Influence of failure modes on PAH emission during lab-scale incineration

In this report the effect of process failure modes on aromatic and polynucl ear aromatic compounds during the lab-scale incineration of municipal sludg e is examined. The thermal, temporal, and fuel-oxidant mixing failure modes were tested. They were respectively simulated by holding the primary therm al exposure at 400 degrees C and varying the afterburning between 500 and 1 100 degrees C, the afterburning residence time between 1 and 3 s, and the c ombustion oxygen using almost stoichiometric (30%) and large excess (160%), Results indicate that the thermal failure mode is the most important facto r controlling the number of compounds emitted at an afterburning temperatur e below 700 degrees C, At higher temperatures the number and amounts of aro matic and polynuclear aromatic compounds emitted are controlled by the fuel -oxidant mixing failure. It was found that, when fuel oxidant mixing failur e was active, the formation of 20 aromatic and polynuclear aromatic compoun ds was observed even at an afterburning temperature as high as 1100 degrees C while, when it was not active, at 900 degrees C no emission of organics was detected.