Influence of combustion parameters on the formation of polychlorinated dibenzo-p-dioxins, dibenzofurans, benzenes, and biphenyls and polyaromatic hydrocarbons in a pilot incinerator

A laboratory-scale fluidized-bed incinerator was used to study the influence of several combustion parameters with respect to the emission of important aromatic contaminants including polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), polychlorinated benzenes (PCBz), polyaromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). The parameters studied include bed temperature, O[sub 2]-concentration, variations in HCl and H[sub 2]O, and temperature and residence time in the postcombustion zone. A two-level fractional factorial design was used for planning the experiments. Flue gas samples were collected and analyzed on HRGC-HRMS. The most important parameter for the formation of the above chlorinated aromatics was found to be the residence time in the postcombustion zone. A substantial formation of the chlorinated compounds occurred during residence times as short as 1.6 s. PAH formation was found to be influenced by the oxygen concentration in the combustion air, and good combustion conditions favor low PAH emissions. 42 refs., 5 figs., 10 tabs.