【摘要】 参照美国标准实验方法(ASTM)中关于汞的OHM等速取样和化学分析法,结合汞的SCEM在线测量技术,利用一多功能流动实验室,对一满负荷运行的100MW煤粉锅炉尾部烟气系统进行了单质汞、氧化态汞和颗粒态汞的现场测试和分析.得到了空气预热器、静电除尘器前后烟气中气态、固态和烟气中总汞的浓度及其分布.结果表明烟气中气态总汞的浓度随温度的降低发生着氧化态汞向颗粒汞的转化.在ESP之后的清洁烟气中,OHM和SCEM方法的测试结果吻合较好;在含颗粒浓度较高的烟气中,2种方法存在较大的偏差,原因在于OHM取样过滤器中形成一定厚度的飞灰.该飞灰颗粒对烟气中气态汞有吸附作用并形成颗粒汞.更多还原

【Abstract】 The in-situ instrumentation technique for measuring mercury and its speciation downstream a utility 100MW pulverized coal (PC) fired boiler system was developed and conducted by the use of the Ontario hydro method (OHM) consistent with American standard test method together with the semi-continuous emissions monitoring (SCEM) system as well as a mobile laboratory for mercury monitoring.The mercury and its speciation concentrations including participate mercury at three locations of before air preheater,before electrostatic precipitator (ESP) and after ESP were measured using the OHM and SCEM methods under normal operation conditions of the boiler system as a result of firing a bituminous coal.The vapor-phase total mercury Hg(VT) concentration declined with the decrease of flue gas temperature because of mercury species transformation from oxidized mercury to particulate mercury as the flue gas moved downstream from the air preheater to the ESP and after the ESP.A good agreement for Hg0,Hg 2+ and Hg(VT) was obtained between the two methods in the ash-free area.But in the dense particle-laden flue gas area,there appeared to be a big bias for mercury speciation owing to dust cake formed in the filter of OHM sampling probe.The particulate affinity to the flue gas mercury and the impacts of sampling condition to accuracy of measure were discussed.更多还原