INFLUENCE OF POSTCOMBUSTION TEMPERATURE PROFILES ON THE FORMATION OF PCDDS, PCDFS, PCBZS, AND PCBS IN A PILOT INCINERATOR

A laboratory-scale fluidized-bed reactor fueled by a synthetic waste was used to study the influence of the flue gas temperature profile after the combustor on the formation of chlorinated aromatic compounds. An experimental plan of full factorial design involving the variables temperature and residence time was chosen for the experiments. Flue gas samples with residence time in the cooling section of the reactor between 0.9 and 2.9 s were collected at temperatures between 260 and 510 degrees C. Response surface models describing the formation of toxic equivalents of polychlorinated dibenzo-p-dioxins, dibenzofurans, and benzenes as a function of temperature and residence time were constructed from the analytical results. The samples were also analyzed for non-ortho-polychlorinated biphenyls. The results show that all the above compounds exhibit a similar dependency on temperature and residence time. The highest levels were obtained at 340 degrees C and 2.9-s residence time, and the lowest levels were obtained under conditions of rapid quenching of the flue gas temperature to 260 degrees C.