Institute for Combustion Science and Environmental Technology (ICSET), Western Kentucky University (WKU), Bowling Green, Kentucky 42101, USA.
Environ Sci Technol. 2010 May 1;44(9):3429-34. doi: 10.1021/es903661b.
The formation of sulfur trioxide (SO(3)) in coal-fired utility boilers can have negative effects on boiler performance and operation, such as fouling and corrosion of equipment, efficiency loss in the air preheater (APH), increase in stack opacity, and the formation of PM(2.5). Sulfur trioxide can also compete with mercury when bonding with injected activated carbons. Tests in a lab-scale reactor confirmed there are major interferences between fly ash and SO(3) during SO(3) sampling. A modified SO(3) procedure to maximize the elimination of measurement biases, based on the inertial-filter-sampling and the selective-condensation-collecting of SO(3), was applied in SO(3) tests in three full-scale utility boilers. For the two units burning bituminous coal, SO(3) levels starting at 20 to 25 ppmv at the inlet to the selective catalytic reduction (SCR), increased slightly across the SCR, owing to catalytic conversion of SO(2) to SO(3,) and then declined in other air pollutant control device (APCD) modules downstream to approximately 5 ppmv and 15 ppmv at the two sites, respectively. In the unit burning sub-bituminous coal, the much lower initial concentration of SO(3) estimated to be approximately 1.5 ppmv at the inlet to the SCR was reduced to about 0.8 ppmv across the SCR and to about 0.3 ppmv at the exit of the wet flue gas desulfurization (WFGD). The SO(3) removal efficiency across the WFGD scrubbers at the three sites was generally 35% or less. Reductions in SO(3) across either the APH or the dry electrostatic precipitator (ESP) in units burning high-sulfur bituminous coal were attributed to operating temperatures being below the dew point of SO(3).
在燃煤电站锅炉中，三氧化硫（SO3）的形成可能会对锅炉性能和运行产生负面影响，例如设备结垢和腐蚀、空气预热器（APH）效率降低、烟囱烟度增加以及 PM2.5 的形成。三氧化硫还可能与注入的活性炭结合时与汞竞争。在实验室规模的反应器中进行的测试证实，在 SO3 采样过程中，飞灰与 SO3 之间存在主要干扰。一种改进的 SO3 程序基于惯性过滤采样和 SO3 的选择性冷凝收集，旨在最大程度地消除测量偏差，已应用于三个全尺寸电站锅炉的 SO3 测试中。对于燃烧烟煤的两个机组，在选择性催化还原（SCR）入口处，SO3 浓度从 20 到 25ppm 开始，由于 SO2 催化转化为 SO3，在 SCR 中略有增加，然后在下游其他空气污染物控制设备（APCD）模块中下降到约 5ppm 和 15ppm 在这两个地点，分别。在燃烧次烟煤的机组中，估计在 SCR 入口处的初始 SO3 浓度低得多，约为 1.5ppm，在 SCR 中降低到约 0.8ppm，并在湿法烟气脱硫（WFGD）出口处降低到约 0.3ppm。在三个地点，WFGD 洗涤器的 SO3 去除效率通常在 35%或以下。在燃烧高硫烟煤的机组中，无论在 APH 还是干式静电除尘器（ESP）中，SO3 的减少都归因于运行温度低于 SO3 的露点。
