Evaluation of PCDD/F Congener Partition in Vapor/Solid Phases of Waste Incinerator Flue Gases

Abstract

Activated carbon injection (ACI) is commonly used to control PCDD/F (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans) emissions from stationary sources. In this study, the characteristics of PCDD/Fs emitted from one municipal waste incinerator (MWI) and two industrial waste incinerators (IWI-1 and IWI-2) that apply activated carbon systems for controlling the emissions are investigated via intensive stack sampling. MWI and IWI-1 are equipped with ACI and bag filters (BF) while IWI-2 is equipped with a fixed activated carbon bed (FCB). Results indicate that most PCDD/Fs in flue gas downstream of ACI+BF exist in vapor phase (over 90%) while most PCDD/ Fs exist in solid phase (over 60%) downstream of FCB. For MWI and IWI-1, the removal efficiencies of vapor and solid-phase PCDD/Fs are 98.5-99.6% and 99.8-99.9%, respectively. In addition,the removal efficiencies of vapor- and solid-phase PCDD/Fs are 84.5% and -13.4% in IWI-2, respectively. The results also indicate that the partition of vapor/solid-phase PCDD/F is affected by the type of the air pollutant control devices (APCDs) applied upstream and the particulate matter concentration in flue gas. On the basis of the sampling results of waste incinerators, this study preliminarily establishes the equations for predicting vapor/solid-phase PCDD/F partition in flue gases downstream of various APCDs including cyclone (CY), electrostatic precipitator (EP), FCB, ACI+BF, and selective catalytic reduction system (SCR).

Formation, Reduction and Emission Behaviors of CBzs and PCDD/Fs from Cement Plants

“…While the I-TEQ value was four times higher than that at the outlet of C2 due to the higher fraction of lower chlorinated PCDD/Fs. Moreover, the ratio of PCDD/Fs in gas phase was lower than the results obtained by Li et al (2015), indicating that there are other properties which can affect partitions of PCDD/Fs in flue gas besides saturation vapor pressures of PCDD/Fs (Chi and Chang, 2005). The level of 2,3,7,8-PCDD/Fs decreased to 397 pg Nm -3 (12 pg I-TEQ Nm -3 ) at the outlet of SP owing to the adsorption behavior.…”

“…The reduction efficiency was 94% (81% for I-TEQ) after passing through the bag filter, which was much higher than value reported by Lee et al (2004). For MWI, the removal efficiencies of gas phase PCDD/Fs are 98.5-99.6% (Chi and Chang, 2005). The partition of gas and solid phase PCDD/F could be affected by the type of the air pollutant control devices (APCDs) and the concentration of particulate matter in flue gas (Chi and Chang, 2005).…”

“…This trend might be attributed to a strong de novo synthesis or the precursor formation from CBzs. The possibility that most gas phase PCDD/Fs was generated via de novo synthesis has been expounded by a study in MSWI (Chi and Chang, 2005). Moreover, the potential for PCDF formation from reactions of chlorinated benzenes has been largely overlooked.…”

“…For MWI, the removal efficiencies of gas phase PCDD/Fs are 98.5-99.6% (Chi and Chang, 2005). The partition of gas and solid phase PCDD/F could be affected by the type of the air pollutant control devices (APCDs) and the concentration of particulate matter in flue gas (Chi and Chang, 2005). Additionally, the concentration of 2,3,7,8-PCDD/Fs in gas phase at the stack Y2 was 49 pg Nm -3 and the level of I-TEQ was higher than that at the stack Y1 owing to the high fraction of 2,3,4,7,8-PeCDF with value of 63%.…”

Simultaneous removal of PCDD/Fs and NOx from the flue gas of a municipal solid waste incinerator with a pilot plant

“…Among the air pollutant control devices (APCDs) applied (Choi and Lee, 2007;Inoue and Kawamoto, 2008;Ji et al, 2014), spraying of powdered activated carbon (PAC) into flue gas or installing a fixed-bed adsorption system to remove PCDD/Fs has been considered as the most convenient strategy Hung et al, 2011;Lu et al, 2013). Due to its simplicity in engineering and high efficiency, activated carbon injection (ACI) has become the popular technology for reducing PCDD/Fs emissions at most MSWIs (Chi and Chang, 2005;Wang et al, 2009). However, some issues still exist in removing PCDD/Fs from MSWIs with ACI.…”