WO2007037771A1 - Pyrometre haute temperature - Google Patents

Pyrometre haute temperature Download PDF

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Publication number
WO2007037771A1
WO2007037771A1 PCT/US2004/015024 US2004015024W WO2007037771A1 WO 2007037771 A1 WO2007037771 A1 WO 2007037771A1 US 2004015024 W US2004015024 W US 2004015024W WO 2007037771 A1 WO2007037771 A1 WO 2007037771A1
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WIPO (PCT)
Prior art keywords
filter
detector
pyrometer
holder
band pass
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PCT/US2004/015024
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English (en)
Inventor
Ulrich Bonne
Emmanuel Nwadiogbu
Rudolph Dudebout
Roland A. Wood
Barrett E. Cole
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Honeywell International Inc.
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Application filed by Honeywell International Inc. filed Critical Honeywell International Inc.
Priority to PCT/US2004/015024 priority Critical patent/WO2007037771A1/fr
Publication of WO2007037771A1 publication Critical patent/WO2007037771A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/48—Thermography; Techniques using wholly visual means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/60—Radiation pyrometry, e.g. infrared or optical thermometry using determination of colour temperature

Definitions

  • the invention pertains to pyrometers and particularly to optical pyrometers. More particularly, the invention pertains to multi-detector pyrometers for measurement of nonsteady emitters.
  • optical pyrometers are based on either one- or two-channel measurement of the radiance of hot-surfaces or hot-gases, whereby this radiance is measured within the selected spectral band with available detectors, whether visible or infrared (IR) .
  • IR infrared
  • Filter-wheel-based approaches do not achieve accurate temperature measurement because of the short measurement time and the generally sequential nature of the signal generation, which is especially detrimental with unsteady radiation sources such as turbulent flames. In addition, they are generally bulky, costly and wear out.
  • optical pyrometers may be related to turbine engine efficiency and emissions control, which at times will be used below as an illustrative example, without limiting the applicability of the described pyrometer.
  • the need for and the possible benefits resulting from a successful turbine combustor exit gas temperature sensor are noted.
  • one solution may be to measure the exit temperature of each combustor, so that appropriate, active fuel/air ratio control can be implemented.
  • Two-channel pyrometers without a filter wheel but with two (double-decker> detectors may be elegant solutions that use one- beam light inlet from the source, followed by either double- decker silicon (Si) detectors, double-decker Si-PbS or by a beam-splitter to engage two separate detectors that are sensitive to different wavelengths.
  • Their output ratio is a . measure for source temperature and may be suitable to monitor unsteady sources . But their output temperature error might become unreasonably large as the ambient temperature deviates from calibration conditions, without temperature-dependent offset compensation.
  • the double-decker version may be very limited in the choice of the two channel wavelengths to those transmitted by the top detector, and the beam-splitter version may not correct for individual variabilities in the sensitivity drift of the two detectors.
  • Two-channel -one-detector pyrometers with a filter wheel include those where the two wavelengths may be selected freely among commercially available narrow-band pass filters.
  • observation of an unsteady source might require that either the filter wheel be turned faster than the source instability (which may reduce detector observation time and the signal-to-noise ratio (S/N) ) or slow enough to raise the S/N (which may then increase the un-relation between the two channel signals due to unsteadiness of the source and the error in the temperature resulting from their signal ratio) .
  • Two-channel-two-detector pyrometer with chopper consisting of two detectors with fixed filters and on/off choppers, may- eliminate the time- and temperature-dependent drift of the null- offset . However, it may not compensate for the error caused by- individual sensitivity drift in the detector (s) inherent in setups with fixed filter-detector pairings.
  • Available combustion pattern factor (CPF) sensors for each of the fuel atomizers in a gas turbine engine tended to depend on the measurement of first stator blade temperature sensing via pyrometry or deposited film thermocouples (or resistors) or special temperature-dependent phosphorescent films.
  • An illustrative example of the invention may be a pyrometer having one or more detectors and a filter holder next to the detectors.
  • the holder may have several band pass filters of various band-pass wavelengths which may be moved past the detectors.
  • the holder may have several positions which include placing filters or no filters in front of the detectors, by exchanging their positions relative to the detectors. These positions may be sequenced by a motor.
  • the filters and radiation blocking spot may be rotated about an axis approximately parallel to the direction of the radiation being sensed by the detectors .
  • the pyrometer may instead include one detector and a filter that may rotate about an axis approximately perpendicular to the direction of the radiation being sensed by the detector.
  • the filter upon rotation may modulate the wavelength of the radiation between on-band and off-band, as well as between several wavelengths that define color temperature.
  • the pyrometer may instead have detectors with one or more filters in front of them that do not physically move relative to the detector.
  • the filters may be Fabry-Perot filters which have their optical thicknesses changed to achieve various bandwidths of band pass capabilities.
  • a mechanism that affects the filters' thicknesses may be connected to a processor.
  • Figure 1 shows a pyrometer having several fixed detectors and moveable filters
  • Figure 2 shows a pyrometer having several fixed filters and moveable detectors
  • Figure 3 shows a pyrometer having several detectors and filters that are not moveable relative to each other;
  • Figure 4 shows the wavelength relationships of the three channel Fabry-Perot pyrometer
  • Figure 5 shows a pyrometer having a filter that rotates on an axis perpendicular to the direction of radiation impinging the detector
  • Figures 6a and 6b show several locations of a pyrometer situated in a gas combustor of a jet engine
  • Figures 7a and 7b reveal transmittance properties of an illustrative example Fabry-Perot mirror at two different orientations
  • Figure 8 shows a plot of a rotating etalon wafer recovering a transmission after a temperature change
  • Figure 9 shows a plot of an etalon wafer or membrane signal versus temperature
  • Figure 10 shows an illustrative fuel cooling and air purging scheme for a pyrometer
  • Figures 11-13 show various computed emission spectra of CO 2
  • Figure 14 shows a graph of emissivity spectra of CO 2 under various environmental conditions
  • Figures 15a and 15b are plots of radiance of combustion gases at 2000 'K;
  • Figures 16a and 16b are plots of radiance of combustion gases at 2500 "K;
  • Figure 17 is a series of comparative plots of radiance of combustion gases at various temperatures
  • Figure 18 is a table comparing characteristics of thermal radiators ;
  • Figures 19a and 19b are plots of radiance of combustion gases at 1000 'K and 1500° K, respectively;
  • Figure 20 is table of data from an evaluation of radiance plotted in Figure 17;
  • Figure 21 shows several views of an example of an air motor and its relationship with the filter it rotates.
  • Figure 22 reveals several views of an example of an air motor attached to the filter wheel.
  • An illustrative device of the invention is a pyrometer 10 having two detectors 11 and 12 and a filter holder 13 next to detectors 14 and 15 in Figure 1.
  • Holder 13 may support two band pass filters 14 and 15 which are moved past detectors 11 and 12.
  • Holder 13 may have three positions which include two filters 14 and 15 in front of detectors 11 and 12, the position of the filters exchanged relative to the detectors, and no filters in front of the detectors, respectively. These positions may occur sequentially.
  • Band pass filters 14 and 15 generally pass different spectral wavelengths. The three positions may be sequenced by a stepper motor 16.
  • the filters and radiation blocking spot 17 may be rotated about an axis 18 approximately parallel to the direction of the radiation being sensed by the detectors through aperture 42.
  • Figure 2 shows a pyrometer 40 similar to pyrometer 10 except that detectors 11 and 12 move relative to stationary filters 14 and 15 for attaining the same relative positions as those of pyrometer 10.
  • a pyrometer 20 of Figure 3 which may likewise have two detectors 21 and 22. However, each detector 21 and 22 may have a filter 23 and 24 in front of it, respectfully, that does not physically move away from the detector. There may in some cases also be a third filter 25 in front of both detectors. The first two filters 23 and 24 individually in front of their respective detectors 21 and 22 may alternate between several band widths relative to their band pass capabilities.
  • a third filter 25 which alternates between a wide band pass that includes the bandwidths of the two individual filters 23 and 24 and a blocking band pass that blocks the bandwidths of both individual filters 23 and 24, of radiation 54 impinging pyrometer 20.
  • All three filters 23, 24 and 25 may be Fabry-Perot filters which have their optical thicknesses changed to achieve passing variable wavelength bands capabilities.
  • a mechanism 26 (such as a heater) that affects the filter optical band pass characteristics of the filters 23, 24 and 25 may be connected to a processor 27 for effecting changes in the filters' characteristics.
  • the components in Figure 3 are not drawn to scale.
  • Still another illustrative example is a pyrometer 30 of Figure 5, though not exhaustive of possible illustrative examples of the invention, may include one detector 31 and a filter 32 that rotates about an axis approximately perpendicular to path 33 of the radiation being sensed by detector 31 via aperture 42 and masks 45. Filter 32 upon rotation may modulate the wavelength of the radiation between on-band and off-band, as well as between two wavelengths that define color temperature.
  • a mechanism such as an air motor 34 may be connected to filter 32 to rotate it. Motor 34 may alternatively be electric.
  • Detector 31 may be structured so as to detect temperatures in a gas cotnbustor 35 such as that of a jet engine 36 in Figure 6a.
  • Three-channel pyrometer 10 of Figure 1 may be compact, affordable and geared to sense black-body temperatures accurately, despite detector drift acerbated by operation in non-thermostatted ambients up to 200°C, individual drift (offset and sensitivity) of detectors 11 and 12, some soiling of filters 14, 15 versus service life, and unsteady sources.
  • Pyrometer device 10 may eliminate some of the shortcomings of the above- noted approaches. It may be a three-channel approach (two "on" channels and one "off” or null channel) , consisting of two freely chosen and separate narrow band-pass filters 14, 15 with transmissions T A and T ⁇ , for instance, 4250 and 4425 nanometers
  • the color temperature of the object (solid or gas) or source 19 at hand may then be obtained via the ratio between two, nulled sensor signals.
  • Each temperature determination may consist of three signal measurements, as follows: 1) Filter 14 with transmission T A facing detector 11 of sensitivity S 1 and filter 15 with transmission T B facing detector 12 of sensitivity S2, leading to signals Al and B2 ; 2) Filter 14 with transmission T A -facing detector 12 with sensitivity S 2 , and filter 15 with transmission T B facing detector 11 of sensitivity S 1 , leading to signals A 2 and Bx; and 3) Null, i.e., when two detectors 11 and 12 just face a relatively cool and opaque filter wheel plate, offset or null signals N 1 and N 2 may be sensed. For the sake of brevity- one may henceforth think 'of the signals A 1 , A 2 , B 1 and B 2 as nulled signals, i.e., signals from which the appropriate N 1 or N 2 values have been subtracted.
  • the incoming radiation intensities from the source 19, I A and Ig may be proportional to the generated signals, A 1 and B 2 , and A 2 and B 1 (for filter positions 1 and 2) , respectively, but may be corrected for variables T A , T B , S 1 and S 2 .
  • For the first two filter positions (and ignoring N 1 and N 2 for now) one may have
  • the angular beam aperture may be somewhat limited by the FWHM (full-width at half maximum, ⁇ ) of the selected band pass filters, because the transmitted wavelength shifts with the angle of incidence.
  • the filters may move between rotational positions of 0, 90, 180, 90 and 0°, corresponding to above positions 1) , 3) , 2) , 3) and 1) , for instance, of filters 14, 17, 15, 17 and 14 positioned in front of detector 11, respectively.
  • detectors 11 and 12 may move between rotational positions of 0, 90, 180, 90 and 0°; for instance, detector 11 may move behind filters 14, 17, 15, 17 and 14, respectfully. Filter holder 41 would not move.
  • ⁇ / ⁇ ⁇ 50/4325, and ⁇ may need to be limited by the
  • Figure 4 shows a graph of radiance, wavelength and transmission of three-channel pyrometer 20 based on Fabry-Perot
  • Solid line “ shows the thermal emission of combustion gases.
  • Dashed line w - - - - » shows the
  • band pass filters ⁇ ( ⁇ ⁇ 25 nm> , may be provided by two Fabry- Perot (FP) comb filters 23 and 24 of about 400 nm tine spacing.
  • the filter transmissions may be controlled in such a way that one filter 23 effectively shifts from its position to transmit
  • FP etalon space One may use an electro- optical material whose index could be modulated by 2.9 percent. Any other actuation 26 based on electrostatic, thermal, magnetic, pneumatic, rotation or piezoelectric to bring about such ⁇ d displacement may be acceptable. A rotation of the FP
  • wavelength may also increase the wavelength by 2.9 percent from ⁇ to ⁇ '' ⁇ .
  • Aperture constraints might need to satisfy Fabry-Perot criteria to maintain the set finesse, the constraints becoming tighter as the ⁇ increases .
  • the maximum allowable uncertainty, E, in each of the radiation sensor measurements, A may depend on the desired maximum acceptable temperature uncertainty, ⁇ T.
  • the most challenging case may be at the highest temperature, T max .
  • each of the Fabry-Perot comb filters 23, 24 in front of detectors 21, 22 may be designed such that 1) their "tine" spacing exceeds the width the one blocking filter and 2) their spectral modulation enables their narrow transmission band of ⁇ 25 nm (see Figure 4) to switch (or scan) between the transmissions at 4250 and 4425 ran.
  • This switch may be accomplished in one of several ways, that is, by changing the optical thickness between the two etalon mirror surfaces mechanically (axial translation or rotation) , piezoelectrically or thermally.
  • one pyrometer location 37 may be as shown in Figure 6a, which benefits from a long path 39 >10 cm, detector 30 cooling from air 43 outside the compressor shell, purge compressed air (for purge and facilitating observation of exit gas) , and access to actuator cable for the detectors.
  • Another location 38 for the detector 30 may be as shown in Figure 6a.
  • Still another location 46 for detector system 30 may be as shown in Figure 6b
  • Illustrative pyrometer 20 of Figure 3 has several features. It may be a high-accuracy color temperature pyrometer, using a three-channel approach with two detectors 21, 22, with auto- compensation for changes in the sensitivity of the two detectors. It may have offset compensation via the third channel, measurement and compensation for non-zero thermal radiation of third channel and a relationship between the two- detector signal ratio and color temperature, indicated by using the geometric mean of two consecutive temperature signals (signal ratios, see eq. 1 above), and a mechanism to interchange two active (T ⁇ an( 3 ⁇ ⁇ ) an ⁇ ⁇ two passive ("null") filters 23, 24 in front of the two detectors 21, 22, respectively. This interchange may be accomplished via thermal actuation of a silicon etalon, from among mechanical and piezoelectric alternatives .
  • the auto-compensation may enable the pyrometer to operate in harsh, uncontrolled temperature environments, and have a long service life of moving parts by executing auto-compensation only when needed, e.g., after exceeding a set change in ambient temperature .
  • the high signal-to-noise, S/N may be achieved by long observation times provided by slow or intermittently moving, automated filter-detector exchange, rather than limiting sense time to the short time-periods provided by a conventional filter-wheel .
  • the ability to measure average temperature of non-steady- state source may be enabled by simultaneous observation of the source via two channels with several implementation approaches (rather than sequential observation of the source as provided by- filter wheel elements passing across one detector) .
  • the pyrometer may use "uncooled" thermo-electric infrared (IR) arrays as detectors, whereby each may consist of an array of 5 x 5 elements or 20 x 20 elements with an active area of about 1.5 x 1.5 mm .
  • IR thermo-electric infrared
  • the advantages may include the ability to operate in a changing temperature environment (i.e., to compensate for changing sensitivity of each individual detector) with automatic rather than manual compensation of changes in view of unpredictable detector sensitivity
  • the present pyrometers may operate in high ambient temperatures (up to about 200 0 C) by using uncooled thermoelectric IR detectors, rather than Si, PbS, PbSe or GaAs devices which are limited to about 80 0 C. They may tolerate some soiling of the narrow band-pass filters (which affects their transmission loss by an equal factor) , after initial calibration with a W-ribbon lamp, because only their ratio appears in equ. 1 above.
  • the preceding noted features may reduce temperature output uncertainty.
  • the present pyrometers may permit one to observe and determine the average of non-steady source temperatures, by virtue of simultaneous measurement and averaging with two detectors, which may not be possible with one-detector pyrometers .
  • a high S/N of the pyrometer may be achieved by optimizing the observation time, rather than being limited by the short time periods associated with traditional or not so traditional filter wheels.
  • Spectral frequency modulation for the pyrometer channel detector exposure to two wavelengths "on" and one "off” positions may be provided by slow-moving stepper motor 16 ( Figures 1, 2) , or micro electromechanical system (MEMS) FP filter etalon (membrane) movement, piezoelectric twist movement or thermal excitation, each one having low-wear characteristics ( Figure 3) .
  • MEMS micro electromechanical system
  • a thermally tuned etalon may be used for band width switching of filters of light to detectors 21 and 22.
  • Two filters 23, 24 may be utilized, one for each detector 21, 22, respectively.
  • the etalon may be fabricated by a deep reactive ion etching (DRIE) of a 30 ⁇ m polysilicon membrane which is a part of a silicon-on-insulator (SOI) wafer. Measurements were taken after coating both sides with a quarter/quarter wave pair of Si/SiO2 films. These measurements showed thermal tuning. To get higher finesse, the wafers were coated with an additional pair of coatings on both sides. They were re-measured using a 1.5 ⁇ m telecom-like laser and a photodiode detector. This demonstrated thermal tuning over the full free spectral range of a silicon etalon by changing the temperature of the wafer including the silicon membrane and observing the central transmission band change by a full fringe.
  • DRIE deep reactive ion etching
  • Figure 3 shows a device 20 and its setup.
  • Figures 7a and 7b reveal calculated etalon properties for Si/Si3N 4 /Si/Si3N 4
  • Figure 9 reveals later data with a higher finesse etalon showing tuning and performance over the full free spectral range for one laser wavelength at 1.5 ⁇ m achieved with a 120°C temperature change. The minimum appears better defined. The added mirror pairs were used and the quarter waves were done in separate runs. This demonstrated the fundamental characteristics of thermal tuning of a Fabry Perot cavity in silicon for potential DWDM applications.
  • An approach to sensing the gas temperature upstream of the stator blades over an adjustable gas space with one passive IR detector 30 for each atomizer may focus on the source of the overheating on each identified atomizer within a response time that is shorter than that of the blade temperature response, with minimal intrusion and high potential durability.
  • a key feature may reside in the location and cooling for IR detector 30.
  • the non-uniformity of the combustor exit gas temperatures may force that temperature to be set to no more than about 2300 0 F (1533°K, i.e., a drop of over eight percent) and in order to prevent unpredictable "hot streaks" to stay below 3300 0 F (2088 0 K) .
  • This forced drop in average temperature and the unpredictable occurrence of hot streaks may result in both turbine efficiency losses as well as excess NO x emissions, respectively. Due to unpredictable fuel
  • one solution may be to measure the exit temperature of each combustor, so that appropriate, active fuel/air ratio control can be implemented.
  • Detector 30 may be sized to be within a cylinder of ⁇ 3"-long x 1"-O.D., have no drift by virtue of the present wavelength modulation approach, feature higher S/N ratios because of the cooling with the fuel supply, generate output signal updates in milliseconds and cost much less than a spectrometer .
  • the challenges with the optical approach based on sensing the flame emission (optical output) at two or more spectral wavelengths may be several-fold. First is to identify suitable wavelength bands. Second is to cool detector 30 to achieve useful S/N (signal-to-noise) ratios.
  • Third is to insure that the optical input represents the temperature of the gas rather then that of the hot background wall or refractory.
  • Fourth is to set the spatial path for the source of emission into one wavelength band such that it is close to the spatial path for the second wavelength band needed to determine color temperature .
  • Figure 10 is a drawing that illustrates how cooling mechanism 47 may utilize the relatively cool liquid fuel 48 to cool detector 31 and oits optical filter 32 of pyrometer 30 from the high flame temperatures in combustor 35 of a jet engine 36 in Figure 6a, or like device. Cooling 47 scheme of Figures 7 and 10 tend to be different relative to that of Figure 5 in terms of purge air 43 and cooling fuel 48.
  • Figure 6b depicts the other location 46 of the detector 31 of system 30, and because the shorter optical path, it may require cooling of an area 49 with air of the combustor wall facing detector 31. Cooling of detector 31 with liquid fuel may require extra looping of the fuel line. However, the gas temperature measurement at this location may better represent the gas temperature impacting the first set of stator blades and the light received by detector 31 may not need to cross (and potentially be absorbed by) the area of concentrated fuel vapor and droplets from the injector nozzle. Cooling scheme 47 of Figure 10 is designed to reduce the risk of coking the fuel 48 line .
  • Figures 11-13 illustrate various computed emission spectra of CO 2 / with and without H2O, showing the emissivity changes
  • Figure 14 shows emissivity spectra of CO2 in a cell of 1 cm in length at 20 bar for 1500°, 2000° and 2500 0 K. It reveals that that 1 cm of optical path may not be enough to guarantee black body radiation from CO2, and that an approximate
  • the path may need a path, L > 4 cm.
  • the path may need to
  • a path of L > 2 cm should be sufficient.
  • the nomenclature utilized here may include: D is light beam diameter in cm or mm; f is frequency in Hz; n is index of refraction (dimensionless) ; k is absorption coefficient in 1/ (cm
  • L optical path length in cm
  • N RMS noise level
  • ⁇ RMS signal
  • p total pressure in bar
  • p o reference
  • T absolute temperature in 0 K
  • ⁇ v line spacing
  • emissivity is in
  • ⁇ is off axis or collimation angle of
  • Figure 15a shows the actual radiance over the 1-5 ⁇ m spectral range for optical paths of 10 cm and 1000 km of combustion gas composed of 10% CO 2 , 10% H 2 O and 80% N 2 at 20 bar
  • the 1000 km path may be long enough to closely follow the expected profile of a black- body radiator, except possibly at the atmospheric windows at 1.05, 1.24, 2.28 and 3.63 ⁇ m.
  • the "black radiators" are the 4.3
  • the H 2 O line at 3.748 ⁇ m has a half-width of 6.15 nm (about
  • Figures 16a and 16b show the spectral variance of having 5 mol% methane versus 5 mol% water vapor as the radiance contributor to 5 mol% in nitrogen, in the 10 cm optical path. Both spectra may correspond to turbine combustion environments at 20 bar and 2500 0 K.
  • the spectral absorption window at 3.628 ⁇ m may be masked by CH 4 (or any related -CH-) absorption,
  • Figure 17 shows plots of spectral radiance at 4 temperatures, indicating that for L > 10 cm, p > 20 bar, T ⁇
  • 4426 nm may be equivalent to that of a black-body radiator, and thus be used to determine gas temperature directly, either via single, absolute measurements (very difficult) or via measurements at two different wavelengths to determine color temperature via formation of radiance ratios (possibly a better approach) .
  • Figure 5 presents an illustrative example of a gas temperature sensor 30, in which the narrow opening 42 to the combustion chamber at left may be tilted so that purging air 43 does not interfere with the radiance measurement; fluid (e.g., fuel 48) flowing around the outer, insulated sheath, may be used for cooling; and lenses may be absent so that alignment may be facilitated and not affected by vibration.
  • fluid e.g., fuel 48
  • lenses may be absent so that alignment may be facilitated and not affected by vibration.
  • filter 32 centered at 4012 nm may be tilted up to 42° to provide wavelength modulation to 4426 nm.
  • An alternate and preferred actuation of blocking filter 32 tilt may be by an air turbine or motor 34 (not shown in Figure 5) , whereby filter 32 may be rotated at rates of 10k to 80k RPM and the IR detector 31 signal amplification may be synchronized with rotation.
  • Tg i.e., temperature of a black body radiating with the same intensity at the wavelength of observation
  • T ⁇ color temperature of a black body appearing to have the same color, i.e., ratio of intensities at two chosen wavelengths, ⁇ and %2 : if tne emissivity is wavelength-
  • T A cannot be less than Tg, but T ⁇ can be larger or smaller than the
  • thermal equilibrium In the subject at hand to determine the temperature of thermally radiating combustion gases, one may need to consider two more variables, that is, thermal equilibrium and gas concentration. First, one may consider thermal equilibrium.
  • gas concentration There being no emitting "surface” in gases, their thermal emissivity, ⁇ , may be determined by the optical path length, L, the molecular concentration, x, of the species contributing to the radiation, and its partial (and total gas) pressure, besides absolute temperature. The computation of such gas emissivities based on all probable molecular transitions tends to be laborious.
  • the gas temperature may rise to its maximum value after combustion is largely complete and most CO2 and H2O have been generated. One therefore may expect low
  • the temperature measurement range may be from 1255 to 1854°K (1800 to
  • angular selectivity may be ⁇ 5° (to inhibit cross sensitivity to adjacent burner flames) .
  • response time may be about 0.5 second.
  • installation/ambient temperature may be about 149°C (300 0 F) .
  • Sixth, demonstrating structural integrity may require that the device needs to pass a vibration test
  • sensor cooling air used for all of the sensors may be ⁇ 0.2 percent of total mass air flow at cruise, or 0.02 lbs/s
  • Uncooled IR sensors for this application in the form of TE (thermo-electric) sensor arrays, may be operated at over 150 0 C.
  • Such sensors have been fabricated at Honeywell International Inc. in Minneapolis, MN.
  • a dedicated, 10-wafer run (10 mm O.D. wafers) might yield over 2000 chips of -5x5 mm, each with an array of 31 x 31, i.e., about 1000, TE junctions. If the signal is high enough in this application, fewer elements may be needed, resulting in lower cost of each sensor.
  • an array of 64 sensor elements of 0.005" x 0.005" in size might fit into a 1 x 1 mm "sweet- spot" detector area.
  • the detector aperture or viewing angle to the flame may need to be limited to ⁇ 1°, at least in the scanning plane,
  • the aperture e.g., D ⁇ 2 mm I.D. for a detector-aperture distance of 60 mm, as depicted in Figure 5. If the detector needs more light to increase S/N, one may open the aperture in the plane of the filter dither axis up to ⁇ 10° or
  • the R-ratio change from 4254 to 4426 nm appears small, but this may be viewed in relation to the signal noise.
  • noise equivalent of 10 0 K one may need an uncertainty in the R-ratio
  • the low radiance (i.e., low absorption and high transmission) at 4012 nm may enable one to periodically check the temperature of the opposite, internal combustor wall; and when the detector faces the opaque edge the output may be viewed as a "zero" signal.
  • the radiance at 4012 nm is only about 170 ppm of the radiance at the other two wavelengths.
  • the evaluation of the signal may be coupled to the timing of the filter wheel 32 rotational angle.
  • the angle-wavelength relation may be, in turn, dependent of the effective refractive index of the films used to fabricate the narrow-band-pass filter.
  • Such a rise in fuel temperature may exceed its coking temperature limit and be not acceptable.
  • the pressures may be about 4% higher than combustor pressures and range from 3 bar (45 psia at idle) to 8.6 bar (125 psia at cruise) to 21 bar (304 psia at full power) .
  • Cool ambient air ( ⁇ 1 bar and ⁇ 82°C ( ⁇ 18O 0 F) ) from the outside of the combustor plenum, may be used to cool the optical system (detector 31, filter 32, motor 34 and masks 45) indirectly, but without mass transfer to the much higher- pressure combustor gases.
  • the filter 32 may need to be driven via electric motor 34.
  • One may use ⁇ 135 0 C ( ⁇ 275°F) fuel to cool a static detector chamber, without any air cooling, with electrical drive for the motor 34 to rotate filter 32 and use only regular compressed air at about 1000 0 F to keep lens 51 clean, as depicted in Figure 10.
  • detector (s) 31 One might move the location of detector (s) 31 away from hot combustor plenum 35, to a space in the "bypass air" channel, to view the hot combustion gases via optical fibers, which at worst may be 30 to 100 cm in length.
  • Individually-mounted sensors 30 may be used with maximum optical fiber lengths of about 30 cm.
  • a cluster-mount approach may be used whereby all optical fibers are brought to a common location.
  • a common filter wheel 53 may ⁇ be used for frequency modulation and isolation (i.e., chopping) of individual beams and one detector 30.
  • the length of all optical (sapphire) fibers may be about 100 cm.
  • a cluster- mount approach may be used whereby each sensor operates independently, with its own approximately 100 cm or so of fiber, electric filter 32 rotator and detector 31.
  • An optical fiber, window or lens at the combustor wall may save the plumbing of purge air through the optical system and enable its operation at ambient pressure; but it may become inaccurate if any soot or tar deposit on the optical surface facing the combustor generates significantly interfering black-body radiation.
  • Air cooling by looping compressed air tubing through bypass air space may enable positioning of sensor at combustor wall, cooling detector, filter 32 and masks 45; driving air motor 34; and purging optical aperture; but may add 0.25" O.D. tubing mass and colder air to combustor.
  • An electric motor 34 used to rotate optical filter 32 may save plumbing and uncertainties of designing a small air motor 34, but add electrical wires and moderate risk with the design of a small electric motor 34. Moving the location of the sensor to the bypass-air space may simplify the cooling problem, but may reduce performance to the extent that the added optical fiber length degrades the combustor gas emission signal. The cost of the longer optical fiber may be offset by the greater ease of installation. Incorporation of the temperature sensor into the fuel nozzle may reduce installation complexities, but might make nozzle design more complex and costly, and eliminate the flexibility to individually optimize the location/position of both nozzle and sensor There may be also detector options.
  • a less sensitive and possibly slower, but more temperature-tolerant IR detector such as a bolometer-type or "uncooled” IR detector, which is less sensitive to ambient temperature than PbSe or PbS, may be operated above 150 0 C (302 0 F) , but is less sensitive and has relatively slow response time (0.05 to 10 ms) .
  • the detector sensitivity may be about 5.6-10" 4 ⁇ W/Vl ⁇ z for a 1 mm 2 detector
  • An air motor 34 may be used for a filter 32 drive as shown in Figure 21.
  • components of an air-motor 34 on air-foil bearings may be used to achieve over 60,000 RPM (1000 Hz) .
  • An acceptable design in Figure 21 may be composed of the following elements and perform as noted in the following.
  • Figures 21 and 22 show details of the filter mount and air- drive rotors 49, respectively. The above results were obtained with rotors 49 generating enough power to overcome viscous drag power of the air bearing and the rotating mirror 32 (assumed to be like the bearing) .
  • Features may include the use of high-speed wavelength modulation of black-body CO2 radiance to an IR detector to determine its gas temperature, whereby the modulation may enable determination of CO2 radiance ratio determination within the IR
  • enclosure may be cooled to ⁇ 275 0 F via external circulation of "cool" fluid, whereby the cool fluid may be liquid fuel or cool air of low or high pressure.
  • the modulation may be accomplished by an air turbine, driven by an air stream which also may be cooled by the fuel.
  • Optics 51 may be kept clean via a purge-air stream, which may exit into the combustion chamber via an upward port or slit.
  • the slit may be dimensioned to not allow aperture angles greater than about 1° to maintain the collimation of the light beam to the modulation filter.
  • the temperature may be determined via a simple relation between it and said ratio of nulled outputs.
  • the advantages of this approach discussed above are that it may be much more compact, accurate, rapid, rugged and affordable.
  • the device may be sized to be within a cylinder of ⁇ 3"-long x 1"-O.D., not drift by virtue of the wavelength modulation approach, feature higher S/N ratios because of the cooling with the fuel supply, generate output signal updates in milliseconds and cost much less than a spectrometer.
  • One may- use much higher modulation speeds (100-1000 Hz) than conventional IR systems (1-10 Hz) , thus decreasing the l/f noise and increasing S/N.

Abstract

La présente invention a trait à un pyromètre comportant au moins deux capteurs et au moins deux filtres passe-bande à proximité de chacun en vue de limiter la bande de longueurs d'onde détectable émise par un objet, et un dispositif pour échanger les filtres en vue d'éliminer des erreurs de rapport de sortie des capteurs. Le rapport de sortie de capteurs est ensuite utilisé pour déduire la température de couleur de l'objet, qui peut présenter des modifications rapides d'intensité d'émission en sortie.
PCT/US2004/015024 2004-05-13 2004-05-13 Pyrometre haute temperature WO2007037771A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1307417C (zh) * 2001-07-12 2007-03-28 乌斯特技术股份公司 用于在纺织材料中识别杂质的方法和装置
TWI548865B (zh) * 2013-11-27 2016-09-11 宇進電測騎士公司 溫度連續測量裝置及包含該裝置的ｒｈ設備

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4410266A (en) * 1980-08-25 1983-10-18 Bsc Industries Corp. Method and apparatus for combustion control and improved optical pyrometer related thereto
US4470710A (en) * 1980-12-11 1984-09-11 Commonwealth Of Australia I. R. Radiation pyrometer
US4817020A (en) * 1987-06-22 1989-03-28 General Electric Company Cooling rate determination apparatus for laser material processing
EP0729023A1 (fr) * 1995-02-27 1996-08-28 Siemens-Elema AB Analyseur optique
US6422745B1 (en) * 1999-01-15 2002-07-23 Ametek, Inc. System and method for determining combustion temperature using infrared emissions

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4410266A (en) * 1980-08-25 1983-10-18 Bsc Industries Corp. Method and apparatus for combustion control and improved optical pyrometer related thereto
US4470710A (en) * 1980-12-11 1984-09-11 Commonwealth Of Australia I. R. Radiation pyrometer
US4817020A (en) * 1987-06-22 1989-03-28 General Electric Company Cooling rate determination apparatus for laser material processing
EP0729023A1 (fr) * 1995-02-27 1996-08-28 Siemens-Elema AB Analyseur optique
US6422745B1 (en) * 1999-01-15 2002-07-23 Ametek, Inc. System and method for determining combustion temperature using infrared emissions

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1307417C (zh) * 2001-07-12 2007-03-28 乌斯特技术股份公司 用于在纺织材料中识别杂质的方法和装置
TWI548865B (zh) * 2013-11-27 2016-09-11 宇進電測騎士公司 溫度連續測量裝置及包含該裝置的ｒｈ設備
US9689048B2 (en) 2013-11-27 2017-06-27 Woojin Electro-Nite Inc. Continuous temperature measuring device and RH apparatus including the same

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