A comparison of sulfur and chlorine gas species in pulverized-coal, air- and oxy-combustion

摘要

Gas phase measurements of sulfur species (SO_2, H_2S, SO_3, and COS) and HCl were collected in the staged near-burner region and the post tertiary injection oxidizing region of a pulverized-coal flame under air-and oxy-fired conditions. The near burner region was characterized by a high CO region near the center of the reactor directly below the burner. This reducing region as indicated by high CO concentrations produced high H_2S and COS and lower SO_2 concentrations in comparison to the post tertiary injection oxidizing region for both air and oxy-fired conditions. The concentrations of HC1 were in most cases insensitive to radial location. Concentrations of all measured sulfur gases were 2.4-2.9 times higher in oxy-fired conditions than air-fired conditions consistent with the increase expected by the removal of N_2 from the oxidizer. The concentration of H_2S were on average 5.8 times higher in oxy-fired reducing conditions than air-fired reducing conditions indicating that the oxy-fired near burner regions were higher in H_2S and lower in SO_2 than would be predicted by removal of N_2 alone from an air-fired system. The concentrations of SO_3 were less than 2% of the total sulfur for both air and oxy-fired conditions but the uncertainty of the measurement did not allow for a comparison between the two firing modes. The concentrations of HC1 were 2.4-2.8 times higher in oxy-fired conditions consistent with the removal of N_2 from the oxidizer. The total measured sulfur, HCl, SO_3, and reducing zone H_2S were all found to increase linearly with increasing sulfur and chlorine concentrations in the coal.