Transformation of Carbon in Refuse Incineration

Abstract

An attempt is made to explain the transformation of carbon in the incineration of refuse on a molecular level, based on the review of available technical literature. Special attention is given to the role of carbon transformation in the formation of the products of incomplete combustion (PIC), specifically dioxins. The combustion of refuse takes place in luminous diffusion flames, caused by radiation of carbon in the yellow spectral region. The pyrolysis of aromatic structures in refuse to coke and graphite proceeds through a pitch. The edges of the pitch structure are reactive sites for the formation of PIC and dioxin precursors. The fly ash metallic surfaces can serve as catalytic sites for the generation of free chlorine and the formation of halogenated aromatic compounds. The optimal structures of benzene adsorbed on the metallic surfaces are condusive to formation of dioxin and other PICs through an activated complex. Benzene is a better surrogate for PIC emission than CO. The best technique for the reduction of carbon particulates in refuse combustion is better mixing in the combustion zone, but certain additives can also inhibit its formation.