Inhibition of PCDD/F by adding sulphur compounds to the feed of a hazardous waste incinerator

Sulphur compounds, including (NH4)2SO4 and pyrite, were tested as suppressants in a hazardous waste incineration facility. The test results suggested that adding sulphur compounds only slightly reduced PCDD/F stack emissions; this restricted effect was attributed to the release of fly ash in large amounts during the sulphur adding experiments, i.e., it was due to a malfunctioning of the baghouse filter. Nevertheless, for the combined flow of flue gas + fly ash a reduction of more than 50% was achieved for the total PCDD/F concentrations and the total toxic concentrations, and an even higher inhibition capability was observed for PCDD. Also, a simulation of the thermodynamic equilibrium conditions by sulphur dioxide was conducted in the domain of experimental interest. Deactivation of catalysts, which promote PCDD/F formation, was found to be the dominant inhibition mechanism in low temperature PCDD/F formation. SO2 could also inhibit the formation of molecular Cl2 via the Deacon reaction, but that was not the main reason for inhibition.

► Inhibitors of sulphur compounds inhibitor was used in hazardous waste incinerator. ► The total dioxin emission could be reduced to a large extent. ► Inhibition mechanism was explained by experiment results and software simulation.