| OCR Text |
Show brown and the product of particle was less . When the temperature increased to 10000e, some liquifaction and black particles , such as tar , formed abruptly in large amounts . At incineration temperature abo ve 11 00 0(, the soot particle had the characteristics of black powder and the quantities of soot particles formed to be increased v;ith the increase of temperature. as shown in Figure 11 . To compare the results of the previous studies that the residence time is controlled at 2 - 4 sec, the trend of the formation of PAHs and soot particulates under variou s incineration conditions is very similar, except the critical temperature is shifted from 900 - 10000e to 1000 -11000e. When the stage-two temperature increased to 10000e, enough the,rmal energy was provided to form PAHs and soot. The concentration of Pha increased to 5100 J.l g/g-P.S. and 4-ring and 5-ring PAHs were also produced in quantity. HO\\"ever, during the physical observation, some liquifaction and black particles, such as tar, were found, but there were no powder- black soot particles. It was thought that the temperature of 10000e was not high enough to provide thermal energy for effective PAHs growth in series reactions, and so soot particles were not formed. When the pyrolysis temperature increased to 11000e, the soot particle began to form . When the stage- two temperature was increased to 1100°C, the benzene formed caused the follo\\"ing two types of reactions to occur : (1) Pyrolysis reaction : H 2 "' CH4 "' C2H 2 and so on form ed (2) Addition and polymer reaction: phenyl radical and acetylene and hydrogen atom reacted and formed naphthalene, and/or phenyl radical and benzene reacted and formed biphenyl, and further formed PAHs and soot particulates by the series reaction. The result also indicated that PAHs would effectively react with C6H6 and C2H2 and grow to larger PAHs when the pyrolysis temperature was increased to the higher temperature of 10000e. Reactions of soot formation such as nucleation, condendation coagulation, aggregation mechani sm s occured effectively. Because the change in free energies caused by the series reaction of PAHs and soot formation were so large, reaction s became practically irreversible . This, in turn, had the effect "of pulling " the reaction sequence forward twords formation of larger PHA s and soot |
