Fundamentals on Vaporization Behavior of Trace Metal Compounds at Different Atmospheres and Temperatures
Fundamentals on Vaporization Behavior of Trace Metal Compounds at Different Atmospheres and Temperatures
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DOI：
10.3775/jie.81.256
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发表时间：
2002-04
影响因子：
0.2
通讯作者：
H. Yao;Hirofumi Minato;I. Mkilaha;I. Naruse
中科院分区：
文献类型：
--
作者：
H. Yao;Hirofumi Minato;I. Mkilaha;I. Naruse
微量金属通常不可避免地包含在废物、煤等中。当废物和/或煤燃烧时，污染物如NOx、SOx、烟灰、颗粒、二恶英和重金属化合物从炉中排出。一些重痕量金属化合物在燃烧/焚烧过程中凝结在颗粒表面和/或形成细颗粒。由于难以通过常规灰尘收集系统捕获这些细颗粒，这些颗粒往往被排放到大气中。本文研究了铅、镉、铬化合物在较低温度下蒸发的基本行为。利用热天平研究了温度和反应气氛对铅、镉、铬化合物蒸发行为的影响。为了验证实验结果，还对每种化合物进行了化学热平衡计算。因此，金属化合物的蒸发行为似乎取决于它们各自的熔点。大多数氯化物在较低温度下容易蒸发。这表明HCl的存在增强了金属化合物的蒸发，而SO2的共存则抑制了Pb和Cd化合物的蒸发趋势。所有的镉化合物在还原条件下蒸发。化学热平衡计算结果与实验结果吻合较好。
Trace metals are usually inevitably contained in wastes, coals and so forth. When the wastes and/or coals are burnt, pollutants like NOx, SOx, soot, particulates, dioxins and heavy metal compounds are emitted from the furnaces. Some of the heavy trace metal compounds condense on the particle surface and/or form fine particulates during the combustion/incineration processes. Owing to the difficulties in capturing those fine particulates by means of conventional dust collection systems, those particulates tend to be exhausted into the atmosphere. In this study, fundamental behavior of the vaporization of Pb, Cd and Cr compounds was studied at relatively low temperature. In this experiment the effects of temperature and reaction atmosphere on the vaporization behavior of Pb, Cd and Cr compounds were studied using a thermobalance. The chemical thermoequilibrium calculation for each compound was also carried out in order to validate the experimental results obtained. As a result, the vaporization behavior of the metal compounds appears dependent on their respective melting points. Most of chlorides were easily vaporized at relatively low temperatures. This suggests that the presence of HCl enhances the vaporization of metal compounds, while coexistence of SO2 shows inhibition of the vaporization tendencies of Pb and Cd compounds. All of the Cd compounds vaporized in the reducing conditions. The results of chemical thermoequilibrium calculation agreed closely with the experimental results obtained.