JP6083466B2 - Gas analyzer - Google Patents

Description

  The present invention relates to a gas analyzer that measures gas concentrations of a plurality of gases contained in a sample gas.

For example, Patent Literature 1 discloses a conventional gas analyzer. This prior art will be described with reference to the drawings. FIG. 11 is a prior art absorption spectrometer described in Patent Document 1.
The absorption spectrometer 300 measures the concentration of NO ₂ (nitrogen dioxide) contained in the sample gas using an ultraviolet absorption method. The absorption spectrometer 300 includes an ultraviolet light source 301, a visible light source 302, a reference cell 303, a sample cell 304, a light guide mechanism 305, a light detection unit 306, a control unit 307, and a calculation unit 308. ing.

The ultraviolet light source 301 is a light emitting diode that emits ultraviolet light. The central emission wavelength of the ultraviolet light is 360 to 400 nm, and is included in the absorption wavelength band of NO ₂ as shown in the wavelength-absorption coefficient characteristic diagram of FIG. Upon irradiation of such ultraviolet light into NO _2, the absorption by the NO ₂ is performed.

The visible light source 302 is a light emitting diode that emits visible light. Since the central emission wavelength of visible light is larger than the wavelength of ultraviolet light, it is included in the absorption wavelength band of NO ₂ as shown in the wavelength-absorption coefficient characteristic diagram of FIG. Is different. Such absorption of visible light by NO ₂ is irradiated to NO ₂ is performed, when compared with the absorption of ultraviolet light by the above NO _2, so that absorbance of visible light is reduced by the NO _2, the visible light source 302 The wavelength is set.

  The reference cell 303 is filled with a reference gas. This reference gas is, for example, nitrogen gas. Ultraviolet light or visible light is incident through the windows 303a and 303b.

  The sample cell 304 is supplied with a sample gas to be measured. Ultraviolet light or visible light is incident through the windows 304a and 304b. The sample gas flows into the sample cell 304 through the gas inlet 304c and flows out through the gas outlet 304d.

The light guide mechanism 305 includes a mirror 305a and a half mirror 305b. The ultraviolet light from the ultraviolet light source 301 and the visible light from the visible light source 302 are reflected from the half mirror 305b and the mirror 305a and introduced into the reference cell 303 from one end side through the window 303a of the reference cell 303. Also, ultraviolet light from the ultraviolet light source 301 and visible light from the visible light source 302 are transmitted through the half mirror 305 b and introduced into the sample cell 304 from one end side through the window 304 a of the sample cell 304. Absorption by NO ₂ is performed in the sample cell 304.

  The light detection unit 306 includes light detectors 306a and 306b. The photodetector 306a is provided on the other end side of the reference cell 303, and detects ultraviolet light or visible light transmitted through the window 303b of the reference cell 303. The photodetector 306b is provided on the other end side of the sample cell 304, and detects ultraviolet light and visible light transmitted through the window 304b of the sample cell 304.

  The control unit 307 causes the ultraviolet light source 301 and the visible light source 302 to emit light in a time-sharing manner. The light detection unit 306 obtains two-wavelength transmitted light that passes through the reference cell 303 and the sample cell 304. As a result, there are two optical paths and two wavelengths, and four signals are obtained: a sample signal for ultraviolet transmitted light, a sample signal for visible transmitted light, a reference signal for ultraviolet transmitted light, and a reference signal for visible transmitted light.

The calculation unit 308 receives the four signals from the light detection unit 306 via the control unit 307, and calculates the NO ₂ gas concentration based on the four signals. Thereby, compensation of drift of the ultraviolet light source 301 and visible light source 302, correction of interference of other components other than the measurement component, correction of light amount reduction due to dirt and clouding of the transmission windows 304a and 304b of the sample cell 304, correction of sensitivity drift, and the like. Make it possible. The NO ₂ gas concentration can be calculated after performing these corrections, and the measurement accuracy is improved.

JP 2011-149965 A (title of the invention “absorption spectrometer”)

  However, in the above-described conventional technology, the measurable gas component is limited to one type. Therefore, in order to measure the concentration of two or more kinds of gases by the absorption method, a plurality of sets of light emitting means for emitting a wavelength for absorbing a certain gas and light receiving means for receiving this light are required for each gas. . Thus, in the prior art, there is a problem that the configuration increases in order to measure the concentration of two or more kinds of gases.

Further, in the prior art, even if there is only one kind of gas to be measured, nitrogen monoxide gas (NO gas) or sulfur dioxide gas (SO ₂ gas) cannot be used as a measurement component. This is because, as shown in FIG. 12, at the absorption wavelength of NO gas in the ultraviolet wavelength region, there is absorption of SO ₂ gas and NO ₂ gas, which is influenced by other gases. Further, at the absorption wavelength of SO ₂ gas in the ultraviolet wavelength region, there was absorption of NO ₂ gas, which was influenced by other gases.

Further, at the absorption wavelength of NO ₂ gas in the visible wavelength region (wavelength of 400 nm or more), NO gas and SO ₂ gas do not absorb, and visible transmitted light does not contain information about NO gas and SO ₂ gas. Therefore, it is impossible to correct interference caused by NO gas or SO ₂ gas, or to use it for concentration measurement of NO gas or SO ₂ gas.
If it contains gas components NO gas and SO ₂ gas in this manner the sample gas was analyzed gas components of these NO gas and SO ₂ gas is difficult.

Therefore, the present invention has been made to solve the above-described problems, and its purpose is to include nitrogen monoxide gas (NO gas) and nitrogen dioxide gas (contained in the sample gas and not conventionally easy to analyze). analysis of the gas concentration of the two components of the NO ₂ gas) or nitrogen gas (NO monoxide gas), and so the analysis of gas concentration 3 components of the nitrogen gas (NO ₂ gas) and sulfur dioxide gas dioxide (sO ₂₎ Another object of the present invention is to provide a gas analyzer capable of analyzing multi-component gas concentrations with a simple configuration.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to an oxidation output state in which a sample gas is mixed with ozone gas and subjected to an oxidation reaction, and then heated and output as a first measurement target gas. a normal output state for outputting a second measurement target gas as a reaction, and switching Ru gas conditioning unit,
A light emitting part for absorbing NO ₂ gas that irradiates irradiation light for absorbing NO ₂ gas having a wavelength of 320 nm to 600 nm in which nitrogen dioxide gas (NO ₂ gas) absorbs;
The first, a detection space in which the second measurement target gas flows, the light transmission window for entering the NO ₂ gas absorption for the irradiation light to the detection space, the gas flow cell having,
A transmitted light receiving unit that receives the irradiation light for absorbing the NO ₂ gas transmitted through the detection space from the light transmission window;
The gas adjusting unit and the NO ₂ gas absorption light emitting unit are controlled to irradiate the NO ₂ gas absorption irradiation light in a state where the first and second measurement target gases are respectively circulated through the gas flow cell. A drive control unit;
A reference light receiving unit that receives the irradiation light for absorbing NO ₂ gas as reference light ;
An optical path for allowing the irradiation light for NO ₂ gas absorption to pass through the detection space through the light transmission window and reach the transmitted light receiving part; and an optical path for reaching the reference light receiving part without passing through the detection space; And an optical path determination unit that allows the light to pass separately.
A correction unit that controls the drive current of the light emitting unit for absorbing NO ₂ gas based on the amount of reference light received by the reference light receiving unit ;
Calculating a gas concentration of nitrogen dioxide gas in the sample gas from a calculated value according to the amount of light received by the transmitted light receiving unit when the first measurement object gas is irradiated with the irradiation light for absorbing NO ₂ gas, The second measurement target gas is irradiated with the NO ₂ gas absorption irradiation light from a calculated value corresponding to the amount of light received by the transmitted light receiving unit when the first measurement target gas is irradiated with the NO ₂ gas absorption irradiation light. characterized in that it comprises the a signal processing unit for calculating the gas concentration of nitric oxide gas by subtracting the calculated value corresponding to the received light amount of the transmitted light receiving unit and the sample gas (NO gas) when .

The invention according to claim 2 is an oxidation output state in which the sample gas is mixed with ozone gas to cause an oxidation reaction and then heated and output as the first measurement object gas, and the second measurement object is left unreacted with the sample gas. a normal output state for outputting as a gas, a switching Ru gas conditioning unit,
A light emitting part for absorbing NO ₂ gas that irradiates irradiation light for absorbing NO ₂ gas having a wavelength of 320 nm to 600 nm in which nitrogen dioxide gas (NO ₂ gas) absorbs;
A SO ₂ gas absorption light emitting unit for irradiating SO ₂ gas absorption irradiation light having a wavelength of 250 nm to 320 nm in which sulfur dioxide gas (SO ₂ gas) and nitrogen dioxide gas absorb;
The first, a detection space in which the second measurement target gas flows, gas flow cell having a light transmission window for the NO ₂ gas absorption irradiation light and the SO ₂ gas absorption for the irradiation light is incident on the detection space When,
A transmitted light receiving unit that receives the irradiation light for absorbing NO ₂ gas and the irradiation light for absorbing SO ₂ gas transmitted through the detection space from the light transmission window;
The NO ₂ gas absorption irradiation light and the SO ₂ gas absorption irradiation light are sequentially irradiated in a state where the first measurement target gas is circulated through the gas distribution cell, and the second measurement target gas is supplied to the gas distribution cell. A drive control unit that controls the gas adjusting unit, the NO ₂ gas absorbing light emitting unit, and the SO ₂ gas absorbing light emitting unit so as to irradiate the irradiation light for NO ₂ gas absorbing in a state of being distributed to
A reference light receiving unit that receives the irradiation light for absorbing NO ₂ gas and the irradiation light for absorbing SO ₂ gas as reference light;
The NO ₂ gas absorption irradiation light and the SO ₂ gas absorption irradiation light are transmitted through the detection space through the light transmission window and reach the transmitted light receiving unit and the detection space without passing through the detection space. An optical path determination unit that allows the optical path to reach the reference light receiving unit and separates the optical path;
A correction unit that controls driving currents of the NO ₂ gas absorption light-emitting unit and the SO ₂ gas absorption light-emitting unit based on the amount of reference light received by the reference light receiving unit ;
Calculating a gas concentration of nitrogen dioxide gas in the sample gas from a calculated value according to the amount of light received by the transmitted light receiving unit when the first measurement object gas is irradiated with the irradiation light for absorbing NO ₂ gas, the transmitted light when irradiated with the NO ₂ gas absorption for the irradiation light in the second measurement target gas calculated value corresponding to the received light amount when irradiated with the NO ₂ gas absorption for the irradiation light to the first measurement target gas calculating a gas concentration of nitric oxide gas in front Symbol sample gas by subtracting the calculated value according to the amount of light received by the light receiving portion (NO gas), the SO ₂ gas absorption for the irradiation light in the first measurement target gas sulfur dioxide gas in the sample gas by subtracting the calculated value corresponding to the received light amount when the from the calculated value corresponding to the received light amount is irradiated with the NO ₂ gas absorption for the irradiation light in the first measurement target gas when irradiated A signal processing unit for calculating the gas concentration of Characterized in that it comprises.

The invention according to claim 3 is an oxidation output state in which the sample gas is mixed with ozone gas to cause an oxidation reaction and then heated and output as the first measurement object gas, and the second measurement object is left unreacted with the sample gas. a normal output state for outputting as a gas, a switching Ru gas conditioning unit,
A light emitting part for absorbing NO ₂ gas that irradiates irradiation light for absorbing NO ₂ gas having a wavelength of 320 nm to 600 nm in which nitrogen dioxide gas (NO ₂ gas) absorbs;
A SO ₂ gas absorption light emitting unit for irradiating SO ₂ gas absorption irradiation light having a wavelength of 250 nm to 320 nm in which sulfur dioxide gas (SO ₂ gas) and nitrogen dioxide gas absorb;
The first, a detection space in which the second measurement target gas flows, gas flow cell having a light transmission window for the NO ₂ gas absorption irradiation light and the SO ₂ gas absorption for the irradiation light is incident on the detection space When,
A transmitted light receiving unit that receives the irradiation light for absorbing NO ₂ gas and the irradiation light for absorbing SO ₂ gas transmitted through the detection space from the light transmission window;
The NO ₂ gas in a state where the first measurement target gas is irradiated with the NO ₂ gas absorption for the irradiation light in the state of being distributed in the gas flow cell, was passed through the second measurement target gas into the gas flow cell A drive control unit for controlling the gas adjusting unit, the NO ₂ gas absorbing light emitting unit, and the SO ₂ gas absorbing light emitting unit so as to sequentially emit the absorbing light for absorbing light and the irradiated light for absorbing SO ₂ gas;
A reference light receiving unit that receives the irradiation light for absorbing NO ₂ gas and the irradiation light for absorbing SO ₂ gas as reference light;
The NO ₂ gas absorption irradiation light and the SO ₂ gas absorption irradiation light are transmitted through the detection space through the light transmission window and reach the transmitted light receiving unit and the detection space without passing through the detection space. An optical path determination unit that allows the optical path to reach the reference light receiving unit and separates the optical path;
A correction unit that controls driving currents of the NO ₂ gas absorption light-emitting unit and the SO ₂ gas absorption light-emitting unit based on the amount of reference light received by the reference light receiving unit ;
Calculating a gas concentration of nitrogen dioxide gas in the sample gas from a calculated value according to the amount of light received by the transmitted light receiving unit when the first measurement object gas is irradiated with the irradiation light for absorbing NO ₂ gas, The second measurement target gas is irradiated with the NO ₂ gas absorption irradiation light from a calculated value corresponding to the amount of light received by the transmitted light receiving unit when the first measurement target gas is irradiated with the NO ₂ gas absorption irradiation light. The gas concentration of the nitric oxide gas (NO gas) in the sample gas is calculated by subtracting the calculated value obtained according to the amount of received light at the time, and the SO ₂ gas absorption irradiation light is applied to the second measurement object gas. the subtracting the calculated value corresponding to the received light amount when the irradiated from the calculated value corresponding to the received light amount of the transmitted light receiving unit of the NO ₂ gas absorption for the irradiation light in the first measurement target gas when irradiated the gas concentration of sulfur dioxide gas in the sample gas Characterized in that it comprises a signal processing unit for calculating a.

The invention according to claim 4 is the gas analyzer according to any one of claims 1 to 3,
The gas adjusting unit is
When there is no command from the drive control unit, a raw material gas is output, and when there is the command, an ozone generation unit that generates ozone gas from the raw material gas and outputs a raw material gas containing ozone gas,
A gas mixing section for mixing and outputting the sample gas and the source gas;
A gas heating unit configured to heat the mixed gas from the gas mixing unit and output the mixed gas as the first and second measurement target gases .

The invention according to claim 5 is the gas analyzer according to any one of claims 1 to 3,
Before SL signal processing unit, and calculates the gas concentration on the basis of the ratio between the received light amount of the transmitted light by the transmitted light receiving unit and the light receiving amount of the reference light due to the reference light receiving unit.

The invention according to claim 6 is the gas analyzer according to claim 1,
The drive control unit is the NO that is a light emitting diode or a laser diode. ₂ It is a pulse that alternately performs output and stop of the gas light-absorbing light emitting unit, and the NO is generated by a drive current having a duty ratio that is shorter than the stop period. ₂ The light-absorbing light emitting unit is driven.

The invention according to claim 7 is the gas analyzer according to claim 2 or claim 3, wherein
The drive control unit is the NO that is a light emitting diode or a laser diode. ₂ It is a pulse that alternately performs output and stop of the gas light-absorbing light emitting unit, and the NO is generated by a drive current having a duty ratio that is shorter than the stop period. ₂ The SO that is a light-emitting diode is driven by the light-absorbing light-emitting unit ₂ The SO is generated by a drive current having a duty ratio that alternately outputs and stops the gas absorption light-emitting unit and has an output period shorter than the stop period. ₂ The light-absorbing light emitting unit is driven.

According to the present invention, analysis of gas concentrations of two components of nitrogen monoxide gas (NO gas) and nitrogen dioxide gas (NO ₂ gas), which are included in the sample gas and were not easily analyzed in the past, or monoxide Enables analysis of multi-component gas concentrations with a simple configuration, such as analysis of three-component gas concentrations of nitrogen gas (NO gas), nitrogen dioxide gas (NO ₂ gas), and sulfur dioxide gas (SO ₂ ). A gas analyzer can be provided.

It is a whole block diagram of the gas analyzer which concerns on the form for implementing this invention. It is a whole block diagram of the gas analyzer which concerns on the other form for implementing this invention. It is a partial block diagram of the gas analyzer which concerns on the other form for implementing this invention. It is a partial block diagram of the gas analyzer which concerns on the other form for implementing this invention. It is a partial block diagram of the gas analyzer which concerns on the other form for implementing this invention. It is a partial block diagram of the gas analyzer which concerns on the other form for implementing this invention. It is a partial block diagram of the gas analyzer which concerns on the other form for implementing this invention. It is a characteristic view which shows the duty ratio-allowable current characteristic of a light emitting diode. It is explanatory drawing of the time change of the drive signal of the light emitting diode produced | generated by the pulse signal. It is explanatory drawing of the time change of the drive signal of the light emitting diode produced | generated by the small duty ratio pulse signal. It is a block diagram of the absorption spectrometer of a prior art. _NO, the wavelength showing the absorption coefficient in the visible region and ultraviolet regions of the NO 2, SO ₂ gas - is the extinction coefficient characteristic diagram.

Next, the gas analyzer which concerns on the basic form of this invention is demonstrated below, referring a figure. FIG. 1 is an overall configuration diagram of a gas analyzer according to this embodiment. In FIG. 1, thick solid arrows indicate gas flow paths, dotted arrows indicate light paths, and thin solid lines indicate electrical signal paths.

First, the components provided in the gas analyzer 100 of this embodiment and their functions will be described. As shown in FIG. 1, the gas analyzer 100 includes a light emitting unit 11 for absorbing NO ₂ gas, a light emitting unit 12 for absorbing SO ₂ gas, an optical path determining unit 13, a gas flow cell 21, a transmitted light receiving unit 31, and a reference light receiving unit. Unit 32, gas adjustment unit 41, gas suction unit 51, and signal processing / drive control unit 61.

NO ₂ gas absorption for the light emitting unit 11 is a wavelength NO ₂ gas absorption, and a light emitting unit that SO ₂ gas to emit NO ₂ gas absorption for the irradiation light of wavelengths not absorption. For example, a light source of irradiation light having a central emission wavelength in a wavelength range of 320 nm to 600 nm in a region extending from ultraviolet light to visible light, for example, a light emitting diode (LED) or a laser diode (LD) can be selected. As shown in FIG. 12, only NO ₂ gas absorbs light in this wavelength region.

SO ₂ gas absorption for the light emitting unit 12 is a wavelength SO ₂ gas absorption, and a light emitting portion for emitting SO ₂ gas absorption for the irradiation light of a wavelength that NO gas is not absorption. For example, a light source of irradiation light having a central emission wavelength at a wavelength of 250 nm to 320 nm in the ultraviolet region, for example, a light emitting diode (LED) can be selected at present. As shown in FIG. 12, in this wavelength region, not only SO ₂ gas but also NO ₂ gas is absorbed.

The optical path determination unit 13 is a half mirror that transmits the irradiation light for absorbing NO ₂ gas with a predetermined transmittance and reflects the irradiation light with a predetermined reflectance. Further, the optical path determination unit 13 transmits the irradiation light for absorbing the SO ₂ gas and reflects the irradiation light with a predetermined reflectance. As will be described later, the NO ₂ gas absorption irradiation light and the SO ₂ gas absorption irradiation light are not output at the same time. For example, only one of them is output independently for each time.

The irradiation light for NO ₂ gas absorption irradiated from the NO ₂ gas absorption light emitting unit 11 enters the optical path determination unit 13. In the optical path determination unit 13, a part of the irradiation light for absorbing NO ₂ gas is reflected, and the remaining irradiation light for absorbing NO ₂ gas is transmitted. The irradiation light for absorbing NO ₂ gas reflected by the optical path determination unit 13 enters the reference light receiving unit 32. Further, the irradiation light for absorbing NO ₂ gas that has passed through the optical path determination unit 13 enters the gas flow cell 21. Similarly, the irradiation light emitted from the SO ₂ gas absorption light emitting unit 12 also enters the optical path determination unit 13. In the optical path determination unit 13, part of the irradiation light for absorbing SO ₂ gas is reflected and the rest of the irradiation light for absorbing SO ₂ gas is transmitted. SO ₂ irradiation light gas absorption reflected by the optical path determining part 13 is incident on the reference light receiving unit 32. In addition, the irradiation light for absorbing SO ₂ gas transmitted through the optical path determination unit 13 is incident on the gas flow cell 21.

  The gas flow cell 21 further includes a tube 22, light transmission windows 23 and 24, a detection space 25, a gas inlet 26, and a gas outlet 27.

  The tube 22 is a cylinder. The inner surface of the tube 22 can be, for example, a polished stainless steel inner surface. Thereby, the reflectance of irradiation light can be kept favorable, preventing adsorption of measurement object gas. In the tube 22, the irradiation light propagates while being reflected by the inner surface of the tube 22.

The light transmission window 23 and the light transmission window 24 are made of a material exhibiting light transmittance in the emission wavelength region of the irradiation light irradiated from the NO ₂ gas absorption light emitting unit 11 and the SO ₂ gas absorption light emitting unit 12. . For example, synthetic quartz or calcium fluoride can be used as the material.

The detection space 25 is a closed space defined by the tube 22, the light transmission window 23, and the light transmission window 24.
The gas inlet 26 and the gas outlet 27 communicate with the detection space 25. The measurement target gas flows into the detection space 25 from the gas inlet 26 and flows out of the gas outlet 27.
In such a gas flow cell 21, irradiation light is irradiated to the flowing measurement target gas, and light absorption occurs.

Transmitted light receiving unit 31 is irradiated from the NO ₂ gas absorption for the light emitting unit 11, and receives the irradiated light for NO ₂ gas absorption which has passed through the gas flow cell 21 and outputs a detection signal corresponding to the light intensity. Further, the transmitted light receiving unit 31 is irradiated from the SO ₂ gas absorption for the light emitting unit 12, and outputs a detection signal corresponding to the light intensity by receiving the irradiated light for SO ₂ gas absorption which has passed through the gas flow cell 21. As the transmitted light receiving unit 31, a photodiode, a photomultiplier tube, or the like having sensitivity to the emission wavelength of the NO ₂ gas absorption irradiation light or the SO ₂ gas absorption irradiation light can be selected. For example, a silicon photodiode can be selected.

  The transmitted light receiving unit 31 detects light absorption by the measurement target gas, and has a function of outputting a light intensity signal proportional to the amount of received irradiation light to the signal processing / drive control unit 61. That is, compared with the case where there is no light absorption by the measurement target gas, the light intensity of the irradiation light received by the transmitted light receiving unit 31 decreases when there is light absorption. The gas concentration is measured using the correlation between the two.

Thus, the NO ₂ gas absorption irradiation light and the SO ₂ gas absorption irradiation light transmitted through the optical path determining unit 13 pass through the light-transmitting light transmission window 23 constituting one end of the gas flow cell 21, and The light propagates through the internal detection space 25, passes through the light-transmitting light transmitting window 24 that forms the other end, and enters the transmitted light receiving unit 31.

Reference-light receiving part 32 is radiated from the NO ₂ gas absorption for the light emitting unit 11 receives the NO ₂ gas absorption irradiation light reflected by the optical path determining section 13, the signal processing light amount intensity signal proportional to the amount of light that is received A function for outputting to the drive control unit 61 is provided. The reference light receiving unit 32 is irradiated from the SO ₂ gas absorption for the light emitting unit 12 receives the SO ₂ gas absorption irradiation light reflected by the optical path determining section 13, the light amount intensity signal proportional to the amount of light that is received It has a function of outputting to the signal processing / drive control unit 61. As the reference light receiving unit 32, a photodiode, a photomultiplier tube, or the like having sensitivity to the emission wavelength of the NO ₂ gas absorption irradiation light or the SO ₂ gas absorption irradiation light can be selected. For example, a silicon photodiode can be selected.

Reference light when the intensity of the irradiation light for NO ₂ gas absorption or the irradiation light for SO ₂ gas absorption varies due to the temperature rise or the like of the NO ₂ gas absorption light emitting unit 11 and the SO ₂ gas absorption light emitting unit 12 The light intensity signal of the NO ₂ gas absorption irradiation light and the SO ₂ gas absorption irradiation light received by the light receiving unit 32 varies. The gas concentration is corrected using the fluctuation amount of the light intensity.

  The gas adjustment unit 41 further includes an ozone generation unit 42, a gas mixing unit 43, and a gas heating unit 44.

The ozone generator 42 has a function of generating ozone. Atmosphere containing oxygen to the ozone generator 42, instrument air, or the raw material gas G _O such as oxygen gas flows. The operation of the ozone generator 42 is controlled by a signal processing / drive controller 61. Material In operation of the ozone generator 42, ozone generator 42, by electrical means, such as silent discharge, using an oxygen gas of the raw material gas G _O generates O ₃ gas, containing O ₃ gas sufficiently The gas _GO is discharged. In an off-state, the ozone generator 42 is directly passing the raw material gas G _O without generating the O ₃ gas. In this way, the signal processing / drive control unit 61 controls the operation / non-operation of the ozone generation unit 42.

Gas mixing unit 43, at the time the raw material gas G _{O (operation} from the sample gas G _S and ozone generator 42 is a raw material gas G _O containing O ₃ gas in large quantities, also in an off-state free of O ₃ gas is provided to mix the free feed gas is G _O). During operation of the ozone generator 42, intermediate reactant gas portion and a chemical reaction occurs in a portion sample gas G _S of the O ₃ gas in the gas mixing portion 43 will be described later is generated, the intermediate reaction gas, excess O ₃ gas, thereby discharging the material gas G _O and excess sample gas G _S excess. Also, when not in operation of the ozone generator 42 is allowed to flow out by mixing it with a raw material gas G _O and the sample gas G _S from the ozone generator 42. Further, as will be described later, when the zero gas G _ZERO or the span gas G _SPAN flows in, the gas mixing unit 43 flows out as it is.

The gas heating unit 44 heats the gas flowing in from the gas mixing unit 43. In operation of the ozone generator 42, the intermediate reaction gas, O ₃ gas, and heating the raw material gas G _O and the sample gas G _S excess is further flow out proceeded a reaction gas as a measurement target gas. Further, in the off-state of the ozone generator 42, because there is no even react by heating the raw material gas G _O and the sample gas G _S from the ozone generator 42, and a directly feed gas G _O and the sample gas G _S Let it flow out as the gas to be measured. The measurement target gas flowing out from the gas heating unit 44 flows through the detection space 25 in the gas flow cell 21 from the gas inlet 26 and flows out from the gas outlet 27.

  The gas suction unit 51 has a function of sucking gas. By exhausting the detection space 25 of the gas flow cell 21, the measurement target gas from the gas heating unit 44 is drawn into the detection space 25. The gas suction part 51 can also be provided between the gas heating part 44 and the gas inlet 26.

The signal processing / drive control unit 61 is an integration of the signal processing unit and the drive control unit of the present invention, and performs both a function as a signal processing unit and a function as a drive control unit. is there. The signal processing / drive control unit 61 has a function of supplying a drive current necessary for causing the NO ₂ gas absorption light emitting unit 11 and the SO ₂ gas absorption light emitting unit 12 to emit light. Further, the signal processing / drive control unit 61 has a received light signal processing function for calculating the gas concentration based on the light intensity signal output from the transmitted light receiving unit 31 and the reference light receiving unit 32. Further, the signal processing / drive control unit 61 has a control function for switching operation / non-operation of the ozone generation unit 42.
The configuration of the gas analyzer 100 is as described above.

  Subsequently, analysis by the gas analyzer 100 will be described. First, the principle of measurement by absorption will be described. The principle of measurement is an absorption method based on the following Lambert-Beer law.

[Equation 1]
P ₁ = P ₀ · exp (−ε · c · L)

Here, P ₁ is the output intensity of the transmitted light that has passed through the measurement target gas flowing in the detection space 25, P ₀ is the output intensity of the reference light before passing through the measurement target gas, ε is the molar extinction coefficient, and c is The gas concentration, L, represents the optical path length. The molar extinction coefficient ε is uniquely determined by determining the type of gas and the wavelength of the light source, and since the optical path length L is constant, the ratio between the output intensities P ₁ and P ₀ is an exponential function of the gas concentration c.

In the gas analyzer 100, irradiation light for absorbing NO ₂ gas (or irradiation light for absorbing SO ₂ gas) is irradiated. A part of the irradiation light for absorbing NO ₂ gas (or irradiation light for absorbing SO ₂ gas) at this time is reflected by the optical path determination unit 13 with a known constant reflectance and is incident on the reference light receiving unit 32 as reference light. To do. The output intensity P ₀ by the reference light can be obtained from the signal of the reference light receiving unit 32. Part of the irradiation light for absorbing NO ₂ gas (or irradiation light for absorbing SO ₂ gas) is transmitted through the optical path determination unit 13 with a known constant transmittance, and propagates through the detection space 25 through the light transmission window 23. After being absorbed, the light passes through the light transmission window 24 and enters the transmitted light receiving unit 31 as transmitted light. The output intensity P ₁ by the transmitted light can be obtained from the signal of the transmitted light receiving unit 31. Therefore, the gas concentration c can be obtained from the ratio between the output intensities P ₁ and P ₀ obtained simultaneously. This principle can be applied to both the detection by the irradiation light for NO ₂ gas absorption and the detection by the irradiation light for SO ₂ gas absorption. The detection principle is like this.

The transmitted light receiving unit 31 and the reference light receiving unit 32 are commonly used when measuring the NO ₂ gas concentration, and are commonly used when measuring the SO ₂ gas concentration. Therefore, if the NO ₂ gas absorption light-emitting unit 11 and the SO ₂ gas absorption light-emitting unit 12 emit light at the same time, the light reception signal becomes the sum of the two and cannot be separated.

Therefore, the signal processing / drive control unit 61 controls the NO ₂ gas absorption light-emitting unit 11 and the SO ₂ gas absorption light-emitting unit 12 to emit light alternately without simultaneously emitting light. Further, the measurement and processing of the received light signal are also performed in synchronization with the light emission period, thereby separating the signals.

Such measurement is performed when the ozone generation unit 42 is in an operating state and the gas adjustment unit 41 is in an oxidized output, and when the ozone generation unit 42 is in a non-operational state and the gas adjustment unit 41 is in a normal output. Is called. Therefore, such a gas analyzer 100 is
(A) Analysis with irradiation light for absorbing NO ₂ gas at the time of oxidation output,
(B) Analysis with irradiation light for SO ₂ gas absorption at the time of oxidation output,
(C) Analysis with irradiation light for absorbing NO ₂ gas at normal output,
(D) Analysis with irradiation light for absorbing SO ₂ gas at normal output,
Four types of analysis are possible. Among these, the gas concentration is calculated by analysis of (a), (b), and (c).

Then, NO contained by the gas analyzer 100 in the sample gas _{G S,} the method for measuring the gas concentration of the three components of NO 2, SO ₂ gas will be described.
As the measurement, the above-described analyzes (a), (b), and (c) are performed, and the gas concentrations of the three components NO, NO ₂ , and SO ₂ are calculated using the obtained gas concentrations. Hereinafter, description will be made separately for each output.

First, description will be made on the assumption that (a) analysis is performed using irradiation light for absorbing NO ₂ gas during oxidation output. This is a measurement after the ozone generating section 42 is in an operating state and the gas adjusting section 41 is oxidized and output. At this time, the NO ₂ gas concentration c ₄ is obtained.

The ozone generator 42 is in an operating state. At this time, ozone generator 42 generates air, the instrument air or O ₂ gas contained in the raw material gas G _0, such as oxygen gas, O ₃ gas (oxygen gas) (ozone). Although the generation amount of O ₃ gas can be determined as appropriate, it is supplied in excess of at least the maximum amount in the measured concentration range of NO gas. From the ozone generator 42 to the gas mixing unit 43 supplies the raw material gas _{G O} containing _{O 3} gas sufficiently.

And the raw material gas G _O and the sample gas G _S containing O ₃ gas sufficiently is mixed in the gas mixing portion 43. Here, causing all of the NO gas in the sample gas G _S, and a part of the O ₃ gas, but the chemical reactions described below.

[Chemical 1]
NO + O ₃ → NO ₂ + O ₂ ... Chemical reaction formula (1)

O ₃ gas amount supplied from the ozone generator 42 is, because it is excessive relative to NO gas amount in the sample gas G _S, NO gas in the sample gas G _S is according to the chemical reaction formula (1), All are converted to NO ₂ gas.

Moreover, excess O ₃ gas not used in the chemical reaction formula (1), the sample gas G _S portion of the NO ₂ gas contained than the original in, and, according to the chemical reaction formula (1) The following chemical reaction occurs with a part of the generated NO ₂ gas.

[Chemical formula 2]
2NO ₂ + O ₃ → N ₂ O ₅ + O ₂ ... Chemical reaction formula (2)

The SO ₂ gas and the O ₃ gas do not cause a chemical reaction.

Accordingly, the gas mixing unit 43, and converted all NO gas in the sample gas _{G S} is the NO ₂ gas. In addition, some of the NO ₂ gas in the sample gas _{G S,} and, in some NO ₂ gas produced by a chemical reaction formula (1) is converted to _N 2 _{O 5} gas, further excess _{O 3} gas one The SO ₂ gas remains unreacted. From the gas mixing unit 43, such NO ₂ gas, N ₂ O ₅ gas, surplus O ₃ gas, surplus raw material gas _GO, and surplus sample gas G _S flow out to the gas heating unit 44.

The gas heating unit 44 heats the above gas, but particularly N ₂ O ₅ gas and surplus O ₃ gas cause a thermal decomposition reaction represented by the following chemical reaction formulas (3) and (4) by heating. .

[Chemical formula 3]
2N ₂ O ₅ → 4NO ₂ + O ₂ ... Chemical reaction formula (3)

[Chemical formula 4]
2O ₃ → 3O ₂ ... Chemical reaction formula (4)

That is, N ₂ O ₅ gas which is a by-product generated in the gas mixing unit 43 is thermally decomposed into NO ₂ gas, and the remaining O ₃ gas is thermally decomposed into oxygen. The SO ₂ gas remains unreacted.

The results of these chemical reactions and thermal decomposition reaction, as the state of the gas contained in the heating gas flowing through the gas flow cell 21, NO gas contained in the sample gas G _S is all converted to NO ₂ gas, sample gas nO ₂ gas contained in the G _S, SO ₂ gas is intact, _{O 3} gas is in a state not included.

In other words, the gas concentration of NO ₂ gas after the chemical reaction and thermal decomposition reaction is the sum of the gas concentration and the gas concentration of the original NO ₂ gas of the original NO gas contained in the sample gas G _S. Further, since the raw material gas _{G O} for producing _{O 3} gas is mixed in the gas mixing portion 43, the flow mixing ratio of NO ₂ gas, the concentration of SO ₂ gas is the raw material gas _{G O} and the sample gas _{G S} Depending on the dilution. As described above, the gas adjustment unit 41 outputs the measurement target gas that is the nitrogen monoxide gas (NO gas) contained in the sample gas after being oxidized by ozone and reacted with the nitrogen dioxide gas (NO ₂ ). Output. Such a measurement target gas is introduced into the gas distribution cell 21.

Next, calculation of the NO ₂ gas concentration c ₄ of the gas analyzer 100 at the time of oxidation output will be described. At the time of measuring the NO ₂ gas concentration, only the NO ₂ gas absorption light emitting unit 11 emits light. The irradiation light for absorbing NO ₂ gas from the light emitting unit 11 for absorbing NO ₂ gas is reflected by the optical path determining unit 13 with a known constant reflectance and is incident on the reference light receiving unit 32. Therefore, the output intensity P ₀ can be obtained from the light intensity signal of the reference light receiving unit 32.

Further, NO ₂ irradiation light gas absorption incident on the detection space 25 of the passes through the optical path determination unit 13 light transmission window 23 a gas flow cell 21 through, while propagating the detection space 25, absorption by NO ₂ gas Is done. Such absorbed light for absorbing NO ₂ gas passes through the light transmission window 24 and enters the transmitted light receiving unit 31. Therefore, the output intensity P ₁ can be obtained from the light intensity signal of the transmitted light receiving unit 31.

By using the transmitted light receiving unit 31 and the reference light receiving unit 32 as the light receiving elements in this way, not only can the concentration be measured, but also the output of the NO ₂ gas absorbing light emitting unit 11 varies due to various factors. Also, there is an effect that an error in density measurement can be reduced by calculating the ratio of the two received light signals.

Light intensity signals from the transmitted light receiving unit 31 and the reference light receiving unit 32 are transmitted to the signal processing / drive control unit 61. The signal processing / drive control unit 61 calculates the NO ₂ gas concentration c ₄ ′ before the flow mixture ratio correction in the gas flow cell 21 based on the above mathematical formula 1, and further calculates the flow mixture ratio in the gas mixer 43. by multiplying, calculating the NO ₂ gas concentration _{c 4} contained in the sample gas _{G S.}

Next, calculation of the SO ₂ gas concentration c ₃ by the gas analyzer 100 will be described. This is (b) analysis with irradiation light for absorbing SO ₂ gas at the time of oxidation output. In the oxidation output measurement object gas containing excess sample gas G _S containing NO ₂ gas, excess raw material gas G _O and SO ₂ gas as described above it is introduced into the gas flow cell 21.

At the time of measuring the SO ₂ gas concentration, only the light emitting unit 12 for absorbing SO ₂ gas emits light. The irradiation light for absorbing SO ₂ gas from the light emitting unit 12 for absorbing SO ₂ gas is reflected by the optical path determining unit 13 with a known constant reflectance and is incident on the reference light receiving unit 32. Therefore, the output intensity P ₀ can be obtained from the light intensity signal of the reference light receiving unit 32.

In addition, the SO ₂ gas absorption irradiation light that has passed through the optical path determination unit 13 and has entered the detection space 25 in the gas flow cell 21 through the light transmission window 23 propagates through the detection space 25, while the SO ₂ gas and NO NO. Absorbed by _two gases. Such absorbed light for absorbing SO ₂ gas passes through the light transmission window 24 and enters the transmitted light receiving unit 31. Therefore, the output intensity P ₁ can be obtained from the signal of the transmitted light receiving unit 31. However, since the output intensity P ₁ includes absorption due to NO ₂ gas, if the SO ₂ gas concentration before concentration correction calculated from P ₀ and P ₁ is c ₃ ″, c ₃ ″ The processing / drive control unit 61 needs the following density correction processing. That is, at the time of calibration by the flow of each of the zero gas G _ZERO and the NO ₂ span gas G _SPAN , the SO ₂ gas absorption light emitting unit 12 is turned on, and NO ₂ based on the decrease in light intensity from the output intensities P ₀ and P _1. The concentration correction coefficient α of the light reception intensity by the span gas is calculated. However, it is assumed that always the raw material gas G ₀ is distributed mixture even during calibration. And α of the flow rate mixing ratio is calculated in real time uncorrected NO ₂ gas concentration _{c 4} 'and, since the density before correction SO ₂ gas concentration _{c 3} ", the flow mixing ratio correction before SO ₂ gas concentration _{c 3'} Is calculated by density correction processing according to the following equation.

[Equation 2]
c ₃ ′ = c ₃ ″ −α × c ₄ ′

By using the transmitted light receiving unit 31 and the reference light receiving unit 32 as the light receiving elements in this way, not only can the concentration be measured, but also the output of the SO ₂ gas absorbing light emitting unit 12 varies due to various factors. Also, there is an effect that an error in density measurement can be reduced by calculating the ratio of the two received light signals.

Output signals from the transmitted light receiving unit 31 and the reference light receiving unit 32 are transmitted to the signal processing / drive control unit 61. The signal processing / drive control unit 61 calculates the output intensities P ₀ and P ₁ , and based on the formulas 1 and 2, the NO ₂ gas concentration c ₄ ′ before the flow mixture ratio correction and the SO ₂ gas before the flow mixture ratio correction. to calculate the concentration _{c 3} ', further by multiplying the flow mixing ratio of a gas mixing section 43, calculates the NO ₂ gas concentration _{c 4} and SO ₂ gas concentration _{c 3} contained in the sample gas _{G S.}

Subsequently, the measurement is performed after the ozone generating unit 42 is in an inoperative state and the gas adjusting unit 41 is normally output. At this time, the NO ₂ gas concentration c ₂ is obtained. This is (c) analysis with irradiation light for absorbing NO ₂ gas at normal output.

The ozone generator 42 is in an inoperative state. At this time, the raw material gas G _O is passes through the ozone generator 42 as described above, is mixed with the sample gas G _S in the gas mixing portion 43. O ₃ because the gas does not exist without a chemical reaction occurs, and the raw material gas G _O and the sample gas G _S-free reaction as it flows out from the gas mixing unit 43. Also, flowing out of the chemical reaction does not occur in the non-reactive material gas G _O and the sample gas G _S and is directly gas heating unit 44 even in the gas heating unit 44. Gas conditioning unit 41 performs a normal output that outputs the sample gas G _S and the raw material gas G _O unresponsive as a measurement target gas.

Since there is no O ₃ gas in this way, the chemical reaction formulas represented by the chemical reaction formula (1) and the chemical reaction formula (2) do not occur in the gas mixing unit 43. In addition, since the gas heating unit 44 does not contain N ₂ O ₅ gas or O ₃ gas, the chemical reaction represented by the chemical reaction formula (3) and the chemical reaction formula (4) does not occur.

As a result, the state of the gas contained in the sample gas flowing through the gas circulation cell 21 is the state in which all of the NO gas, NO ₂ gas, and SO ₂ gas contained in the sample gas are intact. Further, since the source gas is mixed in the gas mixing unit 43, the concentrations of NO gas, NO ₂ gas, and SO ₂ gas are diluted according to the flow rate mixing ratio of the source gas and the sample gas. And such feed gas G _O and the sample gas G _S is introduced into the gas flow cell 21.

The detection of the gas concentration itself is obtained in the same manner as when the ozone generator 42 is in operation (at the time of oxidation output). The signal processing / drive control unit 61 calculates the NO ₂ gas concentration in the gas distribution cell 21 based on the above mathematical formula 1, and further multiplies the flow rate mixing ratio in the gas mixing unit 43 to obtain the sample gas G _S. The NO ₂ gas concentration c ₂ contained in is calculated.

Next, the signal processing / drive control unit 61 calculates the NO gas concentration c ₁ in the sample gas from the combination of the gas concentration during operation of the ozone generation unit 42 and the gas concentration during non-operation.
As explained earlier,
(A) NO ₂ gas concentration c ₄ calculated by analysis with irradiation light for absorbing NO ₂ gas during oxidation output,
(B) NO ₂ gas concentration c ₄ and SO ₂ gas concentration c ₃ calculated by analysis with irradiation light for absorbing O ₃ gas during oxidation output
(C) NO ₂ gas concentration c ₂ calculated by analysis with irradiation light for absorbing NO ₂ gas at normal output,
Has been measured. Here, since the NO ₂ gas concentration c ₄ is determined, the SO ₂ gas concentration c ₃ is also determined.

Further, since the NO ₂ gas concentration c ₄ in the oxidation output state is the sum of the NO gas concentration c ₁ and the NO ₂ gas concentration c ₂ at the normal output, it is possible to calculate c ₁ from the following equation. it can.

[Equation 3]
c ₁ = c ₄ -c ₂

The signal processing / drive control unit 61 calculates the NO gas concentration c ₁ based on the NO ₂ gas concentration c ₄ at the time of oxidation output and the NO ₂ gas concentration c ₂ at the time of normal output.

In this manner, the NO gas concentration c ₁ , the NO ₂ gas concentration c ₄ , and the SO ₂ gas concentration c ₃ can be measured. That is, while the signal processing / drive control unit 61 switches the operation / non-operation of the ozone generation unit 42 in time, NO ₂ (including NO content), SO ₂ at the time of oxidation output during operation of the ozone generation unit 42 The gas concentration is measured, and the NO ₂ (not including NO content) gas concentration is measured at the normal output when the ozone generator 42 is not operating. The NO gas concentration is determined from the NO ₂ gas concentration at the oxidation output. The NO gas concentration can be obtained by subtracting the NO ₂ gas concentration during normal output.

Also, zero gas G _ZERO or span gas G _SPAN can be used for gas concentration calibration. _Zero gas G _ZERO is a gas, for example, nitrogen gas, in which the NO ₂ gas absorption light-emitting unit 11 and the SO ₂ gas absorption light-emitting unit 12 do not absorb light. The span gas G _SPAN is a gas calibrated with the maximum concentration value in a desired measurement range, and NO, NO ₂ , and SO ₂ are used as gas types.

Stopping the supply of the sample gas _{G S,} followed by performing the supply of the zero gas _{G ZERO} calibrated by measuring the light signal at the zero gas _{G ZERO} distribution, or at the time span _{G SPAN} flow by performing the supply of the span gas _{G SPAN} Calibration can be performed by measuring the absorbed light-receiving signal. Although this calibration can be performed at any time, it is performed when it is assumed that the gas concentration indicating value fluctuates due to aging of the component parts, and an accurate value is indicated.

In the above, (d) the analysis by the irradiation light for SO ₂ gas absorption at the normal output is not used, but (b) instead of the analysis by the irradiation light for SO ₂ gas absorption at the oxidation output, this ( The analysis of (a), (c), (d) can also be performed using the analysis of d). In that case, the measurement procedure may be the same as the measurement procedure at the time of oxidation output. This is because SO ₂ is not oxidized by ozone and is not decomposed by the heating unit, so that there is no change in concentration both during oxidation output and during normal output. That is, the NO ₂ gas concentration c ₄ at the oxidation output is calculated by (a), (c) the NO ₂ gas concentration c ₂ calculated by the analysis by the irradiation light for absorbing NO ₂ gas at the normal output is calculated, and (d ) To calculate the NO ₂ gas concentration c ₂ and the SO ₂ gas concentration c ₃ . Since the SO ₂ gas concentration c ₃ is not oxidized by ozone, it is the same as the SO ₂ gas concentration c ₃ at the time of oxidation output. In this way, the SO ₂ gas concentration c ₃ may be calculated. The present invention can also be implemented by analysis based on these (a), (c), and (d).

The analysis according to the above (a) NO ₂ gas absorption for the irradiation light at the time of oxidation output, and, by performing only analysis by NO ₂ gas absorption for the irradiation light at the time of (c) normal output, the SO ₂ gas concentration Without obtaining, only the NO gas concentration c ₁ and the NO ₂ gas concentration c ₂ may be calculated.
The gas analyzer 100 performs the analysis in this way.

Next , the first embodiment will be described with reference to FIG. As shown in FIG. 2, the gas analyzer 200 includes an NO ₂ gas absorption light emitting unit 11, an SO ₂ gas absorption light emitting unit 12, an optical path determination unit 13, a gas flow cell 21, a transmitted light receiving unit 31, and a reference light receiving unit. Unit 32, gas adjustment unit 41, gas suction unit 51, signal processing / drive control unit 61, and correction unit 71.

Compared to the basic form of the gas analyzer 100 shown in FIG. 1, in the form of FIG. 2, to differences that particular correcting unit 71 is added. It is omitted here as well as focuses on correction unit 71 and its operation, the description overlapping with with the same number of other configurations.

The correction unit 71 is connected to the reference light receiving unit 32, the signal processing / drive control unit 61, the NO ₂ gas absorption light emitting unit 11, and the SO ₂ gas absorption light emitting unit 12. Based on this, it has a function of correcting the current for driving the NO ₂ gas absorption light emitting unit 11 and the SO ₂ gas absorption light emitting unit 12.

Reference-light receiving part 32 by receiving the reference light by NO ₂ gas absorption for the irradiation light from the NO ₂ gas absorption for the light emitting unit 11 and outputs the light amount intensity signal. Based on the intensity signal, the correction unit 71 corrects the drive signal, which is a light emitting diode drive current, so that the output intensity is constant, and then outputs the correction signal to the NO ₂ gas absorption light emission unit 11. For example, the light intensity signal of the irradiation light for NO ₂ gas absorption is first stored in the memory unit and controlled to be the same as the initial light intensity signal.
Similarly, the reference light receiving unit 32 by receiving the reference light by SO ₂ gas absorption for the irradiation light from the SO ₂ gas absorption for the light emitting unit 12 and outputs the intensity signal. Based on the intensity signal, the correction unit 71 corrects the drive signal, which is a light-emitting diode drive current, so that the output intensity is constant, and then outputs the correction signal to the SO ₂ gas absorption light-emitting unit 12. For example, the light intensity signal of the irradiation light for SO ₂ gas absorption is first stored in the memory unit and controlled so as to be the same as the initial light intensity signal.

By adopting a configuration in which such a correction unit 71 is added, fluctuations in irradiation light output from the NO ₂ gas absorption light emitting unit 11 and the SO ₂ gas absorption light emitting unit 12 are reduced, and detection accuracy is improved. Can be made.

Next, a description will be given of a second embodiment of the present invention while referring to Figure 3. In addition to the configuration of the gas analyzers 100 and 200 described above , FIG. 3 further includes a lens 14 on the optical axis of the NO ₂ gas absorption light emitting unit 11, and the optical axis of the SO ₂ gas absorption light emitting unit 12. Ru Tei includes a lens 15 thereon.

In general, light emitted from a light emitting diode is diffused with low directivity. Therefore, there is a problem that the ratio of the light that enters the detection space 25 of the gas flow cell 21 through the light transmission window 23 decreases. Therefore, the directivity of the irradiation light irradiated while diffusing from the NO ₂ gas absorbing light emitting portion 11 and the SO ₂ gas absorbing light emitting portion 12 is enhanced by the lens 14 and the lens 15. Thereby, the ratio of the light which enters into the detection space 25 of the gas distribution cell 21 through the light transmission window 23 is increased. As a result, there is an effect that the signal intensity is increased, and consequently the accuracy and stability of the gas concentration measurement are improved.

Note that the NO ₂ gas absorption light-emitting unit 11 and the lens 14 may be integrally configured by modularization, and the SO ₂ gas absorption light-emitting unit 12 and the lens 15 may be integrated by modularization.

Next, a description will be given of a third embodiment of the present invention while referring to Figure 4. As shown in FIG. 4, a light emitting unit 16 is arranged in place of the NO ₂ gas absorbing light emitting unit 11 and the SO ₂ gas absorbing light emitting unit 12. The light emitting unit 16, NO ₂ light-emitting diode array der that is integrated in proximity of the gas absorption for the light emitting unit 11 and the SO ₂ gas absorption for the light emitting portion 12 Ri, NO ₂ gas absorption emitting portion contact and SO ₂ gas absorption lens 17 on the optical axis of the use-emitting portion is disposed.

As a result, the optical axes of the NO ₂ gas absorbing light emitting portion 11 and the SO ₂ gas absorbing light emitting portion 12 are close to each other, so that one lens 17 for increasing directivity is sufficient. Further, since the optical axes are close to each other, the incident efficiency to the reference light receiving unit 32 is also improved. As a result, there is an effect that the signal intensity is increased, and consequently the accuracy and stability of the gas concentration measurement are improved.

Next, it will be described with reference to FIG. 5, a fourth embodiment of the present invention. In FIG. 5, in addition to the configuration of the gas analyzer of each form described above, a lens 18 is further disposed between the light transmission window 24 and the transmitted light receiving unit 21. The lens 18 condenses the NO ₂ gas absorption laser light and the SO ₂ gas absorption laser light that have been transmitted through the light transmission window 24 and efficiently enters the transmitted light receiving portion 31. As a result, there is an effect that the signal intensity is increased, and consequently the accuracy and stability of the gas concentration measurement are improved.

  In addition, the light transmission window 24 and the lens 18 may be integrally configured by modularization. Furthermore, the light transmission window 24 itself may be a convex lens 18 that is light transmissive and has a light collecting effect, and the gas flow cell 21 may be configured by fixing the lens 18 to the tube 22.

Next, a fifth embodiment of the present invention will be described with reference to FIG. This embodiment is such that with a light emitting and receiving unit 19 that is integrated while close to NO ₂ gas absorption for the light emitting unit 11, SO ₂ gas absorption for the light emitting unit 12 and the transmitted light receiving unit 31. Further, the light transmission window 24 of the gas flow cell 21 is replaced with a reflection unit 28, and the transmitted light receiving unit 31 is arranged at a position where the return path light is transmitted by the optical path determination unit 13.

According to this, the lens 17 condenses the irradiation light incident on the transmitted light receiving unit 31 and the function of increasing the directivity of the irradiation light from the NO ₂ gas absorption light emitting unit 11 and the SO ₂ gas absorption light emitting unit 12. It will have the function to do. Further, since the optical path length with light absorption by gas is doubled, it is possible to expect the effect of improving the light absorption signal and improving the accuracy and stability of gas concentration measurement.

Next, a sixth embodiment of the present invention will be described. This embodiment is intended to modify the above optical path determining section 13 in the gas analyzer described with reference to FIGS. In the embodiment described above, a half mirror is assumed. However, the optical path determining unit 13, a mechanical mirror moves the mirror having a mirror surface on which light is totally reflected in the mechanical or, by electrical switching and a mirror and a transparent be those employing mirrors alternating Also good.

In this case, the reference light and the transmitted light cannot be received simultaneously. Therefore, the device configuration of the gas analyzer is changed. That is, the transmitted light receiving unit 31 and the reference light receiving unit 32 (or the signal processing / drive control unit 61) include a storage unit that stores a light intensity signal. In addition, the signal processing / drive control unit 61 controls the mirror of the optical path determination unit 13 so that light can be selected to enter the transmitted light receiving unit 31 or the reference light receiving unit 32. When detecting the reference light of the NO ₂ gas absorption irradiation light, the optical path determination unit 13 is controlled so that the reference light is incident on the reference light receiving unit 32, and then the light intensity signal P ₀ of the reference light is used as a reference. Stored in the storage unit of the light receiving unit 32 (or the signal processing / drive control unit 61). Subsequently, when detecting the transmitted light of the irradiation light for NO ₂ gas absorption, the light intensity determination signal P ₁ of the transmitted light is obtained after controlling the optical path determination unit 13 so that the transmitted light is incident on the transmitted light receiving unit 31. The storage unit of the transmitted light receiving unit 31 (or the signal processing / drive control unit 61) stores it. And separately acquired separately the amount of light intensity signal P ₀ and the light amount intensity signal P ₁ and the time of the transmitted light of the reference light also detected by SO ₂ gas absorption for the irradiation light. Later, the light intensity intensity signals P ₀ and P ₁ of the irradiation light for absorbing NO ₂ gas and the irradiation light for absorbing SO ₂ gas are used to calculate based on the above formulas 1 and 2. In such a gas analyzer, the light intensity of the reference light and the transmitted light is doubled compared to the half mirror, so that the detection capability can be enhanced.

Next, a seventh embodiment of the present invention will be described with reference to FIG. In this embodiment , the light transmission window 24 of the gas flow cell 21 is replaced with a reflection section 28, and the transmitted light receiving section 31 is disposed at a position where the return path light is transmitted by the optical path determination section 13.

In this configuration, forward light, which is irradiation light emitted from the NO ₂ gas absorption light-emitting unit 11 and the SO ₂ gas absorption light-emitting unit 12, passes through the light transmission window 23 and propagates in the detection space 25 of the tube 22. Then, the light is reflected by the reflecting portion 28 and becomes return path light. The reflected return light propagates in the detection space 25 of the tube 22 in the opposite direction, exits from the light transmission window 23, is reflected by the optical path determination unit 13, and enters the transmitted light receiving unit 31.

According to this structure, FIG. 1, since in comparison with FIG optical path length with a light absorption by the gas expands to double, it can be expected to improve the accuracy and stability of the gas concentration measurement.

Will now be described an eighth embodiment of the present invention while referring to Figure 8. FIG. 8 is a duty ratio-allowable current characteristic diagram of a light emitting diode or a laser diode. In this embodiment , the measurement accuracy of the gas analyzer of each embodiment described above is further improved.

First, the principle will be described. As shown in FIG. 8, the allowable current of a light emitting diode or a laser diode is characterized in that, generally, the smaller the duty ratio and the shorter the output period, the larger the current value can be secured. Therefore, the drive currents of the NO ₂ gas absorption light emitting unit 11 and the SO ₂ gas absorption light emitting unit 12 are changed from a large duty ratio as shown in FIG. 9 to a small duty ratio as shown in FIG. Shorter). At this time, the output time is shortened as shown in FIG. 10, but the drive current value can be increased. Therefore, the output intensity of the irradiation light can be increased to ensure a high signal level, the signal level against noise is relatively high, and a stable gas concentration value can be calculated.

Furthermore, since the light emission time of the light emitting diode 11 for absorbing NO ₂ gas, which is a light emitting diode or laser diode, and the light emitting portion 12 for absorbing SO ₂ gas, which is a light emitting diode, can be shortened, deterioration due to heat or the like is suppressed. Thus, it is possible to maintain a long lifetime as compared with continuous light emission.

Such a gas analyzer of the present invention comprises two components, nitrogen monoxide gas (NO gas) and nitrogen dioxide gas (NO ₂ gas), as well as nitrogen monoxide gas (NO gas) and nitrogen dioxide gas (NO ₂ gas). ) And sulfur dioxide gas (SO ₂ ), and is optimal for analysis of combustion exhaust gas such as boilers and garbage incineration. In addition, gas analysis for steel [blast furnace, converter, heat treatment furnace, sintering (pellet equipment), coke oven], fruit and vegetable storage and ripening, biochemistry (microorganism) [fermentation], air pollution [incinerator, flue gas desulfurization / Denitration], exhaust gas (removal tester) of internal combustion engines such as automobiles and ships, disaster prevention [explosive gas detection, toxic gas detection, new building material combustion gas analysis], plant growth, chemical analysis [oil refinery plant, petrochemical Plants, gas generation plants], environmental [landing concentration, concentration in tunnels, parking lots, building management], and analytical instruments for various physics and chemistry experiments.

100,200: Gas analyzer 11: NO ₂ gas absorption for the light emitting portion 12: SO ₂ gas absorption for the light emitting unit 13: optical path determining section 14: Lens 15: Lens 16: light-emitting unit 17: Lens 18: Lens 19: light receiving and emitting Unit 21: Gas distribution cell 22: Tube 23, 24: Light transmission window 25: Detection space 26: Gas inlet 27: Gas outlet 31: Transmitted light receiving unit 32: Reference light receiving unit 41: Gas adjusting unit 42: Ozone Generation unit 43: Gas mixing unit 44: Gas heating unit 51: Gas suction unit 61: Signal processing / drive control unit 71: Correction unit

Claims (7)

An oxidation output state in which the sample gas is mixed with ozone gas to cause an oxidation reaction and then heated and output as the first measurement target gas; and a normal output state in which the sample gas is output as the second measurement target gas without any reaction. a switching Ru gas conditioning unit,
A light emitting part for absorbing NO ₂ gas that irradiates irradiation light for absorbing NO ₂ gas having a wavelength of 320 nm to 600 nm in which nitrogen dioxide gas (NO ₂ gas) absorbs;
The first, a detection space in which the second measurement target gas flows, the light transmission window for entering the NO ₂ gas absorption for the irradiation light to the detection space, the gas flow cell having,
A transmitted light receiving unit that receives the irradiation light for absorbing the NO ₂ gas transmitted through the detection space from the light transmission window;
The gas adjusting unit and the NO ₂ gas absorption light emitting unit are controlled to irradiate the NO ₂ gas absorption irradiation light in a state where the first and second measurement target gases are respectively circulated through the gas flow cell. A drive control unit;
A reference light receiving unit that receives the irradiation light for absorbing NO ₂ gas as reference light ;
An optical path for allowing the irradiation light for NO ₂ gas absorption to pass through the detection space through the light transmission window and reach the transmitted light receiving part; and an optical path for reaching the reference light receiving part without passing through the detection space; And an optical path determination unit that allows the light to pass separately.
A correction unit that controls the drive current of the light emitting unit for absorbing NO ₂ gas based on the amount of reference light received by the reference light receiving unit ;
Calculating a gas concentration of nitrogen dioxide gas in the sample gas from a calculated value according to the amount of light received by the transmitted light receiving unit when the first measurement object gas is irradiated with the irradiation light for absorbing NO ₂ gas, The second measurement target gas is irradiated with the NO ₂ gas absorption irradiation light from a calculated value corresponding to the amount of light received by the transmitted light receiving unit when the first measurement target gas is irradiated with the NO ₂ gas absorption irradiation light. A signal processing unit that calculates a gas concentration of nitric oxide gas (NO gas) in the sample gas by reducing a calculated value according to the amount of light received by the transmitted light receiving unit when
A gas analyzer comprising: An oxidation output state in which the sample gas is mixed with ozone gas to cause an oxidation reaction and then heated and output as the first measurement target gas; and a normal output state in which the sample gas is output as the second measurement target gas without any reaction. a switching Ru gas conditioning unit,
A light emitting part for absorbing NO ₂ gas that irradiates irradiation light for absorbing NO ₂ gas having a wavelength of 320 nm to 600 nm in which nitrogen dioxide gas (NO ₂ gas) absorbs;
A SO ₂ gas absorption light emitting unit for irradiating SO ₂ gas absorption irradiation light having a wavelength of 250 nm to 320 nm in which sulfur dioxide gas (SO ₂ gas) and nitrogen dioxide gas absorb;
The first, a detection space in which the second measurement target gas flows, gas flow cell having a light transmission window for the NO ₂ gas absorption irradiation light and the SO ₂ gas absorption for the irradiation light is incident on the detection space When,
A transmitted light receiving unit that receives the irradiation light for absorbing NO ₂ gas and the irradiation light for absorbing SO ₂ gas transmitted through the detection space from the light transmission window;
The NO ₂ gas absorption irradiation light and the SO ₂ gas absorption irradiation light are sequentially irradiated in a state where the first measurement target gas is circulated through the gas distribution cell, and the second measurement target gas is supplied to the gas distribution cell. A drive control unit that controls the gas adjusting unit, the NO ₂ gas absorbing light emitting unit, and the SO ₂ gas absorbing light emitting unit so as to irradiate the irradiation light for NO ₂ gas absorbing in a state of being distributed to
A reference light receiving unit that receives the irradiation light for absorbing NO ₂ gas and the irradiation light for absorbing SO ₂ gas as reference light;
The NO ₂ gas absorption irradiation light and the SO ₂ gas absorption irradiation light are transmitted through the detection space through the light transmission window and reach the transmitted light receiving unit and the detection space without passing through the detection space. An optical path determination unit that allows the optical path to reach the reference light receiving unit and separates the optical path;
A correction unit that controls driving currents of the NO ₂ gas absorption light-emitting unit and the SO ₂ gas absorption light-emitting unit based on the amount of reference light received by the reference light receiving unit ;
Calculating a gas concentration of nitrogen dioxide gas in the sample gas from a calculated value according to the amount of light received by the transmitted light receiving unit when the first measurement object gas is irradiated with the irradiation light for absorbing NO ₂ gas, the transmitted light when irradiated with the NO ₂ gas absorption for the irradiation light in the second measurement target gas calculated value corresponding to the received light amount when irradiated with the NO ₂ gas absorption for the irradiation light to the first measurement target gas calculating a gas concentration of nitric oxide gas in front Symbol sample gas by subtracting the calculated value according to the amount of light received by the light receiving portion (NO gas), the SO ₂ gas absorption for the irradiation light in the first measurement target gas sulfur dioxide gas in the sample gas by subtracting the calculated value corresponding to the received light amount when the from the calculated value corresponding to the received light amount is irradiated with the NO ₂ gas absorption for the irradiation light in the first measurement target gas when irradiated A signal processing unit for calculating the gas concentration of
A gas analyzer comprising: An oxidation output state in which the sample gas is mixed with ozone gas to cause an oxidation reaction and then heated and output as the first measurement target gas; and a normal output state in which the sample gas is output as the second measurement target gas without any reaction. a switching Ru gas conditioning unit,
A light emitting part for absorbing NO ₂ gas that irradiates irradiation light for absorbing NO ₂ gas having a wavelength of 320 nm to 600 nm in which nitrogen dioxide gas (NO ₂ gas) absorbs;
A SO ₂ gas absorption light emitting unit for irradiating SO ₂ gas absorption irradiation light having a wavelength of 250 nm to 320 nm in which sulfur dioxide gas (SO ₂ gas) and nitrogen dioxide gas absorb;
The first, a detection space in which the second measurement target gas flows, gas flow cell having a light transmission window for the NO ₂ gas absorption irradiation light and the SO ₂ gas absorption for the irradiation light is incident on the detection space When,
A transmitted light receiving unit that receives the irradiation light for absorbing NO ₂ gas and the irradiation light for absorbing SO ₂ gas transmitted through the detection space from the light transmission window;
The NO ₂ gas in a state where the first measurement target gas is irradiated with the NO ₂ gas absorption for the irradiation light in the state of being distributed in the gas flow cell, was passed through the second measurement target gas into the gas flow cell A drive control unit for controlling the gas adjusting unit, the NO ₂ gas absorbing light emitting unit, and the SO ₂ gas absorbing light emitting unit so as to sequentially emit the absorbing light for absorbing light and the irradiated light for absorbing SO ₂ gas;
A reference light receiving unit that receives the irradiation light for absorbing NO ₂ gas and the irradiation light for absorbing SO ₂ gas as reference light;
The NO ₂ gas absorption irradiation light and the SO ₂ gas absorption irradiation light are transmitted through the detection space through the light transmission window and reach the transmitted light receiving unit and the detection space without passing through the detection space. An optical path determination unit that allows the optical path to reach the reference light receiving unit and separates the optical path;
A correction unit that controls driving currents of the NO ₂ gas absorption light-emitting unit and the SO ₂ gas absorption light-emitting unit based on the amount of reference light received by the reference light receiving unit ;
Calculating a gas concentration of nitrogen dioxide gas in the sample gas from a calculated value according to the amount of light received by the transmitted light receiving unit when the first measurement object gas is irradiated with the irradiation light for absorbing NO ₂ gas, The second measurement target gas is irradiated with the NO ₂ gas absorption irradiation light from a calculated value corresponding to the amount of light received by the transmitted light receiving unit when the first measurement target gas is irradiated with the NO ₂ gas absorption irradiation light. The gas concentration of the nitric oxide gas (NO gas) in the sample gas is calculated by subtracting the calculated value obtained according to the amount of received light at the time, and the SO ₂ gas absorption irradiation light is applied to the second measurement object gas. the subtracting the calculated value corresponding to the received light amount when the irradiated from the calculated value corresponding to the received light amount of the transmitted light receiving unit of the NO ₂ gas absorption for the irradiation light in the first measurement target gas when irradiated the gas concentration of sulfur dioxide gas in the sample gas A signal processing unit for calculating a,
A gas analyzer comprising: In the gas analyzer according to any one of claims 1 to 3,
The gas adjusting unit is
When there is no command from the drive control unit, a raw material gas is output, and when there is the command, an ozone generation unit that generates ozone gas from the raw material gas and outputs a raw material gas containing ozone gas,
A gas mixing section for mixing and outputting the sample gas and the source gas;
A gas heating unit that heats the mixed gas from the gas mixing unit and outputs the mixed gas as the first and second measurement target gases;
A gas analyzer comprising: In the gas analyzer according to any one of claims 1 to 3 ,
Before SL signal processing unit, the gas analyzer and calculates the gas concentration on the basis of the ratio between the received light amount of the transmitted light by the transmitted light receiving unit and the light receiving amount of the reference light due to the reference light receiving unit. The gas analyzer according to claim 1, wherein
The drive control unit, said by the light emitting diode or driving current output period than the stop period laser diode in which the output of the NO ₂ gas absorption for the light emitting portion and a stop a pulse alternately performed a short duty ratio NO ₂ A gas analyzer characterized by driving a light-absorbing light emitting unit . The gas analyzer according to claim 2 or claim 3,
The drive control unit, said by the light emitting diode or driving current output period than the stop period laser diode in which the output of the NO ₂ gas absorption for the light emitting portion and a stop a pulse alternately performed a short duty ratio NO ₂ driving the gas absorption emitting portion, wherein the drive current of a light emitting diode wherein the SO ₂ output period than the stop period output and stopping a pulse for performing alternating gas absorption for the light emitting portion is shorter duty ratio SO ₂ A gas analyzer characterized by driving a light-absorbing light emitting unit .

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