JP2018100902A - Analyzer, analysis system, analysis method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce effects of the measured value of strength of measurement light on pressure fluctuations in a measurement space in a gas analyzer equipped with a pneumatic detector.SOLUTION: An analyzer 100 comprises a light source 3a, a pneumatic detector 5 and a correction unit 95. The light source 3a outputs measurement light Lm to a measurement space Sp where a measurement object gas Gs is present. The pneumatic detector 5 includes sealed cells 51a, 51b in which a filler gas Ge is filled in, and a measurement unit 53 for measuring the strength of the measurement light Lm passing through the measurement space Sp and entering the sealed cells 51a, 51b. The correction unit 95 corrects the measured value of strength of the measurement light Lm by a correction factor C calculated on the basis of the dependency of the absorption spectrum of the measurement object gas Gs on the pressure of the measurement space Sp and the dependency of the pneumatic detector 5 on the measurement sensitive wavelength of the measurement light Lm.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a gas analysis apparatus including a pneumatic detector, an analysis system including the analysis apparatus, a gas analysis method using the analysis apparatus, and a program for causing a computer to execute the analysis method.

  Conventionally, a cell in which an enclosed gas having light absorption characteristics similar to or the same as the measurement target gas is sealed, and a measurement unit that measures the intensity of light that has passed through the space in which the measurement target gas exists and the above cell. A pneumatic detector is known. The pneumatic detector measures not only the gas to be measured but also the intensity of light that has passed through a sealed gas having an absorption characteristic similar to or the same as that of the gas to be measured, so that it is difficult to detect the influence of gases other than the gas to be measured. As a result, information on the measurement target gas can be measured with high sensitivity and high selectivity.

  Using the characteristics of the above pneumatic detector, Patent Document 1 discloses a measurement cell into which a measurement target gas is introduced, an infrared light source that irradiates the measurement cell with infrared light, and a red light that has passed through the measurement cell. An infrared gas analyzer including a pneumatic detector for measuring the intensity of external light is disclosed. With this infrared gas analyzer, it is possible to accurately analyze the measurement target gas present in the measurement cell.

JP 2002-131230 A

In the gas analyzer described above, the pressure in the measurement space formed in the measurement cell varies according to, for example, the gas inlet and / or outlet pressure of the measurement cell. In general, since the inlet and / or outlet of the measurement cell is connected to the atmosphere, the pressure in the measurement space is susceptible to atmospheric pressure fluctuations.
When the pressure in the measurement space fluctuates, it means that the density of the gas present in the measurement cell fluctuates, so even if the concentration of the gas to be measured in the measurement space is the same, it is measured by the detector. The intensity of the measurement light varies according to the variation of the pressure in the measurement space.

  In order to correct the influence of the measurement value of the measurement light intensity due to the pressure in the measurement space, the conventional gas analyzer is based on the fluctuation of the gas density in the measurement cell relative to the pressure fluctuation in the measurement cell. Using a coefficient indicating that the intensity of the measurement light measured by the detector varies by 1% when the fluctuation of 1 kPa changes, the measurement value of the intensity of the measurement light measured by the detector is corrected, The measurement target gas was analyzed using the correction value.

  However, in a gas analyzer equipped with a pneumatic detector, even if correction is performed using the coefficient derived based only on the above gas density variation, the analysis result of the measurement target gas depends on the pressure in the measurement space. I was affected.

  An object of the present invention is to reduce the influence on the analysis result with respect to the pressure fluctuation in the measurement space in a gas analyzer equipped with a pneumatic detector.

An analyzer according to an aspect of the present invention includes a light source, a pneumatic detector, and a correction unit. The light source outputs measurement light to the measurement space where the measurement target gas exists. The pneumatic detector includes an encapsulated cell in which an encapsulated gas that absorbs light in a wavelength range including at least a part of the wavelength range in which the measurement target gas absorbs, and measurement light that passes through the measurement space and enters the encapsulated cell. And a measuring unit for measuring the intensity of the.
The correction unit uses a correction coefficient calculated based on the dependency of the absorption spectrum of the measurement target gas on the pressure in the measurement space and the dependency of the measurement light of the measurement light of the pneumatic detector on the wavelength. Correct intensity measurements.
In this way, in an analyzer equipped with a pneumatic detector, by using a correction factor that takes into account not only the effect of gas density in the measurement space but also the dependence of the measurement light of the pneumatic detector on the wavelength of the measurement sensitivity. The influence of the measurement value of the measurement light intensity on the pressure fluctuation in the measurement space can be reduced.

  The correction coefficient may be a coefficient indicating that the measurement value of the intensity of the measurement light varies at a rate smaller than 1 percent when the pressure in the measurement space varies by 1 kilopascal. Thus, the correction coefficient can be a coefficient that considers not only the influence of the gas density in the measurement space but also the influence of the measurement sensitivity in the pneumatic detector.

  The correction coefficient may have a value specific to the measurement target gas. Thereby, a correction coefficient can be made into an appropriate value according to measurement object gas.

  The pressure in the measurement space may be atmospheric pressure or a pressure in the vicinity thereof. As a result, the influence of the pressure in the measurement space that fluctuates at or near atmospheric pressure can be reduced using the correction coefficient.

  The measurement target gas and the sealed gas may be the same gas. Thereby, the measurement sensitivity with respect to measurement object gas of a pneumatic detector can be increased.

  The gas to be measured may be a gas selected from any of carbon monoxide, carbon dioxide, hydrocarbon gas, nitrogen oxide gas, ammonia, sulfur dioxide, and siloxane. Thereby, with respect to various measurement object gas, the influence with respect to the pressure fluctuation of the measurement space of the measured value of the intensity of the measurement light can be reduced.

  The analysis apparatus may further include an analysis unit. The analysis unit analyzes the measurement target gas based on the corrected measurement value of the intensity of the measurement light. Thereby, the influence with respect to the pressure fluctuation of the measurement space of the analysis result of measurement object gas can be reduced.

  An analysis system according to another aspect of the present invention includes an analysis system that analyzes the measurement target gas, and a sampling unit that samples a gas containing the measurement target gas and introduces the gas into the measurement space of the analysis apparatus. It is.

According to still another aspect of the present invention, there is provided an analysis apparatus including a pneumatic detector having a sealed cell in which a sealed gas is sealed, and a measurement unit that measures the intensity of light incident on the sealed cell. It is the analysis method of the measurement object gas used. The analysis method includes the following steps.
A step of outputting measurement light to the measurement space where the measurement target gas exists.
A step of measuring the intensity of the measurement light that has passed through the measurement space with a pneumatic detector.
◎ Measurement of the intensity of the measurement light by the correction coefficient calculated based on the dependence of the absorption spectrum of the gas to be measured on the pressure in the measurement space and the dependence of the measurement sensitivity of the measurement light on the wavelength in the pneumatic detector The step of correcting the value.
Thereby, the influence with respect to the pressure fluctuation of the measurement space of the measured value of the intensity of the measurement light can be reduced.

  A program according to still another aspect of the present invention is a program for causing a computer to execute the above analysis method.

  In an analyzer equipped with a pneumatic detector, the influence of the measurement value of the measurement light intensity on the pressure fluctuation in the measurement space can be reduced.

The figure which shows the structure of an analyzer. The figure which shows the detailed structure of a calculation control part. The figure which shows an example of the fluctuation | variation of the absorption spectrum of measurement object gas with respect to the pressure fluctuation of measurement space. The flowchart which shows the analysis method of measurement object gas. The comparison figure which shows the fluctuation | variation of the analysis result for every measurement day by the difference in the correction method of an intensity | strength measured value. The figure which shows schematic structure of an analysis system.

1. First Embodiment (1) Configuration of Analyzer The configuration of an analyzer 100 according to the first embodiment will be described below with reference to FIG. FIG. 1 is a diagram showing the configuration of the analyzer. The analyzer 100 is, for example, a measurement target gas included in the atmosphere, exhaust gas flowing through a flue, process gas generated in various processes, exhaust gas generated by combustion of garbage, exhaust gas generated in combustion (experiment) of a boiler, and the like. This is an apparatus for analyzing Gs using the light absorption characteristics of the measurement target gas Gs. In addition, the analysis apparatus 100 may be an apparatus that analyzes impurities contained in the gas cylinder as the measurement target gas Gs.
Examples of the measurement target gas Gs that can be analyzed by the analyzer 100 according to the first embodiment include carbon monoxide (CO), carbon dioxide (CO ₂ ), hydrocarbon gas (for example, methane (CH ₄ ), propane). (C ₃ H ₈ )), nitrogen oxide (NO _x ) gas (eg, nitric oxide (NO), nitrogen dioxide (NO ₂ ), nitrous oxide (N ₂ O), etc.), ammonia (NH ₃ ) , Sulfur oxide (SO _x ) gas (eg, sulfur dioxide (SO ₂ )), siloxane, and the like.

The analyzer 100 includes a measurement cell 1. The measurement cell 1 is a hollow member having an introduction port 1a for introducing a measurement target gas therein and an exhaust port 1b for discharging the measurement target gas from the inside. In the present embodiment, the inside of the hollow member into which the measurement target gas is introduced becomes the measurement space Sp.
The introduction and discharge of the gas including the measurement target gas Gs into the measurement space Sp can be performed, for example, by suction of a pump (not shown) connected to the discharge port 1b. In addition, a gas containing the measurement target gas Gs may be introduced into the measurement space Sp from the introduction port 1a by the pressure of the gas. In this case, it is not particularly necessary to suck the gas from the discharge port 1b. In the present embodiment, the pressure in the measurement space Sp is atmospheric pressure or a pressure in the vicinity thereof.

  For example, both ends in the length direction of the measurement cell 1 are transparent to the measurement light Lm so that the measurement light Lm from the first light source 3a (described later) can pass through the measurement space Sp. In addition, for example, by providing optical filters at both ends in the length direction of the measurement cell 1, only light in a wavelength range that can be absorbed by the measurement target gas Gs and the sealed gas Ge (described later) is measured. It may be possible to pass through the space Sp.

  The analyzer 100 includes a first light source 3a at one end of the measurement cell 1 in the length direction. The first light source 3a outputs measurement light Lm including at least light in a wavelength range that can be absorbed by the measurement target gas Gs and the sealed gas Ge to the measurement space Sp. The measurement target gas Gs and the sealing gas Ge shown above can mainly absorb light in the infrared wavelength region. Therefore, as the first light source 3a, for example, a light source capable of outputting infrared light such as an infrared lamp can be used.

  The analysis apparatus 100 includes a pneumatic detector 5 on the side opposite to the side where the first light source 3a in the length direction of the measurement cell 1 is provided. The pneumatic detector 5 measures the intensity of the measurement light Lm that has passed through the measurement space Sp. The configuration of the pneumatic detector 5 will be described in detail later.

The analyzer 100 includes an optical chopper 7 between one end of the measurement cell 1 and the first light source 3a. The optical chopper 7 is, for example, a fan-shaped plate-like member that rotates around a center at a predetermined rotational speed by driving a motor (not shown) or the like.
By rotating the optical chopper 7 while outputting the measurement light Lm from the first light source 3a, the optical chopper 7 can change the intensity of the measurement light Lm output to the measurement space Sp at a period determined by the rotation speed. .

  The analysis apparatus 100 includes an arithmetic control unit 9. The arithmetic control unit 9 is a computer system including a CPU, a storage device (RAM, ROM, etc.), and various interfaces (for example, a D / A converter, an A / D converter, etc.). The arithmetic control unit 9 controls each component of the analyzer 100. In addition, the arithmetic control unit 9 processes an electrical signal regarding the intensity of the measurement light Lm input from the pneumatic detector 5 and analyzes the measurement target gas Gs. The configuration of the arithmetic control unit 9 will be described in detail later.

  For example, the analyzer 100 may further include a pressure gauge 11 that measures the pressure in the measurement space Sp by measuring the pressure of the discharge port 1b. Thereby, the analyzer 100 can measure the pressure of the measurement space Sp.

The analyzer 100 may further include a comparison cell 13, a second light source 3b, and a light collecting block 15.
The comparison cell 13 is a hollow member provided in parallel with the measurement cell 1 and forms a comparison space Sc therein. The comparison space Sc is filled with a comparison gas Gc that does not absorb the measurement light Lm (comparison light Lc). As the comparative gas Gc, for example, nitrogen (N ₂ ) gas can be used. Further, like the measurement cell 1, at least both ends in the length direction of the comparison cell 13 are transparent to the comparison light Lc (described later).

The second light source 3 b is provided at one end in the length direction of the comparison cell 13 and outputs the comparison light Lc toward the comparison cell 13. Since the comparison light Lc is the same light as the measurement light Lm, a light source similar to the first light source 3a can be used as the second light source 3b.
Since the optical chopper 7 rotates the optical chopper 7 while outputting the comparative light Lc from the second light source 3b, the intensity of the comparative light Lc can also be changed at a period determined by the rotational speed.

  The condensing block 15 is provided between the measurement cell 1 and the comparison cell 13 and the pneumatic detector 5, and guides the measurement light Lm that has passed through the measurement space Sp to the pneumatic detector 5. And a second light guide 15 b that guides the comparison light Lc that has passed through the comparison space Sc to the pneumatic detector 5.

  By providing the comparison cell 13, the second light source 3 b, and the light collecting block 15, the analyzer 100 can add to the intensity of the measurement light Lm that has passed through the measurement space Sp including the measurement target gas Gs. The intensity of the measurement light Lm when there is no absorption by the measurement target gas Gs, that is, the background intensity can be measured.

  The analyzer 100 may be held at a predetermined temperature using, for example, a temperature controller (not shown). Thereby, the influence on the analysis result in the analyzer 100 by the temperature around the analyzer 100 can be reduced.

(2) Configuration of Pneumatic Detector Next, the configuration of the pneumatic detector 5 provided in the analyzer 100 will be described.
The pneumatic detector 5 is arranged on the side farther from the first light source 3a via the first encapsulated cell 51a disposed on the side closer to the first light source 3a (and the second light source 3b) and the first encapsulated cell 51a. Second encapsulated cell 51b. A sealed gas Ge is sealed at a predetermined pressure in the first sealed cell 51a and the second sealed cell 51b.
In the present embodiment, the first encapsulated cell 51a and the second encapsulated cell 51b are connected to each other through a gas flow path provided with a measurement unit 53 (described later) so that gas can flow.

  The sealed gas Ge is preferably the same gas as the measurement target gas Gs. This is because, by making the sealed gas Ge and the measurement target gas Gs the same, the wavelength range in which the sealed gas Ge can absorb and the wavelength range in which the measurement target gas Gs can absorb can be made the same. This is because the measurement sensitivity for the measurement target gas Gs of 5 can be increased.

  On the other hand, for example, when the measurement target gas Gs is a highly reactive gas or an acidic gas, the sealed gas Ge has a wavelength range in which the measurement target gas Gs can absorb light in the measurement light Lm. A gas different from the measurement target gas Gs may be used as long as it can absorb light in at least a part of the wavelength range.

The first encapsulated cell 51a can pass the measurement light Lm, while the second encapsulated cell 51b may not be allowed to pass the measurement light Lm. For example, this can be realized by shielding the second encapsulated cell 51b from light.
By allowing the measurement light Lm to pass only through the first sealed cell 51a, the sealed gas Ge in the first sealed cell 51a expands by generating heat by absorbing the measured light Lm, while the second sealed cell 51b. The enclosed gas Ge does not expand. That is, when the measurement light Lm is incident on the first sealed cell 51a, the pressure difference between the first sealed cell 51a and the second sealed cell 51b can be increased to increase the measurement sensitivity of the intensity of the measurement light Lm.

The pneumatic detector 5 has a measurement unit 53. The measurement unit 53 is provided in a gas flow path connecting the first sealed cell 51a and the second sealed cell 51b, and the measurement light Lm is incident on the first sealed cell 51a and / or the second sealed cell 51b. The pressure difference of the sealed gas Ge generated between the first sealed cell 51a and the second sealed cell 51b is measured.
In the present embodiment, the measurement unit 53 is a flow sensor including a heat ray element made of a metal such as platinum and a circuit (for example, a Wheatstone bridge circuit) that measures the resistance value of the heat ray element.

  The measuring unit 53 of the present embodiment measures the flow rate due to the movement of the sealed gas Ge generated by the pressure difference as a resistance change when the thermoelectric element is cooled by the flow of the sealed gas Ge. That is, the measurement unit 53 of the present embodiment measures the intensity of light incident on the encapsulated cells 51a and 51b as a resistance change of the thermoelectric element.

  In the pneumatic detector 5 having the above configuration, the measurement light Lm that has passed through the measurement space Sp and the comparison light Lc that has passed through the comparison space Sc are mainly absorbed by the sealed gas Ge in the first sealed cell 51a. . As a result, the sealed gas Ge in the first sealed cell 51a generates heat. The intensity of the measurement light Lm or the comparison light Lc incident on the first sealed cell 51a can be measured by measuring the amount of pressure increase of the sealed gas Ge in the first sealed cell 51a by the heat by the measurement unit 53.

(3) Configuration of Calculation Control Unit Next, a detailed configuration of the calculation control unit 9 will be described with reference to FIG. FIG. 2 is a diagram illustrating a detailed configuration of the arithmetic control unit. Some or all of the functions of the components of the arithmetic control unit 9 described below may be realized by a program stored in a storage device of a computer system that constitutes the arithmetic control unit 9.
The arithmetic control unit 9 includes a control unit 91. The control unit 91 controls each unit of the analyzer 100 (first light source 3a, second light source 3b, measurement unit 53, optical chopper 7, pressure gauge 11, introduction and stop of measurement target gas Gs, and the like). Further, the control unit 91 receives a signal representing the measurement result from the measurement unit 53 (and the pressure gauge 11).

The arithmetic control unit 9 includes a storage unit 93. The storage unit 93 stores various parameters necessary for the operation of the analyzer 100. The storage unit 93 stores a correction coefficient C for correcting the measurement value in the pneumatic detector 5 of the intensity of the measurement light Lm that has passed through the measurement space Sp.
The arithmetic control unit 9 includes a correction unit 95. The correction unit 95 corrects the measurement value of the intensity of the measurement light Lm that has passed through the measurement space Sp using the correction coefficient stored in the storage unit 93.

The arithmetic control unit 9 includes an analysis unit 97. The analysis unit 97 performs analysis (for example, calculation of concentration) of the measurement target gas Gs existing in the measurement space Sp using the measurement value of the intensity of the measurement light Lm corrected by the correction unit 95.
The arithmetic control unit 9 has a display 99. The display 99 is a display device such as a liquid crystal display that displays various types of information such as the analysis result of the measurement target gas Gs.

(4) Correction coefficient calculation method Hereinafter, in the analyzer 100 using the pneumatic detector 5, the influence of the measured value of the intensity of the measurement light Lm that has passed through the measurement space Sp due to pressure fluctuations in the measurement space Sp is corrected. A method for calculating the correction coefficient C will be described.

  Due to the pressure fluctuation in the measurement space Sp, the spectrum width (spectrum area) of the absorption spectrum of the measurement target gas Gs existing in the measurement space Sp increases and decreases as shown in FIG. Specifically, the spectrum width increases as the pressure increases. FIG. 3 is a diagram illustrating an example of fluctuations in the absorption spectrum of the measurement target gas with respect to pressure fluctuations in the measurement space.

Conventionally, when the pressure in the measurement space Sp increases or decreases by 1 kPa, the spectrum width (area) of the absorption spectrum increases or decreases by 1% regardless of the type of the measurement target gas Gs due to the change in the gas density of the measurement target gas Gs. It had been.
However, when the change in the spectrum width of the absorption spectrum of the measurement target gas Gs due to the pressure change in the measurement space Sp of the measurement target gas Gs is calculated by the pressure influence simulation, the pressure change in the measurement space Sp of the spectrum width of the absorption spectrum is calculated. It turned out that the change with respect to changes with kinds of measurement object gas Gs.

Further, in the above-described pneumatic detector 5, the light absorption characteristics of the sealed gas Ge are dependent on the wavelength, and the wavelength range in which the sealed gas Ge can absorb and the wavelength range in which the measurement target gas Gs can absorb overlap. doing. For this reason, it has been found that the pneumatic detector 5 shows dependence on the wavelength of the measurement light Lm with respect to the measurement sensitivity of the intensity of the measurement light Lm that has passed through the measurement space Sp in which the measurement target gas Gs exists.
Since the sealing pressure of the sealing gas Ge is constant and does not change, the influence on the measurement sensitivity of the measuring light Lm due to the pressure variation of the sealing gas Ge can be ignored.

  As described above, the change of the spectral width of the absorption spectrum with respect to the pressure change in the measurement space Sp differs depending on the type of the measurement target gas Gs, and the measurement sensitivity of the pneumatic detector 5 has wavelength dependency. In the embodiment, the correction coefficient C is calculated based on both the pressure dependence of the measurement space Sp of the absorption spectrum of the measurement target gas Gs and the wavelength dependence of the measurement sensitivity of the intensity of the measurement light Lm.

Specifically, for example, the correction coefficient C can be calculated as follows.
First, the intensity of the measurement light Lm measured by the pneumatic detector 5 when the measurement target gas Gs having a certain concentration in the measurement space Sp is present, and the pressure of the measurement space Sp is a reference pressure (for example, Atmospheric pressure) and when the pressure is near the reference pressure.
The calculated value of the measurement intensity of the measurement light Lm at each pressure is, for example, the light transmittance (absorption spectrum) of the measurement target gas Gs that is a function of wavelength and the measurement of the pneumatic detector 5 for each pressure in the measurement space Sp. It can be calculated by integrating the product of the sensitivity and the intensity of the measurement light Lm in the measurement wavelength range.

  The measurement wavelength range that is the integration range is, for example, the wavelength range of the measurement light Lm that is passed by the optical filters provided at both ends of the measurement cell 1 and the comparison cell 13, and / or the wavelength that the sealed gas Ge can absorb. It can be determined by the range. Further, the wavelength dependence (absorption spectrum) of the light transmittance of the measurement target gas Gs at each pressure can be calculated by pressure influence simulation.

  Thereafter, on the coordinates where the horizontal axis is the pressure of the measurement space Sp and the vertical axis is the intensity of the measurement light Lm, the calculated value of the measurement intensity of the measurement light Lm at each calculated pressure is plotted, and the plotted measurement light Lm The slope of the straight line that most closely matches the calculated value of the measured intensity can be calculated as the correction coefficient C.

In addition, for example, the (calibration) gas containing the measurement target gas Gs having the reference concentration is filled in the measurement space Sp with a plurality of types of pressure including the reference pressure, and the intensity of the measurement light Lm at each pressure in the measurement space Sp is measured. The actual measurement value in the pneumatic detector 5 is acquired, and the actual measurement value of the measurement light Lm at each pressure in the measurement space Sp is plotted on the coordinates with the horizontal axis representing the pressure and the vertical axis representing the intensity of the measurement light Lm. The slope of the straight line that most closely matches the measured value of the measured light Lm may be calculated as the correction coefficient C.
The correction coefficient C calculated from the measured value of the intensity of the measuring light Lm as described above was in good agreement with the correction coefficient C calculated from the calculated value of the measured intensity of the measuring light Lm.

  The correction coefficient C calculated as described above indicates a unique value for each of the above-mentioned gases cited as the measurement target gas Gs. Therefore, in the present embodiment, the correction coefficient C is calculated by the number of types of the measurement target gas Gs that is the analysis target in the analysis apparatus 100 and stored in the storage unit 93.

  The correction coefficient C calculated as described above is a ratio (specifically, the sealed cell 51a) that the measured value of the intensity of the measuring light Lm is smaller than 1% when the pressure in the measuring space Sp fluctuates by 1 kPa. , 51b varies depending on the concentration of the enclosed gas Ge, but it is a coefficient representing the variation in a range of 0.30 to 0.99%).

The correction coefficient C has the above-described characteristics because the change in the spectral width of the absorption spectrum of the measurement target gas Gs due to the pressure change in the measurement space Sp differs depending on the type of the measurement target gas Gs and / or the pneumatic. This is because the spectrum of the sealed gas Ge that determines the wavelength dependence on the measurement sensitivity of the measurement light Lm in the detector 5 has a certain predetermined width.
By using the correction coefficient C calculated as described above as a coefficient for correcting the measurement value of the intensity of the measurement light Lm in the pneumatic detector 5, the pressure fluctuation in the measurement space Sp of the measurement value of the intensity of the measurement light Lm. As will be described later, it is possible to reduce the fluctuation of the analysis result of the measurement target gas Gs with respect to the pressure fluctuation in the measurement space Sp.

(5) Method for Analyzing Measurement Target Gas in Analyzer The measurement target in the analyzer 100 of the present embodiment that corrects the measured value of the intensity of the measurement light Lm in the pneumatic detector 5 using the correction coefficient C described above. A method for analyzing the gas Gs will be described with reference to FIG. FIG. 4 is a flowchart showing a method of analyzing the measurement target gas. Below, the example which correct | amends the measured value of the intensity | strength of the measurement light Lm using the correction coefficient C calculated from the measured value of the intensity | strength of the measurement light Lm in the pneumatic detector 5 demonstrated above is demonstrated.
When the analysis of the measurement target gas Gs is started, the analyzer 100 samples, for example, exhaust gas generated in various processes from a flue through which the exhaust gas flows and introduces it into the measurement space Sp. Further, the control unit 91 rotates the optical chopper 7 at a predetermined number of rotations, and outputs the measurement light Lm from the first light source 3a and the comparison light Lc from the second light source 3b (step S1).

Thereafter, the intensity of the measurement light Lm that has passed through the measurement space Sp and the intensity of the comparison light Lc that has passed through the comparison space Sc are measured (step S2).
Specifically, the control unit 91 receives signals (resistance values) indicating the intensity of the measurement light Lm and the comparison light Lc from the measurement unit 53 of the pneumatic detector 5. The controller 91 determines whether the received signal is a signal related to the intensity of the measurement light Lm or a signal related to the intensity of the comparison light Lc, for example, at a position (rotation angle) where the optical chopper 7 passes the measurement light Lm. It can be determined by whether it is present or at a position (rotation angle) through which the comparison light Lc passes.
The control unit 91 converts the signals related to the intensities of the measurement light Lm and the comparison light Lc received from the measurement unit 53 into measured values of the intensities of the measurement light Lm and the comparison light Lc by A / D conversion or the like. The converted intensity measurement value is temporarily stored in the storage unit 93 or the like.

Next, the correction unit 95 selects and reads the correction coefficient C corresponding to the measurement target gas Gs from the storage unit 93, and uses the correction coefficient C to actually measure the intensity of the measurement light Lm obtained in step S2. For example, the value is corrected to a measured value of intensity at a reference pressure (for example, atmospheric pressure) (step S3).
Specifically, the correction unit 95 first acquires a measurement value of the pressure in the measurement space Sp from the pressure gauge 11 via the control unit 91. Alternatively, the pressure measurement may be entered by the user prior to performing the analysis. Thereafter, the correction unit 95, for example, (actual measurement value of the measurement light Lm) − (correction coefficient C) * {(actual measurement value of the pressure in the measurement space Sp) − (reference pressure)} (the correction coefficient C is the pressure The measured value of the intensity of the measuring light Lm is converted into the measured value of the intensity of the measuring light Lm at the reference pressure (when calculated as a coefficient that increases the measured value of the intensity with increasing). to correct.

  Regarding the comparison light Lc, the pressure of the comparison gas Gc is constant in the comparison space Sc, and the comparison gas Gc does not absorb the comparison light Lc (measurement light Lm). However, the same correction as that performed is not executed.

  After correcting the measurement value of the intensity of the measurement light Lm, the analysis unit 97 receives the corrected measurement value of the intensity of the measurement light Lm from the correction unit 95, and the measurement value of the intensity of the corrected measurement light Lm, Based on the difference between the measured value of the intensity of the comparison light Lc and the measurement gas Sp in the measurement space Sp (for example, calculation of the concentration), the analysis result of the measurement gas Gs is displayed on the display 99. (Step S4).

  By performing the above steps S1 to S4, the wavelength dependence of the measurement sensitivity of the pneumatic detector 5 and the dependence of the absorption spectrum of the measurement target gas Gs on the pressure of the measurement space Sp are appropriately taken into consideration. By using the calculated correction coefficient C, the measurement value of the intensity of the measurement light Lm is appropriately corrected, and the analysis result of the measurement target gas Gs with reduced influence on the pressure fluctuation in the measurement space Sp can be obtained.

For example, as shown in FIG. 5, using the correction coefficient C calculated by the method described in this embodiment, the measurement target gas Gs is analyzed for seven consecutive days (the pressure in the measurement space Sp varies on each day). Variation of the measurement result for each measurement day when the measurement is performed is the variation when the correction by the correction coefficient is not performed on the measurement value of the intensity of the measurement light Lm, and the measurement light with respect to the pressure variation of 1 kPa as the correction coefficient. It was much smaller than the fluctuation when using the coefficient (1% FS / 1 kPa) that the measured value of the intensity of Lm fluctuates by 1%.
In other words, it can be seen that by correcting the measurement value of the intensity of the measurement light Lm by the correction method of the present embodiment, an analysis result having a minimum influence on the pressure fluctuation in the measurement space Sp is obtained.
FIG. 5 is a comparison diagram showing fluctuations in the analysis results for each measurement day due to differences in the correction method of the intensity measurement value.

2. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. In particular, a plurality of embodiments and modifications described in this specification can be arbitrarily combined as necessary.
(A) Other Embodiment of Pneumatic Detector The detector for measuring the intensity of the measurement light is of a type in which the intensity of the measurement light is measured using the pressure fluctuation of the sealed gas that has absorbed the measurement light (that is, As long as it is a pneumatic detector, the correction of the measured value using the correction coefficient C described in the first embodiment can be applied to any type of pneumatic detector.
For example, the correction of the measured value using the correction coefficient C described in the first embodiment can be applied to an analyzer provided with a condenser microphone type pneumatic detector.

(B) Other Embodiments of Analyzing Apparatus The measurement value correction described in the first embodiment can be applied to any analyzing apparatus as long as the analyzing apparatus includes a pneumatic detector. . For example, a cell into which a gas to be measured and a comparison gas (reference gas) described in the first embodiment are alternately introduced, a light source provided at one end of the cell, and provided at the other end The measurement value correction described in the first embodiment can also be applied to an analysis apparatus (cross-flow type analysis apparatus) including a pneumatic detector.

  In addition, a pneumatic detector that measures the intensity of the measurement light absorbed by the measurement target gas and the other interference gas, and a pneumatic detector that measures the intensity of the measurement light absorbed only by the interference gas. The measurement value correction described in the first embodiment can also be applied to the analyzer provided. In this case, correction using the correction coefficient C (set individually for each detector) is performed on the measured values of these two detectors.

  The installation position of the pressure gauge 11 is not limited to the discharge port 1b of the measurement target gas Gs. For example, the pressure gauge 11 may be provided inside a housing that houses the analyzer 100.

As shown in FIG. 6, the analyzer 100 (introduction port 1a) samples a gas containing the measurement target gas Gs from a flue or a pipe, and measures the measurement space Sp of the analyzer 100 (ie, the measurement cell 1). It may be connected to the sampling unit 101 introduced into the system. In this case, the analysis apparatus 100 and the sampling unit 101 constitute an analysis system 200. FIG. 6 is a diagram showing a schematic configuration of the analysis system.
The sampling unit 101 includes, for example, a probe 1011 that samples a gas flowing in a flue or a pipe, a filter 1013 that collects dust contained in the sampled gas, and a pretreatment device 1015 that preprocesses the sampled gas ( For example, it is configured by an electric cooler, a drain separator, a tube pump, and a mist catcher that removes sulfuric acid mist, salt, and the like.

(C) Other Embodiments for Target to be Corrected Correction using a correction coefficient may be performed on the final analysis result of the measurement target gas. In this case, for example, after the analysis result is calculated or measured with the pressure in the measurement space including the measurement target gas having the reference concentration set to the reference pressure and a plurality of pressures in the vicinity thereof, the horizontal axis is the pressure, and the vertical axis is the analysis result. The analysis result is plotted on the graph, and the slope of the straight line that most closely matches the plot can be calculated as a correction coefficient for the analysis result.
The analysis result is based on the difference between the intensity of the measurement light and the intensity of the comparison light, and the measurement value of the intensity of the comparison light is not affected by pressure fluctuations. Is equivalent to executing correction using the correction coefficient for the measurement value of the intensity of the measurement light.

  The present invention can be widely applied to gas analyzers equipped with a pneumatic detector.

DESCRIPTION OF SYMBOLS 100 Analysis apparatus 200 Analysis system 1 Measurement cell 1a Inlet 1b Outlet 3a 1st light source 3b 2nd light source 5 Pneumatic detector 51a 1st enclosure cell 51b 2nd enclosure cell 53 Measurement part 7 Optical chopper 9 Operation control part 91 Control Unit 93 Storage unit 95 Correction unit 97 Analysis unit 99 Display 11 Pressure gauge 13 Comparison cell 15 Condensing block 15a First light guide 15b Second light guide 101 Sampling unit 1011 Probe 1013 Filter 1015 Preprocessing device C Correction coefficient Gc Comparison gas Ge Filled gas Gs Measurement target gas Lc Comparison light Lm Measurement light Sc Comparison space Sp Measurement space

Claims (10)

A light source that outputs measurement light to the measurement space where the measurement target gas exists,
A sealed cell in which a sealed gas that absorbs light in a wavelength range including at least part of a wavelength range in which the measurement target gas absorbs is sealed; and an intensity of the measurement light that has passed through the measurement space and entered the sealed cell. A pneumatic detector having a measuring section for measuring;
According to the correction coefficient calculated based on the dependence of the absorption spectrum of the measurement target gas on the pressure in the measurement space and the dependence on the wavelength of the measurement sensitivity of the measurement light in the pneumatic detector, the measurement light A correction unit for correcting the measured value of the intensity of
An analyzer comprising:   2. The correction coefficient according to claim 1, wherein the correction coefficient is a coefficient indicating that the measurement value of the intensity of the measurement light fluctuates at a rate of less than 1 percent when the pressure in the measurement space fluctuates by 1 kilopascal. Analysis equipment.   The analyzer according to claim 1, wherein the correction coefficient has a value specific to the measurement target gas.   The analyzer according to any one of claims 1 to 3, wherein the pressure in the measurement space is atmospheric pressure or a pressure in the vicinity thereof.   The analyzer according to claim 1, wherein the measurement object gas and the sealed gas are the same gas.   The measurement object gas is a gas selected from any one of carbon monoxide, carbon dioxide, hydrocarbon gas, nitrogen oxide gas, ammonia, sulfur dioxide, and siloxane. Analysis equipment.   The analyzer according to claim 1, further comprising an analyzer that analyzes the measurement target gas based on the corrected measurement value of the intensity of the measurement light. An analysis system comprising: an analysis device that analyzes a measurement target gas; and a sampling unit that samples a gas containing the measurement target gas and introduces the gas into the measurement space of the analysis device,
The analyzer is
A light source that outputs measurement light to the measurement space;
A sealed cell in which a sealed gas that absorbs light in a wavelength range including at least part of a wavelength range in which the measurement target gas absorbs is sealed; and an intensity of the measurement light that has passed through the measurement space and entered the sealed cell. A pneumatic detector having a measuring section for measuring;
According to the correction coefficient calculated based on the dependence of the absorption spectrum of the measurement target gas on the pressure in the measurement space and the dependence on the wavelength of the measurement sensitivity of the measurement light in the pneumatic detector, the measurement light A correction unit for correcting the measured value of the intensity of
Having an analysis system. A method for analyzing a gas to be measured using an analysis device including a sealed cell in which a sealed gas is sealed, and a measurement unit that measures the intensity of light incident on the sealed cell. ,
Outputting measurement light to a measurement space in which the measurement target gas exists;
Measuring the intensity of the measurement light that has passed through the measurement space by the pneumatic detector;
According to the correction coefficient calculated based on the dependence of the absorption spectrum of the measurement target gas on the pressure in the measurement space and the dependence on the wavelength of the measurement sensitivity of the measurement light in the pneumatic detector, the measurement light Correcting the intensity measurements of
Analytical methods including: Outputting measurement light to a measurement space where a measurement target gas exists;
A step of causing a pneumatic detector having a sealed cell filled with a sealed gas and a measurement unit that measures the intensity of light incident on the sealed cell to measure the intensity of the measurement light that has passed through the measurement space; When,
According to the correction coefficient calculated based on the dependence of the absorption spectrum of the measurement target gas on the pressure in the measurement space and the dependence on the wavelength of the measurement sensitivity of the measurement light in the pneumatic detector, the measurement light Correcting the intensity measurements of
A program for causing a computer to execute an analysis method including:

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