Department of Environmental Engineering, Kocaeli University, Kocaeli 41380, Turkey.
J Air Waste Manag Assoc. 2013 Jul;63(7):788-95. doi: 10.1080/10962247.2013.790856.
A study was conducted to observe the changes in polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) levels and congener profiles in the flue gas of a hazardous waste incinerator during two start-up periods. Flue gas samplings were performed simultaneously through Air Pollution Control Devices (APCDs) (including boiler outlet, electrostatic precipitator (ESP) outlet, wet scrubbers (WS) outlet, and activated carbon (AC) filter outlet) in different combustion temperatures during a planned cold (long) start-up and an unplanned warm (short) start-up. The results showed that PCDD/F concentrations could be elevated during the start-up periods up to levels 3-4 times higher than those observed in the normal operation. Especially lower combustion temperatures in the short start-ups may cause high PCDD/F concentrations in the raw flue gas. Assessment of combustion temperatures and Furans/Dioxins values indicated that surface-catalyzed de novo synthesis was the dominant pathway in the formation of PCDD/Fs in the combustion units. PCDD/F removal efficiencies of Air Pollution Control Devices suggested that formation by de novo synthesis existed in ESP also when in operation, leading to increase of gaseous phase PCDD/Fs in ESP Particle-bound PCDD/Fs were removed mainly by ESP and WS, while gaseous phase PCDD/Fs were removed by WS, and more efficiently by AC filter.
This paper evaluates PCDD/F emissions and removal performances of APCDs (ESP, wet scrubbers, and activated carbon) during two start-up periods in an incinerator. The main implications are the following: (1) start-up periods increase PCDD/F emissions up to 2-3 times in the incinerator; (2) low combustion temperatures in start-ups cause high PCDD/F emissions in raw gas; (3) formation of PCDD/Fs by de novo synthesis occurs in ESP; (4) AC is efficient in removing gaseous PCDD/Fs, but may increase particle-bound ones; and (5) scrubbers remove both gaseous and particle-bound PCDD/Fs efficiently.
本研究旨在观察危险废物焚烧炉在两次启动过程中，烟道气中二恶英和呋喃（PCDD/F）水平及同系物形态的变化。在计划的冷（长）启动和非计划的热（短）启动期间，在不同燃烧温度下，通过空气污染物控制设备（APCDs）（包括锅炉出口、静电除尘器（ESP）出口、湿式洗涤器（WS）出口和活性炭（AC）过滤器出口）同时进行烟道气采样。结果表明，在启动期间，PCDD/F 浓度可能会升高，最高可达正常运行时的 3-4 倍。特别是在短启动期间较低的燃烧温度可能会导致原始烟道气中 PCDD/F 浓度较高。燃烧温度和呋喃/二恶英值评估表明，表面催化的从头合成是燃烧单元中二恶英形成的主要途径。空气污染物控制设备的 PCDD/F 去除效率表明，即使在运行中，ESP 中也存在从头合成形成的 PCDD/F，导致 ESP 中气相 PCDD/F 增加。颗粒结合态 PCDD/F 主要通过 ESP 和 WS 去除，而气相 PCDD/F 则通过 WS 去除，更有效地通过 AC 过滤器去除。
本文评估了焚烧炉在两次启动期间 APCD（ESP、湿式洗涤器和活性炭）中二恶英/呋喃的排放和去除性能。主要意义如下：（1）启动期间，焚烧炉中二恶英/呋喃的排放量增加了 2-3 倍；（2）启动期间的低燃烧温度导致原气中 PCDD/F 排放量较高；（3）ESP 中存在通过从头合成形成的 PCDD/F；（4）AC 对去除气相 PCDD/F 有效，但可能增加颗粒结合态 PCDD/F；（5）洗涤器有效地去除气相和颗粒结合态 PCDD/F。
