| Summary: | 碩士 === 元智大學 === 機械工程學系 === 95 === Results show that there are 4 emission factors of the fluoride according to different units. The emission factor in spray dryer with burning heavy oil is 0.0077 kg/tonne-soil; in the wet scrubber with packed tower is 0.012 kg/tonne soil; for the kiln with burning natural gas and without control equipments, the emission factor is 0.0205 kg/tonne tile in the heating area and 0.0022 kg/tonne tile in the cooling area. Compare the fluoride emissions in the heating area with the cooling area in the kiln, it shows about 90.3 % of fluoride is emitted in the heating area. According to the results of factor analysis, in the spray dryer, (1) the decrease in the feed rate of raw materials will increase the exhaust temperature, exhaust moisture, but reduce the concentration of sulfur oxides; (2) the reduction of exhaust speed will enhance the concentrations of carbon dioxide, nitric oxides, and particulates; (3) the increase in the feed rate of fuel (heavy oil) will reduce the oxygen concentration; (4) the concentration of the fluoride decreases with the decrease in the feed rate of fuel. For the kiln, (1) the concentrations of nitric oxides and oxygen decrease with increasing exhaust temperature; (2) the increase in the feed rate of raw materials will decrease the concentrations of oxygen, fluoride and sulfur oxides; (3) the increase in the feed rate of fuel (natural gas) will enhance the oxygen exhaust and increase the concentrations of carbon dioxide and fluoride. Finally, the results of mass balance show that the losses of fluoride in non-heating areas primarily come from the escape of raw materials (3.86 %). While the emissions due to the high temperature, 78.39 % is in the spray dryer and 16.25 % is in the kiln. There is a difference of 0.87 % which is probably attributed to the analysis error or the escape from other exits. To sum up, whether in the spray dryer or in the kiln, the fluoride is present in the gaseous phase over 98 %, and the rest is adsorbed in the solid phase.
|
|---|
