OCR Text |
Show · the concentration was decreased to 0.58 mg/l when the temperature was increased to 1200oe. When the stage-t\\·o temperature \\'as controlled at 900 and IOOO oe and the 02 supply rate was 0.0525 -- 0.210 ~L/min, the formation of benzene decreased as the oxygen supply increased . But, the toluene, styrene. n -butylbenzene increaed when the oxygen supply increased and the maximum concentration occured at 0.0525 and 0.105 NL/min of oxygen supply , respectively ,as shown in Figure 4 . and Figure 5. The trend of the formation of the aromatic same as compounds under various stage-two temperature are the the results of previous studies that residence time is controlled at 2 - 4 sec. But, the concentrations of the aromatic compounds decrease . The reasoning is that polystrene is not effectively decomposed to form styrene, toluene and benzene at shorter residence time . From the analysis result in the 14 species of PHAs as shown In Table 2. and Figure 6. These results indicated that the critical temperature \\t'hich provided the thermal energy enough to form PAHs and PAHs was about 10000e, for P.S. in two-stages incineration when the residence time is 0.5 - 1.0 sec. When the stage-two temperature increased to the critical temperature, the PAHs formed in large amount and particle was also formed in quantity. Pha,Flu and Pyr were major types found among the 14 PAHs. When the stage- t\\-·o temperature \\-'as increased, the 14 PAHs formed were decreased. The reason was that the low-ring PAHs grew to high-ring PAHs and soot particulates . For various oxygen supplied at 10000e, the formation of PAHs decreased about one order of magnitude with each double of the oxygen supply. The fewer the 14 PAHs were formed, the more the molecular oxygen was supplied. When oxygen supply was controlled at 0.210 NL/min, the PAHs and particulates form scarely . The rationale was that the oxidation of PAHs. nuclei and prescusor occured when the oxidized species are present. The fewer the precusors(acetylene and benzene) of PAHs formed, the more molecular oxygen was supplied. The 14 types of PAHs formed in detail are shown in Figures 7-10. When the pyrolysis temperature In the stage-two incineration was controlled at 900°C. the filter sample color from the emitted gas was light - 10 - |