Study on the pyrolysis law of tires in a molten salt heating pyrolysis reactor: Experimental and CFD-DEM simulation

Tire pyrolysis is an important method for the resource utilization of waste tires, and the heat and mass transfer characteristics of the reactor significantly affect the quality of the pyrolysis products. Current studies mainly focus on using air as the heat transfer medium for tire pyrolysis reactors. However, molten salt has better energy storage and heat transfer properties compared to air, yet research on using molten salt as a heat transfer medium for tire pyrolysis is still lacking. In this study, molten salt is innovatively used as the heat transfer medium, and the pyrolysis characteristics of tires are investigated based on a molten salt-heated tire pyrolysis reactor. A corresponding CFD-DEM method is developed to study the heat and mass transfer characteristics of tire particles during the pyrolysis process within the reactor. The results indicate that the proportion of single-ring aromatics in the pyrolysis oil exceeds 30%. The simulation results show that at a pyrolysis temperature of 500 °C, the average heating rate of the tire particles is approximately 0.4–0.6 K/s during the first 100 s. As the pyrolysis reaction progresses, the heating rate of the tire particles gradually decreases, and then starts to increase to 0.41 K/s after 400 s.