WO2022024407A1

WO2022024407A1 - Gas concentration detection device

Info

Publication number: WO2022024407A1
Application number: PCT/JP2020/041199
Authority: WO
Inventors: 修柴田; 武彦辻
Original assignee: 株式会社トラステック愛知
Priority date: 2020-07-28
Filing date: 2020-11-04
Publication date: 2022-02-03
Also published as: JP6886208B1; JP2022024437A

Abstract

[Problem] To provide a gas concentration detection device that is capable of appropriately detecting the concentration of a target gas in a measurement gas without frequently updating a calibration factor using a reference gas and a clean gas. [Solution] A gas concentration detection device 1 is provided with a calibration/attenuation filter 23F for reducing the light intensity 22OLI of outgoing light 22OL to be reached an outgoing light detection unit 24. A signal processing unit 25 obtains the concentration ch of a target gas GJ in a measurement gas GH on the basis of a calibration signal SC which is obtained when a gas container 22 is filled with a clean gas GA and the light intensity of the outgoing light is attenuated by the calibration/attenuation filter, a clean gas signal SA which is obtained when the gas container is filled with a clean gas and no attenuation is caused by the calibration/attenuation filter, a measurement gas signal SH which is obtained before or after the calibration signal SC and the clean gas signal SA and which is obtained when the gas container 22 is filled with the measurement gas GH and no attenuation is caused by the calibration/attenuation filter, and a calibration factor kf of the calibration/attenuation filter.

Description

Gas concentration detector

The present invention relates to a gas concentration detecting device that detects the concentration of a target gas such as chlorine dioxide contained in a gas to be measured.

Conventionally, when detecting the concentration of the target gas in the gas to be measured, for a gas having a light absorption wavelength range such as chlorine dioxide, when light in the emission wavelength range including this light absorption wavelength range is irradiated.
A gas concentration detecting device is known that utilizes the fact that the degree of decrease in the intensity of light transmitted through the gas changes according to the concentration of the target gas (see, for example, Patent Document 1).

Japanese Patent No. 5798230

In order to detect the concentration of the target gas in the gas to be measured with such a gas concentration detection device, the light after the standard gas obtained when the container is filled with the standard gas adjusted to the known concentration of the target gas. The relationship (calibration coefficient) between the intensity of the above and the intensity of the light after the transmission of the clean gas when the clean gas containing no target gas is filled is obtained in advance. After that, the relationship between the light intensity after the measured gas permeates obtained when the measured gas is filled, the light intensity after the clean gas permeated when the clean gas is filled, and the calibration coefficient are taken into consideration. Calculate the concentration of the target gas in the measurement gas. Once the calibration factor is obtained for the gas concentration detector, it is not necessary to update the calibration factor frequently thereafter.

However, when indoor or outdoor air is used as the gas to be measured or clean gas, the condition of the optical path may change over time, such as dirt adhering to the light incident window or exit window of the gas container or the like. In this case, an error occurs in the obtained concentration. In such a case, it is preferable to frequently update the calibration coefficient using a standard gas and a clean gas as described above. However, it is difficult to always prepare a standard gas, and when a standard gas is used, the device tends to be large, for example, a mechanism for introducing the standard gas into a gas container is required. It also takes time to obtain the calibration coefficient using the standard gas and the clean gas as described above.

The present invention has been made in view of such a defect, and is a gas concentration capable of appropriately detecting the concentration of the target gas in the measured gas without frequently updating the calibration coefficient using the standard gas and the clean gas. It provides a detection device.

(Section 1)
One aspect of the present invention for solving the above problems is a light source that emits light from a light source that includes at least a part of the light absorption wavelength range of the target gas within the emission wavelength range, and cleaning with the measured gas or not containing the target gas. A gas container filled with gas, the gas container having an incident window for incidenting the light source light into the gas container, and an exit window for emitting the emitted light after passing through the gas container, and the emission. Signal processing to acquire the concentration ch of the target gas in the measured gas by using the emitted light detection unit that receives the emitted light emitted from the window and outputs the light intensity signal S and the light intensity signal S. A gas concentration detecting device including a unit, a pre-incident light path in which the light source light travels from the light source to the incident window, and a post-exit light path in which the emitted light travels from the exit window to the emitted light detection unit. A calibration dimming filter that reduces the light intensity of the emitted light reaching the emitted light detection unit by arranging it in at least one of the optical paths is provided, and the signal processing unit is the light intensity signal S. Of these, the calibration signal SC obtained when the gas container is filled with the clean gas and the light intensity of the emitted light is reduced by the calibration dimming filter is obtained in tandem with the calibration signal SC. The clean gas signal SA obtained when the gas container is filled with the clean gas and the light intensity of the emitted light by the calibration dimming filter is not reduced, and the calibration signal SC and the clean gas signal. The measured gas signal SH obtained before and after the SA, when the gas container is filled with the measured gas and the light intensity of the emitted light by the calibration dimming filter is not reduced. From the calibration coefficient given to the calibration dimming filter corresponding to the degree of dimming that the calibration dimming filter reduces the light intensity of the emitted light, the concentration ch of the target gas in the measured gas is determined. It is a gas concentration detection device to acquire.

In the above-mentioned gas concentration detecting device, in addition to the clean gas signal SA and the measured gas signal SH, the calibration signal SC when the calibration dimming filter obtained before and after these is used, and the calibration dimming filter are given. Using the calibration coefficient obtained, the concentration channel of the target gas in the gas to be measured is detected.
As described above, the above-mentioned gas concentration detecting device detects the concentration channel by using the calibration dimming filter and the calibration signal SC without using the standard gas containing the target gas having a known concentration, so that it is easy to handle and is easy to handle. The structure of the entire device is also simple and contributes to miniaturization. Moreover, in addition to the clean gas signal SA and the measured gas signal SH, the calibration signal SC is also obtained one after the other, and the concentration channel is detected using these. Therefore, the concentration of the target gas in the gas to be measured can be detected with high accuracy.

Further, among the optical paths from the light source to the emitted light detection unit, the light intensity signal S is generated by arranging or not arranging the calibration dimming filter in at least one of the pre-incident optical path and the post-exit optical path outside the gas container. Since it is acquired, dirt is less likely to adhere to the calibration dimming filter as compared with the case where the calibration dimming filter is placed in the gas container. It is also easy to clean the calibration dimming filter.

The "calibration dimming filter" absorbs or reflects a part of the light source light traveling in the pre-incident optical path or the emitted light traveling in the post-emission optical path, and reduces the light intensity of the emitted light reaching the emitted light detection unit. It is a dimming filter, and the degree of dimming is known in advance. Specifically, a plate material (glass plate, etc.) made of a material (glass, resin, etc.) that absorbs an appropriate amount of light in a specific wavelength region, such as a quartz glass plate that partially absorbs ultraviolet light and transmits a part of it. Examples thereof include a resin plate) and a dimming filter in which an optical film that absorbs light in a specific wavelength region is provided on these plate materials (glass plate, etc.). In addition, when moving the "calibration dimming filter" in the optical path before the incident or in the optical path after the emission so as not to be arranged, the measurer moves the "calibration dimming filter", the "calibration dimming filter". The measurer operates and moves the moving device that holds and moves the "", and the filter movement control unit moves the calibration dimming filter.

Further, as the "calibration coefficient" given to the calibration dimming filter, a value corresponding to the degree of dimming in which the calibration dimming filter reduces the light intensity of the emitted light may be set. For example, there is an example in which the gas concentration cf of the target gas corresponding to the degree of dimming of the calibration dimming filter is used as the calibration gas concentration cf. In addition, the characteristics of the emitted light detection unit and each signal SA, SC, SH in the signal processing unit
The calibration coefficient can be determined according to the method of acquiring the concentration ch of the target gas in the gas to be measured using.

(Section 2)
Further, in the gas concentration detecting device, the emitted light detecting unit is an emitted light detecting unit that outputs a light intensity signal S proportional to the light intensity of the received emitted light, and is used in the calibration dimming filter. The given calibration coefficient is the calibration gas concentration cf of the target gas corresponding to the degree of dimming of the calibration dimming filter, and the signal processing unit is the calibration signal SC and the clean gas signal S.
A, a gas concentration detecting device that calculates the concentration ch of the target gas in the measured gas based on the following formula (1) using the measured gas signal SH and the calibration gas concentration cf. It is good to say.
ch = cf ・ (SA-SH) / (SA-SC) ・・・ (1)

In the above-mentioned gas concentration detection device, the calibration gas concentration cf is used as the calibration coefficient of the calibration dimming filter.
Therefore, using the calibration signal SC, the clean gas signal SA, the gas signal SH to be measured, and the calibration gas concentration cf, the concentration ch of the target gas in the gas to be measured is determined by the equation (1). It can be easily obtained.

The signal processing unit may perform calculation based on the equation (1). For example, from the calibration signal SC, the clean gas signal SA, and the measured gas signal SH, the measured gas dimming amount Gah = SA.
-SH and calibration filter dimming amount Gac = SA-SC are obtained. After that, the dimming ratio Phc =
Gah / Gac = (SA-SH) / (SA-SC) is obtained, and the concentration ch is multiplied by the calibration gas concentration cf.
There is a method to obtain. Instead of this, the calibration signal SC, the clean gas signal SA, and
From the measured gas signal SH, the measured gas dimming rate Rah = (SA-SH) / SA and the calibration filter dimming rate Rac = (SA-SC) / SA are obtained. After that, the dimming ratio Phc = Gah / Ga
Another method is to obtain c = (SA-SH) / (SA-SC) and multiply it by the calibration gas concentration cf to obtain the concentration ch. Further, from the calibration signal SC, the clean gas signal SA, and the measured gas signal SH,
Another method is to directly obtain the dimming ratio Phc = (SA-SH) / (SA-SC) and then multiply it by the calibration gas concentration cf to obtain the concentration ch.

(Section 3)
Further, in the above-mentioned gas concentration detecting device, the emitted light detecting unit is an analog emitted light detecting unit that outputs an analog light intensity signal S proportional to the light intensity of the received emitted light, and is the signal processing. The unit includes the calibration signal SC, which is an analog signal, the clean gas signal SA, and
The measured gas signal SH is subjected to analog arithmetic processing, and in the above equation (1), the measured gas dimming rate signal SRah corresponding to the measured gas dimming rate Rah = (SA-SH) / SA, and the measured gas dimming rate signal SRah, and Calibration filter dimming rate Rac = (SA-SC) / SA Corresponding calibration filter dimming rate signal SRac is output by the first analog calculation unit, the measured gas dimming rate signal SRah, and the calibration filter dimming rate. The first conversion processing unit that converts the signal SRac into the digital value of the measured gas dimming rate Rah and the calibration filter dimming rate Rac, the digital value of the calibration gas concentration cf, and the measured gas dimming rate Rah, respectively. It is preferable to use a gas concentration detecting device having a first concentration calculating unit for calculating the value of the concentration ch of the target gas in the measured gas of the above formula (1) from the above calibration filter dimming rate Rac. ..

In acquiring the density channel according to the equation (1), the light intensity signal S (calibration signal SC, clean gas signal SA, measured gas signal SH) which is an analog value such as a voltage value obtained from the emitted light detection unit.
) Can be converted to a digital value (AD conversion), and then subtraction, division, or the like can be performed by a CPU or the like.

However, when the concentration ch of the target gas in the measured gas is low (small) and the dimming of the emitted light by the target gas is very slight, the amount of dimming of the measured gas Gah = SA-SH or the measured gas is measured. The gas dimming rate Rah = (SA-SH) / SA becomes very small. Even in such a case, in order to obtain the density channel with sufficient accuracy, each light intensity signal S (calibration signal SC, clean gas signal SA, measured gas signal SH) is high with sufficient resolution by AD conversion. It is necessary to convert to a digital value of the bit, it is necessary to use an expensive AD conversion processing circuit (AD conversion processing IC), etc., and the difference between the clean gas signal SA and the measured gas signal SH is SA-SH (measured gas). Dimming amount Gah)
In order to obtain the extinction rate Rah of the gas to be measured, it is necessary to consider numerical processing such as reduction of the number of significant digits due to digit loss.

On the other hand, in the above-mentioned apparatus, in the first analog arithmetic unit, the calibration signal SC, the clean gas signal SA, and the measured gas signal SH, which are analog signals, are used, and the analog arithmetic processing is performed.
The analog measured gas dimming rate signal SRah and the calibration filter dimming rate signal SRac are acquired and output. After that, the first conversion processing unit converts the measured gas dimming rate signal SRah and the calibration filter dimming rate signal SRac into digital values of the measured gas dimming rate Rah and the calibration filter dimming rate Rac. Therefore, even when the concentration ch of the target gas in the measured gas is low (low), the measured gas dimming rate Rah and the calibration filter dimming rate Rac can be obtained with high accuracy. The concentration ch can be calculated with high accuracy.

(Section 4)
Alternatively, in the gas concentration detecting device according to the second item, the emitted light detecting unit is an analog emitted light detecting unit that outputs an analog light intensity signal S proportional to the light intensity of the received emitted light. The signal processing unit includes the calibration signal SC, which is an analog signal, and the clean gas signal S.
A and the measured gas signal SH are subjected to analog arithmetic processing, and in the above equation (1), the measured gas dimming amount signal SGah corresponding to the measured gas dimming amount Gah = SA-SH, and the calibration filter. The second analog calculation unit that outputs the dimming amount signal SGac corresponding to the dimming amount Gac = SA-SC, the measured gas dimming amount signal SGah, and the calibration filter dimming amount signal SGac are each digitally measured. The above formula (the above formula ( It is preferable to use a gas concentration detecting device having a second concentration calculating unit for calculating the value of the concentration ch of the target gas in the measured gas in 1).

In this device, the analog signal SC, the clean gas signal SA, and the measured gas signal SH are used in the second analog arithmetic unit, and the analog measured gas dimming amount signal SGah and the calibration filter are reduced by the analog arithmetic processing. The light amount signal SGac is acquired and output. Then, in the second conversion processing unit, the measured gas dimming amount signal SGah and the calibration filter dimming amount signal SGac are converted into digital values of the measured gas dimming amount Gah and the calibration filter dimming amount Gac. Therefore, even when the concentration ch of the target gas in the measured gas is low (low),
The measured gas dimming amount Gah and the calibration filter dimming amount Gac can be obtained with high accuracy, whereby the density ch can be calculated with high accuracy.

(Section 5)
Alternatively, in the gas concentration detecting device according to the second item, the emitted light detecting unit is an analog emitted light detecting unit that outputs an analog light intensity signal S proportional to the light intensity of the received emitted light. The signal processing unit includes the calibration signal SC, which is an analog signal, and the clean gas signal S.
A and the measured gas signal SH are subjected to analog arithmetic processing to obtain a dimming ratio signal SPhc corresponding to the dimming ratio Phc = (SA-SH) / (SA-SC) in the above equation (1). From the output third analog calculation unit, the third conversion processing unit that converts the dimming ratio signal SPhc into the dimming ratio Phc of the digital value, the calibration gas concentration cf of the digital value, and the dimming ratio Phc, the above equation ( It is preferable to use a gas concentration detecting device having a third concentration calculating unit for calculating the value of the concentration ch of the target gas in the measured gas in 1).

In this apparatus, in the third analog calculation unit, the calibration signal SC, the clean gas signal SA, and the measured gas signal SH, which are analog signals, are used, and the dimming ratio signal SPh is processed by analog calculation.
Acquires c and outputs it. After that, the third conversion processing unit converts the dimming ratio signal SPhc into a digital value dimming ratio Phc. Therefore, even when the concentration ch of the target gas in the gas to be measured is low (low), the dimming ratio Phc can be obtained with high accuracy, and thus the concentration ch can be calculated with high accuracy. can.

(Section 6)
Further, in the gas concentration detecting device according to any one of the above, a filter arrangement state in which the calibration dimming filter is moved to reduce the light intensity of the emitted light by the calibration dimming filter, and the calibration dimming It is preferable that the gas concentration detecting device further includes a filter movement control unit that realizes a filter non-arranged state that does not cause a decrease in the light intensity of the emitted light by the filter.

Since this device is provided with a filter movement control unit that realizes a filter arrangement state and a filter non-arrangement state, the calibration dimming filter is used when acquiring the calibration signal SC, the clean gas signal SA, and the measured gas signal SH. It can be easily moved.

The filter movement control unit may be provided with a filter movement mechanism for moving the calibration dimming filter and a mechanism control unit for controlling the filter movement control unit so that the filter placement state and the filter non-placement state can be realized. Examples of the filter moving mechanism include a filter moving mechanism that moves the calibration dimming filter forward and backward in a direction orthogonal to the pre-incident optical path or the post-exit optical path to realize a filter-arranged state and a filter-non-arranged state. Further, there is also a filter moving mechanism that realizes a filter arrangement state and a filter non-arrangement state by rotating the calibration dimming filter in the plane direction of the calibration dimming filter about a predetermined position outside the filter.

(Section 7)
Further, the gas concentration detecting device according to any one of the above is provided with a calibration coefficient storage unit that rewritably stores the calibration coefficient given to the calibration dimming filter, and the calibration coefficient is the gas. The standard gas signal SS obtained when the inside of the container is filled with a standard gas having a known standard concentration of the target gas and the light intensity of the emitted light is not reduced by the calibration dimming filter, and the above. Clean gas at the time of calibration obtained when the gas container is filled with the clean gas and the light intensity of the emitted light is not reduced by the calibration dimming filter, which is obtained before and after the standard gas signal SS. The signal ScA, the standard gas signal SS, and the clean gas signal ScA at the time of calibration are obtained in phase with each other, the inside of the gas container is filled with the clean gas, and the light intensity of the emitted light is increased by the calibration dimming filter. It is preferable to use a gas concentration detecting device which is a value calculated from the calibration signal ScC at the time of calibration obtained when the value is reduced.

In this apparatus, the calibration coefficient given to the calibration dimming filter is stored in advance in the calibration coefficient storage unit. The calibration coefficient is a value calculated from the standard gas signal SS, the clean gas signal ScA at the time of calibration, and the calibration signal ScC at the time of calibration. Therefore, using a gas concentration detector,
In detecting the concentration of the target gas in the gas to be measured, a calibration dimming filter can be used instead of the standard gas. In this case, the concentration of the target gas is detected by using the value of the calibration coefficient. be able to. On the other hand, it is possible to calibrate and update the value of the calibration coefficient given to the calibration dimming filter in a timely manner.

(Section 8)
Further, in the gas concentration detecting device according to any one of the above, the light source light intensity detecting unit for detecting the light intensity of the light source light emitted by the light source and the light of the light source light detected by the light source light intensity detecting unit. It is preferable to use a gas concentration detecting device further including a light source control unit that drives and controls the light source so that the intensity becomes constant.

Alternatively, a light source that emits light from a light source that includes at least a part of the light absorption wavelength range of the target gas within the emission wavelength range, and a gas container filled with the measured gas or a clean gas that does not contain the target gas. A gas container having an incident window that allows light to enter the gas container and an exit window that emits the emitted light after passing through the gas container, and the emitted light emitted from the emitted window is received and received. A gas concentration detecting device including an emitted light detecting unit that outputs an intensity signal S and a signal processing unit that acquires a concentration channel of the target gas in the measured gas by using the light intensity signal S. , A light source light intensity detecting unit that detects the light intensity of the light source light emitted by the light source, and
It is preferable to use a gas concentration detecting device further including a light source control unit for driving and controlling the light source so that the light intensity of the light source light detected by the light source light intensity detecting unit is constant.

In these devices, the light source light intensity detection unit and the light source control unit drive and control the light source so that the intensity of the light source light becomes constant. As a result, the light intensity of the light source light incident on the gas container can be stabilized, and the concentration channel of the target gas in the gas to be measured can be obtained with higher accuracy.

(Section 9)
Further, in the gas concentration detecting device according to Item 8, the light source light intensity detecting unit includes an optical fiber that guides a branched light source light that is a part of the light source light emitted by the light source, and the branch emitted from the optical fiber. It has a light source light detection unit that receives light from the light source and outputs a branch light intensity signal BS, and the light source control unit has a magnitude of the branch light intensity signal BS output from the light source light detection unit. It is preferable to use a gas concentration detecting device that drives and controls the light source so that the light is constant.

In this device, a part of the light source light is guided to the light source light detection unit by an optical fiber. Therefore, the branched light source light can be stably guided to the light source light detection unit regardless of the state of the space from the light source to the light source light detection unit. In addition, there are few restrictions on the arrangement of the light source and the light source light detection unit, and it is easy to do so.
A part of the light source light can be guided to the light source light detection unit away from the light source. Then, since the light source is driven and controlled so that the magnitude of the branch light source light intensity signal BS becomes constant in the light source control unit, the light intensity of the light source light emitted by the light source can be kept constant, and the light intensity can be kept constant with higher accuracy. The concentration ch of the target gas in the gas to be measured can be obtained.

(Section 10)
Further, in the gas concentration detecting device according to the ninth item, the emitted light detecting unit has an emitted light receiving element that receives the emitted light and converts it into an electric signal, and the light source light detecting unit has the above-mentioned light source light detecting unit. It has a light source light receiving element that receives the branched light source light and converts it into an electric signal with the same product number of the same manufacturer as the light emitting light receiving element, and the emitted light receiving element and the light source light receiving element are on the same electronic substrate. It is preferable to use a gas concentration detection device mounted close to each other.

In this device, the emitted light detecting unit and the light source light detecting unit have an emitted light receiving element and a light source light receiving element of the same part number of the same manufacturer, respectively. Therefore, the emitted light receiving element and the light source light receiving element have various characteristics such as environmental temperature characteristics and light receiving characteristics that are close to each other. Moreover, the emitted light receiving element and the light source light receiving element are mounted close to each other on the same electronic substrate. Therefore, the change in the ambient temperature around the emitted light receiving element and the change in the ambient temperature around the light source light receiving element are also approximated. Therefore, when the light receiving characteristics of the light source light receiving element change due to a change in the ambient temperature of the light source light receiving element, the same applies to the change in the ambient temperature around the emitted light receiving element and the accompanying change in the light receiving characteristics. Therefore, even if the ambient temperature around the light source light receiving element changes, it is possible to make it difficult for the light intensity signal S acquired by the emitted light receiving element to fluctuate.

(Section 11)
Further, the gas concentration detecting device according to any one of the above items, comprising a purification unit that generates a purified gas obtained by removing the target gas from the measured gas guided toward the gas container.
As the clean gas that fills the gas container, a gas concentration detecting device that uses the purified gas may be used.

Alternatively, a light source that emits light from a light source that includes at least a part of the light absorption wavelength range of the target gas within the emission wavelength range, and a gas container filled with a gas to be measured or a clean gas that does not contain the target gas. A gas container having an incident window that allows light to enter the gas container and an emission window that emits the emitted light after passing through the gas container, and the emitted light emitted from the emitting window is received and received. A gas concentration detection device including an emission light detection unit that outputs an intensity signal S, and a purification unit that generates a purification gas obtained by removing the target gas from the measured gas guided toward the gas container. As the clean gas that fills the gas container, a gas concentration detecting device that uses the purified gas may be used.

In the gas concentration detecting device that acquires the concentration ch of the target gas in the measured gas by using a clean gas that does not contain the target gas in addition to the measured gas, it is necessary to obtain this clean gas separately from the measured gas. There is. In obtaining this clean gas, for example, it is advisable to use the outside air as the clean gas. However, depending on the installation location of this gas concentration detection device, it may be necessary to form a pipe that connects to the outside air through the wall of the building where the device is installed, or to arrange it for a long time.
In addition to the large scale of the equipment, it became difficult to obtain clean gas, and the installation location was sometimes limited.

On the other hand, in the above two devices, the purification unit generates a purification gas obtained by removing the target gas from the gas to be measured, and uses this purification gas as the purification gas. For this reason, with this device, there is no need to consider whether or not to obtain clean gas such as outside air, or to install piping that connects to the outside air, etc., and it is compact, there are few restrictions on the installation location, and gas concentration detection is easy to install. It can be a device.

The purification unit that generates the purification gas from which the target gas is removed from the measurement gas differs depending on the measurement gas and the target gas, but for example, the purification unit provided with an adsorbent such as activated carbon or zeolite that adsorbs the target gas. Another example is a purification unit that irradiates the measured gas with light such as ultraviolet light and decomposes and removes the target gas with the irradiated light.

Further, in the gas concentration detecting device according to any one of the above, the target gas is chlorine dioxide, and the gas container introduces the measured gas or the clean gas into the gas container. It has a gas introduction port and a gas discharge port for discharging the gas to be measured or the clean gas that has been introduced from the inside of the gas container, and the cleanliness into the gas container through the gas introduction port. It is provided with a gas introduction / discharge unit for introducing gas or the gas to be measured and discharging the clean gas or the gas to be measured from the inside of the gas container through the gas discharge port, and the gas introduction / discharge unit is the clean It has a gas introduction / discharge control unit that controls the introduction of gas or the gas to be measured into the gas container and the discharge from the gas container, and the gas introduction / discharge control unit is at least the signal processing unit. During the period for acquiring the measured gas signal SH to obtain the measured gas signal SH, the measured gas already irradiated with the light source by the gas introduction / discharging unit is passed through the gas discharging port into the gas container. It is preferable to use a gas concentration detecting device that controls the continuous discharge of the gas to be measured, which has not been irradiated with the light source, into the gas container through the gas introduction port.

Alternatively, a light source that emits light from a light source that includes at least a part of the light absorption wavelength range of the target gas within the emission wavelength range, and a gas container filled with a gas to be measured or a clean gas that does not contain the target gas, and the light source. An incident window that allows light to enter the gas container, an exit window that emits emitted light after passing through the gas container, a gas inlet for introducing the measured gas or the clean gas into the gas container, and a gas inlet. , The gas container having the gas discharge port for discharging the measured gas or the clean gas already introduced from the gas container, and the light emitted from the exit window are received and the light intensity signal S is output. The clean gas into the gas container through the emission light detection unit, the signal processing unit for acquiring the concentration channel of the target gas in the gas to be measured using the light intensity signal S, and the gas introduction port. Alternatively, the gas concentration detecting device including the gas introduction / discharging unit for introducing the measured gas and discharging the clean gas or the measured gas from the inside of the gas container through the gas discharge port. The target gas is chlorine dioxide, and the gas introduction / discharge unit is a gas introduction / discharge control unit that controls the introduction of the clean gas or the measured gas into the gas container and the discharge from the gas container. The gas introduction / discharge control unit already irradiates the light source light by the gas introduction / discharge unit at least during the measurement gas signal acquisition period in which the signal processing unit obtains the measured gas signal SH. The gas to be measured is continuously discharged from the gas container through the gas discharge port, and the gas to be measured that has not been irradiated with the light source light is introduced into the gas container through the gas introduction port. It is preferable to use a gas concentration detection device that continuously controls.

Chlorine dioxide has a strong oxidizing power and is a gas, so it has a permeability that allows it to easily penetrate into a small space. Therefore, for the entire space where chlorine dioxide is introduced,
It can produce actions such as sterilization, sterilization, and virus inactivation. On the other hand, in order to properly maintain the concentration of chlorine dioxide in the space and to reduce the concentration of chlorine dioxide to a sufficiently low concentration by ventilation after treatment such as sterilization, the concentration in the air to be measured collected from the space is measured. A gas concentration detecting device capable of appropriately detecting the concentration of chlorine dioxide is desired.

However, when the light to be measured is irradiated with the light to be measured containing chlorine dioxide, the chlorine dioxide is decomposed into chlorine gas and oxygen gas, and the light in the light absorption wavelength range is absorbed. That is, the measured gas signal S
When the light source is irradiated to the gas to be measured that has already been introduced into the gas container in order to obtain H, chlorine dioxide contained in the gas to be measured is decomposed and its concentration gradually decreases. While obtaining the measured gas signal SH, the concentration of chlorine dioxide in the measured gas may change, and a stable measured gas signal SH may not be measured.

On the other hand, in these devices, at least during the period for acquiring the measured gas signal SH in which the signal processing unit obtains the measured gas signal SH, the gas introduction / discharge unit has already irradiated the light source and the concentration of chlorine dioxide. The measured gas whose chlorine dioxide concentration has decreased is continuously discharged from the gas container through the gas discharge port, and the measured gas whose chlorine dioxide concentration has not decreased without being irradiated with the light source is introduced into the gas container through the gas inlet. Control is performed to continue. Therefore, even if chlorine dioxide in the gas to be measured in the gas container is reduced by irradiation with the light source light, new chlorine dioxide can be supplemented by introducing the gas to be measured not irradiated with the light source light, so that a stable subject can be covered. It can contribute to the measurement of the measured gas signal SH.

(Section 13)
Further, in the gas concentration detecting device according to any one of the above, the target gas is chlorine dioxide, the measured gas is the measured air introduced from the measured space, and the clean gas is the clean gas. The gas container is an ultraviolet light source that emits ultraviolet light as the light source light, and the gas container is external light and the light source light except for the incident window and the exit window. The gas concentration detection unit, which is shielded from light from the outside light and the light from the light source, detects the gas concentration, which is shielded from the light from the outside light and the light from the light source. It is good to use it as a device.

As described above, when chlorine dioxide is irradiated with ultraviolet light, it absorbs ultraviolet light and decomposes, so that the intensity of the transmitted ultraviolet light decreases according to the concentration of chlorine dioxide, and therefore the measured gas signal SH decreases. On the other hand, in order to obtain the measured gas signal SH, for the tested gas guided into the measured gas introduction section or the gas container that guides the tested gas from the measured space toward the gas container. If the measured gas signal SH is irradiated with external light such as sunlight including ultraviolet light or light from a light source, chlorine dioxide in the test gas to be measured (target). gas)
There is a risk that the concentration of chlorine dioxide in the measured gas will not be able to be measured properly due to a decrease in the concentration of chlorine dioxide.

On the other hand, in this device, the gas container and the gas introduction part to be measured are shielded from external light and the light source emitted by the light source, so that the decrease in the concentration of chlorine dioxide in the gas to be measured before the test is suppressed. , The chlorine dioxide concentration in the gas to be measured can be appropriately measured.

It is explanatory drawing which shows the whole of the gas concentration detection apparatus which concerns on embodiment 1 to 3 and the modification. It is a block diagram which shows the processing content in a signal processing part among the gas concentration detection apparatus which concerns on embodiment. It is a block diagram which shows the processing content in a signal processing part among the gas concentration detection apparatus which concerns on modification 1. It is a block diagram which shows the processing content in a signal processing part among the gas concentration detection apparatus which concerns on modification 2.

(Embodiment)
Hereinafter, the gas concentration detecting device 1 according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the entire gas concentration detecting device 1. Further, FIG. 2 shows a processing procedure in the signal processing unit 25 for calculating the value of the concentration ch of the target gas GJ in the measured gas GH by analog calculation and digital calculation.

The gas concentration detecting device 1 of the present embodiment has the measured air (measured gas) GH in the measured space SPH shown by the broken line in FIG. 1 and the target gas GJ (chlorine dioxide in the present embodiment) in the clean area SPC. By alternately introducing clean air (clean gas) GA that does not contain the gas into the gas container 22 and irradiating the light source light 21L from the light source 21D, the target gas (chlorine dioxide) GJ in the air to be measured GH Obtaining the value of the density channel and displaying it on the display panel 43 or the interface unit 4
It is a device that transmits to the outside through 0.

Chlorine dioxide, which is the target gas GJ of the present embodiment, has a strong oxidizing power, and in addition to bleaching pulp and paper, inactivating (removing) viruses and sterilizing bacteria and fungi (mold). Used for. Chlorine dioxide (target gas) GJ has a maximum of around 360 nm and is approximately 270 to
It has a light absorption wavelength range GJB that absorbs light in the range of 500 nm. Therefore, when the air containing chlorine dioxide is irradiated with ultraviolet light having a wavelength of about 360 nm, chlorine dioxide absorbs the ultraviolet light and is decomposed. Therefore, when the air containing chlorine dioxide (measured air GH) is irradiated with ultraviolet light and the transmitted light is observed, the amount of chlorine dioxide absorbed, that is, the concentration of chlorine dioxide in the measured air GH is ch. The amount of ultraviolet light decreases in proportion to. Therefore, in the present embodiment, the concentration ch of chlorine dioxide is detected by detecting this decrease amount.

First, among the gas detection units 20 of the gas concentration detection device 1, the gas container 22 will be described, and then the gas introduction / discharge unit 10 that introduces and discharges the air to be measured GH or the like into the gas container 22 and the gas container 22. explain. The gas container 22 includes a cylindrical container body 22S made of a cylindrical member, specifically PTFE, and an incident window 22I attached so as to airtightly close one end surface (left end surface in FIG. 1) thereof. It has an exit window 22O attached so as to airtightly close the other end surface (the right end surface in FIG. 1). Both the incident window 22I and the emitted window 22O are made of a parallel flat quartz glass plate having less absorption attenuation of ultraviolet light than other optical glasses. The incident window 22I and the exit window 22O may be made of other materials depending on the emission wavelength range 21LB of the light source light 21L described later, and the incident window having a convex lens shape also serves as the lens 21Z described later. It is also possible to use a shape other than the parallel flat plate.

The container body 22S is provided with a gas introduction port 22SI and a gas discharge port 22SO. Of these, a common gas introduction pipe 11M, which will be described later, is connected to the gas introduction port 22SI. On the other hand, a gas discharge pipe 13W, which will be described later, is connected to the gas discharge port 22SO. Container body 22
A light-shielding tubular container light-shielding cover 22C shown by a broken line in FIG. 1 is arranged around S, and the container body 22S has an external light OL and a light source light except for the incident window 22I and the exit window 22O. It is shielded from 21L (stray light).

In the gas concentration detection device 1 of the present embodiment, the gas introduction unit 11 for guiding the measured air GH to the gas container 22 and the clean air GA are connected to the gas container 22 at the gas introduction port 22SI of the container body 22S.
The clean gas introduction unit 12 leading to the above is connected. The measured gas introduction unit 11 includes a three-way solenoid valve 11V, a measured gas introduction pipe 11T that guides the measured air GH in the measured space SPH shown by a broken line toward the three-way solenoid valve 11V, and a three-way solenoid valve 11V. It is composed of a common gas introduction pipe 11M connecting to the gas introduction port 22SI of the container main body 22S.

In the gas concentration detecting device 1 of the present embodiment, the measured gas introduction pipe 11T and the common gas introduction pipe 11M, which form the measured gas introduction unit 11 and through which the measured air GH flows, are shown by thick lines in FIG. As shown, a light-shielding tube is used to connect the three-way electromagnetic valve 11V and the gas inlet 22SI of the container body 22S. As a result, the external light OL is prevented from hitting the air to be measured GH flowing inside these. Further, as described above, the container main body 22S is shielded from the outside light OL and the light source light 21L (stray light) by the container light-shielding cover 22C except for the incident window 22I and the exit window 22O.

As described above, in the gas concentration detecting device 1 of the present embodiment, since the gas container 22 and the gas introduction unit 11 to be measured are shielded from the external light OL and the light source light 21L emitted by the light source 21D, the subject before the test is tested. The decrease in the concentration ch of chlorine dioxide (target gas GJ) in the measured air GH is suppressed.
Thus, the concentration ch of chlorine dioxide in the air to be measured GH can be appropriately measured.

On the other hand, the clean gas introduction unit 12 includes a three-way solenoid valve 11V, a clean gas introduction pipe 12T that guides the clean air GA in the clean area SPC shown by a broken line toward the three-way solenoid valve 11V, and the above-mentioned common gas introduction pipe 11M. It consists of. That is, in the present embodiment, the three-way solenoid valve 11V and the common gas introduction pipe 11M are shared by the measured gas introduction unit 11 and the clean gas introduction unit 12.

The three-way solenoid valve 11V is driven and controlled by a CPU 50 that operates as a gas introduction / exhaust control unit 15, and when the solenoid is not excited, the clean gas introduction pipe 12T and the common gas introduction pipe 1 are used.
The clean area SP is connected to 1M in the gas container 22 by the gas pump 13P described later.
Clean air GA in C is introduced. On the other hand, when the solenoid is excited, the gas introduction tube 11 to be measured
The T and the common gas introduction pipe 11M are connected, and the measured air GH in the measured space SPH is introduced into the gas container 22 by the gas pump 13P described later.

The measured space SPH determines the concentration ch of the target gas GJ (chlorine dioxide) in the measured air GH in the measured space SPH, for example, a space equipped with a generator for generating the target gas GJ (chlorine dioxide). This is the space you want to detect. Therefore, the measured space SPH is often a closed space, but there is no particular limitation, and an open space or an outdoor space can be a measured space SPH.

On the other hand, the clean area SPC is, for example, a space in which the target gas GJ (chlorine dioxide) does not substantially exist. For this reason, the clean area SPC is often a space with good ventilation to the outside or the outside air, but there is no particular limitation, and the clean air GA may be a clean air GA in which the target gas GJ (chlorine dioxide) does not substantially exist. The known space may be used as a clean area SPC.

On the other hand, in the gas discharge port 22SO of the container body 22S, the gas discharge unit 1 that discharges the gas (measured gas GH, clean gas GA) in the gas container 22 to the outside (for example, outdoors).
It is connected to 3. The gas discharge unit 13 includes a purifier 13C, a gas pump 13P, and a gas discharge unit 13.
Gas discharge port 22SO and purifier 13C of container body 22S, purifier 13C and gas pump 1
It consists of a gas discharge pipe 13W connecting to 3P. Of these, the purifier 13C is equipped with, for example, activated carbon that adsorbs chlorine dioxide, and is a device that removes the target gas GJ (chlorine dioxide) remaining in the exported gas GH to be measured, and is a target gas. Measured gas GH in which GJ is decomposed
And clean gas GA is discharged to the outside through the gas pump 13P.

In the gas introduction / discharge unit 10, when the gas pump 13P is operated with the three-way electromagnetic valve 11V de-excited, the gas in the container body 22S is discharged and the clean air GA in the clean area SPC is discharged into the gas container 22. Since the gas is introduced into the gas container 22, the gas container 22 is filled with clean air GA by operating the gas pump 13P for a predetermined time. On the other hand, the three-way solenoid valve 11
When the gas pump 13P is operated with V excited, the gas in the gas container 22 is discharged and the measured air GH in the measured space SPH is introduced into the gas container 22, so that the gas pump 13P is specified. By operating for the above time, the inside of the gas container 22 is filled with the air to be measured GH. Specifically, the CPU 50, which operates as the gas introduction / discharge control unit 15, controls the excitation and non-excitation of the three-way solenoid valve 11V in synchronization with the drive control of the gas pump 13P, thereby forming the inside of the gas container 22. Clean air GA and measured air GH can be introduced alternately.

Next, the light source unit 21 of the gas detection unit 20 will be described. The light source unit 21 has a light source 21D,
It has a light source shading body 21S and a lens 21Z that surround the light source 21D. Of these, the light source 21D
Is an LED, more specifically, an ultraviolet light emitting LED having a peak in the vicinity of a wavelength λ = 365 nm and having an emission wavelength range of 21 LB of about 350 to 400 nm. Therefore, this light source 21
The light source light 21L emitted by D is the light absorption wavelength range GJB (270) of chlorine dioxide (target gas) GJ.
~ 500 nm) is included. Therefore, when the light source light 21L emitted by the light source 21D is irradiated to the air containing chlorine dioxide (target gas) GJ (measured air GH), the contained chlorine dioxide absorbs the light source light 21L and is decomposed. Therefore, along with this, the air to be measured GH
The amount of transmitted light transmitted through the light is reduced. This phenomenon is used to detect the concentration ch of chlorine dioxide (target gas) GJ in the air to be measured GH. The light source 21D is a light source control unit 3 as described later.
Although it is driven by 5, it is preferable that the light source 21D is continuously lit during the period of density detection in consideration of drift and the like due to the temperature rise at the initial stage of lighting of the light source 21D (the initial stage of driving the light source 21D). ..

The periphery of the light source 21D is surrounded by the light source shading body 21S shown by a thick line in FIG. 1, and the light source light 21
It prevents L from leaking to the outside and becoming stray light. On the other hand, the light source light 21L radiated from the opening 21SO is incident on the gas container 22 through the incident window 22I of the gas container 22 while being converged by the lens 21Z. The light source light 21L incident on the gas container 22 is the gas container 22.
It proceeds as transmitted light 22TL transmitted through the air to be measured GH or clean air GA inside, and is emitted from the exit window 22O to the outside of the gas container 22. The emitted light 22OL emitted from the exit window 22O is incident on the emitted light receiving element 24P of the emitted light detection unit 24, which will be described later. This emitted light detection unit 24
Receives the emitted light 22OL and outputs a light intensity signal S corresponding to the light intensity of the emitted light 22OL.

The optical path from the light source 21D to the incident window 22I via the aperture 21SO and the lens 21Z is referred to as a pre-incident optical path LWI, and the optical path from the exit window 22O to the emitted light receiving element 24P is referred to as an exit optical path LWO.

In the present embodiment, the light source light 21L radiated from the opening 21SO is converged in a tapered conical shape by the lens 21Z arranged in the pre-incident optical path LWI, as shown by the broken line in FIG. The focal length of the lens 21Z and the like are adjusted so that the lens 21Z passes through the emission window 22O and is incident on the emission light receiving element 24P without being reflected by the inner peripheral surface 22NS. Unlike this embodiment, the transmitted light 22T is formed on the inner peripheral surface 22SN of the container body 22S of the gas container 22.
When L is made to advance while being reflected, the traveling distance of the transmitted light 22TL changes due to the fluctuation of the reflection accompanying the fluctuation of the optical axis, or the change of the dirty state adhering to the inner peripheral surface of the container body 22S. Under the influence, the light intensity 22OLI of the emitted light 22OL incident on the emitted light receiving element 24P fluctuates, which becomes a fluctuating factor of the light intensity signal S obtained by the emitted light detecting unit 24. On the other hand, as described above, such a variable factor can be removed.

However, although the lens 21Z is shown as a single convex lens in FIG. 1, a plurality of lenses may be combined. Further, instead of the lens 21Z, a collimated lens is used in the pre-incident light path LWI to change the light source light 21L to parallel light, to advance the transmitted light 22TL of the parallel light in the gas container 22, and to receive this parallel light as the emitted light. The light may be received by the element 24P. or,
The parallel light emitted from the emission window 22O may be converged by a convex lens arranged in the optical path LWO after emission and received by the emission light receiving element 24P. In either case, the above-mentioned merits can be obtained by preventing the transmitted light 22TL from being reflected on the inner peripheral surface of the container body 22S.

That is, the transmitted light 22TL incident on the gas container 22 from the incident window 22I is the gas container 22 (
It is preferable that the gas is transmitted through the gas container 22 without being reflected by the inner peripheral surface 22SN of the container body 22S) and is directly emitted from the exit window 22O.

By the way, as can be easily understood, the light intensity 21 of the light source light 21L emitted from the light source 21D
When the LI fluctuates with time, the light intensity 22OLI of the emitted light 22OL incident on the emitted light receiving element 24P fluctuates, which becomes a fluctuation factor of the light intensity signal S obtained by the emitted light detecting unit 24. Therefore, in the present embodiment, the light intensity 21LI of the light source light 21L emitted from the light source 21D is stabilized as follows.

That is, in the gas concentration detecting device 1 of the present embodiment, the light of the light source light intensity detecting unit 31 that detects the light intensity 21LI of the light source light 21L emitted by the light source 21D and the light of the light source light 21L detected by the light source light intensity detecting unit 31. Light source control unit 3 that drives and controls the light source 21D so that the intensity 21LI is constant.
It is equipped with 5. As a result, the light intensity 21 of the light source light 21L incident on the gas container 22
The LI can be stabilized, and the concentration c of the target gas GJ in the air to be measured GH can be measured with higher accuracy.
h can be obtained.

Specifically, the light source light intensity detecting unit 31 receives and branches the optical fiber 31LF for guiding the branched light source light 21BL which is a part of the light source light 21L emitted by the light source 21D and the branched light source light 21BL emitted from the optical fiber 31LF. Light source light detection unit 33 that outputs the light source light intensity signal BS
And have. That is, in the gas concentration detecting device 1 of the present embodiment, the optical fiber 31LF
One end 31LF1 (left end in FIG. 1) is inserted into the container light-shielding cover 22C, arranged near the light source 21D, receives a part of the light source light 21L, and branches the light source light 21BL.
Is guided into the optical fiber 31LF. Branch light source light 21B guided in the optical fiber 31LF
L is radiated from the other end 31LF2 (right end in FIG. 1) of the optical fiber 31LF and is incident on the light source light receiving element 33P of the light source light detecting unit 33. The light source light detection unit 33 outputs a branch light source light intensity signal BS corresponding to the light intensity of the branch light source light 21BL received by the light source light light receiving element 33P.

Then, in the light source control unit 35, the branch light source light intensity signal B output from the light source light detection unit 33
The light source 21D is driven and controlled (feedback control) so that the magnitude of S becomes constant. In the light source control unit 35, the light source 21 is set so that the size of the branch light intensity signal BS is constant.
In driving and controlling D, a reference voltage IC (not shown) that generates a reference voltage VB stabilized with high accuracy against changes in the ambient temperature and fluctuations in the power supply voltage is used, and the reference voltage VB is branched. A method of driving and controlling the light source 21D so that the difference or ratio with the magnitude of the light source light intensity signal BS is always constant can be mentioned.

In the gas concentration detection device 1 of the present embodiment, as described above, the optical fiber 31LF is transmitted from the branched light source light 21BL, which is a part of the light source light 21L, to the light source light detection unit 33 (light source light light receiving element 33P).
Is leading with. Therefore, regardless of the state of the space from the light source 21D to the light source light detection unit 33,
The branched light source light 21BL can be stably guided to the light source light detection unit 33. In addition, the light source 21
Whether D and the light source light detection unit 33 are arranged near or far from each other, there are few restrictions on these arrangements, and even the light source light detection unit 33 away from the light source 21D is the branched light source light 2.
1BL can be easily derived. Then, since the light source control unit 35 drives and controls the light source 21D so that the magnitude of the branch light source light intensity signal BS becomes constant, the light source light 2 emitted by the light source 21D
The light intensity of 1 L of 21 LI can be kept constant, and the concentration ch of the target gas GJ in the measured gas GH can be obtained with higher accuracy.

In particular, in the gas concentration detecting device 1 of the present embodiment, the emitted light detecting unit 24 has an emitted light receiving element 24P that receives the emitted light 22OL and converts it into an electric signal, and the light source light detecting unit 33 emits light. It has a light source light receiving element 33P having the same manufacturer and the same product number as the light receiving element 24P, and receiving a branch light source light 21BL and converting it into an electric signal. Examples of the emitted light receiving element 24P and the light source light receiving element 33P include a photodiode such as a PIN photodiode, and a CC.
Light receiving elements such as D, CMOS, and a photomultiplier tube can be exemplified. Moreover, as shown in FIG.
The emitted light receiving element 24P and the light source light receiving element 33P are mounted close to each other (specifically, within a distance of 5 cm) on the same electronic substrate 1PB (in FIG. 1, they are close to each other vertically). It is arranged.).

Therefore, the change in the ambient temperature around the emitted light receiving element 24P and the change in the ambient temperature around the light source light receiving element 33P are also approximated. Therefore, when the light receiving characteristics of the light source light receiving element 33P change due to a change in the ambient temperature of the light source light receiving element 33P or the like, the change in the ambient environmental temperature of the emitted light receiving element 24P and the light receiving characteristics associated therewith change. Since the change also occurs, even if the ambient temperature of the light source light receiving element 33P changes, the emitted light receiving element 24P
It is possible to prevent fluctuations in the light intensity signal S acquired in.

If the branched light source light 21BL is guided to the light source light receiving element 33P by the optical fiber 31LF as in the gas concentration detecting device 1 of the present embodiment, the degree of freedom in arranging the light source light receiving element 33P is increased, and the emitted light is emitted. The light receiving element 24P and the light source light receiving element 33P can be easily arranged in close proximity to each other.

Next, the calibration dimming filter 23F will be described. Gas concentration detection device 1 of this embodiment
Then, as will be described later, in detecting the concentration channel of chlorine dioxide (target gas) GJ in the air to be measured GH, the calibration signal SC is acquired by using the calibration dimming filter 23F. In the present embodiment, the calibration dimming filter 23F is made of a parallel plate-shaped quartz glass plate. Although it depends on the thickness of the quartz glass plate, only light is passed through the quartz glass plate, and the light intensity is attenuated by several% to 10% in the ultraviolet light region. Therefore, as shown by the broken line in FIG. 1, the calibration dimming filter 23F reaches the emitted light detection unit 24 (emitted light receiving element 24P) by arranging the calibrated dimming filter 23F in the emitted after-light path LWO in which the emitted light 22OL travels. The light intensity 22OLI of the emitted light 22OL can be reduced at a predetermined rate (for example, 10%).

A holder (not shown) that holds the calibration dimming filter 23F in a detachable position is provided, and the measurer attaches the calibration dimming filter 23F to the holder.
The calibration dimming filter 23F is placed in the pre-incident optical path LWI or the post-exit optical path LWO, and the measurer removes the calibration dimming filter 23F from the holder, whereby the calibration dimming filter 23F becomes the pre-incident optical path. It can be in a state where it is not arranged in the LWI or in the optical path LWO after emission. Further, a moving holder (not shown) for holding the calibration dimming filter 23F in a movable manner is provided, and the measurer operates the moving holder to allow the calibration dimming filter 23F to move in the pre-incident optical path LWI or in the post-exit optical path LWO. You may switch between the state where it is placed inside and the state where it is not placed. Further, the filter movement control unit 23 as described below can be provided.

Next, the filter movement control unit 23 that moves the calibration dimming filter 23F will be described. In the gas concentration detection device 1 of the present embodiment, the filter movement control unit 23 includes a calibration dimming filter 23F, a filter movement mechanism 23M for moving the filter movement control unit 23, and the filter movement mechanism 23.
It includes a mechanism control unit 23C that controls the operation of M. Of these, the filter moving mechanism 23M is the emitted light receiving element 24P by the calibration dimming filter 23F, as shown by the broken line in FIG.
The filter arrangement state FD that reduces the light intensity 22OLI of the emitted light 22OL reaching the light beam, and the calibration dimming filter 23F as shown by the solid line in FIG. 1 are retracted from the optical path LWO after being emitted.
The two states of the filter non-arranged state FN that do not cause a decrease in the light intensity 22OLI of the emitted light 22OL by the calibration dimming filter 23F are realized. Specifically, the filter moving mechanism 23M
Then, as shown by the double-headed arrow in FIG. 1, the calibration dimming filter 23F is moved forward and backward in the direction orthogonal to the optical path LWO (vertical direction in FIG. 1) after emission, and the filter arrangement state FD and the filter non-arrangement state F are performed.
Realize N.

On the other hand, the mechanism control unit 23C controls the operation of the filter moving mechanism 23M. In particular,
When the calibration signal SC is obtained in a state where the gas container 22 is filled with the clean gas GA, the filter moving mechanism 23M is operated prior to the acquisition of the calibration signal SC to operate the calibration dimming filter 2
The 3rd floor is moved to the filter arrangement state FD, and the emitted light 22 is set by this calibration dimming filter 23F.
The light intensity 22 OLI of OL is reduced. Further, when the clean gas signal SA is obtained in a state where the gas container 22 is filled with the clean gas GA, the filter moving mechanism 23M is operated to operate the calibration dimming filter 23F prior to the acquisition of the clean gas signal SA. After the light is emitted, it is retracted from the optical path LWO to be in the filter non-arranged state FN, and the light intensity 22OLI of the emitted light 22OL is not reduced by the calibration dimming filter 23F. Further, even when the measured gas signal SH is obtained in a state where the gas container 22 is filled with the measured gas GH, the filter moving mechanism 23M is operated to perform calibration dimming prior to the acquisition of the measured gas signal SH. The filter 23F is retracted from the optical path LWO after emission to obtain a filter non-arranged state FN, and the calibration dimming filter 23F does not reduce the light intensity 22OLI of the emitted light 22OL.

Next, the operation of each part in acquiring the concentration ch of the target gas GJ (chlorine dioxide) in the air to be measured GH and the processing of each signal SC, SA, SH in the signal processing part 25 will be described.
In acquiring the concentration ch, first, the gas container 22 is filled with the clean gas GA. Specifically, in the gas introduction / discharge control unit 15, the gas pump 13P is operated in a state where the three-way electromagnetic valve 11V is not excited and the common gas introduction pipe 11M is communicated with the cleaning region SPC via the cleaning gas introduction pipe 12T. , The gas in the container body 22S is discharged to the outside, and the gas container 2
Introduce clean air GA into 2.

After that, the gas introduction / emission control unit 15 will be used in the signal processing unit 25 for each signal SC, S.
A and SH are acquired in this order, and the gas pump 13P is continuously operated until the gas container 22 is filled with the clean air GA instead of the measured air GH. As a result, when the signal processing unit 25 obtains the calibration signal SC and the clean gas signal SA, the gas container 22 is used.
As the clean air GA continues to be discharged from the inside, new clean air GA continues to be introduced into the gas container 22. Further, in obtaining the measured gas signal SH in the signal processing unit 25,
The air to be measured GH irradiated with the light source light 21L continues to be discharged from the gas container 22, and at the same time.
A new air GH to be measured (not irradiated with the light source light 21L) continues to be introduced into the gas container 22.

Further, the filter moving mechanism 23M is operated to move the calibration dimming filter 23F to set the filter arrangement state FD. In this state, the light intensity 22O with the calibration dimming filter 23F.
The emitted light 22OL with reduced LI is received by the emitted light receiving element 24P, and is output from the emitted light detection unit 24 as a calibration signal SC to the signal processing unit 25 (first analog calculation unit 26).
The emitted light detection unit 24 is an analog emitted light detecting unit that outputs a light intensity signal S (each signal SC, SA, SH) which is an analog voltage signal proportional to the light intensity 22OLI of the received emitted light 22OL.

Subsequently, the filter moving mechanism 23M is operated to emit the calibration dimming filter 23F, and then the optical path L.
It is evacuated from WO and is set to the filter non-arranged state FN. In this state, the light intensity 22OLI of the emitted light 22OL is not reduced by the calibration dimming filter 23F. The emitted light 22OL is received by the emitted light receiving element 24P, and is used as a clean gas signal SA from the emitted light detection unit 24 by the signal processing unit 2.
Output to 5 (first analog arithmetic unit 26).

Subsequently, the gas container 22 is filled with the air to be measured GH. Specifically, in the gas introduction / discharge control unit 15, the gas pump 13P is operated in a state where the three-way electromagnetic valve 11V is excited and the common gas introduction pipe 11M is communicated to the measured space SPH via the gas introduction pipe 11T to be measured. It is operated to discharge the clean gas GA in the container body 22S to the outside, and the air to be measured GH is introduced into the gas container 22. The filter moving mechanism 23M is not operated. Therefore, the calibration dimming filter 23F remains in the filter non-arranged state FN. In this state, the light intensity 22OLI of the emitted light 22OL is not reduced by the calibration dimming filter 23F. This emitted light 2
2OL is received by the emitted light receiving element 24P, and is output from the emitted light detection unit 24 as a measured gas signal SH to the signal processing unit 25 (first analog calculation unit 26).

As described above, since the gas pump 13P is continuously operated in obtaining the gas signal SH to be measured in the signal processing unit 25, the air GH to be measured irradiated with the light source light 21L continues to be discharged from the inside of the gas container 22. , A new air GH to be measured (not irradiated with the light source light 21L) continues to be introduced into the gas container 22. Therefore, even if the chlorine dioxide (target gas) GJ in the measured air GH in the gas container 22 is reduced by the irradiation of the light source light 21L, the introduction of a new measured air GH not irradiated with the light source light is new. Since it can supplement chlorine dioxide GJ,
It can contribute to the stable measurement of the measured gas signal SH.

After that, as will be described later, in the signal processing unit 25, each signal SC, SA, SH,
And, using the calibration coefficient kf (cf) given to the calibration dimming filter 23F, the target gas G
The concentration ch of J (chlorine dioxide) is calculated and acquired.

As described above, in the gas concentration detecting device 1 of the present embodiment, when acquiring the concentration ch at one time,
Each signal SC, SA, SH is continuously acquired by the gas introduction / discharge unit 10. The acquisition of each signal SC, SA, and SH may be performed one after the other, and the order may be appropriately changed and applied. However, it is preferable to acquire each signal SC, SA, SH at a timing as close as possible to each other, for example, acquisition of each signal SC, SA, SH is completed within 30 seconds in total.
This is to suppress differences between the signals SC, SA, and SH due to temperature fluctuations, noise state fluctuations, environmental fluctuations, etc. of each part.

The air to be measured GH is introduced into the gas container 22, and the gas signal SH to be measured is detected by the emitted light detection unit 24.
After acquiring, the three-way solenoid valve 11V is switched. As mentioned above, the gas pump 13
Since P is continuously operated, the measured air GH is discharged from the gas container 22, and the clean air GA is introduced into the gas container 22, the common gas introduction pipe 11M, and the gas discharge pipe 13W. After that, clean air GA in the gas container 22, the common gas introduction pipe 11M, and the gas discharge pipe 13W.
Is circulated, and after the clean air GA is circulated, the gas pump 13P is stopped.
The target gas GJ (chlorine dioxide) contained in the air to be measured GH has a high oxidizing power and decomposes to generate chlorine gas, so that corrosion of each part can be prevented. Therefore, this device 1
The target gas G for the measured air GH in the measured space SPH is repeated intermittently.
When detecting the concentration ch of J (chlorine dioxide), the clean air GA was filled in the gas container 22, the common gas introduction pipe 11M, and the gas discharge pipe 13W during the waiting period until the next concentration detection. It is good to wait in the state. In addition, the order of signal SH, SA, SC, or signal SH
By acquiring each signal in the order of, SC, and SA, the gas container 22 can be filled with clean air GA after the concentration channel is detected. If the gas container 22 is kept on standby as it is, the gas container 22 can be filled.
It is possible to stand by with clean air GA introduced inside.

In the signal processing unit 25 of the gas concentration detection device 1 of the present embodiment, the signals SC, SA, SH obtained from the emitted light detection unit 24 as described above, and the calibration coefficient kf given to the calibration dimming filter 23F. The concentration ch of the target gas GJ in the air to be measured GH using the calibration gas concentration cf.
Is calculated based on the following equation (1).
ch = cf ・ (SA-SH) / (SA-SC) ・・・ (1)
The calibration coefficient kf is the light intensity 22OLI of the emission light 22OL of the calibration dimming filter 23F.
It is a value given to the calibration dimming filter 23F corresponding to the degree of dimming that reduces.
The calibration gas concentration cf is a kind of calibration coefficient kf, and is the concentration of the target gas GJ (chlorine dioxide) corresponding to the degree of dimming of the calibration dimming filter 23F.

Thus, in the gas concentration detecting device 1 of the present embodiment, the concentration ch of the target gas in the measured gas can be easily obtained by the equation (1) using each signal SC, SA, SH and the calibration gas concentration cf. be able to.
In acquiring the density channel according to the equation (1), each analog voltage signal (calibration signal SC, clean gas signal SA, measured gas signal SH) obtained from the emitted light detection unit 24 is converted into a digital value ( It is also possible to calculate the concentration channel of the target gas GJ by performing AD conversion) and then performing subtraction or division by digital calculation in a CPU or the like.

However, when the concentration ch of the target gas GJ in the air to be measured GH is low (for example, when the concentration ch of chlorine dioxide is 1 ppm or less, or 0.1 ppm or less), the target gas G
Since the extinction of the emitted light 22OL due to the absorption of J is very small, the difference between the values of the clean gas signal SA and the measured gas signal SH becomes very small, and the measured gas dimming amount Gah = S in the equation (1).
A-SH and the extinction rate of the measured gas obtained by dividing this by the clean gas signal SA Rah = (SA-SH) /
Since SA is a very small value, it is not preferable to perform arithmetic processing with a digital value.

Therefore, in the gas concentration detecting device 1, the signal processing unit 25 shown in FIG. 2 obtains the concentration channel of the target gas. That is, first, in the first analog calculation unit 26, each signal SC, SA, SH which is an analog voltage signal input from the emission light detection unit 24 is subjected to analog calculation processing, and the measured gas dimming rate Rah = (SA-). Measured gas dimming rate signal SRah corresponding to SH) / SA and calibration filter dimming rate signal SRa corresponding to calibration filter dimming rate Rac = (SA-SC) / SA
c is obtained and output to the first conversion processing unit 27.

In this embodiment, as described above, each signal SC, SA, which is an analog voltage signal,
SH is obtained intermittently in this order, for example, at intervals of several seconds to ten and several seconds. Therefore, once the calibration signal SC is obtained, the magnitude (analog voltage) of the calibration signal SC is temporarily held in the sample hold circuit, and when the clean gas signal SA is obtained, the calibration filter dimming rate Rac = (SA-SC) / Analog calibration filter corresponding to SA Dimming rate signal SRac
Is calculated using an analog divider. Further, the magnitude (analog voltage) of the clean gas signal SA is also temporarily held by the sample hold circuit. After that, when the measured gas signal SH is obtained, the measured gas dimming rate signal SRah, which is an analog voltage signal corresponding to the measured gas dimming rate Rah = (SA-SH) / SA, is converted into an analog divider. An example is an example of a method obtained by calculating using.

Next, the first conversion processing unit 27 AD-converts the measured gas dimming rate signal SRah and the calibration filter dimming rate signal SRac into digital values of the measured gas dimming rate Rah and the calibration filter dimming rate Rac, respectively. , Is input to the CPU 50. After that, in the CPU 50 functioning as the first density calculation unit 28, the calibration gas concentration cf (calibration coefficient kf) of the digital value stored in the calibration coefficient storage unit 29 described later, the measured gas dimming rate Rah, and the calibration filter Dimming rate Rac
From, the value of the concentration ch of the equation (1) is calculated.

In the gas concentration detection device 1 of the present embodiment, as described above, in the first analog calculation unit 26, the measured gas dimming rate signal SRah of the analog voltage signal including the subtraction of SA-SH is performed by the analog calculation processing. The calibration filter dimming rate signal SRac is obtained, and then the digital values of the measured gas dimming rate Rah and the calibration filter dimming rate Rac are obtained. Therefore, the air to be measured GH
Even when the concentration ch of the target gas GJ in the medium is low (low), unlike the case of digital value processing where there is a risk of digit loss, etc., the measured gas dimming rate Rah and calibration filter reduction are performed with high accuracy. The light rate Rac can be obtained, and the density ch can be calculated with high accuracy.

In the gas concentration detection device 1 of the present embodiment, the value of the concentration ch obtained by the first concentration calculation unit 28 is transmitted to the outside through the interface unit 40 of the CPU 50. In addition, the display control unit 42
It is also possible to have a display panel forming a liquid crystal screen or the like show the value of the concentration ch of chlorine dioxide GJ in the air to be measured GH.

Next, the calibration coefficient kf, the calibration gas concentration cf, and the acquisition method of these values will be described. The calibration coefficient kf is a value given to the calibration dimming filter 23F corresponding to the degree of dimming in which the calibration dimming filter 23F reduces the light intensity 22OLI of the emitted light 22OL, and the equation (1).
In this embodiment for calculating the concentration ch of the target gas GJ in the air to be measured GH using the above, the calibration gas concentration cf appearing in this equation (1) corresponds to. This calibration gas concentration cf is a case where the gas concentration detection device 1 uses a standard gas GS having a known standard concentration cs instead of the air to be measured GH, fills the gas container 22 with the standard gas GS, and irradiates the light source light 21L. In addition, based on the degree of dimming that reduces the light intensity 22OLI of the emitted light 22OL, the degree of dimming that the calibration dimming filter 23F reduces the light intensity 22OLI of the emitted light 22OL is the value of the gas concentration of the corresponding target gas GJ. It is shown by cf. That is, the calibration gas concentration cf is the calibration dimming filter 23F.
The value of the concentration c of the target gas GJ that causes dimming of the same magnitude as that caused by using is shown.

In the gas concentration detecting device 1 of the present embodiment, the calibration coefficient kf (calibration gas concentration cf) is set to the CPU.
It is rewritably stored in the calibration coefficient storage unit 29 of 50. The calibration coefficient kf (calibration gas concentration cf) is a value calculated from the standard gas signal SS, the clean gas signal ScA at the time of calibration, and the calibration signal ScC at the time of calibration.
Here, the standard gas signal SS fills the inside of the gas container 22 with the standard gas GS whose target gas GJ concentration c is a known standard concentration cs in the gas concentration detecting device 1, and is output by the calibration dimming filter 23F. It is an analog voltage signal obtained from the emitted light detection unit 24 when the light intensity 22OLI of the emitted light 22OL is not reduced.
Further, the clean gas signal ScA at the time of calibration fills the inside of the gas container 22 with the clean air GA in the gas concentration detection device 1 in phase with the standard gas signal SS, and the calibration dimming filter 23F.
When the light intensity 22OLI of the emitted light 22OL is not reduced due to the above, the emitted light detection unit 2
It is an analog voltage signal obtained from 4.
Further, the calibration signal ScC fills the inside of the gas container 22 with the clean air GA in the gas concentration detection device 1 in tandem with the standard gas signal SS and the clean gas signal ScA at the time of calibration, and the calibration dimming filter. When the light intensity 22OLI of the emitted light 22OL is reduced on the 23rd floor,
It is an analog voltage signal obtained from the emitted light detection unit 24.
Then, the value of the calibration gas concentration cf can be obtained by using the following formula (2). That is,
The value of the calibration gas concentration cf given to the calibration dimming filter 23F can be calibrated in a timely manner using the standard gas GS, and the newly obtained value of the calibration gas concentration cf is stored in the calibration coefficient storage unit 29.
cf = cs · (ScA-ScC) / (ScA-SS) ... (2)

Thus, when the gas concentration detecting device 1 is used to detect the concentration ch of the target gas GJ in the air to be measured GH, instead of using the standard gas GS in which the concentration c of the target gas GJ is a known standard concentration cs. , Calibration dimming filter 23F can be used, in this case
The concentration ch of the target gas GJ can be detected by using the value of the calibration gas concentration cf. Moreover, the value of the calibration coefficient kf (calibration gas concentration cf) given to the calibration dimming filter 23F can be calibrated and updated in a timely manner.

(Deformation form 1)
In the gas concentration detection device 1 of the above-described embodiment, among the signal processing units 25, the first analog calculation unit 26 performs analog calculation processing on each signal SC, SA, SH which is an analog voltage signal, and receives an analog signal. The measurement gas dimming rate signal SRah and the calibration filter dimming rate signal SRac are obtained. Then, in the first conversion processing unit 27, these signals SRah and SRac were AD-converted to obtain digital values of the measured gas dimming rate Rah and the calibration filter dimming rate Rac.

On the other hand, in the gas concentration detecting device 101 of the modified form 1, the signal processing unit 125 (see FIG. 3) performs arithmetic processing different from that of the embodiment to obtain the concentration channel of the target gas. That is,
First, the second analog calculation unit 126 performs analog calculation processing on each signal SC, SA, SH which is an analog voltage signal input from the emission light detection unit 24, and the measured gas dimming amount Gah = SA-.
Measured gas dimming amount signal SGah corresponding to SH and calibration filter dimming amount Gac = SA
-A calibration filter dimming amount signal SGac corresponding to SC is obtained and output to the second conversion processing unit 127.

Even in the present modified mode 1, as described above, the signals SC and SA, which are analog voltage signals, are used.
, SH are obtained intermittently in this order, for example, at intervals of several seconds to ten and several seconds. Therefore, once the calibration signal SC is obtained, the magnitude (analog voltage) of the calibration signal SC is temporarily held in the sample hold circuit, and when the clean gas signal SA is obtained, the calibration filter dimming amount Gac = SA. -An analog calibration filter corresponding to SC The dimming amount signal SGac is calculated by using an analog subtractor. Also, the magnitude of the clean gas signal SA (analog voltage)
Is also temporarily held by the sample hold circuit. After that, when the measured gas signal SH is obtained, there is a method of calculating the analog measured gas dimming amount signal SGah corresponding to the measured gas dimming amount Gah = SA-SH using an analog subtractor. It can be exemplified.

Next, in the second conversion processing unit 127, the measured gas dimming amount signal SGah and the calibration filter dimming amount signal SGac are AD-converted into digital values of the measured gas dimming amount Gah and the calibration filter dimming amount Gac, respectively, and input to the CPU 50. do. After that, in the CPU 50 functioning as the second concentration calculation unit 128, the calibration gas concentration cf (calibration coefficient kf) of the digital value stored in the calibration coefficient storage unit 29, the measured gas dimming amount Gah, and the calibration filter dimming amount Gac. From, the value of the concentration ch of the equation (1) is calculated.

Even in the gas concentration detection device 101 of the present modification 1, as described above, the second analog calculation unit 12
In 6, the measured gas dimming amount signal SGa including the subtraction of SA-SH by analog arithmetic processing.
h and the calibration filter dimming amount signal SGac are obtained, and then the digital values of the measured gas dimming amount Gah and the calibration filter dimming amount Gac are obtained. Therefore, even when the concentration ch of the target gas GJ in the measured air GH is low (low), the measured gas is reduced with high accuracy, unlike the case of digital value processing in which a digit loss may occur. Light rate Rah and calibration filter dimming rate R
Ac can be obtained, whereby the concentration ch can be calculated with high accuracy.

(Deformation form 2)
Further, in the gas concentration detecting device 201 of the modified form 2, the signal processing unit 225 (see FIG. 3) performs arithmetic processing different from that of the embodiment and the modified form 1 to obtain the concentration channel of the target gas. That is, first, in the third analog calculation unit 226, each signal SC, SA, SH which is an analog voltage signal input from the emission light detection unit 24 is subjected to analog calculation processing, and the dimming ratio Phc = (SA).
Obtaining the dimming ratio signal SPhc, which is an analog voltage signal corresponding to -SH) / (SA-SC),
It is output to the second conversion processing unit 127.

In addition, as described above, this modification 2 also has the respective signals SC, SA, which are analog voltage signals.
SH is obtained intermittently in this order, for example, at intervals of several seconds to ten and several seconds. Therefore, once the calibration signal SC is obtained, the magnitude (analog voltage) of the calibration signal SC is temporarily held in the sample hold circuit. After that, when the clean gas signal SA is obtained, the magnitude (analog voltage) of the clean gas signal SA is also temporarily held by the sample hold circuit. Then, when the measured gas signal SH is obtained, the dimming ratio Phc = (SA-SH) / (SA-SC).
An example is a method of calculating the dimming ratio signal SPhc of an analog voltage signal corresponding to the above by using an analog subtractor and an analog divider.

Next, in the third conversion processing unit 227, the dimming ratio signal SPhc is set to the digital value dimming ratio Phc.
AD conversion is performed and input to the CPU 50. After that, C functioning as the third concentration calculation unit 228
In the PU 50, the value of the concentration ch of the formula (1) is calculated by multiplying the calibration gas concentration cf (calibration coefficient kf) of the digital value stored in the calibration coefficient storage unit 29 and the dimming ratio Phc.

In the gas concentration detection device 201 of the present modification 2, as described above, the third analog calculation unit 22
In 6, the dimming ratio signal SPhc including the subtraction of SA-SH and the division of (SA-SH) / (SA-SC) is obtained by analog arithmetic processing, and then the dimming ratio Phc of the digital value is obtained. There is. Therefore, even when the concentration ch of the target gas GJ in the air to be measured GH is low (low),
Unlike the case of digital value processing where there is a risk of digit loss, it is possible to obtain the measured gas dimming rate Rah and the calibration filter dimming rate Rac with high accuracy, and thereby calculate the concentration ch with high accuracy. can do.

(Deformation form 3)
In the gas concentration detecting devices 1, 101, 201 of the above-described embodiments and modifications 1 and 2, FIG. 1
As shown by the solid line in the above, in the gas introduction / discharge unit 10, the measured gas GH of the measured space SPH is introduced into the container body 22S by the measured gas introduction unit 11, and the cleaning is performed by the clean gas introduction unit 12. The clean air (clean gas) GA of the region SPC is introduced into the container body 22S.

On the other hand, in the gas concentration detecting device 301 of the present modification 3, in the gas introduction / discharging unit 310, the measured gas GH of the measured space SPH is containerized by the measured gas introduction unit 11 in the same manner as in the embodiment and the like. It is introduced in the main body 22S. However, unlike the embodiments, the clean area S
Do not introduce the clean air (clean gas) GA of the PC into the container body 22S. That is, as shown by the broken line in FIG. 1, in the clean gas introduction unit 312, the purifying gas GC from which chlorine dioxide (target gas) GJ is removed from the measured gas GH obtained from the measured space SPH by the purifying unit 312C.
To generate. Specifically, the clean gas introduction pipe 312T branched from the measured gas introduction pipe 11T.
Leads the measured gas GH from the measured space SPH to the purification unit 312C. This purification unit 31
In 2C, an adsorbent (activated carbon) capable of adsorbing chlorine dioxide GJ is arranged. Therefore, chlorine dioxide GJ is removed from the purified gas GC that has passed through the purification unit 312CMC. Therefore, this purified gas GC is used as a clean gas GA (instead of the clean gas GA) and introduced into the container body 22S via the three-way solenoid valve 11V.

In the gas concentration detecting devices 1, 101, 201 of the first and second embodiments, as shown by the solid line in FIG. 1, the clean air GA containing no chlorine dioxide GJ is separated from the measured air GH.
Need to get. Generally, in obtaining this clean air GA, for example, it is preferable to use the outside space as the clean area SPC and the outside air as the clean air GA. However, when it becomes difficult to obtain the clean air GA, or the device In some cases, the installation location of the first grade was limited.

On the other hand, in the gas concentration detection device 301 of the modified form 3, the purification unit 312C generates a purification gas GC in which chlorine dioxide GJ is removed from the measured air GH, and this purification gas GC is used as the purification gas GA. Therefore, even in this device 301, the measured air GH and the clean gas G
With A (purified gas GC), the concentration ch of chlorine dioxide GJ in the air to be measured GH can be obtained. Moreover, in this device 301, it is not necessary to consider whether or not to obtain clean air GA such as outside air, or to install piping or the like connected to the outside air, and the device 301 is compact, has few restrictions on the installation location, and is easy to install. Can be. For example, after the exhaust of the gas pump 13P is discharged toward the space outside the measured space SPH, the device 301 is set to the measured space SP.
It is also possible to install it in H so that the air to be measured GH is taken into the device 301. Alternatively, the device 301 is installed in the measured space SPH so that the measured air GH is taken into the device 301 through the measured gas introduction unit 11, and from the measured gas introduction port 11K in the measured space SPH. The exhaust of the gas pump 13P may be discharged to a separated position.

In the above, the present invention has been described in accordance with the embodiments and modifications 1 to 3, but the present invention is not limited to the above-described embodiments and the like, and is appropriately modified as long as the gist of the present invention is not deviated. Needless to say, it can be applied.
For example, in the embodiment, an example in which the calibration dimming filter 23F is arranged in the optical path LWO after emission is shown. However, it may be arranged in the pre-incident optical path LWI, or may be arranged in both the pre-incident optical path LWI and the post-exit optical path LWO.

Further, in the above-described embodiment or the like, when the signal processing unit 25 obtains the gas signal SH to be measured, the air GH to be measured irradiated with the light source light 21L continues to be discharged from the gas container 22 and into the gas container 22. The gas introduction / discharge control unit 15 controlled the gas pump 13P to continue to operate so that a new air GH to be measured (not irradiated with the light source light 21L) was continuously introduced. However, in consideration of the degree of decrease in chlorine dioxide GJ in the measured air GH due to the irradiation of the light source light 21L, the operation of the gas pump 13P is stopped when the measured air GH is filled in the gas container 22. The gas pump 13P may be operated again at the timing of replacement with the clean air GA thereafter.

1,101,201 Gas concentration detection device 1PB Electronic board 10,310 Gas introduction / discharge unit 11 Measured gas introduction unit 15 Gas introduction / discharge control unit 20 Gas detection unit 21 Light source unit 21D Light source (ultraviolet light source)
21L light source light 21LB (light source light) emission wavelength range 21LI (light source light) light intensity 21BL branch light source light 21S light source light shield 22 gas container 22S container body 22SI gas inlet 22SO gas outlet 22I (gas container) incident window 22O (gas container) exit window 22TL (transmitted inside the gas container) transmitted light 22OL (exited from the exit window) emitted light 22OLI (exmitted light) light intensity LWI pre-incident light path LWO post-exit light path 22C container light-shielding cover 23 Filter movement control unit 23C Mechanism control unit 23M Filter movement mechanism 23F Calibration dimming filter kf (given to calibration dimming filter) Calibration coefficient cf (given to calibration dimming filter) Calibration gas concentration FD Filter placement state FN filter Non-arranged state 24 Emission light detection unit (analog emission light detection unit)
24P Emission light receiving element S (Obtained by the emission light detector) Light intensity signal SC Calibration signal SA Clean gas signal SH Measured gas signal DSC Calibration signal acquisition period DSA Clean gas signal acquisition period DSH Measured gas signal acquisition period SRah Measured gas dimming rate signal SRac calibration filter dimming rate signal Rah Measured gas dimming rate Rac calibration filter dimming rate SGah measured gas dimming amount signal SGac calibration filter dimming amount signal Gah measured gas dimming amount Gac calibration filter dimming amount SPhc Dimming ratio signal Phc Dimming ratio ch (target gas in the gas to be measured) Concentration SS Standard gas signal ScA Clean gas signal during calibration ScC Calibration signal during

calibration

25, 125, 225 Signal processing unit 26 1st analog arithmetic unit 126 2nd analog calculation unit 226 3rd analog calculation unit 27 1st conversion processing unit 127 2nd conversion processing unit 227 3rd conversion processing unit 28 1st concentration calculation unit 128 2nd concentration calculation unit 228 3rd concentration calculation unit 29 Calibration Coefficient storage unit 31 Light source light intensity detection unit 31LF Optical fiber 33 Light source light detection unit 33P Light source light light receiving element BS Branch light source light intensity signal 35 Light source control unit GH Measured air (measured gas)
GJ Target gas GJB (target gas) light absorption wavelength range c (target gas) concentration GA clean air (clean gas)
GS standard air (standard gas)
cs Standard concentration SPH Measured space SPC Clean area OL External light

Claims

A light source that emits light source light that includes at least a part of the light absorption wavelength range of the target gas within the emission wavelength range,
A gas container filled with the gas to be measured or a clean gas that does not contain the target gas.
An incident window that allows the light source light to enter the gas container, and
A gas container having an exit window for emitting emitted light after passing through the inside of the gas container, and a gas container.
An emission light detection unit that receives the emission light emitted from the emission window and outputs a light intensity signal S.
A gas concentration detecting device including a signal processing unit that acquires a concentration channel of the target gas in the gas to be measured by using the light intensity signal S.
It shall be arranged in at least one of the pre-incident optical path in which the light source light travels from the light source to the incident window and the post-exit optical path in which the emitted light travels from the emitted window to the emitted light detection unit. A calibration dimming filter that reduces the light intensity of the emitted light that reaches the emitted light detection unit is provided.
The above signal processing unit
Of the above light intensity signals S
The calibration signal SC obtained when the gas container is filled with the clean gas and the light intensity of the emitted light is reduced by the calibration dimming filter.
Obtained before and after the calibration signal SC, the gas container is filled with the clean gas, and the gas container is filled with the clean gas.
Moreover, the clean gas signal SA obtained when the light intensity of the emitted light is not reduced by the calibration dimming filter, and
When the gas container is filled with the gas to be measured and the light intensity of the emitted light by the calibration dimming filter is not reduced, which is obtained before and after the calibration signal SC and the clean gas signal SA. The obtained gas signal SH to be measured and
From the calibration coefficient given to the calibration dimming filter according to the degree of dimming that the calibration dimming filter reduces the light intensity of the emitted light.
A gas concentration detecting device that acquires the concentration ch of the target gas in the gas to be measured.
The gas concentration detecting device according to claim 1.
The emitted light detection unit is
An emission light detection unit that outputs a light intensity signal S proportional to the light intensity of the emitted light received.
The calibration coefficient given to the calibration dimming filter is
Calibration gas concentration cf of the target gas corresponding to the degree of dimming of the calibration dimming filter
And
The signal processing unit
Using the calibration signal SC, the clean gas signal SA, the measured gas signal SH, and the calibration gas concentration cf, the concentration ch of the target gas in the measured gas is expressed by the following formula (
A gas concentration detector calculated based on 1).
ch = cf ・ (SA-SH) / (SA-SC) ・・・ (1)
The gas concentration detecting device according to claim 2.
The emitted light detection unit is
An analog emission light detection unit that outputs an analog light intensity signal S proportional to the light intensity of the emitted light received.
The signal processing unit
The calibration signal SC, the clean gas signal SA, and the measured gas signal SH, which are analog signals, are subjected to analog arithmetic processing, and the measured gas dimming rate Rah = (in the above equation (1)).
The first analog that outputs the measured gas dimming rate signal SRah corresponding to SA-SH) / SA and the calibration filter dimming rate signal SRac corresponding to the calibration filter dimming rate Rac = (SA-SC) / SA. The arithmetic unit and
The first conversion processing unit that converts the measured gas dimming rate signal SRah and the calibration filter dimming rate signal SRac into the digital values of the measured gas dimming rate Rah and the calibration filter dimming rate Rac, respectively.
From the calibration gas concentration cf of the digital value, the dimming rate Rah of the measured gas, and the dimming rate Rac of the calibration filter, the value of the concentration ch of the target gas in the measured gas of the above formula (1) is calculated. A gas concentration detecting device having a first concentration calculating unit.
The gas concentration detecting device according to claim 2.
The emitted light detection unit is
An analog emission light detection unit that outputs an analog light intensity signal S proportional to the light intensity of the emitted light received.
The signal processing unit
The calibration signal SC, the clean gas signal SA, and the measured gas signal SH, which are analog signals, are subjected to analog arithmetic processing, and in the above equation (1), the measured gas dimming amount Gah = S.
Measured gas dimming amount signal SGah corresponding to A-SH and calibration filter dimming amount Gac =
The second analog arithmetic unit that outputs the calibration filter dimming amount signal SGac corresponding to SA-SC, and
A second conversion processing unit that converts the measured gas dimming amount signal SGah and the calibration filter dimming amount signal SGac into the digital values of the measured gas dimming amount Gah and the calibration filter dimming amount Gac, respectively.
The second value of the concentration ch of the target gas in the measured gas of the above formula (1) is calculated from the calibration gas concentration cf of the digital value, the dimming amount Gah of the measured gas, and the dimming amount Gac of the calibration filter. A gas concentration detector having a concentration calculation unit.
The gas concentration detecting device according to claim 2.
The emitted light detection unit is
An analog emission light detection unit that outputs an analog light intensity signal S proportional to the light intensity of the emitted light received.
The signal processing unit
The calibration signal SC, the clean gas signal SA, and the gas signal SH to be measured, which are analog signals, are subjected to analog arithmetic processing, and the dimming ratio Phc = (SA-SH) in the formula (1).
A third analog arithmetic unit that outputs a dimming ratio signal SPhc corresponding to / (SA-SC), and
A third conversion processing unit that converts the dimming ratio signal SPhc into a digital dimming ratio Phc, and
A gas concentration detecting device having a third concentration calculating unit for calculating the value of the concentration ch of the target gas in the measured gas of the above formula (1) from the calibration gas concentration cf and the dimming ratio Phc of the digital value. ..
The gas concentration detecting device according to any one of claims 1 to 5.
Move the calibration dimming filter to
The filter arrangement state that reduces the light intensity of the emitted light with the calibration dimming filter,
A gas concentration detecting device further provided with a filter movement control unit that realizes a filter non-arranged state that does not cause a decrease in the light intensity of the emitted light by the calibration dimming filter.
The gas concentration detecting device according to any one of claims 1 to 6.
It is provided with a calibration coefficient storage unit that rewritably stores the calibration coefficient given to the calibration dimming filter.
The above calibration coefficient is
The standard gas signal SS obtained when the inside of the gas container is filled with a standard gas having a known standard concentration of the target gas and the light intensity of the emitted light by the calibration dimming filter is not reduced. ,
Cleaning at the time of calibration obtained when the gas container is filled with the cleaning gas and the light intensity of the emitted light is not reduced by the calibration dimming filter, which is obtained before and after the standard gas signal SS. Gas signal ScA and
Obtained before and after the standard gas signal SS and the clean gas signal ScA at the time of calibration, the inside of the gas container was filled with the clean gas, and the light intensity of the emitted light was reduced by the calibration dimming filter. A gas concentration detector that is a value calculated from the calibration signal ScC at the time of calibration.
The gas concentration detecting device according to any one of claims 1 to 7.
A light source light intensity detecting unit that detects the light intensity of the light source light emitted by the light source, and
A gas concentration detecting device further comprising a light source control unit that drives and controls the light source so that the light intensity of the light source light detected by the light source light intensity detecting unit becomes constant.
The gas concentration detecting device according to claim 8.
The light source light intensity detecting unit is
An optical fiber that guides the branched light source light that is a part of the light source light emitted by the light source,
It has a light source light detection unit that receives the branch light source light emitted from the optical fiber and outputs a branch light source light intensity signal BS.
The light source control unit
A gas concentration detection device that drives and controls the light source so that the magnitude of the branch light intensity signal BS output from the light source light detection unit is constant.
The gas concentration detecting device according to claim 9 is provided.
The emitted light detection unit is
It has an emitted light receiving element that receives the emitted light and converts it into an electric signal.
The light source light detection unit is
It has a light source light receiving element of the same manufacturer and the same part number as the emitted light receiving element, which receives the branched light source light and converts it into an electric signal.
The emitted light receiving element and the light source light receiving element are gas concentration detecting devices mounted on the same electronic substrate in close proximity to each other.
The gas concentration detecting device according to any one of claims 1 to 10.
A purification unit for generating a purification gas obtained by removing the target gas from the gas to be measured guided toward the gas container is provided.
A gas concentration detecting device that uses the purified gas as the purified gas that fills the gas container.
: During the measurement of the measured gas signal SH, the measured gas is left to flow.
The gas concentration detecting device according to any one of claims 1 to 11.
The target gas is chlorine dioxide.
The gas container is
A gas inlet for introducing the gas to be measured or the clean gas into the gas container,
It has a gas discharge port for discharging the introduced gas to be measured or the clean gas from the inside of the gas container.
Introduction of the clean gas or the gas to be measured into the gas container through the gas inlet,
It also has a gas introduction / discharge unit that discharges the clean gas or the measured gas from the inside of the gas container through the gas discharge port.
The gas introduction / discharge section is
It has a gas introduction / discharge control unit that controls the introduction of the clean gas or the gas to be measured into the gas container and the discharge from the gas container.
The gas introduction / emission control unit is
At least during the period for acquiring the measured gas signal SH in which the signal processing unit obtains the measured gas signal SH,
By the above gas introduction and discharge part
The gas to be measured, which has already been irradiated with the light source, is continuously discharged from the gas container through the gas discharge port, and is also discharged.
A gas concentration detecting device that controls the continuous introduction of the gas to be measured, which has not been irradiated with the light source light, into the gas container through the gas introduction port.
The gas concentration detecting device according to any one of claims 1 to 12.
The target gas is chlorine dioxide.
The gas to be measured is the air to be measured introduced from the space to be measured.
The clean gas is clean air that does not contain chlorine dioxide.
The light source is an ultraviolet light source that emits ultraviolet light as the light source light.
The gas container is shielded from external light and light from the light source, except for the incident window and the exit window.
The gas concentration detection device for introducing the air to be measured, which is the gas to be measured, from the space to be measured into the gas container is a gas concentration detecting device that is shielded from external light and light from a light source.