In-flame reduction of NO_x in oxy-propane combustion at high inlet oxygen concentrations: the importance of soot-NO_x interactions

摘要

Previous oxy-fuel combustion of propane performed at Chalmers University of Technology has shown possibilities for high NO_x reduction during inlet oxygen concentrations above 35%. Such enhanced reduction has not been possible to acknowledge to only homogenous reburning effects. In this work it is investigated to what extent this can be an effect of soot-NO_x interactions. Soot formation has been studied by using an existing soot model. By comparing modeling results with recently published experimental data it is shown that the model is capable to predict soot formation during relevant conditions. In addition, a model for homogenous nitrogen chemistry has been used in the evaluation and sensitivity to key combustion parameters. The increased amount of soot found at high oxygen concentrations, together with higher reaction activity for gas phase species, known to be of importance for both NO_x formation and soot production, support the theory that the high NO_x reduction found at high oxygen concentration is a result of soot-NO_x interactions.