INFLUENCE OF OPERATING PARAMETERS AND FUEL TYPE ON PCDD-F EMISSIONS FROM A FLUIDIZED-BED INCINERATOR

The influence of operating parameters and different fuel types on PCDD/F emissions was studied in a fluidized bed incinerator. Under conditions of incomplete combustion, CO concentration in the flue gas was positively, and O2 concentration was negatively correlated with total PCDD/F emissions. Low O2, high CO, and high C concentrations in the flue gas shifted the distribution pattern of PCDD/F to lower chlorinated homologues. Under normal operating conditions, high fluidized bed temperatures, low freeboard temperatures, and high O2 values increased PCDD/F levels. PCDD/F emissions did not depend on the HCl concentration in the flue gas. The investigated fuel types varied in their chlorine content which, in some experiments, was increased by adding NaCl or polyvinylchloride (PVC). Only the addition of 3% PVC to polyethylene resulted in an increase in PCDD/F concentrations. Apart from this single experiment, no effect of fuel type on PCDD/F emissions was observed. High water contents of refuse derived fuel did not affect total PCDD/F concentrations, but reduced the furans to dioxins ratio and led to a shift to lower chlorinated homologues.