JPH10316404A - Ozone generator for preparation of calibration gas, calibration gas generator, ozone analyzer and nitrogen oxide analyzer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ozone generator that generates ozone for calibration by irradiating oxygen with ultraviolet rays from an ultraviolet source, where the ozone generation amount can be stabilized in a short time after the ultraviolet source is switched on, and ozone generation amount can be accurately and automatically controlled, and also a temperature-controller for controlling the peripheral temperature of the ultraviolet ray source is not required. SOLUTION: A xenon flush lamp 6 is used as an ultraviolet source and oxygen is irradiated with the ultraviolet rays from the xenon flush lamp 6 to generate ozone. The ozone generation is controlled by setting a lightening and frequency-controlling means 10 for the xenon flush lamp 6 and controlling the lightening and the frequency for the xenon lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analyzer using an ozone-containing gas as a gas for calibration, for example, an ozone analyzer based on a chemiluminescence method or an ultraviolet absorption method, and a nitrogen oxide analyzer based on a chemiluminescence method. The present invention relates to an ozone generator used in a gas preparation device for industrial use. The present invention also relates to a gas preparation device for calibrating ozone or nitrogen oxides using the above-mentioned ozone generator, and to an ozone analyzer and a nitrogen oxide analyzer provided with these devices.

[0002]

2. Description of the Related Art An ozone analyzer based on a chemiluminescence method or an ultraviolet absorption method uses an ozone calibration gas to calibrate its indicated value. In addition, in a nitrogen oxide analyzer based on the chemiluminescence method, in principle, nitrogen dioxide is converted into nitric oxide by a converter before detection, but in order to determine the conversion efficiency of the converter, a nitrogen oxide calibration gas is used. Used.
In this case, the nitrogen oxide calibration gas is obtained by reacting a known concentration of nitric oxide with an ozone calibration gas. Conventionally, as an ozone generator for obtaining these calibration gases, an ozone generator configured to irradiate air with ultraviolet light from a low-pressure mercury lamp to generate ozone is used.

FIG. 11 is a flowchart showing an example of a calibration gas preparation apparatus using the above-mentioned ozone generator using a low-pressure mercury lamp. In this apparatus, high-purity air is flowed through a quartz tube, and the quartz tube is irradiated with ultraviolet rays from a low-pressure mercury lamp to excite oxygen in the high-purity air to generate ozone. In this case, the ozone generation amount is controlled by adjusting the discharge current of the low-pressure mercury lamp or the position of the irradiation amount adjusting sleeve covering the irradiation surface of the low-pressure mercury lamp. The ozone concentration in the calibration gas is checked according to JIS-B-795.
7.2.2.2 (2) Measurement of ozone concentration (neutral potassium iodide method).

[0004]

The above-mentioned conventional ozone generator for preparing a calibration gas using a low-pressure mercury lamp as the ultraviolet light source has the following disadvantages. The low-pressure mercury lamp has a large temperature characteristic, and the radiation intensity of ultraviolet rays is affected by the temperature (the temperature of the low-pressure mercury lamp and the ambient temperature of the low-pressure mercury lamp). Therefore, a calibration gas preparation device using an ozone generator with a low-pressure mercury lamp has a difference in ozone generation amount depending on the temperature, even if the discharge current and irradiation area of the low-pressure mercury lamp are the same. The ambient temperature is controlled to about 50 ° C. at which ozone is generated most efficiently. Therefore, a temperature adjusting means (a constant temperature bath or the like) for adjusting the ambient temperature of the low-pressure mercury lamp is required, which complicates the apparatus configuration and is disadvantageous in cost.

[0005] When the low-pressure mercury lamp and the temperature control means are both turned off, that is, when the low-pressure mercury lamp is cooled to about room temperature and the temperature of the low-pressure mercury lamp is not adjusted by the temperature control means, the low-pressure mercury lamp is turned off. When the temperature control means is turned on (cold start), since the low-pressure mercury lamp has a large temperature characteristic, the temperature of the low-pressure mercury lamp and the ambient temperature of the low-pressure mercury lamp are stabilized, and it takes time until the amount of generated ozone is stabilized. Therefore, calibration and
It takes time to perform a gas test using a calibration gas such as repeatability, span drift, pointing error, and response time.

When the low-pressure mercury lamp is off and the temperature control means is on, that is, the temperature adjustment of the ambient temperature of the low-pressure mercury lamp is performed by the temperature control means, but the low-pressure mercury lamp is turned on from a state in which the low-pressure mercury lamp is not turned on. Even in this case (hot start), since the low-pressure mercury lamp has a large temperature characteristic, it takes time for the temperature of the low-pressure mercury lamp to stabilize and the amount of ozone generated to stabilize. For example, when the low-pressure mercury lamp is turned off and turned on again, it takes time until the ozone generation amount becomes stable after re-lighting. Therefore, it takes a particularly long time to perform the repeatability test. The repeatability test is a process in which zero gas is introduced into the analyzer at a set flow rate and the final measurement value is confirmed, and then the operation of similarly introducing span gas and confirming the final measurement value is repeated about three times. This is a test in which the average of each value and span value is calculated to determine the difference between each measured value and the average.

An ozone generator using a low-pressure mercury lamp has poor controllability of the amount of ozone generated. That is, it is actually quite difficult to precisely control the ozone generation amount by adjusting the position of the irradiation amount adjusting sleeve that covers the irradiation surface of the low-pressure mercury lamp. It is also difficult to automatically adjust the position of the irradiation amount adjusting sleeve using a computer. Further, even when the amount of ozone generated is controlled by adjusting the discharge current of the low-pressure mercury lamp, it is difficult to control the amount of generated ozone with high accuracy because the low-pressure mercury lamp has a large temperature characteristic.

The present invention has been made in view of the above circumstances, stabilizes the amount of generated ozone in a short time after turning on the ultraviolet light source, enables accurate control of the amount of generated ozone, and enables ozone generation. It is an object of the present invention to provide a calibration gas preparation ozone generator which can easily control the amount automatically and can eliminate the need for temperature control means for controlling the ambient temperature of the ultraviolet light source. I do. Another object of the present invention is to provide an ozone or nitrogen oxide calibration gas preparation device, an ozone analyzer, and a nitrogen oxide analyzer using the above-described calibration gas preparation ozone generator.

[0009]

According to the present invention, there is provided an ozone generator for preparing a calibration gas, comprising: irradiating oxygen from a xenon flash lamp to oxygen to generate ozone. provide.

Further, the present invention provides an ozone calibration gas preparation apparatus provided with the calibration gas preparation ozone generator and an oxygen supply source, and an ozone calibration gas preparation apparatus having a known concentration. Provided is a nitrogen oxide calibration gas preparation apparatus which includes a nitrogen monoxide supply source and reacts the ozone calibration gas prepared by the ozone calibration gas preparation apparatus with nitric oxide to produce nitrogen dioxide.

Further, according to the present invention, there is provided an ozone calibration gas preparation apparatus, wherein an indicated value is calibrated using an ozone calibration gas prepared by the calibration gas preparation apparatus. A nitrogen oxide meter having a converter for converting nitrogen dioxide to nitric oxide, comprising a nitrogen oxide calibration gas preparation device, and a nitrogen oxide prepared by the calibration gas preparation device. Provided is a nitrogen oxide analyzer characterized in that the conversion efficiency of a converter is obtained by using a calibration gas.

A xenon flash lamp (described later) has small temperature characteristics, and the radiation intensity of ultraviolet rays is hardly affected by the temperature (the temperature of the xenon flash lamp and the ambient temperature of the xenon flash lamp). Therefore, the calibration gas preparation ozone generator of the present invention using a xenon flash lamp as an ultraviolet light source can obtain a stable ozone generation amount even when the temperature of the xenon flash lamp and the ambient temperature of the xenon flash lamp are not so stable. Since the xenon flash lamp is turned on, the amount of ozone generated can be stabilized in a short time after turning on the xenon flash lamp, the time required for calibration and gas test can be shortened, and a temperature adjusting means for adjusting the ambient temperature of the xenon flash lamp Can be eliminated, and the apparatus configuration can be simplified and the cost can be reduced.

Further, since the xenon flash lamp has good linearity between the lighting frequency (described later) and the radiation intensity of ultraviolet rays, the ozone generator for preparing gas for calibration of the present invention uses the xenon flash lamp for lighting. Good linearity between frequency and ozone generation. In addition, the calibration gas preparation ozone generator of the present invention does not have the problem of temperature characteristics unlike the ozone generator using a low-pressure mercury lamp. Therefore, the ozone generator for preparing gas for calibration of the present invention can control the amount of ozone generated with high accuracy by adjusting the lighting frequency of the xenon flash lamp. Further, since the lighting frequency of the xenon flash lamp is a physical quantity suitable for digitally controlling by a computer, it is easy to automatically control the ozone generation amount using a computer.

Since the ozone analyzer and the nitrogen oxide analyzer of the present invention include the calibration gas preparation device using the calibration gas preparation ozone generator of the present invention having the above-mentioned advantages, calibration and gas The test can be performed in a short time, and the apparatus configuration can be simplified and the cost can be reduced. In addition, since the ozone concentration and the nitrogen oxide concentration in the calibration gas can be controlled with high accuracy, the calibration and gas test can be performed with high accuracy. Moreover, by automatically controlling the amount of ozone generated by the ozone generator for preparing gas for calibration using a computer, it is also possible to automatically perform calibration and gas tests.

Hereinafter, the present invention will be described in more detail. The xenon flash lamp used in the present invention is one in which electrodes are arranged in a lamp tube filled with xenon gas, and emits ultraviolet light by pulse lighting. Although the structure of the xenon flash lamp is not necessarily limited, for example, an electrode composed of a main electrode consisting of a cathode and an anode and several trigger probes in a bulb-shaped lamp tube filled with high-purity xenon gas of several hundred Torr. Can be used. This xenon flash lamp applies a predetermined voltage between the cathode and the anode, gives trigger energy to the trigger probe, and performs discharge.
Light containing pulsed light is emitted from a radiation window at the head of the lamp tube by performing pulse lighting.

In this case, it is appropriate to use a xenon flash lamp whose emission window is made of synthetic quartz glass or UV transmitting glass. That is, the emission spectrum of the xenon flash lamp is continuous from ultraviolet to visible and infrared, and the spectral intensity in the ultraviolet region is particularly high, but the emission spectrum distribution differs depending on the material of the emission window. On the other hand, in the calibration gas preparation ozone generator of the present invention, it is necessary to irradiate oxygen with ultraviolet rays (UV-C) having a main wavelength of 100 to 280 nm in order to generate ozone. In this regard, a xenon flash lamp using a radiation window made of synthetic quartz glass or UV-transmissive glass has a high UV-C radiation intensity, so that it can be suitably used for the calibration gas preparation ozone generator of the present invention. it can.

The calibration gas preparation ozone generator of the present invention irradiates ultraviolet rays from the xenon flash lamp to oxygen to generate ozone. In this case, as the oxygen, high-purity oxygen, purified air (zero gas) from which moisture and other components that hinder analysis are removed, and the like can be used. Means for irradiating the ultraviolet rays from the xenon flash lamp to oxygen include, for example, flowing oxygen through a quartz tube, and irradiating the quartz tube with ultraviolet rays from the xenon flash lamp, or providing xenon in an ultraviolet irradiation tank. A flash lamp may be installed, oxygen may be supplied into the ultraviolet irradiation tank, and a xenon flash lamp may be pulse-lit in the ultraviolet irradiation tank to irradiate the ultraviolet light with oxygen.

In the calibration gas preparation ozone generator of the present invention, the amount of ozone generated can be controlled by controlling the operating frequency of the xenon flash lamp to adjust the ozone concentration in the calibration gas. The lighting frequency is the number of times of pulse lighting performed by the xenon flash lamp in one second, and the ozone generation amount increases as the lighting frequency increases. Therefore, it is preferable to provide the xenon flash lamp lighting frequency control means in the calibration gas preparation ozone generator of the present invention. The lighting frequency control means can be constituted by, for example, a trigger power supply connected to the power supply of the xenon flash lamp and a function generator connected to the trigger power supply. Usually, the lighting frequency is adjusted in the range of 5 to 100 Hz.

The gas preparation apparatus for calibrating ozone of the present invention comprises:
The apparatus includes the above-described ozone generator for preparing a calibration gas of the present invention and an oxygen supply source. In this case, as the oxygen supply source, a high-purity oxygen-filled cylinder or a zero-gas preparation means for processing air to remove moisture and other components that hinder analysis and produce purified air (zero gas) may be used. it can. The ozone calibration gas preparation device of the present invention may be provided with a diluting device for mixing and diluting the generated ozone with zero gas as needed.

The apparatus for preparing a gas for calibrating nitrogen oxides of the present invention comprises the above-described gas-for-calibration gas preparation apparatus for ozone and a supply source of nitric oxide with a known concentration, and is prepared by the gas-for-calibration gas preparation apparatus for ozone. The ozone calibration gas is reacted with nitric oxide to produce nitrogen dioxide. That is, since the nitrogen oxide calibration gas preparation device of the present invention has a function of reacting the prepared ozone calibration gas with nitrogen monoxide to form nitrogen dioxide, the nitrogen oxide and nitrogen dioxide are mixed. Thus, a calibration gas for nitrogen oxide can be obtained.
In this case, a cylinder filled with a known concentration of nitric oxide is usually used as the nitric oxide supply source. Incidentally, the nitrogen oxide calibration gas preparation device of the present invention, if necessary,
A dilution device for mixing and diluting zero gas with the generated ozone may be provided.

The ozone analyzer of the present invention includes the above-described ozone calibration gas preparation device of the present invention,
The calibration of the indicated value is performed by introducing an ozone calibration gas prepared by the calibration gas preparation device into the measurement unit instead of the sample gas. In this case, the configuration of the ozone analyzer main body is not limited, and examples thereof include an ozone analyzer based on a chemiluminescence method and an ozone analyzer based on an ultraviolet absorption method.

The nitrogen oxide analyzer of the present invention includes the above-described nitrogen oxide calibration gas preparation device of the present invention,
The conversion efficiency of the converter is determined by introducing the nitrogen oxide calibration gas prepared by the calibration gas preparation device in place of the sample gas into a measurement unit having a converter that converts nitrogen dioxide to nitric oxide. Things. In this case, the configuration of the nitrogen oxide analyzer main body is not limited, and examples thereof include a nitrogen oxide analyzer based on a chemiluminescence method. In addition, the conversion efficiency of the converter is calculated by JI
The converter efficiency test method by the gas phase titration method described in the SB-7953 appendix can be used. In addition,
According to the nitrogen oxide analyzer of the present invention, since the concentration of nitrogen dioxide in the calibration gas of the generated nitrogen oxide is known,
Using that value, the amount of ozone generated from the ozone calibration gas preparation device can be accurately calculated.

[0023]

FIG. 1 is a flow chart showing an example of an ozone analyzer according to the present invention. In the figure, reference numeral 2 denotes a zero gas preparation means for processing the air 3 to produce a zero gas. The zero gas preparation means 2 is provided with a pump, a membrane dehumidifier, a purifier, and the like. In the figure, 4 is an ultraviolet irradiation tank into which the zero gas produced by the zero gas preparation means 2 is introduced, 6 is a xenon flash lamp installed in the ultraviolet irradiation tank 4,
Reference numeral 8 denotes a power supply of a xenon flash lamp, 10 denotes a lighting frequency control means including a trigger power supply and a function generator connected to the power supply 8, 12 denotes a reaction tube into which gas exiting the ultraviolet irradiation tank 4 enters, and 14 denotes a reaction tube. The main body of the ozone analyzer into which the discharged gas is introduced, and 15 denotes a gas discharge pipe for discharging extra gas.

As the xenon flash lamp 6, the one having the structure shown in FIG. 2 was used. In the xenon flash lamp 6 shown in FIG. 2, reference numeral 20 denotes a lamp tube made of synthetic quartz glass having a small bulb shape, and reference numeral 22 denotes a radiation window at the lamp tube head. The lamp tube 20 is filled with a high purity xenon gas of several hundred torr, and has a cathode 24 and an anode 2.
Six and five trigger probes 28 and sparkers 30 are arranged. In the figure, reference numeral 32 denotes a connector. The xenon flash lamp 6 of the present example applies a predetermined voltage between the cathode 24 and the anode 26 and gives a trigger energy to the trigger probe 28 to cause a discharge. The lighting produces an arc light emission 34,
Thus, light including ultraviolet rays is emitted from the emission window 22 in the head of the lamp tube 20.

As the ozone analyzer main body 14, for example, an ozone analyzer based on a chemiluminescence method described in JIS-B-7957 as shown in FIG. 8 and a JIS-B-7957 as shown in FIG. An ozone analyzer based on the described ultraviolet absorption method can be used.

In the apparatus of this embodiment, the ultraviolet irradiation tank 4, the xenon flash lamp 6, the power supply 8, the lighting frequency control means 1
0, a calibration gas preparation ozone generator is constituted by the reaction tube 12, and an ozone calibration gas preparation device is constituted by the calibration gas preparation ozone generator and the zero gas preparation means 2 (oxygen supply source). I have.

In the apparatus shown in FIG. 1, the air 3 is continuously treated by the zero gas preparation means 2 to produce a zero gas having a low moisture content and containing no ozone, hydrocarbon, NO _X , SO _{X and the} like. Is continuously flowed into the ultraviolet irradiation tank 4. In the ultraviolet irradiation tank 4, a xenon flash lamp 6
Performs pulse lighting at a predetermined lighting frequency under the control of the lighting frequency control means 10, and irradiates the zero gas with ultraviolet rays to generate ozone. The gas that has exited the ultraviolet irradiation tank 4 enters the reaction tube 12, where after the ozone generation reaction is completed, the gas is introduced into the ozone analyzer main body 14 as a calibration gas.

FIG. 3 is a flowchart showing an example of the nitrogen oxide analyzer according to the present invention. In the drawing, reference numeral 42 denotes a purified air filling cylinder, 44 denotes a flow meter, 46 denotes an ultraviolet irradiation tank into which purified air is introduced from the purified air filling cylinder 42, and 48 denotes a xenon flash lamp provided in the ultraviolet irradiation tank 46.
0 is the power supply of the xenon flash lamp, 52 is the power supply 50
Lighting frequency control means consisting of a trigger power supply and a function generator connected to the reaction tube; 54, a reaction tube into which gas exiting the ultraviolet irradiation tank 46 enters; 56, a nitric oxide standard gas filling cylinder;
Is a flow meter, 60 is a mixer for mixing the gas that has exited the reaction tube 54 with the nitrogen monoxide standard gas from the nitrogen monoxide standard gas filling cylinder 56, and 62 is the gas that has exited the mixer 60. A nitrogen oxide analyzer main body, 64 is a gas discharge pipe for discharging gas, and 66 is a flow meter.

In this apparatus, the xenon flash lamp 48 having the above-described structure shown in FIG. 2 was used. Further, as the nitrogen oxide analyzer main body 62, for example, JIS-B-7 as shown in FIGS.
953, a nitrogen oxide analyzer based on a chemiluminescence method can be used. 10A shows an analyzer of a flow path switching system, FIG. 10B shows an analyzer of an optical path switching system, and FIG.

In the apparatus of this embodiment, an ozone generator for preparing a calibration gas is constituted by an ultraviolet irradiation tank 46, a xenon flash lamp 48, a power supply 50, a lighting frequency control means 52, and a reaction tube 54. The ozone generator and the purified air filling cylinder 42 (oxygen supply source) constitute an ozone calibration gas preparation apparatus. The ozone calibration gas preparation apparatus and the nitric oxide standard gas filling cylinder 56 are provided.
(Nitrogen monoxide supply source) constitutes a nitrogen oxide calibration gas preparation device, and the nitrogen oxide calibration gas preparation device and the nitrogen oxide analyzer main body 62 constitute a nitrogen oxide analyzer. ing.

The converter efficiency test by the gas phase titration method of the apparatus shown in FIG. 3 is performed by the following procedure as described in JIS-B-7953. The following is a method of operating the analyzer of the flow path switching type, but analyzers of other types may be performed in accordance with this. (A) The operation of the ozone generator is stopped, and the nitrogen oxide analyzer main body 62 is set to the nitric oxide measurement side. (B) Nitrogen monoxide standard gas is supplied from the nitrogen monoxide standard gas filling cylinder 56 and purified air is supplied from the purified air filling cylinder 42, and the indication of the nitrogen oxide analyzer main body 62 is about 8 in the measurement stage.
Adjust the flow rate to show 0%. The indicated value of the nitrogen oxide analyzer main body 62 at this time is assumed to be A. (C) Activate the ozone generator and oxidize nitric oxide with the generated ozone. At this time, the nitrogen oxide analyzer main body 6
Adjust the ozone generator so that the indication of 2 indicates about 10% of the measurement phase. The indicated value of the nitrogen oxide analyzer main body 62 at this time is B. (D) The flow path of the nitrogen oxide analyzer main body 62 is switched to a nitrogen oxide measurement flow path (via a converter), and the indicated value of the nitrogen oxide analyzer main body 62 at this time is C. (E) Using the indicated values A, B and C, the converter efficiency is calculated by the following equation. Converter efficiency (%) = {(CB) / (AB)} ×
100

[0032]

EXAMPLE The following stabilization time test was carried out using the apparatus of FIG.
A linearity test, a repeatability test, and a temperature test were performed. In this case, as the xenon flash lamp 6, L2358 manufactured by Hamamatsu Photonics KK was used, and as the ozone analyzer 14, ML9810 manufactured by Monitor Lab was used. Also, for comparison,
A similar apparatus was prepared except that the xenon flash lamp 6 was replaced by a low-pressure mercury lamp and the lighting frequency control means 10 was replaced by a discharge current control means of the low-pressure mercury lamp, and tests other than the linearity test were performed in the same manner. In this case, a pen-type low-pressure mercury lamp (Penlay) was used as the low-pressure mercury lamp. In the temperature characteristic test described below, an ultraviolet irradiation tank 4, a xenon flash lamp 6, a power supply 8, a lighting frequency control means 10, a reaction tube 12
In a stabilization time test 2 and a temperature characteristic test described below, an ultraviolet irradiation tank 4 of a device using a pen-type low-pressure mercury lamp, a pen-type low-pressure mercury lamp, a power supply 8, a discharge current control means,
The reaction tube 12 was placed in a thermostat.

Stabilization time test 1 The ozone generator kept at room temperature was turned on (cold start), and the zero gas preparation means 2 to the ultraviolet irradiation tank 4
To generate an ozone-containing gas having an ozone concentration of about 0.9 ppm. The ozone-containing gas is introduced into the ozone analyzer 14, and the time until the indication of the ozone analyzer 14 is stabilized (stabilization time) is obtained. Examined. FIG. 4 shows the results.
In FIG. 4 and FIGS. 5 to 7 described later, an apparatus using a xenon flash lamp is indicated as xenon, and an apparatus using a pen-type low-pressure mercury lamp is indicated as penray.
In the case of an ozone generator using a xenon flash lamp, the stabilization time is 100% to 0.970 ppm (24
Min), both the 95% response and the 90% response could not be measured, and the response at 1 minute was 98.8%. In contrast,
In the case of an ozone generator using a pen-type low-pressure mercury lamp, 100
Assuming a% of 0.962 ppm (70 minutes), the 95% response was 9 minutes and the 90% response was 5.4 minutes.

According to this test, the ozone generator of the present invention
It was found that the amount of generated ozone was stabilized in a short time after turning on the xenon flash lamp. On the other hand, an ozone generator using a pen-type low-pressure mercury lamp, when the low-pressure mercury lamp is turned on from a state in which the ambient temperature of the low-pressure mercury lamp is not adjusted (cold start), until the ozone generation amount becomes stable. It took time.

Stabilization time test 2 In an apparatus using a xenon flash lamp, the same test as the above stabilization time test 1 was performed. In an apparatus using a pen-type low-pressure mercury lamp, a test similar to the stabilization time test 1 was performed with the temperature in the thermostat adjusted to 50 ° C. (hot start). FIG. 5 shows the results.

According to this test, the ozone generator using the pen-type low-pressure mercury lamp has an ozone generation amount even when the low-pressure mercury lamp is turned on (hot start) while the ambient temperature of the low-pressure mercury lamp is being adjusted. Was found to take some time to stabilize.

Linearity test The ozone generator kept at room temperature was turned on (cold start), and the zero gas preparation means 2 to the ultraviolet irradiation tank 4
Then, zero gas was flowed at a flow rate of about 3 L / min, the lighting frequency of the xenon flash lamp was changed by 5 Hz from 5 Hz to 45 Hz, and the ozone concentration reached equilibrium at each lighting frequency was examined by the ozone analyzer 14. Fig. 6 shows the results.
Shown in The linearity of an ozone generator using a xenon flash lamp has a correlation coefficient of 0.999978 and a slope of 0.0
19308, section -0.0242. From this test, it was found that the ozone generator of the present invention had excellent linearity between the operating frequency of the xenon flash lamp and the amount of generated ozone.

Repeatability test Ozone concentration of about 0.9 depending on ON / OFF of ozone generator
A ppm span gas and a zero gas were alternately prepared for about 10 minutes, and the final ozone concentration in each sequence was checked by the ozone analyzer 14. The results are shown in Tables 1 and 2. Table 1 shows the results of the apparatus using the xenon flash lamp, and Table 2 shows the results of the apparatus using the pen-type low-pressure mercury lamp. The deviation from the average in Tables 1 and 2 is the difference between the measured span gas value and the average value in each sequence. The ratio to the average is a ratio of the deviation of the measured span gas value in each sequence from the average of the measured span gas value.

According to this test, the ozone generator of the present invention
When the xenon flash lamp was turned off and then turned on again, it was found that the amount of generated ozone was stable in a short time after relighting, and the reproducibility was excellent. On the other hand, in the case of an ozone generator using a pen-type low-pressure mercury lamp, when the pen-type low-pressure mercury lamp is turned off and then turned on again, the amount of ozone generated after re-lighting may not be stable in a short period of time. Was inferior to the ozone generator of the present invention.

[0040]

[Table 1]

[Table 2]

Temperature characteristic test : The ozone generator kept at room temperature was turned on (cold start), and the zero gas preparation means 2 to the ultraviolet irradiation tank 4
A zero gas is flowed at a flow rate of about 3 L / min to generate an ozone-containing gas having an ozone concentration of about 0.9 ppm.
The temperature in the thermostat was changed from 0 ° C. to 40 ° C. at intervals of 5 ° C., and the ozone concentration which reached equilibrium at each temperature was examined by the ozone analyzer 14. FIG. 7 shows the results.

According to this test, the ozone generator of the present invention
It was found that the temperature characteristics were small and the temperature drift of the ozone generation amount was small. On the other hand, an ozone generator using a pen-type low-pressure mercury lamp has a large temperature characteristic and a large temperature drift in the amount of generated ozone.

[0043]

The ozone generator for preparing a calibration gas according to the present invention has the following effects. (A) The amount of generated ozone is stabilized in a short time after the xenon flash lamp is turned on, and the temperature drift of the generated amount of ozone is small. Therefore, the time required for calibration and gas test can be reduced. This effect is a great advantage especially when performing calibration or gas test in the field. (B) It is possible to eliminate the need for a temperature adjusting means for adjusting the ambient temperature of the xenon flash lamp. Therefore, the apparatus configuration can be simplified, and it is advantageous in terms of cost and safety. (C) By adjusting the lighting frequency of the xenon flash lamp, the amount of ozone generated can be controlled accurately. (D) The operating frequency of the xenon flash lamp does not require feedback and is a physical quantity suitable for being digitally controlled by a computer. Therefore, it is easy to automatically control the amount of ozone generated using a computer. is there. Therefore, the automatic operation of the calibration gas preparation ozone generator is facilitated, and the automatic calibration of the analyzer and the automatic gas test are also facilitated.

Further, the ozone analyzer and the nitrogen oxide analyzer of the present invention can perform calibration and gas test in a short time, can simplify the apparatus configuration and reduce the cost, and can perform calibration. The ozone concentration in the working gas can be controlled with high accuracy, and the calibration and gas test can be automatically performed.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of an ozone analyzer according to the present invention.

FIG. 2 shows an example of a xenon flash lamp, wherein (a) is a schematic front view and (b) is a schematic plan view.

FIG. 3 is a flowchart showing an example of a nitrogen oxide analyzer according to the present invention.

FIG. 4 is a graph showing stabilization times of an ozone generator using a xenon flash lamp and an ozone generator using a low-pressure mercury lamp.

FIG. 5 is a graph showing stabilization times of an ozone generator using a xenon flash lamp and an ozone generator using a low-pressure mercury lamp.

FIG. 6 is a graph showing the relationship between the operating frequency of a xenon flash lamp and the generated ozone concentration in an ozone generator using a xenon flash lamp.

FIG. 7 is a graph showing temperature characteristics of an ozone generator using a xenon flash lamp and an ozone generator using a low-pressure mercury lamp.

FIG. 8 is a flowchart showing an example of an ozone analyzer based on a chemiluminescence method.

FIG. 9 is a flowchart showing an example of an ozone analyzer based on an ultraviolet absorption method.

FIGS. 10A to 10C are flow charts each showing an example of a nitrogen oxide analyzer based on a chemiluminescence method.

FIG. 11 is a flowchart showing an example of a gas preparation device for calibration of an analyzer.

[Explanation of symbols]

 2 zero gas preparation means 4 ultraviolet irradiation tank 6 xenon flash lamp 8 power supply 10 lighting frequency control means 12 reaction tube 14 ozone analyzer 42 purified air filling cylinder 46 ultraviolet irradiation tank 48 xenon flash lamp 50 power supply 52 lighting frequency control means 54 reaction tube 56 Nitric oxide standard gas filling cylinder 60 Mixer 62 Nitrogen oxide analyzer main body

Claims (6)

[Claims] 1. An ozone generator for preparing a calibration gas, wherein ozone is generated by irradiating oxygen from a xenon flash lamp to oxygen. 2. The ozone generator for preparing a calibration gas according to claim 1, further comprising a lighting frequency control means for a xenon flash lamp. 3. An ozone calibration gas preparation device, comprising: the calibration gas preparation ozone generator according to claim 1; and an oxygen supply source. 4. An ozone calibration gas preparation device according to claim 3, and a nitrogen monoxide supply source with a known concentration, wherein the ozone calibration gas and the nitric oxide prepared by the calibration gas preparation device are provided. A gas preparation apparatus for calibration of nitrogen oxides, wherein 5. An ozone calibration apparatus comprising the ozone calibration gas preparation device according to claim 3, wherein the indicated value is calibrated using the ozone calibration gas prepared by the calibration gas preparation device. Analyzer. 6. A nitrogen oxide meter having a converter for converting nitrogen dioxide to nitric oxide, comprising the nitrogen oxide calibration gas preparation device according to claim 4, wherein the calibration gas preparation device is A nitrogen oxide analyzer for determining the conversion efficiency of a converter using a prepared nitrogen oxide calibration gas.