Dioxin and furan formation in FBC boilers

Fluidized bed combustion (FBC) is increasingly being used for municipal solid waste incineration and for various applications in which dioxin and furan (PCDD/F) formation are concerns. Despite the fact that fluidized bed combustion is a relatively low temperature system, current evidence shows that they perform relatively well. One hypothesis is that sulfur, which is contained in some of the fuels used in FBC (e.g. coal in cofiring situations), helps to reduce dioxin production. This paper endeavors to examine this speculation and finds that such benefits depend on the CI/S ratio and that at higher sulfur addition levels dioxins, furans, and polycyclic aromatic hydrocarbon (PAH) production may actually increase. This and the reasons for it are discussed.