| The disposal of waste tires is an increasing environmental problem. In China, the main routes for disposal have centered on landfill, open dumping which have proven to be harmful for environment. By incineration only the thermal value of the tires is used while valuable chemical compounds are lost. On the other hand, pyrolysis is an environmentally friendly way to recover useful compounds from waste tyres.A bench-scale bubbling fluidized bed with 30mm inside diameter was used to study the pyrolysis of waste tires. The effects were examined of (1)pyrolysis temperature (450-850℃) and (2)different size of bed materials and (3)fluidization velocity(U/Umf) and (4)CaO sorbent and (5)steam pyrolysis on pyrolysis of waste tires. A Internally Recurrent Net (IRN) neutral network model was established to predict the yields of products and secondary pollutions.As the temperature is increase there is an increase in the yield of pyrolysis gas and decrease in the yield of char. The maximum yield of oil appeared at 550C. Yield of gas increase with smaller bed materials, bigger fluidization number, adding sorbents and using steam pyrolysis. The production rate of pyrolysis gas reduced from 300s at 450℃ to less than 75s at 850℃ . The gases were identified as CH4, C2H4, H2. CO2 and CO, with lower concentrations of C2H2 and other hydrocarbon gases. As the temperature increase there is an increase in yields of H2. CH4. CO. C2H4, LHV and decrease in CO2. LHV of pyrolysis gas is between 8 MJ/Nm3 and 24MJ/Nm3.The size of bed materials and fluidization velocity are important influence factor. The influence of them is similar with each other. Gas production rate and yields of H2, CO, CH4, C2H6 increase as becoming smaller bed materials and bigger U/Umf, whereas C2H4.CO2 decrease. There is not obvious influence of them on LHV and density of pyrolysis gas. CaO catalyze pyrolysis secondary reactions. So, there is an increase forall gas compounds except for CO2. Correspondingly, there is an increase in LHV and density of gas.Steam is very good gasification medium. Relative to N2 pyrolysis, more yields for H2. CO2. C2H2, C2H4. C2H6 and less for CO. CH4 appeared. Correspondingly, there is an increase in LHV and density of gas. The element nitrogen and sulfur in waste tyres are major precursors of secondary pollutions. During pyrolysis, S to H2S conversion ratio is between 0.5-26%, N to NH3 10-55% and N-HCN <0.5%. Pyrolysis temperature is major factor effecting on H2S, NH3, HCN release. In CO2 atmosphere, more H2S was released than in N2 atmosphere. And N to NH3 conversion ratio decrease as temperature increase. There is not inevitable relation between NH3 formation and HCN. In this paper, the dynamic release of H2S, NH3 and HCN was studied too.The kinetic parameters for pyrolysis-gas formation reaction were calculated, based on experimental data from FB reactor. According to activation energy, we can conclude that the reaction was controlled by mass transfer and diffusion in bigger bed material FB, by diffusion andmical reaction controlled in smaller bed material FB. FTIR analysis of pyrolysis oils indicated the presence of alkanes, alkenes, ketones or aldehydes, aromatic, polyaromatic and substituted aromatic groups. Aromatic hydrocarbons were increasing as temperature increasing, whereas aliphatic hydrocarbons were decreasing. GC-FID analysis indicated the presence of PAHs known as carcinogenic or mutagenic hydrocarbons. As temperature was increasing, bed materials becoming smaller and fluidization number becoming bigger the concentration of PAHs was increasing from 0.91% to 9.63%.As temperature was increased, percentage of C, H,N,S and H/C of chars decreased. It showed that the aromaticity of chars increased. Most of S, about 60-80%, remains in chars.The characteristics of pyrolytic chars prepared at various pyrolysis temperatures were analyzed by Mercury Porosimeter and SEM. The experimental results showed t...
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