ROLE OF COMBUSTION AND SORBENT PARAMETERS IN PREVENTION OF POLYCHLORINATED DIBENZO-P-DIOXIN AND POLYCHLORINATED DIBENZOFURAN FORMATION DURING WASTE COMBUSTION
Bk. Gullett et Pm. Lemieux, ROLE OF COMBUSTION AND SORBENT PARAMETERS IN PREVENTION OF POLYCHLORINATED DIBENZO-P-DIOXIN AND POLYCHLORINATED DIBENZOFURAN FORMATION DURING WASTE COMBUSTION, Environmental science & technology, 28(1), 1994, pp. 107-118
This research uses experimental data and a statistical approach to det
ermine the effect of combustion- and sorbent-injection-related paramet
ers on the mechanism of polychlorinated dibenzo-p-dioxin and polychlor
inated dibenzofuran (PCDD and PCDF, respectively) formation and preven
tion in waste combustors. The operation of a pilot-scale combustor was
varied to effect different regimes of oxygen (O2), hydrogen chloride
(HCl), and chlorine (Cl2) concentration, temperature; residence time;
quench rate; and sorbent injection. The fly ash loading of a municipal
waste combustor was simulated by postcombustion injection of fly ash
collected from a full-scale facility. Downstream sampling and analysis
indicated significant PCDD and PCDF formation, beyond concentrations
on the preinjected fly ash, at rates conducive to explaining formation
in full-scale facilities at particle/gas residence times < 5 s. Stepw
ise regression analyses determined the predictive parameters for four
models of PCDD, PCDF, the total of PCDD and PCDF yield, and the partit
ioning between PCDD and total yield. Substantial prevention of PCDD an
d PCDF formation can be brought about with upstream sorbent injection
for HCl and Cl2 reduction, control of excess air, and increased quench
rate.