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
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/85—Investigating moving fluids or granular solids
  • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample
• • 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
  • 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
  • G01N21/359—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using near infrared light
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N25/00—Investigating or analyzing materials by the use of thermal means
  • G01N25/18—Investigating or analyzing materials by the use of thermal means by investigating thermal conductivity
• • 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
• • 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
  • G01N33/22—Fuels; Explosives
  • G01N33/225—Gaseous fuels, e.g. natural gas
• • 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
  • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
  • G01N2021/3181—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths using LEDs
• • 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
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/85—Investigating moving fluids or granular solids
  • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample
  • G01N2021/8514—Probe photometers, i.e. with optical measuring part dipped into fluid sample with immersed mirror
  • G01N2021/8521—Probe photometers, i.e. with optical measuring part dipped into fluid sample with immersed mirror with a combination mirror cell-cuvette
• • 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
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/85—Investigating moving fluids or granular solids
  • G01N2021/8557—Special shaping of flow, e.g. using a by-pass line, jet flow, curtain flow
• • 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
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/85—Investigating moving fluids or granular solids
  • G01N2021/8578—Gaseous flow
• • 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
  • G01N21/15—Preventing contamination of the components of the optical system or obstruction of the light 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
  • G01N21/17—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
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N30/26—Conditioning of the fluid carrier; Flow patterns
  • G01N30/28—Control of physical parameters of the fluid carrier
  • G01N30/32—Control of physical parameters of the fluid carrier of pressure or speed

Definitions

• the subject of the invention is a probe suitable for measuring the composition of an oxidizing gas. It also relates to a system for measuring the composition of an oxidizing gas including such a probe.
• Measuring the composition of an oxidizing gas is particularly advantageous for monitoring the quality of the oxidizing gas in the supply of gas appliances of the gas heat engine, gas burner, gas boiler, gas turbine, gas oven, etc.
• the gas can indeed have variations in its composition, more or less rapid, resulting in poor combustion. These variations can in particular come from the gas source and / or treatment to which it may be subjected. Changes in the composition of the gas can be sudden, when they come from a switch of valves and / or sources of gas supply on a network. This is the case when switching from a gas tank to the gas network, or vice versa.
• Patent documents US2006 / 0092423 (SERVAITES), US8139222 (SAVELIEV) and US9291610 (ZELEPOUGA) describe probes comprising a cell in which a sample of gas to be analyzed circulates. A spectrometer is associated with this cell to measure the composition of the gas. These cells admit a limited flow of gas and therefore operate by sampling bypassing the main gas circuit, which induces an analysis delay with respect to the sampling point, which delay can be several seconds.
• a probe for measuring the composition of a fluid comprising a light source emitting a light beam in a pipe or a tank containing the fluid to be analyzed.
• a spectrometer analyzes the light beam part which has interacted with the fluid, to generate data for measuring the composition of said fluid.
• a set of optical elements makes it possible to guide towards the pipe or the reservoir, at least part of the light beam emitted by the light source, and guide towards a detector of the spectrometer, the part of the light beam having interacted with the fluid.
• a probe comprises a cage adapted to be installed removably inside a pipe in which the gas to be analyzed circulates.
• the cage is configured to allow gas to flow through said cage. At least part of the light beam propagates in the cage so as to be able to interact with the gas.
• the cage serves as a support for an optical reflector adapted to reflect, towards the detector, the part of the light beam propagating in said cage and having interacted with the gas.
• the cage consists of a porous ceramic filter so that the gas circulates with difficulty in said filter. Indeed, the gas undergoes strong stress and must face a great resistance to cross the ceramic wall. As a result, the measurements made by the probe are not in real time, or at least with a certain delay time, because of the latency of the gas to pass through the ceramic wall.
• an objective of the invention is to propose a probe making it possible to measure in real time and / or with an optimized response time, the composition of an oxidizing gas circulating in an existing pipeline and which is not specifically designed for this purpose.
• Another objective of the invention is to provide a measurement probe which can be easily and quickly installed / removed from a pipe.
• Yet another objective of the invention is to provide a measurement probe whose design is simple, robust and whose manufacturing costs are particularly reduced.
• the solution proposed by the invention is a probe comprising a spectrometer suitable for measuring the composition of an oxidizing gas after analysis of at least part of a light beam having interacted with said gas, said spectrometer comprising:
• a light source suitable for emitting a light beam
• an optical device comprising configured optical elements:
• the probe includes a cage adapted to be removably installed inside a pipe in which the gas to be analyzed circulates,
• the cage is configured to allow gas to flow through said cage, at least part of the light beam propagates in the cage so as to be able to interact with the gas,
• the cage serves as a support for an optical reflector adapted to reflect, towards the detector, the part of the light beam propagating in said cage and having interacted with the gas.
• the cage is formed by an elongated tube whose side wall has openings distributed around the periphery of said wall, which openings are configured to allow gas to pass radially through said tube, the combined surface of said openings representing more than 50% of the surface of the wall of said tube, and preferably more than 80%.
• this probe is designed to withstand harsh environments: polluted atmosphere, high ambient temperature, environment crossed by radio waves, vibrations. In particular, its design has no moving parts.
• This probe can be dismountably installed on an existing pipe.
• the supply lines of gas appliances are equipped with flanges, or other similar arrangements, allowing the installation of temperature or pressure probes for example.
• the probe object of the invention can quite be mounted in this way by means of a single flange, without the need to modify the pipe.
• the gas circulates freely and continuously inside the cage (without any additional pumping means), with the least possible stress, so that the probe allows real-time measurement of gas composition, with an optimized response time.
• the optical device comprises an optical element adapted to guide, towards a second detector of the spectrometer, part of the light beam emitted by the light source so that said spectrometer also analyzes a part of light beam not propagating in the cage; the spectrometer is adapted to measure the composition of the gas as a function of the data resulting from the analysis of the part of light beam having propagated in the cage, and of data resulting from the analysis of the part of light beam not propagating not in the cage.
• the optical element is an optical separator placed between the light source and the cage, which optical separator is suitable for: - transmitting in the cage, part of the light beam emitted by the light source; - deflect to a first detector, the part of the light beam having propagated in the cage and which is reflected by the optical reflector arranged in said cage; - deflect towards the second detector of the spectrometer, the part of the light beam which does not propagate in the cage.
• the optical device comprises an optical element suitable for guiding: - towards the cage, part of the light beam emitted by the light source; - towards the detector, the part of the light beam having propagated in the cage and which is reflected by the optical reflector arranged in said cage.
• an air knife acts as the interface between the light source and the optical separator; and an air gap interfaces between the optical splitter and the cage.
• An air gap also advantageously forms the interface between the optical separator and the first detector.
• a first lens and a first diaphragm are arranged in the air gap separating the optical separator and the first detector, said first lens and said first the diaphragm being arranged so that said beam portion having propagated in the cage and which is reflected by the optical reflector, passes first through said first lens and then said first diaphragm before impacting said first detector.
• An air knife also advantageously forms the interface between the optical splitter and the second detector.
• a second lens and a second diaphragm are arranged in the air gap separating the optical separator and the second detector, said second lens and said second diaphragm being arranged so that the portion of light beam which does not propagate in the cage, first passes through said second lens and then said second diaphragm before impacting said second detector.
• a thermal conductivity sensor is arranged on the probe so that said sensor can interact with the gas to be analyzed; a data processing unit is adapted to generate data for measuring the composition of the gas taking into account the signals emitted by the thermal conductivity sensor and the measurement data generated by the spectrometer.
• the probe includes a gas-tight chamber to be analyzed and in which the spectrometer is installed.
• the cage has a first end and a second end which are opposite, which first end has an opening which communicates with the chamber.
• the optical reflector, the aperture and the light source are aligned along the same axis.
• a transparent window made of polished sapphire is preferably arranged opposite the opening arranged at the level of the first end of the cage, which window forms a gas seal between the chamber and said cage, the part of the light beam propagating in said cage, passing through said window.
• the optical reflector is installed on a tip, which tip is attached to one end of the cage.
• a transparent window in polished sapphire covers the optical reflector.
• the probe comprises a gas-tight chamber to be analyzed and in which the spectrometer is installed, more than 50% of the volume of said chamber being filled with resin or elastomer.
• Another aspect of the invention relates to a system comprising a probe, which probe comprises a spectrometer suitable for measuring the composition of an oxidizing gas after analysis of at least part of a light beam having interacted with said gas, said spectrometer comprising:
• a light source suitable for emitting a light beam
• an optical device comprising configured optical elements:
• the system comprises a pipe in which the gas to be analyzed circulates,
• the probe conforms to one of the preceding characteristics, the cage of said probe being installed removably inside the pipe, which cage is configured so that the gas circulates through said cage,
• the cage serves as a support for an optical reflector suitable for reflecting, towards the detector, the part of the light beam propagating in said cage and having interacted with the gas.
• the cage has a longitudinal axis perpendicular or substantially perpendicular to the direction of flow of the gas in the pipeline.
• the cage When the pipeline has a bend, the cage has a longitudinal axis parallel or substantially parallel to the direction of gas flow in the bend of the pipeline.
• the system further comprises a gas chromatography device suitable for generating data for measuring the composition of the gas, which device is connected to the pipeline, so that a sample of the gas circulating in said gas pipeline is analyzed by said device.
• the probe and the gas chromatography apparatus are advantageously connected to a data processing unit; which the processing unit is adapted to correct the measurement data generated by the probe as a function of the measurement data generated by the gas chromatography apparatus.
• the probe further comprises a thermal conductivity sensor arranged so that said sensor can interact with the gas to be analyzed.
• a data processing unit is adapted to generate data for measuring the composition of the gas, taking into account the signals emitted by the thermal conductivity sensor and the measurement data generated by the spectrometer.
• the probe and the gas chromatography device are connected to a data processing unit, which processing unit is suitable for correcting said gas composition measurement data as a function of said measurement data generated by the measurement device. gas chromatography. Description of the figures.
• FIG. 1A is a perspective view of a probe according to the invention without a fixing flange
• FIG. 1B is another perspective view of a probe according to the invention without a fixing flange
• FIG. 1 C shows the probe of FIG. 1 A with fixing flange
• FIG. 2 is a partial section view of a probe according to the invention
• Figure 3 shows schematically an embodiment of a probe according to the invention
• Figure 4 shows schematically another embodiment of a probe according to the invention
• Figure 5 shows schematically yet another embodiment of a probe according to the invention
• FIG. 6A shows diagrammatically the installation of a probe according to the invention on a straight section of pipe, according to a mounting perpendicular to the axis of the pipe,
• FIG. 6B shows diagrammatically the installation of a probe according to the invention on a bent section of pipe, according to a coaxial mounting to a branch of the pipe,
• FIG. 6C shows diagrammatically the installation of a probe according to the invention on a bent section of pipe, according to another assembly coaxial with a branch of the pipe,
• FIG. 6D shows diagrammatically the installation of a probe in accordance with the invention on a straight section of pipe, according to another assembly perpendicular to the axis of the pipe,
• FIG. 7 shows diagrammatically the installation, on a pipe, of a probe according to the invention and of a chromatography apparatus
• FIG. 8 is a graph illustrating a continuous measurement of the concentration of a gas by spectrometry, punctual measurements of the concentration of the gas by chromatography, and the result of the continuous measurement by spectrometry corrected by punctual measurements by chromatography,
• Figure 9 shows schematically a probe according to the invention, in an alternative embodiment.
• the probe object of the invention is used for measuring the composition of an oxidizing gas.
• the latter is more particularly a gas used as fuel in an appliance of the gas thermal engine, gas burner, gas boiler, gas turbine, gas oven, etc. type.
• the gas can also circulate in a pipeline which can be part of a distribution network of the gas pipeline type.
• the probe is used in particular for the control of gas burning appliances, whatever the variability of gas quality. It allows better control of the appliance when the quality of the gas is brought to change, by acting on one or more parameters such as: gas and / or air ejection speed, air-gas ratio, advance to l ignition, etc.
• the gas to be analyzed can for example be methane (CF), ethane (C2He), propane (C3H8), iso-butane (i-C4Hio), normal-butane (n-C4Hio), hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), or a gaseous mixture of these compounds.
• the measurement of the composition of the gas is understood to mean the determination of the concentration (%), by mass or by volume, of one or more compounds of said gas, in proportions capable of affecting combustion.
• the probe S includes a cover 10 delimiting a gas-tight chamber to be analyzed.
• the cover 10 has a generally cylindrical appearance whose diameter is between 5 cm and 20 cm and the height between 5 cm and 30 cm.
• the cover 10 is advantageously made of stainless steel, to provide a Faraday cage effect (in the case where the probe S is used in an environment traversed by radio waves) as well as anti-corrosion protection, and can be obtained by molding or machining.
• cover and “chamber” will be used in a similar manner.
• the chamber 10 is secured to a fixing flange 11 allowing the fixing of the probe S on a pipe in which the gas to be analyzed circulates.
• This flange 1 1 has the shape of a flat disc fixed to a base of the chamber 10 and whose dimensions are greater than those of said chamber. This base is particularly visible in FIGS. 1A and 1 C and bears the reference 1 13.
• the base 113 facilitates the mounting of the flange 11, but is however optional.
• the flange 11 has for example a diameter between 10 cm and 40 cm and a thickness between 1 cm and 5 cm.
• the flange 11 has holes 110 in which engage bolts or threaded rods for the connection to the pipe, preferably according to standard NF EN 1092 of flat flange in PN 10.
• the flange 1 1 is advantageously made of stainless steel and can be obtained by molding, stamping or machining.
• the fixing of the flange 1 1 on the base 113 of the chamber 10 can be carried out by welding, screwing, bolting, riveting, etc.
• the flange 11 can also be mounted mobile in rotation around the base 113, along the axis of the chamber 10. In this case, the securing of the flange 11 on the base 113 can for example be carried out by pinching, at using bolts and / or threaded rods.
• a cage 12 extends opposite the chamber 10, along a longitudinal axis X-X parallel or coaxial with that of said chamber.
• the cage 12 can be arranged so that its axis XX is off-center with respect to that of the chamber 10. Such an off-center - or off-center - configuration makes it possible to optimize the positioning of the elements inside the chamber 10, and in particular the elements of the optical device and those for measuring pressure and temperature. The dimensions of the chamber 10 can then be reduced compared to a configuration where the axis X-X of the cage 12 is coaxial with the axis of the chamber 10.
• the cage 12 is formed by an elongated tube of circular section, so that said tube has a generally cylindrical shape.
• This tube 12 has for example a length between 3 cm and 50 cm and an external diameter between 1 cm and 10 cm.
• the thickness of the side wall of the tube 12 is for example between 0.1 cm and 1 cm.
• the tube 12 is advantageously made of stainless steel and can be obtained by molding or machining.
• the tube 12 is secured to the base 113 of the chamber 10, the fixing being able to be carried out by welding, screwing, bolting, riveting, etc.
• the probe S is therefore shaped by: the chamber 10 (and possibly its base 113), the flange 11 and the cage 12. To optimize the compactness of the probe S, the elements 10, 113 and 11 are coaxial.
• the side wall of the tube 12 has openings 120 which are distributed around the periphery of said wall. These openings 120 allow the gas to be analyzed to circulate freely and quickly inside the cage 12 when the latter is immersed in a pipe where said gas circulates. These openings 120 form meshes which allow the gas to penetrate and to come out of the tube 12.
• the gas passes through the cage 12 according in particular to a radial component. In other words, the gas enters and leaves the tube 12 radially through the openings 120.
• the openings 120 are arranged on the major part of the side wall of the said tube.
• the combined surface of the openings 120 represents more than 50% of the surface of the wall of the tube 12, and preferably more than 80%.
• the shape of the openings 120 can be chosen to reveal possible turbulence inside the tube 12 liable to homogenize the gas mixture in the tube 12 and improve the response time of the probe S without disturbing the measurement.
• the openings 120 are advantageously arranged so as to be radially opposite. Correct operation of the probe S is however obtained when the openings 120 are not radially opposite.
• the openings 120 can be oblong, circular, square, rectangular, or other, and can be obtained by machining the tube 120. Their number can for example vary from 2 to 100.
• the shape and / or the arrangement of these openings 120 can be defined and optimized by calculating aerodynamic flows inside and around the cage 12, using market software such as Ansys Fluent®.
• the cage 12 has a first end 12a and a second end 12b which are opposite.
• the first end 12a has an opening 121 which communicates with the chamber 10. More particularly, when the cage 12 is fixed to the base 113 of the chamber 10, the opening 121 is positioned in a passage 111 produced in said base, which passage opens into chamber 10.
• the opening 121 and passage 11 have a section (shape and size) which corresponds to that of the cage 12.
• a transparent window 112 is arranged opposite the opening 121.
• this window 112 is inserted in the passage 1 11. It forms the gas seal between the chamber 10 and the cage 12, so that the gas flowing in said cage cannot penetrate inside said chamber.
• the chamber 10 is therefore sealed against the gas to be analyzed.
• dimensions of this window are between 10 mm and 20 mm in diameter and between 1 mm and 5 mm thick. This thickness range makes it possible to resist the pressure of the gas flowing in the cage 12, without deformation of the window 112, and therefore without impact on the light beam.
• the window 1 12 is preferably made of polished sapphire.
• This material has the main advantage of not catching the dust or the condensates contained in the gas to be analyzed, thus avoiding fouling and eventually obscuring said window even if precautions are taken to close the chamber 10 in an atmosphere. dry and clean during manufacture, and tightly.
• sapphire has the property of being almost transparent to infrared so that the passage of the portion of the light beam through the window 1 12 causes little loss of light power (little absorption and little thought). The use of this material does not require an anti-reflective treatment on the window 112.
• a tip 122 is attached to the second end 12b.
• This end piece 122 has for example a form of cylindrical plug closing off the second end 12b.
• This tip 122 is advantageously made of stainless steel and can be obtained by molding or machining. It is secured to cage 12 by welding, screwing, bolting, riveting, etc.
• the tip 122 has for example a length between 1 cm and 3 cm and an internal diameter corresponding substantially to the external diameter of the cage 12.
• the thickness of its side wall is for example between 0.1 cm and 1 cm.
• the tip 122 serves as a housing for an optical reflector 51.
• this reflector 51 is adapted to reflect, towards a detector of a spectrometer 4, part of a light beam propagating in the cage 12.
• the reflector 51, the opening 121, the passage 111 and the light source 40 are aligned along the same axis XX.
• the reflector 51 is a concave spherical mirror produced from a silicon support on which is located, exposed to the light beam, a polished aluminum deposit covered with '' surface hardening treatment.
• This mirror 51 makes it possible not only to concentrate the light beam, but also to operate a desired magnification of this beam.
• the radius of the sphere of the mirror 51 is for example between 100 mm and 250 mm. As explained further in the description, the radius of curvature depends on the length of the optical path between the light source 40 and a detector 41 of the spectrometer 4 (FIG. 2). The shorter the optical path, the smaller the radius of curvature.
• a high pressure of the gas may therefore require reducing the length of the optical path and, in fact, reducing the radius of curvature of the mirror 51.
• the length L can be optimized experimentally to maximize the signal-to-noise ratio of the absorption over the entire operating range in pressure and temperature of the probe S.
• the radius of curvature of the mirror 51 also depends on any magnification to be made between the real object (the light source 40) and the image (the sensitive surface of the detector 41 of the spectrometer 4).
• the reflector 51 is covered with a transparent window 510.
• This window 510 has the function of isolating the reflector 51 from the gas to be analyzed, and for this purpose forms gas tightness.
• the material of window 510 is advantageously polished sapphire, for the same reasons as those mentioned above.
• the chamber 10 houses in particular all the electronic components of the probe S, the optical elements of the spectrometer 4 and the light source 40 adapted to emit a light beam F.
• the spectrometer 4 is adapted to generate data for measuring the composition of a gas after analysis of at least part of the light beam F that has interacted with said gas. This analysis is based on absorption spectroscopy, and more particularly on near infrared absorption spectroscopy. This method well known to those skilled in the art makes it possible to determine the concentration of a gaseous compound by measuring the intensity of the electromagnetic radiation which it absorbs at different wavelengths.
• the spectrometer 4 for this purpose comprises two detectors 41 and 42 which are standard and known to those skilled in the art. They are each formed by one or more photosensitive cells (CCD, CMOS, ...) adapted to transform the photons captured into electrical signals. These detectors 41, 42 can each be arranged on a printed circuit board C41, C42.
• the light source 40 emits in the near infrared, on a wavelength spectrum between 1550 nm and 1850 nm.
• the light source 40 preferably consists of an assembly of one or more LEDs (light emitting diodes).
• LEDs light emitting diodes
• four LEDs are used to cover the whole spectrum and have sufficient light power.
• LEDs are advantageously integrated in the same electronic component.
• LEDs have the advantage of having a low thermal emissivity.
• the Applicant was able to observe during the prototyping phase that the temperature of the LEDs relative to the ambient temperature is increased by approximately 6 ° C., thereby reducing the risk of explosion in the event of a gas leak in chamber 10.
• the advantage of LEDs compared to a laser type lighting means is a lower geometric requirement, the laser being much more directive. This results in lower parts and labor costs and quick assembly.
• the LEDs are powered by a pulsed current at a certain frequency and set to a fixed current intensity setpoint: there is no active or dynamic regulation of the intensity of the LED control current.
• the intensity of the current is adjusted to a very high setpoint, for example 200 mA, or even 2 A by LED depending on their type, so as to obtain a maximum of light power.
• the supply current of the light source 40 may come from a current source integrated in the chamber 10 in the form of a battery, or may come from an external current source.
• the probe S includes a power cable allowing its connection to this external current source.
• An optical element 50 placed in the chamber 10 makes it possible to guide in the cage 12 a part Fn of the light beam F.
• This optical element is advantageously an optical separator placed between the light source 40 and the cage 12.
• the optical separator 50 a a cubic shape (separator cube). It is formed of two prisms assembled to each other according to their largest face (the hypotenuse). These larger faces are inclined at 45 ° relative to the incident beam F. The assembly can be done by gluing.
• the side of this cube has a length which corresponds to the diameter of the window 510. This length may however be slightly smaller as long as it is greater than or equal to the width of the light beam F which impacts it.
• the separator cube 50 preferably has an anti-reflective treatment. To optimize the optical path, the optical separator 50 is placed on the axis X-X, in the same alignment as the reflector 51, the opening 121, the passage 11 and the light source 40.
• An air gap forms the interface between the light source 40 and the optical separator 50.
• no light guide or optical fiber is used, which makes it possible to reduce costs and simplify the design of the S probe.
• the light source 40 emits light rays in all directions.
• a collimating lens 400 is disposed between the light source 40 and the optical separator 50. This lens 400 makes it possible to converge the rays of the beam F towards the separator 50. By placing the light source 40 very close in front of the focal point of this lens 400, the rays emerging from said lens are almost parallel and slightly convergent.
• the lens 400 is a standard collimation lens, which, advantageously, has not undergone an anti-reflective treatment in order to reduce costs.
• the separator 50 allows part Fn of the light beam F to pass to the cage 12 and deflects another part F2 at an angle of 90 °.
• the separator 50 therefore performs a first 90 ° angle bevel before the propagation of the light flux in the cage 12.
• the part F2 therefore does not interact with the gas to be analyzed.
• This part F2 impacts the second detector 42 of the spectrometer 4.
• the part F11 crosses the separator 50 in the same direction as the beam F, without deviation.
• This part F11 passes through the window 112 and enters the cage 12 to interact with the gas G to be analyzed.
• an air gap forms the interface between the separator 50 and the cage 12, no optical fiber being used.
• the part F11 then passes through the window 510 to be reflected by the reflector 51.
• the part F12 reflected follows the reverse path of the Fn part and still interacts with the gas G. there is therefore a double interaction of the light flux with the gas G in the cage 12: an "aisle" interaction on the Fn part and a "return” interaction on the part F12.
• the part F12 reflected passes through the window 1 12 and enters the chamber 10 to impact the separator 50.
• the separator 50 deflects the part F12 at an angle of 90 ° (part F13).
• the separator 50 therefore performs a second angle transmission at 90 ° after the propagation of the light flux in the cage 12, that is to say after the interaction with the gas to be analyzed.
• the part F13 then impacts the first detector 41 of the spectrometer 4.
• the spectrometer 4 can thus measure the composition of the gas G as a function:
• This measurement is made in less than a second, so that the S probe is able to measure instantaneous variations in the composition of the gas and allow very precise control of gas appliances to ensure optimal combustion.
• the signals emitted by the detectors 41 and 42 are transmitted to a processing unit 43 of the spectrometer, which unit is adapted to process these signals and generate data for measuring the composition of the gas G.
• the measurement method is well known in the art. skilled in the art and is not part of the invention.
• the processing unit 43 is in the form of one or more printed circuit boards carrying electronic components making it possible to generate the measurement data and the electrical supply of the light source 40.
• the processing unit 43 comprises in particular one or more processors (including microprocessors and / or FPGA (Field-Programmable Gate Array) and / or microcontrollers), and one or more memories.
• processors including microprocessors and / or FPGA (Field-Programmable Gate Array) and / or microcontrollers
• One or more computer applications - or computer programs - are recorded in the memory or memories and whose instructions (or codes), when executed by the processor or processors make it possible to achieve the functionalities of the spectrometer 4 and more generally the functionalities of probe S.
• the processing unit 43 is common to several functional elements of probe S, including for example: a gas temperature sensor, an LED temperature sensor, temperature sensors of each detector 41, 42, a gas pressure sensor, and a gas thermal conductivity sensor described further in the description.
• the processing unit 43 can be associated with a communication module 44 wired (Ethernet or CAN protocol type) or wireless (WiFi or Bluetooth transmitter / receiver type) suitable for receiving instructions and / or transmitting the results of the measurements carried out in particular digitally.
• the measurement and calculation acquisition cycles are carried out by alternating switching on and off of the light source 40.
• the light beam F is emitted intermittently, preferably at the frequency of 16 kHz (+/- 1 kHz), and synchronized with the reception of the light flux on the detectors 41, 42. More precisely at each acquisition and calculation cycle, which may last for example 500 ms, the beam F is activated by successive sequences of a few milliseconds so as to illuminate the detectors 41, 42 successively on their different acquisition frequencies. At the end of this frequency sweep, the beam F is extinguished during the time of the calculation cycle, or over a significant period of this cycle, such as for example 100 ms.
• These different extinction phases, even very short periods, caused by the pulsed mode, the frequency sweep and the calculation time total up to for example 40% of the time and make it possible to cool the light source 40 which, in turn, , heats up as soon as it is on.
• the motherboard carrying the processing unit 43 and the electronic components making it possible to manage the electrical supply of the light source 40 is geographically distant from the light source 40 and from the cards C41, C42 carrying the detectors 41, 42.
• This motherboard is the main source of heat. This geographic distance is for example between 20 mm and 250 mm.
• the motherboard is installed on the back of the chamber 10, opposite the optical part which is close to the gas to be analyzed. In FIG.
• the motherboard C43 is pressed against the internal surface of the bottom wall 100 of the chamber 10, which wall is opposite the cage 12.
• the bottom wall 100 is preferably metallic, in order to facilitate the heat exchange with the outside of the chamber 10.
• cooling fins 101 are arranged on the external surface of the bottom wall 100, which fins accentuate the transfer of calories towards the outside of the room 10. Depending on the quality of the electronic components selected, these fins are not necessary, however.
• the S probe can operate in its environment without producing annoying electromagnetic disturbances for everything inside the Faraday cage that the chamber 10 forms (EMC electromagnetic compatibility), or suffer if such electromagnetic interference is produced.
• EMC electromagnetic compatibility electromagnetic compatibility
• shielded connection cables are used inside the chamber 10, to connect the various components and / or cards.
• the cables used are for example made up of layers of wires, for example 10 wires, which have an alternation of working wires and wires connected to ground. Each ground wire carries out the shielding for two working wires which are adjacent to it.
• most of the chamber 10 can be filled with a resin or with an elastomer (for example a "compound"), having conventional properties.
• the spectrometer 4 (light source 40, separator 50 and detectors 41, 42) is left free, that is to say that the spaces between the components are not filled with resin or elastomer.
• the two detectors 41 and 42 make it possible to overcome this problem by controlling this variation in the light intensity.
• the first detector 41 measures the intensity of the beam portion F13 (measurement intensity) after passage through the gas to be analyzed.
• the second detector 42 measures the intensity of the part F2 of the light beam (reference intensity) before passing through the gas G to be analyzed.
• Applying Beer Lambert's law to the two signals gives the light intensity absorbed by the gas.
• the absorbance A of the gas verifies the law:
• lo is the signal measured by the second detector 42 obtained by extrapolation of the reference signal
• I is the signal measured by the first detector 41.
• the processing unit 43 takes into account any variation in the light intensity and / or the frequency spectrum of the light beam. F.
• the probe S may include a temperature sensor of the LEDs and temperature sensors of each detector 41, 42, these sensors being integrated in the chamber 10.
• a pressure sensor in contact with the gas and / or a temperature sensor (reference 60 in FIGS. 1A, 1 B and 1 C), in contact with the gas, can be fitted on the base 1 13.
• the corrections made by these sensors are known from the prior art and for example mentioned in the aforementioned patent document US9291610 (ZELEPOUGA).
• the gas temperature sensor 60 is advantageously in the form of a rod which projects from the base 113.
• a platinum resistance probe (or another similar sensor) is housed in this rod, at the level of the end which is furthest from chamber 10. This arrangement makes it possible to maintain the temperature sensor 60 away from chamber 10. Since the latter does not have the same temperature as the gas, it does not influence the measurement.
• An air gap (and not an optical fiber) forms the interface between the separator 50 and the first detector 41.
• a first lens 410 and a first diaphragm 411 are arranged in this air gap, The beam part F13 first crosses the first lens 410 then the first diaphragm 411 before impacting the first detector 41.
• the first lens 410, the first diaphragm 411 and the first detector 41 are aligned along the same optical axis.
• the first diaphragm 41 1 is pressed against the first lens 410. It is preferable not to install an optical filter in front of the first detector 41 to maintain optimal light power. Indeed, an optical filter is likely to reduce the light power by about 10%.
• the first lens 410 is a standard converging lens. To reduce costs, the first lens 410 does not undergo any anti-reflective treatment. It allows the rays of the beam portion F13 to converge towards the photosensitive face of the first detector 41, so as to optimize the capture of photons at the level of said first detector.
• the beam portion F13 which impacts the first detector 41 may have a cone angle that is too large relative to the photosensitive face of said detector. Spurious reflections then occur within the detector 41 which disturb the spectral resolution of the said detector, thereby causing a degradation in the quality of its response.
• the first diaphragm 411 solves this problem for this first detector 41 by using only one lens. It limits the angle of the cone of the beam portion F13 and reduces parasitic reflections in the first detector 41. Its opening is calculated to respect the maximum cone angle specified for this type of detector, from the distance between the diaphragm 41 1 and the detector 41. Software on the market such as OpticStudio® developed by the company Zemax allows for example to make these calculations.
• the diameter of the opening of the first diaphragm 411 is for example between 100 ⁇ m and 4000 ⁇ m.
• a similar assembly is provided at the second detector 42.
• An air gap (and not an optical fiber) interfaces between the separator 50 and the second detector 42.
• a second lens 420 and a second diaphragm 421 are arranged in this air gap.
• the portion of beam F2 not having interacted with the gas G, first crosses the second lens 420 then the second diaphragm 421 before impacting the second detector 42.
• the second lens 420, the second diaphragm 421 and the second detector 42 are aligned along the same optical axis.
• no optical filter is placed in front of the second detector 42.
• the object is the light source 40 and the image is the photosensitive face, respectively of the first detector 41 and the second detector 42.
• the components which participate in this enlargement are essentially the lenses 400, 410, 420, the diaphragms 41 1, 421 and the concave mirror 51.
• the light source 40 is for example made up of 2 different LEDs, but complementary in terms of their spectral bands. These LEDs are doubled to form a monobloc component of 4 higher power LEDs. Identical LEDs are arranged on the same diagonal to maximize the light power available over the entire frequency bandwidth when the axis of this beam is not perfectly centered on the various optical components in transmission or reception.
• the magnification is effected by the lenses 400 and 410, by the concave mirror 51 and by the first diaphragm 411.
• the image of the light source 40 is reproduced, in a diffuse and distorted manner, after the image focus of the first lens 410, at the focusing distance (also called focusing distance) of the optical path of measure F, F 11 , F 12 , F13, precisely where the photosensitive face of the first detector 41 is placed.
• the play of the two lenses 400, 420 would give a faithful, non-diffuse and non-deformed image, in particular in terms of dimensions, of the 4 LEDs at the focusing distance of the reference optical path F, F 2 , before the focal point of the receiving lens.
• the light source 40 is 300 microns in diameter, and the sensitive face of the detector 42 is only 100 microns, this image would show the detector only the center - black - of these 4 LEDs.
• the distance between diaphragm and detector can be longer for the beam F2 than for the beam F 13 .
• the second diaphragm 421 in all points identical to the first diaphragm 411 differs from the latter by the dimensions of its opening, dependent on this distance.
• the second lens 420 is identical to the first lens 410.
• the distance between said lens 420 and the center of the separating cube 50 is immaterial. This distance is therefore greatly reduced, to almost 1 mm for example, to contribute to the compactness of the chamber 10.
• the distance between the lens 410 and the center of the separator cube 50 is linked to the distance between mirror and separator cube, and to the radius of curvature of the mirror (spherical).
• the optical path through the gas has a total length of 40 cm, with a round trip in the measured gas area, thanks to a mirror.
• This length results from a balance between the power of the LEDs, and a measurable absorption of light, neither too weak nor too strong, in relation to the density of molecules found in the measured space, this for a range of pressures and temperatures respectively from 0 to 10 bar relative, and 3 ° C to 50 ° C. No particular tolerance is imposed on this distance: deviations from this distance are compensated for during sensor calibration.
• FIG. 4 illustrates an alternative embodiment of the probe S. Only the first detector 41 is used. In comparison with the embodiment of FIG. 3, there is no analysis of the part F2 of light beam.
• This solution is suitable when LEDs are used as a light source, insofar as they are relatively stable, with little or no variation in their light intensity and / or frequency spectrum.
• the optical separator 50 is replaced by another optical element 50 ’suitable for guiding: towards the cage (12), the part F11 of the light beam F emitted by the light source 40; and towards the detector 41: the part F13 having propagated in the cage 12 and having interacted with the gas G.
• the optical element 50 ′ is for example in the form of a semi-reflecting plate inclined at 45 ° by relation to incident beam F.
• FIG. 5 also illustrates an alternative embodiment of the probe S.
• a thermal conductivity sensor 6 is arranged on the probe S so that it can interact with the gas G.
• This sensor 6 is more particularly fixed on the base 113 of the chamber 10, outside the cage 12, so that it is not on the optical path.
• the sensor 6 is connected to the processing unit 43 so that the signals which it transmits are transmitted to said unit. This is adapted to generate data for measuring the composition of gas G by taking these signals into account.
• the probe in FIG. 5 is particularly suitable for measuring the level of hydrogen present in the gas.
• the regulations currently in force limit the rate of hydrogen (0% in England and Belgium, 4% in Switzerland, 6% in France, 10% theoretically but 2% practically in Germany) that can be injected into a gas distribution network .
• Actions are being taken in the context of the energy transition, for example at European level, to harmonize these limits and raise them so as to make hydrogen usable on a large scale, as a means of mass storage of renewable energies.
• gas appliances only accept relatively low hydrogen levels and generally do not support sudden variations in this rate.
• the measurement of the hydrogen level in pipes in which gas circulates therefore appears relevant, and is made possible by the S probe.
• the thermal conductivity sensor 6 does not require any particular maintenance or regular calibration in service, which makes it a component well suited to an industrial application, compared to other possibly more selective sensors, such as Electro-chemical hydrogen sensors, sensitive to saturation, fouling and poisoning described in the aforementioned patent document US9291610 (ZELEPOUGA).
• FIG. 9 illustrates an additional variant embodiment of the probe S.
• the cage 12 is here simply formed of a rigid upright, preferably made of stainless steel, at the end of which the end piece 122 is secured to which the reflector is housed optical 51. This amount is for example in the form of a rod or a flat bar.
• the attachment of the end piece to the upright can be carried out by welding, screwing, riveting, etc.
• the other end of the upright is secured in the same way to the base of the chamber 10, so that the optical reflector is aligned in the X-X axis.
• the upright is offset from this axis so as not to interfere with the optical path.
• This embodiment has the advantage of removing any obstacle (except the amount) on the path of the gas.
• this structure is less rigid and less robust than those illustrated in FIGS. 1 a, 1 b and 2 and must be reserved for an environment free from vibration.
• FIGS. 6A, 6B, 6C and 6D illustrate the installation of the probe S on a pipe C in which the gas to be analyzed circulates.
• the gas G and its direction of flow in the pipeline C are shown diagrammatically by the double arrow.
• Line C can be that of a gas pipeline or, the gas supply line of an appliance A using gas as fuel.
• An opening O is arranged on a wall of the pipe C.
• This opening O typically consists of a flange, or other arrangement initially provided for the installation of temperature or pressure probes for example. However, it may be an opening specifically designed for the probe S.
• the probe S is inserted into the opening O so that the cage 12 enters the pipe.
• the probe S is installed so that the longitudinal axis XX (which is also the axis of the optical path) of the elongated tube forming the cage 12 is perpendicular or substantially perpendicular (+/- 10 °) to the direction of flow of the gas G in the pipeline C.
• This configuration makes it possible to obtain particularly precise measurements.
• FIGS. 6B and 6C For pipes C of small diameter, for example less than 200 mm, preference is given to an installation according to the embodiments of FIGS. 6B and 6C.
• Line C is here cubit.
• the probe S is installed so that the longitudinal axis XX of the tube 12 is parallel or substantially parallel (+/- 10 °) to the direction of flow of the gas G in the elbow. Thanks to the turbulence created by the bend in line C, this configuration allows precise measurements to be obtained.
• the choice of an installation according to FIG. 6B or according to FIG. 6C may depend on the space available around the pipe C.
• FIG. 6D illustrates a configuration making it possible to overcome these drawbacks.
• the opening O and / or the flange 1 1 are shaped so that said flange is flush with the internal wall of the pipe C.
• the entire cage 12 is then in direct contact with the gas flow so that it does not there are no more dead zones.
• the installation according to FIG. 6D also applies to the configurations of FIGS. 6B and 6C.
• the probe S is held in position on the pipe C.
• This holding in position is for example carried out by screwing or bolting the fixing flange 11 on a complementary fixing flange arranged around the opening O. It provides a seal against the gas G flowing in the pipe C, at the opening O.
• This seal is in particular produced by a seal J disposed between the two fixing flanges.
• the measurement data generated by the probe S are advantageously transmitted to an electronic computer UC of the device A to which the pipe C is connected.
• This electronic computer UC is of the known type and makes it possible in particular to adjust according to the type of device, the gas and / or air ejection speed, air-gas ratio, ignition advance, etc.
• the UC computer will thus be able to instantly modify the settings and / or the operation of device A according to the data transmitted by the probe S.
• the S probe described in the preceding paragraphs because of the technical solutions adopted, is particularly inexpensive compared to other similar probes known from the prior art. Its response time being less than one second, it is perfectly suited for instant measurements, directly in the gas flow to be analyzed, without any sampling.
• FIG. 7 illustrates an alternative embodiment where a gas chromatography apparatus 9 is connected to the pipe C. This apparatus 9 is of the type known to those skilled in the art. A gas sample is taken from line C by means of an injection system
• the probe S and the chromatograph 9 are connected to a data processing unit
• This processing unit 91 is similar to the processing unit 43 described above. It receives the measurement data generated by the S probe and the measurement data generated by the chromatograph 9. The measurement data generated by the S probe are received almost continuously (time interval less than 1 second) and the data The measurements generated by the chromatograph 9 are received at a higher time interval (for example every 30 minutes). The processing unit 91 will then correct the measurement data generated by the probe S as a function of the measurement data generated by the chromatograph 9. These corrected data can then be communicated to the calculator UC of the device A.
• Chart 8 illustrates this correction.
• the curve in solid lines illustrates the continuous measurement of the concentration of the gas by the probe S, that is to say by spectrometry, and if necessary by thermal conductivity. It can be seen that the concentration (C%) varies over time (t).
• the points illustrate point measurements (at time t1, t2, t3 and t4) of the gas concentration by the chromatograph 9.
• the dotted curves illustrate the corrections made on the continuous measurement by spectrometry.
• the processing unit 91 finds that the concentration measured by spectrometry is lower than the concentration measured by chromatography. It will therefore adjust the results of the spectrometric measurement, correcting it for the delta (or difference) between the two concentrations measured. This delta will be added here to the results of the measurement by spectrometry.
• the processing unit 91 finds that the concentration measured by spectrometry (and corrected at time t1) is greater than the concentration measured by chromatography. The delta between the two measured concentrations will here be subtracted from the results initially corrected for the spectrometric measurement.
• the processing unit 91 finds that the concentration measured by spectrometry (and corrected at time t2) corresponds to the concentration measured by chromatography. The processing unit 91 then makes no additional correction.
• the processing unit 91 finds that the concentration measured by spectrometry (and corrected at time t2) is again lower than the concentration measured by chromatography. It will therefore readjust the results of the measurement by spectrometry, by adding to them the delta between the two measured concentrations.
• the same correction can be made on the measurement data of the hydrogen level deduced from the measurement data of the thermal conductivity sensor 6 and from the measurement data of the spectrometer 4.
• the chromatography apparatus 9 is adapted to measure directly the hydrogen level of the gas.
• the processing unit 91 can then correct the hydrogen level measurement data generated by the probe S as a function of the measurement data generated by the chromatograph 9. This correction is identical to that described previously with reference to graph 8.
• the chamber 10 and / or the base 113 and / or the flange 11 and / or the tube forming the cage 12, are not necessarily of circular section. They can be square, rectangular, oval, polygonal, etc.
• the tube 12 can be directly secured to the flange 11 in the case where the chamber 10 is devoid of base 113.
• the probe S can be provided with another means of fixing to the pipe than the flange 11. It is for example possible to arrange a thread on the external lateral wall of the chamber 10, which thread comes to engage in a complementary thread arranged in a tapping made in the wall of the pipe.
• the cage 12 can be in the form of a mesh plate shaped as a tube and / or support for the optical reflector.
• the opening 121 can lead directly into the chamber 10.
• the cage 12 can be shaped so that its second end 12b is initially closed, without adding the end piece 122, which second closed end supports the optical reflector 51.
• the light source 40 may in this case consist of a laser, for example if higher costs are accepted. We could also use a tungsten lamp or a halogen lamp for a vibration-free environment, if we accept shorter lifetimes.
• optical fibers make the interface between the light source 40 and the optical separator 50; and / or between the optical separator 50 and the cage 12; and / or between the optical separator 50 and the first detector 41; and / or between the optical separator 50 and the second detector 42.
• the processing unit 43 can be moved outside of the chamber 10. In which case, the signals emitted by the detectors 41, 42 are transmitted to the processing unit 43 by wire or wirelessly (for example by Bluetooth, ISM, Wifi, ANT, ZIGBEE, ). The gas composition measurement data are then generated outside of the chamber 10.
• the processing unit 43 and the data processing unit 91 may be one and the same processing unit.
• the arrangements and / or the characteristics of the various components installed in the chamber 10 and which have been described previously also apply to probes for measuring the composition of a gas. which are not provided with a cage 12.
• the assembly of FIG. 7 and the correction of the instantaneous measurements of the spectrometer by the punctual measurements of the chromatograph of FIG. 8, can be applied to other types of probes , including those described in patent documents US2006 / 0092423 (SERVAITES), US8139222 (SAVELIEV) and US9291610 (ZELEPOUGA), or EP2198277 (SP3H).

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• 2018
  • 2018-11-19 FR FR1871592A patent/FR3088720A1/fr active Pending
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