Modeling of oxy-fuel combustion for a western Canadian sub-bituminous coal☆

The motivation of this research is to develop practical oxy-coal combustion techniques in order to facilitate the conversion of coal-fired utility power plants so as to recover a CO2 rich flue gas stream for use and/or sequestration. The objective of this study is to ascertain the applicability and accuracy of a modeling tool to assist with future pilot scale oxy-fuel combustion experiments and burner scale-up studies. Two modes of oxy-coal combustion, O2 enriched air (OEA) and recycled flue gas (RFG), were experimentally tested in a 0.3 MWth pilot-scale combustor using a western Canadian sub-bituminous coal. The computational fluid dynamic tool was utilized to model the combustion, heat transfer and pollutant formation characteristics of these test cases and to examine the impact due to changes in the combustion medium, burner swirl and burner configuration. The model provided insights for the observed variation in NOx production among the test cases: the dramatic increase in the OEA mode, the drop at higher burner swirl settings and the surprisingly small reduction in the RFG mode. Overall the model results compared well with measured data in all test cases and established confidence in using the model to explore new design concepts for oxy-coal combustion.