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TRANSIENT PCDD AND PCDF CONCENTRATIONS IN A MWC
Citation:
GULLETT, B. K., A. TOUATI, S. P. RYAN, AND D. G. TABOR. TRANSIENT PCDD AND PCDF CONCENTRATIONS IN A MWC. In Proceedings, DIOXIN2006: 26th International Symposium on Halogenated Persistent Organic Pollutants, Oslo, NORWAY, August 21 - 25, 2006. Norwegian Institute of Public Health, Oslo, Norway, 143-146, (2006).
Impact/Purpose:
conference paper
Description:
Time-resolved evaluations of combustor performance have shown that concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) and related pollutants undergo significant changes as a response to upset combustion conditions. During and after transient combustion conditions, PCDD/F raw gas levels have been shown to increase by one or two orders of magnitude. The consensus holds that the dominant formation mechanism during steady state operation of waste combustors is de novo synthesis due to the oxychlorination reactions of carbonaceous deposits. However, during transient conditions, the mechanism appears to change, at least in part; the PCDD and PCDF ratio increases¿the homologue profile shifts to lower chlorinated congeners, and the isomer patterns change. This work examines the changing concentrations of PCDDs/Fs and related compounds in a waste combustor by employing a series of short duration samples in parallel with conventional sampling and with jet resonance-enhanced multiphoton ionization for on-line trace monitoring. Boiler operating scenarios sampled included steady state, pre-shutdown, shutdown, startup, and extended post-startup.