Waste Tire Pyrolysis: Comparison between Fixed Bed Reactor and Moving Bed Reactor

Waste tire pyrolysis has been performed in a fixed bed and a moving bed reactor, in order to know the influence of the reactor type on the yields and product characteristics. Typical pyrolysis conditions have been used in both reactors (600 degrees C and inert atmosphere). The moving bed reactor operates in continuous mode, and it is designed to-process up to 15 kg/h of waste tire. An excellent process reproducibility and stability was observed. Moreover, when results obtained in the fixed bed and moving bed reactors are compared, it can be appreciated that total rubber conversion is achieved in both systems although solid residence time in the fixed bed is clearly longer than that in the moving bed reactor. In addition, a more severe cracking of the primary pyrolysis products occurs in the moving bed reactor due to the faster heating rate and the longer gas residence time. Regarding the pyrolysis products, the solid fraction is mostly constituted of carbon black, the liquid phase is a complex hydrocarbon mixture and the gas phase is a mixture of light hydrocarbons, carbon dioxide, carbon monoxide, hydrogen sulfide, and hydrogen.