Detection device, detection method, and detection program

Abstract

High-precision detection of gases using their light absorption properties. [Solution] The gas detection device 10 searches for light source driving conditions that reduce the influence of interfering gases on the measured values, which show the light absorption characteristics of the measured gas, and creates a calibration curve showing the relationship between the measured values ​​and the concentration of the measured gas based on the searched light source driving conditions.

Description

[Technical Field]

[0001] The present invention relates to a detection device, a detection method, and a detection program. [Background technology]

[0002] Laser-irradiated gas detection devices are known that detect a target gas from the measured light by utilizing the unique light absorption characteristics of the gas. For example, laser-irradiated gas detection devices can detect leaks of ammonia (NH3), which is an industrially important but toxic gas. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-035385 [Patent Document 2] Japanese Patent Publication No. 2011-191246 [Patent Document 3] Japanese Patent Publication No. 2022-151664 [Non-patent literature]

[0004] [Non-Patent Document 1] J. Reid, et al., “Applied Physics B” 26, 203-210, 1981 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, it is difficult to detect gases with high accuracy using their light absorption properties. For example, when detecting ammonia leaked into the atmosphere, the absorption wavelengths of water vapor in the atmosphere and ammonia overlap (or "interfere" as appropriate), which can lead to errors in the measured ammonia levels.

[0006] The present invention has been made in view of the above, and aims to detect gases with high precision by utilizing their light absorption properties. [Means for solving the problem]

[0007] A detection device according to one embodiment of the present invention includes a search unit that searches for driving conditions for a light source that reduce the influence of a second gas on a measured value showing the light absorption characteristics of a first gas, and a creation unit that creates a calibration curve showing the relationship between the measured value and the concentration of the first gas based on the searched driving conditions.

[0008] A detection method according to one embodiment of the present invention involves a computer searching for driving conditions for a light source that reduce the influence of a second gas on a measured value showing the light absorption characteristics of a first gas, and then creating a calibration curve showing the relationship between the measured value and the concentration of the first gas based on the searched driving conditions.

[0009] A detection program according to one embodiment of the present invention causes a computer to perform the following processes: search for driving conditions for a light source that reduce the influence of a second gas on a measured value showing the light absorption characteristics of a first gas; and create a calibration curve showing the relationship between the measured value and the concentration of the first gas based on the searched driving conditions. [Effects of the Invention]

[0010] According to the present invention, there is an effect that gases can be detected with high precision by utilizing their light absorption characteristics. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows an example configuration and processing example of a gas detection system according to an embodiment. [Figure 2] This is a block diagram showing examples of the configurations of each device in the gas detection system according to the embodiment. [Figure 3] This figure shows an example of a calibration curve data storage unit of a gas detection device according to an embodiment. [Figure 4]It is a diagram showing an example of a concentration data storage unit of a gas detection device according to an embodiment. [Figure 5] It is a diagram showing a specific example of a light source driving condition search process of a gas detection system according to an embodiment. [Figure 6] It is a diagram showing a specific example of a simulation result by wavelength modulation spectroscopy of a gas detection system according to the related art. [Figure 7] It is a diagram showing a specific example of a simulation result by wavelength modulation spectroscopy of a gas detection system according to an embodiment. [Figure 8] It is a flowchart showing an example of the flow of the entire gas detection system according to an embodiment. [Figure 9] It is a flowchart showing an example of the flow of a light source driving condition management process of a gas detection system according to an embodiment. [Figure 10] It is a flowchart showing an example of the flow of a calibration curve management process of a gas detection system according to an embodiment. [Figure 11] It is a flowchart showing an example of the flow of a measured value management process of a gas detection system according to an embodiment. [Figure 12] It is a flowchart showing an example of the flow of a concentration management process of a gas detection system according to an embodiment. [Figure 13] It is a diagram showing an example of a hardware configuration according to an embodiment.

Mode for Carrying Out the Invention

[0012] Hereinafter, a detection device, a detection method, and a detection program according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below.

[0013] Hereinafter, the configuration and processing of the gas detection system 100 according to the embodiment, the configuration and processing of each device of the gas detection system 100, the flow of the processing of the gas detection system 100, and the effects of the embodiment will be described.

[0014] [1. Configuration and operation of the gas detection system 100] The configuration and processing of the gas detection system 100 according to the embodiment will be described using Figure 1. Figure 1 is a diagram showing an example of the configuration and processing of the gas detection system 100 according to the embodiment. Below, an example of the overall configuration of the gas detection system 100, an example of the processing of the gas detection system 100, and the effects of the gas detection system 100 will be described.

[0015] In this embodiment, an example of detecting ammonia N containing water vapor H in a plant is described, but the type of gas to be detected, the type and number of interfering gases, the purpose of use, and the application field are not particularly limited.

[0016] (1-1. Example of the overall configuration of the gas detection system 100) An example of the overall configuration of the gas detection system 100 will be described. The gas detection system 100 consists of a gas detection device 10. Here, the gas detection device 10 is connected to a predetermined communication network (not shown) via wired or wireless communication. Various communication networks such as the Internet or dedicated lines can be used as the predetermined communication network.

[0017] (1-1-1. Gas detection device 10) The gas detection device 10 is managed by operator O, who is the manager of the plant or production process, and is installed in the plant or production process, for example, on the outer wall of a storage container that stores ammonia N, to detect ammonia N leakage. The gas detection device 10 also measures the concentration of ammonia N using wavelength-modulated spectroscopy with laser irradiation. Note that the gas detection system 100 shown in Figure 1 may include multiple gas detection devices 10. Furthermore, the location where the gas detection device 10 is installed is not particularly limited to the outer wall of a storage container, etc., and can be installed, for example, in any location where ammonia N leakage needs to be detected.

[0018] (1-2. Example of the overall processing of the gas detection system 100) An example of the overall processing of the gas detection system 100 will be described below. Note that the processes in steps S1 to S5 below can be performed in a different order. Also, some of the processes in steps S1 to S5 below may be omitted. Furthermore, the processes in steps S1 to S3 below are performed prior to the detection of leakage of ammonia N stored in the storage container. Furthermore, the processes in steps S4 and S5 below are performed when detecting leakage of ammonia N stored in the reaction vessel.

[0019] (1-2-1. Absorption peak determination process) Firstly, the gas detection device 10 determines the absorption peak of ammonia (N) (step S1). For example, the gas detection device 10 determines the central wavelength λ0 and wavelength modulation width Δλ0 as the absorption peak of ammonia (N) to be detected.

[0020] (1-2-2. Light source driving condition search process) Secondly, the gas detection device 10 searches for light source driving conditions (step S2). For example, the gas detection device 10 searches for a central wavelength λ1 in which the influence of water vapor H is reduced by running a simulation that changes the wavelength with respect to the central wavelength λ0, maximizes the signal-to-noise ratio (SNR), and minimizes the superposition of the absorption wavelengths of ammonia N and water vapor H. The gas detection device 10 also searches for a wavelength modulation width Δλ1 in which the influence of water vapor H is reduced by running a simulation that changes the wavelength modulation width with respect to the wavelength modulation width Δλ0, maximizes the signal-to-noise ratio, and minimizes the superposition of the absorption wavelengths of ammonia N and water vapor H.

[0021] (1-2-3. Calibration curve creation process) Thirdly, the gas detection device 10 creates a calibration curve (step S3). For example, the gas detection device 10 measures ammonia N at multiple known concentrations under light source driving conditions with a central wavelength λ1 and wavelength modulation width Δλ1, and creates a calibration curve showing the relationship between the measured values ​​of ammonia N and their concentrations.

[0022] (1-2-4. Measurement acquisition process) Fourth, the gas detection device 10 obtains a measurement value for ammonia (N) (step S4). For example, the gas detection device 10 is installed on the outer wall of the storage container and measures the air around the storage container when the plant or production process is in operation, obtaining measurement values ​​at regular intervals.

[0023] (1-2-5. Concentration Calculation Process) Fifth, the gas detection device 10 calculates the concentration of ammonia N (step S5). For example, the gas detection device 10 calculates the concentration of ammonia N from measurements taken at regular intervals using the calibration curve that was created.

[0024] At this time, the gas detection device 10 can also notify the operator O of an alarm. For example, if the calculated concentration of ammonia N exceeds a threshold, the gas detection device 10 determines that ammonia N has leaked from the storage container and generates an alarm sound.

[0025] (1-3. Effects of the gas detection system 100) The following section will describe the overview and problems of the gas detection system 100P related to the reference technology, and then explain the effects of the gas detection system 100.

[0026] (1-3-1. Overview of the 100P Gas Detection System) In the gas detection system 100P, the gas detection device 10P, which is a reference technology, comprises a light-emitting unit that irradiates modulated laser light into space, a light-receiving unit that receives measurement light, a control unit that controls the signal system of the light-emitting unit and the light-receiving unit, and a memory unit that stores the wavelength of the laser light and the measurement results. The gas detection device 10P detects the target gas from the measurement light by utilizing the light absorption characteristics unique to the gas. In this case, the gas detection system 100P irradiates the gas with laser light and receives the measurement light reflected by a scatterer placed in the background of the gas (opposite the side from which the laser light is irradiated).

[0027] The following processes are performed in the gas detection system 100P. First, the gas detection device 10P determines the central wavelength λ0 and wavelength modulation width Δλ0 as the absorption peak of ammonia N. Second, the gas detection device 10P determines the central wavelength λ0 and wavelength modulation width 2.2×λ0 as the light source driving conditions. Third, the gas detection device 10P measures ammonia N at multiple known concentrations under the light source driving conditions of central wavelength λ0 and wavelength modulation width 2.2×λ0, and creates a calibration curve showing the relationship between the measured values ​​of ammonia N and the concentration. Fourth, the gas detection device 10P measures the air around the storage container where ammonia N is stored and acquires measured values ​​of ammonia N at regular intervals. Fifth, the gas detection device 10P uses the created calibration curve to calculate the concentration of ammonia N from the measured values ​​acquired at regular intervals.

[0028] (1-3-2. Problems with the 100P Gas Detection System) Ammonia (N) is an industrially important gas but is toxic. Therefore, when using ammonia, rapid detection of leaks is required. Near-infrared (NIR) wavelengths are frequently used as light sources for measuring ammonia using its light absorption properties. Wavelength-modulation spectroscopy (WMS), in particular, is known for its high-sensitivity measurement capabilities and is widely applied.

[0029] In the gas detection system 100P, when measuring ammonia (N) in the near-infrared band using wavelength-modulated spectroscopy, the wavelength selection is limited to the 1.5 μm band due to the absorption spectrum of ammonia (N). The gas detection system 100P selects absorption peaks from among many based on two criteria: from the perspective of sensitivity, the peak with high absorbance; and from the perspective of gas selectivity, the peak that does not overlap with the absorption of other gases, i.e., does not interfere. Therefore, in order to detect leaked ammonia (N) in the gas detection system 100P, it is necessary to select a peak in which the absorption wavelengths of other gases present in the atmosphere at the source of the leak (e.g., air) do not overlap with the absorption wavelength of ammonia (N).

[0030] In the gas detection system 100P, when ammonia (N) leaks into the atmosphere, water vapor (H) interferes with it. However, since the absorption peak of water vapor (H) is predominantly in the 1.5 μm band, it is not possible to select an absorption peak of ammonia (N) that does not interfere with water vapor (H) at all. Therefore, even when measuring at the wavelength of a specific ammonia (N) absorption peak in the gas detection system 100P, the measured value will contain errors originating from water vapor (H), which is a problem.

[0031] Furthermore, in the gas detection system 100P, the concentration corresponding to the received signal in wavelength-modulated spectroscopy is the integrated value of the concentration along the optical path length (column concentration ppm·m). Therefore, a problem with the gas detection system 100P is that the concentration of water vapor H spread throughout the entire atmosphere changes depending on the background, i.e., the placement of the scattering material.

[0032] As described above, the gas detection system 100P has a problem in that it is difficult to improve the accuracy of detecting the target gas (the "measured gas") when interfering gases (the "interfering gases") are present.

[0033] (1-3-3. Overview of the gas detection system 100) The following processes are performed in the gas detection system 100. First, the gas detection device 10 determines the central wavelength λ0 and wavelength modulation width Δλ0 as the absorption peak of ammonia N. Second, the gas detection device 10 searches for the central wavelength λ1 and wavelength modulation width Δλ1 as light source driving conditions by performing a simulation that maximizes the signal-to-noise ratio and minimizes the superposition of the absorption wavelength of ammonia N and the absorption wavelength of water vapor H. Third, the gas detection device 10 measures ammonia N at multiple known concentrations under the light source driving conditions of central wavelength λ1 and wavelength modulation width Δλ1, and creates a calibration curve showing the relationship between the measured values ​​of ammonia N and the concentration. Fourth, the gas detection device 10 measures the air around the reaction vessel where the ammonia N is stored and acquires measured values ​​of ammonia N at regular intervals. Fifth, the gas detection device 10 calculates the concentration of ammonia N from the measured values ​​acquired at regular intervals using the created calibration curve.

[0034] (1-3-4. Effects of the gas detection system 100) The gas detection system 100 has the following effects. Firstly, the gas detection system 100 enables the measurement of ammonia (N) while eliminating errors caused by water vapor (H). Secondly, by reducing the influence of water vapor (H) and reducing the error caused by water vapor (H) in the measured value, it becomes possible to measure ammonia (N) with high accuracy regardless of the measurement position, i.e., the optical path length. In other words, the gas detection system 100 can improve the accuracy of detecting the measured gas even when interfering gases are present.

[0035] Based on the above, the gas detection system 100 can detect gases with high accuracy by utilizing their light absorption characteristics.

[0036] [2. Configuration and operation of each device of the gas detection system 100] Using Figure 2, the configuration and processing of each device in the gas detection system 100 shown in Figure 1 will be explained. Figure 2 is a block diagram showing an example of the configuration of each device in the gas detection system 100 according to the embodiment. Below, an example of the overall configuration of the gas detection system 100 according to the embodiment, as well as an example of the configuration and processing of the gas detection device 10, will be described.

[0037] (2-1. Example of the overall configuration of the gas detection system 100) Using Figure 2, an example of the overall configuration of the gas detection system 100 shown in Figure 1 will be explained. As shown in Figure 2, the gas detection system 100 consists of a gas detection device 10. The gas detection device 10 is connected via a communication network NW, such as the internet or a dedicated line. The gas detection device 10 is installed, for example, on the outer wall of a storage container that stores the gas to be monitored in a plant.

[0038] (2-2. Example configuration and processing of the gas detection device 10) Using Figure 2, an example of the configuration and processing of the gas detection device 10 will be explained. The gas detection device 10 has an input unit 11, an output unit 12, a communication unit 13, a storage unit 14, and a control unit 15.

[0039] (2-2-1. Input section 11) The input unit 11 is responsible for inputting various types of information to the gas detection device 10. For example, the input unit 11 can be implemented as a button or touch panel, and it accepts various types of information to be input to the gas detection device 10.

[0040] (2-2-2. Output section 12) The output unit 12 is responsible for outputting various types of information from the gas detection device 10. For example, the output unit 12 may be implemented as a display or speaker, and it outputs various types of information stored in the gas detection device 10.

[0041] (2-2-3. Communications Section 13) The communication unit 13 is responsible for data communication with other devices. For example, the communication unit 13 performs data communication with each communication device via a router or the like. The communication unit 13 can also perform data communication with terminals (not shown).

[0042] (2-2-4. Storage section 14) The memory unit 14 stores various information that the control unit 15 references when it operates, and various information acquired when the control unit 15 operates. The memory unit 14 is composed of a calibration curve data storage unit 14a and a concentration data storage unit 14b. Here, the memory unit 14 can be implemented as, for example, a semiconductor memory element such as RAM (Random Access Memory) or flash memory, or a storage device such as a hard disk or optical disc. In the example in Figure 2, the memory unit 14 is installed inside the gas detection device 10, but it may be installed outside the gas detection device 10, or multiple memory units may be installed.

[0043] (2-2-4-1. Calibration curve data storage unit 14a) The calibration curve data storage unit 14a stores light source driving condition data and calibration curve data. For example, the calibration curve data storage unit 14a stores light source driving condition data searched by the search unit 15a of the control unit 15, which will be described later. The calibration curve data storage unit 14a also stores calibration curve data created by the creation unit 15b of the control unit 15, which will be described later. Here, an example of the data stored by the calibration curve data storage unit 14a will be explained using Figure 3. Figure 3 is a diagram showing an example of the calibration curve data storage unit 14a of the gas detection device 10 according to the embodiment. In the example in Figure 3, the calibration curve data storage unit 14a has items such as "calibration curve", "measured gas", "interfering gas", "absorption peak", and "light source driving conditions".

[0044] The "calibration curve" shows calibration curve data that illustrates the relationship between the measured value and concentration of the first gas, which is the measured gas. For example, it is mathematical formula data for calculating a straight line or curve that shows the relationship between the ratio of the 2f component to the 1f component of the measured gas (2f / 1f) and the column concentration of the measured gas (ppm·m). The "measured gas" indicates identification information of the measured gas that is being measured, such as the name of the gas or its chemical formula. The "interfering gas" indicates identification information of the interfering gas, which is the second gas that affects the measured value of the first gas. For example, it is the name of the gas or its chemical formula. The "absorption peak" indicates information about the wavelength at which the absorbance of the measured gas shows its maximum value, such as the center wavelength (nm) or wavelength modulation width (nm). The "light source driving conditions" refer to the driving conditions for the light source that reduce the influence of the interfering gas. For example, they are the optimized center wavelength (nm) and wavelength modulation width (nm) obtained by performing simulations that maximize the signal-to-noise ratio while minimizing the superposition of the absorption wavelength of the measured gas and the absorption wavelength of the interfering gas.

[0045] In other words, Figure 3 shows an example in which calibration curve data, represented by {Calibration curve: "Calibration curve #1", Measured gas: "Ammonia", Interfering gas: "Water vapor", Absorption peak: "Center wavelength λ0" / "Wavelength modulation width Δλ0", Light source driving conditions: "Center wavelength λ1" / "Wavelength modulation width Δλ1"}, is stored in the calibration curve data storage unit 14a.

[0046] (2-2-4-2. Concentration data storage unit 14b) The concentration data storage unit 14b stores measurement data and concentration data. For example, the concentration data storage unit 14b stores measurement data acquired by the measurement unit 15c of the control unit 15, which will be described later. The concentration data storage unit 14b also stores concentration data calculated by the calculation unit 15d of the control unit 15, which will be described later. Here, an example of the data stored by the concentration data storage unit 14b will be explained using Figure 4. Figure 4 is a diagram showing an example of the concentration data storage unit 14b of the gas detection device 10 according to the embodiment. In the example in Figure 4, the concentration data storage unit 14b has items such as "monitoring target", "measured gas", "measured value", and "concentration".

[0047] "Monitored object" refers to identification information used to identify the production process of the plant being monitored, such as the identification number or symbol of the plant or its equipment. "Measured gas" refers to identification information of the measured gas, such as the name of the gas or its chemical formula. "Measured value" refers to the light absorption characteristics of the measured gas, such as the 2f component, 1f component, and the ratio of the 2f component to the 1f component, which are frequency components converted from the received signal. "Concentration" refers to the concentration data of the measured gas calculated using a calibration curve from the light absorption characteristics of the measured gas, such as the column concentration (ppm·m) obtained by integrating the concentration (ppm) of the measured gas and the optical path length (m).

[0048] In other words, Figure 4 shows an example in which data such as {Measurement value 1: "2f component #1-1", Measurement value 2: "1f component #1-1", Concentration: "Column concentration #1-1"}, {Measurement value 1: "2f component #1-2", Measurement value 2: "1f component #1-2", Concentration: "Column concentration #1-2"}, {Measurement value 1: "2f component #1-3", Measurement value 2: "1f component #1-3", Concentration: "Column concentration #1-3"}, ... is stored in the concentration data storage unit 14b for the monitored "tank #1" and the measured gas "ammonia".

[0049] (2-2-5. Control Unit 15) The control unit 15 is responsible for controlling the entire gas detection device 10. The control unit 15 consists of a search unit 15a, a creation unit 15b, a measurement unit 15c, and a calculation unit 15d. Here, the control unit 15 can be implemented by electronic circuits such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), or integrated circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0050] (2-2-5-1. Search section 15a) The search unit 15a searches for various types of information. The search unit 15a then stores the searched information in the storage unit 14. The following describes the light source driving condition search process (center wavelength search process, wavelength modulation width search process).

[0051] (Light source driving condition search process) The search unit 15a performs a light source driving condition search process. For example, the search unit 15a searches for light source driving conditions (light source driving conditions) that reduce the influence of the second gas, the interfering gas, on the measured value, which represents the light absorption characteristics of the first gas, the measured gas. Here, the first gas, i.e., the measured gas, is, for example, ammonia (N). The second gas, i.e., the interfering gas, is, for example, water vapor (H).

[0052] (Center wavelength search process) The search unit 15a performs a central wavelength search process as a light source driving condition search process. For example, the search unit 15a searches for an optimized central wavelength by performing a simulation that maximizes the signal-to-noise ratio and minimizes the superposition of the absorption wavelength of the measured gas and the absorption wavelength of the interfering gas. The search unit 15a also searches for an optimized central wavelength λ1 by performing a simulation that changes the wavelength based on the central wavelength λ0 of the absorption peak of the measured gas.

[0053] A specific example of the central wavelength search process is described below. First, the search unit 15a acquires "absorption spectrum N-1," which is the absorption spectrum data of ammonia N at a known concentration. Second, the search unit 15a acquires "absorption spectrum H-1," which is the absorption spectrum data of water vapor H at a known concentration. Third, the search unit 15a determines the wavelength at which the absorbance in "absorption spectrum N-1" is at its maximum as the "central wavelength λ0." Fourth, the search unit 15a performs a simulation to maximize the signal-to-noise ratio and minimize the superposition of the absorption wavelengths of ammonia N and water vapor H by increasing or decreasing the wavelength in "absorption spectrum N-1" and "absorption spectrum H-1," using the wavelength of "central wavelength λ0" as a reference. Fifth, the search unit 15a determines the optimized wavelength based on the simulation results in "absorption spectrum N-1" and "absorption spectrum H-1" as the "central wavelength λ1." Sixth, the search unit 15a stores the "center wavelength λ0" and "center wavelength λ1" in the calibration curve data storage unit 14a.

[0054] (Wavelength modulation width search process) The search unit 15a performs a wavelength modulation width search process as a light source driving condition search process. For example, the search unit 15a searches for an optimized wavelength modulation width by performing a simulation that maximizes the signal-to-noise ratio and minimizes the superposition of the absorption wavelength of the measured gas and the absorption wavelength of the interfering gas. The search unit 15a also searches for an optimized wavelength modulation width Δλ1 by performing a simulation that changes the wavelength modulation width based on a wavelength modulation width Δλ0 obtained by multiplying the full width at half maximum of the absorption peak of the measured gas by a predetermined value.

[0055] A specific example of the wavelength modulation width search process will be explained. First, the search unit 15a acquires "absorption spectrum N-1," which is the absorption spectrum data of ammonia N at a known concentration. Second, the search unit 15a acquires "absorption spectrum H-1," which is the absorption spectrum data of water vapor H at a known concentration. Third, the search unit 15a determines the wavelength at which the absorbance in "absorption spectrum N-1" shows the maximum value as the "center wavelength λ0." Fourth, the search unit 15a determines the wavelength modulation width Δλ0 as the "wavelength modulation width Δλ0," which is obtained by multiplying the full width at half maximum ±0.5λ0(λ0) of the "center wavelength λ0" by a predetermined value "2.2." Fifth, the search unit 15a performs a simulation to maximize the signal-to-noise ratio and minimize the superposition of the absorption wavelengths of ammonia N and water vapor H by increasing or decreasing the wavelength modulation width in the absorption spectrum N-1 and H-1, using the wavelength modulation width Δλ0 as a reference. Sixth, the search unit 15a determines the optimized wavelength modulation width in the absorption spectrum N-1 and H-1 as the wavelength modulation width Δλ1. Seventh, the search unit 15a stores the wavelength modulation width Δλ0 and Δλ1 in the calibration curve data storage unit 14a.

[0056] (2-2-5-2. Creation Section 15b) The creation unit 15b creates various types of information. The creation unit 15b may also store the created information in the storage unit 14. Furthermore, the creation unit 15b may refer to the information stored in the storage unit 14. The calibration curve creation process will be described below.

[0057] (Calibration curve creation process) The creation unit 15b performs calibration curve creation processing. For example, based on the explored light source driving conditions, the creation unit 15b creates a calibration curve that shows the relationship between the measured values ​​and concentrations of the measured gas.

[0058] A specific example of the calibration curve creation process will be described. First, the creation unit 15b refers to the "center wavelength λ1" and "wavelength modulation width Δλ1" as light source driving condition data stored by the calibration curve data storage unit 14a. Second, the creation unit 15b acquires the measurement data of reference samples of multiple known concentrations of ammonia N acquired by the measurement unit 15c under the light source driving conditions of "center wavelength λ1" and "wavelength modulation width Δλ1", namely "2f component / 1f component S-1", "2f component / 1f component S-2", "2f component / 1f component S-3", ... Third, the creation unit 15b acquires the concentration data of reference samples of multiple known concentrations of ammonia N acquired by the measurement unit 15c under the light source driving conditions of "center wavelength λ1" and "wavelength modulation width Δλ1", namely "column concentration S-1", "column concentration S-2", "column concentration S-3", ... Fourth, the creation unit 15b determines "Calibration Curve #1," which is mathematical formula data for a calculation formula showing the relationship between the measured values ​​and concentrations of the measured gas, using combinations of measured value data and concentration data such as {Measured value: "2f component / 1f component S-1", Concentration: "Column concentration S-1"}, {Measured value: "2f component / 1f component S-2", Concentration: "Column concentration S-2"}, {Measured value: "2f component / 1f component S-3", Concentration: "Column concentration S-3"}, ... Fifth, the creation unit 15b stores "Calibration Curve #1" in the calibration curve data storage unit 14a.

[0059] (2-2-5-3. Measuring part 15c) The measurement unit 15c performs various measurements. The measurement unit 15c may also store the outputted measurement results in the storage unit 14. Furthermore, the measurement unit 15c may refer to various information stored in the storage unit 14. The measurement value acquisition process will be described below.

[0060] (Measurement value acquisition process) The measurement unit 15c performs measurement value acquisition processing. For example, based on the searched light source driving conditions, the measurement unit 15c acquires measurement values ​​of the measurement gas in a mixture of the measurement gas and the interference gas. The measurement unit 15c also acquires measurement values ​​of the measurement gas using wavelength modulation spectroscopy with laser light irradiation.

[0061] A specific example of the measurement value acquisition process will be explained. First, the measurement unit 15c refers to the "center wavelength λ1" and "wavelength modulation width Δλ1" as light source driving condition data stored by the calibration curve data storage unit 14a. Second, the measurement unit 15c acquires the measurement value data of an ammonia N sample of unknown concentration, namely "2f component #1-1", "2f component #1-2", "2f component #1-3", ... under the light source driving conditions of the referenced "center wavelength λ1" and "wavelength modulation width Δλ1". Third, the measurement unit 15c stores the acquired ammonia N measurement value data, namely "2f component #1-1", "2f component #1-2", "2f component #1-3", ... in the concentration data storage unit 14b. Fourth, the measurement unit 15c acquires measurement data of an unknown concentration of ammonia N, namely "1f component #1-1", "1f component #1-2", "1f component #1-3", ... under the light source driving conditions of the referenced "center wavelength λ1" and "wavelength modulation width Δλ1". Fifth, the measurement unit 15c stores the acquired ammonia N measurement data, namely "1f component #1-1", "1f component #1-2", "1f component #1-3", ... in the concentration data storage unit 14b.

[0062] (2-2-5-4. Calculation section 15d) The calculation unit 15d calculates various types of information. The calculation unit 15d may store the calculated information in the storage unit 14. Alternatively, the calculation unit 15d may refer to the information stored in the storage unit 14. The concentration calculation process will be described below.

[0063] (Concentration calculation process) The calculation unit 15d performs concentration calculation processing. For example, the calculation unit 15d calculates the concentration of the measured gas based on the acquired measured values ​​of the measured gas and the created calibration curve.

[0064] A specific example of the concentration calculation process will be explained. First, the calculation unit 15d refers to "Calibration curve #1", which is the formula data of the ammonia N calculation formula stored by the calibration curve data storage unit 14a. Second, the calculation unit 15d obtains the measured ammonia N data "2f component #1-1", "2f component #1-2", "2f component #1-3", ... from the concentration data storage unit 14b. Third, the calculation unit 15d obtains the measured ammonia N data "1f component #1-1", "1f component #1-2", "1f component #1-3", ... from the concentration data storage unit 14b. Fourth, the calculation unit 15d takes the measured ammonia N data, "2f component / 1f component #1-1", "2f component / 1f component #1-2", "2f component / 1f component #1-3", ... as input to the formula data of "Calibration curve #1", and outputs the ammonia N concentration data, "Column concentration #1-1", "Column concentration #1-2", "Column concentration #1-3", ... as input. Fourth, the calculation unit 15d stores the output ammonia N concentration data, "Column concentration #1-1", "Column concentration #1-2", "Column concentration #1-3", ... as input to the concentration data storage unit 14b.

[0065] [3. Specific examples of each process of the gas detection system 100] Using Figures 5 to 7, specific examples of each process of the gas detection system 100 according to the embodiment will be described. Below, specific examples of the light source driving condition search process of the gas detection system 100 and specific examples of simulation results by wavelength modulation spectroscopy will be described.

[0066] (3-1. Specific example of light source driving condition search process) A specific example of the light source driving condition search process of the gas detection system 100 will be explained using Figure 5. Figure 5 is a diagram showing a specific example of the light source driving condition search process of the gas detection system 100 according to the embodiment. Below, the absorption spectrum and the light source driving condition determination process of the gas detection system 100P related to the reference technology will be explained, followed by the light source driving condition search process executed by the gas detection device 10.

[0067] (3-1-1. Absorption Spectrum) As shown in the example in Figure 5, the gas detection device 10 performs a light source driving condition search process using the absorption spectra of ammonia (N), the gas to be measured, and water vapor (H), the interfering gas. In the example in Figure 5, the vertical axis of the absorption spectrum is 0.0 to 2.5 × 10 -5 This shows the "absorbance" in the vicinity. In the example in Figure 5, the horizontal axis of the absorption spectrum shows the "wavelength [nm]" in the range of approximately 1531.0 to 1532.4 nm. Note that in the example in Figure 5, ammonia (N) (solid line) represents a column concentration of 1.0 ppm·m, and water vapor (H) (dashed line) represents a column concentration of 1.0 × 10⁻⁶. 4 It is ppm·m.

[0068] (3-1-2. Determination process for light source driving conditions of gas detection system 100P) The process for determining the light source driving conditions of the gas detection system 100P related to the reference technology will be explained. The gas detection device 10P determines the wavelength of the absorption peak, which is the maximum value in the absorption spectrum described above, to be λ0 = 1531.68 nm. Furthermore, in order to maximize the signal-to-noise ratio in wavelength modulation spectroscopy, the gas detection device 10P sets the wavelength modulation width of the light source to approximately 2.2 times the full width at half maximum (FWHM) of the absorption peak. Here, the gas detection device 10P sets the wavelength modulation width Δλ0 of the light source, which maximizes the signal-to-noise ratio from the full width at half maximum, to about 100 pm.

[0069] However, as shown in the example in Figure 5, measuring ammonia (N) under the above conditions also includes the contribution of water vapor (H). Here, assuming that 1.6% (25°C, 50% relative humidity) of water vapor (H) is uniformly distributed in the atmosphere, and that the distance to the background scatterer reflecting the laser light irradiated by the gas detection device 10P is 10 m, then the column concentration for the round trip is 3.2 × 10⁻⁶. 5 This corresponds to ppm·m. This is 32 times the absorbance of water vapor H shown in the example in Figure 5, and simulations show that this results in a measurement error of at least 10% compared to 10 ppm·m of ammonia N.

[0070] (3-1-3. Search process for light source driving conditions of gas detection system 100) The process for searching for light source driving conditions in the gas detection system 100 will now be described. In contrast to the light source driving condition determination process of the gas detection system 100P described above, the gas detection device 10 can change at least one of the center wavelength and wavelength modulation width to search for conditions in which the influence of water vapor H is small as the light source driving conditions. Furthermore, by performing measurements using wavelength modulation spectroscopy with the searched light source driving conditions, the gas detection device 10 can measure ammonia N without errors caused by water vapor H.

[0071] (3-2. Specific examples of simulation results using wavelength modulation spectroscopy) Using Figures 6 and 7, specific examples of simulation results of the gas detection system 100 using wavelength modulation spectroscopy will be explained. Figure 6 is a diagram showing a specific example of simulation results of the gas detection system 100P according to the reference technology using wavelength modulation spectroscopy. Figure 7 is a diagram showing a specific example of simulation results of the gas detection system 100 according to the embodiment using wavelength modulation spectroscopy. Below, the graphs of the simulation results using wavelength modulation spectroscopy will be explained, followed by a comparison and discussion of the simulation results using wavelength modulation spectroscopy.

[0072] (3-2-1. Graph of simulation results) The simulation results using wavelength modulation spectroscopy shown in Figures 6 and 7 will be explained. In the examples in Figures 6 and 7, the vertical axis represents the ratio of the magnitudes of the 2f component to the 1f component (2f / 1f), which is a value proportional to the gas concentration. Here, the magnitudes and phases of the 1f and 2f components are output from the lock-in amplifier by measurement using wavelength modulation spectroscopy at frequencies 1 and 2 times the modulation frequency f. In the examples in Figures 6 and 7, the horizontal axis represents the column concentration of ammonia (N) (ppm·m). In the examples in Figures 6 and 7, the column concentration of water vapor (H) is 0 ppm·m (solid line) and 2.5 × 10⁻⁶. 5 ppm m (long chain line), 5.0×10 5 ppm·m (long dashed line), 7.5 × 10 5ppm·m (dashed line), and 1.0×10 6 ppm·m (dotted line) are varied in five ways to perform the simulation.

[0073] In the example of FIG. 6, as the light source driving conditions according to the prior art, the simulation is performed at a center wavelength λ0 = 1531.675 nm and a wavelength modulation width Δλ0 = 114 pm. Also, in the example of FIG. 7, as the light source driving conditions according to the embodiment, the simulation is performed at a center wavelength λ1 = 1531.650 nm and a wavelength modulation width Δλ1 = 114 pm.

[0074] (3-2-2. Comparison of Simulation Results) As shown in the example of FIG. 6, in the simulation result of the gas detection system 100P according to the prior art, water vapor H on the order of 10 5 ppm·m generates a 2f component comparable to that of ammonia N of 1 to 10 ppm·m.

[0075] On the other hand, as shown in the example of FIG. 7, in the simulation result of the gas detection system 100 according to the embodiment, the 2f component generated by water vapor H on the order of 10 6 ppm·m is smaller than that of ammonia N of 1 ppm·m, so the influence of the 2f component of water vapor H on ammonia N is reduced.

[0076] (3-2-3. Discussion of Simulation Results) From the above, the gas detection system 100 can use the center wavelength and wavelength modulation width of the light source as parameters, perform the simulation of wavelength modulation spectroscopy while changing the parameters, and search for the light source driving conditions that are less affected by water vapor H. Therefore, the gas detection system 100 can reduce the error component of water vapor H included in the measurement value due to the reduced influence of water vapor H, enabling highly accurate measurement.

[0077] Furthermore, while the light source driving conditions related to the reference technology are conditions that maximize the signal-to-noise ratio, the gas detection system 100 can optimize the light source driving conditions not only from the perspective of maximizing the signal-to-noise ratio, but also from the perspective of avoiding or reducing the influence of interfering gases. Although the signal-to-noise ratio may decrease with the gas detection system 100, it is considered particularly useful when avoiding or reducing the influence of interfering gases is a high priority.

[0078] Furthermore, while the above simulation results described an example where the value of the central wavelength λ1 was changed, changing the value of the wavelength modulation width Δλ1 is also considered useful from the perspective of avoiding or reducing the influence of interfering gases.

[0079] [4. Flow of each process in the gas detection system 100] The processing flow of the gas detection system 100 according to the embodiment will be explained using Figures 8 to 12. Below, the overall processing flow of the gas detection system 100 will be explained, followed by a description of each process: calibration curve management, measurement value management, and concentration management.

[0080] (4-1. Overall processing of the gas detection system 100) The overall processing flow of the gas detection system 100 according to the embodiment will be explained using Figure 8. Figure 8 is a flowchart showing an example of the overall processing flow of the gas detection system 100 according to the embodiment. Note that the processes in steps S101 to S104 below can be executed in a different order. Also, some of the processes in steps S101 to S104 below may be omitted.

[0081] (4-1-1. Light source driving condition management process) Firstly, the gas detection system 100 performs light source driving condition management processing (step S101). For example, the gas detection system 100 manages the optimized center wavelength λ1 and wavelength modulation width Δλ1 as light source driving conditions by performing the processing described in steps S201 to S205.

[0082] (4-1-2. Calibration curve management process) Secondly, the gas detection system 100 performs calibration curve management processing (step S102). For example, the gas detection system 100 manages a calibration curve showing the relationship between the measured value and concentration of the measured gas by performing the processing described in steps S301 to S305.

[0083] (4-1-3. Measurement Value Management Process) Thirdly, the gas detection system 100 performs measurement value management processing (step S103). For example, the gas detection system 100 manages the measured values ​​of the gas by performing the processes described in steps S401 to S404.

[0084] (4-1-4. Concentration control process) Fourth, the gas detection system 100 performs a concentration management process (step S104) and then terminates the process. For example, the gas detection system 100 manages the concentration of the measured gas by performing the processes described in steps S501 to S505.

[0085] (4-2. Light source driving condition management process) The flow of the light source drive condition management process of the gas detection system 100 according to the embodiment will be explained using Figure 9. Figure 9 is a flowchart showing an example of the flow of the light source drive condition management process of the gas detection system 100 according to the embodiment. Note that the processes in steps S201 to S205 below can be executed in a different order. Also, some of the processes in steps S201 to S205 below may be omitted.

[0086] (4-2-1. First central wavelength determination process) Firstly, the gas detection device 10 performs a first central wavelength determination process (step S201). For example, the gas detection device 10 determines the wavelength showing the maximum value as the absorption peak of ammonia N as the central wavelength λ0.

[0087] (4-2-2. First wavelength modulation width determination process) Secondly, the gas detection device 10 performs a first wavelength modulation width determination process (step S202). For example, the gas detection device 10 determines the wavelength modulation width Δλ0 as the absorption peak of ammonia N, which is obtained by multiplying the central wavelength λ0 by 2.2.

[0088] (4-2-3. Second central wavelength determination process) Thirdly, the gas detection device 10 performs a second central wavelength determination process (step S203). For example, the gas detection device 10 searches for and determines a central wavelength λ1 in which the influence of water vapor H is reduced by performing a simulation in which the wavelength is varied with respect to the central wavelength λ0 as the light source driving condition for ammonia N, maximizing the signal-to-noise ratio and minimizing the superposition of the absorption wavelength of ammonia N and the absorption wavelength of water vapor H.

[0089] (4-2-4. Second wavelength modulation width determination process) Fourth, the gas detection device 10 performs a second wavelength modulation width determination process (step S204). For example, the gas detection device 10 searches for and determines a wavelength modulation width Δλ1 in which the influence of water vapor H is reduced by performing a simulation that changes the wavelength modulation width with respect to the wavelength modulation width Δλ0 as the light source driving condition for ammonia N, maximizing the signal-to-noise ratio and minimizing the superposition of the absorption wavelength of ammonia N and the absorption wavelength of water vapor H.

[0090] (4-2-5. Light source driving condition data storage process) Fifth, the gas detection device 10 executes the light source driving condition data storage process (step S205) and terminates the light source driving condition management process. For example, the gas detection device 10 stores the determined center wavelength λ1 and wavelength modulation width Δλ1 as light source driving condition data in the calibration curve data storage unit 14a.

[0091] (4-3. Calibration curve management process) The flow of the calibration curve management process of the gas detection system 100 according to the embodiment will be explained using Figure 10. Figure 10 is a flowchart showing an example of the flow of the calibration curve management process of the gas detection system 100 according to the embodiment. Note that the processes in steps S301 to S305 below can be executed in a different order. Also, some of the processes in steps S301 to S305 below may be omitted.

[0092] (4-3-1. Light source driving condition data reference processing) Firstly, the gas detection device 10 performs a light source driving condition data reference process (step S301). For example, the gas detection device 10 references the center wavelength λ1 and the wavelength modulation width Δλ1 as light source driving condition data stored in the calibration curve data storage unit 14a.

[0093] (4-3-2. Processing to acquire the received light signal) Secondly, the gas detection device 10 performs a light reception signal acquisition process (step S302). For example, the gas detection device 10 acquires a light reception signal by irradiating a reference sample of ammonia N of multiple known concentrations with laser light under light source driving conditions of a central wavelength λ1 and wavelength modulation width Δλ1, and receiving the measurement light.

[0094] (4-3-3. Light reception signal conversion process) Thirdly, the gas detection device 10 performs a light-receiving signal conversion process (step S303). For example, the gas detection device 10 converts the acquired light-receiving signal into a ratio of the 2f component to the 1f component (2f / 1f) as a measured value of ammonia N.

[0095] (4-3-4. Determination of calculation formula) Fourth, the gas detection device 10 performs a calculation formula determination process (step S304). For example, the gas detection device 10 determines a calculation formula that shows the relationship between the ratio of component 2f to component 1f (2f / 1f) as a measured value of ammonia N, and the column concentration (ppm·m) as the concentration of ammonia N.

[0096] (4-3-5. Calibration curve data storage process) Fifth, the gas detection device 10 executes calibration curve data storage processing (step S305) and terminates the calibration curve management processing. For example, the gas detection device 10 stores the mathematical formula data of the determined ammonia N calculation formula in the calibration curve data storage unit 14a as calibration curve data.

[0097] (4-4. Measurement Value Management Process) The flow of the measurement value management process of the gas detection system 100 according to the embodiment will be explained using Figure 11. Figure 11 is a flowchart showing an example of the flow of the measurement value management process of the gas detection system 100 according to the embodiment. Note that the processes in steps S401 to S404 below can be executed in a different order. Also, some of the processes in steps S401 to S404 below may be omitted.

[0098] (4-4-1. Light source driving condition data reference processing) Firstly, the gas detection device 10 performs a light source driving condition data reference process (step S401). For example, the gas detection device 10 references the center wavelength λ1 and wavelength modulation width Δλ1 as light source driving condition data stored in the calibration curve data storage unit 14a.

[0099] (4-4-2. Processing to acquire the received light signal) Secondly, the gas detection device 10 performs a light reception signal acquisition process (step S402). For example, the gas detection device 10 acquires a light reception signal by irradiating a monitoring area of ​​a storage container containing ammonia N with laser light under light source driving conditions of a central wavelength λ1 and wavelength modulation width Δλ1, and receiving the measurement light.

[0100] (4-4-3. Light signal conversion process) Thirdly, the gas detection device 10 performs a light-receiving signal conversion process (step S403). For example, the gas detection device 10 converts the acquired light-receiving signal into a ratio of the 2f component to the 1f component (2f / 1f) as a measured value of ammonia N.

[0101] (4-4-4. Measured Data Storage Process) Fourth, the gas detection device 10 performs measurement data storage processing (step S404) and terminates the measurement data management processing. For example, the gas detection device 10 stores the ratio of the 2f component to the 1f component (2f / 1f) of the converted ammonia N as measurement data in the concentration data storage unit 14b.

[0102] (4-5. Concentration control process) The flow of the concentration management process of the gas detection system 100 according to the embodiment will be explained using Figure 12. Figure 12 is a flowchart showing an example of the flow of the concentration management process of the gas detection system 100 according to the embodiment. Note that the processes in steps S501 to S505 below can be executed in a different order. Also, some of the processes in steps S501 to S505 below may be omitted.

[0103] (4-5-1. Calibration curve data reference processing) Firstly, the gas detection device 10 performs calibration curve data reference processing (step S501). For example, the gas detection device 10 references the mathematical formula data for calculating ammonia N as calibration curve data stored in the calibration curve data storage unit 14a.

[0104] (4-5-2. Processing of measured data reference) Secondly, the gas detection device 10 performs measurement data reference processing (step S502). For example, the gas detection device 10 references the ratio of the 2f component to the 1f component of ammonia N (2f / 1f) as measurement data stored in the concentration data storage unit 14b.

[0105] (4-5-3. Concentration Calculation Process) Thirdly, the gas detection device 10 performs a concentration calculation process (step S503). For example, the gas detection device 10 calculates the column concentration (ppm·m) as the concentration of ammonia N by inputting the ratio of the 2f component to the 1f component of ammonia N (2f / 1f) into the mathematical formula data of the ammonia N calculation formula.

[0106] (4-5-4. Alarm notification processing) Fourth, the gas detection device 10 performs an alarm notification process (step S504). For example, if the calculated column concentration of ammonia N (ppm·m) exceeds a threshold, the gas detection device 10 notifies the operator O of the abnormality by generating an alarm sound indicating ammonia N leakage.

[0107] (4-5-5. Concentration Data Storage Processing) Fifth, the gas detection device 10 performs concentration data storage processing (step S505) and terminates the concentration management process. For example, the gas detection device 10 stores the calculated ammonia N column concentration (ppm·m) as concentration data in the concentration data storage unit 14b.

[0108] [5. Effects of the Embodiment] The effects of the embodiment will now be described. Below, effects 1 to 9 corresponding to the processing according to the embodiment will be described.

[0109] (5-1. Effect 1) Firstly, in the process according to the embodiment described above, the gas detection device 10 searches for light source driving conditions that reduce the influence of interfering gases on the measured values, which represent the light absorption characteristics of the measured gas, and creates a calibration curve showing the relationship between the measured values ​​and the concentration of the measured gas based on the searched light source driving conditions. Therefore, in this process, gases can be detected with high accuracy by utilizing their light absorption characteristics.

[0110] (5-2. Effect 2) Secondly, in the process according to the embodiment described above, the gas detection device 10 acquires measured values ​​of the measured gas in a mixture of the measured gas and the interfering gas based on the searched light source driving conditions, and calculates the concentration of the measured gas based on the acquired measured values ​​of the measured gas and the created calibration curve. Therefore, in this process, by calculating the concentration of the measured gas in real time, the gas can be detected with high accuracy by utilizing its light absorption characteristics.

[0111] (5-3. Effect 3) Thirdly, in the process according to the embodiment described above, the gas detection device 10 searches for an optimized central wavelength λ1 by performing a simulation that maximizes the signal-to-noise ratio and minimizes the superposition of the absorption wavelength of the measured gas and the absorption wavelength of the interfering gas. Therefore, in this process, by optimizing the central wavelength λ as a light source driving condition, the gas can be detected with high accuracy by utilizing its light absorption characteristics.

[0112] (5-4. Effect 4) Fourth, in the process according to the embodiment described above, the gas detection device 10 searches for an optimized central wavelength λ1 by performing a simulation that changes the wavelength based on the central wavelength λ0 of the absorption peak of the measured gas. Therefore, in this process, by efficiently optimizing the central wavelength λ as a light source driving condition based on the absorption peak, the gas can be detected with high accuracy by utilizing the light absorption characteristics.

[0113] (5-5. Effect 5) Fifth, in the process according to the embodiment described above, the gas detection device 10 searches for an optimized wavelength modulation width Δλ1 by performing a simulation that maximizes the signal-to-noise ratio and minimizes the superposition of the absorption wavelength of the measured gas and the absorption wavelength of the interfering gas. Therefore, in this process, by optimizing the wavelength modulation width Δλ as a light source driving condition, the gas can be detected with high accuracy by utilizing its optical absorption characteristics.

[0114] (5-6. Effect 6) Sixth, in the process according to the embodiment described above, the gas detection device 10 searches for an optimized wavelength modulation width Δλ1 by performing a simulation that changes the wavelength modulation width Δλ0, which is obtained by multiplying the full width at half maximum of the absorption peak of the measured gas by a predetermined value. Therefore, in this process, by efficiently optimizing the wavelength modulation width Δλ as a light source driving condition based on the absorption peak, the gas can be detected with high accuracy by utilizing the light absorption characteristics.

[0115] (5-7. Effect 7) Seventh, in the process according to the embodiment described above, the gas detection device 10 acquires measured values ​​of the gas to be measured using wavelength-modulated spectroscopy, which irradiates with laser light. Therefore, in this process, by applying wavelength-modulated spectroscopy, which is capable of detecting the gas to be measured with high sensitivity, the gas can be detected with even higher precision by utilizing its light absorption characteristics.

[0116] (5-8. Effect 8) Eighth, in the process according to the embodiment described above, the gas to be measured is ammonia. Therefore, in this process, industrially important ammonia (N) can be detected with high accuracy by utilizing its light absorption characteristics.

[0117] (5-9. Effect 9) Ninth, in the process according to the embodiment described above, the interfering gas is water vapor. Therefore, in this process, by reducing the influence of water vapor H contained in the atmosphere and interfering in the near-infrared region, the gas can be detected with high accuracy by utilizing its light absorption characteristics.

[0118] [6. Examples of applications of the embodiment] Examples of applications of the embodiment will be described below. Examples of applications 1 to 5 of the embodiment will be described below.

[0119] (6-1. Application Example 1) As an application example 1 of the embodiment, the measurement gas can be applied not only to ammonia (N) according to the embodiment, but also to various gases produced in the plant, such as hydrocarbons, oxygen, carbon monoxide, and carbon dioxide.

[0120] (6-2. Application Example 2) As an application example 2 of the embodiment, the interference gas can be applied not only to water vapor H according to the embodiment, but also to various gases such as nitrogen, oxygen, and carbon dioxide contained in the atmosphere.

[0121] (6-3. Application Example 3) As an application example 3 of the embodiment, the interference gas can be applied not only to one type according to the embodiment, but also to two or more types of various gases.

[0122] (6-4. Application Example 4) As an application example 4 of the embodiment, the wavelength band can be applied not only to the 1.5 μm band according to the embodiment, but also to other wavelength bands.

[0123] (6-5. Application Example 5) As an application example 5 of the embodiment, the detection target can be applied not only to the gas according to the embodiment, but also to various solids and liquids that have light absorption properties.

[0124] [7. System] Unless otherwise specified, the processing procedures, control procedures, specific names, and various data and parameters shown in the above documents and drawings may be changed at will.

[0125] Furthermore, the components of each illustrated device are functionally conceptual and do not necessarily need to be physically configured as shown. In other words, the specific forms of distribution and integration of each device are not limited to those shown. That is, all or part of them can be functionally or physically distributed and integrated in any unit according to various loads and usage conditions.

[0126] Furthermore, each processing function performed by each device may be implemented, in whole or in part, by a CPU and a program executed for analysis by that CPU, or by hardware using wired logic.

[0127] [8. Hardware] A hardware configuration example of the gas detection device 10 will be described. Note that other devices can have a similar hardware configuration. Figure 13 shows a hardware configuration example according to this embodiment. As shown in Figure 13, the gas detection device 10 includes a communication device 10a, an HDD (Hard Disk Drive) 10b, memory 10c, and a processor 10d. Furthermore, the components shown in Figure 13 are interconnected by a bus or the like.

[0128] The communication device 10a is a network interface card or the like, and communicates with other servers. The HDD 10b stores programs and databases that operate the functions shown in Figure 2.

[0129] The processor 10d operates a process that performs the functions described in Figure 2 by reading a program that performs the same processing as each processing unit shown in Figure 2 from the HDD 10b or the like and loading it into memory 10c. For example, this process performs the same functions as each processing unit of the gas detection device 10. Specifically, the processor 10d reads a program that has the same functions as the search unit 15a, creation unit 15b, measurement unit 15c, calculation unit 15d, etc. from the HDD 10b or the like. Then, the processor 10d executes a process that performs the same processing as the search unit 15a, creation unit 15b, measurement unit 15c, calculation unit 15d, etc.

[0130] Thus, the gas detection device 10 operates as a device that performs various processing methods by reading and executing the program according to the embodiment. Furthermore, the gas detection device 10 can also achieve the same functionality as the embodiment described above by reading the program from the recording medium using a media reading device and executing the read program. Note that the program according to the embodiment is not limited to being executed by the gas detection device 10. For example, the present invention can be similarly applied when another computer or server executes the program, or when they cooperate to execute the program.

[0131] The program according to this embodiment can be distributed via a network such as the Internet. Furthermore, this program can be recorded on a computer-readable recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO (Magneto-Optical disk), or DVD (Digital Versatile Disc), and executed by reading it from the recording medium by a computer.

[0132] [9. Other] Some examples of the combinations of technical features that will be disclosed are listed below.

[0133] (1) A detection device comprising: a search unit that searches for driving conditions for a light source that reduce the influence of a second gas on a measured value showing the light absorption characteristics of a first gas; and a creation unit that creates a calibration curve showing the relationship between the measured value and the concentration of the first gas based on the searched driving conditions.

[0134] (2) The detection device according to (1), further comprising: a measuring unit that acquires the measured value of the first gas in a mixed gas of the first gas and the second gas based on the explored driving conditions; and a calculating unit that calculates the concentration of the first gas based on the acquired measured value of the first gas and the calibration curve created.

[0135] (3) The detection device according to (1) or (2), wherein the search unit searches for an optimized central wavelength by performing a simulation that maximizes the signal-to-noise ratio and minimizes the superposition of the absorption wavelength of the first gas and the absorption wavelength of the second gas.

[0136] (4) The detection device according to (3), wherein the search unit searches for an optimized central wavelength by performing a simulation in which the wavelength is changed with reference to the wavelength of the absorption peak of the first gas.

[0137] (5) The detection device according to any one of (1) to (4), wherein the search unit searches for an optimized wavelength modulation width by performing a simulation that maximizes the signal-to-noise ratio and minimizes the superposition of the absorption wavelength of the first gas and the absorption wavelength of the second gas.

[0138] (6) The detection device according to (5), wherein the search unit searches for an optimized wavelength modulation width by performing a simulation that changes the wavelength modulation width based on a wavelength modulation width obtained by multiplying the full width at half maximum of the absorption peak of the first gas by a predetermined value.

[0139] (7) The detection device according to (2), wherein the measuring unit acquires the measurement value of the first gas using wavelength modulation spectroscopy by irradiating with laser light.

[0140] (8) The detection apparatus according to any one of (1) to (7), wherein the first gas is ammonia, hydrocarbon, oxygen, carbon monoxide, or carbon dioxide.

[0141] (9) The detection apparatus according to any one of (1) to (8), wherein the second gas is water vapor, nitrogen, oxygen, or carbon dioxide.

[0142] (10) A detection method that performs a process in which a computer searches for driving conditions for a light source that reduce the influence of a second gas on a measurement value showing the light absorption characteristics of a first gas, and creates a calibration curve showing the relationship between the measurement value and the concentration of the first gas based on the searched driving conditions.

[0143] (11) A detection program that causes a computer to search for driving conditions for a light source that reduce the influence of a second gas on a measured value showing the light absorption characteristics of a first gas, and to create a calibration curve showing the relationship between the measured value and the concentration of the first gas based on the searched driving conditions. [Explanation of symbols]

[0144] 10. Gas detection device 10a Communication device 10b HDD 10c memory 10d processor 11 Input section 12 Output section 13 Communications Department 14 Storage section 14a Calibration curve data storage unit 14b Concentration data storage unit 15 Control Unit 15a Exploration Department 15b Creation Section 15c Measuring section 15d Calculation Unit 100 Gas Detection System H water vapor N ammonia Network O Operator

Claims

1. A search unit searches for driving conditions for a light source that reduce the influence of a second gas on the measured values ​​showing the light absorption characteristics of a first gas, Based on the explored driving conditions, a creation unit creates a calibration curve showing the relationship between the measured values ​​and concentration of the first gas, A detection device equipped with the following features.

2. A measuring unit that acquires the measured value of the first gas in a mixed gas of the first gas and the second gas based on the explored driving conditions, A calculation unit that calculates the concentration of the first gas based on the obtained measurement values ​​of the first gas and the created calibration curve, The detection device according to claim 1, further comprising:

3. The search unit, The optimized central wavelength is searched by performing a simulation that maximizes the signal-to-noise ratio and minimizes the superposition of the absorption wavelengths of the first gas and the second gas. The detection device according to claim 1.

4. The search unit, The optimized central wavelength is searched by performing a simulation in which the wavelength is varied with reference to the wavelength of the absorption peak of the first gas. The detection device according to claim 3.

5. The search unit, The optimized wavelength modulation width is searched by performing a simulation that maximizes the signal-to-noise ratio and minimizes the superposition of the absorption wavelengths of the first gas and the second gas. The detection device according to claim 1.

6. The search unit, The optimized wavelength modulation width is searched by performing a simulation in which the wavelength modulation width is varied based on a wavelength modulation width obtained by multiplying the full width at half maximum of the absorption peak of the first gas by a predetermined value. The detection device according to claim 5.

7. The aforementioned measuring unit is The measurement values ​​of the first gas are obtained using wavelength-modulated spectroscopy with laser light irradiation. The detection device according to claim 2.

8. The first gas is ammonia, hydrocarbons, oxygen, carbon monoxide, or carbon dioxide. The detection device according to any one of claims 1 to 7.

9. The second gas is water vapor, nitrogen, oxygen, or carbon dioxide. The detection device according to any one of claims 1 to 7.

10. Computers We explored the driving conditions for the light source that reduce the influence of the second gas on the measured values ​​showing the light absorption characteristics of the first gas. Based on the explored driving conditions, a calibration curve is created showing the relationship between the measured values ​​and the concentration of the first gas. A detection method for executing a process.

11. On the computer, We explored the driving conditions for the light source that reduce the influence of the second gas on the measured values ​​showing the light absorption characteristics of the first gas. Based on the explored driving conditions, a calibration curve is created showing the relationship between the measured values ​​and the concentration of the first gas. A detection program that initiates a process.

Images