JP6513276B1 - Gas analyzer - Google Patents

Abstract

The present invention provides a gas analyzer which can always accurately analyze the gas composition of a minute flow rate of sample gas. SOLUTION: A sampling flow channel 1 into which a sample gas is introduced, an index gas supply source 2, an index gas flow channel 3 which joins the sampling flow channel and supplies an index gas from the index gas supply source, a sampling flow channel And a mixed gas flow path 4 extending from the junction of the index gas flow paths, and a gas concentration measurement unit 5 connected to the mixed gas flow path for measuring the concentration of the target gas component in the sample gas; The pump 6, the flow rate controller 7 disposed in the index gas flow path, the index gas concentration meter 8 incorporated in the gas concentration measurement section, the index gas concentration set value input section 9, and the index gas concentration meter The mixing ratio of the index gas is determined based on the measured value and the concentration setting value input to the index gas concentration setting value input unit, and the sample before mixing with the index gas from the mixing ratio of the index gas and the measurement value of the gas concentration measuring unit Calculate concentration of target gas component in gas It comprises a gas concentration calculator 10 that. [Selected figure] Figure 1

Description

  The present invention relates to a gas analyzer, and more particularly to a gas analyzer suitable for analyzing the gas composition of a sample gas with a minute flow rate.

In basic research on combustion, it is important to analyze combustion products from relatively small-scale flames such as nozzle burners, counterflow flames, etc. A gas analyzer is used.
In such small-scale flames, since the generation of combustion product gas is performed at a small flow rate, the introduction of the combustion product gas into the gas analyzer does not affect the flow characteristics of the combustion field. Flow rate sampling is required.

On the other hand, with regard to the gas analyzer provided in the gas analyzer, while maintaining the measurement accuracy of the component concentration of the sample gas at a constant level, the sample gas necessary for accurately measuring the transient change of the component concentration of the sample gas A flow rate range (standard measurement flow rate range) is defined.
In particular, in a FTIR (Fourier Transform Infrared) gas analyzer that can measure the concentration of a plurality of gas components simultaneously, a gas analyzer using a quantum cascade laser absorption (QCL-IR) method, etc., a large flow rate of several liters per minute or more It is necessary to sample the sample gas.

  However, when the combustion product gas of a large flow rate is sampled in the analysis of the combustion product gas, the flow characteristic of the combustion field changes, and the accurate analysis of the combustion product gas can not be performed.

  Therefore, in the prior art, there is known a gas analyzer which samples a minute flow rate of sample gas, dilutes it with a dilution gas, and introduces a standard measurement flow rate of the diluted sample gas into the gas analyzer. .

And, as a conventional gas analyzer of this kind, for example, there is one described in Patent Document 1.
The gas analyzer described in Patent Document 1 includes a first supply passage into which a sample gas is introduced, a second supply passage into which a dilution gas is introduced, and a sample gas from a first supply passage and a second supply passage. An introduction pipe which mixes the dilution gas from the mixture to become a mixed gas, a first branch path which branches the mixed gas from the introduction pipe, and a second branch path which branches the mixed gas from the introduction pipe in parallel. There is.

  In addition, first and second mass flow controllers are provided in the first and second supply paths, respectively. A non-dispersive infrared densitometer is provided in the first branch, and a mass spectrometer is connected to the second branch. The first and second branch paths are configured to be capable of changing the internal pressure in accordance with the connected measuring device.

  Thus, in the introduction pipe, the sample gas adjusted to the first flow rate by the first mass flow controller is diluted by the dilution gas adjusted to the second flow rate by the second mass flow controller, and the diluted sample gas is diluted The first and second branches introduce the non-dispersive infrared densitometer and mass spectrometer, respectively.

  Then, analysis of the gas composition based on the measured value of the specific gas by the non-dispersive infrared densitometer, the measured values of the plural kinds of gas by the mass spectrometer, and the dilution rate obtained from the flow rate setting value of each mass flow controller Is done.

  However, while the flow rate setting of the mass flow controller must be determined taking into account the conversion factor of the gas passing through the mass flow controller, the gas composition of the sample gas is usually unknown, so the flow rate setting is determined. Not all of the necessary conversion factors are taken into account.

  Therefore, the flow rate setting value of the mass flow controller may be inaccurate, and in such a case, there is a problem that the gas composition of the sample gas is analyzed based on the incorrect dilution rate of the sample gas.

JP, 2009-300254, A

  Therefore, an object of the present invention is to provide a gas analyzer which can always accurately analyze the gas composition of a minute flow rate of sample gas.

In order to solve the above problems, according to the present invention , a sampling flow channel into which a minute flow rate of sample gas is introduced, an index gas supply unit that switches and supplies two preset different index gas concentrations, and An index gas flow path which joins the downstream end of the sampling flow path and supplies the index gas from the index gas supply unit to the sampling flow path; and a junction point of the sampling flow path and the index gas flow path A mixed gas flow path in which a mixed gas of a sample gas and the index gas flows, and a gas concentration measurement unit connected to the downstream end of the mixed gas flow path and measuring the concentration of a target gas component contained in the sample gas; A pump disposed in the mixed gas flow path or the exhaust system of the gas concentration measurement unit for feeding the mixed gas to the gas concentration measurement unit; the number of rotations of the pump, and the finger The supply amount of the index gas from the gas supply unit is adjusted such that the flow rate of the mixed gas in the mixed gas flow passage becomes a flow rate corresponding to the measurement capability of the gas concentration measurement unit, and the sampling flow A first flow meter disposed in the passage for measuring the flow rate of the sample gas, and disposed in the indicator gas passage, or incorporated in the indicator gas supply unit, from the indicator gas supply unit to the indicator gas passage And a second flow meter for measuring the flow rate of the indicator gas supplied to the second gas flow sensor, and an indicator gas concentration meter incorporated in the gas concentration measurement unit or disposed in the mixed gas flow path to measure the concentration of the indicator gas And each of the measurement values of the first flow meter and the gas concentration measuring unit is maintained constant, and the index gas concentration setting value input unit receiving the setting values of the two different concentrations of the index gas, and the first flow meter and the gas concentration measuring unit Between, When the indicator gas is switched and supplied to the indicator gas flow path, the concentration set value for the indicator gas previously supplied, the measurement value of the second flow meter, and the measurement value of the indicator gas concentration meter, Next, using the concentration set value for the indicator gas supplied, the measurement value of the second flow meter and the measurement value of the indicator gas concentration meter, and the measurement value of the gas concentration measurement unit, the indicator gas A gas analyzer is provided, comprising: a gas concentration calculating unit that calculates the concentration of the target gas component in the sample gas before being mixed.

According to a preferred embodiment of the present invention, the indicator gas supply unit is connected to first and second branch passages branched from the upstream end of the indicator gas passage, and the first branch passage. A first indicator gas supply that supplies the indicator gas of a first concentration of the two different concentrations, and a second one of the two different concentrations connected to the second branch flow path A second indicator gas supply source for supplying the indicator gas having a concentration, and the branch points of the first and second branch passages and the indicator gas passage, the first and second branch passages It has a flow-path switching valve which switches a flow path between, and the flow rate controller arrange | positioned downstream of the said branch point in the said index gas flow path.

According to another preferred embodiment of the present invention, the indicator gas supply unit is connected to the first and second branch passages branched from the upstream end of the indicator gas passage and the first branch passage. A first indicator gas supply for supplying the indicator gas at a first concentration of the two different concentrations, and a second branch flow path connected to the first of the two different concentrations; A second indicator gas supply source for supplying the indicator gas having a concentration of 2, a first flow rate controller disposed in the first branch channel, and a second indicator channel disposed in the second branch channel And two flow controllers, and the second flow meter is disposed in each of the first and second branch paths.

According to the present invention , the sample gas to be sampled is mixed with the indicator gas, and a mixed gas of a flow rate (standard measurement flow rate of the gas concentration measurement unit) corresponding to the measurement capability of the gas concentration measurement unit is introduced into the gas concentration measurement unit. Therefore, even when a gas analyzer (for example, an FTIR gas analyzer or a QCL-IR gas analyzer) having a large standard measurement flow rate is used as the gas concentration measurement unit, the sample flow rate of the sample gas is kept small. The component concentration of the gas can be accurately monitored.

Furthermore, according to the present invention, even when the sample gas contains the measurement target gas component of the indicator gas concentration meter, while the flow rate and concentration measurement value of the sample gas to be sampled are maintained constant. The sample gas of the same type and different two concentrations is switched to be mixed with the sample gas, and the concentration set value for the indicator gas previously mixed, the measurement value of the second flowmeter and the measurement value of the indicator gas concentration meter, and the Next, using the concentration set value for the mixed indicator gas, the measured value of the second flowmeter and the measured value of the indicator gas concentration meter, and the measured value of the gas concentration measuring unit (the measured concentration of the target gas component), Since the concentration of the target gas component in the sample gas before being mixed with the index gas is calculated, that is, the target gas component concentration value in the sample gas is measured based on the numerical value which is accurately set or measured. Gas gas It can be analyzed always with high accuracy.

It is a figure which shows schematic structure of the gas analyzer by one Example of this invention. It is a figure which shows schematic structure of the gas analyzer by another Example of this invention. It is a figure similar to FIG. 2 which shows the modification of the index gas supply part of the gas analyzer of FIG.

Hereinafter, the configuration of the present invention will be described based on a preferred embodiment with reference to the attached drawings.
FIG. 1 is a view showing a schematic configuration of a gas analyzer according to one embodiment of the present invention.
Referring to FIG. 1, the gas analyzer of the present invention includes a sampling channel 1 into which a minute flow rate of sample gas is introduced, and an indicator gas supply source 2 for supplying a preset concentration of index gas. .
The indicator gas is composed of only the gas component not contained in the sample gas or a mixture of the gas component and a gas component other than the target gas component in the sample gas.

  In the gas analyzer, one end 3a is connected to the indicator gas supply source 2, and the other end 3b joins the downstream end 1a of the sampling channel 1 to supply the indicator gas from the indicator gas supply source 2 A passage 3 is provided with a mixed gas passage 4 extending from a junction of the sampling passage 1 and the indicator gas passage 3 and in which a mixed gas of a sample gas and an indicator gas flows.

The gas concentration measurement unit 5 for measuring the concentration of the target gas component contained in the sample gas is connected to the downstream end of the mixed gas flow channel 4. The pump 6 for feeding to is disposed.
As the gas concentration measuring unit 5, for example, an FTIR gas analyzer, a mass spectrometer, a QCL-IR gas analyzer, etc. can be used, and the gas concentration measuring unit 5 may be composed of a plurality of gas analyzers. it can.
The pump 6 can also be disposed in the exhaust system of the gas concentration measurement unit 5.

Further, a flow rate controller 7 is disposed in the indicator gas flow path 3.
The pump 6 and the flow rate controller 7 are adjusted such that the flow rate of the mixed gas in the mixed gas flow path 4 becomes the flow rate corresponding to the measurement capability of the gas concentration measurement unit 5 (the standard measurement flow rate of the gas concentration measurement unit 5). ing.

  Specifically, for example, when the standard measurement flow rate of the gas concentration measurement unit 5 is 5 L / min and the sampling flow rate of the sample gas is 1 L / min, the index gas channel 3 to 4 L / min index Gas is supplied, and the pump 6 and the flow rate controller 7 are adjusted so that the flow rate of the mixed gas flowing through the mixed gas flow path 4 is 5 L / min.

The gas analyzer of the present invention is also incorporated in the gas concentration measuring unit 5, and the indicator gas concentration meter 8 for measuring the concentration of gas components not contained in the sample gas in the indicator gas, and the concentration setting of the indicator gas An indicator gas concentration set value input unit 9 is provided which receives an input of a value.
The indicator gas concentration meter 8 may be disposed in the mixed gas flow path 4 without being incorporated in the gas concentration measurement unit 5.

に従って算出し、指標ガスの混合率Ｍとガス濃度測定部５の測定値（対象ガス成分の濃度測定値）Ｃ_ｓとに基づき、指標ガスと混合される前の試料ガス中の対象ガス成分の濃度Ｃ_ｓ０を

に従って算出するガス濃度算出部１０を備えている。 The gas analyzer of the present invention further sets the measured value of the indicator gas concentration meter 8 to C _i , the concentration set value input to the indicator gas concentration set value input unit 9 to C _i0 , and the mixing ratio M of the index gas

Calculated according mixing ratio M and the gas concentration measurement value of the measurement section 5 of the indicator gas (concentration measurement value of the target gas components) based on the C _s, the target gas components in the sample gas before it is mixed with an indicator gas Concentration C _s0

The gas concentration calculation unit 10 is provided to calculate according to

  In the gas analyzer of the present invention, the sample gas to be sampled is mixed with the indicator gas, and a mixed gas of a flow rate (standard measurement flow rate) corresponding to the measurement capability of the gas concentration measurement unit 5 is introduced into the gas concentration measurement unit 5 Therefore, even when a gas analyzer having a large standard measurement flow rate such as an FTIR gas analyzer or a QCL-IR gas analyzer is used as the gas concentration measurement unit 5, for example, the sampling flow rate of the sample gas is kept small. The response can be obtained at high speed from the gas concentration measuring unit 5 at all times, and the component concentration of the transiently changing sample gas can be accurately captured.

Furthermore, when the indicator gas is composed of only the gas component not contained in the sample gas, or the gas component mixed with the gas component other than the target gas component in the sample gas, the indicator gas The mixing ratio of the index gas is determined based on the concentration setting value and the concentration measurement value of the index gas concentration meter 8, and the mixing ratio of the index gas and the measurement value of the gas concentration measurement unit 5 (the concentration measurement value of the target gas component) are used The concentration of the target gas component in the sample gas before being mixed with the index gas is calculated.
In this way, the target gas component concentration value in the sample gas is measured based on the numerical values that are accurately set and measured, so that the analysis of the gas composition of the sample gas can always be performed with high accuracy.

FIG. 2 is a schematic view of a gas analyzer according to another embodiment of the present invention.
In the embodiment of FIG. 1, the indicator gas is composed of only the gas component not contained in the sample gas, or the gas component mixed with the gas component other than the target gas component in the sample gas. While the analysis of the gas composition of the sample gas can be performed with high accuracy, in the embodiment shown in FIG. 2, the sample gas contains the gas component to be measured by the indicator gas concentration meter. Even if there is, the analysis of the gas composition of the sample gas can be performed with high accuracy.

Referring to FIG. 2, in the gas analyzer of the present invention, the sampling flow channel 11 into which a minute flow rate of sample gas is introduced, and the index which switches and supplies the same flow rate of two different concentration indicator gases set in advance. A gas supply unit and an indicator gas flow passage 12 which joins the downstream end 11 a of the sampling flow passage 11 and supplies an index gas from the indicator gas supply unit are provided.
A first flow meter 13 is disposed in the sampling channel 11.

  In this embodiment, the indicator gas supply unit is connected to the first and second branch passages 14a and 14b branched from the upstream end 12a of the indicator gas passage 12 and the first branch passage 14a, and The first indicator gas supply source 15a for supplying the indicator gas of the first concentration of the different concentrations, and the second branch flow passage 14b are connected to the indicator gas of the second concentration of the two different concentrations. Provided at the branch point of the second indicator gas supply source 15b for supplying the first and second branch channels 14a and 14b and the indicator gas channel 12 and supplying the first and second branch channels 14a and 14b. A flow path switching valve 16 for switching between the flow paths, and a flow rate controller 17 and a second flow meter 18 which are disposed downstream of the branch point in the indicator gas flow path 12.

  The gas analyzer of the present invention also includes a mixed gas flow path 19 extending from the junction of the sampling flow path 11 and the index gas flow path 12, and a mixed gas of the sample gas and the index gas flowing therein; A gas concentration measurement unit 20 connected to the downstream end for measuring the concentration of the target gas component contained in the sample gas, and a pump 21 disposed in the mixed gas flow passage 19 for feeding the mixed gas to the gas concentration measurement unit 20 Have.

As the gas concentration measuring unit 20, for example, an FTIR gas analyzer, a mass spectrometer, a QCL-IR gas analyzer or the like can be used, and the gas concentration measuring unit 20 may be configured of a plurality of gas analyzers. it can.
The pump 21 can also be disposed in the exhaust system of the gas concentration measuring unit 20.

  The pump 21 and the flow rate controller 17 are adjusted such that the flow rate of the mixed gas in the mixed gas flow path 19 becomes a flow rate (standard measurement flow rate of the gas concentration measurement unit 5) according to the measurement capability of the gas concentration measurement unit 20. ing.

The gas analyzer of the present invention is also incorporated in the gas concentration measurement unit 20, and the indicator gas concentration meter 22 for measuring the concentration of the indicator gas, and the indicator gas concentration receiving the set values of two different concentrations of the indicator gas A set value input unit 23 is provided.
The indicator gas concentration meter 22 may be disposed in the mixed gas flow passage 19 without being incorporated in the gas concentration measurement unit 20.

または

に従って算出するガス濃度算出部２４を備えている。 In the gas analyzer of the present invention, the indicator gas is switched and supplied to the indicator gas passage 12 while the measurement values of the flow meter 13 and the gas concentration measurement unit 20 of the sampling passage 11 are maintained constant. When the concentration set value for the indicator gas previously supplied, the measurement value of the second flowmeter 18, and the measurement value of the indicator gas densitometer 22 are respectively C _i10 , Q _i1 and C _i1 , _Let C _i20 , Q _i2 and C _i2 be the concentration set value for the indicator gas, the measured value of the second flow meter 18 and the measured value of the indicator gas densitometer 22 respectively, and supply the indicator gas at the time and the next indicator gas supply When the measured values of the gas concentration measurement unit 20 at the time of measurement are _C.sub.s1 and _C.sub.s2 ), respectively, the concentration _C.sub.s0 of the target gas component in the sample gas before being mixed with the index gas is

Or

The gas concentration calculation unit 24 is provided to calculate according to

Next, the process of deriving equation (3) will be described.
First, the relevant parameters are defined as follows.
C _is : Concentration of indicator gas in sample gas C _i10 : Concentration set value of indicator gas previously supplied C _i20 : Concentration set value of indicator gas supplied next C _i1 : of indicator gas previously supplied Measured concentration value C _i2 : Measured concentration value of indicator gas supplied next Q _s : Volume flow of sample gas Q _i1 : Volume flow of indicator gas previously supplied Q _i2 : Volume of indicator gas supplied next Flow rate C _s1 : Concentration measurement value of the gas concentration measurement unit 20 at the time of the previous indicator gas supply (concentration measurement value of target gas component)
C _s2 : Measured value of concentration of gas concentration measuring unit 20 at the time of next supply of indicator gas (measured value of concentration of target gas component)
C _s0 : Concentration of target gas component in sample gas before being mixed with indicator gas

これをＣ_ｉｓについて解くと、

となる。 The value obtained by multiplying the concentration (volume concentration) by the volume flow rate is unchanged before and after mixing of the sample gas and the index gas, and therefore the following equation holds for the index gas supplied earlier.

Solving this for C _is ,

It becomes.

（５）式と（６）式からＣ_ｉｓを消去し、Ｑ_ｓについて解けば、

が得られる。 Now, while the index gas is switched and supplied, the sampling flow rate of the sample gas and the component concentration value of the sample gas are maintained constant, so equation (5) holds for the index gas supplied next as well. Do. That is,

If C _is is eliminated from equations (5) and (6) and Q _s is solved,

Is obtained.

で表され、混合される前の試料ガス中の対象ガス成分の濃度Ｃ_ｓ０を求めるには、ガス濃度測定部２１の測定値Ｃ_ｓ１を混合率Ｍ_１で割ればよいから、

となって、式（３）が得られる。 The mixing ratio M ₁ when the indicator gas in the sample gas is mixed with the indicator gas previously supplied through the indicator gas channel 13 is

In order to obtain the concentration C _s0 of the target gas component in the sample gas before being mixed, it is sufficient to divide the measured value C _s1 of the gas concentration measurement unit 21 by the mixing ratio M ₁ .

Equation (3) is obtained.

で表され、混合される前の対象ガス成分の濃度Ｃ_ｓ０を求めるには、ガス濃度測定部２１の測定値Ｃ_ｓ２を混合率Ｍ_２で割ればよいから、

となって、式（４）が得られる。 Similarly, the mixing ratio M ₂ when the indicator gas in the sample gas is mixed with the indicator gas supplied next through the indicator gas channel 13 is

Since it is sufficient to divide the measured value C _s2 of the gas concentration measurement unit 21 by the mixing ratio M ₂ in order to obtain the concentration C _s0 of the target gas component before being mixed and represented by

Equation (4) is obtained.

となる。 Here, in the most preferable measurement conditions, Q _i1 = Q _i2 (= Q _i ) and C _s1 = C _s2 (= C _s ), so equation (8) is

It becomes.

で表され、混合される前の試料ガス中の指標ガス以外のガス成分についてその濃度Ｃ_ｓ０を求めるには、ガス濃度測定部２１の測定値Ｃ_ｓ０を混合率Ｍで割ればよいから、

となる。 The mixing ratio M when the indicator gas in the sample gas is mixed with the indicator gas supplied from the indicator gas flow path 13 is

In represented, for the obtaining the concentration C _s0 gas components other than the indicator gas in the sample gas before being mixed, since it cracked measurements C _s0 gas concentration measuring unit 21 in a mixing ratio M,

It becomes.

  Thus, in the gas analyzer of the present invention, the sample gas to be sampled is mixed with the indicator gas, and the mixed gas of the flow rate (standard measurement flow rate) corresponding to the measurement capability of the gas concentration measurement unit 20 is sent to the gas concentration measurement unit 20 Since the gas concentration measuring unit 21 is introduced, for example, even when using a gas analyzer having a large standard measurement flow rate such as an FTIR gas analyzer or a QCL-IR gas analyzer, the sampling flow rate of the sample gas is kept minute. Therefore, the response can be obtained at a high speed from the gas concentration measuring unit 20 at all times, and the component concentration of the transiently changing sample gas can be accurately captured.

  Furthermore, even when the sample gas contains the gas component to be measured by the indicator gas concentration meter, the same kind of difference is obtained while the flow rate and concentration measurement value of the sample gas to be sampled are kept constant. The indicator gas of one concentration is switched to be mixed with the sample gas, and the concentration set value for the indicator gas mixed earlier, the measurement value of the second flowmeter and the measurement value of the indicator gas concentration meter, and the indicator gas mixed next Is mixed with the indicator gas using the concentration set value for the second time, the measurement value of the second flowmeter, the measurement value of the indicator gas concentration meter, and the measurement value of the gas concentration measurement unit 20 (the concentration measurement value of the target gas component) The concentration of the target gas component in the sample gas before calculation is calculated, that is, the target gas component concentration value in the sample gas is measured based on the numerical value that is correctly set or measured. Analysis It can be performed with high accuracy.

  Although the preferred embodiments of the present invention have been described above, the configuration of the present invention is not limited to the above embodiments, and various modifications may be made within the scope of the configurations described in the appended claims by those skilled in the art. It goes without saying that you can devise.

For example, FIG. 3 shows a modification of the gas supply unit of the gas analyzer of FIG. In FIG. 3, the same components as those shown in FIG. 2 are denoted by the same reference numerals.
Referring to FIG. 3, in this embodiment, the indicator gas supply unit includes first and second branch passages 14 a and 14 b branched from the upstream end 12 a of the indicator gas passage 12 and a first branch passage. A second indicator gas supply source 15a connected to 14a and supplying a first concentration indicator gas and a second indicator connected to the second branch flow passage 14b to supply a second concentration indicator gas It has a gas supply source 15b, a first flow rate controller 25a disposed in the first branch flow path 14a, and a second flow rate controller 25b disposed in the second branch flow path 14b. .
Further, one second flow meter 18 is disposed in each of the first and second branch paths 14a and 14b.
Then, the supply of the indicator gas of the first and second concentration is switched by alternately switching the opening and closing of the first and second flow rate controllers 25a, 25b.

1 sampling channel 1a downstream end 2 indicator gas supply source 3 indicator gas channel 3a one end 3b other end 4 mixed gas channel 5 gas concentration measuring unit 6 pump 7 flow controller 8 indicator gas concentration meter 9 indicator gas concentration set value input Unit 10 Gas concentration calculation unit 11 Sampling passage 11a Downstream end 12 Index gas passage 12a Upstream end 13 First flowmeter 14a First branch passage 14b Second branch passage 15a First indicator gas supply source 15b Second indicator gas supply source 16 channel switching valve 17 flow controller 18 second flow meter 19 mixed gas channel 20 gas concentration measuring unit 21 pump 22 indicator gas concentration meter 23 indicator gas concentration set value input unit 24 gas concentration Calculation unit 25a first flow rate controller 25b second flow rate controller

Claims (3)

A sampling channel into which a minute flow of sample gas is introduced;
An indicator gas supply unit that switches and supplies two preset indicator gases of different concentrations;
An indicator gas passage which joins the downstream end of the sampling passage and supplies the indicator gas from the indicator gas supply unit to the sampling passage;
A mixed gas flow path extending from a junction of the sampling flow path and the index gas flow path, and a mixed gas of the sample gas and the index gas flowing therein;
A gas concentration measurement unit connected to the downstream end of the mixed gas flow channel and measuring the concentration of the target gas component contained in the sample gas;
And a pump disposed in the mixed gas flow path or an exhaust system of the gas concentration measurement unit, for feeding the mixed gas to the gas concentration measurement unit.
The rotational speed of the pump and the supply amount of the index gas from the index gas supply unit are such that the flow rate of the mixed gas in the mixed gas flow passage corresponds to the flow rate of the gas concentration measurement unit Are adjusted to
A first flow meter disposed in the sampling channel and measuring a flow rate of the sample gas;
A second flow meter disposed in the indicator gas flow passage or incorporated in the indicator gas supply unit and measuring the flow rate of the indicator gas supplied from the indicator gas supply unit to the indicator gas flow passage;
An indicator gas concentration meter, which is incorporated in the gas concentration measurement unit or disposed in the mixed gas flow path, and measures the concentration of the indicator gas;
An index gas concentration set value input unit receiving an input of set values of the two different concentrations of the index gas;
The indicator gas previously supplied when the indicator gas is switched and supplied to the indicator gas flow path while the measurement values of the first flow meter and the gas concentration measurement unit are maintained constant. Concentration set value, measurement value of the second flow meter and measurement value of the index gas concentration meter, concentration set value of the index gas supplied next, measurement value of the second flow meter, and A gas concentration calculation unit that calculates the concentration of the target gas component in the sample gas before being mixed with the indicator gas using the measurement value of the indicator gas concentration meter and the measurement value of the gas concentration measurement unit; , A gas analyzer characterized in that it comprises. The indicator gas supply unit
First and second branch channels branched from the upstream end of the indicator gas channel;
A first indicator gas supply source connected to the first branch channel and supplying the indicator gas of a first concentration of the two different concentrations;
A second indicator gas supply source connected to the second branch channel and supplying the indicator gas of a second concentration of the two different concentrations;
A flow path switching valve provided at a branch point of the first and second branch flow paths and the index gas flow path and switching the flow path between the first and second branch flow paths;
The gas analyzer according to claim 1, further comprising: a flow rate controller disposed downstream of the branch point in the indicator gas flow path. The indicator gas supply unit
First and second branch channels branched from the upstream end of the indicator gas channel;
A first indicator gas supply source connected to the first branch channel and supplying the indicator gas of a first concentration of the two different concentrations;
A second indicator gas supply source connected to the second branch channel and supplying the indicator gas of a second concentration of the two different concentrations;
A first flow rate controller disposed in the first branch flow path;
And a second flow rate controller disposed in the second branch flow path,
The gas analyzer according to claim 1, wherein the second flow meter is disposed in each of the first and second branch paths.

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