采用Aspen Plus软件对烟气污染控制单元进行模拟，以电厂实际运行数据验证模型的正确性，建模过程中考虑SO3转化和烟气中烟尘浓度的变化，并通过影响因素分析考察操作参数对污染物脱除效果的影响。结果表明，在选择性催化还原(SCR)脱硝过程中，部分SO2转化为SO3，除尘过程中飞灰对SO3有吸附作用，脱硫塔与除尘器对SO3和灰分脱除具有协同作用；SCR脱硝过程的最佳氨氮摩尔比范围为0.8~1.0，氨氮比低于0.6、反应温度低于400℃时，SO3浓度呈上升趋势；湿法脱硫过程中，入口烟气温度上升会阻碍SO2吸收和SO3去除；湿式除尘过程中，除尘效率随温度升高而降低，随气体流速增加先升高后降低，最佳流速为0.8~1.2 m/s。
The Aspen Plus software was used to simulate the flue gas pollution control units and the correctness of the model was verified using the actual operation data of one power plant. In the modeling process, in addition to the removal of conventional flue gas pollutants, the SO3 conversion and the change of dust concentration in the flue gas were taken into account. Furthermore, the effects of operating parameters on the pollutants removal efficiency were examined through influencing factors analysis. In this simulation model, the flue gas entered the SCR (Selective Catalytic Reduction) de-nitrification device firstly, followed by electrostatic precipitator, limestone-gypsum desulfurization, and finally went through the wet electrostatic precipitator process, achieving the ultra-low emission standards before discharges into the atmosphere. In the SCR denitration process, SO2 was oxidized to SO3 due to the catalyst. Ash had an adsorption effect on SO3 during the ESP (Eletrostatic Precipitator) process, and the desulfurization tower and the wet electrostatic precipitator process had a synergistic removal effect on SO3 and ash. To accurate the simulation results, all these details mentioned above were simulated in this study. The influencing factors analysis showed that when the molar ratio of ammonia to nitrogen was lower than 0.6 and the reaction temperature was lower than 400℃, the concentration of SO3 tended to rise. With the increase of the molar ratio of ammonia to nitrogen and temperature, part of SO3 would react with excess ammonia forming NH4HSO4 during the de-nitrification process, which could in turn caused blockage of the air pre-heater. Comprehensive analysis showed that the optimal ammonia?nitrogen molar ratio was in the range of 0.8~1.0. During the desulfurization process, the increase of the absorption liquid flux and the decrease of the inlet flue gas temperature were favorable for the removal of SO3. During the wet dust removal process, when the flow rate of the flue gas was in the range of 0.8~1.2 m/s, the removal of soot was facilitated.
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