Simulation of waste tire pyrolysis in a multi-chamber fluidized bed by coupling CFD-DEM with a particle shrinkage model

The remixing of waste tire particles in a fluidized bed reactor not only increases the energy consumption of pyrolysis but also results in the wastage of raw materials. This study investigates the fluidization and migration behavior of waste tire particles using Computational Fluid Dynamics and Discrete Element Method (CFD-DEM). A particle shrinkage model was integrated into the EDEM discrete element software through an open-source application program interface (API) to accurately represent the real particle pyrolysis process. Particle Image Velocimetry (PIV) technology was employed to validate the accuracy of the numerical simulation results and to analyze the distribution of various pyrolysis stages as well as the flow field structure within the multi-chamber fluidized reactor. The findings indicate that the pyrolysis times for waste tire particles were 55.51, 44.18, and 34.42 s, with corresponding residence times of 34.82, 33, and 32.13 s at temperatures of 600, 650, and 700 °C, respectively. The heating and dry stage was predominantly concentrated in the first chamber, whereas the synthetic rubber pyrolysis primarily occurred in the third chamber. A fountain-shaped flow field structure was observed in each chamber, along with disordered particle motion at the inlet and guide plate sides.