WO2003014712A1 - Procede et dispositif d'analyse quantitative de gaz - Google Patents

Procede et dispositif d'analyse quantitative de gaz Download PDF

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Publication number
WO2003014712A1
WO2003014712A1 PCT/EP2002/007841 EP0207841W WO03014712A1 WO 2003014712 A1 WO2003014712 A1 WO 2003014712A1 EP 0207841 W EP0207841 W EP 0207841W WO 03014712 A1 WO03014712 A1 WO 03014712A1
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WO
WIPO (PCT)
Prior art keywords
radiation source
current
measuring
radiation
switches
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.)
Ceased
Application number
PCT/EP2002/007841
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German (de)
English (en)
Inventor
Frank Eder
Herbert Rosenstiel
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.)
Testo SE and Co KGaA
Original Assignee
Testo SE and Co KGaA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Testo SE and Co KGaA filed Critical Testo SE and Co KGaA
Publication of WO2003014712A1 publication Critical patent/WO2003014712A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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

Definitions

  • the invention relates to a method and a device for quantitative gas analysis.
  • infrared-optical gas sensors are used to measure the C0 2 concentration, since carbon dioxide only triggers a chemical reaction to a limited extent under measuring conditions. Since there are no cross-sensitivities in C0 2 measurements with infrared gas sensors, these gas sensors are particularly well suited for measuring the concentration of carbon dioxide. Cross-sensitivities are understood to be the influences of other gases that are not to be examined, but which may be contained in the measuring medium.
  • Infrared optical gas sensors are designed to measure the concentration of organic and inorganic gases in a sample atmosphere using infrared radiation. They typically work using the absorption spectroscopy method. Multi-atomic, non-elementary gases have the property of absorbing the infrared radiation emitted by the gas sensors, thereby creating an absorption spectrum which is characteristic of the gas to be measured in each case. Every gas has its
  • the attenuation of the infrared radiation emitted by the measuring medium is a measure of the concentration of the gas to be examined. This physical property of the gases to be measured is used in the infrared gas analysis.
  • FIG. 1 shows the structure of an arrangement for quantitative gas analysis.
  • the measuring arrangement 1 has a sensor device consisting of a radiation source 2, for example an incandescent lamp, and a detector device 3. Furthermore, a measuring chamber 4 is provided, in which the measuring medium 5 to be analyzed is contained.
  • the spectral location of the radiation 6 with the intensity Ie emanating from the radiation source 2 is selected such that the radiation can be at least partially absorbed by the measuring medium 5 in the measuring chamber.
  • the radiation passes through the measuring chamber of thickness d, a portion of the injected radiation 6 being absorbed by the measurement medium 5, which causes the intensity Ie of the injected radiation 6 to be attenuated.
  • the radiation 6 ′ of intensity Ia ⁇ Ie emerging from the measuring chamber 4 then hits the detector device 3 and is measured there.
  • the radiation required for the measurement is usually generated by means of incandescent lamps. It is essential for the optical measurement that the radiation emitted by the radiation source has a defined, stable intensity. To stabilize this radiation power, a regulating device is provided, by means of which the current or the voltage of the radiation source is regulated. However, this is only possible in DC voltage operation with a justifiable amount of circuitry. In the measuring arrangements known today, the radiation source is therefore supplied with a direct voltage or a direct current.
  • the Soret effect or the Soret 'see effect is based on a large temperature gradient in the longitudinal direction of the axis of the filament, which leads to mass transfer of the material of the filament. This leads to an increasing inhomogeneity of the surface of the incandescent filament, which manifests itself in a more or less serrated or jagged surface structure.
  • the resulting reduction in cross-section can lead to a break in the incandescent ice or to a change in the optical properties under extreme conditions, for example mechanical shocks or vibrations, preferably in the regions with a smaller cross-section.
  • a change in the optical properties automatically also results in a change in the optical imaging properties and the spectral radiation distribution of the radiation source.
  • the radiation emitted by the radiation source no longer has the predetermined radiation intensity Ie that is required for the measurement, as a result of which the entire measuring system is undesirably misaligned.
  • the measuring system must therefore be readjusted regularly or the radiation source must be replaced. However, this is not always possible, especially with very long measurements.
  • the constant adjustment of the measuring arrangement is time-consuming and therefore cost-intensive. In the event of a broken glow plug, the entire radiation source must be replaced, which also makes the measuring process significantly more expensive.
  • the present invention is therefore based on the object of providing a method and a measuring arrangement for optical gas analysis by means of which the optical imaging properties of the radiation source can be kept largely constant.
  • the method-related problem is solved according to the invention by a measuring method with the features of claim 1, the arrangement-related problem by a measuring arrangement with the features of claim 7. Accordingly, it is provided:
  • Voltage signal is supplied, in which the radiation source generates measurement radiation for gas analysis of a sample atmosphere as a function of the supplied current and / or voltage signal, the sign of the supplied current or voltage signal being changed (claim 1);
  • the idea underlying the present invention is that the current direction of the current supplied to the radiation source is alternately changed. As a result, the mass transports, which are caused by the effects mentioned at the outset and which in extreme cases even render the radiation source inoperable, are largely avoided. A change in the optical imaging properties and the spectral radiation distribution is thereby minimized, as a result of which the functionality of the radiation source and thus also of the entire measuring arrangement is retained. In addition to a small effort for the adjustment of the radiation source increased the lifetime of the radiation source is also advantageous.
  • the sign of the current or voltage signal supplied to the radiation source is advantageously changed in a clock-controlled manner, for which purpose a specially provided clock line must be provided, which is connected to a control device and a clock generator.
  • This method is particularly advantageous in continuous measurement mode.
  • a clock-controlled switchover is often not necessary and, moreover, is too complex.
  • the sign of the current supplied to the radiation source is changed each time the radiation source is switched on or also each time a new measuring process is carried out.
  • the switching device is designed as a full bridge and has at least four controllable switches for this purpose.
  • the controllable switches can be switched on and off via a control device.
  • the controllable switches of the full bridge are typically designed as MOSFETs, but other switches such as bipolar transistors, JFETs or even a relay would also be conceivable here.
  • two switches of the full bridge are switched on, while the other two are switched off.
  • the switches that are switched on and off are arranged crosswise.
  • the switches which are arranged crosswise are switched on and off alternately. These switches are typically switched on and / or off fully synchronously.
  • the radiation source is supplied with a current which is generated by a current source via the full bridge circuit.
  • the current source is typically designed as a resistor or as a MOSFET.
  • the sample atmosphere contained in the measuring chamber consists of C0 2 or a gas containing C0 2 .
  • the method and the arrangement according to the invention are of course also suitable for the gas analysis of other gases.
  • Figure 1 shows the structure of a generally known arrangements for quantitative gas analysis
  • Figure 2 shows a circuit arrangement according to the invention, which provides an alternating current for the radiation source of a measuring arrangement.
  • a circuit arrangement according to the invention is designated by reference number 10 in FIG.
  • the circuit 10 is arranged between a first connection 11 with a first supply potential VDD, for example the positive supply potential, and a second connection 12 with a second supply potential VSS, for example the potential of the reference ground or a negative supply potential.
  • a current source 13 for example a resistor or a MOSFET, is provided, which is between the circuit 10 and the second connection 12 is arranged and which supplies the circuit 10 with a direct current II.
  • the circuit 10 has four controllable switches 14-17 arranged to one another to form a full bridge 21.
  • the radiation source 2 is connected as a load between the two outputs or the taps 18, 19 of the switches 14-17.
  • Conventional transistors, for. B. MOSFETs or bipolar transistors are used, but other configurations would also be conceivable.
  • the controllable switches 14-17 each have a control connection via which they can be switched on and off.
  • the controllable switches 14-17 or their control connections are controlled via control signals VS1-VS4, which are provided by a control device 20.
  • a microprocessor, microcontroller or alternatively also a logic circuit can be used as control device 20, for example.
  • the switches 14-17 are controlled via the control device in such a way that the switches 14-17 switch as abruptly as possible and thus the sign of the current II changes as smoothly as possible. Since the radiation source 2 is supplied with an identical current II in terms of amount, the radiation 6 emitted by the radiation source 2 is also identical. The change of sign of the current II therefore has almost no influence on the emitted radiation 6.
  • the method just described is designed for continuous measurement operation, the method according to the invention is modified in the case of very short measurement processes in such a way that the change of sign of the current II or the switching of the switches 14-17 takes place when the measurement arrangement 1 is switched off.
  • a preferred circuit 10 was described with reference to FIG. 2, by means of which the sign of the current II supplied to the radiation source 2 is reversed according to the invention.
  • the method according to the invention cannot, of course, be implemented exclusively with an arrangement shown in FIG. 2; rather, other advantageous arrangements for reversing the sign of the current II supplied to the radiation source 2 would also be conceivable here.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

La présente invention concerne un procédé et un dispositif destiné à l'analyse quantitative de gaz. Selon l'invention, un dispositif de commutation sert à modifier par alternance la direction du flux alimentant la source de rayonnement. Cela permet d'éviter dans une large mesure les transports en masse dans le filament spiralé de la source de rayonnement.
PCT/EP2002/007841 2001-08-06 2002-07-15 Procede et dispositif d'analyse quantitative de gaz Ceased WO2003014712A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10138508.0 2001-08-06
DE10138508A DE10138508A1 (de) 2001-08-06 2001-08-06 Verfahren und Vorrichtung zur quantitativen Gasanalyse

Publications (1)

Publication Number Publication Date
WO2003014712A1 true WO2003014712A1 (fr) 2003-02-20

Family

ID=7694525

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2002/007841 Ceased WO2003014712A1 (fr) 2001-08-06 2002-07-15 Procede et dispositif d'analyse quantitative de gaz

Country Status (2)

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DE (1) DE10138508A1 (fr)
WO (1) WO2003014712A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10332515A1 (de) * 2003-07-17 2005-02-10 Robert Bosch Gmbh Lampenansteuerung für spektroskopische Sensoren

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0192013A2 (fr) * 1985-02-21 1986-08-27 Dr. THIEDIG + CO. Procédé pour la mesure de la concentration d'un gaz et dispositif pour la mise en oeuvre du procédé
US4859859A (en) * 1986-12-04 1989-08-22 Cascadia Technology Corporation Gas analyzers
US5874737A (en) * 1996-03-06 1999-02-23 Endress + Hauser Conducta Gesellschaft fur Mess- und Regeltechnik mbH + Co. Gas analyzer
US6114700A (en) * 1998-03-31 2000-09-05 Anatel Corporation NDIR instrument

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3005638C2 (de) * 1980-02-15 1987-05-07 Grün Optik Wetzlar GmbH, 6330 Wetzlar Atomspektrallampe für die Zeeman-Atomabsorptionsspektroskopie
DE4119346C2 (de) * 1991-06-12 2000-12-07 Klaus Nonnenmacher Verfahren zur Bestimmung der Konzentration von Gasen, insbesondere von Ozon, und Vorrichtung zur Durchführung des Verfahrens
DE19753672A1 (de) * 1997-12-03 1999-06-10 Siemens Ag Gasanalysator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0192013A2 (fr) * 1985-02-21 1986-08-27 Dr. THIEDIG + CO. Procédé pour la mesure de la concentration d'un gaz et dispositif pour la mise en oeuvre du procédé
US4859859A (en) * 1986-12-04 1989-08-22 Cascadia Technology Corporation Gas analyzers
US5874737A (en) * 1996-03-06 1999-02-23 Endress + Hauser Conducta Gesellschaft fur Mess- und Regeltechnik mbH + Co. Gas analyzer
US6114700A (en) * 1998-03-31 2000-09-05 Anatel Corporation NDIR instrument

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Publication number Publication date
DE10138508A1 (de) 2003-03-06

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