Huaneng Dalian Power Plant
Suzhou Branch,Xi’an Thermal Power Research Institute Co.,Ltd.
State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology

海水法烟气脱硫(SFGD)系统作为传统石灰石烟气脱硫系统的理想替代品,满足控制燃煤烟气中二氧化硫排放的同时,也可抑制烟气中汞的排放。然而,由于海水的还原性,其汞再排放造成的二次污染一直是全球关注的焦点。本研究通过模拟海水法烟气脱硫废水的曝气过程,研究了pH值、系统温度以及和Cl−浓度等一系列因素对Hg0再排放的影响,旨在确定海水法烟气脱硫系统中汞的SO2−3迁移和转化特性。此外,本研究还考察了四种添加剂,包括沉淀剂(Na2S-无机硫化物、TMT-15-有机硫化物)和氧化剂(NaClO和Fenton试剂)对Hg0再排放的抑制机制。结果表明,S(IV)是促进海水中Hg0再释放的主要因素。当浓度为0.05mmol/L时,超过54%的Hg2+转化为Hg0。同时,海水中SO2−3大量的Cl−、较低的温度和较高的pH值均能抑制Hg0的再释放。四种不同添加剂均能不同程度上抑制Hg0再释放,其中Na2S和TMT-15通过与液相中的Hg2+反应生成难溶于水的沉淀和螯合物来有效抑制Hg2+的还原,NaClO和Fenton试剂主要利用其强氧化性将还原生成的Hg0迅速氧化,使Hg2+稳定在液相中,还能通过氧化液相中的还原性离子,抑制Hg2+的还原。在最佳添加量下,Na2S、TMT-15、NaClO和Fenton试剂对Hg0释放抑制率分别为78.1%、79.9%、84.8%、94.2%。相较于沉淀剂,氧化剂NaClO和Fenton试剂能有效降低曝气强度,对于实际海水脱硫废水海水法烟气脱硫废水曝气过程具有较好的应用前景。

The seawater flue gas desulfurization (SFGD) system, as an ideal alternative to traditional limestone-based systems, effectivelycontrols sulfur dioxide (SO2) emissions from coal-fired flue gas while also suppressing mercury (Hg) emissions. However, the reductivenature of seawater has led to concerns regarding the re-emission of mercury on a global scale. In this study, the aeration process of SFGDwastewater was simulated to investigate the effects of pH, system temperature, and the concentrations of and Cl on the re-emissionof elemental mercury (Hg). The objective of this study was to elucidate the migration and transformation characteristics of mercury inSFGD systems. Furthermore, the study investigated the suppression mechanisms of four additives: two precipitants (Na2S, an inorganicsulfide, and TMT-15, an organic sulfide) and two oxidants (NaClO and Fenton reagent). The results demonstrated that S(IV) was theprimary factor promoting Hg0 re-emission, with over 54% of Hg being reduced to Hg at an concentration of 0.05 mmol/L. Concurrently, elevated concentrations of Cl, low temperatures, and heightened pH levels exhibited a substantial inhibitory effect on Hgre-emission. All four additives effectively inhibited Hg re-emission through different mechanisms. Na2S and TMT-15 reacted with Hg inthe liquid phase to form water-insoluble precipitates and chelates, thereby preventing reduction to Hg. NaClO and Fenton reagentsuppressed Hg re-emission by rapidly oxidizing Hg back to Hg and stabilizing it in the liquid phase. They also inhibited Hg reductionby oxidizing reductive ions in the solution. At optimal dosages, the suppression efficiencies of Na2S, TMT-15, NaClO, and Fenton reagentwere 78.1%, 79.9%, 84.8%, and 94.2%, respectively. Compared to precipitants, oxidants such as NaClO and Fenton reagent significantlyreduced the required aeration intensity, demonstrating excellent potential for application in the aeration processes of SFGD wastewatertreatment.

华能集团科技项目资助项目(2022-KJ08-181)

赵宏,雷嗣远,李成宝,等.海水法烟气脱硫系统中汞再释放规律及其稳定化研究[J].洁净煤技术,2025,31(1):173−180.

ZHAO Hong,LEI Siyuan,LI Chengbao,et al. Study on the re-emission and stabilization of mercury in seawater flue gasdesulfurization wastewater[J].Clean Coal Technology,2025,31(1):173−180.