Electric Power Technology and Environmental Protection

【目的】燃煤烟气中HCl的高效脱除是实现超低排放与废水减量化的关键挑战。石灰石-石膏脱硫是目前较为成熟的烟气 脱硫工艺，但仍然面临着脱硫废水量较多的问题。脱硫废水水量主要取决于系统内的Cl-浓度，从源头降低含氯物质浓度是降 低脱硫系统Cl-浓度进而减少废水排放量的有效途径。为有效降低脱硫系统氯离子浓度并指导脱硫运行，需要开展进一步的研 究。【方法】本文通过对相关文献的系统分析，综述了煤燃烧过程中氯的赋存形态、迁移转化规律及烟气脱氯技术的最新研究进 展。【结果】研究表明，煤中氯以无机氯和有机氯形式存在，燃烧后95%以上转化为气态HCl，其释放特性受煤质、颗粒度及温度 调控。现有脱氯技术中，干法脱氯操作简便但效率受限，湿法脱氯效率超90%，但面临含氯废水处理难题，半干法通过多相反 应实现高效脱氯与废水零排放，但存在喷嘴堵塞，较干法更复杂等技术瓶颈。此外，在脱氯剂的种类及其脱氯机理和效果的对 比基础上，得出钙基脱氯剂成本最低、工业应用最广泛的结果。脱氯过程主要通过物理吸附和化学反应实现，研究表明，HCl 在吸附剂表面通过化学吸附生成CaClOH/CaCl2 ，温度显著影响HCl与其他酸性气体竞争吸附，这是由于HCl凭借动力学优势， 优先占据脱氯剂的碱性位点。【结论】未来需聚焦宽温域和经济型脱氯剂的开发、多污染物协同控制，推动燃煤烟气清洁治理技术升级。

 [Objective] The efficient removal of HCl from coal-fired flue gas is a key challenge to achieve ultra-low emission and wastewater reduction. Limestone-gypsum desulfurization is a relatively mature flue gas desulfurization process at present, but it still faces the problem of large amount of desulfurization wastewater. The amount of desulfurization wastewater mainly depends on the concentration of Cl- in the system. Reducing the concentration of chlorine-containing substances from the source is an effective way to reduce the concentration of Cl- in the desulfurization system and thus reduce the discharge of wastewater. In order to effectively reduce the chloride ion concentration in the desulfurization system and guide the desulfurization operation, further research is needed. [Methods] This paper systematically reviews recent advances in understanding chlorine occurrence forms, migration/ transformation mechanisms during coal combustion, and flue gas dechlorination technologies.[Results] Chlorine in coal exists as both inorganic chlorides and organic chlorine compounds, with over 95% converting to gaseous HCl during combustion. Its release characteristics are governed by coal quality, particle size, and temperature regulation. Among existing dechlorination technologies: dry methods offer operational simplicity but limited efficiency. Wet methods achieve over 90% efficiency but encounter challenges in chlorinated wastewater treatment. Semi-dry methods enable efficient dechlorination and zero wastewater discharge through multiphase reactions, yet face technical bottlenecks such as nozzle clogging and operational complexity compared to dry methods. Furthermore, this work examines various dechlorinating agents and their mechanisms, highlighting calcium-based agents as the most widely adopted industrial option due to cost-effectiveness. The dechlorination process primarily involves physical adsorption and chemical reactions, with experimental studies revealing that HCl preferentially undergoes chemical adsorption on sorbent surfaces to form CaClOH/CaCl2 . Temperature significantly influences competitive adsorption between HCl and other acid gases, where HCl dominates alkaline sites on sorbents through kinetic advantages. [Conclusion] Future research should focus on developing wide-temperature-range and cost-effective dechlorinating agents, along with synergistic control of multiple pollutants, to advance clean coal flue gas treatment technologies.