JP5344958B2 - Calorific value calculation formula creation system, calorific value calculation formula creation method, calorific value calculation system, and calorific value calculation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device capable of stably measuring a physical property value of a gas. <P>SOLUTION: A system for measuring the physical property value of the gas includes: a microchip 8A having a heating resistor; a driving circuit 303 supplying a plurality of different powers to the heating resistor of the microchip 8A and making the microchip 8A generate heat at a plurality of different heating temperatures; and a heat radiation coefficient calculation module 301 for calculating a heat radiation coefficient of a gas based on the values of the plurality of powers, the values of the plurality of heating temperature, and the gas temperature of the gas thermally equilibrated with the heating resistor. The supply of power to the heating resistor is stopped at least once while the driving circuit 303 makes the heating resistor generate heat at the plurality of different heating temperatures. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a gas inspection technique, and relates to a gas property value measurement system, a gas property value measurement method, a calorific value calculation formula creation system, a calorific value calculation formula creation method, a calorific value calculation system, and a calorific value calculation method.

Conventionally, when obtaining the calorific value of a mixed gas, it has been necessary to analyze the components of the mixed gas using an expensive gas chromatography apparatus or the like. Further, by measuring the thermal conductivity of the mixed gas and the speed of sound in the mixed gas, methane (CH ₄ ), propane (C ₃ H ₈ ), nitrogen (N ₂ ), and carbon dioxide (CO ₂ ) contained in the mixed gas. A method for calculating the component ratio of) and determining the calorific value of the mixed gas has also been proposed. However, in addition to the sensor for measuring the thermal conductivity, an expensive sound speed sensor for measuring the sound speed is required (for example, see Patent Document 1).

JP-T-2004-514138

  Furthermore, there is an increasing demand for detecting the heat generation amount of gas in real time, and there is a demand for faster and smaller devices for detecting the heat generation amount than ever before. Here, the large amount of calculation may limit the speeding up and downsizing of the apparatus. In the conventional technology, in order to calculate the calorific value of the mixed gas, a step of calculating the ratio of each gas component of the mixed gas and a step of calculating the calorific value of the mixed gas based on the calculated ratio are required. There is a problem that the amount of calculation is large. Therefore, the appearance of a detection method with a smaller amount of computation than before is desired. Accordingly, it is an object of the present invention to provide a method and apparatus for detecting a calorific value that requires a smaller amount of calculation than conventional ones. Another object of the present invention is to provide an apparatus that enables stable measurement of gas property values.

  According to an aspect of the present invention, a heating resistor, a drive circuit that applies a plurality of different powers to the heating resistor, and heats the heating resistor at a plurality of different heat generation temperatures, a plurality of power values, and a plurality of heat generations A gas property value measurement system comprising: a calculation unit that calculates a physical property value of a gas based on a temperature value and a gas temperature value of a gas that is in thermal equilibrium with the heating resistor. There is provided a gas property value measurement system that stops supplying power to the heating resistor at least once while the heating resistor is heated.

  According to the aspect of the present invention, the heating resistor is provided with a plurality of different electric powers, and the heating resistor is caused to generate heat at a plurality of different heating temperatures, and a plurality of power values, a plurality of heating temperature values, And calculating a physical property value of the gas based on a gas temperature value of the gas thermally balanced with the heating resistor, and at least once during the heating of the heating resistor, A method for measuring a gas property value is provided, characterized in that the supply of electric power is stopped.

  According to the gas property value measurement system and the gas property value measurement method according to the aspect of the present invention, the supply of power to the heating resistor is stopped at least once while the heating resistor is heated. Stable measurement of gas physical properties such as heat dissipation coefficient, thermal conductivity, and calorific value becomes possible.

  Further, as described above, conventionally, when calculating the calorific value of the mixed gas, a step of calculating the ratio of each gas component of the mixed gas is required. On the other hand, the inventors reviewed the calculation method of the calorific value, and examined whether the calorific value could be calculated without performing the step of calculating the ratio of each gas component of the mixed gas. The inventors have found theoretically and experimentally a method capable of uniquely calculating the calorific value of the mixed gas, using the heat dissipation coefficient or thermal conductivity of the mixed gas as input information.

  Therefore, according to an aspect of the present invention, a heating resistor, a driving circuit that applies a plurality of different electric powers to the heating resistor, and heats the heating resistor at a plurality of different heating temperatures, and a plurality of different heating temperatures, Measurement unit that measures multiple heat release coefficients or thermal conductivity values of a gas mixture that is in thermal equilibrium with the heating resistor, known heat generation value of the mixed gas, and multiple measured heat release coefficients or heat conduction A calorific value calculation formula comprising: a formula creation unit that creates a calorific value calculation formula using the heat dissipation coefficient or thermal conductivity at a plurality of heat generation temperatures as independent variables and the calorific value as a dependent variable based on the rate value A system for generating a calorific value calculation formula is provided, wherein the drive circuit stops supplying power to the heating resistor at least once while the heating circuit causes the heating resistor to generate heat.

  In addition, according to the aspect of the present invention, a plurality of different electric powers are applied to the heating resistor to cause the heating resistor to generate heat at a plurality of different heating temperatures, and at a plurality of different heating temperatures, Measuring a plurality of heat release coefficients or thermal conductivity values of a mixed gas in equilibrium with each other, a known calorific value of the mixed gas, and a plurality of measured heat release coefficients or heat conductivity values Generating a calorific value calculation formula using a heat dissipation coefficient or a thermal conductivity at a plurality of heat generation temperatures as an independent variable and a calorific value as a dependent variable. A method for creating a calorific value calculation formula is provided in which the supply of electric power to the heating resistor is stopped at least once during the operation.

  According to the calorific value calculation formula creation system and the calorific value calculation formula creation method according to the aspect of the present invention, it is possible to radiate the mixed gas without performing the step of calculating the ratio of each gas component of the mixed gas whose calorific value is unknown. A calorific value calculation formula capable of calculating the calorific value of the mixed gas from the coefficient or the thermal conductivity is provided.

  Furthermore, according to the aspect of the present invention, a heating resistor, a drive circuit that applies a plurality of different powers to the heating resistor, and heats the heating resistor at a plurality of different heating temperatures, and a plurality of different heating temperatures, A measurement unit that measures multiple heat release coefficients or thermal conductivity values of a measurement target gas mixture that is in thermal equilibrium with the heating resistor and whose calorific value is unknown, and multiple heat release coefficients or thermal conductivities at multiple heat generation temperatures Is an independent variable and a calorific value calculation formula with a calorific value as a dependent variable is stored, and a plurality of heat dissipation coefficients or thermal conductivity independent variables of the calorific value calculation formula are measured for the measurement target mixed gas. In a calorific value calculation system comprising: a calorific value calculation unit that calculates a calorific value of a measurement target mixed gas by substituting a plurality of heat dissipation coefficients or thermal conductivity values, the drive circuit causes the heating resistor to generate heat. At least once in between It stops the power supply to the heat resistor, the calorific value calculation system is provided.

  In addition, according to the aspect of the present invention, a plurality of different electric powers are applied to the heating resistor to cause the heating resistor to generate heat at a plurality of different heating temperatures, and at a plurality of different heating temperatures, Measure the multiple heat dissipation coefficients or thermal conductivity values of the measurement target gas mixture with unknown calorific value, and use multiple heat dissipation coefficients or thermal conductivities at multiple heat generation temperatures as independent variables. Prepare a calorific value calculation formula with 従 属 as a dependent variable, and multiple calorific value or thermal conductivity of the measurement target mixed gas in the independent variable of the multiple calorific value or thermal conductivity of the calorific value calculation formula. Substituting the value and calculating the value of the calorific value of the measurement target mixed gas, and supplying the power to the heating resistor at least once while the heating resistor generates heat. How to calculate calorific value to stop It is provided.

  According to the calorific value calculation system and calorific value calculation method according to the aspect of the present invention, the heat dissipation coefficient or heat of the mixed gas can be obtained without performing the step of calculating the ratio of each gas component of the mixed gas whose calorific value is unknown. The calorific value of the mixed gas can be calculated by measuring the conductivity.

  According to the present invention, it is possible to provide a gas property value measurement system and a gas property value measurement method that enable stable measurement of gas property values. Further, according to the present invention, it is possible to provide a calorific value calculation formula creation system, a calorific value calculation formula creation method, a calorific value calculation system, and a calorific value calculation method that can calculate the calorific value with a small amount of calculation.

1 is a perspective view of a microchip according to a first embodiment of the present invention. It is sectional drawing seen from the II-II direction of FIG. 1 of the microchip which concerns on the 1st Embodiment of this invention. It is a circuit diagram regarding the heat generating resistor which concerns on the 1st Embodiment of this invention. It is a circuit diagram regarding the auxiliary heater which concerns on the 1st Embodiment of this invention. It is a graph which shows the relationship between the heat_generation | fever temperature of the heat generating resistor which concerns on the 1st Embodiment of this invention, and the thermal radiation coefficient of gas. It is the 1st schematic diagram of the calorific value calculation formula creation system concerning a 1st embodiment of the present invention. It is the 2nd schematic diagram of the calorific value calculation formula creation system concerning a 1st embodiment of the present invention. It is a graph which shows the drive electric power of the heating resistor of the calorific value calculation formula creation system concerning a 1st embodiment of the present invention. It is a graph which shows the drive electric power of the heating resistor of the calorific value calculation formula creation system concerning the comparative example of the 1st embodiment of the present invention. It is a flowchart which shows the preparation method of the emitted-heat amount calculation formula which concerns on the 1st Embodiment of this invention. It is a graph which shows the drive electric power of the heating resistor of the calorific value calculation formula creation system concerning a 2nd embodiment of the present invention. It is a schematic diagram which shows the emitted-heat amount calculation system which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows the calculation method of the emitted-heat amount which concerns on the 3rd Embodiment of this invention. It is a table | surface which shows the composition and calorific value of the sample mixed gas which concerns on the Example of embodiment of this invention. It is a graph which shows the calculated calorific value and the true calorific value of the sample mixed gas concerning the example of the embodiment of the invention. It is a graph which shows the relationship of the calorific value of the sample mixed gas which concerns on the Example of embodiment of this invention, and the calculated calorific value. It is a graph which shows the relationship between the thermal conductivity which concerns on other embodiment of this invention, and a thermal radiation coefficient.

  Embodiments of the present invention will be described below. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(First embodiment)
First, referring to FIG. 1 which is a perspective view and FIG. 2 which is a cross-sectional view seen from the II-II direction, a calorific value calculation formula creation system and a calorific value calculation formula creation method according to the first embodiment The microchip 8A used for the above will be described. The microchip 8A includes a substrate 60A provided with a cavity 66A, and an insulating film 65A disposed on the substrate 60A so as to cover the cavity 66A. The thickness of the substrate 60A is, for example, 0.5 mm. The vertical and horizontal dimensions of the substrate 60A are, for example, about 1.5 mm. A portion of the insulating film 65A covering the cavity 66A forms a heat insulating diaphragm.

  Further, the microchip 8A includes a heating resistor 61A provided on the insulating film 65A, and a first resistance temperature measuring element 62A and a second temperature measuring resistance element provided on the insulating film 65A so as to sandwich the heating resistor 61A. 63A and a gas temperature sensor 64A provided on the substrate 60A. The gas temperature sensor 64A also includes an electric resistance element or the like. The heating resistor 61A is disposed at the center of the insulating film 65A covering the cavity 66A. The heating resistor 61A generates heat when power is applied, and heats the atmospheric gas in contact with the heating resistor 61A. The gas temperature sensor 64A is provided separately from the heating resistor 61A via the insulating film 65A, and detects the gas temperature of the atmospheric gas.

As a material of the substrate 60A, silicon (Si) or the like can be used. As a material of the insulating film 65A, silicon oxide (SiO ₂ ) or the like can be used. The cavity 66A is formed by anisotropic etching or the like. Further, platinum (Pt) or the like can be used as the material of the heating resistor 61A, the first temperature measuring resistance element 62A, the second temperature measuring resistance element 63A, and the gas temperature sensor 64A. It can be formed.

As shown in FIG. 3, for example, a positive input terminal of an operational amplifier 170 is electrically connected to one end of the heating resistor 61A, and the other end is grounded. A resistance element 161 is connected in parallel with the + input terminal and the output terminal of the operational amplifier 170. The negative input terminal of the operational amplifier 170 has a resistance element 162 and a resistance element 163 connected in series, a resistance element 163 and a resistance element 164 connected in series, and a resistance element 164 and a resistance element connected in series. 165 or electrically connected to the ground terminal of the resistance element 165. For example, a voltage Vin of 5.0 V is applied to the resistance element 162, and a voltage V _{L3 of} 2.4 V, for example, is applied to the resistance element 163. For example, a voltage V _{L2 of} 1.9 V is applied to the resistance element 164, and a voltage V _{L1 of} 1.4 V, for example, is applied to the resistance element 165.

  A switch SW1 is provided between the resistance element 162 and the resistance element 163 and between the negative input terminal of the operational amplifier, and between the resistive element 163 and the resistive element 164 and between the negative input terminal of the operational amplifier. Is provided with a switch SW2. Further, a switch SW3 is provided between the resistance element 164 and the resistance element 165 and between the negative input terminal of the operational amplifier, and between the ground terminal of the resistive element 165 and the negative input terminal of the operational amplifier. A switch SW4 is provided.

When a voltage V _L3 of 2.4 V is applied to the negative input terminal of the operational amplifier 170, only the switch SW1 is energized and the switches SW2, SW3, SW4 are disconnected. Of the operational amplifier 170 - When applying the voltage V _L2 of 1.9V to the input terminal, only the switch SW2 is turned on and the switches SW1, SW3, SW4 are disconnected. When a voltage V _L1 of 1.4 V is applied to the negative input terminal of the operational amplifier 170, only the switch SW3 is energized and the switches SW1, SW2, and SW4 are disconnected. When a voltage V _L0 of 0 V is applied to the negative input terminal of the operational amplifier 170, only the switch SW4 is energized and the switches SW1, SW2, and SW3 are disconnected. Therefore, either 0V or a three-stage voltage can be applied to the negative input terminal of the operational amplifier 170 by opening and closing the switches SW1, SW2, SW3, and SW4. Therefore, the heating temperature of the heating resistor 61A can be set in three stages by opening and closing the switches SW1, SW2, SW3, and SW4.

The resistance value of the heating resistor 61A shown in FIGS. 1 and 2 varies depending on the temperature. A heating temperature T _H of the heating resistor 61A, the relationship between the resistance value R _H of the heating resistor 61A, is given by the following equation (1).
R _H = R _STD × [1 + α (T _H -T _STD ) + β (T _H -T _STD ) ² ] (1)
Here, T _STD represents a standard temperature, for example, 20 ° C. R _STD represents a resistance value measured in advance at the standard temperature T _STD . α represents a first-order resistance temperature coefficient, and β represents a second-order resistance temperature coefficient. The resistance value R _H of the heating resistor 61A includes a driving power P _H of the heating resistor 61A, the current I _H flowing in the heating resistor 61A, given by the following equation (2).
R _H = P _H / I _H ² (2)
Alternatively, the resistance value R _H of the heating resistor 61A is given by the following equation (3) from the voltage V _H applied to the heating resistor 61A and the energization current I _H of the heating resistor 61A.
R _H = V _H / I _H (3)

Here, the heat generation temperature T _H of the heating resistor 61A is stabilized when during the heating resistor 61A and the ambient gas becomes thermally balanced. The thermally balanced state refers to a state in which the heat generation of the heating resistor 61A and the heat dissipation from the heating resistor 61A to the atmospheric gas are balanced. In equilibrium, as shown in the following equation (4), the driving power P _H of the heating resistor 61A, by dividing the difference between the gas temperature T _O of the heating temperature T _H and the ambient gas of the heating resistor 61A, radiation coefficient M _O of the atmosphere gas is obtained. The unit of the heat dissipation coefficient M _O is, for example, W / ° C.
M _O = P _H / (T _H -T _O ) (4)

Energizing current I _H of the heating resistor 61A, since the driving power P _H or the voltage V _H can be measured, the heat producing temperature T _H of the heating resistor 61A from above (1) to (3) can be calculated. Further, the gas temperature T _O of the atmospheric gas can be measured by the gas temperature sensor 64A shown in FIG. Thus, by using the microchip 8A illustrated in FIG. 1 and FIG. 2, the radiation coefficient M _O of the atmosphere gas can be calculated. Note that the gas temperature T _O of the atmospheric gas may be measured using the heating resistor 61A. By supplying the heating resistor 61A with power that does not affect the gas temperature T _O , the gas temperature T _O can be measured by the heating resistor 61A. When measuring the gas temperature T _O of the atmosphere gas in the heating resistor 61A, omit gas temperature sensor 64A, it may be simplified the structure of the microchip 8A. However, it should provided heating resistors 61A and the gas temperature sensor 64A separately are, thereby enabling more accurate measurement of the radiation coefficient M _O.

Further, the microchip 8A may include an auxiliary heater that keeps the temperature of the thermally conductive substrate 60A constant. By keeping the temperature of the substrate 60A constant, the temperature of the ambient gas in the vicinity of the microchip 8A before the heating resistor 61A generates heat approximates the constant temperature of the substrate 60A. Therefore, the variation in the temperature of the atmosphere gas is suppressed, it is possible to calculate the radiation coefficient M _O with higher accuracy. An electric resistance element or the like can also be used for the auxiliary heater. The gas temperature sensor 64A may also serve as an auxiliary heater.

As shown in FIG. 4, the gas temperature sensor 64A forms part of a resistance bridge circuit. The resistance bridge circuit includes a resistance element 181 connected in series with the gas temperature sensor 64A, and resistance elements 182 and 183 connected in parallel with the gas temperature sensor 64A and the resistance element 181. Here, the resistance value of the gas temperature sensor 64A is Rr, and the fixed resistance values of the resistance elements ₁₈₁ , ₁₈₂ , and ₁₈₃ are R ₁₈₁ , R ₁₈₂ , and R ₁₈₃ , respectively. An operational amplifier 171 is connected to the resistance bridge circuit. When the gas temperature sensor 64A functions as an auxiliary heater, bridge driving is performed so that the bridge voltage V _2a between the resistance element 181 and the gas temperature sensor 64A is equal to the bridge voltage V _2b between the resistance element 182 and the resistance element 183. The voltage V ₁ is feedback controlled. Thereby, the resistance value Rr of the gas temperature sensor 64A becomes constant, and the gas temperature sensor 64A generates heat at a constant temperature as an auxiliary heater.

Next, it is assumed that the atmospheric gas is a mixed gas, and the mixed gas is composed of four types of gas components: gas A, gas B, gas C, and gas D. Here, the sum of the volume ratio V _A of gas _A , the volume ratio V _B of gas _B , the volume ratio V _C of gas _C , and the volume ratio V _D of gas D is given by the following equation (5): 1.
V _A + V _B + V _C + V _D = 1 (5)

The calorific value per unit volume of gas A is K _A , the calorific value per unit volume of gas B is K _B , the calorific value per unit volume of gas C is K _C , and the calorific value per unit volume of gas D is Is K _D , the calorific value Q per unit volume of the mixed gas is given by the sum of the volume ratio of each gas component multiplied by the calorific value per unit volume of each gas component. Therefore, the calorific value Q per unit volume of the mixed gas is given by the following equation (6). The unit of the calorific value per unit volume is, for example, MJ / m ³ .
Q = K _A × V _A + K _B × V _B + K _C × V _C + K _D × V _D ... (6)

Moreover, the radiation coefficient M _A gas A, the radiation coefficient of gas B M _B, when the radiation coefficient of gas C M _C, the radiation coefficient of the gas D and M _D, the radiation coefficient M _I of the mixed gas, the It is given as the sum of the volume fraction of the gas component multiplied by the heat dissipation coefficient of each gas component. Therefore, the heat dissipation coefficient M _I of the mixed gas is given by the following equation (7).
M _I = M _A × V _A + M _B × V _B + M _C × V _C + M _D × V _D ... (7)

Further, since the radiation coefficient of gas depends on the heating temperature T _H of the heating resistor 61A, the radiation coefficient M _I of the mixed gas, as a function of the heating temperature T _H of the heating resistor 61A, given by the following equation (8) It is done.
M _I (T _H ) = M _A (T _H ) × V _A + M _B (T _H ) × V _B + M _C (T _H ) × V _C + M _D (T _H ) × V _D・ ・ ・ ( 8)

Therefore, the heat release coefficient M _I (T _H1 ) of the mixed gas when the heat generation temperature of the heat generation resistor 61A is T _H1 is given by the following equation (9), and the mixing is performed when the heat generation temperature of the heat generation resistor 61A is T _H2. The heat release coefficient M _I (T _H2 ) of the gas is given by the following formula (10), and the heat release coefficient M _I (T _H3 ) of the mixed gas when the heating temperature of the heating resistor 61A is T _H3 is given by the following formula (11). Given in. The exothermic temperature T _H1 , the exothermic temperature T _H2 , and the exothermic temperature T _H3 are different temperatures.
M _I (T _H1 ) = M _A (T _H1 ) × V _A + M _B (T _H1 ) × V _B + M _C (T _H1 ) × V _C + M _D (T _H1 ) × V _D・ ・ ・ ( 9)
M _I (T _H2 ) = M _A (T _H2 ) × V _A + M _B (T _H2 ) × V _B + M _C (T _H2 ) × V _C + M _D (T _H2 ) × V _D・ ・ ・ ( Ten)
M _I (T _H3 ) = M _A (T _H3 ) × V _A + M _B (T _H3 ) × V _B + M _C (T _H3 ) × V _C + M _D (T _H3 ) × V _D・ ・ ・ ( 11)

Here, the heat release coefficients M _A (T _H ), M _B (T _H ), M _C (T _H ), and M _D (T _H ) of each gas component are nonlinear with respect to the heat generation temperature T _H of the heat generation resistor 61A. The above formulas (9) to (11) have a linearly independent relationship. Moreover, the radiation coefficient M _A (T _H) of the gas components with respect to the heat producing temperature T _H of the heating resistor _{61A, M B (T H)} , M C (T H), M D (T H) is linearity even with a change in the radiation coefficient M _a of the gas component to the heat producing temperature T _H of the heating resistor _{61A (T H), M B} (T H), M C (T H), M D (T H) When the rates are different, the above equations (9) to (11) have a linearly independent relationship. Further, when the equations (9) to (11) have a linearly independent relationship, the equations (5) and (9) to (11) have a linearly independent relationship.

FIG. 5 shows the relationship between the heat dissipation coefficient of methane (CH ₄ ), propane (C ₃ H ₈ ), nitrogen (N ₂ ), and carbon dioxide (CO ₂ ) contained in natural gas and the heat generation temperature of the heat generating resistor 61A. It is a graph to show. The heat release coefficient of each gas component of methane (CH ₄ ), propane (C ₃ H ₈ ), nitrogen (N ₂ ), and carbon dioxide (CO ₂ ) is linear with respect to the heat generation temperature of the heat generating resistor 61A. Have. However, the rate of change of the heat dissipation coefficient with respect to the heat generation temperature of the heating resistor 61A is different for each of methane (CH ₄ ), propane (C ₃ H ₈ ), nitrogen (N ₂ ), and carbon dioxide (CO ₂ ). Therefore, when the gas components constituting the mixed gas are methane (CH ₄ ), propane (C ₃ H ₈ ), nitrogen (N ₂ ), and carbon dioxide (CO ₂ ), the above (9) to (11 ) Has a linearly independent relationship.

Now, the radiation coefficient M _A (T _H1 ), M _B (T _H1 ), M _C (T _H1 ), M _D (T _H1 ), M _A (T (T) _{H2), M B (T H2} ), M C (T H2), M D (T H2), M A (T H3), M B (T H3), M C (T H3), M D (T H3 ) Can be obtained in advance by measurement or the like. Therefore, when the simultaneous equations of the equations (5) and (9) to (11) are solved, the volume ratio V _{A of} the gas _A , the volume ratio V _{B of} the gas _B , the volume ratio V _{C of} the gas _C , and the gas D Each of the volume ratios V _D is expressed as a function of the heat release coefficient M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 ) of the mixed gas as shown in the following equations (12) to (15). Given. In the following equations (12) to (15), n is a natural number and f _n is a symbol representing a function.
V _A = f ₁ [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 )] (12)
V _B = f ₂ [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 )] (13)
V _C = f ₃ [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 )] (14)
V _D = f ₄ [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 )] (15)

Here, the following equation (16) is obtained by substituting the equations (12) to (15) into the above equation (6).
Q = K _A × V _A + K _B × V _B + K _C × V _C + K _D × V _D
= K _A × f ₁ [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 )] + K _B × f ₂ [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 )]
+ K _C × f ₃ [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 )] + K _D × f ₄ [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 )] ... (16)

As is clear from the above equation (16), the calorific value Q per unit volume of the mixed gas is the heat dissipation coefficient M _I (T _H1 ) of the mixed gas at the heat generation temperatures T _H1 , T _H2 , T _H3 of the heating resistor 61A. , M _I (T _H2 ), M _I (T _H3 ) are given as equations. Therefore, the calorific value Q of the mixed gas is given by the following equation (17), where g is a symbol representing a function.
Q = g [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 )] (17)

Therefore, if the above equation (17) is obtained in advance for a mixed gas composed of gas A, gas B, gas C, and gas D, the volume ratio V _A of gas _A , the volume ratio V _B of gas _B , and the gas C The inventors have found that the calorific value Q per unit volume of the gas to be inspected with unknown volume ratio V _C and volume ratio V _{D of} gas D can be easily calculated. Specifically, the heat release coefficients M _I (T _H1 ), M _I (T _H2 ), and M _I (T _H3 ) of the mixed gas to be inspected at the heating temperatures T _H1 , T _H2 , and T _H3 of the heating resistor 61A are measured. Then, by substituting into the equation (17), it is possible to uniquely determine the calorific value Q of the mixed gas to be inspected.

The gas components of the mixed gas are not limited to four types. For example, when the mixed gas is composed of n types of gas components, first, at least n−1 types of heat generation temperatures T _H1 , T _H2 , T _H3,. , T _Hn-1, M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 ), ..., M _I (T _Hn-1 ) Get in advance. Then, the n-1 types of heat generation temperatures T _H1 , T _H2 , T _H3 ,..., T _Hn-1 of the heating resistor 61A are inspected mixed gases whose volume ratios of the n types of gas components are unknown. By measuring the heat dissipation coefficients M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 ),..., M _I (T _Hn-1 ), and substituting them into the equation (18), The calorific value Q per unit volume of the inspection target mixed gas can be uniquely determined.
Q = g [M _I (T _H1 ), M _I (T _H2 ), M _I (T _H3 ), ..., M _I (T _Hn-1 )] (18)

However, the mixed gas, methane (CH ₄₎ as a gas component in addition to the propane (C ₃ H _8), a j is a natural number, methane (CH ₄₎ and other than propane (C ₃ H ₈₎ alkane (C _j H _{2j + 2} ), alkanes other than methane (CH ₄ ) and propane (C ₃ H ₈ ) (C _j H _{2j + 2} ), and mixtures of methane (CH ₄ ) and propane (C ₃ H ₈ ) This does not affect the calculation of equation (18). For example, ethane (C ₂ H ₆ ), butane (C ₄ H ₁₀ ), pentane (C ₅ H ₁₂ ), and hexane (C ₆ H ₁₄ ) are respectively represented by the following formulas (19) to (22): The equation (18) may be calculated by regarding the mixture as methane (CH ₄ ) and propane (C ₃ H ₈ ) multiplied by a predetermined coefficient.
C ₂ H ₆ = 0.5 CH ₄ + 0.5 C ₃ H ₈ ... (19)
C ₄ H ₁₀ = -0.5 CH ₄ + 1.5 C ₃ H ₈ ... (20)
C ₅ H ₁₂ = -1.0 CH ₄ + 2.0 C ₃ H ₈ ... (21)
C ₆ H ₁₄ = -1.5 CH ₄ + 2.5 C ₃ H ₈ ... (22)

Accordingly, the z as a natural number, a mixed gas consisting of n kinds of gas components methane (CH ₄₎ as a gas component in addition to the propane (C ₃ H _8), methane (CH ₄₎ and propane (C ₃ H ₈ ) Other than z types of alkanes (C _j H _{2j + 2} ), an equation having at least the heat release coefficient of the mixed gas at the nz−1 types of heat generation temperatures as variables may be obtained.

In addition, when the type of the gas component of the mixed gas used in the calculation of the equation (18) is the same as the type of the gas component of the mixed gas to be inspected whose calorific value Q per unit volume is unknown, Of course, the equation (18) can be used to calculate the calorific value Q. Furthermore, when the inspection target mixed gas is composed of less than n kinds of gas components and less than n kinds of gas components are included in the mixed gas used in the calculation of equation (18), Equation (18) can be used. For example, the mixed gas used in the calculation of the equation (18) includes four types of gas components, methane (CH ₄ ), propane (C ₃ H ₈ ), nitrogen (N ₂ ), and carbon dioxide (CO ₂ ). In some cases, the mixed gas to be inspected does not contain nitrogen (N ₂ ) but contains only three kinds of gas components, methane (CH ₄ ), propane (C ₃ H ₈ ), and carbon dioxide (CO ₂ ). The equation (18) can be used to calculate the calorific value Q of the inspection target mixed gas.

Further, when the mixed gas used in the calculation of the equation (18) contains methane (CH ₄ ) and propane (C ₃ H ₈ ) as gas components, the inspection target mixed gas is used in the calculation of the equation (18). Even if the alkane (C _j H _{2j + 2} ) not contained in the mixed gas is contained, the formula (18) can be used. This is because, as described above, the methane (CH ₄₎ and propane (C ₃ H ₈₎ other than the alkane _{(C j H 2j + 2)} , a mixture of methane (CH ₄₎ and propane (C ₃ H ₈₎ Even if it considers, it is because it does not affect calculation of the emitted-heat amount Q per unit volume using (18) Formula.

  Here, the calorific value calculation formula creation system 20 according to the first embodiment shown in FIG. 6 generates heat at a plurality of different exothermic temperatures with the chamber 101 filled with a sample mixed gas whose calorific value is known. The measurement mechanism 10 shown in FIG. 6 that measures the values of a plurality of heat dissipation coefficients of the sample mixed gas, the value of the known calorific value of the sample mixed gas, and the measurement using the heating resistor 61A shown in FIGS. And a formula generation module 302 that generates a calorific value calculation formula using the heat radiation coefficient at a plurality of heat generation temperatures of the heat generating resistor as independent variables and the calorific value as a dependent variable based on the plurality of heat dissipation coefficient values. The sample mixed gas includes a plurality of types of gas components.

  The measurement mechanism 10 includes the microchip 8A described with reference to FIGS. 1 and 2 disposed in the chamber 101 into which the sample mixed gas is injected. The microchip 8A may be disposed in the chamber 101 via a heat insulating material. By the heat insulating material, the temperature of the microchip 8 </ b> A becomes less susceptible to the temperature fluctuation of the inner wall of the chamber 101. The heat conductivity of the heat insulating material is, for example, 10 W / (m · K) or less. The chamber 101 is connected to a flow path 102 for sending the sample mixed gas to the chamber 101 and a flow path 103 for discharging the sample mixed gas from the chamber 101 to the outside.

  When four types of sample mixed gases are used, as shown in FIG. 7, the first gas cylinder 50A for storing the first sample mixed gas, the second gas cylinder 50B for storing the second sample mixed gas, A third gas cylinder 50C for storing the third sample mixed gas and a fourth gas cylinder 50D for storing the fourth sample mixed gas are prepared. In the first gas cylinder 50A, a first gas pressure regulator 31A for obtaining a first sample mixed gas adjusted to a low pressure such as 0.2 MPa from the first gas cylinder 50A via a flow path 91A. Is connected. In addition, a first flow rate control device 32A is connected to the first gas pressure regulator 31A via a flow path 92A. The first flow rate control device 32A controls the flow rate of the first sample mixed gas sent to the calorific value calculation formula creation system 20 via the flow path 92A and the flow path 102.

  A second gas pressure regulator 31B is connected to the second gas cylinder 50B via a flow path 91B. The second flow rate controller 32B is connected to the second gas pressure regulator 31B via a flow path 92B. The second flow rate control device 32B controls the flow rate of the second sample mixed gas sent to the calorific value calculation formula creation system 20 via the flow paths 92B, 93, 102.

  A third gas pressure regulator 31C is connected to the third gas cylinder 50C via a flow path 91C. In addition, a third flow rate control device 32C is connected to the third gas pressure regulator 31C via a flow path 92C. The third flow rate control device 32C controls the flow rate of the third sample mixed gas sent to the calorific value calculation formula creation system 20 via the flow paths 92C, 93, 102.

  A fourth gas pressure regulator 31D is connected to the fourth gas cylinder 50D via a flow path 91D. In addition, a fourth flow rate control device 32D is connected to the fourth gas pressure regulator 31D via a flow path 92D. The fourth flow rate control device 32D controls the flow rate of the fourth sample mixed gas sent to the calorific value calculation formula creation system 20 via the flow paths 92D, 93, 102.

Each of the first to fourth sample mixed gases is, for example, natural gas. Each of the first to fourth sample mixed gases includes four kinds of gas components, for example, methane (CH ₄ ), propane (C ₃ H ₈ ), nitrogen (N ₂ ), and carbon dioxide (CO ₂ ).

The heating resistor 61A shown in FIG. 1 and FIG. 2 of the microchip 8A shown in FIG. 6 is connected to the first circuit during a predetermined time WT ₁ from the drive circuit 303 shown in FIG. 6, for example, as shown in FIG. Drive power PH _{# 1} . By applying the first driving power PH _{# 1} , the heating resistor 61A shown in FIGS. 1 and 2 of the microchip 8A generates heat at 100 ° C., for example. After time WT ₂ has elapsed since the _first driving power PH _{# 1} was applied to the heating resistor 61A, the gas temperature sensor 64A of the microchip 8A is thermally connected to the heating resistor 61A that generates heat at 100 ° C. The gas temperature T _{O # H = 100} of the balanced first sample mixed gas is detected. Time WT ₂ is shorter than time WT ₁ . The reason why the gas temperature sensor 64A detects the gas temperature T _{O # H = 100} after the time WT ₂ has elapsed since the driving power P _{H # 1} is given to the heating resistor 61A is that the heating temperature of the heating resistor 61A This is to wait until the heating resistor 61A and the first sample mixed gas are in thermal equilibrium.

The driving circuit 303 shown in FIG. 6, as shown in FIG. 8, during time WT _1, after giving the first driving power P _{H # 1} the heating resistor 61A, during time WT _3, the driving power Stop providing. Thereafter, the heating resistor 61A during the time WT _1, the driving circuit 303 is given to the second driving power P _{H # 2,} generates heat, for example, 0.99 ° C.. The gas temperature sensor 64A generates heat at 150 ° C. after a time WT ₂ shorter than the time WT ₁ has elapsed since the _second driving power PH _{# 2} was applied to the heating resistor 61A shown in FIGS. The gas temperature T _{O # H = 150} of the first sample mixed gas in thermal equilibrium with the heating resistor 61A is detected.

The driving circuit 303 shown in FIG. 6, as shown in FIG. 8, during time WT _1, after giving the second driving power P _{H # 2} heating resistors 61A, during time WT _3, the driving power Stop providing. Thereafter, the heating resistor 61A during the time WT _1, the driving circuit 303 is given a third driving power P _{H # 3,} generates heat, for example 200 ° C.. The gas temperature sensor 64A includes a heating resistor 61A that generates heat at 200 ° C. after the time WT ₂ has elapsed since the _third driving power PH _{# 3} is applied to the heating resistor 61A shown in FIGS. The gas temperature T _{O # H = 200} of the first sample mixed gas that is thermally balanced is detected.

  As shown in FIGS. 1 and 2, the heating resistor 61A is surrounded by an insulating film 65A. However, as shown in FIG. 9, when driving power is continuously applied to the heating resistor 61A and the heating resistor 61A continues to generate heat, heat may be transferred from the heating resistor 61A shown in FIGS. 1 and 2 to the substrate 60A. Since the substrate 60A made of silicon (Si) or the like has a short thermal time constant (JIS C2570-1), it is easily affected by heat. For this reason, when heat is transferred from the heating resistor 61A to the substrate 60A, the temperature of the substrate 60A may fluctuate rapidly, and the temperature of the ambient gas around the substrate 60A may also fluctuate. In this case, it may be necessary to wait for a long time until the heating resistor 61A and the atmospheric gas are in thermal equilibrium. Further, if the heating resistor 61A continues to generate heat, the resistance value of the heating resistor 61A drifts and the heating temperature may not be constant.

  On the other hand, as shown in FIG. 8, it is possible to suppress the heating resistor 61A from affecting the temperature of the substrate 60A by intermittently applying driving power to the heating resistor 61A. Accordingly, it is possible to shorten the time until the heating resistor 61A and the atmospheric gas are in a thermal equilibrium state. In addition, power consumption can be suppressed.

After the first sample mixed gas is removed from the chamber 101 shown in FIG. 6, the chamber 101 is sequentially filled with the second to fourth sample mixed gases. The microchip 8A has gas temperatures T _{O # H = 100} , T _{O # H = 150} for the heating temperatures of 100 ° C., 150 ° C., and 200 ° C. of the heating resistor 61A of each of the second to fourth sample mixed gases. T _{O # H = 200} is detected.

In addition, when each sample mixed gas contains n types of gas components, the heating resistor 61A shown in FIGS. 1 and 2 of the microchip 8A is caused to generate heat at at least n-1 types of different heating temperatures. However, as described above, methane (CH ₄₎ and propane (C ₃ H ₈₎ other than the alkane (C _j H _{2j + 2)} is regarded as a mixture of methane (CH ₄₎ and propane (C ₃ H ₈₎ sell. Accordingly, a sample mixed gas composed of n kinds of gas components, where z is a natural number, is added to methane (CH ₄ ) and propane (C ₃ H ₈ ) as gas components, and z kinds of alkanes (C _j H _{2j + 2} ). When the heat generating resistor 61A is included, the heating resistor 61A is caused to generate heat at at least nz-1 different heat generation temperatures.

Furthermore, the measurement mechanism 10 shown in FIG. 6 includes a heat dissipation coefficient calculation module 301 connected to the microchip 8A. As shown in the above equation (4), the heat dissipation coefficient calculation module 301 uses the first drive power PH _{# 1} of the heating resistor 61A of the microchip 8A shown in FIGS. 1 and 2 as the heat generation of the heating resistor 61A. Dividing by the difference between the temperature T _H (here, 100 ° C.) and the gas temperature T _{O # H = 100} of each of the first to fourth sample mixed gases, it is thermally balanced with the heating resistor 61A having a heating temperature of 100 ° C. The heat dissipation coefficient values of the first to fourth sample mixed gases at that time are calculated.

Further, the heat dissipation coefficient calculation module 301 shown in FIG. 6 uses the second drive power P _{H # 2} of the heating resistor 61A shown in FIGS. 1 and 2 of the microchip 8A as the heating temperature T _H ( Here, 150 ° C.) is divided by the difference between the gas temperatures T _{O # H = 150 of} the first to fourth sample mixed gases, and the first temperature when the heating resistor 61A having a heating temperature of 150 ° C. is in thermal equilibrium is divided. The value of the heat dissipation coefficient of each of the first to fourth sample mixed gases is calculated.

Further, the heat dissipation coefficient calculation module 301 shown in FIG. 6 uses the third drive power P _{H # 3} of the heating resistor 61A shown in FIGS. 1 and 2 of the microchip 8A as the heating temperature T _H ( Dividing by the difference between the gas temperature T _{O # H = 200 of} the first to fourth sample mixed gases in this case, and the first to fourth sample mixed gases are thermally balanced with the heating resistor 61A having a heating temperature of 200 ° C. The value of the heat dissipation coefficient of each of the first to fourth sample mixed gases is calculated.

  The formula creation module 302 shown in FIG. 6 includes, for example, a known calorific value of each of the first to fourth sample mixed gases, a measured value of the heat dissipation coefficient at a heat generation temperature of 100 ° C., and a heat dissipation coefficient at a heat generation temperature of 150 ° C. And the measured value of the heat dissipation coefficient at an exothermic temperature of 200 ° C. are collected. Furthermore, the formula creation module 302 determines that the A.D. J Smol and B.M. In Support Vector Regression, Multiple Regression Analysis, and Japanese Patent Application Laid-Open No. 5-141999, disclosed in Scholkopf's “A Tutor on Support Vector Regression” (NeuroCOLt Technical Report (NC-TR-98-030), 1998). By multivariate analysis including the disclosed fuzzy quantification theory type II, etc., the heat release coefficient at an exothermic temperature of 100 ° C., the heat release coefficient at an exothermic temperature of 150 ° C., and the heat release coefficient at an exothermic temperature of 200 ° C. are set as independent variables. Calculate a calorific value calculation formula as a dependent variable. The heat dissipation coefficient calculation module 301 and the formula creation module 302 are included in a central processing unit (CPU) 300.

  The calorific value calculation formula creation system 20 further includes a heat dissipation coefficient storage device 401 and a formula storage device 402 connected to the CPU 300. The heat dissipation coefficient storage device 401 stores the value of the heat dissipation coefficient calculated by the heat dissipation coefficient calculation module 301. The formula storage device 402 stores the calorific value calculation formula created by the formula creation module 302. Further, an input device 312 and an output device 313 are connected to the CPU 300. As the input device 312, for example, a keyboard and a pointing device such as a mouse can be used. As the output device 313, an image display device such as a liquid crystal display and a monitor, a printer, and the like can be used.

  Next, a method for creating a calorific value calculation formula according to the first embodiment will be described using the flowchart shown in FIG. In the following example, a case will be described in which the first to fourth sample mixed gases are prepared and the heating resistor 61A of the microchip 8A shown in FIG. 6 generates heat at 100 ° C., 150 ° C., and 200 ° C. .

(A) In step S100, with the valves of the second to fourth flow rate control devices 32B-32D shown in FIG. 7 closed, the valve of the first flow rate control device 32A is opened and placed in the chamber 101 shown in FIG. A first sample mixed gas is introduced. In step S101, the drive circuit 303, the heating resistor 61A shown in FIGS. 1 and 2 of the microchip 8A, for example, during the time WT _1, providing a first driving power P _{H # 1,} the heating resistor 61A is heated at 100 ° C. While the heating resistor 61A is generating heat at 100 ° C., the gas temperature sensor 64A detects the gas temperature T _{O # H = 100} of the first sample mixed gas that is in thermal equilibrium with the heating resistor 61A. The heat dissipation coefficient calculation module 301 shown in FIG. 6 calculates the value of the heat dissipation coefficient of the first sample mixed gas at an exothermic temperature of 100 ° C. Thereafter, the heat dissipation coefficient calculation module 301 stores the value of the heat dissipation coefficient of the first sample mixed gas at the heat generation temperature of 100 ° C. in the heat dissipation coefficient storage device 401.

(B) In step S102, the drive circuit 303, the supply of the drive power to the heating resistor 61A, and stops until the lapse of time WT _3. In step S103, the drive circuit 303 shown in FIG. 6 determines whether or not the switching of the heat generation temperature of the heat generating resistor 61A shown in FIGS. 1 and 2 has been completed. If the switching to the heat producing temperature 0.99 ° C. and the heating temperature of 200 ° C. is not completed, the process returns to step S101, the driving circuit 303 shown in FIG. 6, the heating resistor 61A shown in FIGS. 1 and 2 times WT ₁ Exotherm at 150 ° C. The heat dissipation coefficient calculation module 301 shown in FIG. 6 calculates the value of the heat dissipation coefficient of the first sample mixed gas at an exothermic temperature of 150 ° C. and stores it in the heat dissipation coefficient storage device 401. Further, in step S102, the drive circuit 303, the supply of the drive power to the heating resistor 61A, and stops until the lapse of time WT _3.

(C) In step S103 again, it is determined whether or not the switching of the heating temperature of the heating resistor 61A shown in FIGS. 1 and 2 has been completed. If the switching to the heat producing temperature 200 ° C. is not completed, the process returns to step S101, the driving circuit 303 shown in FIG. 6, at 200 ° C. During the heating resistor 61A time WT ₁ shown in FIGS. 1 and 2 Causes fever. The heat dissipation coefficient calculation module 301 shown in FIG. 6 calculates the value of the heat dissipation coefficient of the first sample mixed gas at an exothermic temperature of 200 ° C. and stores it in the heat dissipation coefficient storage device 401. In step S102, the drive circuit 303 stops the supply of drive power to the heating resistor 61A shown in FIGS.

  (D) When switching of the heat generation temperature of the heat generating resistor 61A is completed, the process proceeds from step S103 to step S104. In step S104, it is determined whether switching of the sample mixed gas is completed. If switching to the second to fourth sample mixed gases has not been completed, the process returns to step S100. In step S100, the first flow control device 32A shown in FIG. 7 is closed, the valves of the second flow control device 32B are opened while the valves of the third to fourth flow control devices 32C-32D are closed, and FIG. A second sample mixed gas is introduced into the chamber 101 shown in FIG.

  (E) Similar to the first sample mixed gas, the loop of step S101 to step S103 is repeated, and the heat dissipation coefficient calculation module 301 determines the value of the heat dissipation coefficient of the second sample mixed gas at the heat generation temperature of 100 ° C., the heat generation temperature. The value of the heat dissipation coefficient of the second sample mixed gas at 150 ° C. and the value of the heat dissipation coefficient of the second sample mixed gas at an exothermic temperature of 200 ° C. are calculated and stored in the heat dissipation coefficient storage device 401.

  (F) Thereafter, the loop of step S100 to step S104 is repeated, and the value of the heat release coefficient of the third sample mixed gas at each of the exothermic temperatures of 100 ° C, 150 ° C, and 200 ° C, and the exothermic temperatures of 100 ° C, 150 ° C, The value of the heat dissipation coefficient of the fourth sample mixed gas at 200 ° C. is stored in the heat dissipation coefficient storage device 401.

  (G) In step S105, the input unit 312 sends the formula generating module 302 the known calorific value of the first sample mixed gas, the known calorific value of the second sample mixed gas, and the third sample mixed Enter the known calorific value of the gas and the known calorific value of the fourth sample gas mixture. Further, the formula creation module 302 reads from the heat dissipation coefficient storage device 401 the values of the heat dissipation coefficients of the first to fourth sample mixed gases at the heating temperatures of 100 ° C., 150 ° C., and 200 ° C., respectively.

  (H) In step S106, the value of the heat generation amount of the first to fourth sample mixed gases and the value of the heat dissipation coefficient of the first to fourth sample mixed gases at each of the heat generation temperatures of 100 ° C., 150 ° C., and 200 ° C. Based on the above, the formula creation module 302 performs multiple regression analysis, using the heat release coefficient at a heat generation temperature of 100 ° C., the heat release coefficient at a heat generation temperature of 150 ° C., and the heat release coefficient at a heat generation temperature of 200 ° C. as independent variables, and the heat generation amount as a dependent variable. The calorific value calculation formula is calculated. Thereafter, in step S107, the formula creation module 302 stores the created calorific value calculation formula in the formula storage device 402, and ends the calorific value calculation formula creation method according to the first embodiment.

  As described above, according to the system and method for generating a calorific value calculation formula according to the first embodiment, the heat dissipation coefficient of the measurement target mixed gas whose calorific value is unknown is measured for a plurality of heat generation temperatures. By doing so, it is possible to create a calorific value calculation formula that can uniquely calculate the calorific value of the measurement target mixed gas. In addition, as described with reference to FIG. 8, by intermittently applying driving power to the heating resistor 61A, the heat dissipation coefficient of the sample mixed gas can be obtained accurately and at high speed.

(Second Embodiment)
In the first embodiment, when driving power is applied to the heating resistor 61A shown in FIGS. 1 and 2, as shown in FIG. 8, the period during which the driving power is stopped every time different driving power is applied. The example which provides is shown. On the other hand, for example, when the sample mixed gas includes seven kinds of gas components and the first to sixth driving powers need to be supplied to the heating resistor 61A, the heat generation of the heating resistor 61A causes the temperature fluctuation of the substrate 60A. As long as it is within the time range that does not affect, the first to third driving powers may be continuously applied to the heating resistor 61A as shown in FIG. After providing the third heating resistor 61A drive power, for example, until time WT ₄ has elapsed, by stopping the provision of driving power, it is possible to lower the temperature of the heating resistor 61A. Therefore, after that, if the fourth to sixth driving powers are applied to the heating resistor 61A within a time range in which the heat generation of the heating resistor 61A does not affect the temperature fluctuation of the substrate 60A, the fourth to sixth driving powers are provided. The gas temperature of the sample mixed gas that is in thermal equilibrium with the heating resistor 61A that generates heat is measured accurately.

(Third embodiment)
As shown in FIG. 12, the calorific value calculation system 21 according to the third embodiment generates heat at a plurality of different heat generation temperatures in a chamber 101 filled with a measurement target mixed gas whose calorific value is unknown. 1 and 2, the measurement mechanism 10 shown in FIG. 12 measures the values of a plurality of heat dissipation coefficients of the measurement target mixed gas, the heat dissipation coefficients at a plurality of heat generation temperatures are independent variables, and generates heat. An equation storage device 402 that stores a calorific value calculation formula having a quantity as a dependent variable, and an independent variable of a heat dissipation coefficient at a plurality of exothermic temperatures in the calorific value calculation formula are measured for a plurality of exothermic temperatures of the measurement target mixed gas. A heat generation amount calculation module 305 is provided that substitutes the value of the heat dissipation coefficient and calculates the value of the heat generation amount of the measurement target mixed gas.

The formula storage device 402 stores the calorific value calculation formula created as described in the first embodiment. Here, as an example, a natural gas containing methane (CH ₄ ), propane (C ₃ H ₈ ), nitrogen (N ₂ ), and carbon dioxide (CO ₂ ) is mixed with a sample to create a calorific value calculation formula. The case where it is used as a gas will be described. Further, the calorific value calculation formula assumes that the heat release coefficient at a heat generation temperature of 100 ° C., the heat release coefficient at a heat generation temperature of 150 ° C., and the heat release coefficient at a heat generation temperature of 200 ° C. are independent variables.

In the third embodiment, for example, the calorific value is unknown, including methane (CH ₄ ), propane (C ₃ H ₈ ), nitrogen (N ₂ ), and carbon dioxide (CO ₂ ) at an unknown volume ratio. Natural gas is introduced into the chamber 101 as a measurement target mixed gas. Heating resistor 61A shown in FIGS. 1 and 2 of the microchip 8A illustrated in FIG. 12, the driving circuit 303 shown in FIG. 12, for example, as shown in FIG. 8, during time WT _1, a first driving power P Given _{H # 1} , exotherm at 100 ° C. After a time WT ₂ shorter than the time WT ₁ has elapsed since the _first driving power PH _{# 1} was applied to the heating resistor 61A, the gas temperature sensor 64A of the microchip 8A generates a heating resistor that generates heat at 100 ° C. The gas temperature T _{O # H = 100} of the measurement target mixed gas that is in thermal equilibrium with the body 61A is detected.

Driving circuit 303 shown in FIG. 12, as shown in FIG. 8, during time WT _1, until after giving first driving power P _{H # 1} to the heating resistor 61A, a time WT ₃ elapses, driving Stop providing power. Thereafter, the heating resistor 61A during the time WT _1, the driving circuit 303 is given to the second driving power P _{H # 2,} generates heat, for example, 0.99 ° C.. The gas temperature sensor 64A generates heat at 150 ° C. after a time WT ₂ shorter than the time WT ₁ has elapsed since the _second driving power PH _{# 2} was applied to the heating resistor 61A shown in FIGS. The gas temperature T _{O # H = 150} of the measurement target mixed gas that is in thermal equilibrium with the heating resistor 61A is detected.

Driving circuit 303 shown in FIG. 12, as shown in FIG. 8, during time WT _1, until after giving the second driving power P _{H # 2} heating resistors 61A, time WT ₃ elapses, driving Stop providing power. Thereafter, the heating resistor 61A during the time WT _1, the driving circuit 303 is given a third driving power P _{H # 3,} generates heat, for example 200 ° C.. The gas temperature sensor 64A generates heat at 200 ° C. after a time WT ₂ shorter than the time WT ₁ has elapsed since the _third driving power PH _{# 3} was applied to the heating resistor 61A shown in FIGS. The gas temperature T _{O # H = 200} of the measurement object mixed gas that is in thermal equilibrium with the heating resistor 61A is detected. Note that the reason why the driving power is intermittently applied to the heating resistor 61A is the same as in the first embodiment.

  The heat dissipation coefficient calculation module 301 shown in FIG. 12 performs the heat dissipation coefficient of the measurement target mixed gas in thermal equilibrium with the heating resistor 61A that generates heat at a heat generation temperature of 100 ° C. according to the method described in the above formulas (1) to (4). Is calculated. Further, the heat dissipation coefficient calculation module 301 is a microchip 8A that generates heat at a heat generation temperature of 200 ° C. and a heat dissipation coefficient value of a measurement target mixed gas that is in thermal equilibrium with the heating resistor of the microchip 8A that generates heat at a heat generation temperature of 150 ° C. The value of the heat dissipation coefficient of the measurement target mixed gas that is in thermal equilibrium with the heating resistor is calculated. The calorific value calculation module 305 substitutes the calculated value of the heat dissipation coefficient of the measurement target mixed gas into the independent variable of the heat dissipation coefficient of the heat generation amount calculation formula, and calculates the value of the heat generation amount of the measurement target mixed gas.

  A heat generation amount storage device 403 is further connected to the CPU 300. The calorific value storage device 403 stores the calorific value of the measurement target mixed gas calculated by the calorific value calculation module 305. The other components of the calorific value calculation system 21 according to the third embodiment are the same as those of the calorific value calculation formula creation system 20 according to the first embodiment described with reference to FIG. .

  Next, a calorific value calculation method according to the third embodiment will be described with reference to the flowchart shown in FIG. In the following example, a case where the heating resistor 61A of the microchip 8A shown in FIG. 12 generates heat at 100 ° C., 150 ° C., and 200 ° C. will be described.

(A) In step S200, the measurement target mixed gas is introduced into the chamber 101 shown in FIG. Next, in step S201, the driving circuit 303 applied to the heating resistor 61A shown in FIGS. 1 and 2 of the microchip 8A, for example, during the time WT _1, a first driving power P _{H # 1,} the heating resistor The body 61A is heated at 100 ° C. While the heating resistor 61A is generating heat at 100 ° C., the gas temperature sensor 64A detects the gas temperature T _{O # H = 100} of the measurement target mixed gas that is in thermal equilibrium with the heating resistor 61A. The illustrated heat dissipation coefficient calculation module 301 calculates the value of the heat dissipation coefficient of the measurement target mixed gas at an exothermic temperature of 100 ° C. Thereafter, the heat dissipation coefficient calculation module 301 stores the value of the heat dissipation coefficient of the measurement target mixed gas at the heat generation temperature of 100 ° C. in the heat dissipation coefficient storage device 401.

(B) In step S202, the drive circuit 303, the supply of the drive power to the heating resistor 61A, until time elapses WT _3, stops. In step S203, the drive circuit 303 shown in FIG. 12 determines whether or not the switching of the heating temperature of the heating resistor 61A shown in FIGS. 1 and 2 has been completed. When the switching to the heat generation temperature 150 ° C. and the heat generation temperature 200 ° C. is not completed, the process returns to step S201, and the drive circuit 303 shown in FIG. 12 sets the heat generation resistor 61A shown in FIGS. Causes fever. The heat dissipation coefficient calculation module 301 shown in FIG. 12 calculates the value of the heat dissipation coefficient of the measurement target mixed gas at an exothermic temperature of 150 ° C. and stores it in the heat dissipation coefficient storage device 401. Further, in step S202, the drive circuit 303, the supply of the drive power to the heating resistor 61A, until time elapses WT _3, stops.

(C) In step S203 again, it is determined whether or not switching of the heating temperature of the heating resistor 61A shown in FIGS. 1 and 2 has been completed. If the switching to the heat generation temperature of 200 ° C. has not been completed, the process returns to step S201, and the drive circuit 303 shown in FIG. 12 causes the heat generation resistor 61A shown in FIGS. The heat dissipation coefficient calculation module 301 shown in FIG. 12 calculates the value of the heat dissipation coefficient of the measurement target mixed gas at an exothermic temperature of 200 ° C. and stores it in the heat dissipation coefficient storage device 401. Further, in step S202, the drive circuit 303, the supply of the drive power to the heating resistor 61A shown in FIGS. 1 and 2, until the elapse of time WT _3, stops.

  (D) When switching of the heat generation temperature of the heat generating resistor 61A is completed, the process proceeds from step S203 to step S204. In step S204, the calorific value calculation module 305 shown in FIG. 12 reads from the formula storage device 402 a calorific value calculation formula using the heat dissipation coefficients at the heat generation temperatures of 100 ° C., 150 ° C., and 200 ° C. as independent variables. Further, the heat generation amount calculation module 305 reads the value of the heat dissipation coefficient of the measurement target mixed gas at each of the heat generation temperatures of 100 ° C., 150 ° C., and 200 ° C. from the heat dissipation coefficient storage device 401.

  (E) In step S205, the heat generation amount calculation module 305 substitutes the value of the heat dissipation coefficient of the measurement target mixed gas at each of the heat generation temperatures of 100 ° C., 150 ° C., and 200 ° C. into the independent variable of the heat generation amount calculation formula. Calculate the calorific value of the target gas mixture. Thereafter, the calorific value calculation module 305 stores the calculated calorific value in the calorific value storage device 403, and ends the calorific value calculation method according to the third embodiment.

  According to the calorific value calculation system and method according to the third embodiment described above, only by measuring the value of the heat dissipation coefficient of the measurement target mixed gas without using an expensive gas chromatography device or a sonic sensor, It is possible to measure the calorific value of the measurement target mixed gas. Further, as shown in FIG. 8, by intermittently applying driving power to the heating resistor 61A, the heat dissipation coefficient of the measurement target mixed gas can be obtained accurately and at high speed. Therefore, it is also possible to accurately and rapidly obtain the calorific value of the measurement target mixed gas.

Natural gas has a different component ratio of hydrocarbons depending on the gas field. Natural gas includes nitrogen (N ₂ ), carbon dioxide (CO ₂ ) and the like in addition to hydrocarbons. Therefore, the volume ratio of the gas component contained in the natural gas differs depending on the output gas field, and even if the type of the gas component is known, the calorific value of the natural gas is often unknown. Moreover, even if it is the natural gas derived from the same gas field, the calorific value is not always constant, and may change depending on the sampling time.

  For this reason, conventionally, when collecting the usage fee of natural gas, a method has been adopted in which charging is made according to the volume used, not the calorific value of natural gas used. However, since natural gas has a calorific value that varies depending on the production gas field from which it is derived, it is not fair to charge the volume used. On the other hand, if the calorific value calculation system and method according to the third embodiment are used, the type of gas component is known, but the natural gas with an unknown calorific value because the volume fraction of the gas component is unknown. The calorific value of the mixed gas such as can be easily calculated. Therefore, it becomes possible to collect a fair usage fee.

  In the manufacturing industry of processed glass products, it is desired that natural gas having a constant calorific value is supplied in order to keep processing accuracy constant when heat-processing glass. To do so, accurately determine the calorific value of each natural gas from multiple gas fields, adjust the calorific value of all natural gas to be the same, and then add natural gas to the glass heating process. Supply is under consideration. On the other hand, if the calorific value calculation system and method according to the third embodiment are used, it is possible to accurately grasp the calorific value of natural gas derived from a plurality of gas fields. Processing accuracy can be kept constant.

Furthermore, according to the calorific value calculation system and method according to the third embodiment, it is possible to easily know the accurate calorific value of the mixed gas such as natural gas, so that it is necessary for burning the mixed gas. It is possible to set an appropriate amount of air. Therefore, it is possible to reduce the amount of wasteful carbon dioxide (CO ₂ ) emissions.

(Example)
First, as shown in FIG. 14, 28 kinds of sample mixed gases with known calorific value values were prepared. Each of the 28 kinds of sample mixed gases includes methane (CH ₄ ), ethane (C ₂ H ₆ ), propane (C ₃ H ₈ ), butane (C ₄ H ₁₀ ), nitrogen (N ₂ ), and It contained any or all of carbon dioxide (CO ₂ ). For example, no. The sample gas mixture of 7 contained 90 vol% methane, 3 vol% ethane, 1 vol% propane, 1 vol% butane, 4 vol% nitrogen, and 1 vol% carbon dioxide. No. The sample mixed gas of 8 contained 85 vol% methane, 10 vol% ethane, 3 vol% propane, and 2 vol% butane, and did not contain nitrogen and carbon dioxide. No. Nine sample gas mixtures contained 85 vol% methane, 8 vol% ethane, 2 vol% propane, 1 vol% butane, 2 vol% nitrogen, and 2 vol% carbon dioxide. Next, the value of the heat release coefficient of each of the 28 sample mixed gases was measured at exothermic temperatures of 100 ° C., 150 ° C., and 200 ° C. For example, No. The sample mixed gas of No. 7 contains six kinds of gas components. As described above, ethane (C ₂ H ₆ ) and butane (C ₄ H ₁₀ ) are methane (CH ₄ ) and propane (C ₃ H). ₈ ) Since it can be regarded as a mixture, there is no problem even if the value of the heat dissipation coefficient is measured at three different exothermic temperatures. After that, based on the calorific value of the 28 sample mixed gases and the measured heat dissipation coefficient value, the calorific value is calculated with the heat dissipation coefficient as an independent variable and the calorific value as a dependent variable by support vector regression. A linear equation, a quadratic equation, and a cubic equation were created.

When creating a linear equation for calculating a calorific value, the calibration points can be determined as appropriate using 3 to 5 calibration points. The created linear equation was given by the following equation (23). The calorific value of 28 kinds of sample mixed gas was calculated by the equation (23), and compared with the true calorific value, the maximum error was 2.1%.
Q = 39.91-20.59 × M _I (100 ° C)-0.89 × M _I (150 ° C) + 19.73 × M _I (200 ° C) ・ ・ ・ (23)

  When creating a quadratic equation for calculating the calorific value, 8 to 9 calibration points can be determined as appropriate. The calorific value of 28 kinds of sample mixed gas was calculated by the prepared quadratic equation, and compared with the true calorific value, the maximum error was 1.2 to 1.4%.

  When creating a cubic equation for calculating the calorific value, 10 to 14 calibration points can be appropriately determined. When the calorific values of 28 kinds of sample mixed gases were calculated by the prepared cubic equation and compared with the true calorific value, the maximum error was less than 1.2%. As shown in FIGS. 15 and 16, the calorific value calculated by the cubic equation created by taking 10 calibration points is a good approximation to the true calorific value.

(Other embodiments)
As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, embodiments, and operation techniques should be apparent to those skilled in the art.

  For example, FIG. 17 shows the relationship between the heat dissipation coefficient and the thermal conductivity of the mixed gas when currents of 2 mA, 2.5 mA, and 3 mA are passed through the heating resistor. As shown in FIG. 17, the heat dissipation coefficient and thermal conductivity of the mixed gas are generally in a proportional relationship. Therefore, in the first to third embodiments, the value of the heat dissipation coefficient of the mixed gas at a plurality of heat generation temperatures of the heating resistor is used. Instead, the thermal conductivity of the mixed gas at the plurality of heat generation temperatures is used. The calorific value calculation formula may be created and the calorific value calculated.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

32A, 32B, 32C, 32D Flow control device 8A Microchip 10 Measuring mechanism 20 Heat generation amount calculation formula creation system 21 Heat generation amount calculation systems 31A, 31B, 31C, 31D Gas pressure regulators 32A, 32B, 32C, 32D Flow control device 50A , 50B, 50C, 50D Gas cylinder 60A Substrate 61A Heating resistor 62A First temperature measuring resistor element 63A Second temperature measuring resistor element 64A Gas temperature sensor 65A Insulating film 66A Cavities 91A, 91B, 91C, 91D, 92A, 92B, 92C, 92D, 102, 103 Channel 101 Chamber 161, 162, 163, 164, 165, 181, 182, 183 Resistance element 170, 171 Operational amplifier 301 Heat radiation coefficient calculation module 302 Formula creation module 303 Drive circuit 305 Heat generation amount calculation module 3 Second input device 313 output device 401 the radiation coefficient storage device 402 formula storage device 403 calorific value storage device

Claims (18)

A heating resistor;
A drive circuit that applies a plurality of different electric powers to the heating resistor and causes the heating resistor to generate heat at a plurality of different heating temperatures;
At the plurality of different heat generation temperatures, a measurement unit that measures a plurality of heat release coefficients or thermal conductivity values of a mixed gas that is in thermal equilibrium with the heat generation resistor,
Based on the known calorific value of the mixed gas and the measured plural heat dissipation coefficients or thermal conductivity values, the heat dissipation coefficient or thermal conductivity at the plural heat generation temperatures is an independent variable, and the heat generation A formula creation unit for creating a calorific value calculation formula with the quantity as a dependent variable;
With
A system for generating a calorific value calculation formula, wherein the drive circuit stops supplying power to the heat generating resistor at least once while the heat generating resistor generates heat. Further comprising a gas temperature sensor for measuring the gas temperature of the mixed gas, the calorific value calculation formula creation system according to claim 1. The measurement unit measures each value of a plurality of heat dissipation coefficients of the mixed gas by dividing each driving power of the heating resistor by a difference between each heating temperature of the heating resistor and the gas temperature, The calorific value calculation formula creation system according to claim 2 . The number of the plurality of different heating temperatures is at least the number obtained by subtracting 1 from the number of plural kinds of gas components contained in the mixed gas, the calorific value calculation according to any one of claims 1 to 3 Formula creation system. The calorific value calculation formula creation system according to any one of claims 1 to 4 , wherein the formula creation unit creates the calorific value calculation formula using support vector regression. Applying a plurality of different electric powers to the heating resistor, causing the heating resistor to generate heat at a plurality of different heating temperatures;
Measuring a plurality of heat release coefficient or thermal conductivity values of a gas mixture thermally balanced with the heating resistor at the plurality of different heating temperatures;
Based on the known calorific value of the mixed gas and the measured plural heat dissipation coefficients or thermal conductivity values, the heat dissipation coefficient or thermal conductivity at the plural heat generation temperatures is an independent variable, and the heat generation Creating a calorific value calculation formula with the amount as a dependent variable;
Including
A method for creating a calorific value calculation formula, wherein power supply to the heating resistor is stopped at least once while the heating resistor is heated. The method for creating a calorific value calculation formula according to claim 6 , further comprising measuring a gas temperature of the mixed gas. 8. The heat generation according to claim 7 , wherein each value of the plurality of heat dissipation coefficients is measured by dividing each driving power of the heating resistor by a difference between each heating temperature of the heating resistor and the gas temperature. How to create a quantity calculation formula. The calorific value calculation formula according to any one of claims 6 to 8 , wherein the number of the plurality of different heat generation temperatures is a number obtained by subtracting 1 from the number of the plurality of types of gas components contained in the mixed gas. How to create The method for creating a calorific value calculation formula according to any one of claims 6 to 9 , wherein support vector regression is used in creating the calorific value calculation formula. A heating resistor;
A drive circuit that applies a plurality of different electric powers to the heating resistor and causes the heating resistor to generate heat at a plurality of different heating temperatures;
At the plurality of different heat generation temperatures, a measurement unit that measures a plurality of heat release coefficients or values of thermal conductivity of the measurement target mixed gas that is in thermal equilibrium with the heating resistor and whose calorific value is unknown,
A formula storage device for storing a calorific value calculation formula having a plurality of heat dissipation coefficients or thermal conductivities at the plurality of exothermic temperatures as independent variables and the calorific value as a dependent variable;
Substituting the measured multiple heat release coefficients or thermal conductivity values of the measurement target mixed gas into the independent variables of the multiple heat release coefficients or thermal conductivity of the calorific value calculation formula, A calorific value calculation unit for calculating a calorific value;
With
A calorific value calculation system, wherein the drive circuit stops supplying power to the heat generating resistor at least once while the heat generating resistor generates heat. The calorific value calculation system according to claim 11 , further comprising a gas temperature sensor that measures a gas temperature of the measurement target mixed gas. The measurement unit measures each value of a plurality of heat dissipation coefficients of the measurement target mixed gas by dividing each driving power of the heating resistor by a difference between each heating temperature of the heating resistor and the gas temperature. The calorific value calculation system according to claim 12 . The heat generation according to any one of claims 11 to 13 , wherein the number of the plurality of different heat generation temperatures is a number obtained by subtracting 1 from the number of the plurality of types of gas components included in the measurement target mixed gas. Quantity calculation system. Applying a plurality of different electric powers to the heating resistor, causing the heating resistor to generate heat at a plurality of different heating temperatures;
At a plurality of different heat generation temperatures, measuring a plurality of heat dissipation coefficients or values of thermal conductivity of a measurement target mixed gas that is in thermal equilibrium with the heating resistor and whose calorific value is unknown;
Preparing a calorific value calculation formula with a plurality of heat release coefficients or thermal conductivities at the plurality of heat generation temperatures as independent variables and the calorific value as a dependent variable;
Substituting the measured multiple heat release coefficients or thermal conductivity values of the measurement target mixed gas into the independent variables of the multiple heat release coefficients or thermal conductivity of the calorific value calculation formula, Calculating the calorific value,
Including
A method for calculating the amount of heat generation, characterized in that the supply of electric power to the heating resistor is stopped at least once while the heating resistor is heated. The calorific value calculation method according to claim 15 , further comprising measuring a gas temperature of the measurement target mixed gas. Each value of the plurality of heat dissipation coefficients of the measurement target mixed gas is measured by dividing each driving power of the heating resistor by a difference between each heating temperature of the heating resistor and the gas temperature. The calorific value calculation method according to 16 . Heating the number of the plurality of different heating temperatures, at least, the a number obtained by subtracting 1 from the number of plural kinds of gas components contained in the mixed gas being measured, according to any one of claims 15 to 17 How to calculate the quantity.

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