Demonstration of the waste tire pyrolysis process on pilot scale in a continuous auger reactor

This work shows the technical feasibility for valorizing waste tires by pyrolysis using a pilot scale facility with a nominal capacity of 150 kWth. A continuous auger reactor was operated to perform thirteen independent experiments that conducted to the processing of more than 500 kg of shredded waste tires in 100 h of operation. The reaction temperature was 550 °C and the pressure was 1 bar in all the runs. Under these conditions, yields to solid, liquid and gas were 40.5 ± 0.3, 42.6 ± 0.1 and 16.9 ± 0.3 wt.% respectively. Ultimate and proximate analyses as well as heating value analysis were conducted for both the solid and liquid fraction. pH, water content, total acid number (TAN), viscosity and density were also assessed for the liquid and compared to the specifications of marine fuels (standard ISO 8217). Gas chromatography was used to calculate the composition of the gaseous fraction. It was observed that all these properties remained practically invariable along the experiments without any significant technical problem. In addition, the reaction enthalpy necessary to perform the waste tire pyrolysis process (907.1 ± 40.0 kJ/kg) was determined from the combustion and formation enthalpies of waste tire and conversion products. Finally, a mass balance closure was performed showing an excellent reliability of the data obtained from the experimental campaign.