Coal-fired power plant is one of the important emission sources of gaseous pollutants such as sulfur dioxide and nitrogen oxides.After Ultra low emission transformation, the condition of flue gas was in conditions of low temperature and high humidity sometimes, which bringing challenges to the test of gaseous pollutantsconcentration.A comparative study onsulfur dioxide and nitrogen oxides emission concentration was carried out in a typical test environment of low temperature and high humidity.The measurement uncertainties of the results of different methods were evaluated based on a bottom-up approach, according to the GUM published by ISO.The results showed that gaseous pollutant concentration was significantly reduced after ultra-low emission transformation.In low temperature and high humidity environment, the ultra-low concentrations of gaseous pollutants could be test accurately by selecting suitable testing equipment and controlling operation procedure.To reduce the measurement uncertainty, it was recommended to test sulfur dioxide by ultraviolet absorption method, and nitrogen oxides by chemiluminescence method.To strengthen the procurement and management of standard gas also helped to reduce the uncertainty of measurement.The implementation of strict quality control (QC) measures would effectively improve the accuracy of measurement.%燃煤电厂是SO2及NOx等气态污染物的重要排放源之一."超低排放"后,部分工况下烟气处于低温高湿条件,对测试工作带来挑战.选择某典型低温高湿的测试环境,比对研究了不同烟气气态污染物测试方法,并依据GUM标准测量不确定度分析手段,评估了不同方法测量结果的测量不确定度.结果表明:超低排放改造后,气态污染物浓度大幅降低;低温高湿环境下,选择适宜的测试仪器,严格操作程序,可实现超低浓度气态污染物的准确测试;为降低测量不确定度,SO2测试推荐采用紫外吸收法,NOx测试推荐采用化学发光法;强化标气采购管理亦有助于降低测量不确定度.实施严格质量控制措施将有效提高测量准确性.
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