Evaluation of PCDD/F partitioning between vapor and solid phases in MWI flue gases with temperature variation.

Partitioning of PCDD/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofuran) between vapor and solid phases in flue gas is affected by several factors including temperature variation. In this study, PCDD/F removal efficiencies achieved with activated carbon injection (ACI) and partitioning of vapor/solid phase PCDD/Fs in flue gases with temperature variation in a municipal waste incinerator (MWI) are evaluated via intensive flue gas sampling. Results indicate that most PCDD/Fs in flue gas downstream of the ACI+bag filter (BF) exist in vapor phase (over 90%) while the removal efficiencies of vapor and solid phase PCDD/Fs are 98.5-99.6% and 99.8-99.9%, respectively. The results of flue gas samplings also indicate that there is optimal operating temperature for PCDD/F removal achieved with ACI. Additionally, a pilot-scale adsorption system (PAS) is constructed in this study to evaluate the PCDD/F partitioning affected by temperature. The results of the PAS experimentation indicate that about 55% and 25% vapor phase PCDD/Fs passing through the filter cake (adsorbent) are transferred to solid phase at 150 and 200 degrees C, respectively. As the temperature is increased to 250 degrees C, filter cake (adsorbent) cannot effectively adsorb vapor phase PCDD/Fs and significant PCDD/Fs are formed via de novo synthesis.