WO2024034488A1 - ガス測定装置、および対象成分の濃度を求める方法 - Google Patents

ガス測定装置、および対象成分の濃度を求める方法 Download PDF

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Publication number
WO2024034488A1
WO2024034488A1 PCT/JP2023/028262 JP2023028262W WO2024034488A1 WO 2024034488 A1 WO2024034488 A1 WO 2024034488A1 JP 2023028262 W JP2023028262 W JP 2023028262W WO 2024034488 A1 WO2024034488 A1 WO 2024034488A1
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gas
component
concentration
measurement
components
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English (en)
French (fr)
Japanese (ja)
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克彦 荒谷
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Shimadzu Corp
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Shimadzu Corp
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Priority to JP2024540416A priority Critical patent/JPWO2024034488A1/ja
Priority to CN202380058162.8A priority patent/CN119654547A/zh
Publication of WO2024034488A1 publication Critical patent/WO2024034488A1/ja
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis

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  • the present disclosure relates to a gas measurement device that measures a sample gas containing a plurality of gas components whose absorption wavelength ranges overlap at least in part with each other, and a method for determining the concentration of a target component among the plurality of gas components.
  • Non-dispersive infrared absorption is used as a device to determine the concentration of target components in sample gases such as gases emitted from chemical factories and steel plants, combustion gases from boilers and combustion furnaces, the atmosphere, and automobile exhaust gas.
  • sample gases such as gases emitted from chemical factories and steel plants, combustion gases from boilers and combustion furnaces, the atmosphere, and automobile exhaust gas.
  • Infrared gas analyzers are known.
  • a gas measuring device such as an infrared gas analyzer that utilizes the light absorption characteristics of a target component
  • errors occur in the measurement of the target component due to the influence of components other than the target component in the sample gas.
  • an interference component having an absorption wavelength range that at least partially overlaps with the absorption wavelength range of the target component is present in the sample gas, an error occurs in the measurement of the target component due to the influence of the interference component.
  • Patent Document 1 discloses that in order to measure the concentration of dinitrogen monoxide, dinitrogen monoxide and carbon dioxide, which is an interference component to dinitrogen monoxide, are measured by infrared absorption analysis, and the measurement results of carbon dioxide are analyzed. A measurement method is disclosed in which the measurement results of dinitrogen monoxide are corrected using the method.
  • Patent Document 2 discloses an analyzer in which an optical filter is arranged between a light source and a detector to cut the absorption wavelength range of interference components.
  • Patent Document 3 discloses that an interference component detector and a measurement component detector are optically arranged in series in this order from the other end of the cell, and a detection signal obtained from the detector is used to perform correction calculations on the measurement component. Disclosed.
  • Patent No. 2952855 Utility Model Publication No. 5-75654 JP2012-68164A
  • Patent Documents 1 to 3 in a gas measuring device that utilizes the infrared absorption characteristics of a target component, it is required to determine the concentration of the target component while taking into account the influence of interference components.
  • Patent Documents 1 to 3 disclose that the concentration of the target component is determined taking into account that the measurement of the target component is affected by interference components; was not considered.
  • One objective of the present disclosure is to more accurately determine the concentration of a target component contained in a sample gas, taking into account that the measurement of an interfering component is influenced by other components.
  • the gas measuring device of the present disclosure measures a sample gas that includes a plurality of gas components whose absorption wavelength ranges overlap at least partially with each other.
  • the gas measurement device includes a detection unit that detects the amount of light in the absorption wavelength range of each of a plurality of gas components by detecting light that has passed through a sample gas, and a detection unit that detects the amount of light in the absorption wavelength range of each of the plurality of gas components. and an arithmetic unit that calculates the concentration of the target component among the plurality of gas components based on the value.
  • a gas component having an absorption wavelength range that at least partially overlaps with an absorption wavelength range of one of the gas components is an interference component with respect to the one gas component.
  • the concentration of each of the plurality of gas components is the concentration after correction, which is obtained by subtracting the measurement error caused by one or more interference components to the measurement of the gas component from the concentration before correction corresponding to the detected value of the gas component. It is expressed as The measurement error caused in the measurement of a gas component is expressed by the linear sum of the corrected concentration of the interference component with respect to the gas component and the influence coefficient indicating the degree of influence of the interference component on the measurement of the gas component.
  • the calculation unit calculates the corrected value of the target component based on the plurality of influence coefficients and the detected value of each of the plurality of gas components, according to the relationship between the concentration after correction and the concentration before correction for each of the plurality of gas components. The concentration is determined as the concentration of the target component.
  • the method of the present disclosure is a method for determining the concentration of a target component in a sample gas that includes a plurality of gas components whose absorption wavelength ranges overlap at least in part with each other.
  • the method includes the step of detecting the light amount in the absorption wavelength range of each of the plurality of gas components by detecting the light that has passed through the sample gas, and obtaining a detected value for each of the plurality of gas components. and a step of determining the concentration of a target component among the plurality of gas components based on the obtained detected values of each of the plurality of gas components.
  • a gas component having an absorption wavelength range that at least partially overlaps with an absorption wavelength range of one of the gas components is an interference component with respect to the one gas component.
  • the concentration of each of the plurality of gas components is the concentration after correction, which is obtained by subtracting the measurement error caused by one or more interference components to the measurement of the gas component from the concentration before correction corresponding to the detected value of the gas component. It is expressed as The measurement error caused in the measurement of a gas component is expressed by the linear sum of the corrected concentration of the interference component with respect to the gas component and the influence coefficient indicating the degree of influence of the interference component on the measurement of the gas component.
  • the corrected concentration of the target component is determined as the concentration of the target component.
  • the corrected concentration of the target component is expressed using the corrected concentration obtained by subtracting the measurement error given to the measurement of the interference component from the uncorrected concentration of the interference component with respect to the target component. Further, the concentration of the target component is determined according to the relationship between the corrected concentration of the target component and the corrected concentration of the interference component. Therefore, it is possible to more accurately determine the concentration of the target component, taking into account that the measurement of the interference component is influenced by other components.
  • FIG. 2 is a schematic diagram showing a method for determining the concentration of a target component in a gas measuring device.
  • FIG. 2 is a schematic diagram showing a method for determining an influence coefficient in a gas measuring device.
  • FIG. 1 is a diagram showing the configuration of a gas measuring device.
  • FIG. 3 is a functional block diagram of a control unit. 3 is a flowchart showing the processing of the control unit during sample gas measurement. 5 is a flowchart showing processing of a control unit when calculating an influence coefficient.
  • This is an infrared absorption spectrum of dinitrogen monoxide and carbon dioxide. Infrared absorption spectra of dinitrogen monoxide, methane, and sulfur dioxide.
  • FIG. 1 is a schematic diagram showing a method for determining the concentration of a target component in a gas measuring device.
  • FIG. 2 is a schematic diagram showing a method for determining an influence coefficient in a gas measuring device.
  • the gas measuring device 1a includes a detection unit 100a and a calculation unit 200a.
  • the detection unit 100a detects the amount of light in the absorption wavelength range of each of the plurality of gas components contained in the sample gas by detecting the transmitted light that has passed through the sample gas.
  • the detection unit 100a sends the detection result to the calculation unit 200a.
  • the calculation unit 200a is a calculation device that calculates the concentration of the component in the sample gas based on the detection result.
  • Each of the plurality of gas components has a unique absorption wavelength range. A portion of the transmitted light is absorbed and attenuated by each of the plurality of gas components contained in the sample gas. Absorbance, which is the degree to which light is absorbed, is proportional to the concentration of the gas component. Therefore, the concentration of the gas component can be determined from the absorbance.
  • the gas component to be measured may be referred to as "target component”.
  • a gas component having an absorption wavelength range that at least partially overlaps with the absorption wavelength range of one gas component may be referred to as an "interference component with respect to one gas component” or simply “an interference component.”
  • an interference component with respect to one gas component or simply “an interference component.”
  • a detection result obtained by detecting the amount of light in the absorption wavelength range of one gas component may be referred to as a "detection value of one gas component” or simply a “detection value.”
  • the sample gas contains a target component and an interference component with respect to the target component.
  • the detected value of the target component obtained by measuring the sample gas reflects not only the effect of light being absorbed by the target component but also the influence of light being absorbed by the interference component. Therefore, even if absorbance in the absorption wavelength range of the target component is detected, an error occurs in measuring the concentration of the target component due to the influence of interference components.
  • the gas measuring device 1a detects a target component and an interference component with respect to the target component, and corrects the detected value of the target component using the detected value of the interference component. Find the concentration.
  • the detection unit 100a includes a first detector 10a that detects the amount of light in the absorption wavelength range of component M, a second detector 10b that detects the amount of light in the absorption wavelength range of component C1, and a second detector 10b that detects the amount of light in the absorption wavelength range of component C2. and a third detector 10c for detection.
  • the method of detecting the amount of light is not particularly limited.
  • the amount of light may be directly detected using a photoconductive element, or the amount of light may be detected indirectly by changes in internal pressure when transmitted light passes through a cell filled with a gas to be detected. Good too.
  • the calculation unit 200a determines the concentration of the component M based on the detected values of each gas component sent from the detection unit 100a.
  • the arithmetic unit 200a uses the detected value of the component M sent from the first detector 10a, the detected value of the component C1 and the detected value of the component C2 sent from the second detector 10b and the third detector 10c, respectively.
  • the concentration [M] of component M is determined. Note that, in the following, for a certain component A, the density before correction corresponding to the detected value is expressed as A, and the density after correction is expressed as [A]. [M] is determined according to equation (1).
  • [C1] is determined according to equation (2).
  • [C2] is determined according to equation (3). Note that the concentration before correction corresponding to the detected value obtained from one detector is calculated based on the detected value obtained from the first detector, without using the detected value obtained from other detectors. concentration.
  • a and b are influence coefficients indicating the degree of influence of component C1 and component C2 on the measurement of component M, respectively.
  • c and d are influence coefficients indicating the degree of influence of component M and component C2 on the measurement of component C1, respectively.
  • e and f are influence coefficients indicating the degree of influence of component M and component C1 on the measurement of component C2, respectively.
  • the concentration of each of a plurality of gas components in a sample gas is determined by the measurement error caused by one or more interference components to the gas component in the measurement of the gas component. It is expressed as the post-correction concentration subtracted from the pre-correction concentration corresponding to the detected value of the gas component.
  • the measurement error caused in the measurement of the gas component is expressed by the linear sum of the corrected concentration of the interference component with respect to the gas component and the influence coefficient indicating the degree of influence of the interference component on the measurement of the gas component.
  • the arithmetic unit 200a calculates the detected values of each of the plurality of gas components and the plurality of influence coefficients a to f according to the relationship between the concentration after correction and the concentration before correction shown in equations (1) to (3) above. Based on this, the corrected density of component M is determined as the density of component M [M].
  • the calculation unit 200a calculates the concentration [M] as follows.
  • [M] can be calculated as the concentration before correction (M, C1, and C2) corresponding to the detected value, as shown in equation (4) below.
  • m 1 to m 3 are intermediate coefficients expressed using influence coefficients a to f, respectively, and are expressed by equations (5) to (7).
  • k in equations (5) to (7) is expressed by equation (8).
  • a' is a-bf
  • b' is b-ad
  • c' is c-de
  • d' is d-bc
  • e' is e-cf
  • f' is f-ae.
  • [M] can be expressed by M, C1, and C2, which are the uncorrected densities corresponding to the detected values, and intermediate coefficients m 1 to m 3 .
  • the concentration [M] of the component M is determined based on the detected value and the intermediate coefficient sent from the detection unit 100a.
  • each of the concentration [C1] and the concentration [C2] can be expressed by M, C1, and C2 corresponding to the detected values and an intermediate coefficient. Therefore, similarly to the concentration [M], the calculation unit 200a can also determine the concentration [C1] and the concentration [C2] based on the detected value and intermediate coefficient sent from the detection unit 100a.
  • the method for determining the concentration according to a plurality of relational expressions is not limited to the method described above.
  • the calculation unit 200a may perform calculations using influence coefficients without using intermediate coefficients.
  • the corrected concentration of the target component is expressed using the corrected concentration obtained by subtracting the measurement error given to the measurement of the interference component from the uncorrected concentration of the interference component with respect to the target component. Further, the concentration of the target component is determined according to the relationship between the corrected concentration of the target component and the corrected concentration of the interference component. Therefore, it is possible to more accurately determine the concentration of the target component, taking into account that the measurement of the interference component is influenced by other components.
  • the gas measuring device 1a detects a plurality of detected values obtained by detecting the amount of light in the absorption wavelength range of each of a plurality of gas components according to the relationship between the concentration after correction and the concentration before correction.
  • the concentration of the target component can be determined based on the influence coefficient of .
  • each influence coefficient a to f is determined as follows.
  • the standard gas consisting of the first component does not need to contain any interference components (for example, the second component) with respect to the first component, and may, for example, contain a gas such as nitrogen that does not affect the measurement of the first component. Also good.
  • the detection unit 100a detects a first standard gas containing the component M at a concentration x and not containing the components C1 and C2 with the second detector 10b and the third detector 10c, and detects the detected value of the component C1. , and the detected value of component C2.
  • the calculation unit 200a calculates the influence coefficient c from the concentration x and the uncorrected concentration of the component C1 corresponding to the detected value of the component C1 detected by the second detector 10b, according to equation (2).
  • the calculation unit 200a calculates the influence coefficient e from the concentration x and the uncorrected concentration of the component C2 corresponding to the detected value of the component C2 detected by the third detector 10c, according to equation (3).
  • the detection unit 100a detects a second standard gas containing the component C1 at a concentration y and not containing the component M and the component C2 with each of the first detector 10a and the third detector 10c, and detects the detected value of the component M. , and the detected value of component C2.
  • the calculation unit 200a calculates the influence coefficient a from the concentration y and the uncorrected concentration of the component M corresponding to the detected value of the component M detected by the first detector 10a, according to equation (1).
  • the calculation unit 200a calculates the influence coefficient f from the concentration y and the uncorrected concentration of the component C2 corresponding to the detected value of the component C2 detected by the third detector 10c, according to equation (3).
  • the detection unit 100a detects a third standard gas containing the component C2 at a concentration z and not containing the component M and the component C1 with each of the first detector 10a and the second detector 10b, and detects the detected value of the component M. , and the detected value of component C1.
  • the calculation unit 200a calculates the influence coefficient b from the concentration z and the uncorrected concentration of the component M corresponding to the detection value of the component M detected by the first detector 10a, according to equation (1).
  • the calculation unit 200a calculates the influence coefficient d from the concentration z and the uncorrected concentration of the component C1 corresponding to the detected value of the component C1 detected by the second detector 10b, according to equation (2).
  • the calculation unit 200a stores the influence coefficients a to f determined as above, and refers to them when measuring the sample gas to determine the concentration of the target component. Note that the calculation unit 200a may calculate and store intermediate coefficients in addition to or instead of the influence coefficients a to f.
  • influence coefficients a to f are calculated based on actual measurement values, influence coefficients can be obtained that take into account individual differences among gas measuring devices.
  • the influence coefficients a to f may be determined by the manufacturer or the like before shipping the gas measuring device 1a to the user, or may be determined by the user after shipping the gas measuring device 1a.
  • FIG. 3 is a diagram showing the configuration of the gas measuring device.
  • the gas measuring device 1 measures exhaust gas as a sample gas and determines the concentration of dinitrogen monoxide (N 2 O) as a target component. Further, the gas measurement device 1 detects the amount of light in the absorption wavelength range of each of sulfur dioxide (SO 2 ), methane (CH 4 ), and carbon dioxide (CO 2 ) as interference components of dinitrogen monoxide. The gas measuring device 1 calculates the concentration of dinitrogen monoxide by correcting the detected value of dinitrogen monoxide using the detected values of sulfur dioxide, methane, and carbon dioxide.
  • exhaust gas specifically includes gas discharged from chemical factories and steel mills, combustion gas from boilers and combustion furnaces, and automobile exhaust gas. Further, the sample gas is not limited to exhaust gas, and may be, for example, the atmosphere.
  • the gas measuring device 1 includes a detection unit 100, a control unit 200, an input section 300, and a display section 400.
  • the detection unit 100 detects the amount of light in the absorption wavelength range of each of the plurality of gas components in the sample gas. More specifically, the detection unit 100 detects the amount of light in the respective absorption wavelength ranges of dinitrogen monoxide, sulfur dioxide, methane, and carbon dioxide.
  • the control unit 200 controls the detection unit 100. Further, the control unit 200 functions as an arithmetic device that calculates the concentration of dinitrogen monoxide based on the detection values of each of the plurality of gas components detected by the detection unit 100.
  • the control unit 200 includes a processor 220, a memory 240, and an input/output interface (not shown) for inputting and outputting various signals.
  • the memory 240 includes, for example, ROM (Read Only Memory) and RAM (Random Access Memory).
  • the processor 220 expands the program stored in the ROM into a RAM or the like and executes the program.
  • the program stored in the ROM is a program in which the processing procedure of the control unit 200 is written.
  • the ROM stores various coefficients and various relational expressions used to determine the concentration of dinitrogen monoxide.
  • Control unit 200 executes various processes for determining the concentration of dinitrogen monoxide according to these programs, various coefficients, and various relational expressions.
  • the processing is not limited to software, but can also be executed by dedicated hardware (electronic circuit).
  • the input unit 300 is a device that receives user operations such as a mouse or a keyboard.
  • the input unit 300 receives an input of the concentration of a gas component in the standard gas, and sends it to the control unit 200.
  • the display unit 400 is a display device such as a liquid crystal panel, and displays, for example, the concentration of dinitrogen monoxide determined by the control unit 200.
  • the detection unit 100 includes a measurement gas line SL, a reference gas line RL, two switching valves 112 and 114, a first detection unit 120, a second detection unit 140, and a motor 160. , sector 180.
  • a measurement gas SG is introduced into the measurement gas line SL.
  • the measurement gas SG is a gas to be measured in the detection unit 100, and includes a sample gas and a standard gas used in preparation for measurement of the sample gas.
  • a reference gas RG is introduced into the reference gas line RL.
  • the reference gas RG is a so-called zero gas, which is an inert gas such as nitrogen that does not absorb infrared rays.
  • the reference gas RG may be any gas that does not interfere with any of the gas components measured in the detection unit 100, and may be a gas that has infrared absorption.
  • the switching valve 112 is connected to the measurement gas line SL, the first line L1, and the third line L3.
  • the switching valve 114 is connected to the reference gas line RL, the second line L2, and the fourth line L4.
  • the first line L1 is connected to the first detection unit 120.
  • the second line L2 is connected to the second detection unit 140.
  • the third line L3 is connected to the second line L2.
  • the fourth line L4 is connected to the first line L1.
  • the switching valve 112 is connected to the measurement gas line SL, the flow path connected to the first sample cell 122, and the flow path connected to the second sample cell 142.
  • the switching valve 114 is connected to the reference gas line RL, a flow path connected to the first sample cell 122, and a flow path connected to the second sample cell 142.
  • the control unit 200 switches the flow path connected to the measurement gas line SL to the flow path connected to the first detection unit 120 or the flow path connected to the second detection unit 140 at a predetermined period. , controls the switching valve 112.
  • the control unit 200 controls the switching valves 112 and 114 so that the reference gas line RL and the second sample cell 142 are connected while the measurement gas line SL and the first detection unit 120 are connected.
  • the control unit 200 also controls the switching valves 112 and 114 so that the reference gas line RL and the first sample cell 122 are connected while the measurement gas line SL and the second sample cell 142 are connected. do.
  • each of the first detection unit 120 and the second detection unit 140 is filled with the reference gas and the sample gas alternately. More specifically, while the first detection unit 120 is filled with the reference gas, the second detection unit 140 is filled with the sample gas, and while the first detection unit 120 is filled with the sample gas, The second detection unit 140 will be filled with the reference gas.
  • the motor 160 rotates the sector 180 according to instructions from the control unit 200.
  • the sector 180 is provided between a first sample cell 122 and a first light source 124, which will be described later, and between a second sample cell 142 and a second light source 144.
  • the sector 180 has a light blocking part and a light transmitting part, and performs irradiation of light from the first light source 124 to the first sample cell 122 and blocking of the irradiation. Further, the sector 180 irradiates light from the second light source 144 to the second sample cell 142 and blocks the irradiation.
  • the first detection unit 120 detects the amount of light in the absorption wavelength range of the target component, which is the main objective, in measuring gas components using the gas measuring device 1.
  • the first detection unit 120 includes a first sample cell 122, a first light source 124, a first detector 10A that detects the amount of light in the absorption wavelength range of dinitrogen monoxide, an optical filter 20, and a first gas filter 30. Equipped with.
  • the first sample cell 122, the first gas filter 30, the optical filter 20, and the first detector 10A are each arranged in this order on the first optical path IR1 of the first light source 124.
  • the second detection unit 140 detects the amount of light in the absorption wavelength range of interference components with respect to the main target component.
  • the second detection unit 140 includes a second light source 144, a second sample cell 142, a second gas filter 40, a second detector 10B that detects the amount of light in the sulfur dioxide absorption wavelength range, and a methane absorption wavelength range. and a fourth detector 10D that detects the amount of light in the absorption wavelength range of carbon dioxide.
  • the second sample cell 142, the second gas filter 40, the second detector 10B, the third detector 10C, and the fourth detector 10D are arranged on the second optical path IR2 of the second light source 144 in this order, respectively. Ru.
  • the first detector 10A that detects dinitrogen monoxide is placed on the first optical path IR1, which is different from the second optical path IR2 where the detector that detects the interference component of dinitrogen monoxide is placed. has been done. Therefore, it is possible to suppress the attenuation of light and suppress the decrease in detection sensitivity of dinitrogen monoxide. Further, a plurality of detectors (second detector 10B, third detector 10C, and fourth detector 10D) that detect interference components of dinitrogen monoxide are arranged in series on the second optical path IR2. Therefore, the overall size of the gas measuring device 1 can be suppressed.
  • the first detection unit 120 detects the amount of light in the absorption wavelength range of the target component, which is the main objective, in measuring gas components using the gas measurement device 1 . In this embodiment, the first detection unit 120 detects the amount of light in the absorption wavelength range of dinitrogen monoxide.
  • the first detection unit 120 includes a first sample cell 122, a first light source 124, a first detector 10A, an optical filter 20, and a first gas filter 30.
  • the first light source 124 emits light that includes at least the absorption wavelength range of the target component.
  • the first light source 124 is not particularly limited, and is, for example, a light source using a nichrome wire.
  • the first sample cell 122, the first gas filter 30, the optical filter 20, and the first detector 10A are each arranged in this order on the first optical path IR1 of the first light source 124. Although not shown, there are windows on the first optical path IR1 at both ends of each of the first sample cell 122, the first gas filter 30, and the optical filter 20 through which the light from the first light source 124 passes. It is formed. As a result, the light from the first light source 124 passes through the first sample cell 122, the first gas filter 30, the optical filter 20, and the first detector 10A in this order.
  • the first sample cell 122 is hollow inside and includes a gas inlet 122a and a gas outlet 122b.
  • the measurement gas SG or the reference gas RG is supplied into the first sample cell 122 from the first line L1 through the gas inlet 122a, and is discharged from the gas outlet 122b.
  • the first detector 10A detects the amount of light in the absorption wavelength range of dinitrogen monoxide.
  • the first detector 10A includes a first housing 12A filled with dinitrogen monoxide as a gas component, and a first detection section 14A that detects the pressure inside the first housing 12A.
  • the first detector 10A indirectly detects the amount of light in the absorption wavelength range specific to dinitrogen monoxide by detecting pressure changes within the first housing 12A.
  • the first detector 10A detects the light from the first light source 124 that has passed through the first sample cell 122, the first gas filter 30, and the optical filter 20 in this order.
  • the optical filter 20 allows light in a specific absorption wavelength range to pass through, while preventing light in a specific absorption wavelength range from passing through.
  • dinitrogen monoxide has a first absorption wavelength range (absorption wavelength range around 7.8 ⁇ m) and a second absorption wavelength range (absorption wavelength around 4.5 ⁇ m). area).
  • the optical filter 20 does not transmit light in a second absorption wavelength range that overlaps with the absorption wavelength range of carbon dioxide, while transmitting light in a first absorption wavelength range.
  • the optical filter 20 does not transmit light with a wavelength of 5.5 ⁇ m to 6.5 ⁇ m or less, but transmits light with a wavelength longer than 5.5 ⁇ m to 6.5 ⁇ m.
  • the first gas filter 30 is filled with a gas that is an interference component having an absorption wavelength range that at least partially overlaps with the first absorption wavelength range among the absorption wavelength ranges of dinitrogen monoxide.
  • the first gas filter 30 is filled with methane as a gas component.
  • the arrangement order of the optical filter 20 and the first gas filter 30 may be reversed. Specifically, the first sample cell 122, the optical filter 20, the first gas filter 30, and the first detector 10A may be arranged on the first optical path IR1 in this order.
  • the second detection unit 140 detects the amount of light in the absorption wavelength range of the interference component with respect to the main target component in the measurement of gas components using the gas measuring device 1 .
  • the second detection unit 140 includes a second light source 144, a second sample cell 142, a second gas filter 40, a second detector 10B, a third detector 10C, and a fourth detector. It is equipped with a container 10D.
  • the second light source 144 and the second sample cell 142 are common to the first light source 124 and the first sample cell 122 of the first detection unit 120, respectively.
  • the measurement gas SG or the reference gas RG is supplied into the second sample cell 142 from the second line L2 through the gas inlet 142a of the second sample cell 142, and is discharged from the gas outlet 142b. .
  • the second sample cell 142, the second gas filter 40, the second detector 10B, the third detector 10C, and the fourth detector 10D are arranged on the second optical path IR2 of the second light source 144 in this order, respectively. Ru.
  • a second light source 144 is provided on the second optical path IR2 at both ends of each of the second sample cell 142, second gas filter 40, second detector 10B, and third detector 10C.
  • a window is formed that allows light to pass through. Light from the second light source 144 passes through the second sample cell 142, the second gas filter 40, the second detector 10B, the third detector 10C, and the fourth detector 10D in this order.
  • the second detector 10B detects the amount of light in the absorption wavelength range of sulfur dioxide.
  • the second detector 10B includes a second housing 12B filled with sulfur dioxide as a gas component, and a second detection section 14B that detects the pressure inside the second housing 12B.
  • the second detector 10B indirectly detects the amount of light in the absorption wavelength range specific to sulfur dioxide by detecting pressure changes within the second housing 12B. Note that the second detector 10B detects the light from the second light source 144 that has passed through the second sample cell 142 and the second gas filter 40 in that order.
  • the third detector 10C detects the amount of light in the methane absorption wavelength range.
  • the third detector 10C includes a third housing 12C filled with methane as a gas component, and a third detection section 14C that detects the pressure inside the third housing 12C.
  • the third detector 10C indirectly detects the amount of light in the absorption wavelength range specific to methane by detecting pressure changes within the third housing 12C. Note that the third detector 10C detects the light from the second light source 144 that has passed through the second sample cell 142, the second gas filter 40, and the second detector 10B in this order.
  • the fourth detector 10D detects the amount of light in the absorption wavelength range of carbon dioxide.
  • the fourth detector 10D includes a fourth housing 12D filled with carbon dioxide as a gas component, and a fourth detection section 14D that detects the pressure inside the fourth housing 12D.
  • the fourth detector 10D indirectly detects the amount of light in the absorption wavelength range specific to carbon dioxide by detecting the pressure change within the fourth housing 12D. Note that the fourth detector 10D detects the light from the second light source 144 that has passed through the second sample cell 142, the second gas filter 40, the second detector 10B, and the third detector 10C in this order.
  • the second gas filter 40 is filled with carbon dioxide.
  • the second gas filter 40 reduces the influence of carbon dioxide on the measurement of sulfur dioxide and methane by reducing the amount of light in the absorption wavelength range of carbon dioxide among the absorption wavelength ranges of sulfur dioxide and methane.
  • FIG. 4 is a functional block diagram of the control unit.
  • the control unit 200 includes a pre-correction density calculation section 222, a correction value calculation section 224, a coefficient calculation section 226, and a storage section 228. Each function shown in FIG. 4 is realized by the processor 220 executing a program.
  • Storage unit 228 corresponds to memory 240.
  • the pre-correction concentration calculation unit 222 converts the detection signal (reference signal) when the reference gas is sent to the detection unit 100 and the detection signal (measurement signal) when the sample gas is sent to the detection unit 100 into a predetermined value. By applying the calculation formula, the concentration of the gas component in the sample gas is determined. That is, the reference signal and the measurement signal correspond to "detected values.”
  • the pre-correction concentration calculation unit 222 calculates the pre-correction concentration of dinitrogen monoxide based on the reference signal and measurement signal detected by the first detector 10A. Similarly, the pre-correction concentration calculation unit 222 calculates the pre-correction concentration of sulfur dioxide based on the reference signal and measurement signal detected by the second detector 10B, and calculates the pre-correction concentration of sulfur dioxide based on the reference signal and measurement signal detected by the third detector 10C. The pre-correction concentration of methane is determined based on the above, and the pre-correction concentration of carbon dioxide is determined based on the reference signal and measurement signal detected by the fourth detector 10D.
  • the pre-correction concentration calculation unit 222 uses the reference gas, but the concentration may be calculated based on the measurement signal without using the reference gas. Further, the gas measuring device 1 may obtain the reference signal by using a reference cell filled with the reference gas and sealed, instead of passing the reference gas.
  • the correction value calculation unit 224 corrects the detected value of dinitrogen monoxide obtained by the detection unit 100 using the detected values of carbon dioxide, methane, and sulfur dioxide, which interfere with the measurement of dinitrogen monoxide. Find the concentration of dinitrogen.
  • the concentration of each gas component is determined according to the following equations (9) to (12). Note that for a certain component A, the concentration before correction corresponding to the detected value is expressed as A, and the concentration after correction is expressed as [A].
  • a, b, and g are influence coefficients indicating the degree of influence of dinitrogen monoxide, sulfur dioxide, and carbon dioxide on the measurement of methane, respectively.
  • c, d, and h are influence coefficients indicating the degree of influence of methane, sulfur dioxide, and carbon dioxide on the measurement of dinitrogen monoxide, respectively.
  • e, f, and i are influence coefficients indicating the degree of influence of methane, dinitrogen monoxide, and carbon dioxide on the measurement of sulfur dioxide, respectively.
  • the concentration of each of a plurality of gas components in a sample gas is determined by the measurement error caused by one or more interference components to the gas component in the measurement of the gas component. It is expressed as the post-correction concentration subtracted from the pre-correction concentration corresponding to the detected value of the gas component.
  • the measurement error caused in the measurement of the gas component is expressed by the linear sum of the corrected concentration of the interference component with respect to the gas component and the influence coefficient indicating the degree of influence of the interference component on the measurement of the gas component.
  • the sample gas is exhaust gas.
  • the carbon dioxide concentration in the exhaust gas is 100 times or more higher than the concentrations of other components (dinitrogen monoxide, sulfur dioxide, and methane).
  • concentration of carbon dioxide is extremely high compared to other components (dinitrogen monoxide, sulfur dioxide, and methane)
  • other components cannot be measured in the measurement of carbon dioxide, as shown in equation (12). It is assumed that there will be no impact.
  • the correction value calculation unit 224 calculates the concentration of dinitrogen monoxide based on the influence coefficient and the pre-correction concentration of the gas component corresponding to each detected value, according to the relationships expressed by equations (9) to (12). Specifically, by solving the simultaneous equations of equations (9) to (12), the concentration of dinitrogen monoxide can be calculated as the concentration before correction (N 2 O, CH 4 , SO 2 , CO 2 ) and an intermediate coefficient expressed using a plurality of influence coefficients. Therefore, the correction value calculation unit 224 can calculate the concentration of dinitrogen monoxide based on the influence coefficient or intermediate coefficient and the pre-correction concentration of the gas component corresponding to each detected value. Note that the method for determining the concentration according to the relationships in equations (9) to (12) is not limited to this method. For example, the correction value calculation unit 224 may perform calculations using influence coefficients without using intermediate coefficients.
  • the coefficient calculation unit 226 calculates an influence coefficient based on the detected value obtained by detecting a standard gas whose concentration is known and the concentration of the standard gas input from the input unit 300. Specifically, the influence coefficients a to i in equations (9) to (11) are determined as follows.
  • the detection unit 100 detects a standard gas consisting of dinitrogen monoxide with a known concentration using each of the second detector 10B and the third detector 10C. Based on the plurality of detected values thus obtained and the known concentration, the influence coefficients a and f in equations (9) and (11) are determined.
  • control unit 200 divides the uncorrected concentration of methane corresponding to the detected value of the third detector 10C by the input concentration of dinitrogen monoxide according to the relationship of equation (9). , determine the influence coefficient a.
  • the control unit 200 calculates the influence coefficient f by dividing the concentration before correction of sulfur dioxide corresponding to the detected value of the second detector 10B by the input concentration of nitrous oxide according to the relationship of equation (11). seek.
  • the detection unit 100 detects a standard gas consisting of sulfur dioxide with a known concentration using each of the first detector 10A and the third detector 10C.
  • the influence coefficients b and d in equations (9) and (10) are determined based on the plurality of detected values obtained thereby and the known concentrations.
  • control unit 200 calculates the influence by dividing the concentration before correction of methane corresponding to the detected value of the third detector 10C by the input concentration of sulfur dioxide according to the relationship of equation (9). Find the coefficient b.
  • the control unit 200 calculates the influence coefficient d by dividing the uncorrected concentration of dinitrogen monoxide corresponding to the detected value of the first detector 10A by the input concentration of sulfur dioxide according to the relationship of equation (10). seek.
  • the detection unit 100 detects a standard gas consisting of methane with a known concentration using each of the first detector 10A and the second detector 10B. Based on the plurality of detected values thus obtained and the known concentration, the influence coefficients c and e in equations (10) and (11) are determined.
  • control unit 200 divides the uncorrected concentration of dinitrogen monoxide corresponding to the detected value of the first detector 10A by the input concentration of methane, according to the relationship of equation (10). , determine the influence coefficient c.
  • the control unit 200 calculates the influence coefficient e by dividing the uncorrected concentration of sulfur dioxide corresponding to the detected value of the second detector 10B by the input concentration of methane, according to the relationship of equation (11).
  • the detection unit 100 detects a standard gas consisting of carbon dioxide with a known concentration using each of the first detector 10A, the second detector 10B, and the third detector.
  • the influence coefficients g, h, and i in equations (9) to (11) are determined based on the plurality of detected values obtained thereby and the known concentration.
  • control unit 200 divides the uncorrected concentration of methane corresponding to the detected value of the third detector 10C by the input carbon dioxide concentration according to the relationship of equation (9), and calculates the influence coefficient.
  • Find g. The control unit 200 calculates the influence coefficient h by dividing the uncorrected concentration of dinitrogen monoxide corresponding to the detected value of the first detector 10A by the input concentration of carbon dioxide according to the relationship of equation (10).
  • the control unit 200 calculates the influence coefficient i by dividing the uncorrected concentration of sulfur dioxide corresponding to the detected value of the second detector 10B by the input concentration of carbon dioxide according to the relationship of equation (11). .
  • the coefficient calculation unit 226 stores each of the determined influence coefficients a to i in the storage unit 228. Note that the coefficient calculation unit 226 may calculate an intermediate coefficient from each of the determined influence coefficients a to i, and store at least one of the influence coefficient and the intermediate coefficient in the storage unit 228. Note that the coefficient calculation unit 226 may calculate only intermediate coefficients without calculating the influence coefficient, and store the calculated intermediate coefficients in the storage unit 228.
  • FIG. 5 is a flowchart showing the processing of the control unit during sample gas measurement.
  • a step is abbreviated as "S”.
  • the control unit 200 detects the amount of light in the absorption wavelength range of each of the plurality of gas components by detecting the light that has passed through the sample gas, and detects the detected value of each of the plurality of gas components. is obtained from the detection unit 100. Specifically, the detection unit 100 detects the amount of light in the absorption wavelength range of each of dinitrogen monoxide, sulfur dioxide, methane, and carbon dioxide. The detection unit 100 sends each detected detection value to the control unit 200.
  • the control unit 200 determines the concentration of dinitrogen monoxide based on the detected values of each of the plurality of gas components. More specifically, the control unit 200 operates based on the plurality of influence coefficients a to f and the pre-correction concentration of the gas component corresponding to each detected value, according to the relationships of equations (9) to (12) described above. to determine the concentration of dinitrogen monoxide.
  • control unit 200 displays the determined concentration of dinitrogen monoxide on the display section 400.
  • control unit 200 determines the concentration of dinitrogen monoxide in the sample gas.
  • FIG. 6 is a flowchart showing the processing of the control unit when calculating the influence coefficient.
  • control unit 200 detects a standard gas consisting of dinitrogen monoxide with a known concentration using each of the second detector 10B and the third detector 10C, and acquires the detected values.
  • control unit 200 receives an input of the concentration of dinitrogen monoxide from the input section 300.
  • control unit 200 determines the influence coefficient a indicating the degree of influence of dinitrogen monoxide in formula (9) on the measurement of methane, and the influence coefficient a that dinitrogen monoxide in formula (11) has on the measurement of sulfur dioxide.
  • An influence coefficient f indicating the degree of influence is determined.
  • control unit 200 detects a standard gas consisting of sulfur dioxide with a known concentration using each of the first detector 10A and the third detector 10C and obtains the detected values.
  • control unit 200 receives an input of the concentration of sulfur dioxide from input section 300.
  • control unit 200 calculates the influence coefficient b indicating the degree of influence of sulfur dioxide in formula (9) on the measurement of methane, and the degree of influence of sulfur dioxide in formula (10) on the measurement of nitrous oxide.
  • control unit 200 detects a standard gas consisting of methane with a known concentration using each of the first detector 10A and the second detector 10B and acquires the detected values.
  • control unit 200 receives an input of the concentration of methane from the input unit 300.
  • control unit 200 calculates the influence coefficient c indicating the degree of influence of methane on the measurement of dinitrogen monoxide in equation (10) and the degree of influence of methane on the measurement of sulfur dioxide in equation (11).
  • the influence coefficient e shown is determined.
  • control unit 200 detects a standard gas consisting of carbon dioxide with a known concentration using each of the first detector 10A, the second detector 10B, and the third detector 10C, and detects the detected values. get.
  • control unit 200 receives an input of the concentration of carbon dioxide from the input unit 300.
  • control unit 200 calculates the influence coefficient g indicating the degree of influence of carbon dioxide in formula (9) on the measurement of methane, and the degree of influence of carbon dioxide on the measurement of nitrous oxide in formula (10).
  • An influence coefficient h indicating the degree of influence of carbon dioxide in equation (11) on the measurement of sulfur dioxide is determined.
  • the gas measuring device 1 calculates the influence coefficient indicating the degree of influence of an interference component on the measurement of one gas component.
  • Examples and comparative examples> An example in which the concentration before correction obtained when measuring a sample gas using the gas measuring device 1 shown in FIG. 3 was corrected by the method according to this embodiment, and a comparative example in which the concentration was corrected by the conventional method. The results are shown in Table 1.
  • the density before correction was corrected according to the above equations (9) to (12). Furthermore, in the comparative example, the pre-correction density is corrected according to the following equations (13) to (15) and the above equation (12). Note that the influence coefficients a to i are common coefficients in the example and the comparative example.
  • the concentration before correction corresponding to the detected value is determined by the interference component without considering that the measurement of the interference component is influenced by other components. Correction is made using the uncorrected concentration of the component.
  • Table 1 there is a difference in density after correction between the comparative example and the example. This difference is due to taking into account that the measurement of the interference component is influenced by other components.By taking into account that the measurement of the interference component is influenced by other components, it is possible to more accurately determine the target component. The concentration of can be determined.
  • FIG. 7 shows infrared absorption spectra of dinitrogen monoxide and carbon dioxide.
  • FIG. 8 is an infrared absorption spectrum of dinitrogen monoxide, methane, and sulfur dioxide.
  • the spectrum shown by the solid line is the infrared absorption spectrum of dinitrogen monoxide.
  • the spectrum indicated by the dashed line is the infrared absorption spectrum of carbon dioxide.
  • the spectrum indicated by the two-dot chain line is the infrared absorption spectrum of sulfur dioxide.
  • the spectrum indicated by the broken line is the infrared absorption spectrum of methane.
  • the horizontal axis is wavelength and the vertical axis is absorbance.
  • dinitrogen monoxide has absorption wavelength regions around 4.5 ⁇ m and around 7.8 ⁇ m.
  • carbon dioxide has an absorption wavelength range around 4.25 ⁇ m, which at least partially overlaps with the absorption wavelength range around 4.5 ⁇ m of dinitrogen monoxide.
  • the first detection unit 120 includes an optical filter 20 that transmits light in the first absorption wavelength range while not transmitting light in the second absorption wavelength range that overlaps with the absorption wavelength range of carbon dioxide.
  • the first detector 10A detects the light that has passed through the optical filter 20, so the first detector 10A detects the light that has passed through the optical filter 20, so the first detector 10A detects the light that has passed through the optical filter 20. Detect the amount of light.
  • the 7.8 ⁇ m detected by the first detector 10A is The absorption in the vicinity is weaker than the absorption in the vicinity of 4.5 ⁇ m.
  • exhaust gas is assumed as the sample gas, and the concentration of carbon dioxide in the exhaust gas is on the order of %, whereas the concentration of dinitrogen monoxide is on the order of ppm. Since the concentration of carbon dioxide is higher than that of dinitrogen monoxide, the influence of carbon dioxide on the measurement of dinitrogen monoxide is extremely large.
  • the first detection unit 120 detects the amount of light in the absorption wavelength range around 7.8 ⁇ m, which does not overlap with the absorption wavelength range of carbon dioxide but has weak absorption. This makes it possible to reduce the influence of carbon dioxide present in a high concentration in the sample gas on the measurement of dinitrogen monoxide, making it possible to measure dinitrogen monoxide with higher accuracy.
  • Carbon monoxide (CO) may be contained in the exhaust gas.
  • the absorption wavelength range of carbon monoxide is around 4.7 ⁇ m, which overlaps with the absorption wavelength range of carbon monoxide around 4.5 ⁇ m. Therefore, by providing the optical filter 20, the influence of carbon monoxide on the measurement of dinitrogen monoxide can be reduced, and dinitrogen monoxide can be measured with higher accuracy.
  • the first detector 10A detects the amount of light in the absorption wavelength range around 7.8 ⁇ m among the absorption wavelength range of dinitrogen monoxide. As shown in Figure 8, methane has an absorption wavelength range around 7.8 ⁇ m, sulfur dioxide has an absorption wavelength range around 7.4 ⁇ m, and each gas component has an absorption wavelength range around 7.8 ⁇ m for dinitrogen monoxide. at least partially overlaps with the absorption wavelength range of Therefore, the detected value of the first detector 10A reflects not only the effect of light absorption by dinitrogen monoxide, but also the effect of light absorption by sulfur dioxide and methane.
  • the first detection unit 120 has at least a portion of the absorption wavelength range of dinitrogen monoxide that is different from the second absorption wavelength range that overlaps with the absorption wavelength range of carbon dioxide.
  • a first gas filter 30 filled with gas components having overlapping absorption wavelength ranges is provided. This reduces the amount of light in the absorption wavelength range of the gas component that at least partially overlaps with the first absorption wavelength range. As a result, the influence of gas components that at least partially overlap with the first absorption wavelength range on the measurement of dinitrogen monoxide can be reduced, and dinitrogen monoxide can be measured with higher accuracy.
  • the first gas filter 30 is filled with methane gas.
  • the absorption wavelength range of methane overlaps more with the absorption wavelength range of dinitrogen monoxide than that of sulfur dioxide. Therefore, methane has a greater influence on dinitrogen monoxide measurements than sulfur dioxide.
  • the amount of light in the absorption wavelength range of methane which has a large influence on the measurement of dinitrogen monoxide, can be reduced, and dinitrogen monoxide can be measured with higher accuracy.
  • a gas filter filled with sulfur dioxide is further provided on the first optical path IR1 between the first sample cell 122 and the first detector 10A. It's okay. Further, the gas component filled in the first gas filter 30 may be sulfur dioxide instead of methane.
  • the effect of the first gas filter 30 can be adjusted by changing the partial pressure of the filling gas or by changing the distance through which the light from the first light source 124 passes through the first gas filter 30.
  • the effect of the first gas filter 30 can be increased by increasing the partial pressure of the filling gas or by increasing the distance through which the light from the first light source 124 passes through the first gas filter 30.
  • the effect of the first gas filter 30 is increased, the amount of light in the absorption wavelength range of dinitrogen monoxide detected by the first detector 10A will also decrease, and the detection sensitivity of dinitrogen monoxide will decrease. Therefore, the partial pressure of the filling gas and the distance through which the light from the first light source 124 passes through the first gas filter 30 are adjusted within a range that ensures detection sensitivity for dinitrogen monoxide.
  • the first detection unit 120 uses the optical filter 20 to cut light in the absorption wavelength range of carbon dioxide.
  • carbon dioxide also absorbs light in the absorption wavelength range around 7.8 ⁇ m, although it is a small amount.
  • the concentration of carbon dioxide in the exhaust gas is higher than that of dinitrogen monoxide.
  • control unit 200 determines the concentration of dinitrogen monoxide, assuming that carbon dioxide affects the measurement of dinitrogen monoxide, as shown in equation (10).
  • control unit 200 determines the concentration of dinitrogen monoxide, assuming that carbon dioxide influences each measurement of sulfur dioxide and methane, as shown in equations (9) and (11).
  • the second detection unit 140 includes a second gas filter 40 filled with carbon dioxide.
  • the second detection unit 140 reduces the amount of light in the absorption wavelength range of carbon dioxide among the absorption wavelength ranges of sulfur dioxide and methane.
  • the influence of carbon dioxide on each measurement of sulfur dioxide and methane can be reduced, and sulfur dioxide and methane can be measured with higher accuracy.
  • the detection sensitivity of the fourth detector 10D is reduced. Therefore, the partial pressure of the filling gas in the second gas filter 40 and the distance through which the light from the second light source 144 passes through the second gas filter 40 are adjusted within a range that ensures carbon dioxide detection sensitivity.
  • the second detection unit 140 includes a second housing 12B filled with sulfur dioxide between a third detector 10C that detects the amount of light in the absorption wavelength range of methane and a second sample cell 142.
  • a container 10B is arranged. Therefore, the third detector 10C detects the light that has passed through the second sample cell 142 and the second housing 12B in this order.
  • the second housing 12B functions as a gas filter, and reduces the amount of light in the absorption wavelength range of sulfur dioxide among the absorption wavelength range of methane. As a result, methane measurement errors caused by sulfur dioxide can be reduced, and methane can be measured with higher accuracy.
  • the third detector 10C may be arranged on the second optical path IR2 between the second sample cell 142 and the second detector 10B.
  • the third housing 12C filled with methane of the third detector 10C functions as a gas filter, reducing the amount of light in the absorption wavelength range of methane among the absorption wavelength range of sulfur dioxide. .
  • errors in measuring sulfur dioxide caused by methane can be reduced, and sulfur dioxide can be measured with higher accuracy.
  • the order of the second detector 10B and the third detector 10C is determined depending on which of methane and sulfur dioxide is desired to be measured more accurately.
  • the gas measuring device 1 uses infrared light, but it may also use ultraviolet light depending on the absorption wavelength range of the target component.
  • the amount of light is indirectly detected by a change in internal pressure when transmitted light passes through a cell filled with a gas to be detected.
  • the amount of light may be directly detected by a photoconductive element or the like.
  • the plurality of detectors (first detector 10A to fourth detector 10D) included in the detection unit 100 were designed to use a common light amount detection method.
  • the plurality of detectors may use different methods of detecting the amount of light.
  • the first detector 10A and the fourth detector 10D arranged at the farthest positions from the light source are detectors equipped with pyroelectric sensors, and the other second detector 10B and third detector 10C may be a detector having the configuration of the above embodiment.
  • gas measuring device 1 was designed to measure exhaust gas, it is also possible to measure other gases.
  • object to be detected by each detector may be changed depending on the object to be measured.
  • the optical filter 20, the first gas filter 30, and the second gas filter 40 can also be adjusted depending on the object to be measured.
  • the gas measuring device 1 was equipped with detectors for three types of interference components: sulfur dioxide, methane, and carbon dioxide, in order to measure the concentration of dinitrogen monoxide.
  • the gas measuring device 1 only needs to be equipped with a detector for at least one of the interference components of sulfur dioxide, methane, and carbon dioxide, and in addition to the detectors for the three types of interference components, it may also A detector for interference components may be provided.
  • the control unit 200 determines the concentration of dinitrogen monoxide, assuming that other components have no influence on the measurement of carbon dioxide, as shown in equation (12).
  • control unit 200 controls the control unit 200 to control the control unit 200 so that, among one or more interference components with respect to one gas component, the measurement error of the interference component with respect to the one gas component in the measurement of the one gas component is greater than the concentration of the one gas component.
  • concentration of the target component may be determined by setting the influence of the interference component on the measurement of the one gas component to zero.
  • the measurement error caused by an interference component in the measurement of a gas component can be calculated by multiplying the corrected concentration of the interference component by an influence coefficient that indicates the degree of influence that the interference component has on the measurement of the gas component. It will be done.
  • the measurement error of an interfering component in the measurement of one gas component is 1/1000 or less of the concentration of that one gas component, the influence of that interfering component on the measurement of that one gas component can be reduced to zero. You can also use it as In addition, if the measurement error of an interfering component in the measurement of one gas component is 1/100 or less of the concentration of the one gas component, the influence of the interfering component on the measurement of the one gas component can be reduced to zero. You can also use it as The standard for setting the influence to zero may be set according to the accuracy required of the gas measuring device 1 and the assumed maximum concentration of the interfering component in the sample gas.
  • the control unit 200 may determine the concentration of dinitrogen monoxide by setting the influence coefficient d in equation (10) to zero.
  • the gas measuring device 1 uses exhaust gas as the sample gas and uses dinitrogen monoxide as a target component to determine the concentration of dinitrogen monoxide.
  • the sample gas and target component may be other gases and components.
  • the gas measurement device 1 may be configured to measure a sample gas that includes two or more types of interference components with respect to the target component in addition to the target component. Even in this case, the detector for the target component and the detector for the interference component should be placed on separate optical paths, and the detectors for each of the multiple interference components should be placed in series on the same optical path. Therefore, it is possible to suppress a decrease in the detection sensitivity of the target component and an increase in the size of the gas measuring device.
  • control unit 200 performs both the control of the detection unit 100 and the calculation of concentration.
  • the gas measurement device 1 may separately include a control unit that controls the detection unit 100 and a calculation unit that calculates the concentration.
  • each of the control unit and the calculation unit includes a processor, a memory, and an input/output interface.
  • a gas measurement device measures a sample gas containing a plurality of gas components whose absorption wavelength ranges overlap at least partially with each other.
  • the gas measurement device includes a detection unit that detects the amount of light in the absorption wavelength range of each of a plurality of gas components by detecting light that has passed through a sample gas, and a detection unit that detects the amount of light in the absorption wavelength range of each of the plurality of gas components. and an arithmetic unit that calculates the concentration of the target component among the plurality of gas components based on the value.
  • a gas component having an absorption wavelength range that at least partially overlaps with an absorption wavelength range of one of the gas components is an interference component with respect to the one gas component.
  • the concentration of each of the plurality of gas components is the concentration after correction, which is obtained by subtracting the measurement error caused by one or more interference components to the measurement of the gas component from the concentration before correction corresponding to the detected value of the gas component. It is expressed as
  • the measurement error caused in the measurement of a gas component is expressed by the linear sum of the corrected concentration of the interference component with respect to the gas component and the influence coefficient indicating the degree of influence of the interference component on the measurement of the gas component.
  • the calculation unit calculates the corrected value of the target component based on the plurality of influence coefficients and the detected value of each of the plurality of gas components, according to the relationship between the corrected concentration and the pre-correction concentration for each of the plurality of gas components. Find the concentration as the concentration of the target component.
  • the corrected concentration of the target component is expressed using the corrected concentration obtained by subtracting the measurement error given to the measurement of the interference component from the uncorrected concentration of the interference component with respect to the target component. be done. Further, the concentration of the target component is determined according to the relationship between the corrected concentration of the target component and the corrected concentration of the interference component. Therefore, it is possible to more accurately determine the concentration of the target component, taking into account that the measurement of the interference component is influenced by other components.
  • the detection unit detects a plurality of gas components by detecting light that has passed through a standard gas having a known concentration consisting of the first component of the plurality of gas components. The amount of light in the absorption wavelength range of the second component of the gas components is detected. The calculation unit determines whether the first component is the same as the second component based on the detected value of the second component and the known concentration of the first component, according to the relationship between the corrected concentration and the pre-corrected concentration of the second component. Find the influence coefficient that indicates the degree of influence on the measurement.
  • the target component is The corrected concentration is represented by the linear sum of an intermediate coefficient represented by a plurality of influence coefficients and a pre-correction concentration corresponding to each detected value of a plurality of gas components.
  • the calculation unit determines the corrected concentration of the target component as the concentration of the target component based on the intermediate coefficient and the detected value of each of the plurality of gas components.
  • the calculation for determining the concentration of the target component can be facilitated, and the load on the calculation unit can be reduced.
  • the plurality of gas components include at least one component of carbon dioxide, methane, and sulfur dioxide. Contains dinitrogen oxide.
  • nitrous oxide which is a greenhouse gas, can be measured with high accuracy using exhaust gas as a sample gas.
  • the calculation unit is configured to perform a calculation on one gas component among one or more interference components with respect to one gas component.
  • the influence of the interference component on the measurement of the one gas component is zero. shall be.
  • the calculation for determining the concentration of the target component can be facilitated, and the load placed on the calculation unit can be reduced.
  • the gas component different from the target component among the plurality of gas components includes carbon dioxide.
  • the calculation unit determines the concentration of the target component assuming that other gas components have no influence on the measurement of carbon dioxide.
  • a method is a method of determining the concentration of a target component in a sample gas containing a plurality of gas components whose absorption wavelength ranges overlap at least in part with each other.
  • the method includes the step of detecting the light amount in the absorption wavelength range of each of the plurality of gas components by detecting the light that has passed through the sample gas, and obtaining a detected value for each of the plurality of gas components. and a step of determining the concentration of a target component among the plurality of gas components based on the obtained detected values of each of the plurality of gas components.
  • a gas component having an absorption wavelength range that at least partially overlaps with an absorption wavelength range of one of the gas components is an interference component with respect to the one gas component.
  • the concentration of each of the plurality of gas components is the concentration after correction, which is obtained by subtracting the measurement error caused by one or more interference components to the measurement of the gas component from the concentration before correction corresponding to the detected value of the gas component. It is expressed as The measurement error caused in the measurement of a gas component is expressed by the linear sum of the corrected concentration of the interference component with respect to the gas component and the influence coefficient indicating the degree of influence of the interference component on the measurement of the gas component.
  • the corrected concentration of the target component is determined as the concentration of the target component.
  • the corrected concentration of the target component is expressed using the corrected concentration obtained by subtracting the measurement error given to the measurement of the interference component from the uncorrected concentration of the interference component with respect to the target component. . Further, the concentration of the target component is determined according to the relationship between the corrected concentration of the target component and the corrected concentration of the interference component. Therefore, it is possible to more accurately determine the concentration of the target component, taking into account that the measurement of the interference component is influenced by other components.
  • the method described in Item 7 further includes the step of determining an influence coefficient indicating the degree of influence of an interference component on one gas component on the measurement of the one gas component.
  • the step of determining the influence coefficient is to detect the absorption wavelength range of the second component among the plurality of gas components by detecting the light that has passed through a standard gas whose concentration is known and is composed of the first component among the plurality of gas components. and obtaining a detected value obtained by detecting the light amount of the second component, and according to the relationship between the corrected density of the second component and the uncorrected density, the detected value of the second component and the known concentration of the first component. and calculating an influence coefficient indicating the degree of influence of the first component on the measurement of the second component based on the method.
  • the gas measurement device measures a sample gas containing a plurality of gas components whose absorption wavelength ranges overlap at least in part with each other.
  • the gas measuring device includes a first detection unit for detecting a first component in a sample gas, a second component each having an absorption wavelength range that at least partially overlaps with an absorption wavelength range of the first component in the sample gas; By correcting the detection value of the first component detected by the second detection unit and the first detection unit, using the plurality of detection values detected by the second detection unit. , an arithmetic unit that calculates the concentration of the first component.
  • the first detection unit includes a first light source, a first sample cell filled with a sample gas, and a first detection unit that detects the light that has passed through the first sample cell and detects the amount of light in the absorption wavelength range of the first component. a detector; The first sample cell and the first detector are arranged in series on a first optical path of light emitted from the first light source.
  • the second detection unit includes a second light source, a second sample cell filled with a sample gas, and a second detection unit that detects the light that has passed through the second sample cell and detects the amount of light in the absorption wavelength range of the second component.
  • It includes a detector and a third detector that detects the light that has passed through the second sample cell and detects the amount of light in the absorption wavelength range of the third component.
  • the second sample cell, the second detector, and the third detector are arranged in series on a second optical path of light emitted from the second light source.
  • the detector detects the first component on the first optical path that is different from the second optical path on which the detector for the component that interferes with the detection of the first component is disposed. By arranging this, it is possible to suppress the attenuation of light and suppress the decrease in detection sensitivity of the first component. Furthermore, since the second detector and the third detector are arranged in series on the second optical path, it is possible to suppress the overall size of the gas measuring device.
  • the sample gas is exhaust gas.
  • the first component is dinitrogen monoxide.
  • nitrous oxide which is a greenhouse gas
  • exhaust gas as a sample gas
  • the first detector includes a first housing filled with the first component, and a first detector that detects the pressure inside the first housing. including.
  • the first detection unit does not transmit light in the second absorption wavelength range that overlaps with the absorption wavelength range of carbon dioxide among the first absorption wavelength range and the second absorption wavelength range that dinitrogen monoxide has, and the first detection unit
  • the device further includes an optical filter that transmits light in a wavelength range, and a first gas filter filled with a gas component having an absorption wavelength range that at least partially overlaps with the first absorption wavelength range.
  • An optical filter and a first gas filter are arranged on a first optical path between the first sample cell and the first detector.
  • the gas measuring device described in Item 11 it is possible to reduce the influence of carbon dioxide present in high concentration in the exhaust gas on the measurement of dinitrogen monoxide, and also to absorb absorption that at least partially overlaps with the first absorption wavelength range.
  • the influence on the measurement of dinitrogen monoxide caused by gas components having a wavelength range can be reduced.
  • the gas component filled in the first gas filter is methane.
  • the second detection unit is arranged on the second optical path between the second sample cell and the second detector, and the second detection unit is arranged on the second optical path between the second sample cell and the second detector, It further includes a filled second gas filter.
  • the second component is sulfur dioxide.
  • the third component is methane.
  • the second detector includes a second housing filled with a second component and a second detection section that detects the pressure inside the second housing. The third detector detects the light that has passed through the second sample cell and the second housing in this order.
  • the second detector functions as a gas filter, and the influence of sulfur dioxide on methane measurement can be reduced.
  • the second detection unit detects the light that has passed through the second sample cell, and detects the absorption wavelength of the first component in the sample gas.
  • the fourth detector further includes a fourth detector that detects the amount of light in the absorption wavelength range of the fourth component that at least partially overlaps with the absorption wavelength range of the fourth component.
  • the second component is sulfur dioxide.
  • the third component is methane.
  • the fourth component is carbon dioxide.
  • the second sample cell, second detector, third detector, and fourth detector are arranged in series on the second optical path in this order.
  • the gas measuring device described in item 15 it is possible to obtain detected values of a plurality of interference components that affect the measurement of dinitrogen monoxide, and the concentration of dinitrogen monoxide can be measured more accurately.
  • 1, 1a gas measuring device 10A, 10a first detector, 10B, 10b second detector, 10C, 10c third detector, 10D fourth detector, 12A to 12D first casing to fourth casing, 14A to 14D First detection section to fourth detection section, 20 Optical filter, 30 First gas filter, 40 Second gas filter, 100, 100a Detection unit, 112, 114 Switching valve, 120 First detection unit, 122 First Sample cell, 122a, 142a Gas inlet, 122b, 142b Gas outlet, 124 First light source, 140 Second detection unit, 142 Second sample cell, 144 Second light source, 160 Motor, 180 Sector, 200 Control unit, 200a Arithmetic unit, 220 Processor, 222 Pre-correction density calculation unit, 224 Correction value calculation unit, 226 Coefficient calculation unit, 228 Storage unit, 240 Memory, 300 Input unit, 400 Display unit, IR1 first optical path, IR2 second optical path, L1 ⁇ L4 1st line ⁇ 4th line, RG reference gas, RL reference

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4700369A1 (en) * 2024-08-23 2026-02-25 Services Pétroliers Schlumberger Measurement of gaseous/volatile hydrocarbon concentrations

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07167784A (ja) * 1993-12-16 1995-07-04 Fuji Electric Co Ltd 赤外線ガス分析計
JP2003050203A (ja) * 2001-08-03 2003-02-21 Nissan Motor Co Ltd 非分散型赤外吸収式ガス分析装置及び分析方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07167784A (ja) * 1993-12-16 1995-07-04 Fuji Electric Co Ltd 赤外線ガス分析計
JP2003050203A (ja) * 2001-08-03 2003-02-21 Nissan Motor Co Ltd 非分散型赤外吸収式ガス分析装置及び分析方法

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4700369A1 (en) * 2024-08-23 2026-02-25 Services Pétroliers Schlumberger Measurement of gaseous/volatile hydrocarbon concentrations

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