Energy valorization of tyres waste: A multi-step approach

A multi-step approach for studying the feasibility of energy valorization of worn out tyres is presented. First of all, a tyre sample was characterized by elemental analysis for the determination of the content of C, H and other elements, and for the evaluation of its heat of combustion. Pyrolysis of the same tyre sample was then studied by TG-MS/TG-GC-MS analyses and lab-scale reactor tests based on the results of the previous analyses. The thermal decomposition of the waste tyre produced a gaseous phase (20%wt of the tyre mass), a tyre pyrolysis oil (TPO, 40% wt) and the solid char (40% wt). Both tar and char were characterized by elemental analysis and heat of combustion determination. TPO presented HHV and LHV of 49.5 and 46.7 MJ/kg, while the HHV and LHV for solid char were 34.7 and 33.7 MJ/kg, respectively. Finally, a case of process application was studied as a last step, taking into account the features of waste tyres combustion plants and pyrolysis processes. The overall approach can be used for generating all the data necessary for design purposes.