WO2001071320A1 - Procede et appareil d'analyse de metal vaporise - Google Patents

Procede et appareil d'analyse de metal vaporise Download PDF

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Publication number
WO2001071320A1
WO2001071320A1 PCT/JP2000/007146 JP0007146W WO0171320A1 WO 2001071320 A1 WO2001071320 A1 WO 2001071320A1 JP 0007146 W JP0007146 W JP 0007146W WO 0171320 A1 WO0171320 A1 WO 0171320A1
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Prior art keywords
light
molten metal
wavelength
intensity
measurement
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PCT/JP2000/007146
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English (en)
Japanese (ja)
Inventor
Kazukiyo Yoshida
Tomoharu Ishida
Takanori Akiyoshi
Atsushi Chino
Ikuhiro Sumi
Ryo Kawabata
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Nkk Corporation
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Priority claimed from JP2000085350A external-priority patent/JP3909999B2/ja
Application filed by Nkk Corporation filed Critical Nkk Corporation
Publication of WO2001071320A1 publication Critical patent/WO2001071320A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/3103—Atomic absorption analysis

Definitions

  • the present invention relates to a method and an apparatus for quickly analyzing a component element in a molten metal.
  • an atomic absorption method is known as a highly reliable analysis method for analyzing the composition of a metal, in which a metal is decomposed with an acid or the like to form a solution.
  • a proposal has been made to apply this atomic absorption method, which is essentially a highly accurate analysis method, to the direct analysis of molten metal.
  • Such proposals include, for example, a method and apparatus for direct analysis of molten metal described in Japanese Patent Application Laid-Open No. 09-049795, and Japanese Patent Application Laid-Open No. 09-5040725.
  • These techniques irradiate a metal vapor layer on the surface of the molten metal with light of a specific wavelength (atomic absorption line wavelength), measure the absorptivity of light absorbed by the vapor layer, and determine the components in the molten metal. This is to determine the concentration of the element.
  • the disadvantage of the atomic absorption spectrometry is that the measured concentration range is narrow because the amount of generated metal vapor cannot be controlled. Appears prominently.
  • the measurement principle of the atomic absorption method is to determine the amount or concentration of an analytical element in a sample based on the atomic absorption phenomenon according to the following equation (1).
  • the light intensity ratio (I / Io) decreases sharply with an increase in the amount or concentration C of the element to be analyzed. If the light intensity ratio (IZI0) is too small, the influence of light other than the absorbed light and the dispersion of the measured values with the measuring device appear. As a result, concentration measurement becomes difficult. Thus, there is an upper limit on the amount or concentration C of the element to be analyzed.
  • one or more of the terms of, C, and C is reduced based on Equation (1) ⁇ .
  • the sample solution is diluted to lower the amount of the element to be analyzed or the concentration C, or the angle with the optical axis of the atomization section (burner) is changed to shorten the vapor layer length L.
  • the concentration C of the generated vapor layer is determined by the production conditions and the content in the molten metal, and cannot be controlled.
  • the vapor layer length L or the extinction coefficient must be reduced. It is difficult to reduce the length of the steam layer] L due to the large engineering challenge required to stably maintain the thickness of the steam layer at an appropriate small value. Also, it is difficult to reduce the absorption coefficient W because there is not always an absorption line having n corresponding to the measured concentration range. For example, as the atomic absorption line of Mn (manganese), there is only a line of 279 nm as a line having a large P and light coefficient, and a line of 403 nm as a line having a small P and light coefficient.
  • the Mn concentration C in the vapor layer is high. Even if it is very short, about 1 mm, the absorption by the vapor layer is too strong. Therefore, the above-mentioned light intensity ratio becomes 1% or less even for Mn with a concentration of 0.1%, and Mn with a concentration of 0.1% or more cannot be measured.
  • the method of focusing on the molten metal surface described in Japanese Patent Application Laid-Open No. 9-500725 is difficult to put to practical use on the surface of a molten metal that actually flows. If the surface of the molten metal is a stationary surface, it behaves like a mirror surface, and the light projected on it reaches the designed reflection position, and its reflection intensity is sufficiently strong. However, when the surface fluctuates and waves are generated, it is only intermittent that the reflection direction returns to the designed reflection position. Furthermore The radiation intensity is also very small as compared with the stationary surface reflection.
  • the reflecting surface is a curved surface rather than a parallel surface, and as a result, the illuminance (density of light intensity) at the measurement position decreases as a result of the reflection angular force spreading according to the curvature.
  • a static surface is made, but it is difficult to make a static surface in the manufacturing process.
  • a stationary surface cannot be created because the molten metal surface fluctuates as a result of flowing Ar or nitrogen gas to inactivate the atmosphere inside the probe.
  • the amount of steam fluctuates due to such a change in the temperature of the molten metal.
  • the amount of Mn vapor generated from molten steel at 1600 ° C changes by about 4% for a temperature change of 5 ° C. Therefore, in order to perform high-precision analysis, the temperature of the molten metal must be measured with an accuracy of 5 ° C or less to correct the measured value of the amount of steam.
  • the use of a platinum-rhodium-based thermocouple is optimal for performing high-temperature measurement with high accuracy, but it is necessary to place the temperature measurement position directly below the laser-irradiated surface, making application quite difficult. Especially in a situation where a probe is used for atmosphere control, etc., it is more preferable to set the measurement position directly below the irradiation surface. Difficult.
  • the light intensity is measured after dispersing the received light using monochrome or polychrome.
  • the measurement sensitivity is insufficient because the amount of light is attenuated due to slits or the like during the spectral separation. Disclosure of the invention
  • An object of the present invention is to provide a method for analyzing a molten metal capable of expanding a measurement concentration range.
  • a molten metal analysis method for allowing a laser beam to pass through a vapor layer of a molten metal and measuring the concentration of an analysis element contained in the molten metal from a change in intensity of the laser beam passing through the vapor layer.
  • a method is provided in which the wavelength of the laser light is adjusted to a position shifted from 0.001 to 0.03 nm from the center position of the absorption wavelength of the analysis element.
  • the measurement light having the center position of the wavelength and the reference light having a wavelength that does not cause atomic absorption are superimposed and passed on the same optical path, and the intensity of the measurement light component and the intensity of the reference light component of the passed light are measured. From the known relationship between the intensity ratio of the measurement light component and the reference light component, the thickness of the vapor layer, and the temperature of the molten metal, a method for analyzing molten metal characterized by measuring the concentration of an analytical element in the molten metal is known. Provided.
  • the wavelength half width Z of the measurement light is X
  • the wavelength half width of the atomic absorption line of the analysis element is X
  • the shift amount of the center wavelength of the measurement light is Y
  • Z ⁇ (2X -It is preferable to satisfy the relationship of Y).
  • the measurement light whose wavelength center position is shifted from the center position of the atomic absorption line of the main component element of the molten metal according to the light absorption sensitivity and the wavelength center position for the analysis element are shifted.
  • the measurement light and the reference light having a wavelength that does not cause atomic absorption are superimposed on the same optical path and passed through the vapor layer on the surface of the molten metal, and the intensity of both the measurement light components of the passed light and the reference light component are compared.
  • the intensity is measured, and the known ratio between the intensity ratio between the measurement light component corresponding to the main component element of the transmitted light and the reference light component and the intensity ratio between the measurement light component corresponding to the analysis element and the reference light component is measured. From this relation, it is preferable to correct the vapor layer thickness.
  • the wavelength of the measurement light is monitored during the analysis, and the deviation amount between the center position of the atomic absorption line and the central position of the measurement light wavelength is measured. It is preferable to correct the light absorption sensitivity of the light measurement light component.
  • the intensity of the reflected light after irradiating the surface of the molten metal with the measuring light and the reference light, reflecting the reflected light and passing the reflected light through the vapor layer.
  • the measuring light and the reference light it is preferable to irradiate the measuring light and the reference light to a region of 5 mm ⁇ or more on the surface of the molten metal.
  • the measurement data when the reflected light intensity of the reference light is equal to or more than the threshold value for the density measurement.
  • the reflected light is received by an optical fiber, and the received reflected light is transmitted to a bandpass filter whose passing wavelength includes the atomic absorption line wavelength of the analysis element and whose passing wavelength width is 5 nm or less. It is preferable to select the wavelength by passing the light and measure the total amount of light after passing through the band-pass filter.
  • the measurement light and the reference light to be irradiated are one laser light, and the intensity of the measurement light and the reference light after the reflected light has passed through the band-pass filter is within the wavelength band of the band-pass filter. It is preferable to adjust the irradiation light intensity so as to be at least 10 times the radiation light intensity of the molten metal.
  • the main component element of the molten metal is S iron and the analysis element is manganese.
  • a plurality of laser light sources having variable wavelengths, half-widths and degrees of laser light to be emitted, means for measuring the wavelengths and degrees of the laser lights, and a plurality of lasers are provided.
  • An optical system for superimposing a plurality of laser beams emitted from the light source with different wavelengths on the same optical path, a chopper for turning on and off the laser beam superimposed on the same optical path at regular intervals, and a molten metal at an end.
  • a band-pass filter that separates a narrow wavelength range including the wavelength of each laser beam from the reflected light afterwards, a photodetector that measures the total amount of light after passing through the band-pass filter, and a means that measures the temperature of the molten metal And a calculation device for calculating the measured result.
  • FIG. 1 is an explanatory diagram of the principle of the present invention.
  • FIG. 2 is an explanatory diagram of the principle of the present invention.
  • FIG. 3 is a diagram showing an example of a molten metal analyzer according to the present invention.
  • FIG. 5 is a diagram illustrating an example of a result of a molten metal analysis in the example.
  • FIG. 6 is an explanatory diagram of the principle of the present invention.
  • the analysis method according to the present invention includes a step of passing a laser beam through a vapor layer of the molten metal, a step of determining an intensity change of the laser beam generated by passing through the vapor layer, and a step of melting from the intensity change. Measuring the concentration of the analysis element contained in the metal.
  • the laser light As the laser light, a laser light whose wavelength is adjusted to a position shifted from the center of the absorption wavelength of the analysis element by 0.001 nm to 0.03 nm is used. This laser beam is It is guided to the vicinity of the metal surface, passes through the molten metal vapor layer, and measures the laser beam intensity change due to the passage.
  • the relational expression between the intensity change and the concentration of the component element in the metal (unit is, for example, wt%) is determined in advance, and the concentration of the analysis element is determined from the intensity change measured using this relational expression.
  • the change in intensity may be measured by comparing the laser light intensity before and after passage, or by measuring only the laser light intensity after passage after creating a calibration curve. .
  • the intensity change amount may be the measured intensity itself, the ratio of a state in which a vapor layer is negligible due to no or very small vapor layer to a state in which a vapor layer is present, or a method of absorbing light in the same optical system. It may be a ratio to light that does not cause light. Also, these values may be themselves, or the logarithms of these values.
  • the absorption spectrum due to the element to be analyzed has a width with respect to the wavelength of light because the temperature of the absorbing substance affects the absorption spectrum. That is, the intensity change due to light absorption is maximum at the light absorption center wavelength, and decreases with the amount of shift at a wavelength position shifted from the center wavelength. In other words, by shifting the wavelength position of one laser beam used for measurement from the absorption center wavelength, it is possible to reduce the intensity change due to the absorption of the analysis element.
  • Figure 1 shows an example of the change in transmitted (detected) light with respect to incident light when the wavelength position of the laser light used for measurement is shifted. If the wavelength position of one laser beam is matched with the center position of the atomic absorption wavelength, there is almost no transmitted light and no light detection power S is possible, but transmission is achieved by shifting the wavelength. It can be seen that light can be detected.
  • the upper limit of the amount of shift is set to less than twice the wavelength half width of the atomic absorption line. More preferably, the upper limit of the shift amount is set so that the absorbance at the maximum value of the measurement concentration range is 0.5 or more. The reason is that if the absorbance is less than 0.5, the sensitivity over the entire measured concentration range is insufficient.
  • the concentration range of elements that can be measured by atomic absorption spectrometry is greatly expanded. be able to.
  • As light source light that enables such measurement continuous light can be separated by a spectroscope to extract light of a target wavelength, and the extracted light can be used as light source light.
  • a laser because of its strength and light intensity.
  • it is suitable for a so-called tunable laser that can arbitrarily adjust the oscillation wavelength position.
  • wavelength tunable lasers are suitable for S, and the wavelength width of the output light must be small.
  • the proportion of light that deviates from the absorption width increases.
  • the amount of unabsorbed light increases, so that the change in light intensity with respect to the change in concentration becomes small and the measurement accuracy deteriorates.
  • the wavelength width of the output light (light source light) as the measurement light as follows, it is possible to limit the proportion of the light that is not absorbed and maintain good measurement accuracy. That is, assuming that the half-width of the wavelength of the atomic absorption line of the analysis element constituting the high-temperature molten metal is X and the deviation of the center wavelength of the measurement light from the center position of the atomic absorption line is Y, the center wavelength of the measurement light Is preferably Z ⁇ (2X ⁇ Y).
  • the wavelength distribution of the absorption spectrum of the element to be analyzed can be regarded as a Gaussian distribution
  • the intensity at twice (2 ⁇ - 4. 7 ⁇ ) away half width from the center is 1. 0-5. That is, the wavelength position absorbance at location 1 0 5 next relative absorbance center wavelength, even if the absorbance at higher a connexion center wave length of the sample concentration becomes 1 0 0 or more, the wavelength position extinction Is the wavelength range that is considered to be almost nonexistent.
  • the measurement light can be regarded as having a Gaussian distribution with a half-width ⁇ ⁇ and a standard deviation ⁇ variance with a center wavelength at a position shifted by ⁇ from the center position of the atomic absorption line of the analysis element.
  • the amount of measurement light is reduced to 1%, and is absorbed by such a power analysis element. The effect is small even if it remains without it.
  • Such measurement light and reference light with a wavelength that does not cause atomic absorption are superimposed on the same optical path using an optical filter that reflects or transmits light according to the wavelength characteristics, and passes through the vapor layer on the surface of the hot molten metal. Let it.
  • the ratio with the reference light that does not cause atomic absorption is necessary.
  • the reference light light having a wavelength close to the wavelength of the measurement light without light absorption by the vapor layer is desirable.
  • the light intensity of the measurement light component and the reference light component of the light that has passed through the vapor layer is detected by spectroscopy using an optical filter that reflects or transmits light according to the wavelength characteristics.
  • a reference light intensity ratio (R: measured light intensity / reference light intensity) is obtained from the obtained light intensities of the respective wavelengths, and the intensity ratio (R 0) in a state where there is no vapor layer or a very small amount is negligible.
  • the amount of change (RZR 0) from is calculated.
  • This absorbance can be expressed as a function of the concentration of the analytical element (measurement component) in the molten metal, the temperature of the molten metal, and the thickness of the vapor layer. Therefore, by correcting the temperature of the molten metal and the thickness of the vapor layer, the concentration of the analytical element in the molten metal can be obtained.
  • the measurement light for measuring the main component elements of the molten metal is passed through the vapor layer on the surface of the high-temperature molten metal along the same optical path as the measurement light for the analysis element and the reference light.
  • the light that has passed through the vapor layer is separated using an optical filter, and the light intensity of each of the main component element measurement light, the analysis element measurement light, and the reference light is detected. From the obtained light intensity, the reference light intensity ratio (R 1S ) of the main component element and the reference light intensity ratio (R) of the analysis element are obtained.
  • the amount of change from the intensity ratio (R 1S 0, R 0) is determined.
  • the vapor layer thickness can be corrected by setting the ratio (A / A Is ) between the absorbance of the analytical element (A) and the absorbance of the main component (A IS ) as the absorbance of the analytical element after correcting the vapor layer thickness. It is.
  • the above equation (1) for P and light phenomena holds. Therefore, both elements
  • the fluctuation term of the vapor layer thickness (length) L is eliminated, and it can be expressed as a function of the concentration of the analyzed element.
  • the center position of the wavelength of the measurement light with respect to the main component element of the molten metal is preferably shifted from the center position of the atomic absorption line of the main component element according to the absorption sensitivity of the atomic absorption of the main component element. No. The reason is that if the center position of the wavelength of the measurement light and the center position of the atomic absorption line are the same, the signal becomes small and the SZN deteriorates when the absorption sensitivity is high. In addition, as will be described later, the measurement accuracy is further improved by monitoring the wavelength of the measurement light during the measurement and performing the measurement while correcting the fluctuation of the absorbance due to the change of the wavelength.
  • the amount of vapor of each element on the surface of the molten metal is proportional to the concentration (activity) of the element in the molten metal and the vapor pressure (saturated vapor pressure).
  • the saturated vapor pressure can be expressed as a function of the temperature of the molten metal.
  • the wavelength tunable laser is required to have a sufficiently small wavelength width of the output light, to be able to accurately set the center position of the wavelength, and to have no change over time in the wavelength position.
  • the absorbance sensitivity is a function of the wavelength position of the light source light, as described above, so that there is no change in the wavelength position over time.
  • the installation environment (particularly temperature change) of the laser is to be strictly controlled, Various difficulties arise, such as making the components of the first component unchanged, and it is practically difficult to achieve them.
  • FIG. 3 shows an example of a device configuration for implementing the present invention.
  • a laser beam emitted from a laser light source 1 passes through an optical system 2 and is applied to a metal vapor layer 4 on the surface of the molten metal 3.
  • the laser light that has passed through the metal vapor layer 4 passes through the optical system 5 and is guided to the photodetector 6, where the intensity is measured.
  • the laser light source 1, the photodetector 6, and the like can be arranged separately from the surface of the molten metal 3.
  • the optimum shift amount of the wavelength can be obtained as follows. First, the wavelength dependence of P and light intensity changes is examined in advance. That is, after preparing a measurement system, the concentration of the target analysis element of the molten metal 3 is measured at several points by changing the wavelength of the laser beam. Then, the position of the laser wavelength at which the intensity of the laser beam after absorption by the metal vapor 4 is considered to be the most appropriate is found. Alternatively, in the atomic absorption analysis of a solution sample using a normal atomic absorption spectrometer, use the laser-light source of this analysis system as the light source and examine the wavelength dependence of P and light intensity change in advance.
  • the intensity change due to light absorption changes according to the wavelength half width of the emission wavelength, not only the wavelength shift amount but also the wavelength width can be changed to make the sensitivity more appropriate.
  • the optical systems 2 and 5 may be arranged in the probe so that the inside of the probe is made to have an inert gas atmosphere.
  • a spectroscope or a band-pass filter may be provided before the photodetector 6. By doing so, it is possible to measure only the intensity of the light of the target wavelength and reduce the effects of the heat radiation of the molten metal 3 and the stray light from the illumination.
  • the light 20 emitted from the tip of the optical fiber 11 a passes through the irradiation optical system 22, passes through the vapor layer 4, and is irradiated on the surface of the molten metal 3.
  • the light 21 reflected on the surface of the molten metal 3 passes through the vapor layer 4 again, and then is transmitted through the light receiving optical fiber 11 lb.
  • the light emitted from the optical fiber for receiving light 1 1b passes through the lens 12 and is converted into parallel light.
  • the light passes through the optical filters 13a and 13b (high-pass filter 1) and is divided into each laser light wavelength. After that, the light passes through the band-pass filters 14a and 14b and is guided to the photodetectors 6a and 6b to measure the intensity.
  • the measured intensity of each wavelength is the temperature information from the molten metal temperature sensor 16, the laser-laser wavelength information from the wavelength measuring instrument 19 measured for the laser light source, and the beam sampler 17 and the light.
  • the laser output power from the laser light source measured by the detector 18 is sent to the arithmetic unit (computer) 15 together with the information.
  • the correction of laser power fluctuation, the fluctuation of laser output wavelength, the fluctuation of vapor layer thickness, and the correction of temperature are performed by the arithmetic unit 15 to determine the concentration of the analytical element in the molten metal. You can ask.
  • the waves occur randomly and move in random directions. And the curvature of the wavefront also changes from moment to moment.
  • the direction in which the light is reflected and returned is also random. Therefore, when the measurement time is finite, the reflected light from a specific point on the molten metal surface may never reach the light receiving section. However, the change in wavefront that occurs at another point away from this specific point also occurs at random, so that the probability that the reflected light from that point also does not reach the light receiving unit is very small. Therefore, by increasing the number of reflection points, the expected value of the number of times of reaching the reflected light power receiving unit increases.
  • the waves generated on the surface due to the fluctuations of the molten metal surface often have a radius of curvature of about 1 to 2 mm, and the force S propagates and the surface has complicated irregularities. Focusing on one of the projections, if the projection is irradiated with light and the light reflected from one point in the projection is received, the reflection from other parts of the projection other than the area very close to that point is detected. No light is received. In order to increase the number of times of light reception, it is an essential condition to irradiate one laser beam to the other concave and convex portions so that the reflected light from another convex or concave portion can be received.
  • the number of times of receiving light can be increased. Since the typical size of the protrusion is 12 to 12 mm, irradiating more than the area with the same width before and after that means that the laser light irradiation area is 5 mm in actual work That is to say. By defining such an irradiation area, the measurement is extremely effective.
  • the measurement accuracy is improved by measuring the light intensity separately every short time and using the signal only when the intensity of the reflected light is equal to or higher than the threshold for the density measurement.
  • Most of the signals with low reflected light intensity are only radiated light, and the amount of light absorbed cannot be measured accurately. Therefore, SZN is improved by using a signal only when the intensity of the reflected light (especially the reflected light of the reference light) is equal to or higher than the threshold for the density measurement, and the analysis accuracy is further improved.
  • the radiation emitted by the molten metal itself is separated from the measurement light as follows. That is, the irradiation of one laser beam is cut off at regular intervals, the radiated light (I f ) at the cutoff is measured, and the measured light intensity at the laser irradiation (I and the radiated light intensity measured at the cutoff (I The difference (I-I “) from f ) is regarded as the intensity of only the reflected light of the laser. The intensity of the atomic absorption can be accurately measured based on the intensity of the reflected light thus measured.
  • the cycle for cutting off the irradiation of one laser beam is preferably in the range of 1 to 1000 Hz.
  • the laser beam is passed through a rotary interrupter (hereinafter referred to as a chopper) before irradiating the molten metal surface. Irradiation and cutoff of laser light are performed alternately. During irradiation, the total light of laser reflected light and radiated light is measured, and when cutoff, only radiated light is measured. In this way, the true laser reflected light can be easily measured. At this time, the laser light blocking time must be longer than the light measurement time.
  • the radiated light from the molten metal is continuous light, as an easy measurement method, the total light of the reflected light and the radiated light is separated by a spectroscope, and the radiated light having a wavelength very close to the wavelength of the incident laser light is measured. By measuring, radiation light having the same wavelength as the laser light may be estimated.
  • a method for detecting reflected light for example, there is a method of measuring light intensity by dispersing light received using a monochromator or a polychromator.
  • the light quantity is attenuated by a slit or the like when performing spectroscopy, so that the measurement sensitivity is insufficient. So we received
  • the light is passed through a band-pass filter whose transmission wavelength includes the reflected light wavelength and the transmission wavelength width is 5 nm or less, and after selecting the wavelength, the entire light amount is detected as a signal.
  • a light-receiving optical fiber with a diameter of about lmm ⁇ is attached to receive the reflected light from the molten metal surface, and the light emitted from the other end of the optical fiber is converted into parallel light by a lens.
  • a band-pass filter After passing through a band-pass filter, the total amount of light is led to a photomultiplier tube (Photomaru), and the light intensity is measured.
  • the measurement sensitivity can be improved.
  • it is desirable that the wavelength to be measured is included in the half width of the bandpass filter, and that the half width is as small as possible.
  • the specific wavelength range for 45-degree incident light is split using an optical filter that reflects and transmits light in another specific wavelength range, passes through a band-pass filter with the measurement wavelength as the center wavelength, and is guided to a photomultiplier tube (Hotmal).
  • a photomultiplier tube Hetmal
  • the irradiation light intensity is adjusted so that the intensity of the reflected light to be detected is 10 times or more that of the radiated light.
  • the intensity of the reflected light of the wavelength absorbed by the vapor layer is reduced by the absorption, so that the intensity of the reflected light when it is not absorbed is 100 times or more that of the radiated light. It is desirable to adjust the strength.
  • the ratio of the reflected light to the radiated light becomes small and the measurement accuracy of the reflected light is deteriorated.
  • at least one surface of the molten metal should be used so as not to detect the radiated light from the molten metal. It is desirable to shield the part.
  • the temperature of the molten metal may be measured by calculating a relational expression between the intensity of the radiated light of a specific wavelength and the temperature of the molten metal in advance and calculating the measured value of the intensity of the radiated light of the specific wavelength. Further, instead of the radiation light intensity of a specific wavelength, a ratio of the intensity of radiation light of two specific wavelengths may be used.
  • the radiant light intensity may be measured by installing a separate measuring device, or may be obtained by using the light amount measured when the measuring light is blocked by the chopper. .
  • the method of the present invention is a method for measuring a system such as molten steel whose main component is iron and whose analysis element is Mn (manganese).
  • Mn manganese
  • the Mn concentration in molten steel is 0.2 wt%
  • the measurement cannot be performed due to saturation of the absorbance S in the above description, the method of the present invention enables measurement even when the Mn concentration in molten steel is 2 wt%.
  • FIG. 4 shows an example of the device.
  • the laser beams emitted from the laser light sources 1a (for the analysis of the analysis element), 1b (for the measurement of the main component) and 1c (for the reference light) are Light passes through the same optical path through an optical filter (high pass filter) 8.
  • the laser light source a laser light source capable of changing the wavelength, half width and intensity of the emitted laser light is used.
  • the light having the same optical path is introduced into the optical fiber 11a through the lens 9 and transmitted to the vicinity of the molten metal.
  • the laser light is passed through a chopper 10 immediately before being introduced into the optical fiber 11a.
  • Light emitted from the tip of the optical fiber 11a passes through the irradiation optical system 22, passes through the vapor layer 4, and is irradiated on the surface of the molten metal 3.
  • the irradiation optical system 22 adjusts the distance between the end face of the fiber 11a and the lens by a fine adjustment mechanism of the lens position attached to the lens, and converts the laser light to the surface of the molten metal 4 as parallel light or divergent light.
  • the mechanism is capable of irradiation.
  • the light reflected on the surface of the molten metal 3 passes through the vapor layer 4 again, and is transmitted through the receiving optical fiber 11b.
  • One or a plurality of optical fibers may be used.
  • the light emitted from the receiving optical fiber 11b passes through the lens 12 to become parallel light, passes through the optical filters 13a, 13b that separate the wavelength range, After being divided, the light passes through a bandpass filter 14a to 14c and is guided to photodetectors 6a to 6c for measuring the total light intensity, and the intensity is measured.
  • the measured intensity of each wavelength is obtained from the temperature information from the molten metal temperature sensor 16, the laser wavelength information from the wavelength measuring instrument 19 measured for the laser beam of the laser source, and the beam sampler 17. It is sent to the arithmetic unit 15 together with information on the laser output power from the laser light source measured by the photodetector 18.
  • the laser-power fluctuation correction, laser-output wavelength fluctuation correction, vapor layer thickness fluctuation correction, and temperature correction are performed by the arithmetic unit 15 to determine the analytical elements in the molten metal.
  • the concentration can be determined.
  • the Mn concentration in the molten metal was measured.
  • Molten metal 3 was produced by melting 5 kg of molten steel in a carbon crucible in a high frequency melting furnace. Then, Mn was added to the molten steel in an amount equivalent to 0 to lwt% in the molten steel concentration. Mn measurement was performed at a molten steel temperature of 1600 ° C.
  • One end of the laser light input fiber 2 was placed at a position where laser light from the laser light source 1 was collected.
  • the other end of the light-entering fiber 2 was placed in the probe and placed near the molten steel surface along with the probe.
  • the inside of the probe was filled with nitrogen gas in order to prevent oxidation due to air mixing.
  • light emitted from the light-entering fiber 2 passed through the vapor layer 4 and was then sent to one end of the light-receiving fiber 5.
  • the other end of the light receiving optical fiber 5 was placed in the entrance slit of a 50 cm evert spectroscope. The light that reached the entrance slit was split by a spectroscope and the intensity was measured by a photodiode 6.
  • Molten metal 3 was prepared by melting 5 kg of molten steel in a carbon crucible in a high-frequency melting furnace and adding Mn to the molten steel in an amount equivalent to 0 to 1.5 wt% in the molten steel. The measurement was performed at a molten steel temperature of 1550 ° C to 1650 ° C.
  • the laser light source 1a for the analytical element measurement of the apparatus shown in Fig. 4 uses a second harmonic oscillation light (0.53 nm) of the YAG laser to excite the Ti sapphire laser and emit a continuous wavelength laser beam.
  • a wavelength tunable laser that oscillates by adjusting the wavelength of the second harmonic of one continuous wavelength laser light was used.
  • the oscillation wavelength was adjusted to 403.313 nm, which was shifted by 0.006 nm from the center of the atomic absorption wavelength of Mn (403.307 nm).
  • the half-width of the laser wavelength was 0.002 nm and the output was 1 OmW.
  • the above three types of laser light are placed in a positional relationship of 90 degrees, and an optical filter 8a to 8c described later is arranged at the intersection of the laser beams.
  • One kind of laser beam was made the same optical path. That is, the laser light from the laser light source 1a was reflected by the optical filter 18a, and then crossed at 90 degrees with the laser light from the laser light source 1b. At this intersection, there was an optical filter 1b that transmits light of 403 nm (light source 1a) and reflects light of 386 nm (light source lb) for 45-degree incident light. Thus, the laser beams from the light sources la and 1b were set to the same optical path.
  • the light was condensed by a lens 9 and introduced into an optical fiber 11 a having a diameter of 0.3 mm.
  • the laser light was passed through a rotary chopper 10 just before entering the optical fiber 11a.
  • optical fiber 1 lb was used as the receiving optical system, and the optical filter was used as the spectral system.
  • the optical filter 13a and 13b were used. That is, a light receiving optical fiber 11 b having a diameter of ⁇ was attached near the molten steel surface, and reflected light 21 from the molten steel surface was received. Light emitted from the other end of the optical fiber 11b was converted into parallel light by the lens 12, and then introduced into the optical filter 13a to be separated.
  • the optical filter 13a transmits light of 43 nm (light source 1c) for 45 degree incident light, and light of 400nm (light source 1a) and 3886nm (light source lb). Light is a reflective filter. The reflected laser light was further separated by the optical filter 13b.
  • the optical filter 13b is a filter that transmits light of 403 nm (light source 1a) and reflects light of 3886 nm (light source lb) at 45 degrees incidence.
  • the laser light of each measurement wavelength thus separated is converted into a band pass filter having a half-width of 2 nm centered on each wavelength.
  • the photomultiplier tubes (Hotmaru) 6a to 6c were passed through 14c, respectively, and the intensity was measured in 2ms units. The measurement was performed for 2 seconds and 1000 data was collected.
  • the temperature was measured using a Pt-Rh-based thermocouple 16.
  • the relationship between the temperature immediately below the surface of the molten steel and the temperature at the temperature measurement position was measured in advance using a Pt-Rh-based thermocouple, and the relationship was determined.
  • the cycle of the chopper was set to 100 ms, the cutoff was repeated for 25 ms, and the irradiation was repeated for 75 ms.
  • the light intensity when cut off by the chopper 10 is radiation light.
  • the average value of the radiated light intensity when the light was blocked was obtained in a time series, and as described above, the width light intensity at the time of the reflected light measurement was obtained by averaging the radiated light intensity before and after the reflected light measurement. .
  • the true reflected light intensity was obtained by subtracting the radiation light intensity thus calculated from the measured value at the time of the reflected light measurement. This was determined for each of the reference light and the measurement light.
  • Fig. 7 shows an example of the reflected light obtained by shielding with the chopper 10 as the reference light and the Mn measurement light. It shows about.
  • Fig. 8 shows an example of the relationship between MnP and luminosity (actually the ratio of FePJ: luminosity) thus measured and the Mn concentration in molten steel.
  • the correlation between the Mn absorbance and the Mn concentration in the molten steel was improved by implementing the present invention, and the Mn concentration analysis could be performed with high accuracy.
  • the output wavelength of the laser beam was stable and did not change.
  • the laser output wavelength changes during the actual long-term measurement.
  • high-precision analysis is possible by correcting the absorbance using the example of absorbance change depending on the wavelength position as shown in Fig. 6.

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Abstract

Un faisceau laser est passé sur une couche de métal vaporisé, et le changement de la densité de son flux lumineux est mesuré afin de déterminer la concentration de l'élément analysé contenu dans le métal vaporisé. La longueur d'onde du faisceau laser est réglée d'une manière telle qu'elle soit décalée de 0,001 à 0,03 nm du centre de la longueur d'onde d'absorption de l'élément analysé. La gamme de mesures de concentration peut être étendue.
PCT/JP2000/007146 2000-03-24 2000-10-16 Procede et appareil d'analyse de metal vaporise WO2001071320A1 (fr)

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JP2000085350A JP3909999B2 (ja) 1999-03-24 2000-03-24 溶融金属分析方法およびその装置
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Publication number Priority date Publication date Assignee Title
US10976240B2 (en) 2015-08-18 2021-04-13 Tokushima University Concentration measurement device

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KR101033516B1 (ko) * 2008-10-01 2011-05-09 한국전기연구원 광계측 응용 구강암 조기 진단 시스템 및 그 방법
KR101499642B1 (ko) * 2013-10-16 2015-03-09 한국원자력연구원 바람장측정용 도플러 라이다의 측정오차보정 방법
WO2017029791A1 (fr) * 2015-08-18 2017-02-23 国立大学法人徳島大学 Dispositif de mesure de concentration

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JPS56147042A (en) * 1980-04-17 1981-11-14 Olympus Optical Co Ltd Method for conversion of concentration
JPS582637A (ja) * 1981-06-29 1983-01-08 Fujitsu Ltd ガス濃度検出方式
JPH06186159A (ja) * 1991-10-04 1994-07-08 Natl Food Res Inst 近赤外透過スペクトルによる果実糖度の非破壊測定法
JPH06300689A (ja) * 1993-04-14 1994-10-28 Mitsui Mining & Smelting Co Ltd 透過法による青果物の内部品質測定法
JPH09500725A (ja) * 1993-07-26 1997-01-21 エルケム・アクシエセルスカプ 溶融金属の直接的化学分析方法
JPH0949795A (ja) * 1995-08-09 1997-02-18 Nkk Corp 溶融金属の直接分析方法及び装置
JPH11108829A (ja) * 1997-09-30 1999-04-23 Nkk Corp 溶融金属のオンライン分析方法及び装置
JP2000275172A (ja) * 1999-03-24 2000-10-06 Nkk Corp 原子吸光分析方法及びその装置
JP2000275170A (ja) * 1999-03-24 2000-10-06 Nkk Corp 原子吸光分析方法及びその装置
JP2000338039A (ja) * 1999-03-24 2000-12-08 Nkk Corp 溶融金属分析方法およびその装置

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5350886A (en) * 1976-10-20 1978-05-09 Hitachi Ltd Magneto-optics spectrophotometer
JPS56147042A (en) * 1980-04-17 1981-11-14 Olympus Optical Co Ltd Method for conversion of concentration
JPS582637A (ja) * 1981-06-29 1983-01-08 Fujitsu Ltd ガス濃度検出方式
JPH06186159A (ja) * 1991-10-04 1994-07-08 Natl Food Res Inst 近赤外透過スペクトルによる果実糖度の非破壊測定法
JPH06300689A (ja) * 1993-04-14 1994-10-28 Mitsui Mining & Smelting Co Ltd 透過法による青果物の内部品質測定法
JPH09500725A (ja) * 1993-07-26 1997-01-21 エルケム・アクシエセルスカプ 溶融金属の直接的化学分析方法
JPH0949795A (ja) * 1995-08-09 1997-02-18 Nkk Corp 溶融金属の直接分析方法及び装置
JPH11108829A (ja) * 1997-09-30 1999-04-23 Nkk Corp 溶融金属のオンライン分析方法及び装置
JP2000275172A (ja) * 1999-03-24 2000-10-06 Nkk Corp 原子吸光分析方法及びその装置
JP2000275170A (ja) * 1999-03-24 2000-10-06 Nkk Corp 原子吸光分析方法及びその装置
JP2000338039A (ja) * 1999-03-24 2000-12-08 Nkk Corp 溶融金属分析方法およびその装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10976240B2 (en) 2015-08-18 2021-04-13 Tokushima University Concentration measurement device

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