Gas measuring device and gas measuring method

Abstract

To measure the temperature of sample gas, such as combustion gas in a combustion furnace or exhaust gas flowing in a flue without using a thermocouple, and accurately measure the concentration of a gas component included in the sample gas.SOLUTION: A gas measuring device comprises: a laser beam source that irradiates sample gas with a laser beam; a photo detector that detects the laser beam transmitted through the sample gas; a radiation thermometer in which a temperature measuring direction is provided along an optical path of the laser beam; and a signal processing unit that calculates the concentration of a gas component included in the sample gas on the basis of a light intensity signal obtained from the photo detector and a temperature signal obtained from the radiation thermometer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas metering device and a gas metering method. [Background technology]

[0002] Conventionally, gas analyzers using laser absorption spectrometry have been considered for in-situ measurement of the concentrations of gas components contained in sample gases such as combustion gases in a combustion furnace and exhaust gases flowing through a flue.

[0003] Here, since it is not possible to control the temperature of sample gases such as the combustion gas in a combustion furnace or the exhaust gas flowing through a flue, in order to accurately measure the concentration of the gas components contained in the sample gas, the temperature of the sample gas is measured and the concentration of the gas components is calculated based on that temperature.

[0004] For example, as shown in Patent Document 1, a gas analyzer has been devised in which a thermocouple is inserted into a combustion furnace or a flue and the concentration of a gas component is calculated based on the temperature measured by the thermocouple.

[0005] However, in order to install a thermocouple in a combustion furnace or a flue, the thermocouple must be designed to withstand high temperatures, which makes the thermocouple expensive. Also, in order to insert the thermocouple into the measurement area of ​​the gas analyzer, such as the center of the furnace, the thermocouple becomes long and easily breaks, so great care must be taken when handling and installing it.

[0006] Furthermore, even though the gas temperature is non-uniform in the area through which the laser light passes, one thermocouple can only measure the temperature at one point in the space inside the combustion furnace or flue. Therefore, the gas components cannot be obtained with high accuracy. Although it is possible to provide multiple thermocouples, this is not practical due to the above problems. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2021-139868 A Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems, and its main objective is to measure the temperature of sample gases such as combustion gases in a combustion furnace and exhaust gas flowing through a flue without using a thermocouple, and to accurately measure the concentration of gas components contained in the sample gas. [Means for solving the problem]

[0009] That is, the gas measurement device of the present invention is characterized by comprising a laser light source that irradiates laser light onto a sample gas, a photodetector that detects the laser light that has passed through the sample gas, a radiation thermometer whose temperature measurement direction is arranged along the optical path of the laser light, and a signal processing unit that calculates the concentration of gas components contained in the sample gas based on a light intensity signal obtained by the photodetector and a temperature signal obtained by the radiation thermometer.

[0010] In such a gas measuring device, the temperature measurement direction of the radiation thermometer is set along the optical path of the laser light, so that the average temperature of the sample gas along the optical path of the laser light can be measured. Therefore, the concentration of the gas components contained in the sample gas can be measured more accurately than with a thermocouple that measures the temperature at one point.

[0011] The gas meter device of the present invention is preferably one for analyzing the sample gas in a furnace or a flue. In this case, it is preferable that an opening through which the laser light passes is formed in the furnace wall or the flue wall, and the radiation thermometer detects the temperature of the sample gas through the opening. This configuration simplifies the configuration of the furnace wall or flue wall for installing the radiation thermometer. Also, since the temperature of the sample gas is detected via the opening through which the laser light passes, it becomes possible to measure the temperature of the sample gas near the optical path of the laser light (near the passing area). Furthermore, a high-temperature thermocouple is not required, which reduces the cost of the device and makes installation easier.

[0012] Specifically, it is preferable that the opening is provided with an optical window through which the laser light passes, and the radiation thermometer measures the temperature of the sample gas through the optical window. With this configuration, the temperature of the sample gas is measured via the optical window through which the laser light passes, so the optical path (optical axis) of the laser light and the temperature measurement axis of the radiation thermometer can be brought closer together, and the temperature of the sample gas in the vicinity of the optical path of the laser light (in the vicinity of the passing area) can be measured with high accuracy. In addition, the opening can be sealed with the optical window, making it possible to eliminate the need for a sealing mechanism when using a thermocouple.

[0013] In order to accurately measure low concentration gas components by lengthening the optical path, it is desirable that the gas meter device further includes a reflecting mirror that reflects the laser light, and that the laser light from the laser light source is reflected by the reflecting mirror and detected by the photodetector.

[0014] In order to facilitate installation in a combustion furnace, a flue, etc., and to facilitate the optical design of the laser light source and the photodetector, it is desirable for the laser light source and the photodetector to be unitized.

[0015] When measuring sample gas in a combustion furnace or a flue in situ, the sample gas is a gas generated by combustion. In this case, in order to accurately measure the temperature of the sample gas while making it difficult for the radiation thermometer to measure the temperature of the furnace wall or the flue wall, it is desirable for the radiation thermometer to measure the temperature of the sample gas via a bandpass filter that passes the absorption wavelength band of the gas components generated by combustion. With this configuration, the thermal radiation emitted from the furnace wall and the flue wall is absorbed by the generated gas, and only the thermal radiation emitted from the gas reaches the radiation thermometer, so the temperature of the gas components generated by combustion can be measured more accurately, and the temperature of the sample gas can be measured with high precision. For example, in the case of a combustion furnace that uses ammonia as fuel, it is possible to use a bandpass filter that passes the absorption wavelength band of moisture (H2O) (e.g., 6 to 8 μm). Also, in the case of a combustion furnace that uses methane gas as fuel, it is possible to use a bandpass filter that passes the absorption wavelength band of carbon dioxide (CO2) (e.g., 4 to 5 μm).

[0016] A desirable example of application of the gas measuring device of the present invention is to analyze combustion gas in an ammonia combustion furnace that uses ammonia as fuel, where combustion control is difficult and in-situ measurement is required.

[0017] As a specific embodiment of the signal processing unit, it is desirable that the signal processing unit calculates the concentration of at least one of the components of nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (N2O) or ammonia (NH3) in the sample gas.

[0018] Furthermore, the gas measurement method of the present invention is a gas analysis method using a laser light source which irradiates a sample gas with laser light and a photodetector which detects the laser light which has passed through the sample gas, and is characterized in that the temperature measurement direction of a radiation thermometer is set along the optical path of the laser light to detect the temperature of the sample gas, and the concentration of gas components contained in the sample gas is calculated based on the light intensity signal obtained by the photodetector and the temperature signal obtained by the radiation thermometer. Effect of the Invention

[0019] According to the present invention configured in this manner, it is possible to measure the temperature of a sample gas, such as the combustion gas in a combustion furnace or the exhaust gas flowing through a flue, without using a thermocouple, and to accurately measure the concentration of gas components contained in the sample gas. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic diagram showing a gas measurement device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a functional block diagram of a signal processing device according to the embodiment. [Diagram 3] FIG. 1 is a diagram showing a driving current (voltage) and a modulation signal in pseudo continuous oscillation. [Figure 4] 5A to 5C are schematic diagrams showing a method of modulating a laser oscillation wavelength in the embodiment. [Diagram 5] 11 is a time series graph showing an example of an oscillation wavelength, a light intensity I(t), a logarithmic intensity L(t), a feature signal Fi(t), and a correlation value Si(t) in the embodiment. [Figure 6] FIG. 13 is a schematic diagram showing a gas meter device according to a modified embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] <One embodiment of the present invention> Hereinafter, an embodiment of a gas meter device according to the present invention will be described with reference to the drawings. In addition, in any of the drawings shown below, for the purpose of easy understanding, some parts are omitted or exaggerated in schematic form as appropriate. The same components are denoted by the same reference numerals and the description thereof is omitted as appropriate.

[0022] <Device configuration> The gas metering device 100 of this embodiment analyzes fuel gas generated by combustion of fuel gas in a combustion furnace 10 using, for example, ammonia (NH3), methane (CH4), hydrogen (H2), etc. Note that the gas metering device 100 may also analyze combustion gas in other combustion furnaces.

[0023] Specifically, the gas measuring device 100 analyzes a sample gas, which is a combustion gas in a furnace, and uses, for example, an infrared laser absorption modulation method (see Japanese Patent No. 6886507; IRLAM (Infrared Laser Absorption Modulation)).

[0024] More specifically, as shown in FIG. 1, the gas metering device 100 includes a laser light source 2 that irradiates a sample gas with a laser light L1, a photodetector 3 that detects the laser light L1 that has passed through the sample gas, a radiation thermometer 4 that detects the temperature of the sample gas, and a signal processor 5 that calculates the concentration of a gas component contained in the sample gas based on a light intensity signal obtained by the photodetector 3 and a temperature signal obtained by the radiation thermometer 4. The gas metering device 100 of this embodiment further includes a reflecting mirror 6 that reflects the laser light L1, and is configured so that the laser light L1 from the laser light source 2 is reflected by the reflecting mirror 6 and detected by the photodetector 3. Here, as the reflecting mirror 6, a retroreflector that reflects the incident laser light L1 in a direction parallel to and opposite to the incident direction can be used. By using a retroreflector in this way, the optical axis of the laser light L1 can be easily adjusted, and the structure is resistant to optical axis deviation.

[0025] The above-mentioned laser light source 2, photodetector 3, radiation thermometer 4, and reflecting mirror 6 are provided outside the combustion furnace 10, and openings 11a, 11b through which the laser light L1 passes are formed in the furnace walls 10a, 10b. The openings 11a, 11b are provided with optical windows 12a, 12b through which the laser light L1 passes, and the openings 11a, 11b are sealed by the optical window 12. This prevents the laser light source 2, photodetector 3, radiation thermometer 4, and reflecting mirror 6 from being exposed to the atmosphere inside the combustion furnace 10. The signal processing unit 5 is also provided outside the combustion furnace 10.

[0026] The laser light source 2 is a semiconductor laser, which is a quantum cascade laser in this embodiment. A quantum cascade laser is a semiconductor laser that uses intersubband transition due to a multi-stage quantum well structure, and oscillates laser light of a specific wavelength in the wavelength range of about 4 μm to about 20 μm. This semiconductor laser 22 is capable of modulating (changing) the oscillation wavelength by a given current (or voltage).

[0027] In this embodiment, a plurality of laser light sources 2 are provided. The plurality of laser light sources 2 are configured to emit laser light L1 of different wavelengths according to the gas components. The gas components to be measured in this embodiment are four nitrogen compounds (nitric oxide (NO), nitrogen dioxide (NO2), dinitrogen oxide (N2O), or ammonia (NH3)), so four laser light sources 2 are provided according to the absorption wavelength bands of each of these gas components. Here, the plurality of laser light sources 2 may be configured to emit laser light at different times, or at least two or more may be configured to emit laser light simultaneously. Note that the gas components to be measured may be carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), water (H2O), sulfur dioxide (SO2), oxygen (O2), hydrogen (H2), or the like, instead of the above four nitrogen compounds.

[0028] Here, the photodetector 3 is a thermal type such as a relatively inexpensive thermopile, but other types such as quantum type photoelectric elements such as HgCdTe, InGaAs, InAsSb, and PbSe, which have good responsiveness, may also be used.

[0029] The radiation thermometer 4 is configured to detect infrared rays emitted from a measurement object using the infrared detection element 41, and measure the temperature of the measurement object based on the detection intensity. The specific configuration of the radiation thermometer 4 will be described later.

[0030] The signal processing unit 5 calculates the concentration of each of the four nitrogen compound components (nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (N2O) and ammonia (NH3)) based on the light intensity signal obtained by the photodetector 3 and the temperature signal obtained by the radiation thermometer 4. Here, the signal processing unit 5 may calculate the concentration of the gas component based on the light intensity signal and then correct the concentration based on the temperature signal, or may calculate the concentration of the gas component based on the light intensity signal and the temperature signal. The specific configuration of the signal processing unit 5 will be described later.

[0031] <Specific configuration of the radiation thermometer 4 and arrangement of the optical systems 2, 3, 6 and the radiation thermometer 4>

[0032] Specifically, as shown in FIG. 1, the radiation thermometer 4 includes an infrared detection element 41 housed in a casing 40, and a lens 42 disposed between the infrared detection element 41 and an object to be measured.

[0033] The infrared detection element 41 detects infrared rays in the entire infrared wavelength band, and is a thermal type such as a thermopile in this example. Note that other types of infrared detection element 41, such as quantum type photoelectric elements of HgCdTe, InGaAs, InAsSb, PbSe, etc., may also be used. Lens 42 is an IR lens that focuses infrared rays emitted from the measurement target onto the infrared detection element 41.

[0034] Furthermore, the radiation thermometer 4 is configured to measure the temperature of the sample gas in the furnace via a bandpass filter 7 that passes the absorption wavelength band of gas components generated by combustion. Specifically, the bandpass filter 7 is provided in front of the infrared detection element 41 inside the radiation thermometer 4 (here, between the infrared detection element 41 and the lens 42). This bandpass filter 7 is a bandpass filter that passes the absorption wavelength band of moisture (H2O) (for example, 6 to 7 μm or 7 to 8 μm) or the absorption wavelength band of carbon dioxide (CO2) (for example, 4 to 5 μm).

[0035] The radiation thermometer 4 is provided with its temperature measurement direction 4x aligned along the optical path LP of the laser light L1. Here, the temperature measurement direction 4x is a direction perpendicular to the infrared detection surface of the infrared detection element 41, and is also aligned with the optical axis of the lens 42. The temperature measurement direction 4x is provided in the vicinity of the optical path LP of the laser light L1 so as to be parallel or substantially parallel to the optical path LP. Specifically, the temperature measurement direction 4x is provided so as to be parallel or substantially parallel to the optical path LP of the incident laser light L1 (laser light L1 incident on the reflection mirror 6). Note that the temperature measurement direction 4x does not have to be aligned with the optical axis of the lens 42.

[0036] The radiation thermometer 4 measures the temperature of the sample gas in the furnace through the openings 11a and 11b (specifically, the opening 11b corresponding to the reflecting mirror 6).

[0037] Specifically, the radiation thermometer 4 measures the temperature of the sample gas in the furnace through an optical window 12b provided in the openings 11a and 11b (specifically, the opening 11b corresponding to the reflecting mirror 6). That is, the optical window 12b of the reflecting mirror 6 and the radiation thermometer 4 are the same. However, the optical window of the reflecting mirror 6 and the radiation thermometer 4 do not have to be the same.

[0038] In this embodiment, a reflective mirror 6 is used, and a combustion furnace 10 has opposing furnace walls 10a and 10b, in which a laser light source 2 and a photodetector 3 are attached to one of the furnace walls 10a, and a reflective mirror 6 and a radiation thermometer 4 are attached to the other furnace wall 10b.

[0039] The laser light source 2 and the photodetector 3 may be integrally structured to constitute a first unit U1. In this embodiment, four laser light sources 2 are arranged in a row to form a unit, and are introduced into the furnace so as to form a common optical path LP via a half mirror 8. This first unit U1 is unitized together with an optical window 12, and may be provided with an adjustment mechanism for adjusting the optical axis of the laser light source 2, the photodetector 3, or the half mirror 8.

[0040] The reflecting mirror 6 and the radiation thermometer 4 may be integrally formed with each other to form a second unit U2. This second unit U2 is unitized with the optical window 12, and may be provided with an adjustment mechanism for adjusting the optical axis of the reflecting mirror 6, or an adjustment mechanism for adjusting the temperature measurement direction of the radiation thermometer 4.

[0041] <Specific Configuration of Signal Processing Unit 5> The signal processing unit 5 includes analog electric circuits including buffers, amplifiers, etc., digital electric circuits including a CPU, memory, etc., and AD converters, DA converters, etc. that mediate between these analog and digital electric circuits.

[0042] The signal processing unit 5, by cooperation of the CPU and its peripheral devices in accordance with a predetermined program stored in a predetermined area of ​​the memory, performs the functions of a light source control unit 51 that controls the output of the laser light source 2, and an arithmetic processing unit 52 that receives a detection signal from the photodetector 3, processes the value, and calculates the concentration of the gas component, as shown in FIG. 2.

[0043] Each part is described in detail below. The light source control unit 51 controls the current source (or voltage source) of the laser light source 2 by outputting a current (or voltage) control signal. Specifically, the light source control unit 51 changes the drive current (or drive voltage) of the laser light source 2 at a predetermined frequency, and modulates the oscillation wavelength of the laser light output from the laser light source 2 at a predetermined frequency with respect to the center wavelength (see FIG. 3). This causes the laser light source 2 to emit modulated light modulated at a predetermined modulation frequency.

[0044] In this embodiment, the light source control unit 51 changes the drive current to a triangular wave shape and modulates the oscillation frequency to a triangular wave shape (see "Oscillation Wavelength" in FIG. 4). In practice, the drive current is modulated with another function so that the oscillation frequency becomes triangular. Also, as shown in FIG. 3, the oscillation wavelength of the laser light is modulated with the peak of the optical absorption spectrum of the gas component to be measured as the center wavelength. Alternatively, the light source control unit 51 may change the drive current to a sine wave shape, sawtooth wave shape, or any other function shape and modulate the oscillation frequency to a sine wave shape, sawtooth wave shape, or any other function shape.

[0045] The calculation processing section 52 includes a logarithm calculation section 52a, a correlation value calculation section 52b, a storage section 52c, and a concentration calculation section 52d.

[0046] The logarithmic calculation unit 52a performs logarithmic calculation on the light intensity signal, which is the detection signal of the photodetector 3. The function I(t) showing the time-series change of the light intensity signal obtained by the photodetector 3 is shown as "light intensity I(t)" in Fig. 4, and by performing logarithmic calculation, it becomes as shown as "logarithmic intensity L(t)" in Fig. 4.

[0047] The correlation value calculation unit 52b calculates correlation values ​​between an intensity-related signal related to the intensity of sample light obtained when measuring the sample gas and a plurality of predetermined feature signals. The feature signal is a signal for extracting a waveform feature of the intensity-related signal by correlating it with the intensity-related signal. As the feature signal, for example, a sine wave signal or various other signals that match the waveform feature to be extracted from the intensity-related signal can be used. Here, the correlation value calculation unit 52b uses a logarithmically calculated light intensity signal (logarithmic intensity L(t)) as the intensity-related signal.

[0048] In addition, the correlation value calculation unit 52b calculates a feature signal F that is greater than the total number of types of the gas components to be measured (in this embodiment, nitrogen compounds such as NO) and the interference components. i (t) (i=1, 2, . . . , n), a plurality of sample correlation values ​​S, which are correlation values ​​between the intensity-related signal of the sample light and each of the plurality of feature signals, are calculated by the following formula (1). i In addition, T in the formula 1 is the modulation period.

[0049]

number

[0050] When calculating the sample correlation value, the correlation value calculation unit 52b calculates the sample correlation value by using the intensity-related signal L(t) of the sample light and the plurality of feature signals F i Correlation value S with (t) i from the reference light intensity-related signal L0(t) and multiple feature signals F i The reference correlation value R i The corrected sample correlation value S iIt is desirable to calculate "A" by subtracting the reference correlation value from the sample correlation value. This removes the offset contained in the sample correlation value, resulting in a correlation value proportional to the concentrations of the gas component to be measured and the interference component, thereby reducing measurement errors. Note that a configuration may be adopted in which the reference correlation value is not subtracted.

[0051] Here, the timing of acquiring the reference light may be simultaneous with the sample light, before or after the measurement, or at any other timing. The intensity-related signal or the reference correlation value of the reference light may be acquired in advance and stored in the storage unit 52c. In addition, a method of acquiring the reference light simultaneously may be, for example, to provide two photodetectors 3 and split the modulated light from the laser light source 2 by a beam splitter or the like, with one being used for measuring the sample light and the other being used for measuring the reference light.

[0052] In this embodiment, the correlation value calculation unit 52b calculates the correlation value based on a plurality of feature signals F i As the characteristic signal F1(t), a function that can more easily capture the waveform characteristics of the logarithmic intensity L(t) than a sine function is used. In the case of a sample gas containing a gas component to be measured and one interference component, it is possible to use two or more characteristic signals F1(t) and F2(t). For example, the two characteristic signals F1(t) and F2(t) may be a function based on a Lorentzian function that is close to the shape of the absorption spectrum and a differential function of the function based on the Lorentzian function. In addition, instead of the function based on the Lorentzian function, a function based on a Voigt function or a function based on a Gaussian function may be used as the characteristic signal. By using such a function as the characteristic signal, a larger correlation value can be obtained than when a sine function is used, and the measurement accuracy can be improved.

[0053] Here, it is desirable to adjust the offset of the characteristic signal so that the DC component is removed, that is, the offset becomes zero when integrated over the modulation period. This makes it possible to remove the effect of an offset being added to the intensity-related signal due to fluctuations in light intensity. Instead of removing the DC component of the characteristic signal, the DC component may be removed from the intensity-related signal, or the DC components may be removed from both the characteristic signal and the intensity-related signal. Alternatively, the characteristic signal may be a sample value of the absorption signal of the gas component and / or interference component to be measured, or a value simulating these.

[0054] In addition, by setting the two feature signals F1(t) and F2(t) as mutually orthogonal orthogonal function sequences or function sequences close to the orthogonal function sequence, the feature of the logarithmic intensity L(t) can be extracted more efficiently, and the concentration obtained by the simultaneous equations described later can be more accurately obtained.

[0055] The storage unit 52c stores, for each of a plurality of temperatures, intensity-related signals and a plurality of characteristic signals F when the gas component to be measured and each interference component are present alone. i The single correlation value, which is the correlation value per unit concentration of the gas component to be measured and each interference component, is stored in the storage unit 100. The single correlation value is calculated by storing a plurality of characteristic signals F i (t) is a plurality of feature signals F used in the correlation value calculation unit 52b. i Same as (t).

[0056] Here, when storing the single correlation value, the storage unit 52c desirably subtracts the reference correlation value from the correlation value when the gas component to be measured and each interference component exist alone, and then stores the corrected single correlation value converted to a unit concentration. This removes the offset contained in the single correlation value, resulting in a correlation value proportional to the concentrations of the gas component to be measured and the interference components, making it possible to reduce measurement errors. Note that a configuration in which the reference correlation value is not subtracted may also be used.

[0057] The concentration calculation section 52d calculates the concentration of the gas component to be measured using the multiple sample correlation values ​​obtained by the correlation value calculation section 52b.

[0058] Specifically, the concentration calculation unit 52d calculates the concentration of the gas component of the measurement target based on the multiple sample correlation values ​​obtained by the correlation value calculation unit 52b and the multiple single correlation values ​​stored in the storage unit 52c corresponding to the measured temperature of the radiation thermometer 4. More specifically, the concentration calculation unit 52d calculates the concentration of the gas component of the measurement target by solving simultaneous equations consisting of the multiple sample correlation values ​​obtained by the correlation value calculation unit 52b, the multiple single correlation values ​​stored in the storage unit 52c corresponding to the measured temperature of the radiation thermometer 4, and the concentrations of the gas component of the measurement target and each interference component. Note that FIG. 5 shows a conceptual diagram of concentration calculation using the single correlation value and the sample correlation value in the concentration calculation unit 52d.

[0059] When the sample gas contains one gas component to be measured (here, NO) and one interference component, the concentration calculation unit 52d calculates the sample correlation values ​​S1' and S2' calculated by the correlation value calculation unit 52b and the single correlation value s in the storage unit 52c corresponding to the temperature measured by the radiation thermometer 4. 1t , s 2t , s 1i , s 2i and the concentration C of the gas component to be measured and each interference component tar , C int Solve the following simultaneous equations consisting of: 1t is the single correlation value of the gas component to be measured in the first characteristic signal, s 2t is the single correlation value of the gas component to be measured in the second characteristic signal, s 1i is the single correlation value of the interference component in the first feature signal, s 2i is the single correlation value of the interference component in the second characteristic signal.

[0060]

number

[0061] This allows the concentration C of the gas component to be measured, free of interference effects, to be calculated by a simple and reliable calculation of solving the simultaneous equations shown above (Equation 2). tar can be determined.

[0062] Even when it is assumed that there are two or more interfering components, the concentration of the gas component to be measured with the interference effects removed can be determined by adding a single correlation value for each interfering component and solving a system of simultaneous equations with the same number of elements as the number of component types.

[0063] <Effects of this embodiment> According to the gas meter device 100 of the present embodiment configured as described above, since the temperature measurement direction 4x of the radiation thermometer 4 is provided along the optical path of the laser light L1, it is possible to measure the average temperature of the sample gas along the optical path of the laser light L1. Therefore, it is possible to measure the concentration of the gas component contained in the sample gas with higher accuracy than with a thermocouple that measures the temperature at one point.

[0064] <Other embodiments> For example, in the above embodiment, the radiation thermometer 4 measures the temperature of the sample gas in the furnace from the same optical window 12b as the reflection mirror 6, but the temperature of the sample gas in the furnace may also be measured from the same optical window 12a as the laser light source 2 and the photodetector 3.

[0065] In addition, although the embodiment described above uses the reflecting mirror 6, the reflecting mirror 6 may not be used. In this case, as shown in FIG. 6, the laser light source 2 is attached to one furnace wall 10a, and the photodetector 3 is attached to the other furnace wall 10b. In this configuration, the radiation thermometer 4 may be configured to measure the temperature of the sample gas in the furnace from the same optical window 12a as the laser light source 2, or may be configured to measure the temperature of the sample gas in the furnace from the same optical window 12b as the photodetector 3. In addition, the radiation thermometer 4 may be configured to measure the temperature of the sample gas in the furnace from an optical window other than the optical window 12a of the laser light source 2 and the optical window 12b of the photodetector 3.

[0066] Although the radiation thermometer 4 in the above embodiment has a built-in bandpass filter 7, it may not have a built-in bandpass filter 7. In this case, the bandpass filter 7 is provided in front of the radiation thermometer 4 (for example, in front of the lens 42).

[0067] The signal processing unit of the above embodiment is not limited to the above embodiment, and may be configured to correct the concentration of the gas component calculated based on the light intensity signal using a calibration curve (correction formula) based on the temperature signal.

[0068] The gas measurement device of the above embodiment uses an infrared laser absorption modulation method, but may use other infrared spectroscopy such as Fourier transform infrared spectroscopy (FTIR) or non-dispersive infrared absorption (NDIR), or may use other laser absorption spectroscopy.

[0069] Although the embodiment has been described as an embodiment in which the sample gas in the furnace is analyzed, the exhaust gas in the flue may be analyzed. In this case, an opening through which the laser light passes is formed in the flue wall of the flue, and the radiation thermometer measures the temperature of the sample gas in the flue through the opening. Specifically, the radiation thermometer measures the temperature of the sample gas in the flue through an optical window provided in the opening.

[0070] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention. [Explanation of symbols]

[0071] 100 Gas measuring device 10. Combustion furnace 10a, 10b...furnace wall 11a, 11b...opening 12a, 12b Optical window L1: Laser light LP...Light path 2. Laser light source 3. Photodetector 4... Radiation thermometer 4x...Temperature measurement direction 5. Signal Processing Section 6. Reflective mirror 7. Bandpass filter

Claims

1. a laser light source that irradiates a laser beam onto the sample gas; a photodetector for detecting the laser light transmitted through the sample gas; a radiation thermometer whose temperature measurement direction is provided along the optical path of the laser light; a signal processing unit that calculates a concentration of a gas component contained in the sample gas based on a light intensity signal obtained by the photodetector and a temperature signal obtained by the radiation thermometer.

2. A device for analyzing sample gas in a furnace or a flue, An opening through which the laser light passes is formed in the furnace wall or the flue wall, The gas measurement device according to claim 1 , wherein the radiation thermometer detects the temperature of the sample gas through the opening.

3. the opening is provided with an optical window through which the laser light passes, The gas measurement device according to claim 2 , wherein the radiation thermometer detects the temperature of the sample gas through the optical window.

4. a reflecting mirror that reflects the laser beam, 4. The gas measuring device according to claim 1, wherein the laser light from the laser light source is reflected by the reflecting mirror and detected by the photodetector.

5. The gas measurement device according to claim 4 , wherein the laser light source and the photodetector are integrated into one unit.

6. The sample gas is a gas generated by combustion, 6. The gas measuring device according to claim 1, wherein the radiation thermometer detects the temperature of the sample gas through a bandpass filter that passes an absorption wavelength band of a gas component generated by combustion.

7. 7. The gas measuring device according to claim 1, which is used to analyze combustion gas in an ammonia combustion furnace that uses ammonia as fuel.

8. The signal processing unit detects nitric oxide (NO), nitrogen dioxide (NO ２ ), nitrous oxide (N ２ O) or ammonia (NH ３ 8. The gas measuring device according to claim 1, wherein the gas measuring device calculates a concentration of at least one of the components listed above.

9. A gas measurement method using a laser light source that irradiates a sample gas with laser light and a photodetector that detects the laser light that has passed through the sample gas, comprising: a radiation thermometer is provided with a temperature measurement direction along the optical path of the laser light to detect the temperature of the sample gas; a gas measuring method for calculating a concentration of a gas component contained in the sample gas based on a light intensity signal obtained by the photodetector and a temperature signal obtained by the radiation thermometer;

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