CA2155339C - A method for measuring temperature, molecular composition or molecular densities in gases - Google Patents
A method for measuring temperature, molecular composition or molecular densities in gases Download PDFInfo
- Publication number
- CA2155339C CA2155339C CA002155339A CA2155339A CA2155339C CA 2155339 C CA2155339 C CA 2155339C CA 002155339 A CA002155339 A CA 002155339A CA 2155339 A CA2155339 A CA 2155339A CA 2155339 C CA2155339 C CA 2155339C
- Authority
- CA
- Canada
- Prior art keywords
- molecular
- temperature
- molecules
- densities
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
A measuring technique and method are provided to simultaneously determine the molecular density of several molecular species and the temperature within a closed process room in a melting or combustion process. In such processes in the industry, e.g. in metallurgic process industry, it is important to determine the temperature and the contents within the gas or flame without physically connect to or disturb the process. This has shown to raise large problems especially at high temperatures. The radio signal over a frequency band is measured on the outside of the process room through a window in the mantel covering as a function of frequency and registered on a computer as a radio spectrum. The system is calibrated by using a known signal transmitted through the process room. The spectral lines are identified by their frequency from a database. The temperature is determined from several lines of the same molecular specie and the molecular densities are determined from the intensities of the lines. The method is suitable to determine vibrational and rotational excitation of molecular species in the radio wavelength range of 500 m et 30 µm. The densities of molecular species and the temperature can be imaged in three dimensions inside the process room or exhaust channel if interferometers are used for simultaneous two dimensional imaging from several azimuth directions.
Description
A method for measuring temperature, molecular composition or molecular densities in gases.
This invention relates to a method for measuring temperature, molecular densities and _ molecular composition or any combination thereof, in gases and/or flames in melting and/or combustion processes.
Conventional gas analysis methods using IR-paramagnetic- and masspectrometer technology need a psychical contact with the gas to be analysed. This means that the gas :hue to be cooled before entering the analyser which may affect the results of the measurements.
Another disadvantage with conventional gas analysers is that they can not simultaneously measure the temperature of the gas and analyse the gas.
It is known that the attenuation of a continuum radio signal can be used to recover the amount of black smoke in exhaust fumes, JP 60-64234. This patent method does not determine any molecular content, nor does it determine any temperature.
It is also known that the changes in refractive index of flying ash can be used to determine the carbon content therein, WO 90/03568. This patent method does not distinguish between molecular species and does not measure any spectral Iines or determine molecular densities, configuration, or temperature.
It is also known that attenuation and reflection in the exhaust fumes from a reaction engine can be used to determine changes in the exhaust fume composition, WO 90/03568. This method does not determine any molecular species or temperature.
It is also known that the existence of a specific molecular specie can be decided if the molecular gas is first mixed with a drive gas and then injected into a cavity chamber, as taught in United States patent No. 5,124,653.
The cavity is then adjusted to the wavelength of the molecular transition and the molecular gds is excited by injecting a radio signal. The radio transmitter is then tamed off and the molecule will emit at its specific frequency if it is present. This method measures a sinLl~ molecular line at the time and can ~nlv detect the molecular species far which it is specifically adjusted. This method does not measure the temperature or the molecular density within the process since the molecular gas has to be taken out of the process-room to the special cavity and the gas is also contaminated with a drive gas.
None of the above patents discloses, discusses, or makes possible the simultaneous determination of a multiple of molecular lines and species or can determine molecular densities and temperature in a working melting process or combustion process without any interaction with the gas flow.
Changes in the pattern of electromagnetic wave fronts represent the most sensitive probes in physics. Electromagnetic waves may penetrate media of varying physical properties, changing its amplitude and phase in a way which is specific to the content of the media. Thus~molecular gas will emit or absorb electromagnetic radiation mainly depending on its density, the physical temperature, or the radiation field in the area where the gas resides.
Continuum radiation will also be affected when penetrating a media in the sense that the amplitude will be attenuated and the propagation velocity will change, resulting in a sudden change of phase in the interface area. The radioband is of particular interest in that here waves can penetrate deeper into dusty areas and also detect and measure complicated molecules by their rotational transitions.
It is an object of the invention to provide an accurate and reliable method to analyse a gas and to determine the temperature of a gas directly in an industrial process without physical contact with the gas that is being analysed and without disturbing the gas and the process.
A method for measuring temperature, molecular compositlon or molecular densities or any combination thereof of high-temperature collision-excited molecules forms one aspect of the invention. T'he method is characterized in that it comprises:
measuring an emission spectrum of the molecules in the radio range defined as wavelengths between 500 m and 30 pm with a radio antenna positioned apart from the molecules;
transmitting a signal through the molecules; detecting a corresponding background transmitted signal an which the emission spectrum is overlaid; measuring spectral lines emitted by the molecules; and determining from the background transmitted signal and measured spectral lines the temperature, molecular composition or molecular densities or any combination thereof.
The invention will be described more closely with reference to the drawings.
Fig 1 shows an experimental set up Fig 2 shows schematically a more sophisticated apparatus Fig 3 is a top view of the apparatus of Fig 2 Fig 4 is a representation of a spectrum observed in a chimney Fig 5 illustrates the identification of spectral lines from an observation Each molecular species has its own fingerprint in the form of a spectrum of lines, in the radio domain mainly determined by the quantified transitions between vibrational-and/or rotational states. Molecular lines in the atmosphere are very much broadened due to the relatively high pressure. The most significant exception is if the molecular floor is hi,hly directive, e. <_. if v~~e are looking through the flaw at an angle perpendicular to that of the flow. In that case the pressure broadening will be much less and molecular fines can be well separated. This exception is the case for gas flow in chimneys or through the gas flaw from any burning process if viewed across the flow.
_ The invention can be best described with an experimental set-up shown in Figure 1. Here a chimney ( 11 ) is made out of ceramic material, chrome-magnesite and charmotte, and covered with steel. The chimney has an opening (12) For an oit burner. The steel cover has two opposite windows (13), with intact ceramic material, Outside the windows (13) and in line with the windows are two parabolic antennas ( 14,1 S). One of the parabola is connected to a transmitter ( I 6) and the other parabola ( I S) is connected to a receiver ( 17}. The transmitter consists of a signal generator which is stepped in frequency over a wide frequency band. The received signal is compared with the transmitted signal in a cross-correlator (l8) connected to a computer (I9). .
The received signal consists of a number of spectral lines emitted from the gas inside the chimney overlaid on the background transmitted signal. The transmitted signal is used to calibrate the frequency response of the system and the attenuation through the chimney walls by looking at the received signal between the molecular lines. This baseline will then be subtracted from the received signal and the intensities of the molecular spectral lines can be determined as calibrated inside the chimney.
The system is further calibrated by measuring the signal transmitted through the chimney as a function of frequency when the chimney is empty .
The registered spectrum is stored in a computer. A database is searched for known lines which coincide in frequency with maxima ' within the observed spectrum. ~~eafter, a Gaussian model fit is made to the line in order to determine the amplitude, frequency, and line width. A
line is considered to be detected if the amplitude of the Gaussian fitted Line is more than three times the calculated noise level. The measured amplitudes are then calibrated to an absolute temperatur a scale.
If a number of lines from the same molecular specie can be detected, then the relative population of the various energy levels maybe determined. This relation is mainly determine:' by the physical temperature of the gas and the density of the molecular specie as:
Nulgu - NrotlQ(Trot) e-E"~rot where Nu is the number of molecules in the upper energy level of the transition, gu is the statistical weight of the transition, E" is the energy of the upper energy level in Kelvin, Q is the rotational constant.. Trot is physical temperature, in the case of burning processes where the excitation is dominated by collisions due to the high temperature, and Nrot is the column density of the molecules of this particular specie.
Nu/gu is directly proportional to the intensity integrated over the spectral line and can therefore be measured. If a number of spectral lines from a molecule are available, then both the density (if the path length is known) and the physical temperature (if the molecule is predominantly collision excited) can be determined simultaneously. If lines from other molecules are also present, then s also the densities of these molecules may be measured from the intensity of a single molecular line.
The radio antenna can also consist of an interferometer where the elements are radio horn antennas mounted in a plane (31,32) and with properly adjusted delay lines as shown in Figure 2~ Then, a two dimensional distribution of molecular densities and temperature of the gas or flame 35 can be constructed by transforming from the aperture (u,v) plane to the image plane.
If the system consists of interferometers (32) which are looking into the process room or exhaust channel from different angles as is shown in Figure 3, then the densities and the Temperature of the gas or flame 35 may also be recovered in three dimensions by a Radon transform, similar to what E
is used tn computer tomagraphy. Such a system can recover the temperature distribution in three dimensions within a hot gas (or a flame). It can also, which will be more important, simultaneously recover the three dimensional density distrihutiorr ojeach detectable molecular specie. These measurement are also performed without any physical probe since the radio signal may, as indeed was the case in our pilot experiment that will be described penetrate .
thror~gh the ceramic wall of the chimney.
In the apparatus shown in Fig 2, an experiment was carried Qut. A.n oxyloil burner was installed and was burning in a steady state.
Fig. 4 shows the spectrum observed in the tadioband 20-40 GHiz through the flew in the chimney. Mast of these lines come from S02, some others from IV'H3 and other molecules. It is therefore clearly possible to detect molecules within the radioband in gas flows on earth. As a consequence it is then also possible to make images of such a flow. Fig. 5 shows the identifications of some of the lines from one observations. Using S02 as a tracer it was possible to determine the temperature as well as the density of S02 as function of time.
This invention relates to a method for measuring temperature, molecular densities and _ molecular composition or any combination thereof, in gases and/or flames in melting and/or combustion processes.
Conventional gas analysis methods using IR-paramagnetic- and masspectrometer technology need a psychical contact with the gas to be analysed. This means that the gas :hue to be cooled before entering the analyser which may affect the results of the measurements.
Another disadvantage with conventional gas analysers is that they can not simultaneously measure the temperature of the gas and analyse the gas.
It is known that the attenuation of a continuum radio signal can be used to recover the amount of black smoke in exhaust fumes, JP 60-64234. This patent method does not determine any molecular content, nor does it determine any temperature.
It is also known that the changes in refractive index of flying ash can be used to determine the carbon content therein, WO 90/03568. This patent method does not distinguish between molecular species and does not measure any spectral Iines or determine molecular densities, configuration, or temperature.
It is also known that attenuation and reflection in the exhaust fumes from a reaction engine can be used to determine changes in the exhaust fume composition, WO 90/03568. This method does not determine any molecular species or temperature.
It is also known that the existence of a specific molecular specie can be decided if the molecular gas is first mixed with a drive gas and then injected into a cavity chamber, as taught in United States patent No. 5,124,653.
The cavity is then adjusted to the wavelength of the molecular transition and the molecular gds is excited by injecting a radio signal. The radio transmitter is then tamed off and the molecule will emit at its specific frequency if it is present. This method measures a sinLl~ molecular line at the time and can ~nlv detect the molecular species far which it is specifically adjusted. This method does not measure the temperature or the molecular density within the process since the molecular gas has to be taken out of the process-room to the special cavity and the gas is also contaminated with a drive gas.
None of the above patents discloses, discusses, or makes possible the simultaneous determination of a multiple of molecular lines and species or can determine molecular densities and temperature in a working melting process or combustion process without any interaction with the gas flow.
Changes in the pattern of electromagnetic wave fronts represent the most sensitive probes in physics. Electromagnetic waves may penetrate media of varying physical properties, changing its amplitude and phase in a way which is specific to the content of the media. Thus~molecular gas will emit or absorb electromagnetic radiation mainly depending on its density, the physical temperature, or the radiation field in the area where the gas resides.
Continuum radiation will also be affected when penetrating a media in the sense that the amplitude will be attenuated and the propagation velocity will change, resulting in a sudden change of phase in the interface area. The radioband is of particular interest in that here waves can penetrate deeper into dusty areas and also detect and measure complicated molecules by their rotational transitions.
It is an object of the invention to provide an accurate and reliable method to analyse a gas and to determine the temperature of a gas directly in an industrial process without physical contact with the gas that is being analysed and without disturbing the gas and the process.
A method for measuring temperature, molecular compositlon or molecular densities or any combination thereof of high-temperature collision-excited molecules forms one aspect of the invention. T'he method is characterized in that it comprises:
measuring an emission spectrum of the molecules in the radio range defined as wavelengths between 500 m and 30 pm with a radio antenna positioned apart from the molecules;
transmitting a signal through the molecules; detecting a corresponding background transmitted signal an which the emission spectrum is overlaid; measuring spectral lines emitted by the molecules; and determining from the background transmitted signal and measured spectral lines the temperature, molecular composition or molecular densities or any combination thereof.
The invention will be described more closely with reference to the drawings.
Fig 1 shows an experimental set up Fig 2 shows schematically a more sophisticated apparatus Fig 3 is a top view of the apparatus of Fig 2 Fig 4 is a representation of a spectrum observed in a chimney Fig 5 illustrates the identification of spectral lines from an observation Each molecular species has its own fingerprint in the form of a spectrum of lines, in the radio domain mainly determined by the quantified transitions between vibrational-and/or rotational states. Molecular lines in the atmosphere are very much broadened due to the relatively high pressure. The most significant exception is if the molecular floor is hi,hly directive, e. <_. if v~~e are looking through the flaw at an angle perpendicular to that of the flow. In that case the pressure broadening will be much less and molecular fines can be well separated. This exception is the case for gas flow in chimneys or through the gas flaw from any burning process if viewed across the flow.
_ The invention can be best described with an experimental set-up shown in Figure 1. Here a chimney ( 11 ) is made out of ceramic material, chrome-magnesite and charmotte, and covered with steel. The chimney has an opening (12) For an oit burner. The steel cover has two opposite windows (13), with intact ceramic material, Outside the windows (13) and in line with the windows are two parabolic antennas ( 14,1 S). One of the parabola is connected to a transmitter ( I 6) and the other parabola ( I S) is connected to a receiver ( 17}. The transmitter consists of a signal generator which is stepped in frequency over a wide frequency band. The received signal is compared with the transmitted signal in a cross-correlator (l8) connected to a computer (I9). .
The received signal consists of a number of spectral lines emitted from the gas inside the chimney overlaid on the background transmitted signal. The transmitted signal is used to calibrate the frequency response of the system and the attenuation through the chimney walls by looking at the received signal between the molecular lines. This baseline will then be subtracted from the received signal and the intensities of the molecular spectral lines can be determined as calibrated inside the chimney.
The system is further calibrated by measuring the signal transmitted through the chimney as a function of frequency when the chimney is empty .
The registered spectrum is stored in a computer. A database is searched for known lines which coincide in frequency with maxima ' within the observed spectrum. ~~eafter, a Gaussian model fit is made to the line in order to determine the amplitude, frequency, and line width. A
line is considered to be detected if the amplitude of the Gaussian fitted Line is more than three times the calculated noise level. The measured amplitudes are then calibrated to an absolute temperatur a scale.
If a number of lines from the same molecular specie can be detected, then the relative population of the various energy levels maybe determined. This relation is mainly determine:' by the physical temperature of the gas and the density of the molecular specie as:
Nulgu - NrotlQ(Trot) e-E"~rot where Nu is the number of molecules in the upper energy level of the transition, gu is the statistical weight of the transition, E" is the energy of the upper energy level in Kelvin, Q is the rotational constant.. Trot is physical temperature, in the case of burning processes where the excitation is dominated by collisions due to the high temperature, and Nrot is the column density of the molecules of this particular specie.
Nu/gu is directly proportional to the intensity integrated over the spectral line and can therefore be measured. If a number of spectral lines from a molecule are available, then both the density (if the path length is known) and the physical temperature (if the molecule is predominantly collision excited) can be determined simultaneously. If lines from other molecules are also present, then s also the densities of these molecules may be measured from the intensity of a single molecular line.
The radio antenna can also consist of an interferometer where the elements are radio horn antennas mounted in a plane (31,32) and with properly adjusted delay lines as shown in Figure 2~ Then, a two dimensional distribution of molecular densities and temperature of the gas or flame 35 can be constructed by transforming from the aperture (u,v) plane to the image plane.
If the system consists of interferometers (32) which are looking into the process room or exhaust channel from different angles as is shown in Figure 3, then the densities and the Temperature of the gas or flame 35 may also be recovered in three dimensions by a Radon transform, similar to what E
is used tn computer tomagraphy. Such a system can recover the temperature distribution in three dimensions within a hot gas (or a flame). It can also, which will be more important, simultaneously recover the three dimensional density distrihutiorr ojeach detectable molecular specie. These measurement are also performed without any physical probe since the radio signal may, as indeed was the case in our pilot experiment that will be described penetrate .
thror~gh the ceramic wall of the chimney.
In the apparatus shown in Fig 2, an experiment was carried Qut. A.n oxyloil burner was installed and was burning in a steady state.
Fig. 4 shows the spectrum observed in the tadioband 20-40 GHiz through the flew in the chimney. Mast of these lines come from S02, some others from IV'H3 and other molecules. It is therefore clearly possible to detect molecules within the radioband in gas flows on earth. As a consequence it is then also possible to make images of such a flow. Fig. 5 shows the identifications of some of the lines from one observations. Using S02 as a tracer it was possible to determine the temperature as well as the density of S02 as function of time.
Claims (9)
1. A method for measuring temperature, molecular composition or molecular densities or any combination thereof of high-temperature collision-excited molecules, characterized in that it comprises:
measuring an emission spectrum of the molecules in the radio range defined as wavelengths between 500 m and 30 µm with a radio antenna positioned apart from the molecules, transmitting a radio signal through the molecules, detecting a corresponding background transmitted signal on which the emission spectrum is overlaid, measuring spectral lines emitted by the molecules, and determining from the background transmitted signal and measured spectral lines the temperature, molecular composition or molecular densities or any combination thereof.
measuring an emission spectrum of the molecules in the radio range defined as wavelengths between 500 m and 30 µm with a radio antenna positioned apart from the molecules, transmitting a radio signal through the molecules, detecting a corresponding background transmitted signal on which the emission spectrum is overlaid, measuring spectral lines emitted by the molecules, and determining from the background transmitted signal and measured spectral lines the temperature, molecular composition or molecular densities or any combination thereof.
2. A method as claimed in claim 1 characterized in that molecular species are identified from the emission spectrum by comparing the detected spectral lines with molecular lines from an identification data base.
3. A method as claimed in claim 2, characterized in that the temperature of the molecules is measured by measuring the relative intensities of several lines from the same molecular species and comparing with a theoretical relation calculated for the expected population of energy levels as a function of temperature.
4. A method as claimed in claim 3, characterized in that the density of the molecular species are determined by measuring the absolute intensity of an spectral line from that species and comparing it with the theoretically expected intensity for the already determined temperature.
5. A method as claimed in claim 1 or 4, characterized in that the spectrum is measured in narrow frequency channels resulting in a frequency spectrum which is calibrated against a known reference signal.
6. A method as claimed in claim 5, characterized by conducting calibration both against a signal transmitted through the molecules and against a signal transmitted in circumstances wherein molecules are not present.
7. A method as claimed in claim 5 or 6, characterized in that the reference signal and background signal are created in steps of narrow frequency channels by stepping a signal generator in frequency.
8. A method as claimed in any one of claims 1 to 7, characterized in that the receiving antenna is an interferometer and that a two dimensional distribution of densities and temperature is constructed from the cross correlation of received signals with transmitted signals.
9. A method as claimed in claim 8, characterized in that the signal is received simultaneously by interferometers placed at several azimuth angles around the location of the molecules and a three dimensional distribution of densities and temperature is constructed by projections.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE9300347A SE501473C2 (en) | 1993-02-03 | 1993-02-03 | Ways of determining the state of gases and flames in melt and combustion processes |
| SE9300347-3 | 1993-02-03 | ||
| PCT/SE1994/000100 WO1994018550A1 (en) | 1993-02-03 | 1994-02-03 | A method for measuring temperature, molecular composition or molecular densities in gases |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2155339A1 CA2155339A1 (en) | 1994-08-18 |
| CA2155339C true CA2155339C (en) | 2005-12-20 |
Family
ID=35645786
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002155339A Expired - Fee Related CA2155339C (en) | 1993-02-03 | 1994-02-03 | A method for measuring temperature, molecular composition or molecular densities in gases |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2155339C (en) |
-
1994
- 1994-02-03 CA CA002155339A patent/CA2155339C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2155339A1 (en) | 1994-08-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0698205B1 (en) | A method for measuring temperature, molecular composition or molecular densities in gases | |
| US5298751A (en) | Remote active vapor concentration measurement system and method thereof | |
| US5793042A (en) | Infrared spectrophotometer accelerated corrosion-erosion analysis system | |
| CN101287976A (en) | Two line gas spectroscopy calibration | |
| US4780832A (en) | Radiation probe and method of use | |
| EP0243139A2 (en) | Method and apparatus for gas analysis | |
| EP1393033B1 (en) | A cryogenic optical fibre temperature sensor | |
| CA2155339C (en) | A method for measuring temperature, molecular composition or molecular densities in gases | |
| JPH0394143A (en) | Apparatus and method for detection | |
| CN105866468A (en) | Propellant charge exhaust plume flow velocity measurement apparatus | |
| Murzyn et al. | Advancing thermochemical diagnostics in kilogram-scale explosive fireballs via laser absorption spectroscopy | |
| CN113125038A (en) | Rayleigh scattering temperature measurement method based on heating rate zone flame | |
| RU2124706C1 (en) | Method and device determining temperature of internal walls of multiwall vessels | |
| Schlamp et al. | Homodyne detection laser-induced thermal acoustics velocimetry | |
| Burger et al. | Nondestructive evaluation through transient thermographic imaging(TTI) | |
| Chmiel et al. | Thermovision and spectroradiometry in stand-off detection of chemical contamination | |
| Wojcik et al. | Passive optical gas concentration sensor in industrial boilers | |
| Wilson et al. | Comparison of velocity and temperature measurements in an MHD topping cycle environment with flow field model calculations | |
| FARAG et al. | Remote spectral sensing of temperature profiles in flames | |
| GB2275109A (en) | Flame monitoring device and method | |
| FLETCHER | An investigation of nonsimultaneous laser-induced fluorescence | |
| Self | Diagnostic Techniques for Thermal Plasmas | |
| Minsheng et al. | Pseudo-colorimetric method for detection of penetration and seam position in welding process | |
| Hase et al. | ECE fluctuation measurements at the W7-AS stellarator comparison of two techniques-correlation with density fluctuations | |
| Kelly et al. | Infrared thermography of burn front propagation in heat powders |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |