Numerical study of plastic waste pyrolysis driven by char smoldering

Pyrolysis is a promising process for the valorization of plastic waste (PW). However, traditional pyrolysis processes have high energy consumption. On the other hand, smoldering has been proven as an effective and economic process to treat waste, becoming an attractive application for developing countries. Therefore, a reactor for PW pyrolysis driven by char smoldering was investigated in this study. A proof-of-concept was the development of a multidimensional mathematical model to verify the proposed reactor's feasibility and evaluate its performance. It was found that PW was pyrolyzed stably driven by a self-sustaining char smoldering front. The model suggested that the air inlet velocity and char concentration determined the duration of the PW pyrolysis process and tar and gas yields by regulating the front velocity and the peak temperature. The carrier gas inlet velocity controlled the tar's residence time in the PW pyrolysis chamber and further affected the tar and gas yields.