SO3采样技术改进及烟气处理设备SO3脱除能力测试

燃煤烟气中SO₃由于其特有的化学性质，一直是国内外燃煤电厂污染物测试的难点之一。参照国内应用广泛的SO₃控制冷凝法，自制了一套SO₃采样系统，在综合考虑烟气SO₃采样过程中的各种影响因素后，通过试验模拟，确定了SO₃控制冷凝法采样系统最佳蛇形管内径、圈径和圈数，以及采样管、过滤器和循环水浴的伴热温度控制，从而提高了SO₃的捕集效率。利用该SO₃采样系统对烟气进行采样，测试燃煤锅炉烟气处理设备对SO₃的脱除能力，分析其影响因素及捕集机理。结果显示：SCR脱硝催化剂对SO₂具有一定的催化作用，且随烟气温度的升高，SO₂/SO₃转化率升高；对于SO₃的脱除效率（各设备进出口浓度对比），干式除尘设备可达80%以上，湿法脱硫设备为35%~40%；湿式电除尘器为70%~75%。

Improvement of SO3 Sampling Technology and SO3 Removal Capability Testing of Flue Gas Treatment Equipment

Due to its unique chemical properties, SO₃ in coal-fired flue gas has been one of the difficult parts in pollutant testing in coal-fired power plants both at home and abroad. In this article, the SO₃ testing system is developed by utilizing the widely used control-condensation method and taking various factors into consideration during the sampling process. The optimal inner diameter, ring diameter and the number of rings of snake-shaped tube in SO₃ controlled condensation sampling system are determined through experimental simulation as well as the sampling tubes, the temperature control of filter and circulating water bath to improve the capture efficiency of SO₃. This SO₃ sampling system has been used to test the removal capability of the flue gas treatment equipment in the coal-fired boiler. The influencing factors and the trapping mechanism on SO₃ by sampling the flue gas are also analyzed. It is showed that SCR catalyst had some catalytic effects on SO₂, and the conversion rate of SO₂/SO₃ increases with higher flue gas temperature. As for the removal efficiency of SO₃, based on the comparison results of the inlet and outlet concentration between each equipment, the dry dedusting equipment can reach more than 80%, while the wet desulphurization equipment is 35%~40% and the wet electrostatic precipitator is 70%~75%.