Ignition of axial pulverized coal jets in a specially designed 100kW oxy-fuel combustor

Oxy-fuel combustion of pulverized coal is one of the few technologies that may allow CO2 sequestration technologies to be applied to existing coal-fired boilers. One issue of interest is to understand and predict the effects on ignition characteristics of the near-burner zone during oxy-fuel combustion processes. A combustion facility was designed and constructed to allow for the systematic investigation of near-burner aerodynamics of axial diffusion flames using a mixture of oxygen/carbon dioxide to replace the combustion air. The purpose of this research would be to determine how burner operating parameters and oxygen partial pressure influence fame attachment/detachment and coal ignition. The focus of this paper is the design and validation of this facility. This novel down-fired laboratory furnace is fired by a 100 kW pulverized coal axial burner, with electrical resistance wall heaters in the main burner zone to allow variations in heat loss. The furnace allows for visual access of the near burner flame zone through a quartz window, and also provides for stabilization of Type 0 axial turbulent diffusion flames through control of jet velocities and momenta. Transport "air" oxygen partial pressure (P-O2), coal particle size distribution, primary and secondary jet velocity, and wall temperature can be varied independently to determine the effect of each variable on flame attachment and pollutant emissions. Preliminary data show how flame attachment increased with PO2 and presence of coal fines. These variables were also shown to have a first order influence on NOx. Future work will use these data to validate simulations of axial coal jet ignition.