EP2215454A1 - Method for operating an ftir spectrometer, and ftir spectrometer - Google Patents

Method for operating an ftir spectrometer, and ftir spectrometer

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Publication number
EP2215454A1
EP2215454A1 EP08851951A EP08851951A EP2215454A1 EP 2215454 A1 EP2215454 A1 EP 2215454A1 EP 08851951 A EP08851951 A EP 08851951A EP 08851951 A EP08851951 A EP 08851951A EP 2215454 A1 EP2215454 A1 EP 2215454A1
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EP
European Patent Office
Prior art keywords
calibration
validation
spectrometer
gas
gases
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08851951A
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German (de)
French (fr)
Inventor
Norbert Will
Bernd Hielscher
Christoph Becker
Berthold Andres
Carsten Rathke
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB AG Germany
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ABB AG Germany
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Filing date
Publication date
Application filed by ABB AG Germany filed Critical ABB AG Germany
Publication of EP2215454A1 publication Critical patent/EP2215454A1/en
Withdrawn legal-status Critical Current

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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
    • G01N21/27—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration
    • G01N21/274—Calibration, base line adjustment, drift correction
    • G01N21/276—Calibration, base line adjustment, drift correction with alternation of sample and standard in optical path
    • 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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/13—Moving of cuvettes or solid samples to or from the investigating station
    • 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
    • G01N21/27—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration
    • G01N21/274—Calibration, base line adjustment, drift correction
    • 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
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J2003/2866—Markers; Calibrating of scan
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J2003/2866—Markers; Calibrating of scan
    • G01J2003/2879—Calibrating scan, e.g. Fabry Perot interferometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection 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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03—Cuvette constructions
    • G01N2021/0357—Sets of cuvettes
    • 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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03—Cuvette constructions
    • G01N2021/0367—Supports of cells, e.g. pivotable
    • 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
    • G01N2021/3196—Correlating located peaks in spectrum with reference data, e.g. fingerprint data
    • 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
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N2021/3595—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using FTIR
    • 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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03—Cuvette constructions
    • 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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03—Cuvette constructions
    • G01N21/05—Flow-through cuvettes
    • 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
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0006—Calibrating gas analysers

Definitions

  • the invention relates to a method for operating an FTIR spectrometer, and FTIR spectrometer itself, according to the preamble of claim 1 and 8.
  • FTIR spectrometers are infrared spectrometers that use the Fourier transform calculation method. Such spectrometers do not work on specific absorption lines but take up a spectrum of a whole wavelength range and thus obtain information about the absorptions over the considered frequency or wavelength spectrum by means of the mathematical spectrometer function. From the obtained distribution, a chemometric observation is subsequently performed and the distribution is assigned to the corresponding gas components. This means that several gas components can be measured simultaneously with the FTIR spectrometer.
  • FTIR spectrometers are also interesting for difficult to handle gases. These include, for example, NH 3 , HCl, HF, H 2 O. The advantage of FTIR spectrometers, however, is that many gas components can be measured simultaneously. Thus, such spectrometers are particularly suitable for emission measurement. Usually there is a daily check of the spectrometer.
  • the verification of the calibration data is usually carried out today in two steps: At regular intervals (usually daily), a reference spectrum is recorded with zero gas (usually purified ambient air) on a regular basis. This reference spectrum compensates for changes in the transmission behavior of the system. Changes in the transmission behavior can be caused, for example, by soiling in the optical path,
  • test gas generators are used for components that are difficult to handle in test gas cylinders, such as H2O or HCl. However, such handling is very difficult and difficult to accomplish in some places of use of the spectrometer.
  • US Pat. No. 5,777,735 discloses a method or a device of this type in which, as in other known methods, the calibration of the device to the respective gas component to be measured is effected by supplying the corresponding gas in pure form as a calibration gas from a reservoir. This is far too expensive for most gases.
  • the invention is therefore the object of developing a method and a spectrometer of the generic type such that at each site and at any time a calibration or validation of the spectrometer can be done.
  • the object is achieved in a method of the generic type efindungshunt by the characterizing features of claim 1.
  • the core of the invention in terms of method is that in the validation of the spectrometer in addition to or instead of the actual measurement components also easily manageable replacement gas components can be selected, covering the entire spectral range of the spectrometer.
  • gases such as HCl, HF, NH 3
  • Test gases must be provided in high purity. Instead, become simply usable gases are used as substitution for the validation, which produce an absorption effect in the region of the "difficult" gas, so to speak, as a representative, so that these substitute gases as validation or calibration gases are much easier to handle than the actual measuring gases, if they are suitable for Calibration must be available in a highly pure form and with a precise concentration, which is referred to as substitute gases that are not nearly as aggressive or difficult to handle as the gases they are intended to represent, making fuller validation and calibration easier.
  • a gas mixture consisting of a plurality of substitute gases is used for the validation, each of which covers subregions of the entire measuring spectrum.
  • the replacement gases can be brought into a gas mixture for calibration, which would be chemically questionable with the actual gas components.
  • the complete spectral range of the spectrometer can be immediately validated in one step.
  • the intensities in the validation / calibration step are also monitored with zero gas, and the entire spectrum is thus stored as reference by interpolation.
  • the Ersatgase automatically fed individually, ie from different gas reservoirs or as a substitute gas mixture from a gas reservoir by individual valve control in an automatic validation / calibration step the cuvette, and afterwards the corresponding validation or calibration steps are performed.
  • the validation step can be carried out automatically and cyclically in a simple and effective manner.
  • the determined validation or calibration values are stored in an adaptive data field, from which the validation / calibration history can also be evaluated if necessary, in order to obtain a diagnosis of the maintenance status of the spectrometer.
  • the replacement gas components are completed individually or as substitute gas mixture in a calibration cuvette, i. are enclosed, and that for carrying out the validation / calibration step they are automatically pivoted into the beam path and then swung out again.
  • the essence of the invention is that serve as calibration gases, which are only representatives of the actual measurement gases in terms of their absorption effect within the spectrometer and stored within a gas reservoir, and at the moment of automatic initiation of a calibration or Validiervorganges automatically serial successively or as a gas mixture in the beam path of the Sepktrometers are introduced.
  • the gases can be introduced by means of an automatic valve control in the measuring cuvette of the spectrometer.
  • the calibration process can be initiated automatically and the gases are introduced.
  • the gases can be automatically swiveled into the beam path of the spectrometer in one or more calibration cuvettes closed after gas filling and can be swiveled out automatically again after calibration / validation.
  • the invention is illustrated with respect to the method according to the invention, as well as in the construction of the spectrometer in the drawing and described in more detail below.
  • Figure 1 basic structure of a FTIR spectrometer with swiveling or sliding calibration cuvette.
  • FIG. 3 Spectrum with guiding components (representatives)
  • Figure 1 shows a basic structure of an FTIR spectrometer, which is constructed for example on a Michelson interferometer.
  • a parallel beam is generated by widening by means of a first optical system 4, which falls on a semitransparent mirror 3 as a beam splitter.
  • a part of the light with the fixed wavelength and frequency position (monochromatic and coherent) now falls on the fixed mirror 1 and is reflected there.
  • the other partial light beam passes through the mirror 3 in a straight line and is reflected by a movable mirror 2, back in the direction of the mirror 3, where now the two partial light beams interfere with each other.
  • the interference is controllably controlled by the adjustment of the mirror 2 along the optical axis.
  • the interfered light irradiates the measuring cuvette 8 through which the measuring gas is passed.
  • the interferometer a very precise tuning of the effective frequency position of the measuring cuvette and thus the measuring gas striking light beam is achieved.
  • a complete spectrum can be detected at the detector, and not just the absorption rate at a fixed frequency.
  • the expanded light beam is refocused via a second optical system 6, specifically to the dimension of the detector.
  • the cuvette contains a gas inlet A and a gas outlet B and is introduced by the sample gas for recording a measuring spectrum and then led out again.
  • a valve control not shown here is now activated, and calibration gas is passed through led the cuvette 8, or rinsed to initiate after calibration by valve reversal the measured gas to be measured.
  • the calibration cuvette is not filled with the respective measurement gas or the measurement gas component which is measured in this calibrated part of the spectrum, but with a replacement gas or replacement gas mixture representing this or that.
  • substitute gases ie as a representative SO 2 , CO 2 , N 2 O or methane used
  • the use of substituting gases according to the invention greatly simplifies calibration / validation because these substitute components are much easier to handle. They are so easy to handle that they can now be handled in closed calibration cuvettes instead of being calibrated in the gas passage method. This would not be possible with HCL or HF or even with water vapor H 2 O.
  • the individual gases can likewise be enclosed in a calibration cuvette and alternately swiveled in a type of aperture wheel, or a gas mixture of all substitute gases in a common calibration cuvette 9 is used, as in the gas passage method.
  • the calibration cuvette can of course be inserted with a linear movement.
  • FIG. 2 shows the control of the FTIR according to the invention in principle.
  • the operation of the light source 5 (laser) and the detector 7 is carried out via a control unit 10.
  • a time control unit 11 triggers the calibration process at an adjustable time, or by a desired drive signal.
  • the Mirror 2 the light source 5 and the detector 7 controlled, and this coordinated the Einschwenk- or Einschiebebetutz the calibration cuvette 9 controlled and so recorded the reference spectrum and stored in the adaptive memory unit 12.
  • the memory unit 12 also writes the data with temporal assignment as historical data, whereupon an evaluation of possible aging effects can be detected. This can be done in addition to the pure calibration and a sustainable self-diagnosis of the spectrometer.
  • valve controller for supplying substitute gases in the passage method can also be controlled in a coordinated manner in order to be able to carry out the calibration in this way with the use of said substitute gases.
  • FIG. 3 shows how, instead of a test gas task for all components, a validation (check) by a test gas mixture of several substitute gases is carried out.
  • the substitute gases can all be mixed together in a test gas cylinder and are stable over a longer period of time.
  • the substitute gases can also be measurement components, for example SO2 or CO2.
  • gases with many absorptions in different wavelength ranges can also be used, for example stable halogenated hydrocarbons or N 2 O and CO 2.
  • the replacement gases ideally cover the entire spectral range of the spectrometer.
  • Figure 4 shows how additionally monitors the intensities of the reference spectrum. This will also monitor the wavelength ranges that are not covered by the substitute gases.
  • the procedure of the whole procedure can be automated. That it can be given by solenoid valves as described computer controlled the test gas mixture of substitute gases and the zero gas for the reference spectrum. The results can be evaluated automatically and, if necessary, an alarm can be triggered. With smaller deviations, a pre-alarm can be triggered.
  • the storage of the history of validation results can be used as a basis for continuous quality monitoring.
  • the history of validation results can be used as a basis for continuous quality monitoring.
  • Spectra for master components and reference values are stored as already described.
  • a test gas cylinder with the mixture of substitute gas components can be completely dispensed with by stably enclosing the replacement gas components in a calibration cuvette.
  • the calibration cuvette is then pivoted as described above cyclically in the optical path.

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Abstract

The invention relates to a method for operating a FTIR (Fourier transformation infrared) spectrometer, wherein a validation/calibration of the spectrometer is carried out in cyclically recurring intervals in that by way of at least two temporarily available gases a reference spectrum with a zero gas and also an absorption spectrum with a calibration gas are recorded. The invention further relates to a spectrometer according to the preamble of the patent claims 1 and 8. In order to achieve that at each site of use and at any time a calibration or validation of the spectrometer can be carried out, the invention proposes to use so-called substitute gases during the validation of the spectrometer as gas components, said substitute gases only simulating the actual measured gas component with respect to the metrological properties.

Description

Verfahren zum Betrieb eines FTIR-Spektrometers, sowie FTIR-Spektromter selbst Method for operating an FTIR spectrometer, and FTIR spectrometer itself
Die Erfindung betrifft ein Verfahren zum Betrieb eines FTIR-Spektrometers, sowie FTIR-Spektrometer selbst, gemäß Oberbegriff des Patentanspruches 1 und 8 .The invention relates to a method for operating an FTIR spectrometer, and FTIR spectrometer itself, according to the preamble of claim 1 and 8.
FTIR-Spektrometer sind Infrarot-Spektrometer, die mit der Rechen-Methode der Fouriertransformation arbeiten. Solche Spektrometer arbeiten nicht auf spezifischen Absorptionslinien, sondern nehmen ein Spektrum eines ganzen Wellenlängenbereiches auf und erhalten mittels der mathematischen Spektrometerfunktion somit Informationen über die Absorptionen über das betrachtete Frequenz- bzw Wellenlängenspektrum. Aus der erhaltenen Verteilung wird nachfolgend eine chemometrische Betrachtung durchgeführt und die Verteilung den entsprechenden Gaskomponenten zugeordnet. Damit können mit dem FTIR- Spektrometer mehrere Gaskomponenten gleichzeitig gemessen werden.FTIR spectrometers are infrared spectrometers that use the Fourier transform calculation method. Such spectrometers do not work on specific absorption lines but take up a spectrum of a whole wavelength range and thus obtain information about the absorptions over the considered frequency or wavelength spectrum by means of the mathematical spectrometer function. From the obtained distribution, a chemometric observation is subsequently performed and the distribution is assigned to the corresponding gas components. This means that several gas components can be measured simultaneously with the FTIR spectrometer.
Um den besagten gesamten Frequenzbereich zu durchfahren wird mit einem interferometrischen Aufbau mit beweglichen Spiegeln gearbeitet, beispielsweise nach Michelson.To pass through said entire frequency range is worked with an interferometric structure with movable mirrors, for example, according to Michelson.
Damit eine gerätebedingte Drift, z.B. hervorgerufen durch Änderungen im Transmissionsverhalten, beseitigt wird, muss regelmäßig kalibriert und validiert werden. Nur so kann die Zuverlässigkeit der Messergebnisse gewährleistet sein. Bei einfach handhabbaren Gaskomponenten wie CO oder CO2 mag dies einfach sein. In der Regel sind FTIR-Spektrometer aber auch für schwierig handhabbare Gase interessant. Hierzu gehören bspw NH3, HCl, HF, H2O. Der Vorteil bei FTIR-Spektrometern ist aber, dass viele Gaskomponenten gleichzeitig gemessen werden können. Somit eigenen sich solche Spektrometer insbesondere auch zur Emissonsmessung. Üblicherweise erfolgt täglich eine Überprüfung des Spektrometers. Die Überprüfung der Kalibrierdaten (Validierung) erfolgt heute üblicherweise in zwei Schritten: In kurzen Abständen (üblicherweise täglich) erfolgt eine regelmäßige Aufnahme eines Referenzspektrums mit Nullgas (üblicherweise gereinigte Umgebungsluft). Mit diesem Referenzspektrum werden Änderungen im Transmissionsverhalten des Systems kompensiert. Änderungen im Transmissionsverhalten können z.B. durch Verschmutzungen im optischen Weg,In order to eliminate device-related drift, eg caused by changes in the transmission behavior, calibration and validation must be carried out regularly. Only then can the reliability of the measurement results be guaranteed. For easy-to-handle gas components such as CO or CO2, this may be easy. In general, FTIR spectrometers are also interesting for difficult to handle gases. These include, for example, NH 3 , HCl, HF, H 2 O. The advantage of FTIR spectrometers, however, is that many gas components can be measured simultaneously. Thus, such spectrometers are particularly suitable for emission measurement. Usually there is a daily check of the spectrometer. The verification of the calibration data (validation) is usually carried out today in two steps: At regular intervals (usually daily), a reference spectrum is recorded with zero gas (usually purified ambient air) on a regular basis. This reference spectrum compensates for changes in the transmission behavior of the system. Changes in the transmission behavior can be caused, for example, by soiling in the optical path,
Änderung der Strahlerleistung, Änderung des Detektors oder durch Verschmutzung der Messzelle verursacht werden. Die Kompensation des Nullpunkts erfolgt wellenlängenabhängig, damit wird gleichzeitig für alle Komponenten der Nullpunkt korrigiert.Changing the radiator output, changing the detector or caused by contamination of the measuring cell. The compensation of the zero point is wavelength-dependent, so that the zero point is corrected for all components at the same time.
In längeren Abständen (üblicherweise wöchentlich bis jährlich) erfolgt eine regelmäßige Validierung (Überprüfung) und ggf. auch Kalibrierung der Referenzpunkte für alle Komponenten mit Prüfgas. Einfach handhabbare Gase wie CO, CO2, NO können ohne zusätzliche Hilfsmittel mit Prüfgasen in Prüfgasflaschen kalibriert werden. Anstelle von Prüfgasflaschen werden für in Prüfgasflaschen schwierig handhabbare Komponenten wie H2O oder HCl Prüfgasgeneratoren eingesetzt. Eine solche Handhabung ist aber sehr schwierig und an manchen Einsatzorten des Spektrometers kaum zu vollziehen.At longer intervals (usually weekly to annually) there is a regular validation (check) and possibly also calibration of the reference points for all components with test gas. Easy-to-handle gases such as CO, CO2, NO can be calibrated with test gases in test gas cylinders without additional aids. Instead of test gas cylinders, test gas generators are used for components that are difficult to handle in test gas cylinders, such as H2O or HCl. However, such handling is very difficult and difficult to accomplish in some places of use of the spectrometer.
Die Validierung bzw. Kalibrierung der Referenzpunkte kann, insbesondere wenn Gase wie H2O oder HCl kalibriert werden müssen, nur mit hohem technischem und zeitlichem Aufwand durchgeführt werden. Gründe dafür sind beispielsweise:The validation or calibration of the reference points can be carried out only with great technical and time expenditure, in particular if gases such as H2O or HCl have to be calibrated. Reasons for this are, for example:
• Installation des zusätzlichen technischen Equipments wie Prüfgasgenerator• Installation of additional technical equipment such as test gas generator
• Lange Einstellzeiten für HCl und H2O• Long response times for HCl and H2O
• Falsche Konzentrationen des Verdampfermaterials können zu einer fehlerhaften Kalibrierung führen Eine Validierung und / oder Kalibrierung der Referenzpunkte kann deshalb nur durch geschulte Spezialisten durchgeführt werden Die Referenzpunkte werdendeshalb nur in langen Abständen überprüft, d.h. für längere Messintervalle gibt es keine Validierung der Referenzpunkte. Dies führt zu einem erhöhten Risiko einer fehlerhaften Anzeige der Konzentrationen.• Incorrect concentrations of evaporator material can lead to incorrect calibration. Validation and / or calibration of reference points can therefore only be performed by trained specialists The reference points are therefore only checked at long intervals, ie for longer measuring intervals there is no validation of the reference points. This leads to an increased risk of erroneous indication of the concentrations.
Aus der US 5,777,735 ist ein Verfahren bzw eine Einrichtung dieser Art bekannt, bei welchem, wie bei anderen bekannten Verfahren die Kalibrierung der Einrichtung auf die jeweilige zu messende Gaskomponente dadurch erfolgt, dass das entsprechende Gas in Reinform als Kalibriergas aus einem Reservoir zugeführt wird. Für die meisten Gase ist dies viel zu aufwändig.US Pat. No. 5,777,735 discloses a method or a device of this type in which, as in other known methods, the calibration of the device to the respective gas component to be measured is effected by supplying the corresponding gas in pure form as a calibration gas from a reservoir. This is far too expensive for most gases.
Der Erfindung liegt somit die Aufgabe zugrunde, ein Verfahren sowie ein Spektrometer der gattungsgemäßen Art dahingehend weiterzubilden, dass an jedem Einsatzort und zu jeder Zeit eine Kalibrierung bzw Validierung des Spektrometers erfolgen kann.The invention is therefore the object of developing a method and a spectrometer of the generic type such that at each site and at any time a calibration or validation of the spectrometer can be done.
Die gestellte Aufgabe ist bei einem Verfahren der gattungsgemäßen Art efindungsgemäß durch die kennzeichnenden Merkmale des Patentanspruches 1 gelöst.The object is achieved in a method of the generic type efindungsgemäß by the characterizing features of claim 1.
Weitere vorteilhafte Ausgestaltungen des erfindungsgemäßen Verfahrens sind in den abhängigen Ansprüchen 2 bis 7 angegeben.Further advantageous embodiments of the method according to the invention are specified in the dependent claims 2 to 7.
Im Hinblick auf ein Spektrometer der gattungsgemäßen Art ist die gestellte Aufgabe erfindungsgemäß durch die kennzeichnenden Merkmale des Patentanspruches 8 gelöst.With regard to a spectrometer of the generic type, the object is achieved by the characterizing features of claim 8.
Weitere vorteilhafte Ausgestaltungen sind in den übrigen abhängigen Ansprüchen angegeben.Further advantageous embodiments are specified in the remaining dependent claims.
Kern der Erfindung in verfahrensgemäßer Hinsicht ist, dass bei der Validierung des Spektrometers zusätzlich oder anstelle der tatsächlichen Messkomponenten auch einfach handhabbare Ersatzgaskomponenten gewählt werden können, die den ganzen Spektralbereich des Spektrometers abdecken. Für den Anwendungsfall, dass schwierig handhabbare Gase zur Messung kommen, wie beispielsweise HCl, HF, NH3, ist es vorteilhaft, dass mit der erfindungsgemäßen Verfahrensweise vermieden werden kann, dass für eine effektive Validierung oder Kalibrierung die genannten Gase alsThe core of the invention in terms of method is that in the validation of the spectrometer in addition to or instead of the actual measurement components also easily manageable replacement gas components can be selected, covering the entire spectral range of the spectrometer. For the application that difficult to handle gases come to measure, such as HCl, HF, NH 3 , it is advantageous that can be avoided with the inventive procedure, that for effective validation or calibration, the gases mentioned as
Prüfgase in hoher Reinheit zur Verfügung gestellt werden müssen. Stattdessen werden einfach handbare Gase für die Validierung als Substitution verwendet, die einen Absorptionseffekt etwa in dem Bereich des „schwierigen" Gases, quasi als Repräsentant erzeugen. Somit sind diese Ersatzgase als Validier- oder Kalibriergase wesentlich einfacher zu handhaben, als die eigentlichen Messgase, wenn diese für die Kalibrierung in hochreiner Form und exakter Konzentration zur Verfügung stehen müssten. Dabei werden nachfolgend Ersatzgase genannt, die bei Weitem nicht so aggresiv oder so schwer zu handhaben sind als diejenigen Gase, die sie repräsentieren sollen. Die gesamte Validierung und Kalibrierung wird dadurch einfacher.Test gases must be provided in high purity. Instead, become simply usable gases are used as substitution for the validation, which produce an absorption effect in the region of the "difficult" gas, so to speak, as a representative, so that these substitute gases as validation or calibration gases are much easier to handle than the actual measuring gases, if they are suitable for Calibration must be available in a highly pure form and with a precise concentration, which is referred to as substitute gases that are not nearly as aggressive or difficult to handle as the gases they are intended to represent, making fuller validation and calibration easier.
In weiterer vorteilhafter Ausgestaltung ist angegeben, dass ein aus mehreren Ersatzgasen bestehendes Gasgemisch zur Validierung eingesetzt wird, welche jeweils Teilbereiche des gesamten Messspektrums abdecken. Auf diese Weise können die Ersatzgase zur Kalibrierung in ein Gasgemisch gebracht werden, was mit den eigentlichen Gaskomponenten schon chemisch bedenklich wäre. Auf diese Weise kann sofort der komplette Spektralbereich des Spektrometers in einem Schritt validiert werden.In a further advantageous embodiment, it is stated that a gas mixture consisting of a plurality of substitute gases is used for the validation, each of which covers subregions of the entire measuring spectrum. In this way, the replacement gases can be brought into a gas mixture for calibration, which would be chemically questionable with the actual gas components. In this way, the complete spectral range of the spectrometer can be immediately validated in one step.
In weiterer vorteilhafter Ausgestaltung ist angegeben, dass solche und so viele Ersatzgase im Kalibrier/Validier-Gasgemisch eingebracht sind, dass diese den gesamten Spektralbereich des Spektrometers abdecken.In a further advantageous embodiment, it is stated that such and so many substitute gases are incorporated in the calibration / validation gas mixture that they cover the entire spectral range of the spectrometer.
In weiterer vorteilhafter Ausgestaltung ist angegeben, dass auch die Intensitäten im Validierungs/Kalibrierungsschritt mit Nullgas überwacht werden, und so durch Interpolation das gesamte Spektrum als Referenz abgespeichert wird.In a further advantageous embodiment, it is stated that the intensities in the validation / calibration step are also monitored with zero gas, and the entire spectrum is thus stored as reference by interpolation.
In weiterer vorteilhafter Ausgestaltung ist angegeben, dass die Ersatgase einzeln d.h. aus verschiedenen Gasreservoiren oder als Ersatzgasgemisch aus einem Gasreservoir durch Einzelventilansteuerung in einem automatischen Validierungs- /Kalibrierschritt automatisch der Messküvette zugeführt, und hernach die entsprechenden Validier- bzw Kalibrierschritte durchgeführt werden. So kann der Validierungsschritt auf einfache und effektive Weise automatisch zyklisch durchgeführt werden. In weiterer vorteilhafter Ausgestaltung ist angegeben, dass die ermittelten Validier- bzw Kalibrierwerte in einem adaptiven Datenfeld abgespeichert werden, aus welchem nach Bedarf auch die Validier-/Kalibrierhistorie auswertbar ist, um ggfs daraus eine Diagnose über den Wartungszustand des Spektrometers zu erhalten.In a further advantageous embodiment, it is indicated that the Ersatgase automatically fed individually, ie from different gas reservoirs or as a substitute gas mixture from a gas reservoir by individual valve control in an automatic validation / calibration step the cuvette, and afterwards the corresponding validation or calibration steps are performed. Thus, the validation step can be carried out automatically and cyclically in a simple and effective manner. In a further advantageous refinement, it is specified that the determined validation or calibration values are stored in an adaptive data field, from which the validation / calibration history can also be evaluated if necessary, in order to obtain a diagnosis of the maintenance status of the spectrometer.
In letzter vorteilhafter Ausgestaltung ist angegeben, dass die Ersatzgaskomponenten einzeln oder als Ersatzgasgemisch in einer Kalibrierküvette abgeschlossen, d.h. eingeschlossen sind, und dass zur Durchführung des Validierungs-/Kalibrierschrittes diese automatisch in den Strahlengang eingeschwenkt und danach wieder herausgeschwenkt werden.In the last advantageous embodiment, it is stated that the replacement gas components are completed individually or as substitute gas mixture in a calibration cuvette, i. are enclosed, and that for carrying out the validation / calibration step they are automatically pivoted into the beam path and then swung out again.
Hinsichtlich eines FTIR Spektrometers besteht der Kern der Erfindung darin, dass als Kalibriermittel Gase dienen, die hinsichtlich ihrer Absorptionswirkung innerhalb des Spektrometers lediglich Repräsentanten der eigentlichen Messgase sind und innerhalb eines Gasreservoirs gespeichert sind, und im Moment der automatischen Initiierung eines Kalibrier- oder Validiervorganges automatisch seriell nacheinander oder als Gasgemisch in den Strahlengang des Sepktrometers einbringbar sind.With regard to an FTIR spectrometer, the essence of the invention is that serve as calibration gases, which are only representatives of the actual measurement gases in terms of their absorption effect within the spectrometer and stored within a gas reservoir, and at the moment of automatic initiation of a calibration or Validiervorganges automatically serial successively or as a gas mixture in the beam path of the Sepktrometers are introduced.
In vorteilhafter Ausgestaltung des erfindungsgemäßen Spektrometers ist angegeben, dass die Gase mittels einer automatischen Ventilsteuerung in die Messküvette des Spektrometers einleitbar sind. So kann der Kalibrierprozess automatisch initiiert werden und die Gase eingeleitet werden.In an advantageous embodiment of the spectrometer according to the invention is indicated that the gases can be introduced by means of an automatic valve control in the measuring cuvette of the spectrometer. Thus, the calibration process can be initiated automatically and the gases are introduced.
In alternativer Ausgestaltung ist angegeben, dass die Gase in einer oder mehreren, nach Gasbefüllung abgeschlossenen Kalibierküvetten in den Strahlengang des Spektrometers automatisch einschwenkbar und nach Kalibrierung/Validierung wieder automatisch ausschwenkbar sind. Somit brauch man keine Gasbevorratung mehr.In an alternative embodiment, it is stated that the gases can be automatically swiveled into the beam path of the spectrometer in one or more calibration cuvettes closed after gas filling and can be swiveled out automatically again after calibration / validation. Thus you do not need gas storage anymore.
Die Erfindung ist in Bezug auf die erfindungsgemäße Verfahrenweise, sowie im Aufbau des Spektrometers in der Zeichnung dargestellt und nachfolgend näher beschrieben.The invention is illustrated with respect to the method according to the invention, as well as in the construction of the spectrometer in the drawing and described in more detail below.
Es zeigt: Figur 1 : prinzipieller Aufbau eines FTIR-Spektrometers mit schwenk-oder schiebbarer Kalibrierküvette.It shows: Figure 1: basic structure of a FTIR spectrometer with swiveling or sliding calibration cuvette.
Figur 2: Steuerung der KalibrierungFigure 2: Control of the calibration
Figur 3: Spektrum mit Leitkomponenten (Repräsentanten)FIG. 3: Spectrum with guiding components (representatives)
Figur 4: Aufteilung des Spektrums in RegionenFigure 4: Distribution of the spectrum in regions
Figur 1 zeigt einen prinzipiellen Aufbau eines FTIR-Spektrometers, das beispielsweise auf einem Michelson-Interferometer aufgebaut wird. Ausgehend von einer Strahlungsquelle 5 wird mittels eines ersten optischen Systems 4 ein paralles Strahlenbündel durch Aufweitung erzeugt, das auf einen halbdurchlässigen Spiegel 3 als Strahlenteiler fällt. Ein Teil des Lichtes mit der festen Wellenlänge und Frequenzlage (monochromatisch und kohärent) fällt nun auf den feststehenden Spiegel 1 und wird dort reflektiert. Das andere Teillichtbündel passiert den Spiegel 3 geradlinig und wird von einem beweglichen Spiegel 2 reflektiert, zurück in Richtung des Spiegels 3, wo nun die beiden Lichtteilstrahlen miteinander interferieren. Die Interferenz wird hierbei kontrollierbar gesteuert über die Verstellung des Spiegel 2 entlang der optischen Achse. Von dort aus durchstrahlt das interferierte Licht die Messküvette 8 durch die Messgas geleitet wird. Mittels des Interferometers wird eine sehr exakte Durchstimmung der effektiven Frequenzlage des die Messküvette und damit das Messgas treffenden Lichtbündels erreicht. So kann am Detektor ein komplettes Spektrum erfasst werden, und nicht nur die Absorptionrate bei einer festen Frequenz. Um den Detektor optimal auszuleuchten, wird über ein zweites optisches System 6 das aufgeweitete Lichtbündel wieder fokussiert, und zwar auf die Dimension des Detektors.Figure 1 shows a basic structure of an FTIR spectrometer, which is constructed for example on a Michelson interferometer. Starting from a radiation source 5, a parallel beam is generated by widening by means of a first optical system 4, which falls on a semitransparent mirror 3 as a beam splitter. A part of the light with the fixed wavelength and frequency position (monochromatic and coherent) now falls on the fixed mirror 1 and is reflected there. The other partial light beam passes through the mirror 3 in a straight line and is reflected by a movable mirror 2, back in the direction of the mirror 3, where now the two partial light beams interfere with each other. The interference is controllably controlled by the adjustment of the mirror 2 along the optical axis. From there, the interfered light irradiates the measuring cuvette 8 through which the measuring gas is passed. By means of the interferometer, a very precise tuning of the effective frequency position of the measuring cuvette and thus the measuring gas striking light beam is achieved. Thus, a complete spectrum can be detected at the detector, and not just the absorption rate at a fixed frequency. In order to illuminate the detector optimally, the expanded light beam is refocused via a second optical system 6, specifically to the dimension of the detector.
Die Messküvette enthält einen Gaseingang A und einen Gasausgang B und wird vom Messgas zur Aufnahme eines Messspektrums eingeleitet und danach wieder herausgeleitet.The cuvette contains a gas inlet A and a gas outlet B and is introduced by the sample gas for recording a measuring spectrum and then led out again.
Um den erfindungsgemäßen Kalibrierschritt durchführen zu können, wird nun entweder eine hier nicht weiter dargestellte Ventilsteuerung angesteuert, und Kalibriergas durch die Küvette 8 geleitet, bzw durchspült, um nach dem Kalibrieren dann durch Ventilumsteuerung das zu messende Messgas einzuleiten.In order to be able to carry out the calibration step according to the invention, either a valve control not shown here is now activated, and calibration gas is passed through led the cuvette 8, or rinsed to initiate after calibration by valve reversal the measured gas to be measured.
Eine andere Alternative ist hier dargestellt, bei welcher das Kalibriergas mit Hilfe von Kalibrierküvetten 9 in den Strahlengang vor den Detektor 7 bzw vor das optische System 6 eingeschwenkt wird, solange die Kalibrierung bzw Validierung dauert. Hernach wird die Kalibrierküvette wieder aus dem Strahlengang herausgeschwenkt.Another alternative is shown here, in which the calibration gas is swiveled by means of calibration cuvettes 9 into the beam path in front of the detector 7 or in front of the optical system 6 as long as the calibration or validation lasts. Afterwards, the calibration cuvette is again swiveled out of the beam path.
Wichtig ist hierbei zu erwähnen, dass die Kalibrierküvette nicht mit dem betreffenden Messgas oder der Messgaskomponente gefüllt ist, die in diesem kalibrierten Teil des Spektrums gemessen wird, sondern mit einem dieses bzw diese repräsentierenden Ersatzgas oder Ersatzgasgemisch. So werden über den Spektralbereich des Spektrometers bspw als Ersatzgase, d.h. als Repräsentanten SO2, CO2, N2O oder Methan verwendet, anstatt der viel heikleren Gaskomponenten HCl, HF, NH3 etc. Letztere zur Kalibrierung in Reinstform zu verwenden ist erheblich aufwändiger. Stattdessen vereinfacht die erfindungsgemäße Verwendung der substituierenden Ersatzgase die Kalibrierung/Validierung ganz erheblich, weil diese genannten Ersatzkomponenten wesentlich leichter zu handhaben sind. Sie sind so leicht zu handhaben, dass diese statt zur Kalibrierung im Gasdurchleitungsverfahren nunmehr auch in abgeschlossenen Kalibrierküvetten handhabbar sind. Dies wäre mit HCL oder HF oder gar mit Wasserdampf H2O so nicht möglich.It is important to mention here that the calibration cuvette is not filled with the respective measurement gas or the measurement gas component which is measured in this calibrated part of the spectrum, but with a replacement gas or replacement gas mixture representing this or that. Thus, over the spectral range of the spectrometer, for example, as substitute gases, ie as a representative SO 2 , CO 2 , N 2 O or methane used, instead of the much trickier gas components HCl, HF, NH 3, etc. to use the latter for calibration in pure form is considerably more complex , Instead, the use of substituting gases according to the invention greatly simplifies calibration / validation because these substitute components are much easier to handle. They are so easy to handle that they can now be handled in closed calibration cuvettes instead of being calibrated in the gas passage method. This would not be possible with HCL or HF or even with water vapor H 2 O.
Bei der Verwendung von Kalibrierküvetten können ebenso die einzelnen Gase jeweils in einer Kalibrierküvette eingeschlossen sein und auf einer Art Blendenrad abwechselnd einschwenkbar sein, oder aber man verwendet wie auch beim Gasdurchleitungsverfahren ein Gasgemisch aus allen Ersatzgasen in einer gemeinsamen Kalibrierküvette 9.When using calibration cuvettes, the individual gases can likewise be enclosed in a calibration cuvette and alternately swiveled in a type of aperture wheel, or a gas mixture of all substitute gases in a common calibration cuvette 9 is used, as in the gas passage method.
Statt der Einschwenkbewegung kann die Kalibrierküvette natürlich auch mit einer linearen Bewegung einschiebbar sein.Instead of the Einschwenkbewegung the calibration cuvette can of course be inserted with a linear movement.
Figur 2 zeigt die Steuerung des erfindungsgemäßen FTIR im Prinzip. Dabei wird über eine Steuereinheit 10 die Betätigung der Lichtquelle 5 (Laser) als auch der Detektor 7 vorgenommen. Eine Zeitsteuereinheit 11 löst zu einer einstellbaren Zeit, oder durch ein gewolltes Ansteuersignal den Kalibriervorgang aus. Hierzu wird nun koordiniert der Spiegel 2, die Lichtquelle 5 sowie der Detektor 7 gesteuert, und hierzu koordiniert die Einschwenk- oder Einschiebebetätigung der Kalibrierküvette 9 gesteuert und so das Referenzspektrum aufgezeichnet und in der adaptiven Speichereinheit 12 abgelegt. Die Speichereinheit 12 schreibt darüber hinaus die Daten mit zeitlicher Zuordnung als historische Daten auf, worauf zusätzlich eine Auswertung möglicher Alterungseffekte erkannt werden können. Hierüber kann neben der reinen Kalibrierung auch eine nachhaltige Selbstdiagnose des Spektrometers vorgenommen werden.FIG. 2 shows the control of the FTIR according to the invention in principle. In this case, the operation of the light source 5 (laser) and the detector 7 is carried out via a control unit 10. A time control unit 11 triggers the calibration process at an adjustable time, or by a desired drive signal. For this purpose is now coordinated the Mirror 2, the light source 5 and the detector 7 controlled, and this coordinated the Einschwenk- or Einschiebebetätigung the calibration cuvette 9 controlled and so recorded the reference spectrum and stored in the adaptive memory unit 12. The memory unit 12 also writes the data with temporal assignment as historical data, whereupon an evaluation of possible aging effects can be detected. This can be done in addition to the pure calibration and a sustainable self-diagnosis of the spectrometer.
Alternativ zur Ansteuerung der Einschwenk- oder Einschiebbewegung der Kalibrierküvette kann auch stattdessen die Ventilsteuerung zur Zuführung von Ersatzgasen im Durchleitungsverfahren koordiniert angesteuert werden, um die Kalibrierung auch auf diesem Wege mit Verwendung von genannten Ersatzgasen durchführen zu können.As an alternative to controlling the pivoting or insertion movement of the calibration cuvette, the valve controller for supplying substitute gases in the passage method can also be controlled in a coordinated manner in order to be able to carry out the calibration in this way with the use of said substitute gases.
Figur 3 zeigt, wie anstelle einer Prüfgasaufgabe für alle Komponenten eine Validierung (Überprüfung) durch ein Prüfgasgemisch aus mehreren Ersatzgasenerfolgt. Die Ersatzgase können alle zusammen in einer Prüfgasflasche gemischt werden und sind über einen längeren Zeitraum stabil. Die Ersatzgase können auch Messkomponenten sein, zum Beispiel SO2 oder CO2. Alternativ oder zusätzlich können aber auch Gase mit vielen Absorptionen in verschiedenen Wellenlängenbereichen eingesetzt werden, zum Beispiel stabile halogenierte Kohlenwasserstoffe oder N2O und CO2. Die Ersatzgase decken idealerweise den ganzen Spektralbereich des Spektrometers ab.FIG. 3 shows how, instead of a test gas task for all components, a validation (check) by a test gas mixture of several substitute gases is carried out. The substitute gases can all be mixed together in a test gas cylinder and are stable over a longer period of time. The substitute gases can also be measurement components, for example SO2 or CO2. Alternatively or additionally, gases with many absorptions in different wavelength ranges can also be used, for example stable halogenated hydrocarbons or N 2 O and CO 2. The replacement gases ideally cover the entire spectral range of the spectrometer.
Beispielsweise können dazu folgende Ersatzgase eingesetzt werden.For example, the following substitute gases can be used for this purpose.
• Langwelliger Bereich z.B. mit SO2 • Mittlerer Bereich z.B. mit CO2Long-wave range e.g. with SO2 • Middle range e.g. with CO2
• Kurzwelliger Bereich durch Methan oder N2O• Short-wave range due to methane or N2O
Figur 4 zeigt, wie zusätzlich die Intensitäten des Referenzspektrums überwacht. Damit werden auch die Wellenlängenbereiche überwacht werden, die durch die Ersatzgase nicht abgedeckt werden.Figure 4 shows how additionally monitors the intensities of the reference spectrum. This will also monitor the wavelength ranges that are not covered by the substitute gases.
Wenn nun bei der Validierung des Spektrometers keine Änderungen für die Ersatzgase bzw. für die einzelnen Bereiche des Referenzspektrums keine Änderungen der Nullpunkte auftreten, gibt es auch keine Änderungen für die restlichen Messkomponenten (beispielsweise HCl oder HF).If, during the validation of the spectrometer, no changes for the substitute gases or for the individual ranges of the reference spectrum no changes of the Zero points occur, there are also no changes for the remaining measurement components (for example, HCl or HF).
Im Gegensatz zur Validierung / Kalibrierung mit Prüfgasgeneratoren kann der Ablauf der ganzen Prozedur automatisiert werden. D.h. es kann über Magnetventile wie beschrieben rechnergesteuert das Prüfgasgemisch aus Ersatzgase und das Nullgas für das Referenzspektrum aufgegeben werden. Die Ergebnisse können automatisch ausgewertet werden und es kann ggf. eine Alarmierung ausgelöst werden. Bei geringeren Abweichungen kann auch erst ein Voralarm ausgelöst werden.In contrast to the validation / calibration with test gas generators, the procedure of the whole procedure can be automated. That it can be given by solenoid valves as described computer controlled the test gas mixture of substitute gases and the zero gas for the reference spectrum. The results can be evaluated automatically and, if necessary, an alarm can be triggered. With smaller deviations, a pre-alarm can be triggered.
Die Speicherung der Historie der Ergebnisse der Validierung kann als Basis für eine kontinuierliche Qualitätsüberwachung verwendet werden. Zusätzlich können dieThe storage of the history of validation results can be used as a basis for continuous quality monitoring. In addition, the
Spektren für Leitkomponenten und Referenzwerte gespeichert werden, wie bereits beschrieben.Spectra for master components and reference values are stored as already described.
Alternativ kann auch auf eine Prüfgasflasche mit dem Gemisch an Ersatzgaskomponenten ganz verzichtet werden, indem die Ersatzgaskomponenten in einer Kalibrierküvette stabil eingeschlossen werden. Anstelle einer Prüfgasaufgabe über Magnetventile wird die Kalibrierküvette dann wie oben beschrieben zyklisch in den optischen Weg eingeschwenkt.Alternatively, a test gas cylinder with the mixture of substitute gas components can be completely dispensed with by stably enclosing the replacement gas components in a calibration cuvette. Instead of a Prüfgasaufgabe via solenoid valves, the calibration cuvette is then pivoted as described above cyclically in the optical path.
* * * * * * * * * *
BezugszeichenlisteLIST OF REFERENCE NUMBERS
1. Spiegel, feststehend1st mirror, fixed
2. Spiegel, beweglich 3. halbdurchlässiger Spiegel / Strahlenteiler2. Mirror, portable 3. Semi-transparent mirror / beam splitter
4. optisches System, aufweitend4. optical system, expanding
5. Strahlenquelle5. Radiation source
6. optisches System, fokussierend6. optical system, focusing
7. Detektor 8. Messküvette7. Detector 8. Measuring cuvette
9. Kalibrierküvette9. Calibration cuvette
10. Steuerung10. Control
11. Zeitsteuerung11. Time control
12. adaptiver Datenspeicher12. adaptive data memory
A Messgaseingang B Messgasausgang A Sample gas inlet B Sample gas outlet

Claims

Patentansprüche claims
1. Verfahren zum Betrieb eines FTIR(Fourier-Transformation-lnfrarot)-Spektrometers bei welchem in zyklisch wiederkehrenden Intervallen eine Validierung/Kalibrierung des Spektrometers erfolgt, indem mit mindestens zwei temporär zur Verfügung gestellten Gasen sowohl ein Referenzsprektum mit Nullgas als auch ein Absorptionsspektrum mit Kalibriergas aufgenommen wird, dadurch gekennzeichnet, dass bei der Validierung des Spektrometers als Gaskomponenten jeweils sogenannte Ersatzgase verwendet werden, die bezüglich der messtechnischen1. A method for operating a FTIR (Fourier transform infrared) spectrometer in which cyclically recurring intervals, a validation / calibration of the spectrometer is carried out by using at least two gases temporarily provided both a Referenzsprektum with zero gas and an absorption spectrum with calibration gas is received, characterized in that in the validation of the spectrometer as gas components each so-called substitute gases are used, with respect to the metrological
Eigenschaften die tatsächliche Messgaskomponente nur simulieren.Properties only simulate the actual sample gas component.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass ein aus mehreren Ersatzgasen bestehendes Gasgemisch zur Validierung eingesetzt wird, welches jeweils Teilbereiche des gesamten Messspektrums abdeckt.2. The method according to claim 1, characterized in that one of several substitute gases existing gas mixture is used for validation, which covers each subareas of the entire measurement spectrum.
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass solche und so viele Ersatzgase im Kalibrier/Validier-Gasgemisch eingebracht sind, dass diese den gesamten Spektralbereich des Spektrometers abdecken.3. The method according to claim 2, characterized in that such and so many substitute gases are introduced in the calibration / validation gas mixture that they cover the entire spectral range of the spectrometer.
4. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass auch die Intensitäten des Referenzsprektrums im Validierungs/Kalibrierungsschritt mit Nullgas überwacht werden, und so durch Interpolation das gesamte Spektrum als Referenz abgespeichert wird. 4. The method according to any one of the preceding claims, characterized in that the intensities of the Referenzsprektrums are monitored in the validation / calibration step with zero gas, and so by interpolation, the entire spectrum is stored as a reference.
5. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Ersatzgase einzeln d.h. aus verschiedenen Gasreservoiren oder als Gasgemisch aus einem Gasreservoir durch Einzelventilansteuerung in einem automatischen Validierungs-/Kalibrierschritt automatisch der Messküvette zugeführt, und hernach die entsprechenden Validier- oder Kalibrierschritte durchgeführt werden.A method according to any one of the preceding claims, characterized in that the substitute gases are individually i. from different gas reservoirs or as gas mixture from a gas reservoir by individual valve control in an automatic validation / calibration automatically supplied to the cuvette, and then the corresponding validation or calibration steps are performed.
6. Verfahren nach Anspruch 5, dadurch gekennzeichnet, dass die ermittelten Validier- oder Kalibrierwerte in einem adaptiven Datenfeld abgespeichert werden, aus welchem nach Bedarf auch die Validier- /Kalibrierhistorie auswertbar ist, um ggfs daraus eine Diagnose über den Wartungszustand des Spektrometers zu erhalten.6. The method according to claim 5, characterized in that the determined validation or calibration values are stored in an adaptive data field, from which the validation / calibration history can also be evaluated as required, in order to obtain a diagnosis of the maintenance status of the spectrometer.
7. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Ersatzgase einzeln oder als Ersatzgasgemisch in einer Kalibrierküvette abgeschlossen, d.h. eingeschlossen sind, und dass zur Durchführung des Validierungs-/Kalibrierschrittes diese automatisch in den Strahlengang eingeschwenkt und danach wieder herausgeschwenkt werden.7. The method according to any one of the preceding claims, characterized in that the replacement gases are completed individually or as a substitute gas mixture in a calibration cuvette, i. are enclosed, and that for carrying out the validation / calibration step they are automatically pivoted into the beam path and then swung out again.
8. FTIR-Spektrometer mit Validierungs- und/oder Kalibriermitteln, zur zyklischen Validierung und/oder Kalibrierung des Messspektrums des FTIR-Spektrometers, dadurch gekennzeichnet, dass als Kalibriermittel Gase dienen, die hinsichtlich ihrer Absorptionswirkung innerhalb des Spektrometers lediglich Repräsentanten der eigentlichen Messgase sind und innerhalb eines Gasreservoirs gespeichert sind, und im Moment der automatischen Initiierung eines Kalibrier- oder Validiervorganges automatisch seriell nacheinander oder als Gasgemisch in den Strahlengang des Sepktrometers einbringbar sind. 8. FTIR spectrometer with validation and / or calibration, for cyclic validation and / or calibration of the measurement spectrum of the FTIR spectrometer, characterized in that serving as a calibration gases, which are only representative of the actual measuring gases in terms of their absorption effect within the spectrometer and are stored within a gas reservoir, and at the moment of the automatic initiation of a calibration or Validiervorganges are automatically introduced successively in series or as a gas mixture in the beam path of the Sepktrometers.
9. FTIR-Spektrometer nach Anspruch 8, dadurch gekennzeichnet, dass die Gase mittels einer automatischen Ventilsteuerung in die Messküvette des Spektrometers einleitbar sind.9. FTIR spectrometer according to claim 8, characterized in that the gases can be introduced by means of an automatic valve control in the measuring cuvette of the spectrometer.
10. FTIR-Spektrometer nach Anspruch 8, dadurch gekennzeichnet, dass die Gase in einer oder mehreren, nach Gasbefüllung abgeschlossenen Kalibierküvetten in den Strahlengang des Spektrometers automatisch einschwenkbar und nach Kalibrierung/Validierung wieder automatisch ausschwenkbar sind. 10. FTIR spectrometer according to claim 8, characterized in that the gases in one or more, completed after gas filling Kalibierküvetten in the beam path of the spectrometer are automatically swiveled and after calibration / validation again automatically swung.
EP08851951A 2007-11-22 2008-11-21 Method for operating an ftir spectrometer, and ftir spectrometer Withdrawn EP2215454A1 (en)

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