DEVELOPMENT OF A STANDARD GAS GENERATOR FOR SO3
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摘要: 烟气中三氧化硫(SO3)是固定源可凝结颗粒物的主要气态前体物之一,排入大气环境后可形成“蓝烟”,具有较强的腐蚀性和环境毒性。目前监测烟气中SO3的方法有多种,测量结果差异较大、准确性较难评判,需要对SO3监测设备进行定期标定。但由于SO3反应活性高、难以稳定保存,导致缺少标气,这大大限制了SO3测量的准确性。研制了基于催化氧化SO2生成SO3的便携式标气发生装置,并对其SO3的产率、稳定性及其影响因素进行了评测。结果表明:在填装600 mg钒催化剂(40~60目),持续通入0.1 L/min、1000 ppm(μmol/mol)的SO2气体,催化温度430 ℃的条件下,SO2转化效率为98.5%。用洁净零空气按一定比例对高浓度SO3气体进行稀释混合,可线性输出浓度范围10~1000 ppm的SO3标气,用于SO3监测设备的标定和质控。Abstract: SO3 is one of the most important precursors of condensable particulate matter, and easily transferred into blue flue gas after emission, which causes adverse effects on the atmospheric environment. SO3 is also corrosive and hazardous gas. It is necessary to measure and monitor its concentration in flue gas. At present, the results and accuracy for methods monitoring SO3 in flue gas are difficult to judge and equipments need to be calibrated regularly. However, SO3 is reactive and difficult to store in the tank and must be generated on-site. The lack of ready-made standard gas is the major limiting factor for accurate measurement and monitoring of SO3. In this paper, a SO3 generator was developed based on the principle of catalytic oxidation. Its performance, stability, and influencing factors were evaluated. The conversion ratio was stable at 98.5% on the condition that injecting 1000 ppm(μmol/mol) SO2 at a flow rate of 0.1 L/min, loading 600 mg vanadium catalysts (40~60 mesi), and setting the conversion temperature at 430 ℃. By diluting the highly-concentrated SO3 with clean air of different flow rates, the generator linearly outputs SO3 standard gas in the range of 10 ppm to 1000 ppm, which can be used for calibration of measurement and monitoring of SO3.
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Key words:
- stationary source /
- SO3 /
- standard gas generator /
- calibration /
- condensable particulate matter
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