Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/59—Transmissivity
  • G01N21/61—Non-dispersive gas analysers
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
  • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
  • C03B5/235—Heating the glass
• • 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
  • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
• • 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
  • G01N2201/00—Features of devices classified in G01N21/00
  • G01N2201/06—Illumination; Optics
  • G01N2201/061—Sources
  • G01N2201/06113—Coherent sources; lasers
  • G01N2201/0612—Laser diodes

Definitions

• the invention relates to the field of the analysis of gas concentrations in hot atmospheres such as ovens, especially glass furnaces.
• the measurement of the concentration of combustion gases (CO, NO, NO2, etc.) produced by each burner of a glass furnace is usually carried out by an extractive technique.
• the air is drawn punctually by a pyrometer cooled by ducts passing through the walls or in the rear of the chambers of the regenerators. This air is then filtered, dried and analyzed by electrochemical sensors.
• the gas concentration measurement can then be used for the control of the combustion. Because of the problems of cooling and condensation of water vapor in the pyrometer, the extractive measurement can only be carried out for limited periods of time. This prevents continuous measurement of the flue gases and therefore an effective and continuous control of the combustion in the furnace.
• enclosure is to be taken in a broad sense, with regard to any container of the atmosphere to be analyzed.
• this enclosure may be a duct communicating combustion fumes to the outside of an oven, that is to say for example a duct connecting a furnace and a regenerator and serving alternately duct brought air to a burner and smoke collector.
• concentrations of the molecular species of interest are obtained from the measurement of transmission for each wavelength (Lambert- Beer).
• wall is meant any wall in the broad sense that is to say any physical limit of the enclosure (including the vault of an oven), since it is possible to cross the radius laser the hot atmosphere of the enclosure without this beam encounters obstacles absorbing too strongly.
• the laser beam is returned by a window according to the invention and is also extended by a window according to the invention, the laser meeting between these two windows that the hot atmosphere of the enclosure. If the laser passes through a glass furnace, the laser passes through the gaseous atmosphere above the glass. This atmosphere may contain fine particles.
• the laser solution according to the invention allows measurement continuously and during normal operation of the installation on which it is mounted.
• the device according to the invention can equip a glass furnace and continuously measure the concentration of gaseous species in the hot atmosphere during normal operation of the furnace.
• this oven can operate continuously.
• the laser radiation is not necessarily continuously present during the operation of the device to be controlled (such as an oven for example). Indeed, the variations in gaseous concentrations are slow enough so that measurements spaced by one or a few seconds are amply sufficient to appreciate the variations in gas concentrations. Such measurements are made by a pulsed laser.
• the device according to the invention can be applied to the analysis of the atmosphere of any type of glass furnace such as overhead or submerged burner melting furnaces, loop furnaces, transverse burner furnaces, these can be equipped with regenerators or recuperators, glass shaping furnaces and float furnaces for flat glass forming.
• any type of glass furnace such as overhead or submerged burner melting furnaces, loop furnaces, transverse burner furnaces, these can be equipped with regenerators or recuperators, glass shaping furnaces and float furnaces for flat glass forming.
• the invention proposes an optical system which makes it possible to transmit at least one laser radiation in the mid-infrared through a wall of an enclosure containing a hot atmosphere, in particular to measure the concentration of combustion gas, for example CO , NO, NO2.
• This continuous metrology makes it possible to optimize combustion and thus improve the energy efficiency of the furnace and the reduction of harmful gases.
• This system comprises a window relatively transparent to the spectral range of measurement, said window being able to be cooled by a dual water / air cooling system to withstand for a long time the normal operating conditions of the enclosure (such as a furnace), which implies a good resistance to temperature and thermal shock.
• the window may in particular be disposed on or in a wall of the enclosure, where appropriate via an insert.
• the window may in particular be incorporated in an insert, said insert being disposed on or in a wall of the enclosure.
• this type of optical insert it is possible to emit one or more laser beams to the inside of the enclosure, through the same window or different windows, while preserving the tightness of the orifices in the walls.
• This sealing prevents the release of gas (possibly harmful) from the hot atmosphere coming from inside the enclosure.
• the measurement length can be determined exactly since it corresponds substantially to the distance between the input window and the output window. As a result, the gas concentration value is accurate.
• sealing means above all that gas from the atmosphere inside the enclosure is obstructed to exit through the orifice provided with the window. This seal may be partial or total depending on the case.
• the invention relates firstly to a device for measuring the concentration of a molecule in a gaseous atmosphere at a temperature greater than 1200 ° C, said molecule comprising an absorption line at a wavelength of between 4 and 8 ⁇ , said device comprising a transmitter of laser radiation of wavelength corresponding to that of the ray of absorption, said emitter emitting the laser radiation through a first window and then through said atmosphere, said window being made of a solid material having a transmittance greater than 50% and preferably greater than 80% at the wavelength of the laser radiation and for a thickness of 1 mm, the laser radiation being analyzed after passing through said atmosphere by an analyzer determining the absorption of the laser radiation by the molecule in the gaseous atmosphere.
• the window necessarily has a thickness of 1 mm, it is simply to define an intrinsic transmittance value of the material, in this case for 1 mm of material thickness. Indeed, the transmittance decreases with the thickness and an intrinsic value can be given for a given thickness.
• the window may have a thickness of, for example, between 0.5 and 20 mm. The thinner the thickness, the more fragile the window. The greater the thickness, the lower the transmittance. For a glass furnace whose internal atmosphere is at a pressure close to atmospheric pressure, a window thickness in the range 2 to 5 mm (including terminals) is generally suitable.
• the device according to the invention comprises two windows made of a solid material having a transmittance greater than 50% and preferably greater than 80% at the wavelength of the laser radiation and for a thickness of 1 mm.
• the first window is crossed by the laser beam before it crosses the hot atmosphere.
• the second window is crossed by the laser beam after the passage through it of the hot atmosphere.
• the first window is therefore laser emission and the second is at the laser reception.
• the laser beam is advantageously thick enough so that the emerging signal is undisturbed by the occasional presence of particles in its path.
• the section of the window orthogonal to the laser beam has an area of at least 10 cm 2 and even at least 15 cm 2 .
• the area of the window is sufficient to pass the entire laser beam.
• the window preferably has an upper surface of minus 30% and even at least 50% at the area of the section of the laser beam.
• the hot atmosphere of the oven can slightly deflect the direction of the laser beam according to the fluctuation of its composition, temperature and particles in its path.
• the larger the reception window the greater the chances of collecting the entire laser beam.
• a window area of between 25 and 100 cm 2 is generally suitable.
• the wavelength of the laser beam depends on the nature of the molecules whose concentration is to be determined. The table below gives the wavelengths of the laser beam to be used according to the molecules sought:
• the window may especially be calcium fluoride (CaF 2 ), sapphire (Al2O3) or zinc selenide (ZnSe).
• CaF 2 calcium fluoride
• Al2O3 aluminum oxide
• ZnSe zinc selenide
• the three compounds which have just been mentioned are advantageously monocrystalline in the context of the invention. In the latter case, it is preferred that the laser beam cross the monocrystal orthogonally to the crystal plane ⁇ 1 1 1> for CaF 2 and ZnSe and orthogonally to the ⁇ 0001> (c-axis) crystalline plane for sapphire.
• the window is placed opposite (that is to say in the axis) of an orifice of a wall of the enclosure containing the hot atmosphere to be analyzed.
• the laser beam emitted through the window and the orifice of the wall.
• the orifice of the wall may for example be an orifice provided for cleaning the enclosure or be an orifice provided for the measurement.
• the window is preferably protected from the gaseous atmosphere by a flow of an inert gas (for example: air or nitrogen) vis-à-vis the material of the window injected between the window and the hot atmosphere.
• an inert gas for example: air or nitrogen
• This injection of inert gas prevents the window is covered with dust from inside the enclosure and ensures the possibility of long-term use without cleaning.
• the window may be incorporated in an insert, said insert being fixed to the wall (at the location of the wall opening), preferably in a sealed manner, to prevent the hot atmosphere of the enclosure from exit through the hole in front of which it is placed.
• This sealing can be obtained in particular with the aid of a refractory binder making the connection between the insert and the enclosure.
• the atmosphere in the chamber is substantially at atmospheric pressure, a perfect seal is not necessarily necessary.
• the invention relates to also an enclosure equipped with the device according to the invention, the device being mounted at least partially sealed or completely sealed to the enclosure.
• the window can be fixed in a metal part of the insert.
• This metal part comprises an orifice for the passage of the laser beam.
• This orifice of the metal part therefore passes through the entire metal part.
• the insert may comprise a tubular portion intended to be housed in the thickness of the wall of the enclosure.
• the recessed area of the tubular portion (the inside of the tube of the tubular portion) constitutes an orifice for the passage of the laser beam.
• this tubular portion may be connected to another portion comprising the window. The connection between these two parts can be achieved by a flange.
• the tubular part of the insert will undergo a temperature close to that prevailing in the furnace and must therefore be made of a material resistant to these temperatures as well as to thermal shocks.
• This material is advantageously more refractory than the metal constituting the metal part which can be made of a common steel. It may be a refractory ceramic (in particular mullite) or a refractory concrete or a refractory metal.
• the insert may comprise an inlet of inert gas relative to the material of the window protecting the window of the hot atmosphere of the enclosure in use condition. Thus, a flow of this gas arrives between the window (face of the window facing the interior of the enclosure) and the hot atmosphere to be analyzed.
• This gas of low flow rate (for example 0.1 to 50 Nm 3 / h) can then be directed towards the hot atmosphere and mix without substantially modifying the gaseous composition of the interior of the enclosure.
• the window may be incorporated in a metal part of an insert, said metal part comprising an orifice for the passage of laser radiation and possibly a cooling water box.
• the window obstructs the hole of the metal part and can be traversed by the laser beam.
• the laser beam can thus cross the entire insert, meeting as solid material only the window.
• the inlet of inert gas to protect the window may be located between the cooling water box and the window. It can also be the opposite, that is to say that the cooling water box is placed between the inlet of inert gas and the window.
• the insert may comprise a ceramic part integral with the metal part, said ceramic part being tubular and allowing the laser radiation to pass along its axis, the axis of the tubular part passing through the orifice of the metal part, the insert being oriented so that the ceramic portion is directed towards the gaseous atmosphere.
• the invention also relates to an insert comprising a window of calcium fluoride or sapphire or zinc selenide, a metal part comprising an orifice and a tubular portion of a more refractory material than the metal part, the tubular portion being secured of the metal part, the window being incorporated in the metal part by obstructing its orifice, the axis of the tubular part passing through the orifice of the metal part and the window, the metal part may comprise a water box, the metal part may comprise a gas inlet opening into the orifice of the metal portion between the window and the tubular portion.
• the laboratory volume of a furnace can be passed through the laser beam, whereby the laser radiation passes from a first sidewall (right) to a second sidewall facing the first wall.
• the entire furnace atmosphere can be passed through the laser beam between an upstream wall and a downstream wall.
• the path required for the laser beam may be a bit too long, so that the emerging beam would be a little too weak.
• the distance traveled by the laser in the hot atmosphere be within the range of 1 to 3 meters (inclusive). It may be the distance between two windows according to the invention, the window for transmitting the laser beam and the window for receiving the laser beam, the two windows framing the gaseous atmosphere to be analyzed.
• the laser beam may then be advantageous to place the laser beam at a place where the fumes are at least partially gathered like a chimney or a burner duct, that is to say the duct making the connection between a regenerator and an oven, said conduit ("port" in English) alternately serving as a burner air duct and as a flue gas outlet conduit to bring them to the regenerator.
• the laser measurement according to the invention is carried out only when the conduit serves to recover the fumes (and not when the conduit is used for the emission of air as a burner oxidizer).
• the laser device according to the invention can also be placed in the flue ("duct fumes" in English) between an oven and a recuperator.
• the invention also relates to a method for measuring the concentration of a molecule in a gaseous atmosphere at a temperature above 1200 ° C. and generally below 1700 ° C. by the device according to the invention.
• This molecule may especially be CO or NO or NO2.
• Several molecules can be analyzed simultaneously. To do this, it is generally used several laser sources, each having an absorption line of a molecule to be analyzed, and then is passed through the various laser beams the hot atmosphere to be analyzed. The different laser beams can be mixed in a single beam before crossing the hot atmosphere.
• the invention also relates to a method of heating glass in a glass furnace equipped with burners whose combustion fumes are analyzed by the measuring method according to the invention.
• FIG. 1 represents an oven 1 equipped with the device according to the invention.
• a laser transmitter 2 emitting in the wavelength range 3 to 24 ⁇ emits the laser radiation 3 through a window 4 fixed on an insert 5, said insert 5 passing through the side wall 6 of the oven 1.
• the laser radiation 3 passes through the hot atmosphere 7 of the oven and emerges from this atmosphere through a window 8 placed in an insert 9 passing through the side wall 10 of the oven opposite the side wall 6.
• the outgoing laser beam is then operated by a analyzer 1 1 to determine the concentration of a given gas in the atmosphere 7 of the furnace from the absorption value of the laser radiation.
• the laser radiation was oriented and moved from the transmitter to the analyzer by a set of mirrors 12.
• FIG. 2 represents an optical insert according to the invention. It comprises a tubular portion 20 made of refractory cement (Licofest MW95C or Licofest H195C) and a metal part 21. These two parts are held together by a flange system 22.
• the refractory cement portion 20 is intended to be inserted into the thickness of the wall of the furnace.
• the recessed area of this tubular portion (near the axis) serves to pass the laser beam.
• the metal portion 21 serves to maintain and cool the window 23 may for example consist of a cylindrical single crystal of calcium fluoride (CaF 2 ) with a diameter of 50 mm and a thickness of 3 mm.
• This metal part includes an orifice (near the axis) for the passage of the laser beam.
• the window 23 obstructs the orifice of the metal part and is traversed by the laser beam.
• the window 23 is protected from hot gases from the furnace by a water box 24 and by air cooling.
• the water box is of the annular type, that is to say that it goes around the orifice of the metal part without obstructing the center near the axis of the insert.
• the water box is supplied with water by a pipe 25, the water emerging from the 26.
• the air is injected through pipes 27.
• the flow of air injected in front of the window 23 is for example about 5 Nm 3 / h.
• the injected air then passes into the hot atmosphere of the oven. This prevents accumulation in the insert of dust from the oven.
• the amount of air coming from the insert and injected into the oven is negligible compared to the volume of the internal atmosphere of the oven.
• the air inlet opens into the hole of the metal part and is located between the window and the tubular part.
• the air inlet to protect the window is placed between the gaseous atmosphere and the water box.
• the insert of Figure 2 can be used for the emission of the laser beam or its reception.
• FIG. 3 represents a loop oven that can be used in the context of the present invention, seen from above.
• This furnace comprises an upstream face 31, two lateral faces 32 and 32 'and a downstream face 33. It is provided with two identical regenerators 34 and 34', juxtaposed and placed both behind the upstream face. Each regenerator is placed behind one half of the upstream face. Niches 36 and 36 'are formed in the side walls 32 and 32' for the introduction of vitrifiable materials. These niches are placed in the first third upstream of the side walls.
• a dam 35 immersed in the molten bath is provided in the downstream half of the furnace. In the case of Figure 3, the flame is from a half 1a of the upstream face.
• the laser beam 38 of a device according to the invention passes through the duct between the oven and the regenerator 34 'and is used for the analysis of the combustion gases.
• the operation of the oven is reversed according to FIG. 4. In this case, the flame comes from the half 1b of the upstream face and the heat of the fumes is recovered in the Another regenerator 34.
• Another device according to the invention generating the laser beam 39 is used and placed to pass through the duct between the oven and the regenerator 34 '.
• FIG. 5 shows a furnace with transverse burners seen from above.
• the vitrifiable materials are introduced through recesses 15 and 15 'located upstream in the side walls. Many transverse burners 16 equip the side walls.
• the fumes are collected by the duct 18 and conducted to the recuperator 17.
• the glass is recovered through the outlet 18.
• a recuperator operates on the model of a heat exchanger, the fumes passing through a warming channel of the air passing through another channel and supplying the transverse burners.
• the laser 19 of the device according to the invention passes through the conduit 18 for the analysis of the combustion gases.
• Figure 6 shows a furnace 41 with transverse burners and regenerators.
• the furnace 41 comprises an upstream wall 43, a downstream wall 44 and two side walls 45 and 45 '.
• the vitrifiable materials are introduced from the upstream wall 43 by a usual device not shown.
• the vitrifiable melted materials flow from upstream to downstream as represented by the arrows.
• the glass passes through an ember 47 for thermal conditioning purposes before going into the processing unit (not shown) and possibly being a float glass installation for the production of flat glass.
• Furnace 41 is equipped through its two side walls with two rows of four overhead burners operating one after the other.
• Each overhead burner comprises at least one fuel injector fed with gas via lines 68 and 68 ', and a hot air inlet 69 and 69'.
• the first two burners of each side wall are in the first third upstream of the furnace (the limit of this first third is indicated by a transverse dotted line 48).
• the openings 69 and 69 ' alternately play the role of hot air intake and that of smoke collector. They are each connected to a regenerator 50, 50 '.
• the injectors of the wall 45 work, those of the wall 45 'do not work.
• the fumes pass through the ducts 69 'of the side wall 45' in front of them and their heat is recovered in the regenerators 50.
• the operation of the furnace is reversed, that is to say that is to say that is to say that the operation of the burners of the wall 45 (stopping of combustible gas through the pipe 8 and stopping air through the ducts 69) is stopped and the overhead burners of the wall 45 'are started up supplying its injectors with gas through line 68 'and supplying the ducts 69' with hot air.
• the air is warm thanks to the heating by the regenerators 50.
• we reverse again the oven operation and so on (repetition of the inversion cycle).
• the combustion gases can be analyzed by the series of devices 70 according to the invention, the laser beams passing through the ducts. 69. It is possible to place a device according to the invention at each duct 69. During the time it is the regenerators 50 'which are in reception of the fumes emitted by the burners located in the wall 45, the combustion gases can be analyzed by the series of devices 70 'according to the invention, the laser beams pass through the conduits 69'. A device according to the invention may be placed at each duct 69 '. Thus, this system has an individual gas analysis for each burner, which allows their adjustment individually.
• the window does not break during the installation of the insert and keeps its transparency.
• the window was mounted in an insert as shown in Figure 2 with water box and sweeping in front of the window by fresh air.
• the window temperature measured during a test was 60 ° C for a furnace temperature of 1500 ° C.

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• 2011
  • 2011-02-14 FR FR1151167A patent/FR2971587B1/fr not_active Expired - Fee Related
• 2012
  • 2012-02-09 EP EP12708892.0A patent/EP2676124A1/de not_active Withdrawn
  • 2012-02-09 BR BR112013019480-4A patent/BR112013019480A2/pt not_active Application Discontinuation
  • 2012-02-09 JP JP2013553982A patent/JP2014509393A/ja active Pending
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  • 2012-02-09 WO PCT/FR2012/050286 patent/WO2012168588A1/fr active Application Filing
• 2013
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