JP2000275171A - Atomic absorption analysis method and apparatus of suspended particles in air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly and continuously analyze a component of suspended particles by heating suspended particles in a duct to atomize them and calculating the absorbancy of a component to be analyzed of suspended particles from a change in the intensity of light transmitted through the atomic gas thereof. SOLUTION: The suspended particles in air 8 flowing through a duct 6 are heated by a heating part 5 to be atomized within the duct 6 to become atomic gas 9. The light from a light source 1 enters the duct 6 from an incident part and passes through the atomic gas 9 and receives the atomic absorption due to the atomic gas 9 to enter a light receiving part 3. A measuring part 4 calculates the intensity ratio of the intensity of the light 7 received by the light receiving part 3 and the intensity of light 7 before passed through the atomic gas 9 measured in the incident part 2 to measure a change in the intensity of the light 7 in the light receiving part 3. The quantity of absorption of the light due to the atomic gas 9, that is, the atomic absorbancy due to a component to be analyzed of suspended particles is calculated from the calculated intensity ratio and the amt. of the component to be analyzed is measured from the calculated absorbancy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analysis technique for analyzing the components of suspended particles contained in exhaust gas from a reaction tower, a furnace, or the like, and more particularly, to analyzing the components of suspended particles quickly and continuously. The present invention relates to an atomic absorption spectrometry method and apparatus capable of performing the above.

[0002]

2. Description of the Related Art Exhaust gas from garbage incinerators, iron making furnaces and the like contains suspended particles. By analyzing the chemical composition of the suspended particles, it is possible to provide important information not only to prevent environmental pollution but also to grasp the condition inside the furnace. By monitoring this information quickly and continuously, it is possible to appropriately control the ever-changing reaction state in the furnace.

[0003] In the component analysis of suspended particles contained in a gas,
Generally, suspended particles are once collected by a filter or the like, and the collected particles are taken out and analyzed. However, with such a method, although the analysis accuracy is good, the suspended particles cannot be analyzed quickly and continuously.

On the other hand, as a method for continuously analyzing the gas component in which the components of the suspended particles change every moment, it has been proposed to analyze the components of the suspended particles in the exhaust gas by using an atomic absorption spectrometry. ing. Atomic absorption spectrometry is based on the principle that an analysis sample is atomized into an atomic gas, and light with a wavelength that causes atomic absorption is passed through the atomic gas. From the absorbance of the atomic gas, the atomic concentration in the atomic gas is analyzed. This is for determining the atomic concentration in a sample. More specifically,
The atomic absorption method is to determine the amount or concentration of an analytical component based on the atomic absorption phenomenon according to the following equation (1). A = μCL ··························· (1) (where, A; absorbance (= −log (I / I ₀ )) ,
(I / I ₀ ); light intensity ratio, I: light intensity after light absorption, I ₀ : light intensity before light absorption, μ: extinction coefficient (specific to wavelength), C: amount or concentration of analysis component, L: atomic gas layer The technique of analyzing suspended particles using atomic absorption spectrometry is described in, for example, Japanese Patent Application Laid-Open No. 8-166343. In this document, a part of the gas in the duct is introduced at a constant flow rate into the heat decomposition excitation section through an introduction pipe to atomize the suspended particles in the excitation section, and the suspended particles composed of zinc oxide are analyzed by the atomic absorption analysis method. Is described. Further, in this technique, the heat decomposition excitation section is housed in a decompression container, and the pressure in the decompression container is made lower than the pressure in the duct. In this way, it is described that the gas can be introduced into the heat decomposition excitation section without using a constant flow pump or the like, so that the gas can be transported at a constant flow rate without causing settling or clogging of particles. ing.

[0005] However, when the gas containing suspended particles is actually introduced through the introduction pipe, it is difficult to completely eliminate the sedimentation of the particles in the introduction pipe even in the above technique. In particular, settling of particles increases at the bent portion of the introduction pipe due to engineering restrictions and the like. For this reason, there is a problem that the introduction pipe is closed or the introduction pipe needs to be periodically cleaned during long-term use. Further, when there is a change in the composition or the like depending on the particle size of the suspended particles, the representativeness of the analysis result becomes a problem. Further, when the gas contains a large amount of moisture, there arises a problem that dew condensation occurs in the middle of the introduction tube and the introduction tube is clogged. As described above, even in the above technique, it is difficult to analyze suspended particles quickly and continuously.

As described above, in the prior art, it was difficult to quickly and continuously analyze suspended particles contained in exhaust gas or the like flowing in a duct.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an analysis method capable of rapidly and continuously analyzing components of suspended particles in a gas flowing in a duct. And an apparatus.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made to atomize suspended particles in a gas in a duct by heating to form an atomic gas in the duct by heating.
An atomic absorption spectrometry and an atomic absorption analysis method for causing atomic light to pass through the atomic gas to provide atomic absorption are provided. According to the present invention, the step of introducing the suspended particles sampled from the gas flowing in the duct to the thermal decomposition excitation section through the introduction pipe is omitted, so that occurrence of troubles such as sedimentation of the particles in the introduction pipe can be prevented. it can. Therefore, it is possible to analyze the components of the suspended particles quickly and continuously.

That is, according to the present invention, there is provided an atomic absorption analysis method for analyzing the components of suspended particles in a gas flowing in a duct, wherein at least a part of the suspended particles in the duct is heated to form a gas in the duct. Atomization into an atomic gas, a step of passing light through the atomic gas, and a step of determining the absorbance of the suspended particles by an analytical component from the change in intensity of the atomic gas passing light and measuring the amount of the component Atomic absorption spectrometry is provided.

Further, according to the present invention, there is provided an atomic absorption spectrometer for analyzing the components of suspended particles in a gas flowing in a duct, wherein a light source and at least a part of the suspended particles in the duct are heated. Heating section for atomizing into atomic gas in a duct, light input section for entering light from a light source into the atomic gas, and light receiving section for receiving light from the light input section that has passed through the atomic gas An atomic absorption spectrometer comprising: a measuring unit that measures the absorbance of the suspended particles by an analytical component from a change in the intensity of light received by the light receiving unit and measures the amount of the component.

In the present invention, it is preferable that the light source emits continuous light including absorbed light in which suspended particles are absorbed by an analysis component.

Further, in the present invention, the light source emits light including absorption light that is absorbed by the analysis component of the suspended particles and reference light that is not absorbed by the component, and the measurement unit uses the absorption light received by the light reception unit. It is preferable to determine the absorbance of the component by comparing the intensity ratio between the light and the reference light with the intensity ratio between the absorbed light and the reference light before incidence.

In the present invention, the light source is preferably a tunable laser.

Further, in the present invention, it is preferable that the light source and the light-entering unit, and the light-receiving unit and the measuring unit are respectively connected by optical fibers.

Further, in the present invention, it is preferable that the heating section is disposed in a duct, and the light input section and the light receiving section are each a light transmission window attached to the duct.

Further, in the present invention, the apparatus further comprises an analysis tube provided in the duct, wherein the heating unit disposed in the duct is attached to the analysis tube, and the light-entering unit and the light-receiving unit are each provided with an analysis tube. Preferably, it is a light transmitting window attached to the tube.

Further, in the present invention, it is preferable that the heating section heats the suspended particles in the duct in a reducing atmosphere.

Further, in the present invention, it is preferable that a purge gas is introduced into a surface of the light transmitting window which comes into contact with the gas in the duct.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, the components of the suspended particles in the gas flowing through the duct are analyzed using the atomic absorption analysis method. Further, the concentration of the component in the gas can be determined from the amount of the component of the suspended particles obtained by the analysis.

The duct is, for example, a pipe for exhaust gas attached to a reaction furnace such as a hot metal processing furnace or a tower. Therefore, the gas flowing through the duct includes exhaust gas from these furnaces and towers. The components of the suspended particles in the gas flowing through the duct include, for example, zinc, zinc oxide, and lead.

FIG. 1 is a schematic diagram showing an example of an analyzer for carrying out the present invention. The device according to the present invention includes a light source 1, a light incident unit 2, a light receiving unit 3, a measuring unit 4, and a heating unit 5.

The light 7 from the light source 1 is incident on the duct 6 by the light entrance 2. The light 7 that has passed through the duct 6 enters the light receiving unit 3, and the intensity and the like of the light 7 received by the light receiving unit 3 are measured by the measuring unit 4. Suspended particles contained in the gas 8 flowing in the duct 6 are atomized in the duct by the heating unit 5 to become an atomic gas 9. The light 7 from the light source 1 is
After passing through the atomic gas 9 in the duct 6 and receiving atomic absorption by the atomic gas 9, the light enters the light receiving unit 3. The measuring unit 4 measures a change in the intensity of the light received by the light receiving unit 3. The measurement of the intensity change is performed by comparing the intensity of the light 7 received by the light receiving unit 3 with the intensity of the light 7 before passing through the atomic gas 9 to obtain a light intensity ratio. Alternatively, the intensity change may be measured by measuring only the intensity of the light 7 received by the light receiving unit 3 after creating the calibration curve. The measurement of the light intensity before passing through the atomic gas 9 is performed, for example, in the light incident section 2. From the obtained intensity ratio, the absorption amount of the light 7 by the atomic gas 9, that is, the atomic absorbance by the component to be analyzed of the suspended particles is obtained. Actually, as described later, since the light intensity fluctuates due to deterioration of the optical transmission system and changes in dust in the duct, the light 7 including the absorbed light absorbed by the analysis component and the reference light not absorbed is used. Then, the intensity ratio between the absorption light received by the light receiving unit 3 and the reference light is obtained,
The absorbance is determined by comparing the intensity ratio between the absorption light before incidence and the reference light. The amount of the analytical component is measured from the absorbance obtained as described above.

The light source 1 is a light having a wavelength at which atomic absorption by the analysis component occurs, that is, a light having an absorption wavelength of the analysis component (absorption light).
Emit light 7 containing When analyzing a plurality of components of the suspended particles, the light source 1 emits light 7 including at least one of the plurality of absorption lights corresponding to each analysis component. The light source 1 may emit monochromatic light consisting only of absorbed light, or may emit continuous light including absorbed light, but preferably emits continuous light. In particular, it is preferable that the light source 1 emits light 7 including the absorption light absorbed by the analysis component and the reference light not absorbed by the analysis component. If such light 7 is used, the absorbance is accurately measured without being affected by changes in dust in the duct 6 by comparing the intensity ratio between the absorbed light and the reference light before and after absorption, as described later. can do. Further, it is preferable that the light source 1 emits light whose wavelength is adjusted to a position shifted from the center position of the absorption wavelength of the analysis component by 0.001 to 0.03 nm. By using light of such a wavelength, the absorbance due to the analysis component can be reduced, so that the measurement range of the component amount of the analysis component can be broadened.

The light source 1 having the above-mentioned characteristics includes a hollow cathode lamp used for ordinary atomic absorption, a wavelength-variable laser, a device that emits continuous light, and a light having a target wavelength by extracting the continuous light with a spectroscope. And the like. Of these, tunable lasers are particularly suitable.
This is because the wavelength tunable laser has such advantages that the intensity of the output light is sufficiently large to withstand light attenuation due to dust and the like, and that the output wavelength position can be adjusted as described above.

The light input section 2 receives light from the light source 1 in the duct 6.
For injecting into the atomic gas 9. As the light incident part 2, for example, a light transmission window attached to the duct 6,
Alternatively, it is preferably a light transmission window attached to an analysis tube described later. Examples of a material for forming the light transmission window include quartz glass.

The light receiving section 3 is for receiving the light 7 after passing through the atomic gas 9. The light receiving unit 3 is also preferably a light transmitting window attached to the duct 6 or the analysis tube, similarly to the light incident unit 2 described above. The light receiving unit 3 is a light incident unit 2
It is mounted at a position facing the light entrance so as to receive light from the light source.

It is preferable that a purge gas is introduced into the surface of the light transmission window which comes into contact with the gas 8 in the duct 6. As the purge gas, for example, nitrogen is used. By flowing the purge gas, it is possible to prevent the surface of the light transmission window from being stained due to the attachment of floating particles and the like in the gas 8 and to reduce the light transmittance of the light transmission window.

The measuring section 4 measures the intensity of the light 7 received by the light receiving section 3 and compares it with the intensity of the light 7 before being incident on the atomic gas 9. Ask. Then, the amount of the analytical component of the suspended particles is measured from the absorbance. Further, the measuring section 4 can also measure the component concentration in the gas 8 from the obtained amount of the analysis component.

The measuring section 4 includes a light detecting means and a calculating means, and includes a spectroscopic means before the light detecting means as required. This dispersing unit is for dispersing the light received by the light receiving unit 3 for each wavelength when the incident light is not monochromatic light. The spectroscopic means includes, for example, a normal spectroscope, a band pass filter, and the like. The light detecting means measures the intensity of the light 7 received by the light receiving unit 3 and includes, for example, a photodetector such as a photomultiplier (photomultiplier tube) or a photodiode array. By measuring the intensity of the light separated by the spectroscopic means, the intensity of the light from the light receiving unit 3 can be measured for each absorption wavelength of the analysis component. The calculation means includes a computer such as a normal computer. The calculating means obtains the absorbance of the analysis component from the ratio between the light intensity measured by the light detection means and the light intensity before incidence, and calculates the amount of the analysis component. Further, the component concentration in the gas 8 in the duct 6 is calculated from the flow rate data of the gas 8 in the duct 6 measured at the same time as the analysis and the amount of the above-described analysis component.

As described above, it is preferable that the light source 1 emits the light 7 including the absorption light absorbed by the analysis component and the reference light not absorbed. In this case, the measuring unit 4 obtains the intensity ratio between the absorbed light received by the light receiving unit 3 and the reference light, and compares the intensity ratio between the absorbed light and the reference light before incidence. From the ratio of these two intensity ratios, the absorbance due to the analytical component is determined. In this way, even when the light intensity received by the light receiving unit 3 changes due to a cause other than the atomic absorption, the change in the light intensity can be corrected and the absorbance can be accurately measured. Causes other than such atomic absorption include, for example, deterioration or contamination due to long-term use of the above-described light transmission window or an optical transmission system described later, or change in dust in the duct 6.

The above-described light source 1, light incident portion 2, and light receiving portion 3
And the measuring section 4 are connected using optical transmission systems 10 and 11, respectively. The optical transmission systems 10, 11 are preferably optical fibers. By using an optical fiber, the light source 1 and the measuring unit 4 can be provided separately from the duct 6. The duct 6 is usually outdoors,
The temperature is high due to heat of exhaust gas and the like. By using the optical fiber, the light source 1 and the measuring unit 4 can be installed in a room separated from the duct or in a place with an appropriate ambient temperature.

The analyzer according to the present invention may further include an analysis tube in the duct. The analysis tube is a tube having a diameter smaller than that of the duct 6 and having both ends opened, and examples of the material to be formed include graphite. The analysis tube is arranged in the duct along the flow direction of the gas 8, and the gas 8 in the duct 6 and a part of suspended particles pass through the analysis tube. As described later, only suspended particles contained in the gas 8 passing through the analysis tube are atomized by heating. By limiting the region of the gas 8 to be heated in the duct 6 to the inside of the analysis tube, the efficiency of atomization by heating can be increased.

The heating unit 5 atomizes at least a part of various forms of suspended particles, such as ions and oxides, existing in the gas in the duct 6 in the duct by heating to generate an atomic gas 9.
It is intended to be. More specifically, the heating unit 5
The analytical components of the suspended particles are converted into gaseous single atoms, that is, atomic gas 9 at a fixed ratio by heat decomposition excitation. When the suspended particles are heated to a high temperature (generally, about 2000 ° C. or higher, or 1000 ° C. or lower for a low melting point metal such as Pb (lead)), at least a part thereof becomes an atomic gas 9 which causes atomic absorption.

The heating unit 5 may be arranged outside the duct 6 or inside the duct 6, but is preferably arranged inside the duct 6. By doing so, the atomization efficiency of suspended particles by heating can be increased.

The heating section 5 outside the duct 6 includes, for example, a heating coil wound around the outside of the duct 6. By energizing the heating coil to generate heat, the suspended particles in the duct 6 can be heated.

The heating section 5 inside the duct 6 may be directly arranged inside the duct 6, but it is preferable that the heating section 5 is attached to the above-mentioned analysis tube inside the duct 6 and arranged. As a result, as described above, since only the gas in the analysis tube can be heated, the atomization efficiency of suspended particles by heating can be increased.

As the heating unit 5 disposed directly in the duct 6, for example, a gas combustion heating device such as a triple tube torch provided in the duct 6 can be mentioned. The triple tube torch has a configuration in which three annular tubes having different diameters are arranged concentrically and three times. The gas 8 and suspended particles in the duct pass through the innermost tube, air is sent between the innermost tube and the intermediate tube, and fuel gas passes between the intermediate tube and the outermost tube. The main component of the fuel gas is, for example, a mixture of normal butane, isobutane, and propane. Then, the fuel gas mixed with the air is burned to generate a flame.

As a method for heating the analysis tube, for example, there is a method in which an electric current is supplied to an analysis tube made of graphite to directly perform electric resistance heating. By doing so, the atomization efficiency of the suspended particles in the analysis tube can be further improved, and the structure can be manufactured without complicating the structures of the analysis tube and the heating unit. As another heating method, a heating coil wound on the outer surface of the analysis tube may be used. The heating coil includes an energizing heating coil that generates heat by energizing the coil, a high-frequency induction heating coil that causes a high-frequency current to flow through the coil to generate an induced current in the analysis tube or the suspended particles, and heats the coil. The heating coil only needs to be wound around the surface near the upstream end in the flow direction of the gas 8 among the outer surfaces of the analysis tube. By doing so, the atomic gas 9 generated on the upstream side of the analysis tube can be loaded on the flow of the gas 8 and filled in the analysis tube. However, it is preferable that the heating coil is wound substantially all over the outside of the analysis tube. By doing so, the atomization efficiency of suspended particles in the analysis tube can be further increased.

The heating by the heating unit 5 is preferably performed in a reducing atmosphere. Usually, the atmosphere around the heating unit 5 often automatically becomes a reducing atmosphere by heating. Even when the reducing atmosphere is not automatically brought into the reducing atmosphere due to the heating, the burning atmosphere is set to a more reducing condition in the gas combustion heating in the above-described duct 6, or the above-described analysis tube 30
In the duct 6 or the analysis tube 3
The inside of 0 can be forcibly set to a reducing atmosphere. By heating in a reducing atmosphere, the suspended particles can be heated and atomized without being oxidized, so that the atomization efficiency can be increased. If heating can be performed in a reducing atmosphere, it is possible to use a heater other than those described above as the heating unit 5.

As described in detail above, in the present invention, since the suspended particles in the gas in the duct are atomized in the duct by heating, it is necessary to introduce the suspended particles into the heat decomposition excitation section through the introduction pipe. There is no. Therefore, sedimentation of the particles in the introduction tube can be prevented, and the components of the suspended particles can be analyzed quickly and continuously.

[0042]

FIG. 2 is a schematic view showing an embodiment of the analyzer according to the present invention. In FIG. 2, a heating device 5 such as a triple tube torch is disposed in a duct 6, and the incident light transmitting window 2 and the passing light transmitting window 3 are provided on the duct 6 so as to face each other. The heating device 5 forms a flame at the time of measurement, for example, to atomize the analysis component of the suspended particles. A purge gas such as nitrogen is introduced into the incident light transmission window 2 and the transmitted light transmission window 3 through a purge gas introduction pipe 15.

Light from the light source 1 is transmitted to an optical transmission system 1 such as an optical fiber through an appropriate optical system such as a lens, if necessary.
0 is introduced. The light is guided to the duct 6 by the optical transmission system 10 and is introduced into the duct 6 through the incident light transmission window 2. After passing through the gas atomized by the heating device 5, the light passes through the passing light transmission window 3 and enters an optical transmission system 11 such as an optical fiber through an appropriate optical system such as a lens as necessary. . The light that has entered the optical transmission system 11 is introduced into the measurement unit 4. The measuring unit 4 includes a spectrophotometer 20 (integrating a spectrometer and a photodetector) and a computer 21. The light introduced into the spectrophotometer 20 is separated and the light intensity is measured for each absorption wavelength of the analysis component. The measured light intensity is transmitted to the computer 21 through the signal transmission system 22. Further, flow rate data of the gas 8 in the duct 6 is transmitted to the computer 21 from a flow meter 23 attached to the duct 6 through a signal transmission line 24. In the computer 21, the amount of the analysis component of the suspended particles is calculated from the light intensity measured by the spectrophotometer 20, as described above. Also,
In the computer 21, the concentration of the component (for example, g / N) in the gas in the duct is obtained from the light intensity and the flow rate data of the gas 8.
m ³ or mg / L) is also calculated.

FIG. 3 is a schematic diagram showing another embodiment of the analyzer according to the present invention. The apparatus shown in FIG. 3 further includes an analysis tube 30 inside the duct 6. The incident light transmitting window 2, the passing light transmitting window 3, and the heating device 5 are attached to the analysis tube 30. Incident light transmitting window 2 and passing light transmitting window 3
Is connected to the duct 6 by the protection members 31 and 32. The protection members 31 and 32 are for storing and protecting the optical transmission systems 10 and 11 such as optical fibers inside. The light transmission systems 10 and 11 reach the incident light and transmitted light transmission windows 2 and 3 from the outside of the duct 6 through the protection members 31 and 32, respectively.

Some of the suspended particles passing through the analysis tube 30 are:
It is thermally decomposed by the heating device 5 to become an atomic gas. Light from the light source 1 passes through the optical transmission system 10 and enters the incident light transmitting window 2.
Incident on the atomic gas. The light that has passed through the atomic gas
The light transmission system 11 is connected through the transmitted light transmission window 3 on the opposite side of the analysis tube 30.
Through the measuring unit 4 outside the duct 6. The measuring section 4 is composed of a spectrophotometer 20 and a computer 21, similarly to the measuring section 4 of the apparatus shown in FIG. The spectrophotometer 20 and the computer 21 are connected by a signal transmission system 22. The flow rate data of the gas 8 in the duct 6 measured separately is transmitted to the computer 21. Thus,
Similarly to the computer 21 shown in FIG. 2, the computer 21 shown in FIG. 3 calculates the amount of the analysis component of the suspended particles and the concentration of the component in the gas 8 in the duct 6.

Using the apparatus shown in FIG. 2, zinc oxide particles in the exhaust gas discharged from the hot metal processing furnace were continuously analyzed. The analysis was performed by determining the atomic absorbance of Zn (zinc) and measuring the zinc oxide concentration in the exhaust gas from the absorbance.

As a wavelength variable laser, a Ti sapphire laser is excited by a second harmonic oscillation light (0.53 nm) of a YAG laser to be a continuous wavelength laser light, and the wavelength is adjusted for the second harmonic of this laser light. And oscillates.

As the absorption light, the atomic absorption wavelength of Zn 472.
Laser light having a wavelength of 216 nm was used. In addition, laser light having a wavelength of 430.000 nm, which does not absorb Zn, was used as reference light. The laser light of the absorption light and the reference light was condensed by a lens, introduced into the light incidence fiber 10, and transmitted to the exhaust gas duct 6 about 100 m away. The light emitted from the light incident fiber 10 is converted into parallel light through a lens, and the incident light transmitting window 2 made of quartz glass is used.
And introduced into the duct 6. The introduced laser light passed through the flame formed by the triple tube torch 5 and exited the duct 6 through the transmitted light window 3 on the opposite side. The outgoing laser light was introduced into the light receiving optical fiber 11 using a lens installed outside the duct 6. The other end of the light receiving fiber 11 is connected to an entrance slit of a 50 cm evert type spectrometer of the spectrophotometer 20. After the laser beam incident on the entrance slit is separated by an Evert type spectroscope,
The light intensity was measured by a photodiode array.

The measured light intensity was transmitted to the computer 21, and the computer 21 determined the absorbance of Zn from the integrated intensity for one second, and the apparent zinc oxide concentration in the exhaust gas 8 every second from the absorbance. The conversion from the absorbance due to Zn to the apparent zinc oxide concentration was performed using a calibration curve previously determined. Further, a flow meter 23 provided in the duct 6
The flow rate data of the exhaust gas 8 due to the above is also transmitted to the computer 21. Then, the zinc oxide concentration in the exhaust gas 8 was determined from the flow rate data and the apparent zinc oxide concentration.

FIG. 4 shows the measurement results of the zinc oxide concentration in the exhaust gas 8 during the hot metal treatment, which was continuously measured as described above. The curve shown by the solid line in FIG. 4 is the zinc oxide concentration measured according to the present invention, and the circles are the values measured by separately collecting the suspended particles in the exhaust gas 8 every 5 minutes.

As is evident from FIG. 4, the zinc oxide concentration determined according to the present invention is in good agreement with the concentration determined by filter collection. From this, it was found that rapid and continuous (every second in the case of the present embodiment) analysis was realized by the present invention with sufficiently good analysis accuracy.

In this example, the measurement was performed by setting the wavelength position of the laser at the center position of the absorption wavelength of zinc.
For this reason, the absorbance sensitivity by zinc was high, and concentration measurement could not be performed where the concentration of zinc oxide was about 2 mg / L or more. However, by shifting the laser wavelength position from the center position of the absorption wavelength by 0.001 to 0.03 nm, the absorption sensitivity can be suppressed, and as a result, it was possible to measure the concentration of higher concentration zinc oxide. .

[0053]

As described above in detail, according to the present invention, a constant flow pump for introducing a gas between a duct through which a gas containing suspended particles flows and a heat decomposition excitation section of an atomic absorption spectrometer. It is not necessary to provide an inlet pipe. Therefore, no problems such as sedimentation of the particles caused by sampling of the floating particles occur, so that the components of the floating particles in the gas can be analyzed quickly and continuously. Also, by using a tunable laser as the light source,
The measurement concentration range of the components of suspended particles is greatly expanded, and the function as an online measurement device is enhanced. Furthermore, by using an optical fiber as the optical transmission system, restrictions on conditions for installing various devices such as a measurement unit including a calculation unit and a light source are greatly eased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an atomic absorption spectrometer according to the present invention.

FIG. 2 is a schematic diagram showing one embodiment of an atomic absorption spectrometer according to the present invention.

FIG. 3 is a schematic view showing another embodiment of the atomic absorption spectrometer according to the present invention.

FIG. 4 is a view showing the results of continuous measurement of the concentration of zinc oxide in exhaust gas measured in the examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Light input part 3 ... Light receiving part 4 ... Measurement part 5 ... Heating part 6 ... Duct 7 ... Light 8 ... Gas in duct 9 ... Atomic gas 10, 11 ... Optical transmission system 15 ... Purge gas introduction pipe 20 ... Spectrophotometer 21: Computer 22, 24: Signal transmission line 23: Flow meter 30: Analysis tube 31, 32: Tubular member

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Atsushi Chino, Inventor 1-1-2, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Tomoji Ishida 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan F-term (reference) in this steel pipe company 2G059 AA01 BB01 CC19 DD01 DD15 EE01 EE11 FF04 FF06 GG01 JJ17 MM01 NN07

Claims (10)

[Claims] An atomic absorption spectrometry for analyzing a component of suspended particles in a gas flowing in a duct, wherein at least a part of the suspended particles in the duct is atomized in the duct by heating to form an atomic gas. The step of passing light through the atomic gas; and the step of determining the absorbance of the suspended particles by the analytical component from the intensity change of the atomic gas passing light and measuring the amount of the component. Analysis method. 2. An atomic absorption spectrometer for analyzing a component of suspended particles in a gas flowing in a duct, wherein the light source and at least a part of the suspended particles in the duct are atomized in the duct by heating. A heating section for converting the gas into an atomic gas, a light input section for inputting light from a light source into the atomic gas, a light receiving section for receiving light from the light input section that has passed through the atomic gas, and a light receiving section for receiving light. An atomic absorption spectrometer comprising: a measuring unit for determining the absorbance of the suspended particles by the analytical component from the change in the intensity of the light and measuring the amount of the component. 3. The atomic absorption spectrometer according to claim 2, wherein the light source emits continuous light including absorption light in which the suspended particles are absorbed by the analysis component. 4. The light source emits light including absorption light generated by absorption of suspended particles by an analysis component and reference light not absorbed by the component, and the measurement unit detects the absorption light and the reference light received by the light receiving unit. The atomic absorption spectrometer according to claim 2, wherein the absorbance of the component is determined by comparing the intensity ratio with the intensity ratio of the absorbed light and the reference light before the incidence. 5. The atomic absorption spectrometer according to claim 2, wherein the light source is a tunable laser. 6. The atomic absorption spectrometer according to claim 2, wherein the light source and the light-entering unit, and the light-receiving unit and the measuring unit are respectively connected by optical fibers. . 7. The heating device according to claim 2, wherein the heating unit is disposed in a duct, and the light input unit and the light receiving unit are light transmission windows respectively attached to the duct. Item 6. The atomic absorption spectrometer according to item 1. 8. An analysis tube provided in the duct, wherein the heating unit disposed in the duct is attached to the analysis tube, and the light input unit and the light receiving unit are respectively attached to the analysis tube. The atomic absorption spectrometer according to claim 7, which is a light transmission window. 9. The heating unit according to claim 2, wherein the heating unit heats the suspended particles in the duct in a reducing atmosphere.
The atomic absorption spectrometer according to any one of claims 1 to 7. 10. The atomic absorption spectrometer according to claim 7, wherein a purge gas is introduced into a surface of the light transmission window that comes into contact with the gas in the duct.