THERMAL SCIENCE

International Scientific Journal

Thermal Science - Online First

online first only

Experimental and numerical investigation of flame characteristics during swirl burner operation under conventional and oxy-fuel conditions

ABSTRACT
Oxy-fuel coal combustion, together with carbon capture and storage or utilization, is a set of technologies allowing to burn coal without emitting globe warming CO2. As it is expected that oxy-fuel combustion may be used for a retrofit of existing boilers, development of a novel oxy-burners is very important step. It is expected that these burners will be able to sustain stable flame in oxy-fuel conditions, but also, for start-up and emergency reasons, in conventional, air conditions. The most cost effective way of achieving dual-mode boilers is to introduce dual-mode burners. Numerical simulations allow investigation of new designs and technologies at a relatively low cost, but for the results to be trustworthy they need to be validated. This paper proposes a workflow for design, modeling and validation of dual-mode burners by combining experimental investigation and numerical simulations. Experiments are performed with semi-industrial scale burners in 0.5 MWth test facility for flame investigation. Novel CFD model based on ANSYS FLUENT solver, with special consideration of coal combustion process, especially regarding devolatilization, ignition, gaseous and surface reactions, NOx formation, and radiation was suggested. The main model feature is its ability to simulate pulverized coal combustion under different combusting atmospheres, and thus is suitable for both air and oxy-fuel combustion simulations. Using the proposed methodology two designs of pulverized coal burners have been investigated both experimentally and numerically giving consistent results. The improved burner design proved to be a more flexible device, achieving stable ignition and combustion during both combustion regimes: conventional in air and oxy-fuel in a mixture of O2 and CO2 (representing dry recycled flue gas with high CO2 content). The proposed framework is expected to be of use for further improvement of multi-mode pulverized fuel swirl burners but can be also used for independent designs evaluation.
KEYWORDS
PAPER SUBMITTED: 2016-11-10
PAPER REVISED: 2016-12-20
PAPER ACCEPTED: 2016-12-22
PUBLISHED ONLINE: 2017-01-14
DOI REFERENCE: https://doi.org/10.2298/TSCI161110325J
REFERENCES
  1. Information on Global Warming Potentials, Technical Paper, Report No. FCCC/TP/2004/3, United Nations, New York, USA, 2004
  2. Edge, P. J., et al, A reduced order full plant model for oxyfuel combustion, Fuel, 101 (2012), 1, pp. 234-243
  3. Wall, T., et al, 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
  4. Vorrias, I., et al, Calcium looping for CO2 capture from a lignite fired power plant, Fuel, 113 (2013), 1, pp. 826-836
  5. Nikolopoulos, N., et al, Numerical investigation of the oxy-fuel combustion in large scale boilers adopting the ECO-Scrub technology, Fuel, 90, 1, (2011), pp. 198-214
  6. Hossain ,M. M., de Lasa, H. I., Chemical-looping combustion (CLC) for inherent separations - a review, Chemical Engineering Science, 63 (2008), 18, pp. 4433-4451
  7. Chen, L., Yong, S. Z., Ghoniem, A.F., Oxy-fuel combustion of pulverized coal: Characterization, fundamentals, stabilization and CFD modeling, Progress in Energy and Combustion Science, 38 (2012), 2, pp. 156-214
  8. Rathnam, R. K., et al, 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
  9. Shaddix, C. R ., Molina, A., Particle imaging of ignition and devolatilization of pulverized coal during oxy-fuel combustion, Proceedings of the Combustion Institute 32 (2009), 2, pp. 2091-2098
  10. Qiao, Y., et al, An investigation of the causes of the difference in coal particle ignition temperature between combustion in air and in O2/CO2, Fuel 89 (2010), 11, pp. 3381-3387
  11. Bejarano, P.A., L,evendis Y. A., Single-coal-particle combustion in O2/N2 and O2/CO2 environments, Combustion and Flame 153 (2008), 1-2, pp. 270-287
  12. Khare, S.P., et al, Factors influencing the ignition of flames from air-fired swirl pf burners retrofitted to oxy-fuel, Fuel 87 (2008), 7, pp.1042-1049
  13. Williams A., et al, Modelling coal combustion: the current position, Fuel, 81 (2002), 5, pp. 605-618
  14. Al-Abbas A. H., Naser J., Dodds D., CFD modelling of air-fired and oxy-fuel combustion of lignite in a 100 KW furnace, Fuel 90 (2011), 5, pp. 1778-1795
  15. Al-Abbas A. H., Naser J., Dodds D., CFD modelling of air-fired and oxy-fuel combustion in a large-scale furnace at Loy Yang A brown coal power station, Fuel 102 (2012), 1, pp. 646-665.
  16. Álvarez L., et al, CFD modeling of oxy-coal combustion: Prediction of burnout, volatile and NO precursors release, Applied Energy 104 (2013), 1, pp. 653-665
  17. Chui E. H., Douglas M. A., Tan Y., Modeling of oxy-fuel combustion for a western Canadian sub-bituminous coal, Fuel 82 (2003), 10, pp. 1201-1210
  18. Toporov D., et al, Detailed investigation of a pulverized fuel swirl flame in CO2/O2 atmosphere, Combustion and Flame, 155 (2008), 4, pp. 605-618
  19. Bhuiyan A. A., Naser J., Numerical modelling of oxy fuel combustion, the effect of radiative and convective heat transfer and burnout, Fuel 139 (2015), 1, pp. 268-284.
  20. Vega F., et al, Geometrical parameter evaluation of a 0.5 MWth bench-scale oxy-combustion burner, Fuel 139 (2015), 1, pp. 637-645
  21. Smart J.,et al, Characterisation of an oxy-coal flame through digital imaging, Combustion and Flame 157 (2010), 6, pp. 1132-1139
  22. ANSYS Inc., ANSYS FLUENT 13.0 theory guide release 12.0., 2009
  23. Hu Y., Yan J., Numerical simulation of radiation intensity of oxy-coal combustion with flue gas recirculation. International, Journal of Greenhouse Gas Control 17 (2013), 1, pp. 473-480
  24. Rebola A., Azevedo J. L. T., Modelling coal combustion with air and wet recycled flue gas as comburent in a 2.5 MWth furnace, Applied Thermal Engineering, 86 (2015), 1, pp. 168-177
  25. Richter A., et al. Detailed analysis of reacting particles in an entrained-flow gasifier, Fuel Processing Technology, 144 (2016), 1, pp. 95-108
  26. Jovanovic R., et al, Sensitivity analysis of different devolatilisation models on predicting ignition point position during pulverized coal combustion in O2/N2 and O2/CO2 atmospheres, Fuel 101 (2012), 1, pp. 23-37
  27. Jovanovic R., et al, Numerical investigation of influence of homogeneous/heterogeneous ignition/combustion mechanisms on ignition point position during pulverized coal combustion in oxygen enriched and recycled flue gases atmosphere, International Journal of Heat and Mass Transfer 54 (2011), 4, pp. 921-931
  28. Shih T. H. et al, A New k- ε Eddy-Viscosity Model for High Reynolds Number Turbulent Flows - Model Development and Validation, Computers and Fluids, 24 (1995),24, 3, pp.227-238.
  29. Launder B. E., Spalding D. B., Lectures in Mathematical Models of Turbulence, Academic Press, London, UK, 1972.
  30. Launder B. E., Spalding D. B., The numerical computation of turbulent flows, Computer Methods in Applied Mechanics and Engineering, 3 (1974), 2, pp. 269-289
  31. Chui E. H., Raithby G. D., Computation of Radiant Heat Transfer on a Non-Orthogonal Mesh Using the Finite-Volume Method, Numerical Heat Transfer, Part B, 23 (1993), 3, pp. 269-288.
  32. Yin C., et al, New Weighted Sum of Gray Gases Model Applicable to Computational Fluid Dynamics (CFD) Modeling of Oxy −Fuel Combustion: Derivation, Validation, and Implementation, Energy and Fuels, 24 (2010), 12, pp. 6275-6282
  33. Solomon P. R., et al, General model of coal devolatilization, Energy and Fuels, 2 (1998), 4, pp. 405-422
  34. Merrick D., Mathematical models of the thermal decomposition of coal 1, The evolution of volatile matter, Fuel, 62 (1983), 5, pp. 535-539
  35. Glarborg P., Jensen A. D., Johnsson J. E., Fuel nitrogen conversion in solid fuel fired systems, Progress in Energy and Combustion Science, 29 (2003), 2, pp.89-113
  36. Andersen J., et al, Global combustion mechanisms for use in CFD modeling under oxy-fuel conditions, Energy and Fuels, 23 (2009), 3, pp. 1379-89
  37. Shaw W., et al, Determination of global kinetics of coal volatiles combustion, Symposium (International) on Combustion, 23 (1993), 1, pp. 1155-1162
  38. Prieler R., et al, Numerical investigation of the steady flamelet approach under different combustion environments, Fuel, 140 (2015), 1, pp. 731-743
  39. Yin C., Rosendahl L. A., Kær S. K., Chemistry and radiation in oxy-fuel combustion: A computational fluid dynamics modeling study, Fuel, 90 (2011), 7, pp. 2519-2529
  40. Guo J., et al, Numerical investigation on oxy-combustion characteristics of a 200 MWe tangentially fired boiler, Fuel, 140 (2015), 1, pp. 660-668
  41. Field, M. A., Gill, D. W., Morgan B. B., Hawskley P. G. W., Combustion of pulverised coal, the British coal utilisation research association, leatherhead, 1967
  42. De Soete G., Overall reaction rates of NO and N2 formation from fuel nitrogen, Symposium (International) on Combustion, 15 (1975), 1, pp. 1093-1102
  43. IFRF Today, www.ffrc.fi/Liekkipaiva_2006/Liekkipaiva2006_IFRF_Today_HUPA.pdf
  44. Da Silva R. C., Kangwanpongpan T., Krautz H. J., Flame pattern, temperatures and stability limits of pulverized oxy-coal combustion, Fuel, 115 (2014), 1, pp. 507-520
  45. Spliethoff, H., Power Generation from Solid Fuels, Springer, Berlin, Germany, 2010