Effects of the Furnace Temperature on the CO, CO_2, NO_x and Unburned Hydrocarbon Emissions from the Combustion of Coal and Alternative Fuels

摘要

Results are presented on the emissions of carbon monoxide (CO), carbon dioxide (CO_2), unburned aromatic hydrocarbons, as well as oxides of nitrogen (NO_x) from the combustion of pulverized bituminous coal, tire-derived fuel and, for a limited number of runs, waste plastics-derived fuel. The particle size cuts of pulverized coal, tire and plastics were 63-75 #mu#m, 180-212 #mu#m and 180-300 #mu#m, respectively. Combustion experiments were conducted in a laboratory-scale drop-tube furnace at gas temperatures, in the range of 1300-1600 K, and several fuel mass loadings in the furnace, expressed in terms of global equivalence ratios in the range of 0.4-2.4. The CO, CO_2 and NO_x emissions were monitored continuously with infrared absorption and chemilluminescent instruments. Up to sixty 2-7 ring polynuclear aromatic hydrocarbons (PAH) were detected by capillary gas chromatography - mass spectrometry (GC-MS) techniques. Results showed that the PAH emission yields (mg/g fuel introduced) increased drastically with increasing bulk equivalence ratio (in the aforementioned range), at fixed furnace temperatures. This was also true for the CO yields, while the CO_2 yields increased with increasing O, reached a maximum around stoichiometry and then decreased mildly. NO_x yields decreased precipitously with increasing equivalence ratio. The CO and, especially, the PAH yields from tire-derived and plastics-derived fuels were much higher than those from coal, but the relative amounts of individual PAH components we4re remarkably similar in the combustion effluent of all fuels. The CO_2 emissions and, especially, the NO_x emissions from tire crumb were lower than those from coal. The CO_2 emissions from plastics were comparable to those from coal, but their NO_x emissions were much lower than those from tire.