Sulfur and Chlorine Gas Species Measurements for a Suite of Nine Coals in a Staged Pulverized Coal Reactor

摘要

Chlorine and sulfur in coal contribute to boiler tube corrosion and air pollution. In order to characterize the evolution of these elements in combustion, Fourier transform infrared spectroscopy (FTIR) has been used to measure the concentrations of gas species containing sulfur and chorine. These species included SO_2, H_2S, SO_3, COS and HC1, and were measured in the reducing and oxidizing zones of a staged, 160 kWth, swirl-stabilized, pulverized coal reactor for a suite of nine US coals. A high percentage of the coal sulfur was released rapidly in the near burner reducing zone forming mostly SO_2 and H_2S. In the reducing zone the ratio of H_2S and COS to SO_2 was higher in regions of high CO concentration suggesting the sulfur was released primarily as H_2S and then later oxidized to SO_2. The mass of sulfur in the four measured gases increased between the reducing and oxidizing zones during char burnout. This may have been due to sulfur release from the char or conversion of unmeasured gas species such as S_2 to SO_2 as oxygen became available. In the oxidizing zone, sulfur was almost entirely in the form of SO_2. The amount of sulfur measured as SO_3 was consistently 1-2% of the total measured sulfur in both the oxidizing and reducing zones. A large fraction of the coal chlorine was released in the reducing zone as HCl. HCl concentrations were slightly higher in the center of the BFR and lower near the walls, but did not increase sharply in regions of high CO as did the H_2S. The mass of chlorine also increased between the reducing and oxidizing zones indicating chlorine release during char burnout.