THERMAL SCIENCE

International Scientific Journal

Goran G. Jankes

,

Olga Cvetković

,

Nebojš M. Milovanović

,

Miroljub M. Adžić

,

Mirjana Stamenić

RAPID PYROLYSIS OF SERBIAN SOFT BROWN COALS

ABSTRACT
Soft brown coals of the open coal fields of Kolubara and Kostolac are the main domestic energy sources of Serbia. This paper presents the results of investigations on rapid devolatilization of these two coals which have covered kinetics of devolatilization (based on total volatile yield), forms of sulphur and petrographic analysis of coal and char. Experiments of devolatilization were performed in inert gas (N2) at atmospheric pressure and in batch-type hot-wire screen reactor. The mass-loss values of both coals at selected final reaction temperatures (300-900°C) and retention times (3-28 s) were obtained. Anthony and Howard's kinetic model was applied over two temperature ranges (300-500 and 700-900°C). The types of sulphur as monosulphide, sulphate, pyritic, and organic sulphur were determined for chars and original coals. Strong transformation of pyrite was evident even at low temperatures (300°C). Devolatilization of all types of sulphur has started over 600 and at 900°C the content of sulphur in char remained only 66% of total sulphur in original coal. Microscopic investigations were carried out on samples prepared for reflected light measurements. The petrographic analysis included: the ratio of unchanged and changed coal, maceral types, the share of cenosferes, isotropic mixed carbonized grains, mixed grains, small fragments, clay, and pyrite. The change of the structure of devolatilized coal was also observed.
KEYWORDS
lignite, rapid devolatilization, sulphur, petrographic analysis
PAPER SUBMITTED: 2008-11-29
PAPER REVISED: 2008-12-01
PAPER ACCEPTED: 2009-02-24
DOI REFERENCE: https://doi.org/10.2298/TSCI0901113J
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2009, VOLUME 13, ISSUE Issue 1, PAGES [113 - 126]
REFERENCES
  1. Jankes, G. G., Issue of Yugoslavs Soft Brown Coals Gasification, Ph. D. thesis, Faculty of Mechanical Engineering, University of Belgrade, Belgrade, 1990
  2. Badizoch, S., Nawksley, G. W., Kinetics of Thermal Decomposition of Pulverized Coal Particle, Ind. Eng. Chem. Proc. Des. Develop., 9 (1970), 4, pp. 521-530
  3. Anthony, D. B., Howard, J. B., Coal Devolatilization and Hydrogasification, AIChe I., 22 (1976), 4, pp. 625-656
  4. Howard, J. B., Fundamentals of Coal Pyrolysis and Hydropyrolysis, in: Chemistry of Coal Utilization, Second Supplementary Volume (Ed. M. A. Elliott), John Wiley & Sons, New York, USA, 1981, pp. 665-784
  5. Suuberg, E. M., Peters, W. A., Howard, J. B., A Comparison of Rapid Pyrolysis of a Lignite and Bituminous Coal, in: Thermal Hydrocarbon Chemistry (Eds. A. G. Oblad, H. G. David, R. T. Eddinger), Advanced in Chemistry Series, No. 183, 1979, pp. 239-257
  6. Jüntgen, H. et. al., Coal Characterization in Relation to Coal Combustion, Part I: Structural Aspects and Combustion (in German), Oil and Coal-Natural Gas-Petrochemistry and Chemistry of Fuels 40, (1987), 4, pp. 153-164
  7. Hütinger, K. J., Michenfelder, A. W., Molecular Structure of a Brown Coal, Fuel, 66 (1987), 8, pp. 1164-1165
  8. Gavalas, G. R., Coal Pyrolysis, Coal Science and Technology, No. 4, Elsevier, Amsterdam, The Netherlands, 1982
  9. Simons, G.A., Coal Pyrolysis, I. Pore Evolution Theory, Combustion and Flame, 53 (1983), 1-3, pp. 83-92
  10. Radovanović, M., Fluidized Bed Combustion (Ed. M. Radovanović), Hemisphere Publ. Corp., New York, USA, 1986
  11. Barišić, V., Estimation of Coal Pyrolysis Kinetics by Thermogravimetric and Fluidized Bed Experiments, Proceedings, 2nd Symposium of South-East European Countries on "Fluidized Beds in Energy Production, Chemical and Process Engineering and Ecology", Arandjelovac, Yugoslavia, 1999, pp. 63-76
  12. Oka, S. N., et al., Single Coal Particle Behavior in Fluidized Bed Combustion: Recent Results Acieved in Vin~a Institute of Nuclear Sciences, Proceedings, ASME-ZSITS International Thermal Science Seminar, Bled, Slovenia, 2000, pp. 83-92
  13. Stojiljković, D., et al., Devolatilisation of Some Pulverized Eastern European Lignites, Journal of the Energy Institute, 78 (2005), 4, pp. 190-195
  14. Ercegovac, M., Pulejković, D., Petrographic Composition and Coalification Degree of Coal in the Kolubara Coal Basin, Annales Geol. de la Penins. Balkanique, 55 (1991), 2, pp. 223-239
  15. Niksa, S. J., et. al., Captive Sample Reactor for Kinetic Studies of Coal Pyrolysis and Hydropyrolysis on Short Time Scales, Fuel, 61 (1982), 12, pp. 1207-1212
  16. Mc Gowan, W. C., Markuzewski, R., Direct Determination of Sulphide, Pyritic and Organic Sulphur in a Single Sample of Coal by Selective, Step-Wise Oxidation with Perchloric Acid, Fuel, 67 (1988), 8, pp. 1091-1095
  17. ***, I. C. C. P. (International Committee for Coal and Organic Petrology), International Handbook of Coal Petrography, Supplement to Second Edition, Centre national de la recherché scientifique, Paris, 1971
  18. Milovanović, N., The Characteristic of the Yugoslav Soft Brown Coals Devolatilization Process, M. Sc. thesis, Faculty of Mechanical Engineering, University of Belgrade, Belgrade, 1996
  19. Anthony, D. B., et al., Rapid Devolatilization and Hydrogasification of Bituminous Coal, Fuel, 55 (1976) , 2, pp. 121-128
  20. Lappas, A. A. et. al., Product Distribution and Kinetic Predictions of Greek Lignite Pyrolysis, Fuel,. 69 (1990), 10, pp. 1304-1308
PDF VERSION [DOWNLOAD]
Rapid pyrolysis of Serbian soft brown coals

© 2024 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, 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