Experimental and modeling study of single coal particle combustion in O2/N2 and Oxy-fuel (O2/CO2) atmospheres

Coal particle combustion experiments were performed in a drop tube furnace (DTF) with oxygen concentration from 21% to 100%, in N-2 and CO2 mixtures, under quiescent flow conditions. Small particles (75-90 pm) of a high-volatile bituminous coal (PSOC-1451) and a lignite coal (DECS-11) are analyzed with particular attention to the particle burnout times and the particle surface temperatures. These experimental measurements are compared with the predictions of a comprehensive model of coal combustion. Combustion of coal particles is a multi-scale process where both chemical and physical phenomena are involved, thus it requires a coupled and accurate description of the kinetics as well as of the heat and mass transport phenomena. Important features of the model are a multistep kinetic scheme of coal volatilization and detailed kinetics of the successive gas-phase reactions and of the heterogeneous reactions of both char oxidation and gasification. The achieved overall agreement between the experimental data and the numerical predictions, in terms of particle temperature and burnout times, highlights the capability of the model to simulate the effect of different operating conditions in the coal combustion processes. (C) 2013 The Combustion Institute. Published by Elsevier Inc. All rights reserved.