燃煤烟气重金属多污染物超低排放过程协同优化研究

Under the requirement in heavy metal elements emission reduction, optimized coal-fired flue gas ultra-low emission system with heavy metal elements emission synergistic control are highly desired. On the basis of the available common pollutants ultra-low emission control technology and effective heavy metals elements removal technology, ultra-low emission system model is established. The exe-economic integration and optimization theory with heavy metals emission control for ultra-low emission system is established to solve multi-objective optimization problems. In order to achieve the synergistic optimization of the ultra-low emission system and to guide the multiple pollutants synergistic control technical routes selection, the change of material flow, energy flow and economic flow with heavy metals transfer is investigated, and the emission potential, energy efficiency, and costs of the whole ultra-low emission system are evaluated. Furthermore, exploration of the interaction mechanism between heavy metal control technology and common pollutants ultra-low emission control technology and analysis of the effects of coal composition and load fluctuation on the performance of the integrated ultra-low emission system with heavy metals control will be performed. The obtained results will provide data support and theoretical direction for the advanced ultra-low emissions coal- fired power system.

针对燃煤烟气多污染物超低排放过程整体优化难题和重金属协同控制的要求，根据现有常规污染物超低排放技术和汞砷等重金属脱除技术，本项目建立满足烟气重金属多污染物超低排放的系统工艺过程模型，以及污染控制与㶲经济集成优化理论方法，揭示重金属等多污染物生成转化迁移过程中能流、经济流的变化规律，评估分析烟气重金属多污染物超低排放一体化系统在能效、污染物减排、经济成本等多方面性能，提出基于“协同控制”理念的全过程烟气重金属多污染物控制技术路线选择策略方法。探究烟气重金属控制技术与烟气常规污染物超低排放控制技术的相互作用机理，分析煤质组成、负荷频繁波动的情况对燃煤烟气重金属多污染物超低排放一体化系统性能影响规律。可为新型多污染物协同控制的燃煤烟气污染物超低排放系统提供理论依据和技术支持。

燃煤烟气污染物超低排放改造显著降低了二氧化硫、氮氧化物、粉尘排放也一定程度上降低了重金属排放。然而如何发挥超低排放工艺协同脱除重金属以满足燃煤电厂重金属排放控制要求缺乏深入研究。本项目通过分析煤炭燃烧过程重金属形态分布特征，明确了影响烟气中重金属形态关键因素，基于燃煤烟气重金属汞多污染物协同控制机理，建立了燃煤烟气污染控制过程汞转化迁移模型和燃煤发电系统全过程模型，系统分析了硝硫尘汞等污染物转化迁移过程污染物排放浓度变化特征、能耗和环保成本，获得了烟气污染物控制过程硝硫尘汞的浓度变化规律和重金属汞迁移分布规律，得到了燃煤超低排放发电系统㶲流分布和㶲损规律，探讨了煤质和负荷变化对燃煤超低排放发电系统性能影响规律。研究发现相对于燃烧气氛，燃烧温度对燃烧过程砷硒汞重金属形态影响显著。烟气污染控制系统出口的烟气硝硫尘汞排放浓度可满足超低排放要求，重金属汞主要富集在飞灰中。湿法脱硫单元能耗高，㶲损失大，㶲效率低，单位供电㶲经济成本增长幅度大。本项目的研究构建了重金属汞多污染物协同控制模型，可为燃煤烟气超低排放系统多污染物的协同脱除效果和排放浓度分析提供理论依据和技术支持。