摘要
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。通过模拟海水法烟气脱硫废水的曝气过程,研究了pH、系统温度以及SO_(3)^(2-)和Cl^(−)浓度等一系列因素对Hg^(0)再排放的影响,旨在确定海水法烟气脱硫系统中汞的迁移和转化特性。此外,还考察了4种添加剂,包括沉淀剂(Na_(2)S-无机硫化物、TMT-15-有机硫化物)和氧化剂(NaClO和Fenton试剂)对Hg^(0)再排放的抑制机制。结果表明:S(IV)是促进海水中Hg^(0)再释放的主要因素。当SO_(3)^(2-)浓度为0.05 mmol/L时,超过54%的Hg^(2+)转化为Hg^(0)。同时,海水中大量的Cl^(−)、较低的温度和较高的pH均能抑制Hg^(0)的再释放。4种不同添加剂均能不同程度上抑制Hg^(0)再释放,其中Na_(2)S和TMT-15通过与液相中的Hg^(2+)反应生成难溶于水的沉淀和螯合物来有效抑制Hg^(2+)的还原,NaClO和Fenton试剂主要利用其强氧化性将还原生成的Hg^(0)迅速氧化,使Hg^(2+)稳定在液相中,还能通过氧化液相中的还原性离子,抑制Hg^(2+)的还原。在最佳添加量下,Na_(2)S、TMT-15、NaClO和Fenton试剂对Hg^(0)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,effectively controls sulfur dioxide(SO2)emissions from coal-fired flue gas while also suppressing mercury(Hg)emissions.However,the reductive nature of seawater has led to concerns regarding the re-emission of mercury on a global scale.In this study,the aeration process of SFGD wastewater was simulated to investigate the effects of pH,system temperature,and the concentrations of SO_(3)^(2-)and Cl^(−)on the re-emission of elemental mercury(Hg^(0)).The objective of this study was to elucidate the migration and transformation characteristics of mercury in SFGD systems.Furthermore,the study investigated the suppression mechanisms of four additives:two precipitants(Na_(2)S,an inorganic sulfide,and TMT-15,an organic sulfide)and two oxidants(NaClO and Fenton reagent).The results demonstrated that S(IV)was the primary factor promoting Hg^(0)re-emission,with over 54%of Hg^(2+)being reduced to Hg^(0)at an SO_(3)^(2-)concentration of 0.05 mmol/L.Concurrently,elevated concentrations of Cl^(−),low temperatures,and heightened pH levels exhibited a substantial inhibitory effect on Hg^(0)re-emission.All four additives effectively inhibited Hg^(0)re-emission through different mechanisms.Na_(2)S and TMT-15 reacted with Hg^(2+)in the liquid phase to form water-insoluble precipitates and chelates,thereby preventing reduction to Hg^(0).NaClO and Fenton reagent suppressed Hg^(0)re-emission by rapidly oxidizing Hg^(0)back to Hg^(2+)and stabilizing it in the liquid phase.They also inhibited Hg^(2+)reduction by oxidizing reductive ions in the solution.At optimal dosages,the suppression efficiencies of Na_(2)S,TMT-15,NaClO,and Fenton reagent were 78.1%,79.9%,84.8%,and 94.2%,respectively.Compared to precipitants,oxidants such as NaClO and Fenton reagent significantly reduced the required aeration intensity,demonstrating excellent potential for application in the aeration processes of SFGD wastewater treatment.
作者
赵宏
雷嗣远
李成宝
唐轲
郭浩
武伟
马宝林
郑晗
关剑
徐仁博
罗通达
孙路石
ZHAO Hong;LEI Siyuan;LI Chengbao;TANG Ke;GUO Hao;WU Wei;MA Baolin;ZHENG Han;GUAN Jian;XU Renbo;LUO Tongda;SUN Lushi(Huaneng Dalian Power Plant,Dalian 116033,China;Suzhou Branch,Xi’an Thermal Power Research Institute Co.,Ltd.,Suzhou 215153,China;State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology,Wuhan 430074,China)
出处
《洁净煤技术》
北大核心
2025年第1期201-208,共8页
Clean Coal Technology
基金
华能集团科技项目资助项目(2022-KJ08-181)。
关键词
海水法烟气脱硫废水
汞
再释放
添加剂
稳定化
seawater flue gas desulfurization wastewater
mercury
re-emission
additive
stabilization
作者简介
赵宏(1970-),男,辽宁大连人,高级工程师。E-mail:zhc120689@sina.com;通讯作者:孙路石(1969-),男,湖北武汉人,教授。E-mail:sunlushi@mail.hust.edu.cn。
