title: Accurate sampling of PCDD/F in high temperature flue-gas using cooled sampling probes.
abstract: In a laboratory-scale combustion reactor, flue-gas samples were collected at two temperatures in the post-combustion zone, 700°C and 400°C, using two different water-cooled sampling probes. The probes were the cooled probe described in the European Standard method EN-1948:1, referred to as the original probe, and a modified probe that contained a salt/ice mixture to assist the cooling, referred to as the sub-zero probe. To determine the efficiency of the cooling probes, internal temperature measurements were recorded at 5cm intervals inside the probes. Flue-gas samples were analyzed for polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs). Samples collected at 700°C using the original cooling probe showed higher concentrations of PCDD/Fs compared to samples collected using the sub-zero probe. No significant differences were observed between samples collected at 400°C. The results indicated that artifact formation of PCDD/Fs readily occurs during flue-gas sampling at high temperatures if the cooling within the probe is insufficient, as found for the original probe at 700°C. It was also shown that this problem could be alleviated by using probes with an enhanced cooling capacity, such as the sub-zero probe. Although this may not affect samples collected for regulatory purposes in exit gases, it is of great importance for research conducted in the high-temperature region of the post-combustion zone.
authors.affiliation: Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden. chau.phan@chem.umu.se
authors.forename: Duong Ngoc Chau
authors.initials: DN
authors.lastname: Phan
authors.forename: Eva
authors.initials: E
authors.lastname: Weidemann
authors.forename: Lisa
authors.initials: L
authors.lastname: Lundin
authors.forename: Stellan
authors.initials: S
authors.lastname: Marklund
authors.forename: Stina
authors.initials: S
authors.lastname: Jansson
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D001572:Benzofurans / Q000032:analysis*; D006358:Hot Temperature; D017745:Incineration / Q000379:methods; D044367:Phase Transition; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis
chemical_list: D000393:Air Pollutants; D001572:Benzofurans; D000072317:Polychlorinated Dibenzodioxins; C023614:dibenzofuran