WO2022270201A1

WO2022270201A1 - Gas analysis device

Info

Publication number: WO2022270201A1
Application number: PCT/JP2022/021337
Authority: WO
Inventors: 卓司生田; 健太郎石田; 佳洋横田; 雅彦藤原
Original assignee: 株式会社堀場製作所
Priority date: 2021-06-25
Filing date: 2022-05-25
Publication date: 2022-12-29
Also published as: JPWO2022270201A1

Abstract

A gas analysis device (100) is provided with a measurement cell (1), a light source (3), a separation member (5), a first sensor unit (7, 7', 7''), a second sensor unit (9, 9', 9''), and a calculation unit (111). A sample gas (Gs) is introduced into the measurement cell (1). The light source (3) radiates measurement light (Lm) inside the measurement cell (1). The separation member (5) splits the measurement light (Lm) having passed through the measurement cell (1) into first component light (CL1) that includes a component in a first wavelength range and third component light (CL3) that includes at least second component light including a component in a second wavelength range. The calculation unit (111) calculates information relating to a component gas in a low concentration range, on the basis of the intensity of the first component light (CL1) measured by the first sensor unit (7, 7', 7''). In addition, the calculation unit (111) calculates information relating to the component gas in a high concentration range, on the basis of the intensity of the second component light (CL2) measured by the second sensor unit (9, 9', 9'').

Description

gas analyzer

The present invention relates to a gas analyzer that analyzes component gases contained in sample gas.

Conventionally, predetermined component gases (e.g., sulfur oxides (SO _x ), nitrogen oxides (NO _x ), As a gas analyzer for analyzing carbon dioxide (CO ₂ ) and carbon monoxide (CO), there is known one that utilizes the light absorption characteristics of the component gas (see Patent Document 1, for example).

This gas analyzer includes a measurement cell into which a sample gas is introduced, a light source that emits measurement light toward the measurement cell, and a sensor that measures the intensity of the measurement light that has passed through the measurement cell.

In the above-described gas analyzer, the measurement light is emitted toward the measurement cell while the sample gas is introduced into the measurement cell, and the intensity of the measurement light after passing through the sample gas in the measurement cell is measured by the sensor. Analysis of the component gas (calculation of information about the component gas) is performed based on the measured intensity of the measurement light.

JP 2012-68164 A

In the gas analyzer described above, the component gas is analyzed on the premise that the relationship between the intensity of the measurement light after passing through the sample gas and the information about the concentration of the component gas does not change from a predetermined relationship. will be However, when analyzing a component gas over a wide concentration range, the relationship between the intensity of the measurement light measured by the sensor and the information about the concentration of the component gas may vary from the predetermined relationship. For example, when the concentration of the component gas is high, the amount of change in the intensity of the measurement light with respect to the change in the concentration of the component gas is smaller than the amount of change in the intensity of the measurement light when the concentration of the component gas is low.

When analyzing a constituent gas on the assumption that the relationship between the intensity of the measurement light measured by the sensor and the information about the concentration of the constituent gas does not change, if the relationship changes over a certain concentration range, the analysis An error occurs in the result.

It is conceivable to correct the change in the relationship between the intensity of the measurement light measured by the sensor and the information about the concentration of the component gas electrically or by a predetermined calculation. However, if the relationship is extremely variable, even electrical or computational techniques cannot compensate for this variation.

In addition, the above problem is solved by separately providing an apparatus for low-concentration analysis in which the optical path length of light passing through the component gas is long and an apparatus for high-concentration analysis in which the optical path length of light passing through the component gas is shortened. It is also possible to solve it by However, in this case, two separate devices are provided, which causes problems such as an increase in the size of the analysis device, an increase in the cost of the analysis device, and an increase in power consumption of the analysis device.

An object of the present invention is to accurately analyze component gases over a wide concentration range in an analyzer that analyzes component gases using the light absorption characteristics of component gases.

A plurality of aspects will be described below as means for solving the problem. These aspects can be arbitrarily combined as needed.
A gas analyzer according to one aspect of the present invention is an apparatus for analyzing component gases contained in a sample gas. A gas analyzer includes a measurement cell, a light source, a separation member, a first sensor section, a second sensor section, and a calculation section.
A sample gas is introduced into the interior of the measurement cell. A light source emits measuring light into the interior of the measuring cell.
The separation member separates the measurement light that has passed through the measurement cell into first component light and third component light including at least the second component light.
The first component light includes components in the first wavelength range. The first wavelength range includes the wavelength range most absorbed by the component gas in one specific wavelength range absorbed by the component gas and is narrower than the specific wavelength range. The second component light includes components in a second wavelength range that is included in the specific wavelength range but not included in the first wavelength range.
The first sensor unit measures the intensity of the first component light.
The second sensor section measures the intensity of the second component light.
The calculation unit calculates information about the component gas in the low concentration range based on the intensity of the first component light measured by the first sensor unit. Also, the calculation unit calculates information about the component gas in the high concentration range based on the intensity of the second component light measured by the second sensor unit.

As a result, since the relationship between the intensity of the component light measured by the sensor unit and the information about the concentration of the component gas does not change from the predetermined relationship over a wide concentration range, the wide concentration range included in the sample gas can be obtained. component gas can be analyzed with high accuracy.

The above gas analyzer may further include a gas switching unit. The gas switching unit switches and introduces a sample gas and a reference gas into the measurement cell. A reference gas is a gas that does not contain component gases. Since the reference gas does not contain any component gas, the intensity of the measurement light when the reference gas is introduced into the measurement cell becomes a background to the intensity of the measurement light when the sample gas is introduced into the measurement cell. Therefore, for example, when calculating the information on the component gas, the information on the component gas can be calculated more accurately by considering the intensity of the measurement light when the reference gas is introduced into the measurement cell.

The separation member may be a bandpass filter that transmits the first component light and reflects the third component light. Thereby, the first component light containing the components in the first wavelength range and the third component light containing components outside the first wavelength range can be reliably separated.

The first sensor section may include a first pneumatic detector capable of measuring the intensity of light in a specific wavelength range. This allows selective measurement of the intensity of the first component light containing the component in the specific wavelength range.

The first sensor section may include a first transmission filter that transmits light in a specific wavelength range, and a thermal solid-state sensor or semiconductor sensor that measures the intensity of light that has passed through the first transmission filter. As a result, even if the sensor itself does not have wavelength selectivity, it is possible to selectively measure the intensity of the first component light containing components in a specific wavelength range.

The second sensor section may include a second pneumatic detector capable of measuring the intensity of light in a specific wavelength range. Thereby, it is possible to selectively measure the intensity of the second component light including the component in the specific wavelength range among the third component light.

The second sensor section may include a second transmission filter that is provided between the separation member and the second pneumatic detector and that transmits light in a specific wavelength range. As a result, only the second component light containing the component in the specific wavelength range among the third component light can enter the second pneumatic detector, so that the selectivity of the second sensor unit for the second component light can be further enhanced. can.

The second sensor section may include a third transmission filter that transmits light in a specific wavelength range, and a thermal solid-state sensor or semiconductor sensor that measures the intensity of light that has passed through the third transmission filter. As a result, only the second component light containing a component in a specific wavelength range out of the third component light can be incident on the sensor. can be measured.

The above gas analyzer may further include a fourth transmission filter. A fourth transmission filter is provided between the measurement cell and the separation member and transmits light in a specific wavelength range. Thereby, the light containing only the components in the specific wavelength range in the measurement light can be incident on the separation member. As a result, the separation member can separate the first component light and the component light (that is, the second component light) containing the component in the specific wavelength range among the third component light.

When the gas analyzer includes a fourth transmission filter, the first sensor section and the second sensor section may be thermal solid-state sensors or semiconductor sensors that measure the intensity of light in a specific wavelength range. This eliminates the need to provide a transmission filter for each of the first sensor section and the second sensor section, so that the first sensor section and the second sensor section can be configured at low cost.

In the above analyzer, the relationship between the intensity of the component light measured by the sensor unit and the information about the concentration of the component gas does not change from a predetermined relationship over a wide concentration range. It can accurately analyze component gases in a wide range of concentrations.

The figure which shows the structure of an analyzer. FIG. 4 is a diagram showing an example of a transmission spectrum and a reflection spectrum of a separation member; The figure which shows the intensity spectrum of each component light. The figure which shows the structure of a control part. 4 is a flow chart showing an analysis operation of a component gas; FIG. 4 is a diagram showing the configuration of a gas analyzer of modification 1; FIG. 10 is a diagram showing the configuration of a gas analyzer according to Modification 2; The figure which shows the connection relationship of a sampling unit and an analyzer.

1. First Embodiment (1) Configuration of Gas Analysis Apparatus The configuration of a gas analysis apparatus 100 will be described below with reference to FIG. FIG. 1 is a diagram showing the configuration of a gas analyzer. The gas analyzer 100 can detect, for example, the atmosphere, exhaust gas flowing through a flue, process gas generated in various processes, exhaust gas generated by combustion of waste, exhaust gas generated by combustion of a boiler, gas filled in a gas cylinder, and the like. This device analyzes the component gas contained in the sample gas Gs by using the light absorption characteristics of the component gas. Specifically, the gas analyzer 100 emits the measurement light Lm into a space alternately filled with the sample gas Gs and the reference gas Gr, and the intensity of the measurement light Lm after passing through the sample gas Gs and the reference gas Gr is is measured, and based on the difference between the intensity of the measurement light Lm measured when the sample gas Gs is filled and the intensity of the measurement light Lm measured when the reference gas Gr is filled, the sample Information (for example, concentration) on the component gas contained in the gas Gs is calculated. The reference gas Gr is a gas containing no component gas. The reference gas Gr is, for example, nitrogen gas (N ₂ ), purified air (from which component gases or the like are removed), or the like.

Since the reference gas Gr does not contain any component gas, the intensity of the measurement light Lm that has passed through the space filled with the reference gas Gr is background to the intensity of the measurement light Lm that has passed through the space filled with the sample gas Gs. becomes. Therefore, based on the difference between the intensity of the measurement light Lm that has passed through the space filled with the sample gas Gs and the intensity of the measurement light Lm that has passed through the space filled with the reference gas Gr, By calculating the information about the component gas, the information about the component gas can be calculated more accurately.

Component gases that can be analyzed by the gas analyzer 100 include, for example, carbon dioxide (CO ₂ ), carbon monoxide (CO), sulfur dioxide (SO ₂ ), nitrogen oxide (NO _x ) gas (e.g., monoxide nitrogen (NO), nitrogen dioxide ₍ NO2), nitrous oxide ₍ N2O), etc.), hydrocarbon gases (eg, methane ₍ CH4), propane ₍ _C3H8 ), etc.).

A specific configuration of the gas analyzer 100 will be described below. In the gas analyzer 100 described below, the component gas is carbon dioxide (CO ₂ ). Even when the other gases listed above are used as component gases, the gas analyzer 100 has substantially the same configuration as the configuration described below. As shown in FIG. 1, the analyzer includes a measurement cell 1, a gas switching unit 2, a light source 3, a separation member 5, a first sensor unit 7, a second sensor unit 9, a control unit 11, Mainly provide

The measurement cell 1 is a hollow member into which the sample gas Gs or the reference gas Gr can be introduced. The measurement cell 1 has an inlet 1a through which the sample gas Gs or the reference gas Gr is introduced, and an outlet 1b through which the introduced gas is discharged to the outside. Infrared transmission windows (for example, calcium fluoride crystal windows) are attached to both ends of the measuring cell 1 in the length direction to form a sealing structure. A space inside the hollow member into which the sample gas Gs or the reference gas Gr is introduced is called a measurement space Sp.

In the above-described measurement cell 1, for example, a pump (not shown) connected to the outlet 1b sucks the sample gas Gs or the reference gas Gr into the measurement space Sp through the inlet 1a. can be introduced into Alternatively, the sample gas Gs or the reference gas Gr can be introduced into the measurement space Sp by pressurizing it. In this case, it is not particularly necessary to suck gas from the discharge port 1b.

The optical path length of the measurement light Lm in the measurement space Sp of the measurement cell 1 is such that the measurement light Lm passing through the measurement space Sp is sufficiently absorbed by the component gas even if the concentration of the component gas contained in the sample gas Gs is low. It is preferable to have a length of a certain degree. Therefore, the measuring cell 1 has a certain length.

If a sufficient length of the measurement cell 1 cannot be ensured, for example, a plurality of mirrors may be provided in the measurement space Sp to multiple-reflect the measurement light Lm so that the measurement light Lm travels back and forth in the measurement space Sp a plurality of times. You may let

The gas switching unit 2 alternately switches and introduces the sample gas Gs and the reference gas Gr into the measurement space Sp of the measurement cell 1 at a constant time cycle. For example, the gas switching unit 2 enables gas communication between the gas line to which the sample gas Gs is supplied and the introduction port 1a, or enables gas communication between the gas line to which the reference gas Gr is supplied and the introduction port 1a. or a solenoid valve capable of alternately switching between

The light source 3 is provided at one end of the measuring cell 1 in the length direction. The light source 3 radiates into the measurement space Sp of the measurement cell 1 measurement light Lm containing at least a component in a wavelength range that can be absorbed by the component gas. Since carbon dioxide is used as the component gas in this embodiment, the measurement light Lm in this embodiment is infrared light. Any light source can be used as the light source 3 as long as it can emit infrared light. Note that the wavelength range of the measurement light Lm can be appropriately changed according to the type of component gas. In addition, any light source can be used as the light source 3 according to the wavelength range that the measurement light Lm should have.

The separation member 5 converts the measurement light Lm that has passed through the measurement space Sp of the measurement cell 1 into a first component light CL1 used for analyzing component gases in the low concentration range and a second component light CL1 used for analyzing component gases in the high concentration range. and a third component light CL3 including at least the light CL2. In this embodiment, the separation member 5 is a bandpass filter having a transmission spectrum and a reflection spectrum as shown in FIG. FIG. 2 is a diagram showing an example of the transmission spectrum and reflection spectrum of the separation member.

Specifically, the wavelength range (referred to as a specific wavelength range) of one specific absorption spectrum (absorbance) absorbed by the component gas is λ1 or more and λ2 or less, and the peak of the absorption spectrum is λ3 ( λ1<λ3<λ2) or more and λ4 (λ1<λ4<λ2) or less, the separation member 5 transmits light in the wavelength range of λ3 or more and λ4 or less. In this way, the separation member 5 transmits component light that includes a wavelength range that is most absorbed by the component gas in the specific wavelength range and that includes components in the first wavelength range narrower than the specific wavelength range. The "wavelength range most absorbed by a component gas" includes the peak position of one particular absorption spectrum (absorbance) of the component gas.

The component light containing the components in the first wavelength range most absorbed by the component gas is sufficiently absorbed even if the concentration of the component gas contained in the sample gas Gs is low. It also exhibits high sensitivity to Further, when the concentration of the component gas is low, the relationship between the information on the concentration of the component gas and the intensity of the component light measured by the sensor is constant. Therefore, in the present embodiment, the component light transmitted by the separation member 5 is defined as the first component light CL1 used for analyzing component gases in the low concentration range. Specifically, as shown in FIG. 3, the first component light CL1 has intensity within a wavelength range of λ3 or more and λ4 or less (that is, the first wavelength range). FIG. 3 is a diagram showing the intensity spectrum of each component light.

On the other hand, the reflection spectrum of the separation member 5 has characteristics opposite to the above transmission spectrum. That is, the separation member 5 separates the component light (referred to as third component light CL3) from the measurement light Lm that has passed through the measurement space Sp of the measurement cell 1, other than the first component light CL1 including the component in the first wavelength range. reflect. Specifically, as shown in FIG. 3, the third component light CL3 includes component light having a wavelength less than λ3 and component light having a wavelength greater than λ4 in the measurement light Lm. That is, the first component light CL1 is not included in the third component light CL3.

As shown in FIG. 2, the reflection spectrum of the separating member 5 partially includes components in a specific wavelength range. That is, the third component light CL3 reflected by the separation member 5 includes component light that is not included in the first wavelength range but is included in the specific wavelength range. Since this component light is included in a specific wavelength range, it is absorbed by the component gas, but the sensitivity to the component gas is low. This is because this component light is component light in the "bottom" wavelength range of the specific wavelength range, and light absorption by the component gas is smaller than that of the first component light CL1.

However, this component light is sufficiently absorbed if the concentration of the component gas is high. Further, even if the concentration of the component gas is high, the relationship between the information on the concentration of the component gas and the intensity of the component light measured by the sensor is constant. Therefore, in the present embodiment, the component light not included in the first wavelength range but included in the specific wavelength range, out of the third component light CL3, is used for the analysis of the component gas in the high-concentration range. and Specifically, as shown in FIG. 3, the second component light CL2 has a wavelength range of λ1 or more and λ3 or less and a wavelength range of λ4 or more and λ2 or less (within the second wavelength range). has a significant intensity in

In this way, the separation member 5, which is a bandpass filter, can reliably separate the first component light CL1 containing components in the first wavelength range and the third component light CL3 containing components outside the first wavelength range. When the component gas is carbon dioxide and the measurement light Lm is infrared light, the band-pass filter having the characteristics described above may be, for example, a thin film of germanium (Ge) and monoxide on a silicon (Si) substrate. A bandpass filter having a multi-layer structure in which thin films of silicon (SiO) are alternately deposited can be used.

Note that the configuration of the bandpass filter can be appropriately changed according to the wavelength range of the measurement light Lm, the type of component gas, and the like. Also, the separation member 5 may be any member other than the bandpass filter as long as it can separate the measurement light Lm into the first component light CL1 and the third component light CL3 (second component light CL2).

The first sensor unit 7 measures the intensity of the first component light CL1 transmitted by the separation member 5. In this embodiment, the first sensor unit 7 has a sealed cell 7b containing a component gas (carbon dioxide in this embodiment), and a first pneumatic sensor capable of measuring the intensity of light in the above specific wavelength range. Detector 7a. By using the first pneumatic detector 7a as the first sensor section 7, the intensity of the first component light CL1 included in the specific wavelength range can be selectively measured. The above-mentioned "selectivity" (or selectivity) means that while the measurement sensitivity is high for the intensity of light in a specific wavelength range, the measurement sensitivity for other light intensities is low.

The second sensor unit 9 measures the intensity of the second component light CL2 included in the third component light CL3 reflected by the separating member 5. In this embodiment, the second sensor unit 9 has a sealed cell 9b containing a component gas (carbon dioxide in this embodiment), and a second pneumatic sensor capable of measuring the intensity of light in the above specific wavelength range. Detector 9a. By using the second pneumatic detector 9a as the second sensor unit 9, it is possible to selectively measure the intensity of the second component light CL2 including the component in the specific wavelength range in the third component light CL3.

As shown in FIG. 1, the second sensor section 9 may have a second transmission filter 9c. The second transmission filter 9c is provided between the separation member 5 and the second pneumatic detector 9a, and transmits light in a specific wavelength range. By providing the second transmission filter 9c in the second sensor section 9, only the second component light CL2 including the component in the specific wavelength range out of the third component light CL3 reflected by the separation member 5 is subjected to the second pneumatic detection. can be incident on the device 9a. As a result, the selectivity of the second sensor section 9 for the second component light CL2 can be further enhanced.

The second transmission filter 9c is, for example, a bandpass filter having a configuration similar to that of the separation member 5. However, since the second transmission filter 9c allows the second component light CL2 to enter the second pneumatic detector 9a, it is configured to transmit light in a wider wavelength range than the first wavelength range transmitted by the separation member 5. .

If the second pneumatic detector 9a has high selectivity for the second component light CL2, the second transmission filter 9c is not particularly necessary.

The control unit 11 is a computer system composed of a CPU, storage devices (RAM, ROM, etc.), various interfaces (eg, D/A converter, A/D converter, etc.), a display, and the like. The control unit 11 controls the gas analyzer 100 and performs various types of information processing. A part or all of the control and information processing performed by the control unit 11 may be implemented by a program stored in the storage device of the computer system that constitutes the control unit 11 . The control unit 11 may implement part or all of the control and information processing of the gas analyzer 100 by hardware. Also, the control unit 11 may be a SoC (System on Chip) in which a CPU, a storage device, various interfaces, etc. are formed on one chip.

As shown in FIG. 4, the control unit 11 has a calculation unit 111, a storage unit 113, and a display unit 115. FIG. 4 is a diagram showing the configuration of the control unit.

The calculation unit 111 converts an electrical signal related to the intensity of the first component light CL1 measured by the first sensor unit 7 and an electrical signal related to the intensity of the second component light CL2 measured by the second sensor unit 9. Information processing is performed, and the amount of absorption of the first component light CL1 and the second component light CL2 by the component gas is calculated. The calculation unit 111 calculates information about the concentration of the component gas contained in the sample gas Gs based on the absorption amount.

In the present embodiment, the calculation unit 111 calculates information about the concentration of the component gas in the low concentration range based on the intensity of the first component light CL1 measured by the first sensor unit 7, and outputs the information to the second sensor unit 9. Information about the concentration of the component gas in the high concentration range is calculated based on the measured intensity of the second component light CL2. Specifically, the calculation unit 111 calculates the first calibration curve C1 representing the relationship between the information about the concentration of the component gas and the intensity of the first component light CL1, and the first component light CL1 measured by the first sensor unit 7. can be used to calculate information about the constituent gases in the low concentration range. On the other hand, the calculation unit 111 calculates the second calibration curve C2 representing the relationship between the information about the concentration of the component gas and the intensity of the second component light CL2, and the intensity of the second component light CL2 measured by the second sensor unit 9. can be used to calculate information about the constituent gases in the high concentration range.

As described above, the intensity of the first component light CL1 is measured by the first sensor unit 7, and the intensity of the second component light CL2 is measured by the second sensor unit 9. That is, the intensities of the first component light CL1 and the second component light CL2 are measured by different sensors. Also, the first component light CL1 and the second component light CL2 have different sensitivities to the component gases. Therefore, the first calibration curve C1 and the second calibration curve C2 are created separately.

The storage unit 113 is all or part of a storage area of a storage device that constitutes the control unit 11, and stores set values, various parameters, and the like used in the gas analyzer 100. Specifically, the storage unit 113 stores the first calibration curve C1 and the second calibration curve C2.

The display unit 115 is a display (for example, a liquid crystal display, an organic EL display, etc.) that constitutes the control unit 11 . The display unit 115 displays various information about the gas analyzer 100 such as analysis results of component gases.

(2) Analyzing Operation of Component Gas Using Gas Analyzing Apparatus Hereinafter, using FIG. 5, an analyzing operation of a component gas using the gas analyzing apparatus 100 having the above configuration will be described. FIG. 5 is a flow chart showing the analysis operation of component gases. First, the sample gas Gs or the reference gas Gr are alternately introduced into the measuring space Sp of the measuring cell 1 . After that, the light source 3 emits the measuring light Lm toward the measuring cell 1 in step S1.

The measurement light Lm emitted from the light source 3 passes through the measurement space Sp into which the sample gas Gs or the reference gas Gr is introduced. When the sample gas Gs is introduced into the measurement space Sp, the measurement light Lm passes through the measurement space Sp while being absorbed by the component gases contained in the sample gas Gs. On the other hand, when the reference gas Gr is introduced into the measurement space Sp, the measurement light Lm passes through the measurement space Sp without being absorbed. This is because the reference gas Gr does not contain any component gas.

The measurement light Lm that has passed through the measurement cell 1 into which the sample gas Gs and the reference gas Gr are alternately introduced is incident on the separation member 5 . The separation member 5 separates (transmits) the first component light CL<b>1 from the incident measurement light Lm and causes the first component light CL<b>1 to enter the first sensor section 7 . Further, the separation member 5 separates (reflects) the third component light CL3 (second component light CL2) from the measurement light Lm and causes it to enter the second sensor section 9 .

Next, in step S2, the first pneumatic detector 7a of the first sensor section 7 detects the first component light CL1. The first pneumatic detector 7a detects the intensity of the first component light CL1 that has passed through the measurement space Sp filled with the sample gas Gs and the intensity of the first component light CL1 that has passed through the measurement space Sp filled with the reference gas Gr. Outputs a signal corresponding to the difference in intensity.

Also, the second pneumatic detector 9a of the second sensor unit 9 detects the second component light CL2 included in the third component light CL3. The second pneumatic detector 9a detects the intensity of the second component light CL2 that has passed through the measurement space Sp filled with the sample gas Gs and the intensity of the second component light CL2 that has passed through the measurement space Sp filled with the reference gas Gr. Outputs a signal corresponding to the difference in intensity.

The calculation unit 111 calculates the intensity of the first component light CL1 detected after passing through the measurement space Sp filled with the sample gas Gs, which is output from the first pneumatic detector 7a, and the measurement space Sp filled with the reference gas Gr. A signal corresponding to the difference between the intensity of the first component light CL1 that has passed through and the intensity of the sample gas Gs and the reference gas Gr when they pass through the measurement cell is inputted.

In addition, the calculation unit 111 calculates the intensity of the second component light CL2 that has passed through the measurement space Sp filled with the sample gas Gs, which is output from the second pneumatic detector 9a, and the measurement space Sp filled with the reference gas Gr. A signal corresponding to the intensity difference between the sample gas Gs and the reference gas Gr of the detected second component light CL2 when passing through the measurement cell is inputted. The calculation unit 111 analyzes the component gas based on the input signal.

In analyzing the component gas, the calculation unit 111 determines in step S3 whether or not the concentration of the component gas contained in the sample gas Gs is estimated to be equal to or higher than a predetermined concentration. The "predetermined concentration" that is the criterion for this determination is, for example, in which concentration range the first calibration curve C1 and the second calibration curve C2 are constant (or changes are small and can be regarded as constant), If it is within the concentration range, it can be determined as appropriate by considering whether significant measurement results can be obtained by the second sensor unit 9 and the like.

The determination of whether or not the concentration of the component gas is estimated to be equal to or higher than a predetermined concentration is made, for example, by a signal corresponding to the intensity of the first component light CL1 and/or a signal corresponding to the intensity of the second component light CL2. This can be done by actually calculating the concentration of the component gas from the signal and determining whether the calculated concentration is equal to or higher than a predetermined concentration.

In addition, for example, whether or not the signal corresponding to the intensity of the first component light CL1 and/or the signal corresponding to the intensity of the second component light CL2 is equal to or greater than a predetermined threshold (or equal to or less than the threshold). It is also possible to determine whether or not the concentration of the component gas contained in the sample gas Gs is estimated to be equal to or higher than a predetermined concentration.

As a result of the above determination, when it is estimated that the concentration of the component gas is not equal to or higher than the predetermined concentration ("No" in step S3), the calculation unit 111, in step S4, outputs from the first pneumatic detector 7a Information about the concentration of the component gas is calculated based on the signal corresponding to the intensity of the first component light CL1 and the first calibration curve C1. For example, the calculation unit 111 may apply the intensity of the first component light CL1 output from the first pneumatic detector 7a to the first calibration curve C1 representing the relationship between the intensity of the first component light CL1 and the concentration of the component gas. By substituting the corresponding signal value, the concentration of the component gas in the low concentration range lower than the predetermined concentration can be calculated.

On the other hand, if it is estimated that the concentration of the component gas is equal to or higher than the predetermined concentration ("Yes" in step S3), the calculation unit 111, in step S5, determines the second component gas output from the second pneumatic detector 9a. Information about the concentration of the component gas is calculated based on the signal corresponding to the intensity of the light CL2 and the second calibration curve C2. For example, the computing unit 111 adds the intensity of the second component light CL2 output from the second pneumatic detector 9a to the second calibration curve C2 representing the relationship between the intensity of the second component light CL2 and the concentration of the component gas. By substituting corresponding signal values, it is possible to calculate the concentration of the component gas in a high concentration range of a predetermined concentration or more.

As described above, the first component light CL1 contains the component in the first wavelength range that is most absorbed by the component gas, so it exhibits high sensitivity even to low-concentration component gases. That is, if the first component light CL1 is used, significant measurement results can be obtained by the first sensor unit 7 even if the concentration of the component gas is low. Further, when the concentration of the component gas is low, the relationship between the intensity of the first component light CL1 measured by the first sensor unit 7 and the information regarding the concentration of the component gas matches the first calibration curve C1. Therefore, by calculating information about the concentration of the component gas in the low concentration range based on the intensity of the first component light CL1 measured by the first sensor unit 7, the component gas in the low concentration range can be accurately analyzed.

On the other hand, the second component light CL2 includes a component in the second wavelength range that includes the specific wavelength range absorbed by the component gas but does not include the first wavelength range. is lower than the first component light CL1. However, the second component light CL2 exhibits significant sensitivity to the component gases if the concentration of the component gases is high. That is, if the concentration of the component gas is high, significant measurement results can be obtained by the second sensor unit 9 using the second component light CL2. Further, in the range where the concentration of the component gas is high, the relationship between the intensity of the second component light CL2 measured by the second sensor section 9 and the information regarding the concentration of the component gas matches the second calibration curve C2. Therefore, by calculating information about the concentration of the component gas in the high concentration range based on the intensity of the second component light CL2 measured by the second sensor unit 9, the component gas in the high concentration range can be accurately analyzed.

As described above, in the gas analyzer 100, the relationship between the intensity of the component light measured by the sensor unit and the information about the concentration of the component gas is the first calibration curve C1 and the second calibration curve C1 over a wide concentration range of the component gas. 2 match the standard curve C2. That is, the relationship between the intensity of the component light measured by the sensor unit and the information about the concentration of the component gas does not change from the predetermined relationship over a wide concentration range. As a result, the gas analyzer 100 can accurately analyze component gases in a wide concentration range contained in the sample gas Gs.

(3) Modification 1
In the above-described first embodiment, the first sensor unit 7 is the first pneumatic detector 7a, and the second sensor unit 9 is the second sensor unit 7a in order to provide selectivity for light in a specific wavelength range that is absorbed by the component gas. A pneumatic detector 9a was used. However, the first sensor section 7 and the second sensor section 9 can be realized with other configurations as long as they have selectivity for light in a specific wavelength range.

For example, as shown in FIG. 6, the first sensor section 7' of the gas analyzer 100 of Modification 1 has a first transmission filter 7a' and a first sensor element 7b'. FIG. 6 is a diagram showing the configuration of the gas analyzer of Modification 1. As shown in FIG.

The first transmission filter 7a' is arranged between the separation member 5 and the first sensor element 7b', and transmits light in a specific wavelength range. The first transmission filter 7a' is, for example, a bandpass filter having a configuration similar to that of the separation member 5 described above. The first transmission filter 7a' preferably has a property of transmitting light in a wavelength range wider than the first wavelength range transmitted by the separation member 5. As shown in FIG.

The first sensor element 7b' measures the intensity of light that has passed through the first transmission filter 7a'. Since the first transmission filter 7a' transmits only the light in the specific wavelength range, the first sensor element 7b' itself does not have to be particularly selective to the light in the specific wavelength range. The first sensor element 7b' is, for example, a thermal solid-state sensor, a semiconductor sensor, or a quantum semiconductor sensor.

Further, the second sensor section 9' has a third transmission filter 9a' and a second sensor element 9b'. The third transmission filter 9a' is arranged between the separation member 5 and the second sensor element 9b' and transmits light in a specific wavelength range. The third transmission filter 9a' is a bandpass filter having the same properties as the first transmission filter 7a'.

The second sensor element 9b' measures the intensity of light that has passed through the third transmission filter 9a'. Since the third transmission filter 9a' transmits only the light in the specific wavelength range, the second sensor element 9b' itself does not have to be particularly selective to the light in the specific wavelength range. The second sensor element 9b' is, for example, a thermal solid-state sensor, a semiconductor sensor, or a quantum semiconductor sensor.

In Modified Example 1, even if the first sensor element 7b' and the second sensor element 9b' themselves do not have selectivity with respect to the specific wavelength range, the first component light CL1 and the second component light CL2 containing components in the specific wavelength range are detected. Intensity can be selectively measured.

One of the first sensor units 7, 7' or the second sensor units 9, 9' is composed of the above transmission filter and sensor element, and the other is a pneumatic sensor that measures the intensity of light in a specific wavelength range. It may be used as a detector.

(4) Modification 2
Further, as another modified example 2, as shown in FIG. 7, the gas analyzer 100 further includes a fourth transmission filter 13, the first sensor section 7'' is configured with a third sensor element 7a'', The second sensor section 9'' may be composed of the fourth sensor element 9a''. FIG. 7 is a diagram showing the configuration of a gas analyzer according to Modification 2. As shown in FIG.

The fourth transmission filter 13 is provided between the measurement cell 1 and the separation member 5, and transmits light within a specific wavelength range. The fourth transmission filter 13 is, for example, a bandpass filter having a configuration similar to that of the separation member 5 described above. The fourth transmission filter 13 preferably has a property of transmitting light in a wavelength range wider than the first wavelength range transmitted by the separation member 5 .

By providing the fourth transmission filter 13 between the measurement cell 1 and the separation member 5 , the light containing only the components in the specific wavelength range in the measurement light Lm can enter the separation member 5 . As a result, the separation member 5 can reliably separate the first component light CL1 and the component light (that is, the second component light CL2) including the component in the specific wavelength range among the third component light CL3.

The third sensor element 7a'' measures the intensity of the light (that is, the first component light CL1) that has passed through the fourth transmission filter 13 and passed through the separation member 5. Since the fourth transmission filter 13 transmits only the light in the specific wavelength range, the third sensor element 7a'' itself does not have to be particularly selective to the light in the specific wavelength range. The third sensor element 7a'' is, for example, a thermal solid-state sensor, a semiconductor sensor, or a quantum semiconductor sensor.

The fourth sensor element 9a'' measures the intensity of the light transmitted through the fourth transmission filter 13 and reflected by the separation member 5 (that is, the second component light CL2). Since the fourth transmission filter 13 transmits only the light in the specific wavelength range, the fourth sensor element 9a'' itself need not have any particular selectivity for the light in the specific wavelength range. The fourth sensor element 9a'' is, for example, a thermal solid-state sensor, a semiconductor sensor, or a quantum semiconductor sensor.

The third sensor element 7a'' and the fourth sensor element 9a'' may be the same type of sensor element, or may be different sensor elements. Also, one or both of the third sensor element 7a'' and the fourth sensor element 9a'' may be a pneumatic detector selective to a specific wavelength range.

In Modification 2, since it is not necessary to provide a transmission filter for transmitting light in a specific wavelength range in each of the first sensor section and the second sensor section, the first sensor section and the second sensor section can be configured at low cost.

2. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the invention. In particular, multiple embodiments and modifications described herein can be arbitrarily combined as required.
(A) As shown in FIG. 8, the gas analyzer 100 (introduction port 1a) samples a gas containing the sample gas Gs from a flue or pipe, and measures the measurement space Sp of the gas analyzer 100 (i.e., It may be connected to a sampling unit 101 which introduces into the measuring cell 1). FIG. 8 is a diagram showing the connection relationship between the sampling unit and the analyzer.

The sampling unit 101 includes, for example, a probe 1011 that samples gas flowing through a flue or pipe, a collection filter 1013 that collects dust contained in the sampled gas, and a pretreatment device that preprocesses the sampled gas. 1015 (comprising, for example, an electric cooler, a drain separator, a tube pump, and a mist catcher to remove sulfuric acid mist, salt, etc.).

(B) The gas analyzer 100 may include a comparison cell and an optical intermittent mechanism. A comparison cell is a cell filled with a gas that does not absorb the measurement light Lm. The light interrupting mechanism is a mechanism for switching whether or not to introduce the measurement light Lm into the measurement cell 1 and the comparison cell at the same time. Examples of such a light intermittence mechanism include a mechanism combining a lighting light source for the measurement cell 1, a lighting light source for the comparison cell, and a chopper, a blinking light source for the measurement cell 1, and a blinking light source for the comparison cell. A mechanism that combines the The light source may be a single light source capable of simultaneously introducing the measurement light Lm into the measurement cell 1 and the comparison cell. Alternatively, the light interrupting mechanism may be a mechanism that alternately introduces the measurement light Lm into the measurement cell 1 and the comparison cell.

In this case, the calculator 111 calculates the difference between the intensity of the measurement light Lm (that is, the first component light CL1 and the second component light CL2) that has passed through the measurement cell 1 and the intensity of the measurement light Lm that has passed through the comparison cell. Analyze the constituent gases based on Thereby, the background component included in the measurement result of the measurement light Lm after passing through the measurement cell 1 is subtracted, and the analysis gas can be analyzed with higher accuracy. As a result, the reference gas Gr becomes unnecessary. Further, the gas switching unit 2 for alternately switching between the sample gas Gs and the reference gas Gr into one measuring cell 1 is not required.

(C) Information about the component gas calculated based on the first component light CL1 and the second component light CL2 is not limited to information about the concentration of the component gas. For example, the information about the component gas may be a signal notifying that the component gas contained in the sample gas is out of a predetermined concentration range.

In this case, the signal notifying that the concentration of the component gas has fallen below the predetermined concentration range can be calculated based on the intensity of the first component light CL1 measured by the first sensor section 7. On the other hand, the signal notifying that the concentration of the component gas has reached or exceeded the predetermined concentration range is calculated based on the intensity of the second component light CL2 measured by the second sensor section 9 .

(D) If the sample gas Gs is, for example, exhaust gas emitted from various combustion plants, the information about the component gas may be a control signal for controlling combustion in the combustion plant. In this case, the calculation unit 111 communicates with the control system (control panel) of the combustion plant, and outputs information regarding the calculated component gas to the control system.

In this case, the control signal required when the concentration of the component gas becomes low can be calculated based on the intensity of the first component light CL1 measured by the first sensor section 7. On the other hand, the control signal required when the concentration of the component gas becomes high is calculated based on the intensity of the second component light CL2 measured by the second sensor section 9. FIG.

Further, the information on the component gas (control signal for controlling combustion in the combustion plant) is obtained by the intensity of the first component light CL1 measured by the first sensor unit 7 and the intensity of the second component light CL1 measured by the second sensor unit 9. You may calculate based on the intensity|strength of CL2. For example, the calculation unit 111 obtains the information about the component gas as f(X)+g(Y) (f(X): function of the intensity of the first component light CL1 measured by the first sensor unit 7, g(Y) : a function of the intensity of the second component light CL2 measured by the second sensor unit 9).

The present invention can be widely applied to gas analyzers that analyze component gases contained in sample gas.

100 gas analyzer 1 measurement cell Sp measurement space

1a introduction port

1b discharge port 2 gas switching unit 3 light source 5 separation members 7, 7', 7'' first sensor unit 7a first pneumatic detector 7b sealed cell 7a' 1 Transmission Filter 7b' First Sensor Element 7a'' Third Sensor Elements 9, 9', 9'' Second Sensor Section 9a Second Pneumatic Detector 9b Sealing Cell 9a' Third Transmission Filter 9b' Second Sensor Element 9a'' Fourth sensor element 9c Second transmission filter 11 Control unit 111 Operation unit 113 Storage unit 115 Display unit C1 First calibration curve C2 Second calibration curve 13 Fourth transmission filter 101 Sampling unit 1011 Probe 1013 Collection filter 1015 Front Processing device Lm Measurement light CL1 First component light CL2 Second component light CL3 Third component light Gs Sample gas Gr Reference gas

Claims

A device for analyzing a component gas contained in a sample gas,
a measuring cell into which the sample gas is introduced;
a light source that emits measurement light inside the measurement cell;
A first wavelength range that includes a wavelength range that is most absorbed by the component gas in one specific wavelength range that is absorbed by the component gas and that is narrower than the specific wavelength range. and a third component light that includes at least a second component light that includes a component in a second wavelength range that is included in the specific wavelength range but not included in the first wavelength range. a separating member that separates;
a first sensor unit that measures the intensity of the first component light;
a second sensor unit that measures the intensity of the second component light;
Information about the component gas in the low concentration range is calculated based on the intensity of the first component light measured by the first sensor unit, and the intensity of the second component light measured by the second sensor unit is calculated. a calculation unit that calculates information about the component gas in the high concentration range based on
A gas analyzer, comprising:
The gas analyzer according to claim 1, further comprising a gas switching unit for switching and introducing the sample gas and the reference gas that does not contain the component gas inside the measurement cell.
The gas analyzer according to claim 1 or 2, wherein the separation member is a bandpass filter that transmits the first component light and reflects the third component light.
The gas analyzer according to any one of claims 1 to 3, wherein said first sensor section includes a first pneumatic detector capable of measuring the intensity of light in said specific wavelength range.
3. The first sensor unit includes a first transmission filter that transmits light in the specific wavelength range, and a thermal solid-state sensor or semiconductor sensor that measures the intensity of the light that has passed through the first transmission filter. 4. The gas analyzer according to any one of 1 to 3.
The gas analyzer according to any one of claims 1 to 5, wherein said second sensor section includes a second pneumatic detector capable of measuring the intensity of light in said specific wavelength range.
7. The gas analyzer according to claim 6, wherein said second sensor section includes a second transmission filter provided between said separation member and said second pneumatic detector and transmitting light in said specific wavelength range. .
3. The second sensor unit includes a third transmission filter that transmits light in the specific wavelength range, and a thermal solid-state sensor or semiconductor sensor that measures the intensity of the light that has passed through the third transmission filter. 6. The gas analyzer according to any one of 1 to 5.
The gas analysis device according to any one of claims 1 to 8, further comprising a fourth transmission filter provided between said measurement cell and said separation member and transmitting light in said specific wavelength range.
The gas analyzer according to claim 9, wherein the first sensor section and the second sensor section are thermal solid-state sensors or semiconductor sensors that measure the intensity of light in the specific wavelength range.