Lumped kinetics of reactions of volatiles and tar from plastic wastes

The goal of this paper was to set up a semi-detailed kinetic scheme for the fate of volatiles and tar produced from pyrolysis of plastic wastes. The scheme must be simple enough to be implemented in codes for the simulation of full scale reactors of pyrolysis, combustion and gasification. According to our scheme, under oxygen rich conditions volatiles and tar are readily oxidized (reactions 3 and 4), but under fuel rich conditions volatiles can undergo further transformations. We supposed that primary tar is mostly formed by long aliphatic chains. We chose n-hexadecane as representative of such young tar. Secondary reactions result in progressive aromatization and loss of hydrogen. We assumed naphthalene as representative of this class of intermediate products (reaction 1). Further reactions eventually lead to large PAHs and soot formation (reaction 2). Rate expressions for the lumped reaction scheme proposed have been obtained from regression of results of computational Chemkin experiments, based on the reaction network of Ranzi and coworkers (198 species and 6307 reactions).