The purpose of this research is to understand and predict the effects of the near burner zone environment on ignition characteristics of a turbulent axial pulverized coal jet. In oxy-coal combustion this environment consists of O2 and CO2 (instead of N2). Ultimately it is planned to provide data for subsequent simulation validation studies that can be used to predict how air fired combustors may be retrofitted to oxy-coal.

Specifically the objective is to explore effects of variations in the partial pressure of O2 and CO2 on coal jet ignition and flame stability. During the oxy coal jet ignition process, the partial pressure of oxygen, PO2, in the transporting fluid, comprised one additional degree of freedom in controlling flame aerodynamics, and enhancing coal ignition, flame attachment/detachment and modifying pollutant formation. The experimental investigations are carried on in a 100 kW laboratory furnace outfitted with an axial burner and arrays of electrically-heated panels in the burner zone in order to control variations in near-burner heat loss. The furnace also has visual access to the burner zone through quartz windows. Sufficient supply of O2 and fresh CO2 are supplied through special utility infrastructure in the laboratory. A special CMOS sensor based camera is used to capture Type 0 axial turbulent diffusion flame shape for the use of statistical studies of flame length at different operational parameters, with special emphasis on systematic variations of partial oxygen pressure in both transport and secondary oxidant streams. Our experimental data show how flame attachment increased with PO2 in either primary or secondary oxidant streams. These variables were also shown to have a first-order influence on fuel NOx. Future work will use these data to validate CFD simulations of axial coal jet ignition in turbulent flows..

Keywords: Oxy-coal Combustion, flame stability, oxygen partial pressure (PO2), flame length, near burner phenomena, coal jet, type 0 axial turbulent flames