Deep-staged, oxygen enriched combustion of coal

Oxygen enriched combustion of coal under different oxidant concentrations and staging levels has been performed in a 20 kW down fired pilot scale combustion test facility. The introduction of oxygen resulted in additional reduction of NO emissions as compared to simple air staged configuration. In comparison to air staged combustion, oxygen enriched air staged combustion at the 31% level of staging resulted in approximately 7%, 20% and 35% NO reduction for 28%, 30% and 35% overall oxygen concentration, respectively. Experimental evidence has also indicated that oxygen enrichment does appear to reduce NO levels along with improvement of carbon burnouts. The provision of oxygen has also resulted in operation of the test facility under lowered stoichiometric ratios. The advantages attributable to oxygen enriched combustion also included enrichment of CO2 concentration in the flue gas to reduce the cost of CO2 scrubbing and capture. The present work provides data associated to oxygen enriched combustion technology, which can be considered a compromise between conventional air-firing combustion and the emerging oxy-fuel combustion systems.