Emissions of mercury, trace elements, and fine particles from stationary combustion sources
Emissions of mercury, trace elements, and fine particles from stationary combustion sources
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DOI：
10.1016/s0378-3820(00)00082-5
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发表时间：
2000-06
影响因子：
7.5
通讯作者：
C. Senior;J. Helble;A. Sarofim
中科院分区：
文献类型：
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作者：
C. Senior;J. Helble;A. Sarofim
来自固定燃烧源的微量元素和汞的排放取决于这些元素在燃料中的存在、元素在炉中转化为蒸气和颗粒的过程以及蒸气和颗粒穿透空气污染控制装置的能力。对于静电除尘器（ESP），在美国超过90%的燃煤电站锅炉中使用，颗粒的优先逃逸尺寸为0.1-1.0 μm。在此尺寸范围内的颗粒的主要来源是母体燃料中无机成分的蒸发和冷凝。潜在的有毒元素虽然主要局限于颗粒相，但由于优先在亚微米颗粒物质表面凝结，因此可能会向环境释放更多。与较大的飞灰颗粒的表面反应可以通过将痕量元素从难以捕获的亚微米颗粒中重新分布来减少这些排放。相比之下，汞是煤中最易挥发的微量元素，当汞以元素蒸气形式存在时，其逃逸几乎完全。然而，汞的排放可以通过转化为氯化汞而得到缓解，而氯化汞更容易在洗涤器中被捕获或以颗粒形式被收集。在本文中，我们提出了我们最近的研究进展，有助于提高对决定微量元素排放的因素的相对重要性的理解。在理解和量化控制燃料无机成分转化的每一个过程方面取得了重大进展，从而在预测排放方面取得了可喜的成果，给出了燃料的详细特征、燃料所暴露的燃烧条件以及APCD的特性。
The emissions of trace elements and mercury from stationary combustion sources are determined by the occurrence of these elements in fuels, the transformation of the elements into vapor and particles in furnaces, and the ability of the vapors and particles to penetrate the air pollution control devices (APCDs). For electrostatic precipitators (ESPs), in use at greater than 90% of coal-fired utility boilers in the US, the preferential escape of particles is in the 0.1–1.0 μm size. The major source of particles in this size range is the vaporization and condensation of the inorganic constituents in the parent fuel. Potentially toxic elements, although mainly confined to the particulate phase, may therefore show enhanced release to the environment as a result of preferential condensation on the surface of submicron particulate matter. Surface reaction with larger fly ash particles can reduce these emissions by redistributing the trace elements away from the difficult-to-capture submicron particulate. In contrast, mercury is the most volatile of the trace elements in coal and its escape is near complete when the mercury is in the elemental vapor form. Mercury emissions may be mitigated, however, by transformation to mercuric chloride, more readily captured either in scrubbers or by collection in the particulate form. In this paper, we present our recent research developments contributing to an improved understanding of the relative importance of factors determining trace element emissions. Significant progress that has been made in understanding and quantifying each of the processes governing the transformation of the inorganic constituents of fuels leading to promising results on the prediction of emissions given detailed characterization of fuels, the combustion conditions to which they are exposed, and the characteristics of APCDs.