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4B - Human health and environmental connections (WEP/197) critical temperature ranges in the PAH production during the pyrolisis of shredded recycled tire rubber. Perin, Guido1, Giacometti, Andrea1, Roverato, Isabella1, 1 Department of Environmental Sciences, University of Venice, Calle Larga S. Marta 2137, I-30123, Venice, Italy, Italy ABSTRACT- Experimental results indicate that during shredded recycled tire rubber pyrolisis in highly oxidizing conditions and when the temperature is not less than ca. 1000°C only environmentally insignificant amount of polynuclear aromatic hydrocarbons (PAH) are produced. Therefore, used tires can be conveniently utilized as an alternative economic fuel, for example, in concrete industry where 1400-1800°C can be reached. In this case our study showed that PAH chimney emission concentrations were less than 100 ng/Nm3, much lover than the regulatory acceptable threshold level for atmospheric emissions. These data were collected in situ and were corroborated by laboratory combustion simulations carried out in the 400-1000°C in presence of preheated input air. The laboratory experiments showed a remarkable relationship between temperature and the disappearance of PAH. Only fluoranthene seems to be present but in very limited amount. The presence of concrete dust does not improve the quality of the emissions probably because the limited contact time with the concrete dust within the reactor. Overall, this research seems to indicate that recycled tire rubber can be conveniently used as fuel for concrete industry when the contact time within the pyrolisis reactor is around few seconds (2-3 sec) while the pyrolisis temperature should be maintained above 1000°C. The contact with heterogeneous materials like concrete dust could be responsible for a sort of ′ protection ′ phenomena probably due to the absorption and subsequent desorption of PAH on the dust particles which could modify the contact time and consequently the pyrolisis kinetics. This inconvenient could be avoided by shifting the pyrolisis zone in a reactor region where no dust is still present. Key words: rubber pyrolisis, recycled tire rubber, PAH production, combustion simulations |
