JP2023028497A - Calorimeter - Google Patents

Abstract

To provide a technique capable of accurately measuring gas calories for various gases with different compositions in a simplified configuration.SOLUTION: A calorimeter comprises a processing unit for executing first measurement processing of measuring velocity of sound waves propagating in a gas to be measured, and second measurement processing of measuring a thermal conductivity rate of the gas. The processing unit calculates a calorie per unit volume of the gas based on the velocity of sound waves measured by the first measurement processing and the thermal conductivity rate measured by the second measurement processing.SELECTED DRAWING: Figure 1

Description

The technology disclosed in this specification relates to gas calorimeters.

US Pat. No. 6,201,401 discloses a method for determining the effective composition of a gas mixture containing multiple hydrocarbon gases. Also disclosed is the determination of the calorific value of natural gas from the determined effective composition of the gas.

Japanese Patent Publication No. 2004-514138

With the technique described in Patent Document 1, the calorific value cannot be determined without determining the effective composition of the gas mixture. However, the equipment and processes for determining the effective composition are complicated. Also, the effective composition may not be accurately determined. Therefore, the present specification provides a technique capable of accurately measuring the calorific value of various gases having different compositions with a simple configuration.

The calorimeter disclosed in the present specification is a processing unit that performs a first measurement process of measuring the velocity of a sound wave propagating in a gas to be measured, and a second measurement process of measuring the thermal conductivity of the gas. wherein the processing unit calculates the heat amount per unit volume of the gas based on the speed of the sound wave measured by the first measurement process and the thermal conductivity measured by the second measurement process do.

According to this configuration, even if various gases have different compositions, the velocity of the sound wave propagating in the gas and the thermal conductivity of the gas are measured accordingly, and based on these, the per unit volume of the gas Calories can be calculated. Therefore, the calorific value of various gases having different compositions can be accurately measured with a simple configuration.

The processing unit substitutes the speed of the sound wave measured by the first measurement process into a predetermined function according to the thermal conductivity measured by the second measurement process, thereby obtaining Calories may be calculated. According to this configuration, the calorie of the gas can be accurately measured simply by substituting the speed of the sound wave propagating in the gas into the predetermined function.

The calorimeter may include a storage unit that stores a plurality of functions corresponding to a plurality of thermal conductivities. The processing unit specifies the predetermined function from the plurality of functions stored in the storage unit according to the thermal conductivity measured by the second measurement process, and assigns the specified function to the first The amount of heat per unit volume of the gas may be calculated by substituting the velocity of the sound wave measured by the measurement process. According to this configuration, by specifying a function according to the thermal conductivity of the gas from a plurality of functions, it is possible to accurately measure the calorie of the gas.

The function may be set according to the thermal conductivity calculated based on the composition of the gas. According to this configuration, it is possible to accurately measure the calorie of various gases having different compositions.

The figure which shows typically the calorimeter of an Example. The figure explaining the structure which measures the speed of sound in gas. The figure explaining the structure which measures the thermal conductivity of gas. The figure which shows the area according to the thermal conductivity of gas. The figure which shows the function according to the area. The table which shows an example of the molar fraction of several components contained in gas. A table showing an example of the thermal conductivity of a single gas. A table showing an example of the speed of sound in a single gas. A table showing an example of the amount of heat per unit volume of a single gas. A graph in which the thermal conductivities of a plurality of gases with different compositions are arranged in ascending order. 11 is a graph showing the relationship between the sound velocity in the gas and the heat quantity of the gas for a plurality of gases in the interval D1 of the graph shown in FIG. 10; A table showing an example of the calorific value of a mixed gas measured by a calorimeter of a test example. A table showing an example of the calorific value of a mixed gas calculated by a comparative example. The figure which shows the 2nd unit of a modification typically.

A calorimeter 2 of an embodiment will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a calorimeter of an example. As shown in FIG. 1, the calorimeter 2 of the embodiment includes a first measurement unit 4 and a second measurement unit 6. As shown in FIG. The calorimeter 2 is attached to the gas pipe 300 and measures the calorie of the gas flowing through the gas pipe 300 . The gas pipe 300 is, for example, a part of a pipeline through which gas supplied from a gas supplier (for example, a gas company) to a gas supply destination (for example, general users) flows. Gas flows along the axial direction (longitudinal direction) of the gas pipe 300 .

The 1st measurement unit 4 is demonstrated. The first measurement unit 4 includes a first ultrasonic sensor 10 , a second ultrasonic sensor 12 , a temperature sensor 14 and a pressure sensor 16 . The first measurement unit 4 also includes a display section 20 , an operation section 22 , a processing section 24 , a storage section 26 and a power source 28 .

As shown in FIG. 2 , the first ultrasonic sensor 10 and the second ultrasonic sensor 12 are attached to a gas pipe 300 and arranged to face each other with the pipe axis of the gas pipe 300 therebetween. The first ultrasonic sensor 10 is arranged on the upstream side in the gas flow direction of the second ultrasonic sensor 12, and is generally arranged to face the downstream side in the gas flow direction. The first ultrasonic sensor 10 emits ultrasonic waves toward the second ultrasonic sensor 12 . The ultrasonic waves emitted from the first ultrasonic sensor 10 propagate through the gas flowing through the gas pipe 300 and are received by the second ultrasonic sensor 12 . In addition, below, the direction from the first ultrasonic sensor 10 to the second ultrasonic sensor 12 may be referred to as the "forward direction".

The second ultrasonic sensor 12 is arranged downstream of the first ultrasonic sensor 10 in the gas flow direction, and is generally arranged to face the upstream side in the gas flow direction. The second ultrasonic sensor 12 emits ultrasonic waves toward the first ultrasonic sensor 10 . The ultrasonic waves emitted from the second ultrasonic sensor 12 propagate through the gas flowing through the gas pipe 300 and are received by the first ultrasonic sensor 10 . In the following, the direction from the second ultrasonic sensor 12 to the first ultrasonic sensor 10 may be called "reverse direction".

Next, a method for calculating the velocity of ultrasonic waves (an example of sound waves) propagating in the gas flowing through the gas pipe 300 will be described. In addition, below, the speed of the ultrasonic wave which propagates in gas may be called "sound speed in gas." In the first measurement unit 4 described above, when the second ultrasonic sensor 12 receives the ultrasonic waves transmitted from the first ultrasonic sensor 10, the processing unit 24 detects the ultrasonic waves from the first ultrasonic sensor 10 to the second ultrasonic sensor 12. Calculate the propagation time T1 (s) of the ultrasonic wave that propagates through. The forward propagation time T1 is calculated, for example, based on the time when the first ultrasonic sensor 10 transmits the ultrasonic wave and the time when the second ultrasonic sensor 12 receives the ultrasonic wave.

Further, in the above-described first measurement unit 4, when the first ultrasonic sensor 10 receives an ultrasonic wave transmitted from the second ultrasonic sensor 12, the processing unit 24 receives the first ultrasonic wave from the second ultrasonic sensor 12. A propagation time T2 (s) of ultrasonic waves transmitted to the sensor 10 is calculated. The backward propagation time T2 is calculated, for example, based on the time when the second ultrasonic sensor 12 transmits the ultrasonic wave and the time when the first ultrasonic sensor 10 receives the ultrasonic wave.

Subsequently, the processing unit 24 calculates the velocity C (m/s) of the ultrasonic wave propagating in the gas inside the gas pipe 300 by, for example, the following arithmetic expression (1). In equation (1) below, L(m) is the distance between the first ultrasonic sensor 10 and the second ultrasonic sensor 12 . T(s) is the propagation time of ultrasonic waves between the first ultrasonic sensor 10 and the second ultrasonic sensor 12, T=(forward propagation time T1+reverse propagation time T2)/2 . A is a predetermined correction factor.

Note that the processing unit 24 may calculate the flow velocity of the gas flowing through the gas pipe 300 based on the above T1, T2, L, and the angle θ shown in FIG. The angle θ shown in FIG. 2 is the angle between the axial direction of the gas pipe 300 and the direction in which the first ultrasonic sensor 10 and the second ultrasonic sensor 12 face each other. The processing unit 24 may also calculate the flow rate of the gas based on the calculated flow velocity of the gas. The calorimeter 2 also functions as a gas velocity meter and a gas flow meter. Since the method of calculating the gas flow velocity and the gas flow rate is already known, detailed description thereof will be omitted.

The temperature sensor 14 and the pressure sensor 16 of the first measurement unit 4 (see FIG. 1) are attached to the gas pipe 300, and the first ultrasonic sensor 10 and the second ultrasonic sensor 10 and the second ultrasonic sensor 10 in the axial direction (longitudinal direction) of the gas pipe 300. It is arranged between the sound wave sensors 12 . Temperature sensor 14 detects the temperature of the gas in gas pipe 300 . The pressure sensor 16 detects the pressure of gas inside the gas pipe 300 .

The display unit 20 is, for example, a liquid crystal screen, and displays various information regarding the calorimeter 2 . The display unit 20 displays, for example, the calorie of the gas measured by the calorimeter 2 . The operation unit 22 is, for example, a button, and receives various operations regarding the calorimeter 2 . The power source 28 is, for example, a commercially available dry battery. Alternatively, the power supply 28 may be an AC mains power supply.

The processing unit 24 has, for example, a CPU, and executes predetermined processing based on a program. For example, the processing unit 24 calculates the calorie of the gas flowing through the gas pipe 300 based on a predetermined function. The storage unit 26 includes, for example, ROM and RAM, and stores various information regarding the calorimeter 2 .

Next, the second measurement unit 6 will be explained. The second measurement unit 6 is wired to the first measurement unit 4 . Information of the second measuring unit 6 is transmitted to the first measuring unit 4 . The second measurement unit 6 is arranged downstream of the first measurement unit 4 in the gas flow direction. The second measurement unit 6 has a thermal sensor 30 attached to the gas pipe 300 .

As shown in FIG. 3, the thermal sensor 30 includes a first fixed resistor 61, a second fixed resistor 62, a third fixed resistor 63, a heating resistor 64, a differential amplifier 65, and a power supply circuit 66. I have. The first fixed resistor 61 and the second fixed resistor 62 are connected in series. Also, the third fixed resistor 63 and the heating resistor 64 are connected in series. Furthermore, a series circuit including the first fixed resistor 61 and the second fixed resistor 62 and a series circuit including the third fixed resistor 63 and the heating resistor 64 are connected in parallel. A first fixed resistor 61, a second fixed resistor 62, a third fixed resistor 63, and a heating resistor 64 constitute a bridge circuit.

The differential amplifier 65 is connected to a point b between the first fixed resistor 61 and the second fixed resistor 62 and a point c between the third fixed resistor 63 and the heating resistor 64 . The differential amplifier 65 amplifies the potential difference between the points b and c and outputs it to the power supply circuit 66 . The power supply circuit 66 is connected to a point a between the first fixed resistor 61 and the third fixed resistor 63 and a point d between the second fixed resistor 62 and the heating resistor 64. Apply a voltage between The power supply circuit 66 adjusts the voltage applied between points a and d so that the potential at point b and the potential at point C are equal.

Next, a method for calculating the thermal conductivity of the gas inside the gas pipe 300 will be described. In the calorimeter 2 described above, information from the thermal sensor 30 of the second measurement unit 6 is transmitted to the first measurement unit 4 . The processing section 24 of the first measurement unit 4 calculates the thermal conductivity of the gas based on information from the thermal sensor 30 received from the second measurement unit 6 . The processing unit 24 calculates the thermal conductivity K (W/m·K) of the gas by, for example, the following arithmetic expressions (2) to (5). In the following equations (2) to (5), H (W/m·K) is the radiation coefficient of the heating resistor 64 in the thermal sensor 30. β is a predetermined correction coefficient between the radiation coefficient of the heating resistor 64 and the thermal conductivity of the gas. Pw is the power applied to the heating resistor 64 . Tw is the heat generation temperature of the heating resistor 64 . Ta is the temperature of the gas to be measured and detected by the temperature sensor 14 . Vw is the voltage applied to the heating resistor 64 . Rw is the resistance value of the heating resistor 64 . Tst is standard temperature (eg, 20° C.). Rst is the resistance value of the heating resistor 64 at the standard temperature Tst. α is the temperature coefficient of the material of the heating resistor 64 (for example, platinum). Iw is the current flowing through the heating resistor 64 (Iw can be assumed constant). The processing unit 24 can measure the heat radiation coefficient H by measuring the power Pw applied to the heating resistor 64 by the power supply circuit 66 of the thermal sensor 30 . The processing unit 24 can measure the thermal conductivity K of the gas by measuring the heat dissipation coefficient H.

Next, information stored in the storage section 26 of the first measurement unit 4 will be described. As shown in FIG. 4, the storage unit 26 stores information on a plurality of intervals (for example, intervals D1 to D7) corresponding to the thermal conductivity of gas to be measured. The relationship between the thermal conductivity of the gas and the corresponding section is stored in the storage unit 26 in the form of graphs and/or tables, for example. When the processing unit 24 measures the thermal conductivity K of the gas in the gas pipe 300, based on the graph and/or table shown in FIG. Interval D1) is identified.

In addition, as shown in FIG. 5, the storage unit 26 stores a linear function F (y=ax+b) corresponding to each section (see FIG. 4). A linear function F corresponding to each section is stored in the storage unit 26 in at least one form of, for example, a graph, a formula, and a table. A linear function F shown in FIG. 5 indicates the relationship between the speed of sound in the gas to be measured and the amount of heat per unit volume of the gas. The storage unit 26 stores a linear function F corresponding to each of the multiple intervals shown in FIG. The linear function F shown in FIG. 5 is, for example, a function corresponding to the section D1 shown in FIG. When the processing unit 24 identifies a section (for example, section D1) corresponding to the thermal conductivity K of the gas measured from the plurality of sections shown in FIG. A linear function F corresponding to the specified interval (for example, interval D1) is specified. Based on the identified linear function F, the processing unit 24 calculates the amount of heat per unit volume of the gas to be measured. The processing unit 24 substitutes the speed of sound in the gas to be measured into the specified linear function F to calculate the amount of heat per unit volume of the gas to be measured. In addition, below, the calorie|heat amount per unit volume of gas may be called "the calorie|heat amount of gas."

Next, a method for deriving information stored in the storage unit 26 will be described. First, the molar fractions of a plurality of components contained in the gas to be measured will be described. FIG. 6 shows the molar fractions of multiple components contained in the mixed gas, assuming that the gas is a mixed gas containing multiple components (eg, CH ₄ , C ₂ H ₆ , C ₃ H _{8 ,} etc.). An example rate is shown. The mixed gas to be measured contains a plurality of components within the range of mole fractions shown in FIG. For example, a certain gas mixture G1 has, in molar fractions, 96 mol% _CH4 , ₂ mol% _C2H6 , 1 mol% _C3H8 , ₀ mol% _C4H10 , 0 mol% _{N2 ,} CO 1 mol % of ₂ is included. Further, _another mixed gas G2 has, in molar fractions, _CH4 of 94 mol%, _C2H6 of 0 mol%, _C3H8 of ₃ mol%, _C4H10 of 0 mol%, and _N2 of 1 mol _. % and 2 mol % of _CO2 . In this specification, a mixed gas is also defined as a case where the mole fraction of methane (CH ₄ ) is 100 mol %.

When the mole fraction is changed in increments of 1 mol % within the mole fraction range shown in FIG. 6, there are 1593 possible combinations of the mole fractions of the components. That is, mixed gases with 1593 different compositions are assumed within the range of mole fractions shown in FIG. In addition to the composition of the mixed gas of G1 and G2 described above, the composition of the mixed gas from G3 to G1593 is assumed.

Next, regarding the thermal conductivity of gas, values calculated from known theory will be described. FIG. 7 shows an example of the thermal conductivity of a single gas, assuming that the gas is composed of a single component (eg, CH ₄ ). The thermal conductivities of single gases shown in FIG. 7 are already known. The thermal conductivity of a single gas may be calculated based on, for example, an arithmetic expression based on the Chapman-Enskog molecular kinetic theory. Also, the thermal conductivity K ₀ (W/m·K) of a single gas may be calculated, for example, based on the following arithmetic expression (6). In the following arithmetic expression (6), b1, b2, b3, and b4 are predetermined approximation coefficients. For example, if the single gas component is methane (CH ₄ ), the approximation coefficient b1 is −6.62E−3, b2 is 1.19E−4, and b3 is 5.64E−8. In the case of methane, b4 is not set. Ta is the temperature (K) of a single gas.

Further, when it is assumed that the gas is a mixed gas containing a plurality of components (eg, CH ₄ , C ₂ H ₆ , C ₃ H ₈ , etc.), the thermal conductivity Kx (W / m K ) is calculated, for example, based on the following equations (7) to (9) based on the Lindsay-Bromley theory and the thermal conductivity of a single gas shown in FIG. In the following arithmetic expressions (7) to (9), Xi and Xj are No. 1 shown in FIG. It is the molar fraction (mol%) of the components i and j. ηi and ηj are respectively No. Viscosity coefficients (Pa·s) of i and j components. Li and Lj are respectively No. It is the molecular weight (kg/kmol) of the components i and j. Also, S is the Sutherland constant, and Tg is the temperature (K) of the mixed gas. n is 6 in the example shown in FIG. The thermal conductivity Kx of the mixed gas is a theoretical value calculated based on the arithmetic expressions (7)-(9) and the thermal conductivity shown in FIG. The method for calculating the theoretical thermal conductivity Kx is not particularly limited.

Next, regarding the speed of sound in gas, values calculated from known theory will be described. FIG. 8 shows an example of the speed of sound in a single gas, assuming that the gas is a single gas consisting of a single component (eg, CH ₄ ). The speed of sound in a single gas, shown in Figure 8, is already known.

Further, when the gas is assumed to be a mixed gas containing a plurality of components (eg, CH ₄ , C ₂ H ₆ , C ₃ H ₈ , etc.), the sound velocity Cx (m/s) in the mixed gas is For example, it is calculated based on the following equation (10) and the speed of sound in a single gas shown in FIG. In the following arithmetic expression (10), Ci is No. shown in FIG. is the speed of sound in a single gas for the components of i. Mi is No. 1 shown in FIG. 8 contained in the mixed gas. is the molar fraction of the i component. n is 6 in the example shown in FIG. The sound velocity Cx in the mixed gas is a theoretical value calculated based on the equation (10) and the sound velocity shown in FIG. The method for calculating the theoretical sound velocity Cx is not particularly limited.

Next, a value calculated from a known theory for the amount of heat per unit volume of gas will be described. FIG. 9 shows an example of the amount of heat per unit volume of a single gas, assuming that the gas is a single gas consisting of a single component (eg, CH ₄ ). The amount of heat per unit volume of the single gas shown in FIG. 9 is already known.

In addition, when the gas is assumed to be a mixed gas containing multiple components (eg, CH ₄ , C ₂ H ₆ , C ₃ H ₈ , etc.), the heat quantity Qx (MJ/m ³ ) is calculated, for example, based on the following arithmetic expression (11) and the amount of heat per unit volume of a single gas shown in FIG. In the following arithmetic expression (11), Qi is No. shown in FIG. It is the amount of heat per unit volume of a single gas of the component i. Mi is No. 1 shown in FIG. 9 contained in the mixed gas. is the molar fraction of the i component. n is 6 in the example shown in FIG. The heat quantity Qx per unit volume of the mixed gas is a theoretical value calculated based on the calculation formula (11) and the heat quantity shown in FIG. The method for calculating the theoretical heat quantity Qx is not particularly limited. The heat quantity shown in FIG. 9 is the higher heating value when the gas pressure is 101.325 kPa and the gas temperature is 20.degree.

Next, a method for deriving the linear function F will be described. In the technology disclosed in the present specification, in order to derive the linear function F, first, the thermal conductivities of the mixed gases of a plurality of assumed compositions are rearranged in ascending order. In the example shown in FIG. 6 described above, mixed gases with 1593 different compositions are assumed when the mole fractions of a plurality of components are changed in increments of 1 mol %. FIG. 10 is a graph in which the thermal conductivities of mixed gases with 1593 possible compositions (1593 thermal conductivities) are arranged in ascending order. The graph in FIG. 10 corresponds to the graph in FIG. 4 described above.

Next, the graph shown in FIG. 10 is divided into a plurality of (eg, seven) sections (eg, sections D1-D7). The width of each section is arbitrary. For example, the width of each section is set to a width that facilitates execution of linear approximation, which will be described later. Each of the multiple intervals includes multiple thermal conductivity values.

Next, for each of the plurality of sections, the relationship between the sonic velocity in the plurality of mixed gases corresponding to the plurality of thermal conductivities included in the section and the heat quantity of the gas is arranged. FIG. 11 is a graph plotting the relationship between the sonic velocity in the mixed gas and the heat quantity of the mixed gas for a plurality of mixed gases in the section D1 of the graph shown in FIG. A similar graph is obtained for the other interval D2-D7 shown in FIG. The graph of FIG. 11 corresponds to the graph of FIG. 5 described above.

Next, a linear function F (y = ax + b) is derived based on linear approximation from the graph shown in FIG. do. For example, a linear function F is derived based on the method of least squares. Since the linear function F shown in FIG. 11 corresponds to the section D1 shown in FIG. 10, it is indicated as a linear function FD1. Further, linear functions FD2-FD7 are similarly derived based on linear approximation for the plurality of mixed gases in each of the plurality of sections D2-D7 shown in FIG. The linear functions FD1-FD7 are functions indicating the relationship between the speed of sound in the mixed gas and the heat quantity of the mixed gas. Note that in a modification, a function of quadratic or higher may be derived.

The storage unit 26 of the first measurement unit 4 stores the relationship between the thermal conductivity of the gas and the plurality of sections shown in FIG. 10 (see FIG. 4). The storage unit 26 also stores the relationship between the sound velocity in the gas and the heat quantity of the gas shown in FIG. 11 (see FIG. 5). The processing unit 24 calculates the calorie of the mixed gas to be measured based on the information shown in FIGS. 4-5 corresponding to FIGS. 10-11.

Next, a method for measuring the calorie of the gas (mixed gas) flowing through the gas pipe 300 with the calorimeter 2 will be described. In the calorimeter 2 described above, the processing unit 24 executes a first measurement process of measuring the speed of sound in the gas in the gas pipe 300 based on the detection results of the first ultrasonic sensor 10 and the second ultrasonic sensor 12. do. Since the configuration for measuring the speed of sound in gas has been described above, the description is omitted. Also, in the calorimeter 2 described above, the processing unit 24 performs a second measurement process of measuring the thermal conductivity of the gas in the gas pipe 300 based on the detection result of the thermal sensor 30 . Since the configuration for measuring the thermal conductivity of gas has been described above, the description is omitted.

In addition, when the processing unit 24 measures the thermal conductivity of the gas in the gas pipe 300, the processing unit 24 selects from a plurality of intervals (see FIG. 4) stored in the storage unit 26 an interval corresponding to the measured thermal conductivity (for example, , section D1). Further, the processing unit 24 identifies a linear function FD1 (see FIG. 5) corresponding to the identified interval (for example, interval D1) from the plurality of linear functions F stored in the storage unit 26 . Then, the processing unit 24 executes a process of calculating the calorie of the gas based on the specified linear function FD1 and the measured speed of sound in the gas. The processing unit 24 calculates the heat quantity of the gas by substituting the measured sound velocity in the gas into the specified linear function FD1.

(Test example)
FIG. 12 is a table showing an example of the calorie of the mixed gas measured by the calorimeter 2 described above. More specifically, FIG. 12 shows, for a plurality of gases with different compositions, the speed of sound in the gas to be measured, the linear function determined by the interval according to the thermal conductivity of the gas, and the speed of sound in the linear function and the gas. , the calorie Qx of the mixed gas as a theoretical value calculated by the arithmetic expression (11), and the error between the two. As shown in FIG. 12, in the test example, it was confirmed that the error between the calorie of the mixed gas measured by the calorimeter 2 and the calorie Qx of the mixed gas as a theoretical value was generally less than ±1%.

(Comparative example)
FIG. 13 is a table showing an example of the calorie of the mixed gas calculated according to the comparative example. In the comparative example, the calorific value of the gas was calculated based on a single linear function even if the thermal conductivity of the gas to be measured was different. A single linear function was derived based on linear approximation from a graph plotting the relationship between the speed of sound in the mixed gas and the calorific value of the mixed gas for all 1593 compositions of the mixed gas. FIG. 13 shows, for a plurality of gases with different compositions, calculation based on the sound velocity in the gas to be measured, a single linear function even if the thermal conductivity of the gas is different, and the linear function and the sound velocity in the gas. , the calorie Qx of the mixed gas as a theoretical value calculated by the arithmetic expression (11), and the error between the two. As shown in FIG. 13, in the comparative example, the error between the calorie of the mixed gas calculated based on a single linear function and the calorie Qx of the mixed gas as a theoretical value is shown in FIG. It was confirmed to be larger than the error shown. Therefore, it was confirmed that the calorific value of various gases with different compositions can be accurately measured by the calorimeter 2 disclosed in this specification.

The calorimeter 2 of the embodiment has been described above. As is clear from the above description, the calorimeter 2 performs a first measurement process for measuring the speed of sound in the mixed gas to be measured and a second measurement process for measuring the thermal conductivity of the mixed gas. A portion 24 is provided. The processing unit 24 performs a process of calculating the heat amount per unit volume of the gas based on the sound velocity in the gas measured by the first measurement process and the thermal conductivity of the gas measured by the second measurement process. do. According to this configuration, even if various gases have different compositions (even if the components contained in the mixed gas are different), the sound velocity in the gas and the thermal conductivity of the gas are measured accordingly, and The calorific value of the gas can be calculated based on Therefore, the calorific value of various gases having different compositions can be accurately measured with a simple configuration.

In addition, the processing unit 24 substitutes the speed of sound in the gas measured by the first measurement process into a predetermined linear function (for example, FD1) according to the thermal conductivity measured by the second measurement process, Calculate the calorific value of the gas. According to this configuration, the calorie of the gas can be accurately measured simply by substituting the speed of sound in the gas into the predetermined function.

In addition, the processing unit 24 selects a predetermined linear function (eg, , FD1), and substituting the speed of sound in the gas measured by the first measurement process into the specified linear function to calculate the calorie of the gas. According to this configuration, by specifying a linear function corresponding to the thermal conductivity of the gas from a plurality of linear functions, it is possible to accurately measure the calorie of the gas.

A predetermined linear function (eg, FD1-FD7) is set according to the thermal conductivity calculated based on the gas composition (see FIGS. 4-5 and 10-11). According to this configuration, it is possible to accurately measure the calorie of various gases having different compositions.

An embodiment has been described above, but specific aspects are not limited to the above embodiment. In the following description, the same reference numerals are given to the same configurations as those in the above description, and the description thereof is omitted.

(Modification)
(1) As shown in FIG. 14 , the gas pipe 300 may include a main pipe 302 and a measurement pipe 304 branching from the main pipe 302 . A second measurement unit 6 may be attached to the measurement pipe 304 . Also, the measurement pipe 304 may be provided with the first valve 90 and the second valve 92 . The first valve 90 is arranged upstream of the second measurement unit 6 in the gas flow direction. The second valve 92 is arranged downstream of the second measurement unit 6 in the gas flow direction. After opening the first valve 90 and the second valve 92 to allow the gas to be measured to flow into the measurement pipe 304, and then closing the first valve 90 and the second valve 92, the thermal conductivity of the gas is measured. measure.

(2) The first measurement unit 4 of the calorimeter 2 may include a communication section (not shown) capable of wireless communication and/or wired communication with other devices. The processing unit 24 may transmit information to another device via the communication unit. For example, the processing unit 24 may transmit information on the measured heat amount of the mixed gas to another device. Also, the processing unit 24 may receive information from other devices via the communication unit. For example, the processing unit 24 may receive the information of the graphs shown in FIGS. 4-5 from another device. The processing unit 24 may store information received from other devices in the storage unit 26 .

(3) The configuration for measuring the thermal conductivity of the gas to be measured is not limited to the configuration described above. For example, the thermal conductivity of gas may be measured using a method of forming a heat ray sensor with a microchip using MEMS technology. Since the method of forming a heat ray sensor with a microchip is already known, a detailed description thereof will be omitted. Also, the configuration for measuring the speed of sound in the gas to be measured is not particularly limited. Further, the sound waves propagating in the gas to be measured are not limited to ultrasonic waves.

(4) The processing unit 24 may calculate the total calorific value of the gas to be measured based on the measured calorific value per unit volume of the gas and the flow rate of the gas.

(5) The calorimeter 2 may be used in combination with an existing flowmeter (eg, ultrasonic flowmeter).

(6) The processing section 24 may be composed of a plurality of processing sections.

The technical elements described in this specification or in the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques exemplified in this specification or drawings can simultaneously achieve a plurality of purposes, and achieving one of them has technical utility in itself.

2: calorimeter, 4: first measurement unit, 6: second measurement unit, 10: first ultrasonic sensor, 12: second ultrasonic sensor, 14: temperature sensor, 16: pressure sensor, 20: display unit, 22: operation unit, 24: processing unit, 26: storage unit, 28: power supply, 30: thermal sensor, 61: first fixed resistor, 62: second fixed resistor, 63: third fixed resistor, 64: heating resistor , 65: differential amplifier, 66: power supply circuit, 90: first valve, 92: second valve, 300: gas pipe, 302: main pipe, 304: measurement pipe

Claims (4)

a first measurement process for measuring the velocity of sound waves propagating in the gas to be measured;
a processing unit that executes a second measurement process for measuring the thermal conductivity of the gas,
The processing unit is a calorimeter that calculates the amount of heat per unit volume of the gas based on the speed of sound waves measured by the first measurement process and the thermal conductivity measured by the second measurement process. The processing unit substitutes the speed of the sound wave measured by the first measurement process into a predetermined function according to the thermal conductivity measured by the second measurement process, thereby obtaining The calorimeter according to claim 1, which calculates the amount of heat. A storage unit storing a plurality of the functions corresponding to a plurality of thermal conductivities,
The processing unit specifies the predetermined function from the plurality of functions stored in the storage unit according to the thermal conductivity measured by the second measurement process, and assigns the specified function to the first 3. The calorimeter according to claim 2, wherein the amount of heat per unit volume of said gas is calculated by substituting the velocity of sound waves measured by the measurement process. 4. The calorimeter according to claim 2, wherein said function is set according to thermal conductivity calculated based on gas composition.

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