Calorie measuring device and calorie calculation method

Abstract

Provided are: a calorimetry device whereby it is possible to accurately perform calorimetry of a natural gas including mainly hydrogen gas as an interference gas, and to reduce the size and cost of the device; and a heat quantity calculation method.　This gas calorimetry device 10 for measuring the heat quantity of a subject gas comprises a thermal-conductivity-converted heat quantity measurement means 12 capable of measuring a heat quantity obtained from the thermal conductivity of the subject gas. The subject gas has a first gas as the main component thereof, and has incorporated therein a second gas that serves as a measurement error component. The thermal-conductivity-converted heat quantity measurement means 12 corrects the error component caused by the second gas on the basis of a relational expression indicating a correlation between the output of measurement by a thermal conductivity measurement means 13 and the actual heat quantity for a plurality of first gases, and calculates the heat quantity of the subject gas.

Description

[Technical Field]

[0001] The present invention relates to, for example, a device for measuring the calorific value of a gas and a method for calculating the calorific value, and more particularly to a device for measuring the calorific value of a paraffinic hydrocarbon gas containing an interfering gas that becomes an error component and a method for calculating the calorific value. [Background technology]

[0002] Conventionally, the natural gas commonly available 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.

[0003] Here, when measuring the calorific value of the natural gas, paraffinic hydrocarbon gas (e.g., methane gas (CH4), ethane gas (C2H6), propane gas (C3H8), butane gas (n-C4H 10 ) etc.), the calorimetry is possible because the calorific value and the refractive index, and the calorific value and the thermal conductivity are proportional to each other.

[0004] 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). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5308842 Summary of the Invention [Problem to be solved by the invention]

[0006] However, since there is no proportional relationship between the calorific value and the thermal conductivity of hydrogen gas (H2), errors cannot be eliminated by conventional calculation processing. Therefore, when calculating the calorific value when hydrogen gas is contained in paraffinic hydrocarbon gas, the presence of hydrogen gas (gas) is a major error factor.

[0007] 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 reducing the cost by miniaturizing or simplifying the configuration.

[0008] The present invention has been made in view 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 main interfering gas, while also being compact and inexpensive. [Means for solving the problem]

[0009] The present invention relates to a calorific value measuring device for measuring the calorific value of a target gas, the calorific value measuring device measuring the calorific value of the target gas, the calorific value measuring device comprising a thermal conductivity converted calorific value measuring means capable of measuring a 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 that becomes a measurement error component, the thermal conductivity converted calorific value measuring means correcting an error due to the second gas for 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 obtained in advance for a plurality of first gases that serve as references, to calculate the calorific value of the target gas. It is something , The thermal conductivity converted calorific value measuring means has a correction means and a converted calorific value calculating means, the correction means having a difference calculating means for calculating a difference between a first output and a second output measured by applying different voltages to the thermal conductivity measuring means for the target gas, and a corrected output value calculating means for calculating a corrected output value of the target gas based on the difference, and the converted calorific value calculating means calculates the calorific value of the target gas based on the corrected output value and the relational expression. The calorimetric device is characterized by the above. 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 error due to the second gas for the measured output of the target gas based on a relational equation showing the correlation between the output measured by a thermal conductivity measuring means, which is obtained in advance for a plurality of first gases that serve as references, and the actual calorific value.

[0010] The present invention also provides a calorific value calculation method for calculating the calorific value of a gas, wherein the target gas is composed mainly of a first gas and contains a second gas that is a measurement error component, and the calorific value of the target gas is calculated by correcting the error caused by the second gas with respect to the measured output of the target gas based on a relational equation showing the correlation between the actual calorific value and a measured thermal conductivity value of the first gas obtained in advance for a plurality of reference gases. The calorific value calculation method includes 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 the target gas contains a first gas as a main component and a second gas that becomes a measurement error component, the first gas is a paraffinic hydrocarbon gas, and the second gas is any one of hydrogen gas, nitrogen gas, and carbon dioxide gas;This is a calorific value calculation method, characterized in that the calorific value of the target gas is calculated by correcting an error due to the second gas in the measured output of the target gas based on a relational equation that shows the correlation between the measured thermal conductivity value of the first gas in a plurality of reference gases and the actual calorific value.

[0011] 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 the error due to the fourth gas. The calorimetric device is characterized by the above.

[0012] 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 a main component and a third gas and a fourth gas that become measurement error components, the method comprising the steps of: calculating a calorific value obtained from the thermal conductivity of the target gas (hereinafter referred to as a "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 values ​​and the actual calorific values ​​for a plurality of the first gases; acquiring a calorific value obtained from the refractive index of the target gas (hereinafter referred to as a "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.

[0013] The present invention also provides a program for causing a computer to execute the above-described method for calculating heat quantity. [Effects of the Invention]

[0014] According to the present invention, it is possible 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 main interfering gas, and that can be made smaller and less expensive. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a calorimetry device according to a first embodiment of the present invention. [Figure 2] 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. [Figure 3] 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. [Figure 4] 10A and 10B are schematic diagrams showing the configuration of a calorimetry device according to a second embodiment of the present invention, in which (A) is a schematic diagram showing the overall configuration, and (B) is a schematic diagram showing a refractive index converted calorie calculation means. [Figure 5] 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. [Figure 6] 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 output of a thermal conductivity meter. [Figure 7]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. [Figure 8] 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. [Figure 9] 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. [Figure 10] 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. [Figure 11] 10A and 10B are diagrams illustrating a method for measuring the calorie quantity of a calorie measuring device according to a third embodiment of the present invention, in which (A) is a graph showing an H2 proportion-voltage curve, and (B) is a graph showing an output-H2 proportion function. [Figure 12] 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. [Figure 13] FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. [Figure 14] FIG. 10 is a schematic diagram showing the configuration of a calorimetry device according to a third embodiment. [Figure 15] FIG. 10 is a schematic diagram showing the configuration of a calorimetry device according to a third embodiment. [Figure 16] 11 is a graph showing the relationship between the calculated heat quantity and the actual heat quantity in the third embodiment. [Figure 17] 11 is a graph showing the relationship between the calculated heat quantity and the actual heat quantity in the third embodiment. [Figure 18] 11 is a graph showing the relationship between the calculated heat quantity and the actual heat quantity in the third embodiment. [Figure 19] 11 is a graph showing the relationship between the calculated heat quantity and the actual heat quantity in the third embodiment. [Figure 20]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. [Figure 21] 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. [Figure 22] 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. [Figure 23] FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. [Figure 24] FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. [Figure 25] FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. [Figure 26] FIG. 10 is a diagram showing an example of a mixture ratio of an interference gas in a reference gas. [Figure 27] 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. [Figure 28] 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. [Figure 29] 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. [Figure 30] 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. [Figure 31] 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. [Figure 32] 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. DETAILED DESCRIPTION OF THE INVENTION

[0016] 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.

[0017] 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 Fig. 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, in an explosion-proof container 50.

[0018] 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 specifically, a gas containing a first gas as the main component and a second gas that becomes a measurement error component. 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-C4H), 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). 10 ) and the second gas is any one of hydrogen gas (H2), nitrogen gas (N2), and carbon dioxide gas (CO2), whose calorific value, thermal conductivity, and refractive index do not have a specific correspondence relationship.

[0019] 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 expression showing the correlation between the output measured by the thermal conductivity measuring means, which is acquired in advance for a plurality of first gases that serve as references, 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 calculating means 15.

[0020] 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.

[0021] The correction means 14 has a difference calculation means 141 and a correction output value calculation means 142, and has a function of correcting an error due to the presence of the second gas when calculating the calorific value of the target gas.

[0022] The converted calorific value calculation means 15 has a function of acquiring (calculating) the calorific value 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 calorific value. In the case of a target gas consisting only of a first gas (paraffinic hydrocarbon gas), the output measured by the thermal conductivity measurement means 13 and the actual calorific value have a predetermined correlation, but if the first gas contains a second gas (interference gas), an error caused by the second gas results in a value that deviates from the correlation. Therefore, the correction means 14 corrects the output measured by the thermal conductivity measurement means 13, and the converted calorific value calculation means 15 calculates the calorific value of the target gas based on the corrected value.

[0023] Although not shown in the figure, the calorific value measuring device 10 has a known configuration including a data transmission path, a calculation means, a control means, a memory means, etc., and these and the respective means (functions) of the thermal conductivity conversion calorific value measuring means 12 work together to measure and perform calculation processing on the target gas.

[0024] The calorific value thus calculated can be output to the outside via output means 18. Output means 18 is, for example, display means, printing means, or transmission means capable of outputting (transmitting) predetermined data via communication with the outside. Calorific value measuring device 10 may also be provided with a separate communication means capable of transmitting and receiving predetermined data to and from an external device.

[0025] Correction of errors due to the inclusion of a second gas will be described with reference to Figure 2. 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), where (A) is the graph before correction of errors due to the inclusion of a second gas, and (B) is the graph after correction. The vertical axis represents the calorific value [MJ / Nm 2 ] of each type of reference gas obtained by analysis using, for example, a gas chromatograph. 3 ] (hereinafter also referred to as "true calorific value"), and the horizontal axis represents the output results of measuring various reference gases using the thermal conductivity measuring means 13. Here, the case where the second gas is hydrogen gas is shown as an example.

[0026] The "reference gases" are all mixed gases in which another component is added to methane gas 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 gas, propane gas, and butane gas, and hydrogen gas, respectively. The concentration of methane gas is 100 vol% to 80 vol%, and the concentrations of the other components are 0 vol% to 20 vol%. 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 the true calorific value are in a nearly linear relationship. That is, the thermal conductivity meter output on the horizontal axis in the figure is the output X of the thermal conductivity measuring means 13 standardized (normalized) in this way. T.C. In this embodiment, this is referred to as "normalized output X T.C. ", or simply "Output X T.C. In the figure, the normalized output X T.C As the value moves away from the "0" point (increases or decreases), the concentration of methane gas decreases in increments of 2.5 vol%, and the concentration of the added component increases.

[0027] FIG. 1A shows the output (normalized output) X of the thermal conductivity measuring means 13 when the voltage applied to the thermal conductivity measuring means 13 is set to 0.5 V for these multiple types of reference gases. T.Cand the output (normalized output) X of the thermal conductivity measuring means 13 when the applied voltage to the thermal conductivity measuring means 13 is 1.0 V. T.C and the true calorific values ​​of each are plotted.

[0028] Specifically, the plots marked with triangles show the results for a mixture of methane and ethane gases (CH4-C2H6) when the applied voltage is 1.0 V. In this case, the output X T.C As the value increases from "0" (pure methane gas), mixed gases in which the concentration of methane gas 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.

[0029] The plot marked with a triangle is the result for a mixture of methane and ethane gases (CH4-C2H6) when the applied voltage is 0.5V, and the output X on the horizontal axis T.C As the value increases from "0" (pure methane gas), mixed gases in which the concentration of methane gas 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.

[0030] Similarly, the plots marked with squares are the results for a mixed gas of methane and propane gas (CH4-C3H8) when an applied voltage of 1.0 V is used, the plots marked with black squares are the results for a mixed gas of methane and propane gas (CH4-C3H8) when an applied voltage of 0.5 V is used, and the plots marked with white squares are the results for a mixed gas of methane and butane gas (CH4-C4H 10 ), and the plots marked with a ◆ are for a mixture of methane and butane gases (CH4-C4H 10 ) is the result.

[0031] The plots marked with circles show the results for a mixture of methane and hydrogen gas (CH4-H2) when the applied voltage is 1.0 V, and the plots marked with circles show the results for a mixture of methane and hydrogen gas (CH4-H2) when the applied voltage is 0.5 V. When hydrogen gas (interference gas) is added, the output X on the horizontal axis T.C As the methane gas concentration decreases from "0" (pure methane gas), mixed gases 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.) are shown.

[0032] As shown in FIG. 1A, in the case of a reference gas consisting of only paraffinic hydrocarbon gas, the output X of the thermal conductivity measuring means 13 increases as the amount of components added to the methane gas increases, regardless of the difference in the gas components. T.C On the other hand, in the case of a reference gas ((CH4-H2) gas) in which interference gas (hydrogen gas) is added to methane gas, the output X of the thermal conductivity measuring means 13 increases as the hydrogen gas component increases. T.C It was found that the true calorific value decreased.

[0033] Furthermore, in the case of a reference gas consisting only of paraffinic hydrocarbon gas, the output X due to the difference in the applied voltage to the thermal conductivity measuring means 13 is generally the same regardless of the difference in the gas components. T.C On the other hand, in the case of a reference gas containing hydrogen gas ((CH4-H2) gas), the output X T.C It was found that a difference occurred (an output difference occurred) and that the output difference was linear with respect to the concentration of hydrogen gas.

[0034] Based on these findings, the applicant of the present application considered that, for a target gas in which hydrogen gas is mixed with methane gas, even if the concentration of the contained hydrogen gas is unknown, it would be possible to calculate the calorific value of the target gas by correcting the error due to hydrogen gas, and thus achieved the present invention.

[0035] The calorimetry device 10 (for example, the thermal conductivity converted calorimetry measuring means 12) measures the output X T.C A relational expression showing the correlation between the actual calorific value and the calorific value (a linear relational expression shown by a solid line in FIG. 2) is acquired in advance and stored 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 formula."

number

[0036] As shown by the circles and circles in FIG. 2, in the case of a reference gas containing hydrogen gas, the plot deviates from the straight line of the calorific value calculation formula, so the correction means 14 adjusts the output X of the thermal conductivity measuring means 13 so that the plot fits onto the straight line of the calorific value calculation formula. T.C In detail, the correction means 14 corrects the output X measured by applying different voltages to the thermal conductivity measuring means 13 for a certain target gas. T.C and 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).

[0037] The difference calculation means 141 calculates the difference (hereinafter referred to as the "output difference") between a first output obtained by applying a first voltage (e.g., 1.0 V) to the thermal conductivity measurement means 13 and a second output obtained by applying a second voltage (e.g., 0.5 V).

[0038] The corrected output value calculation means 142 calculates the output X of the thermal conductivity measurement means 13 when the first voltage is applied using a correction formula based on the output difference. T.C (measurement result of the first output). The correction formula is set according to the type of the second gas and is stored in a storage means of the calorimetry device 10 (for example, the thermal conductivity conversion calorimetry measurement means 12). For example, the correction formula for finding the corrected output value (hereinafter referred to as "corrected output value (H2)") when the second gas is hydrogen gas is shown in Equation 2 below.

number

[0039] For reference gases containing hydrogen gas, the corrected output value (H2) is normalized to the output X T.C The result of plotting the above on the horizontal axis is shown in Figure 2(B). By this correction, the error when hydrogen gas is included is corrected, and the plot of the reference gas ((CH4-H2) gas) containing hydrogen gas is placed on the straight line of the calorific value calculation formula (Formula 1). In other words, in the actual measurement of the target gas, the converted calorific value calculation means 15 converts the corrected output value (H2) into the output X of the calorific value calculation formula based on the corrected output value (H2) and the calorific value calculation formula of Formula 1 (a linear relationship shown by a straight line in Figure 2(B)). T.C By substituting into the calorific value Q of the target gas A The calculated amount of heat can be output via the output means 18.

[0040] Next, the calorific value calculation method of this embodiment will be described. First, 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 at different ratios) among various reference gases is measured by the thermal conductivity measuring means 13 (output X T.C ) and the actual calorific value, a relational expression (calorific value calculation expression (Equation 1)) is obtained. Specifically, the first gas may be, for example, a plurality of (CH4-C2H6) gases with different concentrations of methane gas and ethane gas, a plurality of (CH4-C3H8) gases with different concentrations of methane gas and propane gas, a plurality of (CH4-C4H 10 ) gas.

[0041] 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 %).

[0042] 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 result measured by the thermal conductivity measuring means 13 are obtained. Then, 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 the true calorific value have an approximately linear relationship, and a calorific value calculation formula (Formula 1) showing the correlation between the two is obtained (see the solid line in FIG. 2(A)).

[0043] Next, during the measurement operation, for example, 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. As a result, the thermal conductivity converted calorific value measuring means 12 calculates the calorific value of the target gas based on the calorific value calculation formula (the above formula 1) by correcting the error due to the second gas (hydrogen gas). This calorific value is the calorific value obtained from the thermal conductivity, and can also be called the thermal conductivity converted calorific value.

[0044] 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.

[0045] Next, the difference (output difference) between the first output and the second output is calculated. Then, using a correction formula set for each type of second gas (in the case of hydrogen gas, the correction formula 2 above), the corrected output value (H2) of the target gas (normalized output X of the thermal conductivity measuring means 13 after correcting the error due to hydrogen gas) is calculated. T.C ) is calculated. Then, the corrected output value (H2) is converted into the normalized output X T.C Substituting into, the calorific value of the target gas Q A is calculated (see Figure 2(B)).

[0046] Although the above example shows the case where the second gas (interfering gas) is hydrogen gas, the second gas can be nitrogen gas or carbon dioxide gas in the same manner.

[0047] FIG. 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 results of the thermal conductivity measuring means 13 corresponding to FIG. 2 and the true calorific value. (A) of FIG. 3 is the graph before correction of errors due to the inclusion of a second gas in various reference gases, and (B) of FIG. 3 is the graph after correction. The graph is the same as in FIG. 2 except that hydrogen gas is replaced with nitrogen gas. The plots marked with a ▽ symbol in the graph represent the results for the reference gas ((CH4-N2) gas) in which nitrogen gas is added to methane gas when the applied voltage is 1.0 V, and the plots marked with a ▼ symbol represent the results for the reference gas ((CH4-N2) gas) when the applied voltage is 0.5 V.

[0048] In this case, the process is similar to that of hydrogen gas, so a detailed description will be omitted. However, based on FIG. 3(A), the measured value (output X) of the thermal conductivity measuring means 13 for a reference gas consisting of only a plurality of paraffinic hydrocarbon gases (a mixed gas in which other paraffinic hydrocarbon gases are added to methane gas at different ratios) is T.C ) and the actual calorific value (true calorific value), a relational expression (calorific value calculation formula (formula 1)) is obtained.

[0049] Then, for the (CH4-N2) gas, the output X of the thermal conductivity measuring means 13 is calculated by a correction formula based on the correlation between the output difference due to the difference in applied voltage to the thermal conductivity measuring means 13 and the true value of the calorific value. T.C For example, the correction formula for finding the corrected output value when the second gas is nitrogen gas (hereinafter referred to as "corrected output value (N2)") is shown in the following formula 3.

number

[0050] By plotting this corrected output value (N2) on the horizontal axis, the error when nitrogen gas is included is corrected, and the plot of the reference gas ((CH4-N2) gas) containing nitrogen gas is placed on the straight line of the calorific value calculation formula (Formula 1). In other words, in the case of a target gas containing actual nitrogen gas, the corrected output value (N2) is T.C.By substituting into the calorific value Q of the target gas A can be calculated.

[0051] 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 for hydrogen gas and nitrogen gas described above is shown in Equation 4 below.

number

[0052] That is, the calorimetry device 10 of this embodiment stores at least one of the correction formulas shown in Equations 2 to 4 above in its storage means.

[0053] As described above, the calorific value measuring device 10 of this embodiment can measure the calorific value with high accuracy using a simple configuration for a target gas whose main component is paraffinic hydrocarbon gas and contains any one of hydrogen gas, nitrogen gas, and carbon dioxide gas as an interference gas. 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, the calorific value can be measured with high accuracy by eliminating errors due to the presence of the interference gas.

[0054] Furthermore, in particular, when hydrogen gas is included as an interference gas, calorimetry based on thermal conductivity has conventionally been almost impossible, but according to this embodiment, measurement based on thermal conductivity becomes possible.

[0055] Furthermore, even when nitrogen or carbon dioxide is contained, the calorific value can be calculated using only the measurement results of the thermal conductivity meter, which allows for the device to be made smaller and its configuration simplified, resulting in lower costs.

[0056] Furthermore, by adopting a configuration that satisfies all of the above formulas 2 to 4, it becomes possible to measure the calorific value of a target gas that contains hydrogen gas, nitrogen gas, and carbon dioxide gas as interference gases.

[0057] While the present embodiment has been described above as an example of measuring a target gas containing a first gas as a main component and a second gas, the calorific value measuring device 10 of the present embodiment can also measure gases containing only the first gas (paraffinic hydrocarbon gas). In addition to these, the calorific value measuring device 10 can also measure target gases such as coke oven gas (COG), coal gasification gas, and naphtha gasification gas (all of which contain hydrogen gas and nitrogen gas as the second gas).

[0058] Second Embodiment A second embodiment of the present invention will be described with reference to Figures 4 to 9. The target gases measured in the second embodiment are also natural gas, biogas, etc. However, while the first embodiment measures target gases containing one interference gas, the second embodiment can measure the calorific value of target gases containing two interference gases (one of which is hydrogen gas) while reducing the influence (error) of the interference gases. In other words, the target gas is a gas containing a first gas (paraffinic hydrocarbon gas) as the main component and a third gas (hydrogen gas) and a fourth gas (at least one of nitrogen gas and carbon dioxide gas) that contribute to the measurement error. Specifically, the calorific value can be measured for a mixture of methane, hydrogen, and nitrogen gases (CH4-H2-N2), a mixture of methane, hydrogen, and carbon dioxide gases (CH4-H2-CO2), or a mixture of methane, hydrogen, nitrogen, and carbon dioxide gases (CH4-H2-N2-CO2).

[0059] 4A and 4B are diagrams showing an overview of a calorimetry device 30 according to a second embodiment, in which (A) is a block diagram showing an overview of the overall configuration, and (B) is a schematic diagram showing a refractive index converted calorimetry measurement means 32. In the following description, the same components as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0060] As shown in FIG. 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 FIG. 1A, and 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 is connected to the thermal conductivity converted calorific value measuring means 31 and the refractive index converted calorific value measuring means 32 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, in an explosion-proof container 50.

[0061] The thermal conductivity converted calorific value measuring means 31 has, for example, a thermal conductivity measuring means 13, a correction means 14 for realizing the function of thermal conductivity converted calorific value measurement, and a converted calorific value calculating means (thermal conductivity converted calorific value calculating means) 15, and outputs X measured by the thermal conductivity measuring means 13 for a plurality of first gases. T.C Based on the relational expression showing the correlation between the actual heat quantity and the thermal conductivity, the error due to the third and fourth gases is corrected to obtain the heat quantity converted to thermal conductivity Q. A In other words, the calorific value measuring device 30 (thermal conductivity converted calorific value measuring means 31) stores in its storage 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 measuring means 31 is the same as that of the thermal conductivity converted calorific value measuring means 12 of the first embodiment.

[0062] 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 interference gases (third gas (hydrogen gas) and fourth gas) when calculating the thermal conductivity converted heat quantity of the target gas.

[0063] The thermal conductivity converted heat quantity calculation means 15 calculates the output X measured by the thermal conductivity measurement means 13. T.Cand the actual calorific value (calculation formula shown in the above formula 1). That is, the correction means 14 calculates the thermal conductivity converted calorific value Q of the target gas based on the value (corrected output value) corrected for errors due to the inclusion of interference gas in the target gas and the calorific value calculation formula (formula 1) obtained from the thermal conductivity. A Here, in the second embodiment, the heat quantity calculation formula obtained from the thermal conductivity (linear relational formula (Formula 1) shown by a straight line in FIG. 2(B)) is referred to as a first heat quantity calculation formula.

[0064] The refractive index converted calorific value measuring means 32 detects the difference in refractive index of light between the 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 calculates the refractive index converted calorific value Q of the target gas based on the amount of displacement of the interference fringes. B It is a device (refractive index calorimeter) that measures the above.

[0065] 1B shows a specific example of an apparatus constituting the refractive index converted calorimetry means 32. The refractive index converted calorimetry means 32 may include, for example, 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 adjusted and positioned 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 and is then superimposed on the plane-parallel mirror 325 to generate 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 .

[0066] Referring to FIG. 1(A), the heat quantity calculation means 33 calculates the heat quantity converted into thermal conductivity Q A and refractive index converted heat quantity Q B The calorific value of the target gas is calculated using a coefficient for correcting errors due to a fourth gas (at least one of nitrogen gas and carbon dioxide gas) and a formula for calculating the calorific value (hereinafter referred to as the "second calorific value calculation formula") described below.

[0067] Although not shown in the second embodiment, 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 and the respective means (functions) of the thermal conductivity conversion calorific value measuring means 12 work together to measure and perform calculation processing on the target gas.

[0068] The calculated calorific value can be output to the outside via output means 18. Output means 18 is, for example, display means, printing means, or transmission means capable of outputting (transmitting) predetermined data via communication with the outside. Calorific value measuring device 30 may also be provided with a separate communication means capable of transmitting and receiving predetermined data to and from an external device.

[0069] The correction of errors due to the inclusion of interference gases (third and fourth gases) will be described with reference to Fig. 5. The figure shows the output X of the thermal conductivity measuring means 13 for various reference gases. T.C and the true calorific value, where (A) is the graph before correction of the error due to the inclusion of one type of interference gas in the various reference gases, and (B) is the graph after correction of the error 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 for correcting the error due to hydrogen gas in the first embodiment). The vertical axis represents the true calorific value [MJ / Nm 3 ], and the horizontal axis is the output (normalized output) X measured by the thermal conductivity measuring means 13 for various reference gases. T.C is.

[0070] As already mentioned, the various reference gases are all mixed gases in which another component is added to methane gas in different proportions, and are gases with clear compositions (concentrations) and true calorific values. The other components added are paraffinic hydrocarbon gases such as ethane gas, propane gas, and butane gas, and interference gases such as hydrogen gas, nitrogen gas, and carbon dioxide gas. The methane gas concentration is 100 vol% to 80 vol%, and the concentrations of the other components are 0 vol% to 20 vol%.

[0071] Here, data for cases where the interfering gas is other than carbon dioxide gas are shown again in Figures 2 and 3 of the first embodiment. That is, Figure 2(A) shows the data for the case where the interfering gas is only hydrogen gas, and Figure 3(A) shows the data for the case where the interfering gas is only nitrogen gas, superimposed on each other, with additional data for the case where the interfering gas is only carbon dioxide gas. Furthermore, the data for hydrogen gas in Figure 2(B) is the same as Figure 2(B). The following data is the same as in the first embodiment except for the case where the interfering gas is only carbon dioxide gas, and redundant explanations will be omitted.

[0072] A specific example will be explained for a reference gas containing carbon dioxide gas. The plot marked with a star is the result for a mixture of methane gas and carbon dioxide gas (CH4-CO2) when the applied voltage is 1.0 V. In this case, the output X T.C As the value increases from "0" (pure methane gas), mixed gases in which the concentration of methane gas decreases in increments of 2.5 vol% are shown (97.5 vol% methane gas - 2.5 vol% carbon dioxide gas, 95 vol% methane gas - 5 vol% carbon dioxide gas, 92.5 vol% methane gas - 7.5 vol% carbon dioxide gas, etc.).

[0073] The plot marked with a star is the result for a mixture of methane gas and carbon dioxide (CH4-CO2) when the applied voltage is 0.5V, and the output X on the horizontal axis T.CAs the value increases from "0" (pure methane gas), mixed gases in which the concentration of methane gas decreases in increments of 2.5 vol% are shown (97.5 vol% methane gas - 2.5 vol% carbon dioxide gas, 95 vol% methane gas - 5 vol% carbon dioxide gas, 92.5 vol% methane gas - 7.5 vol% carbon dioxide gas, etc.).

[0074] The calorimetry 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, and is therefore able 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.

[0075] Specifically, the error of hydrogen gas is eliminated (normalized output X for hydrogen gas only) T.C To compensate for this, the normalized output X T.C If the output difference is less than 0, the normalized output X is calculated using the above equation 2. T.C On the other hand, the normalized output X T.C If the output difference is greater than 0, the normalized output is X T.C (The following formula 5 is used as the correction output value.)

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[0076] The corrected output values ​​for these various standard gases were plotted on the horizontal axis, as shown in Figure 1(B). The linear relationship shown by the straight line in Figure 1(B) is the calorific value calculation formula (first calorific value calculation formula shown in Equation 1) obtained from the thermal conductivity, which eliminates the error caused by including only hydrogen gas as an interfering gas.

[0077] FIG. 6(A) shows the results of measuring the various reference gases mentioned above using the refractive index converted calorific value measuring means 32, and the vertical axis represents the refractive index converted calorific value Q B where the horizontal axis is 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 heat quantity and the refractive index have a linear relationship (proportional relationship) as shown by a 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 does not follow a linear pattern.

[0078] 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 (having the difference calculation means 141 that corrects the error of hydrogen gas in the first embodiment). The horizontal axis (normalized output X T.C ) is an adjusted graph.

[0079] 1A and 1B, it is possible to determine the ratio of the error when a gas containing nitrogen gas is measured using the thermal conductivity converted calorimetry means 31 to the error when it is measured using the refractive index converted calorimetry means 32. It is also possible to determine the ratio of the error when a gas containing carbon dioxide gas is measured using the thermal conductivity converted calorimetry means 31 to the error when it is measured using the refractive index converted calorimetry means 32. Since 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).

[0080] 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.

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[0081] 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.

[0082] 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 impossible (difficult), the influence of that error can be reduced and the calorific value Q of the target gas can be measured (calculated).

[0083] 7 is a graph verifying the measurement results of a plurality of reference gases with known compositions obtained by the calorific value measuring device 30 of this embodiment (having the difference calculation means 141 of the first embodiment). The vertical axis of the graph represents the true calorific value [MJ / Nm 3 ], and the horizontal axis represents the measured value (measured calorific value) obtained by the calorific value measuring device 30. The solid line in the graph is the second calorific value calculation formula shown in Equation 6.

[0084] In the figure, (CH4-C2H6) gas is indicated by a triangle, (CH4-C3H8) gas by a square, and (CH4-C4H 10 ) gas is indicated by a ◇, (CH4-H2) gas by a ○, (CH4-N2) gas by a ▽, (CH4-CO2) gas by a ☆, (CH4-H2-N2) gas by a ▼, (CH4-H2-CO2) gas by a ★, and (CH4-H2-C2H6) gas by a ▲.

[0085] 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 of 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.

[0086] In this embodiment, since calorific value measurement can be performed while eliminating the error component due to hydrogen gas (assuming that hydrogen gas is not included), it is naturally possible to measure target gases that do not contain hydrogen gas. For example, as shown in Figure 7, it is possible to measure the calorific value of 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) (not shown).

[0087] As shown in the figure, for a target gas containing two types of paraffinic hydrocarbon gases and hydrogen gas as an interference gas (specifically, a mixed gas of methane gas, ethane, and hydrogen gas (CH4-H2-C2H6 gas)), the error due to hydrogen gas can be corrected to enable accurate calorimetry.

[0088] 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 a gas pipeline 11 is supplied to a thermal conductivity converted calorific value measuring means 31 via a gas flow path 19. In this way, the thermal conductivity converted calorific value measuring means 31 calculates the thermal conductivity converted calorific value Q of the target gas based on the first calorific value calculation formula by correcting an error due to a third gas (hydrogen gas). A Calculate.

[0089] 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.

[0090] 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 the error due to hydrogen gas) is calculated using the correction formula shown in the above formula 2. Then, the corrected output value is used as the normalized output value to calculate the output X of the first heat quantity calculation formula (formula 1). T.C and the converted heat quantity Q of the target gas A Calculate.

[0091] 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 Q of the target gas is measured. B Then, the obtained refractive index converted heat quantity Q B and the heat quantity converted to thermal conductivity Q A The calorific value Q of the target gas is calculated using the second calorific value calculation formula shown in Equation 6 above.

[0092] <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 these embodiments will be omitted, as the third embodiment further reduces the influence of errors due to interference gas in the configuration of the second embodiment.

[0093] As shown in Figure 7, when hydrogen gas and one other gas are included as interference gases, it is possible to reduce the effect of the error, but there is still a deviation from the linear line representing the second calorific value calculation formula. This is 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 normalized output X T.C This is thought to be because the output difference between the two is in a negative and positive relationship, canceling each other out.

[0094] Figure 8 shows the normalized output X of the reference gas containing hydrogen gas and nitrogen gas as interference gases. T.C The reference gas is methane gas ((CH4-H2-N2) gas (methane gas concentration is 80 vol%)) mixed with hydrogen gas and nitrogen gas as interference gases. The standard output X when the concentrations of hydrogen gas and nitrogen gas are changed and voltages of 1.0 V and 0.5 V are applied is shown. T.C The colored circles represent the normalized output X for gases with different concentrations of hydrogen gas and nitrogen gas (CH4-H2-N2). T.C The results are plotted in darker colors as the nitrogen gas content increases, starting from the lowest nitrogen gas content, with the hydrogen gas to nitrogen gas ratio (H2:N2) at 3:1, H2:N2 = 1:1, H2:N2 = 1:3, and H2:N2 = 1:9. The black circles represent the normalized output X 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. T.C The white circle indicates the normalized output X 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. T.C The vertical axis is the output difference [mA], and the horizontal axis is the hydrogen gas concentration [vol%].

[0095] When the interference gas is only hydrogen gas, 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 shown 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 interference gases, the normalized output XT.C of the reference gas will vary depending on their concentrations. T.CIt was also revealed that the error component differs depending on the nitrogen gas concentration.

[0096] FIG. 9 shows the relationship between the voltage applied to the thermal conductivity measuring means 13 and the normalized output X for the reference gas ((CH4-H2-N2) gas). T.C. , and the normalized output X is obtained by changing the applied voltage for each of a plurality of reference gases (six types in this case) in which the ratio of hydrogen gas to nitrogen gas as an interference gas is changed. T.C. The vertical axis is the normalized output X T.C. The horizontal axis represents the applied voltage. The concentration of the hydrogen and nitrogen gas mixture (total concentration of H2 and N2 gases) is 10 vol% for all reference gases. Figure (A) shows the results for a hydrogen to nitrogen gas ratio (H2:N2) of 1:9, Figure (B) shows the results for a H2:N2 ratio of 1:3, Figure (C) shows the results for a H2:N2 ratio of 1:1, Figure (D) shows the results for a H2:N2 ratio of 3:2, and Figure (E) shows the results for a H2:N2 ratio of 9:1. Figure (F) shows the results for a H2:N2 ratio of 10:0, i.e., the results for (CH4-H2) gas (hydrogen gas concentration: 10 vol%, methane gas concentration: 90 vol%).

[0097] From these, the voltage applied to the thermal conductivity measuring means 13 and the normalized output X of the (CH4-H2-N2) gas are calculated. T.C. The relationship between the applied voltage and the normalized output power X of (CH4-H2-N2) gas changes depending on the ratio of hydrogen gas to nitrogen gas. T.C. It was found that there is a correlation between the ratio of hydrogen gas and nitrogen gas and the relationship between the ratio of hydrogen gas and nitrogen gas. Specifically, the normalized power X of (CH4-H2-N2) gas T.C. can be expressed as the following equation 7, which is the relation between the concentrations of hydrogen gas and nitrogen gas.

number

[0098] 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 (CH4-H2-N2) 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, by performing 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).

[0099] While Figures 8 and 9 show the relationship for a target gas ((CH4-H2-N2) gas) containing a mixture of hydrogen and nitrogen gases as interference gases, the relationship was found to be similar for a target gas ((CH4-H2-CO2) gas) containing a mixture of hydrogen and carbon dioxide gases as interference gases, and for a target gas ((CH4-H2-N2-CO2) gas) containing a mixture of hydrogen, nitrogen, and carbon dioxide gases as interference gases. That is, if the concentrations of hydrogen, nitrogen, and / or carbon dioxide gases in the interference gases are known, corrections can be made to eliminate the effects of nitrogen and / or carbon dioxide gas and to match or approximate the hydrogen gas concentration-output difference relationship. Furthermore, this correction allows the thermal conductivity converted calorific value measurement means 12 to calculate the calorific value using the correction formula shown in Equation 2 (the correction formula for when only hydrogen gas is included as an interference gas).

[0100] Based on these findings, the applicant of the present application has studied 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 found 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. There are, for example, the following first and second methods for calculating the hydrogen gas concentration. Note that in the calculation of each gas concentration described below, if either nitrogen gas or carbon dioxide gas is not included, the items of their concentrations (nitrogen gas concentration X N2 , and / or carbon dioxide gas concentration XCO2 ) can be calculated as "0".

[0101] <First method for calculating hydrogen gas concentration> The first method for calculating hydrogen gas concentration is to calculate it from the probability that hydrogen gas is at a certain concentration. First, for a mixed gas containing at least hydrogen gas (specifically, methane gas as a reference gas, (CH4-H2-N2) gas, (CH4-H2-CO2) gas, and (CH4-H2-N2-CO2) gas), multiple gases are prepared with hydrogen gas concentrations (index concentrations) ai varying 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, calculation parameters w and b are obtained using Equation 8 below to calculate the probability that hydrogen gas is at each concentration ai. This results in Equation 9 below, which calculates the probability that hydrogen gas is at each concentration ai. Here, Equations 8 and 9 can be obtained, for example, by machine learning, but the method of deriving Equations 8 and 9 is not limited to machine learning.

number

[0102] When calculating the concentration of a certain hydrogen gas, the thermal conductivity and refractive index (input signal xi) 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 (index concentrations) ai is calculated using Equations 8 and 9. Then, by multiplying each concentration ai by its probability f(ai) and adding them up, the target hydrogen gas concentration X is calculated. H2 can be calculated.

[0103] <Second method of calculating hydrogen gas concentration / First hydrogen concentration calculation formula> The second method of calculating the hydrogen gas concentration is to calculate the voltage applied to the thermal conductivity meter (for example, the thermal conductivity measuring means 13) and the normalized output X T.C. The hydrogen concentration is calculated using the hydrogen concentration calculation formula based on the relationship.

[0104] FIG. 10 shows the relationship between the ratio of hydrogen gas in the (CH4-H2-N2) gas, the voltage applied to the thermal conductivity measuring means 13, and the normalized output X of the (CH4-H2-N2) gas. T.C. 9(A) to 9(F) are plotted on one graph and fitted to a quadratic curve, and the vertical axis is the normalized output X T.C. The horizontal axis is the applied voltage [V]. Hereinafter, the curves (or straight lines) of the six types of gas (CH4-H2-N2) shown in Figure (A) are referred to as "output-voltage functions." Figure (B) shows the slope of the output-voltage function shown in Figure (A) (the slope of the tangent in the case of a curve, hereafter simply referred to as "slope dX T.C. / dV) on the vertical axis and the applied voltage [V] on the horizontal axis. As shown in Figure (B), the slope dX T.C. It can be seen that / dV and the applied voltage have a proportional relationship according to 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."

[0105] As is clear from the figure, the extreme points (peaks, slopes dX) of the output-voltage function for each of the six gases (CH4-H2-N2) T.C. It was found that the point where / dV becomes 0 shifts to the higher voltage side of the applied voltage as the proportion of hydrogen gas increases.

[0106] Figure 11(A) shows the extreme points (slope dX) of each of the six gases (CH4-H2-N2) for the output-voltage function shown in Figure 10(A). T.C. This is a graph in which the percentage of hydrogen gas (H percentage) at the extreme point (the point where / dV becomes 0) is plotted on the vertical axis, and the applied voltage [V] at the extreme point is plotted on the horizontal axis. This curve will be referred to as the "H percentage-voltage curve" hereinafter.

[0107] In addition, Fig. 11(B) plots the slope of each line of the slope-voltage function for the six types of gases (CH4-H2-N2) shown in Fig. 10(B) on the vertical axis and the hydrogen gas ratio (when the concentration of the total of hydrogen gas and nitrogen gas (H2+N2) gas) is 10 vol%) on the horizontal axis, and calculates an approximate line (hereinafter referred to as "output-H2 ratio function"). The "slope of the 'straight line of the slope-voltage function'" shown in Fig. 10(B) is the slope dXT.C. / dV differential value (d 2 X T.C. / dV 2 ), i.e., the normalized output X T.C. is the second derivative of the applied voltage V, and will be referred to as the "normalized output X" below. T.C. In Fig. 11, the results for (CH4-H2-N2) gas are plotted with circles. In addition, 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 in the same manner as in the case of the six types of (CH4-H2-N2) gas described using Figs. 9 and 10, and the relationship with the proportion of hydrogen gas was determined. The former is plotted with triangles, and the latter is plotted with squares.

[0108] As shown in FIG. 11(B), the standard gases ((CH4-H2-N2) gas, (CH4-H2-CO2) gas, and (CH4-H2-N2-CO2) gas) all have a normalized output X T.C. There is a correlation between the second-order differential value and the hydrogen gas ratio, as shown by the approximate curve. In other words, based on these relationships for the reference gas, it was found that the hydrogen gas concentration can be calculated for target gases (methane gas) that contain 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, and (CH4-H2-N2-CO2) gas, whose interference gas concentration is unknown. For (CH4-H2) gas, the hydrogen gas concentration of the target gas can be calculated based on the data for the reference gas with an H2 ratio of "1" among the (CH4-H2-N2) gas data shown in Figures 9 to 11 (data indicated by circles in Figure 11).

[0109] The following will be described by taking as an example the case of an arbitrary target gas ((CH4-H2-N2) gas) whose hydrogen gas concentration and the total concentration of hydrogen gas and nitrogen gas are unknown. According to the H2 proportion-voltage curve shown in FIG. 11(A), for an arbitrary (CH4-H2-N2) gas, the normalized output X T.C.If we find the extreme point of the output-voltage function (slope dX T.C. Based on this, the percentage of hydrogen gas can be calculated when the concentration of the total of hydrogen gas and nitrogen gas (H2 + N2 gas) is 10 vol%.

[0110] Then, based on the output-H2 ratio function in FIG. 11(B), the normalized output X corresponding to the calculated hydrogen gas ratio (horizontal axis) is calculated. T.C. The second derivative value (when the concentration of (H2 + N2) gas is 10 vol%) can be calculated.

[0111] Therefore, the hydrogen gas concentration X in any (CH4-H2-N2) gas H2 can be calculated using the first hydrogen concentration calculation formula shown in the following formula 10A.

number

[0112] The resulting hydrogen gas concentration is proportional to the concentration of (H2+N2) gas in the reference gas ((CH4-H2-N2) gas), so if the (H2+N2) gas concentration in the reference gas increases by N times, the calculation result of Equation 10 (hydrogen gas concentration) is multiplied by N.

[0113] <Second method for calculating hydrogen gas concentration / Second hydrogen concentration calculation formula> Next, another example of the second method will be described. T.C. As a hydrogen concentration calculation formula using the second derivative of the above, a second hydrogen concentration calculation formula shown in the following formula 10B may be used.

number

[0114] Equation 10B is the normalized output X T.C.This is derived from the relationship between the second derivative of the normalized output and the H2 concentration. 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) gas) in which methane gas contains hydrogen gas and nitrogen gas as interference gases and the ratios (known values) of these gases are varied. The vertical axis is the hydrogen gas concentration [vol%], and the horizontal axis is the second derivative of the normalized output.

[0115] The concentration of the hydrogen and nitrogen gas mixture (the total concentration of H2 and N2 gases) varies for each of the eight gas ratios, as shown in Figure 13. Figure 13 shows the measured H2 gas concentration and the total H2 and N2 gas concentration for each of the eight gas ratios (compositions) of multiple gases (e.g., eight gases). The second-order derivative of the normalized output was calculated using these reference gases, and the relationship between the two is plotted in Figure 13 (A). The ratios of the eight gases (H2:N2) for hydrogen 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, and H2:N2 = 1:9. The plots show the lowest nitrogen gas content, with the color becoming lighter as the nitrogen gas content increases.

[0116] 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 interference gases hydrogen gas and nitrogen gas.

[0117] Figure 12(B) shows the results of measurements performed in the same manner as in Figure 12(A) for the following reference gases: a reference gas containing methane, hydrogen, and carbon dioxide ((CH4-H2-CO2) gas: plotted with squares), a reference gas containing hydrogen and ethane ((CH4-H2-C2H6) gas: plotted with triangles), and a reference gas containing hydrogen, nitrogen, and carbon dioxide ((CH4-H2-N2-CO2) gas: plotted with crosses). Specifically, the proportion of interference gases (composition: known values) for each reference gas was varied to multiple types (eight types for (CH4-H2-N2) gas, five types for (CH4-H2-CO2) gas, four types for (CH4-H2-C2H6) gas, and two types for (CH4-H2-N2-CO2) gas). The second-order differential value of the normalized output was plotted on the horizontal axis, and the hydrogen gas concentration [vol%] was plotted on the vertical axis. The concentrations of interference gases (mixed gases) in each reference gas differ depending on the ratio (composition) of the eight interference gases, and details are shown in Figure 13. Figure 12(B) also shows the results of Figure 12(A). Specifically, the reference gas ((CH4-H2) gas) containing only hydrogen gas as an interference gas in methane gas corresponds to the H2:N2 = 1:0 result in Figure 12(A), and is plotted with a black circle in Figure 12(B). The reference gas ((CH4-H2-N2) gas) containing hydrogen and nitrogen gases as interference gases is plotted with a circle in Figure 12(B).

[0118] The results in FIG. 12(B) reveal 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.

[0119] Here, specific examples of coefficients (α, β, γ) in equation 10B are α = -6.3284, β = 16.903, and γ = 0. That is, an example of equation 10B is as follows.

[0120] X H2 = -6.3284×f"(V) 2 +16.903×f"(V) (Equation 10B)

[0121] 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.

[0122] The hydrogen gas concentration X calculated by the first or second method is H2 Based on this, 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 using the following formula 11.

number

[0123] This correction is only performed when the post-correction output difference y is less than the pre-correction output difference (the original "output difference (H2)" in Equation 2). In other words, the post-correction output difference y in Equation 11 is used as the "output difference (H2)" in Equation 2 only when the post-correction output difference y in Equation 11 is smaller than the "output difference (H2)" in Equation 2.

[0124] As already mentioned, the hydrogen gas concentration calculation formulas (Formula 10A and Formula 10B) can be used to calculate the hydrogen gas concentration of a target gas that contains at least hydrogen gas as an interference gas and further 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.

[0125] The total concentration of nitrogen gas and carbon dioxide gas (X ) is calculated from the "output difference (H2)" in Equation 2 (hereinafter referred to as "output difference before correction (H2)") and the output difference y after correction in Equation 11 (hereinafter referred to as "output difference after correction (H2)") using the following Equation 12: N2 +X CO2 ) is calculated.

[0126] If nitrogen gas and / or carbon dioxide gas is not included, X N2 Concentration and / or X CO2The concentration is set to "0".

number

[0127] Furthermore, the total concentration of nitrogen gas and carbon dioxide gas (X N2 +X CO2 ) and the additional correction amount determined by the following equation 13 is added to the output value (H2) of equation 2.

number

[0128] 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 relational expression can be matched or approximated. In this way, the corrected output value (H2) of Equation 2 that reflects the corrections of Equations 11 to 13 is hereinafter referred to as the "additional corrected output value (H2)." Then, X in the first heat quantity calculation formula is calculated using the additional corrected output value (H2) as the value of the normalized output. T.C. By substituting into the thermal conductivity converted heat quantity Q A can be calculated.

[0129] 14 and 15 are block diagrams showing an outline of a calorie measuring device 35 as a specific example of the third embodiment. Fig. 14 is a schematic diagram showing the overall configuration of the calorie measuring device 35, and Fig. 15 is a schematic diagram mainly for explaining the correction processing by the correction means 14. Note that the same components as those in the second embodiment are designated by the same reference numerals, and their explanation will be omitted.

[0130] 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 calculating means 33, and an output means 18. The correcting means 14 in the third embodiment further includes a third gas concentration calculating means 146 and an additional corrected output value calculating means 147.

[0131] As shown in FIG. 15, the third gas concentration calculation means 146 acquires the concentration of the third gas in the target gas (hereinafter referred to as the "third gas concentration"). Specifically, the third gas concentration (here, hydrogen gas concentration X H2 Alternatively, the third gas concentration (here, hydrogen gas concentration X ) is calculated based on a second method using 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. H2 ) is calculated.

[0132] The additional corrected output value calculation means 147 additionally corrects the output value (H2) and the output difference (H2) of the correction formula (Formula 2) for calculating the corrected output value (H2) of the corrected output value calculation means 142. More specifically, the additional corrected output value calculation means 147 additionally corrects the third gas concentration (calculated hydrogen gas concentration X H2 ), equation 11 is used to calculate y (corrected output difference (H2)) to correct the output difference (H2) in equation 2. Furthermore, equation 12 is used to calculate 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. Then, equation 13 is used to calculate the additional correction amount based on the third gas concentration and the fourth gas concentration.

[0133] Then, the additional corrected output value calculation means 147 substitutes y (the corrected output difference (H2)) into the output difference (H2) in equation 2, and substitutes the additional correction amount into the output value (H2) in equation 2, thereby obtaining an additional corrected output value (H2) that is further corrected from the (initial) corrected output value (H2) in equation 2.

[0134] The correction means 14 corrects the measurement result (normalized output X) of the thermal conductivity measuring means 13 using this additional corrected output value (H2). T.C. Correct the actual measurement value.

[0135] The thermal conductivity converted heat quantity calculation means 15 calculates the corrected normalized output X T.C. Using the additional corrected output value (H2) as the standardized output value, X in the first heat calculation formula T.C.) and convert the heat quantity Q into thermal conductivity using Equation 1. A In addition, similarly to the second embodiment, the refractive index converted heat quantity Q B The heat quantity calculation means 33 calculates the heat quantity converted into thermal conductivity Q A and refractive index converted heat quantity Q B and a coefficient CF for correcting an error due to a fourth gas (at least one of nitrogen gas and carbon dioxide gas), and the calorific value Q of the target gas is calculated using the second calorific value calculation formula (Formula 6).

[0136] Specifically, the calorie calculation method according to the third embodiment is as follows: First, similarly to the second embodiment, the calorie calculation formula (first calorie calculation formula) shown in Equation 1 is obtained.

[0137] 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 corrects the error due to the third gas (hydrogen gas) based on the first calorific value calculation formula and calculates the thermal conductivity converted calorific value Q of the target gas. A Calculate.

[0138] 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).

[0139] Next, the correction means 14 calculates the difference (output difference) between the first output and the second output. Then, using the correction formula shown in Equation 2 above, the corrected output value (H2) of the target gas (normalized output X of the thermal conductivity measuring means 13 after correcting the error due to hydrogen gas) is calculated. T.C. ) is calculated.

[0140] Thereafter, the third gas concentration calculation means 146 calculates the third gas concentration (for example, hydrogen gas concentration X H2 ) is calculated. H2Based on this, a correction value y for correcting the output difference (H2) in Equation 2 is obtained (Equation 11). H2 Based on this, calculate the fourth gas concentration (e.g., nitrogen gas concentration and carbon dioxide gas concentration) in the target gas (Equation 12), and obtain an additional correction amount (Equation 13) based on each concentration. If necessary (only when y<the initial output difference (H2) in Equation 2), substitute the correction value y in Equation 11 into the output difference (H2) in Equation 2. Also, substitute the additional correction amount in Equation 13 into the output value (H2) in Equation 2, and use the obtained additional corrected output value (H2) as X in the first heat quantity calculation formula (Equation 1). T.C. The heat quantity converted to the thermal conductivity of the target gas, Q A Calculate.

[0141] 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 Q of the target gas is measured. B Get.

[0142] The refractive index converted heat quantity Q obtained is B and the heat quantity converted to thermal conductivity Q A The calorific value Q of the target gas is calculated using the second calorific value calculation formula shown in Equation 6 above. [Example]

[0143] 16 to 18 are graphs showing the results of calculating the hydrogen gas concentration H2 and the calorific value Q using the first method (for example, a method using machine learning) in the third embodiment.

[0144] FIG. 16 shows the results of the first method (e.g., a method using machine learning) of the third embodiment for a reference gas containing an interference gas ((H2+N2) gas) with a clear component concentration. H2 10 is a graph comparing the results of calculating the calorific value Q (calculated calorific value) with the calorific value actually measured (actual calorific value). As verification data, six kinds of mixed gases (CH4-H2-N2 gases) containing methane gas, hydrogen gas, and nitrogen gas at different ratios were prepared, and the calorific value Q (calculated calorific value) [MJ / m 3 ] on the vertical axis, and the actual measured heat quantity (actual heat quantity) [MJ / m3 The results are plotted on a coordinate system with the horizontal axis being [√]. The circles represent the calculated calorific value. The dashed line indicates the ±1% error range for cases where the calculated calorific value and the actual calorific value match (solid line). Additionally, the results of calculating the calorific value Q based on the corrected output value (H2) from Equation 2 (which corrects for errors caused by the inclusion of only hydrogen gas) before correcting for errors caused by the inclusion of nitrogen gas using the additional corrected output value (H2) are plotted as "output difference" with crosses.

[0145] 10(A) shows the results when the ratio of hydrogen gas to nitrogen gas (H2:N2) is 1:9, FIG. 10(B) shows the results when H2:N2 is 1:3, FIG. 10(C) shows the results when H2:N2 is 1:1, FIG. 10(D) shows the results when H2:N2 is 3:2, FIG. 10(E) shows the results when H2:N2 is 9:1, and FIG. 10(F) shows the results when H2:N2 is 10:0. As is clear from the figures, according to this embodiment, the calorific value Q of (CH4-H2-N2) gas can be calculated with high accuracy, with an error of ±1% or less from the actual measured value.

[0146] 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 calorific value (actual calorific value) actually measured for a reference gas containing an interference gas ((H2+CO2) gas) with a clear component concentration. As verification data, five kinds of mixed gases (CH4-H2-CO2 gas) containing methane gas, hydrogen gas, and carbon dioxide gas at different ratios were prepared, and the calorific value Q (calculated calorific value) [MJ / m 2] calculated by the calorific value calculation means 33 of the third embodiment was compared. 3 ] on the vertical axis, and the actual measured heat quantity (actual heat quantity) [MJ / m 3 The results are plotted on a coordinate system with the horizontal axis being []. Circles indicate the calculated calorific value. The dashed line indicates the ±1% error range. Additionally, the results of calculating the calorific value Q based on the corrected output value (H2) from Equation 2 (which corrects for errors caused by the inclusion of only hydrogen gas) before correcting for errors caused by the inclusion of CO2 gas using the additional corrected output value (H2) are plotted as "output difference" with crosses.

[0147] Figure 1A shows the results for a hydrogen gas to CO2 gas ratio (H2:CO2) of 2:3, Figure 1B shows the results for a H2:CO2 ratio of 1:1, Figure 1C shows the results for a H2:CO2 ratio of 3:2, and Figure 1D shows the results for a H2:CO2 ratio of 9:1. Note that Figure 1A plots data for CO2 gas concentrations of 4 vol% or less, which is within the practical range. Although the data for the H2:CO2 ratio of 1:3 is not shown, there was almost no difference between the "output difference" and the calculated results. As is clear from Figure 1A, this embodiment can also calculate the calorific value Q for (CH4-H2-CO2) gas with reduced error from the actual measured value.

[0148] 18 is a graph comparing the calculation result (calculated calorific value) of the calorific value Q by the first method of the third embodiment with the calorific value (actual calorific value) actually measured for a reference gas containing an interference gas ((H2+N2+CO2) gas) with a clear component concentration. As verification data, two kinds of mixed gases (CH4-H2-N2-CO2 gas) containing methane gas, hydrogen gas, nitrogen gas, and carbon dioxide gas in different ratios were prepared, and the calorific value Q (calculated calorific value) [MJ / m 3 ] on the vertical axis, and the actual measured heat quantity (actual heat quantity) [MJ / m 3 The figure is plotted on a coordinate system with the horizontal axis being []. Circles indicate the calculated calorific value. The dashed line indicates the ±1% error range. Additionally, the calorific value Q calculated based on the corrected output value (H2) according to Equation 2 (which corrects for errors caused by the inclusion of only hydrogen gas) before the error caused by the inclusion of CO2 gas is corrected using the additional corrected output value (H2) is plotted as the "output difference" with crosses. In this figure, data for CO2 gas concentrations below 4 vol%, which is the practical range, is also plotted.

[0149] 10A shows the results when the ratio of hydrogen gas, nitrogen gas, and CO2 gas (H2:N2:CO2) is 6:1:1, and 10B 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.

[0150] 19 is a graph comparing the calculation result (calculated calorific value) of the calorific value Q according to the third embodiment with the calorific value (actual calorific value) actually measured for a reference gas containing an interference gas (H2 gas) with a clear component concentration. As verification data, a three-type mixed gas (CH4-C2H6-H2 gas) containing methane gas, ethane gas, and hydrogen gas at different ratios was prepared, and the calorific value Q (calculated calorific value) [MJ / m 2 ] calculated by the calorific value calculation means 33 of the third embodiment was used. 3 ] on the vertical axis, and the actual measured heat quantity (actual heat quantity) [MJ / m 3 The results are plotted on a coordinate system with the horizontal axis being [√]. The circles represent the calculated calorific value. The dashed lines indicate the ±1% error range. Additionally, the results of calculating the calorific value Q based on the corrected output value (H2) from Equation 2 (which corrects for errors caused by the inclusion of only hydrogen gas) before correcting for errors caused by the inclusion of nitrogen gas using the additional corrected output value (H2) are plotted as "output difference" with crosses.

[0151] Figure (A) shows the results when the ratio of hydrogen gas to ethane gas (H2:C2H6) is 3:1, Figure (B) shows the results when H2:C2H6 is 2:3, and Figure (C) shows the results when H2:C2H6 is 1:3.

[0152] In the above 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 (CH4-C2H6) gas and hydrogen gas is included as an interference gas. Since only hydrogen gas is used as an interference gas, the calorific value Q calculated by the calorific value calculation formula (Formula 1) in the first embodiment (Formula 2) corrected for hydrogen gas only) is AAccording to the figure, it is clear that the calculation method of the calorific value Q according to the third embodiment can obtain the same accuracy as that of the first embodiment, even for a mixed gas in which the first gas is (CH4-C2H6) gas and hydrogen gas is included as an interference gas.

[0153] The present invention may also be a program capable of executing the heat quantity calculation method of the present embodiment described above.

[0154] According to this embodiment, the calorific value Q can be calculated by measuring the thermal conductivity and refractive index of a target gas that is a paraffinic hydrocarbon gas and contains an interference gas that causes an error in the calorific value calculation. That is, the calorific value can be calculated using a known configuration (for example, a thermal conductivity meter and a refractometer) that can measure the thermal conductivity and refractive index as a measurement means, so that the calorific value can be measured (calculated) with a low-cost and simple configuration.

[0155] Furthermore, even if the interfering 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 interfering gas is unknown, the error factors caused by the interfering gas can be eliminated or reduced, and the calorific value Q can be calculated with high accuracy.

[0156] <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.

[0157] The hydrogen gas concentration calculation device 70 of this embodiment is 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. The target gas is a gas containing, in addition to hydrogen gas, for example, a paraffinic hydrocarbon gas, preferably methane gas, at 80 vol% or more, and may contain nitrogen gas and / or carbon dioxide gas in addition to hydrogen gas and methane gas.

[0158] The thermal output is, for example, thermal conductivity. Specifically, the hydrogen gas concentration calculation device 70 includes a thermal conductivity measurement means 13, a gas concentration calculation means 146, an output means 18, etc., and the gas concentration calculation means 146 has the same configuration as the third gas concentration calculation means 146 of the third embodiment based on the thermal conductivity of the target gas. More specifically, the third gas concentration calculation means 146 calculates the hydrogen gas concentration X using, for example, the second method. H2 The hydrogen gas concentration calculation means calculates 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.

[0159] The method for calculating the hydrogen gas concentration using the hydrogen gas concentration calculation device 70 is as follows: For example, a target gas (gas containing hydrogen gas whose composition is unknown) flowing through the gas pipeline 11 is supplied to the hydrogen gas concentration calculation device 70 via the gas flow path 19.

[0160] 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 X T.C. Get.

[0161] Then, the hydrogen gas concentration in the target gas is calculated based on the slope-voltage function shown in Figure 10(B), the H2 proportion-voltage curve shown in Figure 11(A), the output-H2 proportion function shown in Figure 11(B), and Equation 10 (Equation 10A or Equation 10B).

[0162] The third gas concentration (hydrogen gas concentration) calculation means 146 of the hydrogen gas concentration calculation device 70 in the fourth embodiment calculates the hydrogen gas concentration X by, for example, the first method (Equations 8 and 9). H2 The configuration may be such that the following is calculated:

[0163] In recent years, attempts have been made to introduce hydrogen gas into natural gas-derived city gas, etc. 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. are introduced into natural gas at any concentration, using a relatively simple configuration.

[0164] <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).

[0165] 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 containing at least hydrogen gas. The target gas is, for example, natural gas, and preferably a mixed gas containing hydrogen gas, nitrogen gas, and / or carbon dioxide gas in paraffinic hydrocarbon gas. Specifically, the hydrogen gas concentration calculation device 71 has at least a means capable of generating thermal output (for example, thermal conductivity measurement means 13), a difference calculation means 141, and a hydrogen gas concentration calculation means 149.

[0166] 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 (=I1-I2) between the standardized (normalized) output (current value) obtained by applying a first voltage V1 to the thermal conductivity measurement means 13 (standardized current value I1) and the standardized (normalized) second output (current value) obtained by applying a second voltage V2 (standardized current value I2). Note that the standardized current values ​​I1 and I2 are the standardized output X in the above embodiment. T.C. In the following explanation, these will be referred to as normalized current values ​​I, I1, and I2. 、 These are normalized output X T.C.、 X T.C1.、 X T.C2.The difference ΔI is the output difference (H2) 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 (H2).

[0167] The hydrogen gas concentration calculation means 149 has the following formula 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.

number

[0168] Here, a is a constant that is appropriately selected, for example, a=20 to 30, preferably a=25 to 27, and more preferably a=26.4.

[0169] This hydrogen gas concentration calculation device 71 is highly convenient in that the target gas measurement means is the thermal conductivity measurement means 13 only, and the hydrogen gas concentration calculation process is simple (not complicated).

[0170] 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 standard 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.

[0171] The reference gases in Figure 1A are the same mixed gases as those in Figure 8, namely, seven mixed gases ((CH4-H2-N2) gases) containing methane gas, hydrogen gas, and nitrogen gas in different ratios, a mixed gas ((CH4-H2) gas) containing methane gas and hydrogen gas, and a mixed gas ((CH4-N2) gas) containing methane gas and nitrogen gas. In Figure 1A, the ratios of nitrogen gas are indicated in descending order by circle (H2:N2=1:0), triangle (H2:N2=9:1), square (H2:N2=3:1), diamond (H2:N2=3:2), cross (H2:N2=1:1), black (H2:N2=2:3), triangle (H2:N2=1:3), square (H2:N2=1:9), and diamond (H2:N2=0:1). The circles represent the results for (CH4-H2) gas, and the diamonds represent the results for (CH4-N2) gas. The solid line indicates the ±1% error range for when the measured H2 concentration matches the actual hydrogen gas concentration H2.

[0172] The reference gas shown in FIG. 22 contains the same types of gases as the reference gas shown in FIG. 8, but the concentrations of each gas are different. FIG. 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 FIG. 22(A). In addition, the concentration of methane gas in each reference gas is a value excluding the combined concentration of hydrogen gas and nitrogen gas. In addition, 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 given assuming that 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.

[0173] Figure 22(B) shows the case of standard gases ((CH4-H2-CO2) gas, (CH4-H2) gas, (CH4-CO2) gas) in which the nitrogen gas in Figure 22(A) has been replaced with carbon dioxide gas, and the ratios are indicated by circles (H2:CO2=1:0), triangles (H2:CO2=9:1), squares (H2:CO2=3:2), crosses (H2:CO2=1:1), circles (H2:CO2=2:3), triangles (H2:CO2=1:3), and squares (H2:CO2=0:1) in order of decreasing carbon dioxide gas ratio. All other aspects are the same as Figure 22(A).

[0174] 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). In addition, in each reference gas, the concentration of methane gas is a value excluding the total concentration of hydrogen gas and carbon dioxide gas.

[0175] Figure 22(C) shows the case of reference gases ((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).

[0176] 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). In addition, the concentration of methane gas in each reference gas is a value excluding the total concentration of hydrogen gas and ethane gas.

[0177] 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.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 circles (H2:N2:CO2=2:1:1).

[0178] 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). In addition, 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.

[0179] 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.

[0180] In other words, while the hydrogen gas concentration calculation device 71 shown in Figure 21 can be easily realized with a simple configuration, it is prone to errors due to the inclusion of interference gases (especially nitrogen gas and / or carbon dioxide gas), and therefore can be said to be useful when errors due to interference gases are not strict or when the content ratio of nitrogen gas and / or carbon dioxide gas is low.

[0181] The hydrogen gas concentration calculation device 70 of the first configuration shown in FIG. 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, the second-order differential value (d 2 I / dV 2 By performing calculations using the first hydrogen gas concentration calculation formula (Formula 10A) or the second hydrogen gas concentration calculation formula (Formula 10B) using the normalized current I (hereinafter also referred to simply as the "second-order differential value of the normalized current value I"), it is possible to reduce the error between the calculated hydrogen gas concentration value (measured H2 concentration [vol%]) and the actual hydrogen gas concentration H2 [vol%] even when the target gas contains nitrogen gas and / or carbon dioxide gas.

[0182] Again, referring to FIG. 10(B), the slope dI / dV of the output-voltage function (FIG. 10(A)) and the applied voltage V are proportional to 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) is a constant value that depends on the hydrogen gas concentration xH2, especially when the hydrogen gas concentration xH2 is 10 vol% or less, and is expressed by the following equation 15.

number

[0183] This equation 15 shows the calculation using the first hydrogen concentration calculation equation (equation 10A) described above, which calculates the hydrogen gas concentration. In other words, "1 / f"(V)(10vol%)×10" in equation 10(a) is a constant, and equation 15 is obtained by replacing this with the constant a.

[0184] 27 is a graph showing the error between the calculation result (measured H2 concentration) according to the first hydrogen concentration calculation formula (Formula 10A) and the actual hydrogen gas concentration (H2 concentration). For each of a plurality of reference gases whose composition including hydrogen gas is clear, 16 different voltages V16 to V1 are applied to the thermal conductivity measuring means 13 of the hydrogen gas concentration calculation device 70 shown in FIG. 20. The normalized current values ​​I16 to I1 are approximated to a quadratic curve to obtain an "output-voltage function" (FIG. 10(A)). The differential value of the slope dI / dV (the second-order differential value of the normalized current value I) is used to calculate the hydrogen gas concentration X from Formula 10A. H2The 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, were the same as those described in the graph shown in Figure 22. Figure 27(A) shows the cases of (CH4-H2-N2) gas, (CH4-H2) gas, and (CH4-N2) gas, Figure 27(B) shows the cases of (CH4-H2-CO2) gas, (CH4-H2) gas, and (CH4-CO2) gas, Figure 27(C) shows the cases of (CH4-C2H6-H2) gas, (CH4-H2) gas, and (CH4-C2H6) gas, and Figure 27(D) shows the cases of (CH4-H2) gas and (CH4-H2-N2-CO2) gas.

[0185] As is clear from these results, the hydrogen gas concentration measuring device 70 (Equation 10A) shown in Figure 20 can keep the error between the measured (calculated) hydrogen gas concentration (measured H2 concentration) and the actual hydrogen gas concentration (H2 concentration) within approximately ±1 vol%.

[0186] Here, when the hydrogen gas concentration xH2 is up to 10 vol%, the second derivative 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 derivative 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.

[0187] 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 based on the thermal output of the target gas containing at least hydrogen gas, and calculates the hydrogen gas concentration based on the thermal output and multiple physical property values ​​of the target gas.

[0188] 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).

[0189] 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.

[0190] The thermal conductivity measuring means 13, the difference calculating means 141, and the refractive index converted heat quantity calculating means 32 have the same configuration as described in the above embodiment (FIG. 4, etc.), so a description thereof will be omitted.

[0191] The density converted calorific value calculation means 55 calculates the density converted calorific value Q C For example, by utilizing the fact that the resonance frequency when a vibrating tube made of a thin-walled cylindrical body is vibrated in a target gas changes based on the density of the target gas, the density converted calorific value Q of the target gas can be obtained based on the amount of change in the resonance frequency. C Since the calorific value and density of paraffin hydrocarbon gas are inversely proportional to each other, the density of the target gas can be obtained and converted into the calorific value.

[0192] The density converted calorific value calculation means 55 may be configured to have, 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 receiving source arranged at both ends of the tube. By emitting sound from the sound wave source toward the tube through which the target gas flows and measuring the time it takes for the sound to propagate through the by-product gas and reach the receiving source, the speed of sound propagating through the measurement gas can be accurately determined. Then, the density of the target gas (=specific heat ratio×pressure / sound speed) is calculated based on the sound speed measured by the sound speed measurement means. 2 ) and calculate the density converted heat quantity Q C It may also be something that requires.

[0193] The hydrogen gas concentration calculation means 150 calculates the output difference ΔI calculated by the difference calculation means 141 and the refractive index converted heat quantity Q calculated by the refractive index converted heat quantity calculation means 32. B , and the density converted calorific value Q calculated by the density converted calorific value calculation means 55 CThe hydrogen gas concentration xH2 in the target gas is calculated using the following equation 16. Equation 16 is hereinafter referred to as the "third hydrogen concentration calculation equation."

number

[0194] The constants a, b, and c are values ​​that can be selected appropriately. For example, a = -25 to -27, preferably a = -26 to -26.5, and more preferably a = -26.4. For example, b = 0.8 to 1.0, preferably b = 0.85 to 0.95, and more preferably b = 0.916. For example, c = 0.8 to 1.0, preferably c = 0.85 to 0.95, and more preferably c = 0.916.

[0195] Here, we will explain Equation 16. As shown in Equation 14, the hydrogen gas concentration X in the target gas H2 Basically, it can 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 occurs in the calculation result. Therefore, the nitrogen gas concentration X N2 and carbon dioxide gas concentration X CO2 If we know the concentration of nitrogen gas, we can make appropriate corrections according to these concentrations. In other words, as shown in Equation 16.1 (details will be explained later), we can add the nitrogen gas concentration X to the right side of Equation 14. N2 and carbon dioxide gas concentration X CO2 On the other hand, it is possible to add a correction term according to the composition of the target gas to be actually measured (nitrogen gas concentration X N2 and carbon dioxide gas concentration X CO2 ) is unknown.

[0196] By the way, the applicant of the present application has calculated the refractive index converted calorific value Q obtained from the refractive index of the target gas. B and the density converted calorific value Q obtained from the density of the target gas CBased on this, we have developed a unique method to calculate the calorific value Q of the target gas using the following equation 17, under the condition that 2.40≦correction coefficient α≦3.11 (this method is described in detail in Patent No. 5184983).

number

[0197] Furthermore, as a result of consideration by the applicant of the present application, when natural gas contains nitrogen gas and carbon dioxide gas, the nitrogen gas concentration X N2 and carbon dioxide gas concentration X CO2 The total value (actual value) is the carbon dioxide gas concentration X CO2 Only the actual value can be multiplied by 1.55 and the sum can be approximated, and the approximate nitrogen gas concentration X N2 and carbon dioxide gas concentration X CO2 The total value (total approximate concentration) and the refractive index converted heat quantity Q shown in Equation 17 B and density-converted heat quantity Q C It was found that there is a relationship shown in Equation 18 (the right side of Equation 18 is the total approximate concentration).

number

[0198] That is, in calculating the hydrogen gas concentration, the nitrogen gas concentration X N2 and carbon dioxide gas concentration X CO2 Even if the individual concentrations are unknown, the total approximate concentration (X N2 +1.55X CO2 ) is obtained, the error due to the influence of nitrogen gas and carbon dioxide gas is corrected using the above formula 16.1 to obtain the hydrogen gas concentration X H2 can be calculated.

[0199] Furthermore, the actual nitrogen gas concentration x N2 and carbon dioxide gas concentration X CO2 , or even if the total approximate concentration of these is unknown, the refractive index converted heat quantity Q can be used as a substitute for the concentrations of both. B and density-converted heat quantity Q CBy using the above formula 16 (third hydrogen concentration calculation formula), the error due to the influence of nitrogen gas and carbon dioxide gas is corrected, and the hydrogen gas concentration X H2 can be calculated.

[0200] Here, the third hydrogen concentration calculation formula also calculates the hydrogen gas concentration based on the relationship between the voltage applied 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 the hydrogen gas concentration described above.

[0201] The 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 (sonic velocity converted calorific value) of the target gas from the measurement results. This sonic velocity converted calorific value can be treated as equivalent to the density converted calorific value QC, and the same effect as above can be obtained.

[0202] FIG. 29 is a graph showing the error between the calculation result (measured H2 concentration) according to the third hydrogen concentration calculation formula (Formula 16) and the actual hydrogen gas concentration (H2 concentration). For each of a number of standard gases whose composition including hydrogen gas is clear, two different voltages V1 and V2 were applied to the thermal conductivity measuring means 13 of the hydrogen gas concentration calculation device 72 shown in FIG. 28, and the output difference ΔI between the obtained normalized current values ​​I1 and I2 was calculated. In addition, the refractive index of the standard gas was measured to calculate the refractive index converted heat quantity Q B The density of the reference gas is measured to obtain the density converted calorific value Q C and calculate the hydrogen gas concentration X based on the third hydrogen concentration calculation formula (Equation 16). H2The 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 gas, including its composition, was the same as that described in the graph shown in Figure 22. Figure 29(A) shows the cases of (CH4-H2-N2) gas, (CH4-H2) gas, and (CH4-N2) gas, Figure 29(B) shows the cases of (CH4-H2-CO2) gas, (CH4-H2) gas, and (CH4-CO2) gas, Figure 29(C) shows the cases of (CH4-C2H6-H2) gas, (CH4-H2) gas, and (CH4-C2H6) gas, and Figure 29(D) shows the cases of (CH4-H2) gas and (CH4-H2-N2-CO2) gas.

[0203] As is clear from these results, the error between the measured (calculated) hydrogen gas concentration (measured H2 concentration) and the actual hydrogen gas concentration (H2 concentration) can be kept to approximately ±1 vol% by using the hydrogen gas concentration measuring device 72 (Equation 16) shown in Figure 28. Furthermore, this error is smaller (less variable) than the error of the hydrogen gas concentration measuring device 70 (Equation 10A), and in particular when only nitrogen gas (and hydrogen gas) were present (Figure 29(A)), the results were nearly consistent with the actual measured value.

[0204] Next, a number of mixed gases close to the composition of realistic natural gas were prepared, and a reference gas was prepared by mixing these with hydrogen gas of known concentration. The hydrogen gas concentration X was measured using the hydrogen gas concentration measuring device 70 shown in FIG. 20 (method using the first hydrogen concentration calculation formula (Formula 10A)) and the hydrogen gas concentration measuring device 72 shown in FIG. 28 (method using the third hydrogen concentration calculation formula (Formula 16)). H2 Figure 30 is a table summarizing the composition and calorific value of the eight types of mixed gases (Gas No. 1 to No. 8) prepared. In addition, these eight types of mixed gases were mixed with 0, 5, 10, 15, 20, 25, and 30 vol% hydrogen gas, respectively, to create the reference gases to be measured.

[0205] FIG. 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 error 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 value 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 using an optical interferometer, and there is a slight deviation from the planned mixing values ​​(0, 5, 10, 15, 20, 25, 30 [vol%]).

[0206] 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 ◆.

[0207] As a result, it was revealed that the hydrogen gas concentration measuring device 70 shown in Figure 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.

[0208] 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).

[0209] As a result, it was revealed that the hydrogen gas concentration measuring device 70 shown in Figure 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 even more accurate measurements.

[0210] As described above, the hydrogen gas concentration measuring devices 70, 72 according to the present 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 the present 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).

[0211] As an example, the hydrogen gas concentration measuring device 70 includes a thermal conductivity measuring means 13 and a hydrogen gas concentration calculating means 146, and the hydrogen gas concentration calculating means 146 has a first hydrogen concentration calculation formula (Formula 10A) or a second hydrogen concentration calculation formula (Formula 10B).

[0212] 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 voltage of the normalized output (normalized current value I) of the thermal conductivity measurement means 13.

[0213] 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 normalized 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 normalized current value I with respect to the voltage.

[0214] 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).

[0215] As another example, the hydrogen gas concentration measuring device 72 has a thermal conductivity measuring means 13, a difference calculating means 141, a refractive index converted heat power measuring means 32, a density converted heat power measuring means 55, and a hydrogen gas concentration calculating means 150, and the hydrogen gas concentration calculating means 150 has a third hydrogen concentration calculation formula (Formula 16).

[0216] The hydrogen gas concentration measurement method also includes the steps of measuring the thermal output (thermal conductivity) of the target gas when two different voltages are applied, calculating the difference in normalized current values ​​corresponding to the two voltages (output difference ΔI), and calculating the refractive index converted heat quantity Q B and density-converted heat quantity Q C and calculating the hydrogen gas concentration of the target gas using a third hydrogen gas concentration calculation formula (Formula 16) based on the above.

[0217] Furthermore, this embodiment may be configured as a program that can cause a computer to execute each step of the hydrogen gas concentration measurement method described above.

[0218] The thermal output may be a thermal output other than the thermal conductivity. Also, the sonic velocity of the target gas may be used instead of the density of the target gas.

[0219] In recent years, hydrogen gas has been added to natural gas pipelines in some cases, and there is a demand for a simple configuration to check the amount of added hydrogen gas. Furthermore, there is also a demand for a device that can separate and detect only the hydrogen gas concentration in natural gas for the purpose of correcting calculations, for example, when determining the compression coefficient of natural gas.

[0220] According to the hydrogen gas concentration calculation device 70 shown in FIG. 20 (a hydrogen gas concentration calculation method using the first hydrogen gas concentration calculation formula (Formula 10A)), the thermal output (for example, thermal conductivity) of the target gas is measured to reduce errors due to nitrogen gas and carbon dioxide gas in the target gas (eliminate the effects of these as much as possible) and calculate the hydrogen gas concentration X H2The measurement means for the target gas can be configured with only a general thermal conductivity measurement means 13, so it is simple and inexpensive, yet can calculate the hydrogen gas concentration X with high accuracy. H2 It becomes possible to measure (calculate)

[0221] Furthermore, according to the hydrogen gas concentration calculation device 72 shown in FIG. 28 (a method for calculating hydrogen gas concentration using the third hydrogen gas concentration calculation formula (Formula 16)), by measuring the physical property values ​​of the target gas, specifically the refractive index and density (or sound velocity), in addition to the thermal output (for example, thermal conductivity) of the target gas, the hydrogen gas concentration X H2 The measurement means for the target gas requires a refractive index and density (or sound velocity) measurement means in addition to a general thermal conductivity measurement means 13, but these can be configured with a general optical interferometer or sound velocity sensor, and errors due to nitrogen gas and carbon dioxide gas can be reduced even further than with the hydrogen gas concentration measurement device 70 shown in FIG. 20. In addition, the composition of the target gas (particularly the nitrogen gas concentration X N2 and carbon dioxide gas concentration X CO2 ) is unknown (without measuring these concentrations), the hydrogen gas concentration in the target gas can be measured (calculated) with high accuracy by simply measuring the target gas itself.

[0222] In addition, 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 indicate the same value.

[0223] In addition, in the specification and drawings, X N2 , x N2 , xN2 indicate the nitrogen gas concentration, and X CO2 , x CO2 , xCO2 both indicate carbon dioxide concentration, and X H2 , x H2 , xH2 each represent the hydrogen gas concentration.

[0224] In the above embodiment, for example, natural gas and biogas are used as examples of target gases, but the present invention is not limited to these examples. The target gas may be coke oven gas (COG), coal gasification (solid coal converted into gaseous fuel gas), naphtha gasification (naphtha converted into gaseous fuel gas), or the like.

[0225] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the spirit and technical concept of the present invention. [Explanation of symbols]

[0226] 10 Calorimetry device 11 Gas Pipeline 12. Thermal conductivity conversion calorie measurement method 13 Thermal conductivity measurement means 14 Correction means 15 Means for calculating converted calorific value 18 Output Methods 30 Calorimetry device 31 Thermal conductivity conversion calorie measurement method 32 Refractive index calorimetry method 33 Calorie calculation means 35 Calorimetry device 70, 71, 72 Hydrogen gas concentration measuring device 146, 149, 150 Third gas concentration calculation means 147 Additional correction output value calculation means 50 Explosion-proof containers 141 Difference calculation means 142 Corrected output value calculation means A Heat quantity converted into thermal conductivity Q B Refractive index converted heat quantity Q Heat amount CF Correction Factor

Claims

1. 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 quantity 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:

2. A calorimetry 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; 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:

3. 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.

4. A method for calculating the 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.

5. 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.

6. The corrected output value is calculated using a correction formula that is set based on the difference for each type of the second gas.

5. The method for calculating the amount of heat according to claim 4.

7. A calorimetry 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; 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:

8. The thermal conductivity converted calorific value measuring means is 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.

9. 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:

10. The additional correction output value calculation means calculates the concentration of the fourth gas in the target gas (hereinafter referred to as the "fourth gas concentration") according to 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.

11. 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.

12. 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:

13. A step 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 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:

14. A step of obtaining the concentration of the third gas in the target gas (hereinafter referred to as the "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:

15. Calculating the 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.

16. The method of claim 1, wherein 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.

17. A program that causes a computer to execute the heat calculation method described in any one of claims 4 to 6 and claims 12 to 16.

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