paraffinic hydrocarbon gas (e.g., methane gas (CH4), ethane gas ( _C2H6 ), propane gas ( _C3H8 ), butane gas (n- _C4H10 ), etc.) whose calorific value, thermal conductivity, and refractive index have a specific correspondence relationship (specifically, the thermal conductivity is inversely proportional to the calorific value, and the refractive index is proportional to the calorific value), and the second gas is any one of hydrogen gas ( _H2 ), nitrogen gas ( _N2 ), and carbon _dioxide ( _{CO2 ) ,} whose calorific value, thermal conductivity, and refractive index do not have _a specific correspondence relationship.

The thermal conductivity converted calorific value measuring means 12 has a thermal conductivity measuring means 13, and calculates the calorific value of the target gas by correcting for errors due to the second gas based on a relational equation showing the correlation between the output measured by the thermal conductivity measuring means, which is obtained in advance for multiple reference first gases, and the actual calorific value. The thermal conductivity converted calorific value measuring means 12 has, for example, a thermal conductivity measuring means 13, a correction means 14 for realizing the calorific value measurement function, and a converted calorific value calculation means 15.

The thermal conductivity measuring means 13 is a conventionally known thermal conductivity calorimeter that can measure the thermal conductivity of the target gas using a signal (voltage applied to the thermal conductivity measuring means 13) output from an external device (such as a power supply) 17.

The correction means 14 has a difference calculation means 141 and a correction output value calculation means 142, and has the function of correcting the error caused by the presence of a second gas when calculating the calorific value of the target gas.

The converted heat quantity calculation means 15 has the function of acquiring (calculating) the heat quantity of the target gas based on a relational expression showing the correlation between the output of the thermal conductivity measurement means 13 and the actual heat quantity. For target gases consisting only of a first gas (paraffinic hydrocarbon gas), the output measured by the thermal conductivity measurement means 13 and the actual heat quantity have a predetermined correlation; however, if the first gas contains a second gas (interfering gas), the resulting error results in a value that deviates from this correlation. Therefore, the correction means 14 corrects the output measured by the thermal conductivity measurement means 13, and the converted heat quantity calculation means 15 calculates the heat quantity of the target gas based on the corrected value.

Although not shown in the figure, the calorific value measuring device 10 has a known configuration including a data transmission path, calculation means, control means, memory means, etc., and these work together with the various means (functions) of the thermal conductivity conversion calorific value measuring means 12 to measure and calculate the target gas.

The calculated calorific value can be output to the outside via the output means 18. The output means 18 is, for example, a display means, a printing means, or a transmission means capable of outputting (transmitting) predetermined data via communication with the outside. The calorific value measuring device 10 may also be provided with a separate communication means capable of transmitting and receiving predetermined data to and from external devices.

Referring to Figure 2, the correction of errors due to the inclusion of a second gas will be described. This figure is a graph showing the relationship between the output of the thermal conductivity measuring means 13 and the actual calorific value for multiple types of reference gases (reference gases), with (A) being the graph before correction for errors due to the inclusion of the second gas, and (B) being the graph after correction. The vertical axis represents the calorific value [MJ/ ^Nm3 ] (hereinafter also referred to as "true calorific value") of each reference gas obtained by analysis using, for example, a gas chromatograph, and the horizontal axis represents the output results of measurement of each reference gas by the thermal conductivity measuring means 13. Here, the case where the second gas is hydrogen gas is shown as an example.

The "reference gases" are all mixed gases in which methane gas is added with another component at different ratios, and refer to gases whose composition (concentration, mixing ratio) and true calorific value are known. The other components added are paraffinic hydrocarbon gases, such as ethane, propane, and butane, and hydrogen gas. The methane gas concentration is 100 vol% to 80 vol%, and the concentrations of the other components are 0 vol% to 20 vol%. Note that in the figure, the output measured by the thermal conductivity measuring means 13 for a gas with a methane gas concentration of 100 vol% (pure methane gas) is "0," and the output of the thermal conductivity measuring means 13 is standardized (normalized) so that the output and true calorific value are shown to have an approximately linear relationship. In other words, the thermal conductivity meter output on the horizontal axis in the figure is the standardized (normalized) output X _T.C. of the thermal conductivity measuring means 13. In this embodiment, this is sometimes referred to as "normalized output X _T.C. " or simply "output X _T.C. " In the figure, as the normalized output X _T.C. moves away from the point "0" (increases or decreases), the concentration of methane gas decreases in increments of 2.5 vol%, and the concentration of the added component increases.

1A is a plot of the output (normalized output) X _T.C of the thermal conductivity measuring means 13 when the voltage applied to the thermal conductivity measuring means 13 is 0.5 V, the output (normalized output) X _T.C of the thermal conductivity measuring means 13 when the voltage applied to the thermal conductivity measuring means 13 is 1.0 V, and the true calorific value of each, for these multiple types of reference gases.

Specifically, the plots marked with triangles represent the results for a mixed gas of methane and ethane gas (CH ₄ —C ₂ H ₆ ) when the applied voltage is 1.0 V. In this case, mixed gases in which the methane gas concentration decreases in increments of 2.5 vol% (97.5 vol% methane gas - 2.5 vol% ethane gas, 95 vol% methane gas - 5 vol% ethane gas, 92.5 vol% methane gas - 7.5 vol% ethane gas, etc.) are shown as the output _XT.C on the horizontal axis increases from "0" (pure methane gas).

The plots marked with a triangle represent the results for a mixed gas of methane and ethane gas (CH ₄ -C ₂ H ₆ ) when an applied voltage of 0.5 V is used. As the output _XT.C on the horizontal axis increases from "0" (pure methane gas), mixed gases are shown in which the methane gas concentration decreases in 2.5 vol% increments (97.5 vol% methane gas - 2.5 vol% ethane gas, 95 vol% methane gas - 5 vol% ethane gas, 92.5 vol% methane gas - 7.5 vol% ethane gas, etc.).

Similarly, the plots marked with squares represent the results for a mixed gas of methane and propane gas (CH ₄ -C ₃ H ₈ ) when an applied voltage of 1.0 V is used, the plots marked with double squares represent the results for a mixed gas of methane and propane gas (CH ₄ -C ₃ H ₈ ) when an applied voltage of 0.5 V is used, the plots marked with diamonds represent the results for a mixed gas of methane and butane gas (CH ₄ -C ₄ H ₁₀ ) when an applied voltage of 1.0 V is used, and the plots marked with diamonds represent the results for a mixed gas of methane and butane gas (CH ₄ -C ₄ H ₁₀ ) when an applied voltage of 0.5 V is used.

The plots marked with circles indicate the results for a mixed gas of methane and hydrogen gas (CH ₄ -H _{2 ) when an applied voltage of 1.0 V is used, and the plots marked with black circles indicate the results for a mixed gas of methane and hydrogen gas (CH 4 -H 2 ) when} an applied voltage of 0.5 V is used. When hydrogen gas (interference gas) is added, mixed _gases are shown in which the methane gas concentration decreases in 2.5 vol% increments (97.5 vol% methane gas - 2.5 vol% hydrogen gas, 95 vol% methane gas - 5 vol% hydrogen gas, 92.5 vol% methane gas - 7.5 vol% hydrogen gas, etc.) as the output X T.C on the horizontal axis decreases from "0" (pure methane gas).

As shown in Figure 1A, in the case of a reference gas consisting only of paraffinic hydrocarbon gas, the output XT.C and true calorific value of the thermal conductivity measuring means 13 increase as the amount of components added to the methane gas increases, regardless of the gas components. On the other hand, in the case of a reference gas (( _CH4 - _H2 ) gas) in which an interference gas (hydrogen gas) is added to methane gas, the output _XT.C and true calorific value of the thermal conductivity measuring means 13 decrease as the amount of hydrogen _gas component increases.

Furthermore, in the case of a reference gas consisting only of paraffinic hydrocarbon gas, regardless of differences in the gas components, there is generally no (small) difference in the output _XT.C due to differences in the voltage applied to the thermal conductivity measuring means 13, whereas in the case of a reference gas containing hydrogen gas ((CH ₄ -H ₂ ) gas), a difference occurs in the output _XT.C (an output difference occurs), and it was found that the output difference is linear with respect to the concentration of hydrogen gas.

Based on these findings, the applicant believed that it would be possible to calculate the calorific value of a target gas in which methane gas is mixed with hydrogen gas, even if the concentration of the contained hydrogen gas is unknown, by correcting for errors due to hydrogen gas, and thus achieved the present invention.

The calorific value measuring device 10 (e.g., the thermal conductivity converted calorific value measuring means 12) acquires in advance a relational expression (a linear relational expression shown by a solid line in FIG. 2) that indicates the correlation between the output _XT.C from the thermal conductivity measuring means 13 and the true calorific value for a reference gas consisting solely of paraffinic hydrocarbon gas, and stores the relational expression in a storage means. The relational expression is shown in the following Equation 1, and hereinafter this relational expression will be referred to as the "calorific value calculation equation."
is.

2, in the case of a reference gas containing hydrogen gas, the plot deviates from the straight line of the calorific value calculation formula, and therefore the correction means 14 corrects the output _XT.C of the thermal conductivity measuring means 13 so that the plot fits onto the straight line of the calorific value calculation formula. In detail, the correction means 14 has a difference calculation means 141 that calculates the difference (output difference) between the outputs _XT.C measured by applying different voltages to the thermal conductivity measuring means 13 for a certain target gas, and a corrected output value calculation means 142 that calculates a corrected output value of the target gas using a correction formula set based on the difference (see FIG. 1).

The difference calculation means 141 calculates the difference (hereinafter referred to as the "output difference") between the first output obtained by applying a first voltage (e.g., 1.0 V) to the thermal conductivity measuring means 13 and the second output obtained by applying a second voltage (e.g., 0.5 V).

The corrected output value calculation means 142 corrects the output _XT.C (measurement result of the first output) of the thermal conductivity measurement means 13 when the first voltage is applied using a correction formula based on the output difference. The correction formula is set according to the type of the second gas and is stored in the storage means of the calorimetry device 10 (e.g., the thermal conductivity converted calorimetry measurement means 12). For example, the correction formula for finding the corrected output value (hereinafter referred to as the "corrected output value ( _H2 )") when the second gas is hydrogen gas is shown in Equation 2 below.
is.

2B shows the result of plotting the corrected output value (H ₂ ) as normalized output _XT.C on the horizontal axis for a reference gas containing hydrogen gas. This correction corrects the error when hydrogen gas is included, and the plot of the reference gas ((CH ₄ -H ₂ ) gas) containing hydrogen gas is placed on the straight line of the calorific value calculation formula (Equation 1). In other words, in actual measurement of the target gas, the converted calorific value calculation means 15 calculates the calorific value QA of the target gas by substituting the corrected output value (H ₂ ) for the output _XT.C of the calorific value calculation formula based on the corrected output value (H ₂ ) and the calorific value calculation formula of Equation ₁ (a linear relationship shown by a straight line in FIG. 2B). The calculated calorific value is configured to be output via output means 18.

Next, the calorific value calculation method of this embodiment will be described. First, a relational expression (calorific value calculation expression (Equation 1)) showing the correlation between the measured value (output X _T.C ) by the thermal conductivity measuring means 13 and the actual calorific value is obtained for a reference gas consisting only of a plurality of paraffinic hydrocarbon gases (a mixed gas obtained by adding other paraffinic hydrocarbon gases to methane gas in different proportions) from among various reference gases. Specifically, the first gas is, for example, a plurality of (CH ₄ -C ₂ H ₆ ) gases having different concentrations of methane gas and ethane gas, a plurality of (CH ₄ -C ₃ H ₈ ) gases having different concentrations of methane gas and propane gas, or a plurality of (CH ₄ -C ₄ H ₁₀ ) gases having different concentrations of methane gas and butane gas.

Here, the concentrations of the other components are, for example, 0 vol% to 20 vol%, and are changed in increments of 2.5 vol% (the concentration of methane gas is, for example, 100 vol% to 80 vol%).

For each of these first gases, the true calorific value of each mixed gas obtained by analysis using, for example, a gas chromatograph and the output measured by the thermal conductivity measuring means 13 are obtained. The output of the thermal conductivity measuring means 13 is then normalized so that the output of a gas with a methane gas concentration of 100 vol% (pure methane gas) is "0" and a nearly linear relationship is shown between the output and the true calorific value, and a calorific value calculation formula (Equation 1) showing the correlation between the two is obtained (see the solid line in Figure 2(A)).

Next, during measurement, the target gas (e.g., methane gas containing hydrogen gas) flowing through the gas pipeline 11 is supplied to the thermal conductivity converted calorific value measuring means 12 via the gas flow path. The thermal conductivity converted calorific value measuring means 12 then calculates the calorific value of the target gas based on the calorific value calculation formula (Equation 1 above), correcting for errors caused by the second gas (hydrogen gas). This calorific value is the calorific value obtained from the thermal conductivity, and can also be referred to as the thermal conductivity converted calorific value.

Specifically, a first voltage (e.g., 1.0 V) is applied to the thermal conductivity measuring means 13 to measure the target gas and obtain a first output. Next, a second voltage (e.g., 0.5 V) is applied to the thermal conductivity measuring means 13 to measure the same target gas and obtain a second output.

Next, the difference (output difference) between the first output and the second output is calculated. Then, a correction formula set for each type of second gas (in the case of hydrogen gas, the correction formula 2 above) is used to calculate a corrected output value ( _H2 ) of the target gas (normalized output _XT.C of the thermal conductivity measuring means 13 after correcting for errors due to hydrogen gas). Then, the corrected output value ( _H2 ) is substituted for the normalized output _XT.C in the calorific value calculation formula (Formula 1) to calculate the calorific value _QA of the target gas (see FIG. 2(B)).

The above example shows the case where the second gas (interfering gas) is hydrogen gas, but the same procedure can be carried out even if the second gas is nitrogen gas or carbon dioxide gas.

3 is a diagram illustrating the correction of errors due to the inclusion of a second gas when the second gas is nitrogen gas, and is a graph showing the relationship between the output result of the thermal conductivity measuring means 13 corresponding to FIG. 2 and the true calorific value. (A) in FIG. 3 is the graph before correction of errors due to the inclusion of a second gas in various reference gases, and (B) in FIG. 3 is the graph after correction. The graph is the same as FIG. 2 except that hydrogen gas is replaced with nitrogen gas. The plots marked with a ▽ symbol in the graph represent the results for a reference gas ((CH ₄ -N ₂ ) gas) in which nitrogen gas is contained in methane gas when the applied voltage is 1.0 V, and the plots marked with a ▼ symbol represent the results for a reference gas ((CH ₄ -N ₂ ) gas) when the applied voltage is 0.5 V.

In this case, as well, the process is similar to that for hydrogen gas, and detailed description will be omitted, but based on FIG. 3A, a relational equation (calorific value calculation equation (Equation 1)) showing the correlation between the measurement value (output X _T.C ) of the thermal conductivity measuring means 13 and the actual calorific value (true calorific value) is obtained for a reference gas consisting of only a plurality of paraffinic hydrocarbon gases (a mixed gas in which methane gas is added with other paraffinic hydrocarbon gases in different proportions) from among various reference gases.

Then, for (CH ₄ -N ₂ ) gas, the output _XT.C of the thermal conductivity measuring means 13 is corrected using a correction formula based on the correlation between the output difference due to differences in applied voltage to the thermal conductivity measuring means 13 and the true calorific value. For example, the correction formula for finding the corrected output value (hereinafter referred to as "corrected output value (N ₂ )") when the second gas is nitrogen gas is shown in Equation 3 below.
is.

By plotting this corrected output value (N ₂ ) on the horizontal axis, the error when nitrogen gas is included is corrected, and the plot of the reference gas containing nitrogen gas ((CH ₄ -N ₂ ) gas) will be on the straight line of the calorific value calculation formula (Formula 1). In other words, in the case of an actual target gas containing nitrogen gas, the calorific value _QA of the target gas can be calculated by substituting the corrected output value (N ₂ ) for X _T.C. in the calorific value calculation formula.

Although not shown in the figure, the correction formula for calculating the corrected output value (hereinafter referred to as the "corrected output value ( _H2 )") when the second gas is carbon dioxide gas using a method similar to that used for hydrogen gas and nitrogen gas described above is shown in Equation 4 below.
is.

In other words, the calorimetry device 10 of this embodiment stores in its memory means at least one of the correction formulas shown in Equations 2 to 4 above.

As described above, the calorific value measuring device 10 of this embodiment enables highly accurate measurement of the calorific value of a target gas whose main component is paraffinic hydrocarbon gas and contains one of hydrogen gas, nitrogen gas, and carbon dioxide gas as an interference gas, using a simple configuration. For example, even if the target gas contains an interference gas (here, hydrogen gas) whose calorific value does not have a specific correspondence relationship with the thermal conductivity and refractive index, errors due to the presence of the interference gas can be eliminated and the calorific value can be measured with high accuracy.

In particular, when hydrogen gas is included as an interfering gas, calorimetry based on thermal conductivity was previously almost impossible, but this embodiment makes it possible to perform measurements based on thermal conductivity.

Furthermore, even when nitrogen or carbon dioxide is present, the calorific value can be calculated using the measurement results of a thermal conductivity meter alone, which allows for the device to be made smaller and its configuration simplified, resulting in lower prices.

Furthermore, by configuring the device to hold all of the above equations 2 to 4, it becomes possible to measure the calorific value of target gases that contain hydrogen gas, nitrogen gas, and carbon dioxide gas as interference gases.

In the above, this embodiment has been described as an example of measuring a target gas that contains a first gas as a main component and a second gas, but the calorific value measuring device 10 of this embodiment can also measure gases that contain only the first gas (paraffinic hydrocarbon gas). In addition to these, it can also measure target gases such as coke oven gas (COG), coal gasification, and naphtha gasification (all of which contain hydrogen gas and nitrogen gas as the second gas).

Second Embodiment
A second embodiment of the present invention will be described with reference to Figures 4 to 9. The target gas to be measured in the second embodiment is also natural gas, biogas, etc., but while the first embodiment measures a target gas containing one type of interference gas, the second embodiment is capable of measuring the calorific value of a target gas containing two types of interference gases (one of which is hydrogen gas) while reducing the influence (error) of these gases. In other words, the target gas is a gas that contains a first gas (paraffinic hydrocarbon gas) as the main component and also contains a third gas (hydrogen gas) and a fourth gas (at least one of nitrogen gas and carbon dioxide gas) that cause measurement error. Specifically, it is possible to measure the calorimetry of, for example, a mixed gas of methane gas, hydrogen gas, and nitrogen gas (CH _{4 —H 2} —N ₂ gas), or a mixed gas of methane gas, hydrogen gas, and carbon dioxide gas (CH ₄ —H 2 —CO ₂ gas), or a mixed gas of methane gas, hydrogen gas, nitrogen gas, and carbon dioxide gas (CH ₄ —H ₂ —N ₂ —CO ₂ gas).

Figure 4 shows an overview of the calorimetry device 30 of the second embodiment, where (A) is a block diagram showing an overview of the overall configuration, and (B) is a schematic diagram showing the refractive index converted calorimetry measurement means 32. In the following explanation, the same components as in the first embodiment are designated by the same reference numerals, and their explanation will be omitted.

As shown in Figure 1A, the calorific value measuring device 30 measures the calorific value of a target gas flowing, for example, through a gas pipeline 11 in the direction of the arrow in Figure 1A. It includes a thermal conductivity converted calorific value measuring means 31 capable of measuring a thermal conductivity converted calorific value obtained from the thermal conductivity of the target gas, a refractive index converted calorific value measuring means 32 capable of measuring a refractive index converted calorific value obtained from the refractive index of the target gas, a calorific value calculating means 33, and an output means 18. The gas pipeline 11, the thermal conductivity converted calorific value measuring means 31, and the refractive index converted calorific value measuring means 32 are each connected by a gas flow path 19, and the target gas in the gas pipeline 11 is supplied to the thermal conductivity converted calorific value measuring means 31 and the refractive index converted calorific value measuring means 32, respectively. The thermal conductivity converted calorific value measuring means 31, the refractive index converted calorific value measuring means 32, and the calorific value calculating means 33 are disposed, for example, within an explosion-proof container 50.

The thermal conductivity converted calorific value measurement means 31 includes, for example, a thermal conductivity measurement means 13, a correction means 14 for implementing the thermal conductivity converted calorific value measurement function, and a converted calorific value calculation means (thermal conductivity converted calorific value calculation means) 15. Based on a relational expression showing the correlation between the output _XT.C measured by the thermal conductivity measurement means 13 for a plurality of first gases and the actual calorific value, the thermal conductivity converted calorific value _QA can be calculated by correcting for errors due to the third gas and the fourth gas. In other words, the calorific value measurement device 30 (thermal conductivity converted calorific value measurement means 31) stores in its memory means at least correction equations capable of correcting errors for at least the third gas (hydrogen gas in this example) and the fourth gas (e.g., nitrogen gas). The rest of the configuration of the thermal conductivity converted calorific value measurement means 31 is similar to that of the thermal conductivity converted calorific value measurement means 12 of the first embodiment.

The correction means 14 has a difference calculation means 143 (141) and a correction output value calculation means 142, and has the function of correcting errors caused by the presence of interfering gases (third gas (hydrogen gas) and fourth gas) when calculating the thermal conductivity converted heat quantity of the target gas.

The thermal conductivity converted heat quantity calculation means 15 has a function of acquiring (calculating) the thermal conductivity converted heat quantity of the target gas based on a relational expression (heat quantity calculation formula shown in Equation 1 above) showing the correlation between the output _XT.C measured by the thermal conductivity measurement means 13 and the actual heat quantity. That is, the thermal conductivity converted heat quantity QA of the target gas is acquired (calculated) based on a value (corrected output value) corrected by the correction means 14 for errors due to the inclusion of interference gases in the target gas and the heat quantity calculation formula (Equation 1) obtained from the thermal _conductivity . Here, in the second embodiment, the heat quantity calculation formula obtained from the thermal conductivity (linear relational expression (Equation 1) shown by a straight line in FIG. 2(B)) is referred to as the first heat quantity calculation formula.

The refractive index converted calorific value measuring means 32 is a device (refractive index calorimeter) configured to detect the difference in the refractive index of light between, for example, a target gas and a standard gas such as air as a displacement of interference fringes using a signal (applied voltage) output from an external device (such as a power supply) 34, and to measure the refractive index converted calorific value _QB of the target gas based on the amount of displacement of the interference fringes.

Figure 1B shows a specific example of a device constituting the refractive index converted calorimetry means 32. The refractive index converted calorimetry means 32, for example, includes a chamber 321 divided into a target gas cell 322 for introducing a target gas and standard gas cells 323A and 323B for filling the chamber with a standard gas such as air; a plane-parallel mirror 325 for splitting light from a light source 324; a prism 328 positioned and adjusted so that the light split by the plane-parallel mirror 325, passing through the chamber 321, is reflected to change its direction, and the light passes through the chamber 321 again before being superimposed on the plane-parallel mirror 325 to produce interference fringes; and an interference fringe detection means 326 for receiving the combined light (interference light) superimposed on the plane-parallel mirror 325. The refractive index converted calorimetry means 322 further includes a plane mirror 327 for reflecting the combined light and a condenser lens 329 for focusing the combined light, with the interference fringe detection means 326 positioned at the focal point of the condenser lens 329. The dashed-dotted arrow indicates the path of light from the light source 324 until it is received by the interference fringe detection means 326 .

Referring to FIG. 10A, the heat quantity calculation means 33 calculates the heat quantity of the target gas using the thermal conductivity converted heat quantity _QA , the refractive index converted heat quantity _QB , a coefficient for correcting an error due to a fourth gas (at least one of nitrogen gas and carbon dioxide gas), and a formula for calculating the heat quantity (hereinafter referred to as the "second heat quantity calculation formula") described below.

In the second embodiment, although not shown, the calorific value measuring device 30 has a known configuration including a data transmission path, a calculation means, a control means, a memory means, etc., and these work together with the various means (functions) of the thermal conductivity conversion calorific value measuring means 12 to measure and calculate the target gas.

The calculated calorific value can be output to the outside via the output means 18. The output means 18 is, for example, a display means, a printing means, or a transmission means capable of outputting (transmitting) predetermined data via communication with the outside. The calorific value measuring device 30 may also be provided with a separate communication means capable of transmitting and receiving predetermined data to and from external devices.

Referring to Figure 5, correction of errors due to the inclusion of interference gases (third gas and fourth gas) will be described. This figure is a graph showing the relationship between the output _XT.C of the thermal conductivity measuring means 13 and the true calorific value for various reference gases. Figure 5(A) is the graph before correction of errors due to the inclusion of one interference gas in the various reference gases, and Figure 5(B) is the graph after correction of errors due to the inclusion of hydrogen gas when the only interference gas is hydrogen gas (correction by the correction means 14 having the difference calculation means 141 that corrects errors due to hydrogen gas in the first embodiment). The vertical axis represents the true calorific value [MJ/ ^Nm3 ] of the various reference gases obtained by analysis using, for example, a gas chromatograph, and the horizontal axis represents the output (normalized output) _XT.C measured by the thermal conductivity measuring means 13 for the various reference gases.

As previously mentioned, the various reference gases are all mixtures of methane gas with one other component added in different proportions, with known compositions (concentrations) and true calorific values. The other components added are paraffinic hydrocarbon gases (ethane, propane, and butane), as well as interference gases (hydrogen, nitrogen, and carbon dioxide). The methane gas concentration is between 100 vol% and 80 vol%, and the concentrations of the other components are between 0 vol% and 20 vol%.

Here, data for cases where the interfering gas is not carbon dioxide gas is reproduced from Figures 2 and 3 of the first embodiment. That is, Figure 2(A) shows the data for Figure 2(A) when the interfering gas is hydrogen gas only, and Figure 3(A) when the interfering gas is nitrogen gas only, with additional data for when the interfering gas is carbon dioxide gas only. Furthermore, the data for hydrogen gas in Figure 2(B) is the same as Figure 2(B). The rest of the data is the same as in the first embodiment, except for the data for when the interfering gas is carbon dioxide gas only, and redundant explanations will be omitted.

A specific example of a reference gas containing carbon dioxide will be described below. The plot marked with a star represents the results for a mixed gas of methane and carbon dioxide ( _CH4 - _CO2 ) when an applied voltage of 1.0 V is used. In this case, mixed _gases in which the methane concentration decreases in 2.5 vol% increments (97.5 vol% methane - 2.5 vol% carbon dioxide, 95 vol% methane - 5 vol% carbon dioxide, 92.5 vol% methane - 7.5 vol% carbon dioxide, etc.) are shown as the output XT.C on the horizontal axis increases from "0" (pure methane gas).

The plots marked with * represent the results for a mixed gas of methane gas and carbon dioxide ( _CH4 - _CO2 ) when the applied voltage is 0.5V, and show mixed _gases in which the methane gas concentration decreases in 2.5 vol% increments (methane gas 97.5 vol% - carbon dioxide gas 2.5 vol%, methane gas 95 vol% - carbon dioxide gas 5 vol%, methane gas 92.5 vol% - carbon dioxide gas 7.5 vol%, etc.) as the output XT.C on the horizontal axis increases from "0" (pure methane gas).

The calorific value measuring device 10 of the first embodiment is configured to be able to measure the calorific value after correcting for errors due to interference gases when the target gas is paraffinic hydrocarbon gas and contains one type of interference gas selected from hydrogen gas, nitrogen gas, and carbon dioxide gas. In contrast, the calorific value measuring device 30 of the present embodiment is equipped with a refractive index converted calorific value measuring means 32 in addition to a thermal conductivity converted calorific value measuring means 31, thereby making it possible to measure the calorific value of target gases containing hydrogen gas and other types of interference gases after correcting for errors due to interference gases.

Specifically, in order to eliminate errors due to hydrogen gas (to correct the normalized output _XT.C in the case of hydrogen gas only), if the output difference of the normalized output _XT.C is less than 0, the normalized output _XT.C is corrected using the above-mentioned formula 2. On the other hand, if the output difference of the normalized output _XT.C is greater than 0, the normalized output _XT.C is not corrected (the following formula 5 is used as the corrected output value).
The above formulas 2 and 5 are stored in a storage means of the calorimetry device 30 (for example, the thermal conductivity conversion calorimetry means 31).

The results of plotting the corrected output values for these various reference gases on the horizontal axis are shown in Figure 1(B). The linear relationship shown by the straight line in Figure 1(B) is the calorific value calculation formula (the first calorific value calculation formula shown in Equation 1) obtained from thermal conductivity, which eliminates the error caused by the inclusion of only hydrogen gas as an interfering gas.

6A shows the results of measurements of the various reference gases described above using the refractive index converted calorific value measuring means 32, with the vertical axis representing the refractive index converted calorific value _QB and the horizontal axis representing the refractive index. As shown in the figure, for mixed gases consisting only of paraffinic hydrocarbon gases and mixed gases containing only hydrogen gas as an interference gas, the refractive index converted calorific value and the refractive index have a linear relationship (proportional relationship) as shown by the straight line in the figure, regardless of the composition (concentration). On the other hand, for mixed gases containing only nitrogen gas and only carbon dioxide gas, the relationship deviates from the linear relationship.

5B shows the results of measuring the various reference gases described above using the thermal conductivity converted calorific value measuring means 31 that holds the first calorific value calculation formula (and has the difference calculation means 141 that corrects the error for hydrogen gas in the first embodiment), and the horizontal axis (normalized output X T.C ) has been adjusted so that the linear relationship (slope of the line) shown in the graph of _FIG . 5B is aligned with the linear relationship (slope of the line) in FIG. 6A.

From Figures 1A and 1B, it is possible to determine the ratio of the error when measuring a gas containing nitrogen gas using the thermal conductivity converted calorimetry means 31 to the error when measuring it using the refractive index converted calorimetry means 32. It is also possible to determine the ratio of the error when measuring a gas containing carbon dioxide gas using the thermal conductivity converted calorimetry means 31 to the error when measuring it using the refractive index converted calorimetry means 32. Because these measurement error ratios have a predetermined relationship, this relationship can be used to correct errors when only nitrogen gas is included as an interference gas (when hydrogen gas is not included, or when hydrogen gas is included but the error is corrected) and when only carbon dioxide gas is included (when hydrogen gas is not included, or when hydrogen gas is included but the error is corrected).

More specifically, by using an appropriate correction coefficient CF corresponding to the composition of the target gas in the second calorific value calculation formula shown in the following formula 6, which is stored in the storage means of the calorific value measuring device 10, the calorific value calculation means 33 corrects errors due to the presence of interference gases other than hydrogen gas (nitrogen gas and/or carbon dioxide gas) to calculate the calorific value Q of the target gas. This correction of errors due to the presence of nitrogen gas and/or carbon dioxide gas is described in detail in a patent (Japanese Patent No. 5308842) by the applicant of the present application.
is.

The value of the correction coefficient CF is 2.91≦correction coefficient CF≦3.75, and more preferably 2.96≦correction coefficient CF≦3.15.

By applying the correction coefficient CF in the above-mentioned range to this second calorific value calculation formula (Equation 6), even when hydrogen gas is included as an interfering gas, for which error correction was previously not possible (or difficult), the influence of that error can be reduced and the calorific value Q of the target gas can be measured (calculated).

7 is a graph verifying the measurement results obtained by the calorific value measuring device 30 of this embodiment (having the difference calculation means 141 of the first embodiment) for a plurality of reference gases with known compositions. The vertical axis of the graph represents the true calorific value [MJ/ ^Nm3 ] obtained by analysis using, for example, a gas chromatograph, and the horizontal axis represents the measured value (measured calorific value) by the calorific value measuring device 30. The solid line in the graph represents the second calorific value calculation formula shown in Equation 6.

In the figure, _{( CH4} - _C2H6 ) gas is _represented by a △ mark, ( _CH4 - _C3H8 ) gas by a square mark, ( _CH4 - _C4H10 ) gas by a ◇ mark, _{( CH4} - _H2 ) gas by a circle mark, ( _CH4 - _N2 ) gas by a ▽ mark, ( _CH4 - _CO2 ) gas by a star mark, ( _CH4 - _H2 - _N2 ) gas by a ▼ mark, ( _CH4 - _H2 - _CO2 ) gas by a ★ mark, _and ( _CH4 - _H2 - _C2H6 ) gas by a ▲ mark.

As is clear from these results, the calorific value measuring device 30 of this embodiment can reduce the influence of errors due to interference gases and measure the calorific value Q for a mixed gas that contains paraffinic hydrocarbon gas as the main component, hydrogen gas as an interference gas, and either nitrogen gas or carbon dioxide gas (e.g., ( _CH4 - _H2 - _N2 gas)), or a gas in which paraffinic hydrocarbon gas is mixed with hydrogen gas and carbon dioxide gas as interference gases (e.g., ( _CH4 - _H2 - _N2 ) gas), even if the composition of each gas is unknown.

In this embodiment, since calorific value measurement can be performed while excluding error components due to hydrogen gas (assuming no hydrogen gas is included), it is naturally possible to measure target gases that do not contain hydrogen gas. For example, as shown in Figure 7, calorific value measurement is possible for target gases that contain at least one of nitrogen gas and carbon dioxide gas as an interference gas (specifically, for example, a mixed gas of methane gas and nitrogen gas (( _CH4 - _N2 gas)), a mixed gas of methane gas and carbon dioxide gas ( _CH4 - _CO2 ), or a mixed gas of methane gas, nitrogen gas, and carbon dioxide gas ( _CH4 - _N2 - _CO2 ) gas, although not shown).

As shown in the figure, in the case of a target gas containing two types of paraffinic hydrocarbon gases and hydrogen gas as an interference gas (specifically, for example, a mixed gas of methane gas, ethane, and hydrogen gas (CH ₄ —H ₂ —C ₂ H ₆ gas)), it is possible to correct the error due to the hydrogen gas and perform accurate calorimetry.

Next, a calorific value calculation method according to the second embodiment will be described. For example, a target gas (e.g., methane gas containing hydrogen gas and nitrogen gas) flowing through the gas pipeline 11 is supplied to the thermal conductivity converted calorific value measuring means 31 via the gas flow path 19. The thermal conductivity converted calorific value measuring means 31 then calculates the thermal conductivity converted calorific value _QA of the target gas based on the first calorific value calculation formula, correcting for errors due to the third gas (hydrogen gas).

Specifically, a first voltage (e.g., 1.0 V) is applied to the thermal conductivity measuring means 13 to measure the target gas and obtain a first output. Next, a second voltage (e.g., 0.5 V) is applied to the thermal conductivity measuring means 13 to measure the same target gas and obtain a second output.

Next, the difference (output difference) between the first output and the second output is calculated. Then, the corrected output value of the target gas (normalized output of the thermal conductivity measuring means 13 after correcting for errors due to hydrogen gas) is calculated using the correction formula shown in Equation 2 above. Then, the corrected output value is substituted as the normalized output value for the output _XT.C in the first heat quantity calculation formula (Equation 1) to calculate the thermal conductivity converted heat quantity _QA of the target gas.

The target gas is supplied to the refractive index converted calorific value measuring means 32 via the gas flow path 19, and the refractive index converted calorific value _QB of the target gas is obtained. Then, the calorific value _Q of the target gas is calculated using the obtained refractive index converted calorific value _QB , the thermal conductivity converted calorific value QA, and the second calorific value calculation formula shown in Equation 6 above.

Third Embodiment
A third embodiment of the present invention will be described with reference to Figures 8 to 18. The third embodiment is an application of the first and second embodiments, and therefore, detailed descriptions of parts that overlap with the first and second embodiments will be omitted.

As shown in Figure 7, when hydrogen gas and one other gas are included as interference gases, the effect of the error can be reduced, but there is still a deviation from the linear line representing the second calorific value calculation formula. This is thought to be because, as shown in Figure 5(A), when various reference gases include hydrogen gas and when they are other than hydrogen gas (nitrogen gas and carbon dioxide gas), the output difference in normalized output _XT.C is in a negative and positive relationship, and the differences cancel each other out.

8 is a graph showing the effect of nitrogen gas on the difference in normalized output _XT.C for a reference gas containing hydrogen gas and nitrogen gas as interference gases. The reference gas is methane gas (( _CH4 - _H2 - _N2 ) gas (methane gas concentration: 80 vol%)) mixed with hydrogen gas and nitrogen gas as interference gases. The concentrations of hydrogen gas and nitrogen gas were varied for the reference gas, and the difference in normalized output _XT.C (output difference) was obtained when voltages of 1.0 V and 0.5 V were applied. The colored circles represent the normalized output _XT.C for ( _CH4 - _H2 - _N2 ) gases with different concentrations of hydrogen gas and nitrogen gas. The _graph shows the difference in normalized output XT.C for hydrogen gas to nitrogen gas ratios ( _H2 : _N2 ) of 3:1, _H2 : _N2 = 1:1, _H2 : _N2 = 1:3, and _H2 : _N2 = 1:9, with the results plotted in increasing color as the nitrogen gas content increases, from lowest to highest. The black circles represent the difference in normalized output XT.C for methane gas (( _CH4 - _N2 ) gas, nitrogen gas concentration: 20 vol%, methane gas concentration: 80 vol%, i.e., _H2 : _N2 = 0:10) mixed with only nitrogen gas as an interference _gas . The open circles represent the difference in normalized output XT.C for methane gas (( _CH4 - _H2 ) gas, hydrogen gas concentration: 20 vol%, methane gas concentration: 80 vol%, i.e., _H2 : _N2 = 10:0) mixed with only hydrogen gas as an interference _gas . The vertical axis represents the output difference [mA], and the horizontal axis represents the hydrogen gas concentration [vol%].

When the interfering gas is hydrogen gas only, that is, when the solid line connecting the white circles (hereinafter referred to as the "hydrogen gas concentration-output difference relationship") is used as the reference, the difference in normalized output XT.C deviates from the solid line when nitrogen gas is included, as indicated by the colored circles. This deviation from the solid line is an error component caused by the presence of nitrogen gas. In other words, when hydrogen gas and nitrogen gas are included as interfering gases, differences occur in the normalized output _XT.C of the reference gas depending on their concentrations, and it has become clear that differences occur in the error component depending on the concentration of nitrogen gas.

FIG. 9 is a diagram showing the relationship between the voltage applied to the thermal conductivity measuring means 13 and the normalized output _XT.C. for a reference gas (( _CH4 - _H2 - _N2 ) gas). The normalized output _XT.C. was measured by changing the applied voltage for multiple reference gases (six in this case) with different ratios of hydrogen gas and nitrogen gas as interference gases. The vertical axis represents normalized output _XT.C. , and the horizontal axis represents applied voltage. The concentration of the mixed gas of hydrogen gas and nitrogen gas (the total concentration of _H2 gas and _N2 gas) is 10 vol% for all reference gases. 10A shows the results for a hydrogen gas to nitrogen gas ratio (H ₂ :N ₂ ) of 1:9, 10B for a H ₂ :N ₂ ratio of 1:3, 10C for a H ₂ :N ₂ ratio of 1:1, 10D for a H ₂ :N ₂ ratio of 3:2, and 10E for a H 2 :N ₂ ratio of 9:1. 10F for a H ₂ :N ₂ ratio of 10:0, i.e., the results for (CH _{4 -H 2} ) gas (hydrogen gas concentration: 10 vol %, methane gas concentration: 90 vol %).

From these, it was found that the relationship between the applied voltage to the thermal conductivity measuring means 13 and the normalized output _XT.C. of (CH ₄ -H ₂ -N ₂ ) gas changes depending on the ratio of hydrogen gas to nitrogen gas, and that there is a correlation between the relationship between the applied voltage and the normalized output _XT.C. of (CH ₄ -H ₂ -N ₂ ) gas and the ratio of hydrogen gas and nitrogen gas. Specifically, the normalized output _XT.C. of (CH ₄ -H ₂ -N ₂ ) gas can be expressed as the following equation 7, which is a relational expression for the concentrations of hydrogen gas and nitrogen gas.
is.

Therefore, if the concentrations of hydrogen gas and nitrogen gas in the interference gas are known, it is possible to eliminate the influence of nitrogen gas for each of the (CH ₄ -H ₂ -N ₂ ) gases indicated by the colored circles in Figure 8, and perform corrections to match or approximate the hydrogen gas concentration-output difference relationship equation. Furthermore, with this correction, the thermal conductivity converted calorific value measuring means 12 can calculate the calorific value using the correction equation shown in Equation 2 (the correction equation when only hydrogen gas is included as an interference gas).

8 and 9 show the relationship for a target gas ((CH ₄ -H ₂ -N ₂ ) gas) containing a mixture of hydrogen gas and nitrogen gas as interference gases, but it has been found that the same applies to a target gas ((CH ₄ -H ₂ -CO ₂ ) gas) containing a mixture of hydrogen gas and carbon dioxide gas as interference gases, and to a target gas ((CH ₄ -H ₂ -N ₂ -CO ₂ ) gas) containing a mixture of hydrogen gas, nitrogen gas, and carbon dioxide gas as interference gases. In other words, if the concentrations of hydrogen gas, nitrogen gas, and/or carbon dioxide gas in the interference gases are known, correction can be made to eliminate the influence of nitrogen gas and/or carbon dioxide gas and to match or approximate the hydrogen gas concentration-output difference relationship equation. Furthermore, with this correction, the thermal conductivity converted calorific value measurement means 12 can calculate the calorific value using the correction equation shown in Equation 2 (the correction equation when only hydrogen gas is included as an interference gas).

Based on these findings, the applicant of the present application has investigated a method for calculating the concentration of an interference gas for a target gas containing hydrogen gas, nitrogen gas, and carbon dioxide gas as interference gases, where the composition and content of the interference gas are unknown, and has discovered the following method. This method first calculates the hydrogen gas concentration based on a certain relationship, and then calculates the nitrogen gas concentration and carbon dioxide gas concentration (their total value) based on the calculated hydrogen gas concentration. The hydrogen gas concentration can be calculated, for example, by the following first and second methods. In the calculation of each gas concentration described below, if either nitrogen gas or carbon dioxide gas is not included, the calculation can be performed by setting the corresponding concentration item (nitrogen gas concentration X _N2 and/or carbon dioxide gas concentration X _CO2 ) to "0."

<First method for calculating hydrogen gas concentration>
The first method for calculating hydrogen gas concentration is a technique in which the hydrogen gas concentration is calculated from the probability that hydrogen gas is at a certain concentration. First, for a mixed gas containing at least hydrogen gas (specifically, (CH ₄ -H ₂ -N ₂ ) gas, (CH ₄ -H ₂ -CO ₂ ) gas, and (CH ₄ -H ₂ -N ₂ -CO ₂ ) gas) with methane gas as the reference gas, multiple gases are prepared in which the hydrogen gas concentration (index concentration) ai is varied from 0 to 20 vol% (41 values in 0.5 vol% increments), and the thermal conductivity and refractive index of each gas are measured. Then, the calculation parameters w and b for calculating the probability that hydrogen gas is at each concentration ai are obtained using the following equation 8. This results in an equation (the following equation 9) for calculating the probability that the hydrogen gas concentration is at each concentration ai. Here, equations 8 and 9 can be obtained, for example, by machine learning, but the method for deriving equations 8 and 9 is not limited to machine learning.
is.

When calculating the concentration of a certain hydrogen gas, the thermal conductivity and refractive index (input signal x) of the hydrogen gas are measured using, for example, the thermal conductivity measuring means 13 and the refractive index converted calorimetry measuring means 32, and the probability that the hydrogen gas concentration is each of the 41 concentrations (concentrations that serve as indexes) ai is calculated using Equations 8 and 9. Then, the target hydrogen gas concentration _XH2 can be calculated by multiplying each concentration ai by its probability f(ai) and adding them up.

<<Second method of calculating hydrogen gas concentration/First hydrogen concentration calculation formula>>
The second method for calculating the hydrogen gas concentration is to obtain it from a hydrogen concentration calculation formula based on the relationship between the voltage applied to a thermal conductivity meter (for example, the thermal conductivity measuring means 13) and the normalized output X _T.C.

FIG. 10 is a graph showing the relationship between the proportion of hydrogen gas in (CH ₄ -H ₂ -N ₂ ) gas, the applied voltage to the thermal conductivity measuring means 13, and the normalized output _XT.C. of (CH ₄ -H ₂ -N ₂ ) gas. FIG. 10 (A) is a graph obtained by re-plotting FIGS. 9 (A) to 9 (F) into one diagram and fitting to a quadratic curve, with the vertical axis representing normalized output _XT.C. and the horizontal axis representing applied voltage [V]. Hereinafter, the curves (or straight lines) for the six types of (CH ₄ -H ₂ -N ₂ ) gas shown in FIG. 10 (A) are referred to as "output-voltage functions." FIG. 10 (B) is a graph plotting the slope of the output-voltage function shown in FIG. 10 (A) (the slope of the tangent in the case of a curve; hereinafter, simply referred to as "slope _dXT /dV") on the vertical axis and the applied voltage [V] on the horizontal axis. As shown in Figure 10(B), the slope dX _T.C./dV and the applied voltage have a proportional relationship depending on the proportion of hydrogen gas. The relational expression shown by the solid line in Figure 10(B) is hereinafter referred to as the "slope-voltage function."

As is clear from the figure, the extreme points (peaks, points where the slope dX _T.C. /dV is 0) of the output-voltage functions for each of the six (CH ₄ -H ₂ -N ₂ ) gases shift toward higher applied voltages as the proportion of hydrogen gas increases.

11A is a graph plotting the hydrogen gas ratio (H2 ratio) at the extreme points (points where the slope dX _T.C./dV is 0) of each of six types of ( _CH4 - _H2 - _N2 ) gases on the vertical axis and the applied voltage [V] at the extreme points on the horizontal axis for the output _- voltage function shown in FIG. 10A. This curve will be referred to as the " _H2 ratio-voltage curve" hereinafter.

11B shows an approximated line (hereinafter referred to as "output-H2 proportion function") obtained by plotting the slope of each line of the slope-voltage function for the six types of ( _CH4 - _H2 - _N2 ) gases shown in FIG. 10B on the vertical axis and the hydrogen gas proportion (when the concentration of the total of hydrogen gas and nitrogen gas ( _H2 + _{N2 )} gas) is 10 vol%) on the horizontal axis. The "slope of the 'slope-voltage function line'" shown in FIG. 10B is the differential value of the slope dX _T.C./dV ( ^d2X _T.C./dV2 ), i.e., the second-order differential value of the normalized output X _T.C. with respect to the applied voltage V, and may hereinafter be simply referred to as ^the "second-order differential value of the normalized output X _T.C. " In Figure 11, the results for ( _CH4 - _H2 - _N2 ) gas are plotted with circles. Furthermore, for a mixed gas ( _CH4 - _H2 - _CO2 ) containing methane gas, hydrogen gas, and carbon dioxide gas, and a mixed gas ( _CH4 - _H2 - _N2 - _CO2 ) containing methane gas, hydrogen gas, nitrogen gas, and carbon dioxide gas, a reference gas was prepared and the relationship with the proportion of hydrogen gas was determined in the same manner as for the six types of ( _CH4 - _H2 - _N2 ) gas described using Figures 9 and 10, and the former are plotted with triangles and the latter are plotted with squares.

As shown in Figure 11 (B), for all of the reference gases (( _CH4 - _H2 - _N2 ) gas, ( _CH4 - _H2 - _CO2 ) gas, ( _CH4 - _H2 - _N2 - _CO2 ) gas), there is a correlation as shown by the approximate curve in the second-order derivative of the normalized output X _T.C. and the proportion of hydrogen gas. In other words, based on these relationships for the reference gases, it was found that the hydrogen gas concentration can be calculated for a target gas (methane gas) that contains at least hydrogen gas as an interference gas and whose interference gas concentration is unknown (specifically, ( _CH4 - _H2 ) gas, ( _{CH4 - H2} - _N2 ) gas, (CH4- _H2 - _CO2 ) gas, ( _CH4 - _H2 - _N2 - _CO2 ) gas) whose interference gas concentration is unknown. For (CH ₄ -H ₂ ) gas, the hydrogen gas concentration of the target gas can be calculated based on the data for the reference gas with an H ₂ ratio of "1" from the data for (CH ₄ -H ₂ -N ₂ ) gas shown in Figures 9 to 11 (data indicated by circles in Figure 11).

Below, an example will be described for an arbitrary target gas ((CH ₄ -H ₂ -N ₂ ) gas) for which the hydrogen gas concentration and the total concentration of hydrogen gas and nitrogen gas are unknown. According to the H ₂ proportion-voltage curve shown in Figure 11 (A), if the normalized output X _T.C. is obtained for an arbitrary (CH ₄ -H _{2 -N 2} ) gas, the hydrogen gas proportion when the concentration of the total of hydrogen gas and nitrogen gas ((H ₂ +N ₂ ) gas) is 10 vol% can be calculated based on the extreme point of the output-voltage function (the point where the slope dX T.C. /dV is 0).

Then, based on the output- _H2 proportion function in Figure 11 (B), the second derivative value of the normalized output X _T.C. (when the concentration of ( _H2 + _N2 ) gas) is 10 vol%) corresponding to the calculated hydrogen gas proportion (horizontal axis) can be calculated.

Therefore, the hydrogen gas concentration X _H2 in any (CH ₄ —H ₂ —N ₂ ) gas can be calculated by the first hydrogen concentration calculation formula shown in the following formula 10A.
is.

The hydrogen gas concentration obtained as a result is proportional to the concentration of (H ₂ + N ₂ ) gas in the reference gas ((CH ₄ -H ₂ -N ₂ ) gas), so if the (H ₂ + N ₂ ) gas concentration in the reference gas increases by N times, the calculation result of equation 10 (hydrogen gas concentration) is multiplied by N.

<<Second method of calculating hydrogen gas concentration/Second hydrogen concentration calculation formula>>
Next, another example of the second method will be described. A second hydrogen concentration calculation formula shown in the following formula 10B may be used as a hydrogen concentration calculation formula using the second derivative of the normalized output X _T.C.
is.

Equation 10B is derived from the relationship between the second derivative of the normalized output X _T.C. and the H2 concentration, as shown in Figure 12. Figure 12(A) plots the relationship between the second derivative of the normalized output and the hydrogen gas concentration contained in multiple (eight types in this case) reference gases (( _CH4 - _H2 - _N2 ) gases) containing methane gas and hydrogen gas and nitrogen gas as interference gases, with the ratios (known values) of these gases varied. The vertical axis represents the hydrogen gas concentration [vol%], and the horizontal axis represents the second derivative of the normalized output.

The concentration of the mixed gas of hydrogen gas and nitrogen gas (total concentration of _H2 gas and _N2 gas) varies depending on the ratio of eight species, and details are shown in Figure 13. Figure 13 shows a list of _H2 gas concentrations and total concentrations (measured values) of _H2 gas and _N2 gas adjusted for each ratio (composition) of multiple species (e.g., eight species). The second-order differential value of the normalized output was calculated using these reference gases, and the relationship with the hydrogen gas concentration was plotted as shown in Figure 13 (A). The ratios ( _H2 : _N2 ) of the eight types of hydrogen gas and nitrogen gas are _H2 : _N2 = 1:0, _H2 : _N2 = 9:1, _H2 : _N2 = ₃ :1, H2: _N2 = 3:2, _H2 : _{N2 = 1:1, H2:N2 = 2} :3, _H2 : _N2 = 1:3, _H2 : _N2 = 1:9, and these results are plotted from the lowest nitrogen gas content ratio to the lighter color as the content ratio increases.

The results in Figure 12(A) show that for ( _CH4 - _H2 - _N2 ) gas, there is a correlation between the second derivative of the normalized output and the hydrogen gas concentration, regardless of the ratio (composition) of the interfering gases, hydrogen gas and nitrogen gas.

Figure 12(B) shows the results of measurements performed in the same manner as in Figure 12(A) for standard gases containing methane gas, hydrogen gas, and carbon dioxide gas (( _CH4 - _H2 - _CO2 ) gas: plotted with square marks), hydrogen gas, and ethane gas (( _CH4 - _H2 - _C2H6 ) gas: plotted with triangle marks), and hydrogen gas, nitrogen gas, and carbon dioxide gas (( _CH4 - _H2 - _{N2 - CO2} ) gas: plotted with cross marks). That is, the proportion (composition: known value) of interference gases for each reference gas was varied to multiple types (eight types of (CH ₄ -H ₂ -N ₂ ) gas, five types of (CH ₄ -H ₂ -CO ₂ ) gas, four types of (CH ₄ -H ₂ -C ₂ H ₆ ) gas, and two types of (CH ₄ -H ₂ -N ₂ -CO ₂ ) gas), and the second-order differential value of the normalized output was plotted on the horizontal axis and the contained hydrogen gas concentration [vol %] on the vertical axis. The concentration of interference gases (mixed gases) in each reference gas differed depending on the proportion (composition) of the eight types of interference gases, and details are shown in Figure 13. The results of Figure 12(A) are also shown in Figure 12(B). That is, the result for the reference gas ((CH ₄ -H ₂ ) gas) containing only hydrogen gas as an interference gas in methane gas is H2:N2 = 1:0 in Figure 1(A), and is plotted with a ● mark in Figure 1(B), while the result for the reference gas ((CH ₄ -H ₂ -N ₂ ) gas) containing hydrogen gas and nitrogen gas as interference gases is plotted with a ○ mark in Figure 1(B).

The results in Figure 12 (B) show that there is a correlation between the second derivative of the normalized output and the hydrogen gas concentration, regardless of the type and proportion (composition) of the interference gas.

Here, specific examples of the coefficients (α, β, γ) in equation 10B are α = -6.3284, β = 16.903, and γ = 0. In other words, an example of equation 10B is as follows.

X _H2 = -6.3284×f"(V) ² +16.903×f"(V) (Formula 10B)

As such, the second method calculates the hydrogen gas concentration using the hydrogen concentration calculation formula shown in Equation 10A (first hydrogen concentration calculation formula) or the hydrogen concentration calculation formula shown in Equation 10B (second hydrogen concentration calculation formula), and hereinafter, Equation 10A and Equation 10B may be collectively referred to as the hydrogen gas concentration calculation formulas.

Based on the hydrogen gas concentration _XH2 calculated by the first or second method, the corrected output value ( _H2 ) shown in the above formula 2 is further (additionally) corrected. Specifically, the "output difference ( _H2 )" in the calculation formula for the corrected output value (H2) shown in the above formula ₂ is corrected by the following formula 11.
is.

This correction is performed only when the post-correction output difference y is smaller than the pre-correction output difference (the original "output difference (H ₂ )" in Equation 2). In other words, the post-correction output difference y in Equation 11 is used as the "output difference (H ₂ )" in Equation 2 only when the post-correction output difference y in Equation 11 is smaller than the "output difference (H ₂ )" in Equation 2.

As already mentioned, the hydrogen gas concentration calculation formulas (Equation 10A and Equation 10B) allow for the calculation of the hydrogen gas concentration of a target gas that contains at least hydrogen gas as an interference gas and also contains nitrogen gas and/or carbon dioxide gas. The concentrations of nitrogen gas and/or carbon dioxide gas in the target gas can be calculated as follows:

The total concentration of nitrogen gas and carbon dioxide gas (X _N2 +X CO2 ) is calculated using the “output difference (H ₂ )” in Equation 2 (hereinafter referred to as “uncorrected output difference (H ₂ )”) and the corrected output difference y in Equation 11 (hereinafter referred to as “corrected output difference (H _{2 )} ”) using the following Equation 12.

When nitrogen gas and/or carbon dioxide gas is not contained, X _N2 concentration and/or X _CO2 concentration is set to "0".
is.

Furthermore, an additional correction amount determined by the following equation 13 based on the total concentration of nitrogen gas and carbon dioxide gas (X _N2 +X _CO2 ) is added to the output value (H ₂ ) of equation 2.
is.

In this way, by correcting Equation 2 based on the calculated concentrations of hydrogen gas, nitrogen gas, and/or carbon dioxide gas in the interference gas, the influence of nitrogen gas and/or carbon dioxide gas can be eliminated and the hydrogen gas concentration-output difference relationship equation can be matched or approximated. The corrected output value (H ₂ ) of Equation 2, which reflects the corrections of Equations 11 to 13, is hereinafter referred to as the "additional corrected output value (H ₂ )." Then, by substituting the additional corrected output value (H ₂ ) as the standardized output value for X _T.C. in the first heat quantity calculation equation, the thermal conductivity converted heat quantity _QA can be calculated.

Figures 14 and 15 are block diagrams showing an overview of the calorie measuring device 35 as a specific example of the third embodiment. Figure 14 is a schematic diagram showing the overall configuration of the calorie measuring device 35, and Figure 15 is a schematic diagram mainly for explaining the correction processing by the correction means 14. Note that components that are the same as those in the second embodiment are designated by the same reference numerals and their description will be omitted.

The calorific value measuring device 35 includes a thermal conductivity converted calorific value measuring means 31, a refractive index converted calorific value measuring means 32, a calorific value calculation means 33, and an output means 18. The correction means 14 in the third embodiment further includes a third gas concentration calculation means 146 and an additional correction output value calculation means 147.

15, the third gas concentration calculation means 146 acquires the concentration of a third gas in the target gas (hereinafter referred to as the "third gas concentration"). Specifically, Equation 8 and Equation 9 are stored, and the third gas concentration (here, hydrogen gas concentration X _H2 ) is calculated based on a first method using these. Alternatively, Equation 10, the slope-voltage function shown in FIG. 10(B), the _H2 proportion-voltage curve shown in FIG. 11(A), and the output- _H2 proportion function shown in FIG. 11(B) are stored, and the third gas concentration (here, hydrogen gas concentration X _H2 ) is calculated based on a second method using these.

The additional corrected output value calculation means 147 additionally corrects the output value (H _{2 )} and the output difference (H ₂ ) of the correction equation (Equation 2) for calculating the corrected output value (H ₂ ) of the corrected output value calculation means 142. More specifically, the additional corrected output value calculation means 147 determines y (the corrected output difference (H ₂ )) for correcting the output difference (H ₂ ) of Equation 2 using Equation 11, based on the third gas concentration (calculated hydrogen gas concentration X _H2 ) calculated by the first method or the second method. Furthermore, the additional corrected output value calculation means 147 calculates the concentration (hereinafter referred to as the "fourth gas concentration") of a fourth gas (here, nitrogen gas and/or carbon dioxide gas) in the target gas using Equation 12. Then, the additional correction amount is calculated using Equation 13, based on the third gas concentration and the fourth gas concentration.

Then, the additional correction output value calculation means 147 substitutes y (the output difference (H ₂ ) after correction) into the output difference (H ₂ ) in equation 2, and substitutes the additional correction amount into the output value (H ₂ ) in equation 2, to obtain the additional correction output value (H ₂ ) that is further corrected from the (initial) correction output value (H ₂ ) in equation 2.

The correcting means 14 corrects the measurement result (normalized output X _T.C. actual measurement value) of the thermal conduction measuring means 13 using this additional corrected output value (H ₂ ).

The thermal conductivity converted heat quantity calculation means 15 uses the corrected normalized output _XT.C. (substituting the additional corrected output value ( _H2 ) as the normalized output value for _XT.C. in the first heat quantity calculation formula) to calculate the thermal conductivity converted heat quantity _QA according to Formula 1. In addition, as in the second embodiment, the refractive index converted heat quantity _QB is calculated, and the heat quantity calculation means 33 calculates the heat quantity Q of the target gas using the thermal conductivity converted heat quantity _QA , the refractive index converted heat quantity _QB , a coefficient CF for correcting errors due to the fourth gas (at least one of nitrogen gas and carbon dioxide gas), and the second heat quantity calculation formula (Formula 6).

Specifically, the heat quantity calculation method according to the third embodiment is as follows: First, as in the second embodiment, the heat quantity calculation formula (first heat quantity calculation formula) shown in Equation 1 is obtained.

Next, during the measurement operation, for example, the target gas (e.g., methane gas containing hydrogen gas and nitrogen gas) flowing through the gas pipeline 11 is supplied to the thermal conductivity converted calorific value measuring means 31 via the gas flow path 19. As a result, the thermal conductivity converted calorific value measuring means 31 calculates the thermal conductivity converted calorific value _QA of the target gas based on the first calorific value calculation formula, correcting for errors due to the third gas (hydrogen gas).

Specifically, a first voltage (e.g., 1.0 V) is applied to the thermal conductivity measuring means 13 to measure the target gas and obtain a first output (actual measured value). Next, a second voltage (e.g., 0.5 V) is applied to the thermal conductivity measuring means 13 to measure the same target gas and obtain a second output (actual measured value).

Next, the correction means 14 calculates the difference (output difference) between the first output and the second output, and then calculates the corrected output value (H ₂ ) of the target gas (the normalized output X _T.C. of the thermal conductivity measuring means 13 after correcting for errors due to hydrogen gas) using the correction formula shown in Equation 2 above.

Thereafter, the third gas concentration calculation means 146 calculates a third gas concentration (e.g., hydrogen gas concentration _XH2 ) in the target gas. Based on the calculated hydrogen gas concentration _XH2 , a correction value y for correcting the output difference ( _H2 ) in Equation 2 is obtained (Equation 11). Furthermore, a fourth gas concentration (e.g., nitrogen gas concentration and carbon dioxide gas concentration) in the target gas is calculated according to the hydrogen gas concentration _XH2 (Equation 12), and an additional correction amount (Equation 13) is obtained based on the various concentrations. If necessary (only when y<the original output difference ( _H2 ) in Equation 2), the correction value y in Equation 11 is substituted for the output difference ( _H2 ) in Equation 2. Furthermore, the additional correction amount in Equation 13 is substituted for the output value ( _H2 ) in Equation 2, and the obtained additional corrected output value ( _H2 ) is used as _XT.C. in the first heat quantity calculation formula (Equation 1), to calculate the thermal conductivity converted heat quantity _QA of the target gas.

The target gas is supplied to the refractive index converted calorific value measuring means 32 via the gas flow path 19, and the refractive index converted calorific value _QB of the target gas is obtained.

Then, the calorific value Q of the target gas is calculated using the obtained refractive index converted calorific value _QB and thermal conductivity converted calorific value _QA and the second calorific value calculation formula shown in Equation 6 above.

Figures 16 to 18 are graphs showing the results of calculating the hydrogen gas concentration H2 and the heat quantity Q using a first method (e.g., a method using machine learning) in the third embodiment.

FIG. 16 is a graph comparing the results of calculating the hydrogen gas concentration _XH2 using the first method of the third embodiment (e.g., a method using machine learning) to determine the calorific value Q for a reference gas containing an interference gas (( _H2 + _N2) gas) with a known component concentration (calculated calorific value) with the measured calorific value (actual calorific value). As verification data, six types of mixed gases ( _CH4 - _H2 - _N2 ) containing methane gas, hydrogen gas, and nitrogen gas in different proportions were prepared. The calorific value Q (calculated calorific value) [MJ/ ^m3 ] calculated by the calorific value calculation means 33 of the third embodiment is plotted on the vertical axis, and the measured calorific value (actual calorific value) [MJ/ ^m3 ] is plotted on the horizontal axis. Circles indicate the calculated calorific value. The dashed line indicates a ±1% error range for the case where the calculated calorific value and the actual calorific value match (solid line). Additionally, the result of calculating the calorific value Q based on the corrected output value (H2) according to Equation 2 (which corrects the error due to the inclusion of only hydrogen gas) before correcting the error due to the inclusion of nitrogen gas using the additional corrected output value (H2) is plotted as an "output difference" marked with an x.

1A shows the results for a hydrogen gas to nitrogen gas ratio (H ₂ :N ₂ ) of 1:9, FIG. 1B shows the results for a H ₂ :N ₂ = 1:3, FIG. 1C shows the results for a H ₂ :N ₂ = 1:1, FIG. 1D shows the results for a H ₂ :N ₂ = 3:2, FIG. 1E shows the results for a H ₂ :N ₂ = 9:1, and FIG. 1F shows the results for a H ₂ :N ₂ = 10:0. As is clear from the figures, according to this embodiment, the calorific value Q of the (CH ₄ -H ₂ -N ₂ ) gas can be calculated with high accuracy, with an error of ±1% or less from the actual measured value.

17 is a graph comparing the calculation results (calculated calorific value) of the calorific value Q by the first method of the third embodiment with the actually measured calorific value (actual calorific value) for a reference gas containing an interference gas ((H _{2 +} CO 2 ) gas) with a clear component concentration. Five types of mixed gas (CH ₄ -H ₂ -CO ₂ gas) containing methane gas, hydrogen gas, and carbon dioxide gas in different proportions were prepared as verification data, and the calorific value Q (calculated calorific value) [MJ/m ³ ] calculated by the calorific value calculation means 33 of the third embodiment is plotted on the vertical axis, and the actually measured calorific value (actual calorific value) [MJ/m ³ ] is plotted on the horizontal axis. Circles indicate the calculated calorific value. The dashed line indicates an error range of ±1%. Additionally, the result of calculating the calorific value Q based on the corrected output value (H2) according to Equation 2 (which corrects the error due to the inclusion of only hydrogen gas) before correcting the error due to the inclusion of _CO2 gas using the additional corrected output value (H2) is plotted as an "output difference" marked with an x.

FIG. 1A shows the results for a hydrogen gas to _CO2 gas ratio ( _H2 : _CO2 ) of 2:3, FIG. 1B shows the results for a _H2 : _CO2 = 1:1 ratio, FIG. 1C shows the results for a _H2 : _CO2 = 3:2 ratio, and FIG. 1D shows the results for a _H2 : _CO2 = 9:1 ratio. Note that FIG. 1A plots data for _CO2 gas concentrations of 4 vol% or less, which is a substantial range. Although the data for a _H2 : _CO2 = 1:3 ratio is not shown, there was almost no difference between the "output difference" and the calculated results. As is clear from FIG. 1A, according to this embodiment, the calorific value Q can be calculated for ( _CH4 - _H2 - _CO2 ) gas with reduced error from the actual measured value.

FIG. 18 is _a graph comparing _the calculation results (calculated calorific value) of the calorific value Q by the first method of the third embodiment with the actually measured calorific value (actual calorific value) for a reference gas containing an interference gas (( _H 2 +N 2 +CO 2 ) gas) with a clear component concentration. As verification data, two mixed gases (CH ₄ -H ₂ -N ₂ -CO ₂ gas) containing methane gas, hydrogen gas, nitrogen gas, and carbon dioxide gas in different proportions were prepared, and the results are plotted on a coordinate system with the calorific value Q (calculated calorific value) [MJ/m ³ ] calculated by the calorific value calculation means 33 of the third embodiment on the vertical axis and the actually measured calorific value (actual calorific value) [MJ/m ³ ] on the horizontal axis. Circles indicate the calculated calorific value. The dashed line indicates an error range of ±1%. Additionally, the calorific value Q calculated based on the corrected output value (H2) according to Equation 2 (which corrects for errors due to the inclusion of only hydrogen gas) before the error due to the inclusion of _CO2 gas is corrected using the additional corrected output value (H2) is plotted as an "output difference" indicated by an x. In this figure, data for _CO2 gas concentrations of 4 vol% or less, which is the substantial range, is also plotted.

1A shows the results when the ratio of hydrogen gas, nitrogen gas, and _CO2 gas ( _H2 : _N2 : _CO2 ) is 6:1:1, and FIG. 1B shows the results when _H2 : _N2 : _CO2 is 2:1:1. As is clear from the figures, according to this embodiment, even for a mixed gas ( _CH4 - _H2 - _N2 - _CO2 ) containing hydrogen gas, nitrogen gas, and _CO2 gas as interference gases, the calorific value Q can be calculated with reduced error from the actual measured value.

19 is a graph comparing the calculation results (calculated calorific value) of the calorific value Q according to the third embodiment with the actually measured calorific value (actual calorific value) for a reference gas containing an interference gas ( _H2 gas) with a clear component concentration. As verification data, three mixed gases ( _CH4 - _{C2H6 -H2 gas} ) containing methane gas, ethane gas, and hydrogen gas in different ratios were prepared, and the calorific value Q (calculated calorific value) [MJ/ ^m3 ] calculated by the calorific value calculation means 33 of the third embodiment is plotted on the vertical axis, and the actually measured calorific value (actual calorific value) [MJ/ ^m3 ] is plotted on the horizontal axis. Circles indicate the calculated calorific value. The dashed line indicates an error range of ±1%. Additionally, the result of calculating the calorific value Q based on the corrected output value ( _H2 ) according to Equation 2 (which corrects the error due to the inclusion of only hydrogen gas) before correcting the error due to the inclusion of nitrogen gas using the additional corrected output value ( _H2 ) is plotted as the "output difference" with an x mark.

10A shows the results when the ratio of hydrogen gas to ethane gas (H ₂ :C ₂ H ₆ ) is 3:1, FIG. 10B shows the results when H ₂ :C ₂ H ₆ is 2:3, and FIG. 10C shows the results when H ₂ :C ₂ H ₆ is 1:3.

In the above-described embodiment, the first gas is methane gas, but the first gas may be a mixed gas of different paraffinic hydrocarbon gases. The figure shows the calculation results for a mixed gas in which the first gas is (CH ₄ -C ₂ H ₆ ) gas and contains hydrogen gas as an interference gas. Because hydrogen gas is the only interference gas, the calculation can be performed with high accuracy using the first embodiment (calculation of the calorific value _QA using the calorific value calculation formula (Formula 1) corrected for hydrogen gas only using Formula 2 ₎ . The figure reveals that the calculation method for the calorific value Q according to the third embodiment can achieve the same accuracy as the first embodiment, even for a mixed gas in which the first gas is (CH ₄ -C ₂ H 6 ) gas and contains hydrogen gas as an interference gas.

In addition, the present invention may also be a program capable of executing the heat calculation method of this embodiment described above.

According to this embodiment, the calorific value Q can be calculated by measuring the thermal conductivity and refractive index of a target gas containing paraffinic hydrocarbon gas and an interference gas that causes errors in the calorific value calculation. In other words, calorific value calculation is possible using a known measurement device capable of measuring thermal conductivity and refractive index (e.g., a thermal conductivity meter and a refractometer), making it possible to measure (calculate) calorific value with a low-cost, simple configuration.

In particular, even if the interference gas is a mixture of hydrogen gas and other gases (at least one of nitrogen gas and carbon dioxide gas) and the composition (mixing ratio, concentration) of the interference gas is unknown, the error factors caused by the interference gas can be eliminated or reduced, and the calorific value Q can be calculated accurately.

<Another embodiment (fourth embodiment)/hydrogen gas concentration calculation device (first configuration)>
Another embodiment of the present invention will be described with reference to Fig. 20. Fig. 20 is a schematic diagram showing a first configuration of a hydrogen gas concentration calculation device 70. The same components as those in the first to third embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

The hydrogen gas concentration calculation device 70 of this embodiment is capable of calculating the concentration of hydrogen gas contained in a target gas based on the thermal output of the target gas, which contains at least hydrogen gas. The target gas is a gas that contains, in addition to hydrogen gas, for example, a paraffinic hydrocarbon gas, preferably methane gas, at a concentration of 80 vol% or more, and may contain nitrogen gas and/or carbon dioxide gas in addition to hydrogen gas and methane gas.

The thermal output is, for example, thermal conductivity. Specifically, the hydrogen gas concentration calculation device 70 has a thermal conductivity measurement means 13, a gas concentration calculation means 146, an output means 18, etc., and the gas concentration calculation means 146 based on the thermal conductivity of the target gas has the same configuration as the third gas concentration calculation means 146 of the third embodiment. More specifically, the third gas concentration calculation means 146 is, for example, a means (hydrogen gas concentration calculation means) that calculates the hydrogen gas concentration X _H2 using the second method, and holds the slope-voltage function shown in FIG. 10(B), the _H2 proportion-voltage curve shown in FIG. 11(A), the output- _H2 proportion function shown in FIG. 11(B), and the hydrogen gas concentration calculation formula of Equation 10 (the first hydrogen gas concentration calculation formula of Equation 10A, or the second hydrogen gas concentration calculation formula of Equation 10B), and obtains the hydrogen gas concentration in the target gas based on these.

The method for calculating hydrogen gas concentration using the hydrogen gas concentration calculation device 70 is as follows. For example, the target gas (gas containing hydrogen gas of unknown composition) circulating in the gas pipeline 11 is supplied to the hydrogen gas concentration calculation device 70 via the gas flow path 19.

Then, a plurality of different voltages (for example, two or more, preferably five or more, and desirably ten or more) are applied to the thermal conductivity measuring means 13, and the respective normalized outputs _XT.C. are obtained.

Then, the hydrogen gas concentration in the target gas is calculated based on the slope-voltage function shown in FIG. 10(B), the H ₂ proportion-voltage curve shown in FIG. 11(A), the output- _{H 2} proportion function shown in FIG. 11(B), and Equation 10 (Equation 10A or Equation 10B).

The third gas concentration (hydrogen gas concentration) calculation means 146 of the hydrogen gas concentration calculation device 70 in the fourth embodiment may be configured to calculate the hydrogen gas concentration X _H2 by, for example, the first method (Equations 8 and 9).

In recent years, attempts have been made to introduce hydrogen gas into natural gas-derived city gas and other gases. According to the present invention, it is possible to calculate the calorific value and/or hydrogen gas concentration of a mixed gas in which hydrogen gas, biogas, coke oven gas, etc. have been introduced into natural gas at any concentration, using a relatively simple configuration.

<Hydrogen gas concentration calculation device>
The hydrogen gas concentration calculation device will be further described below with reference to Figures 21 to 32. The same components as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. First, Figure 21 is a schematic diagram illustrating the configuration of another example of a hydrogen gas concentration calculation device 71 (second configuration).

The hydrogen gas concentration calculation device 71 is capable of calculating the concentration of hydrogen gas contained in a target gas based on the thermal output of the target gas, which contains at least hydrogen gas. The target gas is, for example, natural gas, and preferably a mixed gas containing paraffinic hydrocarbon gas, hydrogen gas, nitrogen gas, and/or carbon dioxide gas. Specifically, the hydrogen gas concentration calculation device 71 has at least a means capable of generating thermal output (e.g., thermal conductivity measurement means 13), a difference calculation means 141, and a hydrogen gas concentration calculation means 149.

The difference calculation means 141 is the same as in the above embodiment. That is, the difference calculation means 141 is a means for calculating the difference ΔI (= I 1 - I 2 ) between the standardized (normalized) output (current value) obtained by applying a first voltage V1 to the thermal conductivity measurement means 13 (standardized current value I ₁ ) and the standardized (normalized) second output (current value) obtained by applying a second voltage V2 (standardized current value I ₂ ). Note that the standardized current values _{I 1 and} I ₂ are the standardized outputs _XT.C. in the above embodiment, and in the following description, they will be referred to as standardized current values I, I ₁ , _and I _{2 ,} but these can be replaced with standardized outputs _{XT.C., XT.C1, and XT.C2} . Furthermore, the difference ΔI is the output difference (H ₂ ) in the above embodiment, and will be described as the output difference ΔI in the following description, but this can be replaced with the output difference (H ₂ ).

The hydrogen gas concentration calculation means 149 has the following equation 14 and calculates the hydrogen gas concentration _xH2 in the target gas based on the output difference ΔI obtained by the difference calculation means 141.
is.

Note that a is a constant that is selected appropriately; for example, a = 20 to 30, preferably a = 25 to 27, and more preferably a = 26.4.

This hydrogen gas concentration calculation device 71 is highly convenient in that the only measurement means for the target gas is the thermal conductivity measurement means 13, and the calculation process for the hydrogen gas concentration is simple (not complicated).

Figure 22 is a graph showing the calculation results of the hydrogen gas concentration calculation device 70 shown in Figure 21, and is a graph in which the results (measured _H2 concentration [vol%]) measured (calculated) by the hydrogen gas concentration calculation device 70 shown in Figure 21 (using Equation 14) for multiple reference gases containing hydrogen gas and with known component concentrations are plotted on the vertical axis, and the known (actual) hydrogen gas concentration _H2 [vol%] is plotted on the horizontal axis.

The reference gases in Figure 1 (A) are mixed gases similar to the reference gases in Figure 8, namely, seven types of mixed gases ((CH ₄ -H ₂ -N ₂ ) gas) containing methane gas, hydrogen gas, and nitrogen gas in different proportions, a mixed gas ((CH ₄ -H ₂ ) gas) containing methane gas and hydrogen gas, and a mixed gas ((CH ₄ -N ₂ ) gas) containing methane gas and nitrogen gas. In Figure 1A, the nitrogen gas ratios are indicated by circles ( _H2 : _N2 = 1:0), triangles ( _H2 : _N2 = 9:1), squares ( _H2 : _N2 = 3:1), diamonds ( _H2 : _N2 = 3:2), crosses ( _H2 : _N2 = 1:1), circles ( _H2 : _N2 = 2:3), triangles ( _H2 : _N2 = 1:3), squares ( _H2 : _N2 = 1:9), and diamonds ( _H2 : _N2 = 0:1), in descending order of nitrogen gas ratio. Circles represent results for _CH4 - _H2 gas, and diamonds represent results for _CH4 - _N2 gas. The solid lines indicate a ±1% error range for cases where the measured H2 concentration and the actual hydrogen gas concentration H2 match.

Note that the reference gas shown in Figure 22 contains the same types of gases as the reference gas in Figure 8, but the concentrations of each gas are different. Figure 23 shows an example of the concentrations (measured values) of hydrogen gas and nitrogen gas in the above ratios contained in the multiple reference gases shown in Figure 22 (A). Furthermore, in each reference gas, the concentration of methane gas is a value excluding the combined concentration of hydrogen gas and nitrogen gas. Furthermore, the concentration of nitrogen gas contained in actual target gas is often 5 vol% or less, and the concentration of carbon dioxide gas is often 2 vol% or less. Therefore, the following explanation will be based on the case where the concentration of nitrogen gas contained in the reference gas is 5 vol% or less, and the concentration of carbon dioxide gas is 2 vol% or less.

22(B) shows the case of reference gases (( _CH4 - _H2 - _CO2 ) gas, ( _CH4 - _H2 ) gas, ( _CH4 - _CO2 ) gas) in which the nitrogen gas in FIG. 22(A) is replaced with carbon dioxide gas, and the ratios from lowest to highest are indicated by circles ( _H2 : _CO2 = 1:0), triangles ( _H2 : _CO2 = 9:1), squares ( _H2 : _CO2 = 3:2), crosses ( _H2 : _CO2 = 1:1), black circles ( _H2 : _CO2 = 2:3), triangles ( _H2 : _CO2 = 1:3), and squares ( _H2 : _CO2 = 0:1). All other aspects are the same as FIG. 22(A).

Figure 24 shows an example of the concentrations (measured values) of hydrogen gas and carbon dioxide gas in the above ratio contained in the multiple reference gases shown in Figure 22 (B). Furthermore, for each reference gas, the concentration of methane gas is the value excluding the combined concentration of hydrogen gas and carbon dioxide gas.

Figure 22 (C) shows _the case of a reference gas (( _CH4 - _C2H6 - _H2 ) gas, ( _CH4 - _H2 ) gas, ( _CH4 - _C2H6 ) gas) in which methane gas is mixed with ethane gas and/or hydrogen gas, and _{the ratios from lowest to highest are indicated by circles (H2:C2H6 = 1:0), triangles (H2:C2H6 = 3 : 1 ) , circles} ( _H2 : _C2H6 = 2:3), triangles ( _H2 : _C2H6 = 1: ₃ ), squares ( _H2 : _C2H6 = 1:9), and diamonds _{( H2 : C2H6} = 0:1).

Figure 25 shows an example of the concentrations (measured values) of hydrogen gas and ethane gas in the above ratio contained in the multiple reference gases shown in Figure 22 (C). Furthermore, for each reference gas, the concentration of methane gas is a value excluding the combined concentration of hydrogen gas and ethane gas.

Figure 22 (D) shows the case of a reference gas (( _CH4 - _H2 ) gas) made by mixing methane gas with hydrogen gas, and a reference gas (( _CH4 - _H2 - _N2 - _CO2 ) gas) made by mixing methane gas with nitrogen gas, carbon dioxide gas, and hydrogen gas, and the gases with the highest hydrogen gas ratio are indicated by circles ( _H2 : _N2 : _CO2 = 1:0:0), triangles ( _H2 : _N2 : _CO2 = 6:1:1), and black circles ( _H2 : _N2 : _CO2 = 2:1:1).

Figure 26 shows an example of the concentrations (measured values) of hydrogen gas, nitrogen gas, and carbon dioxide gas in the above ratios contained in the multiple reference gases shown in Figure 22 (D). Furthermore, for each reference gas, the concentration of methane gas is a value excluding the total concentration of hydrogen gas, nitrogen gas, and carbon dioxide gas.

From these results, it can be seen that the calculation result (measured _H2 concentration) of the hydrogen gas concentration calculation means 149 (Equation 14) has a larger error from the actual hydrogen gas concentration as the content ratio of nitrogen gas and/or carbon dioxide gas increases, regardless of the reference gas.

In other words, while the hydrogen gas concentration calculation device 71 shown in Figure 21 has a simple configuration and can be easily implemented, it is prone to errors due to the inclusion of interfering gases (especially nitrogen gas and/or carbon dioxide gas), and therefore can be said to be useful when errors due to interfering gases are not strict or when the content of nitrogen gas and/or carbon dioxide gas is low.

20 (hydrogen gas concentration calculation means 146 that performs calculations using Equation 10) is a device that can reduce errors caused by the inclusion of such nitrogen gas and/or carbon dioxide gas. According to this, by performing calculations using the first hydrogen gas concentration calculation formula (Equation 10A) or the second hydrogen gas concentration calculation formula (Equation 10B), both of which use the second-order derivative of the normalized current value I with respect to the applied voltage V (d ² I/dV ² , hereinafter also simply referred to as the "second-order derivative of the normalized current value I"), it is possible to reduce the error between the calculated hydrogen gas concentration value (measured H concentration [vol%]) and the actual hydrogen gas concentration H ₂ [vol%], even when the target gas contains nitrogen gas and/or carbon dioxide gas.

Again, referring to FIG. 10(B), the slope dI/dV of the output-voltage function (FIG. 10(A)) and the applied voltage V have a proportional relationship depending on the proportion of hydrogen gas. This means that even if the target gas contains nitrogen gas and/or carbon dioxide gas, the influence of these gases can be eliminated by using the "slope-voltage function" shown in FIG. 10(B). In other words, the slope of the "slope-voltage function" shown by the solid line in FIG. 10(B) becomes a constant value depending on the hydrogen gas concentration _xH2 , particularly when the hydrogen gas concentration _xH2 is 10 vol% or less, and is expressed by the following equation 15.
is.

Equation 15 shows the calculation using the first hydrogen concentration calculation equation (Equation 10A) described above to calculate the hydrogen gas concentration. In other words, "1/f" (V) (10 vol%) x 10" in Equation 10(a) is a constant, and Equation 15 is obtained by replacing this with the constant a.

27 is a graph showing the error between the calculation result (measured _H2 concentration) and the actual hydrogen gas concentration ( _H2 concentration) using the first hydrogen concentration calculation formula (Formula 10A). For each of a number of reference gases with clear hydrogen gas compositions, 16 different voltages V16 to V1 were applied to the thermal conductivity measurement means 13 of the hydrogen gas concentration calculation device 70 shown in FIG. 20. The normalized current values I16 to I1 were approximated to a quadratic curve to obtain an "output-voltage function" (FIG. 10A). The differential value of the slope dI/dV (the second-order differential value of the normalized current value I) was used to calculate the hydrogen gas concentration _XH2 using Formula 10A. The result (measured _H2 concentration [vol%]) was plotted on the vertical axis, and the actual mixed hydrogen gas concentration (H2 concentration [vol%]) was plotted on the horizontal axis. The reference gases, including their compositions, are the same as those described in the graph shown in Figure 22, with Figure 27 (A) being for ( _CH4 - _H2 - _N2 ) gas, ( _{CH4 - H2} ) gas and ( _CH4 - _N2 ) gas, Figure 27 (B) being for ( _CH4 - _H2 - _CO2 ) gas, (CH4- _H2 ) gas and ( _CH4 - _CO2 ) gas, Figure 27 (C) being for ( _CH4 - _{C2H6 -H2 )} gas, ( _CH4 - _H2 ) gas and ( _CH4 - _C2H6 ) gas, _and Figure 27 (D) being for ( _CH4 - _H2 ) gas and ( _CH4 - _H2 - _N2 - _CO2 ) gas.

As is clear from these results, according to the hydrogen gas concentration measuring device 70 (Equation 10A) shown in FIG. 20, the error between the measured (calculated) hydrogen gas concentration (measured _H2 concentration) and the actual hydrogen gas concentration ( _H2 concentration) can be kept within approximately ±1 vol%.

Here, when the hydrogen gas concentration _xH2 is up to 10 vol%, the second-order differential value of the normalized current value I and the hydrogen gas concentration _xH2 change linearly, so Equation 10A (Equation 15) is used. When the hydrogen gas concentration _xH2 exceeds 10 vol%, the second-order differential value of the normalized current value I and the hydrogen gas concentration _xH2 change in a curved manner, so Equation 10(B) using an approximation curve is used.

Figure 28 is a schematic diagram showing the configuration (third configuration) of yet another hydrogen gas concentration calculation device 72 according to this embodiment. This hydrogen gas concentration calculation device 72 is also capable of calculating the concentration of hydrogen gas contained in a target gas containing at least hydrogen gas based on the thermal output of the target gas, and calculates the hydrogen gas concentration based on the thermal output of the target gas and multiple physical property values.

Here, the multiple physical property values of the target gas are multiple physical property values that have a predetermined correlation with the calorific value of the paraffinic hydrocarbon gas contained in the target gas, and examples include refractive index (proportional to the calorific value) and density (inversely proportional to the calorific value).

Specifically, the hydrogen gas concentration calculation device 72 has, for example, a means capable of thermal output (e.g., a thermal conductivity measuring means 13), a difference calculation means 141, a refractive index converted calorific value calculation means 32, a density converted calorific value calculation means 55, a hydrogen gas concentration calculation means 150, and an output means 18.

The thermal conductivity measuring means 13, difference calculation means 141, and refractive index converted heat quantity calculation means 32 have the same configuration as described in the above embodiment (Figure 4, etc.), so their description will be omitted.

The density converted calorific value calculation means 55 is a means for acquiring the density converted calorific value _QC , and may be, for example, a device configured to measure the density converted calorific value _QC of the target gas based on the amount of change in the resonant frequency, utilizing the fact that the resonant frequency changes based on the density of the target gas when a vibrating tube made of a thin-walled cylindrical body is vibrated in the target gas. Since the calorific value and density of paraffinic hydrocarbon gas are inversely proportional to each other, acquiring the density of the target gas allows conversion into calorific value.

The density-converted calorific value calculation means 55 may be configured to include, for example, a tube through which the target gas flows and a sound speed measurement means (sound speed sensor) equipped with a sound wave source and a sound wave receiving source disposed at both ends of the tube. The sound wave source emits sound toward the tube through which the target gas flows, and the time it takes for the sound to propagate through the by-product gas and reach the receiving source is measured, thereby accurately determining the speed of sound propagating through the measurement gas. The density of the target gas (= specific heat ratio × pressure / sound speed ² ) may then be calculated based on the sound speed measured by the sound speed measurement means, thereby determining the density-converted calorific value _QC .

The hydrogen gas concentration calculation means 150 calculates the hydrogen gas concentration xH2 in the target gas using the output difference ΔI calculated by the difference calculation means 141, the refractive index converted calorific value _QB calculated by the refractive index converted calorific value calculation means 32, and the density converted calorific value _QC calculated by the density converted calorific value calculation means ₅₅ , and the following equation 16. Equation 16 is hereinafter referred to as the "third hydrogen concentration calculation equation."
is.

The constants a, b, and c are values that can be selected as appropriate. One example is a = -25 to -27, preferably a = -26 to -26.5, and more preferably a = -26.4. Another example is b = 0.8 to 1.0, preferably b = 0.85 to 0.95, and more preferably b = 0.916. Another example is c = 0.8 to 1.0, preferably c = 0.85 to 0.95, and more preferably c = 0.916.

Here, we will explain Equation 16. As shown in Equation 14, the hydrogen gas concentration X _H2 in the target gas can basically be calculated if the output difference ΔI calculated by the thermal conductivity measuring means 13 and the difference calculating means 141 can be obtained. However, if the target gas also contains nitrogen gas and carbon dioxide gas, an error will occur in the calculation result. Therefore, if the nitrogen gas concentration X _N2 and the carbon dioxide gas concentration X _CO2 are known, appropriate corrections can be made according to these concentrations. In other words, as shown in Equation 16.1 (details will be described later), it is possible to add correction terms according to the nitrogen gas concentration X _N2 and the carbon dioxide gas concentration X _CO2 to the right side of Equation 14. However, the composition of the target gas to be actually measured (nitrogen gas concentration X _N2 and carbon dioxide gas concentration X _CO2 ) is unknown.

The applicant of the present application has developed a unique method for calculating the calorific value _Q of a target gas using the following equation 17, based on the refractive index converted calorific value _QB obtained from the refractive index of the target gas and the density converted calorific value QC obtained from the density of the target gas, under the condition of 2.40≦correction coefficient α≦3.11 (this method is described in detail in Japanese Patent No. 5184983):
is.

Furthermore, as a result of considerations by the applicant of the present application, it has been found that when natural gas contains nitrogen gas and carbon dioxide gas, the total value (actual value) of the nitrogen gas concentration X _N2 and the carbon dioxide gas concentration X _CO2 can be approximated to the value obtained by multiplying only the actual value of the carbon dioxide gas concentration X _CO2 and adding them together, and that there is a relationship shown in Equation 18 between this approximated total value of the nitrogen gas concentration X _N2 and the carbon dioxide gas concentration X _CO2 (approximate total concentration) and the refractive index converted calorific value Q _B and density converted calorific value Q _C shown in Equation 17 (the right side of Equation 18 is the approximate total concentration).
is.

That is, in calculating the hydrogen gas concentration, even if the respective concentrations are unknown, if the total approximate concentration (X _N2 + 1.55X _CO2 ) can be obtained as a correction term for the error corresponding to the nitrogen gas concentration X _N2 and _the carbon dioxide gas concentration X CO2, the error due to the influence of nitrogen gas and carbon dioxide gas can be corrected using the above formula 16.1 to calculate the hydrogen gas concentration X _H2 .

Furthermore, even if the actual nitrogen gas concentration x _N2 and carbon dioxide gas concentration X _CO2 , or their approximate total concentration, are unknown, by using the refractive index converted calorific value Q _B and the density converted calorific value Q _C as substitutes for the concentrations of both, errors due to the influence of nitrogen gas and carbon dioxide gas can be corrected using the above equation 16 (third hydrogen concentration calculation equation) to calculate the hydrogen gas concentration X _H2 .

Here, the third hydrogen concentration calculation formula also calculates the hydrogen gas concentration based on the relationship between the applied voltage to a thermal conductivity meter (e.g., thermal conductivity measuring means 13) and the normalized current value I, and is included in the second method of calculating hydrogen gas concentration described above.

The above physical property value may be the sonic velocity, which is proportional to the calorific value of the paraffinic hydrocarbon gas. That is, although not shown, the hydrogen gas concentration measuring device 72 may have a sonic velocity converted calorific value measuring means instead of the density converted calorific value measuring means 55. The sonic velocity converted calorific value measuring means has a sonic velocity measuring means (e.g., a sonic velocity sensor), and calculates the calorific value of the target gas (sonic velocity converted calorific value) from the measurement results. This sonic velocity converted calorific value can be treated as equivalent to the above density converted calorific value QC, and the same effect as above can be obtained.

FIG. 29 is a graph showing the error between the calculation result (measured _H2 concentration) using the third hydrogen concentration calculation formula (Equation 16) and the actual hydrogen gas concentration ( _H2 concentration). For each of a number of standard gases with known hydrogen-containing compositions, two different voltages V1 and V2 were applied to the thermal conductivity measurement means 13 of the hydrogen gas concentration calculation device 72 shown in FIG. 28, and the output difference ΔI between the resulting normalized current values I1 and I2 was calculated. The refractive index of the standard gas was measured to obtain the refractive index converted calorific value _QB , and the density of the standard gas was measured to obtain the density converted calorific value _QC . The hydrogen gas concentration _XH2 was then calculated based on the third hydrogen concentration calculation formula (Equation 16). The results (measured _H2 concentration [vol%]) were plotted on the vertical axis, and the actual mixed hydrogen gas concentration ( _H2 concentration [vol%]) was plotted on the horizontal axis. The reference gases, including their compositions, are the same as those described in the graph shown in Figure 22, with Figure 29 (A) being for ( _CH4 - _H2 - _N2 ) gas, ( _{CH4 - H2} ) gas and ( _CH4 - _N2 ) gas, Figure 29 (B) being for ( _CH4 - _H2 - _CO2 ) gas, (CH4- _H2 ) gas and ( _CH4 - _CO2 ) gas, Figure 29 (C) being for ( _CH4 - _{C2H6 -H2 )} gas, ( _CH4 - _H2 ) gas and ( _CH4 - _C2H6 ) gas, _and Figure 29 (D) being for ( _CH4 - _H2 ) gas and ( _CH4 - _H2 - _N2 - _CO2 ) gas.

As is clear from these results, the hydrogen gas concentration measuring device 72 (Equation 16) shown in Figure 28 can keep the error between the measured (calculated) hydrogen gas concentration (measured _H2 concentration) and the actual hydrogen gas concentration ( _H2 concentration) to approximately ±1 vol%. Furthermore, this error is smaller (no variation) than the error of the hydrogen gas concentration measuring device 70 (Equation 10A), and in particular when only nitrogen gas (and hydrogen gas) are present (Figure 29(A)), the results are nearly consistent with the actual measured value.

Next, multiple mixed gases close to the composition of realistic natural gas were prepared, and hydrogen gas with a known concentration was mixed with these to create reference gases. The hydrogen gas concentration XH2 was measured using a hydrogen gas concentration measuring device 70 shown in FIG. 20 (a method using the first hydrogen concentration calculation formula (Formula 10A)) and a hydrogen gas concentration measuring device 72 shown in FIG. 28 (a method using the third hydrogen concentration calculation formula (Formula 16)). FIG. ₃₀ is a table summarizing the compositions and calorific values of the eight types of mixed gases (Gas No. 1 to No. 8) prepared. In addition, 0, 5, 10, 15, 20, 25, and 30 vol% hydrogen gas were mixed with these eight types of mixed gases, respectively, to create the reference gases to be measured.

31 shows the measurement results of the hydrogen gas concentration measuring device 70 shown in FIG. 20 (a method using the first hydrogen concentration calculation formula (Formula 10A)). FIG. 31 (A) is a graph plotting the measured (calculated) hydrogen gas concentration (measured _H2 concentration) on the vertical axis and the actual hydrogen gas concentration ( _H2 concentration) on the horizontal axis, comparing the errors between the two. FIG. 31 (B) is a graph plotting the error value of FIG. 31 (A) on the vertical axis and the actual hydrogen gas concentration ( _H2 concentration) on the horizontal axis, clearly showing the variation in error values due to hydrogen gas concentration. Note that the hydrogen gas concentration on the horizontal axis is the result of measuring the concentration of substantially mixed hydrogen gas with an optical interferometer, and there is a slight deviation from the planned values for the mixture (0, 5, 10, 15, 20, 25, 30 [vol%]).

Gas No. 1 (gas mixed with hydrogen gas, same below) is indicated by a circle, Gas No. 2 by a triangle, Gas No. 3 by a square, Gas No. 4 by a ◇, Gas No. 5 by a ●, Gas No. 6 by a ▲, Gas No. 7 by a ■, and Gas No. 8 by a ◆.

As a result, it became clear that the hydrogen gas concentration measuring device 70 shown in FIG. 20 (a method using the first hydrogen concentration calculation formula (Formula 10A)) can keep the measurement error for the actual hydrogen gas concentration ( _H2 concentration) within ±2 vol% regardless of the hydrogen gas concentration, making it possible to perform highly accurate measurements.

Figure 32 shows the measurement results of the hydrogen gas concentration measuring device 72 shown in Figure 28 (method using the third hydrogen concentration calculation formula (Equation 16)), where Figure 32 (A) is a graph corresponding to Figure 31 (A) and Figure 32 (B) is a graph corresponding to Figure 31 (B).

As a result, it became clear that the hydrogen gas concentration measuring device 70 shown in FIG. 28 (a method using the third hydrogen concentration calculation formula (Formula 16)) can keep the measurement error for the actual hydrogen gas concentration ( _H2 concentration) within ±1 vol% regardless of the hydrogen gas concentration, making it possible to perform measurements with even higher accuracy.

As described above, the hydrogen gas concentration measuring devices 70, 72 according to this embodiment are devices that calculate the concentration of hydrogen gas contained in a target gas containing at least hydrogen gas (particularly, a gas containing at least nitrogen gas and/or carbon dioxide gas in addition to paraffinic hydrocarbon gas) based on at least the thermal output (e.g., thermal conductivity) of the target gas. Furthermore, the hydrogen gas concentration measuring method according to this embodiment is a method that calculates the concentration of hydrogen gas contained in a target gas containing at least hydrogen gas (particularly, a gas containing at least nitrogen gas and/or carbon dioxide gas in addition to paraffinic hydrocarbon gas) based on at least the thermal output (e.g., thermal conductivity).

As an example, the hydrogen gas concentration measuring device 70 includes a thermal conductivity measuring means 13 and a hydrogen gas concentration calculation means 146, and the hydrogen gas concentration calculation means 146 has a first hydrogen concentration calculation formula (Equation 10A) or a second hydrogen concentration calculation formula (Equation 10B).

In addition, both the first hydrogen concentration calculation formula (Formula 10A) and the second hydrogen concentration calculation formula (Formula 10B) are calculation formulas that use the second-order differential value with respect to the voltage of the normalized output (normalized current value I) of the thermal conductivity measuring means 13.

In addition, the hydrogen gas concentration measurement method includes a step of measuring the thermal output (thermal conductivity) of the target gas when two or more different voltages are applied to obtain a standardized current value, and a step of calculating the hydrogen gas concentration in the target gas based on the value of the second-order derivative of the standardized current value I with respect to the voltage.

In addition, the calculation of the hydrogen gas concentration based on the value of the second derivative is performed using the first hydrogen gas concentration calculation formula (Formula 10A) or the second hydrogen gas concentration calculation formula (Formula 10B).

As another example, the hydrogen gas concentration measuring device 72 has a thermal conductivity measuring means 13, a difference calculation means 141, a refractive index converted heat power measuring means 32, a density converted heat power measuring means 55, and a hydrogen gas concentration calculation means 150, and the hydrogen gas concentration calculation means 150 has a third hydrogen concentration calculation formula (formula 16).

The hydrogen gas concentration measurement method also includes the steps of measuring the thermal output (thermal conductivity) of a target gas when two different voltages are applied, and calculating the difference in normalized current values corresponding to the two voltages (output difference ΔI), and calculating the hydrogen gas concentration of the target gas using a third hydrogen gas concentration calculation formula (Formula 16) based on the output difference _ΔI , the refractive index converted calorific value _QB , and the density converted calorific value QC.

In addition, this embodiment may be configured as a program capable of causing a computer to execute each step of the above-mentioned hydrogen gas concentration measurement method.

The thermal output may be a thermal output other than thermal conductivity. Furthermore, the sonic velocity of the target gas may be used instead of the density of the target gas.

In recent years, hydrogen gas has been added to natural gas pipelines in some cases, and there is a demand for a simple system to check the amount of added hydrogen gas. Furthermore, when calculating the compression coefficient of natural gas, for example, there is a demand for a system that can separate and detect only the hydrogen gas concentration in natural gas for the purpose of correcting calculations.

20 (a hydrogen gas concentration calculation method using the first hydrogen gas concentration calculation formula (Formula 10A)), by measuring the thermal output (for example, thermal conductivity) of the target gas, it is possible to calculate the hydrogen gas concentration _XH2 in the target gas while reducing errors due to nitrogen gas and carbon dioxide gas in the target gas (by eliminating the effects of these as much as possible). The measurement means for the target gas can be configured using only a general thermal conductivity measurement means 13, which makes it possible to measure (calculate) the hydrogen gas concentration _XH2 with high accuracy while being simple and inexpensive.

Furthermore, according to the hydrogen gas concentration calculation device 72 shown in FIG. 28 (a hydrogen gas concentration calculation method using the third hydrogen gas concentration calculation formula (Equation 16)), by measuring the physical properties of the target gas, specifically the refractive index and density (or speed of sound) in addition to the thermal output (e.g., thermal conductivity) of the target gas, it is possible to further reduce errors due to nitrogen gas and carbon dioxide gas in the target gas (almost eliminating their effects) and calculate the hydrogen gas concentration _XH2 in the target gas. Although the measurement means for the target gas requires a refractive index and density (or speed of sound) measurement means in addition to a general thermal conductivity measurement means 13, both can be configured with a general optical interferometer or sound speed sensor, and errors due to nitrogen gas and carbon dioxide gas can be further reduced compared to the hydrogen gas concentration measurement device 70 shown in FIG. 20. Furthermore, even if the composition of the target gas (particularly the nitrogen gas concentration _XN2 and the carbon dioxide gas concentration _XCO2 ) is unknown (without measuring these concentrations), the hydrogen gas concentration in the target gas can be measured (calculated) with high accuracy simply by measuring the target gas itself.

Note that the constants and/or coefficients in each equation in this embodiment are valid within each equation, and even if there are duplicate notations as constants and/or coefficients between different equations, they do not represent the same value.

In the specification and drawings, _XN2 , _xN2 , and _xN2 all represent nitrogen gas concentrations, _XCO2 , _xCO2 , and _xCO2 all represent carbon dioxide concentrations, and _XH2 , _xH2 , and _xH2 all represent hydrogen gas concentrations.

In the above embodiment, natural gas and biogas are used as examples of target gases, but this is not limited to these. The target gas can also be coke oven gas (COG), coal gasification (solid coal converted into gaseous fuel gas), naphtha gasification (naphtha converted into gaseous fuel gas), etc.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from its spirit and technical concept.

10 Calorie measuring device 11 Gas pipeline 12 Thermal conductivity converted calorie measuring means 13 Thermal conductivity measuring means 14 Correction means 15 Converted calorie calculation means 18 Output means 30 Calorie measuring device 31 Thermal conductivity converted calorie measuring means 32 Refractive index converted calorie measuring means 33 Calorie calculation means 35 Calorie measuring devices 70, 71, 72 Hydrogen gas concentration measuring devices 146, 149, 150 Third gas concentration calculation means 147 Additional corrected output value calculation means 50 Explosion-proof container 141 Difference calculation means 142 Corrected output value calculation means A Thermal conductivity converted calorie Q _B Refractive index converted calorie Q Calorie CF Correction coefficient

Claims (17)

A calorimetry device for measuring the calorific value of a target gas,
a thermal conductivity converted calorific value measuring means capable of measuring the calorific value obtained from the thermal conductivity of the target gas;
the target gas contains a first gas as a main component and a second gas that is a measurement error component,
the thermal conductivity converted calorific value measuring means calculates the calorific value of the target gas by correcting an error due to the second gas with respect to the measured output of the target gas based on a relational expression indicating a correlation between the output measured by the thermal conductivity measuring means, which is acquired in advance for a plurality of first gases as references, and the actual calorific value;
The thermal conductivity converted calorific value measuring means
Correction means;
A converted heat quantity calculation means,
The correction means
a difference calculation means for calculating a difference between a first output and a second output measured by applying different voltages to the thermal conductivity measurement means for the target gas;
a corrected output value calculation means for calculating a corrected output value of the target gas based on the difference;
The converted heat amount calculation means
Calculating the calorific value of the target gas based on the corrected output value and the relational expression.
A calorimetric device characterized by: A calorimetry device for measuring the calorific value of a target gas,
a thermal conductivity converted calorific value measuring means capable of measuring the calorific value obtained from the thermal conductivity of the target gas ;
the target gas contains a first gas as a main component and a second gas that is a measurement error component ,
the first gas is a paraffinic hydrocarbon gas,
the second gas is any one of hydrogen gas, carbon dioxide gas, and nitrogen gas;
the thermal conductivity converted calorific value measuring means calculates the calorific value of the target gas by correcting an error due to the second gas with respect to the measured output of the target gas based on a relational expression indicating a correlation between the output measured by the thermal conductivity measuring means and the actual calorific value , the relational expression being acquired in advance for a plurality of first gases as references ;
A calorimetric device characterized by: the correcting means calculates the corrected output value using a correction formula that is set based on the difference for each type of the second gas.
2. The calorimetric device according to claim 1 . A calorific value calculation method for calculating a calorific value of a gas, comprising:
The target gas contains a first gas as a main component and a second gas that is a measurement error component ,
and calculating the calorific value of the target gas by correcting an error due to the second gas with respect to the measured output of the target gas based on a relational expression showing a correlation between a measured value of thermal conductivity of the first gas obtained in advance for a plurality of reference gases and an actual calorific value,
applying a first voltage to a thermal conductivity measuring means to measure the target gas and obtain a first output;
applying a second voltage to the thermal conductivity measuring means to measure the target gas and obtain a second output;
obtaining a corrected output value for the target gas based on a difference between the first output and the second output;
and calculating the calorific value of the target gas based on the corrected output value and the relational expression.
A method for calculating calorie content. A calorific value calculation method for calculating a calorific value of a gas, comprising:
The target gas contains a first gas as a main component and a second gas that is a measurement error component,
the first gas is a paraffinic hydrocarbon gas,
the second gas is any one of hydrogen gas, nitrogen gas, and carbon dioxide gas;
calculating the calorific value of the target gas by correcting an error due to the second gas with respect to the measured output of the target gas based on a relational expression indicating a correlation between a measured value of thermal conductivity of the first gas and an actual calorific value, the measured value being obtained in advance for a plurality of reference gases;
A method for calculating calorie content. the corrected output value is calculated using a correction formula that is set for each type of the second gas based on the difference.
5. The method for calculating the amount of heat according to claim 4 . A calorimetry device for measuring the calorific value of a target gas,
a thermal conductivity converted calorific value measuring means capable of measuring a thermal conductivity converted calorific value obtained from the thermal conductivity of the target gas;
a refractive index converted calorific value measuring means capable of measuring a refractive index converted calorific value obtained from the refractive index of the target gas;
a heat quantity calculation means,
the target gas contains a first gas as a main component and a third gas and a fourth gas that become measurement error components,
the thermal conductivity converted calorific value measuring means is configured to be able to calculate the thermal conductivity converted calorific value by correcting an error due to the third gas based on a relational expression indicating a correlation between an output measured by the thermal conductivity measuring means for a plurality of the first gases and an actual calorific value,
the heat quantity calculation means calculates the heat quantity of the target gas using the thermal conductivity converted heat quantity, the refractive index converted heat quantity, and a coefficient for correcting an error due to the fourth gas .
A calorimetric device characterized by: The thermal conductivity converted calorific value measuring means
Correction means;
A converted heat quantity calculation means,
The correction means
a difference calculation means for calculating a difference between a first output and a second output measured by applying different voltages to the thermal conductivity measurement means for the first gas ;
a corrected output value calculation means for calculating a corrected output value of the first gas based on the difference;
The thermal conductivity converted calorific value measuring means
calculating the thermal conductivity converted heat quantity based on the corrected output value and the relational expression;
8. The calorimetric device according to claim 7 . a third gas concentration calculation means for acquiring a concentration of the third gas in the target gas (hereinafter referred to as a "third gas concentration") based on the thermal conductivity of the target gas;
and additional correction output value calculation means for further correcting the corrected output value by an additional correction amount based on the third gas concentration to obtain an additional correction output value,
the thermal conductivity converted calorific value measuring means calculates the thermal conductivity converted calorific value based on the additional corrected output value and the relational expression ;
9. The calorimetric device according to claim 8, further comprising: the additional correction output value calculation means calculates a concentration of the fourth gas in the target gas (hereinafter referred to as "fourth gas concentration") in accordance with the third gas concentration, and calculates the additional correction amount based on the third gas concentration and the fourth gas concentration ;
10. The calorimetric device according to claim 9. the first gas is a paraffinic hydrocarbon gas,
the third gas is hydrogen gas;
The fourth gas is at least one of nitrogen gas and carbon dioxide gas.
11. The calorimetric device according to claim 7, wherein the calorimetric device is a thermocouple . A calorific value calculation method for calculating the calorific value of a target gas, comprising:
the target gas contains a first gas as a main component and a third gas and a fourth gas that become measurement error components,
a step of calculating a heat quantity obtained from the thermal conductivity of the target gas (hereinafter referred to as "thermal conductivity converted heat quantity") by correcting an error due to the third gas based on a relational expression showing a correlation between measured values of thermal conductivity and actual heat quantities for the plurality of first gases;
A step of obtaining a calorific value obtained from the refractive index of the target gas (hereinafter referred to as "refractive index converted calorific value");
calculating the calorific value of the target gas using the thermal conductivity converted calorific value, the refractive index converted calorific value, and a coefficient for correcting an error due to the fourth gas ;
A method for calculating a calorie amount , comprising : applying a first voltage to a thermal conductivity measuring means to measure the target gas and obtain a first output;
applying a second voltage to the thermal conductivity measuring means to measure the target gas and obtain a second output;
obtaining a corrected output value for the target gas based on a difference between the first output and the second output;
calculating the thermal conductivity converted heat quantity based on the corrected output value and the relational expression;
The method for calculating the amount of heat according to claim 12 , further comprising : acquiring a concentration of the third gas in the target gas (hereinafter referred to as "third gas concentration") based on the thermal conductivity of the target gas;
further correcting the corrected output value by an additional correction amount based on the third gas concentration to obtain an additional corrected output value;
calculating the thermal conductivity converted heat quantity based on the additional corrected output value and the relational expression ;
The method for calculating the amount of heat according to claim 13, further comprising : calculating a concentration of the fourth gas in the target gas (hereinafter referred to as the "fourth gas concentration") according to the third gas concentration;
calculating the additional correction amount based on the third gas concentration and the fourth gas concentration ;
The method for calculating the amount of heat according to claim 14 . the first gas is a paraffinic hydrocarbon gas,
the third gas is hydrogen gas;
The fourth gas is carbon dioxide gas or nitrogen gas.
The method for calculating the amount of heat according to any one of claims 12 to 15 . A program that causes a computer to execute the heat quantity calculation method according to any one of claims 4 to 6 and claims 12 to 16.