THERMAL SCIENCE

International Scientific Journal

Authors of this Paper

External Links

MODELLING OF DYNAMICS OF COMBUSTION OF BIOMASS IN FLUIDIZED BEDS

ABSTRACT
New process concepts in energy production and biofuel, which are much more reactive than coal, call for better controllability of the combustion in circulating fluidized bed boilers. Simplified analysis describing the dynamics of combustion in fluidized bed and circulating fluidized bed boilers is presented. Simple formulas for the estimation of the responses of the burning rate and fuel inventory to changes in fuel feeding are presented. Different changes in the fuel feed, such as an impulse, step change, linear increase and cyclic variation are considered. The dynamics of the burning with a change in the feed rate depends on the fuel reactivity and particle size. The response of a fuel mixture with a wide particle size distribution can be found by summing up the effect of different fuel components and size fractions. Methods to extract reaction parameters form dynamic tests in laboratory scale reactors are discussed. The residence time of fuel particles in the bed and the resulting char inventory in the bed decrease with increasing fuel reactivity and differences between coal and biomass is studied. The char inventory affects the stability of combustion. The effect of char inventory and oscillations in the fuel feed on the oscillation of the flue gas oxygen concentration is studied by model calculation. A trend found by earlier measurements is explained by the model.
KEYWORDS
PAPER SUBMITTED: 2004-03-06
PAPER REVISED: 2004-05-10
PAPER ACCEPTED: 2004-05-27
DOI REFERENCE: https://doi.org/10.2298/TSCI0402107S
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2004, VOLUME 8, ISSUE 2, PAGES [107 - 126]
REFERENCES
  1. Tourunen, A., Saastamoinen, J., H䭤l䩮en, J., Paakkinen, K., Kettunen, A., and Hypp䮥n, T., Dynamic Measurements and Analysis of Fuel Reactivity in a Laboratory Scale Circulating Fluidized Bed Combustor, Circulating Fluidized Bed Technology VII, pp. 669-676, John R. Grace, Jesse (J.-X.) Zhu, and Hugo de Lasa, (Eds.), Ottawa 2002 (Proceedings, 7th International Conference on Circulating Fluidized Beds, Niagara Falls, Ontario, Canada, May 5-8, 2002)
  2. Tourunen, A.S, Saastamoinen, J.J., H䭤l䩮en, J.P., Paakkinen, K.M., Hypp䮥n, T.E., Kettunen, A.M., Study of Operation of a Pilot CFB-reactor in Dynamic Conditions, Proceedings, 17th International Conference on Fluidized Bed Combustion 8-21.5.2003, ASME, Jacksonville, Florida
  3. Saastamoinen, J.J., Tourunen, A. H䭤l䩮en, J., Hypp䮥n, T., Loschkin, M., and Kettunen, A. Analytical Solutions for Steady and Unsteady State Particle Size Distributions in FBC and CFBC Boilers for Non-breaking Char Particles, Combustion and Flame, 132 (2003), No. 3., pp. 395-405
  4. Tourunen, A., Effects of Biomass on Dynamics of Combustion in CFB. In this journal issue.
  5. Lee, Y.Y., and Hyppanen, T., A Coal Combustion Model for Circulating Fluidized Bed Boilers, Proceedings, 1989 International Conference on Fluidized Bed Combustion. San Francisco, 1989, ASME, vol. 2, pp. 753-764
  6. Saastamoinen, J., Aho, M., and Linna, V., Simultaneous Pyrolysis and Char Combustion. Fuel, 72 (1993), No. 5, pp. 599?609
  7. Gurgel Veras, C.A., Saastamoinen, J., Carvalho Jr., J.A., and Aho, M., Overlapping of the Devolatilization and Char Combustion Stages in the Burning of Solid Fuel Particles, Combustion and Flame, 116 (1999), pp. 567-579
  8. Saastamoinen, J.J., H䭤l䩮en, J.P., and Kilpinen, P., Release of Nitrogen Compounds from Wood Particles during Pyrolysis, Environmental Combustion Technologies, 1 (2000), pp. 289-316
  9. Saastamoinen, J., Simplified Model for Calculation of Devolatilization in Fluidized Beds, Proceedings, Finnish-Swedish Flame Days 2002
  10. Raiko, R., Saastamoinen, J., Hupa, M., Kurki-Suonio, I., Textbook on Combustion (in Finnish). Gummerus Oy, Jyv䳫yl䬠2002

© 2019 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence