State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
J Environ Sci (China). 2012;24(5):875-81. doi: 10.1016/s1001-0742(11)60869-3.
This study was designed to clarify the influence of operating conditions on the formation and emissions of polychlorinated-p-dibenzodioxins and dibenzofurans (PCDD/Fs) from a sintering process with hot flue gas recycling. A pilot scale sinter pot with simulated flue gas recycling was developed, and four key operational parameters, including temperature, oxygen content of the simulated waste flue gas, the coke rate of the sintering mixture, and the quicklime quality, were selected for exploring PCDD/Fs formation. The results showed that the temperature of the recycled flue gas had a major affect on PCDD/Fs formation, and a high temperature could significantly increase their formation during sintering. A clear linear correlation between the temperature of recycling flue gas and PCDD/Fs emission (r = 0.93) was found. PCDD/Fs could be reduced to a certain extent by decreasing the level of oxygen in the recycled flue gas, while sintering quality was unchanged. The coke rate had no significant influence on the formation of PCDD/Fs, but the quality of quicklime used in the sintering mixture could affect not only the amount of PCDD/Fs emissions but also the sintering productivity. Compared with a benchmark sinter pot test, PCDD/Fs emissions markedly decreased with improvements to quicklime quality. However, the reduction in PCDD/Fs emissions realized by using high-quality quicklime was limited by the temperature of the inlet gas. The highest reduction achieved was 51% compared with conventional quicklime when the temperature of the inlet gas was 150 degrees C.
本研究旨在阐明操作条件对采用热废气循环的烧结过程中多氯代二苯并对二恶英和二苯并呋喃（PCDD/Fs）形成和排放的影响。开发了带有模拟废气循环的中试规模烧结锅，并选择了四个关键操作参数，包括温度、模拟废气中的氧含量、烧结混合料的焦炭率和生石灰质量，以探索 PCDD/Fs 的形成。结果表明，循环废气的温度对 PCDD/Fs 的形成有重大影响，高温会显著增加烧结过程中它们的形成。在循环废气温度和 PCDD/Fs 排放之间发现了明显的线性相关性（r = 0.93）。通过降低循环废气中的氧含量，可以在一定程度上减少 PCDD/Fs，但烧结质量不变。焦炭率对 PCDD/Fs 的形成没有显著影响，但烧结混合料中使用的生石灰质量不仅会影响 PCDD/Fs 的排放量，还会影响烧结的生产率。与基准烧结锅测试相比，改善生石灰质量可显著降低 PCDD/Fs 的排放。然而，使用高质量生石灰减少 PCDD/Fs 排放的效果受到进气温度的限制。当进气温度为 150 摄氏度时，与传统生石灰相比，最高可减少 51%。
