Carbon, Sulfur and Nitrogen Behavior during Pilot-Scale Testing of Oxy-Coal Combustion

摘要

Tests were performed in a 1.5 MW coal-fired pilot-scale furnace (L1500) to evaluate differences in carbon-in-ash, sulfur and NOx concentrations between air- and oxy-fired conditions. Results showed: 1. Carbon-in-ash was lower for oxy-combustion while firing Utah and Illinois coals and higher while firing PRB coal. 2. Sulfur in entrained ash was a linear function of calcium concentration in the mineral matter while oxy-firing. For the baghouse ash and while air firing, the ash sulfur and calcium content appeared unrelated. Analysis of the water condensate along with measurements of condensation rates indicated that sulfur removal through water condensation could be significant for this furnace. 3. Furnace NO_x concentrations were similar for air and oxy-fired conditions at burner stoichiometric ratios less than one, and much higher for oxy-fired conditions at BSRs greater than one, suggesting that recycled NO_x was reburned under substoichiometric conditions. NO_x emissions were much lower for oxy-combustion because of the lower volume of emitted flue gas.