JP4314737B2 - Chemiluminescent nitrogen oxide concentration meter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to chemiluminescent nitrogen in which the concentration of nitrogen oxides contained in boiler flue exhaust gas, automobile exhaust gas, and the like is measured using chemiluminescence by the reaction of nitrogen monoxide (NO) and ozone (O ₃ ). It relates to an oxide densitometer.
[0002]
[Prior art]
Nitrogen oxides (NO _x ) that are harmful to human bodies due to combustion in incinerators of factories and combustion in automobile engines are a problem. one, a chemiluminescent nitrogen oxide concentration meter by chemiluminescence method (hereinafter, referred to as NO _X meter) it is.
This is because sample gas (sample gas collected from the atmosphere or exhaust gas) and ozone (O ₃ ) are brought into contact with each other in a reaction tank in the measuring apparatus, and NO and O ₃ in the sample gas cause a chemical reaction. The concentration of NO in the sample gas is measured by detecting the intensity of chemiluminescence generated when nitrogen dioxide (NO ₂ ) is generated with a photodetector.
[0003]
Nitrogen oxides contained in the ambient air are mainly NO ₂ and NO, but NO ₂ does not have a chemiluminescence reaction with O _3, and cannot be measured by the chemiluminescence method as it is. Therefore, in the NO _x meter, NO ₂ and NO coexist by interposing a converter provided with a catalyst in the sample gas introduction flow channel for introducing the sample gas into the reaction tank of the measurement unit so that the NO ₂ concentration can be measured. The sample gas in the ambient atmosphere is reduced and converted into NO by converting NO ₂ in the sample gas into NO through a converter and measured by the chemiluminescence method. Here, the resulting measured value through the converter, for NO ₂ and NO in the combined NO _X (= NO + NO ₂₎ amount to determine the NO ₂ concentration by subtracting the NO concentration when impervious converter.
[0004]
[Problems to be solved by the invention]
However, the NO _x meter has the following problems because a converter provided with a catalyst is interposed in the sample gas introduction flow path for supplying the sample gas into the reaction vessel of the apparatus measurement unit.
[0005]
That is, the converter catalyst deteriorates with time, and the reduction ability of the catalyst, that is, the NO ₂ -NO conversion efficiency is lowered. Therefore, the measurement error becomes large and there is a problem in terms of reliability of the measured value.
Therefore, in order to maintain and ensure measurement accuracy, the catalyst in the converter, or in the case of the cartridge type, the converter reaction tube that houses the catalyst is appropriately packed with new catalyst in the converter according to the number of measurements and the period. However, the degree of deterioration of the catalyst varies depending on the sample gas to be measured (for example, the exhaust gas from the gas turbine has a high ratio of NO _{2 to} NO _x, so the deterioration of the catalyst is severe. ), It is difficult to properly determine when to refill the catalyst or replace the converter reaction tube. For this reason, there is often a problem that a measurement error occurs in the measurement using the deteriorated catalyst.
The replacement of the catalyst in the converter with a new one and the replacement of the converter reaction tube in the cartridge type containing the catalyst are collectively referred to as catalyst replacement hereinafter.
[0006]
In order to avoid measurement due to the use of a deteriorated catalyst, it is only necessary to perform periodic catalyst replacement in anticipation of safety. Effective due to the fact that no consideration has been given to the deterioration rate depending on the environment, and the catalyst still has a reduction capacity sufficient to guarantee the measurement accuracy, but the expensive catalyst will be discarded. This wastes unnecessary resources, increases the running cost of the measuring apparatus, requires frequent replacement work, and is troublesome and time consuming, resulting in a decrease in measurement efficiency.
[0007]
In addition, in order to determine the deterioration degree of the converter and appropriately determine the timing of catalyst replacement, a standard gas with a known NO ₂ concentration is supplied to the sample gas introduction flow path instead of the sample gas, and this NO ₂ standard gas is supplied to the converter. It is reduced and converted to NO through a converter, supplied to the reaction vessel of the measurement unit to which O ₃ is supplied, and the chemiluminescence intensity generated by the chemical reaction is measured, and the NO ₂ concentration of the standard gas (to be precise, the converted NO ₂₎ Concentration) is measured and compared with the NO ₂ concentration value of the standard gas with a known NO ₂ concentration measured immediately after the replacement of the converter catalyst, thereby measuring the degree of deterioration of the catalyst and accurately determining the catalyst replacement timing. It becomes possible.
[0008]
However, this requires a standard gas supply source known to be NO ₂ (usually, a NO ₂ gas cylinder), which is costly and laborious. The actual situation is that confirmation of the degree of deterioration is not generally performed.
[0009]
In view of the above, the present invention can determine the degree of deterioration of the converter catalyst without using standard gas for determination or confirmation of the converter catalyst, and can easily and accurately (appropriately) replace the converter catalyst at an appropriate time. It is an object of the present invention to provide a chemiluminescent nitrogen oxide concentration meter that can be determined and can automatically determine the replacement time in a routine.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, in the chemiluminescent nitrogen oxide concentration meter of the present invention, exhaust gas in which O ₃ is decomposed through an ozone killer (ozone decomposer) after a chemical reaction in a reaction vessel is used. , Passing through a converter intervening in the sample gas introduction flow path, leading to the reaction tank of the measuring section, and determining the deterioration degree of the catalyst based on the chemiluminescence intensity generated by the chemical reaction with ozone gas in the reaction tank It has become.
[0011]
Specifically, it is an NO _X meter that introduces sample gas and ozone gas into the reaction tank of the measurement unit and measures the chemiluminescence intensity due to the chemical reaction with the photodetector of the measurement unit, and the exhaust gas that has passed through the ozone killer The chemiluminescence intensity generated by the chemical reaction between the ozone gas and the exhaust gas that has passed through the converter in the reaction tank and the flow path leading the sample gas to the converter in the reaction tank is measured, and the converter is based on the measured value. And a control means for determining the degree of deterioration of the catalyst.
The NO _X meter of this type, in the reaction vessel of the measuring unit, an ozone killer are (ozone decomposer) exhaust gas flow path having a connection, excess O unreacted exhaust gas in ozone killer After decomposing ₃ , exhaust gas is released into the atmosphere.
[0012]
The present invention pays attention to the fact that NO ₂ is contained in the exhaust gas decomposed by the ozone killer, and a novel idea of whether or not the deterioration degree of the converter catalyst can be judged using NO ₂ in the exhaust gas as a standard gas. It is based on.
That is, in the NO _x meter, the atmosphere (air) is introduced into a silent discharge type ozone generator and oxygen (O ₂ ) in the atmosphere is converted to O _3. At this time, the ozone generator , _{N 2} in the atmosphere is NO ₂ also occurs with oxidized _{O 3} by _{O 3.}
Thus, in the NO _x meter, O ₂ in the atmosphere is converted to O ₃ by the ozone generator, so the concentration of NO ₂ generated together with O ₃ 3 by the ozone generator is mainly supplied to the generator. Depends on the atmospheric flow rate and moisture content. However, the effects of changes in the atmospheric flow rate can be corrected from the flow rate measured by the flow sensor, and the moisture content is kept constant by an electronic cooler, so the concentration of NO ₂ is approximately constant at several tens of ppm. It was confirmed by experiment.
[0013]
From this point of view, as described above, the NO ₂ concentration in the exhaust gas of the reaction tank after the chemical reaction (actually, it is the NO concentration because NO ₂ in the exhaust gas is converted into NO by the converter). However, for the sake of convenience, the NO ₂ concentration will be measured as appropriate for the sake of convenience by the chemiluminescence method, so that the degree of deterioration (degradation degree) of the converter catalyst can be measured and determined, and the time for replacement of the converter catalyst can be found.
That is, the NO ₂ concentration in the exhaust gas is measured from the chemiluminescence intensity of the reaction tank, and the control means compares this measured value with a predetermined value at normal time when the converter catalyst is not deteriorated. When the measured value falls below the predetermined value, the reduction efficiency of the converter catalyst has deteriorated to such an extent that the predetermined measurement accuracy cannot be obtained, so an instruction to replace the converter catalyst is issued.
[0014]
The instruction for replacement of the converter catalyst of the control means is displayed on the display unit as an indication that the catalyst needs to be replaced, or as an alarm or the like from the notification unit, thereby reducing the reduction efficiency of the catalyst currently used for measurement. Therefore, the operator can detect that it is time for replacement with a new converter catalyst without being used as a catalyst.
[0015]
In addition, the predetermined value compared with the measured value of the chemiluminescence intensity of NO in the exhaust gas from the reaction tank was subjected to ozonolysis with an ozone killer measured using the converter catalyst immediately after replacement with a new converter catalyst. Converter in determination mode of NO ₂ (NO) chemiluminescence intensity value in exhaust gas of reaction tank, NO ₂ (NO) concentration value obtained by arithmetic processing from chemiluminescence intensity and deterioration degree of converter catalyst For the chemiluminescence intensity value of NO ₂ in the exhaust gas by the catalyst, or the difference (or ratio) from the NO ₂ (NO) concentration value obtained from the calculation processing, or the analysis (measurement) accuracy chemiluminescence intensity of nO in the exhaust gas by the converter catalyst deterioration without limit trouble, to, at _{2 (nO)} concentration in the exhaust gas obtained by the arithmetic processing from the chemiluminescence intensity Beforehand through experiments, those obtained by measurement or the like.
[0016]
In addition, the concentration of NO ₂ generated by the ozone generator depends on the flow rate of atmospheric gas introduced into the generator, the amount of moisture, the ambient temperature, etc. This is a flow sensor built in the NO _x meter. (Flow meter) The correction of the NO ₂ concentration (measurement) value generated by the ozone generator from the value of the temperature sensor of the electronic cooler that dehumidifies the atmosphere and keeps a constant amount of water or the temperature sensor built in the NO _x meter is Is possible.
Therefore, the deterioration degree of the converter catalyst can be determined without using a standard gas (cylinder) with a known NO ₂ concentration, the replacement timing thereof can be accurately determined, and measurement using a converter catalyst with reduced reduction efficiency can be performed. It can be prevented beforehand.
[0017]
Furthermore, since the converter catalyst can be used until its reduction efficiency has deteriorated to the extent that the measurement accuracy can be guaranteed, even if the converter catalyst is periodically replaced, the number of replacements can be reduced and effective use of resources can be achieved. Can be planned.
In addition, a solenoid valve, etc. is provided in the flow path that guides the exhaust gas from the reaction tank after passing through the ozone killer to the converter, and this solenoid valve is controlled by a CPU, etc., so that the converter catalyst deterioration degree routine is automatically determined by a routine. Is possible.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to examples shown in the drawings.
FIG. 1 is a schematic configuration diagram showing the configuration of an NO _x meter according to one embodiment of the present invention.
The NO _x meter 1 shown in FIG. 1 includes a three-way solenoid valve SV1, a pretreatment unit 21 including an electronic cooler and a filter, a pump P1, a three-way solenoid valve SV2, a NO ₂ -NO converter 22, and a flow meter 23 as sample gases. An ozone gas introduction path 3 in which a sample gas introduction flow path 2, an electronic cooler 31, a pump P 2, a flow meter 32, a silent discharge type ozone generator 33 and the like are sequentially arranged in the air flow direction, Exhaust gas passages 4 each having an ozone killer (ozone decomposer) 41 such as a thermal decomposition type are provided, and each of the flow passages 2, 3, 4 constitutes a NO _x measuring unit 5 with a photoelectric detector 51. It is connected to the reaction tank 52.
[0019]
A standard gas introduction path 6 is connected to the three-way solenoid valve SV1, and a zero gas introduction path 7 and a span gas introduction path 8 connected to a calibration zero gas and span gas supply source (usually a cylinder) are connected to the flow path 6. The three-way solenoid valve SV2 is connected to each other via the solenoid valves SV3 and SV4. In addition, the sample gas is introduced into the reaction tank 52 without passing through the converter 22 when measuring NO _x (= NO ₂ + NO). The bypass path 24 is connected. These configurations, the difference between the arrangement order of each component precisely there is no place to be essentially river with this conventional type of the NO _X meter.
[0020]
9 is a return flow path for guiding the exhaust gas in the reaction tank 52 that has passed through the ozone killer 41 of the exhaust gas flow path 4 newly provided in the present invention to the converter 22 of the sample gas introduction flow path 2. In the embodiment, the standard gas introduction path 6 connected to the three-way solenoid valve SV1 is connected via the solenoid valve SV5.
[0021]
The output of the photoelectric detector 51 of the measuring unit 5 is connected to an arithmetic processing / control unit 10 mainly composed of a CPU, and the arithmetic processing / control unit 10 indicates the chemiluminescence intensity detected by the photoelectric detector 51. The output signal is processed to obtain NO _x or NO concentration, the operation of the solenoid valves SV5, SV1 to SV4, the pumps P1, P2 is controlled, and the converter 22 interposed in the sample gas introduction channel 2 is provided. In the mode for determining (measuring) the degree of deterioration of the reduction efficiency (capacity) of the catalyst, if the reduction efficiency of the catalyst has deteriorated to such an extent that the measurement accuracy cannot be guaranteed (cannot be used for analysis), An output signal is generated indicating that replacement is required, that is, it is time to replace the catalyst. Note that the arithmetic processing / control unit 10 is connected to a display unit (not shown), a notification unit, a recorder, a keyboard, and the like that are operated by an output signal thereof.
[0022]
Next, the case where the NO _x concentration and the NO concentration in the sample gas are measured in the normal measurement mode using the NO _x meter having the above configuration will be described.
First, in the measurement of NO _x , under the control of the arithmetic control / control unit 10, the three-way solenoid valve SV1 converts the sample gas into the pretreatment unit 21 and the three-way solenoid valve SV2 converts the sample gas into the converter. 22 is switched to the side to be introduced to 22 (the side to close the bypass path 24), and the electromagnetic valves SV5, SV3, SV4 are closed.
When the pumps P1 and P2 are driven under the control of the arithmetic control / control unit 10 in this state, the sample gas introduced into the sample gas flow path 2 and dedusted / dehumidified by the pretreatment unit 21 is converted by the converter 22. The contained NO ₂ component is converted into NO, is made to have a constant flow rate by the flow meter 23, and is introduced into the reaction tank 52 of the measurement unit 5.
[0023]
On the other hand, the external air introduced into the ozone gas introduction flow rate 3 and subjected to the dehumidification treatment by the electronic cooler 31 is transferred to the ozone generator 33 with a constant flow rate by the flow meter 32, where O ₃ gas is removed by silent discharge. The O ₃ gas is generated and introduced into the reaction tank 52 of the measurement unit 5.
The sample gas introduced into the reaction tank 52 of the measuring unit 5 and the O ₃ gas are mixed. As a result, the NO component in the sample gas reacts with O ₃ to generate chemiluminescence, and the intensity thereof is measured by the photoelectric detector 51. Measured. The signal intensity of chemiluminescence is proportional to the NO concentration in the sample gas component, the measured chemiluminescence intensity is processing by the arithmetic processing / control unit 10 concentration of NO _X in the sample gas are quantified, computed The information is displayed on a display unit (not shown) connected to the processing / control unit 10.
[0024]
In addition, the measurement of NO is the same as the measurement of NO _X in the electromagnetic valves SV5, SV1, SV3, SV4 under the control of the arithmetic control / control section 10, and the three-way electromagnetic valve SV2 is switched to the bypass path 24 side. Then, the sample gas passes through the flow meter 23 without passing through the converter 22 and is introduced from the ozone gas introduction flow path 3 into the reaction tank 52 of the measuring unit 5 where the O ₃ gas is introduced. It is measured by the photoelectric detector 51. The measured chemiluminescence intensity is arithmetically processed by the arithmetic processing / control unit 10 and the NO concentration in the sample gas is quantified and displayed on a display unit (not shown) connected to the arithmetic processing / control unit 10.
Note that the NO ₂ concentration is calculated by subtracting the NO concentration in the sample gas that does not pass through the converter 22 from the NO concentration in the sample gas that has passed through the converter 22, that is, the NO _x (= NO ₂ + NO) concentration.
[0025]
Further, in the calibration mode, the three-way solenoid valve SV1 is switched to the standard gas flow path 6 side with the solenoid valve SV5 closed, the solenoid valve SV3 is opened, and zero gas is supplied to the reaction tank 52 from the zero gas introduction path 7. Zero calibration is performed, and span calibration is performed by opening the solenoid valve SV4 and supplying span gas to the reaction tank 52 from the span gas conduit 8.
Such normal NO _x concentration, measurement of NO concentration, and zero / span calibration operation are not different from the conventional NO _x meter.
[0026]
Next, a determination mode for the degree of deterioration of the reduction efficiency (reduction capability) of the catalyst of the converter 22 interposed in the sample gas introduction channel 2 which is a feature of the present invention will be described.
In addition, the judgment mode is performed at any time by interrupting the measurement mode and the calibration mode when the measured value is considered inappropriate or when it is desired to judge or confirm the deterioration degree of the catalyst. You may make it carry out regularly by a routine automatically after calibration.
When it is desired to determine the deterioration of the catalyst, the mode is switched to the determination mode of the degree of deterioration of the catalyst using a keyboard (not shown) connected to the arithmetic processing / control unit 10 or a mode change switch (not shown).
[0027]
Thereby, under the control of the arithmetic processing / control unit 10, the three-way solenoid valve SV 1 introduces the sample gas into the converter 22 on the standard gas passage 6 side connected to the return passage 9. Is switched to the side (the side where the bypass passage 24 is closed), and the pumps P1 and P2 are driven.
First, SV3 is opened with the solenoid valves SV4 and SV5 closed, zero gas (N ₂ ) is introduced, and the sample gas remaining in the sample gas introduction channel 2 and the exhaust gas channel 4 is completely exhausted. Next, after SV3 is closed and zero gas introduction is stopped, SV5 is opened.
Thus, exhaust gas containing excess O ₃ of unreacted from the reaction vessel 52 of the measuring unit 5, O ₃ is thermally decomposed by the ozone killer 41 interposed in the exhaust gas passage 4, O ozone generator 33 _The NO ₂ gas generated together with the _three gases is introduced into the converter 22 via the pretreatment unit 21, the NO ₂ component in the exhaust gas is converted to NO, and the flow rate is adjusted to a constant flow rate by the flow meter 23. It is introduced into the reaction tank 52.
[0028]
The NO ₂ (NO) component in the exhaust gas introduced into the reaction tank 33 reacts with O ₃ introduced from the ozone gas introduction flow path 3 provided with the ozone generator 33 in the same tank 52 to generate chemiluminescence, The intensity is measured by the photoelectric detector 51, the measured chemiluminescence intensity is arithmetically processed by the arithmetic processing / control unit 10, the NO ₂ (NO) concentration in the sample gas is quantified, and the measurement is performed when the indication is stabilized. The value D is stored in the memory of the arithmetic processing / control unit 10.
[0029]
The measured NO ₂ (NO) concentration D of the exhaust gas is a predetermined value threshold K stored in advance in the arithmetic processing / control unit 10 (for example, the ozone killer 41 measured immediately after replacement of the converter catalyst). Compared to the difference or ratio between the NO concentration value in the exhaust gas of the reaction tank 52 subjected to ozonolysis and the NO ₂ (NO) concentration value in the exhaust gas in the determination mode, the threshold value K is exceeded. If (D> K), it is determined that the deterioration of the catalyst of the converter 22 is small, and nothing is displayed or an alarm is not issued, so that the reduction efficiency of the catalyst cannot be ensured to ensure measurement accuracy. It can be confirmed that the NO _x / NO of the sample gas can be continuously measured without refilling and replacing the catalyst with a new one. In this case, you may make it transfer to a normal measurement mode automatically.
[0030]
On the other hand, when the value is below the threshold value K (D <K), it is determined that the deterioration of the catalyst is large, and the arithmetic processing / control unit 10 sends a signal to a display unit (not shown) to “require catalyst replacement”. Messages such as “decrease in efficiency” and “poor measurement accuracy” are displayed, and a notification unit is activated to generate an alarm.
[0031]
The predetermined value is, for example, the chemistry of NO ₂ (NO) in the exhaust gas of the reaction tank that has been ozone-decomposed with an ozone killer measured immediately after the converter catalyst is refilled with a new catalyst (replaced with a new catalyst). NO concentration value obtained by calculation processing from emission intensity value or chemiluminescence intensity and NO ₂ concentration obtained by calculation processing from chemiluminescence intensity value of NO in exhaust gas in determination mode or chemiluminescence intensity The chemiluminescence intensity of NO _{2 in} the exhaust gas or the exhaust gas corresponding to the chemiluminescence intensity when the reduction capacity of the catalyst deteriorates to the limit that does not interfere with the difference or ratio with the value or the analysis (measurement) accuracy The NO ₂ (NO) concentration in the gas, which is obtained in advance through experiments, measurements, etc., and is stored in advance in the memory of the arithmetic processing / control unit 10.
In addition, the predetermined value is not a predetermined constant value but includes an allowable error range that does not affect the measurement accuracy.
[0032]
As a result, the operator can determine or confirm that the reduction efficiency of the catalyst has deteriorated to such an extent that the measurement (analysis) is hindered, and it is time to replace the catalyst. Replace refill.
[0033]
In this way, it is possible to easily determine whether or not the catalyst needs to be replaced at an arbitrary point in the middle of the measurement mode, and it is possible to continuously perform highly reliable determination of NO _x for a long period of time.
In particular, the ratio of NO _{2 to} NO _x is high, and this is effective for measuring the exhaust gas of a gas turbine in which the converter is severely deteriorated.
In addition, since the deterioration of the catalyst can be judged easily and accurately without using a standard gas (cylinder) with a known NO ₂ concentration, measurement (analysis) using a catalyst with reduced efficiency can be prevented and measured. Since it can be used without replacing the catalyst until the reduction efficiency deteriorates to the extent that accuracy can be ensured, even when the catalyst is periodically replaced, the number of catalyst replacements can be reduced and resources can be used effectively. .
[0034]
In the embodiment, the deteriorated catalyst in the converter interposed in the sample gas introduction channel is refilled with a new catalyst. However, when the converter is a cartridge type, the converter reaction tube is replaced.
In the embodiment, the determination mode for determining the degree of deterioration of the catalyst is switched from time to time by operating the keyboard or switch. However, the determination mode is automatically switched to the determination mode before and after the measurement mode or periodically after calibration. It is also possible.
[0035]
Further, since the concentration of NO ₂ generated together with O ₃ by the ozone generator interposed in the ozone gas introduction flow path depends on the flow rate of air (air) introduced into the ozone generator, the amount of moisture, the ambient temperature, etc. The flow rate of air introduced into the generator, the temperature of the electronic cooler used for dehumidification, the ambient temperature, etc. are detected, and the NO ₂ measurement (concentration) value (actually the NO measurement value) is corrected with these detection values. Then, it becomes possible to determine the degree of deterioration of the catalyst more accurately. In this case, the flow rate of air introduced into the ozone generator, the electronic cooler temperature, the detection of such ambient temperatures may be used a flow sensor or a temperature sensor NO _X meter of this type are built.
[0036]
【The invention's effect】
According to the chemiluminescent nitrogen oxide concentration meter of the present invention, it is possible to easily determine whether or not it is necessary to replace the converter catalyst interposed in the sample gas introduction channel for converting NO ₂ in the sample gas into NO. Therefore, its usefulness is extremely great in performing long-term reliable measurement.
[0037]
In addition, since it is possible to determine whether or not it is necessary to replace the converter catalyst, it is possible to prevent measurement using a catalyst with reduced efficiency, and to replace the catalyst up to the limit at which reduction efficiency is reduced to the extent that measurement accuracy can be ensured. Therefore, even when the catalyst is periodically replaced, the number of catalyst replacements can be reduced, and the resources can be used effectively.
[0038]
Furthermore, since a standard gas (cylinder) with a known NO ₂ concentration is not required for determining whether or not the converter catalyst needs to be replaced, the running cost can be reduced.
[Brief description of the drawings]
1 is a configuration explanatory view showing an NO _X meter of one embodiment of the present invention.
[Explanation of symbols]
1: NO _X meter 2: Sample gas introduction flow path 21: Pretreatment section 22 ... NO ₂ -NO converter 23 ... Flow meter 24 ... Bypass path 3: Ozone gas introduction flow path 31 ... Electronic cooler 32 ... Flow meter 33 ... Ozone generation vessel 4: exhaust gas flow passage 41 ... ozone killer 5: NO _X measuring unit 51 ... photodetector 52 ... reactor 6: standard gas introducing passage 7: zero gas introduction path 8: span gas conduit 9: return passage 10: Arithmetic processing / control unit SV1, SV2: Three-way solenoid valve P1, P2: Pump SV5, SV3, SV4: Solenoid valve

Claims (1)

Connect the sample gas introduction flow path that can supply the sample gas via the NO ₂ -NO converter to the reaction tank of the measuring unit to which the ozone gas introduction flow path and the exhaust gas flow path having an ozone killer that decomposes ozone are connected. A chemiluminescent nitrogen oxide concentration meter for measuring a chemiluminescence intensity generated by a chemical reaction between the sample gas and ozone in the reaction vessel with a photodetector of a measuring section, wherein the exhaust gas after passing through the ozone killer And a control means for judging the degree of deterioration of the converter catalyst based on the measurement output of the chemiluminescence intensity generated by the chemical reaction between the exhaust gas and ozone in the reaction tank. A chemiluminescent nitrogen oxide concentration meter.

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