THERMAL SCIENCE

International Scientific Journal

IN-SITU LASER SPECTROSCOPY OF CO, CH4, AND H2O IN A PARTICLE LADEN LABORATORY-SCALE FLUIDIZED BED COMBUSTOR

ABSTRACT
The pyrolysis, devolatilization and char combustion of bituminous coal and biomass (beechwood, firwood) were investigated in a laboratory-scale fluidized bed combustor by tunable diode laser spectroscopy. Individual fuel particles were suspended in the free board of the unit. The bed temperature was 800 deg C, the oxygen partial pressure 0 to 20 kPa (0-10 vol.%). Two Fabry Perot type tunable near infrared diode lasers were deployed for quantitative in-situ species concentration measurements. CH4 and CO were measured simultaneously during devolatilization and char combustion in-situ 10 mm above the surface of the fuel particles as well as H2O using laser spectroscopy. Sand particles were passing the probing laser beam path. Be sides the resonant absorption of the laser light by CO, CH4 and H2O, severe and strongly transient non-resonant attenuation by partial blocking of the beam and beam steering effects occurred. By wave length tuning the two laser sources, species concentrations could be determined. The measured absorbances had to be corrected for the real temperature measured at the position of the probing laser beam. In addition, CO, CO2 and O2 were de termined ex-situ by conventional methods. A spatial profile in side the FBC of major species (CH4, CO, CO2, O, H, OH) was calculated using a chemical kinetics program for a single fuel particle in a plug flow reactor geometry. The results were compared to the experimental findings. Good agreement was found. Tunable diode laser spectros copy was found to be an aptmethod of determining quantitative species concentrations of multiple gases in a high temperature multiphase environment.
KEYWORDS
PAPER SUBMITTED: 2002-09-15
PAPER REVISED: 2002-11-11
PAPER ACCEPTED: 2002-11-15
DOI REFERENCE: https://doi.org/10.2298/TSCI0202013L
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2002, VOLUME 6, ISSUE 2, PAGES [13 - 27]
REFERENCES
  1. J. Huang, A. P. Watkinson, Coal gasification in a stirred bed reactor, Fuel and Energy Abstracts, Volume 38, Issue 3, 1997, 152.
  2. H. Chen, Experimental research on combustion characteristics of pulverized-coal fluidized bed, Fuel and Energy Abstracts, Volume 38, Issue 6, 1997, 422.
  3. J. P. Jacobs, The future of fluidized-bed combustion, Chemical Engineering Science 54 (1999) 5559-5563.
  4. E.R. Furlong, R.M. Mihalcea, M.E. Webber, D.S. Baer and R.K. Hanson, Diode Laser Sensor System for Closed-Loop Control of a 50-kW Incinerator, paper AIAA-97-2833 at 33rd Joint Propulsion Conference, July 7-9, 1997, Seattle, WA.
  5. M. Lackner, G. Totschnig, F. Winter, M. A. Maiorov, D. Z. Garbuzov, and J. C. Connolly; In situ laser measurements of CO and CH4 close to the surface of a burning single fuel particle; Meas. Sci. Technol. 13, 1545-1551, 2002.
  6. G. Totschnig, PhD thesis, Vienna University of Technology, Vienna, Austria, 2002.
  7. D. Garbuzov, R. Menna, M. Maiorov, H. Lee, V. Khalfin, L. DiMarco, D. Capewell, R. Martinelli, G. Gelenky, J. Connolly; 2.3 - 2.7 µm Room Temperature CW-Operation of InGaAsSb/AlGaAsSb Broad-Contact and Single-Mode Ridge-Waveguide SCH-QW Diode Lasers, Proceedings of SPIE, vol. 3628, pp. 124-129 (1999).
  8. D. V. Donetsky, D. Westerfeld, G. L. Belenky, R. U. Martinelli, D. Z. Garbuzov, J. C. Connolly; Extraordinarily wide optical gain spectrum in 2.2-2.5 µm In(Al)GaAsSb/GaSb quantum-well ridge-waveguide lasers, Journal of Applied Physics, Volume 90, Number 8, 2001.
  9. J. Wang, M. Maiorov, J. B. Jeffries, D. Z. Garbuzov, J. C. Connolly, R. K. Hanson, Remote Sensing of CO in Vehicle Exhausts using 2.3 µm Diode Lasers, Measurement Science and Technology 11, 1576-1584, 2000
  10. F. S. Pavone, M. Inguscio, 1993 Appl. Phys. B 56 118-22
  11. Winter, F.; Prah, M.E.; Hofbauer, H. (1997): Intra-Particle Temperatures under Fluidized Bed Combustor Conditions: The Effect of Drying, Devolatilization and Char Combustion, Combust. Flame, Vol. 108, pp. 302-314.
  12. Löffler, G., Wartha, C., Winter, F., Hofbauer, H. (2001): NOx and N2O Formation Mechanisms - A Detailed Chemical kinetic Modeling Study on a Single Fuel Particle in a Laboratory-Scale Fluidized Bed, J. Energy Res. Techn., Vol. 123, No. 3, pp. 228-235.
  13. van den Bleek, C.M.; Brem, G.; Grubor, B.; Johnsson, J.E.; Jones, R.F.; Langer, V.; Verweyen, N., 1990, Documentation of the IEA-AFBC model, Version 1.1, G. Brem, (Ed.), TNO Apelddorn, The Netherlands.
  14. M. Lackner, G. Loeffler, G. Totschnig, F. Winter, H. Hofbauer, Carbon conversion of solid fuels in the freeboard of a laboratory-scale fluidized bed combustor (FBC) - Application of in-situ laser spectroscopy, for submission in Fuel (2002).

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