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WO1988003268A2 - Procede de determination en continu du taux d'humidite de gaz - Google Patents

Procede de determination en continu du taux d'humidite de gaz Download PDF

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Publication number
WO1988003268A2
WO1988003268A2 PCT/EP1987/000636 EP8700636W WO8803268A2 WO 1988003268 A2 WO1988003268 A2 WO 1988003268A2 EP 8700636 W EP8700636 W EP 8700636W WO 8803268 A2 WO8803268 A2 WO 8803268A2
Authority
WO
WIPO (PCT)
Prior art keywords
gas
moisture content
gases
measuring
electrode
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/EP1987/000636
Other languages
German (de)
English (en)
Other versions
WO1988003268A3 (fr
Inventor
Hans Josef Speicher
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.)
Saarbergwerke AG
Original Assignee
Saarbergwerke AG
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 Saarbergwerke AG filed Critical Saarbergwerke AG
Publication of WO1988003268A2 publication Critical patent/WO1988003268A2/fr
Publication of WO1988003268A3 publication Critical patent/WO1988003268A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0026—General constructional details of gas analysers, e.g. portable test equipment using an alternating circulation of another gas
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/417—Systems using cells, i.e. more than one cell and probes with solid electrolytes
    • G01N27/4175—Calibrating or checking the analyser

Definitions

  • the invention relates to a method for continuously detecting the moisture content of gases, in particular flue gases, with a changing composition using a zirconium element.
  • zirconium measuring elements for measuring the moisture content of a gas with, apart from the moisture content itself, a constant composition, ie a constant oxygen concentration.
  • Zirconium measuring elements essentially consist of two heated platinum electrodes, the reference electrode and the measuring electrode, surrounded by zirconium ceramic.
  • the property of zirconium ceramics is used to behave like a solid electrolyte at high temperatures towards oxygen ions. Assign them to the Gasses or gases passed by the reference electrode have different oxygen partial pressures, a corresponding electrical voltage builds up between the two electrodes, for which the relationship applies according to Nernst's equation
  • E the electrical signal y: the oxygen concentration (vol.% - O 2 ) at the measuring electrode a: the oxygen concentration. (Vol.% - O 2 ) at the reference electrode
  • one electrode is charged with a reference gas with a defined O 2 content, eg air with 21 vol.% O 2
  • the second electrode is charged with a measuring gas
  • the voltage measured between the electrodes immediately provides a measure of the oxygen concentration of the sample gas. If the composition of the sample gas remains the same, the oxygen concentration of the sample gas and thus the voltage measured between the electrodes also change due to the changed volumetric composition. The change in voltage is therefore a measure of the change in the moisture content in the sample gas or, if the measuring circuit is appropriately adjusted, for its moisture content itself.
  • zirconium elements cannot easily be used to determine the moisture content of gases with a changing composition, the oxygen concentration of which is therefore influenced not only by the moisture content but also by changing the volume fractions of other gas components.
  • Such a gas with a constantly changing composition or oxygen concentration is, for example, flue gas from combustion plants.
  • flue gas from combustion plants.
  • knowledge of the moisture content is necessary to determine the standard volume. So far, the moisture content due to the combustion stoichiometry has been included in the determination of the standard volume of the flue gas as constant. Errors of up to 10% were accepted.
  • the object of the present invention is therefore to provide a simple method for detecting the moisture content of gases, which is also suitable for the exact and continuous detection of gases with a changing composition, in particular also of flue gases.
  • this object is achieved according to the invention in that sample gas is continuously branched off from the sample gas stream, dried and the dried sample gas is used as the reference gas.
  • a reference gas With the dried sample gas, a reference gas is available, the composition of which corresponds to the composition of the sample gas at all times, except for the moisture content.
  • the moisture content of the untreated measuring gas is thus directly determined by the difference in the oxygen partial pressures or by the electrode voltage. A change in the volume fractions of the other gas components has no influence on the measurement result. It is therefore no longer necessary to know the oxygen concentration itself of the reference gas. The following relationship therefore applies to the determination of the moisture in the sample gas:
  • the reference gas does not have to be absolutely dry. Rather, it is sufficient to dry the reference gas to a defined residual moisture, which can then be compensated for in terms of circuitry.
  • the moisture is expediently removed by cooling the reference gas to a dew point temperature at which the saturation of the reference gas no longer depends on the gas composition, that is to say the reference gas has a defined, known residual moisture. In the case of flue gases, for example, cooling to approx. 2 ° C is advisable.
  • the residual moisture of the reference gas is constant and can be determined using the following equation:
  • v volume concentration in% by volume
  • c saturation content at 2 ° C
  • fs 5.56 g / m 3 T
  • Absolute temperature P pressure (Torr)
  • M molecule aryu weight H 2 O - 18.015
  • the calibration of the measuring device is carried out with dry test gas, the volumetric composition of the oxygen concentration in nitrogen being a defined measure of the moisture content and determined according to the following relationship: c
  • untreated measuring gas is passed over a connection 7 to a measuring electrode 5 of a zircon moisture sensor 1.
  • a partial stream is branched off via line 8, from which the moisture is withdrawn in a gas cooler 9, for example by cooling to 2 ° C., down to the known residual moisture corresponding to the temperature of 2 ° C.
  • the gas thus dried is passed via line 10, valve 13 and line 16 as a reference gas to a reference electrode 6 of the moisture sensor 1.
  • the voltage building up on the electrodes 5, 6 is switched via a measuring amplifier 2 to a display device 6, the scale of which directly indicates vol% moisture.
  • the electrode voltage is switched on in the measuring amplifier 2 when the switch 4 is in the "on" position of a switch 4 to compensate for the residual moisture of the reference gas.
  • the valves 11, 12 and 15 are closed.
  • a test gas with a defined humidity is supplied to the measuring electrode via line 14 when the valve 11 is open.
  • Air with a defined O 2 content of 21% serves as the reference gas, that of the reference electrode 6 via line 16 is supplied with the valve 12 open.
  • the valves 13, 15 are closed, the switch 4 in the "off" position.
  • Air is applied to both electrodes 5, 6 in order to check the zero point. Valves 13 and 11 are closed, valves 12 and 15 are open. When the air pump 17 is switched on, air is conducted via line 16 to the reference electrode 6 and via lines 18, 14 to the measuring electrode 5. Since exactly the same gas is supplied to both electrodes 5, 6, no voltage can occur at the electrodes 5, 6 in this circuit, except for the production-related asymmetry potentia I, which must be taken into account in the calibration.
  • Deadline Publication will be repeated if changes occur.
  • a zirconium measurement element In a process for determining on a constant basis the moisture content of gases, in particular smoke gases with a changing composition, a zirconium measurement element is used, having one electrode to which the gas to be measured is applied and a second electrode to which a reference gas is applied. Gas is continuously extracted from the stream of gas to be measured, then dried, and the dry gas is used as reference gas.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Molecular Biology (AREA)
  • Electrochemistry (AREA)
  • Combustion & Propulsion (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

Pour appliquer un procédé de détermination en continu du taux d'humidité de gaz, en particulier de gaz de fumée ayant une composition changeante, on utilise un élément de mesure en zirconium ayant une électrode à laquelle on applique le gaz à mesurer et une deuxième électrode à laquelle un gaz de référence est appliqué. Du gaz est extrait en continu du courant de gaz à mesurer, puis déshydraté, et le gaz déshydraté est utilisé comme gaz de référence.
PCT/EP1987/000636 1986-10-31 1987-10-27 Procede de determination en continu du taux d'humidite de gaz Ceased WO1988003268A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP3637218.8 1986-10-31
DE19863637218 DE3637218A1 (de) 1986-10-31 1986-10-31 Verfahren zum kontinuierlichen erfassen des feuchtegehaltes von gasen

Publications (2)

Publication Number Publication Date
WO1988003268A2 true WO1988003268A2 (fr) 1988-05-05
WO1988003268A3 WO1988003268A3 (fr) 1988-06-16

Family

ID=6312954

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1987/000636 Ceased WO1988003268A2 (fr) 1986-10-31 1987-10-27 Procede de determination en continu du taux d'humidite de gaz

Country Status (3)

Country Link
AU (1) AU1105088A (fr)
DE (1) DE3637218A1 (fr)
WO (1) WO1988003268A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0472001A3 (en) * 1990-08-23 1992-10-07 Pleva Gmbh Method for determining the quantity of vapours in air, especially of water vapour
EP0548842A1 (fr) * 1991-12-20 1993-06-30 Saarbergwerke Aktiengesellschaft Dispositif pour déterminer la teneur en humidité des gaz

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE202009004132U1 (de) 2009-03-24 2009-06-25 Ams Analysen, Mess- Und Systemtechnik Gmbh Vorrichtung zur Gasfeuchtemessung in insbesondere Rauchgasen

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4098650A (en) * 1976-11-08 1978-07-04 Thermo-Lab Instruments, Inc. Method and analyzer for determining moisture in a mixture of gases containing oxygen
JPS60105957A (ja) * 1983-11-14 1985-06-11 Fuji Electric Co Ltd 水分測定装置
JPS60114765A (ja) * 1983-11-28 1985-06-21 Fuji Electric Co Ltd 水分測定装置
JPS61117447A (ja) * 1984-11-13 1986-06-04 Fuji Electric Co Ltd 水分測定装置

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0472001A3 (en) * 1990-08-23 1992-10-07 Pleva Gmbh Method for determining the quantity of vapours in air, especially of water vapour
DE4026591B4 (de) * 1990-08-23 2005-08-25 Pleva Gmbh Vorrichtung zur Bestimmung der Beladung von Luft mit Dämpfen
EP0548842A1 (fr) * 1991-12-20 1993-06-30 Saarbergwerke Aktiengesellschaft Dispositif pour déterminer la teneur en humidité des gaz

Also Published As

Publication number Publication date
AU1105088A (en) 1988-05-25
DE3637218A1 (de) 1988-05-05
WO1988003268A3 (fr) 1988-06-16

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