Prediction of staged coal combustion in three-dimensional furnaces
(EN)
Bergeles, G
(EN)
Papadakis, G
(EN)
A 3-D numerical method was used for the study of staged coal combustion in a semi-industrial-scale furnace experimentally investigated in the International Flame Research Foundation (IFRF). Detailed evaluation of the 3-D code against experimental data for temperature, oxygen and nitrogen monoxide concentration is presented. In the numerical algorithm is incorporated a higher-order finite-differencing scheme for all equations, along with a general devolatilisation model. In order to minimise time and memory requirements, the computational domain was limited to one quarter of the furnace with the aid of cyclic boundary conditions. A reasonable degree of agreement is indicated by comparison of predicted and experimental results. The NO post-processor used employs a simplified reaction path for the formation and destruction of NO, and both fuel NO and thermal NO are accounted for. Predicted NO levels indicate that under staged combustion conditions the relative effect of char nitrogen on the total NO formed is more important than in normal combustion conditions, where most NO is formed from the nitrogen contained in the volatile. The experimental observation that burner aerodynamic changes affect mostly conversion of volatile nitrogen to NO is correctly predicted.
(EN)
