An initial study of the fine fragmentation fly ash particle mode generated during pulverized coal combustion
An initial study of the fine fragmentation fly ash particle mode generated during pulverized coal combustion
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DOI：
10.1016/s0378-3820(03)00006-7
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发表时间：
2003-05
影响因子：
7.5
通讯作者：
W. Seames
中科院分区：
文献类型：
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作者：
W. Seames
商业煤炭燃烧源排放的空气动力学直径小于 2.5 μm 的环境颗粒物可能比排放较大颗粒的颗粒物吸入人类和动物呼吸系统的风险更大。此外，烟气颗粒收集设备对这些较小颗粒的去除效率较低，这也可能增加在顺风环境中的沉积以及随后迁移到地下水位中。最近的结果表明，粉煤灰颗粒的形成最好描述为三峰粒径分布，包括亚微米烟气区域、以约 2.0 μm 直径为中心的细碎裂区域和块状碎裂区域。对导致精细破碎区域形成的机制以及这种形成如何影响有毒微量金属分配的基本了解是减轻煤炭燃烧对环境影响的重要一步。给出了与该问题相关的一些因素相关的结果。对细破碎区域中飞灰颗粒的广泛 SEM 检查表明，由于断裂、拉伸和脱落等不规则性，与超微米颗粒相比，这些颗粒似乎具有更大的有效表面积。这些颗粒似乎还与氧阴离子微量元素（例如砷和硒）更具反应性，这对于理解煤粉燃烧过程中与微量元素分配相关的主导机制可能很重要。
The emission of ambient particulate matter that is less than 2.5 μm in aerodynamic diameter from commercial coal combustion sources may represent a greater risk of inhalation into human and animal respiratory systems than emission of larger particles. In addition, there is lower removal efficiency in flue gas particle collection equipment for these smaller particles that may also increase deposition in the downwind environment and subsequent migration into the water table. Recent results suggest that pulverized coal fly ash particle formation is best described as a tri-modal particle size distribution that includes a submicron fume region, a fine fragmentation region centered at approximately 2.0 μm diameter, and a bulk fragmentation region. A fundamental understanding of the mechanisms leading to the formation of the fine fragmentation region and of how this formation influences toxic trace metal partitioning is an important step to mitigating the environmental impact of coal combustion. Results are presented related to some of the factors related to this issue. An extensive SEM examination of fly ash particles in the fine fragmentation region indicates that these particles appear to have a much larger effective surface area compared to supermicron particles due to irregularities such as fractures, stretching, and shedding. These particles also appear to be more reactive with oxy-anion trace elements, such as arsenic and selenium, which may be important in understanding the dominant mechanism related to trace element partitioning during pulverized coal combustion.