International Scientific Journal

Thermal Science - Online First

online first only

Online monitoring of the burning characteristics of single pulverized coal particle in O2/N2 and O2/CO2 environments

The objective of this study is to compare the ignition and burning characteristics such as burnout times of volatiles and char, and ignition mechanism of single pulverized coal particle burning in air (O2/N2) and oxy (O2/CO2) environments. An entrained flow reactor with photo detector has been employed for this study. This technique involves online monitoring of radiation emission from an individual coal particle. Individual particles of sub-bituminous or lignite coal particle with size in the ranges of 106 - 125 micron and 180 - 212 micron particles have been injected into an air (O2/N2) or oxy (O2/CO2) environment inside an entrained flow reactor. The oxygen concentration in the ambient gas is varied between 10% to 50% by volume. The volatile and char burnout times have been obtained from time histories estimated from the radiation emitted by the particle. The results show an obvious increase in the burning rates of volatiles and char with increasing oxygen concentration. Further, when compared to N2 atmosphere, the burning rate and radiation intensity are found to be lower in CO2 atmosphere, especially at lower oxygen concentrations. An indication of the possible ignition mechanism has been outlined from the percentages of single and double peaks observed in the radiation emission histories. The complete experimental investigation shows that the burning rates of both volatiles and char are predominantly affected by the oxygen concentration, particle size and gas temperature. The theoretical results from a single particle model has been used to validate the trends and the combustion durations obtained from the present experimental study and is published as a separate manuscript.
PAPER REVISED: 2023-10-02
PAPER ACCEPTED: 2023-10-17
  1. Jovanović, R. D., et al., Experimental and Numerical Investigation of Flame Characteristics During Swirl Burner Operation Under Conventional and Oxy-Fuel Conditions, Thermal Science, 21 (2017), 3, pp. 1463-1477
  2. Belosevic, S. V., et. al., Modeling of pulverized coal combustion for in-furnace NOx reduction and flame control, Thermal Science, 21 (2017), 3, pp. S597-S615
  3. Baghsheikhi, M., et al., The Effect of Fuel Pyrolysis On the Coal Particle Combustion - An Analytical Investigation, Thermal Science, 20 (2016), 1, pp.279-289
  4. Chen, X., et al., Thermal Analyses Of The Lignite Combustion in Oxygen Enriched Atmosphere, Thermal Science, 19 (2015), 3, pp. 801- 811
  5. Buhre B. J. P., et al., Oxy-fuel Combustion technology for coal-fired power generation, Progress in Energy and Combustion Science, 31 (2005), pp.283-307
  6. Maja B. T., Oxy-fuel combustion of solid fuels, Progress in Energy and Combustion Science, 36 (2010), pp.581-625
  7. Wall T. al., Combustion Processes for carbon capture, Proceedings of the combustion Institute, 31 (2010), 1, pp. 31- 47
  8. Wall T.F,, An overview on oxyfuel coal combustion—state of the art research and technology development, Chemical Engineering Research and Design, 87 (2009), 8, pp.1003-1016
  9. Christian H.,, Advanced modelling approaches for CFD simulations of coal combustion and gasification, Progress in Energy and Combustion Science, Progress in Energy and Combustion Science, 86 (2021), pp.100938.
  10. Anderson K. and Johnsson F., Process evaluation of an 865 MWe lignite fired O2/CO2 power plant, Energy conversion and management, 47 (2006), pp.3487-3498
  11. Khare S. P.,, Factors Influencing the Ignition of Flames from Air-fired Swirl Pf Burners Retrofitted to Oxy-fuel, Fuel, 87 (2007), pp. 1042-1049
  12. Suda T., Effect of Carbon dioxide on flame propagation of pulverised coal clouds in CO2/ O2 combustion, Fuel, 86 (2007), pp.2008-2015
  13. Murphy J. J. and Shaddix C. R., Combustion kinetics of coal chars in oxygen-enriched environments, Combustion and Flame, 144 (2006), pp.710-729
  14. Rathnam R. K., Differences in reactivity of pulverised coal in air (O2/N2) and oxy-fuel (O2/CO2) conditions, Fuel Processing Technology, 90 (2009), 6, pp.797-802
  15. Borrego A. and Alvarez D., Comparison of Chars Obtained under Oxy-Fuel and Conventional Pulverized Coal Combustion Atmospheres, Energy & Fuels, 21 (2007), pp. 3171-3179
  16. Varhegyi G., Mathematical Modeling of Char Reactivity in Ar-O2 and CO2-O2 Mixtures, Energy & Fuels, 10 (1996), pp.1208-1214
  17. Bejarano P. A. and Levendis Y. A., Single-coal-particle combustion in O2/N2 and O2/CO2 environments Combustion and Flame, 153 (2008), pp. 270-287.
  18. Molina A. and Shaddix C. R., Ignition and Devolatilization of Pulverised bituminous Coal Particles during Oxygen / Carbon dioxide Coal Combustion, Proceedings of the Combustion institute, 31 (2007), pp. 1095
  19. Kiga T., Characteristics of pulverised-coal combustion in the system of oxygen/recycled flue gas combustion, Energy Conversion and Management, 38 (1997), pp.S129 - S134
  20. Liu H., Zailani R. and Gibbs B. M., Comparisons of pulverized coal combustion in air and in mixtures of O2/CO2,Fuel, 84 (2005),pp. 833-840
  21. Shaddix C. R. and Molina A., Particle imaging of ignition and devolatilization of pulverized coal during oxy-fuel combustion, Proceedings of the Combustion institute, 32 (2009), pp. 2091-2098
  22. Choi S., Observation of Single coal particles flames. Combustion Science and Technology, 78 (1991) pp. 117-126
  23. McLean W. J., Direct observations of devolatilizing pulverized coal Particles in a combustion environment, Eighteenth Symposium (International) on Combustion, 18 (1981) pp.1239-1248
  24. Kobayashi H.,, Coal Devolatilization at High Temperatures, Sixteenth Symposium (International) on Combustion 16 (1977) pp.411-425.
  25. Jost M. E., Reactivity of Pulverised coal in an Oxidizing Environment, Ph.D. Thesis, Stanford University, Stanford. USA. 1994
  26. Timothy L. D., Characteristics of single Particle coal combustion, Nineteenth Symposium (International) on Combustion/The Combustion Institute, 19 (1982) pp.1123-1130.
  27. Cesar O. Gomez, Francis J. Vastola, Ignition and combustion of single coal and char particles: A quantitative differential approach, Fuel, 64 (1985) 4, pp.558-563
  28. Jamaluddin A.S., Modeling of Coal Devolatilization and Its Effect on Combustion Calculations, Combustion and Flame, 62 (1985) pp. 85-89
  29. Zeenathul Farida Abdul Gani , Ignition Behaviour of Individual Pulverized Coal Particles in Air (O2/N2) and Oxy-Fuel (O2/CO2) Environment, Ph.D. thesis, University of Newcastle, . Callaghan, Australia, 2011