PCDD/F prevention by novel inhibitors: Addition of inorganic S- and N-compounds in the fuel before combustion

The objectives of this work were to study the addition of sulfur and nitrogen containing compounds to the fuel before the combustion, to examine their capacity for preventing PCDD/F emissions, to investigate their influence on the PCDD/F homologue patterns and to determine the most effective additive concentration used for inhibition. Various sulfur and nitrogen containing solid compounds were mixed with Refuse Derived Fuel (RDF) in proportions of 10% w/w of the fuel, and the mixtures were combusted in a lab-scale reactor at 1000 degreesC. Analysis and quantification of PCDD/F showed that inorganic sulfur containing compounds significantly affected PCDD/F emissions, resulting in more than 98% reduction of toxic compounds. However, urea presented a lower prevention capacity and resulted in about 28% reduction of PCDD/Fs. High PCDD/F prevention efficiencies, about 96%, were also obtained during the combustion of a mixture containing 1% w/w of amidosulfonic acid (ASA) used as the additive. In addition, the presence of sulfur and nitrogen containing compounds affected the PCDD/F formation pathways, as it was observed from the PCDD/F ratios and the homologue profiles. The PCDD/F prevention ability of sulfur containing compounds is discussed; it could be attributed to the formation of sulfur-copper complexes.