EP0042789B1 - Method for the in situ and continuous high-sensibility measuring of concentrations of gas and volatile products, and apparatus for carrying it out - Google Patents

Method for the in situ and continuous high-sensibility measuring of concentrations of gas and volatile products, and apparatus for carrying it out Download PDF

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Publication number
EP0042789B1
EP0042789B1 EP81400967A EP81400967A EP0042789B1 EP 0042789 B1 EP0042789 B1 EP 0042789B1 EP 81400967 A EP81400967 A EP 81400967A EP 81400967 A EP81400967 A EP 81400967A EP 0042789 B1 EP0042789 B1 EP 0042789B1
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Prior art keywords
chamber
expansion chamber
gases
enclosure
concentrations
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EP81400967A
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German (de)
French (fr)
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EP0042789A1 (en
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Jean-Claude Baubron
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Bureau de Recherches Geologiques et Minieres BRGM
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Bureau de Recherches Geologiques et Minieres BRGM
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/24—Vacuum systems, e.g. maintaining desired pressures

Definitions

  • the invention relates to a method of highly sensitive measurements carried out in situ and continuously of the concentrations of gases and volatile products as well as to apparatuses for implementing the method.
  • such devices although having abundance detection thresholds of the order of 50 ppm when the measurement is made in situ and from 15 to 20 ppm in the laboratory, are still insufficient especially in the case of forecasts of '' volcanic eruptions because they can neither detect very small differences in concentrations nor the presence of a new element at very low concentration.
  • a detection is essential to detect and measure the contributions of elements from leaks from the lower layers located for example at a depth of thirty kilometers and which can be disturbed by the atmosphere and the waters in cycles which cannot be establish the evolution only by systematic and continuous measurements over a long period.
  • the object of the present invention is a method of measurement, high sensitivity, gas concentrations and volatile products from natural sites or not and regardless of the pressures and flow rates since these pressures are greater than 10- 2 bars, by means of an access pipe connected to a mass spectrometer via an expansion chamber, pumps simultaneously maintaining the pressures at optimal values in the expansion chamber and an analysis chamber, characterized in that the gases and volatile products are sampled for which it is desired to know the variations in concentrations, by establishing a permanent passage between the expansion chamber and the access pipe and maintaining the pressure of the expansion chamber at a value determined constant, on the order of magnitude from 10- 1 to 10- 2 mbar, by all of the automatic adjustments of the flow rate of access to the expansion chamber, the output flow of this expansion chamber and the pumping e of the latter in order to obtain a constant pressure.
  • Such a method has the advantage of being able to measure with an accuracy of the order of 2 ppm and continuously the concentrations of gaseous or volatile elements originating from any emergence, whether it be very small emanations or leaks at high flow rates, pressures up to 5 bar for example.
  • Another object of the invention and an apparatus for implementing the process thus defined characterized in that it comprises a semi-flexible stainless metal probe, connected by a low-flow conduit to an expansion chamber connected on the one hand to a gas transfer pump, on the other hand to a pressure gauge of said chamber, a controlled inlet valve controlling the flow rate accessing said chamber, a piezoelectric valve connecting said expansion chamber to the analysis chamber a mass spectrometer, said piezoelectric valve being controlled by an ion gauge for controlling the pressure of the analysis chamber or by the spectrometer itself.
  • the device used still makes it possible, because of the access valves, to avoid the use of long capillary tubes intended to lower the pressure to a predetermined level but the use of which increases the response times of the devices to which they are connected.
  • Another feature of the invention is a device of this type, the mass spectrometer of which is a quadrupole spectrometer so that the whole of the device and the pumps for emptying and establishing low pressures is easily inserted into a sealed housing of small dimensions, the measurements provided by the mass spectrometer being transmitted by cables or radio to any station far from the place of measurement.
  • the single figure represents in schematic form the whole of the measuring device in its enclosure and of the connected elements.
  • the enclosure shown in 1, can take any desired shape depending on the easements of use but is preferably in a parallelepiped shape, rainproof and of reduced dimensions due to the methods and means of implementation adopted. .
  • Access to the various organs can be obtained by any known means by means of a station 2 outside the enclosure.
  • This general control and command station 2 is connected to the electrical supply device 3 by the multiple link cable 4, the device 3 supplying voltage to the various elements of the device.
  • a probe for sampling gases and volatile products has been shown diagrammatically in 5.
  • This probe is permanently introduced into an appropriate vent.
  • the sample thus collected is preferably channeled by a semi-flexible stainless steel tube 6 whose upstream end provided with a breather comprises a filter 7, optionally followed by any device for trapping water and carbon dioxide shown diagrammatically at 8
  • the assembly can also be brought to a high temperature, 120 ° C. for example.
  • a connection 9 brings in the gases and volatile products sampled at the inlet 10 of the device, this inlet being connected to an expansion chamber 11.
  • a valve 12 for example a needle valve or any slaved valve, makes it possible to adjust the flow of gases and volatiles removed to maintain a certain pressure of 10- 2 to 10- 1 mbar for example in the expansion chamber 11 in order to ensure the reproducibility of measurements.
  • the chamber 11 is connected to the pump 13 by the conduit 14.
  • This pump is preferably a two-stage vane pump with a flow rate of 4.5 m 3 per hour or less depending on the applications.
  • the gases exit from the enclosure 1 takes place via the conduit 15, the end of which is directed towards the ground.
  • a pressure gauge 16, of the “Pirani for example” type, supplied by the cable 17 provides the value of the pressure on the indication 18 of the control and command station 2.
  • This station may also include a means for adjusting the valve. 12, the manual or automatic adjustment being performed to maintain a constant pressure in the range of 10- 2 to 10- 1 mbar in the chamber 11.
  • the expansion chamber 11 is connected to the analysis chamber 19 of the mass spectrometer 20 by the pipe 21 and under the control of the piezoelectric valve 22.
  • This valve is automatically controlled by the ion gauge 23 connected to the chamber d analysis 19 by means of the metal fitting 24 or even directly controlled by the spectrometer itself.
  • the ion gauge 23 and the piezoelectric valve 22 are supplied by the electric cable 25 and the devices 26 and 27, the device 27 being a reaction circuit directly controlling the piezoelectric valve 22.
  • the reaction circuit 27 has been shown schematically, this circuit can be of any known type.
  • the adjustment and control of the reaction circuit 27 as a function of the pressure of the analysis chamber 19 are such that they make it possible to vary the flow rate of the volatile products and of the expanded gases from the chamber 11 towards the analysis chamber 19 in order to maintain a stable pressure of 10- 8 to 10- 7 mbar. They can also cause the valve 22 to cut off all communication between the two chambers 11 and 19 in order to obtain perfect safety of the apparatus, in particular in the event of an operating incident liable to affect the filament of the spectrometer 20.
  • the valve 22 also remains closed when the device is in the standby position between the measurements if they are done discontinuously.
  • the analysis chamber 19 is emptied by means of a primary pump 28, of the same type as the pump 13, provided with an outlet pipe 29 and the connector 30 connected to the outlet of the ultra-fast pump 31 which is preferably an oil diffusion pump or a turbomolecular pump.
  • the pump is surmounted by a baffle 32, the cooling of the pump being ensured by forced ventilation.
  • This pumping can also be provided by any other known means, such as a turbo pump for example.
  • a set of control and display means 33 of the control station 2 makes it possible to control each of the pumps 13, 28 and 31 supplied respectively by the electrical circuits 34, 35 and 36.
  • the station 2 likewise allows the control of the ion gauge the spectrometer 20 and the reaction circuit 27 controlling the piezoelectric valve 22 as well as the Pirani gauge 16, its reaction circuit and the valve 12.
  • the results of the mass spectrometer 20, which is of the quadrupole type supplied by the cable 37, are transmitted by the cable 39 to an information processing device 39 possibly connected by the cable 40 to the control and command station 2.
  • the device 39 can be a digital or analog computing device and can be located at any station more or less away from the analysis site. It can be connected by means of the cable 43 to all auxiliary display 41 or print 42 devices.
  • the enclosure 1 of reduced dimensions of the order for example of 40 ⁇ 50 ⁇ 60 cm at least, in the immediate vicinity of this site and to carry out measurements of very low gas concentrations with a view to detecting variations in elements such as H, He, CH 4 , NH 3 etc ... in a mass of H 2 0, CO z , N 2 , l apparatus thus produced having an abundance sensitivity of the order of 2 ppm.
  • the apparatus being in the vicinity of the site, operating autonomously and being permanently controlled by the station 2 possibly slaved to the data processing system 39, it is possible, depending on the results obtained, to repeat the sampling cycles by the probed 5 and of introduction into the analysis chamber 19 by passing through the expansion chamber 11, according to variable frequencies.
  • the data processing device 39 therefore makes it possible to control the frequency of repetition of the measurement cycles as a function of the values of the concentrations obtained independently of the pressures of the gases collected by the probe.
  • the response time of the device can be very short since on the one hand its reduced dimensions lend themselves to a possibility of installation very close to the chosen vent and on the other hand, due to the controls of valves 12 and 22 it is not necessary to connect the device to the probe 5 by a capillary extending over the entire distance existing between probe and device.
  • a single calculation device 39 can be connected to several enclosures 1, each of which permanently receives the emanations from a neighboring emergence.
  • the device can also be used to control the gassing of geothermal boreholes and detect gas anomalies in geothermal energy or in mining research.
  • the apparatus can then be coupled to a scintillation probe 44 for the detection and simultaneous measurement of the Radon.
  • This usual type probe can be connected by any suitable expansion junction 11.
  • the current supply to the probe has been shown diagrammatically by wire 45 and the output by wire 46.
  • the station 2 for monitoring and controlling the elements contained in the enclosure 1 is then controlled by the results of the remote information processing device 39 supplied by the mass spectrometer 20 and by the scintillation probe 44 connected to the expansion chamber 11.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Sampling And Sample Adjustment (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Electron Tubes For Measurement (AREA)

Abstract

Continuous monitoring of variations in the concentrations of individual components in gaseous mixtures such as, more particularly, gases released from volcanic vents, is achieved in the field with consistently high precision, namely about 2 ppm, over extended periods of time, while the time lag for detecting a variation is minimized. On-site measurements are made with a portable apparatus, comprising a sampling probe from which the gas is led to an expansion enclosure maintained at a regulated pressure of about 10-2 to 10-1 millibar. From this enclosure, the gas is metered by means of a piezoelectric valve into the analyzing chamber of a quadrupole mass-spectrometer. Several units operating in the field, directly over the volcanic vents, may be connected to a central data processing station, so as to derive useful correlations for predicting future volcanic activity, for monitoring geothermal sources, and for detecting gas-release anomalies for purposes of geophysical exploration.

Description

L'invention se rapporte à un procédé de mesures de grande sensibilité effectuées in situ et de façon continue des concentrations de gaz et produits volatils ainsi qu'aux appareils de mise en oeuvre du procédé.The invention relates to a method of highly sensitive measurements carried out in situ and continuously of the concentrations of gases and volatile products as well as to apparatuses for implementing the method.

On connaît, par exemple par la demande de brevet français FR-A-2 438 267, des procédés de mesures permettant de surveiller les variations de concentration de gaz, ces mesures étant effectuées en continu au laboratoire. Cependant ces mesures ne portent que sur des gaz à la pression atmosphérique ou à pressions plus faibles, et il n'y a aucune difficulté à utiliser tous appareillages connus pour effectuer de telles mesures.We know, for example from French patent application FR-A-2 438 267, measurement methods for monitoring variations in gas concentration, these measurements being carried out continuously in the laboratory. However, these measurements relate only to gases at atmospheric pressure or at lower pressures, and there is no difficulty in using any known apparatus for carrying out such measurements.

Par contre lorsque l'on désire étudier de très faibles variations de concentrations de gaz susceptibles de contenir en outre des produits volatils, ces gaz se présentant sous des pressions variables, comme cela est notamment le cas d'émanations volcaniques où la pression des gaz peut être considérable et fluctuer entre de très larges limites, on ne dispose d'aucun moyen capable d'effectuer de telles mesures en continu in situ et sur une longue période.On the other hand, when it is desired to study very small variations in the concentrations of gases liable to additionally contain volatile products, these gases occurring under variable pressures, as is notably the case with volcanic emanations where the pressure of the gases can Being considerable and fluctuating between very wide limits, there is no means capable of carrying out such measurements continuously in situ and over a long period.

Il existe bien des appareils capables d'effectuer des prélèvements de gaz de sources volcaniques afin de mesurer les concentrations par chromatographie en phase gazeuse mais ces appareils ne permettent pas d'opérer des mesures de façon continue.There are many devices capable of taking samples of gases from volcanic sources in order to measure concentrations by gas chromatography, but these devices do not allow measurements to be made continuously.

En outre de tels appareils, bien qu'ayant des seuils de détection d'abondance de l'ordre de 50 ppm lorsque la mesure est faite in situ et de 15 à 20 ppm en laboratoire, sont encore insuffisants notamment dans le cas de prévisions d'éventuelles éruptions volcaniques car ils ne peuvent ni détecter de très faibles écarts de concentrations ni la présence d'un élément nouveau à très faible concentration. Or une telle détection est indispensable pour déceler et mesurer les apports d'éléments provenant des fuites des couches inférieures situées par exemple à une trentaine de kilomètres de profondeur et qui peuvent être perturbés par l'atmosphère et les eaux dans des cycles dont on ne peut établir l'évolution que par des mesures systématiques et de façon continue sur une longue période.In addition, such devices, although having abundance detection thresholds of the order of 50 ppm when the measurement is made in situ and from 15 to 20 ppm in the laboratory, are still insufficient especially in the case of forecasts of '' volcanic eruptions because they can neither detect very small differences in concentrations nor the presence of a new element at very low concentration. However, such a detection is essential to detect and measure the contributions of elements from leaks from the lower layers located for example at a depth of thirty kilometers and which can be disturbed by the atmosphere and the waters in cycles which cannot be establish the evolution only by systematic and continuous measurements over a long period.

En résumé on sait mesurer avec une grande précision les variations de concentrations de gaz, par exemple au moyen d'un spectromètre de masse, mais alors les mesures ne peuvent s'effectuer qu'en laboratoire à l'aide d'appareillages volumineux ou bien encore on sait mesurer des variations de concentration in situ mais alors les mesures sont discontinues et manquent de précision pour la détection de faibles concentrations.In summary, it is known to measure with great precision the variations in gas concentrations, for example by means of a mass spectrometer, but then the measurements can only be carried out in the laboratory using bulky apparatuses or else still we know how to measure variations in concentration in situ but then the measurements are discontinuous and lack precision for the detection of low concentrations.

L'objet de la présente invention est un procédé de mesure, de grande sensibilité, des concentrations de gaz et produits volatils émanant de sites naturels ou non et quels que soient les pressions et les débits dès lors que ces pressions sont supérieures à 10-2 bars, au moyen d'une canalisation d'accès reliée à un spectromètre de masse par l'intermédiaire d'une chambre de détente, des pompes maintenant simultanément les pressions aux valeurs optimales dans la chambre de détente et une chambre d'analyse, caractérisé en ce que l'on prélève les gaz et produits volatils dont on désire connaître les variations de concentrations, en établissant un passage permanent entre la chambre de détente et la canalisation d'accès et en maintenant la pression de la chambre de détente à une valeur constante déterminée, de l'ordré de grandeur de 10-1 à 10-2 mbar, par l'ensemble des réglages automatiques du débit d'accès à la chambre de détente, du débit de sortie de cette chambre de détente et du pompage de celle-ci en vue d'obtenir une pression constante.The object of the present invention is a method of measurement, high sensitivity, gas concentrations and volatile products from natural sites or not and regardless of the pressures and flow rates since these pressures are greater than 10- 2 bars, by means of an access pipe connected to a mass spectrometer via an expansion chamber, pumps simultaneously maintaining the pressures at optimal values in the expansion chamber and an analysis chamber, characterized in that the gases and volatile products are sampled for which it is desired to know the variations in concentrations, by establishing a permanent passage between the expansion chamber and the access pipe and maintaining the pressure of the expansion chamber at a value determined constant, on the order of magnitude from 10- 1 to 10- 2 mbar, by all of the automatic adjustments of the flow rate of access to the expansion chamber, the output flow of this expansion chamber and the pumping e of the latter in order to obtain a constant pressure.

Un tel procédé présente l'avantage de pouvoir mesurer avec une précision de l'ordre de 2 ppm et de façon continue les concentrations d'éléments gazeux ou volatils provenant de toute émergence qu'il s'agisse de très faibles émanations ou de fuites à forts débits, les pressions pouvant attein- dre 5 bars par exemple.Such a method has the advantage of being able to measure with an accuracy of the order of 2 ppm and continuously the concentrations of gaseous or volatile elements originating from any emergence, whether it be very small emanations or leaks at high flow rates, pressures up to 5 bar for example.

En particulier, s'il s'agit de surveiller un site volcanique on mesure les variations de concentration des éléments en tous points désirés, de telle sorte qu'il devient possible d'étudier avec rigueur toute corrélation en vue d'établir des prévisions d'éventuelles éruptions alors qu'aucune méthode permanente jusqu'à ce jour ne permettait d'établir la prévision de tels risques.In particular, if it is a question of monitoring a volcanic site one measures the variations of concentration of the elements in all desired points, so that it becomes possible to study with rigor any correlation in order to establish forecasts of 'possible eruptions when no permanent method to date made it possible to establish the forecast of such risks.

Un autre objet de l'invention et un apareil de mise en oeuvre du procédé ainsi défini caractérisé en ce qu'il comprend une sonde métallique semi souple inoxydable, reliée par un conduit à faible débit à une chambre de détente connectée d'une part à une pompe de transfert des gaz, d'autre part à une jauge de pression de ladite chambre, une vanne d'entrée asservie contrôlant le débit accédant à ladite chambre, une vanne piézo-électrique reliant ladite chambre de détente à la chambre d'analyse d'un spectromètre de masse, ladite vanne piézo-électrique étant contrôlée par une jauge ionique de contrôle de la pression de la chambre d'analyse ou par le spectromètre lui-même.Another object of the invention and an apparatus for implementing the process thus defined, characterized in that it comprises a semi-flexible stainless metal probe, connected by a low-flow conduit to an expansion chamber connected on the one hand to a gas transfer pump, on the other hand to a pressure gauge of said chamber, a controlled inlet valve controlling the flow rate accessing said chamber, a piezoelectric valve connecting said expansion chamber to the analysis chamber a mass spectrometer, said piezoelectric valve being controlled by an ion gauge for controlling the pressure of the analysis chamber or by the spectrometer itself.

Quelle que soit la pression des gaz dirigés en permanence vers l'appareil, il est donc possible de régler le débit d'accès à la chambre d'analyse du spectromètre de masse avec une grande précision et d'évaluer en permanence toutes variations des concentrations des éléments du mélange sans que les temps de réponse du dispositif soient prohibitifs. En effet le dispositif utilisé permet encore, en raison des vannes d'accès, d'éviter l'emploi de longs tubes capillaires destinés à baisser la pression à un niveau prédéterminé mais dont l'emploi accroît les temps de réponse des appareils auxquels ils sont connectés.Whatever the pressure of the gases constantly directed towards the apparatus, it is therefore possible to regulate the flow rate of access to the analysis chamber of the mass spectrometer with great precision and to continuously evaluate any variations in concentrations elements of the mixture without the response times of the device being prohibitive. Indeed, the device used still makes it possible, because of the access valves, to avoid the use of long capillary tubes intended to lower the pressure to a predetermined level but the use of which increases the response times of the devices to which they are connected.

Une autre caractéristique de l'invention est un appareil de ce type dont le spectromètre de masse est un spectromètre quadrupolaire de telle sorte que l'ensemble de l'appareil et des pompes de vidage et d'établissement de faibles pressions soit aisément inséré dans un logement étanche de faibles dimensions, les mesures fournies par le spectromètre de masse étant transmises par câbles ou radio à toute station éloignée du lieu de mesure.Another feature of the invention is a device of this type, the mass spectrometer of which is a quadrupole spectrometer so that the whole of the device and the pumps for emptying and establishing low pressures is easily inserted into a sealed housing of small dimensions, the measurements provided by the mass spectrometer being transmitted by cables or radio to any station far from the place of measurement.

Il devient alors possible d'utiliser un tel appareil en tout lieu difficile d'accès dans l'industrie ou dans la nature, dans ce cas l'appareil pouvant être aisément transporté.It then becomes possible to use such a device anywhere difficult to access in industry or in nature, in this case the device can be easily transported.

D'autres caractéristiques et avantages ressortiront de la description suivante faite en référence au dessin annexé qui représente, à titre d'exemple non limitatif, un mode de réalisation de la présente invention.Other characteristics and advantages will emerge from the following description made with reference to the appended drawing which represents, by way of nonlimiting example, an embodiment of the present invention.

Sur le dessin, la figure unique représente sous forme schématique l'ensemble de l'appareil de mesure dans son enceinte et des éléments connectés.In the drawing, the single figure represents in schematic form the whole of the measuring device in its enclosure and of the connected elements.

L'enceinte, figurée en 1, peut prendre toute forme désirée en fonction des servitudes d'emploi mais se présente de préférence sous une forme parallélépipédique, étanche à la pluie et de dimensions réduites en raison des procédés et des moyens de mise en oeuvre adoptés. Les accès aux divers organes peuvent être obtenus par tous moyens connus au moyen d'un poste 2 extérieur à l'enceinte. Ce poste de contrôle et de commande général 2 est connecté au dispositif d'alimentation électrique 3 par le câble de liaison multiple 4, le dispositif 3 alimentant en tension les divers éléments de l'appareil.The enclosure, shown in 1, can take any desired shape depending on the easements of use but is preferably in a parallelepiped shape, rainproof and of reduced dimensions due to the methods and means of implementation adopted. . Access to the various organs can be obtained by any known means by means of a station 2 outside the enclosure. This general control and command station 2 is connected to the electrical supply device 3 by the multiple link cable 4, the device 3 supplying voltage to the various elements of the device.

Une sonde de prélèvement des gaz et produits volatils a été schématisée en 5. Cette sonde est introduite en permanence dans un évent approprié. Le prélèvement ainsi recueilli est canalisé de préférence par un tube métallique 6 inoxydable semi-souple dont l'extrémité amont pourvue d'un reniflard comprend un filtre 7, suivi éventuellement de tout dispositif de piégeage de l'eau et du gaz carbonique schématisé en 8. L'ensemble peut être aussi porté à une température élevée, 120 °C par exemple. Un raccord 9 amène les gaz et produits volatils prélevés à l'entrée 10 de l'appareil, cette entrée étant reliée à une chambre de détente 11. Une vanne 12, par exemple une vanne à pointeau ou une vanne quelconque asservie, permet de régler le débit des gaz et produits volatils prélevés pour maintenir une pression bien déterminée de 10-2 à 10-1 mbar par exemple dans la chambre de détente 11 en vue d'assurer la reproductibilité des mesures.A probe for sampling gases and volatile products has been shown diagrammatically in 5. This probe is permanently introduced into an appropriate vent. The sample thus collected is preferably channeled by a semi-flexible stainless steel tube 6 whose upstream end provided with a breather comprises a filter 7, optionally followed by any device for trapping water and carbon dioxide shown diagrammatically at 8 The assembly can also be brought to a high temperature, 120 ° C. for example. A connection 9 brings in the gases and volatile products sampled at the inlet 10 of the device, this inlet being connected to an expansion chamber 11. A valve 12, for example a needle valve or any slaved valve, makes it possible to adjust the flow of gases and volatiles removed to maintain a certain pressure of 10- 2 to 10- 1 mbar for example in the expansion chamber 11 in order to ensure the reproducibility of measurements.

A cet effet la chambre 11 est reliée à la pompe 13 par le conduit 14. Cette pompe est de préférence une pompe à palettes biétagée d'un débit de 4,5 m3 par heure ou moins selon les applications. La sortie des gaz hors de l'enceinte 1 s'effectue par le conduit 15 dont l'extrémité est dirigée vers le sol. Une jauge de pression 16, du type « Pirani par exemple, alimentée par le câble 17 fournit la valeur de la pression sur l'indication 18 du poste de contrôle et de commande 2. Ce poste peut aussi comporter un moyen de réglage de la vanne 12, ce réglage manuel ou automatique étant effectué pour maintenir une pression constante de l'ordre de 10-2 à 10-1 mbar dans la chambre 11.For this purpose, the chamber 11 is connected to the pump 13 by the conduit 14. This pump is preferably a two-stage vane pump with a flow rate of 4.5 m 3 per hour or less depending on the applications. The gases exit from the enclosure 1 takes place via the conduit 15, the end of which is directed towards the ground. A pressure gauge 16, of the “Pirani for example” type, supplied by the cable 17 provides the value of the pressure on the indication 18 of the control and command station 2. This station may also include a means for adjusting the valve. 12, the manual or automatic adjustment being performed to maintain a constant pressure in the range of 10- 2 to 10- 1 mbar in the chamber 11.

La chambre de détente 11 est raccordée à la chambre d'analyse 19 du spectromètre de masse 20 par la canalisation 21 et sous le contrôle de la vanne piézo-électrique 22. Cette vanne est contrôlée automatiquement par la jauge ionique 23 raccordée à la chambre d'analyse 19 au moyen du raccord métallique 24 ou encore directement contrôlée par le spectromètre lui-même. La jauge ionique 23 et la vanne piézo-électrique 22 sont alimentées par le câble électrique 25 et les dispositifs 26 et 27, le dispositif 27 étant un circuit de réaction commandant directement la vanne piézo-électrique 22. Le circuit de réaction 27 a été représenté de façon schématique, ce circuit pouvant être de tout type connu. Le réglage et la commande du circuit de réaction 27 en fonction de la pression de la chambre d'analyse 19 sont tels qu'ils permettent de faire varier le débit des produits volatils et des gaz détendus de la chambre 11 vers la chambre d'analyse 19 pour y maintenir une pression stable de 10-8 à 10-7 mbar. Ils peuvent en outre entraîner la coupure par la vanne 22 de toute communication entre les deux chambres 11 et 19 afin d'obtenir une parfaite sécurité de l'appareil notamment en cas d'incident de fonctionnement susceptible d'affecter le filament du spectromètre 20.The expansion chamber 11 is connected to the analysis chamber 19 of the mass spectrometer 20 by the pipe 21 and under the control of the piezoelectric valve 22. This valve is automatically controlled by the ion gauge 23 connected to the chamber d analysis 19 by means of the metal fitting 24 or even directly controlled by the spectrometer itself. The ion gauge 23 and the piezoelectric valve 22 are supplied by the electric cable 25 and the devices 26 and 27, the device 27 being a reaction circuit directly controlling the piezoelectric valve 22. The reaction circuit 27 has been shown schematically, this circuit can be of any known type. The adjustment and control of the reaction circuit 27 as a function of the pressure of the analysis chamber 19 are such that they make it possible to vary the flow rate of the volatile products and of the expanded gases from the chamber 11 towards the analysis chamber 19 in order to maintain a stable pressure of 10- 8 to 10- 7 mbar. They can also cause the valve 22 to cut off all communication between the two chambers 11 and 19 in order to obtain perfect safety of the apparatus, in particular in the event of an operating incident liable to affect the filament of the spectrometer 20.

La vanne 22 reste aussi fermée lorsque l'appareil est en position d'attente entre les mesures si celles-ci se font de manière discontinue.The valve 22 also remains closed when the device is in the standby position between the measurements if they are done discontinuously.

La chambre d'analyse 19 est vidée au moyen d'une pompe primaire 28, de même type que la pompe 13, pourvue d'une canalisation de sortie 29 et du raccord 30 relié à la sortie de la pompe ultra-rapide 31 qui est de préférence une pompe à diffusion d'huile ou une pompe turbomoléculaire. Afin d'éviter les rétro-diffusions d'huile, la pompe est surmontée d'un baffle 32, le refroidissement de la pompe étant assuré par une ventilation forcée.The analysis chamber 19 is emptied by means of a primary pump 28, of the same type as the pump 13, provided with an outlet pipe 29 and the connector 30 connected to the outlet of the ultra-fast pump 31 which is preferably an oil diffusion pump or a turbomolecular pump. In order to avoid backscattering of oil, the pump is surmounted by a baffle 32, the cooling of the pump being ensured by forced ventilation.

Ce pompage peut aussi être assuré par tout autre moyen connu, tel une pompe turbo par exemple.This pumping can also be provided by any other known means, such as a turbo pump for example.

Un ensemble de moyens de commande et de visualisation 33 du poste de commande 2 permet de contrôler chacune des pompes 13, 28 et 31 alimentées respectivement par les circuits électriques 34, 35 et 36. Le poste 2 permet de même le contrôle de la jauge ionique du spectromètre 20 et du circuit de réaction 27 commandant la vanne piézo-électrique 22 ainsi que la jauge de Pirani 16, son circuit de réaction et la vanne 12.A set of control and display means 33 of the control station 2 makes it possible to control each of the pumps 13, 28 and 31 supplied respectively by the electrical circuits 34, 35 and 36. The station 2 likewise allows the control of the ion gauge the spectrometer 20 and the reaction circuit 27 controlling the piezoelectric valve 22 as well as the Pirani gauge 16, its reaction circuit and the valve 12.

Les résultats du spectromètre de masse 20, qui est du type quadrupolaire alimenté par le câble 37, sont transmis par le câble 39 à un dispositif de traitement de l'information 39 éventuellement connecté par le câble 40 au poste de contrôle et de commande 2. Le dispositif 39 peut être un dispositif de calcul numérique ou analogique et peut être situé à toute station plus ou moins éloignée du site d'analyse. Il peut être connecté au moyen du câble 43 à tous appareils auxiliaires de visualisation 41 ou d'impression 42.The results of the mass spectrometer 20, which is of the quadrupole type supplied by the cable 37, are transmitted by the cable 39 to an information processing device 39 possibly connected by the cable 40 to the control and command station 2. The device 39 can be a digital or analog computing device and can be located at any station more or less away from the analysis site. It can be connected by means of the cable 43 to all auxiliary display 41 or print 42 devices.

Il est ainsi possible, quelles que soient les difficultés d'accès au site choisi, de disposer l'enceinte 1 de dimensions réduites, de l'ordre par exemple de 40 x 50 x 60 cm au moins, au voisinage immédiat de ce site et de procéder à des mesures de très faibles concentrations de gaz en vue de détecter des variations des éléments tels que H, He, CH4, NH3 etc... dans une masse de H20, COz, N2, l'appareil ainsi réalisé ayant une sensibilité en abondance de l'ordre de 2 ppm.It is thus possible, whatever the difficulties of access to the chosen site, to have the enclosure 1 of reduced dimensions, of the order for example of 40 × 50 × 60 cm at least, in the immediate vicinity of this site and to carry out measurements of very low gas concentrations with a view to detecting variations in elements such as H, He, CH 4 , NH 3 etc ... in a mass of H 2 0, CO z , N 2 , l apparatus thus produced having an abundance sensitivity of the order of 2 ppm.

L'appareil étant au voisinage du site, fonctionnant de façon autonome et étant contrôlé en permanence par le poste 2 éventuellement asservi au système de traitement de données 39, on peut, en fonction des résultats obtenus, procéder à la répétition des cycles de prélèvement par la sondé 5 et d'introduction dans la chambre d'analyse 19 en transitant par la chambre de détente 11, selon des fréquences variables. Le dispositif de traitement de données 39 permet donc de contrôler la fréquence de répétition des cycles de mesure en fonction des valeurs des concentrations obtenues indépendamment des pressions des gaz recueillis par la sonde. Le temps de réponse de l'appareil peut être très court puisque d'une part ses dimensions réduites se prêtent à une possibilité d'installation très proche de l'évent choisi et d'autre part, en raison des contrôles des vannes 12 et 22 il n'est pas nécessaire de relier l'appareil à la sonde 5 par un capillaire s'étendant sur toute la distance existant entre sonde et appareil.The apparatus being in the vicinity of the site, operating autonomously and being permanently controlled by the station 2 possibly slaved to the data processing system 39, it is possible, depending on the results obtained, to repeat the sampling cycles by the probed 5 and of introduction into the analysis chamber 19 by passing through the expansion chamber 11, according to variable frequencies. The data processing device 39 therefore makes it possible to control the frequency of repetition of the measurement cycles as a function of the values of the concentrations obtained independently of the pressures of the gases collected by the probe. The response time of the device can be very short since on the one hand its reduced dimensions lend themselves to a possibility of installation very close to the chosen vent and on the other hand, due to the controls of valves 12 and 22 it is not necessary to connect the device to the probe 5 by a capillary extending over the entire distance existing between probe and device.

Si l'on désire détecter les variations des concentrations de gaz émanant d'émergences volcaniques, on peut effectuer aisément par ce procédé l'analyse systématique et permanente sur le site même des gaz tels que : H, He, CH4 de masse 16, 15 et 14, NH3 de masse 17, 16 et 15, H20 de masse 18 et 17, Ne de masse 20 et 22, N2, O2, H2S de masse 28, 32 et 34, HCI de masse 36 et 38, Ar, C02 de masse 44 et 48, S02 de masse 64 et 68 etc...If one wishes to detect variations in gas concentrations emanating from volcanic emergencies, one can easily carry out by this process systematic and permanent analysis on the site itself of gases such as: H, He, CH 4 of mass 16, 15 and 14, NH 3 of mass 17, 16 and 15, H 2 0 of mass 18 and 17, Ne of mass 20 and 22, N 2 , O2, H 2 S of mass 28, 32 and 34, HCI of mass 36 and 38, Ar, C0 2 of mass 44 and 48, S0 2 of mass 64 and 68 etc ...

Si l'on doit surveiller toute une installation ou une zone volcanique on peut connecter un dispositif de calcul unique 39 à plusieurs enceintes 1 dont chacune reçoit en permanence les émanations d'une émergence voisine.If an entire installation or volcanic area has to be monitored, a single calculation device 39 can be connected to several enclosures 1, each of which permanently receives the emanations from a neighboring emergence.

L'appareil peut également être utilisé pour contrôler les dégagements gazeux de forages géothermiques et détecter les anomalies de gaz en géothermie ou en recherche minière. On peut alors coupler l'appareil à une sonde de scintillation 44 en vue de la détection et de la mesure simultanée du Radon. Cette sonde de type habituel peut être connectée par toute jonction appropriée de détente 11. L'alimentation en courant de la sonde a été schématisée par le fil 45 et la sortie par le fil 46.The device can also be used to control the gassing of geothermal boreholes and detect gas anomalies in geothermal energy or in mining research. The apparatus can then be coupled to a scintillation probe 44 for the detection and simultaneous measurement of the Radon. This usual type probe can be connected by any suitable expansion junction 11. The current supply to the probe has been shown diagrammatically by wire 45 and the output by wire 46.

Le poste 2 de contrôle et de commande des éléments contenus dans l'enceinte 1 est alors contrôlé par les résultats du dispositif éloigné de traitement des informations 39 fournies par le spectromètre de masse 20 et par la sonde de scintillation 44 connectée à la chambre de détente 11.The station 2 for monitoring and controlling the elements contained in the enclosure 1 is then controlled by the results of the remote information processing device 39 supplied by the mass spectrometer 20 and by the scintillation probe 44 connected to the expansion chamber 11.

Claims (8)

1. Process for measuring, with high sensitivity, concentrations of gas and volatile products issuing from sites, natural or not and whatever the pressures and flowrates as long as these pressures are greater than 10-2 bars, by means of an access pipe connected to a mass spectrometer via an expansion chamber (11), pumps simultaneously maintaining the pressures at the optimum values in the expansion chamber (11) and an analysis chamber (19), characterized in that the gases and volatile product of which it is desired to know the variations in concentrations, are sampled by establishing a permanent passage between the expansion chamber (11) and the access pipe (9) and by maintaining the pressure of the expansion chamber (11) at a determined constant value, of the order of magnitude of 10-1 to 10-2 mbar, by all the automatic adjustments of the access flowrate to the expansion chamber (11), of the outlet flowrate from this expansion chamber and of the pumping thereof with a view to obtaining a constant pressure.
2. A process according to claim 1, wherein the operations of circulation of the gases and volative products, in the expansion (11) and analysis (19) chambers are controlled by a control station disposed in the vicinity of the mass spectrometer, characterized in that the control station ensures adjustement of the permanent flowrate of the gases through the expansion chamber (11) and the analysis chamber (19).
3. A process according to any of claims 1 and 2, wherein the measurements of the pressures and concentrations are transmitted to a data processing station (39) remote from the site of the measurements.
4. A process according to claim 3, wherein the data processing device monitors the frequency of repetition of the cycles of measurements as a function of the values of the concentrations obtained independently of the pressures of the gases collected by the probe.
5. An apparatus for carrying out the process claimed in any one of Claims 1 to 4 comprising a pipe for conducting the gases and volatile products under any pressure to be analysed and connected, by means of a valve and an expansion chamber, to the analysis chamber of a mass spectrometer, as well as pumping means, characterized in that the pipe comprises a probe (5) connected to the expansion chamber (11) by a conduit (9) of which the flowrate of the gases is limited by an adjusting valve (12) conducting the gases in continuous manner to said chamber (11), the latter being connected on the one hand to a gas transfer pump (13), on the other hand to a gauge (16) of the pressure of said chamber, a piezo-electric valve (22), connected between the analysis chamber (19) at the mass spectrometer (20) and the expansion chamber (11), ensuring adjustment of the continuous flowrate of the gas coming from the expansion chamber (11) under the control of the ionic gauge (23) for monitoring the pressure of analysis chamber (19), the pump (13) ensuring maintenance of the pressure of the expansion chamber (11) with the valves (12) controlling the continuous inlet flowrate of the gases in the expansion chamber (11) and for controlling the inlet flowrate (22) in the analysis chamber (19).
6. An apparatus according to claim 5, wherein the mass spectrometer (20) is a quadrupolar spectrometer housed in a transportable rain- proof enclosure (1), said enclosure (1) being provided with a source of voltage supply, characterized in that said enclosure (1) contains a second pump (31) with high rate of flow surmounted or not by a baffle (32) intended to reduce the retrodiffusions of oil in the analysis chamber (19), a third pump (28) ensuring the primary vacuum with a view to emptying the analysis chamber (19).
7. An apparatus according to any of claims 5 and 6, wherein the assembly of the elements is controlled by a station (2) outside the enclosure, characterized in that the outlet of the spectrometer measure device (20) is connected, by a data transmission cable (38), to a data processing system (39) and its display equipment (41) and print-out equipment (42) remote from the site of measurement.
8. An apparatus according to claim 7, wherein the station (2) for monitoring and controlling the elements contained in the enclosure (1) is controlled by the results of the remote data processing device (39) furnished by the mass spectrometer (20) and by a scintillation probe (44) connected to the expansion enclosure (11).
EP81400967A 1980-06-20 1981-06-17 Method for the in situ and continuous high-sensibility measuring of concentrations of gas and volatile products, and apparatus for carrying it out Expired EP0042789B1 (en)

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Application Number Priority Date Filing Date Title
AT81400967T ATE15722T1 (en) 1980-06-20 1981-06-17 METHOD FOR IN SITU AND CONTINUOUS MEASUREMENT WITH HIGH SENSITIVITY OF GAS CONCENTRATIONS AND VOLATILE PRODUCTS AND DEVICE FOR PERFORMING THE METHOD.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8013776A FR2485201A1 (en) 1980-06-20 1980-06-20 METHOD FOR MEASURING HIGH PRECISION CONCENTRATIONS OF GASES AND VOLATILE PRODUCTS IN SITU AND CONTINUOUS AND APPARATUS IN SITU
FR8013776 1980-06-20

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EP0042789B1 true EP0042789B1 (en) 1985-09-18

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JP (1) JPS5774656A (en)
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DE3631862A1 (en) * 1986-09-19 1988-03-31 Strahlen Umweltforsch Gmbh DEVICE FOR ANALYTICAL DETERMINATION OF ORGANIC SUBSTANCES
DE3510378A1 (en) * 1985-03-22 1986-10-02 Coulston International Corp., Albany, N.Y. METHOD FOR THE ANALYTICAL DETERMINATION OF ORGANIC SUBSTANCES
AU6281586A (en) * 1985-08-24 1987-03-10 John Maxwell Bather Method and apparatus for detecting dangerous substances
US5313061A (en) * 1989-06-06 1994-05-17 Viking Instrument Miniaturized mass spectrometer system
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US5153433A (en) * 1991-09-10 1992-10-06 The United States Of America As Represented By The United States Department Of Energy Portable mass spectrometer with one or more mechanically adjustable electrostatic sectors and a mechanically adjustable magnetic sector all mounted in a vacuum chamber
US5525799A (en) * 1994-04-08 1996-06-11 The United States Of America As Represented By The United States Department Of Energy Portable gas chromatograph-mass spectrometer
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ATE15722T1 (en) 1985-10-15
DE3172323D1 (en) 1985-10-24
FR2485201A1 (en) 1981-12-24
CA1170079A (en) 1984-07-03
EP0042789A1 (en) 1981-12-30
JPS5774656A (en) 1982-05-10
US4442353A (en) 1984-04-10
FR2485201B1 (en) 1984-03-09

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