TY - GEN A1 - Krautz, Hans Joachim A1 - CorrĂȘa da Silva, Rodrigo A1 - Kangwanpongpan, Tanin T1 - Flame pattern, temperatures and stability limits of pulverized oxy-coal combustion T2 - Fuel : the science and technology of fuel and energy N2 - The challenges in maintaining a stable oxy-coal flame have been reported in the open literature. In case of pulverized coal combustion, narrower flammable regimes arise not only of differences in the feed gas composition, but also due to changes in the flow dynamics because of reduced volume flow rate through the burners to match similar temperatures and radiative heat transfer within the furnace. The present work focuses on the study of flame structure and stability of pre-dried lignite fired by a staged feed-gas burner. Experimental runs were carried out in a 0.40 MWth laboratory facility, with the objective of investigating the effects of swirl strength and feed gas distribution in the burner registers. To assess the experimental data, a numerical study of the non-reacting flow in the near burner region is performed. Predicted flow pattern and flame images show that the primary fuel jet penetrates the internal recirculation zone, forming an annular doughnut reverse flow region for both firing conditions and resembling a type-1 flame pattern. Temperature measurements indicate that the feed gas distribution among the burner registers control the flame temperature in parallel with the swirl number in both air-fired and oxy-fired environments. The oxy-fuel cases exhibite markedly reduced temperatures on the flame axis. This difference in the core arises not just from the more pronounced penetration depth of the primary jet, but also due to reaction mechanisms including pyrolysis and gasification reactions at the higher concentrations of CO2 and water vapor. Flame stabilization is shown to be strongly dependent on an appropriate distribution of the feed gas and strength of swirling flow in the burner front. The results correlated in terms of swirl number, secondary/tertiary flow ratio and secondary/primary axial momentum point to similarities in the stability limits between air-firing and oxy-firing. KW - Oxy-fuel; Pulverized coal combustion; Flame pattern; Stability limits Y1 - 2014 U6 - https://doi.org/10.1016/j.fuel.2013.07.049 SN - 0016-2361 IS - Vol. 115 SP - 507 EP - 520 ER - TY - GEN A1 - Kangwanpongpan, Tanin A1 - Franca, Francis H. R. A1 - Correa da Silva, Rodrigo A1 - Smith Schneider, Paulo A1 - Krautz, Hans Joachim T1 - New correlations for the weighted-sum-of-gray-gases model in oxy-fuel conditions based on HITEMP 2010 database T2 - International Journal of Heat and Mass Transfer Y1 - 2012 U6 - https://doi.org/10.1016/j.ijheatmasstransfer.2012.07.032 SN - 0017-9310 VL - 55 IS - 25-26 SP - 7419 EP - 7433 ER - TY - GEN A1 - Kangwanpongpan, Tanin A1 - Correa da Silva, Rodrigo A1 - Krautz, Hans Joachim T1 - Prediction of oxy-coal combustion through an optimized weighted sum of gray gases model T2 - Energy : the international journal Y1 - 2011 U6 - https://doi.org/10.1016/j.energy.2011.06.010 SN - 0360-5442 VL - 41 IS - 1 SP - 244 EP - 251 ER -