JP6079910B2 - Infrared gas analyzer - Google Patents

Description

  In the present invention, the reference gas and the sample gas are alternately supplied into the sample cell, and the sample cell is irradiated with infrared light to perform analysis based on the amount of infrared light transmitted through the sample cell. The present invention relates to a gas analyzer.

Infrared gas analyzers may be used when measuring concentrations of SO ₂ components, NO _x components, CO components, CO ₂ components, etc. as measurement target components contained in sample gas such as exhaust gas. The infrared gas analyzer is equipped with, for example, a sample cell, and the sample gas is supplied into the sample cell and irradiated with infrared light, thereby analyzing based on the amount of infrared light transmitted through the sample cell. Can be done.

  In the infrared gas analyzer, the reference gas and the sample gas are alternately supplied into the sample cell, so that the amount of infrared light transmitted through the reference gas and the amount of infrared light transmitted through the sample gas are reduced. Some are based on analysis. Specifically, the reference gas and the sample gas can be alternately supplied into the sample cell by alternately introducing the reference gas and the sample gas at regular intervals into the supply path communicating with the sample cell. It has become.

  As an example of this type of infrared gas analyzer, a configuration in which a humidity control unit is provided in a supply path in order to adjust the water vapor concentration of a reference gas and a sample gas has been proposed (for example, see Patent Document 1 below). By providing a humidity control section in the supply path, the water vapor concentration of the reference gas and sample gas that are alternately supplied into the sample cell via the supply path can be made equal, so the measurement that occurs based on the difference in water vapor concentration Errors can be suppressed.

In the configuration exemplified in Patent Document 1, the zero point and the span point can be calibrated by introducing the zero gas and the span gas into the supply path. As the zero gas, for example, a gas (N ₂ gas or the like) that does not include the measurement target component can be used. On the other hand, as the span gas, a gas containing a measurement target component at a known concentration can be used.

  Here, since calibration gas such as zero gas and span gas does not contain moisture, when calibration gas is introduced into the supply path where the humidity control section is provided, the measured value is obtained by gradually drying the humidity control section. There is a problem that it takes time to stabilize. Therefore, Patent Document 1 proposes a configuration in which a bypass flow path that communicates with the sample cell without passing through the humidity control section is provided, and the gas flow path can be switched to the humidity control section side or the bypass flow path side. Has been.

  In other words, the reference gas and the sample gas are introduced into the humidity control section to adjust the water vapor concentration and then supplied into the sample cell, and the calibration gas such as zero gas and span gas is introduced into the bypass flow path side. Thus, it can be supplied into the sample cell without going through the humidity control section.

JP 2005-69870 A

  In the configuration as described in Patent Document 1, the gas flow path is different between the sample measurement for supplying the reference gas and the sample gas into the sample cell and the calibration for supplying the calibration gas into the sample cell. The total volume of the flow path is also different. For this reason, there is a problem that an error occurs in the passage time of the gas in each channel between the sample measurement and the calibration, and as a result, an error also occurs in the measurement result.

  FIG. 4 is a diagram for explaining errors that occur in the measurement results in the conventional configuration. FIG. 4A is a diagram showing a change in concentration in the sample cell when zero gas and span gas are alternately supplied into the sample cell from the bypass channel side during calibration. FIG. 4B is a diagram showing a change in concentration in the sample cell when the reference gas and the sample gas are alternately supplied from the humidity control unit side to the sample cell during sample measurement. FIG. 4C is a diagram for comparing the measurement results of FIGS. 4A and 4B.

  At the time of calibration shown in FIG. 4 (a), during the period T101 in which zero gas is supplied from the bypass channel side into the sample cell, the concentration of the measurement target component in the sample cell gradually decreases, and then from the bypass channel side. During the period T102 in which the span gas is supplied into the sample cell, the concentration of the measurement target component in the sample cell gradually increases. As described above, the operation in which the gas in the sample cell is alternately replaced with the zero gas or the span gas is repeated during the fixed periods T101 and T102.

  In this case, since the total volume of the bypass passage through which the zero gas and the span gas pass is relatively small, there is no noticeable delay in the response when the gas in the sample cell is replaced. Therefore, as shown in FIG. 4A, the gas in the sample cell can be completely replaced between the periods T101 and T102.

  During the sample measurement shown in FIG. 4B, the concentration of the measurement target component in the sample cell gradually decreases during the period T201 in which the reference gas is supplied from the humidity control unit to the sample cell. During a period T202 in which the sample gas is supplied from the wet section side into the sample cell, the concentration of the measurement target component in the sample cell gradually increases. As described above, the operation in which the gas in the sample cell is alternately replaced with the reference gas or the sample gas is repeated during a certain period T201, T202.

  In this case, unlike the case of FIG. 4 (a), since the volume of the humidity control section through which the reference gas and the sample gas pass is large, a delay time T203 occurs in the response when the gas in the sample cell is replaced. It becomes. Therefore, as shown in FIG. 4B, the gas in the sample cell may not be completely replaced between the periods T201 and T202.

  As described above, when the delay time T203 occurs in the response when replacing the gas in the sample cell during the sample measurement, as shown in FIG. 4C, the measurement is performed during the calibration and the sample measurement. There is a possibility that an error Δ may occur in the density value. In this case, since an error also occurs in the display value of the measurement result, there is a problem that the analysis cannot be performed with high accuracy.

  In particular, when a measurement target component having a slow flow rate in the flow path is included in the sample gas, the delay time T203 for replacing the gas in the sample cell is further increased during sample measurement. For this reason, there is a problem that the error Δ of the concentration value measured at the time of calibration and at the time of sample measurement is further increased, and the accuracy of analysis is further lowered.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an infrared gas analyzer capable of performing analysis with high accuracy.

  The infrared gas analyzer according to the present invention alternately supplies a reference gas and a sample gas into a sample cell, and irradiates the sample cell with infrared light, thereby obtaining a light amount of infrared light transmitted through the sample cell. An infrared gas analyzer for performing analysis based on a supply channel for supplying a reference gas and a sample gas into the sample cell, and a control unit provided in the supply channel for adjusting the water vapor concentration in the gas. The wet section and the branch section provided upstream of the humidity control section in the supply path branch off from the supply path, and the junction section provided downstream of the humidity control section in the supply path A bypass flow path for bypassing the humidity control section by joining the supply path, and a switching section for switching the gas flow path to the humidity control section side or the bypass flow path side provided in the branch section And said branch In between the merging section from, characterized in that the total volume of the humidity adjusting unit side including the volume of the humidity control unit, and the total volume of the bypass flow are substantially the same.

  According to such a configuration, since the total volume on the humidity control section side including the volume of the humidity control section and the total volume on the bypass flow path side are substantially the same between the branch section and the merge section, The time required to replace the gas in the sample cell is substantially the same at the time of sample measurement. As a result, it is possible to prevent an error from occurring in the concentration values measured during calibration and during sample measurement, so that analysis can be performed with high accuracy.

  The bypass flow path may be formed by a tubular member extending from the branch portion to the junction portion.

  According to such a configuration, the total volume on the bypass flow path side between the branching portion and the merging portion can be made substantially the same as the total volume on the humidity control portion side using a tubular member that can be easily prepared. . In particular, since the tubular member can be set to an arbitrary length, the total volume on the humidity control unit side and the total volume on the bypass flow path side can be accurately made the same.

  The bypass passage may be provided with a volume expansion section having substantially the same volume as the humidity control section.

  According to such a configuration, the total volume on the bypass flow path side between the branching portion and the merging portion is substantially equal to the total volume on the humidity control portion side using the volume expanding portion having substantially the same volume as the humidity control portion. Can be the same. When the bypass channel is formed of a tubular member, a relatively long tubular member must be arranged in the apparatus, so that the tubular member becomes an obstacle during maintenance, and the maintainability may be reduced. By using the volume expanding section as described above, such a problem can be solved and the maintainability is improved.

  Between the branch part and the junction part, the flow path may be provided symmetrically on the humidity control part side and the bypass flow path side.

  According to such a configuration, it is possible to prevent variation in the gas flow between the humidity control unit side and the bypass flow channel side where the flow paths are provided symmetrically between the branch part and the merge part. Therefore, analysis can be performed with higher accuracy.

  The sample gas may be exhaust gas.

  According to such a configuration, when measuring the concentration of the measurement target component contained in the exhaust gas, it is possible to prevent an error from occurring in the concentration value measured during calibration and during sample measurement. You can analyze well. Therefore, an infrared gas analyzer suitable for exhaust gas analysis can be provided.

  According to the present invention, since the time required to replace the gas in the sample cell is substantially the same during calibration and during sample measurement, there is an error in the concentration value measured during calibration and during sample measurement. Since it can be prevented from occurring, the analysis can be performed with high accuracy.

It is the schematic which shows the structural example of the infrared gas analyzer which concerns on one Embodiment of this invention. It is a figure which shows the structural example of a supply path. It is a figure which shows another structural example of a supply path. It is a figure for demonstrating the error which arises in a measurement result in the conventional structure.

FIG. 1 is a schematic diagram showing a configuration example of an infrared gas analyzer according to an embodiment of the present invention. This infrared gas analyzer detects the infrared light transmitted through the sample cell 1 by the detector 3 by supplying the sample gas into the sample cell 1 and irradiating the sample cell 1 with infrared light from the light source 2. The analysis is based on the light quantity (infrared light intensity). As the sample gas, for example, exhaust gas containing SO ₂ component, NO _x component, CO component or CO ₂ component as a measurement target component can be exemplified, and sample gas collected from an exhaust gas flow path such as a flue is used. Can do.

  In the infrared gas analyzer according to this embodiment, by alternately supplying the reference gas and the sample gas into the sample cell 1, the amount of infrared light transmitted through the reference gas and the infrared light transmitted through the sample gas are reduced. Analysis can be performed based on the amount of light. For example, air is used as the reference gas. The reference gas and the sample gas are alternately supplied into the sample cell 1 through the common supply path 4, and are alternately filled in the sample cell 1 and exhausted.

  The sample gas flow path 5 for supplying the sample gas is connected to the supply path 4 via the electromagnetic valve SV3. The electromagnetic valve SV3 is composed of, for example, a three-way valve, and in addition to the supply path 4 and the sample gas flow path 5, an exhaust path 7 for exhausting gas is connected. Therefore, by controlling the electromagnetic valve SV3, switching between the state in which the sample gas is supplied from the sample gas flow path 5 to the supply path 4 and the state in which the sample gas is exhausted from the sample gas flow path 5 to the exhaust path 7 is possible. It can be done.

  The reference gas flow path 6 for supplying the reference gas is connected to the supply path 4 via the electromagnetic valve SV4. The electromagnetic valve SV4 is composed of, for example, a three-way valve, and the exhaust passage 7 is connected in addition to the supply passage 4 and the reference gas passage 6. Therefore, by switching the solenoid valve SV4, switching between the state in which the reference gas is supplied from the reference gas flow path 6 to the supply path 4 and the state in which the reference gas is exhausted from the reference gas flow path 6 to the exhaust path 7 can be performed. It can be done.

  At the time of sample measurement, with the sample gas introduced into the sample gas flow channel 5 and the reference gas introduced into the reference gas flow channel 6, the electromagnetic valve SV3 and the electromagnetic valve SV4 are in a constant cycle (for example, a cycle of 10 seconds). By switching, the reference gas and the sample gas are alternately supplied to the supply path 4. As a result, the operation of alternately replacing the gas in the sample cell 1 with the reference gas or the sample gas is repeated.

Further, in the infrared gas analyzer according to the present embodiment, the zero point and the span point can be calibrated by introducing the calibration gas such as the zero gas and the span gas into the supply path 4. As the zero gas, for example, a gas (N ₂ gas or the like) that does not include the measurement target component can be used. On the other hand, as the span gas, a gas containing a measurement target component at a known concentration can be used.

  The sample gas flow path 5 is provided with, for example, an electromagnetic valve SV1 composed of a three-way valve, and the sample gas or the calibration gas (zero gas or span gas) is introduced into the sample gas flow path 5 by controlling the electromagnetic valve SV1. The sample cell 1 can be supplied via the supply path 4. On the other hand, the reference gas flow path 6 is provided with, for example, an electromagnetic valve SV2 composed of a three-way valve, and the sample gas or the calibration gas (zero gas) is introduced into the reference gas flow path 6 by controlling the electromagnetic valve SV2. The sample cell 1 can be supplied via the supply path 4.

  At the time of calibration, the solenoid valve SV1 introduces the calibration gas (zero gas or span gas) into the sample gas flow path 5 and the solenoid valve SV2 introduces the calibration gas (zero gas) into the reference gas flow path 6 so that the solenoid valve SV3 and solenoid valve SV4 are switched at a constant cycle (for example, a cycle of 10 seconds).

  For example, when the zero point is calibrated, the gas in the sample cell 1 is replaced with the zero gas by introducing the zero gas into the sample gas channel 5 and the reference gas channel 6. On the other hand, when the span point is calibrated, the span gas is introduced into the sample gas flow path 5 and the zero gas is introduced into the reference gas flow path 6 so that the gas in the sample cell 1 is alternately replaced with the span gas or the zero gas. Repeated.

  The supply path 4 is provided with a humidity control unit 8 for adjusting the water vapor concentration in the gas. The humidity control unit 8 is composed of, for example, a humidity controller including a semipermeable membrane water vapor exchange material, and takes water vapor in the gas into the material or releases water vapor into the gas according to the water vapor concentration in the gas. It has a humidity control function. However, the humidity control unit 8 is not limited to the configuration provided with the semipermeable membrane water vapor exchange material, and may be configured by a humidity controller that realizes the humidity control function by another configuration.

  A branch portion 41 is provided upstream of the humidity control section 8 in the supply path 4, and the bypass flow path 9 branches from the supply path 4 at the branch section 41. The branch portion 41 is provided with an electromagnetic valve SV5 made of, for example, a three-way valve. The electromagnetic valve SV5 constitutes a switching unit, and by controlling the electromagnetic valve SV5, the gas flow path can be switched to the humidity control section 8 side or the bypass flow path 9 side. However, the switching unit is not limited to the one configured by the electromagnetic valve SV5, and the gas channel may be switched to the humidity control unit 8 side or the bypass channel 9 side by another configuration.

  The bypass channel 9 joins the supply channel 4 at a junction 42 provided on the downstream side of the humidity control unit 8 in the supply channel 4. Therefore, by controlling the solenoid valve SV5 and switching the gas flow path to the bypass flow path 9 side, the humidity control section 8 can be bypassed and gas can be supplied to the sample cell 1.

  At the time of sample measurement, the sample gas supplied from the sample gas channel 5 to the supply channel 4 and the reference gas supplied from the reference gas channel 6 to the supply channel 4 are respectively led to the humidity control unit 8 side. After the water vapor concentration is adjusted in the humidity control unit 8, the water is supplied into the sample cell 1. On the other hand, at the time of calibration, the calibration gas (zero gas or span gas) supplied from the sample gas channel 5 to the supply channel 4 and the calibration gas (zero gas) supplied from the reference gas channel 6 to the supply channel 4 are bypassed. It is guided to the flow path 9 side and supplied into the sample cell 1 without passing through the humidity control section 8.

  A sector 10 is provided between the sample cell 1 and the light source 2 for intermittently blocking infrared light from the light source 2. The rotation position of the sector 10 is controlled by a drive unit (not shown) such as a motor. The detector 3 is filled with a gas containing a measurement target component, and can detect an infrared light intensity of an absorption wavelength unique to the measurement target component by an internal pressure change.

  A detection signal in the detector 3 is input to the signal processing unit 11. The signal processing unit 11 performs measurement based on the detection signal from the detector 3 when the sample gas is supplied to the sample cell 1 and the detection signal from the detector 3 when the reference gas is supplied to the sample cell 1. Processing for measuring the concentration of the target component is performed. This measurement result can be displayed on the display unit 12 including, for example, a liquid crystal display.

  FIG. 2 is a diagram illustrating a configuration example of the supply path 4. In the supply path 4, an upstream part 43 located upstream from the branching part 41, an intermediate part 44 located between the branching part 41 and the joining part 42, and a downstream located downstream from the joining part 42. Part 45 is included.

  The upstream part 43 is connected to the intermediate part 44 and the bypass flow path 9 via an electromagnetic valve SV5 provided in the branch part 41. Further, the downstream portion 45 is connected to the intermediate portion 44 and the bypass flow path 9 via a T-shaped tube 421 provided in the merging portion 42.

  In the branch portion 41, the same connecting member 13 is used for the connection between the electromagnetic valve SV5 and the intermediate portion 44 and the connection between the electromagnetic valve SV5 and the bypass flow path 9, respectively. In the junction portion 42, the same connecting member 14 is used for connecting the T-shaped tube 421 and the intermediate portion 44 and connecting the T-shaped tube 421 and the bypass flow path 9. In this example, the connecting member 13 is formed in an L-shape and the connecting member 14 is formed in a straight line. However, the present invention is not limited to such a configuration, and the connecting members 13 and 14 having other various shapes are used. Can do.

The humidity control unit 8 is provided in the intermediate unit 44. Between the branching portion 41 and the merging portion 42, the total volume on the humidity adjusting portion 8 side (intermediate portion 44 side) including the volume of the humidity adjusting portion 8 is, for example, 8906 mm ³ .

In this example, the bypass flow path 9 is formed by a tubular member 91 extending from the branch portion 41 to the junction portion 42. The tubular member 91 is formed with a constant inner diameter (for example, 4 mm) from one end to the other end, and has a total volume corresponding to its length. Here, by setting the length of the tubular member 91 to, for example, 708.7 mm, the total volume on the bypass flow path 9 side between the branching portion 41 and the merging portion 42 is set to, for example, 8906 mm ^3. Yes.

  Thus, since the total volume on the humidity control unit 8 side including the volume of the humidity control unit 8 and the total volume on the bypass flow path 9 side are substantially the same between the branching unit 41 and the junction unit 42, calibration is performed. The time required to replace the gas in the sample cell 1 is substantially the same between the measurement time and the sample measurement time. As a result, it is possible to prevent an error from occurring in the concentration values measured during calibration and during sample measurement, so that analysis can be performed with high accuracy.

  In this example, the total volume on the bypass flow path 9 side between the branching portion 41 and the merging portion 42 is made substantially the same as the total volume on the humidity control portion 8 side using the tubular member 91 that can be easily prepared. can do. In particular, since the tubular member 91 can be set to an arbitrary length, the total volume on the humidity control unit 8 side and the total volume on the bypass flow path 9 side can be accurately made the same.

  FIG. 3 is a diagram illustrating another configuration example of the supply path 4. Also in this example, as in the case of FIG. 2, the supply path 4 includes an upstream portion 43 positioned upstream of the branch portion 41, an intermediate portion 44 positioned between the branch portion 41 and the junction portion 42, And the downstream part 45 located in the downstream rather than the confluence | merging part 42 is contained.

  The upstream part 43 is connected to the intermediate part 44 and the bypass flow path 9 via an electromagnetic valve SV5 provided in the branch part 41. Further, the downstream portion 45 is connected to the intermediate portion 44 and the bypass flow path 9 via a T-shaped tube 422 provided in the merging portion 42.

  In the branch portion 41, the same connecting member 15 is used for the connection between the electromagnetic valve SV5 and the intermediate portion 44 and the connection between the electromagnetic valve SV5 and the bypass passage 9. In the junction portion 42, the same connecting member 16 is used for connecting the T-shaped tube 422 and the intermediate portion 44 and connecting the T-shaped tube 422 and the bypass flow path 9. In this example, the connection members 15 and 16 are all formed in an L shape, but the present invention is not limited to such a configuration, and connection members 15 and 16 having various other shapes can be used.

The humidity control unit 8 is provided in the intermediate unit 44. Between the branching portion 41 and the merging portion 42, the total volume on the humidity adjusting portion 8 side (intermediate portion 44 side) including the volume of the humidity adjusting portion 8 is, for example, 8906 mm ³ .

  In this example, the bypass flow path 9 is provided with a volume expansion section 92 having a volume substantially the same as that of the humidity control section 8. The volume expanding portion 92 can be formed of a member having an inner diameter larger than that of the bypass flow path 9. For example, the same humidity controller as that constituting the humidity control unit 8 is used as the volume expansion unit 92 without operating, or the same shape as the humidity controller constituting the humidity control unit 8 If a hollow member having a volume is used as the volume expansion section 92, the flow path can be provided symmetrically between the branching section 41 and the merge section 42 on the humidity control section 8 side and the bypass flow path 9 side. .

  Also in this example, the total volume on the humidity control unit 8 side including the volume of the humidity control unit 8 and the total volume on the bypass flow path 9 side including the volume expansion unit 92 are between the branch unit 41 and the junction unit 42. Since they are substantially the same, the time required to replace the gas in the sample cell 1 is substantially the same during calibration and during sample measurement. As a result, it is possible to prevent an error from occurring in the concentration values measured during calibration and during sample measurement, so that analysis can be performed with high accuracy.

  In particular, when the bypass channel 9 is formed by the tubular member 91 as shown in FIG. 2, the relatively long tubular member 91 must be disposed in the apparatus, and therefore the tubular member 91 becomes an obstacle during maintenance. There is a risk that the maintainability may deteriorate. For example, in the configuration as shown in FIG. 2, the relatively long tubular member 91 of 708.7 mm must be used. However, if the volume expanding portion 92 is used as shown in FIG. And maintainability is improved.

  In addition, when the volume expanding section 92 is used as shown in FIG. 3, gas is provided between the branching section 41 and the merging section 42 between the humidity control section 8 side and the bypass flow path 9 side where the flow paths are provided symmetrically. Since it is possible to prevent variation in the flow, the analysis can be performed with higher accuracy.

  In the above embodiment, the case where the sample gas is exhaust gas has been described. In this case, when measuring the concentration of the component to be measured contained in the exhaust gas, it is possible to prevent an error from occurring in the concentration value measured during calibration and during sample measurement. Can do. Therefore, an infrared gas analyzer suitable for exhaust gas analysis can be provided.

  Moreover, according to the infrared gas analyzer as described above, even when a component having a slow flow rate in the flow path is included in the sample gas as a measurement target component, the analysis can be performed with high accuracy. That is, when a component having a slow flow rate in the flow path is included in the sample gas as a measurement target component, a delay time tends to occur in the response when the gas in the sample cell 1 is replaced. Even in such a case, the total volume on the humidity control unit 8 side including the volume of the humidity control unit 8 and the total volume on the bypass flow path 9 side are substantially the same between the branching unit 41 and the joining unit 42. By doing so, the time required to replace the gas in the sample cell 1 during calibration and during sample measurement can be made substantially the same, so the concentration value measured during calibration and during sample measurement An error can be prevented from occurring.

However, the infrared gas analyzer according to the present invention can perform analysis using not only exhaust gas but also other various gases as sample gases. In this case, the infrared gas analyzer according to the present invention can be applied to the analysis of a sample gas containing a component other than the SO ₂ component, NO _x component, CO component, or CO ₂ component as a measurement target component.

  Below, the result of the effect confirmation test at the time of comprising the bypass flow path 9 using the tubular member 91 like FIG. 2 is demonstrated.

First, a tubular member shorter than that in the case of FIG. 2 is adopted on the bypass flow path 9 side, and the sample gas containing the SO ₂ component as the measurement target component and the sample gas containing the NO component as the measurement target component are respectively analyzed. went. As the tubular member, a member made of a fluororesin having an inner diameter of 4 mm and a length of 80 mm was used. In this case, the total volume on the bypass flow path 9 side is 1005 mm ³ , which is a value much smaller than the total volume (8906 mm ³ ) on the humidity control unit 8 side.

The test results in this case are as shown in Table 1 below. That is, for the sample gas containing the SO ₂ component as the measurement target component, the concentration measured during calibration is 934 ppm, whereas the concentration measured during sample measurement is 930 ppm, resulting in an error of 4 ppm in the concentration value. It was. In addition, for the sample gas containing the NO component as the measurement target component, the concentration measured during calibration is 92.5 ppm, whereas the concentration measured during sample measurement is 89.5 ppm, and the concentration value is 3 ppm. An error has occurred.

Next, a tubular member 91 as shown in FIG. 2 was employed, and the same sample gas was analyzed. As the tubular member 91, a member made of a fluororesin having an inner diameter of 4 mm and a length of 708.7 mm was used as described above. In this case, the total volume on the bypass flow path 9 side is 8906 mm ³ , which is the same as the total volume (8906 mm ³ ) on the humidity control unit 8 side.

The test results in this case are as shown in Table 2 below. That is, for the sample gas containing the SO ₂ component as the measurement target component, the concentration measured at the time of calibration was 934 ppm, whereas the concentration measured at the time of sample measurement was also 934 ppm, and there was no error in the concentration value. . In addition, for the sample gas containing the NO component as the measurement target component, the concentration measured at the time of calibration is 92.5 ppm, whereas the concentration measured at the time of sample measurement is 92.5 ppm, and there is an error in the concentration value. Did not occur.

  From the result of the effect confirmation test as described above, by constructing the bypass channel 9 using the tubular member 91 as shown in FIG. 2, an error occurs in the concentration value measured at the time of calibration and at the time of sample measurement. It can be seen that this can be prevented. According to this result, it is considered that the same effect can be obtained even when the bypass flow path 9 is configured using the volume expanding section 92 as shown in FIG.

DESCRIPTION OF SYMBOLS 1 Sample cell 2 Light source 3 Detector 4 Supply path 5 Sample gas flow path 6 Reference gas flow path 7 Exhaust path 8 Humidity control part 9 Bypass flow path 10 Sector 11 Signal processing part 12 Display part 13-16 Connection member 41 Branch part 42 Junction part 43 Upstream part 44 Intermediate part 45 Downstream part 91 Tubular member 92 Volume expansion part 421, 422 T-shaped tube SV1 to SV5 Solenoid valve

Claims (5)

An infrared gas analyzer that performs analysis based on the amount of infrared light transmitted through the sample cell by alternately supplying reference gas and sample gas into the sample cell and irradiating the sample cell with infrared light. There,
A supply path for supplying a reference gas and a sample gas into the sample cell;
A humidity control unit provided in the supply path for adjusting the water vapor concentration in the gas;
A branch portion provided upstream of the humidity control section in the supply path branches off from the supply path, and joins the supply path at a junction section provided downstream of the humidity control section in the supply path. Bypassing the bypass for bypassing the humidity control unit,
A switching unit provided in the branching unit, for switching a gas flow channel to the humidity control unit side or the bypass flow channel side;
Infrared gas analysis characterized in that the total volume on the humidity control section side including the volume of the humidity control section and the total volume on the bypass flow path side are substantially the same between the branch section and the merge section. apparatus.   The infrared gas analyzer according to claim 1, wherein the bypass flow path is formed by a tubular member extending from the branch portion to the merge portion.   The infrared gas analyzer according to claim 1, wherein the bypass channel is provided with a volume expansion unit having a volume substantially the same as that of the humidity control unit.   4. The infrared gas analyzer according to claim 3, wherein the flow path is provided symmetrically between the branching section and the merge section on the humidity control section side and the bypass flow path side.   The infrared gas analyzer according to any one of claims 1 to 4, wherein the sample gas is an exhaust gas.

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